[en] The electron responses of PWO, LaBr₃:Ce, and LYSO:Ce crystal scintillators have been investigated at the Kyoto University Free Electron Laser (KU-FEL) facility, which provides electron beams satisfying a single-electron hit condition. The linearities and scintillation decay times were measured at electron energies between 5 and 40 MeV. The distributions of pulse height were compared with those from Monte Carlo simulations to deduce the deposit energies. All the scintillators are found to show good linearity, and their decay times are roughly constant over the measured energy range.

[en] Lead tungstate (PWO) crystal has a very fast response, high atomic density and high radiation hardness. Therefore, they are suitable to be used for high-energy nuclear data measurements under high-background circumstances. Although a good electron-ion separation with a pulse shape analysis technique is essential, scintillation pulse shapes have not been observed with electron beams of a wide energy range. A single-electron beam technique has been developed at Kyoto University Free Electron Laser (KUFEL), and electron beams of 4-38 MeV are available. During the experiments, single electron beams bombarded a PWO crystal. By using oscilloscope we observed scintillation pulses of a PWO crystal coupled with a photomultiplier tube. Measured spectra were compared with the simulation code of EGS5 to analyze scattering effects. As the result, the pulse amplitudes show good linearity and the pulse shapes are almost constant in the observed energy range

[en] The measurement was performed at the Heavy Ion Medical Accelerator in Chiba (HIMAC), National Institute for Radiological Sciences, Japan. The carbon-ions were accelerated to 100 MeV/u and bombarded the target (C, Al, and Co). Emitted charged particles were detected by counter-telescopes installed at the PH2. Light particles (p, d, t. ³He and α) were detected with two ΔE-E telescopes comprising two silicon-surface-barrier detectors (SSDs), a GSO(Ce) crystal and four PWO crystals. Particles heavier than α were detected with two ΔE-E telescopes consisting of two SSDs and a CsI(Tl) crystal. Thanks to their high energy resolutions, isotope separation was achieved for many of detected particles. This report describes experimental results obtained during 2018-2019 at HIMAC. (author)

[en] We have carried out an experimental search for the simplest kaonic nucleus, K"-pp, by using the d(π"+, K"+) reaction at p_π_"+ = 1.69 GeV/c. The differential cross section of this reaction with covering a wide missing-mass range from the Λ production threshold to the Λ(1405)/Σ(1385) region has been measured for the first time. The inclusive missing-mass shape of the Λ and Σ production region was understood with a simple quasi-free picture except for an enhancement at 2.13 GeV/c"2 due to a ΣN cusp. An obtained peak attributed to Y* production was significantly shifted to the low mass side compared with the simulation by -22.4 MeV/c"2. (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] We have measured the inclusive missing-mass spectrum of the ¹²C(K^-, p) reaction at a K^- beam momentum of 1.8 GeV/c. This experiment was carried out as a by-product of a pilot run of the J-PARC E05 experiment, which was conceived to search Ξ-hypernuclei by using the (K^-, K⁺) reaction at J-PARC K1.8 beam line. In present measurement, we study the K-bar-nucleus interaction by comparing the observed missing-mass spectrum with a DWIA calculation. In a preliminary analysis, a 'KINK' structure, which might be originated from the threshold of K^-N → Σπ absorption, was found. (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)