1979年4月16日 · Positron absorption in copper using a 68Ge -+ 68Ga source evaporated on lead. The curve is calculated by eq. (1) as indicated in the text. The best fit is obtained for the full width at half maximum, 2a, of the resolution function indi- cated on the graph and the position x, of the sample surface indicated by the arrow.

1984年6月1日 · Nuclear Instruments and Methods in Physics Research B4 (1984) 23-33 North-Holland, Amsterdam 23 CALCULATIONS OF POSITRON ABSORPTION IN TARGETS V.A. KUZMINIKH, A.D. POGREBNYAK and S.A. VOROBIEV Nuclear Physics Research Institute of the Tomsk Polytechnical Institute, Tomsk, USSR Received 20 December 1982 Using the multiple-step method for calculation of transmission of charged particles through ...

Positron production by laser has attracted a lot of interest in recent years because it may provide a non-radioactive, controllable, radiation tunable positron source in laboratories. There are three main processes capable of creating positrons based on laser-plasma interactions: trident process, Bethe-Heitler (BH) process and Breit-Wheeler (BW ...

2020年4月3日 · Laser-driven positron production is expected to provide a non-radioactive, controllable, radiation tunable positron source in laboratories. ... Enhanced absorption of intense short-pulse laser ...

2023年12月11日 · Copious positron production by femto-second laser via absorption enhancement in a microstructured surface target Article Open access 03 April 2020 Introduction

2016年12月6日 · Positron generation in laser-irradiated targets occurs through two dominant mechanisms due to the large population of high energy electrons accelerated at the target front surface. 8,9 Electron-ion pair production, referred to as the Trident process, 10 initiates with the electrons of kinetic energy exceeding 2 m c 2 that scatter from a nuclear charge, exchanging a virtual photon that ...

1999年2月1日 · The penetration of positrons from a Na 22 source into Kapton foils sandwiched between different backscattering materials (Al, Cu, and Pt) has been studied for the geometry characteristic of positron annihilation techniques. Kapton has served as absorber and each of the selected metals as detector. The method, based on measuring the positron lifetimes, makes use of the difference in values of ...

2006年11月16日 · The foil material positron absorption coefficients were obtained and found to be comparable with the results of previous transmission experiments. Topics. MATLAB, Information theory entropy, Crystallographic defects, Crystal lattices, Dielectric materials, Polycrystalline material, Isotopes, Multi-channel analyzer, Optical absorption, Particle ...

2020年4月3日 · Laser-driven positron production is expected to provide a non-radioactive, controllable, radiation tunable positron source in laboratories. We propose a novel approach of positron production by using a femto-second laser irradiating a microstructured surface target combined with a high-Z converter. …

2016年12月1日 · The physical basis for this distinguishing mark is the maximally achievable yield of moderated positrons in tabletop beams which is limited by the positron self-absorption in the β + source. The quality of a particle beam is characterized by its brightness , which describes the phase space density of a representative ensemble of beam particles ...