Measurement of the neutron-induced fission cross-section of 241Am at the time-of-flight facility n_TOF

F Belloni ,M Dahlfors,M Krtička,G Rudolf,S Marrone,L Tavora,C Rubbia,E Jericha,L Sarchiapone,C Paradela,J Andrzejewski,W Dridi,I Dillmann,C Lamboudis,J Salgado,E Chiaveri,L Perrot,P Vaz,C Eleftheriadis,G Vannini,F Gunsing,E Berthoumieux,K Wisshak,N Patronis,U Abbondanno,R Vlastou,F Neves,H Álvarez,S Andriamonje,P Cennini,C Pretel,A Lindote,L Audouin,H Leeb,M Rosetti,D Karadimos,M C Vincente,A Plukis,I Savvidis,F Bečvář,V Chepel,J Marganiec,P Rullhusen,A Poch,A Goverdovski,E Kossionides,Y Kadi,M Kerveno,F Calviño,F Gramegna,D Karamanis,G Aerts,C Carrapiço,F Käppeler,P Pavlopoulos,M Mosconi,A Pavlik,R Terlizzi,G Tagliente,Marco T Pigni ,R C Haight ,M Meaze ,I F Gonçalves ,C Guerrero ,D Villamarı́n ,F Álvarez‐Velarde ,T Martínez ,A Ferrari ,A Herrera-Martı́nez ,V Vlachoudis ,A Mengoni ,C Stéphan ,L Tassan‐Got ,P Baumann ,S David ,S Lukić ,C Moreau ,Keiko Fujii ,Paolo Milazzo ,R Capote ,W Furman ,A Plompen ,F Voß ,M Heil ,R Plag ,S Walter ,Brian J Haas ,M Calviani ,P Mastinu ,R Reifarth ,Alessandro Ventura ,M Barbagallo ,N Colonna ,C Papadopoulos ,P Koehler ,G Badurek ,H Oberhummer ,M Igashira ,J Praena ,M Lozano ,G Cortés ,T Rauscher ,C Massimi ,I Lopes ,R Ferreira‐Marques ,C Papachristodoulou ,A Couture ,James W Cox ,M Wiescher ,S O’brien ,D Cano‐Ott ,E González‐Romero ,I Durán ,M Embid‐Segura ,C Domingo‐Pardo ,J L Taín ,C Santos ,J M Quesada ,D Tarrío

doi:10.1140/epja/i2013-13002-3

Abstract

The neutron-induced fission cross-section of 241Am has been measured relative to the standard fission cross-section of 235U between 0.5 and 20MeV. The experiment was performed at the CERN n_TOF facility. Fission fragments were detected by a fast ionization chamber by discriminating against the \(\alpha\)-particles from the high radioactivity of the samples. The high instantaneous neutron flux and the low background of the n_TOF facility enabled us to obtain uncertainties of \( \approx\) 5%. With the present results it was possible to resolve discrepancies between previous data sets and to confirm current evaluations, thus providing important information for design studies of future reactors with improved fuel burn-up.

Highlights

The growth in world energy consumption implies pressing problems that humanity has to face in the decades
The data from the digitizers were reduced by a zero-suppression routine and the remaining signals were stored for off-line analysis of the deposited energy in the detectors and the respective time of flight (TOF)
Major difficulties in data analysis were related to energy losses in the samples and to pile-up signals produced by the high background of α-particles from the decay of 241Am, which were investigated by realistic FLUKA [20] Monte Carlo simulations of the detector response [21]

Summary

Introduction

The growth in world energy consumption implies pressing problems that humanity has to face in the decades. The evaluated cross-sections in the data libraries suffer from the limited experimental accuracy as well In view of this unsatisfactory situation, an extensive measurement campaign for reducing the uncertainties of the fission cross-section of 241Am has been carried out at the neutron time-of-flight facility n TOF at CERN, which is unique for its very high instantaneous neutron flux and extremely low duty cycle. These features are instrumental for reducing the α background from the activity of the sample.

The experimental set-up

Data analysis

Results

Comparison with previous measurements

Evaluated data and EMPIRE calculations

Conclusions