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in subjects: "Photons"

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High-Sensitivity Single-Molecule Fluorescence Detection in Theory and Practice

The number of emitted photons that can be obtained from a fluorophore increases with the incident light intensity and the duration of illumination. However, saturation of the absorption transition and photodestruction place natural limits on the ultimate signal-to-noise ratio that can be obtained. Equations have been derived to describe the fluorescence-to-background-noise ratio in the presence of saturating light intensities and photodestruction. The fluorescence lifetime and the photodestruct… more

Date: 1989

Creator: Mathies, R. A.; Peck, K. & Stryer, L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Proposal to assemble a high resolution-electron sensitive-energy flow calorimeter in the NEULAND spectrometer

A ..gamma.. catcher and a liquid scintillation calorimeter module in a simple configuration that is well suited to the investigation of several different neutrino induced processes are described. The variety of neutrino beams now available at Fermilab and synchrotron intensity and energy together with the high resolution calorimeter allow a multiplicity of experiments to be carried out with a single detector configuration.

Date: January 1, 1977

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Spectra of negative particles and photons in collisions of p/minus/W and /sup 16/O/minus/W at 200 GeVu

/rho//perpendicular/ spectra of negative particles were measured for p/minus/W and /sup 16/O/minus/W collisions at 200 GeVupsilon in the rapidity range 0.9< y <1.9. Within the systematic errors of 20% the spectra are indentical in the range 0.05 </rho//perpendicular/<2.0 GeVc. The p/minus/W and /sup 16/O /minus/W spectra exhibit an exponential shape for /rho//perpendicular/>250 MeVc. This is consistent with previous p/minus/A data, but there is a significant excess above this exponential at low… more

Date: January 1, 1987

Creator: Bartels, H.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Unusual initial and final state effects in quantum chromodynamics

We have constructed a number of fundamental tests which can be used to probe discrete symmetries, and their possible violations, in the required new physics'' beyond the standard model. On-going experiments with unpolarized e{sup {minus}}e{sup +} collisions contain many events for the production-decay sequence e{sup {minus}}e{sup +} {yields} Z{degrees}, {gamma}* {yields} {tau}{sup {minus}}{tau}{sup +} {yields} (A{sup {minus}X}) (B{sup +}X). From the beam referenced spin-correlation function for… more

Date: December 1, 1991

Creator: Nelson, C.A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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High-sensitivity transuranic waste assay by simultaneous proton and thermal-neutron interrogation using an electron linear accelerator

Simultaneous photon and neutron interrogation from electron linear accelerator pulses is used as the basis for a unique assay technique for transuranics. Both prompt and delayed neutrons from the induced fissions are counted on a single detection system, and the contributions from each interrogating flux are resolved. Detection limits (3 sigma) for /sup 239/Pu were estimated to be 3 mg for prompt fission neutrons and 6 mg for delayed neutrons. The technique also provides a clear distinction bet… more

Date: January 1, 1982

Creator: Franks, L. A.; Pigg, J. L.; Caldwell, J. T.; Cates, M. R.; Kunz, W. E. & Noel, B. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Radiation in the SLC final focus alcoves from beam losses in collimators and dumps. Revision

There are various beam line components between the interaction point (IP) of the SLC and the beam dumps which will intercept enough beam to warrant calculating the radiation levels inside the final focus alcoves. The three types of devices which are of concern are the main dump, tune-up dumps, and adjustable collimators. Fluences of and doses from neutrons and photons in the alcoves are calculated. It is concluded that if the beam losses do occur as expected, many of the electronic components i… more

Date: October 1, 1986

Creator: Jenkins, T.M. & McCall, R.C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Operation and radiation resistance of a FOXFET biasing structure for silicon strip detectors

AC-coupled strip detectors biased with a FOXFET transistor structure have been studied. Measurement results for the basic operational characteristics of the FOXFET are presented together with a brief description of the physics underlying its operation. Radiation effects were studied using photons from a {sup 137}Cs source. Changes in the FOXFET characteristics as a function of radiation dose up to 1 MRad are reported. Results about the effect of radiation on the noise from a FOXFET biased detec… more

Date: February 1, 1992

Creator: Laakso, M. (Fermi National Accelerator Lab., Batavia, IL (United States) Helsinki Univ. (Finland). Dept. of High Energy Physics); Singh, P.; Engels, E. Jr. & Shepard, P. (Pittsburgh Univ., PA (United States). Dept. of Physics and Astronomy)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Dose-rate conversion factors for external exposure to photons and electrons

This paper describes recent modifications of the computer code DOSFACTER, which was developed for the purpose of estimating dose-rate conversion factors for external exposure to photons and electrons emitted by radionuclides dispersed in the environment. The modifications and additions which have been made to the calculations outlined above include the following: (1) calculation of electron dose-rate factors for radiosensitive portions of the skin; (2) incorporation of improved estimates of org… more

Date: January 1, 1980

Creator: Kocher, David C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Tests of perturbative quantum chromodynamics in photon-photon collisions

The production of hadrons in the collision of two photons via the process e/sup +/e/sup -/ ..-->.. e/sup +/e/sup -/X can provide an ideal laboratory for testing many of the features of the photon's hadronic interactions, especially its short-distance aspects. That part of two-photon physics which is particularly relevant to tests of perturbative QCD is reviewed here. 6 figures.

Date: January 1, 1979

Creator: Brodsky, Stanley J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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One photon exchange processes and the calibration of polarization of high energy protons

Polarization phenomena in small momentum transfer high energy one-photon exchange processes in the reaction p + A ..-->.. X + A where A is a complex nucleus and X is anything are examined. It is shown that these polarizations can be related directly to photoproduction polarization effects in the reaction ..gamma.. + p ..-->.. X at low energies. Explicit formulae are written for polarization effects in the case where X ..-->.. ..pi../sup 0/ + p.

Date: January 1, 1978

Creator: Margolis, B. & Thomas, G. H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Automated MCNP photon source generation for arbitrary configurations of radioactive materials and first-principles calculations of photon detector responses

A patch to the Los Alamos Monte Carlo code MCNP has been developed that automates the generation of source descriptions for photons from arbitrary mixtures and configurations of radioactive isotopes. Photon branching ratios for decay processes are obtained from national and international data bases and accesed directly from computer files. Code user input is generally confined to readily available information such as density, isotopic weight fractions, atomic numbers, etc. of isotopes and mater… more

Date: March 1, 1988

Creator: Estes, G.P.; Schrandt, R.G. & Kriese, J.T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Prospects for Large Dynamic Range Isotope Analysis Using Photon Burst Mass Spectrometry

Photon Burst Mass Spectrometry is a relatively new and untried method which may complement and extend the impressive achievements of Resonance Ionization Mass Spectrometry and Accelerator Mass Spectrometry in the field of large dynamic range isotope analysis. Theoretical predictions indicate that measurements in the 10/sup /minus/11/ to 10/sup /minus/15/ range are possible in a reasonable period of time with zero background. Experimentally only the very first demonstrations of PBMS with stable … more

Date: January 1, 1988

Creator: Fairbank, W. M., Jr.; LaBelle, R. D.; Keller, R. A.; Miller, C. M.; Poths, J. & Fearey, B. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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PHOTON: A user's manual

PHOTON has proven very useful in the development of the X17 superconducting wiggler beamline. Its use has determined the shielding required from the wiggler device to the very end of the beamline in the hutches and angiography section. Doses calculated by this program have been compared with experimental results from conventional bending magnet beamline with great success. In each case the program consistently overestimated the dose by factors ranging from 2 to 10. The reason for this overestim… more

Date: January 1, 1988

Creator: Chapman, D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Comment on an unusual event in the E594 detector from the direction of Cygnus X-3

A small array located near the 80 m/sup 2/ E594 neutrino detector at Fermilab had a two week run. The author makes two comments related to ultra high energy gamma ray physics. The first regards the question of angular resolution from muons. In general, the angle of a muon will not reflect the angle of the shower for reasons which include transverse momentum at production, multiple scattering in the atmosphere, multiple scattering in the detector and detector angular resolution. In multiple muon… more

Date: January 1, 1985

Creator: Goodman, M.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Heavy Flavor Production From Photons and Hadrons

The present state of the production and observation of hadrons containing heavy quarks or antiquarks as valence constituents, in reactions initiated by real and (space-like) virtual photon or by hadron beams is discussed. Heavy flavor production in e/sup +/e/sup -/ annihilation, which is well covered in a number of recent review papers is not discussed, and similarly, neutrino production is omitted due to the different (flavor-changing) mechanisms that are involved in those reactions. Heavy fla… more

Date: January 1, 1982

Creator: Heusch, C. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Study of rare muon decay modes with the crystal box

We report on a search for the lepton family-number-nonconserving decays ..mu../sup +/..-->..e/sup +/e/sup -/e/sup +/, ..mu../sup +/..-->..e/sup +/..gamma.., and ..mu../sup +/..-->..e/sup +/..gamma gamma.., using the Crystal Box detector at LAMPF. The experiment was run in the stopped muon channel at LAMPF during the winter and summer of 1984. Muons were stopped in the middle of a detector system consisting of a cylindrical drift chamber, a plastic scintillator hodoscope, and a segmented array o… more

Date: January 1, 1985

Creator: Sandberg, V.; Bolton, R. D.; Bowman, J. D.; Carlini, R. D.; Copper, M. D.; Doung-Van, M. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Calculation of dose-rate conversion factors for external exposure to photons and electrons

Methods are presented for the calculation of dose-rate conversion factors for external exposure to photon and electron radiation from radioactive decay. A dose-rate conversion factor is defined as the dose-equivalent rate per unit radionuclide concentration. Exposure modes considered are immersion in contaminated air, immersion in contaminated water, and irradiation from a contaminated ground surface. For each radiation type and exposure mode, dose-rate conversion factors are derived for tissue… more

Date: January 1, 1978

Creator: Kocher, David C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The search for low photodesorption coatings

Low photo desorption (PSD) from surfaces of vacuum chambers increases the beam lifetime and reduces the cost of the pumping system of any storage ring. In compact rings where all radiated power ({approximately}10 kW) is incident on a few meters only, low PSD and good thermal conductivity of photon absorbers are of particular importance. An experimental chamber in which one meter long bars can be exposed to white photon beam with 500 eV critical energy has been built and installed on the U10B be… more

Date: January 1, 1990

Creator: Foerster, C.L. & Korn, G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Comparison of q anti qg and q anti q. gamma. events in e/sup +/e/sup -/ annihilation at PEP

In comparing the particle flow in the event plane of three-jet (q anti qg) events and of radiative annihilation events (q anti q..gamma..) for similar kinematic configurations, two PEP experiments find a significant decrease in particle density in the angular region opposite to the gluon jet in q anti qg events, relative to the particle density in the region opposite to the photon in q anti q..gamma.. events. The effect is predicted both by QCD and by phenomenological string models. 5 refs., 5 … more

Date: July 1, 1986

Creator: Hofmann, W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Graphs of the cross sections in the Alternate Monte Carlo Cross Section library at the Los Alamos Scientific Laboratory

Graphs of all neutron cross sections and photon production cross sections on the Alternate Monte Carlo Cross Section (AMCCS) library have been plotted along with local neutron heating numbers. The values of ..nu..-bar, the average number of neutrons per fission, are also plotted for appropriate isotopes.

Date: June 1, 1980

Creator: Seamon, R. E. & Soran, P. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Photon Dose Rate From Induced Activity in the Beam Stop of a 400 GeV Proton Accelerator

Calculated results are presented of the photon dose rate from the induced activity produced in the beam stop of a high-energy proton accelerator. Incident proton energies of 400 GeV, 200 GeV, and 30 GeV are considered. In each case the photon dose rate is given as a function of radius in the beam stop and as a function of time after the beam is turned off for assumed operating times of 90 days and 10 years.

Date: February 1, 1978

Creator: Alsmiller, R. G., Jr.; Gabriel, T. A. & Barish, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Progress report for 1979-1980. [Duke Univ. , 1979-1980]

This basically administrative report describes research in the following areas: ..pi..-neon interactions at 200 GeV; direct ..gamma.. and e/sup +/e/sup -/ pair production; studies of photon production in 16-GeV/c ..pi../sup +/-p interactions; ..gamma..-p interactions at 20 GeV; and computer and hardware development. References are given to published work. An expenditure statement is included. (RWR)

Date: September 16, 1980

Creator: Walker, W. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Transmission factors for the penetration of neutron and photon fluence into wood-frame dwellings, 1990 (TF90)

An earlier study at Oak Ridge calculated radiation doses to persons inside reinforced concrete buildings during the exposure at Nagasaki. The DS86'' study conducted at several laboratories in the United States and Japan concentrated on persons inside wood-frame dwellings at both Nagasaki and Hiroshima. The present study is directed toward applying the general technical approach of the DS86. Numerous simplifications were indicated as a result of the earlier research, and the numerical results ar… more

Date: May 1, 1992

Creator: Rhoades, W. A.; Lillie, R. A. & Emmett, M. B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Spectrometer system for investigation of biological molecules with synchrotron radiation at wavelengths greater than 125 nm

The SUPERB experiment at the SURF II storage ring uses synchrotron radiation as a source of uv photons to measure circular dichroism (CD) of biological molecules. Conventional CD instruments are limited by the lack of stable laboratory continuum sources capable of providing large photon fluxes shortward of 200 nm. Synchrotron radiation overcomes these limitations and enables one to extend CD measurements down to the limit of the window transmission cutoff, which is 125 nm for CaF/sub 2/ used in… more

Date: April 1, 1980

Creator: Takacs, P. Z. & Sutherland, J. C.

Item Type: Article

Partner: UNT Libraries Government Documents Department