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  • 1
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The phase information of triplet muonium signals has been used to measure the slowing down times of the positive muon in Ar. The results agree well with calculated stopping power based on proton data with the assumption that the positive muon and proton have the same stopping power at the same projectilew velocity (velocity scaling).
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Results of muon polarization studies in xenon and argon up to 60 atm are reported. In argon for pressures up to 10 atm, the muon polarization is best explained by an epithermalcharge exchange model. Above this pressure, the decrease inP D and increase inP L are ascribed to charge neutralization and spin exchange reactions, respectively, in the radiolysis track. Measurements with Xe/He mixtures with a xenon pressure of 1 atm indicate that the lost polarization in the pure xenon at this pressure is due to inefficient moderation of the muon. As the pressure in pure xenon is increased above 10 atm, we find thatP L remains roughly constant andP D begins to increase. The lost fraction may be due to the formation of a XeMu Van der Waals type complex, whileP D is ascribed to XeMu+ formation. This suggests that spur processes appear to be less important in xenon than in argon.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report on recent results obtained for longitudinal field (T 1) spin relaxation of the muonium-substituted (“muonated”) free radicals MuCO, MuC2F4, MuC2H3F, and MuC4H8 (t-butyl), comparing with results reported earlier for MuC2H4 (and MuC2D4). Some comparison with transverse field (T 2) data is also given. These data are fit to a phenomenological model based on NMR theory of spin relaxation in gases. The parameters of these fits are presented and discussed.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 87 (1994), S. 1023-1028 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present a collection of measurements of the muon and muonium asymmetries and relaxation parameters in cryocrystals of N2, CO, Xe,136Xe and Ne as functions of temperature. Generally, the fractions of the two species can be attributed to a competition between the formation of muonium or a diamagnetic species, where processes involving transport of spur electrons are important.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 32 (1986), S. 795-799 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The spin polarization of positive muons thermalized in Xe has been measured as a function of pressure up to 4660 Torr (6.1 atm) by the muon spin rotation (MSR) technique. At 4660 Torr, triplet muonium (F=1, M=1) accounts for about 40% of the initial muon polarization and no significant signal from diamagnetic muons has been observed. The unexpectedly slow recovery of the polarization in Xe at high pressures is discussed in conjunction with similar results seen in CCl4 and CHCl3 vapors.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 18 (1984), S. 703-708 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Our group at TRIUMF reported earlier a study of the spin exchange reactions of Mu with O2 and NO in the range 295 K to 478 K. We have extended the measurement with O2 to a low temperature region down to 88 K. From 135 K to 296 K, the spin depolarization rate constantk d(T) was found to vary according to the relative velocity of the colliding species,T 1/2, which indicates that the spin exchange cross section of Mu-O2 is temperature independent in this temperature range. The value ofk d(T) at 296 K is in good agreement with our earlier study. However, it was found that below 105 K and above 400 K,k d(T) tends to have stronger temperature dependences (T n , withn〉1/2). This deviation fromT 1/2-behavior can be attributed to the velocity (energy) dependence of the spin exchange cross section.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 85 (1994), S. 117-122 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present measurements of the transverse (T 2 −1 ) and longitudinal (T 1 −1 ) spin relaxation rates of muonium (Mu) atoms in solid natural xenon (n-Xe) as well as pure136Xe (which has no nuclear moments). The temperature dependences ofT 2 −1 andT 1 −1 in natural Xe belowT ∼ 115 K demonstrate the quantum character of Mu diffusion governed by one-phonon interactions. Taking into account both the polaron effect (PE) and the effect of fluctuational preparation of the barrier (FPB) makes it possible to consistently describe Mu diffusion in Xe. Mu spin relaxation in136Xe at high temperatures is not due to nuclear hyperfine (NHF) interactions.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of radioanalytical and nuclear chemistry 190 (1995), S. 493-503 
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Muonium (Mu=μ++e-) is the bound state of a positive muon and an electron. Since the positive muon has a mass about 1/9 of the proton, Mu can be regarded as an ultra light isotope of hydrogen with unusually large mass ratios (Mu∶H∶D∶T=1/9∶1∶2∶3). The muon spin rotation technique (μSR) relies on the facts that (1) the muon produced in pion decay, π+ → ∶+ + υ∶, is 100% spin polarized and (2) the positron from muon decay is emitted preferentially along the instantaneous muon spin direction at the time of the muon decay. In transverse field μSR (TF-μSR), the precession of the muon spin in muonium substituted radicals is directly observed by detecting decay positrons time differentially. From observed radical frequencies, the hyperfine coupling constants (A μ) of C2H4Mu, C2D4Mu,13C2H4Mu, C2F4Mu, and C2H3FMu are determined. In the longitudinal field avoided level crossing (LF-ALC) technique, one observes the resonant loss of the muon spin polarization caused by the crossing of hyperfine levels at particular magnetic fields. The LF-ALC method together with the information onA μ obtained from TF-μSR allows one to determine the magnitude and sign of the nuclear hyperfine constants at α- and β-positions. Results are compared with hydrogen substituted ethyl-radicals and isotope effects are discussed.
    Type of Medium: Electronic Resource
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