K. Katori

Observation of Second Decay Chain from 278113

RIKEN (The Institute of Physical and Chemical Research), Wako, Saitama 351-0198 Department of Physics, Saitama University, Saitama 338-8570 Center for Instrumental Analysis, Niigata University, Niigata 950-2181 Center for Nuclear Study, University of Tokyo, Wako, Saitama 351-0198 Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 Department of Chemistry, Niigata University, Niigata 950-2181 University of Tsukuba, Tsukuba, Ibaraki 305-8571 Department of Physics, Tohoku University, Sendai 980-8578 Department of Physics, Yamagata University, Yamagata 990-8560

Experiment on Synthesis of an Isotope 277112 by 208Pb+70Zn Reaction

The production and decay of 277 112 have been investigated using a gas-filled recoil ion separator in irradiations of 208 Pb targets with a 70 Zn beam at 349.5 MeV. We have observed two α-decay chains that can be assigned to subsequent decays from 277 112 produced in the 208 Pb( 70 Zn,n) reaction. After emitting four consecutive α-particles, both the chains terminate by spontaneous fission decays of 261 Rf, and the decay energies and decay times of both the chains obtained in the present work agree well with those reported by a group at Gesellschaft fur Schwerionenforschung (GSI), Germany. The present result gives the first clear confirmation of the discovery of 277 112 and its α-decay product 273 Ds reported previously.

Production and decay properties of 272111 and its daughter nuclei

The production and decay of 272 111 has been investigated using a gas-filled recoil ion separator in irradiations of 209 Bi targets with 64 Ni beam at 320, 323 and 326 MeV. We have observed 14 α-decay chains in total, that can be assigned, on the basis of their time correlations, to subsequent decays from 272 111 produced in the 209 Bi( 64 Ni,1n) reaction. The present result is the first clear confirmation for the discovery of 272 111 and its α-decay products, 264 Bh and 268 Mt, reported previously by a GSI group. New information on their half-lives and decay energies as well as the excitation function is presented.

Production and decay properties of

The production and decay of 272 111 has been investigated using a gas-filled recoil ion separator in irradiations of 209 Bi targets with 64 Ni beam at 320, 323 and 326 MeV. We have observed 14 α-decay chains in total, that can be assigned, on the basis of their time correlations, to subsequent decays from 272 111 produced in the 209 Bi( 64 Ni,1n) reaction. The present result is the first clear confirmation for the discovery of 272 111 and its α-decay products, 264 Bh and 268 Mt, reported previously by a GSI group. New information on their half-lives and decay energies as well as the excitation function is presented.

^{272}

A gas-filled type of recoil separator for heavy element research was installed at an experimental hall of RIKEN Linear Accelerator facility to realize getting higher intensity of primary beam and long beam time. Performance of the separator was studied using target recoils and various nuclear reactions. The results show the high performance of the separator for heave element research. As an application of the GARIS, production and identification of an isotope of the 110th element 271[110] have been performed using the 208Pb(64Ni,1n)271[110] reaction. Three decay chains coincide well both in decay times and energies with the ones reported by the group of SHIP experiment at GSI, Germany. Our results provide a confirmation of the synthesis of an isotope 271[110] of element 110.

111 and its daughter nuclei

Decay properties of an isotope {sup 266}Bh and its daughter nucleus {sup 262}Db produced by the {sup 248}Cm({sup 23}Na,5n) reaction were studied by using a gas-filled recoil separator coupled with a position-sensitive semiconductor detector. {sup 266}Bh was clearly identified from the correlation of the known nuclide, {sup 262}Db. The obtained decay properties of {sup 266}Bh and {sup 262}Db are consistent with those observed in the {sup 278}113 chain by RIKEN collaboration, which provided further confirmation of the discovery of {sup 278}113.

Status of heavy element research using a gas-filled recoil separator at RIKEN

The production and decay of 272 111 has been investigated using a gas-filled recoil ion separator in irradiations of 209 Bi targets with 64 Ni beam at 320, 323 and 326 MeV. We have observed 14 α-decay chains in total, that can be assigned, on the basis of their time correlations, to subsequent decays from 272 111 produced in the 209 Bi( 64 Ni,1n) reaction. The present result is the first clear confirmation for the discovery of 272 111 and its α-decay products, 264 Bh and 268 Mt, reported previously by a GSI group. New information on their half-lives and decay energies as well as the excitation function is presented.

Decay Properties of 266Bh and 262Db Produced in the 248Cm+23Na Reaction—Further Confirmation of the 278113 Decay Chain—

A gas-filled recoil separator for heavy element research was installed at the experimental hall of RIKEN linear accelerator facility. An acceptance of the separator was measured using a-particles from 241Am source. Measured acceptance was 12.2 msr. Transmissions of the separator were measured with low-energy Pb (0.26 AMeV) and Bi (0.11 AMeV) recoils. It was found that the transmission for Pb (0.26 AMeV) was 0.84, and that for Bi (0.11 AMeV) was 0.33. Equilibrium charge states for Pb and Bi in helium gas were deduced.