First experiments on transfer with radioactive beams using the TIARA array

Abstract

Results from a study in inverse kinematics of the 24Ne(d, pγ)25Ne reaction, using a radioactive beam of 24Ne from the SPIRAL facility at GANIL, are reported. First, a brief overview is given of several methods using radioactive beams to study the classic single-nucleon transfer reactions such as (d, p) or (d, t)/(d, 3He), where the experimental design is strongly influenced by the extreme inverse kinematics. A promising approach to deliver good energy resolution is to combine a high geometrical efficiency for kinematically complete charged particle detection with a high efficiency array for gamma-ray detection. One of the first dedicated set-ups for this type of experiment is the TIARA silicon strip array combined with the EXOGAM segmented germanium array. Together they comprise a highly compact, position-sensitive particle array with 90% of 4π coverage, mounted inside a cubic arrangement of four segmented gamma-ray detectors in very close geometry with 67% of 4π active coverage. Using this setup, the structure of 25Ne has been studied via the (d, p) reaction. A pure ISOL beam of 105 s-1 of 24Ne at 10 MeV/A was provided by SPIRAL and bombarded a CD2 target of 1 mg/cm2. The 25Ne was detected at the focal plane of the VAMOS spectrometer where the direct beam was separated and intercepted. Reaction protons were detected in coincidence with little background. Four resolved peaks were recorded between Ex = 0 and 4 MeV. The data confirm and extend the results from a multinucleon transfer study using the (13C,14O) reaction. Further information has been obtained using the energies of coincident gamma-rays. The reactions 24Ne(d, dγ)24Ne, 24Ne(d, t)23Ne and 24Ne(d, 3He)23F were recorded simultaneously and analysis of these is also underway.