[en] Beam intensity in the KEK booster decreases to about a half of the injected within one milli-second in the beginning of the acceleration. The mechanism of this loss is successfully explained by the momentum blow up due to the increase of the accelerating RF voltage. The loss is calculated numerically taking into account the beam distribution in the acceptance plane resulting from the multi-turn injection as well as that in the RF bucket during the acceleration. The results are in good agreement with the observations. The essential point in this calculation is that the distribution of the beam to take relatively large momentum deviation is not small but rather large because of the synchrotron motion in the RF bucket. Beam profile projected onto the horizontal plane and that to be obtained by a scraper are calculated with the use of the momentum distribution. Comparison of the calculated profiles with the observations indicates that the contribution of the momentum distribution is considerable. Finally some suggestions are made for increasing beam intensity. (author)

[en] A pulse septum magnet used for beam injection and extraction is commonly installed in a vacuum chamber. In order to cool the magnet coil, metal tubes are attached to it by silver weld, and are drawn from the vacuum to the atmosphere through a flange of the chamber. For the electrical isolation of the coil from the flange, metalized ceramic joints should be inserted in the metal tubes between the coil end and the flange. But water leak into vacuum system will come out within a few years by electric corrosion at the silver weld of the ceramic joint. In our improved magnet, the metal tubes have not any joints in the vacuum chamber, and are drawn from the vacuum to the atmosphere with the same electric potential as coil's through isolated gauge-ports in the flange. As the metal tubes are now isolated by ceramic tubes in the atmosphere, the water leak from the silver weld can be repaired easily. Another improvement is a supporting system of the magnet. The magnet is hung from the cover plate of the box type chamber. So, if a trouble of the magnet happens, we have only to change it for a spare with a cover plate. The position of the top flange of the chamber is arranged so accurately to the beam line that there is no necessary of the resetting after the change of spare. In this paper, the method to fabricate the improved magnet is discussed in detail. (author)

[en] The beam dynamics during the period of H^- charge-exchange injection is analyzed in detail. The formulas to calculate the beam characteristics at the end of this period, such as the hitting probability of protons on the charge-stripping foil, momentum distribution, injection efficiency and emittance are deduced. These formulas include the space charge effect and can be applied to a high intensity beam. The beam characteristics were measured in the KEK Booster Synchrotron by changing the injection energy, thickness of the stripping foil, duration and the injection timing of the chopper H^- ion beam. The calculated results are in good agreement with the measurements. (orig.)

[en] The Operation of KEK-PS has been getting more and more tight, and the beam intensity and higher. Fortunately, machine troubles do not increase, but the residual activity has increased according to the machine time and the beam intensity. When a machine trouble happens, users ask us 'repair the trouble as fast as possible''. So, we must consider ''How to decrease the human DOSE''. We have another trouble caused by the radiation, which is the deterioration of the equipments watching in the PS tunnel, like a fire alarm and a TV camera. (author)

[en] Several kinds of fast beam-loss monitor are developed using a few meter long optical fiber of scintillator or quartz coupled with a photomultiplier tube (PMT). These monitors are very easy to fabricate with low cost. The fast response of these monitor enables to observe bunch by bunch beam loss in a proton synchrotron. Thus, these monitor are utilized for beam tuning of accelerators, such as timing adjust of extraction kicker magnets. The radiation damage of materials which are components of the monitor, such as plastic scintillator, quartz and glass, are also studied by the irradiation of γ-ray and the radiation by the beam loss in KEK-PS. (author)

[en] This report describes a preliminary conceptual design of a high intensity proton synchrotron proposed in a phased program for JHP. A short discussion is devoted to the accelerator system necessary for the first stage of the phased program. The present status of the development study for the JHP 1 GeV proton linac is also described in order to show the properties of the injected H^- beam. Then, it describes results of design work on main components of the synchrotron; the ring lattice, the injection system, the extraction system, synchrotron magnets and its power supply and the radiofrequency accelerating system. Results of computer simulation on the process of beam painting are also given for some painting methods. (author)

[en] At the cyclic particle accelerators, we usually use the septum magnets when the beam is injected and extracted. When the magnetize current is an impulse wave but not a D.C. wave we need level the highest point of the pulse. At the KEK PS accelerators, till today duration of the flat-top has been 100 μsec (4-msec base and 8000 A peak). Because we made the new power supply which is expected to 350 μsec (At the same base and peak current). We want to report the circuit and principle, and conclusion. (author)

[en] When an H^- injection bump system, which consist of four rectangular dipole magnets, is installed in a short straight section, edge effects of the bump magnets can be appreciably large. The Twiss parameters and the dispersion function may be considerably distorted by these effects. Results of calculation are described for a case of the KEK-PS booster synchrotron. (author)

[en] In the proton synchrotron in National Laboratory for High Energy Physics, in the case of transferring beam from the booster ring to the main ring, it is necessary that the phase of high frequency acceleration of both rings coincide, and in order to realize this, by slightly shifting the frequencies of both rings and taking the timing of phase coincidence, beam is transferred. Consequently, as for the waveform of the pulse magnetic field of the septum electromagnet used for taking out beam from the booster, that having flat top is used. However, because of diversified acceleration processes, that having longer flat top has become necessary, and it was decided to replace the power source with the improved one. The power source which is currently in operation and the new power source being manufactured are explained. By inserting coils and a condenser between another condenser and load, the current waveform having longer flat top can be created. The way of functioning of the new power source is described. The analysis of the equivalent circuit of the new power source was carried out. At present, the power source is being manufactured according to the result of the above analysis and the condition of 200 μs flat top waveform. The experiment for extending the flat top further is expected to be carried out after the completion of the power source. (K.I.)

No abstract available