95032063
SHARAQ spectrometer for high-resolution studies for RI-induced reactions
Abstract The SHARAQ spectrometer and High-Resolution Beamline, which began operation in March 2009, have been put into use for six experiments using charge exchange reactions with radioactive isotope beams. For experiments at SHARAQ, detector developments and ion optics studies continue to improve performance in high-resolution nuclear spectroscopy. We have introduced improved timing resolution with CVD diamond detectors, high count-rate beamline tracking detectors and development of multi-particle detection by cathode-readout drift chambers. Ion-optics studies for the high-resolution achromatic (HA) and dispersion-matching (DM) transport modes are also reported here. Momentum tagging in the HA mode demonstrated an improvement in spectroscopic resolution with respect to the momentum spread of the radioactive beam. For the DM transportation mode, a momentum resolution of 1 / 8100 (FWHM) was achieved by taking into account the positions and angles of the beam at the third focal plane of BigRIPS.
122360678
Vacuum system for the SAMURAI spectrometer
Abstract The first commissioning experiment of the SAMURAI spectrometer and its beam line was performed in March, 2012. The vacuum system for the SAMURAI spectrometer includes its beam line and the SAMURAI vacuum chamber with the windows for detecting neutrons and charged particles. The window for neutrons was made of stainless steel with a thickness of 3 mm and was designed with a shape of partial cylinder to support itself against the atmospheric pressure. The window for charged particles was of the combination of Kevlar and Mylar with the thickness of 280 and 75 μm, respectively. The pressure in the vacuum system was at a few Pa throughout the commissioning experiment.
96206265
Production cross section measurements of radioactive isotopes by BigRIPS separator at RIKEN RI Beam Factory
Abstract We have measured the production rates and production cross sections for a variety of radioactive isotopes which were produced from 124 Xe, 48 Ca, and 238 U beams at an energy of 345 MeV/nucleon using the BigRIPS separator at the RIKEN Nishina Center RI Beam Factory (RIBF). Proton-rich isotopes with atomic numbers Z  = 40–52 and neutron-rich isotopes with Z  = 5–16 were produced by projectile fragmentation of the 124 Xe and 48 Ca beam on Be targets, respectively. Neutron-rich isotopes with Z  = 20–59 were produced by in-flight fission of the 238 U beam, in which both Be and Pb were used as production targets. The measured production rates and production cross sections were compared with those of the LISE ++ calculations, and overall fairly good agreement has been obtained. Furthermore, in the measurements with the 124 Xe beam, we have discovered four new isotopes on the proton-drip line, 85,86 Ru and 81,82 Mo, and obtained the clear evidence that 103 Sb is particle unbound with an upper limit of 49 ns for the half-life. The measurements of projectile-fragment momentum distributions have been also performed with the 124 Xe beam, in which the low-momentum tails of the distributions have been measured for the first time at the energy of 345 MeV/nucleon.
122292360
SAMURAI spectrometer for RI beam experiments
Abstract A large-acceptance multiparticle spectrometer SAMURAI has been constructed at the RIKEN RI Beam Factory (RIBF) for RI beam experiments. It was designed primarily for kinematically complete experiments such as the invariant-mass spectroscopy of particle-unbound states in exotic nuclei, by detecting heavy fragments and projectile-rapidity nucleons in coincidence. The system consists of a superconducting dipole magnet, beam line detectors, heavy fragment detectors, neutron detectors, and proton detectors. The SAMURAI spectrometer was commissioned in March 2012, and a rigidity resolution of about 1/1500 was obtained for RI beams up to 2.4 GeV/c.
120444359
New results from GRACE/SUSY at 1-loop
We discuss the physical importance of the 1-loop correction for several supersymmetric processes. The on-shell renormalization scheme in the framework of the MSSM is adopted and 1-loop amplitudes are full-automatically calculated with GRACE system. The system GRACE/SUSY is checked by the independence on the nonlinear gauge parameters.
121044567
LHCf detector performance during the 2009-2010 LHC run
Large Hadron Collider forward (LHCf) has successfully completed the operation during the LHC 2009–2010 period and the detectors were removed in July 2010. The event trigger, data analysis and background have been intensively studied in order to derive inclusive single photon and π0 spectra. In this paper, the details of these intensive studies are described.
119360363
Microscopic structure of high-spin vibrational states in superdeformed A=190 nuclei
Microscopic RPA calculations based on the cranked shell model are performed to investigate the quadrupole and octupole correlations for excited superdeformed (SD) bands in even-even A=190 nuclei. The K = 2 octupole vibrations are predicted to be the lowest excitation modes at zero rotational frequency. The Coriolis coupling at finite frequency produces different effects depending on the neutron and proton number of nucleus. The calculations also indicate that some collective excitations may produce moments of inertia almost identical to those of the yrast SD band. An interpretation of the observed excited bands invoking the octupole vibrations is proposed, which suggests those octupole vibrations may be prevalent in even-even SD A=190 nuclei.
96097660
Laser-cooled radioactive francium factory at CYRIC
Abstract A factory of laser-cooled francium (Fr) atoms is being developed to search for the electric dipole moment (EDM) of the electron. The factory has achieved the production of Fr ions of 9 × 10 5  particles/s and transport with a transmission efficiency of 2%. In pilot experiments, the magneto-optical trapping of rubidium (Rb) has been performed using a new ion-to-atom converter. To achieve the Fr trap, the development and design of each of the factory’s components are in progress.
12101981
Microscopic Study of Wobbling Motions in Hf and Lu Nuclei
One of the most striking findings in the recent high-spin spectroscopy is the discovery of one-phonon, and possibly double-phonon, excitation of the nuclear wobbling rotational bands. In this talk, we first review the properties of observed wobbling motions, and discuss the failure and success of the possible interpretation in terms of the simple rotor model. Then, we further present results of our microscopic study in Hf and Lu nuclei by means of the theoretical framework, the cranked mean-field and the random phase approximation.