Speaker
Description
We report on the pre-neutron mass yields of actinides near $^{232}$Th measured in inverse kinematics at the VAMOS++ spectrometer and its newly developed second arm. The experiment used a $^{232}$Th beam accelerated for the first time at GANIL, impinging on a carbon target (100 $\mu g\cdot cm^{-2}$) inducing fission of a few actinides from multi-nucleon transfer. The VAMOS++ spectrometer allows to measure the isotopic yields after neutron evaporation with a few percents of resolution. It is coupled with the PISTA detector, an array of DSSD detecting and identifying the target-like recoil at forward angles. This allows a better control of the excitation energy of the fissioning system. We present the new detection setup added to the VAMOS++ spectrometer to measure the second fragment. It is composed of two Multi-Wire Proportional Counters (MWPC) separated by 1.6~m, at 40° from the VAMOS++ spectrometer. This allows a precise velocity measurement of the second fragment which, coupled to the VAMOS identification, give access to the pre-neutron masses and therefore to the neutron evaporation of the fragment detected in VAMOS, event by event.
