Search results for "Muon"
showing 10 items of 1376 documents
Spin asymmetriesA1of the proton and the deuteron in the lowxand lowQ2region from polarized high energy muon scattering
1999
We present the results of the spin asymmetries (Formula presented) of the proton and the deuteron in the kinematic region extending down to (Formula presented) and (Formula presented) The data were taken with a dedicated low x trigger, which required hadron detection in addition to the scattered muon, so as to reduce the background at low x. The results complement our previous measurements and the two sets are consistent in the overlap region. No significant spin effects are found in the newly explored region. © 1999 The American Physical Society.
BACKGROUND FOR (μ-, e-) CONVERSION IN NUCLEI FROM MUON DECAY IN ORBIT
1993
A reanalysis of the problem of μ- decay in orbit is done in order to estimate backgrounds for (μ-, e-) conversion. Some approximations are done in order to obtain a very simple formula for the decay rate close to the maximum electron energy. Comparison with more sophisticated approaches leads to differences in the results which cannot be easily interpreted in terms of the approximations which has been done so far. In view of the relevance of this reaction in the planning of (μ-, e-) conversion experiments we point out at the convenience of some independent accurate evaluation.
Muonic radioactive atoms - a unique probe for nuclear structure
2004
Muonic atoms have been a source of high-precision experimental nuclear structure data for decades, through muonic X-rays that yield information on nuclear charge distributions. The intense driver beams for production of radioactive beams in so-called second generation facilities will simultaneously be capable of producing unprecedented amounts of low-energy muons. This paper concerns some of the potential synergies of combining unions with radioactive nuclei. as one possible new tool to be used at future RIB facilities. As a case study, muonic capture rates into highly excited states in Ni-78 have been calculated.
New measurement of the K±→π±μ+μ− decay
2011
Abstract A sample of 3120 K ± → π ± μ + μ − decay candidates with ( 3.3 ± 0.7 ) % background contamination has been collected by the NA48/2 experiment at the CERN SPS, allowing a detailed study of the decay properties. The branching ratio was measured to be BR = ( 9.62 ± 0.25 ) × 10 − 8 . The form factor W ( z ) , where z = ( M μ μ / M K ) 2 , was parameterized according to several models. In particular, the slope of the linear form factor W ( z ) = W 0 ( 1 + δ z ) was measured to be δ = 3.11 ± 0.57 . Upper limits of 2.9 × 10 − 2 and 2.3 × 10 − 2 on possible charge asymmetry and forward–backward asymmetry were established at 90% CL. An upper limit BR ( K ± → π ∓ μ ± μ ± ) 1.1 × 10 − 9 was e…
Microscopic study of muon-capture transitions in nuclei involved in double-beta-decay processes
2003
Abstract Total and partial ordinary muon-capture (OMC) rates to 1 + and 2 − states are calculated in the framework of the proton–neutron quasiparticle random-phase approximation (pnQRPA) for several nuclei involved in double-beta-decay processes. The aim is to obtain information on intermediate states involved in double-beta-decay transitions having these nuclei as either daughter or parent nuclei. It is found that the OMC observables, just like the 2 νββ -decay amplitudes, strongly depend on the particle–particle part of the proton–neutron interaction. First experiments measuring the partial OMC rates for nuclei involved in double beta decays have recently been performed.
Nucleon structure functions from deep inelastic muon scattering
1992
Abstract Recent experimental results from the CERN NA37 (NMC) experiment on deep inelastic muon scattering on hydrogen and deuterium are presented. Absolute structure functions have been measured at 90 and 280 GeV incident energy covering the kinematical range 0.006 2 2 . The new results help to resolve the severe discrepancies between the data of the previous experiments. In addition data on the structure function ratio F 2 n /F 2 p are reviewed. Evidence for a non-leading twist at × ⪆ 0.20 is extracted from the Q 2 dependence of the structure function ratio. Its effect on the determination of the Gottfried sum rule is discussed.
Muon capture in deuterium and the meson exchange current effect
1990
Abstract One-meson exchange current effect in reaction μ − + d → 2 n + v μ is calculated by using the weak axial current operator which satisfies the nuclear continuity equation up to the order 1 M 2 ( M is the nucleon mass). In the vector part of the weak nuclear interaction the vector-isovector pion exchange currents are also included. Their contribution is found to be non-negligible. The nuclear wave functions are generated from the Paris, Reid soft-core and Bonn potential models. Our result is compatible with the previous one, obtained with only the static axial exchange currents included.
Estimation of bounds for left-right mixing from nuclear double beta decay processes
1993
Abstract Nuclear matrix elements, extracted from a systematic calculation of neutrinoless double beta decay rates for 0 + g.s →o + g.s transitions in 76 Ge, 82 Se, 128 Te, 130 Te and 136 Xe, have been used to compute bounds on the left-right mixing angle ζ of the weak currents. The parameters of the nuclear model have been fixed by calculating the corresponding two-neutrino double beta decay half lives. The present analysis favours a mixing of the order of |tanξ| −3 which is to be compared with those obtained in muon decay (|tan ξ | ⩽ 0.035) and in supernova (|tan ξ | ⩽ 10 −5 ) analysis. It shows that nuclear structure calculations yield estimates on ξ which complement the existing data.
Coherent and incoherent (μ−, e−) conversion in nuclei
1993
Coherent and incoherent (μ−, e−) conversion in nuclei is studied within the framework of several theories which violate flavour lepton number. A useful approach is followed which allows a factorization of the conversion widths into nuclear factors and other factors which depend only on the elementary process. The nuclear factors are evaluated in a wide range of nuclei allowing simple calculations of the conversion rates throughout the periodic table for a given theory with a minimum of work in the elementary sector. The coherent conversion is found to dominate the process. The results obtained modify appreciable previous results in the literature, particularly in the incoherent process.
Nuclear transition rates in μ-catalyzedp-dfusion
1991
Nuclear transition rates in \ensuremath{\mu}-catalyzed p-d fusion have been calculated using numerically converged $^{3}\mathrm{He}$ bound-state and p-d scattering wave functions for the first time. The transition rates for M1 radiative capture in both quartet and doublet initial states have been computed using a model of meson-exchange currents which reproduces the thermal n-d capture cross section, and are in excellent agreement with experiment. The muon internal-conversion rate is in very good agreement with a recent reanalysis of old bubble-chamber measurements. Furthermore, our nonvanishing quartet capture rate resolves the anomaly in the Wolfenstein-Gerstein effect.