NSRRC, Hsinchu
The free space between magnets of TPS storage ring is very tight, especially the space between quadrupole and sextupole magnets. The minimum space between the yoke of quadrupole and sextupole is about 150mm, and the space between coils is only 10mm. In this case, the significant magnetic field distortions could have an impact on the performance of machine. Two magnets simulation compare to the individual magnet were performed in TOSCA 3D model. The crosstalk effect shows that the sextupole component increases from 0.0004% to 0.04% in the quadrupole magnet and the quadrupole component increases from 0.0008% to 0.06% in the sextupole magnet. We discuss this crosstalk effect and how to decrease the effect with appropriate shielding.
CIEMAT, Madrid
CEA, Gif-sur-Yvette
FZJ, Jülich
The IFMIF-EVEDA accelerator will handle a 9 MeV, 125 mA continuous wave (CW) deuteron beam which aims to validate the technology that will be used in the future IFMIF accelerator. The Linac design is based on superconducting Half Wave Resonators (HWR) operating at 4.4 K. Due to space charge associated to the high intensity beam, a strong superconducting focusing magnet package is necessary between cavities, with nested steerers and a Beam Position Monitor (BPM). First of all, this paper describes the preliminary study to choose between two quadrupoles or one solenoid as focusing device, both using NbTi wire. The solenoid shows more advantages, mainly associated to available space and reliability. Then, electromagnetic and mechanical design of the solenoid and the steerers are reported. Special care is taken in order to fulfil the fringe field limit at the cavity flange. An active shield configuration using an anti-solenoid has been adopted, avoiding remnant magnetization associated to passive shielding materials.
Muons, Inc, Batavia
To achieve the high luminosity required for a muon collider strong quadrupole magnets will be needed for the final focus in the interaction region. These magnets will be located in regions with space constraints imposed both by the lattice and the collider detector. There are significant beam related backgrounds from muon decays and synchrotron radiation which create unwanted particles which can deposit significant energy in the magnets of the final focus region of the collider. This energy deposition results in the heating of the magnet which can cause it to quench. To mitigate the effects of heating from the energy deposition shielding will need to be included within the magnet forcing the aperture to be larger than desired and consequently reducing the gradient. We propose to use exotic high magnetization materials for pole tips to increase the quadrupole gradient.
NSRRC, Hsinchu
Pulsed magnet system of Taiwan Photon source(TPS) requires a very low stray field to avoid parasitic magnetic field into the stored beam. The stray field from storage ring(SR) injection septum is required to be less than 0.2 Gauss. The most common method to protect parasitic magnetic field is to use high permeability and conductivity material, such as a Mu-metal. A 1.2 ms half-sine wave pulse of up to 8280A current peak are supply to a septum and would result in eddy current loss in magnet and conductor current diffusion during the rapid charging on magnet. Moreover, competition between eddy current loss and magnetic permeability would lead to a complex phenomena inside the mumetal shielding cabinet and shielding performance. In this study, the magnetic shielding performance of a shielding cabinet was examined in different shielding cabinet geometry and thickness. The results were calculated in Opera software and show that there is a significant suppression of SR septum stray field when round shielding cabinet is in use.
SLAC, Menlo Park, California
In accelerator design, there is often a need to evaluate the threshold to the (longitudinal) microwave instability for a bunched beam in a storage ring. Several computational tools are available that allow us, once given a wakefield, to numerically find the threshold current and to simulate the development of the instability. In this work, we present the results of computer simulations with codes recently developed at the SLAC National Accelerator Laboratory. Our simulations include the cases of the resonator broadband impedance, the resistive wall impedance and the coherent synchrotron radiation impedance. We compare the accuracy of the threshold prediction and discuss the capabilities and limitations of the codes.
CLASSE, Ithaca, New York
Coherent Synchrotron Radiation (CSR) can be a detrimental effect on particle bunches with high charge and short bunch lengths. CSR can contribute to an increase in emittance and energy spread, and can limit the process of bunch compression. It is especially important in Energy Recovery Linacs (ERLs), because any relative energy spread induced at high energy is magnified after deceleration, and any energy lost by the particles is energy that cannot be recovered. Here we present CSR simulation results using the particle tracking code BMAD for the main operation modes in the proposed Cornell ERL, including an additional bunch compression mode. These simulations consider the effect of CSR shielding, as well as CSR propagation between bends.
SESAME, Amman
The construction of SESAME, a 2.5 GeV, and 3rd generation synchrotron-light source is under progress. The first electron beam from the Microtron at low energy (less than 10 MeV) could be obtained on July, 14th, 2009 and reproduced several times. The tests of the injection and extraction system as well as the hydraulically and electrical tests of the main magnets of the Booster are complete and the vacuum chambers tests are underway. The Booster RF cavity and its plunger have been conditioned successfully by 1.7 kW CW RF power. The installation of the Booster is expected to start after the completion of the shielding. The design of the completely new storage ring is finalised and the Phase 1 beamlines is updated.
ORNL, Oak Ridge, Tennessee
ORNL RAD, Oak Ridge, Tennessee
All stages of the SNS development require significant research and development work in the field of radiological shielding design to assure safety from a radiation-protection point of view for facility operation and to optimize accelerator and target performance. Here we present an overview of on-going shielding work and associated with it procedures and regulations. In the present time, the most of the shielding work is focused on the neutron beam lines and their instrument enclosures in order to commission and provide save operation in the future. This effort is performed according to the guidelines for shielding calculations of SNS neutron beam lines, which sets standards for the analyses and helps to prepare for the Instrument Readiness Review (IRR). The IRR ascertains that the instruments has been design, constructed, and installed to allow safe operation and maintenance. In addition, there is still support for the accelerator facility to redesign parts of the accelerator structures, to design shielding for removed components and test stands for accelerator structures, and for radiation protection analyses for evaluations of accelerator and target safety systems.
BNL, Upton, Long Island, New York
The shielding design for the NSLS-II will provide adequate protection for the full injected beam loss in two periods of the ring around the injection point, but the remainder of the ring is shielded for lower losses of <10% full beam loss. This will require a system to insure that beam losses don't exceed these levels for a period of time that could cause levels outside the shield walls. This beam containment system will measure, provide a level of control and alarm indication of the beam power losses along the beam path from the source (e-gun, linac) thru the injection system and the storage ring. This system will consist of collimators that will provide limits to (an potentially measure) the beam miss-steering and control the loss points of the charge and monitors that will measure the average beam current losses along the beam path and alarm when this beam power loss exceeds the level set by the shielding specifications. This will require some new ideas in beam loss detection capability and collimation. The initial planning and R&D program will be presented.
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Elektronen-Speicherring BESSY II, Berlin
The HoBiCaT facility has been has been set-up and operated at the Helmholtz-Zentrum-Berlin and BESSY since 2005. Its purpose is testing superconducting cavities horizontally in CW mode of operation and it was successfully demonstrated, that TESLA pulsed technology can be used for CW mode of operation with only minor changes. A specific topic is addressed in this paper: elevated dynamic thermal losses in the cavity walls due to trapped magnetic flux.
Fermilab, Batavia
Test facilities for high-gradient superconducting RF cavities must be shielded for particle radiation, which is generated by field emitted electrons in the cavities. A major challenge for the shielding design is associated with uncertainty in modeling the field emission. In this work, a semi-empirical method that allows us to predict the intensity of the generated field emission is described. Spatial, angular and energy distributions of the generated radiation are calculated with the Fishpact code*. The Monte Carlo code MARS** is used for modeling the radiation transport in matter. The detailed distributions of the generated field emission were used for studies with ILC-type superconducting RF cavities with accelerating gradients up to 35 MV/m in the Fermilab Vertical Cavity Test Facility. This approach allows us to minimize the amount of shielding inside cryostat which is an essential operational feature.
* E. Donoghue et al., Proc. SRF-2005, Ithaca NY, June 2005, TuP67.
** N. V. Mokhov and S. I. Striganov, Proc. Hadronic Shower Simulation Workshop, Batavia, Illinois, USA, 6-8 September, 2006.
KEK, Ibaraki
Vertical tests of five 1.3GHz 9-cell cavities (MHI#5-#9) have been done totally 17 times from 2008 to 2009 for S1-Global project in KEK-STF, which is planned in 2010. MHI#7 cavity achieved 33.6MV/m, which was the best result, and the others below 30MV/m. After the exchange for new EP acid on May/2009, many brown stains (niobium oxide) were observed on the interior surface of the cavity, and onset gradient of radiation level measured at the top flange of cryostat was much lower. After several vertical tests, the effect by this phenomenon was gradually relaxed. After four cavities reached above 25MV/m, the gradient suddenly dropped due to the unknown cause at the next vertical test. Two of four cavities were recovered above 25MV/m at the final vertical test again. However, any cavity in KEK-STF did not reach ILC specification (Eacc=35MV/m, Q0=0.8x1010) yet. This means that more improvement for cavity fabrication and surface treatment is necessary. In this presentation, the summary of the vertical tests for S1-Global project in KEK-STF will be reported.
CERN, Geneva
The Compact Linear Collider (CLIC) accelerator has strong precision requirements on the position of the beam. The beam position will be sensitive to external dynamic magnetic fields (stray fields) in the nanotesla regime. The impact of these fields on the CLIC main beam has been studied by performing simulations on the lattices and tolerances have been determined. Several mitigation techniques will be discussed.
Muons, Inc, Batavia
Northern Illinois University, DeKalb, Illinois
Muon Colliders produce high rates of unwanted particles near the beams in the detector regions. Previous designs have used massive shielding to reduce these backgrounds, at a cost of creating dead regions in the detectors. To optimize the physics from the experiments, new ways to instrument these regions are needed. Since the last study of a muon collider detector in the 1990s, new types of detectors, such as solid state photon sensors that are fine-grained, insensitive to magnetic fields, radiation-resistant, fast, and inexpensive have become available. These can be highly segmented to operate in the regions near the beams. We re-evaluate the detector design, based on new sensor technologies. Simulations that incorporate conditions in recent muon collider interaction region designs are used to revise muon collider detector parameters based on particle type and occupancy. Shielding schemes are studied for optimization. Novel schemes for the overall muon collider design, including "split-detectors", are considered.
NSRRC, Hsinchu
NEXANS Deutschland Industries AG & Co. KG, Moenchengladbach
The National Synchrotron Radiation Research Center is constructing the Taiwan Photon Source (TPS), a 3-GeV synchroton facility. The superconducting radio frequency (SRF) cavity modules are selected as the accelerating cavities in the electron storage ring. A test area for the SRF modules is established in the RF laboratory, which includes cryogenic environment, RF transmitter, low level RF control system, and radiation shielded space. The liquid helium is transferred from the cryogenic plant in the experimental area of the Taiwan Light Source (TLS), which is not only far from the RF laboratory but also characterized by a complicated route of 205 meters. The main concerns on the cryogenic transfer are the installation difficulty, heat loss, two-phase flow, and pressure loss. Instead of a multi-channel transfer line, which would request a long installation period on radiation-restrict area, flexible cryogenic transfer lines from Nexans were chosen. The installation period was dramatically reduced to one week. With a test Dewar in the RF lab and valve boxes on both ends of the transfer lines, a long distance cryogenic transfer system was completed and proved to work functional.
Fermilab, Batavia
The Mucool Test Area (MTA) beamline is a dual purpose beamline. The primary purpose is to provide beam for Muon cooling experiments and the secondary purpose is to provide an emittance measuring station for the Linac. A description of the optics for the two different uses of the line will be given and the radiation protection aspects will be discussed.
JAEA/TARRI, Gunma-ken
LBNL, Berkeley, California
The construction of the Extra Low ENergy Antiprotons (ELENA) upgrade to the Antiproton Decelerator (AD) ring has been proposed at CERN to produce a greatly increased current of low energy antiprotons for various experiments including, of course, anti-hydrogen studies. This upgrade involves the addition of a small storage ring and electrostatic beam lines. 5.3 MeV antiproton beams from AD are decelerated down to 100 keV in the compact ring and transported to each experiment apparatus. In this paper, we describe an electrostatic beam line from ELENA to ATRAP and magnetic shielding of the low-energy beam line against the ATRAP solenoid magnet. A possible design of this system is displayed.
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
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.
UCLA, Los Angeles, California
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.