The Source of Anomalous Positrons in the Cosmic Rays Above 10GeV

We suggest that the heavy neutral lepton in a specific version of SU(3)_L×U(1) model can not only act as dark matter but also provide with a source of anomalous positrons in the cosmic rays above 10GeV.     

Electron Cooling of Positrons in LEPTA

Hyperfine Interactions - Electron cooling of positrons is the essential peculiarity of the method of antihydrogen and positronium fluxes generation, which is based on low-energy positron storage...     

Positrons in metals with voids,vacancies and surfaces

The behaviour of positrons near monovacancies and voids in a metal is discussed in terms of three contributions to the positron work function for the metal, namely the positron zero-point energy, the positron-electron correlation energy and the surface dipole barrier. The image potential when a positron comes near to a metal surface leads to a deep potential ‘trough’ just outside an exterior metal surface or just inside a void surface. Calculations indicate positron bound states localized at metal surfaces for most metals which should be manifested in a long lived positron lifetime component. The behaviour of positronium near metal surfaces is also discussed.     

Conversion of Ultrarelativistic Electrons to Positrons in Thick Targets

Physics of Atomic Nuclei - The values calculated for the electron-to-positron conversion coefficients in a form differential with respect to the energy of product positrons and with respect to the...     

高能电子和正电子在晶体沟道中的辐射

介绍了高能电子和正电子在晶体中的沟道辐射,对超相对论电子和正电子在周期弯曲晶体中的相干辐射进行了分析,并提出了初步的实验设想. The channeling radiation of high energy electrons and positrons in crystals was introduced. According to the new idea proposed by A.V.Korol, the coherent radiation of ultra relativistic electrons and positrons channeled in periodically bent crystals was analyzed. The characteristics of the radiation were obtained by using classic electromagnetic theory and a tentative experimental plan for testing was suggested.     

TeV Electrons and Positrons Measured by PAMELA Spectrometer

Abstract-The PAMELA magnetic spectrometer was launched onboard the Resurs-DK1 satellite to the Earth polar orbit with altitude of 350–600 km to study the fluxes of cosmic ray particles and antiparticles in a wide energy range. Starting science operation in July 2006, PAMELA spectrometer performed continuous observation without major interruption till January 2016 collected about 10 billion trigger events. New analysis included data for all period of observations in 2006–2016 with improved selection efficiency and it allows to extend measurements of total electron and positron flux in TeV region with better statistic accuracy. In this paper, the observed energy spectrum of electrons and positrons is presented and compared with the other modern measurements.

     

Positrons and electron-irradiation induced defects in the layered semiconductor InSe

The positron annihilation characteristics of the layered semiconductor InSe have been investigated. No evidence for low temperature positron trapping is found in as-grown and heavily deformed InSe. The temperature dependence of the S-parameter in these sample exhibits an increase rate in good agreement with the linear expansion coefficient along the c-axis. The positron lifetime spectra of electron-irradiated 0.01% Sn-doped InSe show a long-lifetime component of 336 ps which is tentatively attributed to positrons trapped at isolated In vacancies. Isochronal annealing experiments performed on these samples show that the recovery of the positron lifetime measured at 77K is accomplished in two stages. The first, starting after annealing at 150K, could be induced by the formation of complexes (V_In-Sn_In). The second stage, observed at temperatures T375K, is attributed to the dissociation of these complexes and subsequent annealing of the In vacancies.     

Positrons trapped in polyethylene: Electric field effect

The intensity of the τ₂-component of positrons annihilated in polyethylene is found to increase with increasing electric field, while the formation probability of the positron state responsible for this component remains independent of the field.     

Positrons from supercritical fields of giant nuclear systems

During collisions of heavy nuclei with a combined chargeZ?160 the electronic 1s-state is deeply bound due to the strong Coulomb field, forZ≧173 it even enters as a resonance the lower continuum of the Dirac-Hamiltonian. In pure Rutherford scattering no qualitative indication for the filling of a dynamically createdK-hole by the spontaneous positron creation process is predicted, but the study of heavy-ion collisions with nuclear time delay due to the attractive nuclear force promises clear signatures for the decay of the vacuum. Emphasis is laid also on the quantitative influence of the electron-electron interaction and ofE0-transitions in the giant nuclear system on positron emission, the latter treated in a classical approximation. We compare our results with recent experimental data of two different groups at GSI, Darmstadt.     

Relaxation and Recombination of Antiprotons and Positrons in a Strong Magnetic Field

Journal of Experimental and Theoretical Physics - A physical model is proposed, which makes it possible to determine the velocity distributions of antihydrogen atoms formed as a result of...     

Neutrons in extensive air showers

The main properties of the so-called neutron bursts produced by the passage of extensive air showers (EASs) through a detector array and the properties of these EASs are considered using the experiments that are being or have been carried out previously with the Carpet-2 array at Baksan Neutrino Observatory of the Institute for Nuclear Research, Russian Academy of Sciences, and at Cosmic-Ray Station of UNAM in Mexico as examples. We show that no exotic processes are required to explain the nature of neutron bursts. Based on a working prototype of the previously proposed MULTICOM array, we also show that this phenomenon can be successfully used in studying the EAS hadronic component and that adding special thermal neutron detectors can improve significantly the capabilities of the array for EAS study.     

Neutrons in extensive air showers

The first results of measurements of the thermal-neutron flux in extensive air showers (EASs) using an unshielded scintillation thermal-neutron detector in the Multicom prototype array at the Baksan Neutrino Observatory of the Institute for Nuclear Research are reported. The operating capacity of the new method for studying the EAS hadron component via detection of thermal neutrons and good prospects of this method are demonstrated.     

10—20MeV中子引起单粒子翻转能量沉积统计分析

基于Monte Carlo计算模拟, 对10—20MeV中子引起存储器单粒子翻转能量沉积进行了统计分析, 为了解单粒子翻转随机过程提供能量沉积统计信息.     

Neutrons and antiprotons in ultrahigh-energy cosmic rays

The neutron fraction in the very high-energy cosmic rays near the Greisen-Zatsepin-Kuzmin (GZK) cutoff energy is analyzed by taking into account the time dilation effect of the neutron decays and also the pion photoproduction behaviors above the GZK cutoff. We predict a non-trivial neutron fraction above the GZK cutoff and a negligibly small neutron fraction below. However, there should be a large antiproton fraction in the high-energy cosmic rays below the GZK cutoff in several existing models for the observed cosmic-ray events above and near the GZK cutoff. Such a large antiproton fraction can manifest itself by the muon charge ratio μ⁺/μ^- in the collisions of the primary nucleon cosmic rays with the atmosphere, if there is no neutron contribution. We suggest to use the muon charge ratio as one of the information to detect the composition of the primary cosmic rays near or below the GZK cutoff.     

Overview of Nanotechnology in Korea – 10 Years Blueprint

Journal of Nanoparticle Research -     

Layout and performance of the Asterix IV iodine laser at MPQ,Garching

In this paper, the design procedure and the performance of the single beam Asterix IV high-power iodine laser emitting at = 1315 nm is described. It has been developed on the basis of a 10-years experience with the 1 TW Asterix III laser-system and with the support of a 1-D and a 3-D pulse propagation code. Special emphasis has been put on achieving a high overall system efficiency and a beam intensity profile as homogeneous as possible. Presently, Asterix IV provides output pulses with durations from 0.2 to several ns. At a duration of 0.4 ns, the pulse power is 3 TW and at a duration of 5 ns the pulse energy reaches 2.1 kJ. Under these conditions, the laser can be fired every twenty minutes.