Measurement of the neutron capture cross-section of 236U

Proposal: Measurement of the neutron capture cross-section of 236UPreprin

Measurement of the 240,242Pu(n,f) cross section at the CERN n_TOF facility

Knowledge of neutron cross sections of various plutonium isotopes and other minor actinides is crucial for the design of advanced nuclear systems. The 240, 242Pu(n,f) cross sections were measured at the CERN n_TOF facility, taking advantage of the wide energy range (from thermal to GeV) and the high instantaneous flux of the neutron beam. In this work, preliminary results for 242Pu are presented along with a theoretical cross section calculation performed with the EMPIRE code.Postprint (published version

First results of the new n_TOF spallation target commissioning

The Neutron Time of Flight facility n_TOF located at CERN started to take data in 2001 . Due to an increase of radioactivity released in the cooling water the experiment was stopped by end of 2004 . In 2008 a new spallation target has been installed . In 2009 the collaboration has performed the full commissioning of the facility, consisting in the determination of the fluence, the beam profile, and the energy resolution of the neutron beam. After a brief description of the new target assembly, very preliminary results concerning the shape of the neutron fluence and its absolute value will be given. Measurements of the neutron beam profile will also be shown.Postprint (published version

Neutron beam imaging with micromegas detectors in combination with neutron time-of-flight at the n_tof facility at CERN

A bulk micromegas detector with the anode segmented in 2 orthogonal directions and equipped with a neutron/charged particle converter is employed at the neutron time-of-light (nTOF) facility at CERN to determine the incident neutron beam profile and beam interception factor as a function of the neutron energy determined by the time of flight. Discrepancies between experimental results and simulations in the values of the beam interception factor range up to 12 % and are to be ascribed to a defect in the mesh of the bulk. Nevertheless the detector proved to be really useful for checking the alignment of the neutron beam optics of the facility. Measurements with a new pixelized bulk detector for the determination of the beam interception factor are forseen before the end of 2012Postprint (published version

Study of the photon strength function of 152SM in resonance neutron capture at n-TOF

The Photon Strength Function of 152Sm has been investigated at nTOF by studying the ¿-ray spectra from resonance neutron capture of 151Sm. The experimental apparatus consisted of two C6D6 liquid scintillator detectors. The measured spectra were compared with the predictions of the DICEBOX code, for different assumptions on the Photon Stregth Functions and on the Nuclear Level Density. For a meaningful comparison, the model calculations were filtered through a detailed software replica of the experimental apparatus, performed by means of three different Monte Carlo simulations. Preliminary results indicate that a reasonable reproduction of the experimental ¿-ray spectrum is obtained by postulating the presence of a Scissors Resonance. Some hints on the most suitable models, developed in the most recent studies of the Photon Strength Functions and Nuclear Level Density, are also obtained. © 2007 Sissa Medialab Srl. All rights reserved.Postprint (published version

Integral cross section measurement of the12C(n,p)12B reaction

The integral cross section of the12C(n, p)12B reaction was measured at the neutron time of flight facility nTOF at CERN, from the reaction threshold at 13.6 MeV up to 10 GeV, by means of the combined activation and a timeofflight technique. The integral result is expressed as the number of12B nuclei produced per single pulse of the neutron beam. A simple integral expression is given for calculating the number of produced12B nuclei from any given evaluated cross section and/or model prediction. © 2015, CERN. All rights reserved.Postprint (author's final draft

Measurement of the240Pu(n,f) cross-section at the CERN n-TOF facility: First results from EAR-2

The accurate knowledge of neutron cross-sections of a variety of plutonium isotopes and other minor actinides, such as neptunium, americium and curium, is crucial for feasibility and performance studies of advanced nuclear systems (Generation-IV reactors, Accelerator Driven Systems). In this context, the240Pu(n,f) cross-section was measured with the time-of-flight technique at the CERN n-TOF facility at incident neutron energies ranging from thermal to several MeV. The present measurement is the first to have been performed at n-TOF's newly commissioned Experimental Area II (EAR-2), which is located at the end of an 18 m neutron beam-line and features a neutron fluence that is 25-30 times higher with respect to the existing 185 m flight-path (EAR-1), as well as stronger suppression of sample-induced backgrounds, due to the shorter times-of-flight involved. Preliminary results are presented. © 2015, CERN. All rights reserved.Postprint (published version

The CERN n_TOF facility: a unique tool for nuclear data measurement

The study of the resonant structures in neutron-nucleus cross-sections, and therefore of the compoundnucleus reaction mechanism, requires spectroscopic measurements to determine with high accuracy the energy of the neutron interacting with the material under study. To this purpose, the neutron time-of-flight facility n_TOF has been operating since 2001 at CERN. Its characteristics, such as the high intensity instantaneous neutron flux, the wide energy range from thermal to few GeV, and the very good energy resolution, are perfectly suited to perform highquality measurements of neutron-induced reaction cross sections. The precise and accurate knowledge of these cross sections plays a fundamental role in nuclear technologies, nuclear astrophysics and nuclear physics. Two different measuring stations are available at the n_TOF facility, called EAR1 and EAR2, with different characteristics of intensity of the neutron flux and energy resolution. These experimental areas, combined with advanced detection systems lead to a great flexibility in performing challenging measurement of high precision and accuracy, and allow the investigation isotopes with very low cross sections, or available only in small quantities, or with very high specific activity. The characteristics and performances of the two experimental areas of the n_TOF facility will be presented, together with the most important measurements performed to date and their physics case. In addition, the significant upcoming measurements will be introduced.Postprint (published version

A compact fission detector for fission-tagging neutron capture experiments with radioactive fissile isotopes

In the measurement of neutron capture cross-sections of fissile isotopes, the fission channel is a source of background which can be removed efficiently using the so-called fission-tagging or fission-veto technique. For this purpose a new compact and fast fission chamber has been developed. The design criteria and technical description of the chamber are given within the context of a measurement of the 233U(n,y) cross-section at the n_TOF facility at CERN, where it was coupled to the n_TOF Total Absorption Calorimeter. For this measurement the fission detector was optimized for time resolution, minimization of material in the neutron beam and for alpha-fission discrimination. The performance of the fission chamber and its application as a fission tagging detector are discussed.This work was partially supported by the French NEEDS/NACRE Project and by the European Commission within HORIZON2020 via the EURATOM Project EUFRAT

High accuracy, high resolution 235U(n,f) cross section from n_TOF (CERN) from 18 meV to 10 keV

he version of record os available online at: http://dx.doi.org/10.1140/epja/s10050-022-00779-7U(n,f) cross section was measured in a wide energy range (18 meV–170 keV) at the n_TOF facility at CERN, relative to 6Li(n,t) and 10B(n,a) standard reactions, with high resolution and accuracy, with a setup based on a stack of six samples and six silicon detectors placed in the neutron beam. In this paper we report on the results in the region between 18 meV and 10 keV neutron energy. A resonance analysis has been performed up to 200 eV, with the code SAMMY. The resulting fission kernels are compared with the ones extracted on the basis of the resonance parameters of the most recent major evaluated data libraries. A comparison of the n_TOF data with the evaluated cross sections is also performed from thermal to 10 keV neutron energy for the energy-averaged cross section in energy groups of suitably chosen width. A good agreement, within 0.5%, is found on average between the new results and the latest evaluated data files ENDF/B-VIII.0 and JEFF-3.3, as well as with respect to the broad group average fission cross section established in the framework of the standard working group of IAEA (the so-called reference file). However, some discrepancies, of up to 4%, are still present in some specific energy regions. The new dataset here presented, characterized by a unique combination of high resolution and accuracy, low background and wide energy range, can help to improve the evaluations from the Resolved Resonance Region up to 10 keV, also reducing the uncertainties that affect this region.Peer ReviewedAquest article està escrit per 130 autors/autores: Simone Amaducci, Nicola Colonna, Luigi Cosentino, Sergio Cristallo, Paolo Finocchiaro, Milan Krtiˇcka, Cristian Massimi, Mario Mastromarco, Annamaria Mazzone, Alberto Mengoni, Stanislav Valenta, Oliver Aberle, Victor Alcayne, Józef Andrzejewski, Laurent Audouin, Victor Babiano-Suarez, Michael Bacak, Massimo Barbagallo, Samuel Bennett, Eric Berthoumieux, Jon Billowes, Damir Bosnar, Adam Brown, Maurizio Busso, Manuel Caamaño, Luis Caballero-Ontanaya, Francisco Calviño, Marco Calviani, Daniel Cano-Ott, Adria Casanovas, Francesco Cerutti, Enrico Chiaveri, Guillem Cortés, Miguel Cortés-Giraldo, Lucia-Anna Damone, Paul-John Davies, Maria Diakaki, Mirco Dietz, Cesar Domingo-Pardo, Rugard Dressler, Quentin Ducasse, Emmeric Dupont, Ignacio Durán, Zinovia Eleme, Beatriz Fernández-Domínguez, Alfredo Ferrari, Valter Furman, Kathrin Göbel, Ruchi Garg, Aleksandra Gawlik, Simone Gilardoni, Isabel Gonçalves, Enrique González-Romero, Carlos Guerrero, Frank Gunsing, Hideo Harada, Stephan Heinitz, Jan Heyse, David Jenkins, Arnd Junghans, Franz Käppeler, Yacine Kadi, Atsushi Kimura, Ingrid Knapova, Michael Kokkoris, Yuri Kopatch, Deniz Kurtulgil, Ion Ladarescu, Claudia Lederer-Woods, Helmut Leeb, Jorge Lerendegui-Marco, Sarah-Jane Lonsdale, Daniela Macina, Alice Manna, Trinitario Martínez, Alessandro Masi, Pierfrancesco Mastinu, Emilio-Andrea Maugeri, Emilio Mendoza, Veatriki Michalopoulou, Paolo Milazzo, Federica Mingrone, Javier Moreno-Soto, Agatino Musumarra, Alexandru Negret, Francisco Ogállar, Andreea Oprea, Nikolas Patronis, Andreas Pavlik, Jarosław Perkowski, Luciano Piersanti, Cristina Petrone, Elisa Pirovano, Ignacio Porras, Javier Praena, José-Manuel Quesada, Diego Ramos-Doval, Thomas Rauscher, René Reifarth, Dimitri Rochman, Carlo Rubbia, Marta Sabaté-Gilarte, Alok Saxena, Peter Schillebeeckx, DorotheaPostprint (published version