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A. Algora,D. Jordan,J. L. Tain,B. Rubio,J. Agramunt,L. Caballero,E. Nacher,A. B. Perez-Cerdan,F. Molina,A. Krasznahorkay,M. D. Hunyadi,J. Gulyas,A. Vitez,M. Csatlos,L. Csige,J. Aysto,H. Penttila,S. Ri 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
The decay heat of fission products plays an important role in predictions of the heat released by nuclear fuel in reactors. In this contribution we present results of the analysis of the measurement of the beta decay of some refractory isotopes that were considered possible important contributors to the decay heat in reactors. The measurements presented here were performed at the IGISOL facility of the University of Jyvakyla Finland. In our measurements we have combined for the first time a Penning trap (JYFLTRAP), which was used as a high resolution isobaric separator, with a total absorption spectrometer. The results of the measurements as well as their consequences for decay heat summation calculations are discussed.
Monte Carlo Simulations for the Study of a Moderated Neutron Detector
M. B. Gomez Hornillos,V. Gorlychev,R. Caballero,G. Cortes,A. Poch,C. Pretel,F. Calvino,J. L. Tain,A. Algora,J. Agramunt,D. Cano-Ott,T. Martinez,E. Mendoza,J. Rissanen,J. Aysto,A. Jokinen,T. Eronen,I. 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
This work presents the Monte Carlo simulations performed with the MCNPX and GEANT4 codes for the design of a BEta deLayEd Neutron detector, BELEN-20. This detector will be used for the study of beta delayed neutron emission and consists of a block of polyethylene with dimensions 90 × 90 × 80 cm ^3 and 20 cylindrical ^3He gas counters. The results of these simulations have been validated experimentally with a ^(252)Cf source in the laboratory at UPC, Barcelona. Also the first experiment with this detector has been carried out in November 2009 in JYFL, Finland. In this experiment the neutron emission probability after beta decay of the fission products ^(88)Br, ^(94,95)Rb and ^(138)I has been measured; this data is still under analysis. Simulations with MCNPX and GEANT4 have been performed in order to obtain the efficiency of the BELEN-20 detector for each of the above nuclei using the neutron energy distribution corresponding to each nucleus.
J. L. Tain,A. Algora,E. Estevez,B. Rubio,E. Valencia,D. Jordan,J. Aysto,T. Eronen,A. Jokinen,I. Moore,H. Pentilla,J. Riisanen,L. Batist,M. Bowry,M. Bunce,W. Gelletly,R. Caballero,G. Cortes,B. Gomez-Ho 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
A complete characterisation of the β-decay of neutron-rich nuclei can be obtained from the measurement of β-delayed gamma rays and, whenever the process is energetically possible, β-delayed neutrons. The accurate determination of the β-intensity distribution and the β-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.
Impact of TAGS Measurement on FP Decay Data and Decay Heat Calculations
T. Yoshida,N. Hagura,R. Umezu,A. Algora,J. L. Tain,D. Jordan,T. Tachibana 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
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 ``\textit{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.