Neutron multiplication measurements using moments of the neutron counting distribution

Variance results for the second and third reduced sample moments in neutron multiplicity counting for randomly triggered or signal-triggered counting gates

“…The extent to which the sample and detector obey the ''point model'' assumptions [2][3][4][5] impacts the total measurement error in the estimate of the spontaneous fission rate. But in nearly all cases, for the random error contribution, it is useful to evaluate the variances of the second and third reduced sample moments as defined below.…”

“…Neutron multiplicity counting is an established method to estimate the spontaneous fission rate, and therefore the Plutonium mass for example, in a sample that includes other neutron sources [1][2][3]. The probability distribution describing the number of neutrons detected in a short time window (256 ms for example) is typically summarized by its first few moments.…”

Determination of neutron multiplication of subcritical HEU systems using delayed neutrons

“…We have applied the reduced variance method of analysis developed initially by Feynman et al [4], and used by other investigators [1,2], of spontaneous fissioning systems. The time history of the neutron events recorded in the PATRM module is examined to construct the Feynman histograms, FN ORDER , formed by randomly opening an inspection time interval of fixed width and then counting the number of neutron signals that are present within this time interval.…”

“…The 240 Pu is evenly distributed throughout the volume of the plutonium. Point kinetic models [1][2][3][4] that use multiplicity analyses of the observed neutron detection-time distributions have been successfully applied to determine the multiplication of subcritical plutonium systems.…”

“…The neutron detection times are recorded and subsequently analyzed with the Feynman reducedvariance method [2,4]. This analysis provides a measure of the number of ''single,'' ''double,'' and…”