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Manuscript Title: DYEFIC: LSC efficiency computation at the dynodic output of PMTs.
Authors: F. Ortiz, J.M. Los Arcos
Program title: DYEFIC
Catalogue identifier: ADAU_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 86(1995)123
Programming language: Fortran.
Computer: 286 type PC or higher.
Operating system: DOS 3.1 (or later).
RAM: 54K words
Word size: 16
Keywords: Nuclear physics, Activity detection, Liquid scintillators, Beta-decay, Counting efficiency, Photomultipliers.
Classification: 17.6.

Nature of problem:
The measurement of beta emitters by liquid scintillation counting involves a number of processes, namely the light production, photo- electron generation and dynodic amplification, which eventually convert the energy of the particle into an electric signal at the photo- multiplier (PMT) output. In order to perform accurate standardizations of radionuclide, the propagation of the effective efficiency through the different PMT stages must be know for single PMT systems and for equipments with two PMTs working in summed-coincidence mode.

Solution method:
The Fermi spectrum of each radionuclide is computed and analyzed in 250 energy channels. The average number of photoelectrons generated for each energy band and the corresponding non-detection probability are evaluated. The PMT response is obtained from a statistical iterative method developed to describe the transmission of the non-detection probability through the dynodes of the PMT. This method is based on the composition of the pertinent generating functions at each stage. The overall response of a two-PMT system is obtained by combination of the probabilities of each single component.

Poisson distribution is assumed for the response at each PMT stage. The photoelectron response of each energy band is evaluated through a figure of merit which comprises the interaction processes of the beta particle in a toluene scintillator and the subsequent generation of photo- electrons. The dynodes response is described by their respective dynodic gains. The final efficiency is obtained as a function of the figure of merit.

Unusual features:
The output results for each beta emitter are given in tabular form with two entries, figure of merit and its corresponding efficiency.

Running time:
0.28 s/efficiency value in a 16-MHz 286-system or 0.02 s/value in a 25-MHz 486 system, both with mathematical coprocessor.