Regular Article

Covariance analysis for total neutron cross sections based on a microscopic optical   model potential

China Nuclear Data Center, China Institute of Atomic Energy, P.O. Box 275(41), Beijing 102413, P.R. China

^* e-mail: xrr-001@163.com

Received: 7 December 2017
Received in final form: 1 March 2018
Accepted: 28 May 2018
Published online: 14 November 2018

Abstract

The deterministic simple least square (LS) approach is employed in the covariance analysis of the total neutron cross section (n,tot) calculated by a microscopic optical potential, CTOM, which is based on a fundamental theory − Dirac Brueckner Hartree Fock. The sensitivity to the CTOM parameters is firstly systematically calculated for 77 stable nuclei in the range ¹²C–²⁰⁸Pb within neutron energy 5–200 MeV. Then, an equivalent covariance of experimental data (EVexp) is constructed to describe the experimental data uncertainties and the systematic difference between experimental data and CTOM calculation. The variance and covariance of EVexp matrix are both evaluated via the Gaussian analysis to the ratios of measured (n,tot) cross sections and the CTOM calculations. In addition, a technique named “selection of effective points (SEP)” is suggested additionally to reduce the influence of the Peelle's Pertinent Puzzle problem in this work.