Measurement of the coulomb capture ratio of muons in 13 fluorides

A model is developed which suggests slow muon flux spectra of similar shapes in all alkali halides. The model is based on experimental values of muonic Lyman series intensities and Coulomb capture ratios. It is in good agreement with all the experimental information available at present. Current experimental studies [1] of the Coulomb capture of negative muons by the component atoms contained in chemical compounds or solution systems presently provide muonic X-ray spectra for the component elements. From summations of the total intensity in the respective K X-ray series, relative muon capture ratios, R(M/X), and concentration reduced atomic capture ratios, A (M/X), can be obtained for two component elements M and X. Additionally the alteration of the individual intensity patterns measured in the several series of a particular element with variation of the chemical state of this element have been reported. Vogel and coworkers [2] apparently have first explicitly attacked the problem of a concentration dependence of per-atom Coulomb capture ratios of negative muons by theoretical means. They reported studies of the capture by atoms in a condensed phase using a classical trajectory approach incorporating friction. From Monte Carlo calculations, they obtained results for the capture in model systems composed of individual atoms. In particular the capture ratios were calculated for the three systems neon/argon, neon/xenon, and argon/xenon of varying concentration. In spite of the varying screened Coulomb potentials and sizes of the two constituent atoms, these authors reported that the theoretical per atom capture ratios, A(M/X), were independent of relative concentration and noted that this result followed from the shape independence of their calculated timeaveraged muon flux energy spectrum P(E) =d 3 N(E)/dEdtdA, where N(E) is the total number of muons with an energy below E, t the time and A the cross section of * On leave from Princeton University, Princeton, N.J., USA a "flux measuring" sphere, to the concentration of the solution. Similar theoretical results have very recently been obtained by Leon [3] while an earlier theoretical treatment by Daniel [4] leading to the same conclusions, was performed in closed form. In this communication we note experimental data suggesting that a spectrum P(E) of a shape independent of the target composition holds for negative muons slowing down in all simple ionic crystalline alkali metal halides and make a test of this assumption.The usual model of simple alkali halide crystals is a cubic array of almost singly charged ions where each ion has a fixed intrinsic structure essentially unmodified by the particular type of counter ion. This model is supported by such diverse properties as the crystal lattice spacing systematics, densities, compressibilities and Madelung condensation energies [5]. If the further assumption is made of an invariant shape of (P)E in the sense that all functions P(E) are identical except for an energy-independent intensity scaling factor, then the ch...

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Measurement of the coulomb capture ratio of muons in 13 fluorides

Cited by 16 publications

References 6 publications

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