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Photon Spectrum From Bremsstrahlung

Description: Abstract: The number of photons of given energy radiated in Bremsstrahlung collision of electrons with nuclei is calculated relativistically. Expansions are obtained for energies small to mc-squared. The photon spectrum is averaged over a Maxwell distribution for the electrons. Numerical results are included.
Date: August 11, 1953
Creator: Gluckstern, R. L.; Hull, M. H., Jr. & Breit, G.
Partner: UNT Libraries Government Documents Department

Compton Scattering on Nucleons

Description: From introduction: "The present paper deals with a classical calculation in which some of the meson effects can be included to all orders in the meson-nucleon coupling coupling constant, in particular those having to do with the gyration of the nucleon spin and isotopic spin. Such a treatment leads to results qualitatively different from the weak coupling calculations."
Date: May 24, 1954
Creator: Huddlestone, Richard Harold
Partner: UNT Libraries Government Documents Department

Film quantum yields of EUV& ultra-high PAG photoresists

Description: Base titration methods are used to determine C-parameters for three industrial EUV photoresist platforms (EUV-2D, MET-2D, XP5496) and twenty academic EUV photoresist platforms. X-ray reflectometry is used to measure the density of these resists, and leads to the determination of absorbance and film quantum yields (FQY). Ultrahigh levels ofPAG show divergent mechanisms for production of photo acids beyond PAG concentrations of 0.35 moles/liter. The FQY of sulfonium PAGs level off, whereas resists prepared with iodonium PAG show FQY s that increase beyond PAG concentrations of 0.35 moles/liter, reaching record highs of 8-13 acids generatedlEUV photons absorbed.
Date: January 10, 2008
Creator: Hassanein, Elsayed; Higgins, Craig; Naulleau, Patrick; Matyi, Richard; Gallatin, Greg; Denbeaux, Gregory et al.
Partner: UNT Libraries Government Documents Department

Dissociation of H₂⁺ by Photons

Description: Abstract: "A measurement was made of the dissociation of vibrationally-excited H2+ ions by photons having quantum energy in the vicinity of 4 e.v. The calculated cross section from theory is 3 x 10-(-18) cm-2. The experimental result is 10-(-17) cm-2; a factor of 10 uncertainty is present because the photon intensity was unknown by that factor."
Date: June 12, 1957
Creator: Linlor, William I.; Barnett, C. F. & Reinhardt, R.
Partner: UNT Libraries Government Documents Department

Three-Dimensional Silicon Photonic Crystals

Description: In this work, we report the realization of a series of silicon 3D photonic crystals operating in the infrared (IR), mid-IR and most importantly the near-IR (k= 1 -2pm) wavelengths. The structure maintains its crystal symmetry throughout the entire 6-inches wafer and holds a complete photonic bandgap.
Date: December 4, 1998
Creator: Biswas, R.; Fleming, J.G.; Hetherington, D.L.; Ho, K.M.; Lin, S.; Sigalas, M.M. et al.
Partner: UNT Libraries Government Documents Department

Photon and electron data for use in accelerator applications

Description: In accelerator applications we need photon and electron data, as well as computer codes that utilize this data, in order to predict results inexpensively and safely. In this paper I will first cover the current status of available photon and electron data, with emphasize on the improved detailed that has only recently been added to our data bases. Next I will cover the availability of this data and computer codes that use it.
Date: October 31, 1998
Creator: Cullen, D E
Partner: UNT Libraries Government Documents Department

Two-Dimensional Carrier-Carrier Screening in a Quantum Well

Description: The behavior of carrier-carrier screening is investigated in a GaAs-GaAIAs quantum well structure by measuring the band-to-band polarization dephasing with femtosecond photon echoes. The variation of the electron-hole polarization dephasing time with the carrier concentration reveals the two-dimensional character of the short range screening between the interacting carriers.
Date: July 1, 1991
Creator: Bigot, J.-Y.; Portella, M.T.; Schoenlein, R.W.; Cunningham, J.E. & Shank, C.V.
Partner: UNT Libraries Government Documents Department

Recent results and future challenges for large scale Particle-In-Cell simulations of plasma-based accelerator concepts

Description: The concept and designs of plasma-based advanced accelerators for high energy physics and photon science are modeled in the SciDAC COMPASS project with a suite of Particle-In-Cell codes and simulation techniques including the full electromagnetic model, the envelope model, the boosted frame approach and the quasi-static model. In this paper, we report the progress of the development of these models and techniques and present recent results achieved with large-scale parallel PIC simulations. The simulation needs for modeling the plasma-based advanced accelerator at the energy frontier is discussed and a path towards this goal is outlined.
Date: May 1, 2009
Creator: Huang, C.; An, W.; Decyk, V.K.; Lu, W.; Mori, W.B.; Tsung, F.S. et al.
Partner: UNT Libraries Government Documents Department

A Little Twin Higgs Model

Description: We present a twin Higgs model based on left-right symmetry with a tree level quartic. This is made possible by extending the symmetry of the model to include two Z_2 parities, each of which is sufficient to protect the Higgs from getting a quadratically divergent mass squared. Although both parities are brokenexplicitly, the symmetries that protect the Higgs from getting a quadratically divergent mass are broken only collectively. The quadratic divergences of the Higgs mass are thus still protected at one loop. We find that the fine-tuning in this model is reduced substantially compared to the original left-right twin Higgs model. This mechanism can also be applied to the mirror twin Higgs model to get a significant reduction of the fine-tuning, while keeping the mirror photon massless.
Date: July 25, 2007
Creator: Goh, Hock-Seng; Goh, Hock-Seng & Krenke, Christopher A.
Partner: UNT Libraries Government Documents Department

BEAM EXPOSURE DEPENDENCE AND MECHANISMS OF PHOTON-STIMULATED DESORPTION FROM ALKALI FLUORIDES

Description: Photon-stimulated desorption experiments were performed on the (001) face of LiF for photon energies near the F(2s) and Li(ls) edges (from 37 to 72 eV). There are structures in the F{sup +} yield above the F(2s) edge which are absent in the Li{sup +} spectrum, differences in detail in the Li{sup +} and F{sup +} yields near the Li(1s) edge, and considerable broadening of the desorption yields as compared to the bulk photoabsorption spectrum. The first observation of a strong x-ray, and visible, beam exposure dependence of ion yields from LiF and NaF is also presented. These results are discussed in terms of electronic and defect properties of alkali halides.
Date: November 1, 1983
Creator: Parks, C.C.; Shirley, D.A. & Loubriel, G.
Partner: UNT Libraries Government Documents Department

Photonic Band Gap Micro-Cavities in Three-Dimension

Description: Localization of light to less than a cubic wavelength, {lambda}{sup 3}, has important quantum consequences. The creation of single mode cavities and the modification of spontaneous emission are two important examples. A defect formed inside a three-dimensional (3D) photonic crystal provides an unique optical environment for light localization. Single mode defect cavities were built, for the first time, from an infrared 3D photonic crystal. A cavity state with modal volume of less than one {lambda}{sup 3} was observed.
Date: April 26, 1999
Creator: Biswas, R.; Fleming, J.G.; Ho, K.M.; Lin, Shawn-Yu & Sigalas, M.M.
Partner: UNT Libraries Government Documents Department

First year results from LOTIS

Description: LOTIS (Livermore Optical Transient Imaging System) is a gamma-ray burst optical couterpart search experiment located near Lawrence Livermore National Laboratory in California. The system is linked to the GCN (GRB Coordinates Network) real-time coordinate distribution network and can respond to a burst trigger in 6-15 seconds. LOTIS has a total field-of-view of 17.4 degrees x 17.4 degrees with a completeness sensitivity of mv {approximately} 11 for a 10 second integration time. Since operations began in October 1996, LOTIS has responded to over 30 GCN/BATSE GRB triggers. Seven of these triggers are considered good events subject to the criteria of clear weather conditions, {lt}60 S RESPONSE TIME, AND {gt}50% coverage of the final BATSE 3(sigma) error circle. We discuss results from the first year of LOTIS operations with an emphasis on the observations and analysis of GRB 971006 (BATSE trigger 6414).
Date: November 17, 1997
Creator: Williams, G.G.; Parks, H.S. & Ables, E.
Partner: UNT Libraries Government Documents Department

New new-phenomena results from D-Zero

Description: We have searched for diphoton events ({gamma}{gamma} /E{sub T}) with large missing transverse momentum, {gamma} /E{sub T} events ({gamma} /E{sub T}+{ge} 2 jets) with two or more jets, and diphoton events ({gamma}{gamma}) with high transverse energies in p{anti p} collisions at {radical}s = 1.8 TeV using approximately 100 pb{sup -1} of data collected with the D0 detector at the Fermilab Tevatron in 1992-1996. No excess of events beyond the expected backgrounds is observed. The null results are interpreted in supersymmetric models with a dominant {tilde {xi}}{sup 0}{sub 2} {yields} {gamma}{tilde {xi}}{sup 0}{sub 1} decay and in terms of Dirac pointlike monopole production.
Date: June 1, 1998
Creator: Qian, J.
Partner: UNT Libraries Government Documents Department

Photon and di-photon results from CDF and D0

Description: Measurements by the Fermilab D0 and CDF collaborations of prompt photon events in p{anti p} collisions at {radical}s = 1.8 TeV are reported. The measured isolated photon cross sections are compared to current parton distribution functions and NLO QCD predictions. The cross section ratio of forward to central {eta} bins and {eta} distributions are presented and compared with theoretical predictions. {gamma}+2jet events yield insight into final state radiation. A new measurement of {gamma}+{mu} events is presented which probes the charm content of the proton. Finally, di-photon results are presented as a probe of initial state radiation; these results are compared to NLO QCD, Pythia parton showers, and resummation models.
Date: May 11, 1999
Creator: Hanlet, Pierrick
Partner: UNT Libraries Government Documents Department