E. Morenzoni et al., CHARACTERISTICS OF CONDENSED GAS MODERATORS FOR THE GENERATION OF VERY SLOW POLARIZED MUONS, Journal of applied physics, 81(8), 1997, pp. 3340-3347
Motivated by the possibility of using condensed gas moderators to prod
uce very slow (epithermal) polarized muons we have studied the moderat
or properties of rare gas solids and solid N-2 thin films as a functio
n of the growing parameters (deposition temperature and rate, heat tre
atment) and of the film thickness. For Ar and Kt moderators the modera
tion efficiency is found to depend an the growth temperature and an an
nealing effect is observed. The dependence can be interpreted in terms
of the changes in granularity and porosity of I-he condensed gas laye
rs when the growth parameters are varied. From the thickness dependenc
e of the moderation efficiency the escape depth, of the very slow muon
s was determined, Its large value;indicates a suppression of electroni
c energy loss mechanisms for the epithermal muons. The rime dependent
decay properties of the moderators were also investigated and found to
depend solely on the rest gas pressure. At a pressure of 10(-10) mbar
the moderation efficiency remains stable over a period of days. (C) 1
997 American Institute of Physics.