IPAC2013 - List of Keywords (scattering)

Paper	Title	Other Keywords	Page
MOPEA012	Lifetime Studies at Metrology Light Source and ANKA	cavity, optics, electron, septum	88
	T. Goetsch, J. Feikes, M. Ries, G. Wüstefeld HZB, Berlin, Germany A.-S. Müller KIT, Karlsruhe, Germany
	The Metrology Light Source (MLS), situated in Berlin (Germany) is an electron storage ring operating from 10⁵ MeV to 630 MeV and is serving as the national primary radiation source standard from the near infrared to the vacuum ultraviolet spectral region. In its standard user mode, the lifetime is dominated by the Touschek effect. Measurements and analysis of the Touschek lifetime as a function of beam current and RF-Voltage will be presented and compared to measurements done at the ANKA electron storage ring (Karlsruhe, Germany) which operates at 0.5 to 2.5 GeV. R. Klein et al., Phys. Rev. ST-AB 11, 110701 (2008) ** A.-S. Müller et al., Energy Calibration Of The ANKA Storage Ring, In Proceedings of EPAC 2004

MOPEA017	Electron Cooling of Heavy Ions Interacting with Internal Target at HESR of FAIR	electron, target, emittance, ion	103
	T. Katayama, M. Steck GSI, Darmstadt, Germany R. Maier, D. Prasuhn, H. Stockhorst FZJ, Jülich, Germany
	The High Energy Storage Ring (HESR) is designed and optimized to accumulate and store the anti-proton beam for the internal target experiment. The recent demand of atomic physics has impacted to use the HESR facility also as the storage ring of bare heavy ions. In this concept the bare heavy ions are injected at 740 MeV/u from the Collector Ring where the ions are well stochastically cooled to be matched with HESR ring acceptance. In the HESR the 2 MeV electron cooler is prepared with the maximal electron current of 3 A and the cooling length of 2.7 m. The electron cooling process of typically ²³⁸U⁹²⁺ beam is simulated for the Hydogen and Xe internal target with simultaneous use of barrier voltage to compensate the mean energy loss caused by the interaction with internal target. In the present report the detailed simulation results of 6D phase space obtained by the particle tracking code are precisely discussed.

MOPEA022	Beam Profile Measurement for High Intensity Electron Beams	electron, laser, photon, diagnostics	118
	T. Weilbach, K. Aulenbacher, M.W. Bruker HIM, Mainz, Germany K. Aulenbacher IKP, Mainz, Germany
	Recent developments in the field of high intensity electron beams in the regime below 10 MeV, e.g. energy recovery linacs or magnetized high energy electron coolers, have led to special demands on the beam diagnostics. Since commonly used diagnostic tools like synchrotron radiation and scintillation screens are ineffective or not able to withstand the beam power without being damaged, new methods are needed. Hence a beam profile measurement system based on beam induced fluorescence (BIF) was built. This quite simple system images the light generated by the interaction of the beam with the residual gas onto a PMT. A more elaborated system, the Thomson Laser Scanner (TLS) - the non-relativistic version of the Laser Wire Scanner - is proposed as a method for non-invasive measurement of all phase space components, especially in the injector and merger parts of an ERL. Both methods are implemented in a 100 keV photo gun. Beam profile measurements with BIF as well as first results of the TLS will be presented.

MOPEA037	Theoretical Study on the Two-stage Collimation System Design	collimation, vacuum, simulation, space-charge	157
	N. Wang, S. Wang IHEP, Beijing, People's Republic of China
	Two-stage collimation system is widely used in high intensity machines to localize the beam losses in a restricted area. In the well-known theory, the optical constrains are expressed by the betatronic phase advances between primary and secondary collimators, which minimize the size of the secondary halo. In this paper, the physical model is developed considering the characteristic of the space charge dominated beams. Numerical studied are performed to verify the theoretical model.

MOPEA057	Studies of the Electron Beam Lifetime at MAX III	cavity, electron, vacuum, emittance	208
	A. Hansson, Å. Andersson, J. Breunlin, G. Skripka, E.J. Wallén MAX-lab, Lund, Sweden
	MAX III is a 700 MeV 3rd generation synchrotron light source located at the MAX IV Laboratory in Sweden. The lifetime in the storage ring is lower than originally envisaged. From vertical scraper measurements the lifetime contributions at 300 mA stored current have been determined. The lifetime is mainly limited by the Touschek lifetime, which is lower than its design value, whereas the vacuum lifetime is close to the expected value. The low Touschek lifetime is explained by a lower than design emittance ratio and momentum acceptance in the storage ring.

MOPEA074	Lattice Studies for a Potential Soft X-ray Diffraction Limited Upgrade of the ALS	lattice, emittance, brightness, injection	258
	C. Steier, J.M. Byrd, R.W. Falcone, S.D. Kevan, D. Robin, C. Sun, H. Tarawneh, W. Wan LBNL, Berkeley, California, USA
	Funding: The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The Advanced Light Source (ALS) at Berkeley Lab has seen many upgrades over the years, keeping it one of the brightest sources for soft x-rays worldwide. Recent developments in magnet technology and lattice design (multi bend achromat lattices) appear to open the door for very large further increases in brightness, particularly by reducing the horizontal emittance, even within the space constraints of the existing tunnel. Initial studies yielded candidate lattices which approach the soft x-ray diffraction limit (around 2 keV) in both planes within the ALS footprint.

MOPFI032	Electron Emission of the Stripping Foil and Collimation System for CSNS/RCS	electron, proton, collimation, injection	354
	M.Y. Huang, Y.D. Liu, N. Wang, S. Wang IHEP, Beijing, People's Republic of China
	For the Rapid Cycling Synchrotron of the China Spallation Neutron Source (CSNS/RCS), the electron emission plays an important role in the accelerator limitation. The interactions between the proton beam and the stripping foil were studied, and the electron scattering processes were simulated by the ORBIT and FLUKA codes. Then, the electron energy distribution and the electron yielding rate can be given. Furthermore, the interactions between the proton beam and the collimation system were studied, and the electron scattering processes were simulated. Then, the energy distribution of the primary electron emission can be given and the yielding rate of the primary electron can be obtained.

MOPFI081	Correlating Structure and Function - In situ X-ray Analysis of High QE Alkali-antimonide Photocathodes	cathode, emittance, controls, vacuum	464
	J. Smedley, K. Attenkofer, S.G. Schubert BNL, Upton, Long Island, New York, USA I. Ben-Zvi, X. Liang, E.M. Muller, M. Ruiz-Osés Stony Brook University, Stony Brook, USA T. Forrest, H.A. Padmore, T. Vecchione, J.J. Wong LBNL, Berkeley, California, USA J. Xie ANL, Argonne, USA
	Funding: The authors wish to acknowledge the support of the US DOE, under Contract No. KC0407-ALSJNT-I0013, DE-AC02-98CH10886 and DE-SC0005713. Use of CHESS is supported by NSF award DMR-0936384. Alkali antimonide photocathodes have high quantum efficiency and low emittance when illuminated by visible light, and are thought to be well suited for use in high-brightness photoinjectors of 4th generation light sources. Here we report on the growth of multi-alkali K2CsSb cathodes on [100] silicon substrates measured using in-situ X-ray diffraction (XRD) and X-ray reflection (XRR). Correlations between cathode structure and growth parameters and the resulting quantum efficiency (QE) are also explored. The best cathodes have a QE at 532 nm in excess of 6% and are structurally textured K2CsSb with grain sizes in excess of 20 nm. In an attempt to reduce the complexity of the current growth methodology we are also making alkali antimonides in parallel via the reaction of bulk materials in an inert environment. This approach has the advantage that the desired stoichiometry can be obtained exactly. Initial diffraction results from prepared bulk materials are promising and show the formation of well reacted K3Sb. In the future we intend to transfer this material to smooth thin photocathode films by either sputtering or pulsed laser deposition.

MOPME004	Fast Luminosity Monitoring using Diamond Sensors for Super Flavour Factories	luminosity, photon, electron, positron	473
	C. Rimbault, P. Bambade LAL, Orsay, France
	Super flavour factories aim to reach very high luminosities thanks to a new concept whereby the ultra-low emittance beams collide with a large crossing angle. Fast luminosity measurements are needed as input to luminosity optimization and feedback in the presence of dynamic imperfections. The required small relative precision can be reached exploiting the very large cross section of the radiative Bhabha process at zero photon scattering angle. The instrumental technique selected to sustain the large particle fluxes is based on diamond sensors to be positioned via moveable stages immediately outside the beam pipe, at locations chosen to minimize the contamination from other particle loss mechanisms.

MOPME038	A New Theoretical Design of BLM System for HLS II	electron, vacuum, monitoring, emittance	553
	Y.K. Chen, L.J. He, J. Li, W. Li, Y. Li USTC/NSRL, Hefei, Anhui, People's Republic of China
	Beam loss monitoring (BLM) system has been commonly used to detect the vacuum leakage. The existing BLM system for Hefei Light Source (HLS) was built in 2000. It played an important role in analyzing beam loss distribution and regulating the machine operation parameters. Recently, HLS is being upgraded to HLS II. The emittance will be decreased to increase the brilliance of synchrotron radiation. The Touschek lifetime will be much shorter than before, and dominate the total beam lifetime. It is necessary to redesign the BLM system for HLS II. The most important part of this work is to find a better method of monitoring Touschek lifetime by BLM system while keeping its general functions. According to the results of our research, a preliminary theoretical design for the new BLM system is proposed in this paper. This new system will play an important role in the storage ring commissioning, troubleshooting, and beam lifetime studying.

MOPME065	Approximate Method of Calculation of a Bunch Radiation in Presence of Complex Dielectric Object	radiation, vacuum, optics, diagnostics	625
	A.V. Tyukhtin, E.S. Belonogaya, S.N. Galyamin Saint-Petersburg State University, Russia
	Funding: Work supported by the Grant of President of Russian Federation, Russian Foundation for Basic Research, and the Dmitry Zimin "Dynasty" Foundation. Cherenkov radiation is widely used for detection of charged particles and can be also applied for particle bunch diagnostics. As a rule, dielectric objects applied for these goals have complex forms. Therefore development of methods of calculation of bunch radiation in presence of complex dielectric objects is now of a great interest. The approximate method developed by us allows to take into account influence of the object boundaries closed to the charge trajectory as well as "external" boundaries of the object. The case of the charge crossing a dielectric plate was considered as a test problem. The exact solution of this problem is in a good agreement with our approximate solution. Next, the cases of more complex objects were analyzed. One of them is a dielectric cone with a vacuum channel. Particularly, it was shown that radiation can be convergent under certain conditions, that is the field outside the cone can be more intensive than on the cone boundary. Radiation of the bunch in the case of dielectric prism was considered as well. A.P. Potylitsyn, Yu.A. Popov, L.G. Sukhikh, G.A. Naumenko, M.V. Shevelev, Journal of Physics: Conference Series 236 (2010) 012025.

MOPWA036	GEM Detectors for the Transverse Profile Measurement of Low Energy Antiprotons and High Energy Hadrons	antiproton, electron, hadron, cathode	747
	J. Spanggaard, P. Carriere, S.C. Duarte Pinto, G. Tranquille CERN, Geneva, Switzerland
	Gas Electron Multipliers (GEM) are finding more and more applications in beam instrumentation. Gas Electron Multiplication is a very similar physical phenomenon to that which occurs in Multi Wire Proportional Chambers (MWPC), but for small profile monitors GEMs are much more cost effective to produce and maintain. In 2012, all Multi-Wire Proportional Chambers in the experimental areas of the Antiproton Decelerator at CERN were successfully replaced by Gas Electron Multipliers. This paper describes the choice of detector and reports on the commissioning of 20 GEM detectors for transverse profile measurement on low energy antiproton beams (5.3 MeV, equal to 100 MeV/c). It will also cover the development of, and first results from, a new 200x200 mm GEM detector for profiling the high energy muon beam (172 GeV/c) delivered to the COMPASS experiment and discuss the outlook for replacing all Multi-Wire Proportional Chambers in the CERN experimental areas by GEM based monitors.

MOPWA059	Beam Emittance Measurements and Beam Transport Optimization at the Clatterbridge Cancer Centre	quadrupole, emittance, proton, cyclotron	810
	T. Cybulski, O. Karamyshev, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom A. Degiovanni TERA, Novara, Italy A. Kacperek, B. Marsland, I. Taylor, A. Wray The Douglas Cyclotron, The Clatterbridge Cancer Centre NHS Foundation Trust, Wirral, United Kingdom O. Karamyshev, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: Cockcroft Institute, Daresbury, Warrington, WA4 4AD, United Kingdom University of Liverpool, Liverpool, United Kingdom The QUASAR Group is preparing tests of the high energy physics LHCb VELO detector as a non–invasive online dose monitor at the 60 MeV proton therapy beam at the Clatterbridge Cancer Centre (CCC), UK. The proposed method relies on the cross-correlation between the beam halo signal as measured by VELO and the dose delivered to the patient, linked via the absolute intensity of the beam. In order to estimate the expected halo signal and the total beam intensity, studies into proton beam transport through the whole CCC beam line have been carried out. This required the measurement of beam emittance at several positions of the beam delivery system. Quadrupole scans have been realized using a CsI (Tl) scintillating screen in combination with an 8 bit, 13 Mpixel CCD camera. In this contribution, results from measurements are presented and include a discussion of the effects from dispersion in the beam. Experimental data are compared against earlier measurements performed in 1998 and are used as a basis for suggestions targeting an overall optimization of beam transport at CCC. * Assessing the Suitability of a Medical Cyclotron as an Injector for an Energy Upgrade, J. A. Clarke et all , CLRC Daresbury Laboratory, Warrington, UK

MOPWO038	Cleaning Inefficiency of the LHC Collimation System during the Energy Ramp: Simulations and Measurements	simulation, collimation, proton, injection	975
	E. Quaranta, R. Bruce, L. Lari, D. Mirarchi, S. Redaelli, A. Rossi, B. Salvachua, G. Valentino CERN, Geneva, Switzerland L. Lari IFIC, Valencia, Spain D. Mirarchi The Imperial College of Science, Technology and Medicine, London, United Kingdom G. Valentino University of Malta, Information and Communication Technology, Msida, Malta
	The cleaning inefficiency of the LHC collimation system has already been studied in detail at injection and top energy (450 GeV and 4 TeV respectively). In this paper the results are presented for the cleaning inefficiency at intermediate energies, simulated using the SixTrack code. The first comparisons with measured provoked losses are discussed. This study helps in benchmarking the energy dependence of the simulated inefficiency and is thus important for the extrapolation to future operation at higher energies.

TUODB103	Recent Results from CesrTA Intrabeam Scattering Investigations	emittance, coupling, simulation, damping	1126
	M. P. Ehrlichman, A. Chatterjee, W. Hartung, D.P. Peterson, N.T. Rider, D. L. Rubin, D. Sagan, J.P. Shanks, S. Wang CLASSE, Ithaca, New York, USA
	Funding: This research was supported by NSF and DOE contracts PHY-0734867, PHY-1002467, PHYS-1068662, DE-FC02-08ER41538, DE-SC0006505. Manifestation of intrabeam scattering (IBS) in an electron/positron storage ring depends on the radiation damping time in two ways. First, the beam size is the equilibrium of the IBS growth rate in each of the three degrees of freedom and corresponding damping rates. Second, scattering events that occur less frequently than order once per damping time contribute to non-Gaussian tails that are invisible to our beam size monitors. The tail cut procedure excludes these relatively rare events in the calculation of equilibrium beam size. In machines with short damping times, the tail cut significantly reduces the effective IBS growth rate. At CesrTA, we measure the dependence of beam size on bunch charge in IBS-dominated beams. We vary the vertical emittance using a closed optics bump that increases the vertical dispersion and transverse coupling in the wiggler regions. Measurements are taken at both 2.1 and 2.3 GeV. Here we report the results of these experiments and compare those results to theory.
	Slides TUODB103 [1.221 MB]

TUPFI005	Synchrotron-Radiation Photon Distribution for Highest Energy Circular Colliders	photon, radiation, vacuum, electron	1340
	G.H.I. Maury Cuna CINVESTAV, Mérida, Mexico G. Dugan, D. Sagan CLASSE, Ithaca, New York, USA F. Zimmermann CERN, Geneva, Switzerland
	Funding: Acknowledgements to CINVESTAV, CERN and EPLANET project. At high energies, beam-induced synchrotron radiation is an important source of heating, beam-related vacuum pressure increase, and primary photoelectrons, which can give rise to an electron cloud. The photon distribution along the beam pipe wall is a key input to codes such as ECLOUD and PyECLOUD, which model the electron cloud build-up. For future high-energy colliders, like TLEP or SHE-LHC, photon stops and antechambers are considered in order to facilitate cooling and vacuum pressure control. We use the Synrad3D code developed at Cornell to simulate the photon distribution for the LHC.

TUPFI037	Collimation Down to 2 Sigma in Special Physics Runs in the LHC	proton, background, luminosity, emittance	1427
	H. Burkhardt, S. Jakobsen, S. Redaelli, B. Salvachua, G. Valentino CERN, Geneva, Switzerland
	We report on observations with collimation very close to the beam. Primary collimators were moved in small steps down to 2 σ from the beam axis to allow for measurements of very forward proton scattering in special high-beta runs in the LHC. We studied the reduction in intensity as a function of collimator position which provides information about the halo shape. After scraping at 2 σ, collimators were retracted to 2.5 σ. This allowed for measurements of very forward proton-proton scattering with roman pot detectors at 3 σ from the beam axis at acceptable background levels for about an hour. Good background conditions were restored by another scraping with primary collimators at 2 σ. Beam lifetimes and halo repopulation times were found to be sufficiently long to allow for several hours of data taking between scraping in a single LHC fill.

TUPFI078	Measurement of the Total Cross Section of Uranium-uranium Collisions at a Center-of-mass Energy of 192.8 GeV per Nucleon-pair	ion, beam-losses, luminosity, emittance	1529
	W. Fischer, A.J. Baltz, M. Blaskiewicz, K.A. Drees, D.M. Gassner, Y. Luo, M.G. Minty, P. Thieberger, M. Wilinski BNL, Upton, Long Island, New York, USA I.A. Pshenichnov RAS/INR, Moscow, Russia
	Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy. Heavy ion cross sections totaling several hundred barns have been calculated previously for the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). These total cross sections are more than an order of magnitude larger than the geometric ion-ion cross sections, primarily due to Bound-Free Pair Production (BFPP) and Electro-Magnetic Dissociation (EMD). Apart from a general interest in verifying the calculations experimentally, an accurate prediction of the losses created in the heavy ion collisions is of practical interest for the LHC, where some collision products are lost in cryogenically cooled magnets and have the potential to quench these magnets. In the 2012 RHIC run uranium ions collided with each other at a center-of-mass energy of 192.8 GeV per nucleon-pair with nearly all beam losses due to collisions. This allows for the measurement of the total cross section and a comparison with calculations.

TUPME007	Beam Lifetime in Low Emittance Rings	simulation, lattice, background, factory	1574
	M. Boscolo INFN/LNF, Frascati (Roma), Italy
	In this paper I will review the main effects in low emittance rings that determine the beam lifetime by causing beam losses along the ring. As an example, the case for a B-factory based on the crab-waist collision scheme has been studied. During the machine design all the effects that determine the beam lifetime and induce backgrounds in the detector have been analyzed in details. The crab-waist scheme provides an higher luminosity, but at the same time it induces higher beam losses at the final focus. For this reason single beam effects such as Touschek and beam-gas scattering have been studied in details, by means of a macroparticle tracking code developed for this purpose. Also Radiative Bhabha scattering, that is the dominant effect to lifetime and backgrounds has been studied with the same technique to check possible multiturn losses at IR. An efficient collimation system has been designed to intercept scattered particles that would be lost in the IR in both the horizontal and the vertical plane. Recently, the Touschek tracking simulation code has been implemented to study the lifetime behavior for extremely low-emittance rings. M. Boscolo and P. Raimondi, “Monte Carlo simulation for the Touschek effect with the crab-waist scheme”, Phys. Rev. ST-AB 15 104201 (2012)

TUPME013	Coherent Thomson Scattering using Beam Echo	laser, electron, undulator, radiation	1592
	K. Ohmi, S. Kamada KEK, Ibaraki, Japan H. Fares Kanazawa University, Kanazawa, Japan
	Longitudinal phase space of the beam is modulated by laser interacting in undulators. The beam can have higher frequency component using the beam echo than than the laser as dicussed by G. Stupakov et al. The modulated beam has a potential to emit coherent radiation with the wave length. We evaluate coherent short wave length (~nm) and/or short pulse (attosec) light source using the beam echo in a low energy accelerator ~100MeV.

TUPME015	Proposal of Polarized Gamma-ray Source for ILC Based on CSR Inverse Compton Scattering	electron, cavity, positron, laser	1598
	M. Shimada, K. Yokoya KEK, Ibaraki, Japan R. Hajima JAEA, Ibaraki-ken, Japan M. Tecimer University of Hawaii at Manoa, Honolulu, USA
	The positron source of International Linear Collider (ILC) requires a circular polarized gamma-ray with a flux more than 10¹⁶ phs./s and a helical undulator-based gamma-ray source is proposed in the baseline design. Although the undulator scheme is technically feasible, it is not easy for a stand-alone operation because of the required electron energy, ~ 150GeV. In this paper, we propose an alternative method, the inverse Compton scattering with a high-power mid-infrared optical pulse generated from coherent synchrotron radiation (CSR). To achieve the high flux gamma-ray, CSR with a few MHz is stacked in a high-finesse optical cavity made of a photonic crystal. In the proposed scheme, a stand-alone operation is feasible because the electron energy is less than 10GeV.

TUPME025	Calculation of the Equilibrium Parameters for the Compact Ring of TTX	emittance, photon, electron, storage-ring	1625
	H.S. Xu, W.-H. Huang, C.-X. Tang TUB, Beijing, People's Republic of China S.-Y. Lee IUCEEM, Bloomington, Indiana, USA
	Intra-Beam Scattering (IBS) can cause emittance growth in high intensity low energy beams. We study its effect on the compact low energy electron storage ring, proposed for Tsinghua Thomson Scattering X-ray source (TTX). For a single bunch with peak current at about 17A and re-entrant type normal conducting RF cavity with peak voltage at 15kV, the equilibrium horizontal and vertical emittances are 2.9 and 0.3 μm, and the rms momentum spread and bunch length are about 0.2%, and 23ps. In this paper, we report the methods and results of the IBS calculation.

TUPME046	Performance of SPS Low Transition Energy Optics for LHC Ion Beams	optics, ion, emittance, space-charge	1667
	F. Antoniou, G. Arduini, H. Bartosik, T. Bohl, S. Cettour Cave, K. Cornelis, D. Manglunki, Y. Papaphilippou CERN, Geneva, Switzerland
	An optics with low transition energy has been developed in the SPS for removing intensity limitations of the LHC proton beam and has become operational towards the second part of the 2012 LHC proton run. This optics was also used for filling the LHC with lead ions during the p/Pb run of the beginning of 2013. The impact of this optics in the performance of the LHC ion beam is studied here, especially with respect to collective effects, at the SPS injection energy. In particular, the potential gain of the increased beam sizes provided by this optics, with respect to losses and emittance blow up due to space-charge and Intrabeam Scattering (IBS) is evaluated. The measured lifetime is compared with the one provided by the Touschek effect and its interplay with RF noise is studied. The models are supported by measurements in the SPS and in the LHC flat bottom.

TUPME065	Experimental Study of Horizontal-Longitudinal Coupling at CesrTA	coupling, lattice, cavity, simulation	1715
	M. P. Ehrlichman, A. Chatterjee, W. Hartung, D.P. Peterson, N.T. Rider, D. L. Rubin, J.P. Shanks, S. Wang CLASSE, Ithaca, New York, USA
	Funding: This research was supported by NSF and DOE contracts PHY-0734867, PHY-1002467, PHYS-1068662, DE-FC02-08ER41538, DE-SC0006505. In storage rings, the presence of horizontal dispersion in the RF cavities introduces x-z coupling. The result is that the beam is skewed in the horizontal-longitudinal plane. The skew angle is proportional to the V15 term of the 6X6 coupling matrix which is proportional to the RF cavity voltage and the horizontal dispersion in the cavity. Here we report experiments at CesrTA where x-z coupling was explored using three distinct lattice configurations with different V15 coupling terms. We explore x-z coupling for each of these lattices by measuring the horizontal projection of the beam with a beam size monitor, as the RF voltage is varied. The first lattice has about 1 m dispersion in the RF cavities, resulting in a V15 term at the beam size monitor source point corresponding to 16 mrad x-z tilt. In the second, the V15 generated in one pair of cavities is compensated at the second pair by adjusting the horizontal betatron phase advance between the cavity pairs. In the third, the optics are adjusted so that the RF cavity region is dispersion-free, eliminating the coupling entirely. Additionally, intra-beam scattering is evident in our measurements of beam size vs. RF voltage.

TUPWA024	The Beam Gass Coulomb Scattering in Electron Storage Ring	simulation, electron, radiation, synchrotron	1778
	X.L. Yu, Z. Bai, W.W. Gao, W. Li, L. Wang USTC/NSRL, Hefei, Anhui, People's Republic of China
	Among the various factors which determine the beam life time of the HLSII electron storage ring, the beam loss due to the scattering on residual gas is simulated using MC method. The paper will give the process of elastic and inelastic scattering, and the probability of each scattering is calculated, then using MC sampling to decide which particles will participate in the collision. Tracking the beam with scattering of beam-gas included, the spatial distribution of beam will be obtained. Finally we will give the influence analysis of beam-gas scattering.

TUPWO023	Parasitic Slow Exraction of Extremely Weak Beam From a High-intensity Proton Rapid Cycling Synchroton	extraction, proton, synchrotron, simulation	1931
	Y. Zou, H.T. Jing, C. Meng, J.Y. Tang, Z. Yang IHEP, Beijing, People's Republic of China
	This paper proposes a new method to extract extremely weak beam from a high-intensity proton rapid cycling synchrotron in the parasitic mode, while maintaining the normal fast extraction. The usual slow extraction from a synchrotron by third-order resonance method cannot be applied in a RCS due to very short flat-top at the extraction energy. This is even more difficult when it is high-intensity synchrotron due to the strict control on beam loss. The parasitic slow extraction method to extract extremely weak beam from the RCS of CSNS has been studied in details. By moving only beam halo to a scatting foil in the arc region by a local orbit bump in about 2 ms before the fast extraction, one can extract a very small part of the scattered particles with very limited beam loss in the process. At 1.6 GeV and 62.5 A in beam power, halo particles of about 10^-4 total particles are involved in the parasitic slow extraction can result in a beam intensity of 2105 protons per cycle or lower. Detailed studies including scattering effect in the foil, orbit bumps by bump magnets and energy displacement by adjusting RF, and multi-particle simulations by ORBIT and TURTLE codes are presented.

TUPWO050	Commissioning and Operation at β^* = 1000 m in the LHC	optics, proton, quadrupole, insertion	1982
	H. Burkhardt, T. Persson, R. Tomás, J. Wenninger CERN, Geneva, Switzerland S. Cavalier LAL, Orsay, France
	We have developed a special optics with a β^* of 1000 m for two interaction regions (IR1 and IR5) in the LHC, to produce very low divergence beams required for elastic proton-proton scattering. We describe the design, commissioning and operation of this optics in the LHC. The β^* of 1000 m was reached by de-squeezing the beams using 17 intermediate steps beyond the β^* of 90 m, which had been the previous highest β^* value reached in the LHC. The optics was measured and the beta beating globally corrected to a level of 10 per cent.

WEPWA016	Production of Intense High Energy Gamma Beam for LEPS2 Project at SPring-8	laser, injection, storage-ring, electron	2162
	T. Yorita, T. Hotta, N. Muramatsu, T. Nakano, M. Oka, M. Yosoi RCNP, Osaka, Japan S. Daté, Y. Ohashi, H. Ohkuma, M. Oishi, Y. Okayasu, M. Shoji, S. Suzuki, Y. Taniuchi JASRI/SPring-8, Hyogo-ken, Japan
	Construction of new beam line for LEPS2 Project at SPring-8 has been done and development is now undergoing. LEPS2 is the project for high energy hadron physics using intense high energy gamma beam as probe. The gamma beam is produced by laser backward Compton scattering with injecting high power UV laser into the 8 GeV electron beam on long straight section of SPring-8 storage ring. The target intensities are ~10⁷/s for E_γ=2.4 GeV, ~10⁶/s for E_γ=2.9 GeV.

WEPWA021	X-ray Spectra Reconstruction with HOPG Crystal on TTX	photon, simulation, electron, laser	2174
	Z. Zhang, Y.-C. Du, J.F. Hua, W.-H. Huang, C.-X. Tang, D. Wang, L.X. Yan TUB, Beijing, People's Republic of China
	Thomson Scattering sources, as the new generation of bright X-ray sources, have great application potential in many respects. Traditional spectra measurement methods, applied to measured the spectra of Thomson Scattering source, are troublesome as the X-ray beam is too intense to cause pile up problems. In this article, we use the HOPG crystal to reconstruct the X-ray spectra of Tsinghua Thomson X-ray source (TTX) through Braggs law. This method can get reasonable results with single or several shots, with high energy resolution. We also compare the experiment results of this method with the reconstructed spectra by analyzing the attenuation data of the X-ray beam in silicon , and these two results agree well with each other.

WEPME021	Development of CO2 Laser Optical Enhancement Cavity for a Laser-Compton X-ray Source	cavity, laser, polarization, photon	2974
	K. Ando, A. Endo, K. Sakaue, T. Takeichi, M. Washio Waseda University, Tokyo, Japan
	Funding: Work supported by NEDO (New Energy and Industrial Technology Development Organization). We have been developing a laser-Compton X-ray source using optical enhancement cavity. We have studied 1um pulse laser storage in optical cavity and use for the experiments. Usage of 10um laser for optical enhancement cavity will increase the X-ray energy region of one laser-Compton X-ray source, so that we decided to develop the optical cavity for CO2 laser. We have designed external optical cavity for CO2 laser commercially available optics and verified the enhancement of CO2 laser in external optical cavity, and measured fundamental parameters such as finesse, matching efficiency, and enhancement factor. We have already achieved 540 of finesse, 43 of enhancement, and tested non-planer cavity, which storages two circular polarization separately. In this conference, we will report the design and experimental results of CO2 laser storage cavity and also some future prospects.

THPFI024	Application of Electropolishing in CSNS/RCS Primary Collimator Scrapers	cathode, collimation, synchrotron, proton	3348
	L. Kang, Z.X. He, H. Qu, J.B. Yu, Y.Q. Zou IHEP, Beijing, People's Republic of China
	According to the requirements for the beam collimation system physical design of the rapid cycling synchrotron (RCS) of China Spallation Neutron Source (CSNS) , the primary collimator scrapers are made of 0.17±0.005mm thickness tungsten sheets. The machining of the tungsten sheet is very difficult because of high hardness and characteristics of the intrinsic brittleness of tungsten. In this paper, electropolishing processing methods is used for tungsten sheets processing. A special electropolishing device is designed according to the principle and process of electropolishing. The processing of tungsten sheets are finally completed after a series of experiments. And the rules of electropolishing for tungsten sheet processing are obtained according to the experimental results.

THPFI029	The Structure Design and Analysis of Proton Beam Window for CSNS	radiation, target, proton, neutron	3361
	H.J. Wang, L. Kang, R.H. Liu, H. Qu, D.H. Zhu IHEP, Beijing, People's Republic of China
	The proton beam window (PBW) is one of the key devices of China Spallation Neutron Source (CSNS). In this paper, a new designed PBW structure called single-double layer structure is discussed. The new structure will be used in CSNS, and it is designed based on the beam characteristic of CSNS, which power is 100 kW. The structure design and thermal-analysis are presented, and the convective coefficient of cooling water is calculated. Besides, the radiation damage is discussed to assure there is no danger of radiation lifetime of PBW.

THPFI032	The Design and Analysis of Proton Beam Window for CSNSIII	proton, radiation, target, neutron	3367
	H.J. Wang, L. Kang, R.H. Liu, H. Qu, D.H. Zhu IHEP, Beijing, People's Republic of China
	The proton beam window (PBW) is one of the key devices of China Spallation Neutron Source (CSNS). When the beam power of CSNS upgrades from 100kw to 500kw (CSNSIII), the present single-double layer structure of PBW cannot meet the demands. The PBW will be changed to other structure. This paper discusses sandwiched structure and multiple pipe structure, and the later one is chosen as the PBW of CSNSIII. An appropriate convective coefficient of cooling water is chosen, based on which the detailed thermal-stress analysis is presented. Besides, the lifetime is estimated. All these analyses show the designed PBW can work well in CSNSIII.

THPFI058	Qualification of a Glassy Carbon Blade for a LHC Fast Vacuum Valve	vacuum, acceleration, accumulation, background	3424
	C. Garion, P. Coly CERN, Geneva, Switzerland
	To protect sensitive LHC machine systems against an unexpected gas inrush, a fast vacuum valve system is under development at CERN. The design of the shutter has to be compatible with dynamic loads occurring during the fast closure, namely in the 20 ms range. The material has to fulfil all main requirements such as transparency, high melting temperature, dust free and adequate leak tightness. A development of a blade in vitreous carbon material has been carried out at CERN. The blade has been successfully integrated in a commercial pendulum fast valve. In this paper, the vacuum and mechanical qualification tests are presented.

THPFI059	Robustness Test of a Silicon Strip Crystal for Crystal-assisted Collimation Studies in the LHC	proton, alignment, collimation, extraction	3427
	A. Lechner, J. Blanco Sancho, F. Burkart, M. Calviani, M. Di Castro, Y. Gavrikov, J. Lendaro, F. Loprete, R. Losito, C. Maglioni, A. Masi, S. Montesano, A. Perillo-Marcone, P.S. Roguet, W. Scandale, D. Wollmann CERN, Geneva, Switzerland J. Blanco Sancho EPFL, Lausanne, Switzerland F. Burkart IAP, Frankfurt am Main, Germany Y. Gavrikov PNPI, Gatchina, Leningrad District, Russia V. Guidi, A. Mazzolari INFN-Ferrara, Ferrara, Italy V. Guidi, A. Mazzolari UNIFE, Ferrara, Italy W. Scandale LAL, Orsay, France
	Over the past years, the UA9 experiment has successfully demonstrated the viability of enhancing the collimation efficiency of proton and ion beams in the SPS by means of bent crystals. An extension of UA9 to the LHC has been recently approved. The conditions imposed by the LHC operational environment, in particular the tremendous energy density of the beam, require a reliable understanding of the crystal integrity in view of potential accident scenarios such as an asynchronous beam dump. For this purpose, irradiation tests have been performed at the CERN-HiRadMat facility to examine the mechanical strength of a silicon strip crystal in case of direct beam impact. The tests were carried out using a 440 GeV proton beam of 0.5 mm transverse size. The crystal, 3 mm long in beam direction, was exposed to a total of 210¹⁴ protons, with individual pulse intensities reaching up to 310¹³. First visual inspections reveal no macroscopic damage to the crystal. Complementary post-irradiation tests are foreseen to assess microscopic lattice damage as well as the degradation of the channelling efficiency. On behalf of the UA9 Collaboration.

THPFI065	Thermo-mechanical Investigations of the SINQ "Cannelloni" Target	target, simulation, factory, neutron	3445
	R. Sobbia, S. Dementjevs, S. Joray, M. Wohlmuther PSI, Villigen PSI, Switzerland
	Numerical results of three-dimensional ANSYS thermo-mechanical simulations of single components of the SINQ target system are presented. Thermal stresses are generated by energy deposition in so-called ‘‘cannelloni'' consisting of a Zircaloy-2 rod filled with Lead to 90% of its inner volume. The molten region of the inner Lead filling is calculated by thermal analysis using the energy deposition profile imported from MCNPX calculations. Induced mechanical stresses are studied for a set of predefined parameters, the heat transfer coefficient and the bulk temperature of the heavy water cooling system. Critical stress regions are investigated to provide possible failure scenarios and overall system performance.

THPWA009	Generation of Laser Compton Scattered Gamma-rays from a 150-MeV Microtron	laser, microtron, neutron, photon	3645
	R. Hajima, C.T. Angell, I. Daito, T. Hayakawa, M. Kando, T. Shizuma JAEA, Ibaraki-ken, Japan H. Ohgaki Kyoto University, Institute for Advanced Energy, Kyoto, Japan
	Funding: This work was supported in part by special coordination funds for promoting science and technology in Japan (Grant No. 066). We have developed a laser Compton scattered gamma-ray source based on a 150-MeV racetrack microtron at Japan Atomic Energy Agency. The microtron equipped with a photocathode RF gun accelerates a single bunch of electrons to collide with a laser pulse from a Nd:YAG laser. We have employed laser pulse compression by stimulated Brillouin scattering to obtain high-flux gamma-rays, > 10⁵ ph/s. The gamma-ray source is a prototype of commercial machine for nuclear security applications, non-destructive detection of nuclear material hidden in a ship cargo. Design and performance of the gamma-ray source are presented.

THPWA010	Application of X-band 30 MeV Linac Neutron Source to Nuclear Material Analysis for Fukushima Nuclear Plant Accident	neutron, linac, electron, target	3648
	M. Uesaka, K. Dobashi, T. Fujiwara The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan H. Harada JAEA, Ibaraki-ken, Japan K. Tagi University of Tokyo, Tokyo, Japan M. Yamamoto Accuthera Inc., Kawasaki, Kanagawa, Japan
	We plan to use our X-band (11.424GHz) electron linac as a neutron source for the nuclear analysis for the Fukushima nuclear plant accident. Quantitative material analysis and forensics for nuclear security will start several years later after the safe settlement of the accident is established. For the purpose, we should now accumulate more precise nuclear data of U, Pu, TRU and MA especially in epithermal (0.1-10 eV) neutrons. Therefore, we have decided to move the linac into the core of the experimental nuclear reactor “Yayoi” which is now under the decommission procedure. First we plan to perform the TOF (Time Of Flight) transmission measurement of the total cross sections of the nuclei for 0.1-10 eV neutrons. Electron energy, macro-pulse length, power and neutron yield are ~30 MeV, 100 ns – 1 micros, <0.5 kW and <10¹² n/s, respectively. Optimization of the design of a neutron target (Ta, W, U), TOF line and neutron detector (Ce:LiCAF) of high sensitivity and fast response is underway. Installation, commissioning and measurement starts in 2014. Detailed design and way how to contribute to the analysis of the Fukushima nuclear plant accident will be presented.

THPWO084	Optimization of a Bi-spectral Boxed Side-by-Side Moderator for the Target-Moderator-Reflector System of the ESS	neutron, target, proton, brightness	3957
	T. Reiss, U. Filges, V. Talanov, M. Wohlmuther PSI, Villigen PSI, Switzerland F. X. Gallmeier ORNL, Oak Ridge, Tennessee, USA
	Providing bi-spectral neutron beams is one of the main neutronics design criteria for the target-moderator-reflector (TMR) system of the European Spallation Source, to be built in Lund (Sweden). As a first step, the requirements of neutronics instruments regarding the neutron spectrum are formulated, a figure of merit is defined. In order to maximize the moderator performance to obtain bi-spectral neutron extraction, a parametrized model of the TMR system is developed and used with a MCNPX-based optimization framework. This model is then used to study and optimize the moderator performance, especially in the thermal and cold parts of the spectrum. Results obtained with an optimized moderator setup are dicussed and compared with the requirements of the instruments.

FRXAA01	Beam Dynamics and Collective Effects in "Ultimate" Storage Rings	emittance, ion, coupling, electron	3981
	M. Takao JASRI/SPring-8, Hyogo-ken, Japan
	This presentation will review the beam dynamics issues such as impedance driven instabilities, intrabeam scattering, and the Touschek lifetime in ultimate storage rings with very low emittance.
	Slides FRXAA01 [11.245 MB]

Paper

Title

Other Keywords

Page

MOPEA012

Lifetime Studies at Metrology Light Source and ANKA

cavity, optics, electron, septum

88

T. Goetsch, J. Feikes, M. Ries, G. Wüstefeld
HZB, Berlin, Germany
A.-S. Müller
KIT, Karlsruhe, Germany

The Metrology Light Source (MLS)*, situated in Berlin (Germany) is an electron storage ring operating from 10⁵ MeV to 630 MeV and is serving as the national primary radiation source standard from the near infrared to the vacuum ultraviolet spectral region. In its standard user mode, the lifetime is dominated by the Touschek effect. Measurements and analysis of the Touschek lifetime as a function of beam current and RF-Voltage will be presented and compared to measurements done at the ANKA electron storage ring (Karlsruhe, Germany) which operates at 0.5 to 2.5 GeV**.
* R. Klein et al., Phys. Rev. ST-AB 11, 110701 (2008)
** A.-S. Müller et al., Energy Calibration Of The ANKA Storage Ring, In Proceedings of EPAC 2004

MOPEA017

Electron Cooling of Heavy Ions Interacting with Internal Target at HESR of FAIR

electron, target, emittance, ion

103

T. Katayama, M. Steck
GSI, Darmstadt, Germany
R. Maier, D. Prasuhn, H. Stockhorst
FZJ, Jülich, Germany

The High Energy Storage Ring (HESR) is designed and optimized to accumulate and store the anti-proton beam for the internal target experiment. The recent demand of atomic physics has impacted to use the HESR facility also as the storage ring of bare heavy ions. In this concept the bare heavy ions are injected at 740 MeV/u from the Collector Ring where the ions are well stochastically cooled to be matched with HESR ring acceptance. In the HESR the 2 MeV electron cooler is prepared with the maximal electron current of 3 A and the cooling length of 2.7 m. The electron cooling process of typically ²³⁸U⁹²⁺ beam is simulated for the Hydogen and Xe internal target with simultaneous use of barrier voltage to compensate the mean energy loss caused by the interaction with internal target. In the present report the detailed simulation results of 6D phase space obtained by the particle tracking code are precisely discussed.

MOPEA022

Beam Profile Measurement for High Intensity Electron Beams

electron, laser, photon, diagnostics

118

T. Weilbach, K. Aulenbacher, M.W. Bruker
HIM, Mainz, Germany
K. Aulenbacher
IKP, Mainz, Germany

Recent developments in the field of high intensity electron beams in the regime below 10 MeV, e.g. energy recovery linacs or magnetized high energy electron coolers, have led to special demands on the beam diagnostics. Since commonly used diagnostic tools like synchrotron radiation and scintillation screens are ineffective or not able to withstand the beam power without being damaged, new methods are needed. Hence a beam profile measurement system based on beam induced fluorescence (BIF) was built. This quite simple system images the light generated by the interaction of the beam with the residual gas onto a PMT. A more elaborated system, the Thomson Laser Scanner (TLS) - the non-relativistic version of the Laser Wire Scanner - is proposed as a method for non-invasive measurement of all phase space components, especially in the injector and merger parts of an ERL. Both methods are implemented in a 100 keV photo gun. Beam profile measurements with BIF as well as first results of the TLS will be presented.

MOPEA037

Theoretical Study on the Two-stage Collimation System Design

collimation, vacuum, simulation, space-charge

157

N. Wang, S. Wang
IHEP, Beijing, People's Republic of China

Two-stage collimation system is widely used in high intensity machines to localize the beam losses in a restricted area. In the well-known theory, the optical constrains are expressed by the betatronic phase advances between primary and secondary collimators, which minimize the size of the secondary halo. In this paper, the physical model is developed considering the characteristic of the space charge dominated beams. Numerical studied are performed to verify the theoretical model.

MOPEA057

Studies of the Electron Beam Lifetime at MAX III

cavity, electron, vacuum, emittance

208

A. Hansson, Å. Andersson, J. Breunlin, G. Skripka, E.J. Wallén
MAX-lab, Lund, Sweden

MAX III is a 700 MeV 3rd generation synchrotron light source located at the MAX IV Laboratory in Sweden. The lifetime in the storage ring is lower than originally envisaged. From vertical scraper measurements the lifetime contributions at 300 mA stored current have been determined. The lifetime is mainly limited by the Touschek lifetime, which is lower than its design value, whereas the vacuum lifetime is close to the expected value. The low Touschek lifetime is explained by a lower than design emittance ratio and momentum acceptance in the storage ring.

MOPEA074

Lattice Studies for a Potential Soft X-ray Diffraction Limited Upgrade of the ALS

lattice, emittance, brightness, injection

258

C. Steier, J.M. Byrd, R.W. Falcone, S.D. Kevan, D. Robin, C. Sun, H. Tarawneh, W. Wan
LBNL, Berkeley, California, USA

Funding: The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The Advanced Light Source (ALS) at Berkeley Lab has seen many upgrades over the years, keeping it one of the brightest sources for soft x-rays worldwide. Recent developments in magnet technology and lattice design (multi bend achromat lattices) appear to open the door for very large further increases in brightness, particularly by reducing the horizontal emittance, even within the space constraints of the existing tunnel. Initial studies yielded candidate lattices which approach the soft x-ray diffraction limit (around 2 keV) in both planes within the ALS footprint.

MOPFI032

Electron Emission of the Stripping Foil and Collimation System for CSNS/RCS

electron, proton, collimation, injection

354

M.Y. Huang, Y.D. Liu, N. Wang, S. Wang
IHEP, Beijing, People's Republic of China

For the Rapid Cycling Synchrotron of the China Spallation Neutron Source (CSNS/RCS), the electron emission plays an important role in the accelerator limitation. The interactions between the proton beam and the stripping foil were studied, and the electron scattering processes were simulated by the ORBIT and FLUKA codes. Then, the electron energy distribution and the electron yielding rate can be given. Furthermore, the interactions between the proton beam and the collimation system were studied, and the electron scattering processes were simulated. Then, the energy distribution of the primary electron emission can be given and the yielding rate of the primary electron can be obtained.

MOPFI081

Correlating Structure and Function - In situ X-ray Analysis of High QE Alkali-antimonide Photocathodes

cathode, emittance, controls, vacuum

464

J. Smedley, K. Attenkofer, S.G. Schubert
BNL, Upton, Long Island, New York, USA
I. Ben-Zvi, X. Liang, E.M. Muller, M. Ruiz-Osés
Stony Brook University, Stony Brook, USA
T. Forrest, H.A. Padmore, T. Vecchione, J.J. Wong
LBNL, Berkeley, California, USA
J. Xie
ANL, Argonne, USA

Funding: The authors wish to acknowledge the support of the US DOE, under Contract No. KC0407-ALSJNT-I0013, DE-AC02-98CH10886 and DE-SC0005713. Use of CHESS is supported by NSF award DMR-0936384.
Alkali antimonide photocathodes have high quantum efficiency and low emittance when illuminated by visible light, and are thought to be well suited for use in high-brightness photoinjectors of 4th generation light sources. Here we report on the growth of multi-alkali K2CsSb cathodes on [100] silicon substrates measured using in-situ X-ray diffraction (XRD) and X-ray reflection (XRR). Correlations between cathode structure and growth parameters and the resulting quantum efficiency (QE) are also explored. The best cathodes have a QE at 532 nm in excess of 6% and are structurally textured K2CsSb with grain sizes in excess of 20 nm. In an attempt to reduce the complexity of the current growth methodology we are also making alkali antimonides in parallel via the reaction of bulk materials in an inert environment. This approach has the advantage that the desired stoichiometry can be obtained exactly. Initial diffraction results from prepared bulk materials are promising and show the formation of well reacted K3Sb. In the future we intend to transfer this material to smooth thin photocathode films by either sputtering or pulsed laser deposition.

MOPME004

Fast Luminosity Monitoring using Diamond Sensors for Super Flavour Factories

luminosity, photon, electron, positron

473

C. Rimbault, P. Bambade
LAL, Orsay, France

Super flavour factories aim to reach very high luminosities thanks to a new concept whereby the ultra-low emittance beams collide with a large crossing angle. Fast luminosity measurements are needed as input to luminosity optimization and feedback in the presence of dynamic imperfections. The required small relative precision can be reached exploiting the very large cross section of the radiative Bhabha process at zero photon scattering angle. The instrumental technique selected to sustain the large particle fluxes is based on diamond sensors to be positioned via moveable stages immediately outside the beam pipe, at locations chosen to minimize the contamination from other particle loss mechanisms.

MOPME038

A New Theoretical Design of BLM System for HLS II

electron, vacuum, monitoring, emittance

553

Y.K. Chen, L.J. He, J. Li, W. Li, Y. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China

Beam loss monitoring (BLM) system has been commonly used to detect the vacuum leakage. The existing BLM system for Hefei Light Source (HLS) was built in 2000. It played an important role in analyzing beam loss distribution and regulating the machine operation parameters. Recently, HLS is being upgraded to HLS II. The emittance will be decreased to increase the brilliance of synchrotron radiation. The Touschek lifetime will be much shorter than before, and dominate the total beam lifetime. It is necessary to redesign the BLM system for HLS II. The most important part of this work is to find a better method of monitoring Touschek lifetime by BLM system while keeping its general functions. According to the results of our research, a preliminary theoretical design for the new BLM system is proposed in this paper. This new system will play an important role in the storage ring commissioning, troubleshooting, and beam lifetime studying.

MOPME065

Approximate Method of Calculation of a Bunch Radiation in Presence of Complex Dielectric Object

radiation, vacuum, optics, diagnostics

625

A.V. Tyukhtin, E.S. Belonogaya, S.N. Galyamin
Saint-Petersburg State University, Russia

Funding: Work supported by the Grant of President of Russian Federation, Russian Foundation for Basic Research, and the Dmitry Zimin "Dynasty" Foundation.
Cherenkov radiation is widely used for detection of charged particles and can be also applied for particle bunch diagnostics*. As a rule, dielectric objects applied for these goals have complex forms. Therefore development of methods of calculation of bunch radiation in presence of complex dielectric objects is now of a great interest. The approximate method developed by us allows to take into account influence of the object boundaries closed to the charge trajectory as well as "external" boundaries of the object. The case of the charge crossing a dielectric plate was considered as a test problem. The exact solution of this problem is in a good agreement with our approximate solution. Next, the cases of more complex objects were analyzed. One of them is a dielectric cone with a vacuum channel. Particularly, it was shown that radiation can be convergent under certain conditions, that is the field outside the cone can be more intensive than on the cone boundary. Radiation of the bunch in the case of dielectric prism was considered as well.
* A.P. Potylitsyn, Yu.A. Popov, L.G. Sukhikh, G.A. Naumenko, M.V. Shevelev, Journal of Physics: Conference Series 236 (2010) 012025.

MOPWA036

GEM Detectors for the Transverse Profile Measurement of Low Energy Antiprotons and High Energy Hadrons

antiproton, electron, hadron, cathode

747

J. Spanggaard, P. Carriere, S.C. Duarte Pinto, G. Tranquille
CERN, Geneva, Switzerland

Gas Electron Multipliers (GEM) are finding more and more applications in beam instrumentation. Gas Electron Multiplication is a very similar physical phenomenon to that which occurs in Multi Wire Proportional Chambers (MWPC), but for small profile monitors GEMs are much more cost effective to produce and maintain. In 2012, all Multi-Wire Proportional Chambers in the experimental areas of the Antiproton Decelerator at CERN were successfully replaced by Gas Electron Multipliers. This paper describes the choice of detector and reports on the commissioning of 20 GEM detectors for transverse profile measurement on low energy antiproton beams (5.3 MeV, equal to 100 MeV/c). It will also cover the development of, and first results from, a new 200x200 mm GEM detector for profiling the high energy muon beam (172 GeV/c) delivered to the COMPASS experiment and discuss the outlook for replacing all Multi-Wire Proportional Chambers in the CERN experimental areas by GEM based monitors.

MOPWA059

Beam Emittance Measurements and Beam Transport Optimization at the Clatterbridge Cancer Centre

quadrupole, emittance, proton, cyclotron

810

T. Cybulski, O. Karamyshev, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A. Degiovanni
TERA, Novara, Italy
A. Kacperek, B. Marsland, I. Taylor, A. Wray
The Douglas Cyclotron, The Clatterbridge Cancer Centre NHS Foundation Trust, Wirral, United Kingdom
O. Karamyshev, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Funding: Cockcroft Institute, Daresbury, Warrington, WA4 4AD, United Kingdom University of Liverpool, Liverpool, United Kingdom
The QUASAR Group is preparing tests of the high energy physics LHCb VELO detector as a non–invasive online dose monitor at the 60 MeV proton therapy beam at the Clatterbridge Cancer Centre (CCC), UK. The proposed method relies on the cross-correlation between the beam halo signal as measured by VELO and the dose delivered to the patient, linked via the absolute intensity of the beam. In order to estimate the expected halo signal and the total beam intensity, studies into proton beam transport through the whole CCC beam line have been carried out. This required the measurement of beam emittance at several positions of the beam delivery system. Quadrupole scans have been realized using a CsI (Tl) scintillating screen in combination with an 8 bit, 13 Mpixel CCD camera. In this contribution, results from measurements are presented and include a discussion of the effects from dispersion in the beam. Experimental data are compared against earlier measurements performed in 1998 and are used as a basis for suggestions targeting an overall optimization of beam transport at CCC.
* Assessing the Suitability of a Medical Cyclotron as an Injector for an Energy Upgrade, J. A. Clarke et all , CLRC Daresbury Laboratory, Warrington, UK

MOPWO038

Cleaning Inefficiency of the LHC Collimation System during the Energy Ramp: Simulations and Measurements

simulation, collimation, proton, injection

975

E. Quaranta, R. Bruce, L. Lari, D. Mirarchi, S. Redaelli, A. Rossi, B. Salvachua, G. Valentino
CERN, Geneva, Switzerland
L. Lari
IFIC, Valencia, Spain
D. Mirarchi
The Imperial College of Science, Technology and Medicine, London, United Kingdom
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta

The cleaning inefficiency of the LHC collimation system has already been studied in detail at injection and top energy (450 GeV and 4 TeV respectively). In this paper the results are presented for the cleaning inefficiency at intermediate energies, simulated using the SixTrack code. The first comparisons with measured provoked losses are discussed. This study helps in benchmarking the energy dependence of the simulated inefficiency and is thus important for the extrapolation to future operation at higher energies.

TUODB103

Recent Results from CesrTA Intrabeam Scattering Investigations

emittance, coupling, simulation, damping

1126

M. P. Ehrlichman, A. Chatterjee, W. Hartung, D.P. Peterson, N.T. Rider, D. L. Rubin, D. Sagan, J.P. Shanks, S. Wang
CLASSE, Ithaca, New York, USA

Funding: This research was supported by NSF and DOE contracts PHY-0734867, PHY-1002467, PHYS-1068662, DE-FC02-08ER41538, DE-SC0006505.
Manifestation of intrabeam scattering (IBS) in an electron/positron storage ring depends on the radiation damping time in two ways. First, the beam size is the equilibrium of the IBS growth rate in each of the three degrees of freedom and corresponding damping rates. Second, scattering events that occur less frequently than order once per damping time contribute to non-Gaussian tails that are invisible to our beam size monitors. The tail cut procedure excludes these relatively rare events in the calculation of equilibrium beam size. In machines with short damping times, the tail cut significantly reduces the effective IBS growth rate. At CesrTA, we measure the dependence of beam size on bunch charge in IBS-dominated beams. We vary the vertical emittance using a closed optics bump that increases the vertical dispersion and transverse coupling in the wiggler regions. Measurements are taken at both 2.1 and 2.3 GeV. Here we report the results of these experiments and compare those results to theory.

Slides TUODB103 [1.221 MB]

TUPFI005

Synchrotron-Radiation Photon Distribution for Highest Energy Circular Colliders

photon, radiation, vacuum, electron

1340

G.H.I. Maury Cuna
CINVESTAV, Mérida, Mexico
G. Dugan, D. Sagan
CLASSE, Ithaca, New York, USA
F. Zimmermann
CERN, Geneva, Switzerland

Funding: Acknowledgements to CINVESTAV, CERN and EPLANET project.
At high energies, beam-induced synchrotron radiation is an important source of heating, beam-related vacuum pressure increase, and primary photoelectrons, which can give rise to an electron cloud. The photon distribution along the beam pipe wall is a key input to codes such as ECLOUD and PyECLOUD, which model the electron cloud build-up. For future high-energy colliders, like TLEP or SHE-LHC, photon stops and antechambers are considered in order to facilitate cooling and vacuum pressure control. We use the Synrad3D code developed at Cornell to simulate the photon distribution for the LHC.

TUPFI037

Collimation Down to 2 Sigma in Special Physics Runs in the LHC

proton, background, luminosity, emittance

1427

H. Burkhardt, S. Jakobsen, S. Redaelli, B. Salvachua, G. Valentino
CERN, Geneva, Switzerland

We report on observations with collimation very close to the beam. Primary collimators were moved in small steps down to 2 σ from the beam axis to allow for measurements of very forward proton scattering in special high-beta runs in the LHC. We studied the reduction in intensity as a function of collimator position which provides information about the halo shape. After scraping at 2 σ, collimators were retracted to 2.5 σ. This allowed for measurements of very forward proton-proton scattering with roman pot detectors at 3 σ from the beam axis at acceptable background levels for about an hour. Good background conditions were restored by another scraping with primary collimators at 2 σ. Beam lifetimes and halo repopulation times were found to be sufficiently long to allow for several hours of data taking between scraping in a single LHC fill.

TUPFI078

Measurement of the Total Cross Section of Uranium-uranium Collisions at a Center-of-mass Energy of 192.8 GeV per Nucleon-pair

ion, beam-losses, luminosity, emittance

1529

W. Fischer, A.J. Baltz, M. Blaskiewicz, K.A. Drees, D.M. Gassner, Y. Luo, M.G. Minty, P. Thieberger, M. Wilinski
BNL, Upton, Long Island, New York, USA
I.A. Pshenichnov
RAS/INR, Moscow, Russia

Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy.
Heavy ion cross sections totaling several hundred barns have been calculated previously for the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). These total cross sections are more than an order of magnitude larger than the geometric ion-ion cross sections, primarily due to Bound-Free Pair Production (BFPP) and Electro-Magnetic Dissociation (EMD). Apart from a general interest in verifying the calculations experimentally, an accurate prediction of the losses created in the heavy ion collisions is of practical interest for the LHC, where some collision products are lost in cryogenically cooled magnets and have the potential to quench these magnets. In the 2012 RHIC run uranium ions collided with each other at a center-of-mass energy of 192.8 GeV per nucleon-pair with nearly all beam losses due to collisions. This allows for the measurement of the total cross section and a comparison with calculations.

TUPME007

Beam Lifetime in Low Emittance Rings

simulation, lattice, background, factory

1574

M. Boscolo
INFN/LNF, Frascati (Roma), Italy

In this paper I will review the main effects in low emittance rings that determine the beam lifetime by causing beam losses along the ring. As an example, the case for a B-factory based on the crab-waist collision scheme has been studied. During the machine design all the effects that determine the beam lifetime and induce backgrounds in the detector have been analyzed in details. The crab-waist scheme provides an higher luminosity, but at the same time it induces higher beam losses at the final focus. For this reason single beam effects such as Touschek and beam-gas scattering have been studied in details, by means of a macroparticle tracking code developed for this purpose*. Also Radiative Bhabha scattering, that is the dominant effect to lifetime and backgrounds has been studied with the same technique to check possible multiturn losses at IR. An efficient collimation system has been designed to intercept scattered particles that would be lost in the IR in both the horizontal and the vertical plane. Recently, the Touschek tracking simulation code has been implemented to study the lifetime behavior for extremely low-emittance rings.
* M. Boscolo and P. Raimondi, “Monte Carlo simulation for the Touschek effect with the crab-waist scheme”, Phys. Rev. ST-AB 15 104201 (2012)

TUPME013

Coherent Thomson Scattering using Beam Echo

laser, electron, undulator, radiation

1592

K. Ohmi, S. Kamada
KEK, Ibaraki, Japan
H. Fares
Kanazawa University, Kanazawa, Japan

Longitudinal phase space of the beam is modulated by laser interacting in undulators. The beam can have higher frequency component using the beam echo than than the laser as dicussed by G. Stupakov et al. The modulated beam has a potential to emit coherent radiation with the wave length. We evaluate coherent short wave length (~nm) and/or short pulse (attosec) light source using the beam echo in a low energy accelerator ~100MeV.

TUPME015

Proposal of Polarized Gamma-ray Source for ILC Based on CSR Inverse Compton Scattering

electron, cavity, positron, laser

1598

M. Shimada, K. Yokoya
KEK, Ibaraki, Japan
R. Hajima
JAEA, Ibaraki-ken, Japan
M. Tecimer
University of Hawaii at Manoa, Honolulu, USA

The positron source of International Linear Collider (ILC) requires a circular polarized gamma-ray with a flux more than 10¹⁶ phs./s and a helical undulator-based gamma-ray source is proposed in the baseline design. Although the undulator scheme is technically feasible, it is not easy for a stand-alone operation because of the required electron energy, ~ 150GeV. In this paper, we propose an alternative method, the inverse Compton scattering with a high-power mid-infrared optical pulse generated from coherent synchrotron radiation (CSR). To achieve the high flux gamma-ray, CSR with a few MHz is stacked in a high-finesse optical cavity made of a photonic crystal. In the proposed scheme, a stand-alone operation is feasible because the electron energy is less than 10GeV.

TUPME025

Calculation of the Equilibrium Parameters for the Compact Ring of TTX

emittance, photon, electron, storage-ring

1625

H.S. Xu, W.-H. Huang, C.-X. Tang
TUB, Beijing, People's Republic of China
S.-Y. Lee
IUCEEM, Bloomington, Indiana, USA

Intra-Beam Scattering (IBS) can cause emittance growth in high intensity low energy beams. We study its effect on the compact low energy electron storage ring, proposed for Tsinghua Thomson Scattering X-ray source (TTX). For a single bunch with peak current at about 17A and re-entrant type normal conducting RF cavity with peak voltage at 15kV, the equilibrium horizontal and vertical emittances are 2.9 and 0.3 μm, and the rms momentum spread and bunch length are about 0.2%, and 23ps. In this paper, we report the methods and results of the IBS calculation.

TUPME046

Performance of SPS Low Transition Energy Optics for LHC Ion Beams

optics, ion, emittance, space-charge

1667

F. Antoniou, G. Arduini, H. Bartosik, T. Bohl, S. Cettour Cave, K. Cornelis, D. Manglunki, Y. Papaphilippou
CERN, Geneva, Switzerland

An optics with low transition energy has been developed in the SPS for removing intensity limitations of the LHC proton beam and has become operational towards the second part of the 2012 LHC proton run. This optics was also used for filling the LHC with lead ions during the p/Pb run of the beginning of 2013. The impact of this optics in the performance of the LHC ion beam is studied here, especially with respect to collective effects, at the SPS injection energy. In particular, the potential gain of the increased beam sizes provided by this optics, with respect to losses and emittance blow up due to space-charge and Intrabeam Scattering (IBS) is evaluated. The measured lifetime is compared with the one provided by the Touschek effect and its interplay with RF noise is studied. The models are supported by measurements in the SPS and in the LHC flat bottom.

TUPME065

Experimental Study of Horizontal-Longitudinal Coupling at CesrTA

coupling, lattice, cavity, simulation

1715

M. P. Ehrlichman, A. Chatterjee, W. Hartung, D.P. Peterson, N.T. Rider, D. L. Rubin, J.P. Shanks, S. Wang
CLASSE, Ithaca, New York, USA

Funding: This research was supported by NSF and DOE contracts PHY-0734867, PHY-1002467, PHYS-1068662, DE-FC02-08ER41538, DE-SC0006505.
In storage rings, the presence of horizontal dispersion in the RF cavities introduces x-z coupling. The result is that the beam is skewed in the horizontal-longitudinal plane. The skew angle is proportional to the V15 term of the 6X6 coupling matrix which is proportional to the RF cavity voltage and the horizontal dispersion in the cavity. Here we report experiments at CesrTA where x-z coupling was explored using three distinct lattice configurations with different V15 coupling terms. We explore x-z coupling for each of these lattices by measuring the horizontal projection of the beam with a beam size monitor, as the RF voltage is varied. The first lattice has about 1 m dispersion in the RF cavities, resulting in a V15 term at the beam size monitor source point corresponding to 16 mrad x-z tilt. In the second, the V15 generated in one pair of cavities is compensated at the second pair by adjusting the horizontal betatron phase advance between the cavity pairs. In the third, the optics are adjusted so that the RF cavity region is dispersion-free, eliminating the coupling entirely. Additionally, intra-beam scattering is evident in our measurements of beam size vs. RF voltage.

TUPWA024

The Beam Gass Coulomb Scattering in Electron Storage Ring

simulation, electron, radiation, synchrotron

1778

X.L. Yu, Z. Bai, W.W. Gao, W. Li, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Among the various factors which determine the beam life time of the HLSII electron storage ring, the beam loss due to the scattering on residual gas is simulated using MC method. The paper will give the process of elastic and inelastic scattering, and the probability of each scattering is calculated, then using MC sampling to decide which particles will participate in the collision. Tracking the beam with scattering of beam-gas included, the spatial distribution of beam will be obtained. Finally we will give the influence analysis of beam-gas scattering.

TUPWO023

Parasitic Slow Exraction of Extremely Weak Beam From a High-intensity Proton Rapid Cycling Synchroton

extraction, proton, synchrotron, simulation

1931

Y. Zou, H.T. Jing, C. Meng, J.Y. Tang, Z. Yang
IHEP, Beijing, People's Republic of China

This paper proposes a new method to extract extremely weak beam from a high-intensity proton rapid cycling synchrotron in the parasitic mode, while maintaining the normal fast extraction. The usual slow extraction from a synchrotron by third-order resonance method cannot be applied in a RCS due to very short flat-top at the extraction energy. This is even more difficult when it is high-intensity synchrotron due to the strict control on beam loss. The parasitic slow extraction method to extract extremely weak beam from the RCS of CSNS has been studied in details. By moving only beam halo to a scatting foil in the arc region by a local orbit bump in about 2 ms before the fast extraction, one can extract a very small part of the scattered particles with very limited beam loss in the process. At 1.6 GeV and 62.5 A in beam power, halo particles of about 10^-4 total particles are involved in the parasitic slow extraction can result in a beam intensity of 2105 protons per cycle or lower. Detailed studies including scattering effect in the foil, orbit bumps by bump magnets and energy displacement by adjusting RF, and multi-particle simulations by ORBIT and TURTLE codes are presented.

TUPWO050

Commissioning and Operation at β^* = 1000 m in the LHC

optics, proton, quadrupole, insertion

1982

H. Burkhardt, T. Persson, R. Tomás, J. Wenninger
CERN, Geneva, Switzerland
S. Cavalier
LAL, Orsay, France

We have developed a special optics with a β^* of 1000 m for two interaction regions (IR1 and IR5) in the LHC, to produce very low divergence beams required for elastic proton-proton scattering. We describe the design, commissioning and operation of this optics in the LHC. The β^* of 1000 m was reached by de-squeezing the beams using 17 intermediate steps beyond the β^* of 90 m, which had been the previous highest β^* value reached in the LHC. The optics was measured and the beta beating globally corrected to a level of 10 per cent.

WEPWA016

Production of Intense High Energy Gamma Beam for LEPS2 Project at SPring-8

laser, injection, storage-ring, electron

2162

T. Yorita, T. Hotta, N. Muramatsu, T. Nakano, M. Oka, M. Yosoi
RCNP, Osaka, Japan
S. Daté, Y. Ohashi, H. Ohkuma, M. Oishi, Y. Okayasu, M. Shoji, S. Suzuki, Y. Taniuchi
JASRI/SPring-8, Hyogo-ken, Japan

Construction of new beam line for LEPS2 Project at SPring-8 has been done and development is now undergoing. LEPS2 is the project for high energy hadron physics using intense high energy gamma beam as probe. The gamma beam is produced by laser backward Compton scattering with injecting high power UV laser into the 8 GeV electron beam on long straight section of SPring-8 storage ring. The target intensities are ~10⁷/s for E_γ=2.4 GeV, ~10⁶/s for E_γ=2.9 GeV.

WEPWA021

X-ray Spectra Reconstruction with HOPG Crystal on TTX

photon, simulation, electron, laser

2174

Z. Zhang, Y.-C. Du, J.F. Hua, W.-H. Huang, C.-X. Tang, D. Wang, L.X. Yan
TUB, Beijing, People's Republic of China

Thomson Scattering sources, as the new generation of bright X-ray sources, have great application potential in many respects. Traditional spectra measurement methods, applied to measured the spectra of Thomson Scattering source, are troublesome as the X-ray beam is too intense to cause pile up problems. In this article, we use the HOPG crystal to reconstruct the X-ray spectra of Tsinghua Thomson X-ray source (TTX) through Braggs law. This method can get reasonable results with single or several shots, with high energy resolution. We also compare the experiment results of this method with the reconstructed spectra by analyzing the attenuation data of the X-ray beam in silicon , and these two results agree well with each other.

WEPME021

Development of CO2 Laser Optical Enhancement Cavity for a Laser-Compton X-ray Source

cavity, laser, polarization, photon

2974

K. Ando, A. Endo, K. Sakaue, T. Takeichi, M. Washio
Waseda University, Tokyo, Japan

Funding: Work supported by NEDO (New Energy and Industrial Technology Development Organization).
We have been developing a laser-Compton X-ray source using optical enhancement cavity. We have studied 1um pulse laser storage in optical cavity and use for the experiments. Usage of 10um laser for optical enhancement cavity will increase the X-ray energy region of one laser-Compton X-ray source, so that we decided to develop the optical cavity for CO2 laser. We have designed external optical cavity for CO2 laser commercially available optics and verified the enhancement of CO2 laser in external optical cavity, and measured fundamental parameters such as finesse, matching efficiency, and enhancement factor. We have already achieved 540 of finesse, 43 of enhancement, and tested non-planer cavity, which storages two circular polarization separately. In this conference, we will report the design and experimental results of CO2 laser storage cavity and also some future prospects.

THPFI024

Application of Electropolishing in CSNS/RCS Primary Collimator Scrapers

cathode, collimation, synchrotron, proton

3348

L. Kang, Z.X. He, H. Qu, J.B. Yu, Y.Q. Zou
IHEP, Beijing, People's Republic of China

According to the requirements for the beam collimation system physical design of the rapid cycling synchrotron (RCS) of China Spallation Neutron Source (CSNS) , the primary collimator scrapers are made of 0.17±0.005mm thickness tungsten sheets. The machining of the tungsten sheet is very difficult because of high hardness and characteristics of the intrinsic brittleness of tungsten. In this paper, electropolishing processing methods is used for tungsten sheets processing. A special electropolishing device is designed according to the principle and process of electropolishing. The processing of tungsten sheets are finally completed after a series of experiments. And the rules of electropolishing for tungsten sheet processing are obtained according to the experimental results.

THPFI029

The Structure Design and Analysis of Proton Beam Window for CSNS

radiation, target, proton, neutron

3361

H.J. Wang, L. Kang, R.H. Liu, H. Qu, D.H. Zhu
IHEP, Beijing, People's Republic of China

The proton beam window (PBW) is one of the key devices of China Spallation Neutron Source (CSNS). In this paper, a new designed PBW structure called single-double layer structure is discussed. The new structure will be used in CSNS, and it is designed based on the beam characteristic of CSNS, which power is 100 kW. The structure design and thermal-analysis are presented, and the convective coefficient of cooling water is calculated. Besides, the radiation damage is discussed to assure there is no danger of radiation lifetime of PBW.

THPFI032

The Design and Analysis of Proton Beam Window for CSNSIII

proton, radiation, target, neutron

3367

H.J. Wang, L. Kang, R.H. Liu, H. Qu, D.H. Zhu
IHEP, Beijing, People's Republic of China

The proton beam window (PBW) is one of the key devices of China Spallation Neutron Source (CSNS). When the beam power of CSNS upgrades from 100kw to 500kw (CSNSIII), the present single-double layer structure of PBW cannot meet the demands. The PBW will be changed to other structure. This paper discusses sandwiched structure and multiple pipe structure, and the later one is chosen as the PBW of CSNSIII. An appropriate convective coefficient of cooling water is chosen, based on which the detailed thermal-stress analysis is presented. Besides, the lifetime is estimated. All these analyses show the designed PBW can work well in CSNSIII.

THPFI058

Qualification of a Glassy Carbon Blade for a LHC Fast Vacuum Valve

vacuum, acceleration, accumulation, background

3424

C. Garion, P. Coly
CERN, Geneva, Switzerland

To protect sensitive LHC machine systems against an unexpected gas inrush, a fast vacuum valve system is under development at CERN. The design of the shutter has to be compatible with dynamic loads occurring during the fast closure, namely in the 20 ms range. The material has to fulfil all main requirements such as transparency, high melting temperature, dust free and adequate leak tightness. A development of a blade in vitreous carbon material has been carried out at CERN. The blade has been successfully integrated in a commercial pendulum fast valve. In this paper, the vacuum and mechanical qualification tests are presented.

THPFI059

Robustness Test of a Silicon Strip Crystal for Crystal-assisted Collimation Studies in the LHC

proton, alignment, collimation, extraction

3427

A. Lechner, J. Blanco Sancho, F. Burkart, M. Calviani, M. Di Castro, Y. Gavrikov, J. Lendaro, F. Loprete, R. Losito, C. Maglioni, A. Masi, S. Montesano, A. Perillo-Marcone, P.S. Roguet, W. Scandale, D. Wollmann
CERN, Geneva, Switzerland
J. Blanco Sancho
EPFL, Lausanne, Switzerland
F. Burkart
IAP, Frankfurt am Main, Germany
Y. Gavrikov
PNPI, Gatchina, Leningrad District, Russia
V. Guidi, A. Mazzolari
INFN-Ferrara, Ferrara, Italy
V. Guidi, A. Mazzolari
UNIFE, Ferrara, Italy
W. Scandale
LAL, Orsay, France

Over the past years, the UA9 experiment has successfully demonstrated the viability of enhancing the collimation efficiency of proton and ion beams in the SPS by means of bent crystals. An extension of UA9 to the LHC has been recently approved. The conditions imposed by the LHC operational environment, in particular the tremendous energy density of the beam, require a reliable understanding of the crystal integrity in view of potential accident scenarios such as an asynchronous beam dump. For this purpose, irradiation tests have been performed at the CERN-HiRadMat facility to examine the mechanical strength of a silicon strip crystal in case of direct beam impact. The tests were carried out using a 440 GeV proton beam of 0.5 mm transverse size. The crystal, 3 mm long in beam direction, was exposed to a total of 2*10¹⁴ protons, with individual pulse intensities reaching up to 3*10¹³. First visual inspections reveal no macroscopic damage to the crystal. Complementary post-irradiation tests are foreseen to assess microscopic lattice damage as well as the degradation of the channelling efficiency.
On behalf of the UA9 Collaboration.

THPFI065

Thermo-mechanical Investigations of the SINQ "Cannelloni" Target

target, simulation, factory, neutron

3445

R. Sobbia, S. Dementjevs, S. Joray, M. Wohlmuther
PSI, Villigen PSI, Switzerland

Numerical results of three-dimensional ANSYS thermo-mechanical simulations of single components of the SINQ target system are presented. Thermal stresses are generated by energy deposition in so-called ‘‘cannelloni'' consisting of a Zircaloy-2 rod filled with Lead to 90% of its inner volume. The molten region of the inner Lead filling is calculated by thermal analysis using the energy deposition profile imported from MCNPX calculations. Induced mechanical stresses are studied for a set of predefined parameters, the heat transfer coefficient and the bulk temperature of the heavy water cooling system. Critical stress regions are investigated to provide possible failure scenarios and overall system performance.

THPWA009

Generation of Laser Compton Scattered Gamma-rays from a 150-MeV Microtron

laser, microtron, neutron, photon

3645

R. Hajima, C.T. Angell, I. Daito, T. Hayakawa, M. Kando, T. Shizuma
JAEA, Ibaraki-ken, Japan
H. Ohgaki
Kyoto University, Institute for Advanced Energy, Kyoto, Japan

Funding: This work was supported in part by special coordination funds for promoting science and technology in Japan (Grant No. 066).
We have developed a laser Compton scattered gamma-ray source based on a 150-MeV racetrack microtron at Japan Atomic Energy Agency. The microtron equipped with a photocathode RF gun accelerates a single bunch of electrons to collide with a laser pulse from a Nd:YAG laser. We have employed laser pulse compression by stimulated Brillouin scattering to obtain high-flux gamma-rays, > 10⁵ ph/s. The gamma-ray source is a prototype of commercial machine for nuclear security applications, non-destructive detection of nuclear material hidden in a ship cargo. Design and performance of the gamma-ray source are presented.

THPWA010

Application of X-band 30 MeV Linac Neutron Source to Nuclear Material Analysis for Fukushima Nuclear Plant Accident

neutron, linac, electron, target

3648

M. Uesaka, K. Dobashi, T. Fujiwara
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
H. Harada
JAEA, Ibaraki-ken, Japan
K. Tagi
University of Tokyo, Tokyo, Japan
M. Yamamoto
Accuthera Inc., Kawasaki, Kanagawa, Japan

We plan to use our X-band (11.424GHz) electron linac as a neutron source for the nuclear analysis for the Fukushima nuclear plant accident. Quantitative material analysis and forensics for nuclear security will start several years later after the safe settlement of the accident is established. For the purpose, we should now accumulate more precise nuclear data of U, Pu, TRU and MA especially in epithermal (0.1-10 eV) neutrons. Therefore, we have decided to move the linac into the core of the experimental nuclear reactor “Yayoi” which is now under the decommission procedure. First we plan to perform the TOF (Time Of Flight) transmission measurement of the total cross sections of the nuclei for 0.1-10 eV neutrons. Electron energy, macro-pulse length, power and neutron yield are ~30 MeV, 100 ns – 1 micros, <0.5 kW and <10¹² n/s, respectively. Optimization of the design of a neutron target (Ta, W, U), TOF line and neutron detector (Ce:LiCAF) of high sensitivity and fast response is underway. Installation, commissioning and measurement starts in 2014. Detailed design and way how to contribute to the analysis of the Fukushima nuclear plant accident will be presented.

THPWO084

Optimization of a Bi-spectral Boxed Side-by-Side Moderator for the Target-Moderator-Reflector System of the ESS

neutron, target, proton, brightness

3957

T. Reiss, U. Filges, V. Talanov, M. Wohlmuther
PSI, Villigen PSI, Switzerland
F. X. Gallmeier
ORNL, Oak Ridge, Tennessee, USA

Providing bi-spectral neutron beams is one of the main neutronics design criteria for the target-moderator-reflector (TMR) system of the European Spallation Source, to be built in Lund (Sweden). As a first step, the requirements of neutronics instruments regarding the neutron spectrum are formulated, a figure of merit is defined. In order to maximize the moderator performance to obtain bi-spectral neutron extraction, a parametrized model of the TMR system is developed and used with a MCNPX-based optimization framework. This model is then used to study and optimize the moderator performance, especially in the thermal and cold parts of the spectrum. Results obtained with an optimized moderator setup are dicussed and compared with the requirements of the instruments.

FRXAA01

Beam Dynamics and Collective Effects in "Ultimate" Storage Rings

emittance, ion, coupling, electron

3981

M. Takao
JASRI/SPring-8, Hyogo-ken, Japan

This presentation will review the beam dynamics issues such as impedance driven instabilities, intrabeam scattering, and the Touschek lifetime in ultimate storage rings with very low emittance.

Slides FRXAA01 [11.245 MB]