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shielding

 
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MOPCH186 First Cool Down of the Juelich Accelerator Module Based on Superconducting Half-Wave Resonators vacuum, radiation, instrumentation, COSY 496
 
  • F.M. Esser, B. Laatsch, H.S. Singer, R. Stassen
    FZJ, Jülich
  • R. Eichhorn
    TU Darmstadt, Darmstadt
  In the context of upgrading the existing proton and deuteron accelerator facility COSY at the Forschungszentrum Juelich, an accelerator module based on superconducting half wave resonators is prototyped. Due to beam dynamics, the requirements of cavity operation and a top-loading design for mounting, the cryostat had to be designed very compact and with a separate vacuum system for beam and insulation vacuum. These restricted requirements lead to very short cold-warm transitions in beam port region and to an unconventional design regarding to the shape of the cryostat vessel. This paper will review the design constraints, gives an overview of the ancillary parts of the module (cavities, tuner, etc.) and will present the results of the first cool-down experiments. Furthermore the future work will be presented.  
 
MOPLS002 The Study of the Machine-induced Background and its Applications at the LHC background, LHC, insertion, CERN 529
 
  • V. Talanov, I. Azhgirey, I. Baishev
    IHEP Protvino, Protvino, Moscow Region
  • D. Macina, K.M. Potter, E. Tsesmelis
    CERN, Geneva
  We present the recent advances in the analysis of the machine-induced background generation and formation at the LHC. Different aspects of the study of the machine background problem at the LHC are reviewed, including the background production at the different stages of the machine operation, the role and influence on the background from the collimators in the experimental insertions and the background shielding. The potential use of the machine background for the purposes of detector testing and alignment is also discussed.  
 
MOPLS003 Tertiary Halo and Tertiary Background in the Low Luminosity Experimental Insertion IR8 of the LHC background, LHC, insertion, simulation 532
 
  • V. Talanov
    IHEP Protvino, Protvino, Moscow Region
  • R.W. Assmann, D. Macina, K.M. Potter, S. Redaelli, G. Robert-Demolaize, E. Tsesmelis
    CERN, Geneva
  In our report we present the results for numerical simulation of tertiary halo and tertiary background in the LHC. We study the case of the proton losses in the betatron cleaning insertion IR7 with the subsequent tertiary halo generation in the downstream experimental insertion IR8. We analyze the formation of tertiary background in the experimental area of the IR8 and evaluate the performance of the machine-detector interface shielding with respect to this source of the background. The results obtained are compared with the previous estimates of the machine-induced background in the low luminosity insertions of the LHC, and the balance between different sources of the background is discussed.  
 
TUOCFI01 Radiation Measurements vs. Predictions for SNS Linac Commissioning linac, radiation, CCL, SNS 977
 
  • I.I. Popova, F. X. Gallmeier, P. L. Gonzalez, D. C. Gregory
    ORNL, Oak Ridge, Tennessee
  Detailed predictions for radiation fields, induced inside and outside of the accelerator tunnel, were performed for each of the SNS accelerator commissioning stages, from the ion source through the entire LINAC. Analyses were performed for normal commissioning parameters, for worst possible beam accidents, and for beam fault studies, using the Monte Carlo code MCNPX. Proper temporary shielding was developed and installed in local areas near beam termination points (beam stops) and some critical locations, such as penetrations, in order to minimize dose rates in general occupied areas. Areas that are not full-time occupied and have dose rates above a specified limit during beam accident and fault studies were properly restricted. Radiation monitoring was performed using real time radiation measurement devices and TLDs to measure absorbed dose and dose equivalent rates. The measured radiation fields were analyzed and compared with transport simulations. TLD readings vs. calculations are in a good agreement, generally within a factor of two difference. A large inconsistency among instrument readings is observed, and an effort is underway to understand the variations.  
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TUPCH031 A New SQUID-based Measurement Tool for Characterization of Superconducting RF Cavities cryogenics, pick-up, electron, TESLA 1070
 
  • K. Knaack, K. Wittenburg
    DESY, Hamburg
  • R. Neubert, S. Nietzsche, W. Vodel
    FSU Jena, Jena
  • A. Peters
    GSI, Darmstadt
  In this contribution a LTS-SQUID based measurement tool for characterization of superconducting RF cavities for the upcoming X-FEL project at DESY will be presented. The device makes use of the Cryogenic Current Comparator (CCC) principle and measures the so-called dark current, generated e.g. by superconducting cavities at high voltage gradients. To achieve the maximum possible energy the gradients should be pushed near to the physical limit of 50 MV/m. The measurement of the undesired field emission of electrons (the so-called dark current) in correlation with the gradient will give a proper value to characterize the performance of the RF cavities. The CCC mainly consists of a high performance LTS-DC SQUID system which is able to measure extremely low magnetic fields, e.g. caused by the extracted dark current of the RF cavities. Therefore, a special designed toroidal niobium pick-up coil for the passing electron beam is superconducting connected across the input coil of the SQUID. The noise limited sensitivity of the CCC as well as new experimental results with the whole measurement device assembled in a special wide-necked LHe cryostat will be presented.  
 
TUPCH059 Dual-mode Beam Current Monitor pick-up, impedance, feedback, injection 1145
 
  • S. Ninomiya, T. Adachi, S. Fukumoto
    KEK, Ibaraki
  • S.H. Hatori, T. Kurita
    WERC, Tsuruga , Fukui
  A new type HEREWARD-transformer is developed. The original scheme connects pickup coil to the low impedance input of the amplifier to increase the time constant of the transformer. The new scheme employs negative impedance circuit which realizes perfect cancellation of the coil resistance. Therefore DC component of the beam current can be observed. Since number of winding of the pick up coil is only 100-turns, therefore by using the original scheme with a fast operational amplifier, the transformer can be operated at fast CT mode. Thus the dual mode operation can be realized by single core; the first mode is the slow beam intensity monitor, and the second is a fast response transformer. This operation mode realizes an accurate observation of the beam injection process. In order to make installation easy, the core is divided into two pieces. The magnetic shield from bending field is also installed. This monitor is developed at KEK, and installed into the accelerator at the WAKASA WAN Energy Research Center.  
 
TUPCH194 Analogue and Digital Low Level RF for the ALBA Synchrotron controls, resonance, synchrotron, linac 1468
 
  • F. Pérez, H. Hassanzadegan, A. Salom
    ALBA, Bellaterra
  ALBA is a 3 GeV, 400 mA, 3rd generation Synchrotron Light Source that is in the construction phase in Cerdanyola, Spain. The RF System will have to provide 3.6 MV of accelerating voltage and restore up to 540 kW of power to the electron beam. Two LLRF prototypes are being developed in parallel, both following the IQ modulation/demodulation technique. One is fully based on analogue technologies; the other is based on digital FPGA processing. The advantages of the IQ technique will be summarised and the control loop logic described. The hardware implementation in analogue as well as in digital format will be presented and first test results shown. The implementation of the same logic with both technologies will give us a perfect bench to compare, and use the better of them, for the final LLRF of the ALBA synchrotron.  
 
TUPLS113 Designs of Septum Magnet at 3 GeV RCS in J-PARC septum, vacuum, injection, extraction 1768
 
  • M. Yoshimoto, Y. Irie, J. Kamiya, M. Kinsho, T. Takayanagi, O. Takeda, M. Watanabe
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • H. Fujimori, S. Igarashi, H. Nakayama
    KEK, Ibaraki
  3 GeV RCS (Rapid Cycling Synchrotron) at J-PARC (Japan Proton Accelerator Research Complex) consists in many kinds of septum magnets. There are two septum magnets to inject the beam into the ring, three septum magnets to extract the beam for the users, and two septum magnets to dump the beam which can not be exchanged its charge at the first foil. In order to reduce the magnetic leakage field from the septum magnets at the beam orbit in the ring, the silicon steel sheets are set at the outside of the septum magnets for the magnetic shields. However sufficient spaces to set the thick magnetic shields are not securable at the divergent duct areas. Therefore the vacuum chambers are made by the magnetic stainless steel and the leakage fields in the chambers can be reduced. As results of the 3D field calculations by TOSCA, the magnetic leakage field can be suppressed to a few Gauss or less.  
 
TUPLS116 Extraction System Design for the CSNS/RCS kicker, extraction, septum, lattice 1777
 
  • J. Tang, Y. Chen, Y.L. Chi, Y.L. Jiang, W. Kang, J.B. Pang, Q. Qin, S. Wang, W. Wang
    IHEP Beijing, Beijing
  • J. Wei
    BNL, Upton, Long Island, New York
  The CSNS extraction system takes use one of the four dispersion-free straight sections. Five vertical kickers and one Lambertson septum magnet are used for the one-turn extraction. The rise time of less 250 ns and the total kicking angle of 20 mrad are required for the kickers that are grouped into two tanks. The design for the kicker magnets and the PFN is also given. To reduce the low beam loss in the extraction channels due to large halo emittance, large apertures are used for both the kickers and septum. Stray magnetic field inside and at the two ends of the circulating path of the Lambertson magnet and its effect to the beam has been studied.  
 
TUPLS132 Estimation of the Energy Deposited on the CNGS Magnetic Horn and Reflector target, focusing, secondary-beams, simulation 1813
 
  • L. Sarchiapone, A. Ferrari, M. Lorenzo Sentis
    CERN, Geneva
  In the CNGS installation two magnetic lenses, namely the horn and the reflector, focus the secondary beam generated in the target station. The gap between the horn and reflector is chosen to optimize a wide-band high-energy muon-neutrino beam. These two focusing elements are two coaxial lenses similar in length but different in shape: the outer conductor has a cylindrical shape whereas the inner conductor consists of a sequence of conical shapes to optimize the focusing capacity. The evaluation of the heat load on the support structures is crucial since modifications in the elements around the horn and reflector are under way and the support structures can be adapted to the heat load found. Furthermore, the heat load in the whole horn area has been evaluated to optimize the cooling-ventilation system. The FLUKA geometry input of the horn and reflector electrical connections has been notably improved in order to accommodate the detailed striplines design to the thermal expansion. The energy deposited on the horn and reflector as well as on their adjacent elements has been estimated using the FLUKA Monte Carlo package and results are presented in this document.  
 
WEPCH005 Advances in Beam Orbit Stability at the LNLS Electron Storage Ring storage-ring, synchrotron, vacuum, radiation 1924
 
  • L. Liu, R.H.A. Farias, M.J. Ferreira, S.R. Marques, F. Rodrigues, P.F. Tavares, R.P.C.C. Tenca
    LNLS, Campinas
  We describe recent efforts made at the Brazilian Synchrotron Light Source (LNLS) to improve beam orbit stability. The main driving force is the high positional stability required by some specific experiments and particularly by a high resolution undulator beamline which is being built at LNLS. Recent steps taken to improve orbit stability include the development of x-ray BPMs to measure the vertical position of the x-ray beam, analysis of RF BPM movement due to thermal load induced by synchrotron radiation after injection, new algorithms to deal with BPM electronics or control board false readings and revision and modification of their installations. In addition a weighted least squares method was developed to account for global correction while simultaneously privileging some local source point position. These upgrades are part of an ongoing work to improve beam orbit stability at LNLS.  
 
WEPCH144 CSR Effects in a Bunch Compressor: Influence of the Transverse Force and Shielding LEFT, CSR, simulation, radiation 2260
 
  • G. Bassi, J.A. Ellison, K.A. Heinemann
    UNM, Albuquerque, New Mexico
  We study the influence of CSR on particle bunches traveling on arbitrary planar orbits between parallel conducting plates with a fixed "vertical" charge distribution. Our goal is a numerical solution of the 2 degree-of-freedom Vlasov-Maxwell equations. This provides simulations with lower numerical noise than the macroparticle method and allows the study of emittance degradation and microbunching. As reported*, we calculate the fields excited by the bunch in the lab frame using a new formula that leads to a simplification. The Vlasov equation is integrated in the beam frame interaction picture using the method of local characteristics. The transformation between traditional beam frame and lab frame coordinates is carefully treated. Here we report on our implementation of the algorithm in the context of a chicane bunch compressor**, where the strong correlation between phase space variables requires an adaptive grid. In particular, we present a complete analysis (moments + reduced densities) of the bunch evolution under the fields produced by the unperturbed bunch density. Finally, our progress on the fully self-consistent case is discussed.

* Vlasov treatment of coherent synchrotron radiation from arbitrary planar orbits, Nucl. Instr. Meth. Phys. Res. A, in press.** ICFA Beam Dynamics Mini-Workshop on CSR, Berlin-Zeuthen, 2002. See http://www.desy.de/csr.

 
 
WEPCH194 Complex for X-ray Inspection of Large Containers radiation, electron, target, controls 2388
 
  • V.M. Pirozhenko, V.M. Belugin, V.V. Elyan, A.V. Mischenko, N.E. Rozanov, B.S. Sychev, V.V. Vetrov
    MRTI RAS, Moscow
  • Yu.Ya. Kokorovets, V.D. Ryzhikov, N.A. Shumeiko, S.Ya. Yatsenko
    Communar, Kharkov
  • A.N. Korolev, K.G. Simonov
    ISTOK, Moscow Region
  The X-ray inspection complex is intended for non-intrusive inspection of large containers in the seaport. The complex has been developed, manufactured, and tested. To provide two projections of irradiated container and ensure reliable inspection, the complex includes two sets each containing self-shielded X-ray source and L-shaped detector array. The X-ray source includes electron linear accelerator with 7.3 MeV energy, conversion target, local radiation shielding, and alignment means. The accelerator uses standing wave bi-periodic structure fed by magnetron generator with 2.8 GHz frequency. It provides intensive electron beam without application of external magnetic field for the beam focusing. This feature makes it possible to use massive local radiation shielding made from iron. The radiation shielding provides large attenuation of scattered X-rays and ensures the radiation safety for personnel as well as high sensitivity of detecting system and good penetrability of the complex.  
 
WEPLS089 Feasibility Study of a Permanent Magnet Made from High-Tc Bulk Superconductor dipole, LEFT, permanent-magnet, superconductivity 2580
 
  • M. Masuzawa, K. Egawa, K. Tsuchiya
    KEK, Ibaraki
  A field trapping experiment using a magnetic field up to ~1.5 T was performed using high-Tc bulk superconductors. Applications of bulk high-Tc superconductors have been investigated in various fields. High-Tc superconductors are attractive since they can trap higher magnetic fields than conventional permanent magnets. The trapping experiment was done with a field of above 1 T, which can be easily produced by conventional magnets. However, achieving the desired field distribution and understanding the characteristics of the trapped field and its decay process would open up the possibility of high-Tc bulk superconductor applications in the design of magnets for particle accelerators The distribution of the trapped field and its decay process was monitored by an array of Hall sensors for different shapes of the bulk superconductors. The observations are reported on in this paper.  
 
THPLS018 FLUKA Calculations of Neutron Spectra at BESSY target, electron, vacuum, radiation 3311
 
  • K. Ott
    BESSY GmbH, Berlin
  The synchrotron light source BESSY consists of a 50 MeV microtron, a full energy synchrotron and a 1.9 GeV storage ring. The electron losses during injection causes electromagnetic cascades within the stainless steel of the vacuum system and the aluminum chambers of the undulators. The cascade-produced neutrons result from giant resonances, quasi-deuteron fissions and photo-pion productions. The cross sections of the evaporation reactions of neutrons are an order of magnitude higher than the cross sections of the latter two reaction channels. The energy distribution of the giant resonance neutrons has a maximum at about 1 MeV in comparison with 100 - 200 MeV of the high energy neutrons. At electron accelerators outside the shielding wall, half of the neutron dose is often determined by the more penetrating high energy part of the neutron fluence. We used the particle interaction and transport code FLUKA for the calculations of the energy distribution of both the fluence and the dose inside and outside the shielding wall for different realistic scenarios. From the integrated spectra we get the calibration factor to determine the total neutron dose from the measurements directly.