| Summary: | A novel target system for films of solid hydrogen isotopes has enabled unique experiments
in muon catalyzed fusion. In order to understand the experimental data a knowledge of
target thickness and uniformity is essential, but only indirect information was available.
Conventional techniques for a thickness measurement do not apply, due to the limited
available space and cryogenic requirements of the system. In this thesis, a method of
thickness and uniformity measurement via the energy loss of alpha particles is presented.
A critical review of the literature on the stopping powers of alpha particles was necessary,
given no experimental data for solid hydrogen.
An absolute precision of ~5% at optimal condition was obtained in the thickness
determination. The uncertainty in the relative measurements can be less than 1%. The
average target thickness per unit gas input, weighted by the Gaussian beam profile of
FWHM 20-25 mm is determined to 3.29±0.16 μg/(cm²-torr-litre). A significant nonuniformity
in the thickness distribution was observed with an average deviation of about
7%. The linearity of deposited hydrogen thickness upon gas input was confirmed within
the accuracy. The cross contamination from the other side of the diffuser nozzle is found
to be less than 0.8 x 10- 3 with 90% confidence level. The result is compared to a Monte
Carlo study to understand deposition mechanism.
The importance of the stopping process in the alpha-sticking problem in muon catalyzed
D-T fusion is discussed in detail. The physical phase effect of the stopping power
of hydrogen may partly explain the discrepancy in the sticking values between theory
and experiment at high densities. The concept of a new experiment to measure directly
the sticking probability at high density is proposed. This offers certain advantages over LAMPF/RAL measurements. A Monte Carlo simulation of the experiment is performed.
A very preliminary result from a test run is presented. === Science, Faculty of === Physics and Astronomy, Department of === Graduate
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