H. Fukuma

Status of Solenoid System to Suppress the Electron Cloud Effects at the KEKB

A large number of solenoids have been installed in the KEKB LER to remove the electron cloud. This paper describes recent solenoid winding work and the effect of it on electron cloud effects.

Operational Results of Optics Handling and Closed Orbit Correction in the Tristan Accumulation Ring

The optics handling system of the TRISTAN accumulation ring (AR) is facilitated by the general purpose computer of KEK as well as the machine control computers and has been dealing with many kinds of optics successfully since November 1983. Also a series of correction procedures has reduced r.m.s. values of closed orbit distortion(c.o.d.) at position monitors from 8.5mm to 0.6mm horizontally, and from 2.3mm to 0.3mm vertically in the typical optics of AR. Using the estimated errors, the pre-correction facility has been installed in AR to make an orbit correction possible in a completely new optics before beam injection.

Magnet system for the KEKB main ring

Abstract KEKB is a two-ring electron–positron collider with asymmetric energies of 8 and 3.5 GeV to study CP violation in B meson decay. In KEKB, there are 21 types of magnets; about 1600 in total. About 430 dipole and quadrupole magnets were recycled from TRISTAN, the preceding program. All quadrupole magnets are equipped with vertical and horizontal steering dipole magnets. The number of steering magnets is about 1700. There are 212 sextupole magnets, and all of them are fixed on remotely controlled movers to adjust their positions to the beam passage. All main dipole magnets have back-leg coils to steer beams precisely. All quadrupole and sextupole magnets are equipped with correction coils to have a capability for beam-based alignment. Also one-turn coils are installed as well to each magnetic pole of the main magnets to monitor the magnetic flux in the case of trouble. The magnetic field in all magnets was measured and its quality strictly checked. After field measurement, the magnets were installed and precisely aligned. A cooling water system and a power supply system for these magnets were constructed. Magnet design was started in 1994, and construction of the two rings was completed in November 1998. The parameters of the magnets and the construction of the KEKB magnet system are described. Some of the problems experienced during this construction work are also presented.

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.

Accelerator plan for a light‐source study at the TRISTAN MR

A three‐month operation with a beam is scheduled for the autumn of 1995 at the TRISTAN MR for the sake of light‐source development and research programs using it. The lattice will be modified so as to enable the installation of an undulator 5.4 m long and achieve a very low‐emittance beam of 5 nm at 10 GeV. The emittance damping wigglers will enhance the radiation‐damping rate, which will stabilize the coherent beam instabilities as well as reduce the emittance more. A considerable number of accelerating cavities will be removed from the ring in order to minimize the impedance of the higher‐order modes of the cavities that may cause coupled‐bunch instabilities and limit the intensity of the stored beam. For the stability of the light beam, a local feedback system will be applied to the electron orbit in the MR. The beam emittance will be measured by detecting the angular distribution of the Compton scattering of laser photons from the beam electrons. To measure the beam emittance in an independent way, vi...

Superconducting quadrupole magnet system for TRISTAN mini-beta insertions

Superconducting quadrupoles for the mini-beta insertions were installed close to every interaction point and their performances were tested successfully. The system consists of four subsystems, which can be operated individually at the local control rooms located near the subsystems and/or at the remote central cryogenic control room.<<ETX>>

Digital Simulation for TRISTAN AR Magnet Power Supply and Control System

The TRISTAN AR Magnet Power Supply is the system for exciting the magnets to accelerate the electron and positron beam from 2.5 GeV to 8 GeV. To estimate its performance the digital simulation was performed using DDS (Digital Dynamics Simulator). The simulation method and the result are described.

Software System for the Operation of the TRISTAN-AR Power Supply

Many power supplies ranging from 1 KVA to 4 MVA are controlled remotely through the serial CAMAC data way. The programs for their operation have been combined to form a software system which includes functions such as current monitoring, interlock and status surveillance, current pattern data generation, current fine adjustment, data transfer and so on.

Crabbing angle measurement by streak camera at KEKB

Crab cavities have been installed in the KEKB rings in order to increase the luminosity. This paper describes the measurement of a crabbing angle by streak cameras.

Recent Progress at KEKB

We summarize the machine operation of KEKB during past one year focusing on progress for this period.