Light and heavy transfer products inXe136+U238multinucleon transfer reactions

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 136 Xe + 238 U have been measured in a high-resolution γ -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 γ -ray spectroscopy is feasible for few-neutron transfer channels in U and the −2p channel populating Th isotopes.

Spectroscopy of the neutron-rich actinide nucleusU240following multinucleon-transfer reactions

“…[17] for the CLARA experiment and in Refs. [21,22] for the AGATA experiment. The measured quantities allow univocal identification and determination of the velocity vector for the individual lighter MNT reaction products.…”

“…Most of the produced actinide nuclei are excited up to an energy higher than the neutron-separation energy which enables neutron evaporation. Nonetheless, a gate on the TKEL value is helpful to constrain the excitation energy of the nuclei and to suppress fission events [21].…”

“…It is divided into three regions. The γ -ray spectrum corresponding to TKEL region 1 (blue [gray, bottom]) shows a constant structureless background caused by fission [21]. The γ -ray spectrum of region 2 (red [gray, middle]) shows high background contributions and indications of overlapping peaks.…”

“…As introduced in Ref. [21], the time-of-flight difference ( ToF) between the two reaction products was measured at the entrance detector of PRISMA and the DANTE detector inside the scattering chamber. A 2D histogram in which ToF and the calculated TKEL are correlated is shown in Fig.…”

“…13 for 240 U in Ref. [21]) in order to demonstrate the selectivity and quality of the MNT reaction; however, no results of the following detailed analysis were given. Different isotopes, namely 238−240 U, contribute to the γ -ray spectrum of 240 U.…”