Measurements of cross-sections of (n,xn) threshold reactions in various materials

J Vrzalová,M Suchopár,O Svoboda,V Wagner,A Kugler

doi:10.1051/epjconf/20122110007

Abstract

Experimental cross-section data for (n,xn) reactions with x higher than four and neutron energies over ~30 MeV are very scarce. We performed seven successful (n,xn) cross-section measurements in two campaigns exploiting the quasi-monoenergetic neutron source at The Svedberg Laboratory in Uppsala, Sweden. Neutron energies from the 7 Li(p,n) 7 Be based source were in the region 22 to 94 MeV. We carried out additional five irradiations with neutron energies from 17 up to 34 MeV using the quasi-monoenergetic neutron source of the Nuclear Physics Institute in Řež. We have irradiated Al, Au, Bi, I, In, Ta and Y materials in the form of thin foils. We observed good agreement with the few existing experimental data about corresponding cross-sections in EXFOR database and also with the calculations performed in deterministic code TALYS.

Highlights

As members of international collaboration “Energy and Transmutation of Radioactive Waste” we routinely use (n,xn) threshold reactions in various materials to measure high energy neutron flux from spallation reactions [1]
We observed good agreement with the few existing experimental data about corresponding cross-sections in EXFOR database and with the calculations performed in deterministic code TALYS
Cross-sections of neutron threshold reactions in Al, Au, Bi, I, In, and Ta were studied in the energy region from 17 to 94 MeV by the means of activation analysis and gamma spectroscopy

Summary

Introduction

As members of international collaboration “Energy and Transmutation of Radioactive Waste” we routinely use (n,xn) threshold reactions in various materials to measure high energy neutron flux from spallation reactions [1]. The detailed measurements of the neutron reactions cross-sections in the energy range of interest in above mentioned transmutation studies are still missing. A high energy neutron source with well known monoenergetic spectrum is needed for cross-section studies. This source must be in addition highly intensive for experiments done by the means of activation method. The cyclotron at TSL Uppsala has the energy range from 20 MeV to 180 MeV for protons and the maximum neutron flux density 105 cm-2s-1 [2]. Energy range of neutron source at NPI of ASCR at Řež is between 10 and 37 MeV for protons and the maximum neutron flux density is 108 cm-2s-1 [3]. Transport from the irradiation hall to the spectrometer took approximately two minutes in Uppsala, ten minutes in Řež

DEIMOS32

The total yield and calculation of cross-section

Background subtraction

Summary