An accurate method to compute the annihilation rate in positronic systems by means of quantum Monte Carlo simulations is tested and compared with previously proposed methods using simple model systems. This method can be applied within all the quantum Monte Carlo techniques, just requiring to accumulate the positron-electron distribution function. The annihilation rate of eLiH as a function of ...

A simple method to calculate the total annihilation cross section of massive cold relics is presented. Exact expressions for arel, brel, and crel of σvrel = arel + brelv 2 rel + crelv 4 rel are obtained from simple derivatives of the squared annihilation amplitude. Three examples are given. In one example, the computed annihilation cross section of massive Dirac neutrinos confirms recent correc...

The ALPHA experiment has succeeded in trapping antihydrogen, a major milestone on the road to spectroscopic comparisons of antihydrogen with hydrogen. An annihilation vertex detector, which determines the time and position of antiproton annihilations, has been central to this achievement. This detector, an array of double-sided silicon microstrip detector modules arranged in three concentric cy...

annihilation or reduction of each kind of noise blended in correct data signals is a field that has attracted many researchers. it is a fact that fuzzy theory presents full capability in this field. fuzzy filters are often strong in smoothing corrupted signals, whereas they have simple structures. in this paper, a new powerful yet simple fuzzy procedure is introduced for sharpness reduction in ...

On the basis of phenomenological model of the orthopositronium annihilation ‘isotope anomaly’ in gaseous neon (lifetime spectra, positrons source Na) the realistic estimation of an additinal mode (∼ 0.2%) of the orthopositronium annihilation is received. PACS: 36.10.Dr, 13.90.+i, 06.09.+v In huge volume of the data on lifetime spectra of annihilation in substance of positrons from β-decay Na Na...

Positron two-dimensional angular correlation of annihilation radiation (2D ACAR), i.e., the 2D projection of the electron momentum densities sampled by positron, in Si is employed to verify the prediction of the density functional theory within the local-density approximation (LDA). Carefully conducted test shows that the LDA introduces small but definite discrepancies to the 2D-ACAR anisotropi...

It has been proposed that the excess in cosmic ray positrons, at approximately 8GeV, observed on both flights of the HEAT balloon experiment may be associated with the annihilation of supersymmetric (SUSY) dark matter particles in the Milky Way halo. In this paper we show how the presence of local dark matter substructure could account for this excess. Specifically, we concentrate on dark matte...