Artificial diamonds as radiation-hard detectors for ultra-fast fission-fragment timing

In the framework of the construction of the double time-of-flight spectrometer VERDI, where we aim at measuring pre- and post-neutron masses directly and simultaneously, ultra-fast time pick-up detectors based on artificial diamond material were investigated for the first time with low-energy heavy ions produced in fission(0.5 MeV/u < E/A < 2 MeV/u). Signal stability under a high radiation dose was determined up to at least 10^9 fission fragments together with more than 3.5 x 10^9 neutrons and 3 x 10^10 alpha-particles. These doses are characteristic for fission experiments. The intrinsic timing resolution of a 100 micron thick polycrystalline CVD diamond detector with a size of 1 x 1 cm^2 was determined to sigma_{int} = (283 +- 41) ps by comparison with Monte-Carlo simulations. Using broadband pre-amplifiers, 4-fold segmented detectors of same total size and with a thickness of 180 micron show an intrinsic timing resolution of sigma_{int} = (124 +- 32) ps. This is highly competitive with the best micro-channel plate detectors. Due to the limited and batch-dependent charge collection efficiency of polycrystalline diamond material, the detection efficiency for fission fragments may be smaller than 100%. This restriction will no longer be an issue when detectors made from single-crystal diamonds are used.

OBERSTEDT Stephan;  BORCEA Ruxandra;  BRYS Tomasz;  GAMBONI Thierry;  GEERTS Wouter;  HAMBSCH Franz-Josef;  OBERSTEDT Andreas;  VIDALI Marzio; 

2013-05-27

ELSEVIER SCIENCE BV

JRC73556

0168-9002,   

http://dx.doi.org/10.1016/j.nima.2013.02.029,    https://publications.jrc.ec.europa.eu/repository/handle/JRC73556,   

10.1016/j.nima.2013.02.029,