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n_TOF Collaboration(Mendoza, E. et al), Giubrone, G., & Tain, J. L. (2011). Improved Neutron Capture Cross Section Measurements with the n_TOF Total Absorption Calorimeter. J. Korean Phys. Soc., 59(2), 1813–1816.
Abstract: The n_TOF collaboration operates a Total Absorption Calorimeter (TAC) [1] for measuring neutron capture cross-sections of low-mass and/or radioactive samples. The results obtained with the TAC have led to a substantial improvement of the capture cross sections of (237)Np and (240)Pu [2]. The experience acquired during the first measurements has allowed us to optimize the performance of the TAC and to improve the capture signal to background ratio, thus opening the way to more complex and demanding measurements on rare radioactive materials. The new design has been reached by a series of detailed Monte Carlo simulations of complete experiments and dedicated test measurements. The new capture setup will be presented and the main achievements highlighted.
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n_TOF Collaboration(Paradela, C. et al), Domingo-Pardo, C., Plag, R., Plompen, A., & Tain, J. L. (2011). (237)Np(n,f) Cross Section: New Data and Present Status. J. Korean Phys. Soc., 59(2), 1908–1911.
Abstract: In this document, we present the final result obtained at the nTOF experiment; for the neutron-induced fission cross section of the (237)Np, from the fission threshold up to 1 GeV. The method applied to get tins result is briefly discussed. nTOF data are compared to the last experimental measurements using other TOF facilities or the surrogate method, reported experiments performed with monoenergetic sources and the FISCAL systematic, including a discussion about the existing discrepancies.
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Tain, J. L. et al, Algora, A., Estevez, E., Rubio, B., Valencia, E., & Jordan, D. (2011). Beta Decay Studies of Neutron Rich Nuclei Using Total Absorption Gamma-ray Spectroscopy and Delayed Neutron Measurements. J. Korean Phys. Soc., 59(2), 1499–1502.
Abstract: A complete characterisation of the beta-decay of neutron-rich nuclei can be obtained from the measurement of beta-delayed gamma rays and, whenever the process is energetically possible, beta-delayed neutrons. The accurate determination of the beta-intensity distribution and the beta-delayed neutron emission probability is of great relevance in the fields of reactor technology and nuclear astrophysics. A programme for combined measurements using the total absorption gamma-ray spectroscopy technique and both neutron counters and neutron time-of-flight spectrometers is presented.
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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.
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Yoshida, T., Hagura, N., Umezu, R., Algora, A., Tain, J. L., Jordan, D., et al. (2011). Impact of TAGS Measurement on FP Decay Data and Decay Heat Calculations. J. Korean Phys. Soc., 59(2), 1543–1546.
Abstract: Nuclear level schemes are usually constructed from the high-resolution data of the gamma-ray transitions which immediately follow the beta-decay of their parents. It is recognized that this procedure may lead to the “pandemonium problem”. If we use the decay data suffering from the pandemonium problem for the decay heat calculations the beta-ray component will be overestimated and the gamma-ray component underestimated. The beta-feeding data obtained by the total absorption gamma-ray spectroscopy (TAGS) is proved to be free from this problem. In the case of the Japanese data base for the FP decay heat calculation, the theoretical values based on the gross theory of beta-decay are widely introduced to circumvent the pandemonium problem. The gross theory, however, is not good at describing any beta-transition exclusively concentrating to a single level in the daughter nucleus. The TAGS method is also proved to be able to save this situation. Further, we have to change our comprehension over the currently published decay schemes.
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