JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
A 3GeV Rapid-Cycling Synchrotron (RCS) in Japan Proton Accelerator Research Complex (J-PARC) has been commissioned since September 2007. The most important issue in the beam study is to reduce unnecessary beam loss and to keep the beam line clean for the sake of maintenance and upgrade of the machines. From experience of the former accelerators, the average beam loss should be kept at an order of 1 watt per meter for hands-on maintenance. Since it is very difficult to control the beam loss at such a low level, the only measure we can take is to localize any of the losses in a restricted area, where deliberate modules should be provided for quick coupling and remote handling in order to mitigate the personal doses. Accordingly, we have designed the beam collimation system for the purpose of the beam loss localization. We report the performance of the beam collimation system of RCS through the first commissioning results and the residual doses around RCS components.
KEK, Ibaraki
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
J-PARC, KEK&JAEA, Ibaraki-ken
Proportional counter is adopted as a main beam loss monitor system for the RCS and MR of J-PARC. The advantages are signal amplification and radiation hardness. In our case the signal amplification more than 500 and the radiation hardness of not only component materials but also its sensitivity which keeps constant upto the charge accumulation of 0.0035 C/mm by Co-60 γ-ray source irradiation, corresponds more than several years operation. The rise time is an order of μs which satisfies the requirement of MPS (Machine Protection System). The system will be overviewed and the performance with radiation sources and beams will be reported comparing with the MARS simulation.
J-PARC, KEK&JAEA, Ibaraki-ken
KEK, Ibaraki
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
J-PARC, KEK & JAEA, Ibaraki-ken
The beam commissioning of the J-PARC Main Ring synchrotron (MR) has been started from May of this year. A single bunch beam from 3 GeV Rapid Cycling Synchrotron (RCS) was injected to the ring through 3-50 beam transporting (3-50BT) and then was extracted to the beam dump after 1000 turns (typically) without acceleration. The beam intensity was 4·1011 ppb that is 2 orders of magnitude smaller than that of the design intensity. The beam diagnostic system was used to establish the beam operational parameters. The system includes the instrumentations as follows; 3 types of Current Transformers (CTs), DCCT, fast CT (FCT), and Wall Current Monitor (WCM); Beam Position Monitors (BPMs); proportional counter type Beam Loss Monitors (BLMs) at each quadropole magnet; horizontal and vertical tune monitors with exciter systems; and 3 types of beam profile monitors, Multi Wire Profile Monitors (MWPMs) at 3-50BT and downstream of injection septa, a horizontal Flying Wire Profile Monitor (FWPM) and a vertical residual gas Ionization Profile Monitor (IPM) in the ring. At the workshop, the present status of the system will be presented.