Eur. Phys. J. A (2010) 46: 329-336
https://doi.org/10.1140/epja/i2010-11052-7

Regular Article - Experimental Physics

In-beam measurements of sub-nanosecond nuclear lifetimes with a mixed array of HPGe and LaBr₃:Ce detectors

¹ Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH), R-76900, Bucharest, Romania
² Institute for Nuclear Research and Nuclear Energy (INRNE), Bulgarian Academy of Sciences, Sofia, Bulgaria
³ St. Kliment Ohridski University, Sofia, Bulgaria
⁴ CEA, DAM, DIF, F-91297, Arpajon, France
⁵ CSNSM, F-91404, Orsay, France

^* e-mail: bucurescu@tandem.nipne.ro

Received: 16 June 2010
Accepted: 10 October 2010
Published online: 24 October 2010

Abstract

A fast-timing method to determine lifetimes of nuclear states in the sub-nanosecond domain is presented. It is based on in-beam measurements of triple-gamma coincidences in heavy-ion fusion-evaporation reactions, performed with an array of HPGe and LaBr₃:Ce detectors. The high-energy resolution HPGe detectors are used to define de-exciting cascades, while the fast LaBr₃:Ce detectors are used to determine the decay time spectra of selected levels fed by these cascades. A special method to treat the time information of an array of fast detectors is employed in order to fully use the efficiency of the array. Two measurements are presented to illustrate the method: a re-determination of the known half-life ns of the keV, level in ¹⁰⁷Cd (test experiment), and the determination of a half-life ps for the keV, state of ¹⁹⁹Tl .