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Sample records for pulsed neutron logging

  1. Pulsed neutron porosity logging system

    International Nuclear Information System (INIS)

    Smith, H.D. Jr.; Smith, M.P.; Schultz, W.E.

    1978-01-01

    An improved pulsed neutron porosity logging system is provided in the present invention. A logging tool provided with a 14 MeV pulsed neutron source, an epithermal neutron detector, and a fast neutron detector is moved through a borehole. Repetitive bursts of neutrons irradiate the earth formations and, during the bursts, the fast neutron population is sampled. During the interval between bursts the epithermal neutron population is sampled along with background gamma radiation due to lingering thermal neutrons. The fast and epithermal neutron population measurements are combined to provide a measurement of formation porosity

  2. Pulsed neutron generator for logging

    International Nuclear Information System (INIS)

    Thibideau, F.D.

    1977-01-01

    A pulsed neutron generator for uranium logging is described. This generator is one component of a prototype uranium logging probe which is being developed by SLA to detect, and assay, uranium by borehole logging. The logging method is based on the measurement of epithermal neutrons resulting from the prompt fissioning of uranium from a pulsed source of 17.6 MeV neutrons. An objective of the prototype probe was that its diameter not exceed 2.75 inches, which would allow its use in conventional rotary drill holes of 4.75-inch diameter. This restriction limited the generator to a maximum 2.375-inch diameter. The performance requirements for the neutron generator specified that it operate with a nominal output of 5 x 10 6 neutrons/pulse at up to 100 pulses/second for a one-hour period. The development of a neutron generator meeting the preliminary design goals was completed and two prototype models were delivered to SLA. These two generators have been used by SLA to log a number of boreholes in field evaluation of the probe. The results of the field evaluations have led to the recommendation of several changes to improve the probe's operation. Some of these changes will require additional development effort on the neutron generator. It is expected that this work will be performed during 1977. The design and operation of the first prototype neutron generators is described

  3. Pulsed neutron uranium borehole logging with prompt fission neutrons

    International Nuclear Information System (INIS)

    Bivens, H.M.; Smith, G.W.; Jensen, D.H.

    1976-01-01

    The gross count natural gamma log normally used for uranium borehole logging is seriously affected by disequilibrium. Methods for the direct measurement of uranium, such as neutron logging, which are not affected by disequilibrium have been the object of considerable effort in recent years. This paper describes a logging system for uranium which uses a small accelerator to generate pulses of 14 MeV neutrons to detect and assay uranium by the measurement of prompt fission neutrons in the epithermal energy range. After an initial feasibility study, a prototype logging probe was built for field evaluation which began in January 1976. Physical and operational characteristics of the prototype probe, the neutron tube-transformer assembly, and the neutron tube are described. In logging operations, only the epithermal prompt fission neutrons detected between 250 microseconds to 2500 microseconds following the excitation neutron pulse are counted. Comparison of corrected neutron logs with the conventional gross count natural gamma logs and the chemical assays of cores from boreholes are shown. The results obtained with this neutron probe clearly demonstrate its advantages over the gross count natural gamma log, although at this time the accuracy of the neutron log assay is not satisfactory under some conditions. The necessary correction factors for various borehole and formation parameters are being determined and, when applied, should improve the assay accuracy

  4. Limitations and developing directions of pulsed neutron logging

    International Nuclear Information System (INIS)

    Wu Wensheng; Xiao Lizhi

    2007-01-01

    The paper explains briefly the principle of pulsed neutron logging method, summarizes the system and uses of the method in petroleum logging. The paper points out the limitations of pulsed neutron logging such as low precise measurements, low logging speed, plenty of influence factors, low vertical resolution, bad adaptability, difficult logging interpretation and so on, and expounds its developing directions in hardware, software, method and principle. (authors)

  5. Use of pulsed neutron logging to evaluate perforation washing

    International Nuclear Information System (INIS)

    Dimon, C.A.

    1986-01-01

    This invention relates to the use of pulsed neutron logging techniques before and after perforation washing operations are performed to evaluate the degree of success of the perforation washing operations. Well logging operations of a type designed to respond to the difference between a formation immediately behind the well sheath and voids in the formation are performed both before and after the perforation washing operation. differences between the two resulting logs are then indicative of voids created by perforation washing. In a preferred embodiment, pulsed neutron logging is used as the logging technique, while a weighted brine having a high absorption cross section to pulsed neutrons is used as the perforation washing fluid

  6. Pulsed neutron logging - a modern approach to petroleum exploration

    International Nuclear Information System (INIS)

    Navalkar, M.P.

    1978-01-01

    As hydrocarbons have strikingly different properties for neutrons as compared with rocks, neutronic methods are useful to prepare logs of bore holes drilled for petroleum exploration. The earlier neutron logs were based on steady neutron sources, but the superior logs, namely, neutron life time log and neutron induced spectral log are based on pulsed neutron sources. The methods of obtaining these logs, their limitations and the field equipment required are described briefly. As the two logs are complementary, a plea has been made to develop field equipment which can obtain two logs in a single run. (M.G.B.)

  7. Pinpointing water entries using pulsed neutron and Production logging tools

    International Nuclear Information System (INIS)

    Mukerji, P.; Oluwa, J.

    2003-01-01

    A successful work over requires a comprehensive understanding of fluid entries into the wellbore and fluid contact movement in the reservoir. Such information can be obtained by a combination of production logs and saturation-monitoring measurements. The ability to combine pulsed neutron and production logging tools provides the operator with better diagnostics for identifying candidates for remedial actions and greatly increases the possibility of a successful well intervention. Advances in pulsed neutron spectroscopy tools have improved the accuracy and precision of measured carbon/oxygen ratios. Some of the improvements in accuracy and precision have resulted from better tool characterization in a wider variety of logging environments in the calibration facility and new spectral standards. Coincident with the advances in pulsed neutron spectroscopy has been the development of production logging measurements run on a platform common. We will show how the application of pulsed neutron and production logs can optimize subsequent well intervention to reduce water production and/or increase oil production

  8. The pdk-100 enhances interpretation capabilities for pulsed neutron capture logs

    International Nuclear Information System (INIS)

    Randall, R.R.; Oliver, D.W.; Ferti, W.H.

    1986-01-01

    The PDK-100 is a new pulsed neutron logging system designed to measure Sigma (Σ), the macroscopic thermal neutron capture cross section. In addition to determining Σ, the system provides logging curves which are a measure of formation porosity and which furnish information concerning borehole conditions. This paper reviews the principles of operation of the PDK-100, and presents examples which illustrate the utility of the logging system. In addition, the progress of investigations into new parameters which can be derived with pulsed neutron logging data will be reported

  9. Pulsed neutron source well logging system

    International Nuclear Information System (INIS)

    Dillingham, M.E.

    1975-01-01

    A pulsed neutron source arrangement is provided in which a sealed cylindrical chamber encloses a rotatable rotor member carrying a plurality of elongated target strips of material which emits neutrons when bombarded with alpha particles emitted by the plurality of source material strips. The rotor may be locked in a so-called ON position by an electromagnetic clutch drive mechanism controllable from the earth's surface so as to permit the making of various types of logs utilizing a continuously emitting neutron source. (Patent Office Record)

  10. Use of pulsed neutron-neutron logging, thermal neutron-neutron logging, and gamma logging methods in classification for sand-clay sediments of Lower Cretaceous in Prikumsk oil-and-gas region according to filtration-capacitance characteristics

    International Nuclear Information System (INIS)

    Maksimenko, A.N.; Basin, Ya.N.; Novgorodov, V.A.

    1974-01-01

    To isolate reservoirs, the formation and deformation penetration zone parameters are used. They are estimated according to the false oil saturation factor and the time of the penetration zone deformation which are determined from the complex exploration of cased wells using the pulse neutron logging, thermal neutron-neutron logging and gamma logging techniques

  11. Optimized Design of Spacing in Pulsed Neutron Gamma Density Logging While Drilling

    Directory of Open Access Journals (Sweden)

    ZHANG Feng;HAN Zhong-yue;WU He;HAN Fei

    2016-10-01

    Full Text Available Radioactive source, used in traditional density logging, has great impact on the environment, while the pulsed neutron source applied in the logging tool is more safety and greener. In our country, the pulsed neutron-gamma density logging technology is still in the stage of development. Optimizing the parameters of neutron-gamma density instrument is essential to improve the measuring accuracy. This paper mainly studied the effects of spacing to typical neutron-gamma density logging tool which included one D-T neutron generator and two gamma scintillation detectors. The optimization of spacing were based on measuring sensitivity and counting statistic. The short spacing from 25 to 35 cm and long spacing from 60 to 65 cm were selected as the optimal position for near and far detector respectively. The result can provide theoretical support for design and manufacture of the instrument.

  12. Earth formation pulsed neutron porosity logging system utilizing epithermal neutron and inelastic scattering gamma ray detectors

    International Nuclear Information System (INIS)

    Smith, H.D. Jr.; Smith, M.P.; Schultz, W.E.

    1978-01-01

    An improved pulsed neutron porosity logging system is provided in the present invention. A logging tool provided with a 14 MeV pulsed neutron source, an epithermal neutron detector and an inelastic scattering gamma ray detector is moved through a borehole. The detection of inelastic gamma rays provides a measure of the fast neutron population in the vicinity of the detector. repetitive bursts of neutrons irradiate the earth formation and, during the busts, inelastic gamma rays representative of the fast neutron population is sampled. During the interval between bursts the epithermal neutron population is sampled along with background gamma radiation due to lingering thermal neutrons. the fast and epithermal neutron population measurements are combined to provide a measurement of formation porosity

  13. Time derived sigma for pulsed neutron capture logging

    International Nuclear Information System (INIS)

    Randall, R.R.; Fertl, W.F.; Hopkinson, E.C.

    1981-01-01

    The purpose of this study is to review field applications of the Atlas Neutron Lifetime Log service and to examine recent technical advances in the instrumentation and data analysis system. The major improvement to be discussed is a new method for computing /SIGMA/, the thermal neutron capture cross section of an earth formation. In the new method, the time after the neutron burst is measured for each gamma ray pulse detected by the instrumentation system within a gate of fixed width. This ''average pulse time'' is uniquely related to the thermal neutron decay rate observed in a borehole environment. The technique discussed is applicable for any condition where the neutron or gamma ray flux is time dependent. The advantages of this signal processing method, however, are most apparent for cases of rapid flux change with time, as in an exponential decay. 7 refs

  14. Pulsed neutron well logging apparatus having means for determining background radiation

    International Nuclear Information System (INIS)

    Randall, R.R.

    1979-01-01

    A neutron generator in a well logging instrument is periodically pulsed and has an off period between pulses of 1000 microseconds. A neutron detector is gated on at intervals of 400 to 500, 550 to 650, and 700 to 800 microseconds, respectively, following the termination of each burst of fast neutrons. Circuitry is provided for determining the background radiation and for determining the macroscopic absorption. 3 claims

  15. A cement channel-detection technique using the pulsed-neutron log

    International Nuclear Information System (INIS)

    Myers, G.D.

    1991-01-01

    A channel-detection technique has been developed using boron solutions and pulsed-neutron logging (PNL) tools. This technique relies on the extremely high-neutron-absorption cross section that boron exhibits relative to other common elements, including chlorine. The PNL tool is used to detect movement of a boron solution in a log-inject-log procedure. The technique has identified channels in such difficult applications as logging through two strings of pipe and in highly deviated wellbores. Logging procedures are simple and cement channels can be readily identified. The boron solutions are relatively inexpensive, safe to handle, and nonradioactive. Additional PNL information for reservoir performance evaluation is collected simultaneously during channel-detection logging. This paper describes the theory, development, field application, and limitations of this channel-detection logging technique

  16. Pulsed neutron well logging apparatus having means for determining background radiation

    International Nuclear Information System (INIS)

    Randall, R.R.

    1979-01-01

    A neutron generator in a well logging instrument is periodically pulsed and has an off period between pulses of 1000 microseconds. A neutron detector is gated on at intervals of 400 to 500, 550 to 650, and 700 to 800 microseconds, respectively, following the termination of each burst of fast neutrons. Circuitry is provided for determining the background radiation by the equation: B = N 1 X N 3 - N 2 2 /N 1 + N 3 - 2N 2 where B is the background, and N 1 , N 2 and N 3 are the counts observed during the three gates, respectively. Circuitry is also provided for determining the macroscopic absorption (Σ) from the equation: Σ = 1/VΔt Log [N 1 - B/N 2 - B] where V is the velocity of thermal neutrons, being a constant and Δt represents an increment of time

  17. Background subtraction system for pulsed neutron logging of earth boreholes

    International Nuclear Information System (INIS)

    Hopkinson, E.C.

    1977-01-01

    A neutron generator in well logging instrument is pulsed 100 times having a time between pulses of 1400 microseconds. This is followed by an off period of four cycles wherein 2800 microseconds is allowed for capture radiation to decay to an insignificant level and the remaining 2800 microseconds is used to measure background radiation. This results in the neutron source being disabled four pulses after every hundred pulses of operation, or approximately a 4 percent loss of neutron output. A first detector gate is open from 400 to 680 microseconds and a second detector gate is open from 700 to 980 microseconds. During the 100 cycles, each of the gates is thus open for 280 microseconds times 100 for a total of 28,000 microseconds. By scaling the gate count rate by a factor of 10, the background is subtracted directly

  18. Pulsed neutron gama ray logging for minerals associated with uranium

    International Nuclear Information System (INIS)

    Jensen, D.H.; Humphreys, D.R.; Stephenson, W.A.; Weinlein, J.H.; Bivens, H.M.

    1980-01-01

    The tool uses a pulsed neutron generator to irradiate the nuclei in the formation surrounding the borehole, and N type, high purity, germanium detector to observe the returning gamma rays. The presence or absence of particular elements, in conjunction with information gained from other logs, is expected to predict the location of uranium deposits away from the borehole. The Proof of Principle probe has been assembled. Tests have been run using an external power supply with a resolution better than 2.6 keV. Experiments in a simulated borehole configuration with a pulsed neutron generator have established an output level of 1 x 10 5 neutrons/pulse for the detection of inelastic, capture, and activation gamma rays. Gating of the ADC was shown to improve the signal-to-noise ratio for specific gamma ray lines

  19. Accuracy and borehole influences in pulsed neutron gamma density logging while drilling

    Energy Technology Data Exchange (ETDEWEB)

    Yu Huawei [College of Geo-Resources and Information, China University of Petroleum, Qingdao, Shandong 266555 (China); Center for Engineering Applications of Radioisotopes (CEAR), Department of Nuclear Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Sun Jianmeng [College of Geo-Resources and Information, China University of Petroleum, Qingdao, Shandong 266555 (China); Wang Jiaxin [Center for Engineering Applications of Radioisotopes (CEAR), Department of Nuclear Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Gardner, Robin P., E-mail: gardner@ncsu.edu [Center for Engineering Applications of Radioisotopes (CEAR), Department of Nuclear Engineering, North Carolina State University, Raleigh, NC 27695 (United States)

    2011-09-15

    A new pulsed neutron gamma density (NGD) logging has been developed to replace radioactive chemical sources in oil logging tools. The present paper describes studies of near and far density measurement accuracy of NGD logging at two spacings and the borehole influences using Monte-Carlo simulation. The results show that the accuracy of near density is not as good as far density. It is difficult to correct this for borehole effects by using conventional methods because both near and far density measurement is significantly sensitive to standoffs and mud properties. - Highlights: > Monte Carlo evaluation of pulsed neutron gamma-ray density tools. > Results indicate sensitivity of the tool to standoff and mudcake properties. > Accuracy of far spaced detector is better than near spaced.

  20. Accuracy and borehole influences in pulsed neutron gamma density logging while drilling

    International Nuclear Information System (INIS)

    Yu Huawei; Sun Jianmeng; Wang Jiaxin; Gardner, Robin P.

    2011-01-01

    A new pulsed neutron gamma density (NGD) logging has been developed to replace radioactive chemical sources in oil logging tools. The present paper describes studies of near and far density measurement accuracy of NGD logging at two spacings and the borehole influences using Monte-Carlo simulation. The results show that the accuracy of near density is not as good as far density. It is difficult to correct this for borehole effects by using conventional methods because both near and far density measurement is significantly sensitive to standoffs and mud properties. - Highlights: → Monte Carlo evaluation of pulsed neutron gamma-ray density tools. → Results indicate sensitivity of the tool to standoff and mudcake properties. → Accuracy of far spaced detector is better than near spaced.

  1. The use of diffusion theory to compute invasion effects for the pulsed neutron thermal decay time log

    International Nuclear Information System (INIS)

    Tittle, C.W.

    1992-01-01

    Diffusion theory has been successfully used to model the effect of fluid invasion into the formation for neutron porosity logs and for the gamma-gamma density log. The purpose of this paper is to present results of computations using a five-group time-dependent diffusion code on invasion effects for the pulsed neutron thermal decay time log. Previous invasion studies by the author involved the use of a three-dimensional three-group steady-state diffusion theory to model the dual-detector thermal neutron porosity log and the gamma-gamma density log. The five-group time-dependent code MGNDE (Multi-Group Neutron Diffusion Equation) used in this work was written by Ferguson. It has been successfully used to compute the intrinsic formation life-time correction for pulsed neutron thermal decay time logs. This application involves the effect of fluid invasion into the formation

  2. Application of accelerator sources for pulsed neutron logging of oil and gas wells

    International Nuclear Information System (INIS)

    Randall, R.R.

    1985-01-01

    Dresser Atlas introduced the first commercial pulsed neutron oil well log in the early 1960s. This log had the capability of differentiating oil from salt water in a completed well. In the late 1970s the first continuous carbon/oxygen (C/O) log capable of differentiating oil from fresh water was introduced. The sources used in these commercial logs are radial geometry deuterium-tritium reaction devices with Cockcroft-Walton voltage multipliers providing the accelerator voltage. The commercial logging tools using these accelerators are comprised of scintillators detectors, power supplies, line drivers and receivers, and various timing and communication electronics. They are used to measure either the time decay or energy spectra of neutron-induced gamma events. The time decay information is useful in determining the neutron capture cross section, and the energy spectra is used to characterize inelastic neutron events. (orig.)

  3. Application of accelerator sources for pulsed neutron logging of oil and gas wells

    Science.gov (United States)

    Randall, R. R.

    1985-05-01

    Dresser Atlas introduced the first commercial pulsed neutron oil well log in the early 1960s. This log had the capability of differentiating oil from salt water in a completed well. In the late 1970s the first continuous carbon/oxygen (C/O) log capable of differentiating oil from fresh water was introduced. The sources used in these commercial logs are radial geometry deuterium-tritium reaction devices with Cockcroft-Walton voltage multipliers providing the accelerator voltage. The commercial logging tools using these accelerators are comprised of scintillators detectors, power supplies, line drivers and receivers, and various timing and communications electronics. They are used to measure either the time decay or energy spectra of neutron-induced gamma events. The time decay information is useful in determining the neutron capture cross section, and the energy spectra is used to characterize inelastic neutron events.

  4. Dual detector pulsed neutron logging for providing indication of formation porosity

    International Nuclear Information System (INIS)

    Hopkinson, E.C.

    1979-01-01

    A logging instrument contains a pulsed neutron source and a pair of radiation detectors spaced along the length of the instrument. The radiation detectors are gated differently from each other to provide an indication of formation porosity which is substantially independent of the formation salinity. In the preferred embodiment, the electrical signals indicative of radiation detected by the long-spaced detector are gated for almost the entire interval between neutron pulses and the short-spaced signals are gated for a significantly smaller time interval which commences soon after the termination of a given neutron burst. The signals from the two detectors are combined in a ratio circuit for determination of porosity

  5. Pulse neutron logging technique

    International Nuclear Information System (INIS)

    Bespalov, D.F.; Dylyuk, A.A.

    1975-01-01

    A new method of neutron-burst logging is proposed, residing in irradiating rocks with fast neutron bursts and registering the integrated flux burst of thermal and/or epithermal neutrons, from the moment of its initiation to that of full absorption. The obtaained value is representative of the rock properties (porosity, hydrogen content). The integrated flux in a burst of thermal and epithermal neutrons can be measured both by way of activation of a reference sample of a known chemical composition during the neutron burst and by recording the radiation of induced activity of the sample within an interval between two bursts. The proposed method features high informative value, accuracy and efficiency

  6. Pulsed Neutron log application in accurate fluid contact determination and remedial action planning

    International Nuclear Information System (INIS)

    Kalu, I.; Mukerji, P.

    2002-01-01

    A common application of pulsed neutron logging in the Niger Delta is saturation monitoring when run in carbon-oxygen (CO) mode. Recently, one such log was run across a reservoir to confirm the position of the oil-water contact on a well that was producing at very high water cut on the short string of a dual string producer. Material balance calculations had predicted an oil-water contact about 5ft from the deepest perforations and so a water shut-off operation had been planned. The interpreted log however showed that the OWC was about 30ft from the perforation and it also showed fluid movement in the borehole in front of the perforations. A production log was subsequently run which identified a tubing leak and confirmed the crossflow of water from the long string into the short string detected on the pulsed neutron log. The proposed water shut-off treatment was aborted based on the interpretation and resulted in substantial savings

  7. Development of response transforms from comparative study of commercial pulsed neutron capture logging systems

    International Nuclear Information System (INIS)

    Salaita, G.N.; Youngblood, W.E.

    1991-01-01

    This paper reports that the absence of a common calibration facility to ascertain the accuracy of commercial pulsed neutron capture logging systems, coupled with the desire for more accurate saturation determination from time-lapse logs, prompted Saudi Aramco to carry out this comparative study. Three generations of Schlumberger's Thermal Decay Time (TDT) logging devices, viz., TDT-K, TDT-M, and TDT-P along with Atlas Wireline PDK-100 system were run in an Aramco well. The wellbore 8-1/2 inch with 7-inch casing-penetrated clean sand, shaly sand, and shale streaks sequence as exhibited by the open hole natural gamma ray log. initially, the wellbore fluid was diesel. The fluid was then changed to brines of 42-kppm and 176-kppm NACl, respectively. Three repeat passes at a logging speed of 900 ft/hr were obtained by each device for each of the three borehole liquids. In the case of PDK-100, a second set of log runs was obtained at 1800 ft/hr. The results of this extensive comparative study have increased the author's understanding of the borehole liquid and the diffusion effects on the response of pulsed neutron capture logging systems and also on the relative accuracy and precision of measured formation thermal neutron capture cross section by each system

  8. Determination of residual oil saturation from time-lapse pulsed neutron capture logs in a large sandstone reservoir

    International Nuclear Information System (INIS)

    Syed, E.V.; Salaita, G.N.; McCaffery, F.G.

    1991-01-01

    Cased hole logging with pulsed neutron tools finds extensive use for identifying zones of water breakthrough and monitoring oil-water contacts in oil reservoirs being depleted by waterflooding or natural water drive. Results of such surveys then find direct use for planning recompletions and water shutoff treatments. Pulsed neutron capture (PNC) logs are useful for estimating water saturation changes behind casing in the presence of a constant, high-salinity environment. PNC log surveys run at different times, i.e., in a time-lapse mode, are particularly amenable to quantitative analysis. The combined use of the original open hole and PNC time-lapse log information can then provide information on remaining or residual oil saturations in a reservoir. This paper reports analyses of historical pulsed neutron capture log data to assess residual oil saturation in naturally water-swept zones for selected wells from a large sandstone reservoir in the Middle East. Quantitative determination of oil saturations was aided by PNC log information obtained from a series of tests conducted in a new well in the same field

  9. Pulsed neutron generator

    International Nuclear Information System (INIS)

    Bespalov, D.F.; Bykovskii, Yu.A.; Vergun, I.I.; Kozlovskii, K.I.; Kozyrev, Yu.P.; Leonov, R.K.; Simagin, B.I.; Tsybin, A.S.; Shikanov, A.Ie.

    1986-03-01

    The paper describes a new device for generating pulsed neutron fields, utilized in nuclear geophysics for carrying out pulsed neutron logging and activation analysis under field conditions. The invention employs a sealed-off neutron tube with a laser ion source which increases neutron yield to the level of 10 neutrons per second or higher. 2 refs., 1 fig

  10. New portable neutron generator for well logging

    International Nuclear Information System (INIS)

    Chicanov, A.E.; Gromov, E. V.; Gulko, V. M.; Izmailov, A. V.

    1994-01-01

    The information about the design, investigation and testing of new well neutron generator for the pulse neutron logging (PNL) is given in this paper. The main physical characteristics of new PNL apparatus are: Neutron flux 2.10 sup 8 n/s ; Pulse frequency>=400 Hz; Diameter= 90 mm; Logging velocity >200 m/h; Number of probes = 2; Resource > 300 h. The generator were provided by gas-filled neutron accelerative tube named NTF-2. The perspective of application and optimization shown PNL apparatus are considered. (author)

  11. Accuracy and borehole influences in pulsed neutron gamma density logging while drilling.

    Science.gov (United States)

    Yu, Huawei; Sun, Jianmeng; Wang, Jiaxin; Gardner, Robin P

    2011-09-01

    A new pulsed neutron gamma density (NGD) logging has been developed to replace radioactive chemical sources in oil logging tools. The present paper describes studies of near and far density measurement accuracy of NGD logging at two spacings and the borehole influences using Monte-Carlo simulation. The results show that the accuracy of near density is not as good as far density. It is difficult to correct this for borehole effects by using conventional methods because both near and far density measurement is significantly sensitive to standoffs and mud properties. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Simultaneous thermal neutron decay time and porosity logging system

    International Nuclear Information System (INIS)

    Smith, H.D. Jr.; Smith, M.P.; Schultz, W.E.

    1979-01-01

    A simultaneous pulsed neutron porosity and thermal neutron capture cross section logging system is provided for radiological well logging of subsurface earth formations. A logging tool provided with a 14 MeV pulsed neutron source, an epithermal neutron detector, and a combination gamma ray and fast neutron detector is moved through a borehole. Repetitive bursts of neutrons irradiate the earth formations; and, during the bursts, the fast neutron and epithermal neutron populations are sampled. During the interval between bursts the thermal neutron capture gamma ray population is sampled in two or more time intervals. The fast and epithermal neutron population measurements are combined to provide a measurement of formation porosity phi. The capture gamma ray measurements are combined to provide a simultaneous determination of the thermal neutron capture cross section Σ

  13. Simultaneous thermal neutron decay time and porosity logging system

    International Nuclear Information System (INIS)

    Schultz, W.E.; Smith, H.D.; Smith, M.P.

    1980-01-01

    An improved method and apparatus are described for simultaneously measuring the porosity and thermal neutron capture cross section of earth formations in situ in the vicinity of a well borehole using pulsed neutron well logging techniques. The logging tool which is moved through the borehole consists of a 14 MeV pulsed neutron source, an epithermal neutron detector and a combination gamma ray and fast neutron detector. The associated gating systems, counters and combined digital computer are sited above ground. (U.K.)

  14. Methods for processing of pulsed neutron logging data

    International Nuclear Information System (INIS)

    Iskenderov, V.G.

    1975-01-01

    Conditions were examined for calculating the lifetime of thermal neutrons in neutron-neutron logging by selecting optimum values for the time lag. The dispersion and mean square error of the calculated lifetime values for thermal neutrons are evaluated

  15. Pulsed power supply system for neutron well logging

    International Nuclear Information System (INIS)

    Hopkinson, E.C.

    1975-01-01

    A variable D. C. power supply and a variable A. C. power supply are coupled onto the upper end of a single conductor cable at the earth's surface and from the lower end of said cable to a well logging instrument. The A. C. voltage is used to provide filament power for the ion source accelerator tube. The D. C. voltage is used to provide power to fixed D. C. loads maintained constant by regulators once a threshold is reached. The D. C. voltage is raised above the threshold to control the pulsed acceleration voltage and hence neutron output by first feeding into a unijunction relaxation oscillator in combination with an SCR output which output is transformer coupled into a voltage multiplier circuit. An antilatch feature is provided for the SCR by transformer coupling the pulses on the SCR anode back to the base of a transistor in series with the cathode of the SCR. Two outputs of the voltage multiplier circuit are connected to the cathode and anode, respectively, of an ion source accelerator tube, the cathode being connected through a resistor to retard the ripple pulsing of the cathode to allow ionization of the accelerator tube

  16. Neutron capture in borehole logging

    International Nuclear Information System (INIS)

    Randall, R.R.

    1981-01-01

    The use is described of a pulsed source of fast neutrons and a radiation detector to measure the thermal neutron population decay rate in a well logging instrument. The macroscopic neutron absorption cross-section is calculated by taking the natural logarithm of the ratio of the detected radiation counts occurring within two measurement intervals of fixed duration and starting at a fixed time after a neutron burst. (U.K.)

  17. Pulsed neutron source well logging system

    International Nuclear Information System (INIS)

    Dillingham, M.E.

    1975-01-01

    A pulsed neutron source with a chamber containing a plurality of alpha emitting strips and beryllium targets coaxially mounted is described. A pulsed source is provided by rotation of the target to on-off positions along with electromagnetic and magnetic devices for positive locking and rotation. (U.S.)

  18. A neutron well logging system

    International Nuclear Information System (INIS)

    1980-01-01

    A pulsed neutron well logging system using a sealed off neutron generator tube is provided with a programmable digital neutron output control system. The control system monitors the target beam current and compares a function of this current with a pre-programmed control function to develop a control signal for the neutron generator. The control signal is used in a series regulator to control the average replenisher current of the neutron generator tube. The programmable digital control system of the invention also provides digital control signals as a function of time to provide ion source voltages. This arrangement may be utilized to control neutron pulses durations and repetition rates or to produce other modulated wave forms for intensity modulating the output of the neutron generator as a function of time. (Auth.)

  19. Use of pulsed-neutron capture logs to identify steam breakthrough

    International Nuclear Information System (INIS)

    Masse, P.J.; Gosney, T.C.; Long, D.L.

    1991-01-01

    This paper reports on identification of steam-breakthrough zones in a stacked sand/shale sequence with variable lateral continuity which is difficult. Such identification, however, would allow the modification of field operations to enhance recovery through improved vertical sweep and heat injection. Twenty pulsed-neutron capture (PNC) logs were run to identify the steam-breakthrough zone(s) in a seven-pattern area of Mobil's Middle expansion (MIDX) Steamflood Project in the South Belridge field. These PNC data were combined with data from recent replacement wells and a detailed geologic analysis. Evaluation of this combined information allowed identification of potential steam-breakthrough zone(s), and operations were modified to reduce and eliminate steam breakthrough

  20. Background subtraction system for pulsed neutron logging of earth boreholes

    International Nuclear Information System (INIS)

    Hertzog, R.C.

    1983-01-01

    The invention provides a method for determining the characteristics of earth formations surrounding a well borehole comprising the steps of: repetitively irradiating the earth formations surrounding the well bore with relatively short duration pulses of high energy neutrons; detecting during each pulse of high energy neutrons, gamma radiation due to the inelastic scattering of neutrons by materials comprising the earth formations surrounding the borehole and providing information representative thereof; detecting immediately following each such pulse of high energy neutrons, background gamma radiation due to thermal neutron capture and providing information representative thereof; and correcting the inelastic gamma representative information to compensate for said background representative information

  1. Time interval approach to the pulsed neutron logging method

    International Nuclear Information System (INIS)

    Zhao Jingwu; Su Weining

    1994-01-01

    The time interval of neighbouring neutrons emitted from a steady state neutron source can be treated as that from a time-dependent neutron source. In the rock space, the neutron flux is given by the neutron diffusion equation and is composed of an infinite terms. Each term s composed of two die-away curves. The delay action is discussed and used to measure the time interval with only one detector in the experiment. Nuclear reactions with the time distribution due to different types of radiations observed in the neutron well-logging methods are presented with a view to getting the rock nuclear parameters from the time interval technique

  2. Neutron--neutron logging

    International Nuclear Information System (INIS)

    Allen, L.S.

    1977-01-01

    A borehole logging tool includes a steady-state source of fast neutrons, two epithermal neutron detectors, and two thermal neutron detectors. A count rate meter is connected to each neutron detector. A first ratio detector provides an indication of the porosity of the formation surrounding the borehole by determining the ratio of the outputs of the two count rate meters connected to the two epithermal neutron detectors. A second ratio detector provides an indication of both porosity and macroscopic absorption cross section of the formation surrounding the borehole by determining the ratio of the outputs of the two count rate meters connected to the two thermal neutron detectors. By comparing the signals of the two ratio detectors, oil bearing zones and salt water bearing zones within the formation being logged can be distinguished and the amount of oil saturation can be determined. 6 claims, 2 figures

  3. Method and apparatus for neutron induced gamma ray logging for lithology identificaion

    International Nuclear Information System (INIS)

    Oliver, D.W.; Culver, R.B.

    1979-01-01

    A pulsed neutron generator in a well logging instrument is pulsed at a clock frequency of 20 KHz. Inelastic scatter gamma rays are detected during a first time interval coinciding with the neutron source being on and capture gamma rays are measured during a second interval subsequent to the end of each neutron burst. Only a single detected pulse, assuming detection occurs, is transmitted during each of the two detection intervals. Sync pulses are generated in the well logging instrument scaled down to a frequency of 200 Hz for transmission to the earth's surface. At the earth's surface, the scaled-down sync pulses are applied to a phase-locked loop system for regenerating the sync pulses to the same frequency as that of the clock frequency used to pulse the neutron source and to open the detection gates in the borehole instrument. The regenerated sync pulses are used in the surface instrumentation to route the pulses occurring in the inelastic interval into one section of a multichannel analyzer memory and the pulses occurring in the capture interval into another section of the multichannel analyzer. The use of memory address decoders, subtractors and ratio circuits enables both a carbon/oxygen ratio and a silicon/calcium ratio to be struck, substantially independent of the chlorine content of the borehole and formation

  4. Monte Carlo Simulation on Compensated Neutron Porosity Logging in LWD With D-T Pulsed Neutron Generator

    International Nuclear Information System (INIS)

    Zhang Feng; Hou Shuang; Jin Xiuyun

    2010-01-01

    The process of neutron interaction induced by D-T pulsed neutron generator and 241 Am-Be source was simulated by using Monte Carlo method. It is concluded that the thermal neutron count descend exponentially as the spacing increasing. The smaller porosity was, the smaller the differences between the two sources were. When the porosity reached 40%, the ratio of thermal neutron count generated by D-T pulsed neutron source was much larger than that generated by 241 Am-Be neutron source, and its distribution range was wider. The near spacing selected was 20-30 cm, and that of far spacing was about 60-70 cm. The detection depth by using D-T pulsed neutron source was almost unchanged under condition of the same sapcing, and the sensitivity of measurement to the formation porosity decreases. The results showed that it can not only guarantee the statistic of count, but also improve detection sensitivity and depth at the same time of increasing spacing. Therefore, 241 Am-Be neutron source can be replaced by D-T neutron tube in LWD tool. (authors)

  5. Neutron characteristic and spectroscopy logging methods and apparatus

    International Nuclear Information System (INIS)

    Antkiw, S.

    1977-01-01

    Earth formations surrounding a well bore are irradiated with pulses of fast neutrons, and gamma rays resulting from the ensuring thermal neutron capture interactions with nuclei of the formations are detected, from which measurements of the thermal neutron decay times characterizing the respective formations are derived. The gamma ray energy spectra of the respective formations are analyzed. Gating of the gamma ray detection periods is automatically controlled, both for the decay time and the spectroscopy functions, in accrdance with the measured values of the decay times. The duration and repetition rate of the neutron pulses are also controlled as a function of the measured decay times to provide an overall optimized decay time-spectroscopy operating cycle. spectroscopy outputs representative of formation lithology, salinity, porosity and shaliness are developed to supplement and improve decay time log interpretation

  6. Sync transmission method and apparatus for high frequency pulsed neutron spectral analysis systems

    International Nuclear Information System (INIS)

    Culver, R.B.

    1981-01-01

    An improved synchronization system was developed for high-frequency pulsed-neutron gamma ray well-logging which extends the upper limit of the usable source pulsing frequency. A clock is used to pulse the neutron generator at a given frequency and a scaler generates scaled-down sync pulses at a lower frequency. Radiation from the formations surrounding the borehole is detected and electrical signals related functionally to the radiation are generated. The scaled-down sync pulses and electrical signals are transmitted to the earth's surface via a seven conductor well logging cable. (DN)

  7. Distinguishing oil and water layers in a cracked porous medium using pulsed neutron logging data based on Hudson's crack theory

    Science.gov (United States)

    Zhang, Xueang; Yang, Zhichao; Tang, Bin; Wang, Renbo; Wei, Xiong

    2018-05-01

    During geophysical surveys, water layers may interfere with the detection of oil layers. In order to distinguish between oil and water layers in porous cracked media, research on the properties of the cracks, the oil and water layers, and their relation to pulsed neutron logging characteristics is essential. Using Hudson's crack theory, we simulated oil and water layers in a cracked porous medium with different crack parameters corresponding to the well log responses. We found that, in a cracked medium with medium-angle (40°-50°) cracks, the thermal neutron count peak value is higher and more sensitive than those in low-angle and high-angle crack environments; in addition, the thermal neutron density distribution shows more minimum values than in other cases. Further, the thermal neutron count and the rate of change for the oil layer are greater than those of the water layer, and the time spectrum count peak value for the water layer in middle-high-angle (40°-70°) cracked environments is higher than that of the oil layer. The thermal neutron density distribution sensitivity is higher in the water layer with a range of small crack angles (0°-30°) than in the oil layer with the same range of angles. In comparing the thermal neutron density distribution, thermal neutron count peak, thermal neutron density distribution sensitivity, and time spectrum maximum in the oil and water layers, we find that neutrons in medium-angle (40°-50°) cracked reservoirs are more sensitive to deceleration and absorption than those in water layers; neutrons in approximately horizontal (0°-30°) cracked water layers are more sensitive to deceleration than those in reservoirs. These results can guide future work in the cracked media neutron logging field.

  8. Status report on the development of a prompt fission neutron uranium borehole logging technique

    International Nuclear Information System (INIS)

    Smith, G.W.

    1977-05-01

    The prompt fission neutron (PFN) method of direct uranium measurement was studied. The PFN uranium logging technique measures the enhanced epithermal neutron population created by the prompt thermal fission of 235 U to assay uranium mineralization around a borehole. This neutron population exists for several hundred microseconds after a pulsed neutron source produces a burst of high energy (14 MeV) neutrons. A feasibility study established the basic relationship between the uranium concentration and the enhanced epithermal neutron count, and defined the major measurement perturbing factors. Following the feasibility study, development of a PFN prototype field probe was undertaken. A laboratory type neutron generator, the Controlatron, was modified for use in the probe. Field evaluation of the prototype system began in January 1976. Comparisons of neutron logs and natural gamma logs taken during this evaluation period clearly define many disequilibrium conditions as verified by ore grade estimates from core samples. The feasibility of the PFN logging technique to detect uranium in-situ has now been demonstrated

  9. Digital-to-analog device for continuous detection of neutron damping decrement in logging

    International Nuclear Information System (INIS)

    Sokolov, Yu.I.; Zinchenko, A.I.; Rudenko, Eh.L.

    1976-01-01

    Algorithms are analyzed for a continuous detection of the damping decrement (DD) of the thermal neutron density in time, characterizing absorptive and diffusion properties of a bed; an an automated measuring device has been developed. The design of a digital calculator involving reguired mathematical and logical operations in the DD measurement by the specified algorithms necessitated the use of a system of elements with a diode-transistor RC logic. Following laboratory tests the mock-up of the calculator was subjected to borehole tests as part of the pulsed neutron logging apparatus of the IGN-4 type. A continuous detection of the DD reciprocal with a parallel recording of the differential and integral curves of pulsed neutron-neutron logging has been performed. The borehole tests revealed the efficiency of the new device and the possibility of its use together with the apparatus of the IGN-4 type

  10. Examples of detection of water flow by oxygen activation on pulsed neutron logs

    International Nuclear Information System (INIS)

    de Rosset, W.H.M.

    1986-01-01

    Upward flow of water in cased wellbores may be detected with pulsed neutron capture (PNC) and gamma ray (GR) tools. Water entering tubing, casing and flowing behind pipe may similarly be evaluated qualitatively. Gamma ray background anomalies in PNC data and elevation of GR tool response occur when water is flowing above threshold velocities and volumes. The technique requires logging the well under static and flow conditions or logging at different tools speeds in a flowing well. Oxygen activation results in increased gamma ray count rates at each detector. PNC far detector and GR well log curves from each log run (flowing well, static well) are overlain. The increases for each curve are offset from the point of water entry by a distance similar to tool source-detector spacing. These offsets in gamma increase are 15-20 ft. higher for the GR than for the PNC far detector and distinguish oxygen activation due to flowing water from common hot spots. The amount of gamma ray increase is controlled by the velocity of upward flow of water past the tool, the amount of water flowing, and the distance of the flow from the tool. Prior planning is important to gain usable information in flowing wells. The upward relative velocity imposes maximal and minimal tool speeds to produce significant gamma increases, and tool speed must be adjusted to optimize gamma changes. Use of the technique to answer actual production problems is illustrated with examples. Insight was gained which led to the correction of the problem in each case

  11. Methods and apparatus for environmental correction of thermal neutron logs

    International Nuclear Information System (INIS)

    Preeg, W.E.; Scott, H.D.

    1983-01-01

    An on-line environmentally-corrected measurement of the thermal neutron decay time (tau) of an earth formation traversed by a borehole is provided in a two-detector, pulsed neutron logging tool, by measuring tau at each detector and combining the two tau measurements in accordance with a previously established empirical relationship of the general form: tau = tausub(F) +A(tausub(F) + tausub(N)B) + C, where tausub(F) and tausub(N) are the tau measurements at the far-spaced and near-spaced detectors, respectively, A is a correction coefficient for borehole capture cross section effects, B is a correction coefficient for neutron diffusion effects, and C is a constant related to parameters of the logging tool. Preferred numerical values of A, B and C are disclosed, and a relationship for more accurately approximating the A term to specific borehole conditions. (author)

  12. Pulsed neutron generator for use with pulsed neutron activation techniques

    International Nuclear Information System (INIS)

    Rochau, G.E.

    1980-01-01

    A high-output, transportable, pulsed neutron generator has been developed by Sandia National Laboratories for use with Pulsed Neutron Activation (PNA) techniques. The PNA neutron generator generates > 10 10 14 MeV D-T neutrons in a 1.2 millisecond pulse. Each operation of the unit will produce a nominal total neutron output of 1.2 x 10 10 neutrons. The generator has been designed to be easily repaired and modified. The unit requires no additional equipment for operation or measurement of output

  13. Design of auto-control high-voltage control system of pulsed neutron generator

    International Nuclear Information System (INIS)

    Lv Juntao

    2008-01-01

    It is difficult to produce multiple anode controlling time sequences under different logging mode for the high-voltage control system of the conventional pulsed neutron generator. It is also difficult realize sequential control among anode high-voltage, filament power supply and target voltage to make neutron yield stable. To these problems, an auto-control high-voltage system of neutron pulsed generator was designed. It not only can achieve anode high-voltage double blast time sequences, which can measure multiple neutron blast time sequences such as Σ, activated spectrum, etc. under inelastic scattering mode, but also can realize neutron generator real-time measurement of multi-state parameters and auto-control such as target voltage pulse width modulation (PWM), filament current, anode current, etc., there by it can produce stable neutron yield and realize stable and accurate measurement of the pulsed neutron full spectral loging tool. (authors)

  14. A method to describe inelastic gamma field distribution in neutron gamma density logging.

    Science.gov (United States)

    Zhang, Feng; Zhang, Quanying; Liu, Juntao; Wang, Xinguang; Wu, He; Jia, Wenbao; Ti, Yongzhou; Qiu, Fei; Zhang, Xiaoyang

    2017-11-01

    Pulsed neutron gamma density logging (NGD) is of great significance for radioprotection and density measurement in LWD, however, the current methods have difficulty in quantitative calculation and single factor analysis for the inelastic gamma field distribution. In order to clarify the NGD mechanism, a new method is developed to describe the inelastic gamma field distribution. Based on the fast-neutron scattering and gamma attenuation, the inelastic gamma field distribution is characterized by the inelastic scattering cross section, fast-neutron scattering free path, formation density and other parameters. And the contribution of formation parameters on the field distribution is quantitatively analyzed. The results shows the contribution of density attenuation is opposite to that of inelastic scattering cross section and fast-neutron scattering free path. And as the detector-spacing increases, the density attenuation gradually plays a dominant role in the gamma field distribution, which means large detector-spacing is more favorable for the density measurement. Besides, the relationship of density sensitivity and detector spacing was studied according to this gamma field distribution, therefore, the spacing of near and far gamma ray detector is determined. The research provides theoretical guidance for the tool parameter design and density determination of pulsed neutron gamma density logging technique. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Neutronics of pulsed spallation neutron sources

    International Nuclear Information System (INIS)

    Watanabe, Noboru

    2003-01-01

    Various topics and issues on the neutronics of pulsed spallation neutron sources, mainly for neutron scattering experiments, are reviewed to give a wide circle of readers a better understanding of these sources in order to achieve a high neutronic performance. Starting from what neutrons are needed, what the spallation reaction is and how to produce slow-neutrons more efficiently, the outline of the target and moderator neutronics are explained. Various efforts with some new concepts or ideas have already been devoted to obtaining the highest possible slow-neutron intensity with desired pulse characteristics. This paper also reviews the recent progress of such efforts, mainly focused on moderator neutronics, since moderators are the final devices of a neutron source, which determine the source performance. Various governing parameters for neutron-pulse characteristics such as material issues, geometrical parameters (shape and dimensions), the target-moderator coupling scheme, the ortho-para-hydrogen ratio, poisoning, etc are discussed, aiming at a high performance pulsed spallation source

  16. New neutron imaging using pulsed sources. Characteristics of a pulsed neutron source and principle of pulsed neutron imaging

    International Nuclear Information System (INIS)

    Kiyanagi, Yoshiaki

    2012-01-01

    Neutron beam is one of important tools to obtain the transmission image of an object. Until now, steady state neutron sources such as reactors are mainly used for this imaging purpose. Recently, it has been demonstrated that pulsed neutron imaging based on accelerator neutron sources can provide a real-space distribution of physical information of materials such as crystallographic structure, element, temperature, hydrogen bound state, magnetic field and so on, by analyzing wavelength dependent transmission spectrum, which information cannot be observed or difficult to obtain with a traditional imaging method using steady state neutrons. Here, characteristics of the pulsed neutron source and principle of the pulsed neutron imaging are explained as a basic concept of the new method. (author)

  17. Cased Hole Evaluation Using Pulsed Neutron measurements and remedial actions on non-performing wells

    International Nuclear Information System (INIS)

    Mukerji, P.

    2002-01-01

    Advances in pulsed neutron spectroscopy tools have improved accuracy and precision of measured carbon-oxygen rations. The C/O ratios relate to the volumes of oil and water in the formation. Some of the improvements in accuracy and precision have resulted from better tool characterization in a wider variety of logging environments in the calibration facility and new spectral standards. The ability to combine advanced logging measurements has provided the operator with better diagnosis tools for identifying candidates for possible remedial actions. The successful diagnosis and treatment of water production problems requires the identification of specific influx zones. The information obtained from such logs allows effective treatment of unwanted wellbore fluid entries. This paper will present examples from logs run in the Niger delta. We will show how the application of pulsed neutron logs can optimise subsequent well intervention to reduce water production and/or increase oil production

  18. Pulsed neutron sources for epithermal neutrons

    International Nuclear Information System (INIS)

    Windsor, C.G.

    1978-01-01

    It is shown how accelerator based neutron sources, giving a fast neutron pulse of short duration compared to the neutron moderation time, promise to open up a new field of epithermal neutron scattering. The three principal methods of fast neutron production: electrons, protons and fission boosters will be compared. Pulsed reactors are less suitable for epithermal neutrons and will only be briefly mentioned. The design principle of the target producing fast neutrons, the moderator and reflector to slow them down to epithermal energies, and the cell with its beam tubes and shielding will all be described with examples taken from the new Harwell electron linac to be commissioned in 1978. A general comparison of pulsed neutron performance with reactors is fraught with difficulties but has been attempted. Calculation of the new pulsed source fluxes and pulse widths is now being performed but we have taken the practical course of basing all comparisons on extrapolations from measurements on the old 1958 Harwell electron linac. Comparisons for time-of-flight and crystal monochromator experiments show reactors to be at their best at long wavelengths, at coarse resolution, and for experiments needing a specific incident wavelength. Even existing pulsed sources are shown to compete with the high flux reactors in experiments where the hot neutron flux and the time-of-flight methods can be best exploited. The sources under construction can open a new field of inelastic neutron scattering based on energy transfer up to an electron volt and beyond

  19. Neutron logging reliability techniques and apparatus

    International Nuclear Information System (INIS)

    Johnstone, C.W.

    1978-01-01

    This invention relates in general to neutron logging of earth formations, and in particular, to novel apparatus and procedures for determining the validity, or reliability, of data derived at least in part by logging neutron characteristics of earth formations and, if desired, for affording verifiably accurate indications of such data

  20. Neutron logging reliability techniques and apparatus

    International Nuclear Information System (INIS)

    Johnstone, C.W.

    1974-01-01

    This invention relates in general to neutron logging of earth formations, and in particular, to novel apparatus and procedures for determining the validity, or reliability, of data derived at least in part by logging neutron characteristics of earth formations and, if desired, for affording verifiably accurate indications of such data. (author)

  1. Pulsed neutron generator for mass flow measurement using the pulsed neutron activation technique

    International Nuclear Information System (INIS)

    Rochau, G.E.; Hornsby, D.R.; Mareda, J.F.; Riggan, W.C.

    1980-01-01

    A high-output, transportable neutron generator has been developed to measure mass flow velocities in reactor safety tests using the Pulsed Neutron Activation (PNA) Technique. The PNA generator produces >10 10 14 MeV D-T neutrons in a 1.2 millisecond pulse. The Millisecond Pulse (MSP) Neutron Tube, developed for this application, has an expected operational life of 1000 pulses, and it limits the generator pulse repetition rate to 12 pulses/minute. A semiconductor neutron detector is included in the generator package to monitor the neutron output. The control unit, which can be operated manually or remotely, also contains a digital display with a BCD output for the neutron monitor information. The digital logic of the unit controls the safety interlocks and rejects transient signals which could accidently fire the generator

  2. Neutronics of pulsed spallation neutron sources

    CERN Document Server

    Watanabe, N

    2003-01-01

    Various topics and issues on the neutronics of pulsed spallation neutron sources, mainly for neutron scattering experiments, are reviewed to give a wide circle of readers a better understanding of these sources in order to achieve a high neutronic performance. Starting from what neutrons are needed, what the spallation reaction is and how to produce slow-neutrons more efficiently, the outline of the target and moderator neutronics are explained. Various efforts with some new concepts or ideas have already been devoted to obtaining the highest possible slow-neutron intensity with desired pulse characteristics. This paper also reviews the recent progress of such efforts, mainly focused on moderator neutronics, since moderators are the final devices of a neutron source, which determine the source performance. Various governing parameters for neutron-pulse characteristics such as material issues, geometrical parameters (shape and dimensions), the target-moderator coupling scheme, the ortho-para-hydrogen ratio, po...

  3. Monte Carlo Simulations of Neutron Oil well Logging Tools

    International Nuclear Information System (INIS)

    Azcurra, Mario

    2002-01-01

    Monte Carlo simulations of simple neutron oil well logging tools into typical geological formations are presented.The simulated tools consist of both 14 MeV pulsed and continuous Am-Be neutron sources with time gated and continuous gamma ray detectors respectively.The geological formation consists of pure limestone with 15% absolute porosity in a wide range of oil saturation.The particle transport was performed with the Monte Carlo N-Particle Transport Code System, MCNP-4B.Several gamma ray spectra were obtained at the detector position that allow to perform composition analysis of the formation.In particular, the ratio C/O was analyzed as an indicator of oil saturation.Further calculations are proposed to simulate actual detector responses in order to contribute to understand the relation between the detector response with the formation composition

  4. Monte Carlo simulations of neutron oil well logging tools

    International Nuclear Information System (INIS)

    Azcurra, Mario O.; Zamonsky, Oscar M.

    2003-01-01

    Monte Carlo simulations of simple neutron oil well logging tools into typical geological formations are presented. The simulated tools consist of both 14 MeV pulsed and continuous Am-Be neutron sources with time gated and continuous gamma ray detectors respectively. The geological formation consists of pure limestone with 15% absolute porosity in a wide range of oil saturation. The particle transport was performed with the Monte Carlo N-Particle Transport Code System, MCNP-4B. Several gamma ray spectra were obtained at the detector position that allow to perform composition analysis of the formation. In particular, the ratio C/O was analyzed as an indicator of oil saturation. Further calculations are proposed to simulate actual detector responses in order to contribute to understand the relation between the detector response with the formation composition. (author)

  5. Neutron logging reliability techniques and apparatus

    International Nuclear Information System (INIS)

    Johnstone, C.W.

    1975-01-01

    Apparatus and methods for verifying the validity of data derived at least in part by neutron logging of earth formations, and, where indicated, for affording neutron diffusion-corrected values of such data, are disclosed. (WHK)

  6. Exploration and grade control neutron logging

    International Nuclear Information System (INIS)

    Eisler, P.L.

    1982-01-01

    Techniques used in neutron logging in boreholes are discussed. They include the application of neutron probes to porosity measurements, to lithological determinations based on macroscopic cross-section measurements and measurements of the concentration of chemical constituents in rocks and ores

  7. Dual detector neutron lifetime log: theory and practical applications

    International Nuclear Information System (INIS)

    Serpas, C.J.; Wichmann, P.A.; Fertl, W.H.; DeVries, M.R.; Rndall, R.R.

    1977-01-01

    The Neutron Lifetime Log instrumentation has continued to evolve and now is equipped with dual detectors for increased ease in gas detection and also a ratio response for a simultaneous porosity determination. A good deal of experimentation was involved to minimize both lithology and salinity effects on the porosity indication. This paper contains a discussion of the theory and concepts related to the application of the Dual Detector Neutron Lifetime Log (DNLL). It is important to note that with these advances the recording of thermal neutron capture cross section (Σ) remains consistent with the past measurements of earlier generations of instruments as the most accurate determination of this parameter. A number of field examples of the newly logged results are shown. These field cases include Dual Detector NLL's run thru the drill strings of highly deviated holes when difficulties were encountered in getting conventional open hole logs to bottom, logs thru open perforations and hot radioactive zones, comparisons of the large and small diameter instruments, logs with anomalous fluids in the annulus, logs thru multiple casing strings, and a number of other examples

  8. Specific features of well logging of boreholes drilled on electrical nonconducting solutions

    International Nuclear Information System (INIS)

    Ruchkin, A.F.; Fomenko, V.G.

    1978-01-01

    Methods for identification of permeable strata and determination of their porosity and oil-gas saturation using standard combination of geophysical investigations in the boreholes drilled with nonaqueous and inert drilling fluids are considered. Geophysical combination consists of the methods indications of which are independent on electrical conductivity of drilling fluids. They are all modifications of radioactivity logging (gamma logging, neutron logging, neutron-gamma logging, gamma-gamma logging, pulsed neutron logging, nuclear-magnetic logging), acoustic logging and thermal logging

  9. Spallation neutrons pulsed sources

    International Nuclear Information System (INIS)

    Carpenter, J.

    1996-01-01

    This article describes the range of scientific applications which can use these pulsed neutrons sources: Studies on super fluids, measures to verify the crawling model for the polymers diffusion; these sources are also useful to study the neutron disintegration, the ultra cold neutrons. In certain applications which were not accessible by neutrons diffusion, for example, radiations damages, radionuclides production and activation analysis, the spallation sources find their use and their improvement will bring new possibilities. Among others contributions, one must notice the place at disposal of pulsed muons sources and neutrinos sources. (N.C.). 3 figs

  10. Instrumentation at pulsed neutron sources

    International Nuclear Information System (INIS)

    Carpenter, J.M.; Lander, G.H.; Windsor, C.G.

    1984-01-01

    Scientific investigations involving the use of neutron beams have been centered at reactor sources for the last 35 years. Recently, there has been considerable interest in using the neutrons produced by accelerator driven (pulsed) sources. Such installations are in operation in England, Japan, and the United States. In this article a brief survey is given of how the neutron beams are produced and how they can be optimized for neutron scattering experiments. A detailed description is then given of the various types of instruments that have been, or are planned, at pulsed sources. Numerous examples of the scientific results that are emerging are given. An attempt is made throughout the article to compare the scientific opportunities at pulsed sources with the proven performance of reactor installations, and some familiarity with the latter and the general field of neutron scattering is assumed. New areas are being opened up by pulsed sources, particularly with the intense epithermal neutron beams, which promise to be several orders of magnitude more intense than can be obtained from a thermal reactor

  11. Dual detector pulsed neutron logging for providing indication of formation porosity

    International Nuclear Information System (INIS)

    Hopkinson, E.C.

    1980-01-01

    A new improved apparatus for determining rock formation porosity was developed which is substantially independent of the formation salinity. The improvements achieved by using differing gating intervals for the two detectors. The rock formations surrounding the earth borehole are first pulse-irradiated with discrete bursts from a high-energy neutron source. The radiations at two different points in the formation are detected and electrical signals are generated. The electrical signals from the first point are gated for a shorter time interval than those from the second point. The gated first and second electrical signals are combined to determine the porosity of the formations. (DN)

  12. Log-inject-log in sand consolidation

    International Nuclear Information System (INIS)

    Murphy, R.P.; Spurlock, J.W.

    1977-01-01

    A method is described for gathering information for the determination of the adequacy of placement of sand consolidating plastic for sand control in oil and gas wells. The method uses a high neutron cross-section tracer which becomes part of the plastic and uses pulsed neutron logging before and after injection of the plastic. Preferably, the method uses lithium, boron, indium, and/or cadmium tracers. Boron oxide is especially useful and can be dissolved in alcohol and mixed with the plastic ingredients

  13. Observation of pulsed neutron Ramsey resonance

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, Y. [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba Ibaraki 305-0801 (Japan)]. E-mail: yasuhiro.masuda@kek.jp; Skoy, V. [Joint Institute for Nuclear Reasearch, 141980 Dubna, Moscow Region (Russian Federation); Ino, T. [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba Ibaraki 305-0801 (Japan); Jeong, S.C. [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba Ibaraki 305-0801 (Japan); Watanabe, Y. [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba Ibaraki 305-0801 (Japan)

    2007-07-15

    A Ramsey resonance for pulsed neutrons was observed. The separated oscillatory fields for nuclear magnetic resonance were synchronized with a neutron pulse, and then the Ramsey resonance was observed as a function of the neutron velocity. The phase of one of the oscillatory fields was modulated as a function of the neutron time of flight for a neutron velocity measurement.

  14. Pulsed neutron sources at Dubna

    International Nuclear Information System (INIS)

    Shabalin, E.P.

    1991-01-01

    In 1960 the first world repetitively pulsed reactor IBR was put into operation. It was the beginning of the story how fission based pulsed neutron sources at Dubna have survived. The engineers involved have experienced many successes and failures in the course of new sources upgrading to finally come to possess the world's brightest neutron source - IBR-2. The details are being reviewed through the paper. The fission based pulsed neutron sources did not reach their final state as yet- the conceptual views of IBR prospects are being discussed with the goal to double the thermal neutron peak flux (up to 2x10 16 ) and to enhance the cold neutron flux by 10 times (with the present one being as high that of the ISIS cold moderator). (author)

  15. Quantitative monitoring of gas flooding in oil-bearing reservoirs using a pulsed neutron tool

    International Nuclear Information System (INIS)

    Ruhovets, N.; Wyatt, D.F. Jr.

    1991-01-01

    This paper reports on quantitative monitoring of gas flooding in oil bearing reservoirs which is unique in that saturations of three fluids (gas, oil and water) in the effective pore space have to be determined, while in most other applications saturation behind casing is determined only for two fluids: hydrocarbons and water. A new method has been developed to monitor gas flooding of oil reservoirs. The method is based on computing two porosities: true effective (base) porosity determined before gas flooding, and apparent effective (monitor) porosity determined after gas flooding. The base porosity is determined from open and/or cased hole porosity logs run before the flooding. When open hole logs are available, the cased hole porosity logs are calibrated against open hole log. The monitor porosity is determined from one of the cased hole porosity logs, such as a neutron log or count rate ratio curve from a pulsed neutron log run after the gas flooding. The base and monitor porosities provide determination of the hydrogen index of the reservoir fluid after the flooding. This hydrogen index is then used to determine saturation of the flood agent after flooding. Water saturation after flooding can be determined from the equation which relates neutron total cross section (Σm) to volumetric constituent cross sections, using Σm values from a monitor run (after flooding)

  16. A Wide Spectrum Neutron Polarizer for a Pulsed Neutron Source

    International Nuclear Information System (INIS)

    Nikitenko, Yu.V.

    1994-01-01

    A wide spectrum neutron polarizer for a pulsed neutron source is considered. The polarizer is made in a form of a set of magnetized mirrors placed on a drum. Homogeneous rotation of the polarizer is synchronized with the power pulses of the neutron source. The polarizer may be utilized in a collimated neutron beam with cross section of the order of magnitude of 100 cm 2 within a wavelength from 2 up to 20 A on sources with a pulse repetition frequency up to 50 Hz. (author). 5 refs.; 3 figs

  17. Nuclear borehole logging for oil exploration

    International Nuclear Information System (INIS)

    Oelgaard, P.L.

    1989-01-01

    Reactor physics can be applied to the logging of boreholes for the exploration of oil and gas and the results obtained can be interpreted more correctly by use of reactor physics models, e.g. one-dimensional multi-group diffusion theory adapted for gamma quanta. The standard nuclear logging tools are: natural gamma, gamma density, neutron porosity and the pulsed-neutron tool. The models and interpretation procedures are discussed. 1 fig

  18. Study of general digital DC/pulse neutron generator

    International Nuclear Information System (INIS)

    Li Gang; Liu Zheng; Li Wensheng; Liu Hanlin; Liu Linmao

    2014-01-01

    Preliminary experimental results of digital DC/pulse neutron generator based on a ceramic drive-in target neutron tube for explosives detection are presented. The generator is a portable and on-off neutron source, and it can be controlled by remote PC. The generator can produce DC neutrons, pulse neutrons and multiple pulse neutrons. The maximum neutron yield is about 2 × 10"8 n/s, the minimum pulse width is 10 μs and the maximum pulse frequency is 10 kHz. Neutron yield and time-spectrum is measured in China Academy of Engineering Physics. The generator is suitable for explosive detection with PFTNA technology, and it can be used in other areas such as reactor measurements and on-line industrial test systems. (authors)

  19. Pulsed neutron sources at KAON

    International Nuclear Information System (INIS)

    Thorson, I.M.; Egelstaff, P.A.; Craddock, M.K.

    1991-01-01

    The proposed KAON Factory facility at TRIUMF consists of a number of synchrotrons and storage rings which offer proton beams of energies between 0.45 and 30 GeV with varying pulse amplitudes, widths and repetition rates. Various possibilities for feeding these beams to a pulsed neutron facility and their potential for future development are examined. The incremental cost of such a pulsed neutron facility is estimated approximately. (author)

  20. Neutron-neutron-resonance logging of boron in boreholes with the use of the PRKS-2 radiometer

    International Nuclear Information System (INIS)

    Vakhtin, B.S.; Ivanov, V.S.; Filippov, E.M.; Novoselov, A.V.

    1973-01-01

    The well rig of the PRKS-2 logging radiometer is supplemented with a probe device for neutron measurements permitting to vary the probe size from 20 to 45 cm. To decrease the natural gamma radiation effect an external lead shield 7-mm thick having 50-mm outer diameter is fixed on the instrument sleeve. The instrument is provided with a NaI detector and a set of foils of Cd, Ag, Rh, Tu, In, Ta, and a Pu-Be source of 1x10 6 n/sec strength. The optimal size of the probe is assumed as 25 cm. From the results of well measurements a better differentiation of neutron resonance logging was noticed in comparison with neutron gamma logging. Comparing the data obtained with those of kern analysis a calibration curve was derived of neutron resonance logging versus B for wells of 59 mm dia

  1. Glass scintillator pair for compensation neutron logging

    International Nuclear Information System (INIS)

    Ji Changsong; Li Xuezhi; Yiu Guangduo

    1985-01-01

    Glass scintillator pair types ST 1604 and ST 1605 for compensation of neutron logging is developed. The neutron sensitive material used is multistick lithium glass scintillators 3 and 4 mm in diameter respectively. Thermoneutron detection efficiencies are 50-60% and 100% respectively. The detection efficiency for 60 Co γ ray is lower than 0.3%. The type ST 1604 and ST 1605 may also be used as high sensitive neutron detectors in an intensive γ ray field

  2. Pulsed spallation Neutron Sources

    International Nuclear Information System (INIS)

    Carpenter, J.M.

    1994-01-01

    This paper reviews the early history of pulsed spallation neutron source development at Argonne and provides an overview of existing sources world wide. A number of proposals for machines more powerful than currently exist are under development, which are briefly described. The author reviews the status of the Intense Pulsed Neutron Source, its instrumentation, and its user program, and provides a few examples of applications in fundamental condensed matter physics, materials science and technology

  3. Pulsed spallation neutron sources

    International Nuclear Information System (INIS)

    Carpenter, J.M.

    1996-01-01

    This paper reviews the early history of pulsed spallation neutron source development ar Argonne and provides an overview of existing sources world wide. A number of proposals for machines more powerful than currently exist are under development, which are briefly described. The author reviews the status of the Intense Pulsed Neutron Source, its instrumentation, and its user program, and provide a few examples of applications in fundamental condensed matter physics, materials science and technology

  4. An in-situ check of the epithermal neutron log calibration

    International Nuclear Information System (INIS)

    Burkhard, N.R.

    1993-01-01

    The epithermal neutron log is used to measure the water content of the formation. The large hole epithermal neutron sonde (ENS) utilized at the Nevada Test Site (NTS) has been calibrated in the Hydrogen Content Test Facility (HCTF). These calibrations are used to correct the measured neutron count rate for the effects of tool stand-off and density. For some time, the suspicion has existed that the water contents that are calculated from the ENS data are too large. Hole U2gj represented a unique opportunity to check the validity of the ENS calibration under realistic logging conditions; a portion of the hole had been cemented and redrilled and then logged. The cements have a known water content and can be used as an in-situ calibration check. The author found that the water contents from the log data after processing with the existing calibrations are consistent with these known cement water contents. In addition, the study indicates that the raw neutron data might be more appropriately smoothed by using a median smoother rather than the currently utilized mean smoother

  5. An in-situ check of the epithermal neutron log calibration

    International Nuclear Information System (INIS)

    Burkhard, N.R.

    1993-09-01

    The epithermal neutron log is used to measure the water content of the formation. The large hole epithermal neutron sonde (ENS) that we utilize at the Nevada Test Site (NTS) has been calibrated in the Hydrogen Content Test Facility (HCTF). These calibrations are used to correct the measured neutron count rate for the effects of tool stand-off and density. For sometime, the suspicion has existed that the water contents that are calculated from the ENS data are too large. Hole U2gj represented a unique opportunity to check the validity of the ENS calibration under realistic logging conditions; a portion of the hole had been cemented and re drilled and then logged. The cements have a known water content and can be used as an in situ calibration check. I found that the water contents from the log data after processing with the existing calibrations are consistent with these known cement water contents. In addition, the study indicates that the raw neutron data might be more appropriately smoothed by using a median smoother rather than the currently utilized mean smoother

  6. Pulsed TRIGA reactor as substitute for long pulse spallation neutron source

    International Nuclear Information System (INIS)

    Whittemore, W.L.

    1999-01-01

    TRIGA reactor cores have been used to demonstrate various pulsing applications. The TRIGA reactor fuel (U-ZrH x ) is very robust especially in pulsing applications. The features required to produce 50 pulses per second have been successfully demonstrated individually, including pulse tests with small diameter fuel rods. A partially optimized core has been evaluated for pulses at 50 Hz with peak pulsed power up to 100 MW and an average power up to 10 MW. Depending on the design, the full width at half power of the individual pulses can range between 2000 μsec to 3000 μsec. Until recently, the relatively long pulses (2000 μsec to 3000 μsec) from a pulsed thermal reactor or a long pulse spallation source (LPSS) have been considered unsuitable for time-of-flight measurements of neutron scattering. More recently considerable attention has been devoted to evaluating the performance of long pulse (1000 to 4000 μs) spallation sources for the same type of neutron measurements originally performed only with short pulses from spallation sources (SPSS). Adequate information is available to permit meaningful comparisons between CW, SPSS, and LPSS neutron sources. Except where extremely high resolution is required (fraction of a percent), which does require short pulses, it is demonstrated that the LPSS source with a 1000 msec or longer pulse length and a repetition rate of 50 to 60 Hz gives results comparable to those from the 60 MW ILL (CW) source. For many of these applications the shorter pulse is not necessarily a disadvantage, but it is not an advantage over the long pulse system. In one study, the conclusion is that a 5 MW 2000 μsec LPSS source improves the capability for structural biology studies of macromolecules by at least a factor of 5 over that achievable with a high flux reactor. Recent studies have identified the advantages and usefulness of long pulse neutron sources. It is evident that the multiple pulse TRIGA reactor can produce pulses comparable to

  7. Model wells for nuclear well logging

    International Nuclear Information System (INIS)

    Tittle, C.W.

    1989-01-01

    Considerations needed in the design and construction of model wells for nuclear log calibration are covered, with special attention to neutron porosity logging and total γ-ray logging. Pulsed neutron decay-time and spectral γ-ray logging are discussed briefly. The American Petroleum Institute calibration facility for nuclear logs is a good starting point for similar or expanded facilities. A few of its shortcomings are mentioned; they are minor. The problem of fluid saturation is emphasized. Attention is given to models made of consolidated rock and those containing unconsolidated material such as Ottawa sand. Needed precautions are listed. A similarity method is presented for estimating the porosity index of formations that are not fully saturated. (author)

  8. Well-logging method using well-logging tools run through a drill stem test string for determining in-situ change in formation water saturation values

    International Nuclear Information System (INIS)

    Fertl, W.H.

    1975-01-01

    A logging tool (pulsed neutron or neutron-gamma ray) whose response indicates formation water saturation value, is run through an opening extending through a portion of a drill stem test string. A sample portion of the formation fluid in the zone of interest is removed and another logging run is made. The differences between the plots of the two logging runs indicate the formation potential productivity in the zone of interest

  9. Study of the reservoirs of Jurassic and Cretaceous periods in the south-cast slope of Central Kara-Kum vault using combination of acoustic logging, neutron-gamma logging, gamma logging, and electrical logging

    International Nuclear Information System (INIS)

    Meredov, T.M.; Baranov, M.I.

    1978-01-01

    Considered is the possibility of application of the combination of neutron-gamma logging, gamma logging al partitioncoustic logging and electrical logging to lithologica of sections, discovery reservoir layers in carbonate and terrigeneous sections as well as quantitative estimation of the porosity coefficients values at prospecting areas in the south-east slope of Central Kara-Kum vault. Neutron-gamma logging mostly makes it possible to partition carbonate rocks into limestones, dolomites and their interstitial variaties and to indicate sand stone layers with different degree of carbonate content

  10. New scientific horizons with pulsed spallation neutron sources

    International Nuclear Information System (INIS)

    Carlile, C.J.; Finney, J.L.

    1991-01-01

    Pulsed spallation sources are not just another way of producing neutrons: the time structure of the neutron pulse has consequences which allow new scientific areas to be investigated and traditional areas to be explored afresh. In addition to the high epithermal neutron component traditionally associated with pulsed sources the recent development of cold neutron techniques at ISIS illustrates that very high energy and momentum resolutions can be achieved on pulsed sources over a surprisingly wide range. (orig.)

  11. Pulsed radiation decay logging

    International Nuclear Information System (INIS)

    Mills, W.R. Jr.

    1983-01-01

    There are provided new and improved well logging processes and systems wherein the detection of secondary radiation is accomplished during a plurality of time windows in a manner to accurately characterize the decay rate of the secondary radiation. The system comprises a well logging tool having a primary pulsed radiation source which emits repetitive time-spaced bursts of primary radiation and detector means for detecting secondary radiation resulting from the primary radiation and producing output signals in response to the detected radiation. A plurality of measuring channels are provided, each of which produces a count rate function representative of signals received from the detector means during successive time windows occurring between the primary radiation bursts. The logging system further comprises means responsive to the measuring channels for producing a plurality of functions representative of the ratios of the radiation count rates measured during adjacent pairs of the time windows. Comparator means function to compare the ratio functions and select at least one of the ratio functions to generate a signal representative of the decay rate of the secondary radiation

  12. Electronic instrumentation system for pulsed neutron measurements

    International Nuclear Information System (INIS)

    Burda, J.; Igielski, A.; Kowalik, W.

    1982-01-01

    An essential point of pulsed neutron measurement of thermal neutron parameters for different materials is the registration of the thermal neutron die-away curve after a fast neutron bursts have been injected into the system. An electronic instrumentation system which is successfully applied for pulsed neutron measurements is presented. An important part of the system is the control unit which has been designed and built in the Laboratory of Neutron Parameters of Materials. (author)

  13. Neutron borehole logging correction technique

    International Nuclear Information System (INIS)

    Goldman, L.H.

    1978-01-01

    In accordance with an illustrative embodiment of the present invention, a method and apparatus is disclosed for logging earth formations traversed by a borehole in which an earth formation is irradiated with neutrons and gamma radiation produced thereby in the formation and in the borehole is detected. A sleeve or shield for capturing neutrons from the borehole and producing gamma radiation characteristic of that capture is provided to give an indication of the contribution of borehole capture events to the total detected gamma radiation. It is then possible to correct from those borehole effects the total detected gamma radiation and any earth formation parameters determined therefrom

  14. Quantitative and qualitative applications of the neutron-gamma borehole logging

    International Nuclear Information System (INIS)

    Charbucinski, J.; Aylmer, J.A.; Eisler, P.L.; Borsaru, M.

    1989-01-01

    Two neutron-γ borehole logging applications are described. In a quantitative application of the prompt-gamma neutron-activation analysis (PGNAA) technique, research was carried out both in the laboratory and at a mine to establish a suitable borehole logging technology for manganese-grade predictions. As an example of the qualitative application of PGNAA, the use of this method has been demonstrated for the determination of lithology. (author)

  15. Computer-based system for acquisition of nuclear well log data

    International Nuclear Information System (INIS)

    Meisner, J.E.

    1983-01-01

    There is described a computer-based well logging system, for acquiring nuclear well log data, including gamma ray energy spectrum and neutron population decay rate data, and providing a real-time presentation of the data on an operator's display based on a traversal by a downhole instrument of a prescribed borehole depth interval. The system has a multichannel analyzer including a pulse height analyzer and a memory. After a spectral gamma ray pulse signal coming from a downhole instrument over a logging cable is amplified and conditioned, the pulse height analyzer converts the pulse height into a digital code by peak detection, sample-and-hold action, and analog-to-digital conversion. The digital code defines the address of a memory location or channel, corresponding to a particular gamma ray energy and having a count value to be incremented. The spectrum data is then accessed by the system central processing unit (CPU) for analysis, and routed to the operator's display for presentation as a plot of relative gamma ray emissions activity versus energy level. For acquiring neutron decay rate data, the system has a multichannel scaling unit including a memory and a memory address generator. After a burst of neutrons downhole, thermal and epithermal neutron detector pulses build up and die away. Using the neutron source trigger as an initializing reference, the address generator produces a sequence of memory address codes, each code addressing the memory for a prescribed period of time, so as to define a series of time slots. A detector pulse signal produced during a time slot results in the incrementing of the count value in an address memory location. (author)

  16. Accelerator-based pulsed cold neutron source

    International Nuclear Information System (INIS)

    Inoue, Kazuhiko; Iwasa, Hirokatsu; Kiyanagi, Yoshiaki

    1979-01-01

    An accelerator-based pulsed cold neutron source was constructed. The accelerator is a 35 MeV electron linear accelerator with 1 kW average beam power. The cold neutron beam intensity at a specimen is equivalent to that of a research reactor of 10 14 n/cm 2 .s thermal flux in the case of the quasi-elastic neutron scattering measurements. In spite of some limitations to the universal uses, it has been demonstrated by this facility that the modest capacity accelerator-based pulsed cold neutron source is a highly efficient cold neutron source with low capital investment. Design philosophy, construction details, performance and some operational experiences are described. (author)

  17. Non-destructive diagnostics of irradiated materials using neutron scattering from pulsed neutron sources

    Energy Technology Data Exchange (ETDEWEB)

    Korenev, Sergey E-mail: sergey_korenev@steris.com; Sikolenko, Vadim

    2004-10-01

    The advantage of neutron-scattering studies as compared to the standard X-ray technique is the high penetration of neutrons that allow us to study volume effects. The high resolution of instrumentation on the basis neutron scattering allows measurement of the parameters of lattice structure with high precision. We suggest the use of neutron scattering from pulsed neutron sources for analysis of materials irradiated with pulsed high current electron and ion beams. The results of preliminary tests using this method for Ni foils that have been studied by neutron diffraction at the IBR-2 (Pulsed Fast Reactor at Joint Institute for Nuclear Research) are presented.

  18. Non-destructive diagnostics of irradiated materials using neutron scattering from pulsed neutron sources

    Science.gov (United States)

    Korenev, Sergey; Sikolenko, Vadim

    2004-09-01

    The advantage of neutron-scattering studies as compared to the standard X-ray technique is the high penetration of neutrons that allow us to study volume effects. The high resolution of instrumentation on the basis neutron scattering allows measurement of the parameters of lattice structure with high precision. We suggest the use of neutron scattering from pulsed neutron sources for analysis of materials irradiated with pulsed high current electron and ion beams. The results of preliminary tests using this method for Ni foils that have been studied by neutron diffraction at the IBR-2 (Pulsed Fast Reactor at Joint Institute for Nuclear Research) are presented.

  19. A history of nuclear well logging in the oil industry

    International Nuclear Information System (INIS)

    Tittle, C.W.

    1989-01-01

    Spurred by an interest in logging through steel casing γ-ray logging began in the late 1930s followed soon by neutron logging for porosity. These were the first two nuclear well logs. Gamma-gamma density logging was developed during the 1950s. Pulsed neutron lifetime logging appeared in the 1960s; the slim tools came in the early 1970s. Developments since then have included dual detector devices of several types which offered improved measurements or interpretation, γ-ray spectrometry logging (natural and neutron-induced) which identifies certain chemical elements, induced radioactivity logging, and the photoelectric absorption log, which, combined with the density log in a single tool, is known as litho-density logging. A combination of several γ-ray spectrometers in one tool, designed to determine 10 formation elements, was recently introduced, and a new neutron porosity tool measuring epithermal neutron die-away time has been developed. Digital transmission of logging data was a step forward in about 1975. Also, log interpretation techniques have greatly expanded since the advent of digital computers, and the microcomputer has had a distinct impact. It is now practical and economical to do iterative analysis on a suite of logs to obtain an optimum overall interpretation. (author)

  20. Pulsed White Spectrum Neutron Generator for Explosive Detection

    International Nuclear Information System (INIS)

    King, Michael J.; Miller, Gill T.; Reijonen, Jani; Ji, Qing; Andresen, Nord; Gicquel, Frederic; Kavlas, Taneli; Leung, Ka-Ngo; Kwan, Joe

    2008-01-01

    Successful explosive material detection in luggage and similar sized containers is a critical issue in securing the safety of all airline passengers. Tensor Technology Inc. has recently developed a methodology that will detect explosive compounds with pulsed fast neutron transmission spectroscopy. In this scheme, tritium beams will be used to generate neutrons with a broad energy spectrum as governed by the T(t,2n)4He fission reaction that produces 0-9 MeV neutrons. Lawrence Berkeley National Laboratory (LBNL), in collaboration with Tensor Technology Inc., has designed and fabricated a pulsed white-spectrum neutron source for this application. The specifications of the neutron source are demanding and stringent due to the requirements of high yield and fast pulsing neutron emission, and sealed tube, tritium operation. In a unique co-axial geometry, the ion source uses ten parallel rf induction antennas to externally couple power into a toroidal discharge chamber. There are 20 ion beam extraction slits and 3 concentric electrode rings to shape and accelerate the ion beam into a titanium cone target. Fast neutron pulses are created by using a set of parallel-plate deflectors switching between +-1500 volts and deflecting the ion beams across a narrow slit. The generator is expected to achieve 5 ns neutron pulses at tritium ion beam energies between 80-120 kV. First experiments demonstrated ion source operation and successful beam pulsing

  1. Development of pulse neutron coal analyzer

    International Nuclear Information System (INIS)

    Jing Shiwie; Gu Deshan; Qiao Shuang; Liu Yuren; Liu Linmao; Jing Shiwei

    2005-01-01

    This article introduced the development of pulsed neutron coal analyzer by pulse fast-thermal neutron analysis technology in the Radiation Technology Institute of Northeast Normal University. The 14 MeV pulse neutron generator and bismuth germanate detector and 4096 multichannel analyzer were applied in this system. The multiple linear regression method employed to process data solved the interferential problem of multiple elements. The prototype (model MZ-MKFY) had been applied in Changshan and Jilin power plant for about a year. The results of measuring the main parameters of coal such as low caloric power, whole total water, ash content, volatile content, and sulfur content, with precision acceptable to the coal industry, are presented

  2. YAP scintillators for resonant detection of epithermal neutrons at pulsed neutron sources

    International Nuclear Information System (INIS)

    Tardocchi, M.; Gorini, G.; Pietropaolo, A.; Andreani, C.; Senesi, R.; Rhodes, N.; Schooneveld, E. M.

    2004-01-01

    Recent studies indicate the resonance detector (RD) technique as an interesting approach for neutron spectroscopy in the electron volt energy region. This work summarizes the results of a series of experiments where RD consisting of YAlO 3 (YAP) scintillators were used to detect scattered neutrons with energy in the range 1-200 eV. The response of YAP scintillators to radiative capture γ emission from a 238 U analyzer foil was characterized in a series of experiments performed on the VESUVIO spectrometer at the ISIS pulsed neutron source. In these experiments a biparametric data acquisition allowed the simultaneous measurements of both neutron time-of-flight and γ pulse height (energy) spectra. The analysis of the γ pulse height and neutron time of flight spectra permitted to identify and distinguish the signal and background components. These measurements showed that a significant improvement in the signal-to-background ratio can be achieved by setting a lower level discrimination on the pulse height at about 600 keV equivalent photon energy. Present results strongly indicate YAP scintillators as the ideal candidate for neutron scattering studies with epithermal neutrons at both very low (<5 deg.) and intermediate scattering angles

  3. Detection of SNM by Pulsed Neutron Interrogation

    International Nuclear Information System (INIS)

    Pedersen, Bent; Mayorov, Valeriy; Roesgen, Eric; Mosconi, Marita; Crochemore, Jean-Michel; Ocherashvili, Aharon; Beck, Arie; Ettedgui, Hanania

    2014-01-01

    A method for the detection of special nuclear materials (SNM) in shielded containers which is both sensitive and easily applicable under field conditions is presented. The method applies neutron induced fission in SNM by means of an external pulsed neutron source with subsequent detection of the fast prompt fission neutrons. Liquid scintillation detectors surrounding the container under investigation are able to discriminate gamma rays from fast neutrons by the so-called pulse shape discrimination technique (PSD)

  4. Fissile mass estimation by pulsed neutron source interrogation

    Energy Technology Data Exchange (ETDEWEB)

    Israelashvili, I., E-mail: israelashvili@gmail.com [Nuclear Research Center of the Negev, P.O.B 9001, Beer Sheva 84190 (Israel); Dubi, C.; Ettedgui, H.; Ocherashvili, A. [Nuclear Research Center of the Negev, P.O.B 9001, Beer Sheva 84190 (Israel); Pedersen, B. [Nuclear Security Unit, Institute for Transuranium Elements, Joint Research Centre, Via E. Fermi, 2749, 21027 Ispra (Italy); Beck, A. [Nuclear Research Center of the Negev, P.O.B 9001, Beer Sheva 84190 (Israel); Roesgen, E.; Crochmore, J.M. [Nuclear Security Unit, Institute for Transuranium Elements, Joint Research Centre, Via E. Fermi, 2749, 21027 Ispra (Italy); Ridnik, T.; Yaar, I. [Nuclear Research Center of the Negev, P.O.B 9001, Beer Sheva 84190 (Israel)

    2015-06-11

    Passive methods for detecting correlated neutrons from spontaneous fissions (e.g. multiplicity and SVM) are widely used for fissile mass estimations. These methods can be used for fissile materials that emit a significant amount of fission neutrons (like plutonium). Active interrogation, in which fissions are induced in the tested material by an external continuous source or by a pulsed neutron source, has the potential advantages of fast measurement, alongside independence of the spontaneous fissions of the tested fissile material, thus enabling uranium measurement. Until recently, using the multiplicity method, for uranium mass estimation, was possible only for active interrogation made with continues neutron source. Pulsed active neutron interrogation measurements were analyzed with techniques, e.g. differential die away analysis (DDA), which ignore or implicitly include the multiplicity effect (self-induced fission chains). Recently, both, the multiplicity and the SVM techniques, were theoretically extended for analyzing active fissile mass measurements, made by a pulsed neutron source. In this study the SVM technique for pulsed neutron source is experimentally examined, for the first time. The measurements were conducted at the PUNITA facility of the Joint Research Centre in Ispra, Italy. First promising results, of mass estimation by the SVM technique using a pulsed neutron source, are presented.

  5. Method for controlling an accelerator-type neutron source, and a pulsed neutron source

    International Nuclear Information System (INIS)

    Givens, W.W.

    1991-01-01

    The patent deals with an accelerator-type neutron source which employs a target, an ionization section and a replenisher for supplying accelerator gas. A positive voltage pulse is applied to the ionization section to produce a burst of neutrons. A negative voltage pulse is applied to the ionization section upon the termination of the positive voltage pulse to effect a sharp cut-off to the burst of neutrons. 4 figs

  6. The Neutron-Gamma Pulse Shape Discrimination Method for Neutron Flux Detection in the ITER

    International Nuclear Information System (INIS)

    Xu Xiufeng; Li Shiping; Cao Hongrui; Yin Zejie; Yuan Guoliang; Yang Qingwei

    2013-01-01

    The neutron flux monitor (NFM), as a significant diagnostic system in the International Thermonuclear Experimental Reactor (ITER), will play an important role in the readings of a series of key parameters in the fusion reaction process. As the core of the main electronic system of the NFM, the neutron-gamma pulse shape discrimination (n-γ PSD) can distinguish the neutron pulse from the gamma pulse and other disturbing pulses according to the thresholds of the rising time and the amplitude pre-installed on the board, the double timing point CFD method is used to get the rising time of the pulse. The n-γ PSD can provide an accurate neutron count. (magnetically confined plasma)

  7. Identification of carbonate reservoirs based on well logging data for boreholes drilled using oil base muds

    International Nuclear Information System (INIS)

    Abdukhalikov, Ya.N; Serebrennikov, V.S.

    1979-01-01

    Experiment on carbonate reservoir identification according to well logging data for boreholes drilled using oil base muds is described. Pulse neutron-neutron logging (PNNL) was widely used at the territory of Pripyat' hole to solve the task. To evaluate volumetric clayiness of carbonate rocks the dependence of gamma-logging, that is data of gamma-logging against clayey rocks built for every hollow, is used. Quantitative estimation of clayiness of dense and clayey carbonate rocks-non-reservoirs is carried out on the basis of the data of neutron-gamma and acoustic logging. Porosity coefficient and lithological characteristic of rocks are also determined according to the data of acoustic and neutron gamma-logging

  8. Simulation of neutrons and gamma pulse signal and research on the pulse shape discrimination technology

    International Nuclear Information System (INIS)

    Zuo Guangxia; He Bin; Xu Peng; Qiu Xiaolin; Ma Wenyan; Li Sufen

    2012-01-01

    In neutrons detection, it is important to discriminate the neutron signals from the gamma-ray background. In this article, simulation of neutrons and gamma pulse signals is developed based on the LabVIEW platform. Two digital algorithms of the charge comparison method and the pulse duration time method are realized using 10000 simulation signals. Experimental results show that neutron and gamma pulse signals can be discriminated by the two methods, and the pulse duration time method is better than the charge comparison method. (authors)

  9. High Intensity, Pulsed, D-D Neutron Generator

    International Nuclear Information System (INIS)

    Williams, D.L.; Vainionpaa, J.H.; Jones, G.; Piestrup, M.A.; Gary, C.K.; Harris, J.L.; Fuller, M.J.; Cremer, J.T.; Ludewigt, Bernhard A.; Kwan, J.W.; Reijonen, J.; Leung, K.-N.; Gough, R.A.

    2008-01-01

    Single ion-beam RF-plasma neutron generators are presented as a laboratory source of intense neutrons. The continuous and pulsed operations of such a neutron generator using the deuterium-deuterium fusion reaction are reported. The neutron beam can be pulsed by switching the RF plasma and/or a gate electrode. These generators are actively vacuum pumped so that a continuous supply of deuterium gas is present for the production of ions and neutrons. This contributes to the generator's long life. These single-beam generators are capable of producing up to 1E10 n/s. Previously, Adelphi and LBNL have demonstrated these generators applications in fast neutron radiography, Prompt Gamma Neutron Activation Analysis (PGNAA) and Neutron Activation Analysis (NAA). Together with an inexpensive compact moderator, these high-output neutron generators extend useful applications to home laboratory operations.

  10. Inter-pulse high-resolution gamma-ray spectra using a 14 MeV pulsed neutron generator

    Science.gov (United States)

    Evans, L.G.; Trombka, J.I.; Jensen, D.H.; Stephenson, W.A.; Hoover, R.A.; Mikesell, J.L.; Tanner, A.B.; Senftle, F.E.

    1984-01-01

    A neutron generator pulsed at 100 s-1 was suspended in an artificial borehole containing a 7.7 metric ton mixture of sand, aragonite, magnetite, sulfur, and salt. Two Ge(HP) gamma-ray detectors were used: one in a borehole sonde, and one at the outside wall of the sample tank opposite the neutron generator target. Gamma-ray spectra were collected by the outside detector during each of 10 discrete time windows during the 10 ms period following the onset of gamma-ray build-up after each neutron burst. The sample was measured first when dry and then when saturated with water. In the dry sample, gamma rays due to inelastic neutron scattering, neutron capture, and decay were counted during the first (150 ??s) time window. Subsequently only capture and decay gamma rays were observed. In the wet sample, only neutron capture and decay gamma rays were observed. Neutron capture gamma rays dominated the spectrum during the period from 150 to 400 ??s after the neutron burst in both samples, but decreased with time much more rapidly in the wet sample. A signal-to-noise-ratio (S/N) analysis indicates that optimum conditions for neutron capture analysis occurred in the 350-800 ??s window. A poor S/N in the first 100-150 ??s is due to a large background continuum during the first time interval. Time gating can be used to enhance gamma-ray spectra, depending on the nuclides in the target material and the reactions needed to produce them, and should improve the sensitivity of in situ well logging. ?? 1984.

  11. Future opportunities with pulsed neutron sources

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, A D [Rutherford Appleton Lab., Chilton (United Kingdom)

    1996-05-01

    ISIS is the world`s most powerful pulsed spallation source and in the past ten years has demonstrated the scientific potential of accelerator-driven pulsed neutron sources in fields as diverse as physics, earth sciences, chemistry, materials science, engineering and biology. The Japan Hadron Project gives the opportunity to build on this development and to further realize the potential of neutrons as a microscopic probe of the condensed state. (author)

  12. Neutron die-away well logging

    International Nuclear Information System (INIS)

    Jacobson, L.A.

    1976-01-01

    Neutron die-away well logging is extensively used for the location and monitoring of hydrocarbon zones in cased wells. Casing prohibits the use of conventional open-hole electrical resistivity methods. Through an appropriate interpretation of the measured capture cross-section, it is possible to determine the fractional hydrocarbon content of the rock pore volume, provided that the interstitial water is moderately saline (Σ/sub w/ greater than or equal to .035 cm -1 ). Special sealed D-T accelerator tubes and high voltage supplies have been developed for this purpose. They must fit into a 25 mm design circle and operate at 175 0 C, producing approximately 10 8 neutron/sec average in repetitive bursts. In the Schlumberger method an electronic servo-system adjusts burst and measure-gate timing to minimize statistical uncertainty regardless of die-away time

  13. Workshop on polarized neutron filters and polarized pulsed neutron experiments

    International Nuclear Information System (INIS)

    Itoh, Shinichi

    2004-07-01

    The workshop was held in KEK by thirty-three participants on April 26, 2004. The polarized neutron filter method was only discussed. It consists of three parts; the first part was discussed on the polarized neutron methods, the second part on the polarized neutron experiments and the third on the pulse neutron spectrometer and polarized neutron experiments. The six papers were presented such as the polarized 3 He neutron spin filter, neutron polarization by proton polarized filter, soft master and neutron scattering, polarized neutron in solid physics, polarization experiments by chopper spectroscope and neutron polarization system in superHRPD. (S.Y.)

  14. Neutron generator tube ion source control

    International Nuclear Information System (INIS)

    Bridges, J.R.

    1982-01-01

    A system is claimed for controlling the output of a neutron generator tube of the deuterium-tritium accelerator type and having an ion source to produce sharply defined pulses of neutrons for well logging use. It comprises: means for inputting a relatively low voltage input control pulse having a leading edge and a trailing edge; means, responsive to the input control pulse, for producing a relatively high voltage ion source voltage pulse after receipt of the input pulse; and means, responsive to the input control pulse, for quenching, after receipt of the input pulse, the ion source control pulse, thereby providing a sharply time defined neutron output from the generator tube

  15. Elemental analysis using temporal gating of a pulsed neutron generator

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, Sudeep

    2018-02-20

    Technologies related to determining elemental composition of a sample that comprises fissile material are described herein. In a general embodiment, a pulsed neutron generator periodically emits bursts of neutrons, and is synchronized with an analyzer circuit. The bursts of neutrons are used to interrogate the sample, and the sample outputs gamma rays based upon the neutrons impacting the sample. A detector outputs pulses based upon the gamma rays impinging upon the material of the detector, and the analyzer circuit assigns the pulses to temporally-based bins based upon the analyzer circuit being synchronized with the pulsed neutron generator. A computing device outputs data that is indicative of elemental composition of the sample based upon the binned pulses.

  16. Calibration of a neutron log in partially saturated media. Part II. Error analysis

    International Nuclear Information System (INIS)

    Hearst, J.R.; Kasameyer, P.W.; Dreiling, L.A.

    1981-01-01

    Four sources or error (uncertainty) are studied in water content obtained from neutron logs calibrated in partially saturated media for holes up to 3 m. For this calibration a special facility was built and an algorithm for a commercial epithermal neutron log was developed that obtains water content from count rate, bulk density, and gap between the neutron sonde and the borehole wall. The algorithm contained errors due to the calibration and lack of fit, while the field measurements included uncertainties in the count rate (caused by statistics and a short time constant), gap, and density. There can be inhomogeneity in the material surrounding the borehole. Under normal field conditions the hole-size-corrected water content obtained from such neutron logs can have an uncertainty as large as 15% of its value

  17. Laser neutron generator

    International Nuclear Information System (INIS)

    Anan'in, O.B.; Bespalov, D.F.; Bykovskii, Yu.A.; Kozyrev, Yu.P.; Mints, A.Z.; Riabov, E.V.; Tsybin, A.S.; Cherkasov, Yu.; Shikanov, A.E.

    1986-01-01

    Information is presented concerning devices for producing intense neutrons flows, and may be utilized in nuclear geophysics for carrying out pulsed neutron logging of wells, in studies of the critical characteristics of nuclear reactors, for activation analysis, radiation therapy, defectoscopy, and so on

  18. New opportunities in neutron capture research using advanced pulsed neutron sources

    International Nuclear Information System (INIS)

    Bowman, C.D.

    1987-08-01

    The extraordinary neutron intensities available from the new spallation pulsed neutron sources open up exciting opportunities for basic and applied research in neutron nuclear physics. Prospective experiments are reviewed with particular attention to those with a strong connection to capture gamma-ray spectroscopy

  19. Importance of the metrological network for calibration of neutron logging methods

    International Nuclear Information System (INIS)

    Rysavy, F.

    1995-01-01

    The calibration characteristics of neutron logging instrumentation are discussed. The principles of the rock, plastics, and water models are briefly outlined. Indian limestone of 9% porosity is the primary standard in the neutron logging metrology network, from which secondary standards employed during certification measurements are derived. It is recommended that rock blocks should be used as national standards, and each secondary institution should possess a set of polyethylene cylinders, one of which would serve as the main standard for the institution in question. (J.B.)

  20. Implementation of a tree algorithm in MCNP code for nuclear well logging applications

    Energy Technology Data Exchange (ETDEWEB)

    Li Fusheng, E-mail: fusheng.li@bakerhughes.com [Baker Hughes Incorporated, 2001 Rankin Rd. Houston, TX 77073-5101 (United States); Han Xiaogang [Baker Hughes Incorporated, 2001 Rankin Rd. Houston, TX 77073-5101 (United States)

    2012-07-15

    The goal of this paper is to develop some modeling capabilities that are missing in the current MCNP code. Those missing capabilities can greatly help for some certain nuclear tools designs, such as a nuclear lithology/mineralogy spectroscopy tool. The new capabilities to be developed in this paper include the following: zone tally, neutron interaction tally, gamma rays index tally and enhanced pulse-height tally. The patched MCNP code also can be used to compute neutron slowing-down length and thermal neutron diffusion length. - Highlights: Black-Right-Pointing-Pointer Tree structure programming is suitable for Monte-Carlo based particle tracking. Black-Right-Pointing-Pointer Enhanced pulse height tally is developed for oilwell logging tool simulation. Black-Right-Pointing-Pointer Neutron interaction tally and gamma ray index tally for geochemical logging.

  1. Evaluation of neutron dosimetry techniques for well-logging operations

    International Nuclear Information System (INIS)

    Cummings, F.M.; Haggard, D.L.; Endres, G.W.R.

    1985-07-01

    Neutron dose and energy spectral measurements from 241 AmBe and a 14 MeV neutron generator were performed at a well-logging laboratory. The measurement technique included the tissue equivalent proportional counter, multisphere, two types of remmeters and five types of personnel neutron dosimeters. Several source configurations were used to attempt to relate data to field situations. The results of the measurements indicated that the thermoluminescent albedo dosimeter was the most appropriate personnel neutron dosimeter, and that the most appropriate calibration source would be the source normally employed in the field with the calibration source being used in the unmoderated configuration. 7 refs., 35 figs., 14 tabs

  2. Nuclear log interpretation by first principle

    International Nuclear Information System (INIS)

    Oelgaard, P.L.

    1988-07-01

    A weakness connected to the present interpretation of nuclear borehole logs is that the interdependence of the various logs and physical effects of importance for the tools are not always taken into account in a correct way. Therefore a new approach to the interpretation of nuclear borehole logs is considered. It is based on the logs obtained with the natural gamma, the neutron porosity, the gamma density, and the pulsed neutron tools. For each of these tools a model, taking into account the important physical effects, is established. These models are incorporated into a computer programme which from the tool signals calculates, by use of iteration, a consistent set of the corresponding formation properties. In the paper the models developed for the four tools and the interpretation programme are briefly described. An example of the use of the interpretation programme is given and compared with a conventional interpretation. (author)

  3. Permeability log using new lifetime measurements

    International Nuclear Information System (INIS)

    Dowling, D.J.; Boyd, J.F.; Fuchs, J.A.

    1975-01-01

    Comparative measurements of thermal neutron decay time are obtained for a formation after irradiation with a pulsed neutron source. Chloride ions in formation fluids are concentrated by the electrosmosis effect using charged poles on a well logging sonde. The formation is irradiated with fast neutrons and a first comparative measure of the thermal neutron decay time or neutron lifetime is taken. The chloride ions are then dispersed by acoustic pumping with a magnetostrictive transducer. The formation is then again irradiated with fast neutrons and a comparative measure of neutron lifetime is taken. The comparison is a function of the variation in chloride concentration between the two measurements which is related to formation permeability

  4. Pulsed neutron activation calibration technique

    International Nuclear Information System (INIS)

    Kehler, P.

    1979-01-01

    A pulsed neutron activation (PNA) for measurement of two-phase flow consists of a pulsed source of fast neutron to activate the oxygen in a steam-water mixture. Flow is measured downstream by an NaI detector. Measured counts are sorted by a multiscaler into different time channels. A counts vs. time distribution typical for two-phase flow with slip between the two phases is obtained. Proper evaluation for the counts/time distribution leads to flow-regime independent equations for the average of the inverse transil time and the average density. After calculation of the average mass flow velocity, the true mass flow is derived

  5. Design and characterisation of a pulsed neutron interrogation facility

    International Nuclear Information System (INIS)

    Favalli, A.; Pedersen, B.

    2007-01-01

    The Joint Research Centre recently obtained a license to operate a new experimental device intended for research in the field of nuclear safeguards. The research projects currently being planned for the new device includes mass determination of fissile materials in matrices and detection of contraband non-nuclear materials. The device incorporates a commercial pulsed neutron generator and a large graphite mantle surrounding the sample cavity. In this configuration, a relatively high thermal neutron flux with a long lifetime is achieved inside the sample cavity. By pulsing the neutron generator, a sample may be interrogated by a pure thermal neutron flux during repeated time periods. The paper reports on the design of the new device and the pulsed fast and thermal neutron source. The thermal neutron flux caused by the neutron generator and the graphite structure has been characterised by foil activation, fission chamber and 3 He proportional counter measurements. (authors)

  6. Neutron induced current pulses in fission chambers

    International Nuclear Information System (INIS)

    Taboas, A.L.; Buck, W.L.

    1978-01-01

    The mechanism of neutron induced current pulse generation in fission chambers is discussed. By application of the calculated detector transfer function to proposed detector current pulse shapes, and by comparison with actually observed detector output voltage pulses, a credible, semi-empirical, trapezoidal pulse shape of chamber current is obtained

  7. Condensed matter research using pulsed neutron sources: a bibliography

    International Nuclear Information System (INIS)

    Mildner, D.F.R.; Stirling, G.C.

    1976-05-01

    This report is an updated revision of RL-75-095 'Condensed Matter Research Using Pulsed Neutron Sources: A Bibliography'. As before, the survey lists published papers concerning (a) the production of high intensity neutron pulses suitable for thermal neutron scattering research, (b) moderating systems for neutron thermalization and pulse shaping, (c) techniques and instrumentation for diffraction and inelastic scattering at pulsed sources, and (d) their application to research problems concerning the structural and dynamical properties of condensed matter. Papers which deal with the white beam time-of-flight technique at steady state reactors have also been included. A number of scientists have brought to the author's attention papers which have been published since the previous edition. They are thanked and encouraged to continue the cooperation so that the bibliography may be updated periodically. (author)

  8. Short pulse neutron generator

    Science.gov (United States)

    Elizondo-Decanini, Juan M.

    2016-08-02

    Short pulse neutron generators are described herein. In a general embodiment, the short pulse neutron generator includes a Blumlein structure. The Blumlein structure includes a first conductive plate, a second conductive plate, a third conductive plate, at least one of an inductor or a resistor, a switch, and a dielectric material. The first conductive plate is positioned relative to the second conductive plate such that a gap separates these plates. A vacuum chamber is positioned in the gap, and an ion source is positioned to emit ions in the vacuum chamber. The third conductive plate is electrically grounded, and the switch is operable to electrically connect and disconnect the second conductive plate and the third conductive plate. The at least one of the resistor or the inductor is coupled to the first conductive plate and the second conductive plate.

  9. Moving converter as the possible tool for producing ultra-cold neutrons on pulsed neutron sources

    International Nuclear Information System (INIS)

    Pokotilovskij, Yu.N.

    1991-01-01

    A method is proposed for producing ultra-cold neutrons (UCN) at aperiodic pulse neutron sources. It is based on the use of the fast moving cooled converter of UCN in the time of the neutron pulse and includes the trapping of generated UCN's in a moving trap. 6 refs.; 2 figs

  10. Beryllium neutron activation detector for pulsed DD fusion sources

    International Nuclear Information System (INIS)

    Talebitaher, A.; Springham, S.V.; Rawat, R.S.; Lee, P.

    2011-01-01

    A compact fast neutron detector based on beryllium activation has been developed to perform accurate neutron fluence measurements on pulsed DD fusion sources. It is especially well suited to moderate repetition-rate ( 9 Be(n,α) 6 He cross-section, energy calibration of the proportional counters, and numerical simulations of neutron interactions and beta-particle paths using MCNP5. The response function R(E n ) is determined over the neutron energy range 2-4 MeV. The count rate capability of the detector has been studied and the corrections required for high neutron fluence measurements are discussed. For pulsed DD neutron fluencies >3×10 4 cm -2 , the statistical uncertainty in the fluence measurement is better than 1%. A small plasma focus device has been employed as a pulsed neutron source to test two of these new detectors, and their responses are found to be practically identical. Also the level of interfering activation is found to be sufficiently low as to be negligible.

  11. High count problems in elemental analysis using pulsed neutron inelastic scattering

    Energy Technology Data Exchange (ETDEWEB)

    Vartsky, D; Wielopolski, L; Ellis, K J; Cohn, S H [Brookhaven National Lab., Upton, NY (USA). Medical Dept.

    1983-03-01

    Elemental analysis by neutron inelastic scattering using a miniature intense pulsed neutron source ('Zetatron') was evaluated. The particular problems associated with detector pulse-pile-up during the neutron burst and the limited ability of the analyzer to process on average more than one detector pulse per neutron burst were examined. The severity of these problems is described and a solution using a multiple ADC system is proposed.

  12. Development of resonant detectors for epithermal neutron spectroscopy at pulsed neutron sources

    International Nuclear Information System (INIS)

    Tardocchi, M.; Pietropaolo, A.; Senesi, R.; Andreani, C.; Gorini, G.

    2004-01-01

    New perspectives for epithermal neutron spectroscopy are opened by the development of new detectors for inverse geometry time of flight spectrometers at pulsed neutron sources. One example is the Very Low Angle Detector (VLAD) bank planned to be delivered, within the next 4 years, within the eVERDI project, on the neutron spectrometer VESUVIO, at the ISIS pulsed neutron source (UK). VLAD will extend the (q,ω) kinematical region for neutron scattering to low wavefactor transfer (q -1 ) still keeping energy transfer >1 eV, thus allowing the investigations of new experimental studies in condensed matter systems. The technique being developed for detection of epithermal neutrons, within this low q and high-energy transfer region, is the Resonance Detection Technique. In this work, the state of the detector development will be presented with special focus on the results obtained with some prototype detectors, namely YAP scintillators and cadmium-zinc-telluride semiconductors

  13. Gamma–neutron imaging system utilizing pulse shape discrimination with CLYC

    International Nuclear Information System (INIS)

    Whitney, Chad M.; Soundara-Pandian, Lakshmi; Johnson, Erik B.; Vogel, Sam; Vinci, Bob; Squillante, Michael; Glodo, Jarek; Christian, James F.

    2015-01-01

    Recently, RMD has investigated the use of CLYC (Cs 2 LiYCl 6 :Ce), a new and emerging scintillation material, in a gamma–neutron coded aperture imaging system based on RMD's commercial RadCam TM instrument. CLYC offers efficient thermal neutron detection, fast neutron detection capabilities, excellent pulse shape discrimination (PSD), and gamma-ray energy resolution as good as 4% at 662 keV. PSD improves the isolation of higher energy gammas from thermal neutron interactions (>3 MeV electron equivalent peak), compared to conventional pulse height techniques. The scintillation emission time in CLYC provides the basis for PSD; where neutron interactions result in a slower emission rise and decay components while gamma interactions result in a faster emission components. By creating a population plot based on the ratio of the decay tail compared to the total integral amplitude (PSD ratio), discrimination of gammas, thermal neutrons, and fast neutrons is possible. Previously, we characterized the CLYC-based RadCam system for imaging gammas and neutrons using a layered W-Cd coded aperture mask and employing only pulse height discrimination. In this paper, we present the latest results which investigate gamma-neutron imaging capabilities using PSD. An FPGA system is used to acquire the CLYC–PSPMT last dynode signals, determine a PSD ratio for each event, and compare it to a calibrated PSD cutoff. Each event is assigned either a gamma (low) or neutron (high) flag signal which is then correlated with the imaging information for each event. - Highlights: • The latest results are presented for our CLYC RadCam-2 system which investigate gamma–neutron imaging using pulse shape discrimination. • CLYC RadCam-2 system successfully discriminates gammas, thermal neutrons, and fast neutrons by employing a fully integrated, FPGA-based PSD system. • Imaging of our 252 Cf source was possible using both pulse height and pulse shape discrimination with CLYC. • Imaging

  14. Neutron diffraction on pulsed sources

    International Nuclear Information System (INIS)

    Aksenov, V.L.; Balagurov, A.M.

    2016-01-01

    The possibilities currently offered and major scientific problems solved by time-of-flight neutron diffraction are reviewed. The reasons for the rapid development of the method over the last two decades has been mainly the emergence of third generation pulsed sources with a MW time-averaged power and advances in neutron-optical devices and detector systems. The paper discusses some historical aspects of time-of-flight neutron diffraction and examines the contribution to this method by F.L.Shapiro whose 100th birth anniversary was celebrated in 2015. The state of the art with respect to neutron sources for studies on output beams is reviewed in a special section. [ru

  15. Quantitative and qualitative applications of the neutron-gamma borehole logging

    International Nuclear Information System (INIS)

    Charbucinski, J.; Eisler, P.L.; Borsaru, M.; Aylmer, J.A.

    1990-01-01

    Two examples of neutron-gamma borehole logging application are described. In the quantitative application of the PGNAA technique, research was carried out both in the laboratory and at a mine to establish a suitable borehole logging technology for Mn-grade predictions. As an example of qualitative application of PGNAA, use of this method has been demonstrated for determination of lithology. (author). 4 refs, 10 figs, 7 tabs

  16. Get better cased well data with the carbon/oxygen log

    International Nuclear Information System (INIS)

    Fertl, W.H.; Frost, E.

    1982-01-01

    Using case studies from heavy oil environments in the U.S. and Canada, it is shown how the continuous carbon/oxygen log, a type of pulsed neutron log, has proven an effective cased-hole reservoir evaluation and monitoring device. The article is a follow-up to one last month that detailed how the C/O log operates and reviewed case studies of its use in sandstone and carbonate environments

  17. Method and apparatus for epithermal neutron porosity well logging

    International Nuclear Information System (INIS)

    Hertzog, R.C.; Loomis, W.A.; Wraight, P.

    1991-01-01

    This patent describes a method for investigating the porosity of a subsurface earth formation surrounding a borehole. It comprises repetitively irradiating the borehole and earth formation with discrete bursts of high energy neutrons from a neutron source, which neutrons interact with nuclei of the materials in the borehole and the formation to produce therein populations of epithermal neutrons; detecting the populations of epithermal neutrons at near and far locations in the borehole spaced apart longitudinally by different distances from the neutron source; generating count signals indicative of the magnitudes of the detected epithermal neutron populations at the respective near and far locations; detecting the decay of the epithermal neutron populations following the neutron bursts at least at one location in the borehole and generating signals representative thereof; deriving from the decay signals a signal indicative of the slowing down time of epithermal neutrons in the formation of the at least one location; and deriving from the near and far count signals and the slowing down time signal a measurement signal representative of the porosity of the formation surrounding the borehole inherently compensated for the effects of tool standoff on the responses of the logging tool

  18. S-process studies using single and pulsed neutron exposures

    Science.gov (United States)

    Beer, H.

    The formation of heavy elements by slow neutron capture (s-process) is investigated. A pulsed neutron irradiation leading to an exponential exposure distribution is dominant for nuclei from A = 90 to 200. For the isotopes from iron to zirconium an additional 'weak' s-process component must be superimposed. Calculations using a single or another pulsed neutron exposure for this component have been carried out in order to reproduce the abundance pattern of the s-only and s-process dominant isotopes. For the adjustment of these calculations to the empirical values, the inclusion of new capture cross section data on Se76 and Y89 and the consideration of the branchings at Ni63, Se79, and Kr85 was important. The combination of an s-process with a single and a pulsed neutron exposure yielded a better representation of empirical abundances than a two component pulsed s-process.

  19. S-process studies using single and pulsed neutron exposures

    International Nuclear Information System (INIS)

    Beer, H.

    1986-01-01

    The formation of heavy elements by slow neutron capture (s-process) is investigated. A pulsed neutron irradiation leading to an exponential exposure distribution is dominant for nuclei from A=90 to 200. For the isotopes from iron to zirconium an additional ''weak'' s-process component must be superimposed. Calculations using a single or another pulsed neutron exposure for this component have been carried out in order to reproduce the abundance pattern of the s-only and s-process dominant isotopes. For the adjustment of these calculations to the empirical values, including new capture cross section data on Se76 and Y89 and the consideration of the branchings at Ni63, Se79, and Kr85 was important. The combination of a s-process with a single and a pulsed neutron exposure yielded a better representation of empirical abundances than a two component pulsed s-process

  20. Development of advanced radiation monitors for pulsed neutron fields

    CERN Document Server

    AUTHOR|(CDS)2081895

    The need of radiation detectors capable of efficiently measuring in pulsed neutron fields is attracting widespread interest since the 60s. The efforts of the scientific community substantially increased in the last decade due to the increasing number of applications in which this radiation field is encountered. This is a major issue especially at particle accelerator facilities, where pulsed neutron fields are present because of beam losses at targets, collimators and beam dumps, and where the correct assessment of the intensity of the neutron fields is fundamental for radiation protection monitoring. LUPIN is a neutron detector that combines an innovative acquisition electronics based on logarithmic amplification of the collected current signal and a special technique used to derive the total number of detected neutron interactions, which has been specifically conceived to work in pulsed neutron fields. Due to its special working principle, it is capable of overcoming the typical saturation issues encountere...

  1. Small accelerator-based pulsed cold neutron sources

    International Nuclear Information System (INIS)

    Lanza, Richard C.

    1997-09-01

    Small neutron sources could be used by individual researchers with the convenience of an adequate local facility. Although these sources would produce lower fluxes than the national facilities, for selected applications, the convenience and availability may overcome the limitations on source strength. Such sources might also be useful for preliminary testing of ideas before going to a larger facility. Recent developments in small, high-current pulsed accelerators makes possible such a local source for pulsed cold neutrons.

  2. Benchmark neutron porosity log calculations

    International Nuclear Information System (INIS)

    Little, R.C.; Michael, M.; Verghese, K.; Gardner, R.P.

    1989-01-01

    Calculations have been made for a benchmark neutron porosity log problem with the general purpose Monte Carlo code MCNP and the specific purpose Monte Carlo code McDNL. For accuracy and timing comparison purposes the CRAY XMP and MicroVax II computers have been used with these codes. The CRAY has been used for an analog version of the MCNP code while the MicroVax II has been used for the optimized variance reduction versions of both codes. Results indicate that the two codes give the same results within calculated standard deviations. Comparisons are given and discussed for accuracy (precision) and computation times for the two codes

  3. A comparison of the moisture gauge and the neutron log in air-filled holes at NTS

    International Nuclear Information System (INIS)

    Hearst, J.R.; Carlson, R.C.

    1993-08-01

    Two methods are commonly used to measure water content of geologic materials by neutron diffusion, the moisture gauge and the neutron log. Both are used at NTS, the moisture gauge in tunnels, the neutron log in vertical drilled holes. In this work, the moisture gauge and the neutron log are compared for use in air-filled holes NTS. The measurement instruments have evolved with very different operational characteristics and one important physics difference, the source to detector spacing. The moisture gauge has a very short, 0--6 cm spacing, with little internal shielding, and count increases with water. The neutron log has a long spacing, 30--50 cm, substantial internal shielding, and exhibits decreasing count with increasing water. The moisture gauge gives better bed resolution than the neutron log. Because its count increases with water, the moisture gauge is more strongly affected by water in the borehole, especially in dry formations. In these conditions the neutron log is the method of choice. In air-filled holes, if source size or logging time is not a constraint, the relative sensitivity of the two tools to water is determined by the relative strengths of borehole effects as fluid, holesize, or tool-wall gap. If source size is a constraint for safety reasons, the short spacing provides higher countrates for a given detector efficiency and thus better relative precision in determining the true count. If source size is limited because of detector or electronics saturation, the short spacing will be better at high water content, while the long spacing will be better at low water content. The short spacing may have an advantage because it can make better contact with the hole wall and can be more easily corrected for gap. The long spacing tool is currently used in vertical holes at NTS because that is the only tool available from logging contractors. Since they are most concerned with high water contents, the short spacing tool could prove to be better

  4. Effect of double false pulses in calibrated neutron coincidence collar during measuring time-correlated neutrons from PuBe neutron sources

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Tam Cong, E-mail: tam.nguyen.cong@energia.mta.hu; Huszti, Jozsef; Nguyen, Quan Van

    2015-09-01

    Effect of double false pulses of preamplifiers in neutron coincidence collar was investigated to explain non-parallel shape of calibrated D/S–M{sub Pu} curves of two commercial neutron coincidence collars, JCC-31 and JCC-13. Two curves, which were constructed from D/S ratio (doubles and singles count rate), and Pu content M{sub Pu}, of the same set of secondary standard PuBe neutron sources, should be parallel. Non-parallelism rises doubt about usability of the method based on this curve for determination of Pu content in PuBe neutron sources. We have shown in three steps that the problem originates from double false pulses of preamplifiers in JCC-13. First we used a pulse train diagram for analyzing the non-parallel shape, second we used Rossi-Alpha distribution measured by pulse train recorder developed in our institute and finally, we investigated the effect of inserted noise pulses. This implies a new type of QA test option in traditional multiplicity shift registers for excluding presence of double false pulses.

  5. PNG-300 a nanosecond pulsed neutron generator

    International Nuclear Information System (INIS)

    Sztaricskai, T.; Vasvary, L.; Petoe, G.C.; Devkin, B.V.

    1985-01-01

    The design and operation of a nanosecond-pulse neutron generator is reported. It was constructed for the measurement of prompt neutron and gamma radiation in experimental studies of fast neutron reactions by time of flight techniques. The acceleration voltage is 300 kV and the total resolution of the generator-neutron spectrometer system is 2 ns. The ion-optical system, the vacuum system and the control of the neutron generator is described in detail. The equipment was used for prompt neutron and gamma radiation induced in construction materials. (R.P.)

  6. 50 mm Diameter digital DC/pulse neutron generator for subcritical reactor test

    International Nuclear Information System (INIS)

    Li Gang; Zhang Zhongshuai; Chi Qian; Liu Linmao

    2012-01-01

    A 50 mm diameter digital DC/pulse neutron generator was developed with 25 mm ceramic drive-in target neutron tube. It was applied in the subcritical reactor test of China Institute of Atomic Energy (CIAE). The generator can produce neutron in three modes: DC, pulse and multiple pulse. The maximum neutron yield of the generator is 1 × 10 8 n/s, while the maximum pulse frequency is 10 kHz, and the minimum pulse width is 10 μs. As a remote controlled generator, it is small in volume, easy to be connected and controlled. The tested results indicate that penning ion source has the feature of delay time in glow discharge, and it is easier for glow discharge to happen when switching the DC voltage of penning ion source into pulse. According to these two characteristics, the generator has been modified. This improved generator can be used in many other areas including Prompt Gamma Neutron Activation Analysis (PGNAA), neutron testing and experiment.

  7. 50 mm Diameter digital DC/pulse neutron generator for subcritical reactor test

    Energy Technology Data Exchange (ETDEWEB)

    Li Gang; Zhang Zhongshuai [Northeast Normal University, Changchun 130024 (China); Chi Qian [Guang Hua College of Chang Chun University, Changchun 130117 (China); Liu Linmao, E-mail: ll888@nenu.edu.cn [Northeast Normal University, Changchun 130024 (China)

    2012-11-01

    A 50 mm diameter digital DC/pulse neutron generator was developed with 25 mm ceramic drive-in target neutron tube. It was applied in the subcritical reactor test of China Institute of Atomic Energy (CIAE). The generator can produce neutron in three modes: DC, pulse and multiple pulse. The maximum neutron yield of the generator is 1 Multiplication-Sign 10{sup 8} n/s, while the maximum pulse frequency is 10 kHz, and the minimum pulse width is 10 {mu}s. As a remote controlled generator, it is small in volume, easy to be connected and controlled. The tested results indicate that penning ion source has the feature of delay time in glow discharge, and it is easier for glow discharge to happen when switching the DC voltage of penning ion source into pulse. According to these two characteristics, the generator has been modified. This improved generator can be used in many other areas including Prompt Gamma Neutron Activation Analysis (PGNAA), neutron testing and experiment.

  8. Neutron depolarization studies on magnetization process using pulsed polarized neutrons

    International Nuclear Information System (INIS)

    Mitsuda, Setsuo; Endoh, Yasuo

    1985-01-01

    Neutron depolarization experiments investigating the magnetization processes have been performed by using pulsed polarized neutrons for the first time. Results on both quenched and annealed ferromagnets of Fe 85 Cr 15 alloy indicate the significant difference in the wavelength dependence of depolarization between them. It also constitutes the experimental demonstration of the theoretical prediction of Halpern and Holstein. (author)

  9. Pulsed thermal neutron source at the fast neutron generator.

    Science.gov (United States)

    Tracz, Grzegorz; Drozdowicz, Krzysztof; Gabańska, Barbara; Krynicka, Ewa

    2009-06-01

    A small pulsed thermal neutron source has been designed based on results of the MCNP simulations of the thermalization of 14 MeV neutrons in a cluster-moderator which consists of small moderating cells decoupled by an absorber. Optimum dimensions of the single cell and of the whole cluster have been selected, considering the thermal neutron intensity and the short decay time of the thermal neutron flux. The source has been built and the test experiments have been performed. To ensure the response is not due to the choice of target for the experiments, calculations have been done to demonstrate the response is valid regardless of the thermalization properties of the target.

  10. Calculation of the pulsed Feynman- and Rossi-alpha formulae with delayed neutrons

    International Nuclear Information System (INIS)

    Kitamura, Y.; Pazsit, I.; Wright, J.; Yamamoto, A.; Yamane, Y.

    2005-01-01

    In previous works, the authors have developed an effective solution technique for calculating the pulsed Feynman- and Rossi-alpha formulae. Through derivation of these formulae, it was shown that the technique can easily handle various pulse shapes of the pulsed neutron source. Furthermore, it was also shown that both the deterministic (i.e., synchronizing with the pulsing of neutron source) and stochastic (non-synchronizing) Feynman-alpha formulae can be obtained with this solution technique. However, for mathematical simplicity and the sake of insight, the formal derivation was performed in a model without delayed neutrons. In this paper, to demonstrate the robustness of the technique, the pulsed Feynman- and Rossi-alpha formulae were re-derived by taking one group of delayed neutrons into account. The results show that the advantages of this technique are retained even by inclusion of the delayed neutrons. Compact explicit formulae are derived for the Feynman- and Rossi-alpha methods for various pulse shapes and pulsing methods

  11. High power pulsed neutron source for electronuclear installation

    Energy Technology Data Exchange (ETDEWEB)

    Korenev, S.A.; Puzynin, I.V.; Samoilov, V.N.; Sissakian, A.N. [Joint Inst. for Nuclear Research, Dubna (Russian Federation)

    1997-09-01

    The pulsed neutron source based on the reaction T(d,n)He is described in this report. The source consists of pulsed a pulsed Arkad`ev-Marx generator and a vacuum diode with explosive ion emission. 9 refs., 3 figs.

  12. Fast neutron activating detectors for pulsed flow measurements

    International Nuclear Information System (INIS)

    Dyatlov, V.D.; Kunaev, G.T.; Popytaev, A.N.; Cheremukhov, B.V.

    1979-01-01

    The requirements to the activation detectors of the pulsed flows of the fast neutrons are considered; the criteria of optimum measurement time, geometrical moderator sizes and radioactive detector element properties have been obtained. On their analysis parameter selection has been carried out. The neutron detector to register the short pulses has been designed and calibrated. The ways of further increase of sensitivity and efficiency of such detectors are discussed

  13. Superintensive pulse slow neutron source SIN based on kaon factory

    International Nuclear Information System (INIS)

    Kolmichkov, N.V.; Laptev, V.D.; Matveev, V.A.

    1991-01-01

    Possibility of intensive pulse slow neutron source creation based on 45-GeV proton synchrotron of K-meson factory, planned to construction in INR AS USSR is considered. Calculated peak thermal neutrons flux density value, averaged on 'radiating' light-water moderator surface of 100 cm 2 is 6.6 x 10 17 neutrons/(cm 2 sec) for pulse duration of 35 microseconds. (author)

  14. Response transforms from comparative study of commercial pulsed-neutron-capture logging systems

    International Nuclear Information System (INIS)

    Salaita, G.N.

    1992-01-01

    This paper reports that three generations of Schlumberger's Thermal Decay Time (TDT SM ) logging devices - viz., TDT-K, TDT-M, and TDT-P - along with an Atlas Wireline PDK-100 SM system were run in a Saudi Aramco well. The wellbore (8 1/2 in. with 7-in. casing) penetrated a sequence of clean sand, shaly sand, and shale streaks as exhibited by the openhole natural gamma ray log. The initial wellbore fluid was diesel. The fluid was then changed to brines of 42,000 and 176,000 ppm NaCl, respectively. Three repeat passes at a logging speed of 900 ft/hr were obtained by each device for each borehole liquid. As a result of this extensive comparative study, a set of departure curves and mathematical transforms was developed primarily for standardizing the various Schlumberger tools to a common reference logging system and/or borehole environment. The transforms were used beneficially to determine residual oil saturation (ROS) from time-lapse logs in a Saudi Aramco reservoir

  15. A new type of compensated neutron logging probe

    International Nuclear Information System (INIS)

    Ji Changsong; Shang Xiulan; Dai Zhude; Huang Heyi; Zhang Jianguo; Zu Shihuan; Zhao Jianqiang

    1988-01-01

    A new type of compensated neutron logging probe with glass scintillators has been designed. High sensitivity, long plateau and stability are the features of this probe which differs from the probes with 3 He or LiI(Eu) detector. From the results of field application the measured porosity is in good correspondence with the one obtained by rock core sampling method

  16. Characteristics of the WNR: a pulsed spallation neutron source

    International Nuclear Information System (INIS)

    Russell, G.J.; Lisowski, P.W.; Howe, S.D.; King, N.S.P.; Meier, M.M.

    1982-01-01

    The Weapons Neutron Research facility (WNR) is a pulsed spallation neutron source in operation at the Los Alamos National Laboratory. The WNR uses part of the 800-MeV proton beam from the Clinton P. Anderson Meson Physics Facility accelerator. By choosing different target and moderator configurations and varying the proton pulse structure, the WNR can provide a white neutron source spanning the energy range from a few MeV to 800 MeV. The neutron spectrum from a bare target has been measured and is compared with predictions using an Intranuclear Cascade model coupled to a Monte Carlo transport code. Calculations and measurements of the neutronics of WNR target-moderator assemblies are presented

  17. Earth formation porosity log using measurement of neutron energy spectrum

    International Nuclear Information System (INIS)

    1981-01-01

    Methods and apparatus are described for measuring the porosity of subsurface earth formations in the vicinity of a well borehole by means of neutron well logging techniques. All the commercial techniques for measuring porosity currently available are not as accurate as desirable due to variations in the borehole wall diameter, in the borehole fluids (e.g. with chlorine content) in the casings of the borehole etc. This invention seeks to improve accuracy by using a measurement of the epithermal neutron population at one detector and the fast neutron population at a second detector, spaced approximately the same distance from a neutron source. The latter can be detected either by a fast neutron detector or indirectly by an inelastic gamma ray detector. Background correction can be made, and special detectors used, to discriminate against the detection of thermal neutrons or their resultant capture gamma rays. These fluctuations affect the measurement of thermal neutron populations. (U.K.)

  18. Method and apparatus for formation logging using position sensitive neutron detectors

    International Nuclear Information System (INIS)

    Gadken, L.L.

    1986-01-01

    This patent describes a method for logging earth formations using position sensitive neutron detectors. The method consists of: 1) Irradiation of earth formations in the vicinity of a well borehole with a source of fast neutrons. 2) At four longitudinally spaced distances from the neutron source in the borehole, the epithermal neutron population is detected. Each of the four separate populations is detected in an epithermally sensitive and substantially thermally insensitive portion of the same position sensitive neutron detector. A representative signal from each is then individually generated. 3) First, second, third, and fourth neutron population representative signals are combined. They derive a simultaneous measurement signal. This signal is functionally related to the porosity and also a signal functionally related to a neutron characteristic length of the earth formations in the vicinity of the borehole

  19. Pulsed neutron source and instruments at neutron facility

    Energy Technology Data Exchange (ETDEWEB)

    Teshigawara, Makoto; Aizawa, Kazuya; Suzuki, Jun-ichi; Morii, Yukio; Watanabe, Noboru [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-11-01

    We report the results of design studies on the optimal target shape, target - moderator coupling, optimal layout of moderators, and neutron instruments for a next generation pulsed spallation source in JAERI. The source utilizes a projected high-intensity proton accelerator (linac: 1.5 GeV, {approx}8 MW in total beam power, compressor ring: {approx}5 MW). We discuss the target neutronics, moderators and their layout. The sources is designed to have at least 30 beam lines equipped with more than 40 instruments, which are selected tentatively to the present knowledge. (author)

  20. A pulsed neutron Ramsey's method

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, Y. [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba-shi, Ibaraki 305-0801 (Japan)]. E-mail: yasuhiro.masuda@kek.jp; Ino, T. [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba-shi, Ibaraki 305-0801 (Japan); Jeong, S.C. [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba-shi, Ibaraki 305-0801 (Japan); Muto, S. [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba-shi, Ibaraki 305-0801 (Japan); Skoy, V. [Joint Institute for Nuclear Reasearch, 141980 Dubna (Russian Federation); Watanabe, Y. [High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba-shi, Ibaraki 305-0801 (Japan)

    2005-02-15

    A Ramsey's method with pulsed neutrons is proposed. A Ramsey signal, which is a neutron spin rotation about a static magnetic field for a time interval between two separated oscillatory fields, is observed as a function of a neutron time of flight (TOF) in this method. The neutron spin rotation or the RF oscillation is used as a clock of the neutron velocity measurement which ranges from cold to epithermal neutron energies. This method together with the TOF measurement can be used for neutron inelastic scattering experiments. In addition, this method can be applied to the measurement of magnetic and pseudomagnetic fields in matter, and also to neutron spin manipulation for spin dependent scattering.

  1. Simultaneous thermal neutron decay time and porosity logging system

    International Nuclear Information System (INIS)

    Shultz, W.E.

    1980-01-01

    A method for simultaneously determining the porosity and thermal neutron capture cross-section of earth formations in the vicinity of a well borehole is claimed. It comprises the following steps: passing a well tool into a cased well borehole. The tool has a pulsed source of fast neutrons, a combination fast neutron and gamma ray detector and an epithermal neutron detector; repetitively irradiating the earth formations in the vicinity of the borehole with bursts of fast neutrons; detecting the fast neutron and epithermal neutron populations in the borehole (during the neutron bursts) and generating first and second measurement signals; detecting for second and third time intervals during the time between the neutron bursts, the gamma radiation present in the borehole due to the capture of thermalized neutrons by the nuclei of elements comprising the earth formations and generating third and fourth measurement signals; and combining the first and second measurement signals according to a predetermined relationship to derive an indication of the porosity of the earth formations and combining the third and fourth measurement signals to derive an indication of the thermal neutron capture cross-section of the earth formations

  2. Proposal for the design of a small-angle neutron scattering facility at a pulsed neutron source

    International Nuclear Information System (INIS)

    Kley, W.

    1980-01-01

    The intensity-resolution-background considerations of an optimized small angle neutron scattering facility are reviewed for the special case of a pulsed neutron source. In the present proposal we conclude that for 'true elastic scattering experiments' filters can be used instead of expensive neutron guide tubes since low background conditions can be achieved by a combined action of filters as well as a proper time gating of the twodimensional detector. The impinging neutron beam is monochromatized by phasing a disk chopper to the neutron source pulses and in the scattered beam a second disk chopper is used to eliminate the inelastically scattered neutrons. Therefore, no time of fligh analysis is necessary for the scattered neutron intensity and true-elastic conditions are obtained by simply gating the two-dimensional detector. Considering a 4 m thick shield for the pulsed neutron source and choosing for optimum conditions a detector area element of (2.5 cm) 2 and a sample area of (1.25 cm) 2 , than for a minimum sample-detector-distance of 1.5 m, a maximum neutron source diameter of 6.67 cm is required in order to maintain always the optimum intensity- and resolution requirements

  3. Neutron production enhancements for the Intense Pulsed Neutron Source.

    Energy Technology Data Exchange (ETDEWEB)

    Iverson, E. B.

    1999-01-04

    The Intense Pulsed Neutron Source (IPNS) was the first high energy spallation neutron source in the US dedicated to materials research. It has operated for sixteen years, and in that time has had a very prolific record concerning the development of new target and moderator systems for pulsed spallation sources. IPNS supports a very productive user program on its thirteen instruments, which are oversubscribed by more than two times, meanwhile having an excellent overall reliability of 95%. Although the proton beam power is relatively low at 7 kW, the target and moderator systems are very efficient. The typical beam power which gives an equivalent flux for long-wavelength neutrons is about 60 kW, due to the use of a uranium target and liquid and solid methane moderators, precluded at some sources due to a higher accelerator power. The development of new target and moderator systems is by no means stagnant at IPNS. They are presently considering numerous enhancements to the target and moderators that offer prospects for increasing the useful neutron production by substantial factors. Many of these enhancements could be combined, although their combined benefit has not yet been well established. Meanwhile, IPNS is embarking on a coherent program of study concerning these improvements and their possible combination and implementation. Moreover, any improvements accomplished at IPNS would immediately increase the performance of IPNS instruments.

  4. Neutron production enhancements for the Intense Pulsed Neutron Source

    International Nuclear Information System (INIS)

    Iverson, E. B.

    1999-01-01

    The Intense Pulsed Neutron Source (IPNS) was the first high energy spallation neutron source in the US dedicated to materials research. It has operated for sixteen years, and in that time has had a very prolific record concerning the development of new target and moderator systems for pulsed spallation sources. IPNS supports a very productive user program on its thirteen instruments, which are oversubscribed by more than two times, meanwhile having an excellent overall reliability of 95%. Although the proton beam power is relatively low at 7 kW, the target and moderator systems are very efficient. The typical beam power which gives an equivalent flux for long-wavelength neutrons is about 60 kW, due to the use of a uranium target and liquid and solid methane moderators, precluded at some sources due to a higher accelerator power. The development of new target and moderator systems is by no means stagnant at IPNS. They are presently considering numerous enhancements to the target and moderators that offer prospects for increasing the useful neutron production by substantial factors. Many of these enhancements could be combined, although their combined benefit has not yet been well established. Meanwhile, IPNS is embarking on a coherent program of study concerning these improvements and their possible combination and implementation. Moreover, any improvements accomplished at IPNS would immediately increase the performance of IPNS instruments

  5. Pulsed neutron source based on accelerator-subcritical-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Makoto; Noda, Akira; Iwashita, Yoshihisa; Okamoto, Hiromi; Shirai, Toshiyuki [Kyoto Univ., Uji (Japan). Inst. for Chemical Research

    1997-03-01

    A new pulsed neutron source which consists of a 300MeV proton linac and a nuclear fuel subcritical assembly is proposed. The proton linac produces pulsed spallation neutrons, which are multipied by the subcritical assembly. A prototype proton linac that accelerates protons up to 7MeV has been developed and a high energy section of a DAW structure is studied with a power model. Halo formations in high intensity beam are also being studied. (author)

  6. Monte Carlo Study on Gas Pressure Response of He-3 Tube in Neutron Porosity Logging

    Directory of Open Access Journals (Sweden)

    TIAN Li-li;ZHANG Feng;WANG Xin-guang;LIU Jun-tao

    2016-10-01

    Full Text Available Thermal neutrons are detected by (n,p reaction of Helium-3 tube in the compensated neutron logging. The helium gas pressure in the counting area influences neutron detection efficiency greatly, and then it is an important parameter for neutron porosity measurement accuracy. The variation law of counting rates of a near detector and a far one with helium gas pressure under different formation condition was simulated by Monte Carlo method. The results showed that with the increasing of helium pressure the counting rate of these detectors increased firstly and then leveled off. In addition, the neutron counting rate ratio and porosity sensitivity increased slightly, the porosity measurement error decreased exponentially, which improved the measurement accuracy. These research results can provide technical support for selecting the type of Helium-3 detector in developing neutron porosity logging.

  7. International seminar on structural investigations on pulsed neutron sources. Proceedings

    International Nuclear Information System (INIS)

    Aksenov, V.L.; Balagurov, A.M.; Taran, Yu.V.

    1993-01-01

    The proceedings of the International seminar on structural investigations using pulsed neutron sources are presented. The seminar is dedicated to the memory of Dr. Yu.M. Ostanevich, a world acknowledged physicist. The problems of structural analysis using pulsed neutron source at the IBR-2 reactor are discussed

  8. Neutron generator ion source pulser

    International Nuclear Information System (INIS)

    Peelman, H.E.

    1987-01-01

    This patent describes, for use with a pulsed neutron generator in a logging tool lowered in a borehole, a pulsed high voltage source having an output terminal adapted to be connected to pulse neutron generator. The power supply comprises: (a) high voltage supply means; (b) field effect transistor means comprising at least a pair of field effect transistors serially connected between the high voltage supply means and ground; (c) an output terminal between the two transistors of the field effect transistor means, the output terminal adapted to be connected by a conductor to provide pulsed high voltage to a neutron generator; (d) control pulse forming means connected to the gates of the respective two transistors, the pulse forming means forming control pulses selectively switching the transistors off and on in timed sequence to thereby connect the output terminal to the high voltage supply means, and (e) diode means connected to the gates of the transistors to limit gate voltage for operation of the transistors

  9. A large angle cold neutron bender using sequential garland reflections for pulsed neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Ebisawa, T.; Tasaki, S. [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst; Soyama, K.; Suzuki, J. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-03-01

    We discuss a basic structure and performance of a new cold neutron bender using sequential garland reflections, in order to bend a neutron beam with large divergence by large angle. Using this bender for a pulsed neutron source we could not only avoid the frame overlap for cold neutrons but also install a plural spectrometers at a cold guide and obtain polarized neutron beams if necessary. (author)

  10. A large angle cold neutron bender using sequential garland reflections for pulsed neutron source

    International Nuclear Information System (INIS)

    Ebisawa, T.; Tasaki, S.; Soyama, K.; Suzuki, J.

    2001-01-01

    We discuss a basic structure and performance of a new cold neutron bender using sequential garland reflections, in order to bend a neutron beam with large divergence by large angle. Using this bender for a pulsed neutron source we could not only avoid the frame overlap for cold neutrons but also install a plural spectrometers at a cold guide and obtain polarized neutron beams if necessary. (author)

  11. Neutron resonance transmission spectroscopy with high spatial and energy resolution at the J-PARC pulsed neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Tremsin, A.S., E-mail: ast@ssl.berkeley.edu [University of California at Berkeley, 7 Gauss Way, Berkeley, CA 94720 (United States); Shinohara, T.; Kai, T.; Ooi, M. [Japan Atomic Energy Agency, 2–4 Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Kamiyama, T.; Kiyanagi, Y.; Shiota, Y. [Hokkaido University, Kita 13 Nishi 8 Kita-ku, Sapporo-shi, Hokkaido 060-8628 (Japan); McPhate, J.B.; Vallerga, J.V.; Siegmund, O.H.W. [University of California at Berkeley, 7 Gauss Way, Berkeley, CA 94720 (United States); Feller, W.B. [NOVA Scientific, Inc., 10 Picker Rd., Sturbridge, MA 01566 (United States)

    2014-05-11

    The sharp variation of neutron attenuation at certain energies specific to particular nuclides (the lower range being from ∼1 eV up to ∼1 keV), can be exploited for the remote mapping of element and/or isotope distributions, as well as temperature probing, within relatively thick samples. Intense pulsed neutron beam-lines at spallation sources combined with a high spatial, high-timing resolution neutron counting detector, provide a unique opportunity to measure neutron transmission spectra through the time-of-flight technique. We present the results of experiments where spatially resolved neutron resonances were measured, at energies up to 50 keV. These experiments were performed with the intense flux low background NOBORU neutron beamline at the J-PARC neutron source and the high timing resolution (∼20 ns at epithermal neutron energies) and spatial resolution (∼55 µm) neutron counting detector using microchannel plates coupled to a Timepix electronic readout. Simultaneous element-specific imaging was carried out for several materials, at a spatial resolution of ∼150 µm. The high timing resolution of our detector combined with the low background beamline, also enabled characterization of the neutron pulse itself – specifically its pulse width, which varies with neutron energy. The results of our measurements are in good agreement with the predicted results for the double pulse structure of the J-PARC facility, which provides two 100 ns-wide proton pulses separated by 600 ns, broadened by the neutron energy moderation process. Thermal neutron radiography can be conducted simultaneously with resonance transmission spectroscopy, and can reveal the internal structure of the samples. The transmission spectra measured in our experiments demonstrate the feasibility of mapping elemental distributions using this non-destructive technique, for those elements (and in certain cases, specific isotopes), which have resonance energies below a few keV, and with lower

  12. Experiment for water-flow measurement by pulsed-neutron activation

    International Nuclear Information System (INIS)

    Drozdowicz, K.

    1994-08-01

    An experiment is presented which constitutes a feasibility study for applying the neutron activation method for measurement of the water mass transport in pipings, e.g. in nuclear power stations. The fast neutron generator has been used as a pulsed-neutron activation source for oxygen in water which circulated in a closed system. The γ radiation of the nitrogen product isotope has been measured by the scintillation detectors placed in two positions at the piping. The two time distributions of the pulses have been recorded by a multiscaler (a software design based on CAMAC). The water flow velocity has been estimated from the peak-to-peak time distance. The tests have been performed under different experimental conditions (the neutron pulse duration, the time channel width, the water flow velocity) to define the stability, reproducibility and reliability of the measurement. The detailed results are presented in tables and in time distribution plots. The method has been found useful for the application considered. 4 refs, 17 figs, 5 tabs

  13. Los Alamos pulsed spallation neutron source target systems - present and future

    International Nuclear Information System (INIS)

    Russell, G.J.; Daemen, L.L.; Pitcher, E.J.; Brun, T.O.; Hjelm, R.P. Jr.

    1993-01-01

    For the past 16 yr, spallation target-system designers have devoted much time and effort to the design and optimization of pulsed spallation neutron sources. Many concepts have been proposed, but, in practice, only one has been implemented horizontal beam insertion with moderators in wing geometry i.e., until we introduced the innovative split-target/flux-trap-moderator design with a composite reflector shield at the Manuel Lujan, Jr., Neutron Scattering Center (LANSCE). The LANSCE target system design is now considered a classic by spallation target system designers worldwide. LANSCE, a state-of-the-art pulsed spallation neutron source for materials science and nuclear physics research, uses 800-MeV protons from the Clinton P. Anderson Meson Physics Facility. These protons are fed into the proton storage ring to be compressed to 250-ns pulses before being delivered to LANSCE at 20 Hz. LANSCE produces the highest peak neutron flux of any pulsed spallation neutron source in the world

  14. Neutron activation for logging the distribution of gold in bore-hole cores

    International Nuclear Information System (INIS)

    Rahmanian, H.; Watterson, J.I.W.

    1992-01-01

    A new method for the non-destructive determination of gold in bore-hole cores has been developed using instrumental neutron activation analysis with a 252 Cf source. The procedure obtains the distribution and concentration of gold along the longitudinal axis of the core i.e. a log of the gold concentration. The accuracy of the method is comparable to fire assay at a level of 2 ppm and has a detection limit of 1 ppm under the conditions used. The assay of the gold is carried out by employing a novel variation of the conventional comparator method using gold wires as both standard and flux monitor. A method is described for logging gold in bore-hole cores using neutron activation with a 160 μg 252 Cf neutron source. The method has a limit of detection of about 1 ppm under the described conditions. (author)

  15. Calibration of a detector for pulsed neutron sources

    International Nuclear Information System (INIS)

    Veeser, L.R.; Hemmendinger, A.; Shunk, E.R.

    1978-02-01

    A plastic scintillator detector for measuring the strength of a pulsed neutron source is described and the problems of calibration and discrimination against x-ray background for both pulsed and steady-state detectors are discussed

  16. Large subcriticality measurement by pulsed neutron method

    International Nuclear Information System (INIS)

    Yamane, Y.; Yoshida, A.; Nishina, K.; Kobayashi, K.; Kanda, K.

    1985-01-01

    To establish the method determining large subcriticalities in the field of nuclear criticality safety, the authors performed pulsed neutron experiments using the Kyoto University Critical Assembly (KUCA) at Research Reactor Institute, Kyoto University and the Cockcroft-Walton type accelerator attached to the assembly. The area-ratio method proposed by Sjoestrand was employed to evaluate subcriticalities from neutron decay curves measured. This method has the shortcomings that the neutron component due to a decay of delayed neutrons remarkably decreases as the subcriticality of an objective increases. To overcome the shortcoming, the authors increased the frequency of pulsed neutron generation. The integral-version of the area-ratio method proposed by Kosaly and Fisher was employed in addition in order to remove a contamination of spatial higher modes from the decay curve. The latter becomes significant as subcriticality increases. The largest subcriticality determined in the present experiments was 125.4 dollars, which was equal to 0.5111 in a multiplication factor. The calculational values evaluated by the computer code KENO-IV with 137 energy groups based on the Monte Carlo method agreed well with those experimental values

  17. A Long-Pulse Spallation Source at Los Alamos: Facility description and preliminary neutronic performance for cold neutrons

    International Nuclear Information System (INIS)

    Russell, G.J.; Weinacht, D.J.; Pitcher, E.J.; Ferguson, P.D.

    1998-03-01

    The Los Alamos National Laboratory has discussed installing a new 1-MW spallation neutron target station in an existing building at the end of its 800-MeV proton linear accelerator. Because the accelerator provides pulses of protons each about 1 msec in duration, the new source would be a Long Pulse Spallation Source (LPSS). The facility would employ vertical extraction of moderators and reflectors, and horizontal extraction of the spallation target. An LPSS uses coupled moderators rather than decoupled ones. There are potential gains of about a factor of 6 to 7 in the time-averaged neutron brightness for cold-neutron production from a coupled liquid H 2 moderator compared to a decoupled one. However, these gains come at the expense of putting ''tails'' on the neutron pulses. The particulars of the neutron pulses from a moderator (e.g., energy-dependent rise times, peak intensities, pulse widths, and decay constant(s) of the tails) are crucial parameters for designing instruments and estimating their performance at an LPSS. Tungsten is the reference target material. Inconel 718 is the reference target canister and proton beam window material, with Al-6061 being the choice for the liquid H 2 moderator canister and vacuum container. A 1-MW LPSS would have world-class neutronic performance. The authors describe the proposed Los Alamos LPSS facility, and show that, for cold neutrons, the calculated time-averaged neutronic performance of a liquid H 2 moderator at the 1-MW LPSS is equivalent to about 1/4th the calculated neutronic performance of the best liquid D 2 moderator at the Institute Laue-Langevin reactor. They show that the time-averaged moderator neutronic brightness increases as the size of the moderator gets smaller

  18. Proposal of a wide-band mirror polarizer of slow neutrons at a pulsed neutron source

    International Nuclear Information System (INIS)

    Nikitenko, Yu.V.; Ostanevich, Yu.M.

    1992-01-01

    The new type wide-band mirror-based neutron polarizer to be operated at a pulsed neutron source is suggested. The idea is to use a movable polarizing mirror system, which, be the incoming beam monochromatized by the time-of-flight, would allow one to tune glancing angles in time so, that the total reflection condition is always fulfilled only for one of the two neutron spin eigenstates. Estimates show, that with the pulsed reactor IBR-2 such polarizer allows one to build a small-angle neutron scattering instrument capable to effectively use the wave-length band from 2 to 15 A. 9 refs.; 1 fig

  19. The many facets of pulsed neutron cased-hole logging

    Energy Technology Data Exchange (ETDEWEB)

    Albertin, I.; Darling, H.; Mahdavi, M.; Plasek, R. [Schlumberger Houston Product Center, Sugarland, TX (United States); Cedeno, I. [City Investing Company Ltd., Quito (Ecuador); Hemingway, J.; Richter, P. [GeoQuest, Bakersfield, CA (United States); Markley, M. [Schlumberger, Bogota (Colombia); Olesen, J.R. [Schlumberger, Beijing (China); Roscoe, B. [Schlumberger-Doll Research, Ridgefield, CT (United States); Zeng, Wenchong [Shengli Petroleum Administration Bureau, China Petroleum Corporation, Beijing (China)

    1996-12-31

    The RST Reservoir Saturation Tool, which bombards formations with neutrons and detects gamma rays from the resulting interactions, is rapidly becoming a complete stand-alone, cased-hole evaluation service. Measurements like elemental analysis, thermal decay times, porosity evaluation and production analysis help reservoir engineers locate bypassed oil, detect waterflood fronts, fine-tune formation evaluations and monitor production profiles. 19 figs., 12 refs.

  20. Utilization of a pulsed D-T neutron generator

    International Nuclear Information System (INIS)

    Vilaithong, T.; Singkarat, S.; Tippawan, U.

    2000-01-01

    In the past two decades the IAEA has supported the establishment of neutron laboratories in many developing countries by providing small D-T neutron generators. The neutron generator is basically a low energy (100-400 keV) ion accelerator capable of producing a continuous beam of deuterons with a current in the range between 1-2.5 mA. These neutron generators are primarily intended to be used for fast neutron activation analysis. This paper describes the utilization of a 14 MeV neutron generator in continuous and pulsed beam modes in applied neutron physics program at Chiang Mai University. (author)

  1. International Seminar on Advanced Pulsed Neutron Sources PANS-II. Invited talks

    International Nuclear Information System (INIS)

    Pepelyshev, Yu.N.

    1994-01-01

    A conceptual design of creating intense pulsed neutron sources based on high-current accelerators and pulsed reactors for neutron scattering experiments is considered. The progress in high-efficiency moderator developments is shown. Results of diffraction studied are presented

  2. A prototype detector using the neutron image intensifier and multi-anode type photomultiplier tube for pulsed neutron imaging

    International Nuclear Information System (INIS)

    Ishikawa, Hirotaku; Sato, Hirotaka; Hara, Kaoru Y.; Kamiyama, Takashi

    2016-01-01

    We developed a neutron two-dimensional (2-D) detector for pulsed neutron imaging as a prototype detector, which was composed of a neutron image intensifier and a multi-anode type photomultiplier tube. A neutron transmission spectrum of α-Fe plate was measured by the prototype detector, and compared with the one measured by a typical neutron 2-D detector. The spectrum was in reasonable agreement with the one measured by the typical detector in the neutron wavelength region above 0.15 nm. In addition, a neutron transmission image of a cadmium indicator was obtained by the prototype detector. The usefulness of the prototype detector for pulsed neutron imaging was demonstrated. (author)

  3. Procedure and apparatus for the examination of underground formations with a neutron generator

    International Nuclear Information System (INIS)

    Culver, R.B.

    1978-01-01

    A pulsed neutron generator in a well logging instrument, pulsed at a clock frequency of 20 KHz is described. Inelastic scatter gamma rays are detected during a first time interval coinciding with the neutron source being on and capture gamma rays are measured during a second interval subsequent to the end of each neutron burst. Only a single detected pulse, assuming detection occurs, is transmitted during each of the two detection intervals. Sync pulses are generated in the well logging instrument scaled down to a frequency of 200 Hz for transmission to the earth's surface. At the earth's surface, the scaled-down sync pulses are applied to a phase locked loop system for regenerating the sync pulses to the same frequency as that of the clock frequency used to pulse the neutron source and to open the detection gates in the borehole instrument. The regenerated sync pulses are used in the surface instrumentation to route the pulses occurring in the inelastic interval into one section of a multichannel analyzer memory and the pulses occurring in the capture interval into another section of the multichannel analyzer. The use of memory address decoders, subtractors and ratio circuits enables both a carbon/oxygen ratio and a silicon/calcium ratio to be struck substantially free of background radiation. (Auth.)

  4. Internal strain measurement using pulsed neutron diffraction at LANSCE

    International Nuclear Information System (INIS)

    Goldstone, J.A.; Bourke, M.A.M.; Shi, N.

    1994-01-01

    The presence of residual stress in engineering components can effect their mechanical properties and structural integrity. Neutron diffraction in the only technique that can make nondestructive measurements in the interior of components. By recording the change in crystalline lattice spacings, elastic strains can be measured for individual lattice reflections. Using a pulsed neutron source, all lattice reflections are recorded in each measurement, which allows for easy examination of heterogeneous materials such as metal matrix composites. Measurements made at the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) demonstrate the potential at pulsed sources for in-situ stress measurements at ambient and elevated temperatures

  5. Cadmium-Zinc-Telluride photon detector for epithermal neutron spectroscopy--pulse height response characterisation

    International Nuclear Information System (INIS)

    Tardocchi, M.; Pietropaolo, A.; Andreani, C.; Bracco, A.; D'Angelo, A.; Gorini, G.; Imberti, S.; Senesi, R.; Rhodes, N.J.; Schooneveld, E.M.

    2004-01-01

    The Resonance Detector Spectrometer was recently revised for neutron spectroscopic studies in the eV energy region. In this technique one makes use of a photon detector to record the gamma emission from analyser foils used as neutron-gamma converters. The pulse-height response of a Cadmium-Zinc-Telluride photon detector to neutron capture emission from 238 U and 197 Au analyser foils was characterised in the neutron energy range 1-200 eV. The experiment was performed on the VESUVIO spectrometer at the ISIS neutron-pulsed source. A biparametric data acquisition, specifically developed for these measurements, allowed the simultaneous measurements of both the neutron time of flight and γ pulse-height spectra. Through the analysis of the γ pulse-height spectra the main components of the signal associated with resonant and non-resonant neutron absorption were identified. It was also shown that, in principle, energy discrimination can be used to improve the signal to background ratio of the neutron time-of-flight measurement

  6. Symposium on CIAE 600 kV ns pulse neutron generator

    International Nuclear Information System (INIS)

    Shen Guanren

    2001-01-01

    CIAE 600 kV ns Pulse Neutron Generator was built by China National Nuclear Corporation, which is an important facility mainly used for experimental researches of nuclear reactions induced by 14 MeV neutrons, experimental measurements of energy spectra of secondary neutrons and charged particles and macro-checking experiments of evaluated neutron database and dosimetry researches of neutrons and γ rays. It is the first home made one, but the fourth similar facility in the world. Six articles are included in this symposium. The articles details the general structure, radio frequency ion source, high current beam ns pulsed system, etc. The main technical problems resolved during development are discussed. And attentions and experiences in the generator adjustments are introduced

  7. A method and device for reducing background in well logging devices using inelastic gamma rays

    International Nuclear Information System (INIS)

    Culver, R.B.

    1974-01-01

    The invention relates to a well logging device, of the type comprising a source of pulsed neutrons and means for detecting radioactivity. The device comprises means adapted to interrupt the neutron source emission in response to the detection of a single gamma radiation showing a pre-determined feature [fr

  8. Implementation of variance-reduction techniques for Monte Carlo nuclear logging calculations with neutron sources

    NARCIS (Netherlands)

    Maucec, M

    2005-01-01

    Monte Carlo simulations for nuclear logging applications are considered to be highly demanding transport problems. In this paper, the implementation of weight-window variance reduction schemes in a 'manual' fashion to improve the efficiency of calculations for a neutron logging tool is presented.

  9. Computer model for calculating gamma-ray pulse-height spectra for logging applications

    International Nuclear Information System (INIS)

    Evans, M.L.

    1981-01-01

    A generalized computer model has been devised to simulate the emission, transport, and detection of natural gamma radiation from various logging environments. The model yields high-resolution gamma-ray pulse-height spectra that can be used to correct both gross gamma and spectral gamma-ray logs. The technique can help provide corrections to airborne and surface radiometric survey logs for the effects of varying altitude, formation composition, and overburden. Applied to borehole logging, the model can yield estimates of the effects of varying borehole fluid and casing attenuations, as well as varying formation porosity and saturation

  10. A comparison of the moisture gauge and the neutron log in air-filled holes at NTS

    International Nuclear Information System (INIS)

    Hearst, J.R.; Carlson, R.C.

    1993-01-01

    Two methods are commonly used to measure water content of geologic materials by neutron diffusion. One is used mostly in agricultural, mining and civil engineering areas and is called a moisture gauge. The other is used principally in petroleum and mineral exploration, and is called a neutron log. Both are used at NTS, the moisture gauge principally in tunnels, the neutron log in vertical drilled holes. There is little communication between the two industrial groups, and the measurement instruments have evolved with very different operational characteristics, and one important physics difference, the source to detector spacing. The moisture gauge has a very short, 0-6 cm, spacing, with little internal shielding, and count increases with water. In contrast, the neutron log has a long spacing, 30-50 cm, substantial internal shielding, and exhibits decreasing count with increasing water. Because of its short spacing the moisture gauge gives better bed resolution than the neutron log. Because its count increases with water, the moisture gauge is more strongly affected by water in the borehole, especially in dry formations. In these conditions the neutron log is the method of choice. In air-filled holes, if source size or logging time is not a constraint, the relative sensitivity of the two tools to water is determined by the relative strengths of borehole effects as fluid, holesize, or tool-wall gap. If source size is a constraint for safety reasons, the short spacing provides higher countrates for a given detector efficiency and thus better relative precision in determining the true count. If source size is limited because of detector or electronics saturation, the short spacing will be better at high water content, while the long spacing will be better at low water content. In any case the short spacing may have an advantage because it can make better contact with the hole wall and it can be more easily corrected for gap

  11. Characterization of a high repetition-rate laser-driven short-pulsed neutron source

    Science.gov (United States)

    Hah, J.; Nees, J. A.; Hammig, M. D.; Krushelnick, K.; Thomas, A. G. R.

    2018-05-01

    We demonstrate a repetitive, high flux, short-pulsed laser-driven neutron source using a heavy-water jet target. We measure neutron generation at 1/2 kHz repetition rate using several-mJ pulse energies, yielding a time-averaged neutron flux of 2 × 105 neutrons s‑1 (into 4π steradians). Deuteron spectra are also measured in order to understand source characteristics. Analyses of time-of-flight neutron spectra indicate that two separate populations of neutrons, ‘prompt’ and ‘delayed’, are generated at different locations. Gamma-ray emission from neutron capture 1H(n,γ) is also measured to confirm the neutron flux.

  12. Utilizations of intense pulsed neutron source in radiochemistry and radiation chemistry

    International Nuclear Information System (INIS)

    Shiokawa, Takanobu; Yoshihara, Kenji; Kaji, Harumi; Kusaka, Yuzuru; Tabata, Yoneho.

    1975-01-01

    Intense pulsed neutron sources is expected to supply more useful and fundamental informations in radiochemistry and radiation chemistry. Short-lived intermediate species may be detected and the mechanisms of radiation induced reactions will be elucidated more precisely. Analytical application of pulsed neutrons is also very useful. (auth.)

  13. Report on the international workshop on cold moderators for pulsed neutron sources

    International Nuclear Information System (INIS)

    Carpenter, J. M.

    1999-01-01

    The International Workshop on Cold Moderators for Pulsed Neutron Sources resulted from the coincidence of two forces. Our sponsors in the Materials Sciences Branch of DOE's Office of Energy Research and the community of moderator and neutron facility developers both realized that it was time. The Neutron Sources Working Group of the Megascience Forum of the Organization for Economic Cooperation and Development offered to contribute its support by publishing the proceedings, which with DOE and Argonne sponsorship cemented the initiative. The purposes of the workshop were: to recall and improve the theoretical groundwork of time-dependent neutron thermalization; to pose and examine the needs for and benefits of cold moderators for neutron scattering and other applications of pulsed neutron sources; to summarize experience with pulsed source, cold moderators, their performance, effectiveness, successes, problems and solutions, and the needs for operational data; to compile and evaluate new ideas for cold moderator materials and geometries; to review methods of measuring and characterizing pulsed source cold moderator performance; to appraise methods of calculating needed source characteristics and to evaluate the needs and prospects for improvements; to assess the state of knowledge of data needed for calculating the neutronic and engineering performance of cold moderators; and to outline the needs for facilities for testing various aspects of pulsed source cold moderator performance

  14. Report on the international workshop on cold moderators for pulsed neutron sources.

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, J. M.

    1999-01-06

    The International Workshop on Cold Moderators for Pulsed Neutron Sources resulted from the coincidence of two forces. Our sponsors in the Materials Sciences Branch of DOE's Office of Energy Research and the community of moderator and neutron facility developers both realized that it was time. The Neutron Sources Working Group of the Megascience Forum of the Organization for Economic Cooperation and Development offered to contribute its support by publishing the proceedings, which with DOE and Argonne sponsorship cemented the initiative. The purposes of the workshop were: to recall and improve the theoretical groundwork of time-dependent neutron thermalization; to pose and examine the needs for and benefits of cold moderators for neutron scattering and other applications of pulsed neutron sources; to summarize experience with pulsed source, cold moderators, their performance, effectiveness, successes, problems and solutions, and the needs for operational data; to compile and evaluate new ideas for cold moderator materials and geometries; to review methods of measuring and characterizing pulsed source cold moderator performance; to appraise methods of calculating needed source characteristics and to evaluate the needs and prospects for improvements; to assess the state of knowledge of data needed for calculating the neutronic and engineering performance of cold moderators; and to outline the needs for facilities for testing various aspects of pulsed source cold moderator performance.

  15. Processing and analyses of the pulsed-neutron experimental data of the YALINA facility

    International Nuclear Information System (INIS)

    Cao, Y.; Gohar, Y.; Smith, D.; Talamo, A.; Zhong, Z.; Kiyavitskaya, H.; Bournos, V.; Fokov, Y.; Routkovskaya, C.; Sadovich, S.

    2010-01-01

    Full text: The YALINA subcritical assembly of the Joint Institute for Power and Nuclear Research (JIPNR)-Sosny, Belarus has been utilized to study the physics parameters of accelerator driven systems (ADS) with high intensity Deuterium-Tritium and Deuterium-Deuterium pulsed neutron sources. In particular, with the fast and thermal neutron zones of the YALINA-Booster subcritical assembly, the pulsed neutron experiments have been utilized to evaluate the pulsed neutron methods for determining the reactivity of the subcritical system. In this paper, the pulsed-neutron experiments performed in the YALINA-Booster 1141 configuration with 90% U 235 fuel and 1185 configuration with 36% and 21% U fuel are examined and analized. The Sjo:strand area-ratio method is utilized to determine the reactivities of the subcritical assembly configurations. The linear regression method is applied to obtain the prompt neutron decay constants from the pulsed-neutron experimental data. The reactivity values obtained from experimental data are shown to be dependent on the detector locations and also on the detector types. The large discrepancies between the reactivity values given by the detectors in the fast neutron zone was reduced by spatial correction methods, and the estimated reactivity after the spatial corrections are almost spatially independent.

  16. Proposal of a wide-band mirror polarizer of slow neutrons at a pulsed neutron source

    International Nuclear Information System (INIS)

    Nikitenko, Yu.V.; Ostanevich, Yu.M.

    1993-01-01

    The new type of wide-band mirror-based neutron polarizer, which is to be operated at a pulsed neutron source, is suggested. The idea is to use a movable polarizing mirror system, which, with the incoming beam monochromatized by the time-of-flight, would allow one to tune glancing angles in time so that the total reflection condition is always fulfilled only for one of the two neutron spin eigenstates. Estimates show that with the pulsed reactor IBR-2 such a polarizer allows one to build a small angle neutron scattering instrument capable of effectively using the wavelength band from 2 A with a rather high luminosity (time-averaged flux at sample position being up to 10 7 n/s/cm -2 ). (orig.)

  17. Method and equipment for fast transmission of a signal consisting of many data pulses by a normal well-logging cable

    International Nuclear Information System (INIS)

    Pitts, R.W. Jr.; Whatley, H.A. Jr.

    1975-01-01

    Well logging methods and equipment in general and a nuclear well logging process and apparatus in particular are presented. They increase the number of pulses which can be transmitted to the top of the well from a well logging instrument placed at the bottom, during a given time interval, by means of a processing giving two pulses for each pulse corresponding to a detection. The equipment is a double-spectrum well logging system, with near and far detectors [fr

  18. Cold moderators for pulsed neutron sources

    International Nuclear Information System (INIS)

    Carpenter, J.M.

    1990-01-01

    This paper reviews cold moderators in pulsed neutron sources and provides details of the performance of different cold moderator materials and configurations. Analytical forms are presented which describe wavelength spectra and emission time distributions. Several types of cooling arrangements used in pulsed source moderators are described. Choices of materials are surveyed. The author examines some of the radiation damage effects in cold moderators, including the phenomenon of ''burping'' in irradiated cold solid methane. 9 refs., 15 figs., 4 tabs

  19. Neutron powder diffraction at a pulsed neutron source: a study of resolution effects

    International Nuclear Information System (INIS)

    Faber, J. Jr.; Hitterman, R.L.

    1985-11-01

    The General Purpose Powder Diffractometer (GPPD), a high resolution (Δd/d = 0.002) time-of-flight instrument, exhibits a resolution function that is almost independent of d-spacing. Some of the special properties of time-of-flight scattering data obtained at a pulsed neutron source will be discussed. A method is described that transforms wavelength dependent data, obtained at a pulsed neutron source, so that standard structural least-squares analyses can be applied. Several criteria are given to show when these techniques are useful in time-of-flight data analysis. 14 refs., 6 figs., 1 tab

  20. Linearity improvement on wide-range log signal of neutron measurement system for HANARO

    International Nuclear Information System (INIS)

    Kim, Young-Ki; Tuetken, Jeffrey S.

    1998-01-01

    This paper discusses engineering activities for improving the linearity characteristics of the Log Power signal from the neutron measurement system for HANARO. This neutron measurement system uses a fission chamber based detector which covers 10.3 decade-wide range from 10 -8 % full power(FP) up to 200%FP, The Log Power signal is designed to control the reactor at low power levels where most of the reactor physics tests are carried out. Therefore, the linearity characteristics of the Log Power signal is the major factor for accurate reactor power control. During the commissioning of the neutron measurement system, it was found that the linearity characteristics of the Log Power signal, especially near 10 -2 %FP, were not accurate enough for controlling the reactor during physics testing. Analysis of the system linearity data directly measured with reactor operating determined that the system was not operating per the design characteristics established from previous installations. The linearity data, which were taken as the reactor was increased in power, were sent to manufacturer's engineering group and a follow-up measures based on the analysis were then fed back to the field. Through step by step trouble-shooting activities, which included minor circuit modifications and alignment procedure changes, the linearity characteristics have been successfully improved and now exceed minimum performance requirements. This paper discusses the trouble-shooting techniques applied, the changes in the linearity characteristics, special circumstances in the HANARO application and the final resolution. (author)

  1. NGI-9 pulsed neutron generator with a fluence to 1010 n/s

    International Nuclear Information System (INIS)

    Allakhverdov, A.Sh.; Ogarkin, V.I.; Silicheva, G.P.; Timofeev, Yu.I.

    1975-01-01

    A neutron pulse generator with 14 MeV energy used for the activation analysis, is described. Its functional diagram and the technical characteristics are presented. The studies of the generator that resulted in determination of the effect of the accelerating voltage amplitude, the delay in the ion source firing with respect to the pulse of the accelerating voltage, the amount of operating ion sources and the energy imparted to them on the neutron flux magnitude are conducted. It is confirmed by the studies that the neutron generator operating in the nominal regime makes it possible to obtain a neutron flux of 5x10 9 -10 10 neutr./s. The dependence of the neutron flux variation on the frequency of pulse sequence for various ion sources is shown

  2. Neutron activation system for spectral measurements of pulsed ion diode neutron production

    International Nuclear Information System (INIS)

    Hanson, D.L.; Kruse, L.W.

    1980-02-01

    A neutron energy spectrometer has been developed to study intense ion beam-target interactions in the harsh radiation environment of a relativistic electron beam source. The main component is a neutron threshold activation system employing two multiplexed high efficiency Ge(Li) detectors, an annihilation gamma coincidence system, and a pneumatic sample transport. Additional constraints on the neutron spectrum are provided by total neutron yield and time-of-flight measurements. A practical lower limit on the total neutron yield into 4π required for a spectral measurement with this system is approx. 10 10 n where the neutron yield is predominantly below 4 MeV and approx. 10 8 n when a significant fraction of the yield is above 4 MeV. Applications of this system to pulsed ion diode neutron production experiments on Hermes II are described

  3. Polarizing beam-splitter device at a pulsed neutron source

    International Nuclear Information System (INIS)

    Itoh, Shinichi; Takeda, Masayasu.

    1996-01-01

    A polarizing beam-splitter device was designed using Fe/Si supermirrors in order to obtain two polarized neutron beam lines, from one unpolarized neutron beam line, with a practical beam size for investigating the properties of condensed matter. This device was mounted after a guide tube at a pulsed neutron source, and its performance was investigated. (author)

  4. Application of the pulsed neutron technique on the reactors ALIZE - AQUILON (1963); Application de la methode des neutrons pulses sur les piles ALIZE et AQUILON (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Jacquemart, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    Different methods of measuring the ratio effective delayed fraction / prompt neutron lifetime, {alpha}{sub c}, are described. According to the classic pulsed neutron technique the negative reactivity due to a localized absorber is given by {rho} / {beta}{sub eff} = {alpha} / {alpha}{sub c} -1 Experiments are reported which show that in this case {alpha}{sub c} can not be considered constant for large reactivities. The absorber element distorts the flux in the system, increasing the importance of the reflector. An application of the pulsed neutron method to the measurement of critical distributed boron concentrations of various absorber elements is described. Less time is required than for the usual super-critical techniques, and the experimental analysis is simplified. It is interesting to note that the results are not influenced by the spectral sensitivity of the control element. A modified pulsed neutron method has been tried out. This procedure was used to determine by measurements at sub-critical the critical water level of uranium-heavy water lattices with a high precision. (author) [French] Differents modes operatoires pour definir la valeur du rapport pourcentage effectif de neutrons retardes / temps de vie, {alpha}{sub c}, sont exposes. La methode classique par neutrons pulses definit l'anti-reactivite d'un element absorbant a partir de la relation: {rho} / {beta}{sub eff} {alpha} / {alpha}{sub c} -1 Les manipulations effectuees montrent qu'on ne peut considerer dans ce cas {alpha}{sub c} constant pour de tres grandes anti-reactivites. L'absorbant introduit dans la pile deforme le flux et augmente l'importance du reflecteur. Une application de la methode des neutrons pulses pour mesurer le titre critique en mg de B/l de divers absorbants est signalee. Les operations sont effectuees en regime sous-critique avec un certain gain de temps et une grande facilite de depouillement. Il est interessant de noter que les resultats ne sont pas affectes par la

  5. Application of the pulsed neutron technique on the reactors ALIZE - AQUILON (1963); Application de la methode des neutrons pulses sur les piles ALIZE et AQUILON (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Jacquemart, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    Different methods of measuring the ratio effective delayed fraction / prompt neutron lifetime, {alpha}{sub c}, are described. According to the classic pulsed neutron technique the negative reactivity due to a localized absorber is given by {rho} / {beta}{sub eff} = {alpha} / {alpha}{sub c} -1 Experiments are reported which show that in this case {alpha}{sub c} can not be considered constant for large reactivities. The absorber element distorts the flux in the system, increasing the importance of the reflector. An application of the pulsed neutron method to the measurement of critical distributed boron concentrations of various absorber elements is described. Less time is required than for the usual super-critical techniques, and the experimental analysis is simplified. It is interesting to note that the results are not influenced by the spectral sensitivity of the control element. A modified pulsed neutron method has been tried out. This procedure was used to determine by measurements at sub-critical the critical water level of uranium-heavy water lattices with a high precision. (author) [French] Differents modes operatoires pour definir la valeur du rapport pourcentage effectif de neutrons retardes / temps de vie, {alpha}{sub c}, sont exposes. La methode classique par neutrons pulses definit l'anti-reactivite d'un element absorbant a partir de la relation: {rho} / {beta}{sub eff} {alpha} / {alpha}{sub c} -1 Les manipulations effectuees montrent qu'on ne peut considerer dans ce cas {alpha}{sub c} constant pour de tres grandes anti-reactivites. L'absorbant introduit dans la pile deforme le flux et augmente l'importance du reflecteur. Une application de la methode des neutrons pulses pour mesurer le titre critique en mg de B/l de divers absorbants est signalee. Les operations sont effectuees en regime sous-critique avec un certain gain de temps et une grande facilite de depouillement. Il est interessant de noter que les resultats ne sont pas

  6. Recent performance of the Intense Pulsed Neutron Source accelerator system

    International Nuclear Information System (INIS)

    Potts, C.; Brumwell, F.; Rauchas, A.; Stipp, V.; Volk, G.; Donley, L.

    1987-03-01

    The Intense Pulsed Neutron Source (IPNS) accelerator system has now been in operation as part of a national user program for over five years. During that period steady progress has been made in both beam intensity and reliability. Almost 1.8 billion pulses totaling 4 x 10 21 protons have now been delivered to the spallation neutron target. Recent weekly average currents have reached 15 μA (3.2 x 10 12 protons per pulse, 30 pulses per second) and short-term peaks of almost 17 μA have been reached. In fact, the average current for the last two years is up 31% over the average for the first three years of operation

  7. Neutron-gamma discrimination by pulse analysis with superheated drop detector

    International Nuclear Information System (INIS)

    Das, Mala; Seth, S.; Saha, S.; Bhattacharya, S.; Bhattacharjee, P.

    2010-01-01

    Superheated drop detector (SDD) consisting of drops of superheated liquid of halocarbon is irradiated to neutrons and gamma-rays from 252 Cf fission neutron source and 137 Cs gamma source, respectively, separately. Analysis of pulse height of signals at the neutron and gamma-ray sensitive temperature provides significant information on the identification of neutron and gamma-ray induced events.

  8. Neutron Spectroscopy for pulsed beams with frame overlap using a double time-of-flight technique

    Science.gov (United States)

    Harrig, K. P.; Goldblum, B. L.; Brown, J. A.; Bleuel, D. L.; Bernstein, L. A.; Bevins, J.; Harasty, M.; Laplace, T. A.; Matthews, E. F.

    2018-01-01

    A new double time-of-flight (dTOF) neutron spectroscopy technique has been developed for pulsed broad spectrum sources with a duty cycle that results in frame overlap, where fast neutrons from a given pulse overtake slower neutrons from previous pulses. Using a tunable beam at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory, neutrons were produced via thick-target breakup of 16 MeV deuterons on a beryllium target in the cyclotron vault. The breakup spectral shape was deduced from a dTOF measurement using an array of EJ-309 organic liquid scintillators. Simulation of the neutron detection efficiency of the scintillator array was performed using both GEANT4 and MCNP6. The efficiency-corrected spectral shape was normalized using a foil activation technique to obtain the energy-dependent flux of the neutron beam at zero degrees with respect to the incoming deuteron beam. The dTOF neutron spectrum was compared to spectra obtained using HEPROW and GRAVEL pulse height spectrum unfolding techniques. While the unfolding and dTOF results exhibit some discrepancies in shape, the integrated flux values agree within two standard deviations. This method obviates neutron time-of-flight spectroscopy challenges posed by pulsed beams with frame overlap and opens new opportunities for pulsed white neutron source facilities.

  9. Time-of-flight diffraction at pulsed neutron sources: An introduction to the symposium

    International Nuclear Information System (INIS)

    Jorgensen, J.D.

    1994-01-01

    In the 25 years since the first low-power demonstration experiments, pulsed neutron sources have become as productive as reactor sources for many types of diffraction experiments. The pulsed neutron sources presently operating in the United States, England, and Japan offer state of the art instruments for powder and single crystal diffraction, small angle scattering, and such specialized techniques as grazing-incidence neutron reflection, as well as quasielastic and inelastic scattering. In this symposium, speakers review the latest advances in diffraction instrumentation for pulsed neutron sources and give examples of some of the important science presently being done. In this introduction to the symposium, I briefly define the basic principles of pulsed neutron sources, review their development, comment in general terms on the development of time-of-flight diffraction instrumentation for these sources, and project how this field will develop in the next ten years

  10. The effect of pulse pile-up on discrimination between neutrons and gamma rays

    International Nuclear Information System (INIS)

    Whittlestone, S.

    1980-01-01

    Pulse pile-up lengthens the rise-time of pulses. With an organic scintillator such as NE 213, pile-up can cause a short rise-time pulse originating from gamma rays to be interpreted by a rise-time analyser as a neutron. The degradation of pulse shape analyser performance at high count rates is shown to be directly related to pulse pile-up. Using this relationship, the contribution of piled-up gamma rays and neutrons to count rate related errors is calculated for a time-dependent fast neutron energy spectrum measurement. Errors of a few per cent occur even when the probability of a count per burst is as low as 0.01. (orig.)

  11. Neutron generator tube ion source control apparatus

    International Nuclear Information System (INIS)

    Bridges, J.R.

    1982-01-01

    A pulsed neutron well logging system includes a neutron generator tube of the deuterium-tritium accelerator type and an ion source control apparatus providing extremely sharply time-defined neutron pulses. A low voltage control pulse supplied to an input by timing circuits turns a power FET on via a buffer-driver whereby a 2000 volt pulse is produced in the secondary of a pulse transformer and applied to the ion source of the tube. A rapid fall in this ion source control pulse is ensured by a quenching circuit wherein a one-shot responds to the falling edge of the control pulse and produces a 3 microsecond delay to compensate for the propagation delay. A second one-shot is triggered by the falling edge of the output of the first one-shot and gives an 8 microsecond pulse to turn on the power FET which, via an isolation transformer turns on a series-connected transistor to ground the secondary of the pulse transformer and the ion source. (author)

  12. Structural science using single crystal and pulse neutron scattering

    International Nuclear Information System (INIS)

    Noda, Yukio; Kimura, Hiroyuki; Watanabe, Masashi; Ishikawa, Yoshihisa; Tamura, Itaru; Arai, Masatoshi; Takahashi, Miwako; Ohshima, Ken-ichi; Abe, Hiroshi; Kamiyama, Takashi

    2008-01-01

    The application to single crystal neutron structural analysis is overviewed. Special attention is paid to the pulse neutron method, which will be available soon under J-PARC project in Japan. New proposal and preliminary experiment using Sirius at KENS are described. (author)

  13. LUPIN, a new instrument for pulsed neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Caresana, M. [Politecnico di Milano, Department of Energy, Via Ponzio 34/3, 20133 Milan (Italy); Ferrarini, M. [Politecnico di Milano, Department of Energy, Via Ponzio 34/3, 20133 Milan (Italy); CNAO, Via Privata Campeggi, 27100 Pavia (Italy); Manessi, G.P., E-mail: giacomo.paolo.manessi@cern.ch [CERN, 1211 Geneva 23 (Switzerland); University of Liverpool, Department of Physics, L69 7ZE Liverpool (United Kingdom); Silari, M. [CERN, 1211 Geneva 23 (Switzerland); Varoli, V. [Politecnico di Milano, Department of Energy, Via Ponzio 34/3, 20133 Milan (Italy)

    2013-06-01

    A number of studies focused in the last decades on the development of survey meters to be used in pulsed radiation fields. This is a topic attracting widespread interest for applications such as radiation protection and beam diagnostics in accelerators. This paper describes a new instrument specifically conceived for applications in pulsed neutron fields (PNF). The detector, called LUPIN, is a rem counter type instrument consisting of a {sup 3}He proportional counter placed inside a spherical moderator. It works in current mode with a front-end electronics consisting of a current–voltage logarithmic amplifier, whose output signal is acquired with an ADC and processed on a PC. This alternative signal processing allows the instrument to be used in PNF without being affected by saturation effects. Moreover, it has a measurement capability ranging over many orders of burst intensity. Despite the fact that it works in current mode, it can measure a single neutron interaction. The LUPIN was first calibrated in CERN's calibration laboratory with a PuBe source. Measurements were carried out under various experimental conditions at the Helmholtz-Zentrum in Berlin, in the stray field at various locations of the CERN Proton Synchrotron complex and around a radiotherapy linear accelerator at the S. Raffaele hospital in Milan. The detector can withstand single bursts with values of H⁎(10) up to 16 nSv/burst without showing any saturation effect. It efficiently works in pulsed stray fields, where a conventional rem-counter underestimates by a factor of 2. It is also able to reject the very intense and pulsed photon contribution that often accompanies the neutron field with good reliability. -- Highlights: ► LUPIN is a new detector specifically conceived to work in neutron pulsed fields. ► The detector is a rem counter type instrument working in current mode. ► The performances of the detectors were studied under various experimental conditions. ► The detector

  14. Polarisation modulated crosscorrelation spectroscopy on a pulsed neutron source

    International Nuclear Information System (INIS)

    Cywinski, R.; Williams, W.G.

    1984-07-01

    A crosscorrelation technique is introduced by which a total scattering polarisation analysis spectrometer on a pulsed neutron source can be modified to give full neutron polarisation and energy analysis without changing the physical configuration of the instrument. Its implementation on the proposed POLARIS spectrometer at the Rutherford Appleton Laboratory Spallation Neutron Source is described, and the expected dynamic (Q, ω) range and resolution evaluated. (author)

  15. Development and characterization of a high yield transportable pulsed neutron source with efficient and compact pulsed power system

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Rishi, E-mail: rishiv9@gmail.com, E-mail: rishiv@barc.gov.in; Mishra, Ekansh; Dhang, Prosenjit; Sagar, Karuna; Meena, Manraj; Shyam, Anurag [Energetics and Electromagnetics Division, Bhabha Atomic Research Centre Autonagar, Vishakapatnam 530012 (India)

    2016-09-15

    The results of characterization experiments carried out on a newly developed dense plasma focus device based intense pulsed neutron source with efficient and compact pulsed power system are reported. Its high current sealed pseudospark switch based low inductance capacitor bank with maximum stored energy of ∼10 kJ is segregated into four modules of ∼2.5 kJ each and it cumulatively delivers peak current in the range of 400 kA–600 kA (corresponding to charging voltage range of 14 kV–18 kV) in a quarter time period of ∼2 μs. The neutron yield performance of this device has been optimized by discretely varying deuterium filling gas pressure in the range of 6 mbar–11 mbar at ∼17 kV/550 kA discharge. At ∼7 kJ/8.5 mbar operation, the average neutron yield has been measured to be in the order of ∼4 × 10{sup 9} neutrons/pulse which is the highest ever reported neutron yield from a plasma focus device with the same stored energy. The average forward to radial anisotropy in neutron yield is found to be ∼2. The entire system is contained on a moveable trolley having dimensions 1.5 m × 1 m × 0.7 m and its operation and control (up to the distance of 25 m) are facilitated through optically isolated handheld remote console. The overall compactness of this system provides minimum proximity to small as well as large samples for irradiation. The major intended application objective of this high neutron yield dense plasma focus device development is to explore the feasibility of active neutron interrogation experiments by utilization of intense pulsed neutron sources.

  16. Simulation study of a pulsed neutron focusing using a pulsed electromagnetic lens coupled with a permanent magnet

    International Nuclear Information System (INIS)

    Iwashita, H.; Iwasa, H.; Hiraga, F.; Kamiyama, T.; Kiyanagi, Y.; Suzuki, J.; Shinohara, T.; Oku, T.; Shimizu, H.M.

    2009-01-01

    A pulsed sextupole electromagnetic lens with suitably controlled time-dependent magnetic field can in principle focus pulsed neutrons at the same focal point over a wide range of wavelength as the lens removes aberrations. However, in fact, it is difficult to focus neutrons over a wide range of wavelength because attenuation of a practical pulsed sextupole electromagnet is faster than an ideal case. We have devised a method of canceling the difference between the practical pulsed sextupole magnetic field and the ideal magnetic field with the use of a permanent sextupole magnet. We performed simulation calculations to investigate the feasibility of this method, and it was shown that focusing wavelength range spread compared with the case using a pulsed magnetic lens only. This result indicates the usefulness of the method.

  17. Condensed matter and materials research using neutron diffraction and spectroscopy: reactor and pulsed neutron sources

    International Nuclear Information System (INIS)

    Bisanti, Paola; Lovesey, S.W.

    1987-05-01

    The paper provides a short, and partial view of the neutron scattering technique applied to condensed matter and materials research. Reactor and accelerator-based neutron spectrometers are discussed, together with examples of research projects that illustrate the puissance and modern applications of neutron scattering. Some examples are chosen to show the range of facilities available at the medium flux reactor operated by Casaccia ENEA, Roma and the advanced, pulsed spallation neutron source at the Rutherford Appleton Laboratory, Oxfordshire. (author)

  18. Formation of very short pulse by neutron spin flip chopper for J-PARC

    International Nuclear Information System (INIS)

    Ebisawa, T.; Soyama, K.; Yamazaki, D.; Tasaki, S.; Sakai, K.; Oku, T.; Maruyama, R.; Hino, M.

    2004-01-01

    We have developed neutron spin flip choppers with high S/N ratio and high intensity for pulsed sources using multi-stage spin flip choppers. It is not easy for us to obtain a very short neutron pulse less than 10 μs using a spin flip chopper, due to the time constant L/R in the normal LR circuit. We will discuss a method obtaining a very short neutron pulse applying the modified push-pull circuit proposed by Ito and Takahashi [4] to the double spin flip chopper with polarizing guides

  19. A low background pulsed neutron polyenergetic beam

    International Nuclear Information System (INIS)

    Adib, M.; Abdelkawy, A.; Habib, N.; abuelela, M.; Wahba, M.; kilany, M.; Kalebebin, S.M.

    1992-01-01

    A low background pulsed neutron polyenergetic thermal beam at ET-R R-1 is produced by a rotor and rotating collimator suspended in magnetic fields. Each of them is mounted on its mobile platform and whose centres are 66 cm apart, rotating synchronously at speeds up to 16000 rpm. It was found that the neutron burst produced by the rotor with almost 100% transmission passes through the collimator, when the rotation phase between them is 28.8 degree Moreover the background level achieved at the detector position is low, constant and free from peaks due to gamma rays and fast neutrons accompanying the reactor thermal beam.3 fig

  20. Perspectives for online analysis of raw material by pulsed neutron irradiation

    Science.gov (United States)

    Bach, Pierre; Le Tourneur, P.; Poumarede, B.

    1997-02-01

    On-line analysis by pulsed neutron irradiation is an example of an advanced technology application of nuclear techniques, concerning real problems in the cement, mineral and coal industries. The most significant of these nuclear techniques is their capability of continuous measurement without contact and without sampling, which can lead to improved control of processes and resultant large financial savings. Compared to Californium neutron sources, the use of electrical pulsed neutron generators allows to obtain a higher signal/noise ratio for a more sensitive measurement, and allows to overcome a number of safety problems concerning transportation, installation and maintenance. An experiment related to a possible new on-line raw material analyzer is described, using a pulsed neutron generator. The key factors contributing to an accurate measurement are related to a suitable generator, to a high count rate gamma ray spectroscopy electronics, and to computational tools. Calculation and results for the optimization of the neutron irradiation time diagram are reported. One of the operational characteristics of such an equipment is related to neutron flux available: it is possible to adjust it to the requested accuracy, i.e. for a high accuracy during a few hours/day and for a lower accuracy the rest of the time. This feature allows to operate the neutron tube during a longer time, and then to reduce the cost of analysis.

  1. Residual stress measurement using the pulsed neutron source at LANSCE

    International Nuclear Information System (INIS)

    Bourke, M.A.M.; Goldstone, J.A.; Holden, T.M.

    1991-01-01

    The presence of residual stress in engineering components can effect their mechanical properties and structural integrity. Neutron diffraction is the only measuring technique which can make spatially resolved non-destructive strain measurements in the interior of components. By recording the change in the crystalline interplanar spacing, elastic strains can be measured for individual lattice reflections. Using a pulsed neutron source, all the lattice reflections are recorded in each measurement which allows anisotropic effects to be studied. Measurements made at the Manuel Lujan Jr Neutron Scattering Centre (LANSCE) demonstrate the potential for stress measurements on a pulsed source and indicate the advantages and disadvantages over measurements made on a reactor. 15 refs., 7 figs

  2. Combination of epithermal and inelastic neutron scattering methods to locate coal and oil-shale zones

    International Nuclear Information System (INIS)

    Schultz, W.E.

    1976-01-01

    A pulsed neutron generator of the deuterium-tritium reaction type irradiates earth formations in the vicinity of a borehole with 14 MeV neutrons. Gamma rays produced by the inelastic scattering of the fast neutrons are observed in four energy regions of the gamma ray energy spectrum corresponding to the inelastic scattering of neutrons by carbon, oxygen, silicon, and calcium. The carbon/oxygen, calcium/silicon, and carbon plus oxygen gamma rays are found and combined with a separately derived hydrogen index log to determine the quality of coal-bearing formations or oil-shale regions. The hydrogen index curve is found preferably by a dual-spaced detector epithermal neutron porosity logging technique or from a conventional thermal neutron gamma ray log

  3. Detection of fast burst of neutrons in the background of intense electromagnetic pulse

    International Nuclear Information System (INIS)

    Shyam, Anurag

    1999-01-01

    There are many experiments, in which fast neutron burst is emitted along with strong electromagnetic pulse. This pulse has frequency spectrum starting from few tens of khz to hard x-rays. Detecting these neutrons bursts require special measurement techniques, which are described. (author)

  4. Cased-hole log analysis and reservoir performance monitoring

    CERN Document Server

    Bateman, Richard M

    2015-01-01

    This book addresses vital issues, such as the evaluation of shale gas reservoirs and their production. Topics include the cased-hole logging environment, reservoir fluid properties; flow regimes; temperature, noise, cement bond, and pulsed neutron logging; and casing inspection. Production logging charts and tables are included in the appendices. The work serves as a comprehensive reference for production engineers with upstream E&P companies, well logging service company employees, university students, and petroleum industry training professionals. This book also: ·       Provides methods of conveying production logging tools along horizontal well segments as well as measurements of formation electrical resistivity through casing ·       Covers new information on fluid flow characteristics in inclined pipe and provides new and improved nuclear tool measurements in cased wells ·       Includes updates on cased-hole wireline formation testing  

  5. The performance of neutron scattering spectrometers at a long-pulse spallation source

    International Nuclear Information System (INIS)

    Pynn, R.

    1997-01-01

    In this document the author considers the performance of a long pulse spallation source for those neutron scattering experiments that are usually performed with a monochromatic beam at a continuous wave (CW) source such as a nuclear reactor. The first conclusion drawn is that comparison of the performance of neutron scattering spectrometers at CW and pulsed sources is simpler for long-pulsed sources than it is for the short-pulse variety. Even though detailed instrument design and assessment will require Monte Carlo simulations (which have already been performed at Los Alamos for SANS and reflectometry), simple arguments are sufficient to assess the approximate performance of spectrometers at an LPSS and to support the contention that a 1 MW long-pulse source can provide attractive performance, especially for instrumentation designed for soft-condensed-matter science. Because coupled moderators can be exploited at such a source, its time average cold flux is equivalent to that of a research reactor with a power of about 15 MW, so only a factor of 4 gain from source pulsing is necessary to obtain performance that is comparable with the ILL. In favorable cases, the gain from pulsing can be even more than this, approaching the limit set by the peak flux, giving about 4 times the performance of the ILL. Because of its low duty factor, an LPSS provides the greatest performance gains for relatively low resolution experiments with cold neutrons. It should thus be considered complementary to short pulse sources which are most effective for high resolution experiments using thermal or epithermal neutrons

  6. 40-Tesla pulsed-field cryomagnet for single crystal neutron diffraction

    Science.gov (United States)

    Duc, F.; Tonon, X.; Billette, J.; Rollet, B.; Knafo, W.; Bourdarot, F.; Béard, J.; Mantegazza, F.; Longuet, B.; Lorenzo, J. E.; Lelièvre-Berna, E.; Frings, P.; Regnault, L.-P.

    2018-05-01

    We present the first long-duration and high duty cycle 40-T pulsed-field cryomagnet addressed to single crystal neutron diffraction experiments at temperatures down to 2 K. The magnet produces a horizontal field in a bi-conical geometry, ±15° and ±30° upstream and downstream of the sample, respectively. Using a 1.15 MJ mobile generator, magnetic field pulses of 100 ms length are generated in the magnet, with a rise time of 23 ms and a repetition rate of 6-7 pulses per hour at 40 T. The setup was validated for neutron diffraction on the CEA-CRG three-axis spectrometer IN22 at the Institut Laue Langevin.

  7. The potential use of synthetic profiles of thermal neutrons decay time

    International Nuclear Information System (INIS)

    Tinoco, Franciso Lopes.

    1994-01-01

    The Time Lapse Technique used for monitoring the water and gas movement in a reservoir needs a PNC - Pulsed Neutron Capture Log - base log to be matched. However, few wells have this base log run in unchanged water saturation conditions. This paper presents two alternatives to be used a a base log: a synthetic PNC log and the initial gamma ray log. Some examples are presented to illustrate these techniques. (author). 1 ref., 6 figs., 2 tabs

  8. Data acquisition system for the neutron scattering instruments at the intense pulsed neutron source

    International Nuclear Information System (INIS)

    Crawford, R.K.; Daly, R.T.; Haumann, J.R.; Hitterman, R.L.; Morgan, C.B.; Ostrowski, G.E.; Worlton, T.G.

    1981-01-01

    The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory is a major new user-oriented facility which is now coming on line for basic research in neutron scattering and neutron radiation damage. This paper describes the data-acquisition system which will handle data acquisition and instrument control for the time-of-flight neutron-scattering instruments at IPNS. This discussion covers the scientific and operational requirements for this system, and the system architecture that was chosen to satisfy these requirements. It also provides an overview of the current system implementation including brief descriptions of the hardware and software which have been developed

  9. Random pulsing of neutron source for inelastic neutron scattering gamma ray spectroscopy

    International Nuclear Information System (INIS)

    Hertzog, R.C.

    1981-01-01

    Method and apparatus are described for use in the detection of inelastic neutron scattering gamma ray spectroscopy. Data acquisition efficiency is enhanced by operating a neutron generator such that a resulting output burst of fast neutrons is maintained for as long as practicably possible until a gamma ray is detected. Upon the detection of a gamma ray the generator burst output is terminated. Pulsing of the generator may be accomplished either by controlling the burst period relative to the burst interval to achieve a constant duty cycle for the operation of the generator or by maintaining the burst period constant and controlling the burst interval such that the resulting mean burst interval corresponds to a burst time interval which reduces contributions to the detected radiation of radiation occasioned by other than the fast neutrons

  10. Detection of fast neutrons in a plastic scintillator using digital pulse processing to reject gammas

    International Nuclear Information System (INIS)

    Reeder, P.L.; Peurrung, A.J.; Hansen, R.R.; Stromswold, D.C.; Hensley, W.K.; Hubbard, C.W.

    1999-01-01

    We report on neutron-gamma discrimination in a plastic scintillator based on the time delay inherent in second and third chance neutron scattering. Because of the time delay (∼3 ns) between the first and second scattering of a neutron, calculations of gammas and neutrons in a plastic scintillator predict that a neutron signal should be significantly broader than a pulse from a gamma event. Experimentally, we have used a fast digital oscilloscope coupled to a computer to examine individual pulses from neutron or gamma induced signals in fast scintillators coupled to a fast PMT. Individual neutron-induced signals were consistent with the predictions of our model, but gamma pulses were broader than expected. We present various tests to understand this phenomenon and discuss a way to overcome this problem

  11. Optimisation studies for a moderator on a pulsed neutron source

    International Nuclear Information System (INIS)

    Picton, D.J.; Ross, D.K.; Taylor, A.D.

    1982-01-01

    Having reviewed general aspects of moderator design for pulsed neutron sources, calculations are presented on a number of aspects of moderator optimization. Results of time-independent calculations on metal hydride moderators and a detailed method of evaluating moderated pulse intensities and time distributions, are given. Using computer codes, neutron cross-sections have been calculated from vibrational frequency distributions and time-dependent moderator calculations performed by Monte Carlo methods. The choice of an ambient moderator material and the optimum configuration of heterogeneous poisoning are examined and evaluations of liquid-nitrogen-cooled moderators are presented. Conclusions are drawn concerning the relative merits of cooled and poisoned moderators and an evaluation presented of solid methane at 20 K as a moderator for the production of cold neutrons. (U.K.)

  12. Nondestructive analysis of the natural uranium mass through the measurement of delayed neutrons using the technique of pulsed neutron source

    International Nuclear Information System (INIS)

    Coelho, Paulo Rogerio Pinto

    1979-01-01

    This work presents results of non destructive mass analysis of natural uranium by the pulsed source technique. Fissioning is produced by irradiating the test sample with pulses of 14 MeV neutrons and the uranium mass is calculated on a relative scale from the measured emission of delayed neutrons. Individual measurements were normalised against the integral counts of a scintillation detector measuring the 14 MeV neutron intensity. Delayed neutrons were measured using a specially constructed slab detector operated in anti synchronism with the fast pulsed source. The 14 MeV neutrons were produced via the T(d,n) 4 He reaction using a 400 kV Van de Graaff accelerated operated at 200 kV in the pulsed source mode. Three types of sample were analysed, namely: discs of metallic uranium, pellets of sintered uranium oxide and plates of uranium aluminium alloy sandwiched between aluminium. These plates simulated those of Material Testing Reactor fuel elements. Results of measurements were reproducible to within an overall error in the range 1.6 to 3.9%; the specific error depending on the shape, size and mass of the sample. (author)

  13. Neutronic studies on decoupled hydrogen moderator for a short-pulse spallation source

    International Nuclear Information System (INIS)

    Harada, Masahide; Watanabe, Noboru; Teshigawara, Makoto; Kai, Tetsuya; Ikeda, Yujiro

    2005-01-01

    Neutronic studies of decoupled hydrogen moderators were performed by calculations taking into account para hydrogen content, decoupling energy, moderator dimensions/shapes and reflector material. Low-energy parts of calculated spectral intensities with different para hydrogen contents were analyzed by a modified Maxwell function to characterize neutron spectra. The result shows that a 100% para hydrogen moderator gives the highest pulse peak intensity together with the narrowest pulse width and the shortest decay times. Pulse broadening with a reflector was explained by time distributions of source neutrons entering into the moderator through a decoupler. Material dependence of time distribution was studied. A decoupling energy higher than 1 eV does not bring about a large improvement in pulse widths and decay times, even at a large penalty in the peak intensity. The optimal moderator thickness was also discussed for a rectangular parallelepipe-shaped and a canteen-shaped moderator

  14. Small-angle neutron scattering at pulsed spallation sources

    International Nuclear Information System (INIS)

    Seeger, P.A.; Hjelm, R.P. Jr.

    1991-01-01

    The importance of small-angle neutron scattering (SANS) in biological, chemical, physical and engineering research mandates that all intense neutron sources be equipped with SANS instruments. Four existing instruments at pulsed sources are described and the general differences between pulsed-source and reactor-based instrument designs are discussed. The basic geometries are identical, but dynamic range is generally achieved by using a broad band of wavelengths (with time-of-flight analysis) rather than by moving the detector. This allows optimization for maximum beam intensity at a given beam size over the full dynamic range with fixed collimation. Data-acquisition requirements at a pulsed source are more severe, requiring large fast histrograming memories. Data reduction is also more complex, as all wavelength-dependent and angle-dependent backgrounds and nonlinearities must be accounted for before data can be transformed to intensity vs momentum transfer (Q). A comparison is shown between the Los Alamos pulsed instrument and D11 (Institut Laue-Langevin) and examples from the four major topics of the conference are shown. The general conclusion is that reactor-based instruments remain superior at very low Q or if only a narrow range of Q is required, but that the current generation of pulsed-source instruments is competitive of moderate Q and may be faster when a wide range of Q is required. (orig.)

  15. Acoustic--nuclear permeability logging system

    International Nuclear Information System (INIS)

    Dowling, D.J.; Arnold, D.M.

    1978-01-01

    A down hole logging tool featuring a neutron generator, an acoustic disturbance generator, and a radiation detection system is described. An array of acoustic magnetostriction transducers is arranged about the target of a neutron accelerator. Two gamma ray sensors are separated from the accelerator target by shielding. According to the method of the invention, the underground fluid at the level of a formation is bombarded by neutrons which react with oxygen in the fluid to produce unstable nitrogen 16 particles according to the reaction 16 O(n,p) 16 N. Acoustic pulses are communicated to the fluid, and are incident on the boundary of the borehole at the formation. The resulting net flow of fluid across the boundary is determined from radiation detection measurements of the decaying 16 N particles in the fluid. A measure of the permeability of the formation is obtained from the determination of net fluid flow across the boundary

  16. Small size neutron tube UNG-1

    International Nuclear Information System (INIS)

    Bespalov, D.F.; Mints, A.Z.; Shkol'nikov, A.S.

    A tube UNG-1 (universal neutron gas-filled) is designed for the use in the well neutron generators IGN-1 and IGN-1-M (a pulse neutron generator). Their serial production in the USSR has been started in 1963. At the same year, the serial production of the tubes UNG-1 has been started. Thus, this tube is the first serial logging accelerating tube in the USSR. A Penning source, equipped with a hot cathode, was selected as an ion source of the tube

  17. The performance of neutron spectrometers AR a long-pulse spallation source

    International Nuclear Information System (INIS)

    Pynn, R.; Daemen, L.L.

    1995-01-01

    At a recent workshop at Lawrence Berkeley National Laboratory members of the international neutron scattering community discussed the performance to be anticipated from neutron scattering instruments installed at a 1 MW long-pulse spallation source (LPSS). Although the report of this workshop is long, its principal conclusions can be easily summarised and almost as easily understood. This article presents such a synthesis for a 60 Hz LPSS with 1 msec proton pulses. We discuss some of the limitations of the workshop conclusions and suggest a simple analysis of the performance differences that might be expected between short- and long-pulse sources both of which exploit coupled moderators

  18. A dense plasma focus-based neutron source for a single-shot detection of illicit materials and explosives by a nanosecond neutron pulse

    International Nuclear Information System (INIS)

    Gribkov, V A; Latyshev, S V; Miklaszewski, R A; Chernyshova, M; Drozdowicz, K; Wiacek, U; Tomaszewski, K; Lemeshko, B D

    2010-01-01

    Recent progress in a single-pulse Nanosecond Impulse Neutron Investigation System (NINIS) intended for interrogation of hidden objects by means of measuring elastically scattered neutrons is presented in this paper. The method uses very bright neutron pulses having duration of the order of 10 ns only, which are generated by dense plasma focus (DPF) devices filled with pure deuterium or DT mixture as a working gas. The small size occupied by the neutron bunch in space, number of neutrons per pulse and mono-chromaticity (ΔE/E∼1%) of the neutron spectrum provides the opportunity to use a time-of-flight (TOF) technique with flying bases of about a few metres. In our researches we used DPF devices having bank energy in the range 2-7 kJ. The devices generate a neutron yield of the level of 10 8 -10 9 2.45 MeV and 10 10 -10 11 14 MeV neutrons per pulse with pulse duration ∼10-20 ns. TOF base in the tests was 2.2-18.5 m. We have demonstrated the possibility of registering of neutrons scattered by the substances under investigation-1 litre bottles with methanol (CH 3 OH), phosphoric (H 2 PO 4 ) and nitric (HNO 3 ) acids as well as a long object-a 1 m gas tank filled with deuterium at high pressure. It is shown that the above mentioned short TOF bases and relatively low neutron yields are enough to distinguish different elements' nuclei composing the substance under interrogation and to characterize the geometry of lengthy objects in some cases. The wavelet technique was employed to 'clean' the experimental data registered. The advantages and restrictions of the proposed and tested NINIS technique in comparison with other methods are discussed.

  19. Characterization of the γ background in epithermal neutron scattering measurements at pulsed neutron sources

    International Nuclear Information System (INIS)

    Pietropaolo, A.; Tardocchi, M.; Schooneveld, E.M.; Senesi, R.

    2006-01-01

    This paper reports the characterization of the different components of the γ background in epithermal neutron scattering experiments at pulsed neutron sources. The measurements were performed on the VESUVIO spectrometer at ISIS spallation neutron source. These measurements, carried out with a high purity germanium detector, aim to provide detailed information for the investigation of the effect of the γ energy discrimination on the signal-to-background ratio. It is shown that the γ background is produced by different sources that can be identified with their relative time structure and relative weight

  20. Neutron dosimetry and spectrometry with Bonner spheres. Working out a log-normal reference matrix

    International Nuclear Information System (INIS)

    Zaborowski, Henrick.

    1981-11-01

    From the experimental and theoretical studies made upon the BONNER's spheres System with a I 6 Li(Eu) crystal and with a miniaturized 3 He counter we get the normalized energy response functions R*sub(i)(E). This normalization is obtained by the mathematization of the Resolution Function R*(i,E) in the Log-Normal distribution hypothesis to mono energetic neutrons given in April 1976 to the International Symposium on Californium 252. The fit of the Log-Normal Hypothesis with the experimental and Theoretical data is very satisfactory. The parameter's tabulated values allow a precise interpolation, at all energies between 0.4 eV and 15 MeV and for all spheres diameters between 2 and 12 inches, of the discretized R*sub(ij) Reference Matrix for the applications to neutron dosimetry and spectrometry [fr

  1. Device for measuring the dose rate of pulsed neutrons

    International Nuclear Information System (INIS)

    Klett, A.

    2009-01-01

    The author presents a new apparatus, developed in collaboration by Berthold Technologies and the German company DESY, allowing neutron pulsed fields to be measured. It is based on the activation by high energy neutrons of carbon 12 present in the sensor materials, and on the decay of short life radionuclides produced by this activation. The detection principle and system are briefly presented

  2. Generation and performance of a multigroup coupled neutron-gamma cross-section library for deterministic and Monte Carlo borehole logging analysis

    International Nuclear Information System (INIS)

    Kodeli, I.; Aldama, D. L.; De Leege, P. F. A.; Legrady, D.; Hoogenboom, J. E.; Cowan, P.

    2004-01-01

    As part of the IRTMBA (Improved Radiation Transport Modelling for Borehole Applications) project of the EU community's 5. framework program a special purpose multigroup cross-section library was prepared for use in deterministic and Monte Carlo oil well logging particle transport calculations. This library is expected to improve the prediction of the neutron and gamma spectra at the detector positions of the logging tool, and their use for the interpretation of the neutron logging measurements was studied. Preparation and testing of this library is described. (authors)

  3. Neutron-gamma discrimination based on pulse shape discrimination in a Ce:LiCaAlF{sub 6} scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Yamazaki, Atsushi, E-mail: a-yamazaki@nucl.nagoya-u.ac.jp [Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University (Japan); Watanabe, Kenichi; Uritani, Akira [Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University (Japan); Iguchi, Tetsuo [Department of Quantum Engineering, Graduate School of Engineering, Nagoya University (Japan); Kawaguchi, Noriaki [Tokuyama Corporation (Japan); Yanagida, Takayuki; Fujimoto, Yutaka; Yokota, Yuui; Kamada, Kei [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University (Japan); Fukuda, Kentaro; Suyama, Toshihisa [Tokuyama Corporation (Japan); Yoshikawa, Akira [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University (Japan)

    2011-10-01

    We demonstrate neutron-gamma discrimination based on a pulse shape discrimination method in a Ce:LiCAF scintillator. We have tried neutron-gamma discrimination using a difference in the pulse shape or the decay time of the scintillation light pulse. The decay time is converted into the rise time through an integrating circuit. A {sup 252}Cf enclosed in a polyethylene container is used as the source of thermal neutrons and prompt gamma-rays. Obvious separation of neutron and gamma-ray events is achieved using the information of the rise time of the scintillation light pulse. In the separated neutron spectrum, the gamma-ray events are effectively suppressed with little loss of neutron events. The pulse shape discrimination is confirmed to be useful to detect neutrons with the Ce:LiCAF scintillator under an intense high-energy gamma-ray condition.

  4. A Kinematically Beamed, Low Energy Pulsed Neutron Source for Active Interrogation

    International Nuclear Information System (INIS)

    Dietrich, D.; Hagmann, C.; Kerr, P.; Nakae, L.; Rowland, M.; Snyderman, N.; Stoeffl, W.; Hamm, R.

    2004-01-01

    We are developing a new active interrogation system based on a kinematically focused low energy neutron beam. The key idea is that one of the defining characteristics of SNM (Special Nuclear Materials) is the ability for low energy or thermal neutrons to induce fission. Thus by using low energy neutrons for the interrogation source we can accomplish three goals, (1) Energy discrimination allows us to measure the prompt fast fission neutrons produced while the interrogation beam is on; (2) Neutrons with an energy of approximately 60 to 100 keV do not fission 238U and Thorium, but penetrate bulk material nearly as far as high energy neutrons do and (3) below about 100keV neutrons lose their energy by kinematical collisions rather than via the nuclear (n,2n) or (n,n') processes thus further simplifying the prompt neutron induced background. 60 keV neutrons create a low radiation dose and readily thermal capture in normal materials, thus providing a clean spectroscopic signature of the intervening materials. The kinematically beamed source also eliminates the need for heavy backward and sideway neutron shielding. We have designed and built a very compact pulsed neutron source, based on an RFQ proton accelerator and a lithium target. We are developing fast neutron detectors that are nearly insensitive to the ever-present thermal neutron and neutron capture induced gamma ray background. The detection of only a few high energy fission neutrons in time correlation with the linac pulse will be a clear indication of the presence of SNM

  5. Method and apparatus for neutron induced gamma ray logging for lithology identification

    International Nuclear Information System (INIS)

    Oliver, D.W.; Culver, R.B.

    1981-01-01

    The patent describes a neutron-gamma well logging technique which can distinguish between sandstone and limestone formations irrespective of water salinity in the formation. The formation surrounding a borehole is irradiated by fast neutrons and the resulting gamma rays are counted. The gamma rays are converted to electrical signals in three distinct steps; the first two signals result from gamma rays associated with calcium content of the formation and the third signal from gamma rays associated with silicon content. Gamma rays resulting from irradiation of calcium are counted at two non-contiguous energy bands. (O.T.)

  6. Monte Carlo modeling and analyses of YALINA- booster subcritical assembly Part II: pulsed neutron source

    International Nuclear Information System (INIS)

    Talamo, A.; Gohar, M.Y.A.; Rabiti, C.

    2008-01-01

    One of the most reliable experimental methods for measuring the kinetic parameters of a subcritical assembly is the Sjoestrand method applied to the reaction rate generated from a pulsed neutron source. This study developed a new analytical methodology for characterizing the kinetic parameters of a subcritical assembly using the Sjoestrand method, which allows comparing the analytical and experimental time dependent reaction rates and the reactivity measurements. In this methodology, the reaction rate, detector response, is calculated due to a single neutron pulse using MCNP/MCNPX computer code or any other neutron transport code that explicitly simulates the fission delayed neutrons. The calculation simulates a single neutron pulse over a long time period until the delayed neutron contribution to the reaction is vanished. The obtained reaction rate is superimposed to itself, with respect to the time, to simulate the repeated pulse operation until the asymptotic level of the reaction rate, set by the delayed neutrons, is achieved. The superimposition of the pulse to itself was calculated by a simple C computer program. A parallel version of the C program is used due to the large amount of data being processed, e.g. by the Message Passing Interface (MPI). The new calculation methodology has shown an excellent agreement with the experimental results available from the YALINA-Booster facility of Belarus. The facility has been driven by a Deuterium-Deuterium or Deuterium-Tritium pulsed neutron source and the (n,p) reaction rate has been experimentally measured by a 3 He detector. The MCNP calculation has utilized the weight window and delayed neutron biasing variance reduction techniques since the detector volume is small compared to the assembly volume. Finally, this methodology was used to calculate the IAEA benchmark of the YALINA-Booster experiment

  7. Rietveld refinement with time-of-flight powder diffraction data from pulsed neutron sources

    International Nuclear Information System (INIS)

    David, W.I.F.; Jorgensen, J.D.

    1990-10-01

    The recent development of accelerator-based pulsed neutron sources has led to the widespread use of the time-of-flight technique for neutron powder diffraction. The properties of the pulsed source make possible unusually high resolution over a wide range of d spacings, high count rates, and the ability to collect complete data at fixed scattering angles. The peak shape and other instrument characteristics can be accurately modelled, which make Rietveld refinement possible for complex structures. In this paper we briefly review the development of the Rietveld method for time-of-flight diffraction data from pulsed neutron sources and discuss the latest developments in high resolution instrumentation and advanced Rietveld analysis methods. 50 refs., 12 figs., 14 tabs

  8. Borehole logging system

    International Nuclear Information System (INIS)

    Allen, L.S.

    1988-01-01

    A radioactive borehole logging tool employs an epithermal neutron detector having a neutron counter surrounded by an inner thermal neutron filter and an outer thermal neutron filter. Located between the inner and outer filters is a neutron moderating material for extending the lifetime of epithermal neutrons to enhance the counting rate of such epithermal neutrons by the neutron counter

  9. Inelastic neutron scattering reactions in fluid saturated rock as exploited in oil well logging

    International Nuclear Information System (INIS)

    Underwood, M.C.; Dyos, C.J.

    1986-01-01

    Oil saturated sandstone and limestone targets have been irradiated with 14 MeV neutrons. Gamma-ray spectra were accumulated and the γ-ray intensities arising from inelastic neutron scattering reactions upon carbon and oxygen measured. The results are compared with the predictions of a simple model. They enable some features of the response of (n,γ) tools used in oil well logging to be established and current uncertainties in understanding to be highlighted. (author)

  10. Digital discrimination of neutrons and γ-rays in liquid scintillators using pulse gradient analysis

    International Nuclear Information System (INIS)

    D'Mellow, B.; Aspinall, M.D.; Mackin, R.O.; Joyce, M.J.; Peyton, A.J.

    2007-01-01

    A method for the digital discrimination of neutrons and γ-rays in mixed radiation fields is described. Pulses in the time domain, arising from the interaction of photons and neutrons in a liquid scintillator, have been produced using an accepted empirical model and from experimental measurements with an americium-beryllium source. Neutrons and γ-rays have been successfully discriminated in both of these data sets in the digital domain. The digital discrimination method described in this paper is simple and exploits samples early in the life of the pulse. It is thus compatible with current embedded system technologies, offers a degree of immunity to pulse pile-up and heralds a real-time means for neutron/γ discrimination that is fundamental to many potential industrial applications

  11. The performance of neutron scattering spectrometers at a long-pulse spallation source

    International Nuclear Information System (INIS)

    Pynn, R.

    1995-01-01

    The first conclusion the author wants to draw is that comparison of the performance of neutron scattering spectrometers at CW and pulsed sources is simpler for long-pulsed sources than it is for the short-pulse variety. Even though detailed instrument design and assessment will require Monte Carlo simulations (which have already been performed at Los Alamos for SANS and reflectometry), simple arguments are sufficient to assess the approximate performance of spectrometers at an LPSS and to support the contention that a 1 MW long-pulse source can provide attractive performance, especially for instrumentation designed for soft-condensed-matter science. Because coupled moderators can be exploited at such a source, its time average cold flux is equivalent to that of a research reactor with a power of about 15 MW, so only a factor of 4 gain from source pulsing is necessary to obtain performance that is comparable with the ILL. In favorable cases, the gain from pulsing can be even more than this, approaching the limit set by the peak flux, giving about 4 times the performance of the ILL. Because of its low duty factor, an LPSS provides the greatest performance gains for relatively low resolution experiments with cold neutrons. It should thus be considered complementary to short pulse sources which are most effective for high resolution experiments using thermal or epithermal neutrons

  12. Method and apparatus for epithermal neutron decay logging

    International Nuclear Information System (INIS)

    Nelligan, W.B.

    1998-01-01

    The nature of hydrogenous fluids filling the pore spaces in formations surrounding a well bore are determined by irradiating the formations with bursts of high energy neutrons and using the ratio of time-dependent parameters related to the decay of epithermal neutron populations above two different energy levels to provide values indicative of the kind of fluid present, independent of porosity. The measurement above the higher of these energy levels, appr. 0.4eV, indicates the existence of hydrogenous fluid, water and hydrocarbons in the formations. The lower threshold measurement, above appr. 0.15eV, is indicative of the structure of the molecule in which the hydrogen molecule is bound and of the porosity. A pulsed neutron generator in a sonde irradiates the formations with 14meV neutrons and a pair of detectors, one shielded by cadmium, to establish the 0.4eV threshold energy level and the other, shielded by gadolinium, to establish the 0.15eV threshold energy level. Time related parameters of the count rate information, e.g. the decay constants, provided by each detector are derived. The ratio of the respective parameters is used to identify the type of fluid in the information, independent of porosity. The method and apparatus can determine water saturation, i.e. percentage of water in the formation fluid and can identify specific types of hydrocarbons under 100% hydrocarbon saturation conditions. 8 figs

  13. 4th meeting on advanced pulsed-neutron research on quantum functions in nano-scale materials

    International Nuclear Information System (INIS)

    2006-07-01

    Toward the worldwide realization of high-intensity pulsed neutron source, KEK (High Energy Accelerator Research Organization) proceeds the research by composing 6 research groups as neutron science initiation base to initiate new neutron science. The papers generalizing the researches for 2 years were presented at this meeting. KENS (Neutron Science Laboratory, KEK) shut down on March 22nd in 2006, and KEK will continue the research utilizing the pulsed neutron by using foreign facilities until the completion of J-PARC from now on. At international session in this meeting, the accomplishments and future prospects about the Japan-United Kingdom science and technology collaboration project, and about the research collaboration projects with IPNS (Intense Pulsed Neutron Source, ANL) and LANSCE (Los Alamos Neutron Science Center) were presented. Especially in the latter projects, the first accomplishment was reported under the present agreement. In addition, Meeting on structural study of proteins in aqueous solutions' and 'Meeting on hydrogen quantum atomics study' were held as satellite meetings. (J.P.N)

  14. Assay of fissionable isotopes in aqueous solution by pulsed neutron interrogation

    International Nuclear Information System (INIS)

    Campbell, P.; Gardy, E.M.; Boase, D.G.

    1978-04-01

    Non-destructive assay of uranium-235 and thorium-232 in aqueous nitric acid solutions has been accomplished by irradiation with pulses of neutrons from a 14-MeV Cockcroft-Walton neutron generator, and counting of the delayed neutrons emitted from the fissions induced. Design of the delayed neutron detector assemblies is described, together with the neutron pulse timing and counting systems. The effects of irradiation time, counting time, neutron moderation, detector design and sample geometry on the delayed neutron response from uranium-235 and 238 and thorium-232 are discussed. By using polyethylene to moderate the interrogating neutrons, solutions can be analyzed for both uranium-235 and thorium. Comparative analyses with chemical and γ-spectrometric methods show good agreement. The neutron method is rapid and is shown to be unaffected by the presence in solution of impurities such as iron, nickel, chromium, and aluminum. With the experimental equipment described, detection limits of 0.6 mg of 235 U and 9 mg of 232 Th in a sample volume of 25 mL have been achieved. Analyses of highly radioactive samples may be done easily since the measurements are not affected by the presence of large amounts of βγ radiation. Samples can be enclosed in small lead-shielded flasks during analysis to protect the analyst. The potential of the technique to on-line analysis applications is explored briefly. (author)

  15. Annular shape silver lined proportional counter for on-line pulsed neutron yield measurement

    International Nuclear Information System (INIS)

    Dighe, P.M.; Das, D.

    2015-01-01

    An annular shape silver lined proportional counter is developed to measure pulsed neutron radiation. The detector has 314 mm overall length and 235 mm overall diameter. The central cavity of 150 mm diameter and 200 mm length is used for placing the neutron source. Because of annular shape the detector covers >3π solid angle of the source. The detector has all welded construction. The detector is developed in two halves for easy mounting and demounting. Each half is an independent detector. Both the halves together give single neutron pulse calibration constant of 4.5×10 4 neutrons/shot count. The detector operates in proportional mode which gives enhanced working conditions in terms of dead time and operating range compared to Geiger Muller based neutron detectors

  16. Instrument intercomparison in the pulsed neutron fieldsat the CERN HiRadMat facility

    CERN Document Server

    Aza, E; Cassell, C; Charitonidis, N; Harrouch, E; Manessi, G P; Pangallo, M; Perrin, D; Samara, E; Silari, M

    2014-01-01

    An intercomparison of the performances of active neutron detectors was carried out in pulsed neutron fi elds in the new HiRadMat facility at CERN. Five detectors were employed: four of them (two ionization chambers and two rem counters) are routinely employed in the CERN radiation monitoring system, while the fi fth is a novel instrument, called LUPIN, speci fi cally conceived for applications in pulsed neutron fi elds. The measurements were performed in the stray fi eld generated by a proton beam of very short duration with momentum of 440 GeV/c impinging on a dump. The beam intensity was steadily increased during the experiment by more than three orders of magnitude, with an H*(10) due to neutrons at the detector reference positions varying between a few nSv per burst and a few m Sv per burst, whereas the gamma contribution to the total H*(10) was negligible. The aim of the experiment was to evaluate the linearity of the detector response in extreme pulsed conditions as a function of the neutron burst in- t...

  17. Backscattering at a pulsed neutron source, the MUSICAL instrument

    International Nuclear Information System (INIS)

    Alefeld, B.

    1995-01-01

    In the first part the principles of the neutron backscattering method are described and some simple considerations about the energy resolution and the intensity are presented. A prototype of a backscattering instrument, the first Juelich instrument, is explained in some detail and a representative measurement is shown which was performed on the backscattering instrument IN10 at the ILL in Grenoble. In the second part a backscattering instrument designed for a pulsed neutron source is proposed. It is shown that a rather simple modification, which consists in the replacement of the Doppler drive of the conventional backscattering instrument by a multi silicon monochromator crystal (MUSICAL) leads to a very effective instrument, benefitting from the peak flux of the pulsed source. ((orig.))

  18. Performance of the intense pulsed neutron source accelerator system

    International Nuclear Information System (INIS)

    Potts, C.; Brumwell, F.; Rauchas, A.; Stipp, V.; Volk, G.

    1983-01-01

    The Intense Pulsed Neutron Source (IPNS) facility has now been operating in a routine way for outside users since November 1, 1981. From that date through December of 1982, the accelerator system was scheduled for neutron science for 4500 hours. During this time the accelerator achieved its short-term goals by delivering about 380,000,000 pulses of beam totaling over 6 x 10 20 protons. The changes in equipment and operating practices that evolved during this period of intense running are described. The intensity related instability threshold was increased by a factor of two and the accelerator beam current has been ion source limited. Plans to increase the accelerator intensity are also described. Initial operating results with a new H - ion source are discussed

  19. Test and application of thermal neutron radiography facility at Xi'an pulsed reactor

    CERN Document Server

    Yang Jun; Zhao Xiang Feng; Wang Dao Hua

    2002-01-01

    A thermal neutron radiography facility at Xi'an Pulsed Reactor is described as well as its characteristics and application. The experiment results show the inherent unsharpness of BAS ND is 0.15 mm. The efficient thermal neutron n/gamma ratio is lower in not only steady state configuration but also pulsing state configuration and it is improved using Pb filter

  20. ASPUN: design for an Argonne super-intense pulsed neutron source

    International Nuclear Information System (INIS)

    Khoe, T.K.; Kustom, R.L.

    1983-01-01

    Argonne pioneered the pulsed spallation neutron source with the ZING-P and IPNS-I concepts. IPNS-I is now a reliable and actively used source for pulsed spallation neutrons. The accelerator is a 500-MeV, 8 to 9 μa, 30-Hz rapid-cycling proton synchrotron. Other proton spallation sources are now in operation or in construction. These include KENS-I at the National Laboratory for High Energy Physics in Japan, the WNR/PSR at Los Alamos National Laboratory in the USA, and the SNS at the Rutherford Appleton Laboratory in England. Newer and bolder concepts are being developed for more-intense pulsed spallation neutron sources. These include SNQ at the KFA Laboratory in Juelich, Germany, ASTOR at the Swiss Institute for Nuclear Physics in Switzerland, and ASPUN, the Argonne concept. ASPUN is based on the Fixed-Field Alternating Gradient concept. The design goal is to provide a time-averaged beam of 3.5 ma at 1100 MeV on a spallation target in intense bursts, 100 to 200 nanoseconds long, at a repetition rate of no more than 60 to 85 Hz

  1. Pulsed neutron determination of anisotropic diffusion constants in multi-layered slabs

    International Nuclear Information System (INIS)

    Sri Ram, K.

    1978-01-01

    Anisotropic neutron diffusion parameters for graphite and plexiglas slab assemblies were calculated using one-dimensional discrete ordinates code ANISN, and also Case's eigenfunction expansion technique as suggested by Leonard. These calculated values were checked with the pulsed neutron experimental results as well as simple diffusion theory calculations of Spinrad. Relatively little experimental work has been done with heterogeneous assemblies which do not contain voids. The present comparison shows that the experimental results agree well with transport theory calculations. It appears from the results and inter-comparison of this work in simple geometries, that the pulsed neutron method can yield accurate experimental anisotropic diffusion constants, and can therefore be applied to more complicated geometries which may be difficult to calculate. (author)

  2. An economic alternative to conventional open hole logging in horizontal wells; Eine oekonomische Alternative zu konventionellen Bohrlochmessungen in Horizontalbohrungen

    Energy Technology Data Exchange (ETDEWEB)

    Hogan, G.P.; Kater, H.; Ball, S.; Preiss, F. [Precision Drilling-Computalog, Edemissen (Germany)

    2003-04-01

    Horizontal drilling has become a routine method of field development over the past several years as a means to maximise recoverable reserves. As such, horizontal drilling has impacted the way that petrophysical data is obtained in order to evaluate the reservoir during and after drilling. In horizontal wells, conventional open hole logging methods must be combined with either pipe conveyed logging techniques or coiled tubing conveyed techniques. In many cases, these procedures are time consuming and cost prohibitive based on the economics of the project. Additionally, formation evaluation data may be obtained in horizontal wells by using Logging While Drilling (LWD) technology, but this may also be cost prohibitive in many areas. In the Girkaliai and Nausodis Fields in Lithuania, two wells were drilled to reach oil producing reservoir sandstones at depths of over 1,800 m TVD with horizontal sections of approximately 270 m and 385 m. Based on an economic and petrophysical analysis, neither open hole pipe conveyed logging nor LSW were considered since neither were regarded as cost effective to obtain the petrophysical data required to evaluate the reservoir. An alternative method to obtain critical formation evaluation data was employed utilizing a cased hole pulsed neutron decay logging tool run in the open hole. In one case this was done immediately after drilling. The pulsed neutron decay logging tool was conveyed to TD by a specially modified wireline tractor system. The obtained logs provided critical information to evaluate the reservoir including determining density porosity, neutron porosity, sigma (formation capture cross section) and gamma ray. The data was used to calculate required petrophysical information including lithology, water saturation, and bulk volumes. (orig.)

  3. The efficient neutron-gamma pulse shape discrimination with small active volume scintillation detector

    International Nuclear Information System (INIS)

    Phan Van Chuan; Nguyen Duc Hoa; Nguyen Xuan Hai; Nguyen Ngoc Anh; Tuong Thi Thu Huong; Nguyen Nhi Dien; Pham Dinh Khang

    2016-01-01

    A small detector with EJ-301 liquid scintillation was manufactured for the study on the neutron-gamma pulse shape discrimination. In this research, four algorithms, including Threshold crossing time (TCT), Pulse gradient analysis (PGA), Charge comparison method (CCM), and Correlation pattern recognition (CPR) were developed and compared in terms of their discrimination effectiveness between neutrons and gamma rays. The figures of merits (FOMs) obtained for 100 ÷ 2000 keVee (keV energy electron equivalent) neutron energy range show the charge comparison method was the most efficient of the four algorithms. (author)

  4. Fast neutron flux analyzer with real-time digital pulse shape discrimination

    Energy Technology Data Exchange (ETDEWEB)

    Ivanova, A.A., E-mail: a.a.ivanova@inp.nsk.su [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Zubarev, P.V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 630092 Novosibirsk (Russian Federation); Ivanenko, S.V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Khilchenko, A.D. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 630092 Novosibirsk (Russian Federation); Kotelnikov, A.I. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Polosatkin, S.V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 630092 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Puryga, E.A.; Shvyrev, V.G. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 630092 Novosibirsk (Russian Federation); Sulyaev, Yu.S. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

    2016-08-11

    Investigation of subthermonuclear plasma confinement and heating in magnetic fusion devices such as GOL–3 and GDT at the Budker Institute (Novosibirsk, Russia) requires sophisticated equipment for neutron-, gamma- diagnostics and upgrading data acquisition systems with online data processing. Measurement of fast neutron flux with stilbene scintillation detectors raised the problem of discrimination of the neutrons (n) from background cosmic particles (muons) and neutron-induced gamma rays (γ). This paper describes a fast neutron flux analyzer with real-time digital pulse-shape discrimination (DPSD) algorithm FPGA-implemented for the GOL–3 and GDT devices. This analyzer was tested and calibrated with the help of {sup 137}Cs and {sup 252}Cf radiation sources. The Figures of Merit (FOM) calculated for different energy cuts are presented. - Highlights: • Electronic equipment for measurement of fast neutron flux with stilbene scintillator is presented. • FPGA-implemented digital pulse-shape discrimination algorithm by charge comparison method is shown. • Calibration of analyzer was carried out with {sup 137}Cs and {sup 252}Cf. • Figures of Merit (FOM) values for energy cuts from 1/8 Cs to 2 Cs are from 1.264 to 2.34 respectively.

  5. Performance of a reflectometer at continuous wave and pulsed neutron sources

    International Nuclear Information System (INIS)

    Fitzsimmons, M.R.

    1995-01-01

    The Monte-Carlo simulations presented here involve simulations of reflectivity measurements of one sample using a reflectometer of traditional geometry at different neutron sources. The same reflectometer was used in all simulations. Only the characteristics of the neutron source, and the technique used to measure neutron wavelength were changed. In the case of the CW simulation, a monochromating crystal was used to select a nearly monochromatic beam (MB) from the neutron spectrum. In the simulations of the pulse sources, the time needed to traverse a fixed distance was measured, from which neutron wavelength is deduced

  6. Status of the intense pulsed neutron source

    International Nuclear Information System (INIS)

    Carpenter, J.M.; Brown, B.S.; Kustom, R.L.; Lander, G.H.; Potts, C.W.; Schulke, A.W.; Wuestefeld, G.

    1985-01-01

    Fortunately in spite of some premature reports of its impending demise, IPNS has passed the fourth anniversary of the first delivery of protons to the targets (May 5, 1981) and is approaching the fourth anniversary of its operation as a scattering facility (August 4, 1981). On June 10, 1984, the RCS delivered its one billionth pulse to the IPNS target - the total number of protons delivered to the targets amounted then to 75 stp cm 3 of H 2 gas. Since startup IPNS has improved steadily in terms of the performance of the Rapid Cycling Synchrotron, the source and its moderators and the scattering instruments, and a substantial and productive user program has evolved. This report summarizes the current status of the Intense Pulsed Neutron Source at Argonne National Laboratory. We include reference to recent accelerator operating experience, neutron facility operating experience, improvements to these systems, design work on the ASPUN high-current facility, booster target design, the new solid methane moderator, characterization of the room temperature moderators, and provide some examples of recent results from several of the spectrometers

  7. Rapid response and wide range neutronic power measuring systems for fast pulsed reactors

    International Nuclear Information System (INIS)

    Sumita, Kenji; Iida, Toshiyuki; Wakayama, Naoaki.

    1976-01-01

    This paper summarizes our investigation on design principles of the rapid, stable and wide range neutronic power measuring system for fast pulsed reactors. The picoammeter, the logarithmic amplifier, the reactivity meter and the neutron current chamber are the items of investigation. In order to get a rapid response, the method of compensation for the stray capacitance of the feedback circuits and the capacitance of signal cables is applied to the picoammeter, the logarithmic amplifier and the reactivity meter with consideration for the stability margin of a whole detecting system. The response of an ionization current chamber and the method for compensating the ion component of the chamber output to get optimum responses high pass filters are investigated. Statistical fluctuations of the current chamber output are also considered in those works. The optimum thickness of the surrounding moderator of the neutron detector is also discussed from the viewpoint of the pulse shape deformation and the neutron sensitivity increase. The experimental results are reported, which were observed in the pulse operations of the one shot fast pulsed reactor ''YAYOI'' and the one shot TRIGA ''NSRR'' with the measuring systems using those principles. (auth.)

  8. Analysis of the scintillation mechanism in a pressurized 4He fast neutron detector using pulse shape fitting

    Directory of Open Access Journals (Sweden)

    R.P. Kelley

    2015-03-01

    Full Text Available An empirical investigation of the scintillation mechanism in a pressurized 4He gas fast neutron detector was conducted using pulse shape fitting. Scintillation signals from neutron interactions were measured and averaged to produce a single generic neutron pulse shape from both a 252Cf spontaneous fission source and a (d,d neutron generator. An expression for light output over time was then developed by treating the decay of helium excited states in the same manner as the decay of radioactive isotopes. This pulse shape expression was fitted to the measured neutron pulse shape using a least-squares optimization algorithm, allowing an empirical analysis of the mechanism of scintillation inside the 4He detector. A further understanding of this mechanism in the 4He detector will advance the use of this system as a neutron spectrometer. For 252Cf neutrons, the triplet and singlet time constants were found to be 970 ns and 686 ns, respectively. For neutrons from the (d,d generator, the time constants were found to be 884 ns and 636 ns. Differences were noted in the magnitude of these parameters compared to previously published data, however the general relationships were noted to be the same and checked with expected trends from theory. Of the excited helium states produced from a 252Cf neutron interaction, 76% were found to be born as triplet states, similar to the result from the neutron generator of 71%. The two sources yielded similar pulse shapes despite having very different neutron energy spectra, validating the robustness of the fits across various neutron energies.

  9. Dependence of the neutron-gamma log on the porosity of Malmian limestones from the central part of the Nida Trough

    International Nuclear Information System (INIS)

    Szczerba, A.

    1974-01-01

    Results of correlation-regression analysis of the relationship of the prosity Kp to the relative intensity of neutron-induced gamma radiation dIng are reviewed. The geophysical results and laboratory tests of Malmian carbonate rocks from 10 boreholes from the central part of the Nida trough have been utilized to study this relationship. The regression equation dIng=∫(Kp) and the nomogram to determine the porosity Kp on the basis of neutron-gamma log or neutron-gamma and gamma logs, when the correction for the content is to be considered, have been also presented. (author)

  10. The potential for biological structure determination with pulsed neutrons

    International Nuclear Information System (INIS)

    Wilson, C.C.

    1994-01-01

    The potential of pulsed neutron diffraction in structural determination of biological materials is discussed. The problems and potential solutions in this area are outlined, with reference to both current and future sources and instrumentation. The importance of developing instrumentation on pulsed sources in emphasized, with reference to the likelihood of future expansion in this area. The possibilities and limitations of single crystal, fiber and powder diffraction in this area are assessed

  11. The potential for biological structure determination with pulsed neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, C.C. [CLRC Rutherford Appleton Laboratory, Chilton Didcot Oxon (United Kingdom)

    1994-12-31

    The potential of pulsed neutron diffraction in structural determination of biological materials is discussed. The problems and potential solutions in this area are outlined, with reference to both current and future sources and instrumentation. The importance of developing instrumentation on pulsed sources in emphasized, with reference to the likelihood of future expansion in this area. The possibilities and limitations of single crystal, fiber and powder diffraction in this area are assessed.

  12. Device for Writing the Time Tail from Spallation Neutron Pulses

    International Nuclear Information System (INIS)

    Langan, P.; Schoenborn, Benno P.; Daemen, L.L.

    2001-01-01

    Recent work at Los Alamos Neutron Science Center (LANSCE), has shown that there are large gains in neutron beam intensity to be made by using coupled moderators at spallation neutron sources. Most of these gains result from broadening the pulse-width in time. However the accompanying longer exponential tail at large emission times can be a problem in that it introduces relatively large beam-related backgrounds at high resolutions. We have designed a device that can reshape the moderated neutron beam by cutting the time-tail so that a sharp time resolution can be re-established without a significant loss in intensity. In this work the basic principles behind the tail-cutter and some initial results of Monte Carlo simulations are described. Unwanted neutrons in the long time-tail are diffracted out of the transmitted neutron beam by a nested stack of aperiodic multi-layers, rocking at the same frequency as the source. Nested aperiodic multi-layers have recently been used at X-ray sources and as band-pass filters in quasi-Laue neutron experiments at reactor neutron sources. Optical devices that rock in synchronization with a pulsed neutron beam are relatively new but are already under construction at LANSCE. The tail-cutter described here is a novel concept that uses existing multi-layer technology in a new way for spallation neutrons. Coupled moderators in combination with beam shaping devices offer the means of increasing flux whilst maintaining a sharp time distribution. A prototype device is being constructed for the protein crystallography station at LANSCE. The protein crystallography station incorporates a water moderator that has been judiciously coupled in order to increase the flux over neutron energies that are important to structural biology (3-80meV). This development in moderator design is particularly important because protein crystallography is flux limited and because conventional ambient water and cold hydrogen moderators do not provide relatively

  13. Fast neutron (14 MeV) attenuation analysis in saturated core samples and its application in well logging

    International Nuclear Information System (INIS)

    Amin Attarzadeh; Mohammad Kamal Ghassem Al Askari; Tagy Bayat

    2009-01-01

    To introduce the application of nuclear logging, it is appropriate to provide a motivation for the use of nuclear measurement techniques in well logging. Importance aspects of the geological sciences are for instance grain and porosity structure and porosity volume of the rocks, as well as the transport properties of a fluid in the porous media. Nuclear measurements are, as a rule non-intrusive. Namely, a measurement does not destroy the sample, and it does not interfere with the process to be measured. Also, non- intrusive measurements are often much faster than the radiation methods, and can also be applied in field measurements. A common type of nuclear measurement employs neutron irradiation. It is powerful technique for geophysical analysis. In this research we illustrate the detail of this technique and it's applications to well logging and oil industry. Experiments have been performed to investigate the possibilities of using neutron attenuation measurements to determine water and oil content of rock sample. A beam of 14 MeV neutrons produced by a 150 KV neutron generator was attenuated by different samples and subsequently detected with plastic scintillators NE102 (Fast counter). Each sample was saturated with water and oil. The difference in neutron attenuation between dry and wet samples was compared with the fluid content determined by mass balance of the sample. In this experiment we were able to determine 3% of humidity in standard sample model (SiO 2 ) and estimate porosity in geological samples when saturated with different fluids. (Author)

  14. Pulsed neutron intensity from rectangular shaped light water moderator with fast-neutron reflector

    International Nuclear Information System (INIS)

    Kiyanagi, Yoshiaki; Iwasa, Hirokatsu

    1982-01-01

    With a view to enhancing the thermal-neutron intensity obtained from a pulsed neutron source, an experimental study has been made to determine the optimum size of a rectangular shaped light water moderator provided with fast neutron reflector of beryllium oxide or graphite, and decoupled thermal-neutronically by means of Cd sheet. The optimum dimensions for the moderator are derived for the neutron emission surface and the thickn ess, for the cases in which the neutron-producing target is placed beneath the moderator (''wing geometry'') or immediately behind the moderator (''slab geometry''). The major conclusions drawn from the experimental results are as follows. The presence of the Cd decoupler inserted between the moderator and reflector prevent the enhancement of thermal-neutron emission time gained by the provision of reflector. With a graphite reflector about 14 cm thick, (a) the optimum area of emission surface would be 25 x 25 cm 2 for wing geometry and still larger for slab geometry, and (b) the optimum moderator thickness would be 5.5 cm for slab geometry and 8.5 cm for wing geometry. It is thus concluded that a higher neutron emission intensity can be obtained with slab than with wing geometry provided that a large emission surface can be adopted for the moderator. (author)

  15. Time pulse profiles on a new data acquisition system for neutron time of flight diffractometer

    International Nuclear Information System (INIS)

    Venegas, R.; Baeza, L.; Navarro, G.

    1999-01-01

    A new differential acquisition system was built for a neutron diffuse scattering instrument. We analyze the time, space and velocity behavior of neutron pulse profiles, which can be obtained in a neutron diffuse scattering system of this nature, consisting of a black disc slit chopper and a circular detector bank, in order to design accurate scattering data analyzing methods. Computed direct pulse time spectra and measured spectra show satisfactory agreement. (author)

  16. Pulsed neutron generator system for astrobiological and geochemical exploration of planetary bodies

    International Nuclear Information System (INIS)

    Akkurt, Hatice; Groves, Joel L.; Trombka, Jacob; Starr, Richard; Evans, Larry; Floyd, Samuel; Hoover, Richard; Lim, Lucy; McClanahan, Timothy; James, Ralph; McCoy, Timothy; Schweitzer, Jeffrey

    2005-01-01

    A pulsed neutron/gamma-ray detection system for use on rovers to survey the elemental concentrations of Martian and Lunar surface and subsurface materials is evaluated. A robotic survey system combining a pulsed neutron generator (PNG) and detectors (gamma ray and neutron) can measure the major constituents to a depth of about 30 cm. Scanning mode measurements can give the major elemental concentrations while the rover is moving; analyzing mode measurements can give a detailed elemental analysis of the adjacent material when the rover is stationary. A detailed map of the subsurface elemental concentrations will provide invaluable information relevant to some of the most fundamental astrobiological questions including the presence of water, biogenic activity, life habitability and deposition processes

  17. Method of analysis to determine subcritical reactivity from the pulsed neutron experiment

    International Nuclear Information System (INIS)

    Parks, P.B.

    1975-06-01

    The published methods for the deduction of reactivity from pulsed neutron experiments on subcritical reactors are reviewed. Each method is categorized as inherently yielding a result that is either spatially independent or spatially dependent. The spatially independent results are formally identical with the static reactivity; the result does not depend, in principle, on the location of either the pulsed neutron source or the neutron detector during data collection. The spatially dependent results only approximate the static reactivity; the results are affected, in varying degrees, by the locations of the source and detector. Among the techniques yielding spatially independent results are the Space-Time method of Parks and Stewart and the Inhour method of Preskitt et al. Spatially dependent results are obtained with the Sjoestrand, Gozani, and Garelis-Russell methods which are examined with and without the kinetic distortion corrections given by Becker and Quisenberry. Intercomparisons of all methods are made with reference to pulsed neutron experiments on both unreflected and reflected reactors. Recommendations are made concerning the best choice of method under the various experimental conditions that are likely to be encountered. 14 references. (U.S.)

  18. Study of two-zone reactor system using a pulsed neutron technique

    Energy Technology Data Exchange (ETDEWEB)

    Shishin, B P; Platovskikh, Yu A; Didejkin, T S

    1977-05-01

    Theoretical and experimental investigations of a neutron flux time dependence after a sport fast neutron pulse in a reactor core - neutron reflector multiplying system have been conducted. A correlation between eigenvalues governing neutron flux decrease at t..-->..infinity for the two-zone system and eigenvalues for each zone has been established in terms of the one-group diffusion approximation. Experiments have been performed in an experimental subcritical assembly comprising a cylindrical uranium core surrounded by a radial water reflector with different boric acid concentrations.

  19. The Real-time Frequency Spectrum Analysis of Neutron Pulse Signal Series

    International Nuclear Information System (INIS)

    Tang Yuelin; Ren Yong; Wei Biao; Feng Peng; Mi Deling; Pan Yingjun; Li Jiansheng; Ye Cenming

    2009-01-01

    The frequency spectrum analysis of neutron pulse signal is a very important method in nuclear stochastic signal processing Focused on the special '0' and '1' of neutron pulse signal series, this paper proposes new rotation-table and realizes a real-time frequency spectrum algorithm under 1G Hz sample rate based on PC with add, address and SSE. The numerical experimental results show that under the count rate of 3X10 6 s -1 , this algorithm is superior to FFTW in time-consumption and can meet the real-time requirement of frequency spectrum analysis. (authors)

  20. Small-angle neutron scattering at pulsed spallation sources

    International Nuclear Information System (INIS)

    Seeger, P.A.; Hjelm, R.P. Jr.

    1990-01-01

    The importance of small-angle neutron scattering (SANS) in biological, chemical, physical, and engineering research mandates that all intense neutron sources be equipped with SANS instruments. Four existing instruments are described, and the general differences between pulsed-source and reactor-based instrument designs are discussed. The basic geometries are identical, but dynamic range is achieved by using a broad band of wavelengths (with time-of-flight analysis) rather than by moving the detector. This allows a more optimized collimation system. Data acquisition requirements at a pulsed source are more severe, requiring large, fast histogramming memories. Data reduction is also more complex, as all wave length-dependent and angle-dependent backgrounds and non-linearities must be accounted for before data can be transformed to intensity vs Q. A comparison is shown between the Los Alamos pulsed instrument and D-11 (Institute Laue-Langevin), and examples from the four major topics of the conference are shown. The general conclusion is that reactor-based instruments remain superior at very low Q or if only a narrow range of Q is required, but that the current generation of pulsed-source instruments is competitive at moderate Q and may be faster when a wide range of Q is required. In principle, a user should choose which facility to use on the basis of optimizing the experiment; in practice the tradeoffs are not severe and the choice is usually made on the basis of availability

  1. Logging technique for assaying for uranium in rocks

    International Nuclear Information System (INIS)

    Givens, W.W.

    1973-01-01

    A uranium exploration technique is described for determining the uranium content of a formation traversed by borehole. A delayed fission neutron assay log is obtained by irradiating the formation with repetitive bursts of fast neutrons and detecting delayed neutrons resulting from neutron fission of uranium at time intervals between the fast neutron bursts and after dissipation of the neutrons originating in the bursts. In addition, a response log is obtained by irradiating the formation with a source of fast neutrons whereby the neutrons from this source are moderated in the formation to lower energy levels and are subject to absorption. Secondary radiation attendant to these lower energy neutrons is recorded in order to obtain a log representative of the response of the formation to moderation and absorption of the neutrons. The two logs thus obtained are correlated in order to determine a corrected value of uranium content of the formation. (author)

  2. Pulsed neutron measurement of single and two-phase liquid flow

    International Nuclear Information System (INIS)

    Kehler, P.

    1978-01-01

    Use of radioactive tracers for flow velocity measurements is well developed and documented. Measurement techniques involving pulsed sources of fast (14 MeV) neutrons for in-situ production of tracers can be considered as extensions of the old methods. Improvements offered by these Pulsed Neutron Activation (PNA) techniques over conventional radioisotope techniques are (1) non-intrusion into the system, (2) easier introduction and better mixing of the tracer, and (3) no requirement to handle large amounts of relatively long lived radioactive materials. Just as in conventional tracer techniques, flow velocity measurements by PNA methods can be based on the transit-time or the total-count method. A very significant difference of the PNA technique from conventional methods is that the induced activity is proportional to the density of the fluid, and that PNA techniques can be used for density measurements (of two-phase flows) in addition to flow velocity measurement. Original equations were derived that relate experimental data to the mass flow velocity and the average density. The accuracy of these equations is not effected by the flow regime. Experimental results are presented for tests performed on liquid sodium loops, on air--water loops, on the EBR-II reactor and on the LOFT reactor. Current instrumentation development programs (detectors, pulsed neutron sources) are discussed

  3. Improved fission neutron energy discrimination with {sup 4}He detectors through pulse filtering

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Ting, E-mail: ting.zhu@ufl.edu [University of Florida, Gainesville, FL (United States); Liang, Yinong; Rolison, Lucas; Barker, Cathleen; Lewis, Jason; Gokhale, Sasmit [University of Florida, Gainesville, FL (United States); Chandra, Rico [Arktis Radiation Detectors Ltd., Räffelstrasse 11, Zürich (Switzerland); Kiff, Scott [Sandia National Laboratories, CA (United States); Chung, Heejun [Korean Institute for Nuclear Nonproliferation and Control, 1534 Yuseong-daero, Yuseong-gu, Daejeon (Korea, Republic of); Ray, Heather; Baciak, James E.; Enqvist, Andreas; Jordan, Kelly A. [University of Florida, Gainesville, FL (United States)

    2017-03-11

    This paper presents experimental and computational techniques implemented for {sup 4}He gas scintillation detectors for induced fission neutron detection. Fission neutrons are produced when natural uranium samples are actively interrogated by 2.45 MeV deuterium-deuterium fusion reaction neutrons. Fission neutrons of energies greater than 2.45 MeV can be distinguished by their different scintillation pulse height spectra since {sup 4}He detectors retain incident fast neutron energy information. To enable the preferential detection of fast neutrons up to 10 MeV and suppress low-energy event counts, the detector photomultiplier gain is lowered and trigger threshold is increased. Pile-up and other unreliable events due to the interrogating neutron flux and background radiation are filtered out prior to the evaluation of pulse height spectra. With these problem-specific calibrations and data processing, the {sup 4}He detector's accuracy at discriminating fission neutrons up to 10 MeV is improved and verified with {sup 252}Cf spontaneous fission neutrons. Given the {sup 4}He detector's ability to differentiate fast neutron sources, this proof-of-concept active-interrogation measurement demonstrates the potential of special nuclear materials detection using a {sup 4}He fast neutron detection system.

  4. Baseline distortion effect on gamma-ray pulse-height spectra in neutron capture experiments

    International Nuclear Information System (INIS)

    Laptev, A.; Harada, H.; Nakamura, S.; Hori, J.; Igashira, M.; Ohsaki, T.; Ohgama, K.

    2005-01-01

    A baseline distortion effect due to gamma-flash at neutron time-of-flight measurement using a pulse neutron source has been investigated. Pulses from C 6 D 6 detectors accumulated by flash-ADC were processed with both standard analog-to-digital converter (ADC) and flash-ADC operational modes. A correction factor of gamma-ray yields, due to baseline shift, was quantitatively obtained by comparing the pulse height spectra of the two data-taking modes. The magnitude of the correction factor depends on the time after gamma-flash and has complex time dependence with a changing sign

  5. Development of time projection chamber for precise neutron lifetime measurement using pulsed cold neutron beams

    Energy Technology Data Exchange (ETDEWEB)

    Arimoto, Y. [High Energy Accelerator Research Organization, Ibaraki (Japan); Higashi, N. [Graduate School of Science, University of Tokyo, Tokyo (Japan); Igarashi, Y. [High Energy Accelerator Research Organization, Ibaraki (Japan); Iwashita, Y. [Institute for Chemical Research, Kyoto University, Kyoto (Japan); Ino, T. [High Energy Accelerator Research Organization, Ibaraki (Japan); Katayama, R. [Graduate School of Science, University of Tokyo, Tokyo (Japan); Kitaguchi, M. [Kobayashi-Maskawa Institute, Nagoya University, Aichi (Japan); Kitahara, R. [Graduate School of Science, Kyoto University, Kyoto (Japan); Matsumura, H.; Mishima, K. [High Energy Accelerator Research Organization, Ibaraki (Japan); Nagakura, N.; Oide, H. [Graduate School of Science, University of Tokyo, Tokyo (Japan); Otono, H., E-mail: otono@phys.kyushu-u.ac.jp [Research Centre for Advanced Particle Physics, Kyushu University, Fukuoka (Japan); Sakakibara, R. [Department of Physics, Nagoya University, Aichi (Japan); Shima, T. [Research Center for Nuclear Physics, Osaka University, Osaka (Japan); Shimizu, H.M.; Sugino, T. [Department of Physics, Nagoya University, Aichi (Japan); Sumi, N. [Faculty of Sciences, Kyushu University, Fukuoka (Japan); Sumino, H. [Department of Basic Science, University of Tokyo, Tokyo (Japan); Taketani, K. [High Energy Accelerator Research Organization, Ibaraki (Japan); and others

    2015-11-01

    A new time projection chamber (TPC) was developed for neutron lifetime measurement using a pulsed cold neutron spallation source at the Japan Proton Accelerator Research Complex (J-PARC). Managing considerable background events from natural sources and the beam radioactivity is a challenging aspect of this measurement. To overcome this problem, the developed TPC has unprecedented features such as the use of polyether-ether-ketone plates in the support structure and internal surfaces covered with {sup 6}Li-enriched tiles to absorb outlier neutrons. In this paper, the design and performance of the new TPC are reported in detail.

  6. Pulsed neutron source cold moderators --- concepts, design and engineering

    International Nuclear Information System (INIS)

    Bauer, Guenter S.

    1997-01-01

    Moderator design for pulsed neutron sources is becoming more and more an interface area between source designers and instrument designers. Although there exists a high degree of flexibility, there are also physical and technical limitations. This paper aims at pointing out these limitations and examining ways to extend the current state of moderator technology in order to make the next generation neutron sources even more versatile and flexible tools for science in accordance with the users' requirements. (auth)

  7. Structure analysis of liquids and disordered materials using pulsed neutron diffraction and total scattering

    International Nuclear Information System (INIS)

    Suzuya, Kentaro

    2011-01-01

    Neutron diffraction·total scattering at pulsed neutron source is a powerful method to analyze the complex structure of disordered materials: liquids, glasses, amorphous materials and disordered crystals. The basic idea of the structure of disordered materials, the fundamental diffraction theory for disordered materials, and structure analysis of disordered materials using pulsed neutron diffraction·total scattering technique (TOF method) are described in detail. In addition, the precise information of the world highest class J-PARC MLF spallation neutron source and typical J-PARC neutron total scattering instrument NOVA are also given. Recent structural modelling methods of disordered materials such like reverse Monte Carlo (RMC) simulation method is briefly described using an example of the analysis of a typical disordered material silica glass. (author)

  8. Use of a pulsed neutron generator for in vivo measurement of body carbon

    International Nuclear Information System (INIS)

    Kehayias, J.J.; Ellis, K.J.; Cohn, S.H.; Yasumura, S.

    1986-01-01

    The measurement of total body fat is of importance in studies of nutritional assessment, dietary regimens, and for the management of obesity. In the past, fat has been determined either by anthropometric methods, which introduce high uncertainties, or by model-dependent estimation of fat-free tissue. The validity, however, of the different models in disease is questionable. Total body carbon measurements provide a more direct evaluation of body fat both in normal subjects and in patients. The authors present here a facility for carbon measurements without the use of a major accelerator. The same facility can be used for the measurement of other major body elements and for the evaluation of the body's compartments. Carbon is measured in vivo through neutron inelastic scattering, by detecting the 4.44 MeV gamma rays. A miniature (10 cm long) 14 MeV D-T neutron generator is used. The short half-life of the 4.44 MeV state of carbon requires detection of the gamma rays simultaneously with the 10 μs neutron pulse. Generators with low pulsing rate were found inappropriate for carbon measurement because of their low duty-cycle (high neutron output during pulse). The detection system consists of NaI(T1) detectors and fast electronics for handling the high even rate during the neutron pulse. A description of the facility and an evaluation of the technique will be presented

  9. Pulsed neutron method for diffusion, slowing down, and reactivity measurements

    International Nuclear Information System (INIS)

    Sjoestrand, N.G.

    1985-01-01

    An outline is given on the principles of the pulsed neutron method for the determination of thermal neutron diffusion parameters, for slowing-down time measurements, and for reactivity determinations. The historical development is sketched from the breakthrough in the middle of the nineteen fifties and the usefulness and limitations of the method are discussed. The importance for the present understanding of neutron slowing-down, thermalization and diffusion are point out. Examples are given of its recent use for e.g. absorption cross section measurements and for the study of the properties of heterogeneous systems

  10. 5 MW pulsed spallation neutron source, Preconceptual design study

    Energy Technology Data Exchange (ETDEWEB)

    1994-06-01

    This report describes a self-consistent base line design for a 5 MW Pulsed Spallation Neutron Source (PSNS). It is intended to establish feasibility of design and as a basis for further expanded and detailed studies. It may also serve as a basis for establishing project cost (30% accuracy) in order to intercompare competing designs for a PSNS not only on the basis of technical feasibility and technical merit but also on the basis of projected total cost. The accelerator design considered here is based on the objective of a pulsed neutron source obtained by means of a pulsed proton beam with average beam power of 5 MW, in {approx} 1 {mu}sec pulses, operating at a repetition rate of 60 Hz. Two target stations are incorporated in the basic facility: one for operation at 10 Hz for long-wavelength instruments, and one operating at 50 Hz for instruments utilizing thermal neutrons. The design approach for the proton accelerator is to use a low energy linear accelerator (at 0.6 GeV), operating at 60 Hz, in tandem with two fast cycling booster synchrotrons (at 3.6 GeV), operating at 30 Hz. It is assumed here that considerations of cost and overall system reliability may favor the present design approach over the alternative approach pursued elsewhere, whereby use is made of a high energy linear accelerator in conjunction with a dc accumulation ring. With the knowledge that this alternative design is under active development, it was deliberately decided to favor here the low energy linac-fast cycling booster approach. Clearly, the present design, as developed here, must be carried to the full conceptual design stage in order to facilitate a meaningful technology and cost comparison with alternative designs.

  11. 5 MW pulsed spallation neutron source, Preconceptual design study

    International Nuclear Information System (INIS)

    1994-06-01

    This report describes a self-consistent base line design for a 5 MW Pulsed Spallation Neutron Source (PSNS). It is intended to establish feasibility of design and as a basis for further expanded and detailed studies. It may also serve as a basis for establishing project cost (30% accuracy) in order to intercompare competing designs for a PSNS not only on the basis of technical feasibility and technical merit but also on the basis of projected total cost. The accelerator design considered here is based on the objective of a pulsed neutron source obtained by means of a pulsed proton beam with average beam power of 5 MW, in ∼ 1 μsec pulses, operating at a repetition rate of 60 Hz. Two target stations are incorporated in the basic facility: one for operation at 10 Hz for long-wavelength instruments, and one operating at 50 Hz for instruments utilizing thermal neutrons. The design approach for the proton accelerator is to use a low energy linear accelerator (at 0.6 GeV), operating at 60 Hz, in tandem with two fast cycling booster synchrotrons (at 3.6 GeV), operating at 30 Hz. It is assumed here that considerations of cost and overall system reliability may favor the present design approach over the alternative approach pursued elsewhere, whereby use is made of a high energy linear accelerator in conjunction with a dc accumulation ring. With the knowledge that this alternative design is under active development, it was deliberately decided to favor here the low energy linac-fast cycling booster approach. Clearly, the present design, as developed here, must be carried to the full conceptual design stage in order to facilitate a meaningful technology and cost comparison with alternative designs

  12. MCNP capabilities for nuclear well logging calculations

    International Nuclear Information System (INIS)

    Forster, R.A.; Little, R.C.; Briesmeister, J.F.; Hendricks, J.S.

    1990-01-01

    The Los Alamos Radiation Transport Code System (LARTCS) consists of state-of-the-art Monte Carlo and discrete ordinates transport codes and data libraries. This paper discusses how the general-purpose continuous-energy Monte Carlo code MCNP (Monte Carlo neutron photon), part of the LARTCS, provides a computational predictive capability for many applications of interest to the nuclear well logging community. The generalized three-dimensional geometry of MCNP is well suited for borehole-tool models. SABRINA, another component of the LARTCS, is a graphics code that can be used to interactively create a complex MCNP geometry. Users can define many source and tally characteristics with standard MCNP features. The time-dependent capability of the code is essential when modeling pulsed sources. Problems with neutrons, photons, and electrons as either single particle or coupled particles can be calculated with MCNP. The physics of neutron and photon transport and interactions is modeled in detail using the latest available cross-section data

  13. Pulsed neutron generators based on plasma focus devices of low energy

    International Nuclear Information System (INIS)

    Silva, Patricio; Moreno, Jose; Soto, Leopoldo

    2003-01-01

    The plasma focus is a pulsed neutron source especially suited for applications because it reduces the danger of contamination of conventional isotopic radioactive sources. As first stage of a program to design a repetitive pulsed neutron generator for industrial applications we constructed two very small plasma focus operating at an energy level of the order of a) tens of joules (PF-50J, 160nF capacitor bank, 20-35 kV, 32-100J, ∼150ns first quarter of period) and b) hundred of joules (PF-400J, 880nF, 20-35kV, 176-539J, ∼300ns first quarter of period). In this article we present results related to design and construction of these small plasma foci (PF-50J and PF-400J). Neutron yield vs. deuterium. pressure has been obtained, a maximum emission of the order of 7x10 4 and 10 6 neutrons per shot has been measured in the PF-50J and PF-400J respectively (author)

  14. CIAE 600 kV ns pulse neutron generator

    International Nuclear Information System (INIS)

    Shen Guanren; Guan Xialing; Chen Hongtao

    2001-01-01

    The overall composition of CIAE 600 kV ns Pulse Neutron Generator (CPNG) are introduced, and its characteristic, main technological performance and application were also given. CPNG consists of high voltage power supply with highest output voltage 600 kV, direct current 15 mA, stability and ripple ≤0.1%, 2214 mm x 1604 mm x 1504 mm stainless steel high voltage electrode, built in head equipment uniform field accelerating tube, ns pulsed installation, turbomolecular vacuum pump system and drift pipes at 0 degree and 45 degree. Its characteristics are: (1) high current beam; (2) high current beam ns pulsed installation made use of low energy for chopper and high energy for buncher; (3) compactly laid out and simple in structure

  15. Detection of pulsed fast neutrons by a proportional counter boron-convered and enveloped in paraffin moderators

    International Nuclear Information System (INIS)

    Goncalez, O.L.; Yanagihara, L.S.; Veissid, V.L.C.P.; Herdade, S.B.

    1983-01-01

    The response to pulsed fast neutrons by a parafin moderated boron-lined proportional counter is investigated theoretically and experimentally. The neutrons pulses are generated by 60 MeV electrons from a linear accelerator. The calculation of the counting loss based on the detector dead time and on the exponential decresse of the thermal neutron population in the moderator is presented in detail. An analytical relation between the true counting rate and the reduced one, indicated by the detector, is found. In this formula three parameters appear: the decay constant of the thermal neutron population, the detector dead time and the pulse frequency of the neutron source. The decay constant is calculated by diffusion theory. The experimental results for six values of moderator thickness (between 2.5 to 12.5 cm) agree with our theoretical calculation within 20 per cent. (Author) [pt

  16. The Dynamic Method for Time-of-Flight Measurement of Thermal Neutron Spectra from Pulsed Sources

    International Nuclear Information System (INIS)

    Pepelyshev, Yu.N.; Tulaev, A.B.; Bobrakov, V.F.

    1994-01-01

    The time-of-flight method for a measurement of thermal neutron spectra in the pulsed neutron sources with high efficiency of neutron registration, more than 10 5 times higher in comparison with traditional one, is described. The main problems connected with the electric current technique for time-of-flight spectra measurement are examined. The methodical errors, problems of a special neutron detector design and other questions are discussed. Some experimental results, spectra from surfaces of the water and solid methane moderators, obtained in the pulsed reactor IBR-2 (Dubna, Russia) are presented. 4 refs., 5 figs

  17. Gamma compensated pulsed ionization chamber wide range neutron/reactor power measurement system

    International Nuclear Information System (INIS)

    Ellis, W.H.

    1975-01-01

    An improved method and system of pulsed mode operation of ionization chambers is described in which a single sensor system with gamma compensation is provided by sampling, squaring, automatic gate selector, and differential amplifier circuit means, employed in relation to chambers sensitized to neutron plus gamma and gamma only to subtract out the gamma component, wherein squaring functions circuits, a supplemental high performance pulse rate system, and operational and display mode selection and sampling gate circuits are utilized to provide automatic wide range linear measurement capability for neutron flux and reactor power. Neon is employed as an additive in the ionization chambers to provide independence of ionized gas kinetics temperature effects, and the pulsed mode of operation provide independence of high temperature insulator leakage effects. (auth)

  18. Well logging. Acquisition and applications; Diagraphies. Acquisition et applications

    Energy Technology Data Exchange (ETDEWEB)

    Serra, O.; Serra, L.

    2001-07-01

    This reference book on wire-line and LWD well logging covers all geophysical methods of underground survey in a synthetic, visual and dynamical way. It treats of: the physical principle of well logging measurements, the different types of existing probes, the factors that can influence the measurements, and the applications of these measurements. The following well-logging methods are reviewed: resistivity; electromagnetic wave propagation; magnetic susceptibility and magnetic field; spontaneous potential; nuclear logging: natural gamma radioactivity, density logging, photoelectric index, neutron emission probes, hydrogen index or neutron porosity, neutron induced gamma spectroscopy, neutron relaxation time, NMR; acoustic measurements: sonic logging, seismic profiles; texture, structure and stratigraphy data acquisition; borehole diameter measurement; temperature measurement; wire sampling methods; place and role of well-logging in petroleum exploration; well-logging programs. (J.S.)

  19. Uranium logging in earth formations

    International Nuclear Information System (INIS)

    Givens, W.W.

    1979-01-01

    A technique is provided for assaying the formations surrounding a borehole for uranium. A borehole logging tool cyclically irradiates the formations with neutrons and responds to neutron fluxes produced during the period of time that prompt neutrons are being produced by the neutron fission of uranium in the formations. A borehole calibration tool employs a steady-state (continuous output) neutron source, firstly, to produce a response to neutron fluxes in models having known concentrations of uranium and, secondly, to to produce a response to neutron fluxes in the formations surrounding the borehole. The neutron flux responses of the borehole calibration tool in both the model and the formations surrounding the borehole are utilized to correct the neutron flux response of the borehole logging tool for the effects of epithermal/thermal neutron moderation, scattering, and absorption within the borehole itself

  20. Creative scientific research international session of 2nd meeting on advanced pulsed-neutron research on quantum functions in nano-scale materials

    International Nuclear Information System (INIS)

    Itoh, Shinichi

    2005-06-01

    1 MW-class pulsed-neutron sources will be constructed in Japan, United State and United Kingdom in a few years. Now is the time for a challenge to innovate on neutron science and extend new science fields. Toward the new era, we develop new pulsed-neutron technologies as well as new neutron devices under the international collaborations with existing pulsed-neutron facilities, such as the UK-Japan collaboration program on neutron scattering. At the same time, the new era will bring international competitions to neutron researchers. We aim to create new neutron science toward the new pulsed-neutron era by introducing the new technologies developed here. For this purpose, we have started the research project, 'Advanced pulsed-neutron research on quantum functions in nano-scale materials,' in the duration between JFY2004 and JFY2008. The 2nd meeting of this project was held on 22-24 February 2005 to summarize activities in FY2004 and to propose research projects in the coming new fiscal year. In this international session as a part of this meeting, the scientific results and research plans on the UK-Japan collaboration program, the research plans on the collaboration between IPNS (Intense Pulsed Neutron Source, Argonne National Laboratory) and KENS (Neutron Science Laboratory, KEK), also the recent scientific results arisen form this project were presented. (author)

  1. Impacts of Airborne Lidar Pulse Density on Estimating Biomass Stocks and Changes in a Selectively Logged Tropical Forest

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Silva

    2017-10-01

    Full Text Available Airborne lidar is a technology well-suited for mapping many forest attributes, including aboveground biomass (AGB stocks and changes in selective logging in tropical forests. However, trade-offs still exist between lidar pulse density and accuracy of AGB estimates. We assessed the impacts of lidar pulse density on the estimation of AGB stocks and changes using airborne lidar and field plot data in a selectively logged tropical forest located near Paragominas, Pará, Brazil. Field-derived AGB was computed at 85 square 50 × 50 m plots in 2014. Lidar data were acquired in 2012 and 2014, and for each dataset the pulse density was subsampled from its original density of 13.8 and 37.5 pulses·m−2 to lower densities of 12, 10, 8, 6, 4, 2, 0.8, 0.6, 0.4 and 0.2 pulses·m−2. For each pulse density dataset, a power-law model was developed to estimate AGB stocks from lidar-derived mean height and corresponding changes between the years 2012 and 2014. We found that AGB change estimates at the plot level were only slightly affected by pulse density. However, at the landscape level we observed differences in estimated AGB change of >20 Mg·ha−1 when pulse density decreased from 12 to 0.2 pulses·m−2. The effects of pulse density were more pronounced in areas of steep slope, especially when the digital terrain models (DTMs used in the lidar derived forest height were created from reduced pulse density data. In particular, when the DTM from high pulse density in 2014 was used to derive the forest height from both years, the effects on forest height and the estimated AGB stock and changes did not exceed 20 Mg·ha−1. The results suggest that AGB change can be monitored in selective logging in tropical forests with reasonable accuracy and low cost with low pulse density lidar surveys if a baseline high-quality DTM is available from at least one lidar survey. We recommend the results of this study to be considered in developing projects and national

  2. Detection of low caloric power of coal by pulse fast-thermal neutron analysis

    International Nuclear Information System (INIS)

    Gu De-shan; Sang Hai-feng; Qiao Shuang; Liu Yu-ren, Liu Lin-mao; Jing Shi-wei; Chinese Academy of Sciences, Changchun

    2004-01-01

    Analysis method and principle of pulse fast-thermal neutron analysis (PFTNA) are introduced. A system for the measurement of low caloric power of coal by PFTNA is also presented. The 14 MeV pulse neutron generator and BGO detector and 4096 MCA were applied in this system. A multiple linear regression method applied to the data solved the interferential problem of multiple elements. The error of low caloric power between chemical analysis and experiment was less than 0.4 MJ/kg. (author)

  3. Hidden explosives detector employing pulsed neutron and x-ray interrogation

    International Nuclear Information System (INIS)

    Schultz, F.J.; Caldwell, J.T.

    1993-01-01

    Methods and systems for the detection of small amounts of modern, highly-explosive nitrogen-based explosives, such as plastic explosives, hidden in airline baggage. Several techniques are employed either individually or combined in a hybrid system. One technique employed in combination is X-ray imaging. Another technique is interrogation with a pulsed neutron source in a two-phase mode of operation to image both nitrogen and oxygen densities. Another technique employed in combination is neutron interrogation to form a hydrogen density image or three-dimensional map. In addition, deliberately-placed neutron-absorbing materials can be detected

  4. Hidden explosives detector employing pulsed neutron and x-ray interrogation

    Science.gov (United States)

    Schultz, Frederick J.; Caldwell, John T.

    1993-01-01

    Methods and systems for the detection of small amounts of modern, highly-explosive nitrogen-based explosives, such as plastic explosives, hidden in airline baggage. Several techniques are employed either individually or combined in a hybrid system. One technique employed in combination is X-ray imaging. Another technique is interrogation with a pulsed neutron source in a two-phase mode of operation to image both nitrogen and oxygen densities. Another technique employed in combination is neutron interrogation to form a hydrogen density image or three-dimensional map. In addition, deliberately-placed neutron-absorbing materials can be detected.

  5. Plastic scintillator detector for pulsed flux measurements

    Science.gov (United States)

    Kadilin, V. V.; Kaplun, A. A.; Taraskin, A. A.

    2017-01-01

    A neutron detector, providing charged particle detection capability, has been designed. The main purpose of the detector is to measure pulsed fluxes of both charged particles and neutrons during scientific experiments. The detector consists of commonly used neutron-sensitive ZnS(Ag) / 6LiF scintillator screens wrapping a layer of polystyrene based scintillator (BC-454, EJ-254 or equivalent boron loaded plastic). This type of detector design is able to log a spatial distribution of events and may be scaled to any size. Different variations of the design were considered and modelled in specialized toolkits. The article presents a review of the detector design features as well as simulation results.

  6. The use of multi-energy-group neutron diffusion theory to numerically evaluate the relative utility of three dial-detector neutron porosity well logging tools

    International Nuclear Information System (INIS)

    Zalan, T.A.

    1988-01-01

    Multi-energy-group neutron diffusion theory is used to numerically evaluate the utility of two different dual-detector neutron porosity logging devices, a 14 MeV (accelerator) neutron source - epithermal neutron detector device and a 4 MeV neutron source - capture gamma-ray detector device, relative to the traditional 4 MeV neutron source - thermal neutron detector device. Fast and epithermal neutron diffusion parameters are calculated using Monte Carlo - derived neutron flux distributions. Thermal parameters are calculated from tabulated cross sections. An existing analytical method to describe the transport of gamma-rays through common earth materials is modified in order to accommodate the modeling of the 4 MeV neutron - capture gamma-ray device. The 14 MeV neutron - epithermal neutron device is found to be less sensitive to porosity than the 4 MeV neutron - capture gamma-ray device, which in turn is found to be less sensitive to porosity than the traditional 4 MeV neutron - thermal neutron device. Salinity effects are found to be comparable for the 4 MeV neutron - capture gamma-ray and 4 MeV neutron - thermal neutron devices. The 4 MeV neutron capture gamma-ray measurement is found to be deepest investigating

  7. The dynamic method for time-of-flight measurement of thermal neutron spectra from pulsed sources

    International Nuclear Information System (INIS)

    Pepyolyshev, Yu.N.; Chuklyaev, S.V.; Tulaev, A.B.; Bobrakov, V.F.

    1995-01-01

    A time-of-flight method for measurement of thermal neutron spectra in pulsed neutron sources with an efficiency more than 10 5 times higher than the standard method is described. The main problems associated with the electric current technique for time-of-flight spectra measurement are examined. The methodical errors, problems of special neutron detector design and other questions are discussed. Some experimental results for spectra from the surfaces of water and solid methane moderators obtained at the IBR-2 pulsed reactor (Dubna, Russia) are presented. (orig.)

  8. Pulsed-neutron production at the Brookhaven 200-MeV linac

    International Nuclear Information System (INIS)

    Ward, T.E.; Alessi, J.; Brennan, J.; Grand, P.; Lankshear, R.; Montemurro, P.; Snead, C.L. Jr.; Tsoupas, N.

    1988-01-01

    The new 750-kV RFQ preinjector and double chopper system capable of selecting single nanosecond micropulses with repetition rates of 0.1--20 MHz has been installed at the Brookhaven 200-MeV proton linac. The micropulse intensity is approximately 1 x 10 9 p/μpulse. Neutron time-of-flight path lengths of 30--100 meter at 0/degree/, 12/degree/, 30/degree/, 45/degree/, 90/degree/ and 135/degree/ are available, as well as a zero degree swinger capable of an angular range of 0--25/degree/. Pulsed neutron beams of monoenergetic (p 7 Li → n 7 Be) and spallation (p 238 U → nx) sources will be discussed in the present paper, as well as detailing the chopped-beam capabilities. 11 refs., 5 figs., 1 tab

  9. Ion source development for uranium-logging neutron tube

    International Nuclear Information System (INIS)

    Bacon, F.M.; O'Hagan, J.B.

    1977-03-01

    Ion beam current and mass distributions have been measured for a Penning-type ion source in a uranium-logging neutron tube. For a discharge current of 1 A and gas pressure of 1.3 Pa, the beam current was about 65 mA and the mass distribution was 5 percent D + , 80 percent D 2 + , and 15 percent D 3 + . A demountable version of this source was built to determine how geometry changes could affect the ion beam current and mass distribution. A factor of three increase in beam current was achieved by decreasing the depth of the plasma expansion cup to zero. The only method by which the mass distribution was significantly modified was by dissociating the gas in the source with a hot tungsten filament. Atomic percentage was increased to 40 percent with a filament at about 3000 K

  10. Utilization of the intense pulsed neutron source (IPNS) at Argonne National Laboratory for neutron activation analysis

    International Nuclear Information System (INIS)

    Heinrich, R.R.; Greenwood, L.R.; Popek, R.J.; Schulke, A.W. Jr.

    1983-01-01

    The Intense Pulsed Neutron Source (IPNS) neutron scattering facility (NSF) has been investigated for its applicability to neutron activation analysis. A polyethylene insert has been added to the vertical hole VT3 which enhances the thermal neutron flux by a factor of two. The neutron spectral distribution at this position has been measured by the multiple-foil technique which utilized 28 activation reactions and the STAYSL computer code. The validity of this spectral measurement was tested by two irradiations of National Bureau of Standards SRM-1571 (orchard leaves), SRM-1575 (pine needles), and SRM-1645 (river sediment). The average thermal neutron flux for these irradiations normalized to 10 μamp proton beam is 4.0 x 10 11 n/cm 2 -s. Concentrations of nine trace elements in each of these SRMs have been determined by gamma-ray spectrometry. Agreement of measured values to certified values is demonstrated to be within experiment error

  11. Biological effectiveness of pulsed and continuous neutron radiation for cells of yeast Saccharomyces

    International Nuclear Information System (INIS)

    Tsyb, T.S.; Komarova, E.V.; Potetnya, V.I.; Obaturov, G.M.

    2001-01-01

    Data are presented on biological effectiveness of fast neutrons generated by BR-10 reactor (dose rate up to 3.8 Gy/s) in comparison with neutrons of pulsed BARS-6 reactor (dose rate ∼6x10 6 Gy/s) for yeast Saccharomyces vini cells of a wild type Menri 139-B and radiosensitive Saccharomyces cerevisiae (rad52/rad52; rad54/rad54) mutants which are defective over different systems of DNA reparation. Value of relative biological efficiency (RBE) of continuous radiation for wild stam is from 3.5 up to 2.5 when survival level being 75-10 %, and RBE of pulsed neutron radiation is in the limits of 2.0-1.7 at the same levels. For mutant stam the value of RBE (1.4-1.6) of neutrons is constant at all survival levels and does not depend on dose rate [ru

  12. On-line analysis of bulk materials using pulsed neutron interrogation

    International Nuclear Information System (INIS)

    Lebrun, P.; Tourneur, P. Le; Poumarede, B.; Bach, P.; Moeller, H.

    1999-01-01

    On the basis of our joint experience in neutronics for SODERN and in cement plant engineering for KRUPP POLYSIUS, we have developed a new on-line bulk materials analyser for the cement industry. This equipment includes a pulsed neutron generator GENIE 16, some gamma ray and neutron detectors, specially designed electronics with high counting rate, software delivering the mean elemental composition of raw material, and adequate shielding. This material is transported through the equipment on a conveyor belt, the size of which is adapted to the requirements. This paper briefly describes the equipment and some results, as obtained in dynamic test from a demonstrator installed in Germany

  13. On-line analysis of bulk materials using pulsed neutron interrogation

    Science.gov (United States)

    Lebrun, P.; Tourneur, P. Le; Poumarede, B.; Möller, H.; Bach, P.

    1999-06-01

    On the basis of our joint experience in neutronics for SODERN and in cement plant engineering for KRUPP POLYSIUS, we have developed a new on-line bulk materials analyser for the cement industry. This equipment includes a pulsed neutron generator GENIE 16, some gamma ray and neutron detectors, specially designed electronics with high counting rate, software delivering the mean elemental composition of raw material, and adequate shielding. This material is transported through the equipment on a conveyor belt, the size of which is adapted to the requirements. This paper briefly describes the equipment and some results, as obtained in dynamic test from a demonstrator installed in Germany.

  14. Intensive neutron source based on powerful electron linear accelerator LIA-30 and pulsed nuclear reactor FR-1

    Energy Technology Data Exchange (ETDEWEB)

    Bossamykin, V S; Koshelev, A S; Gerasimov, A I; Gordeev, V S; Grishin, A V; Averchenkov, V Ya; Lazarev, S A; Maslov, G N; Odintsov, Yu M [All-Russian Scientific Research Institute of Experimental Physics, Sarov (Russian Federation)

    1997-12-31

    Some results are given of investigations on joint operation modes of the linear induction electron accelerator LIA-30 ({approx} 40 MeV, {approx} 100 kA, {approx} 20 ns) and the pulsed reactor FR-1 with a compact metal core, aimed at achieving high intensity neutron fluxes. The multiplication factor Q for prompt neutrons in the FR-1 booster mode operation increased from 100 to 4500. The total output of prompt neutrons from FR-1 at Q = 2570 was 1.4 x 10{sup 16} 1/pulse with a pulse half width of {approx} 25 {mu}s. (author). 4 figs., 4 refs.

  15. Analysis of the neutron flux in an annular pulsed reactor by using finite volume method

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Mário A.B. da; Narain, Rajendra; Bezerra, Jair de L., E-mail: mabs500@gmail.com, E-mail: narain@ufpe.br, E-mail: jairbezerra@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Centro de Tecnologia e Geociências. Departamento de Energia Nuclear

    2017-07-01

    Production of very intense neutron sources is important for basic nuclear physics and for material testing and isotope production. Nuclear reactors have been used as sources of intense neutron fluxes, although the achievement of such levels is limited by the inability to remove fission heat. Periodic pulsed reactors provide very intense fluxes by a rotating modulator near a subcritical core. A concept for the production of very intense neutron fluxes that combines features of periodic pulsed reactors and steady state reactors was proposed by Narain (1997). Such a concept is known as Very Intense Continuous High Flux Pulsed Reactor (VICHFPR) and was analyzed by using diffusion equation with moving boundary conditions and Finite Difference Method with Crank-Nicolson formalism. This research aims to analyze the flux distribution in the Very Intense Continuous Flux High Pulsed Reactor (VICHFPR) by using the Finite Volume Method and compares its results with those obtained by the previous computational method. (author)

  16. Analysis of the neutron flux in an annular pulsed reactor by using finite volume method

    International Nuclear Information System (INIS)

    Silva, Mário A.B. da; Narain, Rajendra; Bezerra, Jair de L.

    2017-01-01

    Production of very intense neutron sources is important for basic nuclear physics and for material testing and isotope production. Nuclear reactors have been used as sources of intense neutron fluxes, although the achievement of such levels is limited by the inability to remove fission heat. Periodic pulsed reactors provide very intense fluxes by a rotating modulator near a subcritical core. A concept for the production of very intense neutron fluxes that combines features of periodic pulsed reactors and steady state reactors was proposed by Narain (1997). Such a concept is known as Very Intense Continuous High Flux Pulsed Reactor (VICHFPR) and was analyzed by using diffusion equation with moving boundary conditions and Finite Difference Method with Crank-Nicolson formalism. This research aims to analyze the flux distribution in the Very Intense Continuous Flux High Pulsed Reactor (VICHFPR) by using the Finite Volume Method and compares its results with those obtained by the previous computational method. (author)

  17. Method and apparatus for producing a porosity log of a subsurface formation corrected for detector standoff

    International Nuclear Information System (INIS)

    Allen, L.S.; Leland, F.P.; Lyle, W.D. Jr.; Stromswold, D.C.

    1993-01-01

    A borehole logging tool with a pulsed source of fast neutrons is lowered into a borehole traversing a subsurface formation, and a neutron detector measures the die-away of nuclear radiation in the formation. A model of the die-away is produced using exponential terms varying as the sum of borehole, formation and thermal neutron background components. Exponentially weighted moments of both the die-away measurements and a model are determined and equated. The formation decay constant is determined from the formation and thermal neutron background. An epithermal neutron lifetime is determined from the formation decay constant and is used with the amplitude ratio by a trained neural network to determine a lifetime correction. A standoff corrected lifetime is determined from the epithermal neutron lifetime and the lifetime correction. (author)

  18. Pulsed-neutron production at the Brookhaven 200-MeV linac

    International Nuclear Information System (INIS)

    Ward, T.E.; Alessi, J.; Brennan, J.; Grand, P.; Lankshear, R.; Montemurro, P.; Snead, C.L. Jr.; Tsoupas, N.

    1989-01-01

    The new 750-kV RFQ preinjector and double chopper system capable of selecting single nanosecond micropulses with repetition rates of 0.1 to 20 MHz has been installed at the Brookhaven 200-MeV proton linac. The micropulse intensity is approximately 1 x 10 9 p/μpulse. Neutron time-of-flight path lengths of 30 to 100 meters at 0 degree, 12 degree, 30 degree, 45 degree, 90 degree and 135 degree are available as well as a zero-degree beam swinger capable of an angular range of 0 degree to 25 degree. Pulsed neutron beams of monoenergetic (p 7 Li → n 7 Be) and spallation (p 238 U → nx) sources will be discussed in the present paper as well as detailing the chopped-beam capabilities. 11 refs., 5 figs., 1 tab

  19. Intensity enhancement of cold neutrons from a coupled liquid-hydrogen moderator for pulsed cold neutron sources

    International Nuclear Information System (INIS)

    Ogawa, Y.; Kiyanagi, Y.; Kosugi, N.; Iwasa, H.; Furusaka, M.; Watanabe, N.

    1999-01-01

    In order to obtain higher cold neutron intensity from a coupled liquid-hydrogen moderator with a premoderator for pulsed cold neutron sources, we examined a partial enhancement method, namely, narrow beam extraction for both a flat liquid-hydrogen moderator and a single-groove one. Combined with the narrow beam extraction, which is especially suitable for small-angle scattering and neutron reflectometry experiments, a single-groove moderator provides higher intensity, by about 30%, than a flat-surface moderator at the region of interest on a viewed surface. The effect of double-side beam extraction from such moderators on the intensity gain factor is also discussed. (author)

  20. Pulsed Operation of a Compact Fusion Neutron Source Using a High-Voltage Pulse Generator Developed for Landmine Detection

    International Nuclear Information System (INIS)

    Yamauchi, Kunihito; Watanabe, Masato; Okino, Akitoshi; Kohno, Toshiyuki; Hotta, Eiki; Yuura, Morimasa

    2005-01-01

    Preliminary experimental results of pulsed neutron source based on a discharge-type beam fusion called Inertial Electrostatic Confinement Fusion (IECF) for landmine detection are presented. In Japan, a research and development project for constructing an advanced anti-personnel landmine detection system by using IECF, which is effective not only for metal landmines but also for plastic ones, is now in progress. This project consists of some R and D topics, and one of them is R and D of a high-voltage pulse generator system specialized for landmine detection, which can be used in the severe environment such as that in the field in Afghanistan. Thus a prototype of the system for landmine detection was designed and fabricated in consideration of compactness, lightness, cooling performance, dustproof and robustness. By using this prototype pulse generator system, a conventional IECF device was operated as a preliminary experiment. As a result, it was confirmed that the suggested pulse generator system is suitable for landmine detection system, and the results follow the empirical law obtained by the previous experiments. The maximum neutron production rate of 2.0x10 8 n/s was obtained at a pulsed discharge of -51 kV, 7.3 A

  1. Decay of the pulsed thermal neutron flux in two-zone hydrogenous systems - Monte Carlo simulations using MCNP standard data libraries

    International Nuclear Information System (INIS)

    Wiacek, Urszula; Krynicka, Ewa

    2006-01-01

    Pulsed neutron experiments in two-zone spherical and cylindrical geometry has been simulated using the MCNP code. The systems are built of hydrogenous materials. The inner zone is filled with aqueous solutions of absorbers (H 3 BO 3 or KCl). It is surrounded by the outer zone built of Plexiglas. The system is irradiated with the pulsed thermal neutron flux and the thermal neutron decay in time is observed. Standard data libraries of the thermal neutron scattering cross-sections of hydrogen in hydrogenous substances have been used to simulate the neutron transport. The time decay constant of the fundamental mode of the thermal neutron flux determined in each simulation has been compared with the corresponding result of the real pulsed neutron experiment

  2. EJ-309 pulse shape discrimination performance with a high gamma-ray-to-neutron ratio and low threshold

    Energy Technology Data Exchange (ETDEWEB)

    Kaplan, A.C., E-mail: Alexis.C.Kaplan@gmail.com [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Blvd., Ann Arbor, MI 48104 (United States); Nuclear Engineering and Nonproliferation Division, Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Flaska, M.; Enqvist, A.; Dolan, J.L.; Pozzi, S.A. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Blvd., Ann Arbor, MI 48104 (United States)

    2013-11-21

    Measuring neutrons in the presence of high gamma-ray fluence is a challenge with multi-particle detectors. Organic liquid scintillators such as the EJ-309 are capable of accurate pulse-shape discrimination (PSD) but the chance for particle misclassification is not negligible for some applications. By varying the distance from an EJ-309 scintillator to a strong-gamma-ray source and keeping a weak-neutron source at a fixed position, various gamma-to-neutron ratios can be measured and PSD performance can be quantified. Comparing neutron pulse-height distributions allows for pulse-height specific PSD evaluation, and quantification and visualization of deviation from {sup 252}Cf alone. Even with the addition of the misclassified gamma-rays, the PSD is effective in separating particles so that neutron count rate can be predicted with less than 10% error up to a gamma-to-neutron ratio of almost 650. For applications which can afford a reduction in neutron detection efficiency, PSD can be sufficiently effective in discriminating particles to measure a weak neutron source in a high gamma-ray background. -- Highlights: •We measure neutrons in a high photon background with EJ-309 liquid scintillators. •A low threshold is used to test the limits of particle discrimination. •A weak neutron signal is detectable with a gamma/neutron ratio as high as 770. •Photon pileup most commonly adds to error in classification of neutrons. •Neutron count rates are within 10% of expected rate under high gamma background.

  3. EJ-309 pulse shape discrimination performance with a high gamma-ray-to-neutron ratio and low threshold

    International Nuclear Information System (INIS)

    Kaplan, A.C.; Flaska, M.; Enqvist, A.; Dolan, J.L.; Pozzi, S.A.

    2013-01-01

    Measuring neutrons in the presence of high gamma-ray fluence is a challenge with multi-particle detectors. Organic liquid scintillators such as the EJ-309 are capable of accurate pulse-shape discrimination (PSD) but the chance for particle misclassification is not negligible for some applications. By varying the distance from an EJ-309 scintillator to a strong-gamma-ray source and keeping a weak-neutron source at a fixed position, various gamma-to-neutron ratios can be measured and PSD performance can be quantified. Comparing neutron pulse-height distributions allows for pulse-height specific PSD evaluation, and quantification and visualization of deviation from 252 Cf alone. Even with the addition of the misclassified gamma-rays, the PSD is effective in separating particles so that neutron count rate can be predicted with less than 10% error up to a gamma-to-neutron ratio of almost 650. For applications which can afford a reduction in neutron detection efficiency, PSD can be sufficiently effective in discriminating particles to measure a weak neutron source in a high gamma-ray background. -- Highlights: •We measure neutrons in a high photon background with EJ-309 liquid scintillators. •A low threshold is used to test the limits of particle discrimination. •A weak neutron signal is detectable with a gamma/neutron ratio as high as 770. •Photon pileup most commonly adds to error in classification of neutrons. •Neutron count rates are within 10% of expected rate under high gamma background

  4. Measurement of angular distribution of neutron flux for the 6 MeV race-track microtron based pulsed neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Patil, B.J., E-mail: bjp@physics.unipune.ernet.i [Department of Physics, University of Pune, Pune 411 007 (India); Chavan, S.T.; Pethe, S.N.; Krishnan, R. [SAMEER, IIT Powai Campus, Mumbai 400 076 (India); Dhole, S.D., E-mail: sanjay@physics.unipune.ernet.i [Department of Physics, University of Pune, Pune 411 007 (India)

    2010-09-15

    The 6 MeV race track microtron based pulsed neutron source has been designed specifically for the elemental analysis of short lived activation products, where the low neutron flux requirement is desirable. Electrons impinges on a e-{gamma} target to generate bremsstrahlung radiations, which further produces neutrons by photonuclear reaction in {gamma}-n target. The optimisation of these targets along with their spectra were estimated using FLUKA code. The measurement of neutron flux was carried out by activation of vanadium at different scattering angles. Angular distribution of neutron flux indicates that the flux decreases with increase in the angle and are in good agreement with the FLUKA simulation.

  5. Plastic scintillator detector for pulsed flux measurements

    International Nuclear Information System (INIS)

    Kadilin, V V; Kaplun, A A; Taraskin, A A

    2017-01-01

    A neutron detector, providing charged particle detection capability, has been designed. The main purpose of the detector is to measure pulsed fluxes of both charged particles and neutrons during scientific experiments. The detector consists of commonly used neutron-sensitive ZnS(Ag) / 6 LiF scintillator screens wrapping a layer of polystyrene based scintillator (BC-454, EJ-254 or equivalent boron loaded plastic). This type of detector design is able to log a spatial distribution of events and may be scaled to any size. Different variations of the design were considered and modelled in specialized toolkits. The article presents a review of the detector design features as well as simulation results. (paper)

  6. Research on determine the absolute neutron output of distributed pulse generators

    International Nuclear Information System (INIS)

    Li Bojun; Tang Zhangkui; Wang Dong; Yang Gaozhao; Peng Taiping

    2009-01-01

    In order to determine the absolute neutron output of distributed pulse generators, we deduced equivalent length to deal with experimental data, according to the different layout and weighting of multiple pulse generators. The deposited energy in scintillation crystal and the integral flux which drilling through crystal interface was simulated by MCNP code. The result shows the simulated proportion of different distributed pulse generators is approximately agreed with experimental data. The validity of the equivalent length model was proved by the consistent results between calculation and experimental data. (authors)

  7. Method of assaying uranium with prompt fission and thermal neutron borehole logging adjusted by borehole physical characteristics

    International Nuclear Information System (INIS)

    Barnard, R.W.; Jensen, D.H.

    1982-01-01

    Uranium formations are assayed by prompt fission neutron logging techniques. The uranium in the formation is proportional to the ratio of epithermal counts to thermal or eqithermal dieaway. Various calibration factors enhance the accuracy of the measurement

  8. Storage of cold and thermal neutrons with perfect crystals at the pulsed source

    International Nuclear Information System (INIS)

    Jericha, E.

    1996-12-01

    The possibility of storing cold neutrons by sequential Bragg reflections between two parallel perfect crystal plates in backscattering geometry has been implemented as the parasitic instrument VESTA at the pulsed neutron source ISIS. Filling the neutrons into and releasing them from the storage cavity is accomplished by applying a short-pulsed magnetic field at the crystal plates. The method takes advantage of the conservation of the axial component of the neutron wave vector after Bragg reflection and its Zeeman shift in a magnetic field. The setup at ISIS is presented where a monochromatic neutron beam with wavelength 6.27 A and 2.9 x 10 4 n/scm 2 flux is taken out of the neutron guide leading to the IRIS backscattering spectrometer by a pyrolytic graphite crystal monochromator. The longest storage period obtained with the setup was 2.655 s which corresponds to 1574 consecutive Bragg reflections and a distance traveled of 1675 n. The measurements are analyzed by heuristic methods developed for neutron storage experiments. The apparatus is seen as a passive resonator system and characteristics like stored neutron intensity, the efficiency of the storage process, the probability to remain in the system, the mirror reflectivity, the dispersion of the stored distribution, the penetration depth of a neutron into a crystal mirror and the figure of merit of the resonator system are discussed. Monte Carlo simulations of the extracted beam and of the stored neutron distribution were performed to deepen the understanding of the experimental results. (author)

  9. Conceptual moderator studies for the Spallation Neutron Source short-pulse second target station

    Energy Technology Data Exchange (ETDEWEB)

    Gallmeier, F. X., E-mail: gallmeierfz@ornl.gov; Lu, W.; Riemer, B. W.; Zhao, J. K.; Herwig, K. W.; Robertson, J. L. [Instrument and Source Division, Oak Ridge National Laboratory, P.O. Box 2008, MS6466, Oak Ridge, Tennessee 37831 (United States)

    2016-06-15

    Candidate moderator configurations for a short-pulse second target station (STS) at the Oak Ridge National Laboratory Spallation Neutron Source (SNS) have been identified using a global optimizer framework built around the MCNPX particle transport code. Neutron brightness metrics were selected as the figure-of-merit. We assumed that STS would use one out of six proton pulses produced by an SNS accelerator upgraded to operate at 1.3 GeV proton energy, 2.8 MW power and 60 Hz repetition rate. The simulations indicate that the peak brightness can be increased by a factor of 5 and 2.5 on a per proton pulse basis compared to the SNS first target station for both coupled and decoupled para-hydrogen moderators, respectively. Additional increases by factors of 3 and 2 were demonstrated for coupled and decoupled moderators, respectively, by reducing the area of neutron emission from 100 × 100 mm{sup 2} to 20 × 20 mm{sup 2}. This increase in brightness has the potential to translate to an increase of beam intensity at the instruments’ sample positions even though the total neutron emission of the smaller moderator is less than that of the larger. This is especially true for instruments with small samples (beam dimensions). The increased fluxes in the STS moderators come at accelerated poison and de-coupler burnout and higher radiation-induced material damage rates per unit power, which overall translate into lower moderator lifetimes. A first effort was undertaken to group decoupled moderators into a cluster collectively positioning them at the peak neutron production zone in the target and having a three-port neutron emission scheme that complements that of a cylindrical coupled moderator.

  10. The current situation and prospect of fundamental research about nuclear logging technology

    International Nuclear Information System (INIS)

    Zhang Feng; Wang Xinguang; Yuan Chao

    2010-01-01

    Nuclear logging technology is one of the important methods to evaluate complex hydrocarbon reservoir in the process of petroleum exploration and development. The fundamental research of nuclear logging is an important step of logging technology innovation. Through analyzing the current situation of the development of nuclear logging technology at home and abroad in recent years, the problems and gaps are pointed out in the field of fundamental research of nuclear logging at home, and the future development of new nuclear logging technologies is concisely analyzed. Therefore, the optimal design and processing are conducted from aspects of ray source, detector, data acquisition and processing method. In addition, the fundamental research of LWD and pulsed neutron logging technology is taken as the main breach. In the fundamental research of nuclear logging technology, innovative thinking should be expressed and the innovation should be achieved in every field of the development of nuclear logging technology. Meanwhile, the logging key lab should be taken as the platform and the latest achievement in the field of nuclear logging technology should be fully utilized. Thus, the level of independent R and D and technology innovation of logging tools will be raised and service for the exploration and development of petroleum and other mineral resources. (authors)

  11. Neutron-irradiation facilities at the Intense Pulsed Neutron Source-I for fusion magnet materials studies

    International Nuclear Information System (INIS)

    Brown, B.S.; Blewitt, T.H.

    1982-01-01

    The decommissioning of reactor-based neutron sources in the USA has led to the development of a new generation of neutron sources that employ high-energy accelerators. Among the accelerator-based neutron sources presently in operation, the highest-flux source is the Intense Pulsed Neutron Source (IPNS), a user facility at Argonne National Laboratory. Neutrons in this source are produced by the interaction of 400 to 500 MeV protons with either of two 238 U target systems. In the Radiation Effects Facility (REF), the 238 U target is surrounded by Pb for neutron generatjion and reflection. The REF has three separate irradiation thimbles. Two thimbles provide irradiation temperatures between that of liquid He and several hundred degrees centigrade. The third thimble operates at ambient temperature. The large irradiation volume, the neutron spectrum and flux, the ability to transfer samples without warm up, and the dedication of the facilities during the irradiation make this ideally suited for radiation damage studies on components for superconducting fusion magnets. Possible experiments for fusion magnet materials are discussed on cyclic irradiation and annealing of stabilizers in a high magnetic field, mechanical tests on organic insulation irradiated at 4 K, and superconductors measured in high fields after irradiation

  12. Analysis of Crystallographic Structure of a Japanese Sword by the Pulsed Neutron Transmission Method

    Science.gov (United States)

    Kino, K.; Ayukawa, N.; Kiyanagi, Y.; Uchida, T.; Uno, S.; Grazzi, F.; Scherillo, A.

    We measured two-dimensional transmission spectra of pulsed neutron beams for a Japanese sword sample. Atom density, crystalline size, and preferred orientation of crystals were obtained using the RITS code. The position dependence of the atomic density is consistent with the shape of the sample. The crystalline size is very small and shows position dependence, which is understood by the unique structure of Japanese swords. The preferred orientation has strong position dependence. Our study shows the usefulness of the pulsed neutron transmission method for cultural metal artifacts.

  13. Delayed neutron spectra from short pulse fission of uranium-235

    International Nuclear Information System (INIS)

    Atwater, H.F.; Goulding, C.A.; Moss, C.E.; Pederson, R.A.; Robba, A.A.; Wimett, T.F.; Reeder, P.; Warner, R.

    1986-01-01

    Delayed neutron spectra from individual short pulse (∼50 μs) fission of small 235 U samples (50 mg) were measured using a small (5 cm OD x 5 cm length) NE 213 neutron spectrometer. The irradiating fast neutron flux (∼10 13 neutrons/cm 2 ) for these measurements was provided by the Godiva fast burst reactor at the Los Alamos Critical Experiment Facility (LACEF). A high speed pneumatic transfer system was used to transfer the 50 mg 235 U samples from the irradiation position near the Godiva assembly to a remote shielded counting room containing the NE 213 spectrometer and associated electronics. Data were acquired in sixty-four 0.5 s time bins and over an energy range 1 to 7 MeV. Comparisons between these measurements and a detailed model calculation performed at Los Alamos is presented

  14. Proceedings of the workshop on neutron instrumentation for a long-pulse spallation source

    International Nuclear Information System (INIS)

    Alonso, J.; Schroeder, L.; Pynn, R.

    1995-01-01

    This workshop was carried out under the auspices of the Lawrence Berkeley National Laboratory Pulsed Spallation Source activity and its Pulsed Spallation Source Committee (PSSC). One of our activities has been the sponsorship of workshops related to neutron production by pulsed sources. At the Crystal City PSSC meeting a decision was made to hold a workshop on the instrumentation opportunities at a long-pulse spallation source (LPSS). The enclosed material represents the results of deliberations of the three working groups into which the participants were divided, covering elastic scattering, inelastic scattering and fundamental physics, as well as contributions from individual participants. We hope that the material in this report will be useful to the neutron scattering community as it develops a road-map for future neutron sources. The workshop was held at LBNL in mid-April with about sixty very dedicated participants from the US and abroad. This report presents the charge for the workshop: Based on the bench mark source parameters provided by Gary Russell, determine how a suite of spectrometers in each of the three working group's area of expertise would perform at an LPSS and compare this performance with that of similar spectrometers at a continuous source or a short-pulse source. Identify and discuss modifications to these spectrometers that would enhance their performance at an LPSS. Identify any uncertainties in the analysis of spectrometer performance that require further research. Describe what R ampersand D is needed to resolve these issues. Discuss how the performance of instruments would be affected by changes in source parameters such as repetition rate, proton pulse length, and the characteristic time of pulse tails. Identify beneficial changes that could become goals for target/moderator designers. Identify novel methods that might be applied at an LPSS. Selected papers are indexed separately for inclusion in the Energy Science and Technology

  15. A new pulsed neutron source at Pohang accelerator laboratory

    International Nuclear Information System (INIS)

    Kim, G.N.; Choi, J.Y.; Cho, M.H.; Ko, I.S.; Namkung, W.; Chang, J.H.

    1997-01-01

    The main efforts in the field of promoting the nuclear data activities to support the national nuclear development program being realized in the Republic of Korea are discussed. Within this program frameworks the Korea Atomic Energy Research Institute (KAERI) will play a central role and the Pohang Accelerator Laboratory (PAL) will construct a pulsed neutron source facility. The 100 MeV electron linac based on the existing equipment including Toshiba E3712 klystron, 200 MW modulator and constant gradient accelerating sections is designed in PAL. The schematic diagram and the main parameters of the linac consisting of a triode type electron gun (EIMAC Y824), an S-band prebuncher and buncher, two accelerating sections and various other components are considered. The construction of the linac already started in early 1997 is planned to be completed in 1998. The target room, TOF beam lines and detector stations will be constructed by the end of 1999. The first experiments with the intense pulsed neutrons produced at the facility considered are expected by 2000

  16. Measurement and fitting of pulse shapes of moderators at IPNS [Intense Pulsed Neutron Source]: Progress report

    International Nuclear Information System (INIS)

    Bywater, R.L. Jr.; Williams, R.E.; Carpenter, J.M.

    1988-01-01

    We present a progress report on measurements and fitting of pulse shapes for neutrons emerging from one solid and two liquid methane moderators in IPNS. A time-focused crystal spectrometer arrangement was used with a cooled Ge monochromator. Data analysis of one of the liquid methane moderators has shown the need for some generalization of the Ikeda-Carpenter function that worked well for fitting pulse shapes of polyethylene moderators. We describe attempts to model physical insight into the wavelength dependence of function parameters. 5 refs., 7 figs

  17. Developments in Pulsed Neutron Activation for Determination of Water Flow in Pipes

    CERN Document Server

    Mattsson, H

    2003-01-01

    In PNA (pulsed neutron activation) it is important that the measured data can be related to the total mass flow. In this thesis two fundamental problems of the measurement technique and data treatment have been investigated: transport/mixing and background radiation. The principle of PNA is to introduce a radioactive substance into a pipe by bombarding fluid in the pipe with neutron pulses. The fluid in the pipe is activated and subsequently transported and mixed with the flow. Gamma radiation emitted from the activity is measured with one or two detectors downstream from the activation point. The time-resolved signal from the detectors is used to calculate the average velocity of the water flow. Due to the short distance between the neutron generator and the pipe the activity in the pipe becomes highly inhomogeneous. The transport and mixing of the activity were simulated using colour which was injected into the flow. It was found that the inhomogeneous activity distribution must be taken into account if the...

  18. Characterizations of double pulsing in neutron multiplicity and coincidence counting systems

    Energy Technology Data Exchange (ETDEWEB)

    Koehler, Katrina E., E-mail: kkoehler@lanl.gov [Los Alamos National Laboratory, P. O. Box 1663, Los Alamos, NM 87545 (United States); Henzl, Vladimir [Los Alamos National Laboratory, P. O. Box 1663, Los Alamos, NM 87545 (United States); Croft, Stephen S. [Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37831 (United States); Henzlova, Daniela; Santi, Peter A. [Los Alamos National Laboratory, P. O. Box 1663, Los Alamos, NM 87545 (United States)

    2016-10-01

    Passive neutron coincidence/multiplicity counters are subject to non-ideal behavior, such as double pulsing and dead time. It has been shown in the past that double-pulsing exhibits a distinct signature in a Rossi-alpha distribution, which is not readily noticed using traditional Multiplicity Shift Register analysis. However, it has been assumed that the use of a pre-delay in shift register analysis removes any effects of double pulsing. In this work, we use high-fidelity simulations accompanied by experimental measurements to study the effects of double pulsing on multiplicity rates. By exploiting the information from the double pulsing signature peak observable in the Rossi-alpha distribution, the double pulsing fraction can be determined. Algebraic correction factors for the multiplicity rates in terms of the double pulsing fraction have been developed. We discuss the role of these corrections across a range of scenarios.

  19. The use of vanadium as a scattering standard for pulsed source neutron spectrometers

    International Nuclear Information System (INIS)

    Mayers, J.

    1983-06-01

    The Gaussian approximation for multiphonon cross-sections has been used in a calculation of the variation of vanadium cross-sections with incident neutron energy. The results show that vanadium behaves as an elastic scatterer to within a few percent on pulsed neutron spectrometers with incident neutron energies up to 1 eV. There is a calculated anisotropy in the scattering of 8%. It is found that the scattering properties of vanadium at 77K and 293K differ by a maximum of 1% except for neutron energies < 15 meV. (author)

  20. The high-density Z-pinch as a pulsed fusion neutron source for fusion nuclear technology and materials testing

    International Nuclear Information System (INIS)

    Krakowski, R.A.; Sethian, J.D.; Hagenson, R.L.

    1989-01-01

    The dense Z-pinch (DZP) is one of the earliest and simplest plasma heating and confinement schemes. Recent experimental advances based on plasma initiation from hair-like (10s μm in radius) solid hydrogen filaments have so far not encountered the usually devastating MHD instabilities that plagued early DZP experiments. These encouraging results along with debt of a number of proof-of principle, high-current (1--2 MA in 10--100 ns) experiments have prompted consideration of the DZP as a pulsed source of DT fusion neutrons of sufficient strength (/dot S//sub N/ ≥ 10 19 n/s) to provide uncollided neutron fluxes in excess of I/sub ω/ = 5--10 MW/m 2 over test volumes of 10--30 litre or greater. While this neutron source would be pulsed (100s ns pulse widths, 10--100 Hz pulse rate), giving flux time compressions in the range 10 5 --10 6 , its simplicity, near-time feasibility, low cost, high-Q operation, and relevance to fusion systems that may provide a pulsed commercial end-product (e.g., inertial confinement or the DZP itself) together create the impetus for preliminary considerations as a neutron source for fusion nuclear technology and materials testings. The results of a preliminary parametric systems study (focusing primarily on physics issues), conceptual design, and cost versus performance analyses are presented. The DZP promises an expensive and efficient means to provide pulsed DT neutrons at an average rate in excess of 10 19 n/s, with neutron currents I/sub ω/ /approx lt/ 10 MW/m 2 over volumes V/sub exp/ ≥ 30 litre using single-pulse technologies that differ little from those being used in present-day experiments. 34 refs., 17 figs., 6 tabs

  1. Intense resonance neutron source (IREN) - new pulsed source for nuclear physical and applied investigations

    International Nuclear Information System (INIS)

    Anan'ev, V.D.; Furman, W.I.; Kobets, V.V.; Meshkov, I.N.; Pyataev, V.G.; Shirkov, G.D.; Shvets, V.A.; Sumbaev, A.P.; Kuatbekov, R.P.; Tret'yakov, I.T.; Frolov, A.R.; Gurov, S.M.; Logachev, P.V.; Pavlov, V.M.; Skarbo, B.A.

    2005-01-01

    An accelerator-driven subcritical system (200 MeV electron linac + metallic plutonium subcritical core) IREN is constructed at the Joint Institute for Nuclear Research (JINR). The new pulsed neutron source IREN is optimized for maximal yield of resonance neutrons (1-10 5 eV). The S-band electron linac with a pulse duration near 200 ns, repetition rate up to 150 Hz and the mean beam power 10 kW delivers 200-MeV electrons onto a specially designed tungsten target (an electron-neutron converter) situated in the center of a very compact and fast subcritical assembly with K eff 15 per second. A mean fission power of the multiplying target is planned to be near 15 kW. The current status of the project is presented

  2. Neutron-gamma discrimination based on bipolar trapezoidal pulse shaping using FPGAs in NE213

    Energy Technology Data Exchange (ETDEWEB)

    Esmaeili-sani, Vahid, E-mail: vaheed_esmaeely80@yahoo.com [Department of Nuclear Engineering and Physics, Amirkabir University of Technology, P.O. Box 4155-4494, Tehran (Iran, Islamic Republic of); Moussavi-zarandi, Ali; Akbar-ashrafi, Nafiseh; Boghrati, Behzad; Afarideh, Hossein [Department of Nuclear Engineering and Physics, Amirkabir University of Technology, P.O. Box 4155-4494, Tehran (Iran, Islamic Republic of)

    2012-12-01

    A technique employing neutron-gamma pulse shape discrimination (PSD) system that overcomes pile up limitations of previous methods to distinguish neutrons from gammas in scintillation detectors is described. The output signals of detectors were digitized and processed with a data acquisition system based on bipolar trapezoidal pulse shaping using Field programmable gate arrays (FPGA). FPGAs are capable of doing complex discrete signal processing algorithms with clock rates above 100 MHz. Their low cost, ease of use and selected dedicated hardware make them an ideal option for spectrometer systems.

  3. Pulse-shape discrimination of high-energy neutrons and gamma rays in NaI(Tl)

    International Nuclear Information System (INIS)

    Share, G.H.; Kurfess, J.D.; Theus, R.B.

    1978-01-01

    Pulse-shape discrimination can be used to separate neutron and gamma-ray interactions depositing energies up to in excess of 50 MeV in NaI(Tl) crystals. The secondary alpha particles, deuterons and protons produced in the neutron interactions are also resolvable. (Auth.)

  4. Design criteria for pulse transformers used in neutron detector pulse counting channels

    International Nuclear Information System (INIS)

    Powler, E.P.

    1963-10-01

    The need for long cables between the detector and head amplifier in neutron pulse counting channels has led to the development of systems in which a transformer is used to 'match' the high impedance of a fission or proportional counter to the characteristic impedance of the cable. A further transformer can be used to match the cable to the input of a low noise pulse amplifier if this has a high impedance. This report is intended to give the designer sufficient information to optimise a system and predict the performance in terms of signal to noise ratio, resolving time and gain. Related problems are covered and include the use of balanced twin cables, the requirements of temperatures up to 500 deg. C and the need for high interference rejection. Two systems are described in some detail to emphasise the principles of design. (author)

  5. Fast neutron spectrometer with pulse shape discrimination

    International Nuclear Information System (INIS)

    Verbitsky, S.S.

    1978-01-01

    A fast neutron spectrometer with a stilbene single crystal designed to operate at high pulsed count rate has been described. Making use of identification and rejection of events, accompanied by pile-up, allowed to increase permissible count rates by an order of magnitude. The results of energy dependence of signal amplitude and shape relative anisotropy in stilbene in the range 4-10 and 2-8 MeV respectively have been presented. Taking into account anisotropy of the detector-scintillation properties allowed to improve particle discrimination. (Auth.)

  6. Results and plans on the development of a pulsed neutron generator

    International Nuclear Information System (INIS)

    Sztaricskai, T.; Vasvary, L.; Petoe, G.

    1976-01-01

    Using the vacuum system of an old van de Graaff machine a new pulsed neutron generator has been developed. The block diagram, the scheme of generators arrangement and the electrode system of the ion bunching parts are shown

  7. Performance of novel moderator for pulsed neutron diffraction

    International Nuclear Information System (INIS)

    Mayer, R.E.; Granada, J.R.; Dawidowski, J.; Gillette, V.H.

    1991-01-01

    Measurements of neutron pulse time-width and intensity have been carried out on grids of small moderators placed side by side and decoupled by cadmium strips. This moderator concept had been introduced at ICANS-10. The present measurements explore greater moderator thicknesses than those previously attained, yielding information on thickness optimization, while confirming the previous results on resolution which make this moderator a favourable choice in front of the conventional sandwich set-up. (author)

  8. Study of two-zone reactor system using a pulsed neutron technique

    International Nuclear Information System (INIS)

    Shishin, B.P.; Platovskikh, Yu.A.; Didejkin, T.S.

    1977-01-01

    Theoretical and experimental investigations of a neutron flux time dependence after a sport fast neutron pulse in a reactor core - neutron reflector multiplying system have been conducted. A correlation between eigenvalues governing neutron flux decrease at t→infinity for the two-zone system and eigenvalues for each zone has been established in terms of the one-group diffusion approximation. Experiments have been performed in an experimental subcritical assembly comprising a cylindrical uranium core surrounded by a radial water reflector with different boric acid concentrations. The experiments show that the observed neutron flux decrease in the core is governed by an exponent exp(-Λ 1 t), whereas in the reflector by a sum of two exponents exp(-Λ 1 t) and exp(-Λ 2 t). The eigenvalue Λ 1 reflects multiplying properties of the reactor, and Λ 2 is determined by the reflector absorption cross section

  9. Production of neutrons up to 18 MeV in high-intensity, short-pulse laser matter interactions

    Energy Technology Data Exchange (ETDEWEB)

    Higginson, D. P. [Mechanical and Aerospace Engineering, University of California-San Diego, La Jolla, California 92093 (United States); Lawrence Livermore National Laboratory, Livermore, California 94440 (United States); McNaney, J. M.; Swift, D. C.; Mackinnon, A. J.; Patel, P. K. [Lawrence Livermore National Laboratory, Livermore, California 94440 (United States); Petrov, G. M.; Davis, J. [Naval Research Laboratory, Plasma Physics Division, Washington, DC 20375 (United States); Frenje, J. A. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Jarrott, L. C.; Tynan, G.; Beg, F. N. [Mechanical and Aerospace Engineering, University of California-San Diego, La Jolla, California 92093 (United States); Kodama, R.; Nakamura, H. [Institute of Laser Engineering, Osaka University, 2-5 Yamada-oka, Suita, Osaka 454-0871 (Japan); Lancaster, K. L. [STFC Rutherford Appleton Laboratory, Chilton, Oxon OX11OQX (United Kingdom)

    2011-10-15

    The generation of high-energy neutrons using laser-accelerated ions is demonstrated experimentally using the Titan laser with 360 J of laser energy in a 9 ps pulse. In this technique, a short-pulse, high-energy laser accelerates deuterons from a CD{sub 2} foil. These are incident on a LiF foil and subsequently create high energy neutrons through the {sup 7}Li(d,xn) nuclear reaction (Q = 15 MeV). Radiochromic film and a Thomson parabola ion-spectrometer were used to diagnose the laser accelerated deuterons and protons. Conversion efficiency into protons was 0.5%, an order of magnitude greater than into deuterons. Maximum neutron energy was shown to be angularly dependent with up to 18 MeV neutrons observed in the forward direction using neutron time-of-flight spectrometry. Absolutely calibrated CR-39 detected spectrally integrated neutron fluence of up to 8 x 10{sup 8} n sr{sup -1} in the forward direction.

  10. Intense pulsed neutron source accelerator status

    International Nuclear Information System (INIS)

    Potts, C.W.; Brumwell, F.R.; Stipp, V.F.

    1983-01-01

    The Intense Pulsed Neutron Source (IPNS) facility has been in operation since November 1, 1981. From that date through August 1, 1983, the accelerator system was scheduled for 7191 hours of operation. During this period, 627 million pulses totaling about 1.1 x 10 21 protons were delivered to the spallation target. The accelerator has exceeded goals set in 1981 by averaging 8.65 μA over this two year period. This average beam current, while modest by the standards of proposed machines, makes the IPNS synchrotron (Rapid Cycling Synchrotron [RCS]) the highest intensity proton synchrotron in the world today. Detailed data on accelerator operation are presented. Weekly average currents of 12 μA have been achieved along with peaks of 13.9 μA. A great deal has been learned about the required operating constraints during high beam current operation. It should be possible to increase the average beam current during this next year to 12 μA while observing these restraints. Improvement plans have been formulated to increase the beam current to 16 μA over the next three years

  11. The use of pulsed neutron diffraction to measure strain in composites

    International Nuclear Information System (INIS)

    Bourke, M.A.M.; Goldstone, J.A.; Shi, N.; Gray, G.T. III; James, M.R.

    1994-01-01

    Neutron diffraction is a technique for measuring strain in crystalline materials. It is non destructive, phase discriminatory and more penetrating than X rays. Pulsed neutron sources (in contrast with steady state reactor sources) are particularly appropriate for examining heterogeneous materials or for recording the polycrystalline response of all lattice reflections. Several different aspects of composite behavior can be characterized and examples are given of residual strain measurements, strain relaxation during heating, applied loading, and determination of the strain distribution function

  12. Shape difference between scintillation pulses due to γ rays and to neutrons

    International Nuclear Information System (INIS)

    Cambou, Francis; Ambrosino, Georges

    1960-01-01

    A simple method is described which allows to clearly show the shape differences between γ ray- and neutron-induced pulses. In the neutrons case the intensity of the slow component is 2.4 times higher than in the γ ray case. Reprint of a paper published in Comptes rendus des seances de l'Academie des Sciences, t. 250, p. 1034-1036, sitting of 8 February 1960 [fr

  13. Processing of gamma-ray spectrometric logs

    International Nuclear Information System (INIS)

    Umiastowski, K.; Dumesnil, P.

    1984-10-01

    CEA (Commissariat a l'Energie Atomique) has developped a gamma-ray spectrometric tool, containing an analog-to-digital converter. This new tool permits to perform very precise uranium logs (natural gamma-ray spectrometry), neutron activation logs and litho-density logs (gamma-gamma spectrometric logs). Specific processing methods were developped to treate the particular problems of down-hole gamma-ray spectrometry. Extraction of the characteristic gamma-ray peak, even if they are superposed on the background radiation of very high intensity, is possible. This processing methode enables also to obtain geological informations contained in the continuous background of the spectrum. Computer programs are written in high level language for SIRIUS (VICTOR) and APOLLO computers. Exemples of uranium and neutron activation logs treatment are presented [fr

  14. The application of pulse shape discrimination in NE 213 to neutron spectrometry

    International Nuclear Information System (INIS)

    Perkins, L.J.; Scott, M.C.

    1979-01-01

    The use of a zero-crossing pulse shape discrimination technique to distinguish protons from alpha particles in NE 213 is described, and a theoretical analysis is performed to predict the zero crossing characteristics. It is shown that, irrespective of the particular method of pulse shape discrimination employed, the pulse shape at low energies no longer uniquely determines the particle type for electrons, protons, alpha particles or 12 C nuclei, and the general limitations of pulse shape discrimination in NE 213 are deduced. The use of an alpha discrimination technique is then discribed, enabling neutron spectra to be unfolded from the measured detector response using a differential code. (orig.)

  15. A new philosophy for calibrating oil well logging tools based on neutron transport codes

    International Nuclear Information System (INIS)

    Butler, J.; Clayton, C.G.

    1984-01-01

    The current practice of calibrating neutron borehole logging probes is limited by an inability to match calibration conditions to those which pertain in an operational situation. In addition, test boreholes are expensive to construct and, when natural materials are used, rely on an exact correspondence in composition and in structure between the materials of the test facility and representative samples which may not be valid. Now that neutron tansport codes have been developed to a point at which they are able to cope with realistic, complex situations an alternative approach to calibration can be considered. The basis of this philosophy is the construction of a limited number of calibration facilities which are composed of artificial rocks of controlled but variable porosity and accurately known nuclear characteristics

  16. Log quality enhancement: A systematic assessment of logging company wellsite performance and log quality

    International Nuclear Information System (INIS)

    Farnan, R.A.; Mc Hattie, C.M.

    1984-01-01

    To improve the monitoring of logging company performance, computer programs were developed to assess information en masse from log quality check lists completed on wellsite by the service company engineer and Phillips representative. A study of all logging jobs performed by different service companies for Phillips in Oklahoma (panhandle excepted) during 1982 enabled several pertinent and beneficial interpretations to be made. Company A provided the best tool and crew service. Company B incurred an excessive amount of lost time related to tool failure, in particular the neutron-density tool combination. Company C, although used only three times, incurred no lost time. With a reasonable data base valid conclusions were made pertaining, for example, to repeated tool malfunctions. The actual logs were then assessed for quality

  17. Simultaneous multi-element analysis of some edible pulses using neutron activation analysis

    International Nuclear Information System (INIS)

    El-Sweify, F.H.; Metwally, E.; Abdel-Khalik, H.

    2007-01-01

    This paper comprises the application of instrumental neutron activation analysis (INAA) for multi-element determination in some edible pulse samples. These edible pulses are usually daily used in the Egyptian kitchen. These were: anise, cumin, coriander, caraway, black cumin, white kidney bean, lupine, lentil, chickpea, broad bean, peanut, almond, and fenugreek. The pulses have been analyzed as dehulled pulses, in the case of legume and oil pulses with simultaneous analysis of their respective skins. The determined elements were: Ce, Co, Cr, Cs, Eu, Fe, Hf, Rb, Sb, Sc, Sr, Th and Zn. The element content in the dehulled pulses and their respective skins has been compared. Some elements were major or minor elements where others were trace elements. Standard reference materials were used to assure quality control, accuracy and precision of the technique. (author)

  18. Neutron lifetime well logging methods and apparatus

    International Nuclear Information System (INIS)

    Paap, H.J.; Pitts, R.W.

    1974-01-01

    A method for investigating the earth formations surrounding a well borehole, comprising the steps of: continuously generating high energy neutrons in the borehole and bombarding the surrounding media with such neutrons to develop a cloud of thermal neutrons therein; modulating the intensity of said high energy neutrons harmonically as a function of time in order to intensity modulate said cloud of thermal neutrons as a function of time; and measuring a time-dependant thermal neutron characteristic of said intensity modulated cloud of thermal neutrons

  19. A pulsed fast reactor; Un reacteur pulse a neutrons rapides; Impul'snyj reaktor na bystrykh nejtronakh; Reactor rapido pulsado

    Energy Technology Data Exchange (ETDEWEB)

    Blokhin, G. E.; Blokhintsev, D. I.; Blyumkina, Yu. A.; Bondarenko, I. I.; Deryagin, B. N.; Zajmovskij, A. S.; Zinov' ev, V. P.; Kazachkovskij, O. D.; Krasnoyarov, N. V.; Lejpunskij, A. I.; Malykh, V. A.; Nazarov, P. M.; Nikolaev, S. K.; Stavisskij, Yu. Ya.; Ukraintsev, F. I.; Frank, I. M.; Shapiro, F. Ji.; Yazvitskij, Yu. S. [Akademiya Nauk, Moscow, SSSR (Russian Federation)

    1962-03-15

    A pulsed fast reactor (IBR) has been operating at rated capacity since December 1960 in the Joint Institute for Nuclear Research. This reactor is used as a pulsed neutron source for physical experiments carried out by the time-of-flight method. It is used for total cross-section and intermediate neutron capture cross- section measurements, for studying the interaction between slow neutrons and solids and liquids, and for measuring neutron spectra produced in various media. The paper describes the basic structural features of the reactor and the results of the experiments for which it has been used. The reactor's operating system is based on recurrent pulses. Power pulses are produced when the mobile part of the reactor core moves swiftly through the stationary part of the core. The mobile part of the core is fastened to a rotating disc and travels at a speed of 230 m/s. The frequency of power pulses can be altered by means of an auxiliary mobile zone which has a range of 2.3-88 pulses per second. The mean power of the reactor is 1 kW, and the half-width of the power pulse in 36 {mu}s. The reactor is provided with a control and safety system which ensures automatic maintenance of mean power and swift shutdown in the event of any operational irregularity. It is fitted with a system of evacuated-neutron-flight tubes used in time-of-flight experiments. The main tube is 1000 m in length. In the start-up process and during physical experiments carried out on the reactor, the influence on reactivity of displacing the controls and the mobile parts of the core was studied ; the length of the pulse was measured under various operating conditions, and power pulse amplitude fluctuations were studied. Further measurements were made to establish the lifetime of prompt neutrons, the effective fraction of delayed neutrons, and coefficients of reactivity. (author) [French] L'Institut unifie de recherches nucleaires dispose d'un reacteur puise a neutrons rapides (IBR), qui

  20. Instrumentation system for pulsed neutron generator. Pt. 1. Electronic control and data acquisition

    International Nuclear Information System (INIS)

    Burda, J.; Igielski, A.; Janik, W.; Kosik, M.; Kurowski, A.; Zaleski, T.

    1997-01-01

    The paper presents an electronic instrumentation system which is successfully applied for pulsed neutron generator and measurements. In the paper there are described in details all modernized parts of the system as well as new designed and applied ones. The set of diagrams is enclosed. An important part of the system has been designed and built in the Neutron Transport Physics Laboratory. (author)

  1. Nondestructive analysis of the natural uranium mass through the measurement of delayed neutrons using the technique of pulsed neutron source; Analise nao destrutiva da massa de uranio natural atraves da medida de neutrons atrasados com o uso da tecnica de fonte pulsada de neutrons rapidos

    Energy Technology Data Exchange (ETDEWEB)

    Coelho, Paulo Rogerio Pinto

    1979-07-01

    This work presents results of non destructive mass analysis of natural uranium by the pulsed source technique. Fissioning is produced by irradiating the test sample with pulses of 14 MeV neutrons and the uranium mass is calculated on a relative scale from the measured emission of delayed neutrons. Individual measurements were normalised against the integral counts of a scintillation detector measuring the 14 MeV neutron intensity. Delayed neutrons were measured using a specially constructed slab detector operated in anti synchronism with the fast pulsed source. The 14 MeV neutrons were produced via the T(d,n) {sup 4}He reaction using a 400 kV Van de Graaff accelerated operated at 200 kV in the pulsed source mode. Three types of sample were analysed, namely: discs of metallic uranium, pellets of sintered uranium oxide and plates of uranium aluminium alloy sandwiched between aluminium. These plates simulated those of Material Testing Reactor fuel elements. Results of measurements were reproducible to within an overall error in the range 1.6 to 3.9%; the specific error depending on the shape, size and mass of the sample. (author)

  2. Time-lapse cased hole reservoir evaluation based on the dual-detector neutron lifetime log: the CHES II approach

    International Nuclear Information System (INIS)

    DeVries, M.R.; Fertl, W.

    1977-01-01

    A newly developed cased hole analysis technique provides detailed information on (1) reservoir rock properties, such as porosity, shaliness, and formation permeability, (2) reservoir fluid saturation, (3) distinction of oil and gas pays, (4) state of reservoir depletion, such as cumulative hydrocarbon-feet at present time and cumulative hydrocarbon-feet already depleted (e.g., the sum of both values then giving the cumulative hydrocarbon-feet originally present), and (5) monitoring of hydrocarbon/water and gas/oil contacts behind pipe. The basic well log data required for this type of analysis include the Dual-Detector Neutron Lifetime Log, run in casing at any particular time in the life of a reservoir, and the initial open-hole resistivity log. In addition, porosity information from open-hole porosity log(s) or core data is necessary. Field examples from several areas are presented and discussed in the light of formation reservoir and hydrocarbon production characteristics

  3. Pulse-shape discrimination in radioanalytical methods. Part I. Delayed fission neutron counting

    International Nuclear Information System (INIS)

    Posta, S.; Vacik, J.; Hnatowicz, V.; Cervena, J.

    1999-01-01

    In this study the principle of pulse shape discrimination (PSD) has been employed in delayed fission neutron counting (DNC) method. Effective elimination of unwanted gamma background signals in measured radiation spectra has been proved. (author)

  4. Calibration of a detector by activation with a continuous neutron source used as a transfer standard for measuring pulsed neutron beams

    International Nuclear Information System (INIS)

    Moreno, Jose; Silva, Patricio; Birstein, Lipo; Soto, Leopoldo

    2002-01-01

    This paper presents a method for calibrating activation detectors. These detectors will be used as transfer standard in measuring neutron fluxes produced by pulsed plasma sources. A standard neutron source is used as a secondary standard. The activation detector is being shielded in order to substantially reduce detection of gamma emission coming from the source. The detector's calibration factor is obtained by considering also the standard neutron source as a free source of gamma radiation so that the measurements can be done without quickly withdrawing the neutron source as it is usually done. This will substantially simplify the traditionally established method (JM)

  5. Design of 6 Mev linear accelerator based pulsed thermal neutron source: FLUKA simulation and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Patil, B.J., E-mail: bjp@physics.unipune.ac.in [Department of Physics, University of Pune, Pune 411 007 (India); Chavan, S.T.; Pethe, S.N.; Krishnan, R. [SAMEER, IIT Powai Campus, Mumbai 400 076 (India); Bhoraskar, V.N. [Department of Physics, University of Pune, Pune 411 007 (India); Dhole, S.D., E-mail: sanjay@physics.unipune.ac.in [Department of Physics, University of Pune, Pune 411 007 (India)

    2012-01-15

    The 6 MeV LINAC based pulsed thermal neutron source has been designed for bulk materials analysis. The design was optimized by varying different parameters of the target and materials for each region using FLUKA code. The optimized design of thermal neutron source gives flux of 3 Multiplication-Sign 10{sup 6}ncm{sup -2}s{sup -1} with more than 80% of thermal neutrons and neutron to gamma ratio was 1 Multiplication-Sign 10{sup 4}ncm{sup -2}mR{sup -1}. The results of prototype experiment and simulation are found to be in good agreement with each other. - Highlights: Black-Right-Pointing-Pointer The optimized 6 eV linear accelerator based thermal neutron source using FLUKA simulation. Black-Right-Pointing-Pointer Beryllium as a photonuclear target and reflector, polyethylene as a filter and shield, graphite as a moderator. Black-Right-Pointing-Pointer Optimized pulsed thermal neutron source gives neutron flux of 3 Multiplication-Sign 10{sup 6} n cm{sup -2} s{sup -1}. Black-Right-Pointing-Pointer Results of the prototype experiment were compared with simulations and are found to be in good agreement. Black-Right-Pointing-Pointer This source can effectively be used for the study of bulk material analysis and activation products.

  6. Electron-volt spectroscopy at a pulsed neutron source using a resonance detector technique

    CERN Document Server

    Andreani, C; Senesi, R; Gorini, G; Tardocchi, M; Bracco, A; Rhodes, N; Schooneveld, E M

    2002-01-01

    The effectiveness of the neutron resonance detector spectrometer for deep inelastic neutron scattering measurements has been assessed by measuring the Pb scattering on the eVS spectrometer at ISIS pulsed neutron source and natural U foils as (n,gamma) resonance converters. A conventional NaI scintillator with massive shielding has been used as gamma detector. A neutron energy window up to 90 eV, including four distinct resonance peaks, has been assessed. A net decrease of the intrinsic width of the 6.6 eV resonance peak has also been demonstrated employing the double difference spectrum technique, with two uranium foils of different thickness.

  7. REM meter for pulsed sources of neutrons

    International Nuclear Information System (INIS)

    Thorngate, J.E.; Hunt, G.F.; Rueppel, D.W.

    1980-01-01

    A rem meter was constructed specifically for measuring neutrons produced by fusion experiments for which the source pulses last 10 ms or longer. The detector is a 6 Li glass scintillator, 25.4 mm in diameter and 3.2 mm thick, surrounded by 11.5 cm of polyethylene. This detector has a sensitivity of 8.5 x 10 4 counts/mrem. The signals from this fast scintillator are shaped using a shorted delay line to produce pulses that are only 10 ns long so that dose equivalent rates up to 12 mrem/s can be measured with less than a 1% counting loss. The associated electronic circuits store detector counts only when the count rate exceeds a preset level. When the count rate returns to background, a conversion from counts to dose equivalent is made and the results are displayed. As a means of recording the number of source pulses that have occurred, a second display shows how many times the preset count rate has been exceeded. Accumulation of detector counts and readouts can also be controlled manually. The unit will display the integrated dose equilavent up to 200 mrem in 0.01 mrem steps. A pulse-height discriminator rejects gamma-ray interactions below 1 MeV, and the detector size limits the response above that energy. The instrument can be operated from an ac line or will run on rechargeable batteries for up to 12 hours

  8. Tests on a digital neutron-gamma pulse shape discriminator with NE213

    International Nuclear Information System (INIS)

    Bell, Z.W.

    1981-01-01

    A technique using charge sensitive analog-to-digital converters to do neutron-gamma pulse shape discrimination is reported. The converters are gated by short (135 ns) pulses so as to reduce pile-up and the timing is such that the slow and total light output from the scintillator are measured. Preliminary tests indicate that the system performs reasonably well but poorer than some reported analog systems employing gated integrators or cross-over techniques. (orig.)

  9. Neutron polarization measurements using the pulsed-polarized proton and deuteron beams at TUNL

    International Nuclear Information System (INIS)

    Walter, R.L.

    1981-01-01

    Nanosecond wide pulses of polarized protons or deuterons at a repetition rate of 4 MHz are now routinely available for studying interactions involving outgoing neutrons. Up to 90 nA of protons and 200 nA of deuterons have been observed on target. The authors' first experiments involved the determination of the analyzing power A /SUB y/ (UJ) for a few (→p,n) and (→d,n) reactions using conventional neutron time-of-flight detection. A major program for observing polarization effects in neutron elastic scattering has been initiated. The source of polarized neutrons for this program is the 2 H(→d,n→) 3 He reaction which yields a neutron beam having 90% of the polarization of the incident deuterons

  10. Thermal neutron pulsed parameters in non-hydrogenous systems. Experiment for lead grains

    International Nuclear Information System (INIS)

    Drozdowicz, K.; Gabanska, B.; Kosik, M.; Krynicka, E.; Woznicka, U.; Zaleski, T.

    1997-01-01

    In Czubek's method of measurement of the thermal neutron macroscopic absorption cross section a two-region geometry is applied where the investigated sample is surrounded by an external moderator. Both regions in the measurements made up till now were hydrogenous, which means the same type of the thermal neutron transport properties. In the paper a theoretical consideration to use non-hydrogenous materials as the samples is presented. Pulsed neutron measurements have been performed on homogeneous material in a geometry of the classic experiment with the variable geometric buckling. Two decay constants have been measured for different cylindrical samples of small lead grains (a lead shot). (author)

  11. Apparatus for reducing pulse pileup in an elemental analyzer measuring gamma rays arising from neutron capture in bulk substances

    International Nuclear Information System (INIS)

    Marshall, J.H. III.

    1979-01-01

    The active reduction of the number of analyzed events with pulse amplitudes which pileup has distorted improves measurement accuracy and response time in an apparatus for neutron-capture-based on-line elemental analysis of bulk substances. Within the apparatus, the analyzed bulk substance is exposed to neutrons, and neutron capture generates prompt gamma rays therefrom. A detector interacts with some of these gamma rays to produce electrical signals used to measure their energy spectrum by pulse-height analysis. Circuits associated with this pulse-height analysis also detect the pileup of the signals of two or more independent gamma rays using one or more of several techniques. These techniques include multiple outputs from a special amplifier-discriminator system, which has been optimized for low pulse-pair resolving time and may have adaptive thresholds, and the requirement that the relative amplitudes of the outputs of slow and fast amplifiers be consistent with a single event producing both outputs. Pulse-width measurements are also included in the pileup detection

  12. Neutron control of well debit increasing by acoustic influence on oil formation

    International Nuclear Information System (INIS)

    Bogdanovich, B.Yu.; Nesterovich, A.V.; Khasaya, D.R.; Shikanov, A.E.; Shikanov, E.A.; Il'inskiy, A.V.; Mihailov, L.V.; Kolomiets, N.F.

    2012-01-01

    The effectiveness of the A E direction in oil reservoirs can be improved by controlling the parameters of the processes occurring before and after acoustic effect in oil reservoirs, followed by a choice of intervals stimulation of oil. Measurements of changes in these processes in the reservoir are made remotely via a metal pipe casing that requires the use of transparent methods of control. In implementing the method of pulse neutron-neutron logging in the study area provide periodic field impulse of fast neutrons emitted by the accelerating tube, resulting in leakage to its target nuclear reaction T (d, n) 4He

  13. A method of precise profile analysis of diffuse scattering for the KENS pulsed neutrons

    International Nuclear Information System (INIS)

    Todate, Y.; Fukumura, T.; Fukazawa, H.

    2001-01-01

    An outline of our profile analysis method, which is now of practical use for the asymmetric KENS pulsed thermal neutrons, are presented. The analysis of the diffuse scattering from a single crystal of D 2 O is shown as an example. The pulse shape function is based on the Ikeda-Carpenter function adjusted for the KENS neutron pulses. The convoluted intensity is calculated by a Monte-Carlo method and the precision of the calculation is controlled. Fitting parameters in the model cross section can be determined by the built-in nonlinear least square fitting procedure. Because this method is the natural extension of the procedure conventionally used for the triple-axis data, it is easy to apply with generality and versatility. Most importantly, furthermore, this method has capability of precise correction of the time shift of the observed peak position which is inevitably caused in the case of highly asymmetric pulses and broad scattering function. It will be pointed out that the accurate determination of true time-of-flight is important especially in the single crystal inelastic experiments. (author)

  14. Intercomparison of radiation protection instrumentation in a pulsed neutron field

    CERN Document Server

    Caresana, M; Esposito, A; Ferrarini, M; Golnik, N; Hohmann, E; Leuschner, A; Luszik-Bhadra, M; Manessi, G; Mayer, S; Ott, K; Röhrich, J; Silari, M; Trompier, F; Volnhals, M; Wielunski, M

    2014-01-01

    In the framework of the EURADOS working group 11, an intercomparison of active neutron survey meters was performed in a pulsed neutron field (PNF). The aim of the exercise was to evaluate the performances of various neutron instruments, including commercially available rem-counters, personal dosemeters and instrument prototypes. The measurements took place at the cyclotron of the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH. The cyclotron is routinely used for proton therapy of ocular tumours, but an experimental area is also available. For the therapy the machine accelerates protons to 68 MeV. The interaction of the proton beam with a thick tungsten target produces a neutron field with energy up to about 60 MeV. One interesting feature of the cyclotron is that the beam can be delivered in bursts, with the possibility to modify in a simple and flexible way the burst length and the ion current. Through this possibility one can obtain radiation bursts of variable duration and intensity. All instru...

  15. Palm top plasma focus device as a portable pulsed neutron source

    International Nuclear Information System (INIS)

    Rout, R. K.; Niranjan, Ram; Srivastava, R.; Rawool, A. M.; Kaushik, T. C.; Gupta, Satish C.; Mishra, P.

    2013-01-01

    Development of a palm top plasma focus device generating (5.2 ± 0.8) × 10 4 neutrons/pulse into 4π steradians with a pulse width of 15 ± 3 ns is reported for the first time. The weight of the system is less than 1.5 kg. The system comprises a compact capacitor bank, a triggered open air spark gap switch, and a sealed type miniature plasma focus tube. The setup is around 14 cm in diameter and 12.5 cm in length. The energy driver for the unit is a capacitor bank of four cylindrical commercially available electrolytic capacitors. Each capacitor is of 2 μF capacity, 4.5 cm in diameter, and 9.8 cm in length. The cost of each capacitor is less than US$ 10. The internal diameter and the effective length of the plasma focus unit are 2.9 cm and 5 cm, respectively. A DC to DC converter power supply powered by two rechargeable batteries charges the capacitor bank to the desired voltage and also provides a trigger pulse of −15 kV to the spark gap. The maximum energy of operation of the device is 100 J (8 μF, 5 kV, 59 kA) with deuterium gas filling pressure of 3 mbar. The neutrons have also been produced at energy as low as 36 J (3 kV) of operation. The neutron diagnostics are carried out with a bank of 3 He detectors and with a plastic scintillator detector. The device is portable, reusable, and can be operated for multiple shots with a single gas filling.

  16. Chemical crystallography with pulsed neutrons and synchrotron x-rays

    International Nuclear Information System (INIS)

    Carrondo, M.A.; Jeffrey, G.A.

    1988-01-01

    Solid-state chemists and physicists, crystallographers and molecular biologists who are using or who plan to use the special properties of pulsed neutron spallation and synchrotron X-ray sources will find this book invaluable. Those scientists who have not yet gained experience in working with such sources will find the basic physics of the radiations, their production and their scattering properties explained, together with descriptions of the different types of diffraction experiments which use them

  17. Theory of Pulsed Neutron Experiments in Highly Heterogeneous Multiplying Media

    International Nuclear Information System (INIS)

    Corno, S.E.

    1965-01-01

    In this work we investigate the time and space dependence of the neutron flux within a highly heterogeneous assembly, in which pulsed or sinusoidally modulated neutrons are injected. We consider, for the sake of simplicity, a device consisting of a cylindrical block of heavy moderator, along the axis of which a line-shaped region of fissionable material is located. The driving neutron source is assumed to be located on one of the end faces of the cylinder. The extent of the fissionable region allows us to deal with it as with an absorbing and multiplying singularity of the neutron field. As our attention is mostly concentrated on space and time variation of the neutron flux, rather crude approximations are assumed as far as the energy dependence of the neutron population is concerned. Within the limits of the age-diffusion theory, the response of the device to any neutron excitation may be found in closed form. For a sinusoidally modulated source of given frequency, it may easily be shown that, if the axial singularity were a purely absorbing one, the neutron waves being propagated along the device would possess a phase shift; a wavelength and an attenuation constant depending on the absorbing properties of the singularity. This picture becomes more and more complicated when neutron multiplication occurs. For this general case the solution derived in our paper obviously turns out to be dependent on both absorption and multiplication properties of the singularity. This circumstance suggests, among others, the idea of using a device of the type described above for testing fuel elements of heterogeneous reactors. (author) [fr

  18. The feasibility of well-logging measurements of arsenic levels using neutron-activation analysis

    Science.gov (United States)

    Oden, C.P.; Schweitzer, J.S.; McDowell, G.M.

    2006-01-01

    Arsenic is an extremely toxic metal, which poses a significant problem in many mining environments. Arsenic contamination is also a major problem in ground and surface waters. A feasibility study was conducted to determine if neutron-activation analysis is a practical method of measuring in situ arsenic levels. The response of hypothetical well-logging tools to arsenic was simulated using a readily available Monte Carlo simulation code (MCNP). Simulations were made for probes with both hyperpure germanium (HPGe) and bismuth germanate (BGO) detectors using accelerator and isotopic neutron sources. Both sources produce similar results; however, the BGO detector is much more susceptible to spectral interference than the HPGe detector. Spectral interference from copper can preclude low-level arsenic measurements when using the BGO detector. Results show that a borehole probe could be built that would measure arsenic concentrations of 100 ppm by weight to an uncertainty of 50 ppm in about 15 min. ?? 2006 Elsevier Ltd. All rights reserved.

  19. Time-of-flight small-angle scattering spectrometers on pulsed neutron sources

    International Nuclear Information System (INIS)

    Ostanevich, Yu.M.

    1987-01-01

    The operation principles, constructions, advantages and shortcomings of known time-of-flight small angle neutron scattering (TOF SANS) spectrometers built up with pulsed neutron sources are reviewed. The most important characteristics of TOF SANS apparatuses are rather a high luminosity and the possibility for the measurement in an extremely wide range of scattering vector at a single exposure. This is achieved by simultaneous employment of white beam, TOF technique for wave length-scan and the commonly known angle-scan. However, the electronic equipment, data-matching programs, and the measurement procedure, necessary for accurate normalization of experimental data and their transformation into absolute cross-section scale, they all become more complex, as compared with those for SANS apparatuses operating on steady-state neutron sources, where only angle-scan is used

  20. Small-angle scattering at a pulsed neutron source: comparison with a steady-state reactor

    Energy Technology Data Exchange (ETDEWEB)

    Borso, C S; Carpenter, J M; Williamson, F S; Holmblad, G L; Mueller, M H; Faber, J Jr; Epperson, J E; Danyluk, S S [Argonne National Lab., IL (USA)

    1982-08-01

    A time-of-flight small-angle diffractometer employing seven tapered collimator elements and a two-dimensional gas proportional counter was successfully utilized to collect small-angle scattering data from a solution sample of the lipid salt cetylpyridinium chloride, C/sub 21/H/sub 38/N/sup +/.Cl/sup -/, at the Argonne National Laboratory prototype pulsed spallation neutron source, ZING-P'. Comparison of the small-angle scattering observed from the same compound at the University of Missouri Research Reactor corroborated the ZING-P' results. The results are used to compare the neutron flux available from the ZING-P' source relative to the well characterized University of Missouri source. Calculations based on experimentally determined parameters indicated the time-averaged rate of detected neutrons at the ZING-P' pulsed spallation source to have been at least 33% higher than the steady-state count rate from the same sample. Differences between time-of-flight techniques and conventional steady-state techniques are discussed.

  1. Status of the intense pulsed neutron source

    International Nuclear Information System (INIS)

    Brown, B.S.; Carpenter, J.M.; Crawford, R.K.; Rauchas, A.V.; Schulke, A.W.; Worlton, T.G.

    1988-01-01

    IPNS is not unique in having concerns about the level of funding, and the future looks good despite these concerns. This report details the progress made at IPNS during the last two years. Other papers in these proceedings discuss in detail the status of the enriched uranium Booster target, the two instruments that are under construction, GLAD and POSY II, and a proposal for research on an Advanced Pulsed Neutron Source (ASPUN) that has been submitted to the Department of Energy (DOE). Further details on IPNS are available in the IPNS Progress Report 1987--1988, available by writing the IPNS Division Office. 9 refs., 3 tabs

  2. A target-moderator-reflector concept of the JAERI 5 MW pulsed spallation neutron source

    International Nuclear Information System (INIS)

    Watanabe, Noboru; Teshigawara, Makoto; Aizawa, Kazuya; Suzuki, Jyunichi; Oyama, Yukio

    1998-03-01

    In Japan Atomic Energy Research Institute the construction of a 5 MW (short) pulsed spallation neutron source is under planning using a projected high power superconducting proton (or H - ) linac of 8 MW in total beam power. In the present paper we report our consideration on target-moderator-reflector concept, based on the layout of the tentative neutron instruments for the assumed neutron scattering experiments in future. The choice of cold neutron moderators for high resolution and high intensity experiments, thermal and epithermal neutron moderators for high resolution uses was discussed and a reference layout of target-moderator-reflector system was proposed for detailed neutronic calculation and optimization. The proposed system was designed like that it can provide, at least, 30 beam lines for more than 40 instruments. (author)

  3. Advanced neutron imaging methods with a potential to benefit from pulsed sources

    International Nuclear Information System (INIS)

    Strobl, M.; Kardjilov, N.; Hilger, A.; Penumadu, D.; Manke, I.

    2011-01-01

    During the last decade neutron imaging has seen significant improvements in instrumentation, detection and spatial resolution. Additionally, a variety of new applications and methods have been explored. As a consequence of an outstanding development nowadays various techniques of neutron imaging go far beyond a two- and three-dimensional mapping of the attenuation coefficients for a broad range of samples. Neutron imaging has become sensitive to neutron scattering in the small angle scattering range as well as with respect to Bragg scattering. Corresponding methods potentially provide spatially resolved and volumetric data revealing microstructural inhomogeneities, texture variations, crystalline phase distributions and even strains in bulk samples. Other techniques allow for the detection of refractive index distribution through phase sensitive measurements and the utilization of polarized neutrons enables radiographic and tomographic investigations of magnetic fields and properties as well as electrical currents within massive samples. All these advanced methods utilize or depend on wavelength dependent signals, and are hence suited to profit significantly from pulsed neutron sources as will be discussed.

  4. A novel method for active fissile mass estimation with a pulsed neutron source

    International Nuclear Information System (INIS)

    Dubi, C.; Ridnik, T.; Israelashvili, I.; Pedersen, B.

    2013-01-01

    Neutron interrogation facilities for mass evaluation of Special Nuclear Materials (SNM) samples are divided into two main categories: passive interrogation, where all neutron detections are due to spontaneous events, and active interrogation, where fissions are induced on the tested material by an external neutron source. While active methods are, in general, faster and more effective, their analysis is much harder to carry out. In the paper, we will introduce a new formalism for analyzing the detection signal generated by a pulsed source active interrogation facility. The analysis is aimed to distinct between fission neutrons from the main neutron source in the system, and the surrounding “neutron noise”. In particular, we derive analytic expressions for the first three central moments of the number of detections in a given time interval, in terms of the different neutron sources. While the method depends on exactly the same physical assumptions as known models, the simplicity of the suggested formalism allows us to take into account the variance of the external neutron source—an effect that was so far neglected

  5. A novel method for active fissile mass estimation with a pulsed neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Dubi, C., E-mail: chendb331@gmail.com [Physics Department, Nuclear Research Center of the Negev, POB 9001, Beer Sheva (Israel); Ridnik, T.; Israelashvili, I. [Physics Department, Nuclear Research Center of the Negev, POB 9001, Beer Sheva (Israel); Pedersen, B. [Nuclear Security Unit, Institute for Transuranium Elements, Via E. Fermi, 2749 JRC, Ispra (Italy)

    2013-07-01

    Neutron interrogation facilities for mass evaluation of Special Nuclear Materials (SNM) samples are divided into two main categories: passive interrogation, where all neutron detections are due to spontaneous events, and active interrogation, where fissions are induced on the tested material by an external neutron source. While active methods are, in general, faster and more effective, their analysis is much harder to carry out. In the paper, we will introduce a new formalism for analyzing the detection signal generated by a pulsed source active interrogation facility. The analysis is aimed to distinct between fission neutrons from the main neutron source in the system, and the surrounding “neutron noise”. In particular, we derive analytic expressions for the first three central moments of the number of detections in a given time interval, in terms of the different neutron sources. While the method depends on exactly the same physical assumptions as known models, the simplicity of the suggested formalism allows us to take into account the variance of the external neutron source—an effect that was so far neglected.

  6. Development of Portable Pulsed Neutron Generators Utilizing a D-T or D-D Fusion Reaction

    International Nuclear Information System (INIS)

    Nishimura, Kazuya; Miake, Yoshinobu; Kato, Michio; Rintsu, Yukou

    2001-01-01

    Prototypes of sealed neutron tubes in a D-T or D-D fusion reaction for logging while drilling (LWD) were developed; then operational tests were performed to check their functional properties. One of the prototypes passed most of the specified conditions for using LWD. Further studies were needed to put a sealed neutron tube into practical use. For applications to other fields, such as an in situ calibration source for neutron detector efficiencies and an in situ calibration source for fusion systems, a sealed neutron tube is needed to have higher-intensity neutron output and a long life. Thus, the performance of the ion source used in the neutron tube is improved to obtain high gas utilization efficiencies or low-pressure operation with high ionization efficiencies. The characteristics of the new ion sources used in the foregoing sealed neutron tube are discussed in terms of preliminary tests. The aforementioned performances are obtained

  7. Dead time of different neutron detectors associated with a pulsed electronics with current collection

    International Nuclear Information System (INIS)

    Bacconnet, Eugene; Duchene, Jean; Duquesne, Henry; Schmitt, Andre

    1968-01-01

    After having outlined that the development of fast neutron reactor physics, notably kinetics, requires highly efficient neutron detectors and pulse measurement chains able to cope with high counting rates, the authors report the measurement of dead time of various neutron detectors which are used in the experimental study of fast neutron reactors. They present the SAITB 1 electronic measurement set, its components, its general characteristics, the protected connection between the detector and the electronics. They present and report the experiment: generalities about detector location and measurements, studied detectors (fission chambers, boron counters), and report the exploitation of the obtained results (principle, data, high-threshold counting gain) [fr

  8. High-efficiency resonant rf spin rotator with broad phase space acceptance for pulsed polarized cold neutron beams

    Directory of Open Access Journals (Sweden)

    P.-N. Seo

    2008-08-01

    Full Text Available High precision fundamental neutron physics experiments have been proposed for the intense pulsed spallation neutron beams at JSNS, LANSCE, and SNS to test the standard model and search for new physics. Certain systematic effects in some of these experiments have to be controlled at the few ppb level. The NPDGamma experiment, a search for the small parity-violating γ-ray asymmetry A_{γ} in polarized cold neutron capture on parahydrogen, is one example. For the NPDGamma experiment we developed a radio-frequency resonant spin rotator to reverse the neutron polarization in a 9.5  cm×9.5  cm pulsed cold neutron beam with high efficiency over a broad cold neutron energy range. The effect of the spin reversal by the rotator on the neutron beam phase space is compared qualitatively to rf neutron spin flippers based on adiabatic fast passage. We discuss the design of the spin rotator and describe two types of transmission-based neutron spin-flip efficiency measurements where the neutron beam was both polarized and analyzed by optically polarized ^{3}He neutron spin filters. The efficiency of the spin rotator was measured at LANSCE to be 98.8±0.5% for neutron energies from 3 to 20 meV over the full phase space of the beam. Systematic effects that the rf spin rotator introduces to the NPDGamma experiment are considered.

  9. Developments in Pulsed Neutron Activation for Determination of Water Flow in Pipes

    Energy Technology Data Exchange (ETDEWEB)

    Mattsson, Haakan

    2003-06-01

    In PNA (pulsed neutron activation) it is important that the measured data can be related to the total mass flow. In this thesis two fundamental problems of the measurement technique and data treatment have been investigated: transport/mixing and background radiation. The principle of PNA is to introduce a radioactive substance into a pipe by bombarding fluid in the pipe with neutron pulses. The fluid in the pipe is activated and subsequently transported and mixed with the flow. Gamma radiation emitted from the activity is measured with one or two detectors downstream from the activation point. The time-resolved signal from the detectors is used to calculate the average velocity of the water flow. Due to the short distance between the neutron generator and the pipe the activity in the pipe becomes highly inhomogeneous. The transport and mixing of the activity were simulated using colour which was injected into the flow. It was found that the inhomogeneous activity distribution must be taken into account if the precision of the measurements is to be improved. The shape of the background in PNA affects the shape and position of the time spectrum. The nature of the background has been determined using one detector upstream and one downstream of the neutron generator. The background was shown to be caused by {sup 16}N. A method that subtracts the background from the PNA time spectrum was also developed.

  10. Developments in Pulsed Neutron Activation for Determination of Water Flow in Pipes

    International Nuclear Information System (INIS)

    Mattsson, Haakan

    2003-06-01

    In PNA (pulsed neutron activation) it is important that the measured data can be related to the total mass flow. In this thesis two fundamental problems of the measurement technique and data treatment have been investigated: transport/mixing and background radiation. The principle of PNA is to introduce a radioactive substance into a pipe by bombarding fluid in the pipe with neutron pulses. The fluid in the pipe is activated and subsequently transported and mixed with the flow. Gamma radiation emitted from the activity is measured with one or two detectors downstream from the activation point. The time-resolved signal from the detectors is used to calculate the average velocity of the water flow. Due to the short distance between the neutron generator and the pipe the activity in the pipe becomes highly inhomogeneous. The transport and mixing of the activity were simulated using colour which was injected into the flow. It was found that the inhomogeneous activity distribution must be taken into account if the precision of the measurements is to be improved. The shape of the background in PNA affects the shape and position of the time spectrum. The nature of the background has been determined using one detector upstream and one downstream of the neutron generator. The background was shown to be caused by 16 N. A method that subtracts the background from the PNA time spectrum was also developed

  11. Assessment of Laser-Driven Pulsed Neutron Sources for Poolside Neutron-based Advanced NDE – A Pathway to LANSCE-like Characterization at INL

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Markus [Technische Univ. Darmstadt (Germany); Vogel, Sven C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bourke, Mark Andrew M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Fernandez, Juan Carlos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mocko, Michael Jeffrey [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Glenzer, Siegfried [Stanford Univ., CA (United States); Leemans, Wim [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Siders, Craig [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Haefner, Constantin [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2017-04-19

    A variety of opportunities for characterization of fresh nuclear fuels using thermal (~25meV) and epithermal (~10eV) neutrons have been documented at Los Alamos National Laboratory. They include spatially resolved non-destructive characterization of features, isotopic enrichment, chemical heterogeneity and stoichiometry. The LANSCE spallation neutron source is well suited in neutron fluence and temporal characteristics for studies of fuels. However, recent advances in high power short pulse lasers suggest that compact neutron sources might, over the next decade, become viable at a price point that would permit their consideration for poolside characterization on site at irradiation facilities. In a laser-driven neutron source the laser is used to accelerate deuterium ions into a beryllium target where neutrons are produced. At this time, the technology is new and their total neutron production is approximately four orders of magnitude less than a facility like LANSCE. However, recent measurements on a sub-optimized system demonstrated >1010 neutrons in sub-nanosecond pulses in predominantly forward direction. The compactness of the target system compared to a spallation target may allow exchanging the target during a measurement to e.g. characterize a highly radioactive sample with thermal, epithermal, and fast neutrons as well as hard X-rays, thus avoiding sample handling. At this time several groups are working on laser-driven neutron production and are advancing concepts for lasers, laser targets, and optimized neutron target/moderator systems. Advances in performance sufficient to enable poolside fuels characterization with LANSCE-like fluence on sample within a decade may be possible. This report describes the underlying physics and state-of-the-art of the laser-driven neutron production process from the perspective of the DOE/NE mission. It also discusses the development and understanding that will be necessary to provide customized capability for

  12. Monte Carlo simulations of the pulsed thermal neutron flux in two-region hydrogenous systems (using standard MCNP data libraries)

    International Nuclear Information System (INIS)

    Wiacek, U.; Krynicka, E.

    2005-02-01

    Monte Carlo simulations of the pulsed neutron experiment in two- region systems (two concentric spheres and two coaxial finite cylinders) are presented. The MCNP code is used. Aqueous solutions of H 3 BO 3 or KCl are used in the inner region. The outer region is the moderator of Plexiglas. Standard data libraries of the thermal neutron scattering cross-sections of hydrogen in hydrogenous substances are used. The time-dependent thermal neutron transport is simulated when the inner region has a constant size and the external size of the surrounding outer region is variable. The time decay constant of the thermal neutron flux in the system is found in each simulation. The results of the simulations are compared with results of real pulsed neutron experiments on the corresponding systems. (author)

  13. Diffusion Parameters of BeO by the Pulsed Neutron Method

    International Nuclear Information System (INIS)

    Joshi, B.V.; Nargundkar, V.R.; Subbarao, K.

    1965-01-01

    The use of the pulsed neutron method for the precise determination of the diffusion parameters of moderators is described. The diffusion parameters of BeO have been obtained by this method. The neutron bursts were produced from a cascade accelerator by pulsing the ion source and using the Be (d, n) reaction. The detector was an enriched boron trifluoride proportional counter. It is shown that by a proper choice of the counter position arid length, and the source position, most of the space harmonics can be eliminated. Any constant background can be accounted for in the calculation of the decay constant. Very large bucklings were not used to avoid time harmonics. Any remaining harmonic content was rendered ineffective by the use of adequate time delay. The decay constant of the fundamental mode of the thermal neutron population was determined for several bucklings. Conditions to be satisfied for an accurate determination of the diffusion cooling constant C are discussed. The following values are obtained for BeO: λ 0 = absorption constant = 156.02 ± 4.37 s -1 D = diffusion coefficient = (1.3334 ± 0.0128) x 10 5 cm 2 /s C = diffusion cooling constant = (-4.8758 ± 0.5846) x 10 5 cm 4 /s. The effect of neglecting the contribution of the B 6 term on the determination of the diffusion parameters was estimated and is shown to be considerable. The reason for the longstanding discrepancy between the values of C obtained for the same moderator by different workers is attributed to this. (author) [fr

  14. Neutron-Gamma Pulse Shape Discrimination With Ne-213 Liquid Scintillator By Using Digital Signal Processing Combined With Similarity Method

    International Nuclear Information System (INIS)

    Mardiyanto

    2008-01-01

    Neutron-Gamma Pulse Shape Discrimination with a NE-213 Liquid Scintillator by Using Digital Signal Processing Combined with Similarity Method. Measurement of mixed neutron-gamma radiation is difficult because a nuclear detector is usually sensitive to both radiations. A new attempt of neutron-gamma pulse shape discrimination for a NE-213 liquid scintillator is presented by using digital signal processing combined with an off-line similarity method. The output pulse shapes are digitized with a high speed digital oscilloscope. The n-γ discrimination is done by calculating the index of each pulse shape, which is determined by the similarity method, and then fusing it with its corresponding pulse height. Preliminary results demonstrate good separation of neutron and gamma-ray signals from a NE-213 scintillator with a simple digital system. The results were better than those with a conventional rise time method. Figure of Merit is used to determine the quality of discrimination. The figure of merit of the discrimination using digital signal processing combined with off-line similarity method are 1.9; 1.7; 1.1; 1.1; and 0.8; on the other hand by using conventional method the rise time are 0.9; 0.9; 0.9; 0.7; and 0.4 for the equivalent electron energy of 800; 278; 139; 69; and 30 keV. (author)

  15. A low background pulsed neutron polyenergetic beam at the ET-RR-1 reactor

    International Nuclear Information System (INIS)

    Adib, M.; Abdel-Kawy, A.; Habib, N.; Abu-El-Ela, M.; Wahba, M.; Kilany, M.

    1991-12-01

    A low background pulsed neutron polyenergetic thermal beam at ET-RR-1 is produced by a rotor and rotating collimator suspended in magnetic fields. Each of them is mounted on its mobile platform and whose centres are 66 cm apart, rotating synchronously at speeds up to 16000 rpm. It was found that the neutron burst produced by the rotor with almost 100% transmission passes through the collimator, when the rotation phase between them is 28.8 deg. Moreover the background level achieved at the detector position is low, constant and free from peaks due to gamma rays and fast neutrons accompanying the reactor thermal beam. (author). 12 refs, 3 figs

  16. Heuristic derivation of the Rossi-alpha formula for a pulsed neutron source

    International Nuclear Information System (INIS)

    Baeten, P.

    2004-01-01

    Expressions for the Rossi-alpha distribution for a pulsed neutron source were derived using a heuristic derivation based on the method of joint detection probability. This heuristic technique was chosen over the more rigorous master equation method due to its simplicity and the complementary of both techniques. The derived equations also take into account the presence of delayed neutrons and intrinsic neutron sources which often cannot be neglected in source-driven subcritical cores. The obtained expressions showed that the ratio of the correlated to the uncorrelated signal in the Rossi-Alpha distribution for a Pulsed Source (RAPS) was strongly increased compared to the case for a standard Rossi-alpha distribution for a continuous source. It was also demonstrated that by using this RAPS technique four independent measurement quantities, instead of three with the standard Rossi-alpha technique, can be determined. Hence, it is no longer necessary to combine the Rossi-alpha technique with another method to measure the reactivity expressed in dollars. Both properties, the increased signal-to-noise ratio of the correlated signal and the measurement of a fourth measurement quantity, make that the RAPS technique is an excellent candidate for the measurement of kinetic parameters in source-driven subcritical assemblies

  17. Small-angle neutron scattering at pulsed sources compared to reactor sources

    International Nuclear Information System (INIS)

    Hjelm, R.P. Jr.; Seeger, P.A.; Thiyagarajan, P.

    1990-01-01

    Detailed comparisons of measurements made on small-angle neutron scattering instruments at pulsed spallation and reactor sources show that the results from the two types of instruments are comparable. It is further demonstrated that spallation instruments are preferable for measurements in the mid-momentum transfer domain or when a large domain is needed. 8 refs., 2 figs

  18. Miscellaneous neutron techniques

    International Nuclear Information System (INIS)

    Iddings, F.A.

    1976-01-01

    Attention is brought to the less often uses of neutrons in the areas of neutron radiography, well logging, and neutron gaging. Emphasis on neutron radiography points toward the isotopic sensitivity of the method versus the classical bulk applications. Also recognized is the ability of neutron radiography to produce image changes that correspond to thickness and density changes obtained in photon radiography. Similarly, neutron gaging applications center on the measurement of radiography. Similarly, neutron gaging applications center on the measurement of water, oil, or plastics in industrial samples. Well logging extends the neutron gaging to encompass many neutron properties and reactions besides thermalization and capture. Neutron gaging also gives information on organic structure and concentrations of a variety of elements or specific compounds in selected matrices

  19. Digital pulse shape discrimination between fast neutrons and gamma rays with para-terphenyl scintillator

    Science.gov (United States)

    Chepurnov, A. S.; Kirsanov, M. A.; Klenin, A. A.; Klimanov, S. G.; Kubankin, A. S.

    2017-12-01

    In the presented work, we investigated several digital methods of a discrimination signals from fast neutrons and gamma quanta. The experimental setup consists of a Pu-Be neutron source, a scintillation detector with an organic para-terphenyl monocrystal, and a digitizer (CAEN DT5730, 500 MS/s). Mixed waveform sequences were stored and then separated by pulse shape. Four methods were used for signals separation. Comparison of the traditional and the new methods of Figure of Merit (FOM) calculation is given. FOM = 1.5 was obtained in our setup for the minimum threshold value. A scintillation detector with a para-terphenyl crystal was used to measure neutron yield in the neutron generator with carbon nanotubes.

  20. Pulse Shape Analysis and Discrimination for Silicon-Photomultipliers in Helium-4 Gas Scintillation Neutron Detector

    Science.gov (United States)

    Barker, Cathleen; Zhu, Ting; Rolison, Lucas; Kiff, Scott; Jordan, Kelly; Enqvist, Andreas

    2018-01-01

    Using natural helium (helium-4), the Arktis 180-bar pressurized gas scintillator is capable of detecting and distinguishing fast neutrons and gammas. The detector has a unique design of three optically separated segments in which 12 silicon-photomultiplier (SiPM) pairs are positioned equilaterally across the detector to allow for them to be fully immersed in the helium-4 gas volume; consequently, no additional optical interfaces are necessary. The SiPM signals were amplified, shaped, and readout by an analog board; a 250 MHz, 14-bit digitizer was used to examine the output pulses from each SiPMpair channel. The SiPM over-voltage had to be adjusted in order to reduce pulse clipping and negative overshoot, which was observed for events with high scintillation production. Pulse shaped discrimination (PSD) was conducted by evaluating three different parameters: time over threshold (TOT), pulse amplitude, and pulse integral. In order to differentiate high and low energy events, a 30ns gate window was implemented to group pulses from two SiPM channels or more for the calculation of TOT. It was demonstrated that pulses from a single SiPM channel within the 30ns window corresponded to low-energy gamma events while groups of pulses from two-channels or more were most likely neutron events. Due to gamma pulses having lower pulse amplitude, the percentage of measured gamma also depends on the threshold value in TOT calculations. Similarly, the threshold values were varied for the optimal PSD methods of using pulse amplitude and pulse area parameters. Helium-4 detectors equipped with SiPMs are excellent for in-the-field radiation measurement of nuclear spent fuel casks. With optimized PSD methods, the goal of developing a fuel cask content monitoring and inspection system based on these helium-4 detectors will be achieved.

  1. Thermoelastic expansion in prompt-critical neutron pulse idealized in a fissile metallic sphere

    International Nuclear Information System (INIS)

    Barroso, D.E.G.; Ribeiro, S.G.

    1985-01-01

    Prompt critical pulses in solid and homogeneous spheres of enriched uranium (93%) and metallic plutonium are studied. The feedback mechanism of the negative inserted reactivity is given by the elastic expansion due to the increase of the temperature in the sphere. Thermomechanical behavior and the capability of the system to become subcritical without a very large increase of energy released in the pulse are analysed. The neutronic and thermoelasticity equations are solved in the time. (M.C.K.) [pt

  2. Status of the intense pulsed neutron source

    International Nuclear Information System (INIS)

    Brown, B.S.; Carpenter, J.M.; Crawford, R.K.; Rauchas, A.V.; Schulke, A.W.; Worlton, T.G.

    1989-01-01

    Since 1981 the average proton currents at IPNS has increased substantially. The reliability has averaged 91%. The moderator has changed from a room temperature polyethylene to cryogenic methane. This report details progress made at IPNS (Intense Pulsed Neutron Source) during the last two years. The topics discussed are the operating status of the accelerator systems, other accelerator activities (such as, IPNS participation in SDI), instrumentation operating at IPNS, chopper development at IPNS, data acquisition, Booster target, moderators and examples of recent scientific results. The ever increasing instrument capability, the Booster target and the very active involvement with the scientific user community guarantees a productive scientific future at IPNS. 9 figs., 3 tabs

  3. Nanosecond neutron generator

    International Nuclear Information System (INIS)

    Lobov, S.I.; Pavlovskaya, N.G.; Pukhov, S.P.

    1991-01-01

    High-voltage nanosecond neutron generator for obtaining neutrons in D-T reaction is described. Yield of 6x10 6 neutron/pulse was generated in a sealed gas-filled diode with a target on the cathode by accelerating pulse voltage of approximately 0.5 MV and length at half-height of 0.5 ns and deuterium pressure of 6x10 -2 Torr. Ways of increasing neutron yield and possibilities of creating generators of nanosecond neutron pulses with great service life are considered

  4. Shallow infiltration processes at Yucca Mountain, Nevada: Neutron logging data 1984--1993

    International Nuclear Information System (INIS)

    Flint, L.E.; Flint, A.L.

    1995-01-01

    To determine site suitability of Yucca Mountain, Nevada, as a potential high-level radioactive waste repository, a study was devised to characterize net infiltration. This study involves a detailed data set produced from 99 neutron boreholes that consisted of volumetric water-content readings with depth from 1984 through 1993 at Yucca Mountain. Boreholes were drilled with minimal disturbance to the surrounding soil or rock in order to best represent field conditions. Boreholes were located in topographic positions representing infiltration zones identified as ridgetops, sideslopes, terraces, and active channels. Through careful field calibration, neutron moisture logs, collected on a monthly basis and representing most of the areal locations at Yucca Mountain, illustrated that the depth of penetration of seasonal moisture, important for escaping loss to evapotranspiration, was influenced by several factors. It was increased (1) by thin soil cover, especially in locations where thin soil is underlain by fractured bedrock; (2) on ridgetops; and (3) during the winter when evapotranspiration is low and runoff is less frequent. This data set helps to provide a seasonal and areal distribution of changes in volumetric water content with which to assess hydrologic processes contributing to net infiltration

  5. Shallow infiltration processes at Yucca Mountain, Nevada - neutron logging data 1984-93

    International Nuclear Information System (INIS)

    Flint, L.E.; Flint, A.L.

    1995-01-01

    To determine site suitability of Yucca Mountain, Nevada, as a potential high-level radioactive waste repository, a study was devised to characterize net infiltration. This study involves a detailed data set produced from 99 neutron boreholes that consisted of volumetric water-content readings with depth from 1984 through 1993 at Yucca Mountain. Boreholes were drilled with minimal disturbance to the surrounding soil or rock in order to best represent field conditions. Boreholes were located in topographic positions representing infiltration zones identified as ridge-tops, sideslopes, terraces, and active channels. Through careful field calibration, neutron moisture logs, collected on a monthly basis and representing most of the areal locations at Yucca Mountain, illustrated that the depth of penetration of seasonal moisture, important for escaping loss to evapotranspiration, was influenced by several factors. It was increased (1) by thin soil cover, especially in locations where thin soil is underlain by fractured bedrock; (2) on ridgetops; and (3) during the winter when evapotranspiration is low and runoff is less frequent. This data set helps to provide a seasonal and areal distribution of changes in volumetric water content with which to assess hydrologic processes contributing to net infiltration

  6. Non-destructive characterization using pulsed fast-thermal neutrons

    International Nuclear Information System (INIS)

    Womble, P.C.

    1995-01-01

    Explosives, illicit drugs, and other contraband materials contain various chemical elements in quantities and ratios that differentiate them from each other and from innocuous substances. Furthermore, the major chemical elements in coal can provide information about various parameters of importance to the coal industry. In both examples, the non-destructive identification of chemical elements can be performed using pulsed fast-thermal neutrons that, through nuclear reactions, excite the nuclei of the various elements. This technique is being currently developed for the dismantling of nuclear weapons classified as trainers, and for the on-line coal bulk analysis. (orig.)

  7. Performance following a 500-675 rad neutron pulse

    International Nuclear Information System (INIS)

    Yochmowitz, M.G.; Brown, G.C.; Hardy, K.A.

    1985-01-01

    A three-light, three-lever discrete avoidance behavioral task was initiated to study the effects of a 500-675 rad neutron pulse upon performance. Eight primates performed the task for 4 h (3.5 h postexposure) on exposure day and for 4 h on each of 3 d postexposure. For the exposure day, five subjects had a decrease in correct responses, seven had increased reaction times, and six experienced productive emesis within 3.5 hours postexposure. Although the performance degradations were not severe, these data suggest that the performance of time critical tasks could be significantly impaired. 10 references

  8. Neutronic design of pulse operation simulating device for in-pile functional test of fusion blanket by MCNP

    Energy Technology Data Exchange (ETDEWEB)

    Nagao, Yoshiharu; Nakamichi, Masaru; Kawamura, Hiroshi [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan)

    2000-03-01

    The pulse operation of a fusion reactor can be simulated in a fission reactor by controlling the neutron flux entering a test section by using a rotating 'hollow cylinder with window' made of hafnium. The rotating cylinder is installed between the test section and the fixed outer neutron absorber cylinder and is also made of hafnium with an opening in the direction to the core center. For gathering engineering data for the tritium breeding blanket such as characteristics of temperature change, tritium release and recovery, etc., it is desirable that the ratio of minimum to maximum thermal neutron fluxes is greater than 1:10. Design calculations were performed for the test assembly which considered local neutronic effects and the mechanical constraints of the device. From the results of these calculations, the ratio of minimum to maximum thermal neutron flux under irradiation would be about 1:10 using a pulse operation simulating device which has a thickness of 6.5 mm and a 150deg window angle for the rotating hollow cylinder and 5.0 mm in thickness of fixed neutron absorber. (author)

  9. Simulation for developing new pulse neutron spectrometers I. Creation of new McStas components of moderators of JSNS

    CERN Document Server

    Tamura, I; Arai, M; Harada, M; Maekawa, F; Shibata, K; Soyama, K

    2003-01-01

    Moderators components of the McStas code have been created for the design of JSNS instruments. Three cryogenic moderators are adopted in JSNS, one is coupled H sub 2 moderators for high intensity experiments and other two are decoupled H sub 2 with poisoned or unpoisoned for high resolution moderators. Since the characteristics of neutron beams generated from moderators make influence on the performance of pulse neutron spectrometers, it is important to perform the Monte Carlo simulation with neutron source component written precisely. The neutron spectrum and time structure were calculated using NMTC/JAERI97 and MCNP4a codes. The simulation parameters, which describe the pulse shape over entire spectrum as a function of time, are optimized. In this paper, the creation of neutron source components for port No.16 viewed to coupled H sub 2 moderator and for port No.11 viewed to decoupled H sub 2 moderator of JSNS are reported.

  10. Neutron pulse propagation in natural UO sub(2) subcritical assembly moderated by heavy water

    International Nuclear Information System (INIS)

    Prado Souza, R.M.G. do.

    1976-01-01

    Short neutron bursts are fed to the graphite base of CAPITU, a D sub(2)O - natural uranium subcritical assembly. Due to the dispersive properties of the media the wave -components of the neutron pulses are attenuated and phase shifted along the axial direction. The experimental impulse response is Fourier transformed to yield the system's dispersion law, a relationship connecting the neutron diffusion parameters and the inverse complex relaxation length K (ω). The experimental results for five assemblies studied in CAPITU are compared with the theoretical dispersion law obtained from the two group diffusion theory. (author)

  11. The effect of an accretion disk on coherent pulsed emission from weakly magnetized neutron stars

    International Nuclear Information System (INIS)

    Asaoka, Ikuko; Hoshi, Reiun.

    1989-01-01

    Using a simple model for hot spots formed on the magnetic polar regions we calculate the X-ray pulse profiles expected from bright low-mass X-ray binaries. We assume that neutron stars in close binary systems are surrounded by accretion disks extending down in the vicinity of their surfaces. Even partial eclipses of a hot spot by the accretion disk change the coherent pulsed fraction and, in some cases, the phase of pulsations by almost 180deg. Coherent pulsations are clearly seen even for sufficiently compact model neutron stars, if the hot spots emit isotropic or fan-beam radiation. In the case of pencil-beam radiation, coherent pulsations are also seen if the cap-opening angle is less than ∼60deg, while the inclination angle is larger than 68deg. Gravitational lensing alone does not smear coherent pulsations in moderately weak magnetized neutron stars in the presence of an absorbing accretion disk. (author)

  12. Monte Carlo Numerical Models for Nuclear Logging Applications

    Directory of Open Access Journals (Sweden)

    Fusheng Li

    2012-06-01

    Full Text Available Nuclear logging is one of most important logging services provided by many oil service companies. The main parameters of interest are formation porosity, bulk density, and natural radiation. Other services are also provided from using complex nuclear logging tools, such as formation lithology/mineralogy, etc. Some parameters can be measured by using neutron logging tools and some can only be measured by using a gamma ray tool. To understand the response of nuclear logging tools, the neutron transport/diffusion theory and photon diffusion theory are needed. Unfortunately, for most cases there are no analytical answers if complex tool geometry is involved. For many years, Monte Carlo numerical models have been used by nuclear scientists in the well logging industry to address these challenges. The models have been widely employed in the optimization of nuclear logging tool design, and the development of interpretation methods for nuclear logs. They have also been used to predict the response of nuclear logging systems for forward simulation problems. In this case, the system parameters including geometry, materials and nuclear sources, etc., are pre-defined and the transportation and interactions of nuclear particles (such as neutrons, photons and/or electrons in the regions of interest are simulated according to detailed nuclear physics theory and their nuclear cross-section data (probability of interacting. Then the deposited energies of particles entering the detectors are recorded and tallied and the tool responses to such a scenario are generated. A general-purpose code named Monte Carlo N– Particle (MCNP has been the industry-standard for some time. In this paper, we briefly introduce the fundamental principles of Monte Carlo numerical modeling and review the physics of MCNP. Some of the latest developments of Monte Carlo Models are also reviewed. A variety of examples are presented to illustrate the uses of Monte Carlo numerical models

  13. Direct Fast-Neutron Detection

    International Nuclear Information System (INIS)

    DC Stromswold; AJ Peurrung; RR Hansen; PL Reeder

    2000-01-01

    Direct fast-neutron detection is the detection of fast neutrons before they are moderated to thermal energy. We have investigated two approaches for using proton-recoil in plastic scintillators to detect fast neutrons and distinguish them from gamma-ray interactions. Both approaches use the difference in travel speed between neutrons and gamma rays as the basis for separating the types of events. In the first method, we examined the pulses generated during scattering in a plastic scintillator to see if they provide a means for distinguishing fast-neutron events from gamma-ray events. The slower speed of neutrons compared to gamma rays results in the production of broader pulses when neutrons scatter several times within a plastic scintillator. In contrast, gamma-ray interactions should produce narrow pulses, even if multiple scattering takes place, because the time between successive scattering is small. Experiments using a fast scintillator confirmed the presence of broader pulses from neutrons than from gamma rays. However, the difference in pulse widths between neutrons and gamma rays using the best commercially available scintillators was not sufficiently large to provide a practical means for distinguishing fast neutrons and gamma rays on a pulse-by-pulse basis. A faster scintillator is needed, and that scintillator might become available in the literature. Results of the pulse-width studies were presented in a previous report (peurrung et al. 1998), and they are only summarized here

  14. Exploitation of the Fourier chopper in neutron diffractometry at pulsed sources

    International Nuclear Information System (INIS)

    Hiismaeki, P.; Poeyry, H.; Tiitta, A.

    1988-01-01

    The application of the Fourier chopper in the reverse time-of-flight mode to upgrading the performance of neutron powder diffractometry at pulsed sources is considered. Exploitation of a dual-delay-line binary correlator is suggested and a comprehensive analysis of the necessary data acquisition process is given. The best benefit is shown to be achievable at intensity optimized moderators. (orig.)

  15. The application of radiation logs to groundwater hydrology

    Energy Technology Data Exchange (ETDEWEB)

    Scott Keys, W [United States Geological Survey, Denver, CO (United States)

    1967-05-15

    The drilling of exploratory holes to determine the availability of groundwater and to plan the most economical methods of water development is expensive. The only technique available at present for obtaining geological and hydrological information through the casing of pre-existing water wells and other boreholes is by radiation logging. Up to now these logging techniques have been little used in groundwater hydrology. This report describes inexpensive portable radiation logging equipment that is available or has been developed for groundwater studies in connection with a general research project on the application of borehole geophysics in groundwater hydrology. It is possible to obtain data on the following: the source, velocity, and chemical quality of groundwater; the location, extent, geometry, bulk density, porosity, permeability, and specific yield of aquifers and associated strata; and the position of casings, casing collars, leaks, perforations, and cement. The radiation logs employed include natural gamma, gamma-gamma, neutron-gamma. neutron epithermal-neutron. and radioactive tracer. The following radioisotopes are utilized: cobalt-60, plutonium-239, americium-241, and iodine-131. Typical radiation logs obtained by the various techniques are described and examples are given of practical applications of radiation logging to groundwater investigations. The applications cited are studies of perched water in basaltic rocks and associated sedimentary strata; the porosity, moisture content, and position of zones into which water was injected in volcanic tuff; the position of the interface between brine and fresh water in fine-grained carbonate rocks and associated fine clastic rocks; the interpretation of porosity from a neutron log; and the location by means of a radioactive tracer of the more permeable fracture zones in a well penetrating crystalline rock. (author)

  16. Area radiation monitor at the intense pulsed-neutron source

    International Nuclear Information System (INIS)

    Eichholz, J.J.; Lynch, F.J.; Mundis, R.L.; Howe, M.L.; Dolecek, E.H.

    1981-01-01

    A tissue-equivalent ionization chamber with associated circuitry has been developed for area radiation monitoring in the Intense Pulsed-Neutron Source (IPNS) facility at Argonne National Laboratory. The conventional chamber configuration was modified in order to increase the electric field and effective volume thereby achieving higher sensitivity and linearity. The instrument provides local and remote radiation level indications and a high level alarm. Twenty-four of these instruments were fabricated for use at various locations in the experimental area of the IPNS-1 facility

  17. Experimental and numerical investigations of radiation characteristics of Russian portable/compact pulsed neutron generators: ING-031, ING-07, ING-06 and ING-10-20-120

    International Nuclear Information System (INIS)

    Chernikova, D.; Romodanov, V.L.; Belevitin, A.G.; Afanas'ev, V.V.; Sakharov, V.K.; Bogolubov, E.P.; Ryzhkov, V.I.; Khasaev, T.O.; Sladkov, A.A.; Bitulev, A.A.

    2014-01-01

    The present paper discusses results of full-scale experimental and numerical investigations of influence of construction materials of portable pulsed neutron generators ING-031, ING-07, ING-06 and ING-10-20-120 (VNIIA, Russia) to their radiation characteristics formed during and after an operation (shutdown period). In particular, it is shown that an original monoenergetic isotropic angular distribution of neutrons emitted by TiT target changes into the significantly anisotropic angular distribution with a broad energy spectrum stretching to the thermal region. Along with the low-energetic neutron part, a significant amount of photons appears during the operation of generators. In the pulse mode of operation of neutron generator, a presence of the construction materials leads to the “tailing” of the original neutron pulse and the appearance of an accompanying photon pulse at ∼3ns after the instant neutron pulse. In addition to that, reactions of neutron capture and inelastic scattering lead to the creation of radioactive nuclides, such as 58 Co, 62 Cu, 64 Cu and 18 F, which form the so-called activation radiation. Thus, the selection of a portable neutron generator for a particular type of application has to be done considering radiation characteristics of the generator itself. This paper will be of interest to users of neutron generators, providing them with valuable information about limitations of a specific generator and with recommendations for improving the design and performance of the generator as a whole

  18. The WNR facility - a pulsed spallation neutron source at the Los Alamos Scientific Laboratory

    International Nuclear Information System (INIS)

    Russell, G.J.; Lisowski, P.W.; King, N.S.P.

    1978-01-01

    The Weapons Neutron Research facility (WNR) at the Los Alamos Scientific Laboratory is the first operating example of a new class of pulsed neutron sources using the X(p,n)Y spallation reaction. At present, up to 10 microamperes of 800-MeV protons from the Clinton P. Anderson Meson Physics Facility (LAMPF) linear accelerator bombard a Ta target to produce an intense white-neutron spectrum from about 800 MeV to 100 keV. The Ta target can be coupled with CH 2 and H 2 O moderators to produce neutrons of lower energy. The time structure of the WNR proton beam may be varied to optimize neutron time-of-flight (TOF) measurements covering the energy range from several hundred MeV to a few meV. The neutronics of the WNR target and target/moderator configurations have been calculated from 800 MeV to 0.5 eV. About 11 neutrons per proton are predicted for the existing Ta target. Some initial neutron TOF data are presented and compared with calculations

  19. Intercomparison of radiation protection instrumentation in a pulsed neutron field

    Energy Technology Data Exchange (ETDEWEB)

    Caresana, M., E-mail: marco.caresana@polimi.it [Politecnico di Milano, CESNEF, Dipartimento di Energia, via Ponzio 34/3, 20133 Milano (Italy); Denker, A. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Esposito, A. [IFNF-LNF, FISMEL, via E. Fermi 40, 00044 Frascati (Italy); Ferrarini, M. [CNAO, Via Privata Campeggi, 27100 Pavia (Italy); Golnik, N. [Institute of Metrology and Biomedical Engineering, Warsaw University of Technology, Sw. A. Boboli 8, 02-525 Warsaw (Poland); Hohmann, E. [Paul Scherrer Institut (PSI), Radiation Metrology Section, CH-5232 Villigen PSI (Switzerland); Leuschner, A. [Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22603 Hamburg (Germany); Luszik-Bhadra, M. [Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig (Germany); Manessi, G. [CERN, 1211 Geneva 23 (Switzerland); University of Liverpool, Department of Physics, L69 7ZE Liverpool (United Kingdom); Mayer, S. [Paul Scherrer Institut (PSI), Radiation Metrology Section, CH-5232 Villigen PSI (Switzerland); Ott, K. [Helmholtz-Zentrum Berlin, BESSYII, Albert-Einstein-Str.15, 12489 Berlin (Germany); Röhrich, J. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Silari, M. [CERN, 1211 Geneva 23 (Switzerland); Trompier, F. [Institute for Radiological Protection and Nuclear Safety, F-92262 Fontenay aux Roses (France); Volnhals, M.; Wielunski, M. [Helmholtz Zentrum München, Ingolstädter Landstr. 1, D-85764 Neuherberg (Germany)

    2014-02-11

    In the framework of the EURADOS working group 11, an intercomparison of active neutron survey meters was performed in a pulsed neutron field (PNF). The aim of the exercise was to evaluate the performances of various neutron instruments, including commercially available rem-counters, personal dosemeters and instrument prototypes. The measurements took place at the cyclotron of the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH. The cyclotron is routinely used for proton therapy of ocular tumours, but an experimental area is also available. For the therapy the machine accelerates protons to 68 MeV. The interaction of the proton beam with a thick tungsten target produces a neutron field with energy up to about 60 MeV. One interesting feature of the cyclotron is that the beam can be delivered in bursts, with the possibility to modify in a simple and flexible way the burst length and the ion current. Through this possibility one can obtain radiation bursts of variable duration and intensity. All instruments were placed in a reference position and irradiated with neutrons delivered in bursts of different intensity. The analysis of the instrument response as a function of the burst charge (the total electric charge of the protons in the burst shot onto the tungsten target) permitted to assess for each device the dose underestimation due to the time structure of the radiation field. The personal neutron dosemeters were exposed on a standard PMMA slab phantom and the response linearity was evaluated.

  20. Directional epithermal neutron detector

    International Nuclear Information System (INIS)

    Givens, W.W.; Mills, W.R. Jr.

    1986-01-01

    A borehole tool for epithermal neutron die-away logging of subterranean formations surrounding a borehole is described which consists of: (a) a pulsed source of fast neutrons for irradiating the formations surrounding a borehole, (b) at least one neutron counter for counting epithermal neutrons returning to the borehole from the irradiated formations, (c) a neutron moderating material, (d) an outer thermal neutron shield providing a housing for the counter and the moderating material, (e) an inner thermal neutron shield dividing the housing so as to provide a first compartment bounded by the inner thermal neutron shield and a first portion of the outer thermal neutron shield and a second compartment bounded by the inner thermal neutron shield and a second portion of the outer thermal neutron shield, the counter being positioned within the first compartment and the moderating material being positioned within the second compartment, and (f) means for positioning the borehole tool against one side of the borehole wall and azimuthally orienting the borehole tool such that the first chamber is in juxtaposition with the borehole wall, the formation epithermal neutrons penetrating into the first chamber through the first portion of the outer thermal neutron shield are detected by the neutron counter for die-away measurement, thereby maximizing the directional sensitivty of the neutron counter to formation epithermal neutrons, the borehole fluid epithermal neutrons penetrating into the second chamber through the second chamber through the second portion of the outer thermal neutron shield are largely slowed down and lowered in energy by the moderating material and absorbed by the inner thermal neutron shield before penetrating into the first chamber, thereby minimizing the directional sensitivity of the neutron counter to borehole fluid epithermal neutrons

  1. Semi-automatic logarithmic converter of logs

    International Nuclear Information System (INIS)

    Gol'dman, Z.A.; Bondar's, V.V.

    1974-01-01

    Semi-automatic logarithmic converter of logging charts. An original semi-automatic converter was developed for use in converting BK resistance logging charts and the time interval, ΔT, of acoustic logs from a linear to a logarithmic scale with a specific ratio for subsequent combining of them with neutron-gamma logging charts in operative interpretation of logging materials by a normalization method. The converter can be used to increase productivity by giving curves different from those obtained in manual, pointwise processing. The equipment operates reliably and is simple in use. (author)

  2. Determination of reactivity of multiplying systems filled with spherical HTGR-fuel elements using kinetic methods with regard to the pulsed-neutron method

    International Nuclear Information System (INIS)

    Drueke, V.

    1978-06-01

    At three critical or subcritical facilities - two of them filled with spherical HTGR-fuel elements - the reactivity is determined using kinetic methods. Besides the inverskinetic method the applicability of the pulsed-neutron method is investigated. The experimental results using the pulsed-neutron method are compared partly with the inverskinetic method and partly with diffusion-calculations. It is shown, that in the HTGR the space dependence of the reactivity in radial direction is not remarkable in spite of the 'kinetic distortion'; on the contrary in axial direction - the direction of the external neutron source - space dependent reactivity worths are measured. The results of the pulsed-neutron methods of Sjoestrand and Simmons-King are rather good applicable in all configurations. For the method of Sjoestrand it is necessary to select the detector positions, whereas for Simmons-King the calculated life-time determines the results. Therefore it is proposed to compare calculated and measured decay constants of the prompt neutron field in future. (orig.) [de

  3. Staged Z-pinch Experiments at the 1MA Zebra pulsed-power generator: Neutron measurements

    Science.gov (United States)

    Ruskov, Emil; Darling, T.; Glebov, V.; Wessel, F. J.; Anderson, A.; Beg, F.; Conti, F.; Covington, A.; Dutra, E.; Narkis, J.; Rahman, H.; Ross, M.; Valenzuela, J.

    2017-10-01

    We report on neutron measurements from the latest Staged Z-pinch experiments at the 1MA Zebra pulsed-power generator. In these experiments a hollow shell of argon or krypton gas liner, injected between the 1 cm anode-cathode gap, compresses a deuterium plasma target of varying density. Axial magnetic field Bz neutron Time of Flight (nTOF) detectors are augmented with a large area ( 1400 cm2) liquid scintillator detector to which fast gatedPhotek photomultipliers are attached. Sample data from these neutron diagnostics systems is presented. Consistently high neutron yields YDD >109 are measured, with highest yield of 2.6 ×109 . A pair of horizontally and vertically placed plastic scintillator nTOFs suggest isotropic i.e. thermonuclear origin of the neutrons produced. nTOF data from the liquid scintillator detector was cross-calibrated with the silver activation detector, and can be used for accurate calculation of the neutron yield. Funded by the Advanced Research Projects Agency - Energy, under Grant Number DE-AR0000569.

  4. Neutron Imaging at Compact Accelerator-Driven Neutron Sources in Japan

    Directory of Open Access Journals (Sweden)

    Yoshiaki Kiyanagi

    2018-03-01

    Full Text Available Neutron imaging has been recognized to be very useful to investigate inside of materials and products that cannot be seen by X-ray. New imaging methods using the pulsed structure of neutron sources based on accelerators has been developed also at compact accelerator-driven neutron sources and opened new application fields in neutron imaging. The world’s first dedicated imaging instrument at pulsed neutron sources was constructed at J-PARC in Japan owing to the development of such new methods. Then, usefulness of the compact accelerator-driven neutron sources in neutron science was recognized and such facilities were newly constructed in Japan. Now, existing and new sources have been used for neutron imaging. Traditional imaging and newly developed pulsed neutron imaging such as Bragg edge transmission have been applied to various fields by using compact and large neutron facilities. Here, compact accelerator-driven neutron sources used for imaging in Japan are introduced and some of their activities are presented.

  5. A l-nCi/g sensitivity transuranic waste assay system using pulsed neutron interrogation

    International Nuclear Information System (INIS)

    Kunz, W.E.; Atencio, J.D.; Caldwell, J.T.

    1980-01-01

    We have developed a pulsed thermal neutron interrogation system and have demonstrated a sub-1-nCi/g assay sensitivity for high density TRU wastes contained in 200-liter barrels. We detect prompt fission neutrons, resulting in greatly enhanced sensitivity compared to techniques in which delayed fission neutrons are detected. We observe a linear assay response over at least three orders of magnitude in 235 U (or 239 Pu) mass. We also have measured a flat (to +-10%) interrogation flux profile throughout the volume of a 200-liter barrel filled with 200 kg of sand and vermiculite, which indicates flatness of response to fissile material at different locations within the barrel

  6. Fast counting electronics for neutron coincidence counting

    International Nuclear Information System (INIS)

    Swansen, J.E.

    1987-01-01

    This patent describes a high speed circuit for accurate neutron coincidence counting comprising: neutron detecting means for providing an above-threshold signal upon neutron detection; amplifying means inputted by the neutron detecting means for providing a pulse output having a pulse width of about 0.5 microseconds upon the input of each above threshold signal; digital processing means inputted by the pulse output of the amplifying means for generating a pulse responsive to each input pulse from the amplifying means and having a pulse width of about 50 nanoseconds effective for processing an expected neutron event rate of about 1 Mpps: pulse stretching means inputted by the digital processing means for producing a pulse having a pulse width of several milliseconds for each pulse received form the digital processing means; visual indicating means inputted by the pulse stretching means for producing a visual output for each pulse received from the digital processing means; and derandomizing means effective to receive the 50 ns neutron event pulses from the digital processing means for storage at a rate up to the neutron event rate of 1 Mpps and having first counter means for storing the input neutron event pulses

  7. Brighter H- source for the intense pulsed neutron source accelerator system

    International Nuclear Information System (INIS)

    Stipp, V.; DeWitt, A.; Madsen, J.

    1983-01-01

    Further increases in the beam intensity of the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory required the replacement of the H - source with a higher current source. A magnetron ion source of Fermi National Accelerator Laboratory (FNAL) design was adapted with a grooved cathode to provide a stable 40 to 50 mA of beam operating at 30 Hz for up to a 90 μs pulse duration. Problems of space charge blowup due to the lack of neutralization of the H - beam were solved by injecting additional gs into the 20 keV transport system. The source has recently been installed in the machine and the available input to the accelerator has more than doubled

  8. Neutron scattering instrumentation for biology at spallation neutron sources

    Energy Technology Data Exchange (ETDEWEB)

    Pynn, R. [Los Alamos National Laboratory, NM (United States)

    1994-12-31

    Conventional wisdom holds that since biological entities are large, they must be studied with cold neutrons, a domain in which reactor sources of neutrons are often supposed to be pre-eminent. In fact, the current generation of pulsed spallation neutron sources, such as LANSCE at Los Alamos and ISIS in the United Kingdom, has demonstrated a capability for small angle scattering (SANS) - a typical cold- neutron application - that was not anticipated five years ago. Although no one has yet built a Laue diffractometer at a pulsed spallation source, calculations show that such an instrument would provide an exceptional capability for protein crystallography at one of the existing high-power spoliation sources. Even more exciting is the prospect of installing such spectrometers either at a next-generation, short-pulse spallation source or at a long-pulse spallation source. A recent Los Alamos study has shown that a one-megawatt, short-pulse source, which is an order of magnitude more powerful than LANSCE, could be built with today`s technology. In Europe, a preconceptual design study for a five-megawatt source is under way. Although such short-pulse sources are likely to be the wave of the future, they may not be necessary for some applications - such as Laue diffraction - which can be performed very well at a long-pulse spoliation source. Recently, it has been argued by Mezei that a facility that combines a short-pulse spallation source similar to LANSCE, with a one-megawatt, long-pulse spallation source would provide a cost-effective solution to the global shortage of neutrons for research. The basis for this assertion as well as the performance of some existing neutron spectrometers at short-pulse sources will be examined in this presentation.

  9. A pulsed neutron monochromatic beam at the ET-RR-1 reactor

    International Nuclear Information System (INIS)

    Adib, M.; Abdel-Kawy, A.; Eid, Y.; Maayouf, R.M.A.

    1985-01-01

    A pulsed neutron monochromatic beam, at the ET-RR-1 reactor, is produced by two 32 cm diameter rotors suspended in magnetic fields, whose centres are 126 cm apart rotating at speeds up to 16,000 rev/min. Each of the rotors has two slots, which are of constant cross-section in area - 7x10mm 2 , and are curved so that they have a maximum transmission for neutrons whose speed is 8.2 times that of the rotor tip. The jitter of the phase between the rotors at different rotation rates is found not to exceed +-1 μs. It has been found that both the observed time distribution and the TOF distribution of the neutrons at different rotation rates are in good agreement with the calculated ones. The observed intensity of the monochromatic neutrons of wavelength 2.74+-0.09 A, obtained by the rotors rotating at a speed of 10,500 rev/min with 864+-1 μs difference in phase between them, is 66.8 n/s. This value is found to be less than the predicted one by a factor of 5.5. (author)

  10. Neutron kinetics in moderators and SNM detection through epithermal-neutron-induced fissions

    Energy Technology Data Exchange (ETDEWEB)

    Gozani, Tsahi, E-mail: tgmaven@gmail.com [1050 Harriet St., Palo Alto, CA 94301 (United States); King, Michael J. [Rapiscan Laboratories Inc., 520 Almanor Ave., Sunnyvale, CA 94085 (United States)

    2016-01-01

    Extension of the well-established Differential Die Away Analysis (DDAA) into a faster time domain, where more penetrating epithermal neutrons induce fissions, is proposed and demonstrated via simulations and experiments. In the proposed method the fissions stimulated by thermal, epithermal and even higher-energy neutrons are measured after injection of a narrow pulse of high-energy 14 MeV (d,T) or 2.5 MeV (d,D) source neutrons, appropriately moderated. The ability to measure these fissions stems from the inherent correlation of neutron energy and time (“E–T” correlation) during the process of slowing down of high-energy source neutrons in common moderating materials such as hydrogenous compounds (e.g., polyethylene), heavy water, beryllium and graphite. The kinetic behavior following injection of a delta-function-shaped pulse (in time) of 14 MeV neutrons into such moderators is studied employing MCNPX simulations and, when applicable, some simple “one-group” models. These calculations served as a guide for the design of a source moderator which was used in experiments. Qualitative relationships between slowing-down time after the pulse and the prevailing neutron energy are discussed. A laboratory system consisting of a 14 MeV neutron generator, a polyethylene-reflected Be moderator, a liquid scintillator with pulse-shape discrimination (PSD) and a two-parameter E–T data acquisition system was set up to measure prompt neutron and delayed gamma-ray fission signatures in a 19.5% enriched LEU sample. The measured time behavior of thermal and epithermal neutron fission signals agreed well with the detailed simulations. The laboratory system can readily be redesigned and deployed as a mobile inspection system for SNM in, e.g., cars and vans. A strong pulsed neutron generator with narrow pulse (<75 ns) at a reasonably high pulse frequency could make the high-energy neutron induced fission modality a realizable SNM detection technique.

  11. Nuclear cross section library for oil well logging analysis

    International Nuclear Information System (INIS)

    Kodeli, I.; Kitsos, S.; Aldama, D.L.; Zefran, B.

    2003-01-01

    As part of the IRTMBA (Improved Radiation Transport Modelling for Borehole Applications) Project of the EU Community's 5 th Programme a special purpose multigroup cross section library to be used in the deterministic (as well as Monte Carlo) oil well logging particle transport calculations was prepared. This library is expected to improve the prediction of the neutron and gamma spectra at the detector positions of the logging tool, and their use for the interpretation of the neutron logging measurements was studied. Preparation and testing of this library is described. (author)

  12. Physical and measuring principles of nuclear well logging techniques

    International Nuclear Information System (INIS)

    Loetzsch, U.; Winkler, R.

    1981-01-01

    Proceeding from the general task of nuclear geophysics as a special discipline of applied geophyscis, the essential physical problems of nuclear well logging techniques are considered. Particularly, the quantitative relationship between measured values and interesting geologic parameters to be determined are discussed taking into account internal and external perturbation parameters. Resulting from this study, the technological requirements for radiation sources and their shielding, for detectors, electronic circuits in logging tools, signal transmission by cable and recording equipment are derived, and explained on the basis of examples of gamma-gamma and neutron-neutron logging. (author)

  13. Pulsed neutron generators based on the sealed chambers of plasma focus design with D and DT fillings

    International Nuclear Information System (INIS)

    Yurkov, D I; Dulatov, A K; Lemeshko, B D; Golikov, A V; Andreev, D A; Mikhailov, Yu V; Prokuratov, I A; Selifanov, A N

    2015-01-01

    Development of neutron generators using plasma focus (PF) chambers is being conducted in the All-Russia Scientific Research Institute of Automatics (VNIIA) during more than 25 years. PF is a source of soft and hard x-rays and neutrons 2.5 MeV (D) or 14 MeV (DT). Pulses of x-rays and neutrons have a duration of about several tens of nanoseconds, which defines the scope of such generators—the study of ultrafast processes. VNIIA has developed a series of pulse neutron generators covering the range of outputs 10 7 –10 12 n/pulse with resources on the order of 10 3 –10 4 switches, depending on purposes. Generators have weights in the range of 30–700 kg, which allows referring them to the class of transportable generators. Generators include sealed PF chambers, whose manufacture was mastered by VNIIA vacuum tube production plant. A number of optimized PF chambers, designed for use in generators with a certain yield of neutrons has been developed. The use of gas generator based on gas absorber of hydrogen isotopes, enabled to increase the self-life and resource of PF chambers. Currently, the PF chambers withstand up to 1000 switches and have the safety of not less than 5 years. Using a generator with a gas heater, significantly increased security of PF chambers, because deuterium-tritium mixture is released only during work, other times it is in a bound state in the working element of the gas generator. (paper)

  14. Electron volt spectroscopy on a pulsed neutron source using resonance absorption filters

    International Nuclear Information System (INIS)

    Newport, R.J.; Williams, W.G.

    1983-05-01

    The design aspects of an inelastic neutron spectrometer based on energy selection by the resonance absorption filter difference method are discussed. Detailed calculations of the accessible dynamical range (Q, ω), energy and momentum transfer resolutions and representative count rates are presented for Sm and Ta resonance filters in an inverse geometry spectrometer on a high intensity pulsed source such as the RAL Spallation Neutron Source (SNS). A discussion is given of the double-difference method, which provides a means of improving the resonance attenuation peak shape. As a result of this study, as well as preliminary experimental results, recommendations are made for the future development of the technique. (author)

  15. A proposed experiment for studying the direct neutron-neutron interaction

    International Nuclear Information System (INIS)

    Hassan Fikry, A.R.; Maayouf, R.M.A.

    1979-01-01

    An experiment for studying the direct neutron-neutron interaction is suggested. The experiment is based on the combined use of an accelerator, e.g., an electron linear accelerator, together with a mobile pulsed reactor; or using a pulsed beam reactor together with a mobile neutron generator

  16. Time-of-flight pulsed neutron diffraction of molten salts

    Energy Technology Data Exchange (ETDEWEB)

    Fukushima, Y; Misawa, M; Suzuki, K [Tohoku Univ., Sendai (Japan). Research Inst. for Iron, Steel and Other Metals

    1975-06-01

    In this work, the pulsed neutron diffraction of molten alkali metal nitrate and bismuth trihalide was measured by the time-of-flight method. An electron linear accelerator was used as the pulsed neutron source. All the measurements were carried out with the T-O-F neutron diffractometer installed on the 300 MeV electron lineac. Molten NaNO/sub 3/ and RbNO/sub 3/ were adopted as the samples for alkali metal nitrate. The measurement is in progress for KNO/sub 3/ and LiNO/sub 3/. As the first step of the study on bismuth-bismuth trihalide system, the temperature dependence of structure factors was observed for BiCl/sub 3/, BiBr/sub 3/ and BiI/sub 3/ in the liquid state. The structure factors Sm(Q) for molten NaNO/sub 3/ at 340/sup 0/C and RbNO/sub 3/ at 350/sup 0/C were obtained, and the form factor F/sub 1/(Q) for single NO/sub 3//sup -/ radical with equilateral triangle structure was calculated. In case of molten NaNO/sub 3/, the first peak of Sm(Q) is simply smooth and a small hump can be observed in the neighbourhood of the first minimum Q position. The first peak of Sm(Q) for molten RbNO/sub 3/ is divided into two peaks, whereas a hump at the first minimum becomes big, and shifts to the low Q side of the second peak. The size of the NO/sub 3//sup -/ radical in molten NaNO/sub 3/ is a little smaller than that in molten RbNO/sub 3/. The values of the bond length in the NO/sub 3//sup -/ radical are summarized for crystal state and liquid state. The temperature dependence of the structure factor S(Q) was observed for BiCl/sub 3/, BiBr/sub 3/ and BiI/sub 3/, and shown in a figure.

  17. Fissile material detection and control facility with pulsed neutron sources and digital data processing

    International Nuclear Information System (INIS)

    Romodanov, V.L.; Chernikova, D.N.; Afanasiev, V.V.

    2010-01-01

    Full text: In connection with possible nuclear terrorism, there is long-felt need of devices for effective control of radioactive and fissile materials in the key points of crossing the state borders (airports, seaports, etc.), as well as various customs check-points. In International Science and Technology Center Projects No. 596 and No. 2978, a new physical method and digital technology have been developed for the detection of fissile and radioactive materials in models of customs facilities with a graphite moderator, pulsed neutron source and digital processing of responses from scintillation PSD detectors. Detectability of fissile materials, even those shielded with various radiation-absorbing screens, has been shown. The use of digital processing of scintillation signals in this facility is a necessary element, as neutrons and photons are discriminated in the time dependence of fissile materials responses at such loads on the electronic channels that standard types of spectrometers are inapplicable. Digital processing of neutron and photon responses practically resolves the problem of dead time and allows implementing devices, in which various energy groups of neutrons exist for some time after a pulse of source neutrons. Thus, it is possible to detect fissile materials deliberately concealed with shields having a large cross-section of absorption of photons and thermal neutrons. Two models of detection and the control of fissile materials were advanced: 1. the model based on graphite neutrons moderator and PSD scintillators with digital technology of neutrons and photons responses separation; 2. the model based on plastic scintillators and detecting of time coincidences of fission particles by digital technology. Facilities that count time coincidences of neutrons and photons occurring in the fission of fissile materials can use an Am Li source of neutrons, e.g. that is the case with the AWCC system. The disadvantages of the facility are related to the issues

  18. Detection of explosives and other illicit materials by a single nanosecond neutron pulses - Monte-Carlo simulations of the detection process

    International Nuclear Information System (INIS)

    Miklaszewski, R.; Drozdowicz, K.; Wiacek, U.; Dworak, D.; Gribkov, V.

    2011-01-01

    Recent progress in the development of a single-pulse Nanosecond Impulse Neutron Investigation System (NINIS) intended for interrogation of hidden objects (explosives and other illicit materials) by means of measuring elastically scattered neutrons is presented in this paper. The method is based on the well know fact that nuclide-specific information is present in the scattered neutron field. The method uses very bright neutron pulses having duration of the order of few nanoseconds, generated by a dense plasma focus (DPF) devices filled with a pure deuterium or deuterium-tritium mixture as a working gas. Very short duration of the neutron pulse, its high brightness and mono-chromaticity allow to use the time-of-flight method with bases of about few meters to distinguish signals from neutrons scattered by different elements. Results of the Monte Carlo simulations of the scattered neutron field from several compounds (explosives and everyday use materials) are presented in the paper. The MCNP5 code has been used to get information on the angular and energy distributions of the neutrons scattered by the above mentioned compounds assuming the initial neutron energy equal to 2.45 MeV (D-D). A new input has been elaborated that allows the modelling of not only a spectrum of the neutrons scattered at different angles but also their time history from the moment of generation up to detection. Such an approach allows getting approximate signals as registered by scintillator + photomultiplier probes placed at various distances from the scattering object, demonstrating a principal capability of the method to identify an elemental content of the inspected objects. Preliminary results of the MCNP modelling of the interrogation process of the airport luggage containing several illicit objects are presented as well. (authors)

  19. Fast neutron tomography with real-time pulse-shape discrimination in organic scintillation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Joyce, Malcolm J., E-mail: m.joyce@lancaster.ac.uk [Department of Engineering, Lancaster University, Lancaster, Lancashire LA1 4YW (United Kingdom); Agar, Stewart [Department of Engineering, Lancaster University, Lancaster, Lancashire LA1 4YW (United Kingdom); Aspinall, Michael D. [Hybrid Instruments Ltd., Gordon Manley Building, Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YW (United Kingdom); Beaumont, Jonathan S.; Colley, Edmund; Colling, Miriam; Dykes, Joseph; Kardasopoulos, Phoevos; Mitton, Katie [Department of Engineering, Lancaster University, Lancaster, Lancashire LA1 4YW (United Kingdom)

    2016-10-21

    A fast neutron tomography system based on the use of real-time pulse-shape discrimination in 7 organic liquid scintillation detectors is described. The system has been tested with a californium-252 source of dose rate 163 μSv/h at 1 m and neutron emission rate of 1.5×10{sup 7} per second into 4π and a maximum acquisition time of 2 h, to characterize two 100×100×100 mm{sup 3} concrete samples. The first of these was a solid sample and the second has a vertical, cylindrical void. The experimental data, supported by simulations with both Monte Carlo methods and MATLAB®, indicate that the presence of the internal cylindrical void, corners and inhomogeneities in the samples can be discerned. The potential for fast neutron assay of this type with the capability to probe hydrogenous features in large low-Z samples is discussed. Neutron tomography of bulk porous samples is achieved that combines effective penetration not possible with thermal neutrons in the absence of beam hardening.

  20. PNP2 calculus programme for interpretation of the experimental data by pulsed source neutrons methods. (Pt. 1). [Fortran IV for ICT 1900

    Energy Technology Data Exchange (ETDEWEB)

    Fratiloiu, C; Cristea, Gh

    1975-01-01

    PNP2 is a calculation programme destined to the interpretation of the experimental data by the pulsed source neutrons method on multiplyer environments into critic or subcritic state, populated with thermal neutrons. The programme is elaborate in the FORTRAN IV language of the ICT 1900 computer. The variation form in time of the thermal neutrons population for the multiplyer environments as a result of this whipping to the moments t=KT, with pockets of neutrons, appearing in the simplified theory of the pulsed source neutrons method. By this process are determinated the quantities Nsub(..cap alpha..), ..cap alpha.., Nsub(r) and B as well as empiric variants which affect these magnitudes. With these quantities is calculated the reactivity in relative units.

  1. Advances towards a portable pulsed source of neutrons and X-ray with energy of work close to 1 Joule

    International Nuclear Information System (INIS)

    Soto, Leopoldo; Pavez, C.; Moreno, Jose; Clausse, Alejandro; Barbaglia, Mario O.

    2005-01-01

    Plasma Focus devices are pulsed sources of X and neutron radiation from intense electrical discharges in deuterium. Classically these devices operate at energies between a few KJ to 1 MJ. In this work we present the design and feasibility studies of a Plasma Focus operating at energies close to 1 Joule. Experimental evidence of focalization is presented, and the optimum parameter relations at such low energies are discussed. The results indicate the device will be able to emit pulses about 1000 neutrons per J. (author) [es

  2. Method and apparatus for measuring neutron characteristics of material surrounding a borehole

    International Nuclear Information System (INIS)

    Randall, R.R.

    1983-01-01

    A method for logging the formations surrounding an earth borehole, comprising: pulsedly irradiating said formations with discrete bursts form a source of high energy neutrons; detecting radiations emanating from said irradiated formations at a detector spaced from said source; measuring said detected radiations during first and second time intervals following a burst from said source; generating time-separated electrical pulses indicative of said detected radiations during a third fixed time duration interval following a subsequent burst from said sources; and controlling automatically the starting time of said third measurement interval in accordance with the said measurement from said first and second time intervals

  3. Determination of the geotechnical properties of mudrocks from geophysical logging of the Harwell boreholes

    International Nuclear Information System (INIS)

    Horseman, S.T.; McCann, D.M.; McEwen, T.J.; Brightman, M.A.

    1984-11-01

    The geotechnical properties of mainly argillaceous strata at depth in borehole HW3 at Harwell, Oxfordshire have been determined using a variety of borehole geophysical logging techniques. The aim of this work was to assess the usefulness of such techniques for the indirect measurement of the geotechnical properties of the rocks and the subsequent bearing that such knowledge would have on the design of a site investigation programme for the deep disposal of non heat emitting radioactive waste. The borehole was logged by Seismograph Services Ltd over the interval from 165 - 551 m., whilst open and mud filled. Seven different geophysical logs were run: caliper, formation density, neutron-neutron, natural-gamma, 3D velocity, spontaneous potential, single point resistance and 16''/64'' normal resistivity. The logs that were of any use in determining geotechnical properties were the neutron-neutron, the formation density and the sonic log. It is suggested that in these types of formation the sonic log, once calibrated for the particular circumstances, could be used to provide a useful downhole strength log. (author)

  4. Pattern decomposition and quantitative-phase analysis in pulsed neutron transmission

    International Nuclear Information System (INIS)

    Steuwer, A.; Santisteban, J.R.; Withers, P.J.; Edwards, L.

    2004-01-01

    Neutron diffraction methods provide accurate quantitative insight into material properties with applications ranging from fundamental physics to applied engineering research. Neutron radiography or tomography on the other hand, are useful tools in the non-destructive spatial imaging of materials or engineering components, but are less accurate with respect to any quantitative analysis. It is possible to combine the advantages of diffraction and radiography using pulsed neutron transmission in a novel way. Using a pixellated detector at a time-of-flight source it is possible to collect 2D 'images' containing a great deal of interesting information in the thermal regime. This together with the unprecedented intensities available at spallation sources and improvements in computing power allow for a re-assessment of the transmission methods. It opens the possibility of simultaneous imaging of diverse material properties such as strain or temperature, as well as the variation in attenuation, and can assist in the determination of phase volume fraction. Spatial and time resolution (for dynamic experiment) are limited only by the detector technology and the intensity of the source. In this example, phase information contained in the cross-section is extracted from Bragg edges using an approach similar to pattern decomposition

  5. Measurement of the velocity of sound in crystals by pulsed neutron diffraction

    International Nuclear Information System (INIS)

    Willis, B.T.M.; Carlile, C.J.; Ward, R.C.; David, W.I.F.; Johnson, M.W.

    1986-03-01

    The diffraction method of observing elementary excitations in crystals has been applied to the study of one-phonon thermal diffuse scattering from pyrolytic graphite on a high resolution pulsed neutron diffractometer. The variation of the phase velocity of sound as a function of direction in the crystal and efficient method of determining sound velocities in crystals under extreme conditions. (author)

  6. New developments of TOF neutron diffraction at the IBR-2 pulsed reactor

    International Nuclear Information System (INIS)

    Balagurov, Anatoli M.

    2001-01-01

    Development of high-resolution RTOF Fourier technique for powder neutron diffraction studies is being continued at the IBR-2 pulsed reactor in Dubna. Besides some technical improvements in the operating HRFD instrument, a new dedicated instrument, Fourier Strain Diffractometer (FSD), for investigation of residual stresses in bulk materials has been constructed at IBR-2 in 1999. With a new HRFD Fourier chopper smaller than 10 μs TOF contribution in a resolution function was obtained in the experiment with perfect Si single crystal. A series of diffraction experiments with the beams from a new methane cold neutron moderator installed at the IBR-2 in 1999 is discussed. A comparison with the results obtained with the conventional water comb-like moderator shows that for various types of experiments, which are performed at HRFD and DN-2 diffractometers, the methane cold neutron source provides better conditions. (author)

  7. Pulsed neutron source very intense, Booster

    International Nuclear Information System (INIS)

    Abbate, J.M.

    1978-09-01

    A compact Accelerator-Booster (fast, pulsed and modulate reactivity research reactor) is a new and appropriate conception to use as a very intense thermal neutrons source. Its definition and feasibility have been already described in several studies showing its relative advantages in comparison with others kinds of facilities. This work, wich is part of one of those studies, contains a general analysis on the meis facility parameters and core and shielding theoretical calculations. The following results were obtained: Selection and test of a calculation system suitable to use in compact fast reactors; Development a method to perform estimations in some safety and shielding problems and obtainment of adequate theoretical predictions on the general performance. Moreover, final results for importent parameters of the feasibility study and predesign (critical mass and volume, lifetime, etc.) and others related to the use of plutonium oxide as fuel are given and then evaluations of different basic functions are showed. (author) [es

  8. Target-moderator-reflector optimization for JAERI 5 MW pulsed spallation neutron source

    International Nuclear Information System (INIS)

    Watanabe, Noboru; Teshigawara, Makoto; Kai, Tetsuya

    1999-01-01

    Optimization studies on the target-moderator-reflector neutronics for the projected intense pulsed-spallation-neutron-source in JAERI are reported. In order to obtain the highest possible performance of the source a new target-moderator-reflector system has been proposed and effects of various parameters, such as material and the shape/dimensions of the target, the profile/distribution of the proton beam, material and dimensions of the reflector, the coupling scheme of the target-moderator, moderator parameters, etc., on slow neutron performance and energy deposition in cryogenic moderators have extensively been studied by neutronic calculations. A cold neutron moderator for high-resolution together with high-intensity experiments has newly been proposed. It was found that, by adopting a flat target with a flat beam profile, the slow neutron intensities from the moderators could be rather insensitive to the target/beam dimensions, providing more flexibility to the engineering design of the target and the moderators. The moderator position relative to the target is another important issue to be optimized. It was confirmed that the proposed target-moderator-reflector layout made it possible to put all the moderators almost at the best position (It has not been possible so far), resulting in a higher performance. The predicted performance obtained with nearly optimized parameters was compared with those of similar projects in the world to justify the present concept. (author)

  9. Parameters measurement for the thermal neutron beam in the thermal column hole of Xi’an pulse reactor

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The distribution of the neutron spectra in the thermal column hole of Xi’an pulse reactor was measured with the time-of-flight method.Compared with the thermal Maxwellian theory neutron spectra,the thermal neutron spectra measured is a little softer,and the average neutron energy of the experimental spectra is about 0.042±0.01 eV.The thermal neutron fluence rate at the front end of thermal column hole,measured with gold foil activation techniques,is about 1.18×105 cm-2 s-1.The standard uncertainty of the measured thermal neutron fluence is about 3%.The spectra-averaged cross section of 197Au(n,γ) determined by the experimental thermal neutron spectra is(92.8±0.93) ×10-24 cm2.

  10. DrSPINE - New approach to data reduction and analysis for neutron spin echo experiments from pulsed and reactor sources

    International Nuclear Information System (INIS)

    Zolnierczuk, P.A.; Ohl, M.; Holderer, O.; Monkenbusch, M.

    2015-01-01

    Neutron spin echo (NSE) method at a pulsed neutron source presents new challenges to the data reduction and analysis as compared to the instruments installed at reactor sources. The main advantage of the pulsed source NSE is the ability to resolve the neutron wavelength and collect neutrons over a wider bandwidth. This allows us to more precisely determine the symmetry phase and measure the data for several Q-values at the same time. Based on the experience gained at the SNS NSE - the first, and to date the only one, NSE instrument installed at a pulsed spallation source, we propose a novel and unified approach to the NSE data processing called DrSPINE. The goals of the DrSPINE project are: -) exploit better symmetry phase determination due to the broader bandwidth at a pulsed source; -) take advantage of larger Q coverage for TOF instruments; -) use objective statistical criteria to get the echo fits right; -) provide robust reduction with report generation; -) incorporate absolute instrument calibration; and -) allow for background subtraction. The software must be able to read the data from various instruments, perform data integrity, consistency and compatibility checks and combine the data from compatible sets, partial scans, etc. We chose to provide a console-based interface with the ability to process macros (scripts) for batch evaluation. And last and not the least, a good software package has to provide adequate documentation. DrSPINE software is currently under development

  11. The Space-, Time-, and Energy-distribution of Neutrons from a Pulsed Plane Source

    Energy Technology Data Exchange (ETDEWEB)

    Claesson, Arne

    1962-05-15

    The space-, time- and energy-distribution of neutrons from a pulsed, plane, high energy source in an infinite medium is determined in a diffusion approximation. For simplicity the moderator is first assumed to be hydrogen gas but it is also shown that the method can be used for a moderator of arbitrary mass.

  12. Measuring and calculational complex on the base of multi-detector system and the kinetics parametrs by the method of neutron pulsed source

    International Nuclear Information System (INIS)

    Veselova, G.P.; Grachev, A.V.; Ivanova, N.K.

    1985-01-01

    Description of hardware of a measuring and calculation complex (MCC) designed for measuring neutron-physical characteristics of a reactor by the neutron pulsed method simultaneously from 8 detectors and the MERA-60 computer software used by MCC for measuring dependences of neutron generation and life time on the reactivity change is presented. The complex serviceability is tested at one of the PEI physical stands. MCC operation during a year has demonstrated its high reliability and a possibility of being used both for pulsed and other methods for investigating physical stands without introduction of supplementary equipment

  13. Monte Carlo simulations to advance characterisation of landmines by pulsed fast/thermal neutron analysis

    NARCIS (Netherlands)

    Maucec, M.; Rigollet, C.

    The performance of a detection system based on the pulsed fast/thermal neutron analysis technique was assessed using Monte Carlo simulations. The aim was to develop and implement simulation methods, to support and advance the data analysis techniques of the characteristic gamma-ray spectra,

  14. A fast Monte Carlo program for pulsed-neutron capture-gamma tools

    International Nuclear Information System (INIS)

    Hovgaard, J.

    1992-02-01

    A fast model for the pulsed-neutron capture-gamma tool has been developed. It is believed that the program produce valid results even though some approximation have been introduced. A correct γ photon transport simulation, which is under preparation, has for instance not yet been included. Simulations performed so far has shown that the model, with respect to computing time and accuracy, fully lives up to expectations with respect to computing time and accuracy. (au)

  15. Computation of porosity and water content from geophysical logs, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Nelson, P.H.

    1996-01-01

    Neutron and density logs acquired in boreholes at Yucca Mountain, Nevada are used to determine porosity and water content as a function of depth. Computation of porosity requires an estimate of grain density, which is provided by core data, mineralogical data, or is inferred from rock type where neither core nor mineralogy are available. The porosity estimate is merged with mineralogical data acquired by X-ray diffraction to compute the volumetric fractions of major mineral groups. The resulting depth-based portrayal of bulk rock composition is equivalent to a whole rock analysis of mineralogy and porosity. Water content is computed from epithermal and thermal neutron logs. In the unsaturated zone, the density log is required along with a neutron log. Water content can also be computed from dielectric logs, which were acquired in only a fraction of the boreholes, whereas neutron logs were acquired in all boreholes. Mineralogical data are used to compute a structural (or bound) water estimate, which is subtracted from the total water estimate from the neutron-density combination. Structural water can be subtracted only from intervals where mineralogical analyses are available; otherwise only total water can be reported. The algorithms and procedures are applied to logs acquired during 1979 to 1984 at Yucca Mountain. Examples illustrate the results. Comparison between computed porosity and core measurements shows systematic differences ranging from 0.005 to 0.04. These values are consistent with a sensitivity analysis using uncertainty parameters for good logging conditions. Water content from core measurements is available in only one borehole, yielding a difference between computed and core-based water content of 0.006

  16. Correlated sampling added to the specific purpose Monte Carlo code McPNL for neutron lifetime log responses

    International Nuclear Information System (INIS)

    Mickael, M.; Verghese, K.; Gardner, R.P.

    1989-01-01

    The specific purpose neutron lifetime oil well logging simulation code, McPNL, has been rewritten for greater user-friendliness and faster execution. Correlated sampling has been added to the code to enable studies of relative changes in the tool response caused by environmental changes. The absolute responses calculated by the code have been benchmarked against laboratory test pit data. The relative responses from correlated sampling are not directly benchmarked, but they are validated using experimental and theoretical results

  17. Neutron scattering studies of the dynamics of biopolymer-water systems using pulsed-source spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Middendorf, H.D. [Univ. of Oxford (United Kingdom); Miller, A. [Stirling Univ., Stirling (United Kingdom)

    1994-12-31

    Energy-resolving neutron scattering techniques provide spatiotemporal data suitable for testing and refining analytical models or computer simulations of a variety of dynamical processes in biomolecular systems. This paper reviews experimental work on hydrated biopolymers at ISIS, the UK Pulsed Neutron Facility. Following an outline of basic concepts and a summary of the new instrumental capabilities, the progress made is illustrated by results from recent experiments in two areas: quasi- elastic scattering from highly hydrated polysaccharide gels (agarose and hyaluronate), and inelastic scattering from vibrational modes of slightly hydrated collagen fibers.

  18. The analysis of neutron physical characteristics of fast reactors by means of pulsed experiments

    International Nuclear Information System (INIS)

    Stumbur, Eh.A.; Milyutina, Z.N.

    1992-01-01

    Possibility is considered for determination of macroscopic cross sections of homogeneous multiplicating media with fast neutrons. It is shown that by means of the critical size, laplaccian and neutron pulse damping decrement measurement results it is possible to obtain values of almost all cross sections of a medium. The method is tested with systems of metal 235 U and BFS-32 assemblies with the composition, typical for fast power reactors. A suitable algorithm is developed for solving nonstationary asymptotic transport problems. Calculation results are compared with experimental ones. 21 refs.; 2 figs.; 3 tabs

  19. Neutron scattering studies of the dynamics of biopolymer-water systems using pulsed-source spectrometers

    International Nuclear Information System (INIS)

    Middendorf, H.D.; Miller, A.

    1994-01-01

    Energy-resolving neutron scattering techniques provide spatiotemporal data suitable for testing and refining analytical models or computer simulations of a variety of dynamical processes in biomolecular systems. This paper reviews experimental work on hydrated biopolymers at ISIS, the UK Pulsed Neutron Facility. Following an outline of basic concepts and a summary of the new instrumental capabilities, the progress made is illustrated by results from recent experiments in two areas: quasi- elastic scattering from highly hydrated polysaccharide gels (agarose and hyaluronate), and inelastic scattering from vibrational modes of slightly hydrated collagen fibers

  20. Etude de la diagraphie neutron du granite de Beauvoir. Effet neutron des altérations et de la matrice du granite. Calibration granite. Porosité totale à l'eau et porosité neutron Analysis of the Beauvoir Granite Neutron Log. Neutron Effect of Alterations and of the Granite Matrix. Granite Calibration. Total Water Porosity and Neutron Porosity

    Directory of Open Access Journals (Sweden)

    Galle C.

    2006-11-01

    carottes (n. Nous montrons que, pour le granite de Beauvoir, l'effet neutron de la matrice est important (en moyenne proche de 7% et ne peut être négligé lorsque l'on mesure des porosités voisines de 0,5% sur carottes. La calibration de l'outil neutron dans le granite et non pas dans des calcaires est d'autre part capitale quant à la précision quantitative des résultats. This article describes the research done on the Beauvoir granite (Echassières GPF 1 borehole, French Massif Central range. The aim of this project was to obtain representative values of the water saturation (n total free water porosity of the Beauvoir granite from PorosityN neutron porosity (BRGM neutron log. The exact knowledge of the porosity of a crystalline block is effectively fundamental to determine its possibilities for being used as a waste storage site. With this goal, neutron logging provides indispensable information concerning the characterization of a porous medium. Our procedure was experimental, and we tried to go more deeply into various problems linked to the use of neutron logging in a granitic rock. Two main factors governed the neutron response : (i the hydrogen concentration of the formation (free water and combined water of various minerals and (ii the presence of absorber elements with a large capture cross-section such as gadolinium, cadmium, boron as well as lithium for the Beauvoir granite. After measuring the Beauvoir granite n total (free water porosity on core samples, we evaluated the combined water content of each sample tested on the basis of fire loss tests on rock powder at 900°C. From the hydrogen atoms volumic concentration, we determined a hydrogen index that we directly converted into the PorosityN(OH- neutron porosity, (by definition, pure water at 20°C has a hydrogen index of 1 which is equivalent to a 100% porosity. For the Beauvoir granite, the matrix combined water represents an average neutron porosity (Table 1 of about 4%. In the second phase, we used

  1. Laser-energy scaling law for neutrons generated from nano particles Coulomb-exploded by intense femtosecond laser pulses

    International Nuclear Information System (INIS)

    Sakabe, Shuji; Hashida, Masaki

    2015-01-01

    To discuss the feasibility of compact neutron sources the yield of laser produced neutrons is scaled by the laser energy. High-energy ions are generated by Coulomb explosion of clusters through intense femtosecond laser-cluster interactions. The laser energy scaling law of the neutron yield is estimated using the laser intensity scaling law for the energy of ions emitted from clusters Coulomb-exploded by an intense laser pulse. The neutron yield for D (D, n) He shows the potential of compact neutron sources with modern laser technology, and the yield for p (Li, n) Be shows much higher than that for Li (p, n) Be with the assumption of 500 nm-class cluster Coulomb explosion. (author)

  2. Importance estimation in Monte Carlo modelling of neutron and photon transport

    International Nuclear Information System (INIS)

    Mickael, M.W.

    1992-01-01

    The estimation of neutron and photon importance in a three-dimensional geometry is achieved using a coupled Monte Carlo and diffusion theory calculation. The parameters required for the solution of the multigroup adjoint diffusion equation are estimated from an analog Monte Carlo simulation of the system under investigation. The solution of the adjoint diffusion equation is then used as an estimate of the particle importance in the actual simulation. This approach provides an automated and efficient variance reduction method for Monte Carlo simulations. The technique has been successfully applied to Monte Carlo simulation of neutron and coupled neutron-photon transport in the nuclear well-logging field. The results show that the importance maps obtained in a few minutes of computer time using this technique are in good agreement with Monte Carlo generated importance maps that require prohibitive computing times. The application of this method to Monte Carlo modelling of the response of neutron porosity and pulsed neutron instruments has resulted in major reductions in computation time. (Author)

  3. Proposed second harmonic acceleration system for the intense pulsed neutron source rapid cycling synchrotron

    International Nuclear Information System (INIS)

    Norem, J.; Brandeberry, F.; Rauchas, A.

    1983-01-01

    The Rapid Cycling Synchrotron (RCS) of the Intense Pulsed Neutron Source (IPNS) operating at Argonne National Laboratory is presently producing intensities of 2 to 2.5 x 10 12 protons per pulse (ppp) with the addition of a new ion source. This intensity is close to the space charge limit of the machine, estimated at approx.3 x 10 12 ppp, depending somewhat on the available aperture. With the present good performance in mind, accelerator improvements are being directed at: (1) increasing beam intensities for neutron science; (2) lowering acceleration losses to minimize activation; and (3) gaining better control of the beam so that losses can be made to occur when and where they can be most easily controlled. On the basis of preliminary measurements, we are now proposing a third cavity for the RF systems which would provide control of the longitudinal bunch shape during the cycle which would permit raising the effective space charge limit of the accelerator and reducing losses

  4. NATO Advanced Study Institute on Chemical Crystallography with Pulsed Neutrons and Synchrotron X-Rays

    CERN Document Server

    Jeffrey, George

    1988-01-01

    X-ray and neutron crystallography have played an increasingly impor­ tant role in the chemical and biochemical sciences over the past fifty years. The principal obstacles in this methodology, the phase problem and com­ puting, have been overcome. The former by the methods developed in the 1960's and just recognised by the 1985 Chemistry Nobel Prize award to Karle and Hauptman, the latter by the dramatic advances that have taken place in computer technology in the past twenty years. Within the last decade, two new radiation sources have been added to the crystallographer's tools. One is synchrotron X-rays and the other is spallation neutrons. Both have much more powerful fluxes than the pre­ vious sources and they are pulsed rather than continuos. New techniques are necessary to fully exploit the intense continuos radiation spectrum and its pulsed property. Both radiations are only available from particular National Laboratories on a guest-user basis for scientists outside these Na­ tional Laboratories. Hi...

  5. Study of heterogeneous multiplying and non-multiplying media by the neutron pulsed source technique

    International Nuclear Information System (INIS)

    Deniz, V.

    1969-01-01

    The pulsed neutron technique consists essentially in sending in the medium to be studied a short neutron pulse and in determining the asymptotic decay constant of the generated population. The variation of the decay constant as a function of the size of the medium allows the medium characteristics to be defined. This technique has been largely developed these last years and has been applied as well to moderator as to multiplying media, in most cases homogeneous ones. We considered of interest of apply this technique to lattices, to see if useful informations could be collected for lattice calculations. We present here a general theoretical study of the problem, and results and interpretation of a series of experiments made on graphite lattices. There is a good agreement for non-multiplying media. In the case of multiplying media, it is shown that the age value used until now in graphite lattices calculations is over-estimated by about 10 per cent [fr

  6. Logging technique for assaying for uranium in earth formations

    International Nuclear Information System (INIS)

    Givens, W.W.; Mills, W.R. Jr.

    1979-01-01

    A borehole logging tool includes a source of fast neutrons, an epithermal neutron flux detector, and a thermal neutron flux detector. A count rate meter is connected to each detector. A ratio detector provides a signal indicative of the ratio of the count rates of the two detectors obtained during the time that prompt neutrons are emitted from neutron fission of uranium in the formation

  7. Super-resolution processing for pulsed neutron imaging system using a high-speed camera

    International Nuclear Information System (INIS)

    Ishizuka, Ken; Kai, Tetsuya; Shinohara, Takenao; Segawa, Mariko; Mochiki, Koichi

    2015-01-01

    Super-resolution and center-of-gravity processing improve the resolution of neutron-transmitted images. These processing methods calculate the center-of-gravity pixel or sub-pixel of the neutron point converted into light by a scintillator. The conventional neutron-transmitted image is acquired using a high-speed camera by integrating many frames when a transmitted image with one frame is not provided. It succeeds in acquiring the transmitted image and calculating a spectrum by integrating frames of the same energy. However, because a high frame rate is required for neutron resonance absorption imaging, the number of pixels of the transmitted image decreases, and the resolution decreases to the limit of the camera performance. Therefore, we attempt to improve the resolution by integrating the frames after applying super-resolution or center-of-gravity processing. The processed results indicate that center-of-gravity processing can be effective in pulsed-neutron imaging with a high-speed camera. In addition, the results show that super-resolution processing is effective indirectly. A project to develop a real-time image data processing system has begun, and this system will be used at J-PARC in JAEA. (author)

  8. Neutron stars

    International Nuclear Information System (INIS)

    Irvine, J.M.

    1978-01-01

    The subject is covered in chapters entitled: introduction (resume of stellar evolution, gross characteristics of neutron stars); pulsars (pulsar characteristics, pulsars as neutron stars); neutron star temperatures (neutron star cooling, superfluidity and superconductivity in neutron stars); the exterior of neutron stars (the magnetosphere, the neutron star 'atmosphere', pulses); neutron star structure; neutron star equations of state. (U.K.)

  9. FPGA based computation of average neutron flux and e-folding period for start-up range of reactors

    International Nuclear Information System (INIS)

    Ram, Rajit; Borkar, S.P.; Dixit, M.Y.; Das, Debashis

    2013-01-01

    Pulse processing instrumentation channels used for reactor applications, play a vital role to ensure nuclear safety in startup range of reactor operation and also during fuel loading and first approach to criticality. These channels are intended for continuous run time computation of equivalent reactor core neutron flux and e-folding period. This paper focuses only the computational part of these instrumentation channels which is implemented in single FPGA using 32-bit floating point arithmetic engine. The computations of average count rate, log of average count rate, log rate and reactor period are done in VHDL using digital circuit realization approach. The computation of average count rate is done using fully adaptive window size moving average method, while Taylor series expansion for logarithms is implemented in FPGA to compute log of count rate, log rate and reactor e-folding period. This paper describes the block diagrams of digital logic realization in FPGA and advantage of fully adaptive window size moving average technique over conventional fixed size moving average technique for pulse processing of reactor instrumentations. (author)

  10. California-Nevada uranium logging. Final report

    International Nuclear Information System (INIS)

    1981-04-01

    The purpose of this project was to obtain geophysical logs of industry drill holes to assess the uranium resource potential of geologic formations of interest. The work was part of the US Department of Energy's National Uranium Resource Evaluation (NURE) Program. The principal objective of the logging program was to determine radioelement grade of formations through natural gamma ray detectors. Supplementary information was obtained from resistivity (R), self-potential (SP), point resistance (RE), and neutron density (NN) logs for formation interpretation. Additional data for log interpretation was obtained from caliper logs, casing schedules, and downhole temperature. This data was obtained from well operators when available, with new logs obtained where not formerly available. This report contains a summary of the project and data obtained to date

  11. An Improved Nuclear Recoil Calibration in the LUX Detector Using a Pulsed D-D Neutron Generator

    Science.gov (United States)

    Huang, Dongqing

    2017-01-01

    The LUX dark matter search experiment is a 370 kg (250 kg active mass) two-_phase liquid/gas xenon time projection chamber located at the 4850 ft level of the Sanford Underground Research Facility in Lead, SD. The first absolute charge (Qy) and light (Ly) measurement performed in situ in the LUX detector with a D-D calibration technique for nuclear recoil spanning 0.7 to 74 keV and 1.1 to 74 keV respectively have been reported in. The D-D calibration has subsequently been further improved by incorporating pulsing technique, i.e. the D-D neutron production is concentrated within narrow pulses (20 us / 250 Hz) with the timing information recorded. This technique allows the suppression of accidental backgrounds in D-D neutron data and also provides increased sensitivity for the lower energy NR calibrations. I will report the improved NR absolute Qy and Ly measurements using the pulsed D-D calibration technique performed in situ in the LUX detector. Brown University, Large Underground Xenon(LUX) Collaboration.

  12. Analytical solution of neutron transport equation in an annular reactor with a rotating pulsed source; Resolucao analitica da equacao de transporte de neutrons em um reator anelar com fonte pulsada rotativa

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, Paulo Cleber Mendonca

    2002-12-01

    In this study, an analytical solution of the neutron transport equation in an annular reactor is presented with a short and rotating neutron source of the type S(x) {delta} (x- Vt), where V is the speed of annular pulsed reactor. The study is an extension of a previous study by Williams [12] carried out with a pulsed source of the type S(x) {delta} (t). In the new concept of annular pulsed reactor designed to produce continuous high flux, the core consists of a subcritical annular geometry pulsed by a rotating modulator, producing local super prompt critical condition, thereby giving origin to a rotating neutron pulse. An analytical solution is obtained by opening up of the annular geometry and applying one energy group transport theory in one dimension using applied mathematical techniques of Laplace transform and Complex Variables. The general solution for the flux consists of a fundamental mode, a finite number of harmonics and a transient integral. A condition which limits the number of harmonics depending upon the circumference of the annular geometry has been obtained. Inverse Laplace transform technique is used to analyse instability condition in annular reactor core. A regenerator parameter in conjunction with perimeter of the ring and nuclear properties is used to obtain stable and unstable harmonics and to verify if these exist. It is found that the solution does not present instability in the conditions stated in the new concept of annular pulsed reactor. (author)

  13. Influence of media size on energy distribution of pulsed thermal neutrons

    International Nuclear Information System (INIS)

    Dabrowska, J.

    2007-01-01

    The work is devoted to the investigation of the diffusion cooling phenomenon of pulsed thermalized neutron fields in bounded media. It is aimed at the examination of the validity of the neutron temperature model that involves the assumption that an asymptotic energy distribution of neutrons in bounded media can be described by the Maxwell distribution but with a shifted temperature, lower than a temperature of medium. The research carried out entirely by means of Monte Carlo simulation of the neutron transport was preceded by a measurement of the time decay constants obtained in all variants of Monte Carlo simulations of the experiment and the measured one was stated. The form of asymptotic energy distribution of neutrons and its dependence on the size of medium was investigated in three kinds of materials of different thermal neutron transport properties: energy independent scatterer with negligible absorption (silica), energy dependent scatterer with 1/v absorption (borated silica) and energy dependent scatterer with 1/v absorption (water). As it was expected, in the case of large media, which can be treated as infinite, neutrons attained the Maxwell energy distribution at the temperature of the medium. For all materials under investigation the average and the most probable values of the energy distribution steadily decreased with decreasing geometric dimensions of the media. At the same time a growing distortion from the pure Maxwellian energy distribution was observed, which means that the concept of the neutron temperature fails in the case of small media. Although the spectra under investigation in general did not have the Maxwellian shape, the most probable velocity in a neutron density distribution decreased linearly with the increasing geometric buckling of the medium. This dependence manifested a stronger cooling than the one predicted by a certain approximate formula. The neutron spectrum in a small medium of pure silica was cooler than the spectrum in

  14. CFD simulation of the pulsed neutron activation technique for water flow measurements

    International Nuclear Information System (INIS)

    Mattsson, H.; Nordlund, A.

    2005-01-01

    A pulse neutron activation (PNA) flowmeter uses a radioactive substance to measure water flow in pipes. The water in the pipe is bombarded with neutron pulses, thus introducing activity into the pipe. The activity is then transported and mixed with the flow. Gamma radiation emitted from the activity is measured with one or two detectors downstream from the activation point. The average velocity of the water is calculated using the time-resolved signal from the detector. The CFD program FLUENT was used to simulate the transport and mixing of the activity induced in the pipe. The turbulence of the flow is described with the k-ε model. Some parameters affecting a PNA measurement have been investigated. From the calculations it was possible to quantify how much the average initial velocity of the activity differs from the average velocity of the water. Results also show that activity initially produced far away from the wall has a substantial effect on the detector signal. To accurately simulate the detector signal it is necessary to include activity produced in a large part of the pipe. The results also indicate that the collimation of the detectors have a significant impact on the data and should be included when evaluating simulated data. Three different response functions were also tested. (authors)

  15. Neutron dosimeters and survey meters in accelerators, reactors and other neutron environments

    International Nuclear Information System (INIS)

    1989-03-01

    Neutron fields in occupationally accessible areas around nuclear reactors, radioisotope sources and medical and high energy accelerators have been characterized using currently available information. Neutron, rem meters, such as the Leake detector, are the most suitable instruments available for conducting neutron dose rate surveys in the vicinity of radioisotope neutron sources, nuclear reactors and medical accelerators. However, these instruments have been shown to be deficient in that they overrespond by a factor of four to neutrons in the 0.1 to 1 MeV range and are insensitive to neutrons from about 1 eV up to about 10 keV. Also, they are insensitive to neutrons above 20 MeV and their use must be restricted near high energy accelerators where significant numbers of neutrons above 20 MeV are known to be present. The most suitable instrument of measure dose from neutrons above 20 MeV is the 12 C(n,2n) 11 C scintillation chamber. Commercially available rem meters frequently use BF 3 counters in the pulse mode to detect thermal neutrons. Therefore, measurements around pulsed accelerators must be made with caution to ensure that the detector is not saturated during each pulse and that the accelerator pulse period is greater than the response time of the detector. The personal neutron dosimeters currently available either are known to be insensitive to neutrons above 20 MeV or have not been tested. Also, all except the albedo dosimeter are insensitive to or have not been tested for neutron energies in the range 1 eV to 10 keV. Several dosimeter types respond reasonably well to neutrons in the energy range 0.1 to 15 MeV, for example, CR-39, bubble and superheated drop detectors. However, the first gas a lower limit of sensitivity of about 0.3 mSv. The bubble detector can be designed to measure doses as small as 1μSv and offers the additional benefit of direct-reading capability. The superheated drop detector is not suitable for use around pulsed accelerators because

  16. Extension of the calibration of an NE-213 liquid scintillator based pulse height response spectrometer up to 18 MeV neutron energy and leakage spectrum measurements on bismuth at 8 MeV and 18 MeV neutron energies

    International Nuclear Information System (INIS)

    Fenyvesi, A.; Valastyan, I.; Olah, L.; Csikai, J.; Plompen, A.; Jaime, R.; Loevestam, G.; Semkova, V.

    2011-01-01

    Monoenergetic neutrons were produced at the Van de Graaff accelerator of the EC-JRC-Institute for Reference Materials and Measurements (IRMM, Geel, Belgium). An air-jet cooled D_2-gas target (1.2 bar, ΔE_d = 448 keV) was bombarded with E_d =4976 keV deuterons to produce neutrons up to E_n = 8 MeV energy via the D(d,n)"3He reaction. Higher energy neutrons up to E_n = 18 MeV were produced via the T(d,n)"4He reaction by bombarding a TiT target with E_d =1968 keV deuterons. Pulse height spectra were measured at different neutron energies from E_n = 8 MeV up to E_n = 18 MeV with the NE-213 liquid scintillator based Pulse Height Response Spectrometer (PHRS) of UD-IEP. The energy calibration of the PHRS system has been extended up to E_n = 18 MeV. Pulse height spectra induced by gamma photons have been simulated by the GRESP7 code. Neutron induced pulse height spectra have been simulated by the NRESP7 and MCNP-POLIMI codes. Comparison of the results of measurements and simulations enables the improvement of the parameter set of the function used by us to describe the light output dependence of the resolution of the PHRS system at light outputs of L > 2 light units. Also, it has been shown that the derivation method for unfolding neutron spectra from measured pulse height spectra performs well when relative measurements are done up to E_n = 18 MeV neutron energy. For matrix unfolding purposes, the NRESP7 code has to be preferred to calculate the pulse height response matrix of the PHRS system. Leakage spectra of neutrons behind bismuth slabs of different thicknesses have been measured with the PHRS system by using monoenergetic neutrons. The maximum slab thickness was d = 14 cm. Simulations of the measurements have been carried out with the MCNP-4c code. The necessary nuclear cross-sections were taken from the from the ENDF/B-VII and JEFF.3.1 data libraries. For both libraries, the agreement of measured and simulated neutron spectra is good for the 5 MeV ≤ En ≤ 18 Me

  17. Subcritical Neutron Multiplication Measurements of HEU Using Delayed Neutrons as the Driving Source

    International Nuclear Information System (INIS)

    Hollas, C.L.; Goulding, C.A.; Myers, W.L.

    1999-01-01

    A new method for the determination of the multiplication of highly enriched uranium systems is presented. The method uses delayed neutrons to drive the HEU system. These delayed neutrons are from fission events induced by a pulsed 14-MeV neutron source. Between pulses, neutrons are detected within a medium efficiency neutron detector using 3 He ionization tubes within polyethylene enclosures. The neutron detection times are recorded relative to the initiation of the 14-MeV neutron pulse, and subsequently analyzed with the Feynman reduced variance method to extract singles, doubles and triples neutron counting rates. Measurements have been made on a set of nested hollow spheres of 93% enriched uranium, with mass values from 3.86 kg to 21.48 kg. The singles, doubles and triples counting rates for each uranium system are compared to calculations from point kinetics models of neutron multiplicity to assign multiplication values. These multiplication values are compared to those from MC NP K-Code calculations

  18. Physical model of reactor pulse

    International Nuclear Information System (INIS)

    Petrovic, A.; Ravnik, M.

    2004-01-01

    Pulse experiments have been performed at J. Stefan Institute TRIGA reactor since 1991. In total, more than 130 pulses have been performed. Extensive experimental information on the pulse physical characteristics has been accumulated. Fuchs-Hansen adiabatic model has been used for predicting and analysing the pulse parameters. The model is based on point kinetics equation, neglecting the delayed neutrons and assuming constant inserted reactivity in form of step function. Deficiencies of the Fuchs-Hansen model and systematic experimental errors have been observed and analysed. Recently, the pulse model was improved by including the delayed neutrons and time dependence of inserted reactivity. The results explain the observed non-linearity of the pulse energy for high pulses due to finite time of pulse rod withdrawal and the contribution of the delayed neutrons after the prompt part of the pulse. The results of the improved model are in good agreement with experimental results. (author)

  19. Criteria for identification of carbonate reservoirs according to well logging data (carboniferous deposits of Astrakhan' vault taken as an example)

    International Nuclear Information System (INIS)

    Makarova, A.N.; Mitalev, I.A.

    1979-01-01

    Described are the criteria for identification of carbonate reservoirs according to well logging data (carboniferous deposits of Astrakhan' vault taken as an example). According to gamma logging and cavitymetry data clay areas (decreased readings of neutron-gamma logging opposite dense rocks) are distinguished in a well log. ''Reservoir-nonreserVoir'' boundary is relatively drawn on the basis of the relation between neutron-gamma logaing indications and average general porosity of carbonate rocks determined by accoustic and neutron gamma logging

  20. Engineering aspects of radiometric logging

    International Nuclear Information System (INIS)

    Huppert, P.

    1982-01-01

    Engineering problems encountered in the development of nuclear borehole logging techniques are discussed. Spectrometric techniques require electronic stability of the equipment. In addition the electronics must be capable of handling high count rates of randomly distributed pulses of fast rise time from the detector and the systems must be designed so that precise calibration is possible under field operating conditions. Components of a logging system are discussed in detail. They include the logging probe (electronics, detector, high voltage supply, preamplifier), electronic instrumentation for data collection and processing and auxiliary equipment

  1. In-situ assaying for uranium in rock formations and method of undirectly monitoring the output of a pulsed neutron source

    International Nuclear Information System (INIS)

    Givens, W.W.; Caldwell, R.L.; Mills, W.R. Jr.

    1975-01-01

    A description is given of a method of assaying for uranium in the formations traversed by a borehole, which comprises: 1) locating a pulsed neutron source and a neutron detector in a borehole at the level of a formation of interest suspected of containing uranium; 2) operating the neutron source cyclically with the time between each neutron burst being sufficient to allow neutrons from the source to disappear but being long enough to allow the delayed neutrons resulting from the neutron fission of uranium to appear at the detector; 3) detecting neutrons with the detector, as a result of the irradiation of the formations with the neutrons from the source, and obtaining measurements of the quantity of neutrons detected between neutron bursts only at a time period when neutrons from the source have disappeared but, while delayed fission neutrons from uranium may be emitted. (author)

  2. A mechanical velocity selector for a small angle scattering instrument on a pulsed neutron source

    International Nuclear Information System (INIS)

    Meardon, B.H.; Stewart, R.J.; Williams, W.G.

    1978-11-01

    Design parameters and performance calculations are given for a straight-slot velocity selector which can be used for discriminating between elastic and inelastic scattering events in small angle scattering experiments on a pulsed neutron source. The selector has a high transmittance over the wavelength range 3 A 5%. (author)

  3. LOFT experimental measurements uncertainty analyses. Volume XX. Fluid-velocity measurement using pulsed-neutron activation

    International Nuclear Information System (INIS)

    Lassahn, G.D.; Taylor, D.J.N.

    1982-08-01

    Analyses of uncertainty components inherent in pulsed-neutron-activation (PNA) measurements in general and the Loss-of-Fluid-Test (LOFT) system in particular are given. Due to the LOFT system's unique conditions, previously-used techniques were modified to make the volocity measurement. These methods render a useful, cost-effective measurement with an estimated uncertainty of 11% of reading

  4. Three frequency modulated combination thermal neutron lifetime log and porosity

    International Nuclear Information System (INIS)

    Paap, H.J.; Arnold, D.M.; Smith, M.P.

    1976-01-01

    Methods are disclosed for measuring simultaneously the thermal neutron lifetime of the borehole fluid and earth formations in the vicinity of a well borehole, together with the formation porosity. A harmonically intensity modulated source of fast neutrons is used to irradiate the earth formations with fast neutrons at three different modulation frequencies. Intensity modulated clouds of thermal neutrons at each of the three modulation frequencies are detected by dual spaced detectors and the relative phase shift of the thermal neutrons with respect to the fast neutrons is determined at each of the three modulation frequencies at each detector. These measurements are then combined to determine simultaneously the thermal neutron decay time of the borehole fluid, the thermal neutron decay time of surrounding earth formation media and the porosity of the formation media

  5. Well logging, atom and geology

    International Nuclear Information System (INIS)

    Serra, O.

    1994-01-01

    Well logging techniques exploit interactions of gamma photons and neutrons with atoms. Interactions of neutrons of different energies with atoms allow the detection and evaluation of the weight percentage of several elements composing the rocks (C, O, Si, Ca, Fe, S); spectrometry of gamma rays produced by thermal neutron absorption allows for the weight percentage determination of Si, Ca, Fe, S, Cl, H, Ti and Gd, etc. High resolution detectors (germanium doped by Li, at liquid nitrogen temperature) allow the recognition of more elements. Other techniques involving neutrons consist in determining the population in epithermal neutrons at a certain distance of the neutron source (measurement of the hydrogen index). By analyzing the intensity of the gamma flux produced by Compton scattering, the electronic and bulk densities of the rocks are measured. All these data lead to the detection and evaluation of ore deposits (uranium and potassium) and coal, and determination of the lithology, the main minerals composing the rocks, petrophysical properties... 1 fig

  6. 150 keV accelerator as pulsed neutron source; Acelerador de 150 keV como fuente de neutrones pulsada

    Energy Technology Data Exchange (ETDEWEB)

    Cordero, F

    1970-07-01

    The project of a 150 keV Cockcroft-Walton accelerator built at J.E.N. is described. Beam currents of more than 10 mA, with a neutron intensity of 10{sup 1}1 n.s{sup 1}, are obtained. Also, we report some research made in connection with that project. The role of the contamination in the vacuum system and the performance of the pumps and gauges pumping deuterium gas are studied. Sinusoidal pulses are employed as an analysis method of the discharge in the ion source and the performance of the extracting-focusing system. The parameters of the beam leaving the ion source have been determined; these are used to calculate the electrostatic lenses with the gaussian optics. Measurements concerning deuterium and tritium targets as neutron sources have been made and the processes affecting their practical service life are analyzed. (Author) 71 refs.

  7. Survey of Pulsed Neutron Source Methods for Multiplying Media; Methodes des Neutrons Pulses Pour l'Etude des Milieux Multiplicateurs; Obzor metodov s ispol'zovaniem istochnikov impul'snykh nejtronov dlya razmnozhayushchej sredy; Estudio Panoramico de los Metodos de Empleo de Fuentes de Neutrons Pulsados en Medios Multiplicadores

    Energy Technology Data Exchange (ETDEWEB)

    Garelis, E. [General Electric Company, Vallecitos Atomic Laboratory, Pleasanton, CA (United States)

    1965-10-15

    In recent years there have existed two schools of thought on the most effective manner of obtaining measurements of the shutdown reactivity using pulsed neutron generators; these are (i) the conventional pulsed neutron source measurements with a repetitively pulsed source and (ii) methods based on a pseudo-random impulse response technique using cross-correlation between input and output. In both techniques the pertinent information obtained is identical, i.e. ideally both methods serve to determine the response function. The development of pulsed neutron source techniques on thermal systems for the purpose of reactivity measurements is traced from the early efforts of Sjoestrand to the recent (k{beta} Script-Small-L ) method. In the usual pulsed neutron source method, the Green's function of the subcritical assembly, the reactor response to a delta function source of neutrons, is the sought-after property. The exponential decay, exp(-{alpha}t), of the Green's function yields a spatially independent prompt neutron decay constant. The methods by which the reactivity is derived from the ct-measurement, e.g. the a-delayed critical measurement and the recent (k{beta} Script-Small-L ) method, are discussed. The fundamental modal treatments are examined in the light of the theory of the pulsed neutronsource techniques as developed for the (k{beta} Script-Small-L ) model. The implications of the pulsed neutron source theory to obtain precise decay constants and suitable data for the analysis of pulsed systems are considered. Experimental work is reviewed that shows the advantages as well as the limitations of the (k{beta} Script-Small-L ) technique. The use of pseudo-random impulse response methods with cross-correlation between the input and output for the determination of the Green's function of a multiplying assembly is also discussed. It is shown that the information obtained by the pseudo-random method is identical to that obtained from the repetitively pulsed method

  8. Fast neutron detection using a new pulse shape discrimination technique: Charge sensitive integration

    International Nuclear Information System (INIS)

    Zucker, M.; Tsoupas, N.; Karwowski, H.; Castaneda, C.; Nimnual, S.; Porter, R.; Ward, T.

    1988-01-01

    A new electronic technique that depends on charge sensitive integration (CSI) has been developed and tested using a CAMAC based pulse shape discrimination system. Neutrons are well separated from γ-ray signals in the 0.1-100 MeV energy range. The new method was compared with the old zero-crossing time-to-amplitude differentiating technique and was found to be comparable in count rate and superior in noise suppression

  9. Thermal neutron measurements on electrolytic cells with deuterated palladium cathodes subjected to a pulsed current

    International Nuclear Information System (INIS)

    Granada, J.R.; Mayer, R.E.; Guido, G.; Florido, P.C.; Larreteguy, A.; Gillette, V.H.; Patino, N.E.; Converti, J.; Gomez, S.E.

    1990-01-01

    The present work describes the design of a high efficiency thermal neutron detection system and the measurements performed with it on electrolytic cells containing LiH dissolved in D 2 O with palladium cathodes. A procedure involving the use of a non-stationary (pulsed) current through the cell caused a correlated neutron production to be observed in a repeatable manner. These patterns are strongly dependent on the previous charging history of the cathodes. The technique employed seems to be very useful as a research tool for a systematic study of the different variables governing the phenomenon. (author)

  10. The upgrade of intense pulsed neutron source (IPNS) through the change of coolant and reflector

    CERN Document Server

    Baek, I C; Iverson, E B

    2002-01-01

    The current intense pulsed neutron source (IPNS) depleted uranium target is cooled by light water. The inner reflector material is graphite and the outer reflector material is beryllium. The presence of H sub 2 O in the target moderates neutrons and leads to a higher absorption loss in the target than is necessary. D sub 2 O coolant in the small quantities required minimizes this effect. We have studied the possible improvement in IPNS beam fluxes that would result from changing the coolant from H sub 2 O to D sub 2 O and the inner reflector from graphite to beryllium. Neutron intensities were calculated for directions normal to the viewed surface of each moderator for four different cases of combinations of target coolant and reflector materials. The simulations reported here were performed using the MCNPX (version 2.1.5) computer program. Our results show that substantial gains in neutron beam intensities can be achieved by appropriate combination of target coolant and reflector materials. The combination o...

  11. Conceptual design for an accelerator system for a very high-intensity pulsed neutron source using a linear-induction accelerator

    International Nuclear Information System (INIS)

    Foss, M.H.

    1981-01-01

    Several accelerator-based intense neutron sources have been constructed or designed by various laboratories around the world. All of these facilities have a common scheme of a linac and synchrotron or accumulator ring, and the system produces the proton energy of 500 to 1000 MeV. The average beam currents range from a few mA to a few hundred mA. The protons are then used to generate high-flux neutrons by spallation out of heavy-metal targets. In a synchrotron system, the protons are already bunched, and thus the pulse rate of the neutron beam is that of the repetition rate of the synchrotron. For an accumulator system, the pulse rate is determined by the extraction repetition rate of the accumulator. We have conceptually designed a new system that uses a linear-induction accelerator which can be operated for an average beam current up to a few mA with a repetition rate up to 100 Hz. The details of the design will be given

  12. The National Spallation Neutron Source Collaboration: Towards a new pulsed neutron source in the United States

    International Nuclear Information System (INIS)

    Appleton, B.R.; Ball, J.B.; Alonso, J.R.; Gough, R.A.; Weng, W.T.; Jason, A.

    1996-01-01

    The US Department of Energy has commissioned Oak Ridge National Laboratory to initiate the conceptual design for a next-generation pulsed spallation neutron source. Current expectation is for a construction start in FY 1998, with commencement of operations in 2004. For this project, ORNL has entered into a collaborative arrangement with LBNL, BNL, LANL (and most recently ANL). The conceptual design study is now well underway, building on the strong base of the extensive work already performed by various Laboratories, as well as input from the user community (from special BESAC subpanels). Study progress, including accelerator configuration and plans for resolution of critical issues, is reported in this paper

  13. Neutron activation analysis with pulsed 14 MeV neutrons for the characterization of heterogeneous radioactive wastes; Neutronenaktivierungsanalyse mit gepulsten 14 MeV Neutronen zur Charakterisierung heterogener radioaktiver Abfaelle

    Energy Technology Data Exchange (ETDEWEB)

    Mildenberger, Frank

    2017-07-01

    For the transport, interim storage and disposal of radioactive waste, it is assumed to have knowledge of the radioactive and non-radioactive inventory. In order to determine the radioactive inventory destructive (e.g. α-, β-, γ-measurements according to wet chemical sample preparation) and non-destructive (e.g. γ-scanning and neutron measurements) measurement methods are used. For the characterization of non-radioactive substances a prototype for the assay of small-volume (50 L) samples was constructed and parameterized using the neutron activation analysis (NAA) with a pulsed 14 MeV neutron source. Subsequently, the non-destructive analytical method called MEDINA (Multi Element Detection Based on Instrumental Neutron Activation) for 200 l waste drums was developed in a cooperation between RWTH Aachen University and Forschungszentrum Juelich GmbH. The aim of this thesis is to investigate and characterize heterogeneous mixed samples regarding their material composition as well as their inhomogeneous distribution. For this purposes, studies were carried out on 200 l steel drums with heterogeneous matrices using the NAA in the MEDINA facility. The samples are composed out of a mixture of concrete and polyethylene (PE) bodies. Due to its high hydrogen content, the PE can have a strong influence on the neutron moderation and neutron absorption and can thereby occur as a possible disturbance variable in the characterization of the non-radioactive inventory. For these studies a pulsed 14 MeV neutron source is used to record the prompt and delayed γ-rays between the neutron pulses, separately. Thus, the performance of the MEDINA method relating to strongly moderating mixed matrices and their characterization is studied. In order to optimize the measurement of delayed γ-rays without any appreciable interference of prompt γ-rays, the decay of thermal neutrons was studied and the thermal neutron die-away time was determined. It ranges between 2 and 5 ms according to

  14. Study on boron-film thermal neutron converter prepared by pulsed laser deposition

    International Nuclear Information System (INIS)

    Song Zifeng; Ye Shuzhen; Chen Ziyu; Song Liao; Shen Ji

    2011-01-01

    The boron film converter used in the position-sensitive thermal neutron detector is discussed and the method of preparing this converter layer via Pulsed Laser Deposition (PLD) is introduced. The morphology and the composition were studied by Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). Both boron and boride existed on the layer surface. It was shown that the energy intensity of laser beam and the substrate temperature both had an important influence on the surface morphology of the film.

  15. Study on boron-film thermal neutron converter prepared by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Song Zifeng; Ye Shuzhen; Chen Ziyu; Song Liao [Department of Modern Physics, University of Science and Technology of China, Anhui Hefei 230026 (China); Shen Ji, E-mail: shenji@ustc.edu.c [Department of Modern Physics, University of Science and Technology of China, Anhui Hefei 230026 (China)

    2011-02-15

    The boron film converter used in the position-sensitive thermal neutron detector is discussed and the method of preparing this converter layer via Pulsed Laser Deposition (PLD) is introduced. The morphology and the composition were studied by Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). Both boron and boride existed on the layer surface. It was shown that the energy intensity of laser beam and the substrate temperature both had an important influence on the surface morphology of the film.

  16. Development of an Intelligent System to Synthesize Petrophysical Well Logs

    Directory of Open Access Journals (Sweden)

    Morteza Nouri Taleghani

    2013-07-01

    Full Text Available Porosity is one of the fundamental petrophysical properties that should be evaluated for hydrocarbon bearing reservoirs. It is a vital factor in precise understanding of reservoir quality in a hydrocarbon field. Log data are exceedingly crucial information in petroleum industries, for many of hydrocarbon parameters are obtained by virtue of petrophysical data. There are three main petrophysical logging tools for the determination of porosity, namely neutron, density, and sonic well logs. Porosity can be determined by the use of each of these tools; however, a precise analysis requires a complete set of these tools. Log sets are commonly either incomplete or unreliable for many reasons (i.e. incomplete logging, measurement errors, and loss of data owing to unsuitable data storage. To overcome this drawback, in this study several intelligent systems such as fuzzy logic (FL, neural network (NN, and support vector machine are used to predict synthesized petrophysical logs including neutron, density, and sonic. To accomplish this, the petrophysical well logs data were collected from a real reservoir in one of Iran southwest oil fields. The corresponding correlation was obtained through the comparison of synthesized log values with real log values. The results showed that all intelligent systems were capable of synthesizing petrophysical well logs, but SVM had better accuracy and could be used as the most reliable method compared to the other techniques.

  17. The secondary neutron sources for generation of particular neutron fluxes

    International Nuclear Information System (INIS)

    Tracz, G.

    2007-07-01

    The foregoing paper presents the doctor's thesis entitled '' The secondary neutron sources for generation of particular neutron fluxes ''. Two secondary neutron sources have been designed, which exploit already existing primary sources emitting neutrons of energies different from the desired ones. The first source is devoted to boron-neutron capture therapy (BNCT). The research reactor MARIA at the Institute of Atomic Energy in Swierk (Poland) is the primary source of the reactor thermal neutrons, while the secondary source should supply epithermal neutrons. The other secondary source is the pulsed source of thermal neutrons that uses fast 14 MeV neutrons from a pulsed generator at the Institute of Nuclear Physics PAN in Krakow (Poland). The physical problems to be solved in the two mentioned cases are different. Namely, in order to devise the BNCT source the initial energy of particles ought to be increased, whilst in the other case the fast neutrons have to be moderated. Slowing down of neutrons is relatively easy since these particles lose energy when they scatter in media; the most effective moderators are the materials which contain light elements (mostly hydrogen). In order to increase the energy of neutrons from thermal to epithermal (the BNCT case) the so-called neutron converter should be exploited. It contains a fissile material, 235 U. The thermal neutrons from the reactor cause fission of uranium and fast neutrons are emitted from the converter. Then fissile neutrons of energy of a few MeV are slowed down to the required epithermal energy range. The design of both secondary sources have been conducted by means of Monte Carlo simulations, which have been carried out using the MCNP code. In the case of the secondary pulsed thermal neutron source, some of the calculated results have been verified experimentally. (author)

  18. Investigations on the pulse operation of YAYOI

    International Nuclear Information System (INIS)

    1977-04-01

    This report is composed of ten independent documents concerning the pulse operation of YAYOI, which were prepared in the period between July, 1976, and March, 1977. The titles of the documents included in this report are: (1) the operational sequence of the linac neutron generating facility, (2) safety systems of linac pulse operation and the treatment and preservation of neutron generating targets, (3) nuclear calculation concerning linac pulse operation, (4) simulated natural uranium core, (5) linac neutron target system, (6) computer processing accompanying linac pulse operation, (7) fundamental concept of electron beam generation within the reactor room, (8) reactor room shielding requirements for the linac neutron source, (9) TOF measuring room, and (10) utilization of low energy neutrons from P-YAYOI operation. (Aoki, K.)

  19. Use of a high repetition rate neutron generator for in vivo body composition measurements via neutron inelastic scattering

    International Nuclear Information System (INIS)

    Kehayias, J.J.; Ellis, K.J.; Cohn, S.H.; Weinlein, J.H.

    1986-01-01

    A small D-T neutron generator with a high pulse rate is used for the in vivo measurement of body carbon, oxygen and hydrogen. The core of the neutron generator is a 13 cm-long Zetatron tube pulsed at a rate of 10 kHz delivering 10 3 to 10 4 neutrons per pulse. A target-current feedback system regulates the source of the accelerator to assure constant neutron output. Carbon is measured by detecting the 4.44 MeV γ-rays from inelastic scattering. The short half-life of the 4.44 MeV state of carbon requires detection of the γ-rays during the 10 μs neutron pulse. Generators with low pulsing rate were found inappropriate for carbon measurements because of their low duty-cycle (high neutron output during the pulse). In vivo measurements were performed with normal volunteers using a scanning bed facility for a dose less than 25 mrem. This technique offers medical as well as general bulk analysis applications. 8 refs., 5 figs

  20. Optimization of Pulsed Operation of the Superconducting Radio-Frequency (SRF) Cavities at the Spallation Neutron Source (SNS)

    International Nuclear Information System (INIS)

    Kim, Sang-Ho; Campisi, Isidoro E.

    2007-01-01

    In order to address the optimization in a pulsed operation, a systematic computational analysis has been made in comparison with operational experiences in superconducting radio-frequency (SRF) cavities at the Spallation Neutron Source (SNS). From the analysis it appears that the SNS SRF cavities can be operated at temperatures higher than 2.1 K, a fact resulting from both the pulsed nature of the superconducting cavities, the specific configuration of the existing cryogenic plant and the operating frequency