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.
KEK, Ibaraki
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
This talk will review the impedance and beam instabilities study for the J-PARC RCS and MR rings. RCS is possibly the first synchrotron employing a massive amount of ceramic chambers to reduce the eddy current effects on the chambers. The resulting RF shields on the chambers to reduce the beam impedance required new considerations on impedance calculation procedure. MR, on the other hand, uses conventional stain-less steel chambers due to its relatively small rep rate (0.3Hz), but then induces huge resistive-wall impedance. The recent study of resistive-wall impedance shows that the actual impedance will be even larger than the calculated one using the conventional formula, when the typical skin depth becomes comparable to the thickness of the chamber. In my talk, I will also touch on the issues of kicker impedances and their possible cures.
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.
Fermilab, Batavia, Illinois
KEK, Ibaraki
Working group F was charged with presentations and discussions on diagnostics and instrumentation of highintensity beams. We had 3 sessions spanning a total time of 330 minutes, in which 13 talks were presented. The presentation time for each talk had to be limited to 15-20 min., in order to allow sufficient time (5-10 min.) for some discussion. This turned out quite well, even though some presentations went longer, not every topic required the anticipated discussion time.
A final discussion session of 110 minutes was held as joint session with working group D (operations).