Discovery and cross-section measurement of neutron-rich isotopes in the element range from neodymium to platinum with the FRS

Abstract

Using the high-resolution performance of the fragment separator FRS at GSI we have discovered 60 new neutron-rich isotopes in the atomic number range of 60 ⩽ Z ⩽ 78. The new isotopes were unambiguously identified in reactions with a ²³⁸U beam impinging on a Be target at 1 GeV/nucleon. The production cross-section for the new isotopes have been measured down to the pico-barn level and compared with predictions of different model calculations. For elements above hafnium fragmentation is the dominant reaction mechanism which creates the new isotopes, whereas fission plays a dominant role for the production of the new isotopes up to thulium.