Accurate Measurement of the Cross Section of ⁹²Mo (n,p)92mNb Reaction Induced by 14.1MeV Neutrons

Molybdenum, as an important structural material, has been widely used in nuclear energy systems. Therefore, the high-precision neutron reaction cross-section of molybdenum is of great significance for the development of nuclear energy systems. This paper used activation and relative measurement methods to measure the reaction cross section of ⁹²Mo (n,p)92mNb. The sample was irradiated at a 90 degree angle using nanosecond pulse neutron generator (CPNG) from the China Institute of Atomic Energy. After a period of cooling time, the activity of the activated product nuclei of the irradiated sample was measured using a high-purity germanium detector, and the reaction cross section and correction factor were calculated,conventional correction factors include neutron fluence fluctuation、cascade、self-absorption、geometry and scattered-neutron corrections. Finally, the reaction cross section of ⁹²Mo (n,p)92mNb at 14.1 MeV energy point was obtained. To reduce the uncertainty of experimental measurements.This work proposes a strategy in which the product to be measured and the monitoring product are the same nuclide, effectively eliminated uncertainties introduced by the half-life and decay branch ratio of the product nucleus, gamma detection efficiency, and beam fluctuations during irradiation, and effectively improved measurement accuracy, obtained the highest precision experimental data so far. As this experiment aims to minimize the overall measurement uncertainty, stringent requirements were imposed on both the sample mass-thickness and the operating environment. The mass and thickness of each sample were therefore determined by five independent measurements with a 0.1 mg-precision analytical balance and a vernier caliper, respectively, and the mean values were adopted. After the experiment, the measured data were carefully compared and analyzed with other datasets, The value of cross-section is not significantly different from others in the database and is located within the error range, which further verifies the feasibility of this method, providing high-precision experimental support for the nuclear-data evaluation of this reaction channel. The paper is organized as follows:At first, the experimental method is introduced; then, the experiment of the ⁹²Mo (n,p)92mNb cross-section is described in detail; finally, the results are presented and analyzed, and compared with values available in nuclear databases. All previous studies cited employed the activation technique, reporting relative uncertainties in the range 3.5%- 10.9%. By contrast, the present experiment achieves an uncertainty below 2%, thereby delivering high-accuracy data for nuclear databases.