Towards more exoticness—X-ray spectroscopy of Ξ− atoms at J-PARC

Atoms with a doubly-strange hadron, namely Ξ−, are really exotic and interesting objects. We are planning to measure X rays from Ξ− atoms for the first time at J-PARC, where a high intensity and high quality kaon beam is available. Our purpose is to obtain the strength of the optical potential, and hence to provide information on the Ξ-N interaction which is currently very poorly known. We can accumulate several thousand counts of X rays and determine the level energy shift down to ~0.05 keV. This is sensitive enough to observe the expected level shift (~1 keV) with reasonable accuracy, while the sensitivities for the level width is somewhat weaker (measurable down to ~1 keV)

Search For A Ξ Bound State In The 12C(K-,K+)X Reaction At 1.8 Gev/c

The 26th International Nuclear Physics Conference, 11-16 September, 2016, Adelaide, Australia

The energy spectrum of forward photons measured by the RHICf experiment in sqrt{s} = 510 GeV proton-proton collisions

The Relativistic Heavy Ion Collider forward (RHICf) experiment aims at understanding the high-energy hadronic interaction by measuring the cross sections of very forward neutral particles in proton-proton collisions at $\sqrt{s}$ = 510 GeV. For the analysis of the photon measurement, the trigger efficiency and the particle identification performance are studied by using the Monte Carlo simulation data and the experimental data. In the RHICf operation, two kinds of trigger modes (Shower, HighEM) were implemented. The trigger efficiency of the Shower trigger is 100$\%$ for photons with the energies more than 20 GeV. The HighEM trigger is designed to detect high energy photons effectively, and the trigger efficiency of the HighEM trigger is 90$\%$ for photons with the energies more than 130 GeV. The correction factor for the photon identification is calculated by using the efficiency and purity. It is found that this correction does not make a sizeable effect on the shape of the energy spectrum because the energy dependency of the factor is small

Measurement of very forward particle production at RHIC with √s=510 GeV proton-proton collisions

The Relativistic Heavy Ion Collider forward (RHICf) experiment has measured neutral particles produced in the very forward direction in the √s=510 GeV proton-proton collisions at RHIC in June 2017. The production cross sections of these particles are crucial to understand the hadronic interaction relevant to the air shower development at the cosmic-ray equivalent energy of 1.4×10$^{14}$ eV, just below the energy of the knee. Together with the data at LHC, accelerator data can cover the interaction in the cosmic-ray energy of 10$^{14}$ eV to 10$^{17}$ eV. In addition, RHICf is able to improve the former measurements of single-spin asymmetry in the polarized proton- proton collisions that is sensitive to the fundamental process of the meson exchange. Common data taking with the STAR experiment will shed light on the unexplored low mass diffraction process

Beam and SKS spectrometers at the K1.8 beam line

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 107 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/c2 (FWHM) was achieved for the ∑ peaks of (π±, K+) reactions on a proton target in the first physics run of E19 in 2010

Status of J-PARC K1.8 Beam Line

The commissioning of the K1.8 beam line in the hadron hall of J-PARC has been going very well. In November 2011, the first physics data was taken for E19 experiment, which is the day-one experiment in the hadron hall of J-PARC. A preliminary result of E19 exhibits no peak for pentaquark Θ+ around 1540 MeV