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An explicit positronium (Ps) source model was implemented in Geant4 to provide direct event-level control over annihilation channel selection, decay timing, and photon emission topology. The implementation supports direct annihilation,…

医学物理 · 物理学 2026-04-29 Jason G Parker

Various mesoporous materials were investigated to choose the best material for experiments requiring high yield of long-lived positronium. We found that the fraction of 3\gamma annihilation determined using \gamma-ray energy spectra and…

The excess energy emitted during the positronium (Ps) formation in condensed matter may be released as light. Spectroscopic analysis of this light can be a new method of studying the electronic properties of materials. We report the first…

Photoelectron (PES) spectra from aluminum cluster anions (from 12 to 15 atoms) at various temperature regimes, were studied using ab-initio molecular dynamics simulations and experimentally. The calculated PES spectra, obtained via shifting…

原子与分子团簇 · 物理学 2009-10-31 Jaakko Akola , Matti Manninen , Hannu Hakkinen , Uzi Landman , Xi Li , Lai-Sheng Wang

The optical response of bulk germanium sulfide (GeS) is investigated systematically using different polarization-resolved experimental techniques, such as photoluminescence (PL), reflectance contrast (RC), and Raman scattering (RS). It is…

A precision measurement by AMS-02 of the positron fraction in primary cosmic rays is presented on this proceeding. Over the last two decades, there has been a strong interest in the cosmic ray positron fraction which exhibit an excess of…

高能天体物理现象 · 物理学 2017-01-02 Sami Caroff

The Positronium (Ps) system, a bound state of an electron and a positron, is suitable for testing the predictions of quantum electrodynamics (QED), since its properties can be perturbatively calculated to high accuracy and, unlike the…

核实验 · 物理学 2021-12-21 Elena Perez del Rio

Positron Emission Tomography (PET) is a Nuclear Medicine technique that creates images that allow the study of metabolic activity and organ function using radiopharmaceuticals. Continuous improvement of scintillation detectors for radiation…

AMS-02 recently published its lepton spectra measurement. The results show that the positron fraction no longer increases above $\sim$200 GeV. The aim of this work is to investigate the possibility that the excess of positron fraction is…

高能物理 - 唯象学 · 物理学 2016-04-28 Jie Feng , Hong-Hao Zhang

The background spectrum of a germanium detector, shielded from the radiations arriving from the lower and open for the radiations arriving from the upper hemisphere is studied, both in a ground level and in an underground laboratory. It is…

仪器与探测器 · 物理学 2015-06-15 R. Banjanac , D. Maletić , D. Joković , N. Veselinović , A. Dragić , V. Udovičić , I. Aničin

Positronium-based imaging requires realistic modelling of positronium (Ps) decay in matter. We introduce a modular Ps decay model implemented in GATE 9.4 and GATE 10, enabling the definition of an arbitrary number of decay channels…

A major part of cosmic rays consists of the primary protons, and this portion plays a crucial role in the space applications such as shielding of spacecrafts. In this study, the proton flux values measured at the top of the atmosphere…

仪器与探测器 · 物理学 2025-01-03 A. Ilker Topuz

The gamma to neutron ratio is measured via Pulse Shape Discrimination (PSD) of a Plutonium Beryllium (PuBe) source and of a rudimentary constructed Polonium Beryllium (PoBe) source using one organic liquid scintillator detector and digital…

核实验 · 物理学 2021-11-05 Sebastian Ritter

Gamma-ray spectroscopy provides diagnostics of particle acceleration in solar flares, but care must be taken when interpreting the spectra due to effects of the angular distribution of the accelerated particles (such as relativistic…

太阳与恒星天体物理 · 物理学 2015-05-20 Shichao Tang , David M. Smith

Positronium (Ps) has emerged as a promising test particle within the QUPLAS collaboration for investigating the gravitational effect. In this work, we present a novel approach to generate a monoenergetic and highly coherent Ps beam by…

原子物理 · 物理学 2023-07-25 M. Sacerdoti , V. Toso , G. Vinelli , G. Rosi , L. Salvi , G. M. Tino , M. Giammarchi , R. Ferragut

The positron-electron pair annihilation in two photons is known for its numerous applications using PET scanners. The decay of Positronium (Ps) from a standard sealed source in more than two photons is less likely but can be observed with a…

物理教育 · 物理学 2011-09-20 M. E. A. Elbasher , W. Erasmus , E. A. M. Khaleel , J. Ndayishimye , P. Papka

We present a universal approach for determining the spontaneous polarization Psp of a wurtzite semiconductor from the emission energies of excitons bound to the different types of stacking faults in these crystals. Employing…

We design a GeV gamma ray detector based on an electron-positron pair measurement by using the BESS-polar magnet and study it with the GEANT4 simulation code. We consider an additional counter to select an electron-positron pair for which…

高能天体物理现象 · 物理学 2010-10-07 S. Osone

Due to the inconsistency in the results of the GEp/Gmp ratio of the proton, as extracted from the Rosenbluth and recoil polarization techniques, high precision measurements of the e-p elastic scattering cross sections were made at Q^2 =…

核实验 · 物理学 2009-09-29 Issam A. Qattan

Published data on the emission of charged particles following nuclear muon capture are extremely limited. In addition to its interest as a probe of the nuclear response, these data are important for the design of some current searches for…

高能物理 - 实验 · 物理学 2020-03-18 A. Gaponenko , A. Grossheim , A. Hillairet , G. M. Marshall , R. E. Mischke , A. Olin
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