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Interactive modeling of scintillation pulses by visual overlay of computed pulse shapes with the raw data

Description: The modeling technique described was developed to aid in interpretation of the effects of various changes in scintillator formulations on the shape of scintillation pulses. Theoretical pulse shapes were synthesized, the system response function is folded in, and the result is overlaid on the raw data arrays. It has thus been possible to distinguish relatively unambiguously between quenching of the solvent and the solute when various heavy-atom quenchers were added to solutions of a series of substituted terphenyls. The method is found to be valuable in providing basic information about energy transfer steps in a multicomponent scintillator. (LEW)
Date: January 1, 1983
Creator: Flournoy, J.M.; Lutz, S.S.; Franks, L.A.; Ashford, C.B. & Lyons, P.B.
Partner: UNT Libraries Government Documents Department

New liquid scintillators for fiber-optic applications

Description: New long-wavelength-emitting, high-speed, liquid scintillators have been developed and tailored specifically for plasma diagnostic experiments employing fiber optics. These scintillators offer significant advantages over commercially available plastic scintillators in terms of sensitivity and bandwidth. FWHM response times as fast as 350 ps have been measured. Emission spectra, time response data, and relative sensitivity information are presented.
Date: January 1, 1981
Creator: Lutz, S.S.; Franks, L.A.; Flournoy, J.M. & Lyons, P.B.
Partner: UNT Libraries Government Documents Department

New scintillators for fiber optics: system sensitivity and bandwidth as a function of fiber length

Description: Long-wavelength liquid scintillators have been developed for fiber-optic plasma-diagnostic experiments. Relative system sensitivity and bandwidth data as a function of fiber length for several scintillator systems will be presented.
Date: January 1, 1981
Creator: Lutz, S.; Franks, L.A.; Flournoy, J.M. & Lyons, P.B.
Partner: UNT Libraries Government Documents Department

Performance studies of the new generation Amperex XP2020 photomultiplier

Description: Characteristics have been measured for the new generation Amperex XP2020 45 mm-diameter photomultiplier. Some typical photomultiplier characteristics - such as gain, dark current, transit and rise times - are compared with data provided by the manufacturer. Photomultiplier characteristics generally not available from the manufacturer, such as the single photoelectron time spread for the full photocathode illumination, the relative collction efficiency as a function of the voltage between photocathode and focusing electrode, were measured and are discussed, particularly with respect to the optimization of photomultiplier operating conditions for timing applications. Measurements were also made on the photomultiplier's high repetition rate counting performance as well as the rate dependent photomultiplier gain.
Date: November 1, 1980
Creator: Lo, C.C. & Leskovar, B.
Partner: UNT Libraries Government Documents Department

Performance studies of high gain photomultiplier having Z-configuration of microchannel plates

Description: The characteristics of a high gain type ITT F4129 photomultiplier having three microchannel plates in cascade for electron multiplication have been investigated. These plates are in the Z-configuration. Measurements are given of the gain, dark current, cathode quantum efficiency, anode pulse linearity, electron transit time, single and multiphoton time spreads, fatigue, and pulse height resolution. The gain as a function of transverse magnetic field has been measured and is discussed. Photomultiplier characteristics as a function of the input pulse repetition frequency have also been investigated and discussed.
Date: November 1, 1980
Creator: Lo, C.C. & Leskovar, B.
Partner: UNT Libraries Government Documents Department

Review of high bandwidth fiber optics radiation sensors

Description: This paper summarizes the use of fiber optics or guided optical systems for radiation sensors. It is limited a passive systems wherein electrical is not required at the sensor location. However, electrically powered light sources, receivers and/or recorders may still be required for detection and data storage in sensor system operation. This paper emphasizes sensor technologies that permit high bandwidth measurements of transient radiation levels, and will also discuss several low bandwidth applications. 60 refs.
Date: January 1, 1985
Creator: Lyons, P.B.
Partner: UNT Libraries Government Documents Department

Neutron response characteristics of CR-39 polymer for reactor and dosimetry applications

Description: A desensitized etching technique has been developed which has resulted in an excellent differential energy response for alpha particles in the energy range 3 to 14 MeV. This response complements the previously reported differential proton and integral alpha energy responses obtained with different etching techniques. Proton recoil track yields and diameter distributions have been measured for CR-39 polymer solid state track recorders which were exposed to monoenergetic neutron sources in the energy range 0.57 to 15.1 MeV using various thicknesses and types of proton radiator materials.
Date: September 4, 1981
Creator: Ruddy, F.H.; Gold, R.; Preston, C.C.; Roberts, J.H.; Benton, E.V. & Schraube, H.
Partner: UNT Libraries Government Documents Department

Radiation damage in semiconductor detectors

Description: A survey is presented of the important damage-producing interactions in semiconductor detectors and estimates of defect numbers are made for MeV protons, neutrons and electrons. Damage effects of fast neutrons in germanium gamma ray spectrometers are given in some detail. General effects in silicon detectors are discussed and damage constants and their relationship to leakage current is introduced.
Date: December 1, 1981
Creator: Kraner, H.W.
Partner: UNT Libraries Government Documents Department

Status report on activities of ASTM E10. 05. 01 Task Group on Uncertainty Analysis

Description: Uncertainties in the field of reactor dosimetry are analyzed. A survey on uncertainty analysis as it is practiced at leading laboratories which are involved in reactor dosimetry is described. A questionnaire was prepared and mailed to about 45 installations and researchers. Nine replies were received, several of them were prepared by more than one author. Three of the nine came from installations outside the US. Results and the questionnaire are presented.
Date: January 1, 1979
Creator: Kam, F.B.K. & Stallman, F.W.
Partner: UNT Libraries Government Documents Department

Time resolution performance studies of high speed photon detectors

Description: The time resolution capabilities of prototype microchannel plate and static crossed-field high gain photon detectors have been investigated. The devices studied included the LEP HR350 and PM 137-proximity focused high gain microchannel plate and VPM-154A/1.6L static crossed-field photomultipliers. Measurements were made of electron transit time, rise time, time resonse, single photoelectron time spread and multiphotoelectron time spread. The experimental data have been compared with results obtained with conventionally designed RCA 8850 and C31024 high speed photomultipliers. Descriptions are given of the measuring techniques.
Date: May 1, 1979
Creator: Leskovar, B.
Partner: UNT Libraries Government Documents Department

High frequency energy measurements

Description: High-frequency (> 100 MHz) energy measurements present special problems to the experimenter. Environment or available electronics often limit the applicability of a given detector type. The physical properties of many detectors are frequency dependent and in some cases, the physical effect employed can be frequency dependent. State-of-the-art measurements generally involve a detection scheme in association with high-speed electronics and a method of data recording. Events can be single or repetitive shot requiring real time, sampling, or digitizing data recording. Potential modification of the pulse by the detector and the associated electronics should not be overlooked. This presentation will review typical applications, methods of choosing a detector, and high-speed detectors. Special considerations and limitations of some applications and devices will be described.
Date: January 1, 1981
Creator: Stotlar, S.C.
Partner: UNT Libraries Government Documents Department

Detector-selection technique for Monte Carlo transport in azimuthally symmetric geometries

Description: Many radiation transport problems contain geometric symmetries which are not exploited in obtaining their Monte Carlo solutions. An important class of problems is that in which the geometry is symmetric about an axis. These problems arise in the analyses of a reactor core or shield, spent fuel shipping casks, tanks containing radioactive solutions, radiation transport in the atmosphere (air-over-ground problems), etc. Although amenable to deterministic solution, such problems can often be solved more efficiently and accurately with the Monte Carlo method. For this class of problems, a technique is described in this paper which significantly reduces the variance of the Monte Carlo-calculated effect of interest at point detectors.
Date: January 1, 1982
Creator: Hoffman, T.J.; Tang, J.S. & Parks, C.V.
Partner: UNT Libraries Government Documents Department

Progress in the development of scintillating optical fibers

Description: Starting with 1 inch diameter PVT scintillator as a preform, the authors have drawn fibers of several diameters ranging from 1 to 4 mm. These fibers have been coated in line with the draw to form optical fibers. Several cladding materials whose index of refraction ranges from 1.35 to 1.55 have been used. The most successful fiber has been obtained with an extra thick (200 micron) cladding of silicone in combination with a linear draw, as opposed to a spool draw. This fiber is acceptable, but it is extremely fragile and its quality is difficult to control. The authors are currently constructing a 12 channel hodoscope with 1 mm spatial resolution using 4 mm diameter fibers. An account is also given of the progress made in using the Avalanche Photo Diode (APD) operated in the Geiger mode as the photo detector.
Date: January 1, 1983
Creator: Borenstein, S.R. & Strand, R.C.
Partner: UNT Libraries Government Documents Department

Measurement of electromagnetic shower position and size with a saturated avalanche tube hodoscope and a fine grained scintillation hodoscope

Description: A hodoscope has been constructed from 100 ..mu.. m diameter wires and brass tubes (1.2 x 0.7 cm/sup 2/ cross section) filled with a mixture of argon, ethane and ethyl alcohol. It has been tested in the saturated avalanche mode in an SCG1-C electromagnetic shower detector to determine its properties for the measurement of the position and size of electromagnetic showers. Two of these tube hodoscopes were positioned 3.5 radiation lengths deep in the detector and the profiles of 1 to 25 GeV electromagnetic showers were measured. Simultaneous measurements were performed using a plane of twenty, 0.5 cm wide scintillation counters positioned immediately behind the gas tube hodoscope. In addition the transition between saturated avalanche and limited streamer modes has been measured for the tube hodoscopes.
Date: January 1, 1984
Creator: Rameika, R.; Cox, B.; Jenkins, C.M.; Judd, D.J.; Hale, G.; Mazur, P.O. et al.
Partner: UNT Libraries Government Documents Department

Calibration of thin film EMP sensors by AFWL Coaxial Chamber

Description: Preliminary EMP calibration data on magnetic thin film current sensors has been obtained. The Air Force Weapon Lab's Coaxial Chamber was used as the EMP standard and a current pulse width of 40 ns was used. It was found that the sensitivity of the sensors can be increased by controlling the width of the 90/sup 0/ wall strip and that the current scales for the sensors were linear. The results strongly suggest that the dimensions of the sensors can be varied to meet different measurement requirements.
Date: July 8, 1976
Creator: Hsieh, E. J.; Vindelov, K. E.; Brown, T. G. & Miller, D. E.
Partner: UNT Libraries Government Documents Department

Development of a 10-decade single-mode reactor flux monitoring system

Description: Conventional wide-range neutron channels employ three optional modes to monitor the required flux range from source levels to full power (typically 10 or more decades). Difficult calibrations are necessary to provide a continuous output signal when such a system switches from counting mode in the source range to mean-square voltage mode in the midrange to dc current mode in the power range. In an ORNL proof-of-principle test, a method of extended range counting was implemented with a fission counter and conventional wide-band pulse processing electronics to provide a single-mode, monotonically increasing signal that spanned /approximately 10/ decades of neutron flux. Ongoing work includes design, fabrication, and testing of a comlpete neutron flux monitoring system suitable for advanced liquid metal reactor designs. 6 refs., 4 figs.
Date: March 31, 1988
Creator: Valentine, K.H.; Shepard, R.L.; Falter, K.G. & Reese, W.B.
Partner: UNT Libraries Government Documents Department

A Sr-90/Y-90 field calibrator for performance testing of beta-gamma survey instruments

Description: ANSI and regulatory agency guidelines prescribe periodic performance tests for radiation protection instrumentation. Reference readings should be obtained for one point on each scale or decade normally used. A small and lightweight calibrator has been developed that facilitates field testing of beta-gamma survey instruments. The calibrator uses a 45 microcurie Sr-90/Y-90 beta source with a filter wheel to generate variable dose rates in the range from 4 to 400 mrad/hr. Thus, several ranges may be checked by dialing in appropriate filters. The design, use, and typical applications of the calibrator are described.
Date: January 1, 1988
Creator: Olsher, R.H. & Haynie, J.S.
Partner: UNT Libraries Government Documents Department

New developments in radiation protection instrumentation via active electronic methods

Description: New developments in electronics and radiation detectors are improving on real-time data acquisition of radiation exposure and contamination conditions. Recent developments in low power circuit designs, hybrid and integrated circuits, and microcomputers have all contributed to smaller and lighter radiation detection instruments that are, at the same time, more sensitive and provide more information (e.g., radioisotope identification) than previous devices. New developments in radiation detectors, such as cadmium telluride, gas scintillation proportional counters, and imaging counters (both charged particle and photon) promise higher sensitivities and expanded uses over present instruments. These developments are being applied in such areas as health physics, waste management, environmental monitoring, in vivo measurements, and nuclear safeguards.
Date: January 1, 1981
Creator: Umbarger, C.J.
Partner: UNT Libraries Government Documents Department

Status and problems of semiconductor detectors

Description: A brief review is given of the types of silicon and germanium detectors used or presently being developed for nuclear experiments. Large-area silicon and germanium detector telescopes for use in long-range particle detection and identification are emphasized. Large area position-sensitive detectors are also described. Some results are presented regarding radiation damage and damage repair by annealing. Evidence is also presented for the importance of producing large area silicon crystals of adequate quality to reduce trapping problems to negligible proportions.
Date: March 1, 1981
Creator: Walton, J.T.; Goulding, F.S.; Haller, E.E. & Pehl, R.H.
Partner: UNT Libraries Government Documents Department

Experimental study of the signals from a segmented cathode drift chamber

Description: A test drift chamber has been constructed with a segmented cathode for measuring the second coordinate. A corona discharge source has also been constructed to measure the response of the cathode segments. Various size segments were studied and the position resolution and pulse height distributions measured.
Date: October 1, 1978
Creator: Fancher, D.L. & Schaffer, A.C.
Partner: UNT Libraries Government Documents Department

Studies of high-gain microchannel plate photomultipliers

Description: The characteristics and performance of several kinds of high-gain micro-channel plate photomultipliers have been investigated. Special attention was directed toward (1) lifetime studies, (2) performance in the magnetic field, and (3) timing properties. Lifetime studies include separate investigations of the photocathode quantum efficiency degradation caused by ion feedback, and the deterioration of the micro-channel plate gain. The dependence of the micro-channel plate photomultiplier gain on the intensity and the direction of the magnetic field (up to 7 kGauss) is reported.
Date: January 1, 1980
Creator: Oba, K. & Rehak, P.
Partner: UNT Libraries Government Documents Department

Studies of prototype high-gain microchannel plate photomultipliers

Description: The characteristics of new prototype high gain photomultipliers having two microchannel plates in cascade for electron multiplication have been investigated. Measurements are given of the gain, dark current, quantum efficiency, anode pulse linearity, electron transit time, single and multiphotoelectron time spreads, and pulse height resolution of LEP PM137 8/II and PM137 7/I photomultipliers. The gain as a function of transverse magnetic field has been measured and is discussed. Emphasis is put on the determination of optimum photomultiplier operating conditions, particularly with respect to their pulse height resolution capability. Photomultiplier characteristics as a function of input pulse repetition frequency have also been investigated and discussed.
Date: August 1, 1978
Creator: Lo, C.C. & Leskovar, B.
Partner: UNT Libraries Government Documents Department