Guerrero, C., Tessler, M., Paul, M., Lerendegui-Marco, J., Heinitz, S., Maugeri, E. A., et al. (2019). The s-process in the Nd-Pm-Sm region: Neutron activation of Pm-147. Phys. Lett. B, 797, 134809–6pp.
Abstract: The Nd-Pm-Sm branching is of interest for the study of the s-process, related to the production of heavy elements in stars. As Sm-148 and Sm-150 are s-only isotopes, the understanding of the branching allows constraining the s-process neutron density. In this context the key physics input needed is the cross section of the three unstable nuclides in the region: Nd-147 (10.98 d half-life), Pm-147 (2.62 yr) and Pm-148 (5.37 d). This paper reports on the activation measurement of Pm-147, the longest-lived of the three nuclides. The cross section measurement has been carried out by activation at the SARAF LiLiT facility using a 56(2) μg target. Compared to the single previous measurement of Pm-147, the measurement presented herein benefits from a target 2000 times more massive. The resulting Maxwellian Averaged Cross Section (MACS) to the ground and metastable states in Pm-148 are 469(50) mb and 357(27) mb. These values are 41% higher (to the ground state) and 15% lower (to the metastable state) than the values reported so far, leading however to a total cross section of 826(107) mb consistent within uncertainties with the previous result and hence leaving unchanged the previous calculation of the s-process neutron density.
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n_TOF Collaboration(Lederer-Woods, C. et al), Domingo-Pardo, C., Tain, J. L., & Tarifeño-Saldivia, A. (2019). Measurement of Ge-73(n, gamma) cross sections and implications for stellar nucleosynthesis. Phys. Lett. B, 790, 458–465.
Abstract: Ge-73(n, gamma) cross sections were measured at the neutron time-of-flight facility n_TOF at CERN up to neutron energies of 300 keV, providing for the first time experimental data above 8 keV. Results indicate that the stellar cross section at kT = 30 keV is 1.5 to 1.7 times higher than most theoretical predictions. The new cross sections result in a substantial decrease of Ge-73 produced in stars, which would explain the low isotopic abundance of Ge-73 in the solar system.
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n_TOF Collaboration(Weiss, C. et al), Domingo-Pardo, C., Tain, J. L., & Tarifeño-Saldivia, A. (2015). The new vertical neutron beam line at the CERN n_TOF facility design and outlook on the performance. Nucl. Instrum. Methods Phys. Res. A, 799, 90–98.
Abstract: At the neutron Lime-of-flight facility n_TOF at CERN a new vertical beam line was constructed in 2014, in order to extend the experimental possibilities at this facility to an even wider range of challenging cross-section measurements of interest in astrophysics, nuclear technology and medical physics. The design of the beam line and the experimental hall was based on FLUKA Monte Carlo simulations, aiming at maximizing the neutron flux, reducing the beam halo and minimizing the background from neutrons interacting with the collimator or back-scattered in the beam dump. The present paper gives an overview on the design of the beam line and the relevant elements and provides an outlook on the expected performance regarding the neutron beam intensity, shape and energy resolution, as well as the neutron and photon backgrounds.
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n_TOF Collaboration(Gawlik, A. et al), Domingo-Pardo, C., Tain, J. L., & Tarifeño-Saldivia, A. (2021). Radiative Neutron Capture Cross-Section Measurement of Ge Isotopes at n_TOF CERN Facility and Its Importance for Stellar Nucleosynthesis. Acta Phys. Pol. A, 139(4), 383–388.
Abstract: This manuscript summarizes the results of radiative neutron capture cross-section measurements on two stable germanium isotopes, Ge-70 and Ge-73. Experiments were performed at the n_TOF facility at CERN via the time-of-flight technique, over a wide neutron energy range, for all stable germanium isotopes (70,72,73,74, and 76). Results for Ge-70 [Phys. Rev. C 100, 045804 (2019)] and Ge-73 [Phys. Lett. B 790, 458 (2019)] are already published. In the field of nuclear structure, such measurements allow to study excited levels close to the neutron binding energy and to obtain information on nuclear properties. In stellar nucleosynthesis research, neutron induced reactions on germanium are of importance for nucleosynthesis in the weak component of the slow neutron capture processes.
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n_TOF Collaboration(Cano-Ott, D. et al), Domingo-Pardo, C., & Tain, J. L. (2011). Neutron Capture Measuremetns on Minor Actinides at the n_TOF Facility at CERN: Past, Present and Future. J. Korean Phys. Soc., 59(2), 1809–1812.
Abstract: The successful development of advanced nuclear systems for sustainable energy production and nuclear waste management depends on high quality nuclear data libraries. Recent sensitivity studies and reports [1-3] have identified the need for substantially improving the accuracy of neutron cross-section data for minor actinides. The n_TOF collaboration has initiated an ambitious experimental program for the measurement of neutron capture cross sections of minor actinides. Two experimental setups have been constructed for this purpose: a Total Absorption Calorimeter (TAC) [4] for measuring neutron capture cross-sections of low-mass and/or radioactive samples and a set of two low neutron sensitivity C(6)D(6) detectors for the less radioactive materials.
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