[en] At J-PARC MR Slow Extraction, Dynamic Bump System is implemented to reduce the beam loss. During extraction, bump orbit is defined by the bare horizontal tune which depends on the QFN and EQ current values. The bump current values are processed by a dynamic bump DSP from the given QFN current pattern and the real time EQ current value. But the control instruments of bump magnet powersupplys wasn't suitable, this system was unstable. We developed a new DAC and amplifier for powersupply control. Dynamic bump system has become stability. (author)

[en] At J-PARC Slow Extract, bump orbit was fixed during extraction, that couldn't decrease beam loss. To make measures, we develop the dynamic bump system for J-PARC slow extraction. (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)

[en] A search for the Θ"+ pentaquark in the π"-p → K"-X reaction was performed at the J-PARC Hadron Facility. Two data samples were collected in 2010 and 2012 at π beam momenta of 1.92 and 2.0 GeV/c, respectively. No peak structure was observed in the missing mass spectra obtained from either data set. The upper limit for the production cross section averaged over the scattering-angle range of 2° to 15° in the laboratory frame was found to be 0.28 μb/sr. The decay width of the Θ"+ can be directly connected to the production cross section through a theoretical calculation using an effective Lagrangian. The estimated upper limits of the width were 0.41 and 2.8 MeV for the spin-parities of 1/2"+ and 1/2"-, respectively. (author)