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Balibrea-Correa, J.*; 木村 敦; 他133名*
Nuclear Instruments and Methods in Physics Research A, 1064, p.169385_1 - 169385_13, 2024/07
被引用回数：3 パーセンタイル：86.15(Instruments & Instrumentation)A Monte Carlo method for detectors using the Total Energy Deposition principle (which is obtained via application of the PHWT) was proposed. In this method, both dead-time and pile-up effects are considered simultaneously in a consistent manner. To validate this method in harsh count rate conditions, we have applied it to two different types of C
D liquid scintillators at different count rate conditions and demonstrated the capability to account for these effects in neutron-capture cross-section measurements at the CERN n_TOF facility. The method brings very good results under the count rates up to 
8 c/
s.
Pb, the heaviest 
-process; Only isotope in the solar systemCasanovas-Hoste, A.*; 原田 秀郎; 木村 敦; 他130名*
Physical Review Letters, 133(5), p.052702_1 - 052702_8, 2024/07
被引用回数：3 パーセンタイル：75.95(Physics, Multidisciplinary)Tl(n, 
) cross section was measured at the CERN neutron time-of-flight facility n_TOF, employing a sample of only 9 mg of Tl produced at the Institute Laue Langevin high flux reactor. At the -process temperatures of kT 
8 keV and kT 30 keV, Maxwellian-averaged cross sections (MACS) of 580(168) mb and 260(90) mb, respectively. These figures are about 3% lower and 20% higher than the corresponding values widely used in astrophysical calculations, which were based only on theoretical calculations. By using the new Tl MACS, the uncertainty arising from the Tl(n, ) cross section on the -process abundance of Pb has been reduced from 30% down to +8%/-6%, and the -process calculations are in agreement with the latest solar system abundance of Pb reported by K. Lodders in 2021.
) cross-section measurements at n_TOF EAR2Alcayne, V.*; 木村 敦; 他134名*
Radiation Physics and Chemistry, 217, p.111525_1 - 111525_11, 2024/04
被引用回数：6 パーセンタイル：96.49(Chemistry, Physical)The neutron time-of-flight facility n_TOF at CERN is a spallation source dedicated to measurements of neutron induced reaction cross-sections of interest in nuclear technologies, astrophysics, and other applications. Since 2014, Experimental ARea 2 (EAR2) is operational and delivers a neutron fluence of 
neutrons per nominal proton pulse, which is 50 times higher than the one of the other experimental area. The high neutron flux at EAR2 results in high counting rates in the detectors that challenged the previously existing capture detection systems. For this reason, a Segmented Total Energy Detector (sTED) has been developed to overcome the limitations in the detector's response, by reducing the active volume and by using a photo-multiplier (PMT) optimized for high counting rates. This paper presents the main characteristics of the sTED, including energy and time resolution, response to -rays, and provides details for the Pulse Height Weighting Technique (PHWT). The sTED has been validated to perform neutron-capture cross-section measurements in EAR2 in the neutron energy range from thermal up to at least 400 keV.
-rays from slow neutron-induced fission of 
U with STEFFWright, T.*; 原田 秀郎; 木村 敦; 他121名*
European Physical Journal A, 60(3), p.70_1 - 70_11, 2024/03
被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)The average energy and multiplicity of prompt -rays from slow neutron-induced fission of U have been measured using the STEFF spectrometer at the neutron time-of-flight facility n_TOF. The individual responses from 11 NaI scintillators were corrected for multiple -ray interactions, prompt fission neutrons and background counts before being deconvolved to estimate the emitted spectrum of prompt fission -rays. The results give an average -ray energy 
of 1.71(5) MeV and multiplicity 
of 2.66(18) considering -rays emitted within the energy range from 0.8 to 6.8 MeV. The n_TOF data has a slightly larger and smaller than other recent measurements, however the product of the two is in agreement within the quoted uncertainties.
Ce(n, ) cross section at n_TOF and its astrophysical implications for the chemical evolution of the universeAmaducci, S.*; 原田 秀郎; 木村 敦; 他130名*
Physical Review Letters, 132(12), p.122701_1 - 122701_8, 2024/03
被引用回数：5 パーセンタイル：82.50(Physics, Multidisciplinary)Ce(n,) is a key reaction for slow neutron-capture (-process) nucleosynthesis due to being a bottleneck in the reaction flow. For this reason, it was measured with high accuracy (uncertainty 5%) at the n_TOF facility, with an unprecedented combination of a high purity sample and low neutron-sensitivity detectors. The measured Maxwellian averaged cross section is up to 40% higher than previously accepted values. Stellar model calculations indicate a reduction around 20% of the s-process contribution to the Galactic cerium abundance and smaller sizeable differences for most of the heavier elements. No variations are found in the nucleosynthesis from massive stars.
Th at the CERN n_TOF facilityMichalopoulou, V.*; 原田 秀郎; 木村 敦; 他134名*
Physical Review C, 108(1), p.014616_1 - 014616_15, 2023/07
被引用回数：2 パーセンタイル：43.87(Physics, Nuclear)The neutron-induced fission cross section of Th has been measured at the neutron time-of-flight facility n_TOF located at CERN. The experiment was performed at the experimental area EAR-1 with a neutron flight path of 185 m, using Micromegas detectors for the detection of the fission fragments. The Th(n,f) cross section was determined relative to the U(n, f) one, covering the energy range from the fission threshold up to 400 MeV. The results from the present work are compared with existing cross-section datasets and the observed discrepancies are discussed and analyzed.
Se(n,) cross section up to 200 keV at the n_TOF facility at CERNSosnin, N. V.*; 原田 秀郎; 木村 敦; 他128名*
Physical Review C, 107(6), p.065805_1 - 065805_9, 2023/06
被引用回数：1 パーセンタイル：25.07(Physics, Nuclear)The Se(n,) reaction is of importance for Se abundance during the slow neutron capture process in massive stars. We have performed a new measurement of the Se radiative neutron capture cross section at the Neutron Time-of-Flight facility at CERN. Resonance capture kernels were derived up to 51 keV and cross sections up to 200 keV. Maxwellian-averaged cross sections were calculated for stellar temperatures between kT = 5 keV and kT = 100 keV, with uncertainties between 4.2% and 5.7%. Our results lead to substantial decreases of 14% and 19% in Se abundances produced through the slow neutron capture process in selected stellar models, compared to using previous recommendation of the cross section.
N(n, p)C cross section at the CERN n_TOF facility from subthermal energy to 800 keVTorres-S
nchez, P.*; 原田 秀郎; 木村 敦; 他129名*
Physical Review C, 107(6), p.064617_1 - 064617_15, 2023/06
被引用回数：1 パーセンタイル：25.07(Physics, Nuclear)The N(n, p)C reaction cross section has been measured at the CERN neutron time-of-flight facility n_TOF from subthermal energy to 800 keV. The experiment was performed at the experimental area EAR-2 with a stack of micromesh gaseous structure detectors (MicroMegas). 
B(n,
)
Li and U(n, f) reactions were used as references. A thermal cross section was obtained (1.809 
0.045 b) that is lower than the two most recent measurements by slightly more than one standard deviation, but in line with the ENDF/B-VIII.0 andJEFF-3.3 evaluations.
Patronis, N.*; 木村 敦; 他130名*
EPJ Techniques and Instrumentation (Internet), 10, p.13_1 - 13_10, 2023/05
During the second long shutdown period of the CERN accelerator complex (LS2, 2019-2021), several upgrade activities took place at the n_TOF facility. The most important have been the replacement of the spallation target with a next generation nitrogen-cooled lead target. Additionally, a new experimental area, at a very short distance from the target assembly (the NEAR Station) was established. In this paper, the core commissioning actions of the new installations are described. The improvement in the n_TOF infrastructure was accompanied by several detector development projects. All these upgrade actions are discussed, focusing mostly on the future perspectives of the n_TOF facility. Furthermore, some indicative current and future measurements are briefly reported.
Domingo-Pardo, C.*; 木村 敦; 他135名*
European Physical Journal A, 59(1), p.8_1 - 8_11, 2023/01
被引用回数：11 パーセンタイル：90.92(Physics, Nuclear)This article presents a few selected developments and future ideas related to the measurement of (n, ) 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 -ray imaging capability for background suppression, and the development of an array of small-volume organic scintilla tors aimed at exploiting the high instantaneous neutron-flux of EAR2.
Ge(n,) cross section below 70 keV measured at n_TOF CERNLederer-Woods, C.*; 原田 秀郎; 木村 敦; 他128名*
European Physical Journal A, 58(12), p.239_1 - 239_9, 2022/12
被引用回数：0 パーセンタイル：0.00(Physics, Nuclear)Neutron capture reaction cross sections on Ge are of importance to determine Ge production during the astrophysical slow neutron capture process. We present new resonance data on Ge(n,) reactions below 70 keV neutron energy. We calculate Maxwellian averaged cross sections, combining our data below 70 keV with evaluated cross sections at higher neutron energies. Our stellar cross sections are in agreement with a previous activation measurement performed at Forschungszentrum Karlsruhe by Marganiec et al., once their data has been re-normalised to account for an update in the reference cross section used in that experiment.
U(n,f) cross section from n_TOF (CERN) from 18 meV to 10 keVMastromarco, M.*; Amaducci, S.*; Colonna, N.*; 木村 敦; 他118名*
European Physical Journal A, 58(8), p.147_1 - 147_13, 2022/08
被引用回数：6 パーセンタイル：65.93(Physics, Nuclear)The U(n,f) cross section was measured in a wide energy range (18 meV - 170 keV) at the n_TOF facility at CERN, relative to 
Li(n,t) and B(n,) standard reactions, with a setup based on a stack of six samples and six silicon detectors placed in the neutron beam. A resonance analysis has been performed up to 200 eV, with the code SAMMY. A good agreement, within 0.5%, is found on average between the new results and the latest evaluated data files ENDF/B-VIII.0 and JEFF-3.3, as well as with respect to the broad group average fission cross section established in the framework of the standard working group of IAEA. However, some discrepancies, of up to 4%, are still present in some specific energy regions.
Moreno-Soto, J.*; 木村 敦; 他130名*
Physical Review C, 105(2), p.024618_1 - 024618_14, 2022/02
被引用回数：2 パーセンタイル：31.55(Physics, Nuclear)The -ray spectra from neutron-capture reactions on the 
U, 
U, and 
U nuclei have been measured with the total absorption calorimeter of the n_TOF facility at CERN. The background-corrected sum-energy and multi-step-cascade spectra were extracted for several isolated s-wave resonances up to about 140 eV. The experimental spectra were compared to statistical model predictions coming from a large selection of models of photon strength functions (PSFs) and nuclear level density (NLD). No combination of PSF and NLD models from literature is able to globally describe our spectra. After extensive search we were able to find model combinations with modified generalized Lorentzian (MGLO) E1 PSF, which match the experimental spectra as well as the total radiative widths.
Ge(n,) cross section at the n_TOF facility at CERNGawlik, A.*; 原田 秀郎; 木村 敦; 他130名*
Physical Review C, 104(4), p.044610_1 - 044610_7, 2021/10
被引用回数：5 パーセンタイル：51.13(Physics, Nuclear)The Ge(n,) reaction has been measured at the n_TOF facility at CERN via the time-of-flight technique. Neutron capture cross sections on Ge are of interest to a variety of low-background experiments, such as neutrinoless double 
decay searches, and to nuclear astrophysics. We have determined resonance capture kernels up to 52 keV neutron energy and used the new data to calculate Maxwellian-averaged neutron capture cross sections for k
T values of 5 to 100 keV.
-ray emitter 
Al in massive stars; Study of the key Al(n,) reactionLederer-Woods, C.*; 原田 秀郎; 木村 敦; 他123名*
Physical Review C, 104(3), p.L032803_1 - L032803_6, 2021/09
被引用回数：8 パーセンタイル：67.39(Physics, Nuclear)Neutron destruction reactions of the cosmic -ray emitter Al are of importance to determine the amount of Al ejected into our galaxy by supernova explosions and for Al production in asymptotic giant branch stars. We performed a new measurement of the Al(n,) reaction up to 160-keV neutron energy at the neutron time-of-flight facilities n_TOF at CERN and GELINA at EC-JRC. We provide strengths for ten resonances, six of them for the first time. We use our data to calculate astrophysical reactivities for stellar temperatures up to 0.7 GK. Our results resolve a discrepancy between the two previous direct measurements of this reaction, and indicate higher stellar destruction rates than the most recently recommended reactivity.
-ray emitter Al in massive stars; Study of the key Al(n, p) reactionLederer-Woods, C.*; 原田 秀郎; 木村 敦; 他121名*
Physical Review C, 104(2), p.L022803_1 - L022803_7, 2021/08
被引用回数：8 パーセンタイル：67.39(Physics, Nuclear)The Al(n,p)Mg reaction is the key reaction impacting on the abundances of the cosmic -ray emitter Al produced in massive stars and impacts on the potential pollution of the early solar system with Al by asymptotic giant branch stars. We performed a measurement of the Al(n,p)Mg cross section at the high-flux beam line EAR-2 at the n_TOF facility (CERN). We report resonance strengths for eleven resonances, nine being measured for the first time, while there is only one previous measurement for the other two. Our resonance strengths are significantly lower than the only previous values available. Our cross-section data range to 150 keV neutron energy, which is sufficient for a reliable determination of astrophysical reactivities up to 0.5 GK stellar temperature.
Babiano-Surez, V.*; 原田 秀郎; 木村 敦; 他132名*
European Physical Journal A, 57(6), p.197_1 - 197_17, 2021/06
被引用回数：19 パーセンタイル：88.41(Physics, Nuclear)i-TED is an innovative detection system which exploits Compton imaging techniques to achieve a superior signal-to-background ratio in (n,) cross-section measurements using time-of-flight technique. This work presents the first experimental validation of the i-TED apparatus for high resolution time-of-flight experiments and demonstrates for the first time the concept proposed for background rejection. To this aim, the 
Au(n,) and 
Fe(n,) reactions were studied at CERN n_TOF using an i-TED demonstrator based on three position-sensitive detectors. The i-TED prototype built for this study shows a factor of about 3 times higher detection sensitivity than traditional 
detectors in the 10 keV neutron-energy region. This paper explores also the perspectives of further enhancement in performance attainable with the final i-TED array consisting of twenty position-sensitive detectors and new analysis methodologies based on Machine-Learning techniques.
Ce(n,)
Ce cross-section measurement at n_TOFAmaducci, S.*; 原田 秀郎; 木村 敦; 他127名*
Universe (Internet), 7(6), p.200_1 - 200_11, 2021/06
被引用回数：5 パーセンタイル：32.63(Astronomy & Astrophysics)An accurate measurement of the Ce(n,) 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. For this measurement, we used a sample of cerium oxide enriched in 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 Ce Maxwellian-averaged cross-section.
Ge(n,) cross section over a wide neutron energy range at the CERN n_TOF facilityDietz, M.*; 原田 秀郎; 木村 敦; 他121名*
Physical Review C, 103(4), p.045809_1 - 045809_8, 2021/04
被引用回数：7 パーセンタイル：63.10(Physics, Nuclear)The Ge(n,) cross section was measured for neutron energies up to 300 keV at the neutron time-of-flight facility n_TOF (CERN). The measurement was performed at the high-resolution beamline EAR-1, using an isotopically enriched Ge sample. The prompt capture rays were detected with four liquid scintillation detectors, optimized for low neutron sensitivity. We determined resonance capture kernels up to a neutron energy of 43 keV, and averaged cross sections from 43 to 300 keV. Maxwellian-averaged cross section values were calculated from kT = 5 to 100 keV, with uncertainties between 3.2% and 7.1%. The new results significantly reduce uncertainties of abundances produced in the slow neutron capture process in massive stars.
Terranova, N.*; Aberle, O.*; Alcayne, V.*; 木村 敦; 他125名*
EPJ Web of Conferences, 239, p.01024_1 - 01024_5, 2020/09
被引用回数：6 パーセンタイル：95.71(Nuclear Science & Technology)The U(n,f) cross section from 20 MeV up to about 1 GeV has been measured relative to the 
H(n,n)H reaction. The neutron flux impinging on the U sample has been obtained by detecting recoil protons originating from n-p scattering in a C
H
sample. Two Proton Recoil Telescopes (PRT), consisting of several layers of solid-state detectors and fast plastic scintillators, have been set at proton scattering angles of 25.07
and 20.32. Extensive Monte Carlo simulations were performed to characterize proton transport through the PRTs. In this work we compare measured data collected with the PRTs with a full Monte Carlo simulation based on the Geant-4 toolkit.
