|
|
n_TOF Collaboration(Sabate-Gilarte et al.), Domingo-Pardo, C., Tain, J. L., & Tarifeño-Saldivia, A. (2017). High-accuracy determination of the neutron flux in the new experimental area n_TOF-EAR2 at CERNx. Eur. Phys. J. A, 53(10), 210–13pp.
Abstract: A new high flux experimental area has recently become operational at the nTOF facility at CERN. This new measuring station, nTOF-EAR2, is placed at the end of a vertical beam line at a distance of approximately 20m from the spallation target. The characterization of the neutron beam, in terms of flux, spatial profile and resolution function, is of crucial importance for the feasibility study and data analysis of all measurements to be performed in the new area. In this paper, the measurement of the neutron flux, performed with different solid-state and gaseous detection systems, and using three neutronconverting reactions considered standard in different energy regions is reported. The results of the various measurements have been combined, yielding an evaluated neutron energy distribution in a wide energy range, from 2meV to 100MeV, with an accuracy ranging from 2%, at low energy, to 6% in the high-energy region. In addition, an absolute normalization of the n_TOF-EAR2 neutron flux has been obtained by means of an activation measurement performed with 197 Au foils in the beam.
|
|
|
|
n_TOF Collaboration(Paradela, C. et al), Domingo-Pardo, C., Giubrone, G., & Tain, J. L. (2015). High-accuracy determination of the U-238/U-235 fission cross section ratio up to approximate to 1 GeV at n_TOF at CERN. Phys. Rev. C, 91(2), 024602–11pp.
Abstract: The U-238 to U-235 fission cross section ratio has been determined at nTOF up to approximate to 1 GeV, with two different detection systems, in different geometrical configurations. A total of four datasets has been collected and compared. They are all consistent to each other within the relative systematic uncertainty of 3-4%. The data collected at nTOF have been suitably combined to yield a unique fission cross section ratio as a function of neutron energy. The result confirms current evaluations up to 200 MeV. Good agreement is also observed with theoretical calculations based on the INCL++ /Gemini++ combination up to the highest measured energy. The n_TOF results may help solve a long-standing discrepancy between the two most important experimental datasets available so far above 20 MeV, while extending the neutron energy range for the first time up to approximate to 1 GeV.
|
|
|
|
n_TOF Collaboration(Tarrio, D. et al), Domingo-Pardo, C., Plag, R., Plompen, A., & Tain, J. L. (2011). High-energy Neutron-induced Fission Cross Sections of Natural Lead and Bismuth-209. J. Korean Phys. Soc., 59(2), 1904–1907.
Abstract: The CERN Neutron Time-Of-Flight (n_TOF) facility is well suited to measure small neutron-induced fission cross sections, as those of subactinides. The cross section ratios of (nat)Pb and (209)Bi relative to (235)U and (238)U were measured using PPAC detectors. The fragment coincidence method allows to unambiguously identify the fission events. The present experiment provides the first results for neutron-induced fission up to 1 GeV for (nat)Pb and (209)Bi. A good agreement with previous experimental data below 200 MeV is shown. The comparison with proton-induced fission indicates that the limiting regime where neutron-induced and proton-induced fission reach equal cross section is close to 1 GeV.
|
|
|
|
Zanon, I. et al, Domingo-Pardo, C., & Gadea, A. (2023). High-Precision Spectroscopy of O-20 Benchmarking Ab Initio Calculations in Light Nuclei. Phys. Rev. Lett., 131(26), 262501–7pp.
Abstract: The excited states of unstable O-20 were investigated via.-ray spectroscopy following the O-19(d, p)O-20 reaction at 8 AMeV. By exploiting the Doppler shift attenuation method, the lifetimes of the 2(2)(+) and 3(1)(+) states were firmly established. From the gamma-ray branching and E2/M1 mixing ratios for transitions deexciting the 2(2)(+) and 3(1)(+) states, the B(E2) and B(M1) were determined. Various chiral effective field theory Hamiltonians, describing the nuclear properties beyond ground states, along with a standard USDB interaction, were compared with the experimentally obtained data. Such a comparison for a large set of gamma-ray transition probabilities with the valence space in medium similarity renormalization group ab initio calculations was performed for the first time in a nucleus far from stability. It was shown that the ab initio approaches using chiral effective field theory forces are challenged by detailed high-precision spectroscopic properties of nuclei. The reduced transition probabilities were found to be a very constraining test of the performance of the ab initio models.
|
|
|
|
Tagliente, G. et al, Babiano-Suarez, V., Domingo-Pardo, C., Ladarescu, I., & Tain, J. L. (2024). High-resolution cross section measurements for neutron interactions on 89Y with incident neutron energies up to 95 keV. Eur. Phys. J. A, 60(1), 21–18pp.
Abstract: The cross section of the Y-89(n,gamma) reaction has important implications in nuclear astrophysics and for advanced nuclear technology. Given its neutron magic number N = 50 and a consequent small neutron capture crosssection,89Y represents one of the key nuclides for the stellars-process. It acts as a bottleneck in the neutron capture chain between the Fe seed and the heavier elements. Moreover, it is located at the overlapping region, where both the weak and mains-process components take place.Y-89, the only stable yttrium isotope, is also used in innovative nuclear reactors. Neutron capture and transmission measurements were per-formed at the time-of-flight facilities n_TOF at CERN and GELINA at JRC-Geel. Resonance parameters of individual resonances were extracted from a resonance analysis of the experimental transmission and capture yields, up to a neutron incident energy of 95 keV. Even though a comparison with results reported in the literature shows differences in resonance parameters, the present data are consistent with the Maxwellian averaged cross section suggested by the astro-physical database KADoNiS.
|
|
