München 2006 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 45: Instrumentation und Anwendungen

HK 45.5: Vortrag

Donnerstag, 23. März 2006, 15:15–15:30, H

Proton detection in the spectrometer aSPECT — •Martin Simson¹, Heinz Angerer¹, Fidel Ayala Guardia², Stefan Baeßler², Michael Borg², Klaus Eberhardt², Ferenc Glück², Werner Heil², Igor Konorov¹, Gertrud Konrad², Naika Luquero Llopis², Raquel Muñoz Horta², Gerd Petzoldt¹, Dennis Rich¹, Yuri Sobolev², Hans-Friedrich Wirth¹, and Oliver Zimmer¹ — ¹Physik Department E18, Technische Universität München — ²Institut für Physik, Universität Mainz

In the retardation spectrometer aSPECT, protons from neutron decay are guided to a detector via magnetic fields. Between the detector and the decay volume is a variable electrostatic potential barrier, which allows us to measure the shape of the proton recoil spectrum and, in turn, the electron-antineutrino correlation coefficient a. Using a and the neutron lifetime, we can determine the element V_ud of the Cabbibo-Kobayashi-Maskawa matrix and clarify the issue of a possible non-unitarity of the CKM matrix.
This measurement requires a very sensitive detection system. We use segmented Si-PIN diodes, which allow us to supress correlated electron background by applying an E×B drift in front of the detector. The entire detection system, which includes a low-noise preamplifier and a fast digital readout, are put on a high voltage of about 30 kV to accelerate the protons to detectable energies.
The detection and readout system as well as first results from beamtimes at the FRM2 in Munich will be presented in this talk.
This work is supported by the MLL Garching and the BMBF.