221 research outputs found
Spatial confinement of muonium atoms
We report the achievement of spatial confinement of muonium atoms (the bound
state of a positive muon and an electron). Muonium emitted into vacuum from
mesoporous silica reflects between two SiO confining surfaces separated by
1 mm. From the data, one can extract that the reflection probability on the
confining surfaces kept at 100 K is about 90% and the reflection process is
well described by a cosine law. This technique enables new experiments with
this exotic atomic system and is a very important step towards a measurement of
the 1S-2S transition frequency using continuous wave laser spectroscopy.Comment: 5 pages, 6 figure
Formation of hydrogen impurity states in silicon and insulators at low implantation energies
The formation of hydrogen-like muonium (Mu) has been studied as a function of
implantation energy in intrinsic Si, thin films of condensed van der Waals
gases (N2, Ne, Ar, Xe), fused and crystalline quartz and sapphire. By varying
the initial energy of positive muons (mu+) between 1 and 30 keV the number of
electron-hole pairs generated in the ionization track of the mu+ can be tuned
between a few and several thousand. The results show the strong suppression of
the formation of those Mu states that depend on the availability of excess
electrons. This indicates, that the role of H-impurity states in determining
electric properties of semiconductors and insulators depends on the way how
atomic H is introduced into the material.Comment: 4 pages, 4 enscapulated postscript figures, uses revtex4 twocolumn
style to be published in Physical Review Letter
Measurement of the spatial extent of inverse proximity in a Py/Nb/Py superconducting trilayer using low-energy muon-spin rotation
The authors acknowledge the financial support of the EPSRC (Grant No. EP/J01060X).Muon-spin rotation has been used to observe directly the spatial variation of the magnetic flux density near the ferromagnetic-superconducting interface in a permalloy-niobium trilayer. Above the superconducting transition temperature Tc the profile of the induced magnetic flux density within the niobium layer has been determined. Below Tc there is a significant reduction of the induced flux density, predominantly near the ferromagnetic-superconducting interfaces. We are uniquely able to determine the magnitude and spatial variation of this reduction in induced magnetization due to the presence of the Cooper pairs, yielding the magnitude and length scale associated with this phenomenon. Both are inconsistent with a simple Meissner screening and indicate the existence of another mechanism, the influence of which is localized within the vicinity of the ferromagnetic interface.Publisher PDFPeer reviewe
- …