Thermal Cross-Section of Naturally Occurring Tantalum

Neutron induced thermal cross-section of naturally occurring Tantalum (Ta) has been analyzed by using four different Ta samples with thickness 4.0, 2.0, 1.0 and 0.5 mm (respectively equivalent to 0.0224, 0.0111, 0.0055, and 0.0025 atoms/barn) at the Pohang Neutron Facility, Republic of Korea. The PNF consists of a 100 MeV electron linear accelerator (LINAC), a water cooled Tantalum (Ta) target, 12.06 m TOF path length, four position automatic sample changer controlled remotely by the CAMAC data acquisitions systems, and a 6LiZnS(Ag) inorganic scintillator as a neutron detector. The distance from the water cooled Ta target to the sample changer is 5.4 m. To reduce the gamma flash originated from the neutron target we have employed a neutron-gamma separation system based on their different pulse shape. The samples were highly pure (~99.9 %). In order to estimate the background and also to calibrate the energy we used notch filter of Cobalt (Co), Indium (In), and Cadmium (Cd) that has a large resonance peaks within our analyzed energy region. The area of the each samples of notch filter was 100 × 100 mm, and the thickness were 0.5 mm for Co and Cd; and 0.2 mm for the In. To get more events, experiments were done around 110 hours. The unwanted events were deleted from the real events by fitting with black resonances events of notch filter. The weighted mean of the measured thermal total neutron cross-section of Ta was compared with the existing experimental as well as evaluated nuclear data files.