MEASUREMENT OF THE MAIN CHARACTERISTICS OF PuBe AND 238PuBe NEUTRON SOURCES USING BONNER SPHERE SPECTROMETER WITH A 3He-COUNTER

• Main Authors: V. B. Ivanskyi, O. N. Letuchyy, А. N. Orobinskyi, H. V. Siroko
• Format: Article
• Language: English
• Published: V.N. Karazin Kharkiv National University Publishing 2017-08-01
• Series: East European Journal of Physics
• Subjects: NEMUS spectrometer on Bonner spheres; 3He neutron counter; shadow cone; neutron radiation spectrum; Bayes theorem; response function; likelihood function; MAXED method; maximum entropy and deconvolution method; Shannon entropy; Lagrange multiplier method
• Online Access: http://periodicals.karazin.ua/eejp/article/view/8959

The energy and pulse height spectrum of PuBe and 238PuBe neutron sources are measured without taking into account scattered radiation, taking into account this radiation (without the shadow cone) and own scattered radiation from these sources (with a shadow cone) using a NEMUS spectrometer on Bonner spheres with 3He -counter. An analytical solution of the likelihood function equation is given, taking into account the fact that the counting rate of pulses obeys the chi-square distribution used to estimate the variances, the discrete Poisson distribution, and the normal distribution, using the Bayes theorem and the Lagrange multiplier method. The values of the main characteristics of neutron radiation are measured: neutron flux density, ambient dose rate equivalent, individual dose rate equivalent and average neutron radiation energy. Extensive uncertainties were obtained in the measurement of these characteristics with a confidence level of 0.95. Calculation of energy spectrum, basic characteristics of neutron radiation and extended uncertainties is performed by the MAXED (maximum entropy and deconvolution) method using the UMG_3.3 software.