[en] A medium size hydrogen bubble chamber has been constructed at the National Laboratory for High Energy Physics, KEK. The bubble chamber has been designed to be operated with a maximum rate of three times per half a second in every two second repetition time of the accelerator, by utilizing a hydraulic expansion system. The bubble chamber has a one meter diameter and a visible volume of about 280 l. A three-view stereo camera system is used for taking photographic pictures of the chamber. A 2 MW bubble chamber magnet is constructed. The main part of the bubble chamber vessel is supported by the magnet yoke. The magnet gives a maximum field of 18.4 kG at the centre of the fiducial volume of the chamber. The overall system of the KEK 1 m hydrogen bubble chamber facility is described in some detail. Some operational characteristics of the facility are also reported. (auth.)

[en] A new method has been developed to control the temperature of a 1-m cylindrical hydrogen bubble chamber at the National Laboratory for High Energy Physics, KEK. The temperature and pressure control system uses liquid hydrogen as a coolant. The system has been working successfully, keeping the bubble chamber temperature to within 0.03 K at about 26 K and the pressure to within 0.05 atm at about 5 atm. This paper describes this temperature and pressure control system and the basic operational characteristics. (author)

[en] For the cavities of ILC, the frequency tuner which can compensate a Lorentz detuning larger than 2 kHz is needed for a high-field operation over than 35 MV/m. A ball-screw tuner was designed aiming at a large dynamic range of compensation for the cavity operated even higher gradient of 45 MV/m level. This tuner response was studied with investigating the cavity characteristics. Tests were performed both at room temperature and at a liquid nitrogen temperature. A high dynamic range of 5 kHz was found feasible. (author)

[en] A helium cryogenic system has been constructed to circulate 300 g/s of Supercritical Helium (SHe) at 4.5 K through a series of superconducting magnets for a neutrino beam line at J-PARC. The conceptual cryogenic system design, considering the cooling characteristics of the magnets, was defined in 2005. The engineering design was subsequently carried out by Taiyo Nippon Sanso Corp. The main elements are a screw compressor with a capacity of 160 g/s at 1.4 MPa, a refrigerator with a capacity of 1.5 kW at 4.5 K and a centrifugal SHe pump with a flow rate of 300 g/s. After system integration in 2008, performance tests were conducted. In a preliminary cooling test to confirm the cryogenic capacity, the cryogenic system successfully performed to the required specifications by circulating a supercritical helium flow of 300 g/s at 0.4 MPa and 4.5 K through a bypass line with a simulated heat load of 520 W and simulated pressure drop of 0.85 MPa. Following this, a full system test with the magnets was carried out. The magnets were pre-cooled from the ambient temperature for eight days and were kept below 4.8 K by circulating pumped SHe. The measured heat leakage at the magnets during these tests, including SHe transfer lines, was 210 W. Since the maximum beam loss predicted is 150 W, the cooling capacity of the cryogenic system is large enough to manage beam operations expected in the future. (author)

[en] High-resolution spectrometers for both incident beams and scattered particles have been constructed at the K1.8 beam line of the Hadron Experimental Facility at J-PARC. A point-to-point optics is realized between the entrance and exit of QQDQQ magnets for the beam spectrometer. Fine-pitch wire chamber trackers and hodoscope counters are installed in the beam spectrometer to accept a high rate beam up to 10"7 Hz. The superconducting kaon spectrometer for scattered particles was transferred from KEK with modifications to the cryogenic system and detectors. A missing-mass resolution of 1.9 ± 0.1 MeV/c"2 (FWHM) was achieved for the Σ peaks of (π"±, K"+) reactions on a proton target in the first physics run of E19 in 2010. (author)