Development of a rapid-transit system for precision nuclear physics measurements

Abstract

A Rapid Belt-driven Irradiated Target Transfer System, named RABITTS, was developed for use at the Triangle Universities Nuclear Laboratory. This system allows for cyclic activation with neutron or photon beams, and measurement of reaction products using γ-ray spectroscopy. Both a 1 meter and 10 meter transfer system have been developed with transit times as low as 0.4 and 1.0 s, respectively. The systems are deployed at the tandem accelerator laboratory for use with monoenergetic neutron beams, and at the High-Intensity γ-ray Source facility for activation using photon beams. A detailed characterization of the systems’ performance and sensitivity is presented. In order to produce the highest accuracy cross-section data, a model for calculating corrections to cyclic activation with variable beam flux is developed and presented. We have commissioned these systems by measuring 197mAu, where we report a measured half-life of 7.73±0.05 s and a 197Au(n,n′)197mAu isomer production cross of 628±28 mb at neutron energy En=2.0MeV. In addition, we measured 90mZr, where we report a measured half-life of 799.7±8.0ms and a 90Zr(n,n′)90mZr isomer production cross of 180±12 mb at En=4.6MeV. These measured half-lives are in excellent agreement with the evaluated values and the cross-section measurements are performed at previously unmeasured incident neutron energies.