Characterisation of the neutron beam in the n_TOF-EAR2 experimental area at CERN following the spallation target upgrade

Žugec, P., Wright, T., Woods, P. J., Wallner, A., Vlastou, R., Vescovi, D., Vaz, P., Variale, V., Valenta, S., Urlass, S., Torres-Sánchez, P., Terranova, N., Tarrío, D., Tarifeño-Saldivia, A., Tagliente, G., Spelta, M., Sosnin, N. V., Smith, A. G., Sekhar, A., Schumann, D., Schillebeeckx, P., Sánchez, A., Rubbia, C., Romano, F., Romanets, Y., Rochman, D., Reifarth, R., Rauscher, T., Protti, N., Praena, J., Porras, I., Pomp, S., Pirovano, E., Piersanti, L., Petrone, C., Perkowski, J., Pellegriti, M. G., Pérez-Maroto, P., Oprea, A., Negret, A., Musumarra, A., Murtas, F., Mucciola, R., Milazzo, P. M., Michalopoulou, V., Mengoni, A., Mendoza, E., Mazzone, A., Maugeri, E. A. and Cescutti, G. (2025) Characterisation of the neutron beam in the n_TOF-EAR2 experimental area at CERN following the spallation target upgrade. European Physical Journal A, 61 (227): 277. ISSN 1434-6001

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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.

Item Type	Article
Identification Number	10.1140/epja/s10050-025-01727-x
Additional information	© Crown 2025. This article is licensed under a Creative Commons Attribution 4.0 International License, To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Keywords	nuclear and high energy physics
Date Deposited	16 Jan 2026 14:12
Last Modified	16 Jan 2026 14:12