[en] An optimized momentum spread is predicted for best bunching factor and RF capture at RCS injection. A sufficiently wide range of output momentum spread was successfully achieved from J-PARC linac for the verification. It is found that not only momentum spread, but also transverse emittance, Twiss parameters and dispersion play import roles. Series of theoretical and experimental tests were carried out for improving J-PARC linac output beam for mitigating beam loss at injection to RCS. (author)

[en] We present a case in which multiple pancreatic tumours were diagnosed as metastatic clear cell renal carcinomas with chemical shift MRI (CSI) before surgery. Radiologists may be unable to recognize the loss of intensity on CSI macroscopically. We believe that it is useful to make subtraction images and calculate signal intensity on CSI, even if the lesions are multiple metastatic tumours Copyright (2005) Blackwell Publishing Asia Pty Ltd

[en] We are now preparing for the third generation (e,e'K⁺) Λ hypernuclear spectroscopic experiment at Hall C, Jefferson Lab (USA). The goal of the experiment is the precise spectroscopy of hypernuclei in wide mass region. We have constructed a new high resolution electron spectrometer 'HES' dedicated to (e,e' K⁺) hypernuclear study in Japan and it was shipped to JLab in February, 2008. We will discuss about the physics of the (e,e' K⁺) hypernuclear study at JLab and report the current preparation status of the third generation experiment. (authors)

No abstract available

[en] The Facility for Rare Isotope Beams (FRIB) will be the world's premier rare-isotope beam facility. Experiments with the majority ($\sim <!--\; ???\; -->80$%) of the isotope predicted to exist will become available. The FRIB facility is based on a superconducting (SC) heavy ion linac with output energy above 200 MeV/u for any ions at beam power of 400 kW. FRIB includes a target facility for in-flight production of rare isotopes. A three-stage fragment separator will be used to prepare fast rare isotope beams with high-purity for nuclear physics experiments. The installation work of the accelerator and experimental systems is approaching completion and multi-stage beam commissioning activities started in summer 2017 with expected project completion in early 2022. The commencement of operation for users' experiments is planned immediately following the project completion.

[en] We have measured the longitudinal bunch size of beams from the radio-frequency quadrupole linac (RFQ) at the Japan Proton Accelerator Research Complex (J-PARC). The radio-frequency deflector (RFD) is installed in the medium-energy beam transport section (MEBT1) between the RFQ and the drift-tube linac (DTL). The RFD, which is usually used to produce a macro pulse configuration for the 3-GeV rapid-cycling synchrotron, is utilized to produce a different deflecting angle depending on the bunch arrival phase. Transverse beam profiles were measured after the RFD with and without deflection to extract the longitudinal bunch size. The Courant-Snyder parameters in the longitudinal direction were estimated by measurements for different strength of the upstream buncher. These measurements are one of the important steps to understand the longitudinal beam properties at a high beam current. (paper)

[en] The output beam power of the J-PARC linac has been improved by increasing the acceleration energy and peak beam current. The beam loss is getting serious along with increasing output beam power; however, the beam loss in the front-end region is difficult to detect because of the low energy of the radioactive emission. An interlock system using the beam current monitors has been developed to prevent significant material activation. In this system, an electrical circuit measures the beam transmission between the two beam current monitors. This study describes the design and performance of this electrical circuit and introduces the system configuration. (author)

[en] In the past year J-PARC linac accomplished many upgrades. From 2016, the J-PARC linac started 40 mA operation. Separated amplifiers were ready for the chopper cavities, and the ringing effects due to previous connection in series were cured. Newly designed bunch shape monitors for MEBT1 (BSM) (3 MeV) and MEBT2-ACS (∼200 MeV) were tested on-line, which will work for the longitudinal measurement and 3D matching to DTL and ACS. Lattices in the 200∼400 MeV part (ACS section) with actually redesigned both in transverse and longitudinal planes were studied and tested. Results of successfully mitigated beam loss from the intra-beam stripping effect were obtained. (author)

[en] We used bunch shape monitors (BSMs) to measure the longitudinal bunch length of a negative hydrogen ion beam in the J-PARC linac. Because we experienced a vacuum degradation to suspend a beam operation during the BSM operations, BSMs were once dismounted for vacuum conditioning. We installed one BSM again in the beam line with additional vacuum equipment. We stared to measure the 191-MeV beam again to tune the buncher amplitude after checking a functioning BSM by comparing its results with those of a simulation. To evaluate the measurement errors with peak beam current increasing, we observed waveforms with various beam currents. Therefore, the RMS bunch length depends on the peak beam current and the bending at the pulse head grows with the peak beam current. Furthermore, to avoid the thermal stress, we compared the data taken at an off-center beam with the ones taken at an on-center beam, because a target wire will be exposed to a higher peak beam current. In this study, we introduced the peak beam current dependence of the bunch length waveforms, and an effect of on-/off-centering of the wire position. Finally, the new buncher tuning method using one BSM is discussed. (author)

[en] We have measured the angular correlation of the pair nucleons np and nn emitted from the nonmesonic weak decay (NMWD) of _Λ¹²C produced via the (π+,K+) reaction in coincidence measurement. The Λp → np and Λn → nn modes were clearly identified by measuring the back-to-back correlation of the emitted nucleon pairs which is the characteristic of two-body kinematics. From the measured nucleon pair numbers Nnn and Nnp, the ratio Γn/Γp of the partial decay widths Γn(Λn → nn) and Γp(Λp → np) of _Λ¹²C was extracted to be 0.51 ± 0.13(stat)±0.04(syst); this result is almost free from the ambiguity due to the nuclear final state interaction and 3-body decay process, which were inherent in the previous results. The obtained Γn/Γp ratio of _Λ¹²C (p-shell) is close to that of _Λ⁵He (s-shell). The results are consistent with those of recent theoretical calculations