mu. /sup +/ charge exchange and muonium formation in low-pressure gases

Journal Article · Mon Nov 01 04:00:00 EST 1982 · Phys. Rev. A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.26.2527· OSTI ID:6511072

Fleming, D G; Mikula, R J; Garner, D M

Using the basic muon-spin-rotation technique, the fractions of energetic positive muons thermalizing in diamagnetic environments (f/sub ..mu../) or as the paramagnetic muonium atom (f/sub Mu/) have been measured in low-pressure pure gases (He, Ne, Ar, Kr, Xe, H/sub 2/, N/sub 2/, NH/sub 3/, and CH/sub 4/) as well as in several gas mixtures (Ne-Xe, Ne-Ar, Ne-NH/sub 3/, and Ne-CH/sub 4/). In the pure gases, the muonium fractions of f/sub Mu/ are generally found to be smaller than expected from analogous proton-charge-exchange studies, particularly in the molecular gases. This is probably owing to hot-atom reactions of muonium following the charge-exchange regime. Comparisons with muonium formation in condensed matter as well as positronium formation in gases are also presented. In the gas mixtures, the addition of only a few hundred parts per million of a dopant gas (e.g., Xe) which is exothermic for muonium formation gives rise to an f/sub Mu/ characteristic of the pure dopant gas itself, demonstrating the importance of the neutralization process right down to thermal energies. In all cases, the experimental signal amplitudes are found to be strongly pressure dependent, which is interpreted in terms of the time spent by the muon as neutral muonium in the charge-exchange regime t/sub n/<0.2 ns. This time is generally shorter in the case of molecular gases than in rare gases.

• Research Organization: Department of Chemistry and Tri-University Meson Facility, University of British Columbia, Vancouver, British Columbia V6T 1Y6, Canada
• OSTI ID: 6511072
• Journal Information: Phys. Rev. A; (United States), Journal Name: Phys. Rev. A; (United States) Vol. 26:5; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640303* -- Atomic
Molecular &amp; Chemical Physics-- Positronium
Muonium
&amp; Muonic &amp; Mesic Atoms &amp; Molecules
74 ATOMIC AND MOLECULAR PHYSICS
ALKANES
AMMONIA
ATOM COLLISIONS
BARYONS
BEAM NEUTRALIZATION
CHARGE EXCHANGE
CHARGED PARTICLES
CHARGED-PARTICLE REACTIONS
COLLISIONS
COMPARATIVE EVALUATIONS
DISPERSIONS
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
FLUIDS
GASES
HADRONS
HYDRIDES
HYDROCARBONS
HYDROGEN
HYDROGEN COMPOUNDS
ION COLLISIONS
ION-ATOM COLLISIONS
IONS
LEPTON REACTIONS
LOW PRESSURE
METHANE
MIXTURES
MUON REACTIONS
MUONIC IONS
MUONIUM
NITROGEN
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NONMETALS
NUCLEAR REACTIONS
NUCLEONS
ORGANIC COMPOUNDS
PARTICLE PRODUCTION
PRESSURE DEPENDENCE
PROTONS
RARE GASES