Title: Highly accurate measurements of the spontaneous fission half-life of 240,242Pu
Authors: SALVADOR CASTINEIRA PAULABRYS TOMASZEYKENS ROGERHAMBSCH Franz-JosefMOENS AndreOBERSTEDT StephanSIBBENS GoedeleVANLEEUW DAVIDVIDALI MarzioPRETEL C.
Citation: PHYSICAL REVIEW C vol. 88 no. 6 p. 064611
Publisher: AMER PHYSICAL SOC
Publication Year: 2013
JRC N°: JRC90589
ISSN: 0556-2813
URI: http://journals.aps.org/prc/abstract/10.1103/PhysRevC.88.064611
http://publications.jrc.ec.europa.eu/repository/handle/JRC90589
DOI: 10.1103/PhysRevC.88.064611
Type: Articles in periodicals and books
Abstract: Fast spectrum neutron-induced fission cross-section data for transuranic isotopes are of special demand from the nuclear data community. In particular highly accurate data are needed for the new generation IV nuclear applications. The aim is to obtain precise neutron-induced fission cross sections for 240Pu and 242Pu. To do so, accurate data on spontaneous fission half-lives must be available. Also, minimizing uncertainties in the detector efficiency is a key point. We studied both isotopes by means of a twin Frisch-grid ionization chamber with the goal of improving the present data on the neutron-induced fission cross section. For the two plutonium isotopes the high α-particle decay rates pose a particular problem to experiments due to piling-up events in the counting gas. Argon methane and methane were employed as counting gases, the latter showed considerable improvement in signal generation due to its higher drift velocity. The detection efficiency for both samples was determined, and improved spontaneous fission half-lives were obtained with very low statistical uncertainty (0.13% for 240Pu and 0.04% for 242Pu): for 240Pu, T1/2,SF = 1.165 × 1011 yr (1.1%), and for 242Pu, T1/2,SF = 6.74 × 1010 yr (1.3%). Systematic uncertainties are due to sample mass (0.4% for 240Pu and 0.9% for 242Pu) and efficiency (1%).
JRC Directorate:Health, Consumers and Reference Materials

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