Production cross sections of neutron rich isotopes from a 82Se beam

TL;DR

This study measures production cross sections and momentum distributions of neutron-rich isotopes generated from 82Se beam fragmentation, identifying new isotopes and confirming previous findings about neutron-rich fragment production.

Contribution

First measurement of production cross sections for several neutron-rich isotopes from 82Se fragmentation, including new isotopes of Ti, V, Cr, Mn, and confirmation of enhanced production near Z=20.

Findings

Identified new neutron-rich isotopes of Ti, V, Cr, Mn.

Measured momentum distributions for 122 isotopes.

Confirmed enhanced production of neutron-rich fragments near Z=20.

Abstract

Production cross sections for neutron-rich nuclei from the fragmentation of a 82Se beam at 139 MeV/u were measured. The longitudinal momentum distributions of 122 neutron-rich isotopes of elements $11 \le Z \le 32$ were determined by varying the target thickness. Production cross sections with beryllium and tungsten targets were determined for a large number of nuclei including several isotopes first observed in this work. These are the most neutron-rich nuclides of the elements $22 \le Z \le 25$ (64Ti, 67V, 69Cr, 72Mn). One event was registered consistent with 70Cr, and another one with 75Fe. A one-body Qg systematics is used to describe the production cross sections based on thermal evaporation from excited prefragments. The current results confirm those of our previous experiment with a 76Ge beam: enhanced production cross sections for neutron-rich fragments near Z=20.