M.M. Aléonard

Improvements in the in-beam γ-ray spectroscopy provided by an ancillary detector coupled to a Ge γ-spectrometer: the DIAMANT-EUROGAM II example

For the first time the 4π γ-ray spectrometer EUROGAM II has been coupled to a 4π light charged particle detector array, DIAMANT, during a test experiment on the reaction 32S + 58Ni at 120 MeV beam energy. A very large improvement in the peak-to-background ratio of the γ-spectra has been found when EUROGAM II is triggered by DIAMANT to select an exit channel. A simple algebra has been developed which provides theoretical estimates in good agreement with these experimental results. It is demonstrated that, depending on both the γ-spectrometer and ancillary detector performances, much better peak-to-background can be obtained by such a coupling. For the same peak-to-background ratio, the use of an ancillary detector allows for a lower γ-ray coincidence level and therefore improves the statistics. Ways to select the most appropriate ancillary detector are given. The ability of the ancillary detector to provide a total Doppler shift correction is crucial for the improvement of the peak-to-background ratio.

The DIAMANT electronics and data acquisition system

Abstract We describe the electronics and data acquisition system of the 4π light particle multidetector array DIAMANT. This system has been conceived to be very modular with regard to both the kind and number of detectors. The whole system is designed to run either with a few additional ancillary detectors (Ge) or linked to 4π γ arrays such as EUROGAM. Part of the electronics has been designed using SMD devices; the acquisition is based on CAMAC ADCs and VME units for data acquisition, data transfer is handled via a 32 bit ECL bus (DT32) used for EUROGAM. The data acquisition, distributed on a network, is based on the VxWorks Real Time kernel and the UNIX Operating System.

Correction method for Doppler broadened γ-ray lines using the linear momentum of the evaporated charged particles in heavy-ion induced fusion–evaporation reactions

Abstract A method based on the conservation of linear momentum is used to correct the position and the width of the γ-ray lines of the residual nucleus produced in heavy-ion induced fusion–evaporation reactions. This method implies the measurement of the total number of the emitted particles, their masses, energies and directions of emission in coincidence with the prompt γ-rays. It has been applied to the 120 MeV 32 S + 58 Ni reaction whose data have been collected using the high efficiency and large granularity 4 π light charged particle detector DIAMANT, coupled to the 4 π γ-ray spectrometer EUROGAM II.