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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Collective plasma effects of electron–positron pairs in beam-driven QED cascades

Understanding the interplay of strong-field QED and collective plasma effects is important for explaining extreme astrophysical environments like magnetars. It has been shown that QED pair plasma can be produced and observed by passing a relativistic electron beam through an intense laser field. This work presents in detail multiple sets of 3D QED-particle-in-cell simulations to show the creation of pair plasma in the QED cascade. The beam driven method enables a high pair particle density and also a low particle Lorentz factor, which both play equal roles on exhibiting large collective plasma effects. Finite laser frequency upshift is observed with both ideal parameters (24 PW laser colliding with a 300 GeV electron beam) and with existing technologies (3 PW laser colliding with a 30 GeV electron beam).

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Measurement of the fractional radiation length of a pixel module for the CMS Phase-2 upgrade via the multiple scattering of positrons

High-luminosity particle collider experiments such as theones planned at the High-Luminosity Large Hadron Collider requireever-greater vertexing precision of the tracking detectors,necessitating reductions in the material budget of the detectors.Traditionally, the fractional radiation length (x/X$_{0}$) ofdetectors is either estimated using known properties of theconstituent materials, or measured in dedicated runs of the finaldetector. In this paper, we present a method of direct measurementof the material budget of a CMS prototype module designed for thePhase-2 upgrade of the CMS detector using a 40–65 MeV positronbeam. A total of 630 million events were collected at the PaulScherrer Institut PiE1 experimental area using a three-planetelescope consisting of the prototype module as the central plane,surrounded by two MALTA monolithic pixel detectors. Fractionalradiation lengths were extracted from scattering angle distributionsusing the Highland approximation for multiple scattering. Astatistical technique recovered runs suffering from triggerdesynchronisation, and several corrections were introduced tocompensate for local inefficiencies related to geometric and beamshape constraints. Two regions of the module were surveyed andyielded average x/X$_{0}$ values of (0.72 ± 0.05)% and(0.95 ± 0.09)%, which are compatible with empirical estimatesfor these regions computed from known material properties of 0.753%and 0.892%, respectively. Two types of higher-granularity maps ofthe fractional radiation length were produced, subdivided eitherinto rectangular regions of uniform size, or polygonal-shapedregions of uniform material composition. The results bode well forthe CMS Phase-2 upgrade modules, which will play a key role in theminimisation of the material of the upgraded detector.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗