IPAC2012 - List of Keywords (beam-losses)

Paper	Title	Other Keywords	Page
MOPPD027	A Compact High Intensity Cyclotron Injector for DAEδALUS Experiment	extraction, cyclotron, resonance, simulation	424
	L. Calabretta, D. Rifuggiato INFN/LNS, Catania, Italy A. Adelmann Paul Scherrer Institut, Villigen, Switzerland A. Calanna, D. Campo CSFNSM, Catania, Italy M.M. Maggiore, L.A.C. Piazza INFN/LNL, Legnaro (PD), Italy J.J. Yang CIAE, Beijing, People's Republic of China
	Funding: Istituto Nazionale di Fisica Nucleare - Laboratori Nazionale del Sud. The experiment DAEδALUS, recently proposed by MIT scientist to search for CP violation in the neutrino sector, needs three accelerator with energy of about 800 MeV, average power of some MW and duty cycle of 20%. To reduce the cost of the accelerators a cyclotron complex consisting of an injector and of a booster ring cyclotron has been proposed. The main characteristics of the new kind of separated sector cyclotron injector able to accelerate a H²⁺ molecule beam up to 60 MeV/n will be presented. Due to the low duty cycle, the peak current to be accelerated is 5 mA. The problem related to the injection of a H²⁺ beam, delivered by a compact ion source, and to the space charge effects will be discussed. To allow an easier injection in the booster Superconducting Ring Cyclotron the extraction energy has been increased up to 60 MeV/n. The pole gap was decreased to 60 mm to achieve a more efficient beam extraction. The updated configuration of the magnetic sectors, of the isochronous magnetic field and beam dynamics along extraction path and during the acceleration will be presented, too. J. Alonso et al., "Novel Search for CP Violation in the Neutrino Sector: DAEδALUS," Jun2010 e-Print: arXiv:1006.0260 ** L. Calabretta, Proc. of IPAC 2011, WEPS073, p. 2673 (2011).

MOPPD052	Study of Electrostatic Septum by Low-Z Material for High Intensity Proton Beam	septum, extraction, scattering, proton	484
	D. Horikawa Sokendai, Ibaraki, Japan Y. Arakaki, K. Okamura, Y. Shirakabe, M. Tomizawa KEK, Ibaraki, Japan I. Sakai University of Fukui, Faculty of Engineering, Fukui, Japan T. Shimogawa Saga University, Faculty of Science and Engineering, Saga, Japan
	In a high-intensity proton accelerator, the beam loss at the time of late beam extraction causes radioactivation of apparatus. It takes out and is a problem serious to that of upper about beam power. Its attention was paid to electric septum (ESS) of the equipment used for beam extraction for problem solving. The septum section of ESS which beam hits directly is usually used for tungsten. Therefore, it is low atomic number material to the septum section. Development of the new model ESS using the textile material carbon fiber of a certain carbon (CF) was started. Is it a problem in CF at processability? Is it using for the septum section of ESS for a certain reason? Difficult it was. Therefore, it succeeded in obtaining required form and intensity by developing the twisting thread technology of CF. Moreover, the tension strength test of CFwire and the pyrogenicity test by electric current were done. Is it the tension intensity and heat durability which exceed the existing tungsten wire? It was confirmed. In addition to the ESS development technique using these new materials, and a result, a future measure is reported.

MOPPD058	LHC Abort Gap Cleaning Studies during Luminosity Operation	luminosity, kicker, injection, emittance	496
	E. Gianfelice-Wendt Fermilab, Batavia, USA W. Bartmann, A. Boccardi, C. Bracco, E. Bravin, B. Goddard, W. Höfle, D. Jacquet, A. Jeff, V. Kain, M. Meddahi, F. Roncarolo, J.A. Uythoven, D. Valuch CERN, Geneva, Switzerland
	The presence of significant intensities of un-bunched beam is a potentially serious issue in the LHC. Procedures using damper kickers for cleaning both Abort Gap (AG) and buckets targeted for injection, are currently in operation at flat bottom. Recent observations of relatively high population of the AG during physics runs brought up the need for AG cleaning during luminosity operation as well. In this paper the results of experimental studies performed in October 2011 are presented.

MOPPD059	Proposal of a Dummy Septum to Mitigate Ring Irradiation for the CERN PS Multi-Turn Extraction	septum, extraction, vacuum, shielding	499
	M. Giovannozzi, H. Bartosik, D. Bodart, J. Borburgh, R.J. Brown, S. Damjanovic, S.S. Gilardoni, B. Goddard, C. Hernalsteens, M. Hourican, M. Widorski CERN, Geneva, Switzerland
	High activation of the magnetic extraction septum of the CERN PS machine was observed due to the losses of the continuous beam extracted via the Multi-Turn Extraction (MTE) method. The resulting activation is however incompatible with safe operation so a mitigation measure was required and found, namely the installation of a passive dummy septum to protect the actual one seems to provide the required reduction in activation in the extraction area. The shielded dummy septum is intended to absorb particles during the rise time of the MTE extraction kickers, avoiding the beam impact on the blade of the active magnetic extraction septum. The principle of the proposed modifications of the PS layout will be presented together with the studies aimed at finalising the new configuration.

MOPPD060	Modified Extraction Scheme for the CERN PS Multi-Turn Extraction	extraction, septum, kicker, quadrupole	502
	M. Giovannozzi, S.S. Gilardoni, C. Hernalsteens, A. Lachaize, G. Métral CERN, Geneva, Switzerland
	High-activation of the extraction magnetic septum of the CERN PS machine was observed due to the losses of the continuous beam extracted via the Multi-Turn Extraction (MTE) method. A possible mitigation measure consists of using an existing electrostatic septum, located upstream of the extraction magnetic septum, to deflect the beam. This would highly decrease the beam losses, and hence the induced activation, during the rise time of the MTE kickers due to the reduced thickness of the electrostatic septum with respect to the magnetic one. The layout of this new extraction will be described in detail and the results of beam measurements presented.

MOPPD072	A High Energy Collimation System for the European Spallation Source	collimation, target, optics, linac	529
	H.D. Thomsen, A.I.S. Holm, S.P. Møller ISA, Aarhus, Denmark
	At the European Spallation Source (ESS), a ~160 m high energy beam transport (HEBT) system is to guide the high-power (5 MW) proton beam from a superconducting 2.5 GeV linac to a spallation target station. The HEBT could include a single-pass collimation system to protect all downstream accelerator components, including the vital target. The system would be built to withstand both continuous low-power losses (i.e. introduce halo reduction) and infrequent short-term, high-power beam exposure, essentially a fault scenario. Although a collimation system could reduce the uncontrolled beam losses and thus activation levels elsewhere, it takes up precious longitudinal space intended for future beam power upgrades and sets demands for the beam optics, as will be discussed. Possible materials and specifications will also be described.

MOPPD075	Optimization of the Collimation System for the CSNS/RCS	collimation, closed-orbit, injection, scattering	538
	N. Wang, M.Y. Huang, S. Wang, S.Y. Xu IHEP, Beijing, People's Republic of China
	Beam loss induced activation of the accelerator components is one of the primary concerns in designing a high intensity machine. The uncontrolled beam loss is required to be less than 1 W/m for hands-on maintenance of the machine. A two stage collimation system is designed in the Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) to localize the beam losses in a restricted area. The parameters of the collimator are optimized in order to obtain high collimation efficiency. The final design of the collimation system is presented. The reliability of the collimation system is estimated for different working points and with closed orbit errors.

MOPPD076	Numerical Study of a Collimation System to Mitigate Beam Losses in the ESS Linac	linac, DTL, collimation, simulation	541
	R. Miyamoto, H. Danared, M. Eshraqi, A. Ponton ESS, Lund, Sweden
	The European Spallation Source (ESS) will be a 5 MW proton linac to produce spallation neutrons. A high power linac has a very low tolerance on beam losses, typically on the order of 1 W/m, to avoid activation of the linac components; hence, emittance and halo of the beam must be well controlled throughout the linac. A system of collimators in beam transport sections has been studied and tested as a means to mitigate the beam losses in several linacs. This paper presents the result of a numerical study of a collimation system for the ESS linac.

MOPPD083	Improving the Fermilab Booster Notching Efficiency, Beam Losses and Radiation Levels	booster, kicker, radiation, injection	562
	I.L. Rakhno, A.I. Drozhdin, N.V. Mokhov, V.I. Sidorov, I.S. Tropin Fermilab, Batavia, USA
	Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. Currently a fast vertical 1.08-m long kicker (notcher) located in the Fermilab Booster Long-5 straight section is used to remove 3 out of 84 circulating bunches after injection to generate an abort gap. With magnetic field of 72.5 Gauss it removes only 87% of the 3-bunch intensity at 400 MeV, with 75% loss on pole tips of the focusing Booster magnets, 11% on the Long-6 collimators, and 1% in the rest of the ring. We propose to improve the notching efficiency and reduce beam loss in the Booster by using two horizontal kickers in the Long-12 section. The STRUCT calculations show that using such horizontal notchers, one can remove up to 99% of the 3-bunch intensity at 400-700 MeV, directing 96% of it to a new beam dump at the Long-13 section. This fully decouples notching and collimation. The beam dump absorbs most of the impinging proton energy in its jaws. The latter are encapsulated into an appropriate radiation shielding that reduces impact on the machine components, personnel and environment to the tolerable levels. The MARS simulations show that corresponding prompt and residual radiation levels can be reduced ten times compared to the current ones.

TUPPC010	Study of Effects of Failure of Beamline Elements and its Compensation in CW Superconducting Linac	linac, cavity, emittance, focusing	1173
	A. Saini, K. Ranjan University of Delhi, Delhi, India C.S. Mishra, J.-F. Ostiguy, N. Solyak, V.P. Yakovlev Fermilab, Batavia, USA
	Project-X is the proposed high intensity proton facility to be built at Fermilab in United States. First stage of the Project-X consists of H^- superconducting linac (SC) which will be operated in continuous wave (CW) mode to accelerate the beam from kinetic energy of 2.1 MeV to 3 GeV. The operation in CW mode puts stringent tolerances on the beam line components, particularly at low energy section. The failure of beam line elements result in mismatch of the beam with the following sections due to different beam parameters than designed parameters. It makes the beam unstable which causes emittance dilution, and ultimately results in beam losses. In worst case, it can affect the reliability of the machine and may lead to the shutdown of the linac to replace the failed elements. Thus, it is important to study impacts of these effects and their compensation to restore linac performance to avoid beam interruption. This paper presents the studies performed for the failure of accelerating cavity and focusing magnets at the critical locations in the Project-X CW superconducting linac

TUPPC081	First Experimental Observations from the LHC Dynamic Aperture Experiment	dynamic-aperture, kicker, synchrotron, injection	1362
	M. Giovannozzi, M. Albert, G.E. Crockford, S.D. Fartoukh, W. Höfle, E.H. Maclean, A. Macpherson, L. Ponce, S. Redaelli, H. Renshall, F. Roncarolo, R.J. Steinhagen, E. Todesco, R. Tomás, W. Venturini Delsolaro CERN, Geneva, Switzerland R. Miyamoto BNL, Upton, Long Island, New York, USA
	Following intensive numerical simulations to compute the dynamic aperture for the LHC in the design phase, the successful beam commissioning and the ensuing beam operations opened the possibility of performing beam measurements of the dynamics aperture. In this paper the experimental set-up and the first observations based on the few experimental sessions performed will be presented and discussed in detail.

TUPPD066	Lifetime Studies of Cs2Te Cathodes at the PHIN RF Photoinjector at CERN	vacuum, cathode, gun, laser	1554
	C. Heßler, E. Chevallay, M. Divall Csatari, S. Döbert, V. Fedosseev CERN, Geneva, Switzerland
	The PHIN photoinjector has been developed to study the feasibility of a photoinjector option for the CLIC (Compact LInear Collider) drive beam as an alternative to the baseline design, using a thermionic gun. The CLIC drive beam requires a high charge of 8.4 nC per bunch in 0.14 ms long trains, with 500 MHz bunch spacing and 50 Hz macro pulse repetition rate, which corresponds to a total charge per macro pulse of 0.59 mC. This means unusually high peak and average currents for photoinjectors and is challenging with respect to the cathode lifetime. In this paper detailed studies of the lifetime of Cs2Te cathodes, produced by the co-evaporation technique, with respect to bunch charge, train length and vacuum level are presented. Furthermore, the impact of the train length and bunch charge on the vacuum level will be discussed and steps to extend the lifetime will be outlined.

TUPPR034	Beam-based Alignment in CTF3 Test Beam Line	quadrupole, alignment, feedback, injection	1894
	G. Sterbini, S. Döbert, R.L. Lillestøl, E. Marín, D. Schulte CERN, Geneva, Switzerland E. Adli University of Oslo, Oslo, Norway
	The CLIC linear collider is based on the two beams acceleration scheme. During acceleration, the drive beam suffers a large increase in its energy spread. In order to efficiently transport such a beam, beam-based alignment techniques together with tight pre-alignment tolerances are crucial. A beam-based steering campaign has been conducted at the Test Beam Line of the CLIC Test Facility to evaluate the performance of several algorithms. In the following we present and discuss the obtained results.

TUPPR092	Transient Beam Losses in the LHC Injection Kickers from Micron Scale Dust Particles	kicker, vacuum, electron, injection	2044
	B. Goddard, P. Adraktas, T. Baer, M.J. Barnes, F. Cerutti, A. Ferrari, N. Garrel, A.H.J. Gerardin, M. Guinchard, A. Lechner, A. Masi, V. Mertens, R. Morón Ballester, S. Redaelli, J.A. Uythoven, V. Vlachoudis, F. Zimmermann CERN, Geneva, Switzerland
	Transient beam losses on a time scale of a few ms have been observed in the LHC injection kickers, occurring mainly shortly after beam injection with a strong correlation in time to the kicker pulsing. The beam losses, which have at times affected LHC availability, are attributed to micron scale ceramic dust particles detached from the alumina beam pipe and accelerated into the beam. The beam related observations are described, together with laboratory measurements of beam pipe contamination and kicker vibration, simulations of electric field in the beam pipe and the basic dynamic model. Energy deposition simulations modelling the beam losses are presented and compared to measurement. Extrapolations to future LHC operation at higher intensities and energies are made, and prospects for mitigation are discussed.

TUPPR096	Angular Alignment of the LHC Injection Protection Stopper	injection, alignment, kicker, proton	2056
	C. Bracco, R.W. Assmann, W. Bartmann, B. Goddard, V. Kain, J.A. Uythoven CERN, Geneva, Switzerland
	Machine safety depends critically on the correct setup of the protection elements. One of the injection protection collimators is constituted by exceptionally long jaws (4 m). For this element, an angular offset of the jaws could affect significantly the measured beam size and, as a consequence, the correct setup with respect to the beam. Dedicated studies and cross-calibrations have been performed to quantify the effect of tilts and offsets on the setup of this collimator and to check the provided passive protection.

TUPPR097	Modeling and Simulation of LHC Beam-Based Collimator Setup	alignment, simulation, emittance, collider	2059
	G. Valentino, N.J. Sammut University of Malta, Information and Communication Technology, Msida, Malta R.W. Assmann, F. Burkart, S. Redaelli, A. Rossi, D. Wollmann CERN, Geneva, Switzerland L. Lari IFIC, Valencia, Spain
	In the 2011 Large Hadron Collider run, collimators were aligned for proton and heavy ion beams using a semi-automatic setup algorithm. The algorithm provided a reduction in the beam time required for setup, an elimination of beam dumps during setup and higher accuracy with respect to manual alignment. A collimator setup simulator was developed based on a Gaussian model of the beam distribution as well as a parametric model of the beam losses. A time-varying beam loss signal can be simulated for a given collimator movement into the beam. The simulation results and comparison to measurement data obtained during collimator setups and dedicated fills for beam halo scraping are presented. The simulator will then be used to develop a fully automatic collimator alignment algorithm.

WEOAA03	Development of the Beam Halo Monitor in the J-PARC 3-GeV RCS	extraction, injection, electron, gun	2122
	M. Yoshimoto, N. Hayashi, H. Hotchi, M. Kinsho, S.I. Meigo, K. Okabe, P.K. Saha, K. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	Transverse beam halo is one of the most important beam parameters due to limit the performance of the high intensity beam accelerator. Therefore the transverse beam halo measurement is required to increase the beam power of the J-PARC 3-GeV RCS. Transverse halo monitors, which are horizontal and vertical scanning aluminum plates type, has been installed in the extraction beam line. But the residual secondary electrons hindered the beam halo diagnostic. Thus we develop the new beam halo monitor with vibrating wire monitor.
	Slides WEOAA03 [6.701 MB]

WEPPD044	Machine Protection System for the SPIRAL2 Facility	controls, diagnostics, target, ion	2612
	M.H. Moscatello, C. Berthe, C. Jamet, G. Normand GANIL, Caen, France
	The phase 1 of the SPIRAL2 facility, extension project of the GANIL laboratory, is under construction. The accelerator is based on a linear solution, mainly composed of a normal conducting RFQ and a superconducting linac. One of its specificities is to be designed to accelerate high power deuteron and heavy ion beams (40-200kW), and medium intensity heavy ion beams as well (a few kW). The associated Machine Protection System, has thus to be able to control and protect the accelerator for a very large range in terms of beam intensities and beam powers. This paper presents the technical solutions chosen for this system and the present status of its construction.

THEPPB005	Study on the Injection Optimization and Transverse Coupling for CSNS/RCS	injection, emittance, collimation, coupling	3240
	M.Y. Huang, J. Qiu, S. Wang, S.Y. Xu IHEP, Beijing, People's Republic of China
	The injection system of the China Spallation Neutron Source uses H⁻ stripping and phase space painting method to fill large ring acceptance with the linac beam of small emittance. The emittance evolution, beam losses, and collimation efficiency during the injection procedures for different injection parameters, such as the injection emittances, starting injection time, twiss parameters and momentum spread, were studied, and then the optimized injection parameters was obtained. In addition, the phase space painting scheme which also affect the emittance evolution and beam losses were simulated and the optimization range of phase space painting were obtained. There will be wobble in the power supply of the injection bumps, and the wobble effects were presented. In order to study the transverse coupling, the injection procedures for different betatron tunes and momentum spreads were studied.

THPPP020	Project X with Superconducting Rapid Cycling Synchrotron	synchrotron, extraction, proton, FEL	3773
	H. Piekarz Fermilab, Batavia, USA
	A synchrotron-based upgrade of Fermilab accelerator complex for high intensity physics with Project X is described. It consists of: 1 GeV pulse linac, 1-8 GeV superconducting rapid cycling synchrotron (SRCS), dual 8 GeV storage ring (SR1,2), and 60 GeV Main Injector(MI). Pulse linac and SRCS operate at 10 Hz while SR1, SR2, and MI operate at 1.33 Hz. SR1 stores 3 and SR2 4 SRCS pulses making physics cycle 0.7 s. SR1 batch is extracted in 0.5 s at 3 locations of its ring providing beams to kaon and 2 muon experiments. SR2 batch is transferred to MI, accelerated to 60 GeV, and extracted to 3 neutrino production targets for Minos, Nova, and LBNE experiments. Main synchrotron parameters are listed and magnet systems described. Projected beam power is compared to expectations with linac-only based upgrade as well as with current and planned similar accelerator facilities elsewhere.

THPPP056	Beam Loss Due to Misalignments, RF Jitter and Mismatch in the Fermilab Project-X 3GeV CW Linac	linac, solenoid, quadrupole, lattice	3868
	J.-P. Carneiro, V.A. Lebedev, S. Nagaitsev, J.-F. Ostiguy, A. Saini, B.G. Shteynas, N. Solyak Fermilab, Batavia, USA
	This paper presents an analysis of beam losses along the current design of the FNAL 3 GeV superconducting cw linac. Simulations from the RFQ exit up to the end of the linac (~430 meters) are performed on the FermiGrid using the beam dynamics code TRACK. The impact of beam mismatch, element misalignments, and RF jitter on the beam dynamics is discussed and corresponding beam loss patterns are presented. A correction scheme to compensate for misalignments is described.

THPPP083	Status of J-PARC 3 GeV RCS	injection, extraction, beam-transport, vacuum	3927
	M. Kinsho JAEA/J-PARC, Tokai-mura, Japan
	J-PARC RCS have delivered beam progressively since 2008. The RCS ramped up the beam power, and delivered beam of 300kW equivalent and 220kW to MR and MLF, respectively, before the earthquake disaster. The RCS was heavily affected by the last Great East Japan Earthquake. At the RCS, the circulating road went wavy and the yard area for electricity and cooling water devices was heavily distorted. We have investigated damages of each device and also have tried to restore beam operation. From middle of December last year we could start beam test and also would start to deliver beam to MR and MLF for user operation from this January. We have been performed not only recovery works but also improvement of the RCS for realizing high power stable operation with low beam losses. I report status of beam operation and near future plan for the RCS.

THPPP086	UFOs in the LHC: Observations, Studies and Extrapolations	simulation, proton, diagnostics, quadrupole	3936
	T. Baer, M.J. Barnes, F. Cerutti, A. Ferrari, N. Garrel, B. Goddard, E.B. Holzer, S. Jackson, A. Lechner, V. Mertens, M. Misiowiec, E. Nebot Del Busto, A. Nordt, J.A. Uythoven, V. Vlachoudis, J. Wenninger, C. Zamantzas, F. Zimmermann CERN, Geneva, Switzerland T. Baer University of Hamburg, Hamburg, Germany N. Fuster Martinez Valencia University, Atomic Molecular and Nuclear Physics Department, Valencia, Spain
	Unidentified falling objects (UFOs) are potentially a major luminosity limitation for nominal LHC operation. They are presumably micrometer sized dust particles which lead to fast beam losses when they interact with the beam. With large-scale increases and optimizations of the beam loss monitor (BLM) thresholds, their impact on LHC availability was mitigated from mid 2011 onwards. For higher beam energy and lower magnet quench limits, the problem is expected to be considerably worse, though. In 2011/12, the diagnostics for UFO events were significantly improved: dedicated experiments and measurements in the LHC and in the laboratory were made and complemented by FLUKA simulations and theoretical studies. The state of knowledge, extrapolations for nominal LHC operation and mitigation strategies are presented.

THPPR037	Estimation of Thresholds for the Signals of the BLMs around the LHC Final Focus Triplet Magnets	proton, simulation, radiation, luminosity	4053
	M. Sapinski, F. Cerutti, B. Dehning, A. Ferrari, A. Lechner, M. Mauri, A. Mereghetti CERN, Geneva, Switzerland C. Hoa CEA-CENG, Grenoble, France
	The Interaction Points of the Large Hadron Collider are the regions where the two circulating beams collide. Hence, the magnets the closest to any Interaction Point are exposed to an elevated radiation field due to the collision debris. In this study the signal in the Beam Loss Monitors due to the debris is estimated and compared with the measurements. In addition, the energy density in the coils and the signal in the Beam Loss Monitors at quench are estimated for various beam loss scenarios. It is shown that the Beam Loss Monitors, as presently installed on the outside of the vacuum vessel of the magnets, cannot disentangle the signals due to a localised halo loss from that of the constant signal due to the collision debris.

Paper

Title

Other Keywords

Page

MOPPD027

A Compact High Intensity Cyclotron Injector for DAEδALUS Experiment

extraction, cyclotron, resonance, simulation

424

L. Calabretta, D. Rifuggiato
INFN/LNS, Catania, Italy
A. Adelmann
Paul Scherrer Institut, Villigen, Switzerland
A. Calanna, D. Campo
CSFNSM, Catania, Italy
M.M. Maggiore, L.A.C. Piazza
INFN/LNL, Legnaro (PD), Italy
J.J. Yang
CIAE, Beijing, People's Republic of China

Funding: Istituto Nazionale di Fisica Nucleare - Laboratori Nazionale del Sud.
The experiment DAEδALUS*, recently proposed by MIT scientist to search for CP violation in the neutrino sector, needs three accelerator with energy of about 800 MeV, average power of some MW and duty cycle of 20%. To reduce the cost of the accelerators a cyclotron complex consisting of an injector and of a booster ring cyclotron has been proposed**. The main characteristics of the new kind of separated sector cyclotron injector able to accelerate a H²⁺ molecule beam up to 60 MeV/n will be presented. Due to the low duty cycle, the peak current to be accelerated is 5 mA. The problem related to the injection of a H²⁺ beam, delivered by a compact ion source, and to the space charge effects will be discussed. To allow an easier injection in the booster Superconducting Ring Cyclotron the extraction energy has been increased up to 60 MeV/n. The pole gap was decreased to 60 mm to achieve a more efficient beam extraction. The updated configuration of the magnetic sectors, of the isochronous magnetic field and beam dynamics along extraction path and during the acceleration will be presented, too.
* J. Alonso et al., "Novel Search for CP Violation in the Neutrino Sector: DAEδALUS," Jun2010 e-Print: arXiv:1006.0260
** L. Calabretta, Proc. of IPAC 2011, WEPS073, p. 2673 (2011).

MOPPD052

Study of Electrostatic Septum by Low-Z Material for High Intensity Proton Beam

septum, extraction, scattering, proton

484

D. Horikawa
Sokendai, Ibaraki, Japan
Y. Arakaki, K. Okamura, Y. Shirakabe, M. Tomizawa
KEK, Ibaraki, Japan
I. Sakai
University of Fukui, Faculty of Engineering, Fukui, Japan
T. Shimogawa
Saga University, Faculty of Science and Engineering, Saga, Japan

In a high-intensity proton accelerator, the beam loss at the time of late beam extraction causes radioactivation of apparatus. It takes out and is a problem serious to that of upper about beam power. Its attention was paid to electric septum (ESS) of the equipment used for beam extraction for problem solving. The septum section of ESS which beam hits directly is usually used for tungsten. Therefore, it is low atomic number material to the septum section. Development of the new model ESS using the textile material carbon fiber of a certain carbon (CF) was started. Is it a problem in CF at processability? Is it using for the septum section of ESS for a certain reason? Difficult it was. Therefore, it succeeded in obtaining required form and intensity by developing the twisting thread technology of CF. Moreover, the tension strength test of CFwire and the pyrogenicity test by electric current were done. Is it the tension intensity and heat durability which exceed the existing tungsten wire? It was confirmed. In addition to the ESS development technique using these new materials, and a result, a future measure is reported.

MOPPD058

LHC Abort Gap Cleaning Studies during Luminosity Operation

luminosity, kicker, injection, emittance

496

E. Gianfelice-Wendt
Fermilab, Batavia, USA
W. Bartmann, A. Boccardi, C. Bracco, E. Bravin, B. Goddard, W. Höfle, D. Jacquet, A. Jeff, V. Kain, M. Meddahi, F. Roncarolo, J.A. Uythoven, D. Valuch
CERN, Geneva, Switzerland

The presence of significant intensities of un-bunched beam is a potentially serious issue in the LHC. Procedures using damper kickers for cleaning both Abort Gap (AG) and buckets targeted for injection, are currently in operation at flat bottom. Recent observations of relatively high population of the AG during physics runs brought up the need for AG cleaning during luminosity operation as well. In this paper the results of experimental studies performed in October 2011 are presented.

MOPPD059

Proposal of a Dummy Septum to Mitigate Ring Irradiation for the CERN PS Multi-Turn Extraction

septum, extraction, vacuum, shielding

499

M. Giovannozzi, H. Bartosik, D. Bodart, J. Borburgh, R.J. Brown, S. Damjanovic, S.S. Gilardoni, B. Goddard, C. Hernalsteens, M. Hourican, M. Widorski
CERN, Geneva, Switzerland

High activation of the magnetic extraction septum of the CERN PS machine was observed due to the losses of the continuous beam extracted via the Multi-Turn Extraction (MTE) method. The resulting activation is however incompatible with safe operation so a mitigation measure was required and found, namely the installation of a passive dummy septum to protect the actual one seems to provide the required reduction in activation in the extraction area. The shielded dummy septum is intended to absorb particles during the rise time of the MTE extraction kickers, avoiding the beam impact on the blade of the active magnetic extraction septum. The principle of the proposed modifications of the PS layout will be presented together with the studies aimed at finalising the new configuration.

MOPPD060

Modified Extraction Scheme for the CERN PS Multi-Turn Extraction

extraction, septum, kicker, quadrupole

502

M. Giovannozzi, S.S. Gilardoni, C. Hernalsteens, A. Lachaize, G. Métral
CERN, Geneva, Switzerland

High-activation of the extraction magnetic septum of the CERN PS machine was observed due to the losses of the continuous beam extracted via the Multi-Turn Extraction (MTE) method. A possible mitigation measure consists of using an existing electrostatic septum, located upstream of the extraction magnetic septum, to deflect the beam. This would highly decrease the beam losses, and hence the induced activation, during the rise time of the MTE kickers due to the reduced thickness of the electrostatic septum with respect to the magnetic one. The layout of this new extraction will be described in detail and the results of beam measurements presented.

MOPPD072

A High Energy Collimation System for the European Spallation Source

collimation, target, optics, linac

529

H.D. Thomsen, A.I.S. Holm, S.P. Møller
ISA, Aarhus, Denmark

At the European Spallation Source (ESS), a ~160 m high energy beam transport (HEBT) system is to guide the high-power (5 MW) proton beam from a superconducting 2.5 GeV linac to a spallation target station. The HEBT could include a single-pass collimation system to protect all downstream accelerator components, including the vital target. The system would be built to withstand both continuous low-power losses (i.e. introduce halo reduction) and infrequent short-term, high-power beam exposure, essentially a fault scenario. Although a collimation system could reduce the uncontrolled beam losses and thus activation levels elsewhere, it takes up precious longitudinal space intended for future beam power upgrades and sets demands for the beam optics, as will be discussed. Possible materials and specifications will also be described.

MOPPD075

Optimization of the Collimation System for the CSNS/RCS

collimation, closed-orbit, injection, scattering

538

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

Beam loss induced activation of the accelerator components is one of the primary concerns in designing a high intensity machine. The uncontrolled beam loss is required to be less than 1 W/m for hands-on maintenance of the machine. A two stage collimation system is designed in the Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) to localize the beam losses in a restricted area. The parameters of the collimator are optimized in order to obtain high collimation efficiency. The final design of the collimation system is presented. The reliability of the collimation system is estimated for different working points and with closed orbit errors.

MOPPD076

Numerical Study of a Collimation System to Mitigate Beam Losses in the ESS Linac

linac, DTL, collimation, simulation

541

R. Miyamoto, H. Danared, M. Eshraqi, A. Ponton
ESS, Lund, Sweden

The European Spallation Source (ESS) will be a 5 MW proton linac to produce spallation neutrons. A high power linac has a very low tolerance on beam losses, typically on the order of 1 W/m, to avoid activation of the linac components; hence, emittance and halo of the beam must be well controlled throughout the linac. A system of collimators in beam transport sections has been studied and tested as a means to mitigate the beam losses in several linacs. This paper presents the result of a numerical study of a collimation system for the ESS linac.

MOPPD083

Improving the Fermilab Booster Notching Efficiency, Beam Losses and Radiation Levels

booster, kicker, radiation, injection

562

I.L. Rakhno, A.I. Drozhdin, N.V. Mokhov, V.I. Sidorov, I.S. Tropin
Fermilab, Batavia, USA

Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
Currently a fast vertical 1.08-m long kicker (notcher) located in the Fermilab Booster Long-5 straight section is used to remove 3 out of 84 circulating bunches after injection to generate an abort gap. With magnetic field of 72.5 Gauss it removes only 87% of the 3-bunch intensity at 400 MeV, with 75% loss on pole tips of the focusing Booster magnets, 11% on the Long-6 collimators, and 1% in the rest of the ring. We propose to improve the notching efficiency and reduce beam loss in the Booster by using two horizontal kickers in the Long-12 section. The STRUCT calculations show that using such horizontal notchers, one can remove up to 99% of the 3-bunch intensity at 400-700 MeV, directing 96% of it to a new beam dump at the Long-13 section. This fully decouples notching and collimation. The beam dump absorbs most of the impinging proton energy in its jaws. The latter are encapsulated into an appropriate radiation shielding that reduces impact on the machine components, personnel and environment to the tolerable levels. The MARS simulations show that corresponding prompt and residual radiation levels can be reduced ten times compared to the current ones.

TUPPC010

Study of Effects of Failure of Beamline Elements and its Compensation in CW Superconducting Linac

linac, cavity, emittance, focusing

1173

A. Saini, K. Ranjan
University of Delhi, Delhi, India
C.S. Mishra, J.-F. Ostiguy, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA

Project-X is the proposed high intensity proton facility to be built at Fermilab in United States. First stage of the Project-X consists of H^- superconducting linac (SC) which will be operated in continuous wave (CW) mode to accelerate the beam from kinetic energy of 2.1 MeV to 3 GeV. The operation in CW mode puts stringent tolerances on the beam line components, particularly at low energy section. The failure of beam line elements result in mismatch of the beam with the following sections due to different beam parameters than designed parameters. It makes the beam unstable which causes emittance dilution, and ultimately results in beam losses. In worst case, it can affect the reliability of the machine and may lead to the shutdown of the linac to replace the failed elements. Thus, it is important to study impacts of these effects and their compensation to restore linac performance to avoid beam interruption. This paper presents the studies performed for the failure of accelerating cavity and focusing magnets at the critical locations in the Project-X CW superconducting linac

TUPPC081

First Experimental Observations from the LHC Dynamic Aperture Experiment

dynamic-aperture, kicker, synchrotron, injection

1362

M. Giovannozzi, M. Albert, G.E. Crockford, S.D. Fartoukh, W. Höfle, E.H. Maclean, A. Macpherson, L. Ponce, S. Redaelli, H. Renshall, F. Roncarolo, R.J. Steinhagen, E. Todesco, R. Tomás, W. Venturini Delsolaro
CERN, Geneva, Switzerland
R. Miyamoto
BNL, Upton, Long Island, New York, USA

Following intensive numerical simulations to compute the dynamic aperture for the LHC in the design phase, the successful beam commissioning and the ensuing beam operations opened the possibility of performing beam measurements of the dynamics aperture. In this paper the experimental set-up and the first observations based on the few experimental sessions performed will be presented and discussed in detail.

TUPPD066

Lifetime Studies of Cs2Te Cathodes at the PHIN RF Photoinjector at CERN

vacuum, cathode, gun, laser

1554

C. Heßler, E. Chevallay, M. Divall Csatari, S. Döbert, V. Fedosseev
CERN, Geneva, Switzerland

The PHIN photoinjector has been developed to study the feasibility of a photoinjector option for the CLIC (Compact LInear Collider) drive beam as an alternative to the baseline design, using a thermionic gun. The CLIC drive beam requires a high charge of 8.4 nC per bunch in 0.14 ms long trains, with 500 MHz bunch spacing and 50 Hz macro pulse repetition rate, which corresponds to a total charge per macro pulse of 0.59 mC. This means unusually high peak and average currents for photoinjectors and is challenging with respect to the cathode lifetime. In this paper detailed studies of the lifetime of Cs2Te cathodes, produced by the co-evaporation technique, with respect to bunch charge, train length and vacuum level are presented. Furthermore, the impact of the train length and bunch charge on the vacuum level will be discussed and steps to extend the lifetime will be outlined.

TUPPR034

Beam-based Alignment in CTF3 Test Beam Line

quadrupole, alignment, feedback, injection

1894

G. Sterbini, S. Döbert, R.L. Lillestøl, E. Marín, D. Schulte
CERN, Geneva, Switzerland
E. Adli
University of Oslo, Oslo, Norway

The CLIC linear collider is based on the two beams acceleration scheme. During acceleration, the drive beam suffers a large increase in its energy spread. In order to efficiently transport such a beam, beam-based alignment techniques together with tight pre-alignment tolerances are crucial. A beam-based steering campaign has been conducted at the Test Beam Line of the CLIC Test Facility to evaluate the performance of several algorithms. In the following we present and discuss the obtained results.

TUPPR092

Transient Beam Losses in the LHC Injection Kickers from Micron Scale Dust Particles

kicker, vacuum, electron, injection

2044

B. Goddard, P. Adraktas, T. Baer, M.J. Barnes, F. Cerutti, A. Ferrari, N. Garrel, A.H.J. Gerardin, M. Guinchard, A. Lechner, A. Masi, V. Mertens, R. Morón Ballester, S. Redaelli, J.A. Uythoven, V. Vlachoudis, F. Zimmermann
CERN, Geneva, Switzerland

Transient beam losses on a time scale of a few ms have been observed in the LHC injection kickers, occurring mainly shortly after beam injection with a strong correlation in time to the kicker pulsing. The beam losses, which have at times affected LHC availability, are attributed to micron scale ceramic dust particles detached from the alumina beam pipe and accelerated into the beam. The beam related observations are described, together with laboratory measurements of beam pipe contamination and kicker vibration, simulations of electric field in the beam pipe and the basic dynamic model. Energy deposition simulations modelling the beam losses are presented and compared to measurement. Extrapolations to future LHC operation at higher intensities and energies are made, and prospects for mitigation are discussed.

TUPPR096

Angular Alignment of the LHC Injection Protection Stopper

injection, alignment, kicker, proton

2056

C. Bracco, R.W. Assmann, W. Bartmann, B. Goddard, V. Kain, J.A. Uythoven
CERN, Geneva, Switzerland

Machine safety depends critically on the correct setup of the protection elements. One of the injection protection collimators is constituted by exceptionally long jaws (4 m). For this element, an angular offset of the jaws could affect significantly the measured beam size and, as a consequence, the correct setup with respect to the beam. Dedicated studies and cross-calibrations have been performed to quantify the effect of tilts and offsets on the setup of this collimator and to check the provided passive protection.

TUPPR097

Modeling and Simulation of LHC Beam-Based Collimator Setup

alignment, simulation, emittance, collider

2059

G. Valentino, N.J. Sammut
University of Malta, Information and Communication Technology, Msida, Malta
R.W. Assmann, F. Burkart, S. Redaelli, A. Rossi, D. Wollmann
CERN, Geneva, Switzerland
L. Lari
IFIC, Valencia, Spain

In the 2011 Large Hadron Collider run, collimators were aligned for proton and heavy ion beams using a semi-automatic setup algorithm. The algorithm provided a reduction in the beam time required for setup, an elimination of beam dumps during setup and higher accuracy with respect to manual alignment. A collimator setup simulator was developed based on a Gaussian model of the beam distribution as well as a parametric model of the beam losses. A time-varying beam loss signal can be simulated for a given collimator movement into the beam. The simulation results and comparison to measurement data obtained during collimator setups and dedicated fills for beam halo scraping are presented. The simulator will then be used to develop a fully automatic collimator alignment algorithm.

WEOAA03

Development of the Beam Halo Monitor in the J-PARC 3-GeV RCS

extraction, injection, electron, gun

2122

M. Yoshimoto, N. Hayashi, H. Hotchi, M. Kinsho, S.I. Meigo, K. Okabe, P.K. Saha, K. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

Transverse beam halo is one of the most important beam parameters due to limit the performance of the high intensity beam accelerator. Therefore the transverse beam halo measurement is required to increase the beam power of the J-PARC 3-GeV RCS. Transverse halo monitors, which are horizontal and vertical scanning aluminum plates type, has been installed in the extraction beam line. But the residual secondary electrons hindered the beam halo diagnostic. Thus we develop the new beam halo monitor with vibrating wire monitor.

Slides WEOAA03 [6.701 MB]

WEPPD044

Machine Protection System for the SPIRAL2 Facility

controls, diagnostics, target, ion

2612

M.H. Moscatello, C. Berthe, C. Jamet, G. Normand
GANIL, Caen, France

The phase 1 of the SPIRAL2 facility, extension project of the GANIL laboratory, is under construction. The accelerator is based on a linear solution, mainly composed of a normal conducting RFQ and a superconducting linac. One of its specificities is to be designed to accelerate high power deuteron and heavy ion beams (40-200kW), and medium intensity heavy ion beams as well (a few kW). The associated Machine Protection System, has thus to be able to control and protect the accelerator for a very large range in terms of beam intensities and beam powers. This paper presents the technical solutions chosen for this system and the present status of its construction.

THEPPB005

Study on the Injection Optimization and Transverse Coupling for CSNS/RCS

injection, emittance, collimation, coupling

3240

M.Y. Huang, J. Qiu, S. Wang, S.Y. Xu
IHEP, Beijing, People's Republic of China

The injection system of the China Spallation Neutron Source uses H⁻ stripping and phase space painting method to fill large ring acceptance with the linac beam of small emittance. The emittance evolution, beam losses, and collimation efficiency during the injection procedures for different injection parameters, such as the injection emittances, starting injection time, twiss parameters and momentum spread, were studied, and then the optimized injection parameters was obtained. In addition, the phase space painting scheme which also affect the emittance evolution and beam losses were simulated and the optimization range of phase space painting were obtained. There will be wobble in the power supply of the injection bumps, and the wobble effects were presented. In order to study the transverse coupling, the injection procedures for different betatron tunes and momentum spreads were studied.

THPPP020

Project X with Superconducting Rapid Cycling Synchrotron

synchrotron, extraction, proton, FEL

3773

H. Piekarz
Fermilab, Batavia, USA

A synchrotron-based upgrade of Fermilab accelerator complex for high intensity physics with Project X is described. It consists of: 1 GeV pulse linac, 1-8 GeV superconducting rapid cycling synchrotron (SRCS), dual 8 GeV storage ring (SR1,2), and 60 GeV Main Injector(MI). Pulse linac and SRCS operate at 10 Hz while SR1, SR2, and MI operate at 1.33 Hz. SR1 stores 3 and SR2 4 SRCS pulses making physics cycle 0.7 s. SR1 batch is extracted in 0.5 s at 3 locations of its ring providing beams to kaon and 2 muon experiments. SR2 batch is transferred to MI, accelerated to 60 GeV, and extracted to 3 neutrino production targets for Minos, Nova, and LBNE experiments. Main synchrotron parameters are listed and magnet systems described. Projected beam power is compared to expectations with linac-only based upgrade as well as with current and planned similar accelerator facilities elsewhere.

THPPP056

Beam Loss Due to Misalignments, RF Jitter and Mismatch in the Fermilab Project-X 3GeV CW Linac

linac, solenoid, quadrupole, lattice

3868

J.-P. Carneiro, V.A. Lebedev, S. Nagaitsev, J.-F. Ostiguy, A. Saini, B.G. Shteynas, N. Solyak
Fermilab, Batavia, USA

This paper presents an analysis of beam losses along the current design of the FNAL 3 GeV superconducting cw linac. Simulations from the RFQ exit up to the end of the linac (~430 meters) are performed on the FermiGrid using the beam dynamics code TRACK. The impact of beam mismatch, element misalignments, and RF jitter on the beam dynamics is discussed and corresponding beam loss patterns are presented. A correction scheme to compensate for misalignments is described.

THPPP083

Status of J-PARC 3 GeV RCS

injection, extraction, beam-transport, vacuum

3927

M. Kinsho
JAEA/J-PARC, Tokai-mura, Japan

J-PARC RCS have delivered beam progressively since 2008. The RCS ramped up the beam power, and delivered beam of 300kW equivalent and 220kW to MR and MLF, respectively, before the earthquake disaster. The RCS was heavily affected by the last Great East Japan Earthquake. At the RCS, the circulating road went wavy and the yard area for electricity and cooling water devices was heavily distorted. We have investigated damages of each device and also have tried to restore beam operation. From middle of December last year we could start beam test and also would start to deliver beam to MR and MLF for user operation from this January. We have been performed not only recovery works but also improvement of the RCS for realizing high power stable operation with low beam losses. I report status of beam operation and near future plan for the RCS.

THPPP086

UFOs in the LHC: Observations, Studies and Extrapolations

simulation, proton, diagnostics, quadrupole

3936

T. Baer, M.J. Barnes, F. Cerutti, A. Ferrari, N. Garrel, B. Goddard, E.B. Holzer, S. Jackson, A. Lechner, V. Mertens, M. Misiowiec, E. Nebot Del Busto, A. Nordt, J.A. Uythoven, V. Vlachoudis, J. Wenninger, C. Zamantzas, F. Zimmermann
CERN, Geneva, Switzerland
T. Baer
University of Hamburg, Hamburg, Germany
N. Fuster Martinez
Valencia University, Atomic Molecular and Nuclear Physics Department, Valencia, Spain

Unidentified falling objects (UFOs) are potentially a major luminosity limitation for nominal LHC operation. They are presumably micrometer sized dust particles which lead to fast beam losses when they interact with the beam. With large-scale increases and optimizations of the beam loss monitor (BLM) thresholds, their impact on LHC availability was mitigated from mid 2011 onwards. For higher beam energy and lower magnet quench limits, the problem is expected to be considerably worse, though. In 2011/12, the diagnostics for UFO events were significantly improved: dedicated experiments and measurements in the LHC and in the laboratory were made and complemented by FLUKA simulations and theoretical studies. The state of knowledge, extrapolations for nominal LHC operation and mitigation strategies are presented.

THPPR037

Estimation of Thresholds for the Signals of the BLMs around the LHC Final Focus Triplet Magnets

proton, simulation, radiation, luminosity

4053

M. Sapinski, F. Cerutti, B. Dehning, A. Ferrari, A. Lechner, M. Mauri, A. Mereghetti
CERN, Geneva, Switzerland
C. Hoa
CEA-CENG, Grenoble, France

The Interaction Points of the Large Hadron Collider are the regions where the two circulating beams collide. Hence, the magnets the closest to any Interaction Point are exposed to an elevated radiation field due to the collision debris. In this study the signal in the Beam Loss Monitors due to the debris is estimated and compared with the measurements. In addition, the energy density in the coils and the signal in the Beam Loss Monitors at quench are estimated for various beam loss scenarios. It is shown that the Beam Loss Monitors, as presently installed on the outside of the vacuum vessel of the magnets, cannot disentangle the signals due to a localised halo loss from that of the constant signal due to the collision debris.