Abstract: The excited states of unstable O-20 were investigated via.-ray spectroscopy following the O-19(d, p)O-20 reaction at 8 AMeV. By exploiting the Doppler shift attenuation method, the lifetimes of the 2(2)(+) and 3(1)(+) states were firmly established. From the gamma-ray branching and E2/M1 mixing ratios for transitions deexciting the 2(2)(+) and 3(1)(+) states, the B(E2) and B(M1) were determined. Various chiral effective field theory Hamiltonians, describing the nuclear properties beyond ground states, along with a standard USDB interaction, were compared with the experimentally obtained data. Such a comparison for a large set of gamma-ray transition probabilities with the valence space in medium similarity renormalization group ab initio calculations was performed for the first time in a nucleus far from stability. It was shown that the ab initio approaches using chiral effective field theory forces are challenged by detailed high-precision spectroscopic properties of nuclei. The reduced transition probabilities were found to be a very constraining test of the performance of the ab initio models.

Abstract: Background: Multinucleon transfer reactions (MNT) are a competitive tool to populate exotic neutron-rich nuclei in a wide region of nuclei, where other production methods have severe limitations or cannot be used at all. Purpose: Experimental information on the yields of MNT reactions in comparison with theoretical calculations are necessary to make predictions for the production of neutron-rich heavy nuclei. It is crucial to determine the fraction of MNT reaction products which are surviving neutron emission or fission at the high excitation energy after the nucleon exchange. Method: Multinucleon transfer reactions in Xe-136 + U-238 have been measured in a high-resolution gamma-ray/particle coincidence experiment. The large solid-angle magnetic spectrometer PRISMA coupled to the high-resolution Advanced Gamma Tracking Array (AGATA) has been employed. Beamlike reaction products after multinucleon transfer in the Xe region were identified and selected with the PRISMA spectrometer. Coincident particles were tagged by multichannel plate detectors placed at the grazing angle of the targetlike recoils inside the scattering chamber. Results: Mass yields have been extracted and compared with calculations based on the GRAZING model for MNT reactions. Kinematic coincidences between the binary reaction products, i.e., beamlike and targetlike nuclei, were exploited to obtain population yields for nuclei in the actinide region and compared to x-ray yields measured by AGATA. Conclusions: No sizable yield of actinide nuclei beyond Z = 93 is found to perform nuclear structure investigations. In-beam gamma-ray spectroscopy is feasible for few-neutron transfer channels in U and the -2p channel populating Th isotopes.

Abstract: Shape coexistence is a ubiquitous phenomenon in the neutron-rich nuclei belonging to (or sitting at the shores of) the N = 20 island of inversion (IoI). Exact isospin symmetry predicts the same behavior for their mirrors and the existence of a proton-rich IoI around Z = 20, centered in the (surely unbound) nucleus Ca-32. In this article we show that in Ca-36 and S-36, Coulomb effects break dramatically the mirror symmetry in the excitation energies due to the different structures of the intruder and normal states. The mirror energy difference (MED) of their 2(+) states is known to be very large at – 246 keV. We reproduce this value and predict the first excited state in Ca-36 to be a 0(+) at 2.7 MeV, 250 keV below the first 2(+). In its mirror S-36 the 0(+) lies at 55keV above the 2(+) measured at 3.291 MeV. Our calculations predict a huge MED of -720 keV, that we dub the “colossal” mirror energy difference. A possible reaction mechanism to access the O-2(+) in Ca-36 will be discussed. In addition, we theoretically address the MEDs of the A = 34, T = 3 and A = 32, T = 4 mirrors.

Abstract: The NEutron Detector Array, NEDA, will form the next generation neutron detection system that has been designed to be operated in conjunction with gamma-ray arrays, such as the tracking-array AGATA, to aid nuclear spectroscopy studies. NEDA has been designed to be a versatile device, with high-detection efficiency, excellent neutron-gamma discrimination, and high rate capabilities. It will be employed in physics campaigns in order to maximise the scientific output, making use of the different stable and radioactive ion beams available in Europe. The first implementation of the neutron detector array NEDA with AGATA 1 pi was realised at GANIL. This manuscript reviews the various aspects of NEDA.

Abstract: .In a fusion-evaporation reaction, nuclei are produced by evaporating light-charged particles and neutrons from the compound nucleus. Typically, a nucleus of interest is produced as a result of a part of the total cross-section and, in order to guarantee a good channel discrimination, a particle detector, like the EUCLIDES 4 Si-ball array, is necessary. EUCLIDES has been quoted in more than a hundred publications resulting from many experiments performed in combination with the EUROBALL and GASP -ray spectrometers. The present paper reports on the upgraded version of EUCLIDES, that is presently coupled to the new GALILEO -ray spectrometer, installed at the Laboratori Nazionali di Legnaro, INFN. The design, characteristics and performance of the EUCLIDES array are presented and discussed.