IPAC2017 - List of Keywords (shielding)

Paper	Title	Other Keywords	Page
MOPAB004	Improved Protection of the Warm Magnets of the LHC Betatron Cleaning Insertion	radiation, operation, luminosity, collimation	72
	C. Bahamonde Castro, F. Cerutti, P. Fessia, A. Lechner, A. Mereghetti, D. Mirarchi, S. Redaelli, E. Skordis CERN, Geneva, Switzerland E. Skordis The University of Liverpool, Liverpool, United Kingdom
	After the High Luminosity (HL) upgrade in 2024-2026, the LHC is anticipated to increase its integrated luminosity by a factor of 10 beyond its original design value of 300 fb-1. In preparation for this, several improvements to the equipment will already be implemented during the next Long Shutdown (LS2) starting in 2019. In the betatron cleaning insertion, the debris leaking out of several collimators will deposit energy in the downstream warm magnets, causing long-term radiation damage. A new layout has been proposed in which the most exposed magnet of each assembly is removed, reducing the assembly from 6 to 5 magnet units and gaining 2 spare magnets. New absorbers are therefore required to enhance the shielding of the remaining magnet string. In this paper, we present an evaluation of the dose to the warm magnets for post-LS2 operation, and we quantify the achievable reduction of the long-term radiation damage for different absorber configurations. A solution for an improved magnet protection that fulfills the HL-LHC requirements is proposed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB004
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MOPIK015	Improvement of Electron Intensity Reduction System at SLRI Beam Test Facility	electron, target, synchrotron, booster	528
	K. Kittimanapun, N. Chanlek, P. Klysubun, S. Krainara, S. Supajeerapan SLRI, Nakhon Ratchasima, Thailand
	Funding: This work is partly supported by the National Science and Technology Development Agency (NSTDA) under contract FDA-C0-2558-855-TH. Synchrotron Light Research Institute (SLRI) has been commissioning an additional experimental station, a Beam Test Facility (BTF), to the SLRI accelerator complex. SLRI BTF was constructed to provide electron test beams with energy ranging from 40 MeV up to 1.2 GeV and with tunable electron intensity from a few to millions of electrons per burst. In order to obtain low intensity of test beams, an approach using a metal target together with an energy selector has been employed. A combination of a target chamber installed at the high energy beam transport line and the existing 4-degree bending magnet that is used as an energy selector first produced low intensity test beams. However, the test beam profile was not well determined due to the insufficient bending angle of the energy selector and high primary beam energy. Another approach mounting a target chamber at the low energy beam transport line and using the synchrotron booster as an energy selector was implemented to avoid such problems. Once in operation, the facility will have the potential to service calibration and testing of high energy detectors as well as beam diagnostic instrumentations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK015
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MOPIK035	New Injection Scheme of J-PARC Rapid Cycling Synchrotron	injection, proton, operation, synchrotron	579
	K. Yamamoto, H. Harada, H. Hotchi, J. Kamiya, P.K. Saha, T. Takayanagi, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan N. Miki, O. Takeda Nippon Advanced Technology Co., Ltd., Tokai, Japan
	The 3-GeV Rapid Cycling Synchrotron (RCS) of Japan Proton Accelerator Research Complex (J-PARC) aims to deliver 1-MW proton beam to the neutron target and Main Ring synchrotron (MR). Present beam power of RCS is up to 500-kW and the higher radiation doses were concentrated in the injection area. These activations were caused by the interaction between the foil and the beam. To reduce the worker dose near the injection point, we have studied new design of the injection scheme to secure enough space for radiation shielding and bellows. In the new system, two of four injection pulse bump magnets are replaced and we are able to ensure the additional 500 mm space at the injection foil .
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK035
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MOPIK077	Impact of Dynamical Stray Fields on CLIC	collimation, luminosity, synchrotron, linear-collider	708
	E. Marín, D. Schulte CERN, Geneva, Switzerland B. Heilig MFGI, Budapest, Hungary J. Pfingstner University of Oslo, Oslo, Norway
	In this paper we estimate the tolerances of stray-fields variations on the Compact Linear Collider (CLIC), discuss possible sources and propose several solutions. The Beam Delivery System (BDS) is the most sensitive system of CLIC to unwanted magnetic field variations, already variations of 1 nT would reduce the luminosity by 10% at wavelengths comparable to the BDS without considering any correction mechanism. Two sources of magnetic field variations are considered, natural and man-made. Precise magnetic field measurements at Earth's surface under a typical geomagnetic storm are presented. Additionally, stray field measurements have been conducted at CERN, to inspect B-field variations due to technical equipment in an accelerator environment. Different solutions are proposed to minimise the impact of stray fields on the CLIC performance.
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MOPIK102	Beam Dynamics Studies of the HIE-ISOLDE Transfer Lines in the Presence of Magnetic Stray Fields	quadrupole, experiment, operation, solenoid	768
	J. Mertens, J. Bauche, M.A. Fraser, B. Goddard, R. Ostojić, J.S. Schmidt CERN, Geneva, Switzerland
	The ISOLDE facility at CERN produces radioactive isotopes far from stability for fundamental nuclear physics research. The radioactive beams are accelerated to high-energy using a post-accelerator before being transferred for study in different experiments at the end of a network of High Energy Beam Transfer (HEBT) lines. In the framework of the HIE-ISOLDE project, the energy of post-accelerated beams is to be increased to over 10 MeV/u and new experimental detectors are being proposed for installation to exploit the new energy regime. The stray magnetic fields associated with many of the new detectors will distort the beam trajectories in the HEBT, potentially affecting the transmission of the low intensity beams delivered to the experiments. In this contribution, the influence on the HEBT of the stray field of the proposed ISOL Solenoidal Spectrometer is discussed, correction schemes described and shielding options assessed.
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TUPAB107	Study of 60 Hz Beam Orbit Fluctuations in the Taiwan Photon Source	SRF, vacuum, photon, insertion-device	1566
	C.H. Huang, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, K.H. Hu, C.Y. Liao, C.Y. Wu NSRRC, Hsinchu, Taiwan
	The Taiwan Photon Source is a 3 GeV synchrotron light source at NSRRC. To achieve high quality experimental results, it is important to minimize beam motion. During the installation of insertion devices and front-ends, the beam motion around 60 Hz became significant. The response matrix together with singular value decomposition was used to identify the transmitter of the superconducting radio frequency system as the source for the 60 Hz perturbations. This was subsequently corrected by rerouting the grounding of the mains in the transmitters. Yet, the 60Hz orbit fluctuation became even more serious after the next shutdown. A serious of experiments are performed to dig out that the beam was disturbed by the magnetic field from newly installed fan motors. Shielding the fans with mu-metal and increasing the distance between fan and beam pipe drastically reduced the leakage field and greatly increased beam stability. These errors could be prevented at the design stage in the ideal case. However, these errors happened finally and need to be dug out and eliminated. The method and experiences are summarized in this report. These will benefit others who facing the similar problems.
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TUPAB133	Perturbation Analysis for Beam Trajectories. Determining Local Shielding Containment for LCLS-II	quadrupole, simulation, dipole, undulator	1637
	M. Santana-Leitner SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515 Containment of beam losses by halo and momentum/energy collimators is a well-established practice for normal operation of particle accelerators where tracking codes are applied. However, for exceptional events, such as magnet power failures, severe lattice mis-match, etc., ad-hoc analytical approaches are typically applied. Oftentimes those simplified methods are not automatic; they don't define the full phase-space of mis-steered trajectories and cannot keep up with beam-line upgrades. Moreover, there may exist a disconnect between the teams analyzing consequences of errant beams and those involved in beam-line design. With electron beams exceeding 100 kW, design of LCLS-II at SLAC National Accelerator Laboratory required exhaustive beam-containment studies to avoid potential destruction of components and excessive dose rates. The geometry of the different beam-lines and the nominal optics was built with MadFLUKA [1], and FLUKA [2] Monte Carlo code along with perturbations to magnetic fields was used to inspect failures compatible with beam operations and hardware settings. Consequences of mis-steered rays and the respective mitigations were directly analyzed with FLUKA. [1] M. Santana-Leitner et al., MadFLUKA Beam Line 3D Builder. Simulation of Beam Loss Propagation in Accelerators, IPAC14 proceedings, MOPME040 [2] A. Ferrari et al, The FLUKA Code: Developments and Challenges for High Energy and Medical Applications, Nuclear Data Sheets 120, 211-214 (2014)
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TUPIK034	NSC KIPT Neutron Source on the Base of Subcritical Assembly With Electron Linear Accelerator Driver	neutron, target, electron, operation	1754
	A.Y. Zelinsky, I.M. Karnaukhov, A. Mytsykov, I. Ushakov NSC/KIPT, Kharkov, Ukraine Y.L. Chi IHEP, Beijing, People's Republic of China Y. Gohar ANL, Argonne, Illinois, USA
	National Science Center Kharkov Institute of Physics & Technology (NSC KIPT) together with ANL, Chicago, USA developed up to date scientific facility that is Neutron Source on the base of subcritical assembly driven with 100 MeV/100 kW electron accelerator. During bombarding of the Tungsten or Uranium targets the electron beam generates the original neutrons that are multiplied in the facility core of low enriched uranium trough the fission process. The maximal value of the neutron multiplication factor is 0.98. So the total neutron flux output is increased as much as 50 times and is 2·10 13 n·cm^-2·c-1. The subcriticality of the system eliminates the possibility of self-sustained chain reaction existence that increases the nuclear safety of the facility drastically. The neutron source mentioned above is the first facility of such type in the world. The results that will be obtained at studies of neutron characteristics of the neutron source with low enriched uranium core and during optimization of the operation modes of the facility systems will became the scientific background for the further development of the safe, ecological nuclear energetics of the future.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK034
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TUPIK066	Beam Loss Simulation and Radiation Shielding for Top-Off Operation of Hefei Light Source	electron, storage-ring, injection, simulation	1845
	X. Zhou, J.Y. Li, J.G. Wang, S.W. Wang, W.B. Wu, W. Xu, K. Xuan, Q.B. Zeng USTC/NSRL, Hefei, Anhui, People's Republic of China
	The Hefei Light Source (HLS) is undergoing a series of upgrades to prepare for the top-off operation. To ensure radiation safety in the experimental hall under abnormal beam loss, simulations under various system errors in the HLS storage ring are performed to get in-depth understanding of the induced radiation nature. To make the radiation shielding more effective, a beam scraper is used to decrease the aperture opening of the vacuum chamber, and additional shielding is installed around the scraper. Simulation and beam test results are reported in this paper.
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TUPVA041	Exploring the Triplet Parameter Space to Optimise the Final Focus of the FCC-hh	optics, quadrupole, target, radiation	2155
	L. van Riesen-Haupt, J.L. Abelleira, E. Cruz Alaniz, A. Seryi JAI, Oxford, United Kingdom
	One of the main challenges when designing final focus systems of particle accelerators is maximising the beam stay clear in the strong quadrupole magnets of the inner triplet. Moreover it is desirable to keep the quadrupoles in the inner triplet as short as possible for space and costs reasons but also to reduce chromaticity and simplify corrections schemes. An algorithm that explores the triplet parameter space to optimise both these aspects was written. It uses thin lenses as a first approximation and MADX for more precise calculations. In cooperation with radiation studies, this algorithm was then applied to design an alternative triplet for the final focus of the Future Circular Collider.
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TUPVA043	A Code for Optimising Triplet Layout	quadrupole, collider, focusing, proton	2163
	L. van Riesen-Haupt, J.L. Abelleira, E. Cruz Alaniz, A. Seryi JAI, Oxford, United Kingdom
	Funding: EuroCirCol One of the main challenges when designing final focus systems of particle accelerators is maximising the beam stay clear in the strong quadrupole magnets of the inner triplet. Moreover it is desirable to keep the quadrupoles in the inner triplet as short as possible for space and costs reasons but also to reduce chromaticity and simplify corrections schemes. An algorithm that explores the triplet parameter space to optimise both these aspects was written. It uses thin lenses as a first approximation for a broad parameter scan and MADX for more precise calculations. The thin lens algorithm is significantly faster than a full scan using MADX and relatively precise at indicating the approximate area where the optimum solution lies.
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TUPVA121	Shielding Calculations for the Commissioning Beam Dump During the First Stage Beam Commissioning of the ESS Warm Linac	proton, linac, neutron, DTL	2376
	K. Batkov, L. Tchelidze ESS, Lund, Sweden
	Starting operations in 2019, the European Spallation Source will be a long pulsed neutron source powered by a 5 MW proton beam impinging on a rotating tungsten target. This study describes the results of shielding calculations performed to determine necessary shielding configuration during various steps of first stage beam commissioning of the ESS Linac. The first stage commissioning is divided in four steps with different beam energy, up to maximum 74 MeV. The commissioning beam dump shielding assessment is presented for each step of first stage commissioning and different beam parameters (energies, repetition rates, pulse lengths and currents).
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WEPIK077	Shielding of Beam Pipe on Rapidly Varying Magnetic Field	simulation, vacuum, feedback, emittance	3107
	N. Wang, J. Chen, S.K. Chen, P. He, G. Xu IHEP, Beijing, People's Republic of China
	In low emittance rings, beam is quite sensitive to orbit oscillations. Fast correctors will be used to correct the beam orbit. The fast varying magnetic field will generate eddy current on the beam pipe, which will in turn change the phase and the amplitude of the magnetic field. The shielding effect of the beam pipe on a fast varying magnetic field is simulated for different frequencies. The results are also benchmarked with the measurements in the lab.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK077
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WEPIK090	Characterization of Shielding for the CERN-SPS Vacuum Flanges With Respect to Beam Coupling Impedance	impedance, vacuum, resonance, coupling	3143
	T. Kaltenbacher, C. Vollinger CERN, Geneva, Switzerland
	Longitudinal multi-bunch instabilities in the CERN-SPS pose a serious limitation for future beam intensities required for high luminosity LHC. Hence, an impedance model for the SPS accelerator was developed from which one group of vacuum flanges could be identified as being a major culprit for these instabilities. These flanges support high impedance modes and their impact on beam stability was traced to a longitudinal mode at about 1.4GHz. For improvement of multi-bunch stability threshold, this group of flanges will be shielded as part of an impedance reduction campaign. We describe the evaluation of different impedance shielding designs proposed to reduce the longitudinal beam coupling impedance of this group of vacuum flanges in the SPS. EM-field simulations were performed to identify remaining resonances in these vacuum flanges with impedance shield prototypes installed, and the simulation models were benchmarked with RF-measurements. Depending on the performance and other parameters, the most suitable shield design will be selected, built and installed. As a first step, the installation of one shielding design in some positions in the SPS is planned for the beginning of 2017.
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WEPVA029	SIS100 Tunnel Design and Status	radiation, site, operation, extraction	3316
	C. Omet, J. Falenski, G. Fehrenbacher, H. Kisker, K. Konradt, A. Sokolov, P.J. Spiller GSI, Darmstadt, Germany A. Fischer FAIR, Darmstadt, Germany
	As the FAIR project is proceeding, many of the building and tunnel designs in the meanwhile are frozen and documents are prepared for tendering. For the future FAIR driver accelerator, SIS100, the accelerator tunnel T110 comprises a 1100 m long tunnel, which has a depth of 17 m under ground. In this paper, its environmental boundary conditions, design principles and the finally chosen layout are presented.
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WEPVA070	Alignment and Calibration for Collimation System in CSNS/RCS	collimation, vacuum, alignment, laser	3432
	J.B. Yu, L. Dong, L. Kang, B. Li, X.J. Nie, A.X. Wang, G.Y. Wang, X.L. Wang, J.S. Zhang IHEP, Beijing, People's Republic of China J.X. Chen, T. Luo, C.J. Ning CSNS, Guangdong Province, People's Republic of China
	Funding: National Natural Science Foundation of China (Grant Nos.11375217) In order to reduce the uncontrolled losses in the localized station, the beam collimation system has been performed for the 1.6GeV synchrotron of CSNS. The CSNS/RCS transverse collimation system is designed to be a two-stage system which consists of one primary collimator and four secondary collimators. All collimators had completed processing and now been installed in the tunnel. To meet the requirements of physical system, alignment for collimation system have to be done before circulating beams. This paper will show the alignment technique of collimation system. Then some problems during the alignment process will be mentioned. For the primary collimator will be replaced in second-stage of CSNS, and the alignment for the replaced collimator will be introduced finally.
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WEPVA110	Analysis and Operational Feedback on the New Design of the High Energy Beam Dump in the CERN SPS	vacuum, operation, simulation, interlocks	3524
	P. Rios Rodriguez, J.A. Briz Monago, M. Calviani, K. Cornelis, S. De Man, R. Esposito, S.S. Gilardoni, B. Goddard, J.L. Grenard, D. Grenier, M. Grieco, J. Humbert, V. Kain, F.M. Leaux, C. Pasquino, A. Perillo-Marcone, J.R.F. Poujol, S. Sgobba, D. Steyart, F.M. Velotti, V. Vlachoudis CERN, Geneva, Switzerland
	CERN's Super Proton Synchrotron (SPS) high-energy internal dump (Target Internal Dump Vertical Graphite, known as TIDVG) is required to intercept beams from 10² to 450 GeV. The equipment installed in 2014 (TIDVG#3) featured an absorbing core composed of different materials surrounded by a water-cooled copper jacket, which hold the UHV of the machine. An inspection of a previous equipment (TIDVG#2) in 2013 revealed significant beam induced damage to the aluminium section of the dump, which required imposing operational limitations to minimise the risk of reproducing this phenomenon. Additionally, in 2016 a vacuum leak was detected in the dump assembly, which imposed further limitations, i.e. a reduction of the beam intensity that could be dumped per SPS supercycle. This paper presents a new design (TIDVG#4), which focuses on improving the operational robustness of the device. Moreover, thanks to the added instrumentation, a careful analysis of its performance (both experimentally and during operation) will be possible. These studies will help validating technical solutions for the design of the future SPS dump to be installed during CERN's Long Shutdown 2 in 2020 (TIDVG#5).
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WEPVA114	Optimising Machine-Experiment Interventions in HL-LHC	operation, radiation, experiment, vacuum	3540
	F. Sanchez Galan, C. Adorisio, I. Bergstrom, D. Brethoux, S. Evrard, A. Gaddi, L.P. Krzkempek, M. Lazzaroni, J. Perez Espinos, M. Raymond, H. Vincke CERN, Geneva, Switzerland
	Funding: This Research is supported by the HL-LHC project The luminosity reach of the HL-LHC experiments implies new constraints for the protection of the inner triplets from the machine debris. In general activation levels will increase a factor of 15-30 from the 2015 values (LS1), affecting both radiation tolerance of equipment and maintenance scenarios. The design of new equipment takes into account these constraints and the entire layout of tunnel equipment near the interaction regions will al-low for simplified maintenance. In particular, new ab-sorbers will replace the existing protection of the ma-chine-experiment cavern boundaries, with an optimised layout of the region. This paper summarises the main constraints (both physical and operational) existing at the region, together with the solutions adopted to reduce worker's dose.
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WEPVA151	The eRHIC Interaction Region Magnets	electron, quadrupole, hadron, dipole	3624
	B. Parker, R.B. Palmer, H. Witte BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. Designing eRHIC Interaction Region (IR) magnets faces special Machine Detector Interface challenges. Based upon HERA-II experience, a fundamental consideration is to avoid excessive background due to synchrotron radiation striking masks and septa in the vicinity of the experiment. Circumventing such radiation is problematic because the colliding beams have quite different rigidities; we must shield the e-beam from hadron IR magnet multi-tesla coil fields. On the outgoing-hadron, i.e. forward IR side, this difficulty is compounded by needing large hadron beam apertures to enable downstream separation and experimental detection of a mix of scattered and produced forward going charged particles and (in the electron-ion case) a wide-spread cone of neutrons. Here we present superconducting magnet designs with combinations of active and passive shielding and Sweet Spot coils to meet these requirements along with the design of a superferric spectrometer dipole, with an integrated cancel coil, that extends the forward experimental acceptance.
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THPAB007	Short Bunches at the Transition From Strong to Weak Longitudinal Instability	simulation, synchrotron, damping, experiment	3696
	P. Kuske HZB, Berlin, Germany
	The interaction of particles with their vacuum sur-roundings can lead to longitudinal instabilities of the whole bunch of particles. Most of these instabilities are strong and the growth rates are large compared to the damping rate. For a weak instability the opposite is true and with just a resistive impedance the instability would always be weak and independent of the bunch length. The interaction of a bunch with its own radiation emitted midway between parallel plates leads to a strong instabil-ity for long bunches and a transition to weak instability if the bunch length becomes shorter. This regime is ana-lysed numerically with a Vlasov-Fokker-Planck solver. The results are compared to recent observations at ANKA. An attempt is made to explain the remaining discrepan-cies by including higher order terms of the momentum compaction factor into these calculations. There are indi-cations that the simple model needs refinements in order to take radiation from upstream dipoles into account.
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THPAB061	Limiting Effects in the Double EEX Beamline	emittance, timing, simulation, dipole	3858
	G. Ha POSTECH, Pohang, Kyungbuk, Republic of Korea M.E. Conde, D.S. Doran, J.G. Power ANL, Argonne, Illinois, USA
	Funding: This work is supported by Department of Energy, Office of High Energy Physics, under Contract No. DE-AC02-06CH11357. The double emittance exchange (EEX) beamline is suggested to overcome the large horizontal emittance and transverse jitter issues associated with the single EEX beamline while preserving its powerful phase-space manipulation capability. However, the double EEX beamline also has potential limitations due to coherent synchrotron radiation (CSR) and transverse jitter. The former limitation arises because double EEX uses twice as many bending magnets as single EEX which means stronger CSR effects degrading the beam quality. The latter limitation arises because a longitudinal jitter in front of the first EEX beamline is converted into a transverse jitter in the middle section (between the EEX beamlines) which can cause beam loss or beam degradation. In this paper, we numerically explore the effects of these two limitations on the emittance and beam transport.
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THPVA040	Magnetic Field Computation for PMTs Shielding Optimization	simulation, experiment, quadrupole, photon	4522
	E. Bouquerel, O. Dorvaux, S. Kihel, M. Krauth, P. Peaupardin IPHC, Strasbourg Cedex 2, France C. Ciemala IFJ-PAN, Kraków, Poland
	The Photon Array for the studies of Radioactive and Ion Stable beams (PARIS) is a multidetector of clusters. Each cluster is composed of 9 units of two-shells phoswiches of LaBr3/NaI scintillators optically coupled to one photomultiplier tube. PARIS will be used in combination with the VAMOS spectrometer at GANIL. During the experiment, PMTs will be exposed to the constant magnetic fringe fields produced by a quadrupole. Magnetic shielding is essential to efficiently lower the magnetic field inside the PMTs. The design and the optimization of this shield is presented. A comparison is done between the simulated and the experimental values.
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Paper

Title

Other Keywords

Page

MOPAB004

Improved Protection of the Warm Magnets of the LHC Betatron Cleaning Insertion

radiation, operation, luminosity, collimation

72

C. Bahamonde Castro, F. Cerutti, P. Fessia, A. Lechner, A. Mereghetti, D. Mirarchi, S. Redaelli, E. Skordis
CERN, Geneva, Switzerland
E. Skordis
The University of Liverpool, Liverpool, United Kingdom

After the High Luminosity (HL) upgrade in 2024-2026, the LHC is anticipated to increase its integrated luminosity by a factor of 10 beyond its original design value of 300 fb-1. In preparation for this, several improvements to the equipment will already be implemented during the next Long Shutdown (LS2) starting in 2019. In the betatron cleaning insertion, the debris leaking out of several collimators will deposit energy in the downstream warm magnets, causing long-term radiation damage. A new layout has been proposed in which the most exposed magnet of each assembly is removed, reducing the assembly from 6 to 5 magnet units and gaining 2 spare magnets. New absorbers are therefore required to enhance the shielding of the remaining magnet string. In this paper, we present an evaluation of the dose to the warm magnets for post-LS2 operation, and we quantify the achievable reduction of the long-term radiation damage for different absorber configurations. A solution for an improved magnet protection that fulfills the HL-LHC requirements is proposed.

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MOPIK015

Improvement of Electron Intensity Reduction System at SLRI Beam Test Facility

electron, target, synchrotron, booster

528

K. Kittimanapun, N. Chanlek, P. Klysubun, S. Krainara, S. Supajeerapan
SLRI, Nakhon Ratchasima, Thailand

Funding: This work is partly supported by the National Science and Technology Development Agency (NSTDA) under contract FDA-C0-2558-855-TH.
Synchrotron Light Research Institute (SLRI) has been commissioning an additional experimental station, a Beam Test Facility (BTF), to the SLRI accelerator complex. SLRI BTF was constructed to provide electron test beams with energy ranging from 40 MeV up to 1.2 GeV and with tunable electron intensity from a few to millions of electrons per burst. In order to obtain low intensity of test beams, an approach using a metal target together with an energy selector has been employed. A combination of a target chamber installed at the high energy beam transport line and the existing 4-degree bending magnet that is used as an energy selector first produced low intensity test beams. However, the test beam profile was not well determined due to the insufficient bending angle of the energy selector and high primary beam energy. Another approach mounting a target chamber at the low energy beam transport line and using the synchrotron booster as an energy selector was implemented to avoid such problems. Once in operation, the facility will have the potential to service calibration and testing of high energy detectors as well as beam diagnostic instrumentations.

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MOPIK035

New Injection Scheme of J-PARC Rapid Cycling Synchrotron

injection, proton, operation, synchrotron

579

K. Yamamoto, H. Harada, H. Hotchi, J. Kamiya, P.K. Saha, T. Takayanagi, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
N. Miki, O. Takeda
Nippon Advanced Technology Co., Ltd., Tokai, Japan

The 3-GeV Rapid Cycling Synchrotron (RCS) of Japan Proton Accelerator Research Complex (J-PARC) aims to deliver 1-MW proton beam to the neutron target and Main Ring synchrotron (MR). Present beam power of RCS is up to 500-kW and the higher radiation doses were concentrated in the injection area. These activations were caused by the interaction between the foil and the beam. To reduce the worker dose near the injection point, we have studied new design of the injection scheme to secure enough space for radiation shielding and bellows. In the new system, two of four injection pulse bump magnets are replaced and we are able to ensure the additional 500 mm space at the injection foil .

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MOPIK077

Impact of Dynamical Stray Fields on CLIC

collimation, luminosity, synchrotron, linear-collider

708

E. Marín, D. Schulte
CERN, Geneva, Switzerland
B. Heilig
MFGI, Budapest, Hungary
J. Pfingstner
University of Oslo, Oslo, Norway

In this paper we estimate the tolerances of stray-fields variations on the Compact Linear Collider (CLIC), discuss possible sources and propose several solutions. The Beam Delivery System (BDS) is the most sensitive system of CLIC to unwanted magnetic field variations, already variations of 1 nT would reduce the luminosity by 10% at wavelengths comparable to the BDS without considering any correction mechanism. Two sources of magnetic field variations are considered, natural and man-made. Precise magnetic field measurements at Earth's surface under a typical geomagnetic storm are presented. Additionally, stray field measurements have been conducted at CERN, to inspect B-field variations due to technical equipment in an accelerator environment. Different solutions are proposed to minimise the impact of stray fields on the CLIC performance.

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MOPIK102

Beam Dynamics Studies of the HIE-ISOLDE Transfer Lines in the Presence of Magnetic Stray Fields

quadrupole, experiment, operation, solenoid

768

J. Mertens, J. Bauche, M.A. Fraser, B. Goddard, R. Ostojić, J.S. Schmidt
CERN, Geneva, Switzerland

The ISOLDE facility at CERN produces radioactive isotopes far from stability for fundamental nuclear physics research. The radioactive beams are accelerated to high-energy using a post-accelerator before being transferred for study in different experiments at the end of a network of High Energy Beam Transfer (HEBT) lines. In the framework of the HIE-ISOLDE project, the energy of post-accelerated beams is to be increased to over 10 MeV/u and new experimental detectors are being proposed for installation to exploit the new energy regime. The stray magnetic fields associated with many of the new detectors will distort the beam trajectories in the HEBT, potentially affecting the transmission of the low intensity beams delivered to the experiments. In this contribution, the influence on the HEBT of the stray field of the proposed ISOL Solenoidal Spectrometer is discussed, correction schemes described and shielding options assessed.

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TUPAB107

Study of 60 Hz Beam Orbit Fluctuations in the Taiwan Photon Source

SRF, vacuum, photon, insertion-device

1566

C.H. Huang, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, K.H. Hu, C.Y. Liao, C.Y. Wu
NSRRC, Hsinchu, Taiwan

The Taiwan Photon Source is a 3 GeV synchrotron light source at NSRRC. To achieve high quality experimental results, it is important to minimize beam motion. During the installation of insertion devices and front-ends, the beam motion around 60 Hz became significant. The response matrix together with singular value decomposition was used to identify the transmitter of the superconducting radio frequency system as the source for the 60 Hz perturbations. This was subsequently corrected by rerouting the grounding of the mains in the transmitters. Yet, the 60Hz orbit fluctuation became even more serious after the next shutdown. A serious of experiments are performed to dig out that the beam was disturbed by the magnetic field from newly installed fan motors. Shielding the fans with mu-metal and increasing the distance between fan and beam pipe drastically reduced the leakage field and greatly increased beam stability. These errors could be prevented at the design stage in the ideal case. However, these errors happened finally and need to be dug out and eliminated. The method and experiences are summarized in this report. These will benefit others who facing the similar problems.

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TUPAB133

Perturbation Analysis for Beam Trajectories. Determining Local Shielding Containment for LCLS-II

quadrupole, simulation, dipole, undulator

1637

M. Santana-Leitner
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515
Containment of beam losses by halo and momentum/energy collimators is a well-established practice for normal operation of particle accelerators where tracking codes are applied. However, for exceptional events, such as magnet power failures, severe lattice mis-match, etc., ad-hoc analytical approaches are typically applied. Oftentimes those simplified methods are not automatic; they don't define the full phase-space of mis-steered trajectories and cannot keep up with beam-line upgrades. Moreover, there may exist a disconnect between the teams analyzing consequences of errant beams and those involved in beam-line design. With electron beams exceeding 100 kW, design of LCLS-II at SLAC National Accelerator Laboratory required exhaustive beam-containment studies to avoid potential destruction of components and excessive dose rates. The geometry of the different beam-lines and the nominal optics was built with MadFLUKA [1], and FLUKA [2] Monte Carlo code along with perturbations to magnetic fields was used to inspect failures compatible with beam operations and hardware settings. Consequences of mis-steered rays and the respective mitigations were directly analyzed with FLUKA.
[1] M. Santana-Leitner et al., MadFLUKA Beam Line 3D Builder. Simulation of Beam Loss Propagation in Accelerators, IPAC14 proceedings, MOPME040
[2] A. Ferrari et al, The FLUKA Code: Developments and Challenges for High Energy and Medical Applications, Nuclear Data Sheets 120, 211-214 (2014)

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TUPIK034

NSC KIPT Neutron Source on the Base of Subcritical Assembly With Electron Linear Accelerator Driver

neutron, target, electron, operation

1754

A.Y. Zelinsky, I.M. Karnaukhov, A. Mytsykov, I. Ushakov
NSC/KIPT, Kharkov, Ukraine
Y.L. Chi
IHEP, Beijing, People's Republic of China
Y. Gohar
ANL, Argonne, Illinois, USA

National Science Center Kharkov Institute of Physics & Technology (NSC KIPT) together with ANL, Chicago, USA developed up to date scientific facility that is Neutron Source on the base of subcritical assembly driven with 100 MeV/100 kW electron accelerator. During bombarding of the Tungsten or Uranium targets the electron beam generates the original neutrons that are multiplied in the facility core of low enriched uranium trough the fission process. The maximal value of the neutron multiplication factor is 0.98. So the total neutron flux output is increased as much as 50 times and is 2·10 13 n·cm^-2·c-1. The subcriticality of the system eliminates the possibility of self-sustained chain reaction existence that increases the nuclear safety of the facility drastically. The neutron source mentioned above is the first facility of such type in the world. The results that will be obtained at studies of neutron characteristics of the neutron source with low enriched uranium core and during optimization of the operation modes of the facility systems will became the scientific background for the further development of the safe, ecological nuclear energetics of the future.

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TUPIK066

Beam Loss Simulation and Radiation Shielding for Top-Off Operation of Hefei Light Source

electron, storage-ring, injection, simulation

1845

X. Zhou, J.Y. Li, J.G. Wang, S.W. Wang, W.B. Wu, W. Xu, K. Xuan, Q.B. Zeng
USTC/NSRL, Hefei, Anhui, People's Republic of China

The Hefei Light Source (HLS) is undergoing a series of upgrades to prepare for the top-off operation. To ensure radiation safety in the experimental hall under abnormal beam loss, simulations under various system errors in the HLS storage ring are performed to get in-depth understanding of the induced radiation nature. To make the radiation shielding more effective, a beam scraper is used to decrease the aperture opening of the vacuum chamber, and additional shielding is installed around the scraper. Simulation and beam test results are reported in this paper.

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TUPVA041

Exploring the Triplet Parameter Space to Optimise the Final Focus of the FCC-hh

optics, quadrupole, target, radiation

2155

L. van Riesen-Haupt, J.L. Abelleira, E. Cruz Alaniz, A. Seryi
JAI, Oxford, United Kingdom

One of the main challenges when designing final focus systems of particle accelerators is maximising the beam stay clear in the strong quadrupole magnets of the inner triplet. Moreover it is desirable to keep the quadrupoles in the inner triplet as short as possible for space and costs reasons but also to reduce chromaticity and simplify corrections schemes. An algorithm that explores the triplet parameter space to optimise both these aspects was written. It uses thin lenses as a first approximation and MADX for more precise calculations. In cooperation with radiation studies, this algorithm was then applied to design an alternative triplet for the final focus of the Future Circular Collider.

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TUPVA043

A Code for Optimising Triplet Layout

quadrupole, collider, focusing, proton

2163

L. van Riesen-Haupt, J.L. Abelleira, E. Cruz Alaniz, A. Seryi
JAI, Oxford, United Kingdom

Funding: EuroCirCol
One of the main challenges when designing final focus systems of particle accelerators is maximising the beam stay clear in the strong quadrupole magnets of the inner triplet. Moreover it is desirable to keep the quadrupoles in the inner triplet as short as possible for space and costs reasons but also to reduce chromaticity and simplify corrections schemes. An algorithm that explores the triplet parameter space to optimise both these aspects was written. It uses thin lenses as a first approximation for a broad parameter scan and MADX for more precise calculations. The thin lens algorithm is significantly faster than a full scan using MADX and relatively precise at indicating the approximate area where the optimum solution lies.

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TUPVA121

Shielding Calculations for the Commissioning Beam Dump During the First Stage Beam Commissioning of the ESS Warm Linac

proton, linac, neutron, DTL

2376

K. Batkov, L. Tchelidze
ESS, Lund, Sweden

Starting operations in 2019, the European Spallation Source will be a long pulsed neutron source powered by a 5 MW proton beam impinging on a rotating tungsten target. This study describes the results of shielding calculations performed to determine necessary shielding configuration during various steps of first stage beam commissioning of the ESS Linac. The first stage commissioning is divided in four steps with different beam energy, up to maximum 74 MeV. The commissioning beam dump shielding assessment is presented for each step of first stage commissioning and different beam parameters (energies, repetition rates, pulse lengths and currents).

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WEPIK077

Shielding of Beam Pipe on Rapidly Varying Magnetic Field

simulation, vacuum, feedback, emittance

3107

N. Wang, J. Chen, S.K. Chen, P. He, G. Xu
IHEP, Beijing, People's Republic of China

In low emittance rings, beam is quite sensitive to orbit oscillations. Fast correctors will be used to correct the beam orbit. The fast varying magnetic field will generate eddy current on the beam pipe, which will in turn change the phase and the amplitude of the magnetic field. The shielding effect of the beam pipe on a fast varying magnetic field is simulated for different frequencies. The results are also benchmarked with the measurements in the lab.

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WEPIK090

Characterization of Shielding for the CERN-SPS Vacuum Flanges With Respect to Beam Coupling Impedance

impedance, vacuum, resonance, coupling

3143

T. Kaltenbacher, C. Vollinger
CERN, Geneva, Switzerland

Longitudinal multi-bunch instabilities in the CERN-SPS pose a serious limitation for future beam intensities required for high luminosity LHC. Hence, an impedance model for the SPS accelerator was developed from which one group of vacuum flanges could be identified as being a major culprit for these instabilities. These flanges support high impedance modes and their impact on beam stability was traced to a longitudinal mode at about 1.4GHz. For improvement of multi-bunch stability threshold, this group of flanges will be shielded as part of an impedance reduction campaign. We describe the evaluation of different impedance shielding designs proposed to reduce the longitudinal beam coupling impedance of this group of vacuum flanges in the SPS. EM-field simulations were performed to identify remaining resonances in these vacuum flanges with impedance shield prototypes installed, and the simulation models were benchmarked with RF-measurements. Depending on the performance and other parameters, the most suitable shield design will be selected, built and installed. As a first step, the installation of one shielding design in some positions in the SPS is planned for the beginning of 2017.

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WEPVA029

SIS100 Tunnel Design and Status

radiation, site, operation, extraction

3316

C. Omet, J. Falenski, G. Fehrenbacher, H. Kisker, K. Konradt, A. Sokolov, P.J. Spiller
GSI, Darmstadt, Germany
A. Fischer
FAIR, Darmstadt, Germany

As the FAIR project is proceeding, many of the building and tunnel designs in the meanwhile are frozen and documents are prepared for tendering. For the future FAIR driver accelerator, SIS100, the accelerator tunnel T110 comprises a 1100 m long tunnel, which has a depth of 17 m under ground. In this paper, its environmental boundary conditions, design principles and the finally chosen layout are presented.

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WEPVA070

Alignment and Calibration for Collimation System in CSNS/RCS

collimation, vacuum, alignment, laser

3432

J.B. Yu, L. Dong, L. Kang, B. Li, X.J. Nie, A.X. Wang, G.Y. Wang, X.L. Wang, J.S. Zhang
IHEP, Beijing, People's Republic of China
J.X. Chen, T. Luo, C.J. Ning
CSNS, Guangdong Province, People's Republic of China

Funding: National Natural Science Foundation of China (Grant Nos.11375217)
In order to reduce the uncontrolled losses in the localized station, the beam collimation system has been performed for the 1.6GeV synchrotron of CSNS. The CSNS/RCS transverse collimation system is designed to be a two-stage system which consists of one primary collimator and four secondary collimators. All collimators had completed processing and now been installed in the tunnel. To meet the requirements of physical system, alignment for collimation system have to be done before circulating beams. This paper will show the alignment technique of collimation system. Then some problems during the alignment process will be mentioned. For the primary collimator will be replaced in second-stage of CSNS, and the alignment for the replaced collimator will be introduced finally.

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WEPVA110

Analysis and Operational Feedback on the New Design of the High Energy Beam Dump in the CERN SPS

vacuum, operation, simulation, interlocks

3524

P. Rios Rodriguez, J.A. Briz Monago, M. Calviani, K. Cornelis, S. De Man, R. Esposito, S.S. Gilardoni, B. Goddard, J.L. Grenard, D. Grenier, M. Grieco, J. Humbert, V. Kain, F.M. Leaux, C. Pasquino, A. Perillo-Marcone, J.R.F. Poujol, S. Sgobba, D. Steyart, F.M. Velotti, V. Vlachoudis
CERN, Geneva, Switzerland

CERN's Super Proton Synchrotron (SPS) high-energy internal dump (Target Internal Dump Vertical Graphite, known as TIDVG) is required to intercept beams from 10² to 450 GeV. The equipment installed in 2014 (TIDVG#3) featured an absorbing core composed of different materials surrounded by a water-cooled copper jacket, which hold the UHV of the machine. An inspection of a previous equipment (TIDVG#2) in 2013 revealed significant beam induced damage to the aluminium section of the dump, which required imposing operational limitations to minimise the risk of reproducing this phenomenon. Additionally, in 2016 a vacuum leak was detected in the dump assembly, which imposed further limitations, i.e. a reduction of the beam intensity that could be dumped per SPS supercycle. This paper presents a new design (TIDVG#4), which focuses on improving the operational robustness of the device. Moreover, thanks to the added instrumentation, a careful analysis of its performance (both experimentally and during operation) will be possible. These studies will help validating technical solutions for the design of the future SPS dump to be installed during CERN's Long Shutdown 2 in 2020 (TIDVG#5).

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WEPVA114

Optimising Machine-Experiment Interventions in HL-LHC

operation, radiation, experiment, vacuum

3540

F. Sanchez Galan, C. Adorisio, I. Bergstrom, D. Brethoux, S. Evrard, A. Gaddi, L.P. Krzkempek, M. Lazzaroni, J. Perez Espinos, M. Raymond, H. Vincke
CERN, Geneva, Switzerland

Funding: This Research is supported by the HL-LHC project
The luminosity reach of the HL-LHC experiments implies new constraints for the protection of the inner triplets from the machine debris. In general activation levels will increase a factor of 15-30 from the 2015 values (LS1), affecting both radiation tolerance of equipment and maintenance scenarios. The design of new equipment takes into account these constraints and the entire layout of tunnel equipment near the interaction regions will al-low for simplified maintenance. In particular, new ab-sorbers will replace the existing protection of the ma-chine-experiment cavern boundaries, with an optimised layout of the region. This paper summarises the main constraints (both physical and operational) existing at the region, together with the solutions adopted to reduce worker's dose.

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WEPVA151

The eRHIC Interaction Region Magnets

electron, quadrupole, hadron, dipole

3624

B. Parker, R.B. Palmer, H. Witte
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Designing eRHIC Interaction Region (IR) magnets faces special Machine Detector Interface challenges. Based upon HERA-II experience, a fundamental consideration is to avoid excessive background due to synchrotron radiation striking masks and septa in the vicinity of the experiment. Circumventing such radiation is problematic because the colliding beams have quite different rigidities; we must shield the e-beam from hadron IR magnet multi-tesla coil fields. On the outgoing-hadron, i.e. forward IR side, this difficulty is compounded by needing large hadron beam apertures to enable downstream separation and experimental detection of a mix of scattered and produced forward going charged particles and (in the electron-ion case) a wide-spread cone of neutrons. Here we present superconducting magnet designs with combinations of active and passive shielding and Sweet Spot coils to meet these requirements along with the design of a superferric spectrometer dipole, with an integrated cancel coil, that extends the forward experimental acceptance.

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THPAB007

Short Bunches at the Transition From Strong to Weak Longitudinal Instability

simulation, synchrotron, damping, experiment

3696

P. Kuske
HZB, Berlin, Germany

The interaction of particles with their vacuum sur-roundings can lead to longitudinal instabilities of the whole bunch of particles. Most of these instabilities are strong and the growth rates are large compared to the damping rate. For a weak instability the opposite is true and with just a resistive impedance the instability would always be weak and independent of the bunch length. The interaction of a bunch with its own radiation emitted midway between parallel plates leads to a strong instabil-ity for long bunches and a transition to weak instability if the bunch length becomes shorter. This regime is ana-lysed numerically with a Vlasov-Fokker-Planck solver. The results are compared to recent observations at ANKA. An attempt is made to explain the remaining discrepan-cies by including higher order terms of the momentum compaction factor into these calculations. There are indi-cations that the simple model needs refinements in order to take radiation from upstream dipoles into account.

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THPAB061

Limiting Effects in the Double EEX Beamline

emittance, timing, simulation, dipole

3858

G. Ha
POSTECH, Pohang, Kyungbuk, Republic of Korea
M.E. Conde, D.S. Doran, J.G. Power
ANL, Argonne, Illinois, USA

Funding: This work is supported by Department of Energy, Office of High Energy Physics, under Contract No. DE-AC02-06CH11357.
The double emittance exchange (EEX) beamline is suggested to overcome the large horizontal emittance and transverse jitter issues associated with the single EEX beamline while preserving its powerful phase-space manipulation capability. However, the double EEX beamline also has potential limitations due to coherent synchrotron radiation (CSR) and transverse jitter. The former limitation arises because double EEX uses twice as many bending magnets as single EEX which means stronger CSR effects degrading the beam quality. The latter limitation arises because a longitudinal jitter in front of the first EEX beamline is converted into a transverse jitter in the middle section (between the EEX beamlines) which can cause beam loss or beam degradation. In this paper, we numerically explore the effects of these two limitations on the emittance and beam transport.

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THPVA040

Magnetic Field Computation for PMTs Shielding Optimization

simulation, experiment, quadrupole, photon

4522

E. Bouquerel, O. Dorvaux, S. Kihel, M. Krauth, P. Peaupardin
IPHC, Strasbourg Cedex 2, France
C. Ciemala
IFJ-PAN, Kraków, Poland

The Photon Array for the studies of Radioactive and Ion Stable beams (PARIS) is a multidetector of clusters. Each cluster is composed of 9 units of two-shells phoswiches of LaBr3/NaI scintillators optically coupled to one photomultiplier tube. PARIS will be used in combination with the VAMOS spectrometer at GANIL. During the experiment, PMTs will be exposed to the constant magnetic fringe fields produced by a quadrupole. Magnetic shielding is essential to efficiently lower the magnetic field inside the PMTs. The design and the optimization of this shield is presented. A comparison is done between the simulated and the experimental values.

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