|
|
n_TOF Collaboration(Calviani, M. et al), Domingo-Pardo, C., & Tain, J. L. (2011). Fission Cross-section Measurements of (233)U, (245)Cm and (241,243)Am at CERN n_TOF Facility. J. Korean Phys. Soc., 59(2), 1912–1915.
Abstract: Neutron-induced fission cross-sections of minor actinides have been measured using the nTOF white neutron source at CERN. Geneva, as part of a large experimental program aiming at collecting new data relevant for nuclear astrophysics and for the design of advanced reactor systems. The measurements at nTOF take advantage of the innovative features of the n_TOF facility, namely the wide energy range, high instantaneous neutron flux and good energy resolution. Final results on the fission cross-section of (233)U, (245)cm and (243)Am from thermal to 20 MeV are here reported, together with preliminary results for (241)Am. The measurement have been performed with a dedicated Fast Ionization Chamber (FIC), a fission fragment detector with a very high efficiency, relative to the very well known cross-section of (235)U, measured simultaneously with the same detector.
|
|
|
|
n_TOF Collaboration, Kappeler, F., Mengoni, A., Mosconi, M., Fujii, K., Heil, M., et al. (2011). Neutron Studies for Dating the Universe. J. Korean Phys. Soc., 59(2), 2094–2099.
Abstract: The neutron capture cross sections of (186)Os and (187)Os are of key importance for defining the 8-process abundance of (187)Os at the formation of the solar system. This quantity can be used to determine the radiogenic abundance component of (187)Os from the decay of (187)Re (t(1/2) = 41.2 Gyr) and to infer the time-duration of the nucleosynthesis in our galaxy (Re/Os cosmochronometer). The neutron capture cross sections of (186)Os, (187)Os, and (188)Os have been measured at the CERN nTOF facility from 1 eV to 1 MeV, covering the entire energy range of astrophysical interest. From these data Maxwellian averaged capture cross sections have been calculated with uncertainties between 3.3 and 4.7%. Additional information was obtained by measuring the inelastic scattering cross section of (187)Os at the Karlsruhe 3.7 MV Van de Graaff accelerator and by neutron resonance analyses of the nTOF capture data to establish a comprehensive experimental basis for the Hauser-Feshbach statistical model. Consistent I-IF calculations for the capture and inelastic reaction channels were performed to determine the stellar enhancement factors, which are required to correct the Maxwellian averaged cross sections for the effect of thermally populated excited states. The consequences of this analysis for the s-process component of the (187)Os abundance and the related impact on the evaluation of the time-duration of Galactic nucleosynthesis via the Re/Os cosmo-chronometer are discussed.
|
|
|
|
n_TOF Collaboration(Lederer, C. et al), Domingo-Pardo, C., Giubrone, G., & Tain, J. L. (2013). Neutron Capture Cross Section of Unstable Ni-63: Implications for Stellar Nucleosynthesis. Phys. Rev. Lett., 110(2), 022501–5pp.
Abstract: The Ni-63(n, gamma) cross section has been measured for the first time at the neutron time-of-flight facility n_TOF at CERN from thermal neutron energies up to 200 keV. In total, capture kernels of 12 (new) resonances were determined. Maxwellian averaged cross sections were calculated for thermal energies from kT = 5-100 keV with uncertainties around 20%. Stellar model calculations for a 25M(circle dot) star show that the new data have a significant effect on the s-process production of Cu-63, Ni-64, and Zn-64 in massive stars, allowing stronger constraints on the Cu yields from explosive nucleosynthesis in the subsequent supernova.
|
|
|
|
n_TOF Collaboration(Guerrero, C. et al), Domingo-Pardo, C., Giubrone, G., & Tain, J. L. (2013). Performance of the neutron time-of-flight facility n_TOF at CERN. Eur. Phys. J. A, 49(2), 27–15pp.
Abstract: The neutron time-of-flight facility n_TOF features a white neutron source produced by spallation through 20 GeV/c protons impinging on a lead target. The facility, aiming primarily at the measurement of neutron-induced reaction cross sections, was operating at CERN between 2001 and 2004, and then underwent a major upgrade in 2008. This paper presents in detail all the characteristics of the new neutron beam in the currently available configurations, which correspond to two different collimation systems and two choices of neutron moderator. The characteristics discussed include the intensity and energy dependence of the neutron flux, the spatial profile of the beam, the in-beam background components and the energy resolution/broadening. The discussion of these features is based on dedicated measurements and Monte Carlo simulations, and includes estimations of the systematic uncertainties of the mentioned quantities.
|
|
|
|
n_TOF Collaboration(Zugec, P. et al), Domingo-Pardo, C., Giubrone, G., & Tain, J. L. (2014). Measurement of the C-12(n, p)B-12 cross section at n_TOF at CERN by in-beam activation analysis. Phys. Rev. C, 90(2), 021601–5pp.
Abstract: The integral cross section of the C-12(n, p)B-12 reaction has been determined for the first time in the neutron energy range from threshold to several GeV at the n_TOF facility at CERN. The measurement relies on the activation technique with the beta decay of B-12 measured over a period of four half-lives within the same neutron bunch in which the reaction occurs. The results indicate that model predictions, used in a variety of applications, are mostly inadequate. The value of the integral cross section reported here can be used as a benchmark for verifying or tuning model calculations.
|
|
