Nuclear physics experiments with in-beam fast-timing and plunger techniques

摘要

Nuclear lifetime and g factor are crucial observables in nuclear physics, as they give access to the excited states nuclear wave functions using the well-known electromagnetic transition operators. Thus, they are benchmarks to validate or discard nuclear structure theories. During the last decades, the evolution of the nuclear instruments and methods gave birth to several techniques used to measure lifetimes and moments. Among them, the in-beam Fast Electronic Scintillation Timing (FEST) technique is used to measure lifetimes of nuclear states in the picosecond to nanosecond range. Plunger devices originally developed to perform lifetime measurements of excited states in the picosecond range using the Recoil Distance Doppler Shift (RDDS) are now also employed to measure g factor using the new Time-Differential Recoil-In-Vacuum (TDRIV) technique. Recently commissioned, the ROmanian array for Spectroscopy in HEavy ion REactions (ROSPHERE) is dedicated to perform y-ray spectroscopy, specially suited for lifetime measurements using the RDDS and in-beam fast-timing techniques at the 9 MV Bucharest-Tandem accelerator facility of the Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH). An introduction of above-mentioned techniques is provided and selected results are illustrating them with physics cases. The in-beam fast-timing and RDDS techniques are described using lifetime measurements respectively in ~(67)Cu and ~(120)Te measured at the 9 MV Bucharest-Tandem accelerator. Finally, the precise g factor measurement of the first-excited state in ~(24)Mg using by the new TDRIV technique at the ALTO-Tandem Orsay facility is presented.