ANL, Argonne
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
Construction of the DOE Californium Rare Ion Breeder Upgrade (CARIBU) for the ATLAS facility is expected to be completed by the end of 2008 and commissioning should be well along by the time of the conference. The facility will use fission fragments from a 1 Ci 252Cf source, thermalized and collected into a low-energy particle beam by a helium gas catcher, mass analyzed by an isobar separator, and charge breed to higher charge states for acceleration in ATLAS. In addition, unaccelerated beams will be available for trap and laser probe studies. Expected yields of accelerated beams are up to ~5x105 (107 to traps) far-from-stability ions per second on target. The facility design and first results of beam acceleration using a weaker 80 mCi source will be presented in this paper and plans for installation of the 1 Ci source will be discussed.
CERN, Geneva
In the CERN Large Hadron Collider, about 6 km of the UHV beam pipe are at ambient temperature and serve as experimental or utility insertions. The vacuum of these sectors rely on TiZrV non-evaporable getter (NEG) coating to achieve very low pressure. In the case of venting to atmosphere, the use of NEG coatings implies the bake-out of the vacuum sector to recover the low pressure and reactivate the NEG coatings. A new method to vent a vacuum sector to atmosphere allows performing short interventions without losing completely the performance of the already activated NEG coating. The principle is to over-pressurize the vacuum sector with neon gas which is not pumped by the NEG coatings, remove the faulty component and then pump down the sector again. The injection of such a gas in the vacuum sector aims at preserving the saturation of the NEG coatings during the exchange of the component. A detailed description of this new venting system will be presented and discussed. Preliminary results obtained from a laboratory venting system and its evaluation in the LHC tunnel to replace existing components will be presented.
CERN, Geneva
The LHC collider has recently started-up at CERN. It will provide colliding beams to four experiments installed in large underground caverns. A specially designed and constructed sector of the LHC beam vacuum system transports the beams though each of these collision regions, forming a primary interface between machine and experiment. ATLAS is the largest of the four LHC colliding beam experiments, being some 40 m long and 22 m in diameter. Physics performance, geometry and access imposed a large number of constraints on the design of the beam vacuum system. This paper describes the geometry and layout of the ATLAS beam vacuum system. Specific technologies developed for ATLAS, and for the alignment and installation of the vacuum chambers are described as well as the issues related to the physical interfaces with the experiment.
TRIUMF, Vancouver
The replacement of the 30-year-old Philips cryogenerator with a modern LINDE-1630 helium refrigerator is an important component of TRIUMF’s ongoing 500 MeV cyclotron refurbishing program. Two 10.7 m long cryopanels are cooled with liquid helium rather than with 17 K helium gas, as was the case with the cryogenerator. This has increased the pumping speed and, respectively, improved the vacuum in the approximately 100 m3 cyclotron tank. Additionally, the thermal shield, previously cooled with helium gas, is now cooled with liquid nitrogen. These changes have resulted in increased reliability of the cyclotron vacuum system and, consequently, longer operation periods without maintenance. The new refrigeration unit was commissioned in September 2007. The results from over one year of operational experience are discussed. Also, data on hydrogen cryopumping is presented.
BNL, Upton, Long Island, New York
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
We observed, for the first time, the emission of an electron beam from a hydrogenated diamond in the emission mode on a phosphor screen. Our experimental device is based on the following concept: primary electrons of a few keV energy generate a large number of secondary electron-hole pairs in a diamond. The secondary electrons are transmitted to the opposite face of the diamond, which is hydrogenated, and emitted from its negative-electron-affinity (NEA) surface. Under our present conditions, the maximum emission gain of the primary electron is about 40, and the bunch charge is 50pC/0.5mm2. Our achievement led to new understanding of the hydrogenated surface of the diamond. We propose an electron-trapping mechanism near the hydrogenated surface. The probability of electron trapping in our tests is less than 70%. The hydrogenated diamond was demonstrated to be extremely robust. After exposure to air for days, the sample exhibited no observable degradation in emission.
Fermilab, Batavia
CERN, Geneva
BNL, Upton, Long Island, New York
Funding: This work has been partially performed under the auspices of the US department of energy
The complex LHC crab cavity design and the beam-line configuration pose very tight constraints for the cryostat design. An initial assessment of the LHC main RF cryostat points to a new design both from the RF and engineering point of view. The cavity and tunnel constraints are discussed in detail and an intial cryostat design along with the cryogenic circuit is presented.
IBS, Atlanta, Georgia
MEPhI, Moscow
In today’s turbulent and unsecure world, an X-ray radiographic image and a dual-energy Z-detection mapping of a container contents are needed to provide a reasonable level of port and border security. An interlaced dual-energy electron-beam linac has been developed for the use in cargo inspection systems to meet this growing need. Electron energy of the linac is software controllable from 3 to 15 MeV. Nominal operating energy levels of 4 and 9 MeV were chosen. The 9 MeV beam energy operating point is used for generating the X-ray radiographic image while 4 and 9 MeV beams are used for Z-detection mapping. The S-band linac has been calculated, designed, built and tested. Frequency repetition rate of alternating 4 and 9 MeV beams is 240 Hz. Pulse length is 10 μs. The beam energy in each beam pulse is over 10 J.
CERN, Geneva
IN2P3 IPNL, Villeurbanne
INFN/LNL, Legnaro (PD)
Istituto Nazionale di Fisica Nucleare, Milano
The CNGS facility (CERN Neutrinos to Gran Sasso) aims at directly detecting muon-neutrino to tau-neutrino oscillations. An intense muon-neutrino beam (1017 muon-neutrino per day) is generated at CERN and directed over 732 km towards the Gran Sasso National Laboratory, LNGS, in Italy, where two large and complex detectors, OPERA and ICARUS, are located. After a brief overview of the facility, the major events since its commissioning in 2006 will be discussed. Emphasis will be given on the design challenges and operation constraints coupled to such a high-intensity facility summarizing the acquired experience. Highlights of the 2008 operations, which was the first complete year of physics in CNGS with 1.78·1019 protons delivered on target, will be presented.
NSRRC, Hsinchu
The purpose of this paper is to reduce the Electromagnetic Interference (EMI) from kicker and its pulsed power supply. Analysis of conducted and radiated EMI is the beginning mission. Different frequency range of radiated EMI was measured by different sensors. A hybrid shielding method was used to test reduction of radiated EMI. The copper and μ-metal enclosure was used on kicker magnet to prevent the radiated EMI. The reduction of electromagnetic field showed the effect of different material. Besides, the conducted EMI was also tested and eliminated by adding grounding routs. For decreasing grounding noise to other systems, the individual grounding bus was installed. The experimental results showed significant effect. In the future, TPS (Taiwan Photon Source) injection magnets will design higher performance, lower EMI than TLS (Taiwan Light Source). Therefore reducing and eliminating the interference of electromagnetic waves will be a very important issue. All the EMI prevention schemes will implement in the new project.
CAEP/IFP, Mainyang, Sichuan
Funding: Hongtao Li is with the Institute of Fluid Physics, China Academy of Engineering Physics (CAEP), Mianyang City, Sichuan, China. (Fax:86-816-2282695; e-mail: lht680526@ 21cn.com).
In order to study the physics of fast Z-pinches and research the key issues of pulse power technology, a 10MA/6MV z-pinch primary test stand (PTS) composed of 24 modules will be built in IFP. The prototype module adopted capacitive storage scheme is composed of the 6MV/300kJ Marx-generator (MG), intermediate storage capacitor (IC), laser-triggered switch (LTS), pulse forming line (PFL), water self-breakdown switch (WS), and tri-plate pulse transmission line (PTL). The measured output current of the prototype is approximate 520kA, and output voltage is approximate 2.1MV. The unique multi-stage LTS based on uniform field distribution design and multi-pin unsymmetrical WS make the prototype modules have low systemic delay jitter which is necessary for synchronization of multi-module facility. 1-δ jitter of delay of the system is less than 4ns.
INFN/LASA, Segrate (MI)
Funding: Work partially supported by the FP6 EU programs EUROTRANS (Contract FI6KW-CT-2004-516520) and CARE/HIPPI (Contract RII3-CT-2003-506395).
The two TRASCO elliptical superconducting cavities for low energy (100-200 MeV) protons have been completed with equipping them with cold tuner and a magnetic shield internal to the helium tank. One of the two structures is now available for significative tests of Lorentz Force Detuning control of these low beta structures under pulsed conditions for future high intensity linac programs, as SPL or the ESS. The second structure will be integrated in a single cavity cryomodule under fabrication for the prototypical activities of the EUROTRANS program for nuclear waste trasmutation in accelerator driven systems.
CERN, Geneva
INFN/LASA, Segrate (MI)
Recent studies show that the energy deposition for the LHC phase one luminosity upgrade, aiming at a peak luminosity 2.5 1034 cm-2s-1, can be handled by appropriate shielding. The phase II upgrade aims at a further increase of a factor 4, possibly using Nb3Sn quadrupoles. This paper describes how the main features of the triplet layout, such as quadrupole lengths, gaps between magnets, and aperture, affect the energy deposition in the insertion. We show the dependence of the triplet lay-out on the energy deposition patterns in the insertion magnets. An additional variable which is taken into account is the choice of conductor, i.e. solutions with Nb-Ti and Nb3Sn are compared. Nb3Sn technology gives possibilities for increasing the magnet apertures and space for new shielding solutions. Our studies give a first indication on the possibility of managing energy deposition for the phase II upgrade.
SLAC, Menlo Park, California
INFN/LNF, Frascati (Roma)
Funding: Work supported by the Department of Energy under contract number DE-AC03-76SF00515.
We present a possible design for a fast luminosity feedback for the Super-B Interaction Point (IP). The design is an extension of the fast luminosity feedback installed on the PEP-II accelerator. During the last two runs of PEP-II and BaBar (2007-2008), we had an improved luminosity feedback system that was able to maintain peak luminosity with faster correction speed than the previous system. The new system utilized fast dither coils on the High-Energy Beam (HEB) to independently dither the x position, the y position and the y angle at the IP, at roughly 100 Hz. The luminosity signal was then read out with three independent lock-in amplifiers. An overall correction was computed based on the lock-in signal strengths and beam corrections for position in x and y and in the y angle at the IP were simultaneously applied to the HEB. With the 100 times increase in luminosity for the SuperB design, we propose using a similar fast luminosity feedback that can operate at frequencies between DC and 1 kHz, high enough to be able to follow and nullify any vibrational beam motion from the final focusing magnets.
SLAC, Menlo Park, California
DESY, Hamburg
OXFORDphysics, Oxford, Oxon
ISU, Ames
CLASSE, Ithaca, New York
BNL, Upton, Long Island, New York
KEK, Ibaraki
Funding: Work supported in part by US DOE contract DE-AC02-76-SF00515.
The Interaction Region of the International Linear Collider* is based on two experimental detectors working in a push-pull mode. A time efficient implementation of this model sets specific requirements and challenges for many detector and machine systems, in particular the IR magnets, the cryogenics and the alignment system, the beamline shielding, the detector design and the overall integration. This paper attempts to separate the functional requirements of a push pull interaction region and machine detector interface from the conceptual and technical solutions being proposed by the ILC Beam Delivery Group and the three detector concepts**. As such, we hope that it provides a set of ground rules for interpreting and evaluation the MDI parts of the proposed detector concept’s Letters of Intent, due March 2009. The authors of the present paper are the leaders of the IR Integration Working Group within Global Design Effort Beam Delivery System and the representatives from each detector concept submitting the Letters Of Intent.
*ILC Reference Design Report, ILC-Report-2007-01.
**Materials of IR Engineering Design Workshop, 2007, http://www-conf.slac.stanford.edu/ireng07
Bruce Technologies Inc., North Billerica, MA
D-Pace, Nelson, British Columbia
Many of today’s PET cyclotrons are delivered from the factory for fully-automated “black box” operation in a hospital-based clinical program. Simplicity and ease of operation by non-specialists is desired, and this is achieved in-part through relatively low current targets bolted directly to the PET cyclotron’s main vacuum tank. However, commercial-scale production of short-lived radiopharmaceuticals is becoming increasingly prevalent where substantially higher-current target operation* requiring greater optimization of beam parameters through compact external beamlines**,*** is necessary to meet ever-more demanding production schedules and delivery commitments. This paper describes a system which incorporates the highest current and highest power PET water targets and a short well-instrumented beamline for beam centring/focusing and maximum productivity.
*M. Stokely et al, WTTC11, Cambridge, 2006, p.{10}2.
**M.P. Dehnel et al, NIM B 261, 2007, p. 809.
***J.E. Theroux et al, CYC2007, Giardini Naxos, Italy, 2007, p. 361.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
Funding: This work is supported by the Commission of the European Communities under the 6th Framework Programme “Structuring the European Research Area”, contract number RIDS-011899
After different wakefield test beams and radiation damage studies a prototype design for the International Linear Collider (ILC) spoilers of the betatron collimation system in the Beam Delivery System (BDS) is under development. Studies of activation and residual equivalent dose rate are needed in order to achieve an optimum design as well as to assess the radiation shielding requirements.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
CERN, Geneva
Linac4 is a 160 MeV H- linac which will replace the existing Linac2, a 50 MeV proton linac, at CERN as a first step of the upgraded LHC proton injector chain. No collimation system is foreseen in the baseline design but it will become mandatory for opreation at highest duty cycle in order to reduce activation of the machine. Such a system will also help to reduce activation at low duty cycle. A review of different collimation options, initial studies on collimator designs capable of intercepting beam power of 10, 25 and 50 Watts at energies between 50 and 160 MeV, the activation of such designs and the downstream elements are shown in this paper.
CERN, Geneva
Personnel access to the LHC tunnel will be restricted to varying extents during the life of the machine due to radiation and cryogenic hazards. For this reason a remotely operated modular inspection train, (TIM) running on the LHC tunnel’s overhead monorail has been developed. In order to be compatible with the LHC personnel access system, a small section train that can pass through small openings at the top of sector doors has now been produced. The basic train can be used for remote visual inspection; additional modules give the capability of carrying out remote measurement of radiation levels, environmental conditions around the tunnel, and even remote measurement of the precise position of machine elements such as collimators. The paper outlines the design, development and operation of the equipment including preparation of the infrastructure. Key features of the trains are described along with future developments and intervention scenarios.
CLASSE, Ithaca, New York
Funding: This work was supported by the National Science Foundation.
The theories of beam loss and emittance growth by Touschek and intra-beam scattering formulated for beams in storage rings have recently been extended to linacs. In most linacs, these effects are not relevant, but they become important in Energy Recovery Linacs (ERLs) not only because of their large current, but also because the deceleration of the spent beam increases the relative energy deviation and transverse oscillation amplitude of the scattered particles. In this paper, we describe a methodology for designing a collimator scheme to control where scattered particles are lost. The methodology is based on Touschek particle generation and tracking simulations implemented in {\tt BMAD}, Cornell's beam dynamics code. The simulations give the locations where scattering occurs and the locations where the scattered particles are lost. The simulations are used to determine the trajectory of the scattered particles, which are analyzed to determine optimal locations for collimators.
CLASSE, Ithaca, New York
Funding: NSF PHY-0131508
The forces from Coherent Synchrotron Radiation (CSR) on the particle bunch can be computed exactly for a line charge. Modeling a finite bunch by a line charge often produces a very good model of the CSR forces, and the full bunch can then be propagated under these forces. This 1-D model of CSR has often been used with a small angle approximation, an ultra relativistic approximation, and the approximation that radiation originating in one dipole can be neglected in the next dipole. Here we use Jefimenko's forms of Maxwell's equations, without such approximations, to calculate the wake-fields due to the longitudinal CSR force in multiple bends and drifts. Several interesting observations are presented, including multiple bend effects, shielding by conducting parallel plates, and bunch compression.
CERN, Geneva
BNL, Upton, Long Island, New York
Graz University of Technology (TUG), Signal Processing and Speech Communication Laboratory (SPSC), Graz
In particle accelerators coaxial cables are commonly used to transmit wideband beam signals covering many decades of frequencies over long distances. Those transmission lines often have a corrugated outer and/or inner conductor. This particular construction exhibits a significant amount of frequency dependent group delay variation. A comparison of simulations based on theoretical models and S11 and S21 network analyzer measurements up to 2.5 GHz is presented. It is shown how the non-linear phase response and varying group delay leads to ringing in the pulse response and subsequent distortion of signals transmitted through such coaxial transmission lines.
ANL, Argonne
Funding: This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
A Cf-252 fission source yields neutron-rich fission fragments. The CAlifornium Rare Ion Breeder Upgrade (CARIBU) project is an upgrade to the Argonne Tandem Linear Accelerator System (ATLAS) that provides a 37 GBq (1 Ci) source of these radioactive ions for acceleration. Fission fragments stop in a gas catcher, are extracted into an ECR ion source to increase the charge state, and then accelerated in ATLAS. The radiation fields produced by an unshielded 1 Ci 252Cf source are 46 rem/hr (neutron) and 4 R/hr (gamma) at 30 cm. A shielding system has been constructed that reduces the radiation fields to ≤ 1 mrem/hr at 30 cm from all accessible surfaces. The MCNPX code was used to model the transport of the spontaneous fission neutrons and gamma radiation, and the gamma radiation induced in the shielding materials by the neutrons. The primary neutron shielding material chosen was 5% borated polyethylene, enclosed in steel. Calculations are made for emissions of radioactive effluents, primarily noble gases, using the EPA CAP-88 computer program. The maximum credible incident scenario releases a small quantity of Cf-252. Calculated dose results and mitigation methods are presented.
PSI, Villigen
With increasing beam powers and current densities in current neutron spallation sources one approaches materials' limits. The importance of near-target beam monitoring rises accordingly. At the Paul Scherrer Institute (PSI), the liquid metal target of MEGAPIE set especially stringent requirements for the reliable interruption of the proton beam in case of an anomaly in the incident current density distribution. A completely novel device called VIMOS based on the optical monitoring of a glowing mesh has been devised. By now, the system has been operating successfully for five years. Starting from the initial goal of reliably detecting beam anomalies in a timely manner the scope of the system has been extended to serve as a standard device for beam monitoring and fine tuning of the settings of the beam transport lines. In parallel to the expansion of the use of VIMOS over time, requirements for improving the maintainability of the system while also reducing concurrent cost have become more urgent. A summary of the operational experience of VIMOS will be reported as well as steps taken in order to deliver more quantitative data on the beam profile in the future.
JINR, Dubna, Moscow Region
IBA, Louvain-la-Neuve
C400 is compact superconducting cyclotron for hadron therapy. The permissible level of the transverse magnetic field at the horizontal part of axial injection beam line of a cyclotron is about 10 Gauss. At the same time the C400 magnetic field is about 500 Gauss in magnitude at the places of the ion sources, vertical bending magnet and quadrupole lens location. Thereby the screening of these beam-line elements is needed. The 3D OPERA model of the cyclotron and channel elements is used for this purpose.