Measurement of the 72Ge(n,γ) cross section over a wide neutron energy range at the CERN n_TOF facility

M Dietz,N Colonna,C Massimi,A Wallner,P Vaz,V Furman,S Valenta,A Saxena,D Radeck,R Cardella,D Kurtulgil,A Musumarra,D Kahl,F Bečvář,J Marganiec,N V Sosnin,M Sabaté-Gilarte,G Vannini,U Battino,J Billowes,F Cerutti,E Griesmayer,P Kavrigin,L Audouin,A Mazzone,T Glodariu,D G Jenkins,E Jericha,I Durán,L A Damone,P Žugec,A Casanovas,F Käppeler,G Tagliente,A Masi,N Kivel,F Gunsing,R Vlastou,A Manna,M Mastromarco,V Variale,J Andrzejewski,E Berthoumieux,F Mingrone,O Aberle,M Kokkoris,J Heyse,A Gawlik,V Vlachoudis,M Calviani,E Leal-Cidoncha,J Lerendegui-Marco,P Sedyshev,S Heinitz,H Leeb,Y H Chen,G Cortés,A Pavlik,J Perkowski,T Wright,M Krtička,S Amaducci,P J Woods,A Tattersall,J Balibrea,Y Kadi,A Oprea,D Macina,C Rubbia,D Schumann,A Kalamara,M Bacak,E Mendoza,E Chiaveri,E A Maugeri,A Stamatopoulos,F Calviño,J M Quesada,A Negret,I F Gonçalves,S Lo Meo,M Caamaño,S J Lonsdale,A Ferrari,N Patronis,E Dupont,L Cosentino,K Göbel,R Reifarth,J A Ryan,E González‐Romero ,Μ Diakaki ,Paolo Milazzo ,A Ventura,Hideo Harada ,L Tassan‐Got ,J L Taı́n ,C Domingo‐Pardo ,D Bosnar,A R García ,S Gilardoni,B Fernández–Domínguez ,S Warren,A Brown,R Nolte,C Guerrero,C Weiß ,A Mengoni,C Lederer-Woods,R Dressler,D Cano‐Ott ,M A Cortés‐Giraldo ,P Mastinu,P Finocchiaro,A Tarifeño-Saldivia,J Praena,I Porras,P Schillebeeckx,M Barbagallo,Andrew Smith ,Paulo Ricardo Araújo Ferreira ,T Martínez,T Rauscher,Akira Kimura

doi:10.1103/physrevc.103.045809

Abstract

The Ge72(n,γ) cross section was measured for neutron energies up to 300keV at the neutron time-of-flight facility n_TOF (CERN), Geneva, for the first time covering energies relevant to heavy-element synthesis in stars. The measurement was performed at the high-resolution beamline EAR-1, using an isotopically enriched GeO272 sample. The prompt capture γ rays were detected with four liquid scintillation detectors, optimized for low neutron sensitivity. We determined resonance capture kernels up to a neutron energy of 43keV, and averaged cross sections from 43 to 300keV. Maxwellian-averaged cross section values were calculated from kT=5 to 100keV, with uncertainties between 3.2% and 7.1%. The new results significantly reduce uncertainties of abundances produced in the slow neutron capture process in massive stars.

Highlights

The chemical elements heavier than Fe are predominantly produced by neutron capture processes in stars and stellar explosions
The s process consists of three components: the main component occurs during H and He shell burning phases in low-mass asymptotic giant branch (AGB) stars, at temperatures of about 0.09 and 0.3 GK, respectively (1 GK = 109 K) [4]
The high neutron exposures reached allow the establishment of a reaction flow equilibrium of the form N × MACS ≈ const, where N is the abundance produced in the s process, and MACS is the Maxwellian-averaged cross section, i.e., the neutron capture cross section averaged over the stellar neutron velocity distribution

Summary

Published by the American Physical Society

The 72Ge(n, γ ) cross section was measured for neutron energies up to 300 keV at the neutron time-of-flight facility n_TOF (CERN), Geneva, for the first time covering energies relevant to heavy-element synthesis in stars. We determined resonance capture kernels up to a neutron energy of 43 keV, and averaged cross sections from 43 to 300 keV. Maxwellian-averaged cross section values were calculated from kT = 5 to 100 keV, with uncertainties between 3.2% and 7.1%. The new results significantly reduce uncertainties of abundances produced in the slow neutron capture process in massive stars

INTRODUCTION

DATA ANALYSIS AND RESULTS

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Data SAMMY Fit ENDF

This work