Bonn 2010 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 53: Instrumentierung X
HK 53.8: Talk
Thursday, March 18, 2010, 18:30–18:45, HG IV
Developments for a New Isochronous Mass Spectrometry Experiment with Uranium Fission Fragments at the FRS-ESR Facility at GSI — •Natalia Kuzminchuk1,2, Samuel Ayet1, Marcel Diwisch1, Hans Geissel1,2, Christophor Kozhuharov2, Ronja Knöbel1,2, Yuri Litvinov2, Wolfgang Plass1,2, Christoph Scheidenberger1,2, Baohua Sun1,2, and Helmut Weick2 — 1II. Physikalisches Institut, Gießen, Germany — 2GSI, Darmstadt, Germany
Masses of nuclei around 130Cd produced by 238U projectile fission will be studied in a planned Isochronous Mass Spectrometry experiment at the FRS-ESR facility at GSI. These nuclei are of much relevance for the understanding of the neutron shell at N=82 as well as for the r-process nucleosynthesis. The masses of the nuclei are directly determined from the revolution frequencies measured by a microchannel plate (MCP) time-of-flight detector. In the detector, ions passing a thin carbon foil release secondary electrons, which are transported to microchannel plates by electric and magnetic fields.
In preparation for the experiment the detector has been further developed and improved. As a high rate of particles is expected for this experiment, the rate acceptance of the detector was determined and increased. The rate capability of MCP is influenced by their channel diameter. MCPs with the same active diameter but different pore sizes were tested. The timing characteristics of the detector were improved by modification of the electron transport from the foil to the MCPs. The design of an anode to improve the signal quality will be presented.