Related papers: Orthopositronium: Annihilation of positron in gase…
The anomalous bump in the cosmic ray positron to electron ratio at $10 GeV$ can be explained as being a component from a point source that was originally harder than the primary electron background and degrades due to synchrotron and…
We discuss challenges to a dark matter annihilation interpretation of the excess positron fraction in the cosmic rays observed by the PAMELA, Fermi-LAT and AMS-02 collaborations. The spectra of positrons from annihilations into the leptonic…
Radioactive nuclei, especially those created in SN explosion, have long been suggested to be important contributors of galactic positrons. In this paper we describe the findings of three independent OSSE/SMM/TGRS studies of positron…
Calculations of gamma spectra for positron annihilation on a selection of molecules, including methane and its fluoro-substitutes, ethane, propane, butane and benzene are presented. The annihilation gamma spectra characterise the momentum…
Two different model-independent mapping techniques have been applied to OSSE, SMM, TGRS and balloon data and reveal a feature in the 0.511 MeV electron-positron annihilation radiation pattern of our galaxy centered roughly at l=-2 deg. and…
The Double Chooz experiment measures the neutrino mixing angle $\theta_{13}$ by detecting reactor $\bar{\nu}_e$ via inverse beta decay. The positron-neutron space and time coincidence allows for a sizable background rejection, nonetheless…
The lifetime of the metastable 3P2 state of neon has been determined to 14.70(13) s (decay rate 0.06801(62) 1/s) by measuring the decay in fluorescence of an ensemble of Ne-20 atoms trapped in a magneto-optical trap (MOT). Due to low…
We present a calculation of the branching ratio of orthopositronium decay into an invisible mode, which is done in the context of Mirror World models, where ordinary positronium can disappear from our world due to oscillation into its…
We investigate one-photon annihilation of the electron-positron pair in the field of a central, very heavy and positively charged atomic nucleus. The explicit formula for the annihilation rate of this process $\Gamma^{(b)}_{1 \gamma}$ is…
Expansion of Standard Model for the quantitative description of the orthopositronium lifetime anomalies (from QED to supersymmetric QED) allows to formulate experimental tests of supervision of additional realization of the supersymmetry in…
Positron physics touches on a wide-ranging variety of fields from materials science to medical imaging to high energy physics. In this paper we present the development of a flexible positron annihilation spectrometer appropriate for the…
We present first-principles approaches based on density functional theory for calculating positron states and annihilation characteristics in condensed matter. The treatment of the electron-positron correlation effects (the enhancement of…
We present evidence for small oscillations we observe in electron-positron and proton-antiproton annihilation data, with a periodicity of 76+-2 MeV, independent of the beam energy. We discuss some possible scenarios to explain the…
We suggest that the observed large annihilation rates of ortho-positronium ($o$-Ps) in halogen gases are due to the process of dissociative Ps attachment, ${\rm Ps} + X_2 \to {\rm Ps}X + X$, where $X$ stands for a halogen atom. This process…
Charged lepton system symmetry under combined charge, parity, and time-reversal transformation (CPT) remains scarcely tested. Despite stringent quantum-electrodynamic limits, discrepancies in predictions for the electron-positron bound…
The aim of this work is to identify the mechanisms responsible for very large rates and other peculiarities observed in low-energy positron annihilation on molecules. The two mechanisms considered are: (i) Direct annihilation of the…
We consider the decay of positronium to a neutrino-antineutrino accompanied by a single photon. Since the neutrino pair go undetected, this appears as a single photon decay of positronium. These decay channel are mediated through the…
We present the results of lifetime positron annihilation spectroscopy (PALS) for the alloys Fe21Ga and Fe22.4Ga, whose defect structure is connected with annealing from 20 to 1000C along the phase diagram of Fe21Ga and Fe22.4Ga, at the…
Recently published results from the PAMELA experiment have shown conclusive evidence for an excess of positrons at high (~ 10 - 100 GeV) energies, confirming earlier indications from HEAT and AMS-01. Such a signal is generally expected from…
A small difference between the energy of the para-positronium (p-Ps) and ortho-positronium (o-Ps) states suggests the possibility of superposition of p-Ps and o-Ps during the formation of positronium (Ps) from pre-Ps terminating its…