Activation cross section and isomeric cross section ratio for the 76Ge(n,2n)75m,gGe process

Junhua Luo,Xinxing Wang,Li Jiang

doi:10.1140/epja/i2018-12501-y

Abstract

.We measured neutron-induced reaction cross sections for the 76Ge(n,2n)75m,gGe reactions and their isomeric cross section ratios sigma_{m}/sigma_{g} at three neutron energies between 13 and 15MeV by an activation and off-line gamma-ray spectrometric technique using the K-400 Neutron Generator at the Chinese Academy of Engineering Physics (CAEP). Ge samples and Nb monitor foils were activated together to determine the reaction cross section and the incident neutron flux. The monoenergetic neutron beams were formed via the 3H(d,n)4He reaction. The pure cross section of the ground state was derived from the absolute cross section of the metastable state and the residual nuclear decay analysis. The cross sections were also calculated using the nuclear model code TALYS-1.8 with different level density options at neutron energies varying from the reaction threshold to 20MeV. Results are discussed and compared with the corresponding literature data.

Highlights

We aimed to measure the pure ground state cross section σg directly by means of the analysis methods of residual nuclear decay [15,16,17] and to compare the experimental results to those obtained by the statistical model calculation
Between 13 and 15 MeV, the Talys-1.8 calculations with ldmodels 1–6 are lower than all the results of papers in the literature [7,9,14], but the TALYS-1.8 calculations with ldmodel 1 agree very well with our data, whilst the results by Casanova and Sanchez [7], Vanska and Rieppo [9], and Attar et al [14] are about 60–90% higher than our data and TALYS-1.8 calculations
The results were compared with previous experimental results reported in the literature and theoretical nuclear model calculations computed using TALYS-1.8

Summary

Introduction

We aimed to measure the pure ground state cross section σg directly by means of the analysis methods of residual nuclear decay [15,16,17] and to compare the experimental results to those obtained by the statistical model calculation. About 0.1 and 0.19 cm in thickness and 20 mm in diameter, were formed by pressing approximately 1.7 and 3.2 g of Ge (99.99% pure) powder (natural isotopic composition) at 980 MPa to form a pellet. The samples were irradiated near the target and sandwiched between two Nb foils (99.99% pure, 0.12 mm thick) with the same diameter which were used to monitor the neutron fluence via the 93Nb(n, 2n)92mNb reaction.

Objectives

Methods

Findings

Conclusion