616 Matching Results

Search Results

Advanced search parameters have been applied.

Proportional Fission Neutron Counters

Description: Abstract: Some proportional fission neutron counters are described with information on methods of preparation and details of a circuit for a portable model. The portable instrument has an efficiency of .01% for neutrons from polonium beryllium sources.
Date: March 26, 1951
Creator: Rohr, R. C.; Rohrer, E. R. & Macklin, R. L.
Partner: UNT Libraries Government Documents Department

Testing of Kaonetics Devices at BNL

Description: The goal of these measurements was to evaluate whether there is evidence of emission of X-rays, gamma-rays, and neutrons by devices developed by Kaonetics Technologies, Inc. during their operation.
Date: June 1, 2011
Creator: Bolotnikov, A.; Smith, G. & and James, R.B.
Partner: UNT Libraries Government Documents Department

Fast-Neutron Surveys Using Indium-Foil Activation

Description: Activation of indium foils by thermal neutrons has been applied to measurement of fast-neutron fluxes. Foils are encased in paraffin spheres placed in cadmium boxes. The high-energy neutrons that penetrate the cadmium become thermal neutrons; the thermal-neutron flux is proportional to the incident fast-neutron flux over a range of about 20 kev to 20 Mev. The foils are removed from the boxes and counted on a methane-flow proportional counter. High instantaneous neutron fluxes are easily detected and counted by use of these foils. Many simultaneous measurements have been made easily by this method.
Date: August 13, 1958
Creator: Stephens, Lloyd D. & Smith, Alan R.
Partner: UNT Libraries Government Documents Department

Upgrade of the wide-angle neutron diffractometer at the high flux isotope reactor

Description: The Wide-Angle Neutron Diffractometer (WAND) is a flat-cone geometry diffractometer located at the High Flux Reactor (HFIR). This instrument is currently being upgraded. The central part of this upgrade is the development of a new curved one-dimensional position sensitive detector which covers a 125 degree angular range with an effective radius of 71 cm. This detector will be a multi-anode (624 anodes on a 0.2 degree pitch) {sup 3}He gas-filled proportional counter. This totally new system will give high resolution, good uniformity and high counting range - a maximum capability of 10{sup 5} cps/pixel and a 10{sup 7} cps overall. A prototype of this detector has shown that these design targets can be met. The new WAND will greatly broaden its capabilities for single-crystal diffraction experiments and for time-resolved measurements.
Date: July 15, 1997
Creator: Katano, S.; Morii, Y. & Child, H.R.
Partner: UNT Libraries Government Documents Department

X-ray spectral properties of {gamma}-ray bursts

Description: The authors summarize the spectral characteristics of a sample of 22 bright gamma-ray bursts detected with the gamma-ray burst sensors aboard the satellite Ginga. This instrument employed a proportional and scintillation counter to provide sensitivity to photons in the 2--400 keV range, providing a unique opportunity to characterize the largely unexplored X-ray properties of gamma-ray bursts. The photon spectra of the Ginga bursts are well described by a low energy slope, a bend energy, and a high energy slope. In the energy range where they can be compared, this result is consistent with burst spectral analyses obtained from the BATSE experiment aboard the Compton Observatory. However, below 20 keV they find evidence for a positive spectral number index in approximately 40% of their burst sample, with some evidence for a strong rolloff at lower energies in a few events. They find that the distribution of spectral bend energies extends below 10 keV. The observed ratio of energy emitted in the X-rays relative to the gamma-rays can be much larger than a few percent and, in fact, is sometimes larger than unity. The average for their sample is 24%.
Date: September 1, 1997
Creator: Strohmayer, T.E.; Fenimore, E.E.; Murakami, Toshio & Yoshida, Atsumasa
Partner: UNT Libraries Government Documents Department

An Independent Measurement of the Total Active 8B Solar Neutrino Flux Using an Array of 3He Proportional Counters at the Sudbury Neutrino Observatory

Description: The Sudbury Neutrino Observatory (SNO) used an array of {sup 3}He proportional counters to measure the rate of neutral-current interactions in heavy water and precisely determined the total active ({nu}{sub x}) {sup 8}B solar neutrino flux. This technique is independent of previous methods employed by SNO. The total flux is found to be 5.54{sub -0.31}{sup +0.33}(stat){sub -0.34}{sup +0.36}(syst) x 10{sup 6} cm{sup -2}s{sup -1}, in agreement with previous measurements and standard solar models. A global analysis of solar and reactor neutrino results yields {Delta}m{sup 2} = 7.94{sub -0.26}{sup +0.42} x 10{sup -5} eV{sup 2} and {theta} = 33.8{sub -1.3}{sup +1.4} degrees. The uncertainty on the mixing angle has been reduced from SNO's previous results.
Date: June 5, 2008
Creator: Colla, SNO
Partner: UNT Libraries Government Documents Department


Description: We report properties of single-wire proportional chambers and multiple-wire ionization chambers filled with liquid xenon. Proportional multiplication is seen for anode fields > 10{sup 6} volts/cm (anode-cathode voltage> 1 kV for a 3.5-{micro}-diam anode wire). The efficiency for detecting ionizing radiation is {approx} 100%. The time resolution of the chambers is {+-} 10{sup -7} sec. We attained a spatial resolution of {+-} 15 {micro} with a multiwire ionization chamber, considerably better than that of any other real-time particle detector.
Date: June 1, 1971
Creator: Muller, Richard A.; Derenzo, Stephen E.; Smadja, Gerard.; Smith, Dennis B.; Smits, Robert G.; Zaklad, Haim. et al.
Partner: UNT Libraries Government Documents Department

Fast Neutron Flux Measurements for Shielding Applications

Description: Pressed sulfur pellets, irradiated for two hours at 10 w yielded satisfactory counting rates on an internal proportional counter for measuring fast neutrons. The pellets were counted in their original form and an equation applicable to thick sources was applied to obtain disintegration rates. Decay data and beta energy analyses indicated that the induced activity was due to P/ sup 32/. Cross section values reported in the literature for the S/sup 32/(n,p)P/ sup 32/ reaction involved were found to differ widely. The fust flux values given are based on an assumed cross section of 285 millibarns in a fission spectrum. Thermal flux values at the same positions and for the same power are also presented. (auth)
Date: August 27, 1959
Creator: Roy, M.
Partner: UNT Libraries Government Documents Department


Description: We discuss new anode geometries, employing position-dependent charge partitioning, which can be used with microchannel plates, planar proportional counters, and mesh dynode electron multipliers to obtain a two-dimensional position signal from each detected photon or particle. Only three or four anode electrodes and signal paths are required, yet images comprised of a number of detected events have little geometric distortion and the resolution is not limited by thermal noise inherent in resistive sheet anodes. We present an analysis of the geometrical image nonlinearity in the relationship between event centroid location and the charge partition ratios. Fabrication and testing of two wedge-and-strip anode systems are discussed. Images obtained with EUV radiation and microchannel plates that verify the predicted performance of this readout system are shown. We emphasize that the spatial resolution of the wedge-and-strip anode is in no way limited by the coarseness of the anode conductor pattern. The resolution is of the order of 0.4% of the image field size, and could be further improved by adopting low noise signal circuitry. Tradeoffs encountered in the design of practical x-ray, EUV, and charge particle image systems are discussed.
Date: February 1, 1981
Creator: Martin, C.; Jelinsky, P.; Lampto, M.; Malina, R.F. & Anger, H.O.
Partner: UNT Libraries Government Documents Department

Development of a screened cathode gas flow proportional counter for in situ field determination of alpha contamination in soil

Description: This study resulted in the design, construction and testing of a gas flow proportional counter for in-situ determination of soil contamination. The uniqueness of this detector is the screened material used for the cathode. A Pu-239 source of 0.006 {micro}Ci was mounted to the outside of the cathode to simulate radioactive soil. The detector probe was placed into a laboratory mock-up and tested to determine operating voltage, efficiency and energy resolution. Two gas flow proportional counters were built and tested. The detectors are cylindrical, each with a radius of 1.905 cm, having an anode wire with a radius of 0.0038 cm. The length of the smaller detector`s anode was 2.54 cm, and the length of the larger detector`s anode was 7.64 cm. Therefore, the active volumes were 28.96 cm{sup 3} and 87.10 cm{sup 3}, respectively, for the small and large detector. An operating voltage of 1,975 volts was determined to be sufficient for both detectors. The average efficiency was 2.59 {+-} 0.12% and 76.71 {+-} 10.81% for the small volume and large volume detectors, respectively. The average energy resolution for the low-energy peak of the small detector was 4.24 {+-} 1.28% and for the large-energy peak was 1.37 {+-} 0.66%. The large detectors` energy resolution was 17.75 {+-} 3.74%. The smaller detector, with better energy resolution, exhibited a bi-modal spectrum, whereas the larger detector`s spectrum centered around a single broad peak.
Date: February 1, 1997
Creator: Bush, S.P.
Partner: UNT Libraries Government Documents Department

Electronics progress report, August 1--31, 1948

Description: Various studies centering on problems and their solutions encountered in electroplating production at Mound Laboratory. Some studies described include construction of the Scaler-Multiplier EL-229, operation of a methane-flow proportional counter, life-time decreases of production half-cells, and use of vibrating reed electrometer.
Date: December 31, 1948
Creator: Heyd, J.W.
Partner: UNT Libraries Government Documents Department

Searching for antiproton decay at the Fermilab Antiproton Accumulator

Description: This paper describes an experimental search for antiproton decay at the Fermilab Antiproton Accumulator. The E868 (APEX) experimental setup is described. The APEX data is expected to be sensitive to antiproton decay if the antiproton lifetimes is less than a few times 100,000 years.
Date: September 1, 1995
Creator: Geer, S. & Collaboration, E868
Partner: UNT Libraries Government Documents Department

Solar Neutrino Physics

Description: With its heavy water target, the Sudbury Neutrino Observatory (SNO) offers the unique opportunity to measure both the 8B flux of electron neutrinos from the Sun and, independently, the flux of all active neutrino species reaching the Earth. A model-independent test of the hypothesis that neutrino oscillations are responsible for the observed solar neutrino deficit can be made by comparing the charged-current (CC) and neutral-current (NC) rates. This LDRD proposal supported the research and development necessary for an assessment of backgrounds and performance of the SNO detector and the ability to extract the NC/CC-Ratio. Particular emphasis is put upon the criteria for deployment and signal extraction from a discrete NC detector array based upon ultra-low background 3He proportional counters.
Date: July 15, 1999
Creator: Bowles, T.J.; Brice, S.J.; Esch, E.-I.; Fowler, M.M.; Goldschmidt, A.; Hime, A. et al.
Partner: UNT Libraries Government Documents Department

An array of low-background 3He proportional counters for theSudbury Neutrino Observatory

Description: An array of Neutral-Current Detectors (NCDs) has been builtin order to make a unique measurement of the total active ux of solarneutrinos in the Sudbury Neutrino Observatory (SNO). Data in the thirdphase of the SNO experiment were collected between November 2004 andNovember 2006, after the NCD array was added to improve theneutral-current sensitivity of the SNO detector. This array consisted of36 strings of proportional counters lled with a mixture of 3He and CF4gas capable of detecting the neutrons liberated by the neutrino-deuteronneutral current reaction in the D2O, and four strings lled with a mixtureof 4He and CF4 gas for background measurements. The proportional counterdiameter is 5 cm. The total deployed array length was 398 m. The SNO NCDarray is the lowest-radioactivity large array of proportional countersever produced. This article describes the design, construction,deployment, and characterization of the NCD array, discusses theelectronics and data acquisition system, and considers event signaturesand backgrounds.
Date: February 1, 2007
Creator: Amsbaugh, J.F.; Anaya, J.M.; Banar, J.; Bowles, T.J.; Browne,M.C.; Bullard, T.V. et al.
Partner: UNT Libraries Government Documents Department


Description: The increasing availability of short lived gamma and positron emitting isotopes, coupled with the importance of dynamical studies and better imaging, has generated the need for an improved {gamma}-ray camera. The authors discuss a new type of {gamma}-ray camera which makes use of electron avalanches in liquid xenon. A configuration currently under development is shown in Figure 1. The successful operation of a liquid xenon proportional counter was recently reported. The liquid xenon camera promises better spatial resolution and higher counting rate than the existing NaI(Tl) scintillation camera. The spatial resolution for {gamma} rays is in principle limited only by the range of photoelectrons in liquid xenon, which is < 0.2 mm for energies < 1 MeV. A counting rate of 10{sup 6} C/s or more appears possible. As a result of the better resolution and high counting rate capability, the definition of the picture is improved. In addition, the high counting rate capability makes possible dynamic studies which were previously unfeasible. Although they expect the energy resolution with liquid xenon to be superior to that of NaI, the preliminary measurements show 17% FWHM for 279 keV {gamma}'s. Improvements are expected by using better geometry and smoother wire.
Date: February 1, 1972
Creator: Zaklad, Haim.; Derenzo, Stephen E.; Muller, Richard A.; Smadja,Gerard.; Smits, Robert G. & Alvarez, Luis W.
Partner: UNT Libraries Government Documents Department


Description: A relationship is derived between the mean square fluctuating current of a hot wire anemometer and the six turbulent Reynolds' stresses in the stream- coordinate system without employing the usual low turbulent intensity approximation. The relatively simple result is a consequence of assuming proportionality between the wire current reading and the perpendicular velocity component instead of the nonlinear dependence required by King's law. The assumption is valid for instruments equipped with the proper linearizing circuitry. Tbe stream-coordinate Reynolds' stresses are then related to the cylindrical polar Reynolds' stresses. An error analysis on the experimental determination of ore of these stresses is indicated but cannot be evaluated without fu rther data. (auth)
Date: February 21, 1961
Creator: Wichner, R.P. & Peebles, F.N.
Partner: UNT Libraries Government Documents Department