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Title: Some Physics Processes in the Nitrogen-Filled Photoluminescence Cell - Rev. 1

Abstract

As shown in Ref. [1], the photoluminescence cell is a viable candidate for monitoring the total energy in the Linac Coherent Light Source. In Ref. [1], most of the discussion was concentrated on the cell with argon as a working gas. In the present note I provide a discussion of some physics processes that may affect the performance of the photoluminescence cell with the nitrogen fill. In particular, I will consider the role of the space charge effects, ambipolar diffusion, and recombination processes. This group of phenomena determines the duration of the afterglow process that follows an initial short (<100 ns) burst of optical radiation. The presence of this afterglow can be of some significance for the detection system. Compared to my previous note with the same title UCRL-TR-222274, a more detailed discussion of space charge effects is provided, with an emphasis on the electrostatic confinement of the primary electrons. Also, some additional atomic data are included into sections describing recombination processes. The general template for this discussion follows a draft report [1] where the argon-filled cell was considered. But some processes in nitrogen are different and require separate consideration. In what follows, I am not attempting to produce ''exact''more » results, but rather to provide a quick order-of-magnitude scoping study.« less

Authors:
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
896573
Report Number(s):
UCRL-TR-222388
TRN: US0700794
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; AFTERGLOW; AMBIPOLAR DIFFUSION; ARGON; CONFINEMENT; DETECTION; ELECTRONS; ELECTROSTATICS; LIGHT SOURCES; LINEAR ACCELERATORS; MONITORING; NITROGEN; PHOTOLUMINESCENCE; PHYSICS; RECOMBINATION; SPACE CHARGE

Citation Formats

Ryutov, D D. Some Physics Processes in the Nitrogen-Filled Photoluminescence Cell - Rev. 1. United States: N. p., 2006. Web. doi:10.2172/896573.
Ryutov, D D. Some Physics Processes in the Nitrogen-Filled Photoluminescence Cell - Rev. 1. United States. doi:10.2172/896573.
Ryutov, D D. 2006. "Some Physics Processes in the Nitrogen-Filled Photoluminescence Cell - Rev. 1". United States. doi:10.2172/896573. https://www.osti.gov/servlets/purl/896573.
@article{osti_896573,
title = {Some Physics Processes in the Nitrogen-Filled Photoluminescence Cell - Rev. 1},
author = {Ryutov, D D},
abstractNote = {As shown in Ref. [1], the photoluminescence cell is a viable candidate for monitoring the total energy in the Linac Coherent Light Source. In Ref. [1], most of the discussion was concentrated on the cell with argon as a working gas. In the present note I provide a discussion of some physics processes that may affect the performance of the photoluminescence cell with the nitrogen fill. In particular, I will consider the role of the space charge effects, ambipolar diffusion, and recombination processes. This group of phenomena determines the duration of the afterglow process that follows an initial short (<100 ns) burst of optical radiation. The presence of this afterglow can be of some significance for the detection system. Compared to my previous note with the same title UCRL-TR-222274, a more detailed discussion of space charge effects is provided, with an emphasis on the electrostatic confinement of the primary electrons. Also, some additional atomic data are included into sections describing recombination processes. The general template for this discussion follows a draft report [1] where the argon-filled cell was considered. But some processes in nitrogen are different and require separate consideration. In what follows, I am not attempting to produce ''exact'' results, but rather to provide a quick order-of-magnitude scoping study.},
doi = {10.2172/896573},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2006,
month = 6
}

Technical Report:

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  • The photoluminescence cell is a viable candidate for monitoring the total energy in the Linac Coherent Light Source [1]. In Ref. [1], most of the discussion was concentrated on the cell with argon as a working gas. In the present note I provide a discussion of some physics processes that may affect the performance of the photoluminescence cell with the nitrogen fill. In particular, I will consider the role of the space charge effects, ambipolar diffusion, and recombination processes. This group of phenomena determines the duration of the afterglow process that follows an initial short (<100 ns) burst of opticalmore » radiation. The presence of this afterglow can be of some significance for the detection system. The general template for this discussion follows a draft report where the argon-filled cell was considered. But some processes in nitrogen are different and require separate consideration. In what follows, I am not attempting to produce ''exact'' results, but rather to provide a quick order-of-magnitude scoping study.« less
  • The authors report photoluminescence measurement of MBE-grown nitrogen-doped ZnSe under hydrostatic stress. They determined the pressure coefficients of two separate donor-acceptor pair transitions in these samples. The results indicate that the deeper transition is caused by a localized donor that moves further into the band gap with increasing pressure, confirming that it stems from a localized donor. They also show that annealing at temperatures above 325 C produces this donor and results in compensation of the acceptor.
  • As part of the ongoing international DECOVALEX project, four research teams used five different models to simulate coupled thermal, hydrological, and mechanical (THM) processes near underground waste emplacement drifts. The simulations were conducted for two generic repository types, one with open and the other with back-filled repository drifts, under higher and lower post-closure temperature, respectively. In the completed first model inception phase of the project, a good agreement was achieved between the research teams in calculating THM responses for both repository types, although some disagreement in hydrological responses are currently being resolved. Good agreement in the basic thermal-mechanical responses wasmore » also achieved for both repository types, even though some teams used relatively simplified thermal-elastic heat-conduction models that neglect complex near-field thermal-hydrological processes. The good agreement between the complex and simplified process models indicates that the basic thermal-mechanical responses can be predicted with a relatively high confidence level.« less
  • Samples of single-crystal, n-type Cd(X)Se(1-X) (where X is = to 1.000, 0.74, 0.49, 0.26, 0.11, 0.00) emit when excited with ultraband gap excitation. The 295 K band gaps monotoniclly decrease with X from approx. 2.4 eV for CdS to approx. 1.7 eV for CdSe. Photoluminescence (PL) spectra are sharp and have band positions which vary nearly linearly with composition: lumbda(max) (nm) approximately equal to 718-210 X. The energetic proximity to the band gap, temperature dependence and decay times are all consistent with a description of the PL as edge emission. Measured PL efficiencies, phi(r), are approx. 0.0004 in air. Whenmore » the samples are used as photoanodes in photo-electrochemical cells (PECs) employing aqueous polysulfide electrolyte, the emission of intensity can be quenched by the passage of photocurrent. The extent of quenching can be correlated with the photocurrent quantum efficiency. Electroluminescence (EL) can be initiated by using the CdS(X)Se(1-X) samples as dark cathodes in aqueous, alkaline, peroxydisulfate electrolyte at potentials cathodic of approx.-0.9 to -1.1V vs. SCE. The EL spectral distribution for a given sample is similar to that observed in PL experiments and indicates that the same emissive excited state is involved.« less