High-intensity positron microprobe at the Thomas Jefferson National Accelerator Facility

Golge, S.; Vlahović, Branislav; Wojtsekhowski, B.

doi:10.1063/1.4884781

Cited by 7 publications

(3 citation statements)

References 57 publications

(63 reference statements)

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“…There was some concern expressed by the attendees that there is a long path from 100 MeV to 1 eV and while many have attempted it, none have succeeded in getting 10 10 slow e + /s in a useful beam diameter and energy. This concern was met by consideration of the proposal from NCCU [17] of a way to use the highly efficient solid Ne moderator [8] to get slow positron intensities much greater than 10 10 slow e + per sec. Another concern was that the Jefferson Lab has no onsite history, expertise, or leadership in slow positron physics.…”

Section: Overviewmentioning

confidence: 99%

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Proposal for a slow positron facility at Jefferson National Laboratory

Mills

2018

AIP Conference Proceedings

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One goal of the JPos-17 International Workshop on Physics with Positrons was to ascertain whether it would be a good idea to expand the mission of the Thomas Jefferson National Accelerator Facility (JLab) to include science with low energy (i.e. "slow") spin polarized positrons. It is probably true that experimentation with slow positrons would potentially have wide-ranging benefits comparable to those obtained with neutron and x-ray scattering, but it is certain that the full range of these benefits will never be fully available without an infrastructure comparable to that of existing neutron and x-ray facilities. The role for Jefferson Laboratory would therefore be to provide and maintain (1) a dedicated set of machines for making and manipulating high intensity, high brightness beams of polarized slow positrons; (2) a suite of unique and easily used instruments of wide utility that will make efficient use of the positrons; and (3) a group of on-site positron scientists to provide scientific leadership, instrument development, and user support. In this note some examples will be given of the science that might make a serious investment in a positron facility worthwhile. At the same time, the lessons learned from various proposed and successful positron facilities will be presented for consideration.

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Section: Overviewmentioning

confidence: 99%

“…(1) The primary solid Ne moderated slow positron source will be based on the proposal by S. Golge, B. Vlahovic, and B. Wojtsekhowski [17] and will be implemented by collaborators at JLab.…”

Section: Proposal Elementsmentioning

confidence: 99%

Proposal for a slow positron facility at Jefferson National Laboratory

Mills

2018

AIP Conference Proceedings

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“…Bright γ-sources from electron bremsstrahlung in a target or from nuclear reactors are used successfully to generate intense positron beams (for a review of the positron sources worldwide see [3]). Spin-polarized positrons from radioactive sources provide a new, atomic scale view on the magnetism and electronic structure of magnetic materials [4].…”

Section: Introductionmentioning

confidence: 99%

Project for a Source of Polarized Slow Positrons at ELI-NP

Djourelov

Oprisa

Leca

2017

DDF

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We describe the status of a project for obtaining an intense beam of polarized slow positrons at the Extreme Light Infrastructure - Nuclear Physics (ELI-NP) at Magurele (near Bucharest, Romania) [1]. Positrons will be created via pair production and moderated at a tungsten target using the pulsed brilliant gamma beam which will be produced by Compton back-scattering of circularly polarized laser photons on electrons from a warm linac beam [2]. Simulations of the interaction of circularly polarized γ‑rays of energies up to 3.5 MeV and an intensity of 2.4×1010γ/s with the target, moderation of created positrons and beam formation are discussed. The optimization of the target design showed that the primary slow positron beam can be obtained with intensity of 1‑2×106e+/s. The primary beam will be transversally polarized with a degree of polarization of ~30%. We discuss the necessity of changing the e+ beam polarization from transversal to longitudinal by an electrostatic 90˚ bender which is proposed to work in combination with a remoderator. Simulations show that neither the remoderator nor the electrostatic bender will change the degree of e+ beam polarization. The longitudinally polarized e+ can be successfully transported to the sample chambers without depolarization, but with reduced intensity (by approximately one order of magnitude) due to the remoderation. We present a convertor-moderator assembly with a hole which will allow creating positrons in parasitic mode, i.e., simultaneously with the nuclear physics experiments at ELI-NP. The positron spectroscopy laboratory at ELI-NP will be user dedicated and the beam will have the highest intensity of polarized slow positrons for material science in the world and therefore it could become a unique tool for investigation of magnetic samples.

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