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Pu(n,f) cross-section at the CERN n_TOF facility; First results from experimental area II (EAR-2)Stamatopoulos, A.*; Tsinganis, A.*; Colonna, N.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他126名*
EPJ Web of Conferences, 146, p.04030_1 - 04030_4, 2017/09
被引用回数：6 パーセンタイル：95.25(Nuclear Science & Technology)The accurate knowledge of the neutron-induced fission cross-sections of actinides and other isotopes involved in the nuclear fuel cycle is essential for the design of advanced nuclear systems, such as Generation-IV nuclear reactors. Such experimental data can also provide the necessary feedback for the adjustment of nuclear model parameters used in the evaluation process, resulting in the further development of nuclear fission models. In the present work, the Pu(n,f) cross-section was measured at CERN n_TOF facility relative to the well-known 
U(n,f) cross section, over a wide range of neutron energies, from meV to almost MeV, using the time-of-flight technique and a set-up based on Micromegas detectors. This measurement was the first experiment to be performed at n_TOF new experimental area (EAR-2), which offers a significantly higher neutron flux compared to the already existing experimental area (EAR-1).Preliminary results as well as the experimental procedure, including a description of the facility and the data handling and analysis, are presented.
Lerendegui-Marco, J.*; Cort
s-Giraldo, M. A.*; Guerrero, C.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他114名*
EPJ Web of Conferences, 146, p.03030_1 - 03030_4, 2017/09
被引用回数：0 パーセンタイル：0.08(Nuclear Science & Technology)Monte Carlo (MC) simulations are an essential tool to determine fundamental features of a neutron beam, such as the neutron flux or the 
ray background, that sometimes can not be measured or at least not in every position or energy range. Until recently, the most widely used MC codes in this field had been MCNPX and FLUKA. However, the Geant4 toolkit has also become a competitive code for the transport of neutrons after the development of the native Geant4 format for neutron data libraries, G4NDL. In this context, we present the Geant4 simulations of the neutron spallation target of the n TOF facility at CERN, done with version 10.1.1 of the toolkit. The first goal was the validation of the intra-nuclear cascade models implemented in the code using, as benchmark, the characteristics of the neutron beam measured at the first experimental area (EAR1), especially the neutron flux and energy distribution, and the time distribution of neutrons of equal kinetic energy, the so-called Resolution Function. The second goal was the development of a Monte Carlo tool aimed to provide useful calculations for both the analysis and planning of the upcoming measurements at the new experimental area (EAR2) of the facility.
Be(n,
) and Be(n,p) cross-section measurement for the cosmological lithium problem at the n_TOF facility at CERNBarbagallo, M.*; Colonna, N.*; Aberle, O.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他125名*
EPJ Web of Conferences, 146, p.01012_1 - 01012_4, 2017/09
被引用回数：1 パーセンタイル：61.21(Nuclear Science & Technology)The Cosmological Lithium Problem refers to the large discrepancy between the abundance of primordial Li predicted by the standard theory of Big Bang Nucleosynthesis and the value inferred from the so-called "Spite plateau" in halo stars. A possible explanation for this longstanding puzzle in Nuclear Astrophysics is related to the incorrect estimation of the destruction rate of Be, which is responsible for the production of 95% of primordial Lithium. While charged-particle induced reactions have mostly been ruled out, data on the Be(n,) and Be(n,p) reactions are scarce or completely missing, so that a large uncertainty still affects the abundance of Li predicted by the standard theory of Big Bang Nucleosynthesis. Both reactions have been measured at the n_TOF facility at CERN, providing for the first time data in a wide neutron energy range.
Chiaveri, E.*; Aberle, O.*; Andrzejewski, J.*; 原田 秀郎; 木村 敦; n_TOF Collaboration*; 他111名*
EPJ Web of Conferences, 146, p.03001_1 - 03001_4, 2017/09
被引用回数：1 パーセンタイル：61.21(Nuclear Science & Technology)The CERN n_TOF neutron beam facility is characterized by a very high instantaneous neutron flux, excellent TOF resolution at the 185m long flight path (EAR-1), low intrinsic background and coverage of a wide range of neutron energies, from thermal to a few GeV. The overall efficiency of the experimental program and the range of possible measurements has been expanded with the construction of a second experimental area (EAR-2), located 20m on the vertical of the n_TOF spallation target. This upgrade, which benefits from a neutron flux 30 times higher than in EAR-1, provides a substantial extension in measurement capabilities, opening the possibility to collect data on neutron cross-section of isotopes with short half-lives or available in very small amounts. We will discuss the innovative features of the EAR-2 neutron beam that make possible to perform very challenging measurements on short-lived radioisotopes or sub-mg samples, out of reach up to now at other neutron facilities around the world. Finally, the future perspectives of the facility will be presented.
