HB2012 - List of Keywords (injection)

Paper	Title	Other Keywords	Page
MOI1A01	LHC - Challenges in Handling Beams Exceeding 100 MJ	beam-losses, luminosity, insertion, collimation	1
	R. Schmidt CERN, Geneva, Switzerland
	The Large Hadron Collider (LHC) at CERN operates at 4 TeV with high intensity beams, with bunch intensities exceeding the nominal value by several 10 %. The energy stored in each beams is beyond 130 MJ, less than a factor of three from the nominal value at 7 TeV. With these parameters, operation entered into a regime where various effects due to high intensity bunches are observed (instabilities, beam-beam effects, e-cloud effects). The highly efficient collimation system limits beam losses that threaten to quench superconducting magnets. The correct functioning of the machine protection systems is vital during the different operational phases, where already a small fraction of the stored energy is sufficient to damage accelerator equipment or experiments in case of uncontrolled beam loss. Safe operation in presence of such high intensity proton beams is guaranteed by the interplay of many different systems: beam dumping system, beam interlocks, beam instrumentation, equipment monitoring, collimators and absorbers. The experience gained with the key systems of LHC machine protection and collimation will be discussed.
	Slides MOI1A01 [31.116 MB]

MOI1B02	Technological Challenges for High-Intensity Proton Rings	linac, proton, acceleration, space-charge	15
	Y. Yamazaki FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 High-intensity, pulsed proton accelerators have been and will be requested by a wide variety of scientific fields and industrial and medical applications, for example, pulsed spallation neutron sources and neutrino sources. We will focus our discussion on the proton rings with a pulse length of a few μsec and a beam power of MW. These accelerators may be used for boosting injectors to higher-energy accelerators, like a neutrino factories. At first, we will discuss on the space-charge force which limit the stored charges in a ring together with the negative-ion injection scheme. The pulsed spallation neutron sources are classified into two schemes. One is the combination of a full-energy linac and an accumulation ring (AR) exemplified by SNS and LANSCE. The other is that of a low-energy linac and a Rapid-Cycle Synchrotron (RCS) exemplified by J-PARC RCS and ISIS. In general, pros and cons of accelerator schemes are dependent upon the technological development results. Pros and cons of AR versus RCS will be discussed on the basis of recent technological developments and beam experiment data together with the future perspectives for MW-class machines.
	Slides MOI1B02 [3.850 MB]

MOP203	Bunch-by-Bunch Beam Loss Diagnostics with Diamond Detectors at the LHC	beam-losses, proton, kicker, simulation	41
	M. Hempel BTU, Cottbus, Germany T. Baer University of Hamburg, Hamburg, Germany S. Bart Pedersen, B. Dehning, E. Effinger, E. Griesmayer, A. Lechner, R. Schmidt CERN, Geneva, Switzerland W. Lohmann DESY, Hamburg, Germany
	A main challenge in the operation with high intensity beams is managing beam losses that imply the risk of quenching superconducting magnets or even damage equipment. There are various sources of beam losses, such as losses related to injection, to beam instabilities and to UFOs (Unidentified Falling Objects). Mostly surprising in the first years of LHC operation was the observation of UFOs. They are believed to be dust particles with a typical size of 1-100 um, which lead to beam losses with a duration of about ten revolutions when they fall into the beam. 3600 BLMs (Beam Loss Monitors) are installed around the LHC ring, allowing to determinate the accurate location of UFOs. The time resolution of the BLMs is 40 us (half a turn revolution). A measurement of the beam losses with a time resolution better than the bunch spacing of 50 ns is crucial to understand loss mechanisms. Diamond sensors are able to provide such diagnostics and perform particle counting with ns time resolution. In this paper, we present measurements of various types of beam losses with diamond detectors. We also compare measurements of UFO induced beam losses around the LHC ring with results from MadX simulations.

MOP204	A Method to Measure the Incoherent Synchrotron Frequencies in Bunches	space-charge, simulation, synchrotron, dipole	46
	O. Chorniy, H. Reeg GSI, Darmstadt, Germany
	The method of measuring the incoherent synchrotron frequencies in a stationary bunch is presented. It can be shown that by measuring the local current at a fixed coordinate in RF bucket the corresponding incoherent synchrotron frequency can be obtained. Test calculations were done using simulation data where longitudinal space charge effects were included. The incoherent frequencies obtained with method are in a good agreement with theory. In real experiment, the incoherent frequencies were determined from bunch profiles recorded in the SIS18 with low intensity beam at injection energy. Bunch profiles were measured with a new Fast Current Transformer which has a relatively broad frequency range. The profiles were recorded using 8 bit resolution oscilloscope. The frequency spectra of local current fluctuation at different longitudinal positions were obtained numerically. The strongest lines in these spectra were at positions of theoretically expected incoherent frequencies. In this paper the method is described in details, the comparison of incoherent frequencies obtained from the simulation and measurement data with theoretical solutions is shown.

MOP209	High Intensity Proton FFAG Ring with Serpentine Acceleration for ADS	acceleration, proton, closed-orbit, transverse-dynamics	60
	E. Yamakawa, Y. Ishi, Y. Kuriyama, J.-B. Lagrange, Y. Mori, T. Uesugi Kyoto University, Research Reactor Institute, Osaka, Japan
	In order to produce high intensity proton beam for ADS, a new type of fixed rf acceleration scheme, so-called serpentine acceleration, is examined in scaling FFAG. Longitudinal hamiltonian for scaling FFAG is first derived analytically. Then the features of serpentine acceleration in longitudinal phase space are studied. Ring design for ADS is finally shown.

MOP210	Beam Stacking for High Intensity Pulsed Proton Beam with FFAG	acceleration, simulation, extraction, neutron	64
	Y. Mori, Y. Ishi, Y. Kuriyama, J.-B. Lagrange, T. Uesugi Kyoto University, Research Reactor Institute, Osaka, Japan
	Multi-beam stacking scheme to generate an intense short-pulsed proton beam with high repetition proton FFAG is presented.

MOP211	1-MW Beam Operation Scenario in the J-PARC RCS	quadrupole, emittance, lattice, controls	68
	H. Hotchi, H. Harada, N. Hayashi, M. Kinsho, P.K. Saha, Y. Shobuda, F. Tamura, K. Yamamoto, M. Yamamoto, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y. Irie KEK, Ibaraki, Japan
	The injection energy of the J-PARC RCS will be upgraded from 181 MeV to 400 MeV in the 2013 summer-autumn period. With this upgraded injection energy, we are to aim for 1 MW design output beam power. In this paper, we discuss beam dynamics issues for the 1 MW beam operation and their possible solutions.

MOP213	Beam Losses due to the Foil Scattering for CSNS/RCS	beam-losses, scattering, proton, electron	78
	M.Y. Huang, N. Wang, S. Wang, S.Y. Xu IHEP, Beijing, People's Republic of China
	For the Rapid Cycling Synchrotron of China Spallation Neutron Source (CSNS/RCS), the stripping foil scattering generates the beam halo and gives rise to additional beam losses during the injection process. The interaction between the proton beam and the stripping foil was discussed and the foil scattering was studied. A simple model and the realistic situation of the foil scattering were considered. By using the codes ORBIT and FLUKA, the multi-turn phase space painting injection process with the stripping foil scattering for CSNS/RCS was simulated and the beam losses due to the foil scattering were obtained.

MOP216	The Design Study on the Longitudinal Beam Dynamics for CSNS/RCS	acceleration, simulation, space-charge, bunching	89
	N. Wang, M.Y. Huang, Y. Li, S. Wang, S.Y. Xu, Y.S. Yuan IHEP, Beijing, People's Republic of China
	Rapid Cycling Synchrotron (RCS) is the key part of China Spallation Neutron Source (CSNS) accelerators. The RCS accumulates and accelerates 80 MeV beam from linac to 1.6 GeV. The particle number is 1.56·10¹³ for each pulse, with repetition rate of 25 Hz. In the RCS, longitudinal beam dynamics plays a crucial role in achieving high intensity beam with low beam loss. Longitudinal parameters are studied and optimized for efficient RF trapping of the beam in the longitudinal phase space. Beam performance is investigated by particle tracking simulations. Beam dynamic issues related to the high order mode induced by the RF generator are studied with a new developed code. Primary study on the adoption of dual harmonic cavity for higher beam power is also addressed.

MOP247	Beam Stability and Tail Population at SPS Scrapers	emittance, extraction, controls, diagnostics	166
	L.N. Drøsdal, K. Cornelis, B. Goddard, V. Kain, M. Meddahi, O. Mete, B. Mikulec, E. Veyrunes CERN, Geneva, Switzerland
	Before injection into the LHC the beams are scraped in the SPS to remove the tails of the transverse particle distributions. Without scraping the tail population is large enough to create losses above the beam abort thresholds of the LHC beam loss monitor system when injecting. The scrapers are only effective if correctly set up. This paper shows the results of periodical scraper scans. The beam position and beam size at the scraper is changing with time. The scraper settings hence need to follow accordingly. The scans also give insight into the transverse tail population and could therefore provide useful beam quality diagnostics. The impact on new scraper designs and setting up strategy are discussed.

MOP248	Brightness Evolution for LHC Beams during the 2012 Run	emittance, brightness, luminosity, extraction	170
	M. Kuhn Uni HH, Hamburg, Germany G. Arduini, J.F. Comblin, A. Guerrero, V. Kain, B. Mikulec, F. Roncarolo, M. Sapinski, M. Schaumann, R. Steerenberg CERN, Geneva, Switzerland
	One of the reasons for the remarkable achievements of the LHC is the excellent performance of the LHC injector chain. The evolution of the brightness in the injectors and at LHC collision in 2011 and 2012 is discussed. During certain run periods, the brightness from the beam provided by the injectors was lower than usual. Some of the issues have been identified so far and will be reported. The latest results on emittance blow-up investigations through the 2012 LHC cycle will also be presented and compared to the 2011 data. Possible implications for LHC upgrade scenarios will be mentioned.

MOP249	Tune Spread Studies at Injection Energies for the CERN Proton Synchrotron Booster	emittance, linac, space-charge, proton	175
	B. Mikulec, A. Findlay, V. Raginel, G. Rumolo, G. Sterbini CERN, Geneva, Switzerland
	In the near future, a new H⁻ injector, Linac4, will replace the current proton injector of the CERN Proton Synchrotron Booster (PSB), Linac2. The new charge-exchange injection at 160 MeV will yield higher brightness beams compared to the conventional 50 MeV multi-turn injection of Linac2. To make full use of the higher injection energy, space-charge effects will need to be understood and mitigated to optimize the intensity versus transverse emittance reach. This includes an optimization of longitudinal acceptance and distribution with a two-harmonic rf system, careful selection of the working point to accommodate the large Laslett tune-shift of approximately -0.5 and compensation of resonances within their stopbands. This paper will present calculations of the tune spread, based on measurements of longitudinal parameters and transverse emittances, for energies up to 160 MeV, different bunch densities and varying beam intensities. It should provide valuable information on the expected tune spread after the connection of Linac4 with the PSB and input for the study of resonance compensation techniques.

MOP255	Acceleration in Vertical Orbit Excursion FFAGs with Edge Focussing	space-charge, proton, simulation, acceleration	197
	S.J. Brooks STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	FFAGs with vertical orbit excursion (VFFAGs) provide a promising alternative design for rings with fixed-field superconducting magnets. They have a vertical magnetic field component that increases with height in the vertical aperture, yielding a skew quadrupole focussing structure. Edge focussing can provide an alternating gradient within each magnet, thus reducing the ring circumference. Like spiral scaling horizontal FFAGs (but not non-scaling ones) the machine has fixed tunes and no intrinsic limitation on momentum range. Rings to accelerate the 800MeV beam from the ISIS proton synchrotron are investigated, in terms of both magnet field geometry and longitudinal behaviour during acceleration with space charge. The 12GeV ring produces an output power of at least 2.18MW.

MOP256	High-power Scaling FFAG Ring Studies	space-charge, scattering, lattice, dynamic-aperture	202
	D.J. Kelliher, S. Machida, G.H. Rees STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	High-power scaling FFAG rings have potential application in areas such as neutron spallation, muon production, and accelerator-driven systems. It is proposed to build a model of such a ring in order to study major issues such as space charge and injection. A 20 ' 70 MeV radial DFD FFAG model, that was initially described in , incorporates long straights to facilitate H⁻ charge exchange injection. Bump magnets are used to move the injected beam away from the foil. The effect of the injection process on the beam emittance is considered. The tune depression and emittance blow up resulting from the effect of space charge is also calculated. G.H. Rees et al, ‘A Model for a High-Power Scaling FFAG Ring', IPAC12, New Orleans, 2012, MOPPD020, http://www. JACow.org

MOP257	Space Charge Limits on the ISIS Synchrotron including the Effects of Images	simulation, space-charge, synchrotron, resonance	206
	B.G. Pine, C.M. Warsop STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	The ISIS synchrotron provides a pulsed, 50 Hz, 800 MeV proton beam for spallation neutron production. Each pulse from the synchrotron contains ~2.8×10¹³ ppp, and at this beam intensity space charge and image forces have a strong effect on transverse beam dynamics. In order to increase intensity in the present machine, and to prepare for possible upgrades running at a higher intensity, studies are under way aimed at understanding the most critical features of such forces and their impact on beam loss. These studies are focused on working point optimisation, including resonances due to space charge and images. A 2D simulation code, Set, has been developed to improve understanding of transverse dynamics at ISIS, using a particle-in-cell algorithm to include space charge and image forces self-consistently. The ISIS synchrotron has profiled vacuum vessels and RF shields which conform to the shape of the beam envelope, and have a distinctive influence on the beam dynamics. Set is specifically designed to include these image forces. A systematic simulation study of possible working points is presented, along with an assessment of the effect on apertures.

MOP260	Beam Halo Measurements using Adaptive Masking Methods and Proposed Recent Halo Experiment	quadrupole, space-charge, diagnostics, simulation	215
	H.D. Zhang, B.L. Beaudoin, S. Bernal, R.B. Fiorito, R.A. Kishek, K. Řežaei, A.G. Shkvarunets UMD, College Park, Maryland, USA
	Beam halo is a common phenomenon in particle beams, especially for modern, advanced accelerators where high beam intensities lead to strong space charge. Halo is generally understood as a population of particles that do, or will, reach large transverse radii relative to a more intense, centralized beam core. It is associated with emittance growth, beam quality degradation and particle loss. The particle-core model [1] is commonly used to describe halo formation as the result of a parametric resonance due to envelope mismatch. Few experiments have been carried out to test this theory [2]. Measurement of beam halo is particularly problematic for faint halos, where light from the intense core obscures the optical image of the halo. In this paper, we present a new diagnostic for high-dynamic range halo measurements based on adaptive masking of the beam core [3]. We also present the design of an experiment to study halo formation from envelope mismatch for beams spanning a wide range of intensities on the University of Maryland Electron Ring (UMER) [4]. [1] R. Gluckstern, Phys. Rev. Lett., vol.73, 1994. [2] C. Allen, Phys. Rev. Lett. Vol 89, 1998 [3] H. Zhang, et al., Proc of PAC11. [4] R.A. Kishek, these proceedings.

TUO1A01	The High Intensity/High Brightness Upgrade Program at CERN: Status and Challenges	linac, emittance, space-charge, extraction	226
	S.S. Gilardoni, G. Arduini, T. Argyropoulos, S. Aumon, H. Bartosik, E. Benedetto, N. Biancacci, T. Bohl, J. Borburgh, C. Carli, F. Caspers, H. Damerau, J. Esteban Müller, V. Forte, R. Garoby, M. Giovannozzi, B. Goddard, S. Hancock, K. Hanke, A. Huschauer, G. Iadarola, M. Meddahi, G. Métral, B. Mikulec, E. Métral, Y. Papaphilippou, S. Persichelli, G. Rumolo, B. Salvant, F. Schmidt, E.N. Shaposhnikova, R. Steerenberg, G. Sterbini, M. Taborelli, H. Timko, M. Vretenar, R. Wasef, C. Yin Vallgren, C. Zannini CERN, Geneva, Switzerland G. Franchetti GSI, Darmstadt, Germany M. Migliorati University of Rome "La Sapienza", Rome, Italy A.Y. Molodozhentsev J-PARC, KEK & JAEA, Ibaraki-ken, Japan M.T.F. Pivi SLAC, Menlo Park, California, USA V.G. Vaccaro Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli, Italy
	The future beam brilliance and intensities required by the HL-LHC (High-Luminosity LHC) project and for possible new neutrino production beams triggered a deep revision of the LHC injector performances. The analysis, progressing in the framework of the LHC Injectors Upgrade (LIU) projects, outlined major limitations mainly related to collective effects - space charge in PSB and PS, electron cloud driven and TMCI instabilities in the SPS, longitudinal coupled bunch instabilities in the PS for example - but also to the existing hardware capability to cope with beam instabilities and losses. A summary of the observations and simulation studies carried out so far, as well as the future ones, will be presented. The solution proposed to overcome the different limitations and the plans for their implementation will be also briefly reviewed.
	Slides TUO1A01 [12.748 MB]

TUO1B01	Beam Loss Due to Foil Scattering in the SNS Accumulator Ring	scattering, proton, collimation, extraction	254
	J.A. Holmes, M.A. Plum ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. The Spallation Neutron Source is now operating in production mode at about 1 MW of beam power on target, which corresponds to more than 10¹⁴ protons per pulse at 60 Hz with energies exceeding 900 MeV. Although overall beam losses in production tune are low, the highest losses in the entire machine occur in the region downstream of the ring injection stripper foil. In order to better understand the contribution of scattering from the primary stripper foil to losses in the SNS ring, we have carried out calculations using the ORBIT Code aimed at evaluating these losses. These calculations indicate that the probability of beam loss within one turn following a foil hit is ~1.7·10^-8*T, where T is the foil thickness in g/cm², assuming a carbon foil. Thus, for a stripper foil of thickness T = 390 g/cm², the probability of loss within one turn of a foil hit is ~6.7·10^-6. This paper describes the calculations used to arrive at this result, presents the distribution of these losses around the SNS ring, and compares the the calculated loss distribution with that observed experimentally.
	Slides TUO1B01 [2.174 MB]

TUO1B02	Injection Design for Fermilab Project X	booster, linac, dipole, proton	259
	D.E. Johnson, C.-Y. Tan, Z. Tang Fermilab, Batavia, USA
	Fermilab is proposing a staged approach for Project X, a high power proton accelerator system. The first stage of this project will be to construct a 1 GeV CW H⁻ superconducting linear accelerator to inject into the existing 8 GeV Booster synchrotron ultimately providing in excess of 1 MW beam power for the Neutrino program out of the Main Injector. We will discuss the current project plans for injection into the Booster and related issues.
	Slides TUO1B02 [1.380 MB]

TUO1B04	Beam Loss Control for the Fermilab Main Injector	radiation, collimation, booster, quadrupole	264
	B.C. Brown Fermilab, Batavia, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. From 2005 through 2012, the Fermilab Main Injector provided intense beams of 120 GeV protons to produce neutrino beams and antiprotons. Hardware improvements in conjunction with improved diagnostics allowed the system to reach sustained operation at ~400 kW beam power. Losses were at or near the 8 GeV injection energy where 95\% beam transmission results in about 1.5 kW of beam loss. By minimizing and localizing loss, residual radiation levels fell while beam power was doubled. Lost beam was directed to either the collimation system or to the beam abort. Critical apertures were increased while improved instrumentation allowed optimal use of available apertures. We will summarize the impact of various loss control tools and the status and trends in residual radiation in the Main Injector.
	Slides TUO1B04 [1.356 MB]

TUO1C02	Online Monitoring System for the Waste Beam in the 3-GeV RCS of J-PARC	monitoring, proton, linac, target	297
	P.K. Saha, H. Harada, S. Hatakeyama, N. Hayashi, H. Hotchi, K. Yamamoto, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	We have established two independent methods for monitoring the waste beam of only about 0.4% in the 3 GeV Rapid Cycling Synchrotron of the Japan Proton Accelerator. Although using conventional monitor systems, the measurement technique made it possible for clearly measuring such a waste beam even with significantly low error. One of the method uses a current transformer to measure the waste beam as a whole, while the other one uses a multi-wire profile monitor for clearly measuring beam profiles of both un-stripped and partially stripped components of the waste beam. While the raw signal measured by a CT (current transformer) contains a large noise, an FFT (Fast Fourier Transformation) analysis made it possible to clearly identify the beam signal corresponding to the frequency of the intermediate pulse. The waste beam was measured to be (0.38±0.03)%. Being non destructive, the 1st method is efficiently operating for online monitoring of the waste beam during the RCS user operation so as to directly know the the stripper foil condition and would have great importance for higher power operation.
	Slides TUO1C02 [2.687 MB]

TUO1C03	The Beam Diagnostics of CSNS	diagnostics, emittance, linac, neutron	302
	T.G. Xu, J.N. Bai, C. Chen, L.X. Han, F. Li, P. Li, M. Meng, J.L. Sun, J.M. Tian, A.X. Wang, B. Wang, M.H. Xu, Zh.H. Xu, X.Y. Yang, L. Zeng IHEP, Beijing, People's Republic of China
	CSNS project is in the construction stage. The overview of CSNS beam diagnostics is presented which includes linac, RCS and both transport beam line. also some predevelopment of CSNS beam diagnostics is presented.
	Slides TUO1C03 [8.366 MB]

TUO1C04	Detection of Unidentified Falling Objects at LHC	emittance, simulation, proton, beam-losses	305
	E. Nebot Del Busto, T. Baer, F.V. Day, B. Dehning, E.B. Holzer, A. Lechner, R. Schmidt, J. Wenninger, C. Zamantzas, M. Zerlauth, F. Zimmermann CERN, Geneva, Switzerland M. Hempel BTU, Cottbus, Germany
	About 3600 Ionization Chambers are located around the LHC ring to detect beam losses that could damage the equipment or quench superconducting magnets. The BLMs integrate the losses in 12 different time intervals (from 40 μs to 83.8 s) allowing for different abort thresholds depending on the duration of the loss and the beam energy. The signals are also recorded in a database at 1 Hz for offline analysis. Since the 2010 run, a limiting factor in the machine availability occurred due to unforeseen sudden losses appearing around the ring on the ms time scale. Those were detected exclusively by the BLM system and they are the result of the interaction of macro-particles, of sizes estimated to be 1-100 microns, with the proton beams. In this document we describe the techniques employed to identify such events as well as the mitigations implemented in the BLM system to avoid unnecessary LHC downtime.
	Slides TUO1C04 [6.812 MB]

TUO1C05	Measurements and Interpretation of the Betatron Tune Spectra of High Intensity Bunched Beam at SIS-18	space-charge, synchrotron, ion, acceleration	310
	R. Singh, O. Chorniy, P. Forck, R. Haseitl, W. Kaufmann, P. Kowina, K. Lang GSI, Darmstadt, Germany O. Boine-Frankenheim, R. Singh, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	The paper presents the status of the transverse tune measurements in the synchrotron SIS18 at GSI. Presently, there are two systems for tune measurements in operation in the SIS18, namely TOPOS (Tune, Orbit and POsition measurement System) and BBQ (Base Band tune measurement system). The first one is a digital system where the BPM signal is digitized and the bunch position is calculated numerically. The second system is an analog system, where the transverse bunch motion is detected using peak detector. Band limited noise and chirp excitations were used to excite the betatron oscillations. Measurements of the betatron tune spectra were done at injection energy at medium and high intensities. In the frequency spectra a number of peaks around the position of betatron tune were seen. The peaks can be attributed to different bunch head-tail modes which were observed in time domain. These modes were dependent on the beam intensity. In this paper we compare the tune spectra measured at high beam intensity with the theoretical model for the space charge affected head-tail modes.
	Slides TUO1C05 [1.315 MB]

TUO3C02	FNAL Proton Source High Intensity Operations and Beam Loss Control	booster, proton, controls, cavity	320
	F.G.G. Garcia, W. Pellico Fermilab, Batavia, USA
	Funding: U.S. Department of Energy The Proton Source (PS) has been the workhorse of the Fermi National Accelerator Laboratory (FNAL) for over 40 years. During that time the United States High Energy Physics program has continued to change with increasing demands put on the PS. The past 10 years saw an increase of over 10 fold in required hourly flux for the PS and plans are now underway to have the capability to double the output with continued operations until at least 2025. To meet these goals, effort in area of beam loss control has been a major part of the upgrades. Beam collimation and absorption systems as well as diagnostics used to mitigate and control losses have been implemented. The recent implementation of new correctors for orbit and higher harmonic control has also been very beneficial. A summary of recent and planned modification to these PS systems will be discussed.
	Slides TUO3C02 [16.766 MB]

TUO3C04	Beam Loss Mitigation in the Oak Ridge Spallation Neutron Source	quadrupole, linac, DTL, neutron	329
	M.A. Plum ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. The Oak Ridge Spallation Neutron Source (SNS) accelerator complex routinely delivers 1 MW of beam power to the spallation target. Due to this high beam power, understanding and minimizing the beam loss is an ongoing focus area of the accelerator physics program. In some areas of the accelerator facility the equipment parameters corresponding to the minimum loss are very different from the design parameters. In this presentation we will summarize the SNS beam loss measurements, the methods used to minimize the beam loss, and a compare the design vs. the loss-minimized equipment parameters.
	Slides TUO3C04 [4.617 MB]

TUO3C05	Beam Commissioning Plan for CSNS Accelerators	DTL, linac, optics, target	334
	S. Wang, S. Fu, H.F. Ouyang, J. Peng IHEP, Beijing, People's Republic of China
	Funding: Supported by National Natural Science Foundation of China (11175193) The China Spallation Neutron Source (CSNS) is now under construction, and the beam commissioning of ion source will start from the end of 2013, and will last several years for whole accelerator. The commissioning plan for CSNS accelerators will be presented in the presentation, including the commissioning correlated parameters, the goal at different commissioning stages and some key commissioning procedures for each part of accelerators. The detailed schedule for commissioning will be also given.
	Slides TUO3C05 [3.574 MB]

TUO3C06	The Result of Beam Commissioning in J-PARC 3-GeV RCS	lattice, collimation, scattering, extraction	339
	H. Harada, N. Hayashi, H. Hotchi, M. Kinsho, P.K. Saha, Y. Shobuda, F. Tamura, K. Yamamoto, M. Yamamoto, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y. Irie, T. Koseki, Y. Sato, K. Satou, M.J. Shirakata KEK, Ibaraki, Japan S. Kato Tohoku University, Graduate School of Science, Sendai, Japan
	J-PARC 3-GeV RCS has started the beam commissioning since Oct. 2007. In the beam commissioning, the beam tuning for basic parameters and high-intensity operation has been continuously performed. This presentation will describe the results of the beam-loss reduction and minimization for high-intensity operation.
	Slides TUO3C06 [7.753 MB]

WEO1A02	LHC Impedance Model: Experience with High Intensity Operation in the LHC	impedance, octupole, brightness, damping	349
	B. Salvant, O. Aberle, G. Arduini, R.W. Aßmann, V. Baglin, M.J. Barnes, P. Baudrenghien, A. Bertarelli, C. Bracco, R. Bruce, X. Buffat, F. Carra, F. Caspers, G. Cattenoz, S.D. Claudet, H.A. Day, J. Esteban Müller, M. Garlaschè, L. Gentini, B. Goddard, A. Grudiev, B. Henrist, W. Herr, S. Jakobsen, R.J. Jones, G. Lanza, L. Lari, T. Mastoridis, N. Mounet, E. Métral, A.A. Nosych, J.L. Nougaret, S. Persichelli, T. Pieloni, A.M. Piguiet, S. Redaelli, F. Roncarolo, G. Rumolo, B. Salvachua, M. Sapinski, E.N. Shaposhnikova, L.J. Tavian, M.A. Timmins, J.A. Uythoven, A. Vidal, R. Wasef, D. Wollmann CERN, Geneva, Switzerland A.V. Burov Fermilab, Batavia, USA S.M. White BNL, Upton, Long Island, New York, USA
	The CERN Large Hadron Collider (LHC) is now in luminosity production mode and has been pushing its performance in the past months by increasing the proton beam brightness, the collision energy and the machine availability. As a consequence, collective effects have started to become more and more visible and have effectively slowed down the performance increase of the machine. Among these collective effects, the interaction of brighter LHC bunches with the longitudinal and transverse impedance of the machine has been observed to generate beam induced heating and transverse instabilities since 2010. This contribution reviews the current LHC impedance model obtained from theory, simulations and bench measurements as well as a selection of measured effects with the LHC beam.
	Slides WEO1A02 [7.991 MB]

WEO1A03	Resistive Wall Instability in CSNS/RCS	impedance, simulation, extraction, wakefield	354
	L. Huang, Y.D. Liu, S. Wang IHEP, Beijing, People's Republic of China
	Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) is a high intensity proton accelerator, with average beam power of 100kW. The collective effects caused by the coupling impedance may be the limit to beam power. The impedance estimation for components on beam line shows that the resistive wall impedance and its instability are more serious than any others. Based on the impedance budget, the instability is theoretically estimated. A simple resistive wall wake field model is used to simulate the bunch oscillation and obtain the growth time. In this simulation model, the continuous resistive wall wake field is concentrated to one position in the ring and the long bunch is sliced into many micro-bunches. By tracking the dynamics of the macro-bunches, the transverse growth time are obtained. The simulation results are also confirmed the restriction to instability by natural chromaticity. # Supported by National Natural Science Foundation of China (11175193) *wangs@ihep.ac.cn
	Slides WEO1A03 [1.358 MB]

WEO1B01	Low Gamma Transition Optics for the SPS: Simulation and Experimental Results for High Brightness Beams	optics, emittance, electron, extraction	381
	H. Bartosik, G. Arduini, T. Argyropoulos, T. Bohl, K. Cornelis, J. Esteban Müller, K.S.B. Li, Y. Papaphilippou, G. Rumolo, B. Salvant, F. Schmidt, E.N. Shaposhnikova, H. Timko CERN, Geneva, Switzerland A.Y. Molodozhentsev KEK, Ibaraki, Japan
	The single bunch transverse mode coupling instability (TMCI) at injection is presently one of the main intensity limitation for LHC beams in the SPS. A new optics for the SPS with lower transition energy yields an almost 3-fold increase of the slip factor at injection energy and thus a significantly higher TMCI threshold, as demonstrated both in simulations and in experimental studies. It is observed furthermore that the low gamma transition optics yields better longitudinal stability throughout the entire acceleration cycle. In addition, simulations predict a higher threshold for the electron cloud driven single bunch instability, which might become an important limitation for high intensity LHC beams with the nominal 25 ns bunch spacing. This contribution gives a summary of the experimental and simulation studies, addressing also space charge effects and the achievable brightness with high intensity single bunch beams.

WEO1B03	Circular Modes for Flat Beams in LHC	emittance, optics, space-charge, luminosity	391
	A.V. Burov Fermilab, Batavia, USA
	Benefits and problems for operation with flat beams are discussed.
	Slides WEO1B03 [0.192 MB]

WEO1B05	PTC-Orbit Studies for the CERN LHC Injectors Upgrade Project	emittance, booster, resonance, space-charge	399
	A.Y. Molodozhentsev, E. Forest KEK, Ibaraki, Japan G. Arduini, H. Bartosik, E. Benedetto, C. Carli, M. Fitterer, V. Forte, S.S. Gilardoni, M. Martini, N. Mounet, E. Métral, F. Schmidt, R. Wasef CERN, Geneva, Switzerland
	The future improvement of the beam brilliance and intensities required in the frame of the LIU (LHC Injectors Upgrade) project to reach the demands of the HL-LHC (High-Luminosity LHC) project triggered a comprehensive study of the combined effects of the space charge and the machine resonances for the CERN synchrotrons, which are the injector chain for LHC. In frame of this report we will summarize new features of the PTC-ORBIT code which allow the beam dynamics modeling in the LHC injectors taking into account the time variation of the machine parameters during the injection process. The measurements, obtained during recent MD companies, and simulations for the low-energy high-intensity beams, will be discussed.
	Slides WEO1B05 [3.063 MB]

WEO1C02	Simulation and Measurement of Half Integer Resonance in Coasting Beams in the ISIS Ring	resonance, simulation, synchrotron, space-charge	434
	C.M. Warsop, D.J. Adams, B. Jones, S.J. Payne, B.G. Pine, H. V. Smith, R.E. Williamson STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Operation centres on a high intensity proton synchrotron, accelerating 3·10¹³ ppp from 70-800 MeV, at a repetition rate of 50 Hz. Present studies are looking at key aspects of high intensity behaviour with a view to increasing operational intensity, identifying optimal upgrade routes and understanding loss mechanisms. Of particular interest is the space charge limit imposed by half integer resonance: we present results from coasting beam experiments with the ISIS ring in storage ring mode, along with detailed 3D (ORBIT) simulations to help interpret observations. The methods for experimentally approaching resonance, and the implications on beam behaviour, measurement and interpretation are discussed. In addition, results from simpler 2D simulations and analytical models are used to help interpret expected beam loss and halo evolution. Plans and challenges for the measurement and understanding of this important beam loss mechanism are summarised, as are some closely related areas of high intensity work on ISIS.
	Slides WEO1C02 [2.224 MB]

WEO1C03	Longitudinal Beam Loss Studies of the CERN PS-to-SPS Transfer	cavity, emittance, simulation, impedance	439
	H. Timko, T. Argyropoulos, T. Bohl, H. Damerau, J. Esteban Müller, S. Hancock, E.N. Shaposhnikova CERN, Geneva, Switzerland
	Bunch-to-bucket transfer between the Proton Synchrotron (PS) and the Super Proton Synchrotron (SPS) is required before beams can enter the Large Hadron Collider. The overall beam loss at this transfer is currently around 5-10 %, and is increased for higher intensities or larger longitudinal emittances. Previous attempts to reduce the losses with additional RF voltage from spare cavities in the PS were unsuccessful. In this paper, we modelled the complete PS flat-top bunch splitting and rotation manipulations, PS-to-SPS transfer, SPS flat bottom and acceleration ramp using end-to-end simulations. Starting from the measured bunch distributions, the simulations provide an accurate insight into the problem and allow direct benchmarking with experiments. As a result, it was understood and confirmed by measurements that shorter bunches do not necessarily lead to better transmission. The particle distribution in longitudinal phase space at PS extraction should be optimised instead. A significant loss reduction of up to 50 % is expected from simulations; experimental studies are on-going to verify these theoretical findings.
	Slides WEO1C03 [3.903 MB]

WEO1C04	Acceleration of High-Intensity Protons in the J-PARC Synchrotrons	synchrotron, cavity, extraction, proton	444
	M. Yoshii KEK/JAEA, Ibaraki-Ken, Japan
	The J-PARC consisting of the 181 MeV Linac, the 3GeV rapid cycling synchrotron (RCS) and the 50 GeV main synchrotron (MR), is the first high intensity proton synchrotron facility to use the high field gradient magnetic alloy (MA) loaded accelerating cavity. MA is a low-Q material. However, because of the high permeability and the high saturation magnetic flux density, the MA cores are the only materials to realize the required gradient. The MA loaded cavity can be considered as a stable passive load. No tuning control is necessary. 11 RF systems are installed in the RCS, and 8 RF systems in the MR. In addition, the RCS RF systems are operated in a dual harmonic mode to perform the acceleration and the longitudinal manipulation of the high intensity beam in the RCS available space. Beam loading compensation is an important issue. The feed-forward method using the RF beam signals from the wall current monitor has been established. The J-PARC synchrotrons realize stable, reproducible and clean acceleration of high intensity protons. A transition-free lattice and a precise digital timing system asynchronous to the AC-line are the distinctive features, which enable this achievement.
	Slides WEO1C04 [3.861 MB]

WEO1C05	Longitudinal Space Charge Phenomena in an Intense Beam in a Ring	space-charge, induction, focusing, electron	447
	R.A. Kishek, B.L. Beaudoin, D.W. Feldman, I. Haber, T.W. Koeth, Y. Mo UMD, College Park, Maryland, USA
	Funding: Supported by the US Dept. of Energy, Offices of High Energy Physics and Fusion Energy Sciences, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office. The University of Maryland Electron Ring (UMER) uses nonrelativistic, high-current electron beams to access the intense space charge dynamics applicable to hadron beams. The UMER beam parameters correspond to space charge incoherent tune shifts, at injection, in the range of 1-5.5 integers. Longitudinal induction focusing is used to counteract the space charge force at the edges of a long rectangular bunch, confining the beam for 100s of turns. We report on two recent findings: (1) The formation and propagation of solitons from large amplitude longitudinal perturbations, observed experimentally and reproduced in WARP* simulations. (2) The evolution of a longitudinal multi-streaming instability when the space-charge force is allowed to lengthen the bunch ends. The expanding bunch ends fill the ring, interpenetrate, and wrap repeatedly, forming multiple streams at any one location, each with its unique velocity. The resulting multi-stream instability is investigated over a wide range of beam currents and initial pulse lengths, and experimental observations are in good agreement with WARP simulations and an analytical theory that successfully predicts the onset of the instability. * D.P. Grote, A. Friedman, I. Haber, S. Yu, Fus. Eng. & Des. 32-33, 193-200 (1996).
	Slides WEO1C05 [5.868 MB]

WEO3C01	Injection and Stripping Foil Studies for a 180 MeV Injection Upgrade at ISIS	simulation, synchrotron, dipole, electron	456
	B. Jones, D.J. Adams, M.C. Hughes, S.J.S. Jago, B.G. Pine, H. V. Smith, C.M. Warsop, R.E. Williamson STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	The Rutherford Appleton Laboratory (RAL) is home to ISIS, the world's most productive spallation neutron source. ISIS has two neutron producing target stations (TS-1 and TS-2), operated at 40 Hz and 10 Hz respectively with a 50 Hz, 800 MeV proton beam from a rapid cycling synchrotron (RCS), which is fed by a 70 MeV H− drift tube linac. The multi-turn charge-exchange injection process used on ISIS has been the subject of a programme of detailed studies in recent years including benchmarked simulations and experiments. More recently, these studies have been expanded as plans for upgrading ISIS have focussed on replacement of the 70 MeV linac with a new, higher energy injector and a new synchrotron injection straight. Whilst much of these studies have been reported elsewhere, this paper presents a summary of the programme with some further details.
	Slides WEO3C01 [4.895 MB]

THO1A03	Dual-harmonic Acceleration Studies at CSNS RCS	acceleration, simulation, bunching, cavity	487
	J.F. Chen, J.Y. Tang, X. Zhang IHEP, Beijing, People's Republic of China
	Dual harmonic acceleration is proposed to alleviate the space charge effects in the RCS (Rapid Cycling Synchrotron) at the upgrading stages of the CSNS (China Spallation Neutron Source). Different dual harmonic acceleration schemes have been studied by using a self-made parameter calculation code - RAMADH and the simulation code - ORBIT. Both complete and partial coverage of the dual harmonic RF system along the acceleration have been considered. The injection by combining beam chopping and off-momentum is used in the macro-particle tracking simulations by ORBIT. In addition, a new idea that unlocks the RF frequency and the magnetic field in the injection period is found very useful in obtaining a good longitudinal painting.
	Slides THO1A03 [1.343 MB]

THO1A04	High Intensity Longitudinal Dynamics Studies for an ISIS Injection Upgrade	simulation, synchrotron, bunching, space-charge	492
	R.E. Williamson, D.J. Adams, C.M. Warsop STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is the world's most productive pulsed neutron and muon source, at the Rutherford Appleton Laboratory in the UK. Operation is centred on a loss-limited 50 Hz proton synchrotron which accelerates 3·10¹³ protons per pulse from 70 MeV to 800 MeV, delivering a mean beam power of 0.2 MW. Recent upgrade studies at ISIS have centred on a new 180 MeV linac for injection into the existing ring offering the possibility of beam powers in the 0.5 MW regime through reduction in space charge and optimized injection. A central and critical aspect of such an upgrade is the longitudinal dynamics including beam stability, associated RF parameters, space charge levels and stringent requirements on beam loss. This paper outlines possible longitudinal injection schemes for the injection upgrade meeting key design requirements such as minimising halo, bunching factor and satisfying the Keil-Schnell-Boussard (KSB) stability criterion throughout acceleration. Details of simulation models including calculation of KSB are given together with associated assumptions. Latest results from studies to understand and confirm stability limits on ISIS via simulation and experiment are presented.
	Slides THO1A04 [2.641 MB]

THO3A03	Simulations and Measurements in High Intensity LEBT with Space Charge Compensation	emittance, simulation, space-charge, rfq	507
	N. Chauvin CEA/IRFU, Gif-sur-Yvette, France O. Delferrière, R. Gobin, P.A.P. Nghiem, D. Uriot CEA/DSM/IRFU, France R.D. Duperrier ESS, Lund, Sweden
	Over the last years, the interest of the international scientific community for high power accelerators in the megawatt range has been increasing. One of the major challenges is to extract and transport the beam while minimizing the emittance growth in the Low Energy Beam Transport line (LEBT). Consequently, it is crucial to perform precise simulations and cautious design of LEBT. In particular, the beam dynamics calculations have to take into account not only the space charge effects but also the space charge compensation of the beam induced by ionization of the residual gas. The code SOLMAXP has been developed in CEA-Saclay to perform self-consistent calculations taking into account space charge compensation. Extensive beam dynamics simulations have been done with this code to design the IFMIF LEBT (Deuteron beam of 125 mA at 100 keV, cw). The commissioning of the IFMIF injector started a few months ago and emmittance measurements of H⁺ and D⁺ beams have been done. The first experimental results will be presented and compared to simulation.
	Slides THO3A03 [3.165 MB]

THO3A04	Beam Halo Definitions and its Consequences	emittance, linac, beam-losses, space-charge	511
	P.A.P. Nghiem, N. Chauvin, D. Uriot CEA/DSM/IRFU, France W. Simeoni CEA/IRFU, Gif-sur-Yvette, France
	In high-intensity accelerators, much attention is paid to the beam halo: formation, growth interaction with the beam core, etc. Indeed, beam losses, a critical issue for those high-power accelerators, directly depend on the beam halo behaviour. But in the presence of very strong space-charge forces, the beam distribution takes very different shapes along the accelerator, often very far from any regular distributions, with very varied halo extensions. The difficulty is then to find a general definition of the halo capable of describing any distribution type. This paper proposes a definition of the beam halo, studies its consequences and compares it to the most usual ones.
	Slides THO3A04 [9.030 MB]

THO1C02	Beam Loss Control in the ISIS Accelerator Facility	synchrotron, controls, proton, acceleration	560
	D.J. Adams, B. Jones, A.H. Kershaw, S.J. Payne, B.G. Pine, H. V. Smith, C.M. Warsop, R.E. Williamson, M. Wright STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	The ISIS spallation neutron and muon source has been in operation since 1984. The accelerator complex consists of an H⁻ ion source, RFQ, 70 MeV linac, 800 MeV proton synchrotron and associated beam lines. The facility currently delivers ~2.8·10¹³ protons per pulse at 50 Hz, splitting the pulses 40/10 between two neutron target stations. High intensity performance and operation are dominated by the need to control beam loss, which is key to sustainable machine operation and hands on maintenance. Beam loss measurement systems on ISIS are described, along with typical operational levels. The dominant beam loss in the facility occurs in the synchrotron due to high intensity effects during the H⁻ injection and longitudinal trapping processes. These losses are localised in a single superperiod using a beam collector system. Emittance growth during acceleration also drives extraction and beam transport loss at 800 MeV. Measurements, simulation and correction systems for these processes are discussed, as are the implications for further intensity upgrades.
	Slides THO1C02 [4.759 MB]

THO1C04	Performances and Future Plans of the LHC RF	cavity, klystron, emittance, impedance	565
	P. Baudrenghien, T. Mastoridis CERN, Geneva, Switzerland
	The ramp-up of the LHC operation has been exceptionally fast: from the first acceleration of a single bunch at nominal intensity (1.1· E11 p) to 3.5 TeV/c on May 2010, to the accumulation of 11 fb-1 integrated luminosity two years later (June 2012). On the RF side this was made possible by a few key design choices and several developments, that allow reliable LHC operation with 0.35 A DC beam at 4 TeV/c (1380 bunches at 50 ns spacing, 1.5·10¹¹ p per bunch). This paper reviews the RF design and presents its performance. Plans are also outlined that would allow operation with 25 ns bunch spacing (doubling the beam current) and even increased bunch intensity with the target of above 1A DC current per beam, without big modification to the existing RF power system.
	Slides THO1C04 [9.945 MB]

THO1C06	Recent Commissioning of High-intensity Proton Beams in J-PARC Main Ring	beam-losses, proton, kicker, acceleration	575
	Y. Sato, K. Hara, Y. Hashimoto, Y. Hori, S. Igarashi, K. Ishii, N. Kamikubota, T. Koseki, Y. Kurimoto, K. Niki, K. Ohmi, C. Ohmori, M. Okada, M. Shimamoto, M.J. Shirakata, T. Sugimoto, J. Takano, M. Tejima, T. Toyama, M. Uota, S. Yamada, N. Yamamoto, M. Yoshii KEK, Ibaraki, Japan S. Hatakeyama, H. Hotchi, F. Tamura JAEA/J-PARC, Tokai-mura, Japan S. Nakamura, K. Satou J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	J-PARC main ring (MR) provides high power proton beams of 200 kW to the neutrino experiment. Beam losses were well managed within capacity of collimation system. Since this beam power was achieved by shortening the repetition rate, following tunings had been applied in order to reduce the beam losses, such as improvement of tune flatness, chromaticity correction, upgrades of injection kickers, dynamic bunch-by-bunch feed-back to suppress transverse oscillation, beam loading compensation using feed-forward technique, and balancing the collimators of MR and the injection beam transport line. The dynamic bunch-by-bunch feed-back was effective to reduce the beam losses to one-tenth during injection and beginning of acceleration. With the beam loading compensation, impedance seen by the beam was significantly reduced, longitudinal oscillations were damped, and the beam power was increased over 5% without increasing the beam losses. Monitors were upgraded to find time structure and location of the beam losses, even in first several turns after each injection. In this presentation these commissioning procedures and beam dynamics simulations are shown, and our upgrade plan is discussed.
	Slides THO1C06 [2.193 MB]

FRO1A03	Accelerator System Design, Injection, Extraction and Beam-Material Interaction: Working Group C Summary Report	collimation, ion, proton, simulation	615
	N.V. Mokhov Fermilab, Batavia, USA D. Li LBNL, Berkeley, California, USA
	Working Group C summary:The performance of high beam power accelerators is strongly dependent on appropriate injection, acceleration and extraction system designs as well as on the way interactions of the beam with machine components are handled. The experience of the previous ICFA High-Brightness Beam workshops has proven that it is quite beneficial to combine analyses and discussion of these issues in one group, WG-C at this Workshop. A broad range of topics was presented and discussed in twenty talks at four WG-C sessions as well as at two joint WGA/C and WG-B/C sessions. Highlights from these talks, outstanding issues along with plans and proposals for future work are briefly described.
	Slides FRO1A03 [4.907 MB]

FRO1B01	Summary of the Working Group on Commissioning and Operation	beam-losses, linac, proton, simulation	620
	R. Schmidt CERN, Geneva, Switzerland M.A. Plum ORNL, Oak Ridge, Tennessee, USA Y. Sato J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	The Working Group D summary report focussed on answering the following issues: observation of beam losses (e.g. time structure, other parameters,…), reducing beam losses with operational parameters away from the design set points, reducing beam losses (or concentrating beam losses at a few locations) using collimators, minimizing beam losses due to beam transfer from one accelerator to the following accelerator - what parameters are important? The issue of reducing beam losses with operational parameters away from the design set points is especially valuable as it is rarely discussed.
	Slides FRO1B01 [0.426 MB]

Paper

Title

Other Keywords

Page

MOI1A01

LHC - Challenges in Handling Beams Exceeding 100 MJ

beam-losses, luminosity, insertion, collimation

1

R. Schmidt
CERN, Geneva, Switzerland

The Large Hadron Collider (LHC) at CERN operates at 4 TeV with high intensity beams, with bunch intensities exceeding the nominal value by several 10 %. The energy stored in each beams is beyond 130 MJ, less than a factor of three from the nominal value at 7 TeV. With these parameters, operation entered into a regime where various effects due to high intensity bunches are observed (instabilities, beam-beam effects, e-cloud effects). The highly efficient collimation system limits beam losses that threaten to quench superconducting magnets. The correct functioning of the machine protection systems is vital during the different operational phases, where already a small fraction of the stored energy is sufficient to damage accelerator equipment or experiments in case of uncontrolled beam loss. Safe operation in presence of such high intensity proton beams is guaranteed by the interplay of many different systems: beam dumping system, beam interlocks, beam instrumentation, equipment monitoring, collimators and absorbers. The experience gained with the key systems of LHC machine protection and collimation will be discussed.

Slides MOI1A01 [31.116 MB]

MOI1B02

Technological Challenges for High-Intensity Proton Rings

linac, proton, acceleration, space-charge

15

Y. Yamazaki
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
High-intensity, pulsed proton accelerators have been and will be requested by a wide variety of scientific fields and industrial and medical applications, for example, pulsed spallation neutron sources and neutrino sources. We will focus our discussion on the proton rings with a pulse length of a few μsec and a beam power of MW. These accelerators may be used for boosting injectors to higher-energy accelerators, like a neutrino factories. At first, we will discuss on the space-charge force which limit the stored charges in a ring together with the negative-ion injection scheme. The pulsed spallation neutron sources are classified into two schemes. One is the combination of a full-energy linac and an accumulation ring (AR) exemplified by SNS and LANSCE. The other is that of a low-energy linac and a Rapid-Cycle Synchrotron (RCS) exemplified by J-PARC RCS and ISIS. In general, pros and cons of accelerator schemes are dependent upon the technological development results. Pros and cons of AR versus RCS will be discussed on the basis of recent technological developments and beam experiment data together with the future perspectives for MW-class machines.

Slides MOI1B02 [3.850 MB]

MOP203

Bunch-by-Bunch Beam Loss Diagnostics with Diamond Detectors at the LHC

beam-losses, proton, kicker, simulation

41

M. Hempel
BTU, Cottbus, Germany
T. Baer
University of Hamburg, Hamburg, Germany
S. Bart Pedersen, B. Dehning, E. Effinger, E. Griesmayer, A. Lechner, R. Schmidt
CERN, Geneva, Switzerland
W. Lohmann
DESY, Hamburg, Germany

A main challenge in the operation with high intensity beams is managing beam losses that imply the risk of quenching superconducting magnets or even damage equipment. There are various sources of beam losses, such as losses related to injection, to beam instabilities and to UFOs (Unidentified Falling Objects). Mostly surprising in the first years of LHC operation was the observation of UFOs. They are believed to be dust particles with a typical size of 1-100 um, which lead to beam losses with a duration of about ten revolutions when they fall into the beam. 3600 BLMs (Beam Loss Monitors) are installed around the LHC ring, allowing to determinate the accurate location of UFOs. The time resolution of the BLMs is 40 us (half a turn revolution). A measurement of the beam losses with a time resolution better than the bunch spacing of 50 ns is crucial to understand loss mechanisms. Diamond sensors are able to provide such diagnostics and perform particle counting with ns time resolution. In this paper, we present measurements of various types of beam losses with diamond detectors. We also compare measurements of UFO induced beam losses around the LHC ring with results from MadX simulations.

MOP204

A Method to Measure the Incoherent Synchrotron Frequencies in Bunches

space-charge, simulation, synchrotron, dipole

46

O. Chorniy, H. Reeg
GSI, Darmstadt, Germany

The method of measuring the incoherent synchrotron frequencies in a stationary bunch is presented. It can be shown that by measuring the local current at a fixed coordinate in RF bucket the corresponding incoherent synchrotron frequency can be obtained. Test calculations were done using simulation data where longitudinal space charge effects were included. The incoherent frequencies obtained with method are in a good agreement with theory. In real experiment, the incoherent frequencies were determined from bunch profiles recorded in the SIS18 with low intensity beam at injection energy. Bunch profiles were measured with a new Fast Current Transformer which has a relatively broad frequency range. The profiles were recorded using 8 bit resolution oscilloscope. The frequency spectra of local current fluctuation at different longitudinal positions were obtained numerically. The strongest lines in these spectra were at positions of theoretically expected incoherent frequencies. In this paper the method is described in details, the comparison of incoherent frequencies obtained from the simulation and measurement data with theoretical solutions is shown.

MOP209

High Intensity Proton FFAG Ring with Serpentine Acceleration for ADS

acceleration, proton, closed-orbit, transverse-dynamics

60

E. Yamakawa, Y. Ishi, Y. Kuriyama, J.-B. Lagrange, Y. Mori, T. Uesugi
Kyoto University, Research Reactor Institute, Osaka, Japan

In order to produce high intensity proton beam for ADS, a new type of fixed rf acceleration scheme, so-called serpentine acceleration, is examined in scaling FFAG. Longitudinal hamiltonian for scaling FFAG is first derived analytically. Then the features of serpentine acceleration in longitudinal phase space are studied. Ring design for ADS is finally shown.

MOP210

Beam Stacking for High Intensity Pulsed Proton Beam with FFAG

acceleration, simulation, extraction, neutron

64

Y. Mori, Y. Ishi, Y. Kuriyama, J.-B. Lagrange, T. Uesugi
Kyoto University, Research Reactor Institute, Osaka, Japan

Multi-beam stacking scheme to generate an intense short-pulsed proton beam with high repetition proton FFAG is presented.

MOP211

1-MW Beam Operation Scenario in the J-PARC RCS

quadrupole, emittance, lattice, controls

68

H. Hotchi, H. Harada, N. Hayashi, M. Kinsho, P.K. Saha, Y. Shobuda, F. Tamura, K. Yamamoto, M. Yamamoto, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y. Irie
KEK, Ibaraki, Japan

The injection energy of the J-PARC RCS will be upgraded from 181 MeV to 400 MeV in the 2013 summer-autumn period. With this upgraded injection energy, we are to aim for 1 MW design output beam power. In this paper, we discuss beam dynamics issues for the 1 MW beam operation and their possible solutions.

MOP213

Beam Losses due to the Foil Scattering for CSNS/RCS

beam-losses, scattering, proton, electron

78

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

For the Rapid Cycling Synchrotron of China Spallation Neutron Source (CSNS/RCS), the stripping foil scattering generates the beam halo and gives rise to additional beam losses during the injection process. The interaction between the proton beam and the stripping foil was discussed and the foil scattering was studied. A simple model and the realistic situation of the foil scattering were considered. By using the codes ORBIT and FLUKA, the multi-turn phase space painting injection process with the stripping foil scattering for CSNS/RCS was simulated and the beam losses due to the foil scattering were obtained.

MOP216

The Design Study on the Longitudinal Beam Dynamics for CSNS/RCS

acceleration, simulation, space-charge, bunching

89

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

Rapid Cycling Synchrotron (RCS) is the key part of China Spallation Neutron Source (CSNS) accelerators. The RCS accumulates and accelerates 80 MeV beam from linac to 1.6 GeV. The particle number is 1.56·10¹³ for each pulse, with repetition rate of 25 Hz. In the RCS, longitudinal beam dynamics plays a crucial role in achieving high intensity beam with low beam loss. Longitudinal parameters are studied and optimized for efficient RF trapping of the beam in the longitudinal phase space. Beam performance is investigated by particle tracking simulations. Beam dynamic issues related to the high order mode induced by the RF generator are studied with a new developed code. Primary study on the adoption of dual harmonic cavity for higher beam power is also addressed.

MOP247

Beam Stability and Tail Population at SPS Scrapers

emittance, extraction, controls, diagnostics

166

L.N. Drøsdal, K. Cornelis, B. Goddard, V. Kain, M. Meddahi, O. Mete, B. Mikulec, E. Veyrunes
CERN, Geneva, Switzerland

Before injection into the LHC the beams are scraped in the SPS to remove the tails of the transverse particle distributions. Without scraping the tail population is large enough to create losses above the beam abort thresholds of the LHC beam loss monitor system when injecting. The scrapers are only effective if correctly set up. This paper shows the results of periodical scraper scans. The beam position and beam size at the scraper is changing with time. The scraper settings hence need to follow accordingly. The scans also give insight into the transverse tail population and could therefore provide useful beam quality diagnostics. The impact on new scraper designs and setting up strategy are discussed.

MOP248

Brightness Evolution for LHC Beams during the 2012 Run

emittance, brightness, luminosity, extraction

170

M. Kuhn
Uni HH, Hamburg, Germany
G. Arduini, J.F. Comblin, A. Guerrero, V. Kain, B. Mikulec, F. Roncarolo, M. Sapinski, M. Schaumann, R. Steerenberg
CERN, Geneva, Switzerland

One of the reasons for the remarkable achievements of the LHC is the excellent performance of the LHC injector chain. The evolution of the brightness in the injectors and at LHC collision in 2011 and 2012 is discussed. During certain run periods, the brightness from the beam provided by the injectors was lower than usual. Some of the issues have been identified so far and will be reported. The latest results on emittance blow-up investigations through the 2012 LHC cycle will also be presented and compared to the 2011 data. Possible implications for LHC upgrade scenarios will be mentioned.

MOP249

Tune Spread Studies at Injection Energies for the CERN Proton Synchrotron Booster

emittance, linac, space-charge, proton

175

B. Mikulec, A. Findlay, V. Raginel, G. Rumolo, G. Sterbini
CERN, Geneva, Switzerland

In the near future, a new H⁻ injector, Linac4, will replace the current proton injector of the CERN Proton Synchrotron Booster (PSB), Linac2. The new charge-exchange injection at 160 MeV will yield higher brightness beams compared to the conventional 50 MeV multi-turn injection of Linac2. To make full use of the higher injection energy, space-charge effects will need to be understood and mitigated to optimize the intensity versus transverse emittance reach. This includes an optimization of longitudinal acceptance and distribution with a two-harmonic rf system, careful selection of the working point to accommodate the large Laslett tune-shift of approximately -0.5 and compensation of resonances within their stopbands. This paper will present calculations of the tune spread, based on measurements of longitudinal parameters and transverse emittances, for energies up to 160 MeV, different bunch densities and varying beam intensities. It should provide valuable information on the expected tune spread after the connection of Linac4 with the PSB and input for the study of resonance compensation techniques.

MOP255

Acceleration in Vertical Orbit Excursion FFAGs with Edge Focussing

space-charge, proton, simulation, acceleration

197

S.J. Brooks
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

FFAGs with vertical orbit excursion (VFFAGs) provide a promising alternative design for rings with fixed-field superconducting magnets. They have a vertical magnetic field component that increases with height in the vertical aperture, yielding a skew quadrupole focussing structure. Edge focussing can provide an alternating gradient within each magnet, thus reducing the ring circumference. Like spiral scaling horizontal FFAGs (but not non-scaling ones) the machine has fixed tunes and no intrinsic limitation on momentum range. Rings to accelerate the 800MeV beam from the ISIS proton synchrotron are investigated, in terms of both magnet field geometry and longitudinal behaviour during acceleration with space charge. The 12GeV ring produces an output power of at least 2.18MW.

MOP256

High-power Scaling FFAG Ring Studies

space-charge, scattering, lattice, dynamic-aperture

202

D.J. Kelliher, S. Machida, G.H. Rees
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

High-power scaling FFAG rings have potential application in areas such as neutron spallation, muon production, and accelerator-driven systems. It is proposed to build a model of such a ring in order to study major issues such as space charge and injection. A 20 ' 70 MeV radial DFD FFAG model, that was initially described in *, incorporates long straights to facilitate H⁻ charge exchange injection. Bump magnets are used to move the injected beam away from the foil. The effect of the injection process on the beam emittance is considered. The tune depression and emittance blow up resulting from the effect of space charge is also calculated.
* G.H. Rees et al, ‘A Model for a High-Power Scaling FFAG Ring', IPAC12, New Orleans, 2012, MOPPD020, http://www. JACow.org

MOP257

Space Charge Limits on the ISIS Synchrotron including the Effects of Images

simulation, space-charge, synchrotron, resonance

206

B.G. Pine, C.M. Warsop
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The ISIS synchrotron provides a pulsed, 50 Hz, 800 MeV proton beam for spallation neutron production. Each pulse from the synchrotron contains ~2.8×10¹³ ppp, and at this beam intensity space charge and image forces have a strong effect on transverse beam dynamics. In order to increase intensity in the present machine, and to prepare for possible upgrades running at a higher intensity, studies are under way aimed at understanding the most critical features of such forces and their impact on beam loss. These studies are focused on working point optimisation, including resonances due to space charge and images. A 2D simulation code, Set, has been developed to improve understanding of transverse dynamics at ISIS, using a particle-in-cell algorithm to include space charge and image forces self-consistently. The ISIS synchrotron has profiled vacuum vessels and RF shields which conform to the shape of the beam envelope, and have a distinctive influence on the beam dynamics. Set is specifically designed to include these image forces. A systematic simulation study of possible working points is presented, along with an assessment of the effect on apertures.

MOP260

Beam Halo Measurements using Adaptive Masking Methods and Proposed Recent Halo Experiment

quadrupole, space-charge, diagnostics, simulation

215

H.D. Zhang, B.L. Beaudoin, S. Bernal, R.B. Fiorito, R.A. Kishek, K. Řežaei, A.G. Shkvarunets
UMD, College Park, Maryland, USA

Beam halo is a common phenomenon in particle beams, especially for modern, advanced accelerators where high beam intensities lead to strong space charge. Halo is generally understood as a population of particles that do, or will, reach large transverse radii relative to a more intense, centralized beam core. It is associated with emittance growth, beam quality degradation and particle loss. The particle-core model [1] is commonly used to describe halo formation as the result of a parametric resonance due to envelope mismatch. Few experiments have been carried out to test this theory [2]. Measurement of beam halo is particularly problematic for faint halos, where light from the intense core obscures the optical image of the halo. In this paper, we present a new diagnostic for high-dynamic range halo measurements based on adaptive masking of the beam core [3]. We also present the design of an experiment to study halo formation from envelope mismatch for beams spanning a wide range of intensities on the University of Maryland Electron Ring (UMER) [4].
[1] R. Gluckstern, Phys. Rev. Lett., vol.73, 1994.
[2] C. Allen, Phys. Rev. Lett. Vol 89, 1998
[3] H. Zhang, et al., Proc of PAC11.
[4] R.A. Kishek, these proceedings.

TUO1A01

The High Intensity/High Brightness Upgrade Program at CERN: Status and Challenges

linac, emittance, space-charge, extraction

226

S.S. Gilardoni, G. Arduini, T. Argyropoulos, S. Aumon, H. Bartosik, E. Benedetto, N. Biancacci, T. Bohl, J. Borburgh, C. Carli, F. Caspers, H. Damerau, J. Esteban Müller, V. Forte, R. Garoby, M. Giovannozzi, B. Goddard, S. Hancock, K. Hanke, A. Huschauer, G. Iadarola, M. Meddahi, G. Métral, B. Mikulec, E. Métral, Y. Papaphilippou, S. Persichelli, G. Rumolo, B. Salvant, F. Schmidt, E.N. Shaposhnikova, R. Steerenberg, G. Sterbini, M. Taborelli, H. Timko, M. Vretenar, R. Wasef, C. Yin Vallgren, C. Zannini
CERN, Geneva, Switzerland
G. Franchetti
GSI, Darmstadt, Germany
M. Migliorati
University of Rome "La Sapienza", Rome, Italy
A.Y. Molodozhentsev
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
M.T.F. Pivi
SLAC, Menlo Park, California, USA
V.G. Vaccaro
Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli, Italy

The future beam brilliance and intensities required by the HL-LHC (High-Luminosity LHC) project and for possible new neutrino production beams triggered a deep revision of the LHC injector performances. The analysis, progressing in the framework of the LHC Injectors Upgrade (LIU) projects, outlined major limitations mainly related to collective effects - space charge in PSB and PS, electron cloud driven and TMCI instabilities in the SPS, longitudinal coupled bunch instabilities in the PS for example - but also to the existing hardware capability to cope with beam instabilities and losses. A summary of the observations and simulation studies carried out so far, as well as the future ones, will be presented. The solution proposed to overcome the different limitations and the plans for their implementation will be also briefly reviewed.

Slides TUO1A01 [12.748 MB]

TUO1B01

Beam Loss Due to Foil Scattering in the SNS Accumulator Ring

scattering, proton, collimation, extraction

254

J.A. Holmes, M.A. Plum
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.
The Spallation Neutron Source is now operating in production mode at about 1 MW of beam power on target, which corresponds to more than 10¹⁴ protons per pulse at 60 Hz with energies exceeding 900 MeV. Although overall beam losses in production tune are low, the highest losses in the entire machine occur in the region downstream of the ring injection stripper foil. In order to better understand the contribution of scattering from the primary stripper foil to losses in the SNS ring, we have carried out calculations using the ORBIT Code aimed at evaluating these losses. These calculations indicate that the probability of beam loss within one turn following a foil hit is ~1.7·10^-8*T, where T is the foil thickness in g/cm², assuming a carbon foil. Thus, for a stripper foil of thickness T = 390 g/cm², the probability of loss within one turn of a foil hit is ~6.7·10^-6. This paper describes the calculations used to arrive at this result, presents the distribution of these losses around the SNS ring, and compares the the calculated loss distribution with that observed experimentally.

Slides TUO1B01 [2.174 MB]

TUO1B02

Injection Design for Fermilab Project X

booster, linac, dipole, proton

259

D.E. Johnson, C.-Y. Tan, Z. Tang
Fermilab, Batavia, USA

Fermilab is proposing a staged approach for Project X, a high power proton accelerator system. The first stage of this project will be to construct a 1 GeV CW H⁻ superconducting linear accelerator to inject into the existing 8 GeV Booster synchrotron ultimately providing in excess of 1 MW beam power for the Neutrino program out of the Main Injector. We will discuss the current project plans for injection into the Booster and related issues.

Slides TUO1B02 [1.380 MB]

TUO1B04

Beam Loss Control for the Fermilab Main Injector

radiation, collimation, booster, quadrupole

264

B.C. Brown
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
From 2005 through 2012, the Fermilab Main Injector provided intense beams of 120 GeV protons to produce neutrino beams and antiprotons. Hardware improvements in conjunction with improved diagnostics allowed the system to reach sustained operation at ~400 kW beam power. Losses were at or near the 8 GeV injection energy where 95\% beam transmission results in about 1.5 kW of beam loss. By minimizing and localizing loss, residual radiation levels fell while beam power was doubled. Lost beam was directed to either the collimation system or to the beam abort. Critical apertures were increased while improved instrumentation allowed optimal use of available apertures. We will summarize the impact of various loss control tools and the status and trends in residual radiation in the Main Injector.

Slides TUO1B04 [1.356 MB]

TUO1C02

Online Monitoring System for the Waste Beam in the 3-GeV RCS of J-PARC

monitoring, proton, linac, target

297

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

We have established two independent methods for monitoring the waste beam of only about 0.4% in the 3 GeV Rapid Cycling Synchrotron of the Japan Proton Accelerator. Although using conventional monitor systems, the measurement technique made it possible for clearly measuring such a waste beam even with significantly low error. One of the method uses a current transformer to measure the waste beam as a whole, while the other one uses a multi-wire profile monitor for clearly measuring beam profiles of both un-stripped and partially stripped components of the waste beam. While the raw signal measured by a CT (current transformer) contains a large noise, an FFT (Fast Fourier Transformation) analysis made it possible to clearly identify the beam signal corresponding to the frequency of the intermediate pulse. The waste beam was measured to be (0.38±0.03)%. Being non destructive, the 1st method is efficiently operating for online monitoring of the waste beam during the RCS user operation so as to directly know the the stripper foil condition and would have great importance for higher power operation.

Slides TUO1C02 [2.687 MB]

TUO1C03

The Beam Diagnostics of CSNS

diagnostics, emittance, linac, neutron

302

T.G. Xu, J.N. Bai, C. Chen, L.X. Han, F. Li, P. Li, M. Meng, J.L. Sun, J.M. Tian, A.X. Wang, B. Wang, M.H. Xu, Zh.H. Xu, X.Y. Yang, L. Zeng
IHEP, Beijing, People's Republic of China

CSNS project is in the construction stage. The overview of CSNS beam diagnostics is presented which includes linac, RCS and both transport beam line. also some predevelopment of CSNS beam diagnostics is presented.

Slides TUO1C03 [8.366 MB]

TUO1C04

Detection of Unidentified Falling Objects at LHC

emittance, simulation, proton, beam-losses

305

E. Nebot Del Busto, T. Baer, F.V. Day, B. Dehning, E.B. Holzer, A. Lechner, R. Schmidt, J. Wenninger, C. Zamantzas, M. Zerlauth, F. Zimmermann
CERN, Geneva, Switzerland
M. Hempel
BTU, Cottbus, Germany

About 3600 Ionization Chambers are located around the LHC ring to detect beam losses that could damage the equipment or quench superconducting magnets. The BLMs integrate the losses in 12 different time intervals (from 40 μs to 83.8 s) allowing for different abort thresholds depending on the duration of the loss and the beam energy. The signals are also recorded in a database at 1 Hz for offline analysis. Since the 2010 run, a limiting factor in the machine availability occurred due to unforeseen sudden losses appearing around the ring on the ms time scale. Those were detected exclusively by the BLM system and they are the result of the interaction of macro-particles, of sizes estimated to be 1-100 microns, with the proton beams. In this document we describe the techniques employed to identify such events as well as the mitigations implemented in the BLM system to avoid unnecessary LHC downtime.

Slides TUO1C04 [6.812 MB]

TUO1C05

Measurements and Interpretation of the Betatron Tune Spectra of High Intensity Bunched Beam at SIS-18

space-charge, synchrotron, ion, acceleration

310

R. Singh, O. Chorniy, P. Forck, R. Haseitl, W. Kaufmann, P. Kowina, K. Lang
GSI, Darmstadt, Germany
O. Boine-Frankenheim, R. Singh, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

The paper presents the status of the transverse tune measurements in the synchrotron SIS18 at GSI. Presently, there are two systems for tune measurements in operation in the SIS18, namely TOPOS (Tune, Orbit and POsition measurement System) and BBQ (Base Band tune measurement system). The first one is a digital system where the BPM signal is digitized and the bunch position is calculated numerically. The second system is an analog system, where the transverse bunch motion is detected using peak detector. Band limited noise and chirp excitations were used to excite the betatron oscillations. Measurements of the betatron tune spectra were done at injection energy at medium and high intensities. In the frequency spectra a number of peaks around the position of betatron tune were seen. The peaks can be attributed to different bunch head-tail modes which were observed in time domain. These modes were dependent on the beam intensity. In this paper we compare the tune spectra measured at high beam intensity with the theoretical model for the space charge affected head-tail modes.

Slides TUO1C05 [1.315 MB]

TUO3C02

FNAL Proton Source High Intensity Operations and Beam Loss Control

booster, proton, controls, cavity

320

F.G.G. Garcia, W. Pellico
Fermilab, Batavia, USA

Funding: U.S. Department of Energy
The Proton Source (PS) has been the workhorse of the Fermi National Accelerator Laboratory (FNAL) for over 40 years. During that time the United States High Energy Physics program has continued to change with increasing demands put on the PS. The past 10 years saw an increase of over 10 fold in required hourly flux for the PS and plans are now underway to have the capability to double the output with continued operations until at least 2025. To meet these goals, effort in area of beam loss control has been a major part of the upgrades. Beam collimation and absorption systems as well as diagnostics used to mitigate and control losses have been implemented. The recent implementation of new correctors for orbit and higher harmonic control has also been very beneficial. A summary of recent and planned modification to these PS systems will be discussed.

Slides TUO3C02 [16.766 MB]

TUO3C04

Beam Loss Mitigation in the Oak Ridge Spallation Neutron Source

quadrupole, linac, DTL, neutron

329

M.A. Plum
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.
The Oak Ridge Spallation Neutron Source (SNS) accelerator complex routinely delivers 1 MW of beam power to the spallation target. Due to this high beam power, understanding and minimizing the beam loss is an ongoing focus area of the accelerator physics program. In some areas of the accelerator facility the equipment parameters corresponding to the minimum loss are very different from the design parameters. In this presentation we will summarize the SNS beam loss measurements, the methods used to minimize the beam loss, and a compare the design vs. the loss-minimized equipment parameters.

Slides TUO3C04 [4.617 MB]

TUO3C05

Beam Commissioning Plan for CSNS Accelerators

DTL, linac, optics, target

334

S. Wang, S. Fu, H.F. Ouyang, J. Peng
IHEP, Beijing, People's Republic of China

Funding: Supported by National Natural Science Foundation of China (11175193)
The China Spallation Neutron Source (CSNS) is now under construction, and the beam commissioning of ion source will start from the end of 2013, and will last several years for whole accelerator. The commissioning plan for CSNS accelerators will be presented in the presentation, including the commissioning correlated parameters, the goal at different commissioning stages and some key commissioning procedures for each part of accelerators. The detailed schedule for commissioning will be also given.

Slides TUO3C05 [3.574 MB]

TUO3C06

The Result of Beam Commissioning in J-PARC 3-GeV RCS

lattice, collimation, scattering, extraction

339

H. Harada, N. Hayashi, H. Hotchi, M. Kinsho, P.K. Saha, Y. Shobuda, F. Tamura, K. Yamamoto, M. Yamamoto, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y. Irie, T. Koseki, Y. Sato, K. Satou, M.J. Shirakata
KEK, Ibaraki, Japan
S. Kato
Tohoku University, Graduate School of Science, Sendai, Japan

J-PARC 3-GeV RCS has started the beam commissioning since Oct. 2007. In the beam commissioning, the beam tuning for basic parameters and high-intensity operation has been continuously performed. This presentation will describe the results of the beam-loss reduction and minimization for high-intensity operation.

Slides TUO3C06 [7.753 MB]

WEO1A02

LHC Impedance Model: Experience with High Intensity Operation in the LHC

impedance, octupole, brightness, damping

349

B. Salvant, O. Aberle, G. Arduini, R.W. Aßmann, V. Baglin, M.J. Barnes, P. Baudrenghien, A. Bertarelli, C. Bracco, R. Bruce, X. Buffat, F. Carra, F. Caspers, G. Cattenoz, S.D. Claudet, H.A. Day, J. Esteban Müller, M. Garlaschè, L. Gentini, B. Goddard, A. Grudiev, B. Henrist, W. Herr, S. Jakobsen, R.J. Jones, G. Lanza, L. Lari, T. Mastoridis, N. Mounet, E. Métral, A.A. Nosych, J.L. Nougaret, S. Persichelli, T. Pieloni, A.M. Piguiet, S. Redaelli, F. Roncarolo, G. Rumolo, B. Salvachua, M. Sapinski, E.N. Shaposhnikova, L.J. Tavian, M.A. Timmins, J.A. Uythoven, A. Vidal, R. Wasef, D. Wollmann
CERN, Geneva, Switzerland
A.V. Burov
Fermilab, Batavia, USA
S.M. White
BNL, Upton, Long Island, New York, USA

The CERN Large Hadron Collider (LHC) is now in luminosity production mode and has been pushing its performance in the past months by increasing the proton beam brightness, the collision energy and the machine availability. As a consequence, collective effects have started to become more and more visible and have effectively slowed down the performance increase of the machine. Among these collective effects, the interaction of brighter LHC bunches with the longitudinal and transverse impedance of the machine has been observed to generate beam induced heating and transverse instabilities since 2010. This contribution reviews the current LHC impedance model obtained from theory, simulations and bench measurements as well as a selection of measured effects with the LHC beam.

Slides WEO1A02 [7.991 MB]

WEO1A03

Resistive Wall Instability in CSNS/RCS

impedance, simulation, extraction, wakefield

354

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

Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) is a high intensity proton accelerator, with average beam power of 100kW. The collective effects caused by the coupling impedance may be the limit to beam power. The impedance estimation for components on beam line shows that the resistive wall impedance and its instability are more serious than any others. Based on the impedance budget, the instability is theoretically estimated. A simple resistive wall wake field model is used to simulate the bunch oscillation and obtain the growth time. In this simulation model, the continuous resistive wall wake field is concentrated to one position in the ring and the long bunch is sliced into many micro-bunches. By tracking the dynamics of the macro-bunches, the transverse growth time are obtained. The simulation results are also confirmed the restriction to instability by natural chromaticity.
# Supported by National Natural Science Foundation of China (11175193)
*wangs@ihep.ac.cn

Slides WEO1A03 [1.358 MB]

WEO1B01

Low Gamma Transition Optics for the SPS: Simulation and Experimental Results for High Brightness Beams

optics, emittance, electron, extraction

381

H. Bartosik, G. Arduini, T. Argyropoulos, T. Bohl, K. Cornelis, J. Esteban Müller, K.S.B. Li, Y. Papaphilippou, G. Rumolo, B. Salvant, F. Schmidt, E.N. Shaposhnikova, H. Timko
CERN, Geneva, Switzerland
A.Y. Molodozhentsev
KEK, Ibaraki, Japan

The single bunch transverse mode coupling instability (TMCI) at injection is presently one of the main intensity limitation for LHC beams in the SPS. A new optics for the SPS with lower transition energy yields an almost 3-fold increase of the slip factor at injection energy and thus a significantly higher TMCI threshold, as demonstrated both in simulations and in experimental studies. It is observed furthermore that the low gamma transition optics yields better longitudinal stability throughout the entire acceleration cycle. In addition, simulations predict a higher threshold for the electron cloud driven single bunch instability, which might become an important limitation for high intensity LHC beams with the nominal 25 ns bunch spacing. This contribution gives a summary of the experimental and simulation studies, addressing also space charge effects and the achievable brightness with high intensity single bunch beams.

WEO1B03

Circular Modes for Flat Beams in LHC

emittance, optics, space-charge, luminosity

391

A.V. Burov
Fermilab, Batavia, USA

Benefits and problems for operation with flat beams are discussed.

Slides WEO1B03 [0.192 MB]

WEO1B05

PTC-Orbit Studies for the CERN LHC Injectors Upgrade Project

emittance, booster, resonance, space-charge

399

A.Y. Molodozhentsev, E. Forest
KEK, Ibaraki, Japan
G. Arduini, H. Bartosik, E. Benedetto, C. Carli, M. Fitterer, V. Forte, S.S. Gilardoni, M. Martini, N. Mounet, E. Métral, F. Schmidt, R. Wasef
CERN, Geneva, Switzerland

The future improvement of the beam brilliance and intensities required in the frame of the LIU (LHC Injectors Upgrade) project to reach the demands of the HL-LHC (High-Luminosity LHC) project triggered a comprehensive study of the combined effects of the space charge and the machine resonances for the CERN synchrotrons, which are the injector chain for LHC. In frame of this report we will summarize new features of the PTC-ORBIT code which allow the beam dynamics modeling in the LHC injectors taking into account the time variation of the machine parameters during the injection process. The measurements, obtained during recent MD companies, and simulations for the low-energy high-intensity beams, will be discussed.

Slides WEO1B05 [3.063 MB]

WEO1C02

Simulation and Measurement of Half Integer Resonance in Coasting Beams in the ISIS Ring

resonance, simulation, synchrotron, space-charge

434

C.M. Warsop, D.J. Adams, B. Jones, S.J. Payne, B.G. Pine, H. V. Smith, R.E. Williamson
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Operation centres on a high intensity proton synchrotron, accelerating 3·10¹³ ppp from 70-800 MeV, at a repetition rate of 50 Hz. Present studies are looking at key aspects of high intensity behaviour with a view to increasing operational intensity, identifying optimal upgrade routes and understanding loss mechanisms. Of particular interest is the space charge limit imposed by half integer resonance: we present results from coasting beam experiments with the ISIS ring in storage ring mode, along with detailed 3D (ORBIT) simulations to help interpret observations. The methods for experimentally approaching resonance, and the implications on beam behaviour, measurement and interpretation are discussed. In addition, results from simpler 2D simulations and analytical models are used to help interpret expected beam loss and halo evolution. Plans and challenges for the measurement and understanding of this important beam loss mechanism are summarised, as are some closely related areas of high intensity work on ISIS.

Slides WEO1C02 [2.224 MB]

WEO1C03

Longitudinal Beam Loss Studies of the CERN PS-to-SPS Transfer

cavity, emittance, simulation, impedance

439

H. Timko, T. Argyropoulos, T. Bohl, H. Damerau, J. Esteban Müller, S. Hancock, E.N. Shaposhnikova
CERN, Geneva, Switzerland

Bunch-to-bucket transfer between the Proton Synchrotron (PS) and the Super Proton Synchrotron (SPS) is required before beams can enter the Large Hadron Collider. The overall beam loss at this transfer is currently around 5-10 %, and is increased for higher intensities or larger longitudinal emittances. Previous attempts to reduce the losses with additional RF voltage from spare cavities in the PS were unsuccessful. In this paper, we modelled the complete PS flat-top bunch splitting and rotation manipulations, PS-to-SPS transfer, SPS flat bottom and acceleration ramp using end-to-end simulations. Starting from the measured bunch distributions, the simulations provide an accurate insight into the problem and allow direct benchmarking with experiments. As a result, it was understood and confirmed by measurements that shorter bunches do not necessarily lead to better transmission. The particle distribution in longitudinal phase space at PS extraction should be optimised instead. A significant loss reduction of up to 50 % is expected from simulations; experimental studies are on-going to verify these theoretical findings.

Slides WEO1C03 [3.903 MB]

WEO1C04

Acceleration of High-Intensity Protons in the J-PARC Synchrotrons

synchrotron, cavity, extraction, proton

444

M. Yoshii
KEK/JAEA, Ibaraki-Ken, Japan

The J-PARC consisting of the 181 MeV Linac, the 3GeV rapid cycling synchrotron (RCS) and the 50 GeV main synchrotron (MR), is the first high intensity proton synchrotron facility to use the high field gradient magnetic alloy (MA) loaded accelerating cavity. MA is a low-Q material. However, because of the high permeability and the high saturation magnetic flux density, the MA cores are the only materials to realize the required gradient. The MA loaded cavity can be considered as a stable passive load. No tuning control is necessary. 11 RF systems are installed in the RCS, and 8 RF systems in the MR. In addition, the RCS RF systems are operated in a dual harmonic mode to perform the acceleration and the longitudinal manipulation of the high intensity beam in the RCS available space. Beam loading compensation is an important issue. The feed-forward method using the RF beam signals from the wall current monitor has been established. The J-PARC synchrotrons realize stable, reproducible and clean acceleration of high intensity protons. A transition-free lattice and a precise digital timing system asynchronous to the AC-line are the distinctive features, which enable this achievement.

Slides WEO1C04 [3.861 MB]

WEO1C05

Longitudinal Space Charge Phenomena in an Intense Beam in a Ring

space-charge, induction, focusing, electron

447

R.A. Kishek, B.L. Beaudoin, D.W. Feldman, I. Haber, T.W. Koeth, Y. Mo
UMD, College Park, Maryland, USA

Funding: Supported by the US Dept. of Energy, Offices of High Energy Physics and Fusion Energy Sciences, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office.
The University of Maryland Electron Ring (UMER) uses nonrelativistic, high-current electron beams to access the intense space charge dynamics applicable to hadron beams. The UMER beam parameters correspond to space charge incoherent tune shifts, at injection, in the range of 1-5.5 integers. Longitudinal induction focusing is used to counteract the space charge force at the edges of a long rectangular bunch, confining the beam for 100s of turns. We report on two recent findings: (1) The formation and propagation of solitons from large amplitude longitudinal perturbations, observed experimentally and reproduced in WARP* simulations. (2) The evolution of a longitudinal multi-streaming instability when the space-charge force is allowed to lengthen the bunch ends. The expanding bunch ends fill the ring, interpenetrate, and wrap repeatedly, forming multiple streams at any one location, each with its unique velocity. The resulting multi-stream instability is investigated over a wide range of beam currents and initial pulse lengths, and experimental observations are in good agreement with WARP simulations and an analytical theory that successfully predicts the onset of the instability.
* D.P. Grote, A. Friedman, I. Haber, S. Yu, Fus. Eng. & Des. 32-33, 193-200 (1996).

Slides WEO1C05 [5.868 MB]

WEO3C01

Injection and Stripping Foil Studies for a 180 MeV Injection Upgrade at ISIS

simulation, synchrotron, dipole, electron

456

B. Jones, D.J. Adams, M.C. Hughes, S.J.S. Jago, B.G. Pine, H. V. Smith, C.M. Warsop, R.E. Williamson
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The Rutherford Appleton Laboratory (RAL) is home to ISIS, the world's most productive spallation neutron source. ISIS has two neutron producing target stations (TS-1 and TS-2), operated at 40 Hz and 10 Hz respectively with a 50 Hz, 800 MeV proton beam from a rapid cycling synchrotron (RCS), which is fed by a 70 MeV H− drift tube linac. The multi-turn charge-exchange injection process used on ISIS has been the subject of a programme of detailed studies in recent years including benchmarked simulations and experiments. More recently, these studies have been expanded as plans for upgrading ISIS have focussed on replacement of the 70 MeV linac with a new, higher energy injector and a new synchrotron injection straight. Whilst much of these studies have been reported elsewhere, this paper presents a summary of the programme with some further details.

Slides WEO3C01 [4.895 MB]

THO1A03

Dual-harmonic Acceleration Studies at CSNS RCS

acceleration, simulation, bunching, cavity

487

J.F. Chen, J.Y. Tang, X. Zhang
IHEP, Beijing, People's Republic of China

Dual harmonic acceleration is proposed to alleviate the space charge effects in the RCS (Rapid Cycling Synchrotron) at the upgrading stages of the CSNS (China Spallation Neutron Source). Different dual harmonic acceleration schemes have been studied by using a self-made parameter calculation code - RAMADH and the simulation code - ORBIT. Both complete and partial coverage of the dual harmonic RF system along the acceleration have been considered. The injection by combining beam chopping and off-momentum is used in the macro-particle tracking simulations by ORBIT. In addition, a new idea that unlocks the RF frequency and the magnetic field in the injection period is found very useful in obtaining a good longitudinal painting.

Slides THO1A03 [1.343 MB]

THO1A04

High Intensity Longitudinal Dynamics Studies for an ISIS Injection Upgrade

simulation, synchrotron, bunching, space-charge

492

R.E. Williamson, D.J. Adams, C.M. Warsop
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

ISIS is the world's most productive pulsed neutron and muon source, at the Rutherford Appleton Laboratory in the UK. Operation is centred on a loss-limited 50 Hz proton synchrotron which accelerates 3·10¹³ protons per pulse from 70 MeV to 800 MeV, delivering a mean beam power of 0.2 MW. Recent upgrade studies at ISIS have centred on a new 180 MeV linac for injection into the existing ring offering the possibility of beam powers in the 0.5 MW regime through reduction in space charge and optimized injection. A central and critical aspect of such an upgrade is the longitudinal dynamics including beam stability, associated RF parameters, space charge levels and stringent requirements on beam loss. This paper outlines possible longitudinal injection schemes for the injection upgrade meeting key design requirements such as minimising halo, bunching factor and satisfying the Keil-Schnell-Boussard (KSB) stability criterion throughout acceleration. Details of simulation models including calculation of KSB are given together with associated assumptions. Latest results from studies to understand and confirm stability limits on ISIS via simulation and experiment are presented.

Slides THO1A04 [2.641 MB]

THO3A03

Simulations and Measurements in High Intensity LEBT with Space Charge Compensation

emittance, simulation, space-charge, rfq

507

N. Chauvin
CEA/IRFU, Gif-sur-Yvette, France
O. Delferrière, R. Gobin, P.A.P. Nghiem, D. Uriot
CEA/DSM/IRFU, France
R.D. Duperrier
ESS, Lund, Sweden

Over the last years, the interest of the international scientific community for high power accelerators in the megawatt range has been increasing. One of the major challenges is to extract and transport the beam while minimizing the emittance growth in the Low Energy Beam Transport line (LEBT). Consequently, it is crucial to perform precise simulations and cautious design of LEBT. In particular, the beam dynamics calculations have to take into account not only the space charge effects but also the space charge compensation of the beam induced by ionization of the residual gas. The code SOLMAXP has been developed in CEA-Saclay to perform self-consistent calculations taking into account space charge compensation. Extensive beam dynamics simulations have been done with this code to design the IFMIF LEBT (Deuteron beam of 125 mA at 100 keV, cw). The commissioning of the IFMIF injector started a few months ago and emmittance measurements of H⁺ and D⁺ beams have been done. The first experimental results will be presented and compared to simulation.

Slides THO3A03 [3.165 MB]

THO3A04

Beam Halo Definitions and its Consequences

emittance, linac, beam-losses, space-charge

511

P.A.P. Nghiem, N. Chauvin, D. Uriot
CEA/DSM/IRFU, France
W. Simeoni
CEA/IRFU, Gif-sur-Yvette, France

In high-intensity accelerators, much attention is paid to the beam halo: formation, growth interaction with the beam core, etc. Indeed, beam losses, a critical issue for those high-power accelerators, directly depend on the beam halo behaviour. But in the presence of very strong space-charge forces, the beam distribution takes very different shapes along the accelerator, often very far from any regular distributions, with very varied halo extensions. The difficulty is then to find a general definition of the halo capable of describing any distribution type. This paper proposes a definition of the beam halo, studies its consequences and compares it to the most usual ones.

Slides THO3A04 [9.030 MB]

THO1C02

Beam Loss Control in the ISIS Accelerator Facility

synchrotron, controls, proton, acceleration

560

D.J. Adams, B. Jones, A.H. Kershaw, S.J. Payne, B.G. Pine, H. V. Smith, C.M. Warsop, R.E. Williamson, M. Wright
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The ISIS spallation neutron and muon source has been in operation since 1984. The accelerator complex consists of an H⁻ ion source, RFQ, 70 MeV linac, 800 MeV proton synchrotron and associated beam lines. The facility currently delivers ~2.8·10¹³ protons per pulse at 50 Hz, splitting the pulses 40/10 between two neutron target stations. High intensity performance and operation are dominated by the need to control beam loss, which is key to sustainable machine operation and hands on maintenance. Beam loss measurement systems on ISIS are described, along with typical operational levels. The dominant beam loss in the facility occurs in the synchrotron due to high intensity effects during the H⁻ injection and longitudinal trapping processes. These losses are localised in a single superperiod using a beam collector system. Emittance growth during acceleration also drives extraction and beam transport loss at 800 MeV. Measurements, simulation and correction systems for these processes are discussed, as are the implications for further intensity upgrades.

Slides THO1C02 [4.759 MB]

THO1C04

Performances and Future Plans of the LHC RF

cavity, klystron, emittance, impedance

565

P. Baudrenghien, T. Mastoridis
CERN, Geneva, Switzerland

The ramp-up of the LHC operation has been exceptionally fast: from the first acceleration of a single bunch at nominal intensity (1.1· E11 p) to 3.5 TeV/c on May 2010, to the accumulation of 11 fb-1 integrated luminosity two years later (June 2012). On the RF side this was made possible by a few key design choices and several developments, that allow reliable LHC operation with 0.35 A DC beam at 4 TeV/c (1380 bunches at 50 ns spacing, 1.5·10¹¹ p per bunch). This paper reviews the RF design and presents its performance. Plans are also outlined that would allow operation with 25 ns bunch spacing (doubling the beam current) and even increased bunch intensity with the target of above 1A DC current per beam, without big modification to the existing RF power system.

Slides THO1C04 [9.945 MB]

THO1C06

Recent Commissioning of High-intensity Proton Beams in J-PARC Main Ring

beam-losses, proton, kicker, acceleration

575

Y. Sato, K. Hara, Y. Hashimoto, Y. Hori, S. Igarashi, K. Ishii, N. Kamikubota, T. Koseki, Y. Kurimoto, K. Niki, K. Ohmi, C. Ohmori, M. Okada, M. Shimamoto, M.J. Shirakata, T. Sugimoto, J. Takano, M. Tejima, T. Toyama, M. Uota, S. Yamada, N. Yamamoto, M. Yoshii
KEK, Ibaraki, Japan
S. Hatakeyama, H. Hotchi, F. Tamura
JAEA/J-PARC, Tokai-mura, Japan
S. Nakamura, K. Satou
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

J-PARC main ring (MR) provides high power proton beams of 200 kW to the neutrino experiment. Beam losses were well managed within capacity of collimation system. Since this beam power was achieved by shortening the repetition rate, following tunings had been applied in order to reduce the beam losses, such as improvement of tune flatness, chromaticity correction, upgrades of injection kickers, dynamic bunch-by-bunch feed-back to suppress transverse oscillation, beam loading compensation using feed-forward technique, and balancing the collimators of MR and the injection beam transport line. The dynamic bunch-by-bunch feed-back was effective to reduce the beam losses to one-tenth during injection and beginning of acceleration. With the beam loading compensation, impedance seen by the beam was significantly reduced, longitudinal oscillations were damped, and the beam power was increased over 5% without increasing the beam losses. Monitors were upgraded to find time structure and location of the beam losses, even in first several turns after each injection. In this presentation these commissioning procedures and beam dynamics simulations are shown, and our upgrade plan is discussed.

Slides THO1C06 [2.193 MB]

FRO1A03

Accelerator System Design, Injection, Extraction and Beam-Material Interaction: Working Group C Summary Report

collimation, ion, proton, simulation

615

N.V. Mokhov
Fermilab, Batavia, USA
D. Li
LBNL, Berkeley, California, USA

Working Group C summary:The performance of high beam power accelerators is strongly dependent on appropriate injection, acceleration and extraction system designs as well as on the way interactions of the beam with machine components are handled. The experience of the previous ICFA High-Brightness Beam workshops has proven that it is quite beneficial to combine analyses and discussion of these issues in one group, WG-C at this Workshop. A broad range of topics was presented and discussed in twenty talks at four WG-C sessions as well as at two joint WGA/C and WG-B/C sessions. Highlights from these talks, outstanding issues along with plans and proposals for future work are briefly described.

Slides FRO1A03 [4.907 MB]

FRO1B01

Summary of the Working Group on Commissioning and Operation

beam-losses, linac, proton, simulation

620

R. Schmidt
CERN, Geneva, Switzerland
M.A. Plum
ORNL, Oak Ridge, Tennessee, USA
Y. Sato
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

The Working Group D summary report focussed on answering the following issues:

observation of beam losses (e.g. time structure, other parameters,…),
reducing beam losses with operational parameters away from the design set points,
reducing beam losses (or concentrating beam losses at a few locations) using collimators,
minimizing beam losses due to beam transfer from one accelerator to the following accelerator - what parameters are important?

The issue of reducing beam losses with operational parameters away from the design set points is especially valuable as it is rarely discussed.

Slides FRO1B01 [0.426 MB]