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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：2 パーセンタイル：52.69(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.
Gd(n,
) induced by thermal and epithermal neutronsMastromarco, M.*; Manna, A.*; Aberle, O.*; Andrzejewski, J.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他116名*
European Physical Journal A, 55(1), p.9_1 - 9_20, 2019/01
被引用回数：27 パーセンタイル：92.58(Physics, Nuclear)Neutron capture cross section measurements on 
Gd and 
Gd were performed using the time-of-flight technique at the n_TOF facility at CERN on isotopically enriched samples. The measurements were carried out in the n TOF experimental area EAR1, at 185m from the neutron source, with an array of 4 C
D liquid scintillation detectors. At a neutron kinetic energy of 0.0253eV, capture cross sections of 62.2(2.2) and 239.8(8.4) kilobarn have been derived for Gd and Gd, respectively, with up to 6% deviation relative to values presently reported in nuclear data libraries, but consistent with those values within 1.6 standard deviations. A resonance shape analysis has been performed in the resolved resonance region up to 181eV and 307eV, respectively for Gd and Gd, where on average, resonance parameters have been found in good agreement with evaluations. Above these energies and up to 1keV, the observed resonance-like structure of the cross section has been analysed and characterised. From a statistical analysis of the observed neutron resonances we deduced: neutron strength function of 2.01(28) 
10
and 2.17(41) 10; average total radiative width of 106.8(14)meV and 101.1(20)meV and s-wave resonance spacing 1.6(2)eV and 4.8(5)eV for n + Gd and n + Gd systems, respectively.
Be(n,p)Li reaction and the cosmological lithium problem; Measurement of the cross section in a wide energy range at n_TOF at CERNDamone, L.*; Barbagallo, M.*; Mastromarco, M.*; Cosentino, L.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他152名*
Physical Review Letters, 121(4), p.042701_1 - 042701_7, 2018/07
被引用回数：50 パーセンタイル：91.96(Physics, Multidisciplinary)We report on the measurement of the Be(n,p)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 they 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 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 Li(p,n)Be reaction, thus yielding only a relatively minor improvement on the so-called cosmological lithium problem. The relevance of these results on the near threshold neutron production in the p+Li reaction is also discussed.
Be(n,p)Li reaction at n_TOFBarbagallo, M.*; Andrzejewski, J.*; Mastromarco, M.*; Perkowski, J.*; Damone, L. A.*; Gawlik, A.*; 木村 敦; n_TOF Collaboration*; 他122名*
Nuclear Instruments and Methods in Physics Research A, 887, p.27 - 33, 2018/04
被引用回数：13 パーセンタイル：79.66(Instruments & Instrumentation)Following the completion of the second neutron beam line and the related experimental area (EAR2) at the n_TOF spallation neutron source at CERN, several experiments were planned and performed. The high instantaneous neutron flux available in EAR2 allows to investigate neutron induced reactions with charged particles in the exit channel even employing targets made out of small amounts of short-lived radioactive isotopes. After the successful measurement of the Be(n,)cross section, the Be(n,p)Li reaction was studied in order to provide still missing cross section data of relevance for Big Bang Nucleosynthesis (BBN), in an attempt to find a solution to the cosmological Lithium abundance problem. This paper describes the experimental setup employed in such a measurement and its characterization.
