Advances in $\gamma$-rays spectroscopy of neutron-rich fission fragments

International audienceThe first γ-ray spectroscopy of fission fragments characterizing nuclei far from stability and at relatively high angular momentum was reported by Cheifetz and collaborators in 1970. The advent of large γ-ray detector arrays like EUROBALL and Gammasphere allowed the use of high-fold γ-ray coincidences for detailed spectroscopic studies of fission fragments far from stability. The sensitivity was further improved by simultaneous detection of both the fission fragments using gas detectors. However, the use of a spectrometer for identification of fission fragments has been restricted to the study of isomeric states. Recently we used a magnetic spectrometer for isotopic identification of fission fragments produced in reactions around the Coulomb barrier. Measurements of prompt Doppler-corrected γ-rays from uniquely identified fragments (M,Z) formed in fusion- and transfer induced- fission reactions of 238U+9Be at 6.20 MeV/u performed at GANIL will be presented. The fragments were identified in both A and Z using the improved and larger acceptance VAMOS++, while the coincident γ-rays were detected using the EXOGAM array. Results will be presented to demonstrate the sensitivity of this method for prompt γ-ray spectroscopy. This method is complementary to the crosscoincidence technique, and provides improved sensitivity thus opens new avenues in spectroscopy of nuclei far from stability. Status of the work and future plans in studying exotic neutron-rich nuclei through fission at GANIL will be presented.Read More: http://www.worldscientific.com/doi/abs/10.1142/9789814525435_others1