Eur. Phys. J. A (2020) 56: 94
https://doi.org/10.1140/epja/s10050-020-00088-x

Regular Article - Experimental Physics

GRIDSA: femtosecond lifetime measurements with germanium detector arrays

¹ Dipartimento di Fisica dell’Universita degli Studi di Milano, INFN Sezione di Milano, Milan, 20133, Italy
² Institut Laue–Langevin, 71 Avenue des Martyrs, 38042, Grenoble, France
³ Institute of Nuclear Physics Polish Academy of Sciences, 31342, Kraków, Poland

^* e-mail: jentsch@ill.fr

Received: 5 September 2019
Accepted: 9 February 2020
Published online: 21 March 2020

Abstract

We demonstrate the possibility to extract nuclear state femtosecond lifetimes from two-step ray cascades measured with a Ge-detector array. The technique is based on measuring the Doppler shift of a ray, caused by the recoil of a preceding ray emission. Since the two rays are populating/de-populating the same state they form a start/stop signal, the delay of which is compared to the slowing down motion of the nucleus within the target material. A multi-detector array combined with digital acquisition electronics in list mode, allows to measure several angular combinations and two-step cascades efficiently and simultaneously within one single experiment. The concept was demonstrated with the FIPPS array for the reaction, where we obtained good agreement with literature values showing the validity of the method.