First Results of the 140^{140}Ce(n,γ)141^{141}Ce Cross-Section Measurement at n_TOF

An accurate measurement of the $^{140}$Ce(n,γ) energy-dependent cross-section was performed at the n_TOF facility at CERN. This cross-section is of great importance because it represents a bottleneck for the s-process nucleosynthesis and determines to a large extent the cerium abundance in stars. The measurement was motivated by the significant difference between the cerium abundance measured in globular clusters and the value predicted by theoretical stellar models. This discrepancy can be ascribed to an overestimation of the $^{140}$Ce capture cross-section due to a lack of accurate nuclear data. For this measurement, we used a sample of cerium oxide enriched in $^{140}$Ce to 99.4%. The experimental apparatus consisted of four deuterated benzene liquid scintillator detectors, which allowed us to overcome the difficulties present in the previous measurements, thanks to their very low neutron sensitivity. The accurate analysis of the p-wave resonances and the calculation of their average parameters are fundamental to improve the evaluation of the $^{140}$Ce Maxwellian-averaged cross-section

First Results of the 140^{140}Ce(n,γ)141^{141}Ce Cross-Section Measurement at n_TOF

An accurate measurement of the $^{140}$Ce(n,γ) energy-dependent cross-section was performed at the n_TOF facility at CERN. This cross-section is of great importance because it represents a bottleneck for the s-process nucleosynthesis and determines to a large extent the cerium abundance in stars. The measurement was motivated by the significant difference between the cerium abundance measured in globular clusters and the value predicted by theoretical stellar models. This discrepancy can be ascribed to an overestimation of the $^{140}$Ce capture cross-section due to a lack of accurate nuclear data. For this measurement, we used a sample of cerium oxide enriched in $^{140}$Ce to 99.4%. The experimental apparatus consisted of four deuterated benzene liquid scintillator detectors, which allowed us to overcome the difficulties present in the previous measurements, thanks to their very low neutron sensitivity. The accurate analysis of the p-wave resonances and the calculation of their average parameters are fundamental to improve the evaluation of the $^{140}$Ce Maxwellian-averaged cross-section

Measurement of the 244^{244}Cm, 246^{246}Cm and 248^{248}Cm neutron-induced capture cross sections at the CERN n_TOF facility

Accurate neutron capture cross section data for minor actinides (MAs) are required to estimate the production and transmutation rates of MAs in light water reactors, critical fast reactors like Gen-IV systems, and other innovative reactor systems such as accelerator driven systems (ADS). In particular, $^{244}$Cm, $^{246}$Cm and $^{248}$Cm ($^{244,246,248}$Cm) play an important role in the transport, storage and transmutation of the nuclear waste of the actual nuclear reactors, due to the contribution of these isotopes to the radiotoxicity, neutron emission, and decay heat in the spent nuclear fuel. Also, capture reactions in these Cm isotopes open the path for the formation of heavier elements such as Bk and Cf. Recent sensitivity studies have shown that the uncertainties in the evaluations of $^{244,246,248}$Cm in the resonance region are too big to obtain the desired uncertainties in the characterisation of the spent fuel of conventional nuclear reactors.\\ In order to reduce the uncertainties, new measurements of the $^{244,246,248}$Cm capture cross sections have been performed at n\_TOF. There are only two previous capture measurements of the cross sections of these isotopes. The first measurement was carried out in 1969 by Moore \textit{et al.} using an underground nuclear explosion, and the cross sections were measured between 20 eV and 1 keV. The second measurement was performed in J-PARC by Kimura \textit{et al.} in 2010 with germanium detectors, and the cross sections were measured between 4 and 30 eV.\\ The measurements at the n\_TOF facility have been performed with two different samples, one prepared to measure the cross section of $^{244}$Cm and the other to measure the cross sections of $^{246,248}$Cm. The two samples were the same as the ones used in the previous Cm capture measurement at J-PARC. The cross section of $^{244}$Cm has been measured in the first experimental area of n\_TOF (\gls{EAR1}) located at 185 meters with the Total Absorption Calorimeter (TAC) in the energy range between 7 and 100 eV, and in the second experimental area (\gls{EAR2}) located at 19 meters with C$_6$D$_6$ detectors in the energy range between 7 and 300 eV. The results obtained for the two areas are compatible. In \gls{EAR2} the cross sections of $^{246}$Cm and $^{248}$Cm have also been measured, in the energy range between 4 and 400 eV and between 7 and 100 eV, respectively. In addition, the resonances of $^{240}$Pu, present in the samples due to the decay of $^{244}$Cm, have been analysed between 20 and 190 eV. The $^{244,246,248}$Cm and $^{240}$Pu cross sections have been normalised to the first resonance of $^{240}$Pu. \\ In total, 36 resonances of Cm have been fitted, implementing the SAMMY code, and the uncertainties in the resonance parameters are smaller than the uncertainties in the two previous measurements for most of the resonances, improving the status of the nuclear data for these isotopes

On the resolution function of the n_TOF facility: a comprehensive study and user guide

The purpose of this report is to provide the necessary information and tools for the n_TOF Collaboration on how to correctly account for the neutron resolution function in the experimental areas (EAR1 and EAR2) for different n_TOF operation periods. The n_TOF target as well as the cooling/moderation system was designed to optimize the performances of the neutron beam for EAR1. Additionally, EAR1 is located underground 200 m away, in nearly the same direction as the incoming proton beam, from the spallation target. On the contrary, EAR2 was an extension of the existing facility. It is located above the ground at 20 m from the spallation target in the perpendicular direction with respect to the incoming proton beam. Even though the energy resolution is worse due to the shorter flightpath, the main issue with the resolution function comes from the geometry of the cooling/moderation system and the shape of the spallation target. Experimental data acquired in any of the experimental areas has embedded the effect of the resolution function. Therefore, when treating these data there are two options. Either deconvolute them from the resolution function or convolve the reference data, for instance evaluated cross sections, with the resolution function to be able to compare both sets of data in the same conditions. Usually, the second method is adopted for simplicity. In both cases the explicit distribution of the resolution function should be available. Even more, to perform the resonance analysis with SAMMY or REFIT this information must be known. The question here is: how to obtain the resolution function

The DESPEC setup for GSI and FAIR

The DEcay SPECtroscopy (DESPEC) setup for nuclear structure investigations was developed and commissioned at GSI, Germany in preparation for a full campaign of experiments at the FRS and Super-FRS. In this paper, we report on the first employment of the setup in the hybrid configuration with the AIDA implanter coupled to the FATIMA LaBr3(Ce) fast-timing array, and high-purity germanium detectors. Initial results are shown from the first experiments carried out with the setup. An overview of the setup and function is discussed, including technical advancements along the path.Peer ReviewedArticle signat per 169 autors/es. A.K. Mistry 1,2,∗, H.M. Albers 2, T. Arıcı 3, A. Banerjee 2, G. Benzoni 4, B. Cederwall 5, J. Gerl 2, M. Górska 2, O. Hall 6, N. Hubbard 1,2, I. Kojouharov 2, J. Jolie 7, T. Martinez 8, Zs. Podolyák 9, P.H. Regan 9,10, J.L. Tain 11, A. Tarifeno-Saldivia 12, H. Schaffner 2, V. Werner 1, G. Ağgez 3, J. Agramunt 11, U. Ahmed 1, O. Aktas 5, V. Alcayne 8, A. Algora 11,13, S. Alhomaidhi 1,2, F. Amjad 2, C. Appleton 6, M. Armstrong 7, M. Balogh 14, K. Banerjee 15, P. Bednarczyk 16, J. Benito 17, C. Bhattacharya 15, P. Black 6, A. Blazhev 7, S. Bottoni 4,18, P. Boutachkov 2, A. Bracco 18,4, A.M. Bruce 19, M. Brunet 9, C.G. Bruno 6, I. Burrows 20, F. Calvino 12, R.L. Canavan 9,10, D. Cano-Ott 8, M.M.R. Chishti 9, P. Coleman-Smith 20, M.L. Cortés 1, G. Cortes 12, F. Crespi 18,4, B. Das 5, T. Davinson 6, A. De Blas 12, T. Dickel 2, M. Doncel 21, A. Ertoprak 5,3, A. Esmaylzadeh 7, B. Fornal 16, L.M. Fraile 17, F. Galtarossa 14, A. Gottardo 14, V. Guadilla 11,22, J. Ha 23,24, E. Haettner 2, G. Häfner 25,7, H. Heggen 2, P. Herrmann 1, C. Hornung 2, S. Jazrawi 9,10, P.R. John 1, A. Jokinen 26, C.E. Jones 19, D. Kahl 6,27, V. Karayonchev 7, E. Kazantseva 2, R. Kern 1, L. Knafla 7, R. Knöbel 2, P. Koseoglou 1, G. Kosir 28, D. Kostyleva 2, N. Kurz 2, N. Kuzminchuk 2, M. Labiche 20, J. Lawson 20, I. Lazarus 20, S.M. Lenzi 23, S. Leoni 4,18, M. Llanos-Expósito 17, R. Lozeva 25, A. Maj 16, J.K. Meena 15, E. Mendoza 8, R. Menegazzo 24, D. Mengoni 14, T.J. Mertzimekis 29, M. Mikolajczuk 22,2, B. Million 4, N. Mont-Geli 12, A.I. Morales 11, P. Morral 20, I. Mukha 2, J.R. Murias 17, E. Nacher 11, P. Napiralla 1, D.R. Napoli 14, B.S. Nara-Singh 30, D. O’Donnell 30, S.E.A. Orrigo 11, R.D. Page 31, R. Palit 32, M. Pallas 12, J. Pellumaj 14, S. Pelonis 29, H. Pentilla 26, A. Pérez de Rada 8, R.M. Pérez-Vidal 14, C.M. Petrache 25, N. Pietralla 1, S. Pietri 2, S. Pigliapoco 24, J. Plaza 8, M. Polettini 4,18, C. Porzio 4,18, V.F.E. Pucknell 20, F. Recchia 23, P. Reiter 7, K. Rezynkina 24, S. Rinta-Antila 26, E. Rocco 2, H.A. Rösch 2,1, P. Roy 15,2, B. Rubio 11, M. Rudigier 1, P. Ruotsalainen 26, S. Saha 33, E. Şahin 1,2, Ch. Scheidenberger 2, D.A. Seddon 31, L. Sexton 6, A. Sharma 34, M. Si 25, J. Simpson 20, A. Smith 35, R. Smith 20, P.A. Söderström 27, A. Sood 5, A. Soylu 36, Y.K. Tanaka 37, J.J. Valiente-Dobón 14, P. Vasileiou 29, J. Vasiljevic 5, J. Vesic 28, D. Villamarin 8, H. Weick 2, M. Wiebusch 2, J. Wiederhold 1, O. Wieland 4, H.J. Wollersheim 2, P.J. Woods 6, A. Yaneva 7, I. Zanon 14, G. Zhang 23,24, J. Zhao 2,38, R. Zidarova 1, G. Zimba 26, A. Zyriliou 29Postprint (author's final draft

First Results of the 140Ce(n,g)141Ce Cross-Section Measurement at n_TOF

The cerium oxide material for this measurement was provided by T. Katabuchi of the Tokyo Institute of Technology.An accurate measurement of the 140Ce(n,g) energy-dependent cross-section was performed at the n_TOF facility at CERN. This cross-section is of great importance because it represents a bottleneck for the s-process nucleosynthesis and determines to a large extent the cerium abundance in stars. The measurement was motivated by the significant difference between the cerium abundance measured in globular clusters and the value predicted by theoretical stellar models. This discrepancy can be ascribed to an overestimation of the 140Ce capture cross-section due to a lack of accurate nuclear data. For this measurement, we used a sample of cerium oxide enriched in 140Ce to 99.4%. The experimental apparatus consisted of four deuterated benzene liquid scintillator detectors, which allowed us to overcome the difficulties present in the previous measurements, thanks to their very low neutron sensitivity. The accurate analysis of the p-wave resonances and the calculation of their average parameters are fundamental to improve the evaluation of the 140Ce Maxwellian-averaged cross-section