W. Prymas

Experimental survey of the sticking problem in muon catalyzed dt fusion

The “sticking” process dtμ → αμ + n, which constitutes the most severe limit to the number of fusions which a muon can catalyze, is reviewed. Many attempts were made to determine by calculations and measurements the probability for initial stickingωs0 (immediately after dtμ fusion) and for final stickingωs (after the αμ came to rest). Previous results based on neutron disappearance rates and on the observation of αμ-X-rays were controversial and also in some disagreement with theory. New data are reported from PSI on direct observation of final sticking, using a setup with the St. Petersburg ionization chamber. These data mark a significant improvement in reliability and may clarify questions concerning previous discrepancies. The new results isωs∼(0.56±0.04)%, lower than the theory predictionωs=(0.65±0.03)%, at medium density.

Muon catalyzed fusion in deuterium gas

AbstractWe present the results of an experiment performed at PSI to investigate muon catalyzed fusion in pure deuterium gas of 5% density (LHD) at temperatures ranging from 28 K to 350 K. Using a new high pressure ionization chamber the reactions dd → n + 3He and dd → p+t were observed with 100% detection efficiency. The rates of dμd formation were measured with the absolute precision of 1% and the μd spin-flip rates with 0.5%. The temperature dependence of molecular formation and spin-flip rates display pronounced resonance structures. A preliminary fit based on the Vesman mechanism of resonant muonic molecule formation was carried out yielding a dd fusion rate of 3.5·108 s-1 and a hfs splitting energy

Systematic analysis of the PSI experiment to directly measure the sticking probabilityωs in dt fusion

\delta \varepsilon _{d\mu d}

Experimental investigation of the muon transfer reaction from deuterium to helium isotopes

of 24.3 meV, both in good agreement with the theory.

PRECISION MEASUREMENT OF NUCLEAR MUON CAPTURE BY 3HE

The first direct measurement ofqls and its dependence on target density and deuterium concentration was performed in H/D (protium/deuterium) mixtures. Charge coupled devices (CCDs) were employed to detect the muonic hydrogen X rays. The presented preliminary results were obtained by determining the relative Kα-yields of both isotopes.

Final dt sticking? s using the ?survived moun method?

Starting in 1989 an experiment was run at PSI to directly measure the final sticking probability in muon catalyzed dt fusion. This experiment was based on an “active-target” ionization chamber (IC) built at Gatchina, Russia, and an array of plastic neutron counters. In three runs approximately 5×106 isolated alpha signals were recorded with around one half of these occurring in the inner chamber region where we have more complete understanding of the systematic errors. Particularly from a long run in 1992 we were able to obtain a very clean sticking peak of some 5000 μα events. However, to reach an accurate value of sticking, all systematic effects and several major backgrounds had to be understood in detail. To this end a Monte Carlo code was written to simulate the full electrostatic environment of the IC and to recreate completely each signal type including the actual tritium decay noise from the live experiment. A slightly model dependent value of approx. 0.56±0.04% is obtained for final sticking.

Hydrogen/deuterium-mixtures as a laboratory for the study of the muonic cascade and muon-catalyzed fusion

A new experiment was started at PSI aiming for high-precision and complete studies of dµd fusion in D2, HD and D2/H2 gas mixtures. A high-pressure ionization chamber surrounded by a set of neutron counters is used to observe dd-fusion at temperatures between 25 and 350 K. Here we report preliminary results from the first test run with pure D2 filling.

Final results on the mu He-3-capture experiment and perspectives for mu p-capture studies

Muon transfer from the ground state of muonic deuterium to a helium atom proceeds mainly via the formation of a muonic molecule in an excited state. A large number of decay X rays (∼ 6.8 keV) from these (dµHe)* molecules were observed for the4He as well as for the3He case. The time distributions of these X rays allow the determination of the ground state transfer rate. The simultaneous employment of Ge/Si-detectors and CCDs for the same target conditions allows the determination of the branching ratio of radiative to nonradiative decay for the first time.