# Measurement of the 235U(n,f) cross section relative to the 6Li(n,t) and 10B(n,alpha) standards from thermal to 170 keV neutron energy range at n_TOF **Authors:** S. Amaducci, L. Cosentino, M. Barbagallo, N. Colonna, A. Mengoni, C., Massimi, S. Lo Meo, P. Finocchiaro, O. Aberle, J. Andrzejewski, L. Audouin,, M. Bacak, J. Balibrea, F. Be\v{c}v\'a\v{r}, E. Berthoumieux, J. Billowes, D., Bosnar, A. Brown, M. Caama\~no, F. Calvi\~no, M. Calviani, D. Cano-Ott, R., Cardella, A. Casanovas, F. Cerutti, Y. H. Chen, E. Chiaveri, G. Cort\'es, M., A. Cort\'es-Giraldo, L. A. Damone, M. Diakaki, C. Domingo-Pardo, R. Dressler,, E. Dupont, I. Dur\'an, B. Fern\'andez-Dom\'inguez, A. Ferrari, P. Ferreira,, V. Furman, K. G\"obel, A. R. Garc\'ia, A. Gawlik, S. Gilardoni, T. Glodariu,, I. F. Gon\c{c}alves, E. Gonz\'alez-Romero, E. Griesmayer, C. Guerrero, F., Gunsing, H. Harada, S. Heinitz, J. Heyse, D. G. Jenkins, E. Jericha, F., K\"appeler, Y. Kadi, A. Kalamara, P. Kavrigin, A. Kimura, N. Kivel, I., Knapova, M. Kokkoris, M. Krti\v{c}ka, D. Kurtulgil, E. Leal-Cidoncha, C., Lederer, H. Leeb, J. Lerendegui-Marco, S. J. Lonsdale, D. Macina, A. Manna,, J. Marganiec, T. Mart\'inez, A. Masi, P. Mastinu, M. Mastromarco, E. A., Maugeri, A. Mazzone, E. Mendoza, P. M. Milazzo, F. Mingrone, A. Musumarra, A., Negret, R. Nolte, A. Oprea, N. Patronis, A. Pavlik, J. Perkowski, I. Porras,, J. Praena, J. M. Quesada, D. Radeck, T. Rauscher, R. Reifarth, C. Rubbia, J., A. Ryan, M. Sabat\'e-Gilarte, A. Saxena, P. Schillebeeckx, D. Schumann, P., Sedyshev, A. G. Smith, N. V. Sosnin, A. Stamatopoulos, G. Tagliente, J. L., Tain, A. Tarife\~no-Saldivia, L. Tassan-Got, S. Valenta, G. Vannini, V., Variale, P. Vaz, A. Ventura, V. Vlachoudis, R. Vlastou, A. Wallner, S., Warren, C. Weiss, P. J. Woods, T. Wright, P. \v{Z}ugec arXiv: 1902.10631 ยท 2019-09-04 ## TL;DR This study measured the 235U(n,f) cross section relative to standard reactions across a broad neutron energy range at n_TOF, revealing overestimations in recent evaluations and confirming resonance structures, thus improving data accuracy. ## Contribution The paper provides high-resolution measurements of the 235U(n,f) cross section relative to standards, highlighting discrepancies in recent evaluations and confirming resonance features in the keV range. ## Key findings - Overestimation of cross section in 9-18 keV range in recent data - Confirmation of resonance-like structures in the keV neutron energy region - Potential reduction of uncertainty in 1-100 keV neutron energy measurements ## Abstract The 235U(n,f) cross section was measured in a wide energy range at n_TOF relative to 6Li(n,t) and 10B(n,alpha), with high resolution and in a wide energy range, with a setup based on a stack of six samples and six silicon detectors placed in the neutron beam. This allowed us to make a direct comparison of the reaction yields under the same experimental conditions, and taking into account the forward/backward emission asymmetry. A hint of an anomaly in the 10{\div}30 keV neutron energy range had been previously observed in other experiments, indicating a cross section systematically lower by several percent relative to major evaluations. The present results indicate that the evaluated cross section in the 9{\div}18 keV neutron energy range is indeed overestimated, both in the recent updates of ENDF/B-VIII.0 and of the IAEA reference data. Furthermore, these new high-resolution data confirm the existence of resonance-like structures in the keV neutron energy region. The new, high accuracy results here reported may lead to a reduction of the uncertainty in the 1{\div}100 keV neutron energy region. Finally, the present data provide additional confidence on the recently re-evaluated cross section integral between 7.8 and 11 eV. --- Source: https://tomesphere.com/paper/1902.10631