120675862
Surface interactions of muonium in oxide powders at low temperatures
Measurements of muonium (..mu../sup +/e/sup -/) spin relaxation in finely powdered samples of Al/sub 2/O/sub 3/, MgO, and SiO/sub 2/ indicate that the muonium atoms escape the powder grains with a high efficiency, regardless of the ambient temperature of the powder. In Al/sub 2/O/sub 3/ powder in a pure He (or Ne) atmosphere at low temperature (T<30 K), the muonium spin relaxation rate is proportional to the fraction of the powder surface area not covered by adsorbed He (Ne); it is postulated that a He (Ne) film on the powder surfaces protects muonium against depolarizing collisions with the bare Al/sub 2/O/sub 3/ surfaces.
56523859
Production of thermal muonium in the vacuum between the grains of fine silica powders
Abstract When spin-polarized positive muons are stopped in fine SiO 2 powder under vacuum, muonium precession is observed indicating 45% muonium formation. Depolarization by oxygen indicates that muonium, like positronium, emerges from the powder grains into the voids.
93893855
Muon catalyzed fusion at very low temperature:a new target system
119275815
Precise measurement of parity violation in polarized muon decay
We present a new high precision measurement of parity violation in the weak interaction, using polarized muon decay. The TWIST collaboration has measured $P_\mu^\pi \xi$, where $P_\mu^\pi$ is the polarization of the muon in pion decay and $\xi$ describes the intrinsic asymmetry in muon decay. We find $P_\mu^\pi \xi = 1.00084 \pm 0.00029\,(\textrm{stat.})_{-0.00063}^{+0.00165}\,(\textrm{syst.})$, in good agreement with the standard model prediction of $P_\mu^\pi=\xi=1$. Our result is a factor of 7 more precise than the pre-TWIST value, setting new limits in left-right symmetric electroweak extensions to the standard model.
37256736
Drift chambers for a precision measurement of the Michel parameters in muon decay
Planar drift chambers will be used in a solenoidal magnetic field to measure the Michel parameters in muon decay. The chamber manufacture procedure uses flat glass tables and precise ceramic glass spacers to provide precise anode– cathode spacing. Results of bench and beam tests of the prototype chambers are discussed. # 2001 Elsevier Science B.V. All rights reserved.
120675862
Surface interactions of muonium in oxide powders at low temperatures
Measurements of muonium (..mu../sup +/e/sup -/) spin relaxation in finely powdered samples of Al/sub 2/O/sub 3/, MgO, and SiO/sub 2/ indicate that the muonium atoms escape the powder grains with a high efficiency, regardless of the ambient temperature of the powder. In Al/sub 2/O/sub 3/ powder in a pure He (or Ne) atmosphere at low temperature (T<30 K), the muonium spin relaxation rate is proportional to the fraction of the powder surface area not covered by adsorbed He (Ne); it is postulated that a He (Ne) film on the powder surfaces protects muonium against depolarizing collisions with the bare Al/sub 2/O/sub 3/ surfaces.
119192638
The galactic center region gamma ray excess from a supersymmetric leptophilic Higgs model
In a recent paper by Hooper and Goodenough, data from the Fermi Gamma Ray Telescope was analyzed and an excess of gamma rays was claimed to be found in the emission spectrum from the Galactic Center Region. Hooper and Goodenough suggest that the claimed excess can be well explained by 7-10 GeV annihilating dark matter with a power law density profile if the dark matter annihilates predominantly to tau pairs. In this paper we present such a dark matter model by extending the MSSM to include four Higgs doublets and one scalar singlet. A $ {\mathbb{Z}_2} $ symmetry is imposed that enforces a Yukawa structure so that the up quarks, down quarks, and leptons each receive mass from a distinct doublet. This leads to an enhanced coupling of scalars to leptons and allows the model to naturally achieve the required phenomenology in order to explain the gamma ray excess. Our model yields the correct dark matter thermal relic density and avoids collider bounds from measurements of the Z width as well as direct production at LEP.