https://doi.org/10.1140/epja/s10050-025-01727-x
Regular Article - Experimental Physics
Characterisation of the neutron beam in the n_TOF-EAR2 experimental area at CERN following the spallation target upgrade
1
Universidad de Sevilla, Seville, Spain
2
European Organization for Nuclear Research (CERN), Geneva, Switzerland
3
Instituto de Física Corpuscular, CSIC-Universidad de Valencia, Valencia, Spain
4
Istituto Nazionale di Fisica Nucleare, Sezione di Bologna, Bologna, Italy
5
Dipartimento di Fisica e Astronomia, Università di Bologna, Bologna, Italy
6
INFN Laboratori Nazionali del Sud, Catania, Italy
7
INFN Laboratori Nazionali di Legnaro, Legnaro, Italy
8
Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain
9
University of Granada, Granada, Spain
10
University of Ioannina, Ioannina, Greece
11
Istituto Nazionale di Fisica Nucleare, Sezione di Pavia, Pavia, Italy
12
Department of Physics, University of Pavia, Pavia, Italy
13
University of Lodz, Lodz, Poland
14
University of Manchester, Manchester, UK
15
CEA Irfu, Université Paris-Saclay, 91191, Gif-sur-Yvette, France
16
Department of Physics, Faculty of Science, University of Zagreb, Zagreb, Croatia
17
Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Perugia, Italy
18
Dipartimento di Fisica e Geologia, Università di Perugia, Perugia, Italy
19
University of Santiago de Compostela, Santiago de Compostela, Spain
20
Universitat Politècnica de Catalunya, Catalunya, Spain
21
Agenzia nazionale per le nuove tecnologie (ENEA), Rome, Italy
22
Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Trieste, Italy
23
Department of Physics, University of Trieste, Trieste, Italy
24
National Technical University of Athens, Athens, Greece
25
Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Turin, Italy
26
Department of Physics, University of Torino, Turin, Italy
27
Istituto Nazionale di Fisica Nucleare, Sezione di Bari, Bari, Italy
28
Istituto Nazionale di Astrofisica-Osservatorio Astronomico di Teramo, Teramo, Italy
29
Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany
30
Paul Scherrer Institut (PSI), Villigen, Switzerland
31
Istituto Nazionale di Fisica Nucleare, Sezione di Roma1, Rome, Italy
32
Affiliated with an Institute Covered by a Cooperation Agreement with CERN, Geneva, Switzerland
33
European Commission, Joint Research Centre (JRC), Geel, Belgium
34
University of York, York, UK
35
TU Wien, Atominstitut, Stadionallee 2, 1020, Vienna, Austria
36
Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
37
Tokyo Institute of Technology, Tokyo, Japan
38
Charles University, Prague, Czech Republic
39
Goethe University Frankfurt, Frankfurt, Germany
40
School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
41
Institut de Physique Nucléaire, CNRS-IN2P3, Univ. Paris-Sud, Paris, France
42
Dipartimento Interateneo di Fisica, Università degli Studi di Bari, Bari, Italy
43
Consiglio Nazionale delle Ricerche, Bari, Bari, Italy
44
INFN Laboratori Nazionali di Frascati, Frascati, Italy
45
Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Catania, Italy
46
Department of Physics and Astronomy, University of Catania, Catania, Italy
47
Horia Hulubei National Institute of Physics and Nuclear Engineering, Măgurele, Romania
48
Uppsala University, Uppsala, Sweden
49
Department of Physics, University of Basel, Basel, Switzerland
50
Instituto Superior Técnico, Lisbon, Portugal
51
Australian National University, Canberra, Australia
52
Particle Physics Department, STFC-Rutherford Appleton Laboratory, OX11 0QX, Harwell, Didcot, UK
a
marta.sabate.gilarte@cern.ch
Received:
6
May
2025
Accepted:
23
October
2025
Published online:
8
December
2025
The n_TOF facility at CERN has undergone a major upgrade after the installation of a new spallation target, designed to improve the performance of both neutron beamlines at the experimental areas 1 and 2 (EAR1 and EAR2) and the commissioning of a new experimental area (NEAR). Due to improved coupling of the spallation target with the EAR2 beamline, the upgrade resulted in a significantly increased neutron flux and improved neutron energy resolution. This paper presents the results of the commissioning phase that followed to characterise the EAR2 neutron beamline and validate the FLUKA Monte Carlo simulations of the facility. The main characteristics of the neutron beam, namely the neutron flux, spatial profile and energy resolution, are evaluated and compared to the previous target. The neutron flux presents a general increase of 20% below 1 eV, 40% between 1 eV and 100 keV and 50% between 100 keV and 10 MeV. The measured width of the beam profile was 3 cm full width at half maximum (FWHM) at the reference position for neutron capture measurements. The energy resolution with the new spallation target shows a significant improvement compared to the previous one. Moreover, FLUKA Monte Carlo simulations present a good agreement with the measured neutron flux and profile within uncertainties, and a remarkable reproduction of the energy resolution.
© Crown 2025
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