| Paper | Title | Page |
|---|---|---|
| MOPE013 | Measurements of Proton Beam Extinction at J-PARC | 984 |
|
||
|
Proton beam extinction, defined as a residual to primary ratio of beam intensity, is one of the most important parameters to realize the future muon electron conversion experiment (COMET) proposed at J-PARC. To achieve the required extinction level of 10-9, we started measuring beam extinction at main ring (MR) as the first step. The newly developed beam monitor was installed into the abort beam line and the first measurement was successfully performed by using the fast-extracted MR beam. We found that empty RF buckets of RCS, in which all protons were considered to be swept away by a RF chopper before injection to RCS,, contained about 10-5 of the main beam pulse due to chopper inefficiency. We are now developing a new beam monitor with improved performance for further studies at the abort line. In addition, we have started new measurements at the different stage of proton acceleration, i.e. at Linac, 3-50 BT line, and the main ring. In this paper, we present recent results and future prospect of beam extinction measurements. |
||
| TUPEB058 | Online Analyzer System for the Development of the Long-lived Charge-Stripping Foil at the J-PARC | 1653 |
|
||
|
The carbon stripping foil is the key element for the high-intensity proton accelerator. At KEK, the foil test system using the 650keV H- Cockcroft-Walton accelerator is in operation, which can simulate the energy depositions to the foil with the same amount in the J-PARC. In order to quantatively observe the foil degradations (such as foil thinning, pin-hole production) during irradiation, online energy and particle analyzing system is under construction. This report outlines the design detail of the analyzing system including the detectors. |
||
| MOPE024 | Development of Radiation Registant Optics System for High Intensity Proton Beamline at the J-PARC | 1017 |
|
||
|
Optical beam measurement such as OTR(Optical Transition Radiation), ODR(Optical Diffraction Radiation), gas Cerenkov, and so on is a powerful tool to observe a two-dimensional information of high intensity beam profile, so that this method is widely used at various electron and hadron accelerators. However, high radiation field to damage an optical system gradually becomes a major issue with increasing the beam intensity to explore new physics. Our present effort is devoted to develop a high efficient optical system to resist such high radiation field. We newly designed an optical system composed of two spherical mirrors which do not have any lenses vulnerable to radiation. Detailed optics design and a result of optical performance test will be presented. Also we will report a result of a beam test experiment of this optics system combined with an OTR screen performed at high intensity proton extraction beamline of the J-PARC. |
||
| TUPE091 | Recent Progress in the Energy Recovery Linac Project in Japan | 2338 |
|
||
|
Future synchrotron light source using a 5-GeV-class energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting active R&D efforts for that. We are developing super-brilliant DC photocathode guns, two types of cryomodules for both injector and main superconducting linacs, 1.3 GHz high CW-power rf sources, and other important components. We are also constructing a compact ERL for demonstrating the recirculation of low-emittance, high-current beams using those key components. We present our recent progress in this project. |
||
| WEPEA034 | Development and Operational Status of PF-Ring and PF-AR | 2561 |
|
||
|
KEK manages two synchrotron radiation sources, Photon Factory storage ring (PF-ring) of 2.5 GeV and Photon Factory advanced ring (PF-AR) of 6.5 GeV. These rings share an injector linac with the two main rings of KEK B-factory, 8-GeV HER and 3.5-GeV LER. Recently, the linac has succeeded in a pulse by pulse multi-energy acceleration. A top-up operation of PF-ring has been realized as the simultaneous continuous injection to the 3 rings, PF-ring, HER and LER. Development of new injection scheme using a pulsed sextupole magnet continues aiming at practical use in the top-up operation. A rapid-polarization-switching device consisting of tandem two APPLE-II type undulators has been developed at PF-ring. The first undulator was installed in 2008, and the second one will be installed in 2010 summer. PF-AR, operated in a single-bunch mode at all times, has been suffered from sudden lifetime drop phenomena attributed to dust trapping for many years. Using the movable electrodes installed for experiment, we confirmed that the discharge created by the electrode was followed by the dust trapping, and succeeded in a visual observation of luminous dust streaking in front of CCD cameras. |
||
| THPEC045 | Electrostatic Separator and K1.8 Secondary Beamline at the J-PARC Hadron-Hall | 4161 |
|
||
|
In the hadron experimental hall at the 50-GeV Proton Synchrotron (PS) of J-PARC, the secondary beam line K1.8 with double stage separator is expected to provide 1-2 GeV/c kaon beams with less contamination of pions mainly for hadron and nuclear physics experiments with strangeness. An electrostatic (ES) separator is one of key elements of this secondary beam line. The ES separator will generate a 75kV/cm electrostatic field between parallel electrodes of 10cm gap and 6m in length along the beam direction. It is designed so as to be radiation-proof and to lower spark rate at the high intensity proton accelerator facility. The K1.8 line has two 6m ES separators with the intermediate focal point upstream of separators to reduce the pion backgrounds from the production target. The K-/π- ratio of the line is expected to have a larger value than 1 at the experimental target. Beam commissioning of the K1.8 has just started. We will report separator performance, optics design of the K1.8 beam line and the first result of the beam commissioning. |
||
| THPE069 | Simulation of Space Charge Effects in JPARC | 4677 |
|
||
|
Nonlinear space charge interaction in high intensity proton rings causes beam loss, which limits the performance. Simulations based on particle in cell method has been performed for JPARC-Rapid Cycle Synchrotron and Main Ring. Beam loss estimation during acceleration and resonances analysis are discussed with various simulations using dynamic and frozen models. |
||
| THPEB014 | Status and Upgrade Plan of Slow Extraction from the J-PARC Main Ring | 3912 |
|
||
|
High power protons from the J-PARC main ring is slowly extracted using the third integer resonance and delivered to the experimental hall for various nuclear and particle physics experiments. The slow extraction device comprises two electro static septa (ESS),ten magnetic septa, four bump magnets, eight resonant sextupole magnets and their power supply. One of the critical issue of the slow extraction is radiation caused by the beam loss during the slow extraction. We have developed the electrostatic and magnetic septa with thin septum thickness. A unique scheme with large step size and small angular spread of the extracted beam enables hit rate on the ESS less than 1% level. In January 2009, first 30 GeV proton beam has been successfully delivered to the fixed target. Quadrupole magnets and a DSP feedback control system to obtain a uniform beam spill structure were implemented in 2009 summer shutdown period. We will report the extraction efficiency, extracted beam profiles and spill structure obtained by the beam commissioning so far. We will also mention a upgrade plan based on some new ideas to aim a higher performance. |
||
| THPEB022 | Beam Spill Control for the J-PARC Slow Extraction | 3933 |
|
||
|
The slow extraction beam from the J-PARC Main Ring (MR) to the Hadron Experimental Facility is used in various nuclear and particle physics experiments. A flat structure and low ripple noise are required for the spills of the slow extraction. The spill control system has been developed for the J-PARC slow extraction to make a flat structure and small ripple. It consists of the extraction quadrupole magnets and feedback device. The extraction magnets consist of two kinds of quadrupole magnets, EQ (Extraction Q-magnet) which make flat beam and RQ (Ripple Q-magnet) which reject the high frequent ripple noise. The feedback system, which is using Digital Signal Processor (DSP), makes a ramping pattern for EQ and RQ from spill beam monitor. The extraction magnets and feedback device were installed in September 2009, and spill feedback study were successfully started from the beam time in October 2009. Here we report the operation status of magnets and first study of beam commissioning with spill feedback. |
||
| MOPD046 | Construction of New Injector Linac for RI Beam Factory at RIKEN Nishina Center | 789 |
|
||
|
A new additional injector (RILAC2) is constructed at RIKEN Nishina Center in order to enable the independent operation of the RIBF experiments and super-heavy element synthesis. The RILAC2 consists of a 28 GHz superconducting ECR ion source, a low-energy beam transport with a pre-buncher, a four-rod RFQ linac, a rebuncher, three DTL tanks, and strong Q-magnets between the rf resonators for the transverse focusing. Very heavy ions with m/q of 7 such as 136Xe20+ and 238U35+ will be accelerated up to the energy of 680 keV/u in the cw mode and be injected to the RIKEN Ring Cyclotron without charge stripping. The RFQ linac, the last tank of the DTL, and the bunchers have been converted from old ones in order to save the cost. Construction of the RILAC2 started at the end of the fiscal 2008. The RFQ and DTLs will be installed in the AVF cyclotron vault and be tested in March 2010. The ECR ion source and low-energy beam transport will be set on the RILAC2 in 2010 summer, and the first beam will be accelerated in 2010 autumn. We will present the details of the linac part of RILAC2 as well as the progress of construction which includes the result of high power test of resonators. |
||
| THPEB023 | Design of the Low Energy Beam Transport in RIKEN New Injector | 3936 |
|
||
|
The RI beam factory at RIKEN Nishina Center needs high intensity of uranium ion beams. We constructed a new injector, RILAC2, which would provide several hundred times higher intensity. As a part of the RILAC2, we designed the low energy beam transport, LEBT, from the superconducting ECR ion source to the RFQ entrance. In this paper we present its requirements and problems, and show our design as the solutions to them. Especially we focus a technique of a pair of two solenoids to treat a rotational operation and a focusing operation independently. Based on this design, the LEBT was completed in March 2010. The RILAC2 will be operational this fall. |
||
| THPEB024 | Design of the Medium Energy Beam Transport from High-voltage Terminal | 3939 |
|
||
|
The RI beam factory at RIKEN Nishina Center needs high intensity of uranium ion beams. We have used so far the RFQ pre-injector upstream of the linac system, in which the extraction voltage of the ECR ion source is as low as 5.7 kV for the uranium beam. However, for much higher intensity beams from a newly developed superconducting ECR ion source, such a low voltage was expected to significantly increase their emittance due to the space charge effect. To reduce this effect, we prepared a new pre-injector line of 127 kV for uranium beams by placing the ion source on a high-voltage terminal. In this paper we present the design of the 127 kV medium energy beam transport, MEBT, and show the measured results through the line. |