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KISS project aims at finding an astrophysical condition for synthesizing r-process heavy element isotopes, which are characterized as the third peak in the solar abundance pattern. This is an experimental challenge in nuclear physics to measure ground and isomeric state properties of unknown nuclei around the region of N=126 isotones. So far we have constructed and developed new type of mass separation system, KISS (KEK Isotope Separation System) and performed measurements of lifetimes and hyperfine structures of some platinum and iridium neutron-rich radioactive isotopes by applying multi-nucleon transfer reactions and in-gas laser ionization and spectroscopy (IGLIS) methods. In this report, recent physics results, updated KISS performance, and future's research plan including a challenge of a systematic mass measurement with MRTOF (Multi-Reflection Time-Of-Flight mass spectrograph) are presented. [ABSTRACT FROM AUTHOR]

The ß -decay properties of nuclei with N = 126, which are believed to act as progenitors in the rapid neutron capture (r-) process path forming the third peak (A ~ 195) in the observed r-abundance element distribution, are considered critical for understanding the production of heavy elements such as gold and platinum at astrophysical sites. We have constructed the KEK Isotope Separation System (KISS), which consists of a gas cell based laser ion source (atomic number selection) and an isotope separation on-line (ISOL) (mass number selection), to produce pure low-energy beams of neutron-rich isotopes around N = 126 and to study their ß -decay properties, which are also of interest for astrophysics. The isotopes of interest will be produced by multi-nucleon transfer reactions in heavy ion collisions (e.g. 136Xe projectile on 198Pt target). KISS will allow us to study unknown isotopes produced in weak reaction channels under low background conditions. We successfully extracted the stable 56Fe beam from KISS at the last commissioning on-line experiment with the extraction efficiency of 0.25% and beam purity of more than 98%.We can access the nuclei with N = 126 and measure their half-lives using the KISS in the case of the extraction efficiency of 0.1%. [ABSTRACT FROM AUTHOR]

The ultimate scientific goal of the experimental project with KEK Isotope Separation System (KISS) is to study the decay properties of unknown neutron-rich isotopes having the neutron magic number, N=126, for the astrophysical interest. These isotopes will be produced through the multi-nucleon transfer reactions of neutron-rich heavy-ion beams. Produced activities will be separated and measured by the KISS, which has been constructed at RIKEN. It consists of the argon gas-cell system for stopping and neutralizing the single atoms of nuclear reaction products, the laser system for the laser resonant ionization, and the mass-separator system followed by the decay measurement stations. We have succeeded to extract ions of iron and nickel by the resonant laser ionization at the KISS performance test of the off-line mode. Mass resolving power is observed to be around 900 as expected by the ion-optical calculation. [ABSTRACT FROM AUTHOR]

We have measured the γ-ray angular distribution of the 12C(α,γ)16O reaction at TRIAC (Tokai Radioactive Ion Accelerator Complex) to accurately determine the E1 and E2 cross sections. In this experiment, we used high efficiency anti-Compton NaI(T1) spectrometers to detect a γ-ray from the reaction with large S/N ratio, intense pulsed α-beams to discriminate true event from background events due to neutrons from 13C(α,n)16O reaction with a time-of-flight (TOF) method. We succeeded in removing a background events due to neutrons and clearly detected γ-ray from the 12C(αγ)16O reaction with high statistics. [ABSTRACT FROM AUTHOR]

The β decay properties of the neutron-rich isotopes with neutron number N = 126, out of reach by any reaction well established so far, are very interesting from the astrophysical point of view. We will propose β decay lifetime measurements with a new isotope separation system, which is supposed to separate a single species of the radioactive nuclei among target-like fragments produced via multi-nucleon transfer reactions in binary heavy ion collisions, by using a gas catcher cell combined with laser resonance ionization technique. The present proposal aims to measure β decay properties of several nuclei around A∼200 with N = 126 and nearby nuclei by using a stable 136Xe beam on a 198Pt target. [ABSTRACT FROM AUTHOR]

In order to study the nucleus-nucleus interaction in Pb-based cold fusion, we have measured excitation functions for quasi-elastic scattering of 48Ti, 54Cr, 56Fe, 64Ni, 70Zn and 86Kr projectiles on 208Pb target at backward angles. The barrier distributions were derived from the first derivative of measured quasi-elastic scattering cross sections relative to the Rutherford scattering cross section. The centroids of the barrier distributions show a deviation from several predicted barrier heights toward the low energy side. The shape of the barrier distributions is well reproduced by the results of a coupled-channel calculation taking account of the coupling effects of two phonon excitations of the quadrupole vibration for the projectiles and of the octupole vibration for the 208Pb target. [ABSTRACT FROM AUTHOR]

Two systems of 64Ni+118Sn and 58Ni+124Sn produce the same compound nucleus 182Pt in the fusion reaction and they show the similar fusion cross sections below and near the Coulomb barriers, although only the system of 58Ni+124Sn has positive Q-value multi-neutron transfer channels of 1–11 neutron(s). In order to investigate the possible effect of positive Q-value multi-neutron transfer channels on the capture cross sections, the quasi-elastic back-scattering for the two systems were measured below and near the Coulomb barriers at the backward angles of 162° and 172°. The beam energies were altered in the energy range and the quasi-elastic back-scattering excitation functions were obtained. They were compared with the coupled-channel calculations of collective excitations and a two-neutron transfer channel, indicating no evidence of a significant effect of the positive Q-value multi-neutron transfer channels on the capture cross sections for the system of 58Ni+124Sn. [ABSTRACT FROM AUTHOR]

We report a recent experiment about the measurement of wall distribution of ions externally injected for charge-breeding in an electron cyclotron resonance (ECR) ion source. The ions, radioactive and singly charged 111In, were injected into the ECR ion source (ECRIS) for breeding their charge states at the Tokai Radioactive Ion Accelerator Complex (TRIAC). The residual radioactivity on the wall of the ECR plasma chamber of the source was measured, giving a two-dimensional distribution of the ions failed to be re-extracted during charge breeding. The distribution was decomposed, according to azimuthal symmetry, into three components, asymmetric, 120-degree symmetric, and isotropic ones, whose origins were qualitatively discussed for clarifying ion-losses in the course of charge breeding in ECRIS. [ABSTRACT FROM AUTHOR]

The excitation functions of the 8Li(d,t)7Li and the 8Li(d,p)9Li reactions were directly measured using 8Li beams with Ecm = 0.3, 0.4, 0.5, 0.7, 0.8, 1.0, 1.1, and 1.2 MeV irradiating CD2 targets. These beam energies covered the Gamow peaks for 1-3×109 K. Large cross sections were observed at around Ecm = 0.8 MeV for the 8Li(d,t)7Li and Ecm = 1.0 MeV for the 8Li(d,p)9Li, implying the existence of a resonant state of 10Be at the excitation energy of around 22.4 MeV. Enhanced with the present work, the astrophysical reaction rates of the 8Li(d,t)7Li and the 8Li(d,p)9Li reactions are higher by one and two orders of magnitude than the previously evaluated ones, respectively. [ABSTRACT FROM AUTHOR]

An ISOL-based radioactive nuclear beam facility, Tokai Radioactive Ion Accelerator Complex (TRIAC), has been jointly constructed by High Energy Accelerator Research Organization (KEK) and Japan Atomic Energy Agency (JAEA). The facility started to provide RNBs for experiments in 2005. RNBs, including fission fragments with energies up to 1.1 MeV/nucleon, are available. The experiments were performed with accelerated 8Li beams of various energies. Current status of the equipments and preliminary results on these experimental studies are presented. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

The excitation fuction of the 18Ne(α,p)21Na reaction in was directry measured using a new active target detector system. We are analyzing accumulated data. We will report the result of the development of the GEM - MSTPC and the preliminary results of the 18Ne(α,p)21Na a experiment. [ABSTRACT FROM AUTHOR]

We have developed an active-target type gas-detector, a Gas Electron Multiplier Multiple-Sampling and Tracking Proportional Chamber (GEM-MSTPC) operating with low-pressure He-base mixed gas, where He is used as a target for studies of astrophysical nuclear reaction rates. Different kinds of 400 μm thick GEMs were examined. The gain stability was examined with a configuration of GEMs of 400 μm in thickness fabricated in different ways, against the injection rate of low-energy heavy ions of 105 particles per second. The gain of GEM with Cu electrodes coated by Au was observed to be stable up to the injection rate of 105 particles per second. [ABSTRACT FROM AUTHOR]

The 8Li(α,n)11B reaction has been measured directly and exclusively in the energy region of Ecm=0.45–1.75 MeV by using highly efficient detector system covering Ecm= 0.56 MeV, which corresponds to the Gamow window at T9=1. This experiment has been performed in the condition of inverse kinematics by using low-energy radioactive 8Li beam at the Tandem accelerator facility of Japan Atomic Energy Research Institute. The reaction cross section obtained in the present measurement is consistent with that of the previous exclusive measurements within the errors in an overlapping energy region, but is less than half of that of the inclusive measurements, in particular for lower energy region. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]