A new method to reduce the statistical and systematic uncertainty of chance coincidence backgrounds measured with waveform digitizers

Abstract

A new method for measuring chance-coincidence backgrounds during the collection of coincidence data is presented. The method relies on acquiring data with near-zero dead time, which is now realistic due to the increasing deployment of flash electronicdigitizer (waveform digitizer) techniques. An experiment designed to use this new method is capable of acquiring more coincidence data, and a much reduced statistical fluctuation of the measured background. A statistical analysis is presented, and used to derive a figure of merit for the new method. Factors of four improvement over other analyses are realistic. The technique is illustrated with preliminary data taken as part of a program to make new measurements of the prompt fission neutron spectra at Los Alamos Neutron Science Center. It is expected that the these measurements will occur in a regime where the maximum figure of merit will be exploited.

Comparison of Results from Recent NNSA and CEA Measurements of the 239Pu(n, f) Prompt Fission Neutron Spectrum

“…The NNSA team used the asynchronous t 0 , fission, and outgoing neutron rates to determine the rate of random coincidences as described in Ref. (30). Both methods provide high-statistics measures of the random-coincidence background.…”

The 235U prompt fission neutron spectrum measured by the Chi-Nu project at LANSCE

“…In order to correct for random background events in the data, a new technique has been developed [13]. Since ChiNu uses an asynchronous readout using CAEN digitizers, it records all of the individual signals from each detector, only later using these data to construct coincidences between them.…”

Photon–electron coincidence experiments at synchrotron radiation facilities with arbitrary bunch modes

“…Since its first use in the 1920s, 1,2 coincident particle detection evolved to one of the most powerful tools in various disciplines, e.g., nuclear science, [3][4][5][6][7] high-energy particle physics, 6,[8][9][10] positronemission tomography, 11,12 astrophysics, 13,14 quantum communication, 15,16 or atomic and molecular physics, [17][18][19][20][21][22][23][24][25][26][27] and references therein. The simultaneous detection of multiple particles from decays of radioactive matter or following defined target-projectile interactions allowed the identification and quantification of distinct processes in experiments.…”