Tatsuro Nakamura

KEKB accelerator control system

The KEKB accelerator control system including a control computer system, a timing distribution system, and a safety control system are described. KEKB accelerators were installed in the same tunnel where the TRISTAN accelerator was. There were some constraints due to the reused equipment. The control system is based on Experimental Physics and Industrial Control System (EPICS). In order to reduce the cost and labor for constructing the KEKB control system, as many CAMAC modules as possible are used again. The guiding principles of the KEKB control computer system are as follows: use EPICS as the controls environment, provide a two-language system for developing application programs, use VMEbus as frontend computers as a consequence of EPICS, use standard buses, such as CAMAC, GPIB, VXIbus, ARCNET, RS-232 as field buses and use ergonomic equipment for operators and scientists. On the software side, interpretive Python and SAD languages are used for coding application programs. The purpose of the radiation safety system is to protect personnel from radiation hazards. It consists of an access control system and a beam interlock system. The access control system protects people from strong radiation inside the accelerator tunnel due to an intense beam, by controlling access to the beamline area. On the other hand, the beam interlock system prevents people from radiation exposure by interlocking the beam operation. For the convenience of accelerator operation and access control, the region covered by the safety system is divided into three major access control areas: the KEKB area, the PF-AR area, and the beam-transport (BT) area. The KEKB control system required a new timing system to match a low longitudinal acceptance due to a low-alpha machine. This timing system is based on a frequency divider/multiply technique and a digital delay technique. The RF frequency of the KEKB rings and that of the injector Linac are locked with a common divisor frequency. The common divisor frequency determines the injection timing. The RF bucket selection system is also described. r 2002 Elsevier Science B.V. All rights reserved.

Present status of Photon Factory Advanced Ring

The upgrade project of the pulse X-ray source PF-AR was successfully completed by the end of 2001. The initial beam current and the lifetime were largely improved. The injection energy was raised from 2.5 GeV to 3.0 GeV, the maximum beam current of 65 mA was achieved. With a new global orbit feedback system, orbit drifts were largely improved.

Present status and beam-stability issues of the KEKB injector linac

The KEKB injector linac was completely upgraded for the KEK B-Factory (KEKB) project in March, 1998. Many difficulties have been overcome during the elaborate commissioning of the upgraded linac since the end of 1997. The 3.5-GeV positron and 8-GeV electron beams have been injected to the KEKB rings with good performance. Much effort has also been continuing to stabilize the intensity and quality of the beams. Some experimental results on the beam stability issues am shown together with the recent operation status in this report. A beam test on a new scheme of a two-bunch injection was started in order to increase the positron intensity since March, 2001.

Control system design for KEKB accelerators

The KEKB project, constructing an asymmetric electron-positron collider for B physics in Japan, has officially approved and has started in 1994. The goal of the KEKB accelerator control system is to provide a powerful, flexible, and extendible control system for both accelerator physicists, who need beam information and are not so patient, and operators, who control all equipment. To achieve this goal on schedule, we decided to use standard technology where it is applicable. We have studied some existing control systems based on Standard Model of the modern accelerator control systems, such as EPICS or V-system, as a framework of the control system and have chosen the base of the control system according to this study. Another key issue in the KEKB accelerator control system is use of database management system for unified management of the information which the control system requires. Integration of control system with the modeling software, SAD, is also discussed.

PF-ring and PF-AR operational status

The present operational status of the Photon Factory storage ring (PF-ring) and the Photon Factory advanced ring (PF-AR) in KEK is reported. The scheduled user times of them were more than 4000 hours in FY2006. In the last summer shutdown, new undulators were installed in both of the rings and have been stably operated. A top-up operation in a single-bunch mode was demonstrated for six days in February 2007 druring the shutdown of KEKB at the PF-ring.

Improvement of photon factory advanced ring control system

As a part of the Photon Factory Advanced Ring (PF-AR) upgrading project, the control system is upgraded. Considering the importance to realize the seamless operation between PF-AR, injector linac and KEKB, we decided to adopt EPICS as a basis of the control system. The old control system of the PF-AR was based on the HIDIC mini computer system and the CAMAC was used as a field-bus. In order to minimize the cost and the work of renewal, we didnt change the device interface layer below CAMAC. A total of 13 EPICS Input/Output controllers (IOCs) are used to replace HIDIC mini computers, and we use the VME modules such as CAMAC crate controller, GPIB interface and the timing synchronization module. The ARCNET driver modules are also used mainly for the control of magnet power supplies. For the archiving of accelerator parameters, we use Channel Archiver, which is one of the EPICS extensions. We have also renewed the accelerator safety control system using the PLC.

The Construction of the SuperKEKB Magnet Control System

There were more than 2500 magnet power supplies for KEKB storage rings and injection beam transport lines. For the remote control of such a large number of power supplies, we have developed the Power Supply Interface Controller Module (PSICM), which is plugged into each power supply. It has a microprocessor, ARCNET interface, trigger signal input interface, and parallel interface to the power supply. The PSICM is not only an interface card but also controls synchronous operation of the multiple power supplies with an arbitrary tracking curve. For SuperKEKB we have developed the upgraded version of the PSICM. It has the fully backward compatible interface to the power supply. The enhanced features includes high speed ARCNET communication and redundant trigger signals. Towards the phase 1 commissioning of SuperKEKB, the construction of the magnet control system is ongoing. First mass production of 1000 PSICMs has been completed and their installation is in progress. The construction status of the magnet control system is presented in this report. (1) Introduction ----Original PSICM KEKB, the asymmetric electron-positron collider for B-meson physics, started in operation in Dec.1998 and finished in Jun. 2010. KEKB control system was EPICS-based, using more than 100 VME/VxWorks computers as IOC (I/O Controller). About 2500 magnet power supplies were installed in the KEKB storage rings and the injection beam transport lines and controlled by 11 IOCs. To connect such many power supplies to the IOCs, we adopted ARCNET as the field bus and developed the PSICM (Power Supply Interface Controller Module). . Original PSICM New PSICM Microprocessor AM186 MPC8306 Clock frequency 20MHz 133MHz Data memory 256kB SRAM 128MB DDR2 SDRAM Program memory 256kB EPROM 64MBit NOR FLASH ARCNET interface 2.5Mbps Backplane mode 2.5Mbps/5Mbps/10Mbps Backplane mode Controller COM20020 COM20022 Media driver HYC2485 HYC5000 Power required 5V 0.4A 5V 1A ARCNET Interface board (4 ch. / boards)

Pulse-to-Pulse Modulation of Injector Linac with Event Timing System

The Pulse-to-Pulse Modulation of Injector Linac at KEK is developed for efficient injections. It automatically switches the beam mode with the real-time process. We integrated this system in 2009 to simultaneously perform the top-up filling into more than one rings with only one injector. The system is based on the Event Timing System. Recently, we upgraded the configuration of Event Timing System to satisfy the complicated requirements of SuperKEKB and developed the test procedure to understand stability of real-time process. The failure of real-time process at Main Trigger Station is intentionally caused when we shorten the allowed computing time as the stress test. The reasonable dependence between the failure rate and the allowed computing time is determined. It indicates we can evaluate the failure rate in case of normal operation at Main Trigger Station.

Beam-beam effects observed at KEKB

At KEKB, a dedicated machine experiment on crab crossing has been carried out for about 4.5 months. Some of the beam-beam effects observed with crab crossing, which include a beam lifetime issue, are discussed in comparison with those with a finite crossing angle of plusmn11 mrad.

Status of the 6.5‐GeV Photon Factory Advanced Ring

The Photon Factory Advanced Ring (PF‐AR) is a 6.5‐GeV synchrotron light source at the High Energy Accelerator Research Organization (KEK). It can provide high‐flux hard X‐rays for such research as the materials science, structural biology and medical applications. The PF‐AR has five insertion devices including four in‐vacuum undulators. It is operated with a single bunch which fits for time‐resolved experiments. A special 5‐GeV operation is partly provided for a clinical application. An initial beam current and a beam lifetime are 60 mA and approximately 14 hours, respectively. Recent developments include an installation of a new in‐vacuum undulator (U♯NW14‐36) to the west rf section, which was accompanied by transferring two rf cavities to other section. The undulator has been successfully operated at a minimum magnetic gap of 10 mm. We also carried out such accelerator studies as a successful test of beam injection using a pulsed quadrupole magnet, a study of low emittance optics, an establishment of tw...