Muonic hydrogen and deuterium in H-D mixture and muon transfer in excited states

The deexcitation of µp and µd atoms in hydrogen-deuterium mixtures has been studied with a new kinetics model that takes the energy dependence of the cascade processes into account. The X-ray yields, the populations of atomic states, and the muon transfer from hydrogen to deuterium during the cascade have been calculated as functions of density and isotope fractions. The evolution of the kinetic energy distribution during the cascade is shown to play an important role in the transfer kinetics. The atomic energy distribution in the ground state is significantly changed by the transfer. The calculated X-ray yields and the muon transfer probabilities are in fair agreement with experimental data provided the current theoretical transfer rates are reduced by a factor of about 2.     

Measurement of the heavy neutrino admixture upper limit from muon capture by3He

The triton energy spectrum of the muon capture reaction µ³Het+_µ where µ³He is the ground state of muonic³He, has been measured by means of a high-pressure ionization chamber in order to investigate a possible heavyv admixture into the µ flavor with high sensitivity. The upper limit of the µ-heavy v_i mixing matrix element squared was obtained to be U_µi²10^–3 for heavy neutrino masses in the range of 25 E_0V75 MeV.     

Measurement of absolute yields of Lyman transitions in pionic hydrogen and deuterium as a function of pressure

Absolute yields ofK X-ray transitions in pionic hydrogen and deuterium were determined with accuracies of typically ±10% at target pressures of 2.8, 15 and 40 bar and compared with the results of a recently developed cascade code.Deceased     

Scattering of Light Exotic Atoms in Excited States

The scattering of light exotic atoms in excited states (n = 2–5) from hydrogen has been calculated in a close-coupling model. For the first time, the absorption cross sections for hadronic atoms due to Stark collisions have been calculated by taking the shifts and widths of the nS states into account in a self-consistent quantum mechanical framework. A classical-trajectory Monte Carlo method has been used to calculate the scattering of exotic atoms from molecular hydrogen for n≥8. The Coulomb transitions with Δn>1 are found to be the dominant deexcitation mechanism at the initial stage of the cascade.     

Study of μ-catalyzed fusion in H-D mixtures

Muon-catalyzed fusion was first observed in the pdμ system, and remains a good test of our understanding of the underlying molecular and nuclear processes. In contrast to the ddμ and dtμ systems, no resonant behavior is expected, which considerably simplifies the dynamics. We will discuss data taken with solid H-D mixtures of 0.05%, 2%, 15% and 75% D₂. In these measurements we observed simultaneously muons from pdμ→μ+ ³He and γs from pdμ→μ ³He + γ. A simulation code incorporating the relevant physics processes has been developed for the analysis of this data. Preliminary results are presented for the fusion and molecular formation rates. This new data stringently tests the currently-accepted fusion scheme. A new value of the astrophysical S-factor is derived. This revised version was published online in August 2006 with corrections to the Cover Date.     

Insights on d μ t sticking from d μ d stripping and μ,3He capture

Data from the recent PSI high statistics experiment on d μ d fusion are used to measure the stripping process in d μ d→ n+μ,³He and test current calculations of the stripping process. The PSI results in μ³He capture are also used to remove a troubling background from this measurement. Combination of these results with the old dμ t sticking analysis slightly raise and improve that result to ω_s= (0.58± 0.04)% and indicate that theory and experiment can meet if theoretical stripping is increased only at the beginning of the track. This conclusion is in accord with the new stripping calculations where excited state stripping is increased significantly. This revised version was published online in August 2006 with corrections to the Cover Date.     

Time-of-flight spectroscopy of muonic tritium

Emission of muonic tritium from a solid hydrogen layer has been studied via imaging of the muon-decay electrons and the time-of-flight distributions have been compared with detailed Monte Carlo calculations. Results are consistent at the 10% level with the theoretical prediction of a Ramsauer-Townsend minimum cross-section energy. This revised version was published online in August 2006 with corrections to the Cover Date.     

Pion absorption reactions on N, Ar and Xe

The absorption of π⁺ on Ar was studied at pion energies of 70, 118, 162, 239 and 330MeV, and on N and Xe at 239MeV. Twenty-six absorption reaction channels with at least two energetic charged particles in the final state have been evaluated. Partial cross-sections have been determined according to the number of protons, neutrons and deuterons in the final state. Received: 16 October 2000 / Accepted: 1 December 2000     

New Reflective Lens for an Ion Mirror of a Planar Multi-Reflection Time-of-Flight Mass Spectrometer

Technical Physics - A reflecting lens of a planar ionic mirror formed by a channel adjacent normal to the closing mirror lid is considered. The wide flange of the channel and lid of the mirror have...