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Manuscript Title: CHEREN, the Cherenkov counting efficiency.
Authors: A. Grau Carles, A. Grau Malonda
Program title: CHEREN
Catalogue identifier: ADIE_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 111(1998)258
Programming language: Fortran.
Computer: IBM AT.
Operating system: MS-DOS.
RAM: 22K words
Word size: 32
Keywords: Nuclear physics, Particle detection, Radioactivity, Cherenkov counting, Beta-decay, Shape factor, Liquid-scintillation Counting.
Classification: 17.5.

Nature of problem:
Although the commercial liquid-scintillation counters are efficient Cherenkov light detectors, experimentalists commonly prefer to apply liquid scintillators, because the detection efficiency is always higher. However, Cherenkov counting techniques may be comparatively advantageous in certain situations in which the use of a liquid scintillation cocktail is not feasible. In particular, the ability to recover the radioactive sample unaltered, and the possibility to enhance the total volume of radioactive substance added into the vials are particularly interesting. Also the threshold condition for the emission of Cherenkov radiation can be applied as a powerful tool to discriminate electron energies below the threshold energy.

Solution method:
The ratio of detected to emitted particles (i.e., the Cherenkov counting efficiency) is separated into a product of two terms; the Cherenkov yield and the intrinsic Cherenkov counting efficiency. The Cherenkov yield is defined as the ratio of beta particles that, according to the Fermi theory of beta disintegration, are over the Cherenkov threshold energy. The intrinsic Cherenkov counting efficiency, on the other hand, contains all variables that depend on the measurement conditions. Also we introduce the concept of the detection probability function to include all the experimental variables that affect to the Cherenkov counting efficiency.

The application of the detection probability function to other nuclides requires one to maintain the measurement conditions applied to the standards of 36Cl and 32P. Therefore, the sample volume, the acid and carrier concentrations, and the vial material cannot be modified throughout the experiments. The standardization of beta-gamma-emitters is restricted to radionuclides for which the contribution of the Compton electrons to the total Cherenkov counting efficiency can be considered negligible (i.e., less than 2% for coincident decay schemes). For instance, the program does not include the nuclides 60Co or 137Cs, because the beta-particle and gamma-ray contributions are of the same order.

Running time:
The test run requires about 10 minutes on an IBM AT.