04 Hadron Accelerators

T19 Collimation and Targetry

Paper Title Page
THPEC041 Uniform Beam Distribution by Nonlinear Focusing Forces 4149
 
  • Y. Yuri, I. Ishibori, T. Ishizaka, S. Okumura, T. Yuyama
    JAEA/TARRI, Gunma-ken
 
 

To achieve ultra-low-fluence large-area uniform irradiation of ion beams for advanced applications in the field of materials sciences and biotechnology, a uniform-beam irradiation system has been developed using multipole magnets at the Japan Atomic Energy Agency (JAEA) cyclotron facility. The system consists of a beam attenuator for the wide-range intensity control, an electrostatic beam chopper for the control of irradiation time, scattering foils for conditioning of the initial beam distribution, octupole magnets for transverse tail-folding, sextupole magnets for the correction of the beam misalignment, and the diagnostic station of the two-dimensional beam profile. In this paper, recent experimental results are described, especially on the formation of a beam with a uniform transverse distribution by the combination of the sextupole and octupole magnets.

 
THPEC042 Thermal and Structual Stability of Medium Energy Target Carrier Assembly for NOvA at Fermilab 4152
 
  • M.W. McGee, C.R. Ader, K. Anderson, J. Hylen, M.A. Martens
    Fermilab, Batavia
 
 

The NOνA project will upgrade the existing Neutrino at Main Injector (NuMI) project beamline at Fermilab to accommodate beam power of 700 kW. The Medium Energy (ME) graphite target assembly is provided through an accord with the State Research Center of Russia Institute for High Energy Physics (IHEP) at Protvino, Russia. The effects of proton beam energy deposition within beamline components are considered as thermal stability of the target carrier assembly and alignment budget are critical operational issues. Results of finite element thermal and structural analysis involving the target carrier assembly is provided with detail regarding the target's beryllium windows.


mcgee@fnal.gov

 
THPEC078 Development of a Cryocatcher Prototype for SIS100 4238
 
  • L.H.J. Bozyk
    TU Darmstadt, Darmstadt
  • D.H.H. Hoffmann, H. Kollmus, P.J. Spiller
    GSI, Darmstadt
 
 

The central accelerator SIS100 of the FAIR-facility will provide high intensity, intermediate charge state heavy ion beams. In order to assure a reliable operation with the intermediate charge states, a special synchrotron design, including ion catcher system had to be developed. Intermediate charge state heavy ions suffer from high cross sections for ionization. Due to the dedicated synchrotron layout, ions which have been further stripped by collisions with residual gas atoms are not lost uncontrolled onto the beam pipe but are caught by the ion catcher system in the cryogenic arcs. The construction and test of a cryo-catcher prototype at GSI is a workpackage of the EU-FP7 project COLMAT. A prototype catcher including cryostat will be set-up at GSI to perform measurements with heavy ion beams of the heavy ion synchrotron SIS18.

 
THPEC079 Collimation and Material Science Studies (COLMAT) at GSI 4241
 
  • J. Stadlmann, H. Kollmus, E. Mustafin, I.J. Petzenhauser, P.J. Spiller, I. Strašík, N.A. Tahir, C. Trautmann
    GSI, Darmstadt
  • L.H.J. Bozyk, M. Krause
    TU Darmstadt, Darmstadt
  • M. Tomut
    INFIM, Bucharest
 
 

Within the frame of the EuCARD program, the GSI Darmstadt is performing accelerator R&D in workpackage 8: ColMat. The effort is focused on materials important for building the FAIR accelerator facility at GSI and the LHC upgrade at CERN. Accelerator components and especially protection devices have to be operated in high dose environments. The radiation hazard occurs either by the primary proton and ion beams or the secondary radiation. Detailed numerical simulations have been carried out to study the damage caused to solid targets by the full impact of the LHC beam as well as the SPS beam. Tungsten, copper and graphite targets have been studied. Experimental an theoretical studies on radiation damage on materials used for the LHC upgrade and the FAIR accelerators are performed at the present GSI experimental facilities. Technical decisions based on these results will have an impact on the FAIR component specifications. A cryogenic ion-catcher prototype will be constructed and tested. The ion-catcher is essential for reaching highest heavy ion beam intensities in SIS100. The prototype will be set-up at GSI to perform measurements with heavy ion beams of synchrotron SIS18.

 
THPEC080 Fabrication of Silicon Strip Crystals for UA9 Experiment 4243
 
  • A. Mazzolari, E. Bagli, V. Guidi
    INFN-Ferrara, Ferrara
  • S. Baricordi, P. Dalpiaz, D. Vincenzi
    UNIFE, Ferrara
  • A. Carnera, D. De Salvador
    Univ. degli Studi di Padova, Padova
  • G. Della Mea
    INFN/LNL, Legnaro (PD)
  • A.M. Taratin
    JINR, Dubna, Moscow Region
 
 

Channeling in bent crystals is a technique with high potential to steer charged-particle beams for several applications in accelerators physics. Revisited methods of silicon micromachining techniques allowed one to realize a new generation of crystals. Characterizations using x-ray diffraction, atomic force microscopy, high resolution transmission electron microscopy and ion beam analysis techniques, showed high quality of the crystals. A specifically designed holder allowed to mechanically bend a crystal at given curvature and remove unwanted torsion. Characterization of such crystals with 400 GeV at CERN H8 external line highlighted 85% single-pass efficiency. A selected crystal has been installed inside the SPS ring in the environment of the CERN experiment UA9 and successfully employed for collimation of the circulating beam.


On behalf of UA9 collaboration

 
THPEC081 Upgrade of Radiation Shield for BT Collimators 4246
 
  • M.J. Shirakata, T. Oogoe
    KEK, Ibaraki
 
 

The beam transport line between 3 GeV Rapid Cycling Synchrotron and Main Ring has a beam collimator system in order to improve the quality of injected beam in the main ring. The beam power deposited into the collimators is required to be increased for high intensity beam operation. The tolerance of existing radiation shield becomes insufficient, even though there is no heat problem. The gate-type shield system has been preparing in order to satisfy both the radiation shielding and feasibility of maintenance. The development of movable gate-type shield system is reported here, which fully covers more than 20 meters long collimator section.

 
THPEC083 Dump and Current Measurement of Unstripped H- Ions at the Injection from the CERN LINAC4 into the PS Booster 4249
 
  • R. Chamizo, J. Borburgh, B. Goddard, A. Mereghetti, R. Versaci, W.J.M. Weterings
    CERN, Geneva
 
 

Linac4 is the new H- linear accelerator under construction at CERN aiming to double the brightness of the beam injected to the CERN PS Booster (PSB) for delivering proton beams to experiments or further CERN accelerators, down to the LHC. The injection system in the PSB is based on the H- charge exchange where the 160 MeV H- beam is converted into an H+ beam by stripping the electrons with a carbon foil. A beam dump located inside a pulsed magnet for the injection bump will intercept the unstripped ions (H0 and H-) and measure the collected charge to detect the relative efficiency and degradation of the stripping foil. The challenge of the dump design is to meet the requirements of a beam dump providing a current measurement and at the same time minimizing the perturbation of the magnetic field of the surrounding pulsed magnet. This paper describes all phases of the dump design and the main issues related to its integration in the line.

 
THPEC084 Crystal Collimation Efficiency Measured with the Medipix Detector in SPS UA9 Experiment 4252
 
  • E. Laface, W. Scandale, L. Tlustos
    CERN, Geneva
  • V. Ippolito
    INFN-Roma, Roma
 
 

The UA9 experiment was performed in 6 MDs from May to November 2009 with the goal of studying the collimation properties of a crystal in the framework of a future exploitation in the LHC collimation system. An important parameter evaluated for the characterization of the crystal collimation is the efficiency of halo extraction when the crystal is in channeling mode. In this paper it is explained how this efficiency can be measured using a pixel detector, the Medipix, installed in the Roman Pot of UA9. The number of extracted particles counted by the Medipix is compared with the total number of circulating particles measured by the Beam Current Transformers (BCTs): from this comparison the efficiency of the system composed by the crystal, used in channeling mode, and a tungsten absorber is proved to be greater than 85%.

 
THPEC087 Measurement of Nuclear Reaction Rates in Crystals using the CERN-SPS North Area Test Beams 4258
 
  • W. Scandale, R. Losito
    CERN, Geneva
  • A.M. Taratin
    JINR, Dubna, Moscow Region
 
 

A number of tests were performed by the UA9 Collaboration* in the North area of the SPS in view of investigating crystal-particles interactions for future application in hadron colliders. The rate of nuclear reactions was measured with 400 GeV proton beams directed into a silicon bent crystal. In this way the background induced by the crystal itself either in amorphous or in channeling orientation was revealed. The results provide fundamental information to put in perspective the use of silicon crystals to assist halo collimation in hadron colliders, whilst minimizing the induced loss. Crystals made of Germanium were also investigated in view of the expected increase of the collimation efficiency respect to silicon. Finally, crystals were tested in axial orientation and with incoming particles of negative charge. The collected results are presented in details.


* http://greybook.cern.ch/programmes/experiments/UA9.html

 
THPEC088 Simulation based optimization of a collimator system at the PSI proton accelerator facilities 4260
 
  • Y. Lee, V. Gandel, D.C. Kiselev, D. Reggiani, M. Seidel, S. Teichmann
    PSI, Villigen
 
 

A simulation based optimization of a collimator system at the 590 MeV PSI proton accelerator is presented, for the ongoing beam power upgrade from the current 1.2 MW [2 mA] towards 1.8 MW [3 mA]. The collimators are located downstream of the 4 cm thick graphite meson production target. These are designed to shape the optimal beam profile for low-loss beam transport to the neutron spallation source SINQ. The optimized collimators are predicted to withstand the beam intensity up to 3 mA, without sacrificing intended functionalities. The collimator system is under the heavy thermal load generated by a proton beam power deposition approximately of 240 kW at 3 mA, and it needs an active water cooling system. Advanced multiphysics simulations are performed for a set of geometric and material parameters, for the thermomechanical optimization of the collimator system. In particular, a FORTRAN subroutine is integrated into CFD-ACE+, for calculating local beam stopping power in the collimator system. Selected results are then compared with those of full MCNPX simulations.

 
THPEC089 Overview of Solid Target Studies for a Neutrino Factory 4263
 
  • T.R. Edgecock
    STFC/RAL, Chilton, Didcot, Oxon
  • J.J. Back
    University of Warwick, Coventry
  • J.R.J. Bennett
    STFC/RAL/ISIS, Chilton, Didcot, Oxon
  • C.N. Booth, G.P. Skoro
    Sheffield University, Sheffield
  • S.J. Brooks
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
 
 

The UK programme of high power target developments for a Neutrino Factory is centred on the study of high-Z materials (tungsten, tantalum). A description of lifetime shock tests on candidate materials is given as part of the research into a solid target solution. A fast high current pulse is applied to a thin wire of the sample material and the lifetime measured from the number of pulses before failure. These measurements are made at temperatures up to ~2000 K. The stress on the wire is calculated using the LS-DYNA code and compared to the stress expected in the real Neutrino Factory target. It has been found that tantalum is too weak to sustain prolonged stress at these temperatures but a tungsten wire has reached over 26 million pulses (equivalent to more than ten years of operation at the Neutrino Factory). An account is given of the optimisation of secondary pion production from the target and the issues related to mounting the target in the muon capture solenoid and target station are discussed.

 
THPEC091 Tungsten Behavior at High Temperature and High Stress 4269
 
  • G.P. Skoro, C.N. Booth
    Sheffield University, Sheffield
  • J.J. Back
    University of Warwick, Coventry
  • J.R.J. Bennett, S.A. Gray, A.J. McFarland
    STFC/RAL/ISIS, Chilton, Didcot, Oxon
  • T.R. Edgecock
    STFC/RAL, Chilton, Didcot, Oxon
 
 

Recently reported results on the tungsten lifetime/fatigue tests under conditions expected in the Neutrino Factory target have strengthened the case of solid target option for a Neutrino Factory. This paper gives description of the detailed measurements of the tungsten properties at high temperature and high stress. We have performed extensive set of measurements of the surface displacement and velocity of the tungsten wires that were stressed by passing a fast, high current pulse through a thin sample. Radial and longitudinal oscillations of the wire were measured by a Laser Doppler Vibrometer. The wire was operated at temperatures of 300-2500 K by adjusting the pulse repetition rate. In doing so we have tried to simulate the conditions (high stress and temperature) expected at the Neutrino Factory. Most important result of this study is an experimental confirmation that strength of tungsten remains high at high temperature and high stress. The experimental results have been found to agree very well with LS-DYNA modelling results.

 
THPEC092 A Pion Production and Capture System for a 4MW Target Station 4272
 
  • X.P. Ding, D.B. Cline
    UCLA, Los Angeles, California
  • J.S. Berg, H.G. Kirk
    BNL, Upton, Long Island, New York
 
 

A study of a pion production and capture system for a 4MW target station for a neutrino factory or muon collider is presented. Using the MARS code, we simulate the pion production produced by the interaction of a free liquid mercury jet with an intense proton beam. We study the variation of meson production with the direction of the proton beam relative to the target. We also examine the influence on the meson production by the focusing of the proton beam. The energy deposition in the capture system is determined and the shielding required in order to avoid radiation damage is discussed.