Determination of fission rate by mean last passage time

2004 ◽  
Vol 69 (2) ◽  
Author(s):  
Jing-Dong Bao ◽  
Ying Jia
Keyword(s):  
Passage Time ◽  
Fission Rate ◽  
Last Passage Time

scholarly journals Last-Passage Time for Linear Diffusions and Application to the Emptying Time of a Box

2020 ◽  
Vol 181 (5) ◽  
pp. 1565-1602
Author(s):  
Alain Comtet ◽  
Françoise Cornu ◽  
Grégory Schehr
Keyword(s):  
Passage Time ◽  
Last Passage Time ◽  
Linear Diffusions ◽  
Emptying Time

scholarly journals Determination of the fast-neutron-induced fission cross-section of 242Pu at nELBE

2018 ◽  
Vol 169 ◽  
pp. 00009
Author(s):  
Toni Kögler ◽  
Roland Beyer ◽  
Arnd R. Junghans ◽  
Ronald Schwengner ◽  
Andreas Wagner
Keyword(s):  
Fast Neutron ◽  
Cross Section ◽  
Neutron Transport ◽  
Fission Cross Section ◽  
Data Sets ◽  
Fission Rate ◽  
Relative Cross Section ◽  
Neutron Time ◽  
Induced Fission

The fast-neutron-induced fission cross section of 242Pu was determined in the energy range of 0.5 MeV to 10MeV at the neutron time-of-flight facility nELBE. Using a parallel-plate fission ionization chamber this quantity was measured relative to 235U(n,f). The number of target nuclei was thereby calculated by means of measuring the spontaneous fission rate of 242Pu. An MCNP 6 neutron transport simulation was used to correct the relative cross section for neutron scattering. The determined results are in good agreement with current experimental and evaluated data sets.

scholarly journals Sparre Andersen identity and the last passage time

2016 ◽  
Vol 53 (2) ◽  
pp. 600-605 ◽  
Author(s):  
Jevgenijs Ivanovs
Keyword(s):  
Random Walks ◽  
Uniform Distribution ◽  
Lévy Processes ◽  
Passage Time ◽  
Levy Processes ◽  
Last Passage Time ◽  
Random Times

AbstractIt is shown that the celebrated result of Sparre Andersen for random walks and Lévy processes has intriguing consequences when the last time of the process in (-∞, 0], say σ, is added to the picture. In the case of no positive jumps this leads to six random times, all of which have the same distribution—the uniform distribution on [0, σ]. Surprisingly, this result does not appear in the literature, even though it is based on some classical observations concerning exchangeable increments.

AN AUTOMATED METHOD FOR THE DETERMINATION OF URINARY 17-HYDROXYCORTICOSTEROIDS

1967 ◽  
Vol 38 (4) ◽  
pp. 363-374 ◽  
Author(s):  
J. D. CAISEY ◽  
K. J. CHILD
Keyword(s):  
Aqueous Solution ◽  
Periodate Oxidation ◽  
Passage Time ◽  
Borohydride Reduction ◽  
Reaction Products ◽  
Automated Method ◽  
Adequate Accuracy ◽  
Working Day

SUMMARY An automated method for measuring urinary 17-hydroxycorticosteroids is described. The preliminary borohydride reduction of pre-existing 17-oxo-steroids is performed manually and the reduced urine transferred to the sample cups of an Auto-Analyzer. The urine is submitted to periodate oxidation, mild alkaline hydrolysis and then extracted with dichloromethane. The dichloromethane extract is mixed with an aqueous solution of m-dinitrobenzene in hyamine and the mixture passed through a 'solvent exchanger' at 75° to evaporate the dichloromethane. Alkali is added and the Zimmermann reaction performed at 55°. After extraction of the reaction products into n-hexanol their light absorption is measured at 510 mμ. The method has been evaluated for accuracy, precision, sensitivity and validity. Urine samples can be assayed in duplicate at the rate of 5/hr. with adequate accuracy. Passage time through the automated procedure is 36 min.; thus 30 to 40 samples can easily be assayed in a normal working day. Details are given of the recovery of cortisone from urine and of comparison between the results obtained with the automated method and with a manual method. The choice of cortisone as the standard, and the role of the temperature and the pH maintained during periodate oxidation are discussed.

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