Activities on Nuclear Data Measurements at Pohang Neutron Facility

摘要

We report the activities of the Pohang Neutron Facility which consists of an electron linear accelerator, a water-cooled Ta target, and a 12-m time-of-flight path. It has been equipped with a four-position sample changer controlled remotely by a CAMAC data acquisition system, which allows simultaneous accumulation of the neutron time of flight spectra from 4 different detectors. It can be possible to measure the neutron total cross-sections in the neutron energy range from 0.1 eV to few hundreds eV by using the neutron time-of-flight method. A 6LiZnS(Ag) glass scintillator was used as a neutron detector. The neutron flight path from the water-cooled Ta target to the neutron detector was 12.1 m. The background level was determined by using notch-filters of Co, In, Ta, and Cd sheets. In order to reduce the gamma rays from bremsstrahlung and those from neutron capture, we employed a neutron-gamma separation system based on their different pulse shapes. The present measurements of several samples (Ta, Mo) are in general agreement with the evaluated data in ENDF/B-VI. We measured the thermal neutron capture cross-sections and the resonance integrals of the ~(MWMW19o r ero(eacn(ct8itno,iony89n, a 7)bnyd~67) t~h(e (a~)c(t)ivation method using the 197Au(n,y) 198Au monitor reaction as a single comparator. We also report the isomeric yield ratios for the 44m,gSc isomeric pairs produced from four different photonuclear reactions using the activation method.