Kazuaki Niki

Manufacture of a compact Ku-band electron cyclotron resonance ion source with two resonance zones and variable frequency

A compact ECR ion source working at a Ku band has been manufactured for the production of both low and multiple charged ions. This source can be formed for both the ordinal ECR zone and second Bernstein resonance zone with a half Becr field. The B minimum field configuration is realized by the use of permanent magnets and its axial mirror field can be adjusted within ±0.03 T by a small auxiliary solenoid. Microwave power can be injected from both axial and radial ports. Effective power of 200–250 W can be supplied to the source with a continuously variable frequency in the range of 12.0–14.5 GHz and with a variable pulse mode. The outer dimension of the source is φ180×230 and its total weight is just 30 kg. The design, manufacture and results of the preliminary test are reported.

Present status of the radioactive nuclear beam facility at KEK-Tanashi and the E-arena in the KEK–JAERI joint project

Abstract The performance of the RNB facility at KEK-Tanashi, which is a pilot facility for the E-arena in the KEK–JAERI joint project, is presented. The muonic X-ray spectroscopy of unstable nuclei by combining the RNB with muon-beam from the M-arena in the joint project is introduced.

Wall-loss distribution of charge breeding ions in an electron cyclotron resonance ion source

The ion loss distribution in an electron cyclotron resonance ion source (ECRIS) was investigated to understand the element dependence of the charge breeding efficiency in an electron cyclotron resonance (ECR) charge breeder. The radioactive (111)In(1+) and (140)Xe(1+) ions (typical nonvolatile and volatile elements, respectively) were injected into the ECR charge breeder at the Tokai Radioactive Ion Accelerator Complex to breed their charge states. Their respective residual activities on the sidewall of the cylindrical plasma chamber of the source were measured after charge breeding as functions of the azimuthal angle and longitudinal position and two-dimensional distributions of ions lost during charge breeding in the ECRIS were obtained. These distributions had different azimuthal symmetries. The origins of these different azimuthal symmetries are qualitatively discussed by analyzing the differences and similarities in the observed wall-loss patterns. The implications for improving the charge breeding efficiencies of nonvolatile elements in ECR charge breeders are described. The similarities represent universal ion loss characteristics in an ECR charge breeder, which are different from the loss patterns of electrons on the ECRIS wall.

The RB facility at KEK-Tanashi

An ISOL-based radioactive nuclear beam facility at KEK-Tanashi has been constructed. The linac complex to accelerate radioactive beams comprises a 25.5 MHz split coaxial RFQ (SCRFQ) and a 51 MHz interdigital-H (IH) linac, and accelerates heavy ions up to 1 MeV/u. Beam tests using stable nuclear beam have been done in order to examine the performance of the linacs. Acceleration tests of a radioactive nuclear beam was also performed. This facility is a prototype for the exotic nuclei arena (E-arena) of the proposed Japanese Hadron Facility (JHF), in which 3 GeV, 10 μA protons is used as a primary beam, and a radioactive nuclear beam is accelerated up 6.5 MeV/u by an extension of the IH linac. In this paper, outline, present status and future plan of the facility are reported with emphasis on the heavy ion linacs.

KEK ISOTOPE SEPARATION SYSTEM FOR β DECAY SPECTROSCOPY OF R-PROCESS NUCLEI

Status: Relevant Experiments Chair: 09:50 KEK isotope separation system for beta-decay spectroscopy of r-process nuclei Y. Watanabe (KEK) 2 10:10 Coffee Break 10:40 Mass measurements of rare isotopes with the Penning trap mass spectrometer SHIPTRAP M. Block (GSI) 3 11:00 A Large Acceptance Spectrometer for Deep-Inelastic Scattering with Reaccelerated Radioactive Beams G. Souliotis (Univ. Athens) 3 11:20 Large-bore Solenoid Collector (BigSol) for Isotope and HeavyElement Production F. Becchetti (Univ. Michigan) 4 11:40 Near barrier collisions of transactinides: excitation functions and angular distributions of transfer reaction products V. Zagrebaev (FLNR) 4

Measurement of the 12C(α,γ)16O reaction at TRIAC

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.

An Experimental Plan to Study Beta‐decay Properties on N = 126 Waiting‐Point Nuclei in the r‐process

The {beta}-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 {beta}-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 {beta}-decay properties of several nuclei around A{approx}200 with N = 126 and nearby nuclei by using a stable {sup 136}Xe beam on a {sup 198}Pt target.

Experimental Proposal to Study β Decay Properties around N = 126 Nuclei Produced by Multi‐Nucleon Transfer Reactions

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.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.

Status of Tokai Radioactive Ion Accelerator Complex and Feasibility Study for Transfer Reactions Using Low‐Energy RNB

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.