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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., 1915-; Barnett, C. F. & Reinhardt, R.
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

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

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

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

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

Classical two-slit interference effects in double photoionization of molecular hydrogen at high energies

Description: Recent experiments on double photoionization of H$_2$ with photon energies between 160 and 240 eV have revealed body-frame angular distributions that suggest classical two-slit interference effects may be present when one electron carries most of the available energy and the second electron is not observed. We report precise quantum mechanical calculations that reproduce the experimental findings. They reveal that the interpretation in terms of classical diffraction is only appropriate atsubstantially higher photon energies. At the energies considered in the experiment we offer an alternative explanation based on the mixing of two non-diffractive contributions by circularly polarized light.
Date: July 6, 2008
Creator: Horner, Daniel A.; Miyabe, Shungo; Rescigno, Thomas N; McCurdy, C. William; Morales, Felipe & Martin, Fernando
Partner: UNT Libraries Government Documents Department

Alignment of the Pixel and SCT Modules for the 2004 ATLAS Combined Test Beam

Description: A small set of final prototypes of the ATLAS Inner Detector silicon tracking system(Pixel Detector and SemiConductor Tracker), were used to take data during the 2004 Combined Test Beam. Data were collected from runs with beams of different flavour (electrons, pions, muons and photons) with a momentum range of 2 to 180 GeV/c. Four independent methods were used to align the silicon modules. The corrections obtained were validated using the known momenta of the beam particles and were shown to yield consistent results among the different alignment approaches. From the residual distributions, it is concluded that the precision attained in the alignmentof the silicon modules is of the order of 5 mm in their most precise coordinate.
Date: June 2, 2008
Creator: Collaboration, ATLAS; Ahmad, A.; Andreazza, A.; Atkinson, T.; Baines, J.; Barr, A.J. et al.
Partner: UNT Libraries Government Documents Department

Feasibility of Measuring the Cosmological Constant [LAMBDA]and Mass Density [Omega]using Type Ia Supernovae

Description: We explore the feasibility of resurrecting the apparent magnitude-redshift relation for a 'standard candle' to measure the cosmological constant and mass density. We show that type Ia supernovae, if measured with 0.15 mag uncertainty out to a redshift of z = 1, may provide a good standard candle or calibrated candle for this purpose. The recent discovery of probable type Ia supernovae in the redshift range z = 0.3 to 0.5 (Perlmutter et al. 1994a, and 1994b) indicates that the flux of optical photons from these events can be measured this accurately. The 7 distant supernovae discovered to date do not by themselves distinguish between different cosmological models, however the further discovery of about 50 type Ia supernovae at redshifts in the range 0.5 < z {approx} 1.0 could strongly constrain the allowed range of these parameters. We estimate that the follow-up photometry necessary for this measurement would be on the order of 20 - 70 hours of time on a lO-meter class telescope at a site with good seeing.
Date: April 1, 1995
Creator: Goobar, A. & Perlmutter, S.
Partner: UNT Libraries Government Documents Department

Observation of a narrow mass state decaying into $\Upsilon(1S) + \gamma$ in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV

Description: Using data corresponding to an integrated luminosity of 1.3 fb{sup -1}, we observe a narrow mass state decaying into {Upsilon}(1S) + {gamma}, where the {Upsilon}(1S) meson is detected by its decay into a pair of oppositely charged muons, and the photon is identified through its conversion into an electron-positron pair. The significance of this observation is 5.6 standard deviations. The mass of the state is centered at 10.551 {+-} 0.014(stat.) {+-} 0.017(syst.) GeV/c{sup 2}, which is consistent with that of the state recently observed by the ATLAS Collaboration.
Date: March 1, 2012
Creator: Abazov, Victor Mukhamedovich & al., et
Partner: UNT Libraries Government Documents Department

Some studies of data using the STAR endcap electromagnetic calorimeter.

Description: A series of studies was performed using data from the STAR detector at the Brookhaven National Laboratory's RHIC accelerator from collisions of protons at {radical}s = 200 GeV. Many of these involved the shower maximum detector (SMD) of the STAR endcap electromagnetic calorimeter (EEMC). Detailed studies of photon candidates from {eta} {yields} {gamma}{gamma} decay, and of {gamma} + Jet inclusive data and simulated events were performed.
Date: February 24, 2009
Creator: Krueger, K.; Spinka, H. M.; Underwood, D. G. & Physics, High Energy
Partner: UNT Libraries Government Documents Department

Hybrid bubble chamber studies of K+ p and K- p interactions at 75-GeV/c

Description: We propose to expose the FNAL 30' liquid hydrogen bubble chamber to K{sup +} and K{sup -} beams both at 75 GeV/c. Each exposure consists of 100,000 equivalent K pictures. We plan to use the upstream tagging system currently in place and a downstream spectrometer with acceptance considerably increased over that of the current PHC system. This new downstream system will also be equipped with a lead glass photon detector with good spatial and energy resolution. We will study comparison of K{sup +} and K{sup -} results, as well as results from {pi}{sup +}, {pi}{sup -} , and {bar p} beams at this energy which are the subject of separate proposals.
Date: January 1, 1975
Creator: Bugg, W.M.; Condo, G.T.; Hart, E.L.; Handler, T.; U., /Tennessee; Cohn, H.O. et al.
Partner: UNT Libraries Government Documents Department

Simple model relating recombination rates and non-proportional light yield in scintillators

Description: We present a phenomenological approach to derive an approximate expression for the local light yield along a track as a function of the rate constants of different kinetic orders of radiative and quenching processes for excitons and electron-hole pairs excited by an incident {gamma}-ray in a scintillating crystal. For excitons, the radiative and quenching processes considered are linear and binary, and for electron-hole pairs a ternary (Auger type) quenching process is also taken into account. The local light yield (Y{sub L}) in photons per MeV is plotted as a function of the deposited energy, -dE/dx (keV/cm) at any point x along the track length. This model formulation achieves a certain simplicity by using two coupled rate equations. We discuss the approximations that are involved. There are a sufficient number of parameters in this model to fit local light yield profiles needed for qualitative comparison with experiment.
Date: September 24, 2008
Creator: Moses, William W.; Bizarri, Gregory; Singh, Jai; Vasil'ev, Andrey N. & Williams, Richard T.
Partner: UNT Libraries Government Documents Department

Longitudinal and Transverse Cross Sections in the <sup>1</sup>H(e,e'K<sup>+</sup>)Lambda Reaction

Description: The <sup>1</sup>H(e,e'K<sup>+</sup>)Lambda reaction was studied as a function of the squared four-momentum transfer, Q<sup>2</sup>, and the virtual photon polarizations. The Q<sup>2</sup> dependence of the sigma-L/sigma-T ratio differs significantly from current theoretical predictions. This, combined with the precision of the measurement, implies a need for revision of existing calculations.
Date: August 1, 1998
Creator: Niculescu, Gabriel; Gueye, Paul & Mtingwa, Sekazi
Partner: UNT Libraries Government Documents Department

Counting constituents in molecular complexes by fluorescence photon antibunching

Description: Modern single molecule fluorescence microscopy offers new, highly quantitative ways of studying the systems biology of cells while keeping the cells healthy and alive in their natural environment. In this context, a quantum optical technique, photon antibunching, has found a small niche in the continuously growing applications of single molecule techniques to small molecular complexes. Here, we review some of the most recent applications of photon antibunching in biophotonics, and we provide a guide for how to conduct photon antibunching experiments at the single molecule level by applying techniques borrowed from time-correlated single photon counting. We provide a number of new examples for applications of photon antibunching to the study of multichromophoric molecules and small molecular complexes.
Date: April 17, 2007
Creator: Fore, S; Laurence, T; Hollars, C & Huser, T
Partner: UNT Libraries Government Documents Department

Ultrabright Laser-based MeV-class Light Source

Description: We report first light from a novel, new source of 10-ps 0.776-MeV gamma-ray pulses known as T-REX (Thomson-Radiated Extreme X-rays). The MeV-class radiation produced by TREX is unique in the world with respect to its brightness, spectral purity, tunability, pulse duration and laser-like beam character. With T-REX, one can use photons to efficiently probe and excite the isotope-dependent resonant structure of atomic nucleus. This ability will be enabling to an entirely new class of isotope-specific, high resolution imaging and detection capabilities.
Date: April 2, 2008
Creator: Albert, F; Anderson, G; Anderson, S; Bayramian, A; Berry, B; Betts, S et al.
Partner: UNT Libraries Government Documents Department

Smoothed Emission for IMC

Description: Here is a review of the current way we handle source photons in Implicit Monte Carlo (IMC). A source photon is created with a randomly sampled position x{sub p} in the zone, a direction {Omega}{sub p}, a frequency v{sub p} sampled from the appropriate distribution, and a time t{sub p} uniformly sampled from [t{sup n}, t{sup n+1}]. The source photons each have an energy E{sub p}. The sum of E{sub p} over all of the photons equals the energy of the source for that time step. In the case of thermal emission in a zone with Volume V, they would have {Sigma}{sub p=1}{sup N} E{sub p} = {sigma} {sub p}acT{sup 4}V{Delta}t, where N is the number of thermal source photons for that time step, and {sigma}{sub p} is the Planck mean opacity. Census photons do not differ from source photons in any way, except that they all start the time step with t{sub p} = t{sup n}. Then they advance each photon until it reaches the end of the time step. When they are done with all of the photons, they update the matter temperature using the difference between the emitted and absorbed energy, and proceed to the next time step.
Date: January 24, 2011
Creator: Gentile, N A
Partner: UNT Libraries Government Documents Department

Stimulated Terahertz Emission from Intra-Excitonic Transitions inCu2O

Description: We report the first observation of stimulated emission of terahertz radiation from internal transitions of excitons. The far-infrared electromagnetic response of Cu{sub 2}O is monitored via broadband terahertz pulses after ultrafast resonant excitation of three-dimensional 3p excitons. Stimulated emission from the 3p to the energetically lower 2s bound level occurs at a photon energy of 6.6 meV, with a cross section of {approx} 10{sup 14} cm{sup 2}. Simultaneous excitation of both exciton levels, in turn, drives quantum beats which lead to efficient terahertz emission sharply peaked at the difference frequency.
Date: June 16, 2005
Creator: Huber, Rupert; Schmid, Ben A.; Shen, Y. Ron; Chemla, Daniel S. & Kaindl, Robert A.
Partner: UNT Libraries Government Documents Department