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in subjects: "Collimators"

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Instrument for observing transient cosmic gamma-ray sources for the ISEE-C Heliocentric spacecraft

Satellite instrumentation that would serve as one element of a three-satellite network to provide precise directional information for the recently discovered cosmic gamma-ray bursts is described. The proposed network would be capable of determining source locations with uncertainties of less than one arc minute, sufficient for a meaningful optical and radio search. The association of the gamma bursts with a known type of astrophysical object provides the most direct method for establishing sour… more

Date: December 1, 1977

Creator: Evans, W.D.; Aiello, W.P. & Klebesadel, R.W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Gamma densitometer for measuring Pu density in fuel tubes

A fuel-gamma-densitometer (FGD) has been developed to examine nondestructively the uniformity of plutonium in aluminum-clad fuel tubes at the Savannah River Plant (SRP). The monitoring technique is ..gamma..-ray spectroscopy with a lead-collimated Ge(Li) detector. Plutonium density is correlated with the measured intensity of the 208 keV ..gamma..-ray from /sup 237/U (7d) of the /sup 241/Pu (15y) decay chain. The FGD measures the plutonium density within 0.125- or 0.25-inch-diameter areas of th… more

Date: January 1, 1982

Creator: Winn, Willard G.

Item Type: Report

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

open access

Irradiated fuel inspection in a storage pond with no fuel movement and an uncollimated detector

It is assumed that the assemblies are not to be moved during the inspection in order to reduce the time required. The task is simplified further when the detector is well collimated. If the collimation is insufficient to respond to only one assembly from among an array of fuel assemblies, then an unfolding process is needed. A formulation of the detector's behavior is given followed by an unfolding process to yield the detector's response to each assembly as if it were isolated. Some simulated … more

Date: July 1, 1980

Creator: Rinard, P. M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

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

Radiation levels inside the final focus alcoves are calculated from the main dump, tune-up dumps, and adjustable collimators. Neutron calculations are done for giant resonance neutrons. Fluences of neutrons and photons in the alcoves are determined. It is concluded that, if the beam losses do indeed occur as believed, many of the electronic components in the alcoves will begin to fail after a very short running period. (LEW)

Date: September 10, 1986

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

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Fast optical shutters for Nova, a high power fusion laser

Preliminary design and performance test results for fast optical shutters intended for use in the Nova high power fusion laser system are briefly described. Both an opening shutter to protect the pellet target from amplified spontaneous emission (ASE), and a closing shutter to protect the laser from light reflected back from the target are discussed. Faraday rotators, synchronized by a 400 Hz oscillator, provide an opening shutter mechanism with an opening time of approximately 10 ..mu..s. A pl… more

Date: October 18, 1977

Creator: Bradley, L. P.; Gagnon, W. L. & Carder, B. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Plane grating monochromators for synchrotron radiation

The general background and theoretical basis of plane grating monochromators (PGM's) is reviewed and the particular case of grazing incidence PGM's suitable for use with synchrotron radiation is considered in detail. The theory of reflection filtering is described and the problem of the finite source distance is shown to be of special importance with high brightness storage rings. The design philosophy of previous instruments is discussed and a new scheme proposed, aimed at dealing wi… more

Date: January 1, 1979

Creator: Howells, M R

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Design Calculations for a Neutron Collimator for the TFTR

Some of the design calculations for a collimator for TFTR application are presented and discussed. Discrete ordinates transport calculations have been completed for several right circular cylindrical stainless steel collimators using a 14-MeV neutron, isotropic, 30-cm radius disc source to approximate a plasma volume source. The collimators considered in these survey calculations consisted of 3-cm diameter columns centrally located in 60-cm diameter stainless steel cylinders that varied in leng… more

Date: January 1, 1977

Creator: Lillie, R. A.; Alsmiller, R. G., Jr. & Mihalczo, J. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Development and fabrication of a solar cell junction processing system. Quarterly report No. 2, July 1980

The basic objectives of the program are the following: (1) to design, develop, construct and deliver a junction processing system which will be capable of producing solar cell junctions by means of ion implantation followed by pulsed electron beam annealing; (2) to include in the system a wafer transport mechanism capable of transferring 4-inch-diameter wafers into and out of the vacuum chamber where the ion implantation and pulsed electron beam annealing processes take place; (3) to integrate,… more

Date: July 1, 1980

Creator: Siesling, R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Nuclear data development and shield design for neutrons below 60 MeV

A nuclear data library was created for medium-energy-neutron-transport calculations. The 60-group library includes P/sub 5/ cross sections in standard LASL format for H, B, C, N, O, Si, Fe, and W. The 60-group structure was chosen from a sensitivity analysis of a thick iron shield calculated with a 50-MeV deuteron-on-beryllium neutron source spectrum and a 121-group cross-section set. The library combines processed ENDF/B-IV cross-section data below 20 MeV and higher-energy cross-section parame… more

Date: February 1, 1978

Creator: Wilson, W.B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Beam loss by collimation in a neutralizer duct

Beam fractions lost by collimation in a neutralizer duct are computed in x-x' phase space by using three examples of slab beam distributions under a broad range of duct dimensions, beam half-widths, and beam divergences. The results can be used to design compact neutralizers and to specify beam requirements. The computer code ILOST can be used under a broad range of beam conditions to compute the fraction lost by collimation.

Date: April 3, 1980

Creator: Hamilton, G.W. & Willmann, P.A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Los Alamos constant-Q spectrometer

A constant-Q spectrometer, which has been installed on the pulsed source of the Los Alamos Neutron Scattering Center, is described. It features a number of innovations that ease sample and analyser alignment and a novel composite crystal analyzer which exploits the mosaic properties of plastically deformed germanium in a new way. Observations of phonon dispersion in aluminium and of incoherent scattering in ZrH/sub 2/ are reported, along with background measurements. 11 refs., 5 figs., 1 tab.

Date: January 1, 1985

Creator: Robinson, R.A.; Pynn, R.; Eckert, J. & Goldstone, J.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Design study of a time of flight small-angle diffractometer for a pulsed neutron source

The design study for a neutron SAS instrument at Argonne's proposed Intense Pulsed Neutron Source (peak thermal neutron flux 10/sup 16/ n/cm/sup 2/-sec) indicates that an effective high-resolution TOF SAS diffractometer can be constructed. The design features include a converging slit collimator, provision for 5 x 5 cm/sup 2/ sample cross sectional area, and a 1 x 1 m/sup 2/, two-dimensional detector. The fractional wavelength resolution of the instrument is negligibly small for all wavelengths… more

Date: January 1, 1977

Creator: Carpenter, J.M. & Faber, J. Jr.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Efficient lensing element for x-rays. [Blazed Fresnel Phase Plate]

An efficient x-ray lens with an effective speed of order less than approximately f/50 for lambda greater than approximately 10 A x-rays is described. Fabrication of this lensing element appears feasible using existing microfabrication technology. Diffraction and refraction are coupled in a single element to achieve efficient x-ray concentration into a single order focal spot. Diffraction is used to produce efficient ray bending (without absorption) while refraction is used only to provide appro… more

Date: August 12, 1977

Creator: Ceglio, N.M. & Smith, H.I.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Alignment of the SLC Final Focus system using beam orbits

Beam based alignment is being routinely applied in the SLC Final Focus and has proved to be a very useful tool for determining the quality of the zeroth order orbit as defined by various beam line elements. Given the stringent requirement on the beam quality at the interaction point, a well aligned beam line is essential in that it minimizes the confusion which would otherwise arise in the higher order optics, the demand called on the correctors which also serve as optical knobs, and the proble… more

Date: August 1, 1991

Creator: Chao, Y.; LeDiberder, F.; Burchat, P.; Kozanecki, W. & Toge, N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Improved performance of the ATA injector

During the last year we re-configured the ATA injector to accommodate field emission cathodes. The injector is now run as a diode machine with a 7 cm radius cathode, an A-K gap of 12.9 cm and a field stress of 190 kV/cm. The advantage of using field emission cathodes is we have increased the injector brightness by a factor of ten above the level we were able to reach using the low density plasma cathodes.

Date: June 18, 1985

Creator: Weir, J.T.; Caporaso, G.J. & Prono, D.S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Radiation shielding for the Main Injector collimation system

The results of Monte Carlo radiation shielding studies performed with the MARS15 code for the Main Injector collimation system are presented and discussed. A Proton Plan was developed recently at Fermilab for the benefit of the existing neutrino programs as well as to increase anti-proton production for the Tevatron programs [1]. As a part of the plan, the intensity of proton beams in the Main Injector (MI) should be increased by means of slip-stacking injection. In order to localize beam loss … more

Date: December 1, 2007

Creator: Rakhno, Igor

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Studies of Background Levels for the NIF Yield Diagnostics from Neutron and Gamma Radiation

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is nearing completion of construction and is preparing for the National Ignition Campaign (NIC) with potentially significant yield in 2010. The design of a wide range of yield diagnostics in and outside the target-bay of the NIF must consider scattered background neutrons and neutron-induced gamma rays to measure neutrons and x-rays from target. The large and complex target chamber and facility make the calcul… more

Date: August 27, 2007

Creator: Song, P.; Eder, D.; Moran, M.; Landen, O.; O'Brien, D. & Hsing, W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Beam Collimation Studies for the ILC Positron Source

Results of the collimation studies for the ILC positron source beam line are presented. The calculations of primary positron beam loss are done using the ELEGANT code. The secondary positron and electron beam loss, the synchrotron radiation along the beam line and the bremsstrahlung radiation in the collimators are simulated using the STRUCT code. The first part of the collimation system, located right after the positron source target (0.125 GeV), is used for protection of the RF Linac sections… more

Date: June 26, 2008

Creator: Drozhdin, A.; Nosochkov, Y. & Zhou, F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Outline for an experiment on multi-turn patterns of a crystal collimation system.

No Description Available.

Date: June 23, 2008

Creator: Robert-Demolaize,G.; Drees, A.; Fliller, R. & Peggs, S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

SURFING: A Program for Precise Determination of Sample Position in Stress Measurements Via Neutron Diffraction

Precise determination of the specimen position relative to the sampling volume for texture and stress measurements by neutron diffraction is difficult or sometimes impossible using only optical devices due to large or irregular sample dimensions and/or complicated shape of the sampling volume. The knowledge of the shape and size of the sampling volume allows development of a general mathematical model for the intensity variation with a parallelogram-shape sampling volume moving from outside to … more

Date: August 8, 2000

Creator: Wang, D.-Q.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Design of a boron neutron capture enhanced fast neutron therapy assembly

The use of boron neutron capture to boost tumor dose in fast neutron therapy has been investigated at several fast neutron therapy centers worldwide. This treatment is termed boron neutron capture enhanced fast neutron therapy (BNCEFNT). It is a combination of boron neutron capture therapy (BNCT) and fast neutron therapy (FNT). It is believed that BNCEFNT may be useful in the treatment of some radioresistant brain tumors, such as glioblastoma multiform (GBM). A boron neutron capture enhanced fa… more

Date: August 1, 2006

Creator: Wang, Zhonglu & Tech, /Georgia

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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LIQUID XENON MULTIWIRE PROPORTIONAL CHAMBERS FOR NUCLEAR MEDICINEAPPLICATIONS

The need for improved spatial resolution in nuclear medicine has long been recognized. Notable attempts to achieve this goal are the gas-filled wire chambers and solid-state detectors. (1) However, at energies above 100 keV, gas-filled chambers suffer from poor detection efficiency and a long recoil electron range in the gas. While it is advantageous to pressurize these chambers to 10 or more atmospheres, structural design of the thin window presents a formidable task. High-resolution optimal c… more

Date: May 1, 1974

Creator: Zaklad, H.; Derenzo, S.E.; Budinger, T.F. & Alvarez, L.W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Assessment of the sources of error affecting the quantitative accuracy of SPECT imaging in small animals

Small animal SPECT imaging systems have multiple potential applications in biomedical research. Whereas SPECT data are commonly interpreted qualitatively in a clinical setting, the ability to accurately quantify measurements will increase the utility of the SPECT data for laboratory measurements involving small animals. In this work, we assess the effect of photon attenuation, scatter and partial volume errors on the quantitative accuracy of small animal SPECT measurements, first with Monte Car… more

Date: February 15, 2008

Creator: Joint Graduate Group in Bioengineering, University of California, San Francisco and University of California, Berkeley; Department of Radiology, University of California; Gullberg, Grant T; Hwang, Andrew B.; Franc, Benjamin L.; Gullberg, Grant T. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department