The $^{7}$Be($\boldsymbol{n,p}$)$^{7}$Li reaction and the Cosmological Lithium Problem: measurement of the cross section in a wide energy range at n_TOF (CERN)
L. Damone, M. Barbagallo, M. Mastromarco, A. Mengoni, L. Cosentino, E. Maugeri, S. Heinitz, D. Schumann, R. Dressler, F. Käppeler, N. Colonna, P. Finocchiaro, J… 展开作者
L. Damone, M. Barbagallo, M. Mastromarco, A. Mengoni, L. Cosentino, E. Maugeri, S. Heinitz, D. Schumann, R. Dressler, F. Käppeler, N. Colonna, P. Finocchiaro, J. Andrzejewski, J. Perkowski, A. Gawlik, O. Aberle, S. Altstadt, M. Ayranov, L. Audouin, M. Bacak, J. Balibrea-Correa, J. Ballof, V. Bécares, F. Bečvář, C. Beinrucker, G. Bellia, A. P. Bernardes, E. Berthoumieux, J. Billowes, M. J. G. Borge, D. Bosnar, A. Brown, M. Brugger, M. Busso, M. Caamaño, F. Calviño, M. Calviani, D. Cano-Ott, R. Cardella, A. Casanovas, D. M. Castelluccio, R. Catherall, F. Cerutti, Y. H. Chen, E. Chiaveri, G. Cortés, M. A. Cortés-Giraldo, S. Cristallo, M. Diakaki, M. Dietz, C. Domingo-Pardo, A. Dorsival, E. Dupont, I. Duran, B. Fernandez-Dominguez, A. Ferrari, P. Ferreira, W. Furman, S. Ganesan, A. García-Rio, S. Gilardoni, T. Glodariu, K. Göbel, I. F. Gonçalves, E. González-Romero, T. D. Goodacre, E. Griesmayer, C. Guerrero, F. Gunsing, H. Harada, T. Heftrich, J. Heyse, D. G. Jenkins, E. Jericha, K. Johnston, Y. Kadi, A. Kalamara, T. Katabuchi, P. Kavrigin, A. Kimura, N. Kivel, U. Kohester, M. Kokkoris, M. Krtička, D. Kurtulgil, E. Leal-Cidoncha, C. Lederer-Woods, H. Leeb, J. Lerendegui-Marco, S. Lo Meo, S. J. Lonsdale, R. Losito, D. Macina, J. Marganiec, B. Marsh, T. Martíne, J. G. Martins Correia, A. Masi, C. Massimi, P. Mastinu, F. Matteucci, A. Mazzone, E. Mendoza, P. M. Milazzo, F. Mingrone, M. Mirea, A. Musumarra, A. Negret, R. Nolte, A. Oprea, N. Patronis, A. Pavlik, L. Piersanti, M. Piscopo, A. Plompen, I. Porras, J. Praena, J. M. Quesada, D. Radeck, K. Rajeev, T. Rauscher, R. Reifarth, A. Riego-Perez, S. Rothe, P. Rout, C. Rubbia, J. Ryan, M. Sabaté-Gilarte, A. Saxena, J. Schell, P. Schillebeeckx, S. Schmidt, P. Sedyshev, C. Seiffert, A. G. Smith, N. V. Sosnin, A. Stamatopoulos, T. Stora, G. Tagliente, J. L. Tain, A. Tarifeño-Saldivia, L. Tassan-Got, A. Tsinganis, S. Valenta, G. Vannini, V. Variale, P. Vaz, A. Ventura, V. Vlachoudis, R. Vlastou, A. Wallner, S. Warren, M. Weigand, C. Weiß, C. Wolf, P. J. Woods, T. Wright, P. Žugec
We report on the measurement of the $^{7}$Be($n, p$)$^{7}$Li cross section from thermal to approximately 325 keV neutron energy, performed in the high-flux experimental area (EAR2) of the n\_TOF facility at CERN. This reaction plays a key role in the lithium yield of the Big Bang Nucleosynthesis (BBN) for standard cosmology. The only two previous time-of-flight measurements performed on this reaction did not cover the energy window of interest for BBN, and showed a large discrepancy between each other. The measurement was performed with a Si-telescope, and a high-purity sample produced by implantation of a $^{7}$Be ion beam at the ISOLDE facility at CERN. While a significantly higher cross section is found at low-energy, relative to current evaluations, in the region of BBN interest the present results are consistent with the values inferred from the time-reversal $^{7}$Li($p, n$)$^{7}$Be reaction, thus yielding only a relatively minor improvement on the so-called Cosmological Lithium Problem (CLiP). The relevance of these results on the near-threshold neutron production in the p+$^{7}$Li reaction is also discussed.
Neutron capture data on intermediate mass nuclei are of key importance to nucleosynthesis in the weak component of the slow neutron capture processes, which occurs in massive stars. The ($n,γ$) cross section on $^{70}$Ge, which is mainly produced in the $s$~process, was measured at the neutron time-of-flight facility n_TOF at CERN. Resonance capture kernels were determined up to 40~keV neutron energy, and average cross sections up to 300~keV. Stellar cross sections were calculated from $kT=5$~keV to $kT=100$ keV and are in very good agreement with a previous measurement by Walter and Beer (198…
A neutron radiography testing station has been developed exploiting the neutron beam of CERN's n\_TOF Experimental Area 2, located at the shortest distance to the neutron producing-target. The characteristics of the n\_TOF neutron beam for the imaging setup are presented in this paper, together with the obtained experimental results. The possible developments of neutron imaging capabilities of the n\_TOF facility in terms of detection-systems and beam-line upgrades are as well outlined.
The 235U(n,f) cross section was measured in a wide energy range (25 meV - 170 keV) at the n_TOF facility at CERN, relative to 6Li(n,t) and 10B(n,alpha) 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 thermal 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 rec…
This article presents a few selected developments and future ideas related to the measurement of $(n,γ)$ data of astrophysical interest at CERN n_TOF. The MC-aided analysis methodology for the use of low-efficiency radiation detectors in time-of-flight neutron-capture measurements is discussed, with particular emphasis on the systematic accuracy. Several recent instrumental advances are also presented, such as the development of total-energy detectors with $γ$-ray imaging capability for background suppression, and the development of an array of small-volume organic scintillators aimed at explo…
Neutron capture cross section measurement of 238U at the n TOF CERN facility with C6D6 scintillation detectors in the energy region from 1 eV to 700 keV
Energy-differential measurement of the $^{\mathrm{nat}}$C(n,p) and $^{\mathrm{nat}}$C(n,d) reactions at the n_TOF facility at CERN
University of Zagreb（萨格勒布大学）；Istituto Nazionale di Fisica Nucleare, Sezione di Bari（意大利国家核物理研究所巴里分部）；Paul Scherrer Institut (PSI)（保罗谢尔研究所）；European Organization for Nuclear Research (CERN)（欧洲核子研究组织）；University of Lodz（罗兹大学）；Istituto Nazionale di Fisica Nucleare, Sezione di Bologna（意大利国家核物理研究所博洛尼亚分部）；Universidad de Sevilla（塞维利亚大学）；TU Wien, Atominstitut（维也纳工业大学原子研究所）；CEA Irfu, Université Paris-Saclay（法国替代能源和原子能委员会伊夫林研究技术中心，巴黎-萨克雷大学）；University of Manchester（曼彻斯特大学）
We report on the measurement of the $^{7}$Be($n, p$)$^{7}$Li cross section from thermal to approximately 325 keV neutron energy, performed in the high-flux experimental area (EAR2) of the n_TOF facility at CERN. This reaction plays a key role in the lithium yield of the Big Bang Nucleosynthesis (BBN) for standard cosmology. The only two previous time-of-flight measurements performed on this reaction did not cover the energy window of interest for BBN, and showed a large discrepancy between each other. The measurement was performed with a Si-telescope, and a high-purity sample produced by impla…
A new experimental area, the NEAR station, has recently been built at the CERN n TOF facility, at a short distance from the spallation target (1.5 m). The new area, characterized by a neutron beam of very high flux, has been designed with the purpose of performing activation measurements of interest for astrophysics and various applications. The beam is transported from the spallation target to the NEAR station through a hole in the shielding wall of the target, inside which a collimator is inserted. The new area is complemented with a γ-ray spectroscopy laboratory, the GEAR station, equipped …
A new measurement of the $^{235}$U(n,f) cross section was performed at the neutron time-of-flight facility n_TOF at CERN. The experiment focused on neutron energies from 20 MeV to several hundred MeV, and was normalized to neutron scattering on hydrogen. This is a measurement first of its kind at this facility, in an energy range that was until now not often explored, so the detector development phase was crucial for its success. Two detectors are presented, a parallel plate fission chamber (PPFC) and a recoil proton telescope (RPT), both dedicated to perform measurements in the incident neutr…
73Ge(n,g) cross sections were measured at the neutron time-of-flight facility n_TOF at CERN up to neutron energies of 300 keV, providing for the first time experimental data above 8 keV. Results indicate that the stellar cross section at kT = 30 keV is 1.5 to 1.7 times higher than most theoretical predictions. The new cross sections result in a substantial decrease of 73Ge produced in stars, which would explain the low isotopic abundance of 73Ge in the solar system.
The interpretation of the emergent collective behaviour of atomic nuclei in terms of deformed intrinsic shapes [1] is at the heart of our understanding of the rich phenomenology of their structure, ranging from nuclear energy to astrophysical applications across a vast spectrum of energy scales. A new window onto the deformation of nuclei has been recently opened with the realization that nuclear collision experiments performed at high-energy colliders, such as the CERN Large Hadron Collider (LHC), enable experimenters to identify the relative orientation of the colliding ions in a way that ma…
A new data analysis method is developed for the angle resolving silicon telescope introduced at the neutron time of flight facility n_TOF at CERN. The telescope has already been used in measurements of several neutron induced reactions with charged particles in the exit channel. The development of a highly detailed method is necessitated by the latest joint measurement of the $^{12}$C($n,p$) and $^{12}$C($n,d$) reactions from n_TOF. The reliable analysis of these data must account for the challenging nature of the involved reactions, as they are affected by the multiple excited states in the d…
The neutron capture cross section of $^{154}$Gd was measured from 1 eV to 300 keV in the experimental area located 185 m from the CERN n\_TOF neutron spallation source, using a metallic sample of gadolinium, enriched to 67$\%$ in $^{154}$Gd. The capture measurement, performed with four C$_{6}$D$_{6}$ scintillation detectors, has been complemented by a transmission measurement performed at the GELINA time-of-flight facility (JRC-Geel), thus minimising the uncertainty related to sample composition. An accurate Maxwellian averaged capture cross section (MACS) was deduced over the temperature rang…
Recoil Proton Telescopes and Parallel Plate Avalanche Counters for the $^{235}$U(n,f) cross section measurement relative to H(n,n)H between 10 and 450 MeV neutron energy
University of Zagreb（萨格勒布大学）；Istituto Nazionale di Fisica Nucleare（意大利国家核物理研究所）；European Organization for Nuclear Research (CERN)（欧洲核子研究组织（CERN））；Uniwersytet Łódzki（罗兹大学）；Universidad de Sevilla（塞维利亚大学）；Technische Universität Wien（维也纳工业大学）
The paper explores the feasibility of using machine learning techniques, in particular neural networks, for classification of the experimental data from the joint $^\text{nat}$C(n,p) and $^\text{nat}$C(n,d) reaction cross section measurement from the neutron time of flight facility n_TOF at CERN. Each relevant $ΔE$-$E$ pair of strips from two segmented silicon telescopes is treated separately and afforded its own dedicated neural network. An important part of the procedure is a careful preparation of training datasets, based on the raw data from Geant4 simulations. Instead of using these raw d…
Neutron capture measurements on $^{155}$Gd and $^{157}$Gd were performed using the time-of-flight technique at the n\_TOF facility at CERN. Four samples in form of self-sustaining metallic discs isotopically enriched in $^{155}$Gd and $^{157}$Gd were used. The measurements were carried out at the experimental area (EAR1) at 185 m from the neutron source, with an array of 4 C$_6$D$_6$ liquid scintillation detectors. The capture cross sections of $^{155}$Gd and $^{157}$Gd at neutron kinetic energy of 0.0253 eV have been estimated to be 62.2(2.2) kb and 239.8(9.3) kb, respectively, thus up to 6\%…
First $^{94}$Nb($n,γ$) Measurement: Constraining the Nucleosynthetic Origin of $^{94}$Mo in Presolar Grains
Instituto de Física Corpuscular, CSIC - Universidad de Valencia（瓦伦西亚大学粒子物理研究所）；Charles University（布拉格查理大学）；Istituto Nazionale di Fisica Nucleare, Sezione di Trieste（意大利国家核物理研究所的里雅斯特分部）；Department of Physics, University of Trieste（的里雅斯特大学物理系）；Istituto Nazionale di Fisica Nucleare, Sezione di Perugia（意大利国家核物理研究所佩鲁贾分部）；Istituto Nazionale di Astrofisica - Osservatorio Astronomico d’Abruzzo（意大利国家天体物理研究所阿布鲁佐天文台）；Goethe University Frankfurt（法兰克福歌德大学）；Institute for Astrophysical Research, Boston University（波士顿大学天体物理研究所）；Paul Scherrer Institut (PSI)（保罗谢勒研究所）；Institut Laue-Langevin (ILL)（朗之万-居里研究所）；Universitat Politècnica de Catalunya（加泰罗尼亚理工大学）；Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT)（能源、环境与技术研究中心）
