n_TOF Collaboration(Massimi, C. et al), Domingo-Pardo, C., & Tain, J. L. (2012). Resonance neutron-capture cross sections of stable magnesium isotopes and their astrophysical implications. Phys. Rev. C, 85(4), 044615–15pp.
Abstract: We have measured the neutron capture cross sections of the stable magnesium isotopes Mg-24,Mg-25,Mg-26 in the energy range of interest to the s process using the neutron time-of-flight facility n_TOF at CERN. Capture events from a natural metal sample and from samples enriched in Mg-25 and Mg-26 were recorded using the total energy method based on (C6H6)-H-2 detectors. Neutron resonance parameters were extracted by a simultaneous resonance shape analysis of the present capture data and existing transmission data on a natural isotopic sample. Maxwellian-averaged capture cross sections for the three isotopes were calculated up to thermal energies of 100 keV and their impact on s-process analyses was investigated. At 30 keV the new values of the stellar cross section for Mg-24, Mg-25, and Mg-26 are 3.8 +/- 0.2 mb, 4.1 +/- 0.6 mb, and 0.14 +/- 0.01 mb, respectively.
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Yokoyama, R., Singh, M., Grzywacz, R., Keeler, A., King, T. T., Agramunt, J., et al. (2019). Segmented YSO scintillation detectors as a new beta-implant detection tool for decay spectroscopy in fragmentation facilities. Nucl. Instrum. Methods Phys. Res. A, 937, 93–97.
Abstract: A newly developed segmented YSO scintillator detector was implemented for the first time at the RI-beam Factory at RIKEN Nishina Center as an implantation-decay counter. The results from the experiment demonstrate that the detector is a viable alternative to conventional silicon-strip detectors with its good timing resolution and high detection efficiency for beta particles. A Position-Sensitive Photo-Multiplier Tube (PSPMT) is coupled with a 48 x 48 segmented YSO crystal. To demonstrate its capabilities, a known short-lived isomer in Ni-76 and the beta decay of Co-74 were measured by implanting those ions into the YSO detector. The half-lives and gamma-rays observed in this work are consistent with the known values. The beta-ray detection efficiency is more than 80 % for the decay of Co-74.
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Briz, J. A., Nacher, E., Borge, M. J. G., Algora, A., Rubio, B., Dessagne, P., et al. (2015). Shape study of the N = Z nucleus Kr-72 via beta decay. Phys. Rev. C, 92(5), 054326–10pp.
Abstract: The beta decay of the N = Z nucleus Kr-72 has been studied with the total absorption spectroscopy technique at ISOLDE (CERN). A total B(GT) = 0.79(4)g(A)(2)/4 pi has been found up to an excitation energy of 2.7 MeV. The B(GT) distribution obtained is compared with predictions from state-of-the-art theoretical calculations to learn about the ground state deformation of Kr-72. Although a dominant oblate deformation is suggested by direct comparison with quasiparticle random phase approximation (QRPA) calculations, beyond-mean-field and shell-model calculations favor a large oblate-prolate mixing in the ground state.
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Estevez Aguado, M. E. et al, Algora, A., Agramunt, J., Rubio, B., Tain, J. L., & Jordan, D. (2015). Shapes of Pb-192, Pb-190 ground states from beta-decay studies using the total-absorption technique. Phys. Rev. C, 92(4), 044321–8pp.
Abstract: The beta decay of Pb-192,Pb-190 has been studied using the total absorption technique at the ISOLDE (CERN) facility. The beta-decay strength deduced from the measurements, combined with QRPA theoretical calculations, allow us to infer that the ground states of the Pb-192,Pb-190 isotopes are spherical. These results represent the first application of the shape determination method using the total absorption technique for heavy nuclei and in a region where there is considerable interest in nuclear shapes and shape effects.
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n_TOF Collaboration(Guerrero, C. et al), Giubrone, G., & Tain, J. L. (2012). Simultaneous measurement of neutron-induced capture and fission reactions at CERN. Eur. Phys. J. A, 48(3), 29–9pp.
Abstract: The measurement of the capture cross-section of fissile elements, of utmost importance for the design of innovative nuclear reactors and the management of nuclear waste, faces particular difficulties related to the.-ray background generated in the competing fission reactions. At the CERN neutron time-of-flight facility nTOF we have combined the Total Absorption Calorimeter (TAC) capture detector with a set of three U-235 loaded MicroMegas (MGAS) fission detectors for measuring simultaneously two reactions: capture and fission. The results presented here include the determination of the three detection efficiencies involved in the process: epsilon(TAC)(n, f), epsilon(TAC)(n, gamma) and epsilon(MGAS)(n, f). In the test measurement we have succeeded in measuring simultaneously with a high total efficiency the U-235 capture and fission cross-sections, disentangling accurately the two types of reactions. The work presented here proves that accurate capture cross-section measurements of fissile isotopes are feasible at nTOF.
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