Benchmark experiment on molybdenum with graphite by using DT neutrons at JAEA/FNS

- A new benchmark experiment on molybdenum was conducted with DT neutron at JAEA/FNS.
- Dosimetry reaction and fission rates were measured in the molybdenum assembly.
- Calculated results with MCNP5 code were compared with the measured ones.
- A problem on the capture cross section data of molybdenum was pointed out.

In our previous benchmark experiment on Mo at JAEA/FNS, we found problems of the (n,2n) and (n,γ) reaction cross sections of Mo in JENDL-4.0 above a few hundred eV. We perform a new benchmark experiment on Mo with a Mo assembly covered with graphite and Li2O blocks in order to validate the nuclear data of Mo in lower energy region than in the previous experiment. Several dosimetry reaction and fission rates are measured and compared with calculated ones with the MCNP5-1.40 code and the recent nuclear data libraries, ENDF/B-VII.1, JEFF-3.2, and JENDL-4.0. It is suggested that the (n,γ) reaction cross section of 95Mo should be larger in the tail region below the large resonance of 45 eV in these nuclear data libraries.