Darmstadt 2008 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 4: Instrumentation und Anwendungen I

HK 4.6: Talk

Monday, March 10, 2008, 15:30–15:45, 2C

Diamond detectors for ultra-fast fission-fragment timing — •Stephan Oberstedt¹, F.-J. Hambsch¹, Cezar Negoita¹, Andreas Oberstedt², Carlos Chaves de Jesus¹, Wouter Geerts¹, and Marzio Vidali¹ — ¹EC-JRC IRMM, B-2440 Geel — ²Örebro University, S-70182 Örebro

The precise knowledge about delayed neutron (DN) yields in fission is highly relevant for the reliable control of nuclear reactors and the save operation of sub-critical assemblies, like e. g. ADS, where minor actinides are mixed into the nuclear fuel. One way to achieve a more fundamental understanding of the production of so-called DN pre-cursor isotopes in fission is to measure the emission yields with high mass resolution. For this purpose a two-arm time-of-flight spectrometer for high resolution fission-fragment spectromertry is being built at the Institute for Reference Materials and Measurements, a Joint Research Centre of the European Commission. The ultimate goal is to achieve a mass resolution A/ΔA ≈ 120 in conjunction with a reasonable counting efficiency. One pre-requisite for such a device is the use of ultra-fast timing detectors. For this purpose poly-crystalline chemical vapour deposited (pcCVD) diamond detectors have been tested for the first time as time pick-up for binary fission fragments. In particular, the charge-collection efficiency has been investigated as a function of the irradiation time, which corresponds to the integral dose applied to the detector material. The intrinsic timing resolution for fission fragments has been determined to be better than 40 ps.