Production of very neutron-rich nuclei with a 76Ge beam

TL;DR

This study measured production cross sections of neutron-rich nuclei resulting from 76Ge beam fragmentation at 132 MeV/u, revealing new isotopes and using a novel target variation method for momentum distribution analysis.

Contribution

It introduces a new experimental approach of varying target thickness to scan momentum distributions and reports the discovery of 15 previously unobserved neutron-rich isotopes.

Findings

Identified 15 new neutron-rich isotopes of elements 17 to 25.

Measured production cross sections for a wide range of neutron-rich nuclei.

Observed anomalously large production cross sections near 58Ca.

Abstract

Production cross sections for neutron-rich nuclei from the fragmentation of a 76Ge beam at 132 MeV/u were measured. The longitudinal momentum distributions of 34 neutron-rich isotopes of elements 13 <= Z <= 27 were scanned using a novel experimental approach of varying the target thickness. Production cross sections with beryllium and tungsten targets were determined for a large number of nuclei including 15 isotopes first observed in this work. These are the most neutron-rich nuclides of the elements 17 <= Z <= 25 (50Cl, 53Ar, 55,56K, 57,58Ca, 59,60,61Sc, 62,63Ti, 65,66V, 68Cr,70Mn). A one-body Qg systematics is used to describe the production cross sections based on thermal evaporation from excited prefragments. Some of the fragments near 58Ca show anomalously large production cross sections.