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Sample records for proportional scintillation counters

  1. A Gas Proportional Scintillation Counter with krypton filling

    NASA Astrophysics Data System (ADS)

    Monteiro, C. M. B.; Mano, R. D. P.; Barata, E. C. G. M.; Fernandes, L. M. P.; Freitas, E. D. C.

    2016-12-01

    A Gas Proportional Scintillation Counter filled with pure krypton was studied. Energy resolution below 10% for 5.9-keV X-rays was obtained with this prototype. This value is much better than the energy resolution obtained with proportional counters or other MPGDs with krypton filling. The krypton electroluminescence scintillation and ionisation thresholds were found to be about 0.5 and 3.5 kV cm-1bar-1, respectively.

  2. Proportional counter for X-ray analysis of lunar and planetary surfaces. [a position sensitive scintillating imaging proportional counter

    NASA Technical Reports Server (NTRS)

    1979-01-01

    A position sensitive proportional scintillation detector was developed and evaluated for use in applications involving X-ray imaging as well as spectroscopy. Topics covered include limitations of the proportional scintillation counter for use in space; purification of the xenon gas in the detector, and the operation of the detector system. Results show that the light signal in a proportional scintillation detector remains well localized. With modest electric fields in xenon, the primary electrons from a photoelectric absorption of an X-ray can be brought a distance of a few millimeters to a higher field region without spreading more than a millimeter or so. Therefore, it is possible to make a proportional scintillation detector with good position sensitivity that could be used to calibrate out the difference in light collection over its sensitive volume.

  3. An imaging gas scintillation proportional counter for the detection of subkiloelectron-volt X-rays

    NASA Technical Reports Server (NTRS)

    Hailey, C. J.; Ku, W. H. M.; Vartanian, M. H.

    1981-01-01

    A large area imaging gas scintillation proportional counter (IGSPC) was constructed for use in X-ray astronomy. The IGSPC consists of a gas scintillation proportional counted (GSPC) with a micron polyprotylene window coupled to a multiwire proportional counter (MWPC) via a calcium fluoride window. Over a sensitive area of 21 cu cm the instrument has a measured energy resolution of 17.5% (FWHM) and 1.9 mm (FWHM) spatial resolution at 1.5 keV.

  4. An imaging gas scintillation proportional counter for use in X-ray astronomy

    NASA Technical Reports Server (NTRS)

    Hailey, C. J.; Ku, W. H.-M.; Vartanian, M. H.

    1983-01-01

    An imaging gas scintillation proportional counter (GSPC) has been constructed for use in X-ray astronomy. The IGSPC consists of a gas scintillation proportional counter (GSPC) with a 1 micron polypropylene window coupled to a multiwire proportional counter (MWPC) via a calcium fluoride window. The MWPC, filled with a mixture of argon, methane, and tetrakis (dimethylamino) ethylene, detects the UV photons emitted by the xenon gas in the GSPC. The measured energy resolution is 17.0 percent (fwhm) and 8.0 percent (fwhm) at 1.5 keV and 5.9 keV, respectively. The measured position resolution is 1.9 mm (fwhm) and 0.9 mm (fwhm) at 1.5 and 5.9 keV, respectively. Possible astrophysical observations which can be performed with an IGSPC at the focal plane of a grazing incidence telescope are also discussed.

  5. Lithium glass scintillator neutron detector as an improved alternative to the standard 3 he proportional counter

    SciTech Connect

    Vladimir Popov, Pavel Degtiarenko

    2011-06-01

    Lithium glass scintillator made from 6Li-enriched substrate is a well known for its neutron detection capability. In spite of neutron interaction, cross section of 6Li happens to be lower than that of 3He. However, the neutron detection efficiency could be higher due to higher volume content of 6Li nuclear in the solid scintillator vs. gas filled proportional counter. At the same time, as lithium glass is sensitive to gamma and charge particle radiation, non-neutron radiation discrimination is required. Our detector is composed of two equal-size cylindrical Li(Ce) glass scintillators. The first one is high-sensitive to thermal neutrons GS-20 (6Li doped), the second one is GS-30 (7Li doped) type Scint-Gobain made lithium glass scintillator. Each of scintillators is coupled with R7400U Hamamatsu subminiature photomultiplier tube, and all assembly is fitted into NP100H 3He tube size. 6Li absorbs thermal neutrons releasing alpha particles and triton with 4.8 MeV total energy deposit inside the scintillator (equivalent to about ~1.3 MeV gamma energy depositions). Because 7Li isotope does not absorb thermal neutrons, and the physical properties of the two scintillators are virtually identical, the difference between these two scintillators could be used to provide neutron dose rate information. Results of study of neutron detector assembled of two Li(Ce) scintillators and NP100H moderator are presented

  6. A large area imaging gas scintillation proportional counter for use in X-ray astronomy

    NASA Technical Reports Server (NTRS)

    Ku, W. H.-M.; Lum, K. S.; Vartanian, M. H.

    1984-01-01

    A large area (200 sq cm), broad bandwidth (0.1-70 keV), imaging gas scintillation proportional counter (IGSPC) has been constructed for use in X-ray astronomy. The IGSPC consists of a high pressure xenon gas scintillation proportional counter (GSPC) coupled to a multi-wire proportional counter (MWPC) via a calcium fluoride window. THe MWPC, filled with a mixture of argon, methane, and tetrakis (dimethylamino) ethylene, detects the UV photons emitted by the xenon gas in the GSPC. The detector has a measured energy resolution of 8.0 percent (FWHM) and 4.3 percent (FWHM) at 5.9 keV and 22.1 keV, respectively. The predicted spatial resolution of the detector is less than 1 mm (FWHM) between 3-22 keV and 37-60 keV. A method to determine the three-dimensional location of detected X-rays is described. In addition, a combination of discrimination schemes designed to reduce the non-X-ray background in the IGSPC by more than two orders of magnitude is discussed.

  7. A high resolution gas scintillation proportional counter for studying low energy cosmic X-ray sources

    NASA Technical Reports Server (NTRS)

    Hamilton, T. T.; Hailey, C. J.; Ku, W. H.-M.; Novick, R.

    1980-01-01

    In recent years much effort has been devoted to the development of large area gas scintillation proportional counters (GSPCs) suitable for use in X-ray astronomy. The paper deals with a low-energy GSPC for use in detecting sub-keV X-rays from cosmic sources. This instrument has a measured energy resolution of 85 eV (FWHM) at 149 eV over a sensitive area of 5 sq cm. The development of imaging capability for this instrument is discussed. Tests are performed on the feasibility of using an arrangement of several phototubes placed adjacent to one another to determine event locations in a large flat counter. A simple prototype has been constructed and successfully operated.

  8. A High-Energy Focal-Plane Gas Scintillation Proportional Counter

    NASA Technical Reports Server (NTRS)

    Ramsey, B. D.; Austin, R. A.; Apple, J. A.; Dietz, K. L.

    1999-01-01

    We have developed a high-pressure Gas Scintillation Proportional Counter (GSPC) for the focus of a hard-x-ray telescope. It features an absorption region 50 mm in diameter and 50 mm deep, filled with Xenon + 4% He at 10(exp 6) Pa total pressure, which gives useful response (greater than 75% efficiency) up to the mirror cut-off of 70 keV. Tests with a prototype unit show an energy resolution of 3.5% at 60 keV and a spatial resolution of 0.35 mm from 30-50 keV. Two flight units are currently under construction for a balloon flight in September 1999. Full details of their design and performance will be presented together with available quick-look background data from the flight.

  9. Gas Scintillation Proportional Counters for High-Energy X-ray Astronomy

    NASA Technical Reports Server (NTRS)

    Gubarev, Mikhail; Ramsey, Brian; Apple, Jeffery

    2003-01-01

    A focal plane array of high-pressure gas scintillation proportional counters (GSPC) for a balloon-borne hard-x-ray telescope is under development at the Marshall Space Flight Center. These detectors have an active area of approx. 20 sq cm, and are filled with a high pressure (10(exp 6) Pa) xenon-helium mixture. Imaging is via crossed-grid position-sensitive phototubes sensitive in the UV region. The performance of the GSPC is well matched to that of the telescopes x-ray optics which have response to 75 keV and a focal spot size of approx. 500 microns. The detector s energy resolution, 4% FWHM at 60 keV, is adequate for resolving the broad spectral lines of astrophysical importance and for accurate continuum measurements. Full details of the instrument and its performance will be provided.

  10. Hybrid gas scintillation proportional counter/phoswich detector for hard X-ray astronomy

    NASA Technical Reports Server (NTRS)

    Grindlay, Jonathan E.; Manandhar, Raj P.

    1989-01-01

    A concept is presented for a balloon-borne imaging hybrid proportional counter/phoswich detector of medium to hard X-rays. The phoswich would be optically coupled to the exit window of the proportional counter, and both detectors would use a common position-sensitive readout. It is anticipated that such a detector could combine the good energy and position resolution and excellent background rejection ability of the proportional counter for incident photon energies less than 100 keV with the extended response of the phoswich for higher energies. The phoswich could also be used to reject Compton scattering events in the proportional counter. This detector concept is studied using numerical simulations of a 400 sq cm square prototype detector. Results from this simulation indicate that current levels of proportional counter and phoswich performance are attainable at small cost in quantum efficiency, compared to a bare phoswich detector.

  11. Performance of Gas Scintillation Proportional Counter Array for High-Energy X-Ray Observatory

    NASA Technical Reports Server (NTRS)

    Gubarev, Mikhail; Ramsey, Brian; Apple, Jeffery

    2004-01-01

    A focal plane array of high-pressure gas scintillation proportional counters (GSPC) for a High Energy X-Ray Observatory (HERO) is developed at the Marshall Space Flight Center. The array is consisted from eight GSPCs and is a part of balloon born payload scheduled to flight in May 2004. These detectors have an active area of approximately 20 square centimeters, and are filled with a high pressure (10(exp 6) Pa) xenon-helium mixture. Imaging is via crossed-grid position-sensitive phototubes sensitive in the UV region. The performance of the GSPC is well matched to that of the telescopes x-ray optics which have response to 75 keV and a focal spot size of approximately 500 microns. The detector's energy resolution, 4% FWHM at 60 keV, is adequate for resolving the broad spectral lines of astrophysical importance and for accurate continuum measurements. Results of the on-earth detector calibration will be presented and in-flight detector performance will be provided, as available.

  12. Scintillation Counters

    NASA Astrophysics Data System (ADS)

    Bell, Zane W.

    Scintillators find wide use in radiation detection as the detecting medium for gamma/X-rays, and charged and neutral particles. Since the first notice in 1895 by Roentgen of the production of light by X-rays on a barium platinocyanide screen, and Thomas Edison's work over the following 2 years resulting in the discovery of calcium tungstate as a superior fluoroscopy screen, much research and experimentation have been undertaken to discover and elucidate the properties of new scintillators. Scintillators with high density and high atomic number are prized for the detection of gamma rays above 1 MeV; lower atomic number, lower-density materials find use for detecting beta particles and heavy charged particles; hydrogenous scintillators find use in fast-neutron detection; and boron-, lithium-, and gadolinium-containing scintillators are used for slow-neutron detection. This chapter provides the practitioner with an overview of the general characteristics of scintillators, including the variation of probability of interaction with density and atomic number, the characteristics of the light pulse, a list and characteristics of commonly available scintillators and their approximate cost, and recommendations regarding the choice of material for a few specific applications. This chapter does not pretend to present an exhaustive list of scintillators and applications.

  13. Coincidence Proportional Counter

    DOEpatents

    Manley, J H

    1950-11-21

    A coincidence proportional counter having a plurality of collecting electrodes so disposed as to measure the range or energy spectrum of an ionizing particle-emitting source such as an alpha source, is disclosed.

  14. Proportional counter radiation camera

    DOEpatents

    Borkowski, C.J.; Kopp, M.K.

    1974-01-15

    A gas-filled proportional counter camera that images photon emitting sources is described. A two-dimensional, positionsensitive proportional multiwire counter is provided as the detector. The counter consists of a high- voltage anode screen sandwiched between orthogonally disposed planar arrays of multiple parallel strung, resistively coupled cathode wires. Two terminals from each of the cathode arrays are connected to separate timing circuitry to obtain separate X and Y coordinate signal values from pulse shape measurements to define the position of an event within the counter arrays which may be recorded by various means for data display. The counter is further provided with a linear drift field which effectively enlarges the active gas volume of the counter and constrains the recoil electrons produced from ionizing radiation entering the counter to drift perpendicularly toward the planar detection arrays. A collimator is interposed between a subject to be imaged and the counter to transmit only the radiation from the subject which has a perpendicular trajectory with respect to the planar cathode arrays of the detector. (Official Gazette)

  15. The microstrip proportional counter

    NASA Technical Reports Server (NTRS)

    Ramsey, B. D.

    1992-01-01

    Microstrip detectors in which the usual discrete anode and cathode wires are replaced by conducting strips on an insulating or partially insulating substrate are fabricated using integrated circuit-type photolithographic techniques and hence offer very high spatial accuracy and uniformity, together with the capability of producing extremely fine electrode structures. Microstrip proportional counters have now been variously reported having an energy resolution of better than 11 percent FWHM at 5.9 keV. They have been fabricated with anode bars down to 2 microns and on a variety of substrate materials including thin films which can be molded to different shapes. This review will examine the development of the microstrip detector with emphasis on the qualities which make this detector particularly interesting for use in astronomy.

  16. Air Proportional Counter

    DOEpatents

    Simpson, Jr, J A

    1950-12-05

    A multiple wire counter utilizing air at atmospheric pressure as the ionizing medium and having a window of a nylon sheet of less than 0.5 mil thickness coated with graphite. The window is permeable to alpha particles so that the counter is well adapted to surveying sources of alpha radiation.

  17. GASEOUS SCINTILLATION COUNTER

    DOEpatents

    Eggler, C.; Huddleston, C.M.

    1959-04-28

    A gaseous excitation counter for detecting the presence amd measuring the energy of subatomic particles and electromagnetic radiation is described. The counter includes a gas-tight chamber filled with an elemental gas capable of producing ultra-violet excitation quanta when irradiated with subatomic particles and electromagnetic radiation. The gas has less than one in a thousand parts ultra-violet absorbing contamination. When nuclear radiation ps present the ultra-violet light produced by the gas strikes a fluorescent material within the counter, responsive to produce visible excitation quanta, and photo-sensitive counting means detect the visible emission.

  18. Photodetectors for Scintillator Proportionality Measurement

    SciTech Connect

    Moses, William W.; Choong, Woon-Seng; Hull, Giulia; Payne, Steve; Cherepy, Nerine; Valentine, J.D.

    2010-10-18

    We evaluate photodetectors for use in a Compton Coincidence apparatus designed for measuring scintillator proportionality. There are many requirements placed on the photodetector in these systems, including active area, linearity, and the ability to accurately measure low light levels (which implies high quantum efficiency and high signal-to-noise ratio). Through a combination of measurement and Monte Carlo simulation, we evaluate a number of potential photodetectors, especially photomultiplier tubes and hybrid photodetectors. Of these, we find that the most promising devices available are photomultiplier tubes with high ({approx}50%) quantum efficiency, although hybrid photodetectors with high quantum efficiency would be preferable.

  19. Broad Energy Range Neutron Spectroscopy using a Liquid Scintillator and a Proportional Counter: Application to a Neutron Spectrum Similar to that from an Improvised Nuclear Device.

    PubMed

    Xu, Yanping; Randers-Pehrson, Gerhard; Marino, Stephen A; Garty, Guy; Harken, Andrew; Brenner, David J

    2015-09-11

    A novel neutron irradiation facility at the Radiological Research Accelerator Facility (RARAF) has been developed to mimic the neutron radiation from an Improvised Nuclear Device (IND) at relevant distances (e.g. 1.5 km) from the epicenter. The neutron spectrum of this IND-like neutron irradiator was designed according to estimations of the Hiroshima neutron spectrum at 1.5 km. It is significantly different from a standard reactor fission spectrum, because the spectrum changes as the neutrons are transported through air, and it is dominated by neutron energies from 100 keV up to 9 MeV. To verify such wide energy range neutron spectrum, detailed here is the development of a combined spectroscopy system. Both a liquid scintillator detector and a gas proportional counter were used for the recoil spectra measurements, with the individual response functions estimated from a series of Monte Carlo simulations. These normalized individual response functions were formed into a single response matrix for the unfolding process. Several accelerator-based quasi-monoenergetic neutron source spectra were measured and unfolded to test this spectroscopy system. These reference neutrons were produced from two reactions: T(p,n)(3)He and D(d,n)(3)He, generating neutron energies in the range between 0.2 and 8 MeV. The unfolded quasi-monoenergetic neutron spectra indicated that the detection system can provide good neutron spectroscopy results in this energy range. A broad-energy neutron spectrum from the (9)Be(d,n) reaction using a 5 MeV deuteron beam, measured at 60 degrees to the incident beam was measured and unfolded with the evaluated response matrix. The unfolded broad neutron spectrum is comparable with published time-of-flight results. Finally, the pair of detectors were used to measure the neutron spectrum generated at the RARAF IND-like neutron facility and a comparison is made to the neutron spectrum of Hiroshima.

  20. Broad Energy Range Neutron Spectroscopy using a Liquid Scintillator and a Proportional Counter: Application to a Neutron Spectrum Similar to that from an Improvised Nuclear Device

    PubMed Central

    Randers-Pehrson, Gerhard; Marino, Stephen A.; Garty, Guy; Harken, Andrew; Brenner, David J.

    2015-01-01

    A novel neutron irradiation facility at the Radiological Research Accelerator Facility (RARAF) has been developed to mimic the neutron radiation from an Improvised Nuclear Device (IND) at relevant distances (e.g. 1.5 km) from the epicenter. The neutron spectrum of this IND-like neutron irradiator was designed according to estimations of the Hiroshima neutron spectrum at 1.5 km. It is significantly different from a standard reactor fission spectrum, because the spectrum changes as the neutrons are transported through air, and it is dominated by neutron energies from 100 keV up to 9 MeV. To verify such wide energy range neutron spectrum, detailed here is the development of a combined spectroscopy system. Both a liquid scintillator detector and a gas proportional counter were used for the recoil spectra measurements, with the individual response functions estimated from a series of Monte Carlo simulations. These normalized individual response functions were formed into a single response matrix for the unfolding process. Several accelerator-based quasi-monoenergetic neutron source spectra were measured and unfolded to test this spectroscopy system. These reference neutrons were produced from two reactions: T(p,n)3He and D(d,n)3He, generating neutron energies in the range between 0.2 and 8 MeV. The unfolded quasi-monoenergetic neutron spectra indicated that the detection system can provide good neutron spectroscopy results in this energy range. A broad-energy neutron spectrum from the 9Be(d,n) reaction using a 5 MeV deuteron beam, measured at 60 degrees to the incident beam was measured and unfolded with the evaluated response matrix. The unfolded broad neutron spectrum is comparable with published time-of-flight results. Finally, the pair of detectors were used to measure the neutron spectrum generated at the RARAF IND-like neutron facility and a comparison is made to the neutron spectrum of Hiroshima. PMID:26273118

  1. Broad energy range neutron spectroscopy using a liquid scintillator and a proportional counter: Application to a neutron spectrum similar to that from an improvised nuclear device

    NASA Astrophysics Data System (ADS)

    Xu, Yanping; Randers-Pehrson, Gerhard; Marino, Stephen A.; Garty, Guy; Harken, Andrew; Brenner, David J.

    2015-09-01

    A novel neutron irradiation facility at the Radiological Research Accelerator Facility (RARAF) has been developed to mimic the neutron radiation from an Improvised Nuclear Device (IND) at relevant distances (e.g. 1.5 km) from the epicenter. The neutron spectrum of this IND-like neutron irradiator was designed according to estimations of the Hiroshima neutron spectrum at 1.5 km. It is significantly different from a standard reactor fission spectrum, because the spectrum changes as the neutrons are transported through air, and it is dominated by neutron energies from 100 keV up to 9 MeV. To verify such wide energy range neutron spectrum, detailed here is the development of a combined spectroscopy system. Both a liquid scintillator detector and a gas proportional counter were used for the recoil spectra measurements, with the individual response functions estimated from a series of Monte Carlo simulations. These normalized individual response functions were formed into a single response matrix for the unfolding process. Several accelerator-based quasi-monoenergetic neutron source spectra were measured and unfolded to test this spectroscopy system. These reference neutrons were produced from two reactions: T(p,n)3He and D(d,n)3He, generating neutron energies in the range between 0.2 and 8 MeV. The unfolded quasi-monoenergetic neutron spectra indicated that the detection system can provide good neutron spectroscopy results in this energy range. A broad-energy neutron spectrum from the 9Be(d,n) reaction using a 5 MeV deuteron beam, measured at 60 degrees to the incident beam was measured and unfolded with the evaluated response matrix. The unfolded broad neutron spectrum is comparable with published time-of-flight results. Finally, the pair of detectors were used to measure the neutron spectrum generated at the RARAF IND-like neutron facility and a comparison is made to the neutron spectrum of Hiroshima.

  2. Scintillation counter with WLS fiber readout

    NASA Astrophysics Data System (ADS)

    Bukin, D. A.; Druzhinin, V. P.; Golubev, V. B.; Serednyakov, S. I.

    1997-02-01

    The parameters of a cylindrical scintillation counter of 126 mm in diameter and 370 mm in length with wavelength shifter (WLS) fiber readout are presented. The fibers are glued into machined grooves along the scintillator. Light from both ends of the WLS fibers is transmitted to separate photomultipliers by 1 m long clear optical fibers. The average total signal, collected from both sides of the counter is equivalent to 8 photoelectrons per minimum ionizing particle. The described cylindrical scintillation counter is a part of inner system of collider detector SND.

  3. Progress in studying scintillator proportionality: Phenomenological model

    SciTech Connect

    Bizarri, Gregory; Cherepy, Nerine; Choong, Woon-Seng; Hull, Giulia; Moses, William; Payne, Sephen; Singh, Jai; Valentine, John; Vasilev, Andrey; Williams, Richard

    2009-04-30

    We present a model to describe the origin of non-proportional dependence of scintillator light yield on the energy of an ionizing particle. The non-proportionality is discussed in terms of energy relaxation channels and their linear and non-linear dependences on the deposited energy. In this approach, the scintillation response is described as a function of the deposited energy deposition and the kinetic rates of each relaxation channel. This mathematical framework allows both a qualitative interpretation and a quantitative fitting representation of scintillation non-proportionality response as function of kinetic rates. This method was successfully applied to thallium doped sodium iodide measured with SLYNCI, a new facility using the Compton coincidence technique. Finally, attention is given to the physical meaning of the dominant relaxation channels, and to the potential causes responsible for the scintillation non-proportionality. We find that thallium doped sodium iodide behaves as if non-proportionality is due to competition between radiative recombinations and non-radiative Auger processes.

  4. Boron-10 Lined Proportional Counter Wall Effects

    SciTech Connect

    Siciliano, Edward R.; Kouzes, Richard T.

    2012-05-01

    The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube based system in the configuration of a coincidence counter. This report provides information about how variations in proportional counter radius and gas pressure in a typical coincident counter design might affect the observed signal from boron-lined tubes. A discussion comparing tubes to parallel plate counters is also included.

  5. Scintillator fiber optic long counter

    DOEpatents

    McCollum, T.; Spector, G.B.

    1994-03-29

    A flat response position sensitive neutron detector capable of providing neutron spectroscopic data utilizing scintillator fiber optic filaments embedded in a neutron moderating housing having an open end through which neutrons enter to be detected is described. 11 figures.

  6. Scintillator fiber optic long counter

    DOEpatents

    McCollum, Tom; Spector, Garry B.

    1994-01-01

    A flat response position sensitive neutron detector capable of providing neutron spectroscopic data utilizing scintillator fiber optic filaments embedded in a neutron moderating housing having an open end through which neutrons enter to be detected.

  7. Neutron spectrometry with He-3 proportional counters

    SciTech Connect

    Manolopoulou, M.; Fragopoulou, M.; Stoulos, S.; Vagena, E.; Westmeier, W.; Zamani, M.

    2011-07-01

    Helium filled proportional counters are widely used in the field of neutron detection and spectrometry. In this work the response of a commercially available He-3 counter is studied experimentally and calculated with Monte Carlo for the neutron energy range from 230 keV up to about 7 MeV. The calculated response of the system is used to determine neutron yield energy distribution emitted from an extended {sup nat}U/Pb assembly irradiated with 1.6 GeV deuterons. The results are in acceptable agreement with the calculated neutron distribution with DCM-DEM code. (authors)

  8. Gamma heating measurements with proportional counters

    SciTech Connect

    Chiu, H.; Bennett, E.F.; Micklich, B.J.

    1990-05-01

    A new data acquisition technique (the Continuously-varied Bias- voltage Acquisition mode) has been developed and tested for the low-flux broad-energy regime characteristic of existing fusion blanket mock-ups. This method of analysis allows for the acquisition of data spanning several orders of magnitude in energy with a single proportional counter. Utilizing this method, the gamma energy deposition in a mixed neutron and gamma field was measured. 7 refs., 5 figs.

  9. Boron-10 Lined Proportional Counter Model Validation

    SciTech Connect

    Lintereur, Azaree T.; Siciliano, Edward R.; Kouzes, Richard T.

    2012-06-30

    The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project “Coincidence Counting With Boron-Based Alternative Neutron Detection Technology” at Pacific Northwest National Laboratory (PNNL) for the development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube-based alternative system in the configuration of a coincidence counter. This report discusses the validation studies performed to establish the degree of accuracy of the computer modeling methods current used to simulate the response of boron-lined tubes. This is the precursor to developing models for the uranium neutron coincidence collar under Task 2 of this project.

  10. Microstrip proportional counter development at MSFC

    NASA Technical Reports Server (NTRS)

    Fulton, M. A.; Kolodziejczak, J. J.; Ramsey, B. D.

    1992-01-01

    Microstrip detectors are an exciting new development in proportional counter design fabricated using integrated circuit-type photolithography techniques; they therefore offer very high spatial accuracy and uniformity. A development program is underway at NASA-Marshall to produce large-area microstrips for use in an X-ray detector balloon flight program and to investigate the general performance limits of these new devices. Microstrips tested so far have been fabricated both in-house using standard photolithographic techniques and by an outside contractor using electron beam technology. Various substrate materials have been tested along with different electrode configurations. The distributions of pickup on subdivided cathodes on both top and bottom surfaces of the microstrips are also being investigated for use as two-dimensional imaging detectors. Data from these tests in the development of a large-area device will be presented.

  11. Development of a liquid scintillator neutron multiplicity counter (LSMC)

    NASA Astrophysics Data System (ADS)

    Frame, Katherine; Clay, Willam; Elmont, Tim; Esch, Ernst; Karpius, Peter; MacArthur, Duncan; McKigney, Edward; Santi, Peter; Smith, Morag; Thron, Jonathan; Williams, Richard

    2007-08-01

    A new neutron multiplicity counter is being developed that utilizes the fast response of liquid scintillator detectors. The ability to detect fast (vs. moderated) fission neutrons makes possible a coincidence gate of the order of tens of nanoseconds (vs. tens of microseconds). A neutron counter with such a narrow gate will be virtually insensitive to accidental coincidences, making it possible to measure items with a high single neutron background to greater accuracy in less time. This includes impure Pu items with high (α, n) rates as well as items of low-mass HEU where a strong active interrogation source is needed. Liquid scintillator detectors also allow for energy discrimination between interrogation source neutrons and fission neutrons, allowing for even greater assay sensitivity. Designing and building a liquid scintillator multiplicity counter (LSMC) requires a symbiotic effort of simulation and experiment to optimize performance and mitigate hardware costs in the final product. We present preliminary Monte-Carlo studies using the GEANT toolkit.

  12. Scintillation counters in modern high-energy physics experiments (Review)

    NASA Astrophysics Data System (ADS)

    Kharzheev, Yu. N.

    2015-07-01

    Scintillation counters (SCs) based on organic plastic scintillators (OPSs) are widely used in modern high-energy physics (HEP) experiments. A comprehensive review is given to technologies for production of OPS strips and tiles (extrusion, injection molding, etc.), optical and physical characteristics of OPSs, and methods of light collection based on the use of wavelength-shifting (WLS) fibers coupled to multipixel vacuum and silicon PMs. Examples are given of the use of SCs in modern experiments involved in the search for quarks and new particles, including the Higgs boson (D0, CDF, ATLAS, CMS), new states of matter (ALICE), CP violation (LHCb, KLOE), neutrino oscillations (MINOS, OPERA), and cosmic particles in a wide mass and energy interval (AMS-02). Scintillation counters hold great promise for future HEP experiments (at the ILC, NICA, FAIR) due to properties of a high segmentation, WLS fiber light collection, and multipixel silicon PMT readout.

  13. Time statistics of the photoelectron emission process in scintillation counters

    NASA Astrophysics Data System (ADS)

    Ranucci, Gioacchino

    1993-10-01

    In this work the statistical time properties of the photoelectron emission process in scintillation counters are evaluated assuming that the total number of emitted photoelectrons is distributed according to a generic random distribution. Under this general assumption, the probability density function of the time of emission of the ith photoelectron is computed; it is also demonstrated that if the number of emitted photoelectrons is Poisson distributed, this probability density function reduces to the expression already published for this particular case. Finally the procedure adopted is extended to give the expressions predicting the performances of organic scintillators for the pulse shape discrimination of particles of different type.

  14. Multianode cylindrical proportional counter for high count rates

    DOEpatents

    Hanson, J.A.; Kopp, M.K.

    1980-05-23

    A cylindrical, multiple-anode proportional counter is provided for counting of low-energy photons (< 60 keV) at count rates of greater than 10/sup 5/ counts/sec. A gas-filled proportional counter cylinder forming an outer cathode is provided with a central coaxially disposed inner cathode and a plurality of anode wires disposed in a cylindrical array in coaxial alignment with and between the inner and outer cathodes to form a virtual cylindrical anode coaxial with the inner and outer cathodes. The virtual cylindrical anode configuration improves the electron drift velocity by providing a more uniform field strength throughout the counter gas volume, thus decreasing the electron collection time following the detection of an ionizing event. This avoids pulse pile-up and coincidence losses at these high count rates. Conventional RC position encoding detection circuitry may be employed to extract the spatial information from the counter anodes.

  15. Multianode cylindrical proportional counter for high count rates

    DOEpatents

    Hanson, James A.; Kopp, Manfred K.

    1981-01-01

    A cylindrical, multiple-anode proportional counter is provided for counting of low-energy photons (<60 keV) at count rates of greater than 10.sup.5 counts/sec. A gas-filled proportional counter cylinder forming an outer cathode is provided with a central coaxially disposed inner cathode and a plurality of anode wires disposed in a cylindrical array in coaxial alignment with and between the inner and outer cathodes to form a virtual cylindrical anode coaxial with the inner and outer cathodes. The virtual cylindrical anode configuration improves the electron drift velocity by providing a more uniform field strength throughout the counter gas volume, thus decreasing the electron collection time following the detection of an ionizing event. This avoids pulse pile-up and coincidence losses at these high count rates. Conventional RC position encoding detection circuitry may be employed to extract the spatial information from the counter anodes.

  16. Modelling boron-lined proportional counter response to neutrons.

    PubMed

    Shahri, A; Ghal-Eh, N; Etaati, G R

    2013-09-01

    The detailed Monte Carlo simulation of a boron-lined proportional counter response to a neutron source has been presented. The MCNP4C and experimental data on different source-moderator geometries have been given for comparison. The influence of different irradiation geometries and boron-lining thicknesses on the detector response has been studied.

  17. Transmission Line Properties of Nickel-Bodied Proportional Counters

    NASA Astrophysics Data System (ADS)

    Ryu, Jennifer

    2008-10-01

    Simultaneous measurements of neutral current and charged current neutrino scattering events allowed the Sudbury Neutrino Observatory (SNO) to demonstrate definitively neutrino oscillation. The three phases of the SNO detector are distinguished by different techniques of detecting the neutrons produced by neutral current neutrino scattering. In the final phase, nickel-bodied proportional counters filled with ^3He were used as neutral current detectors (NCDs) by observing the charged particles produced by neutron capture on ^3He. If we can understand the electrical transmission properties of the NCDs, we can use the different pulse shapes produced by neutron captures compared to those of alphas to distinguish these events and gain more sensitivity to the neutral current events. We found that because of the ferromagnetism of the nickel, standard calculations provided for proportional counters are not accurate enough. To obtain a better calculation, we directly measured the electrical properties of the transmission line as a function of frequency. This is a presentation of our results.

  18. Measurements of electron attachment by oxygen molecule in proportional counter

    NASA Astrophysics Data System (ADS)

    Tosaki, M.; Kawano, T.; Isozumi, Y.

    2013-11-01

    We present pulse height measurements for 5-keV Auger electrons from a radioactive 55Fe source mounted at the inner cathode surface of cylindrical proportional counter, which is operated with CH4 admixed dry air or N2. A clear shift of the pulse height has been observed by varying the amount of the admixtures; the number of electrons, created in the primary ionization by Auger electrons, is decreased by the electron attachment of the admixtures during their drift from the place near the source to the anode wire. The large gas amplification (typically 104) in the secondary ionization of proportional counter makes it possible to investigate a small change in the number of primary electrons. The electron attenuation cross-section of O2 has been evaluated by analyzing the shifts of the pulse height caused by the electron attachment to dry air and N2.

  19. A complete database for the Einstein imaging proportional counter

    NASA Technical Reports Server (NTRS)

    Helfand, David J.

    1991-01-01

    A complete database for the Einstein Imaging Proportional Counter (IPC) was completed. The original data that makes up the archive is described as well as the structure of the database, the Op-Ed analysis system, the technical advances achieved relative to the analysis of (IPC) data, the data products produced, and some uses to which the database has been put by scientists outside Columbia University over the past year.

  20. Automatic method to manufacture 2D Multiwire Proportional Counter frames

    NASA Astrophysics Data System (ADS)

    Martínez, J. C.; Ramos-Lerate, I.; Fernández, F.; Beltrán, D.; Bordas, J.

    2007-04-01

    In this paper, a complete solution to manufacture anodes and cathodes for a Multiwire Proportional Counter (MWPC) is described. The solution consists of a semiautomatic winding machine and a soldering method by radiation. This method allows manufacturing one frame (electrode) in 3 h with a minimum human intervention. The machine can work with several types of frames and a great accuracy in the position and the stress of the wires can be achieved.

  1. Quench gases for xenon- (and krypton-) filled proportional counters

    NASA Technical Reports Server (NTRS)

    Ramsey, B. D.; Agrawal, P. C.

    1988-01-01

    Xenon-filled proportional counters are used extensively in astronomy, particularly in the hard X-ray region. The choice of quench gas can have a significant effect on the operating characteristics of the instrument although the data necessary to make the choice are not easily obtainable. Results which detail the performance obtained from both cylindrical and parallel field geometries for a wide variety of readily available, ultrahigh or research grade purity, quench gases are presented.

  2. Optical Design Considerations for Efficient Light Collection from Liquid Scintillation Counters

    SciTech Connect

    Bernacki, Bruce E.; Douglas, Matthew; Erchinger, Jennifer L.; Fuller, Erin S.; Keillor, Martin E.; Morley, Shannon M.; Mullen, Crystal A.; Orrell, John L.; Panisko, Mark E.; Warren, Glen A.; Wright, Michael E.

    2015-01-01

    Liquid scintillation counters measure charged particle-emitting radioactive isotopes and are used for environmental studies, nuclear chemistry, and life science. Alpha and beta emissions arising from the material under study interact with the scintillation cocktail to produce light. The prototypical liquid scintillation counter employs low-level photon-counting detectors to measure the arrival of the scintillation light produced as a result of the dissolved material under study interacting with the scintillation cocktail. For reliable operation the counting instrument must convey the scintillation light to the detectors efficiently and predictably. Current best practices employ the use of two or more detectors for coincidence processing to discriminate true scintillation events from background events due to instrumental effects such as photomultiplier tube dark rates, tube flashing, or other light emission not generated in the scintillation cocktail vial. In low background liquid scintillation counters additional attention is paid to shielding the scintillation cocktail from naturally occurring radioactive material (NORM) present in the laboratory and within the instruments construction materials. Low background design is generally at odds with optimal light collection. This study presents the evolution of a light collection design for liquid scintillation counting in a low background shield. The basic approach to achieve both good light collection and a low background measurement is described. The baseline signals arising from the scintillation vial are modeled and methods to efficiently collect scintillation light are presented as part of the development of a customized low-background, high sensitivity liquid scintillation counting system.

  3. Response of a tissue equivalent proportional counter to neutrons

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Robbins, D. E.; Gibbons, F.; Braby, L. A.

    2002-01-01

    The absorbed dose as a function of lineal energy was measured at the CERN-EC Reference-field Facility (CERF) using a 512-channel tissue equivalent proportional counter (TEPC), and neutron dose equivalent response evaluated. Although there are some differences, the measured dose equivalent is in agreement with that measured by the 16-channel HANDI tissue equivalent counter. Comparison of TEPC measurements with those made by a silicon solid-state detector for low linear energy transfer particles produced by the same beam, is presented. The measurements show that about 4% of dose equivalent is delivered by particles heavier than protons generated in the conducting tissue equivalent plastic. c2002 Elsevier Science Ltd. All rights reserved.

  4. Development of a proportional scintillation x-ray imaging chamber for synchrotron radiation experiments

    NASA Astrophysics Data System (ADS)

    Suzuki, Masayo; Takahashi, Tan; Awaya, Yohko; Oura, Masaki; Yamamoto, Masaki; Uruga, Tomoya; Mizogawa, Tatsumi; Masuda, Kimiaki

    1995-02-01

    Proportional scintillation x-ray imaging chamber (PSXIC) is a new type of two-dimensional position-sensitive x-ray detector composed of a spherical drift chamber, a parallel plate avalanche counter, and an image-intensifier-associated charge coupled device camera. A prototype of PSXIC filled with xenon (97%)+triethylamine (3%) gaseous mixture has been stably operated under a high flux of x-ray irradiation. The spatial resolution the prototype can attain has been found better than 800 μm. The time-resolved imaging capability has also been examined by taking time-varying x-ray images of a test pattern with a time resolution of 1/30 s.

  5. Gas amplification factor in neon-nitrogen filled proportional counters

    NASA Astrophysics Data System (ADS)

    Othman, A.

    1988-07-01

    The gas amplification factor in a cylindrical proportional counter filled with NeN 2 Penning mixtures has been measured (over the range 1 < A < 6.4 × 10 3) to verify the validity of the gas gain formulae of Rose and Korff, Khristov, Williams and Sara, Diethorn and Zastawny. This factor has been found to obey Zastawny's formula over the range of variables studied. The formula of Diethorn can be fitted only for small nitrogen concentrations (below 5 × 10 -4). Constants appropriate to the Zastawny and Diethorn formulae have been determined over a wide range of N 2 concentrations from spectroscopically pure Ne up to 11.1% N 2.

  6. Proportional counter windows for the Bragg Crystal Spectrometer on AXAF

    NASA Technical Reports Server (NTRS)

    Markert, T. H.; Bauer, J. M.; Canizares, C. R.; Isobe, T.; Nenonen, S.; O'Connor, J.; Schattenburg, M. L.; Flanagan, K. A.; Zombeck, M. V.

    1991-01-01

    A Bragg Crystal Spectrometer (BCS) using a gas flow proportional counter as its primary detector is among the instruments under development for AXAF. The BCS will employ windows of 1-micron-thick polyimide coated on both sides with 200 A of Al; this window composition, while X-ray transmitting, will leak gas at a lower rate than the polypropylene film-based windows formerly employed. Accounts are given of the results obtained with additional innovative X-ray window materials currently under development, including diamond and Si-enriched Si3N4.

  7. Alpha Backgrounds in the SNO ^3He Proportional Counter Array

    NASA Astrophysics Data System (ADS)

    Stonehill, Laura

    2006-04-01

    The Sudbury Neutrino Observatory (SNO) has recently deployed an array of proportional counters known as Neutral Current Detectors (NCDs) to detect thermalized neutrons via the ^3He(n,p)^3H reaction. The primary physics background to the neutron-capture signal is alpha particle emission from uranium- and thorium-chain decays in the NCD walls. The expected capture rate of neutrons from the neutral-current neutrino reaction on deuterium is three per day and the intrinsic alpha background rate is approximately 250 alphas per day. Fewer than 10% of these alphas fall into the energy range where neutron-capture signals occur, and a substantial number of these can be eliminated by pulse-shape analysis. This talk will focus on measurements of the alpha backgrounds in the NCDs and the extent to which these alphas contaminate the neutron-capture signal region.

  8. A multiwire proportional counter system for high energy astrophysics

    NASA Technical Reports Server (NTRS)

    Lacy, J. L.; Badhwar, G. D.; Deney, C. L.; Golden, R. L.

    1974-01-01

    Resolution tests of multiwire proportional counter delay line readout systems are reported. The system is being developed at NASA/JSC for use in a large balloon borne magnet spectrometer. The system is ultimately intended for use in Space Shuttle missions. Tests of two different types of delay line and associated electronics carried out in minimum ionizing particle beams (accelerator and sea level cosmic ray) are reported. Resolution performance is shown to be strongly dependent on type of gas mixture and in the case of inclined events upon the propagation velocity of the delay line. The resolution performance achieved for magic gas chamber filling (100 um at normal incidence) is far superior to any other state of the art technique capable of being applied to large geometry factor systems.

  9. A Complete Public Archive for the Einstein Imaging Proportional Counter

    NASA Technical Reports Server (NTRS)

    Helfand, David J.

    1996-01-01

    Consistent with our proposal to the Astrophysics Data Program in 1992, we have completed the design, construction, documentation, and distribution of a flexible and complete archive of the data collected by the Einstein Imaging Proportional Counter. Along with software and data delivered to the High Energy Astrophysics Science Archive Research Center at Goddard Space Flight Center, we have compiled and, where appropriate, published catalogs of point sources, soft sources, hard sources, extended sources, and transient flares detected in the database along with extensive analyses of the instrument's backgrounds and other anomalies. We include in this document a brief summary of the archive's functionality, a description of the scientific catalogs and other results, a bibliography of publications supported in whole or in part under this contract, and a list of personnel whose pre- and post-doctoral education consisted in part in participation in this project.

  10. Calibration and optimization of proportional counter modules using Garfield

    SciTech Connect

    Chung, Kiwhan; Brockwell, Michael I; Borozdin, Konstantin N; Green, J Andrew; Hogan, Gary E; Makela, Mark F; Mariam, Fesseha G; Morris, Christopher L

    2010-01-01

    Prototypes of radiation detector arrays used for charged-particle radiography require iniliol calibration to correlate the distribution of electron arrival time to the particle track locations. This step is crucial to obtaining the spatial resolution necessary to separate particle tracks traversing the individual proportional counters in the arrays. Our past attempts to use cosmic rays alone for the initial calibration have fallen short of obtaining the desired resolution due to the insufficient cosmic ray flux to provide the necessary number of particle tracks. A theoretical relation between electron drift time and radial drift distance is obtained with Garfield, a CERN gas detector simulation program. This relation is then used as an effective starting point for the initial calibration and results in a shorter calibration period and improved spatial resolution of the detectors.

  11. Compact multiwire proportional counters for the detection of fission fragments

    SciTech Connect

    Jhingan, Akhil; Sugathan, P.; Golda, K. S.; Singh, R. P.; Varughese, T.; Singh, Hardev; Behera, B. R.; Mandal, S. K.

    2009-12-15

    Two large area multistep position sensitive (two dimensional) multiwire proportional counters have been developed for experiments involving study of fission dynamics using general purpose scattering chamber facility at IUAC. Both detectors have an active area of 20x10 cm{sup 2} and provide position signals in horizontal (X) and vertical (Y) planes, timing signal for time of flight measurements and energy signal giving the differential energy loss in the active volume. The design features are optimized for the detection of low energy heavy ions at very low gas pressures. Special care was taken in setting up the readout electronics, constant fraction discriminators for position signals in particular, to get optimum position and timing resolutions along with high count rate handling capability of low energy heavy ions. A custom made charge sensitive preamplifier, having lower gain and shorter decay time, has been developed for extracting the differential energy loss signal. The position and time resolutions of the detectors were determined to be 1.1 mm full width at half maximum (FWHM) and 1.7 ns FWHM, respectively. The detector could handle heavy ion count rates exceeding 20 kHz without any breakdown. Time of flight signal in combination with differential energy loss signal gives a clean separation of fission fragments from projectile and target like particles. The timing and position signals of the detectors are used for fission coincidence measurements and subsequent extraction of their mass, angular, and total kinetic energy distributions. This article describes systematic study of these fission counters in terms of efficiency, time resolution, count rate handling capability, position resolution, and the readout electronics. The detector has been operated with both five electrode geometry and four electrode geometry, and a comparison has been made in their performances.

  12. GAMMA PROPORTIONAL COUNTER CONTAINING HIGH Z GAS AND LOW Z MODERATOR

    DOEpatents

    Fox, R.

    1963-07-23

    A gamma radiation counter employing a gas proportional counter is described. The radiation counter comprises a cylindrical gas proportional counter which contains a high atomic number gas and is surrounded by a low atomic number gamma radiation moderator material. At least one slit is provided in the moderator to allow accident gamma radiation to enter the moderator in the most favorable manner for moderation, and also to allow low energy gamma radiation to enter the counter without the necessity of passing through the moderator. This radiation counter is capable of detecting and measuring gamma radiation in the energy range of 0.5-5 Mev. (AEC)

  13. Four pi-recoil proportional counter used as neutron spectrometer

    NASA Technical Reports Server (NTRS)

    Bennett, E. F.

    1968-01-01

    Study considers problems encountered in using 4 pi-recoil counters for neutron spectra measurement. Emphasis is placed on calibration, shape discrimination, variation of W, the average energy loss per ion pair, and the effects of differentiation on the intrinsic counter resolution.

  14. Microprocessor-based single particle calibration of scintillation counter

    NASA Technical Reports Server (NTRS)

    Mazumdar, G. K. D.; Pathak, K. M.

    1985-01-01

    A microprocessor-base set-up is fabricated and tested for the single particle calibration of the plastic scintillator. The single particle response of the scintillator is digitized by an A/D converter, and a 8085 A based microprocessor stores the pulse heights. The digitized information is printed. Facilities for CRT display and cassette storing and recalling are also made available.

  15. Coaxial anode for background suppression in X-ray proportional counters

    NASA Technical Reports Server (NTRS)

    Bunner, A. N.; Kraushaar, W. L.; Mccammon, D.; Vanderhill, M.; Williamson, F.

    1972-01-01

    A scheme which permits the ends (near the anode seals) as well as the bottom and sides of an X-ray astronomy proportional counter to be protected by anticoincidence guard counters is described. A rocket-borne test showed that the non-X-ray background is reduced by an additional factor of about 30 when the end guard counter feature is added.

  16. The Performance and Long Term Stability of the D0 Run II Forward Muon Scintillation Counters

    SciTech Connect

    Bezzubov, V.; Denisov, D.; Evdokimov, V.; Lipaev, V.; Shchukin, A.; Vasilyev, I.

    2014-07-21

    The performance of the D0 experiment forward muon scintillation counters system during Run II of the Tevatron from 2001 to 2011 is described. The system consists of 4214 scintillation counters in six layers. The long term stability of the counters amplitude response determined using LED calibration system and muons produced in proton-antiproton collisions is presented. The average signal amplitude for counters of all layers has gradually decreased over ten years by 11%. The reference timing, determined using LED calibration, was stable within 0.26 ns. Average value of muon timing peak position was used for periodic D0 clock signal adjustments to compensate seasonal drift caused by temperature variations. Counters occupancy for different triggers in physics data collection runs and for minimum bias triggers are presented. The single muon yields versus time and the luminosity dependence of yields were stable for the forward muon system within 1% over 10 years.

  17. Secondary electron background produced by heavy nuclei in a multiwire proportional counter hodoscope

    NASA Technical Reports Server (NTRS)

    Morgan, S. H., Jr.; Watts, J. W., Jr.; Schwille, H.; Pollvogt, U.

    1974-01-01

    The secondary electron background produced by heavy nuclei in a multiwire proportional counter hodoscope is calculated using both a simplified and a more complete Monte Carlo model. These results are compared with experimental data from a small multiwire proportional counter hodoscope operated in a 530 MeV/nucleon accelerator beam of nitrogen nuclei. Estimates of the secondary electron background produced by heavy relativistic nuclei are presented along with the detailed results from calculations of energy deposition in the hodoscope counter cells.

  18. Novel determination of protein, fat, and lactose of milk by liquid scintillation counter

    SciTech Connect

    Noble, R.C.; Shand, J.H.; West, I.G.

    1981-01-01

    A method for routine determination of protein, fat, and lactose contents of milk is based on the ability of a scintillation counter to measure coloration or opalescence through attenuation of photons emitted from sealed miniature carbon-14 and hydrogen-3 radioactive standards. A series of simplified and accurate analytical procedures enable full advantage to be taken of the automatic facilities on the modern liquid scintillation counter. The methods provide several advantages over existing procedures. Accuracy of quantification was high as assessed by comparing the results with those derived by recommended Kjeldahl, Gerber, and colorimetric procedures for protein, fat, and lactose determinations, respectively.

  19. Background characterization of an ultra-low background liquid scintillation counter

    DOE PAGES

    Erchinger, J. L.; Orrell, John L.; Aalseth, C. E.; ...

    2017-01-26

    The Ultra-Low Background Liquid Scintillation Counter developed by Pacific Northwest National Laboratory will expand the application of liquid scintillation counting by enabling lower detection limits and smaller sample volumes. By reducing the overall count rate of the background environment approximately 2 orders of magnitude below that of commercially available systems, backgrounds on the order of tens of counts per day over an energy range of ~3–3600 keV can be realized. Finally, initial test results of the ULB LSC show promising results for ultra-low background detection with liquid scintillation counting.

  20. 30-ps time resolution with segmented scintillation counter for MEG II

    NASA Astrophysics Data System (ADS)

    Uchiyama, Y.; Boca, G.; Cattaneo, P. W.; De Gerone, M.; Gatti, F.; Nakao, M.; Nishimura, M.; Ootani, W.; Pizzigoni, G.; Rossella, M.; Simonetta, M.; Yoshida, K.

    2017-02-01

    A new timing detector has been developed to measure ∼50 MeV/c positrons with a time resolution of σt ≃ 30 ps in the MEG II experiment. The detector are segmented into 512 scintillation counters, each of which consists of 120 ×(40 or 50) × 5mm3 size BC-422 and two arrays of six AdvanSiD silicon photomultipliers. The single-counter resolutions are measured to be 70-80 ps. The counter layout is optimized to get the maximum number of hit counters (on average 9 for signal positrons). This multiple-counters measurement leads to a significant improvement in the time resolution down to 30 ps. Using the first one-fourth (128) counters, a pilot run was carried out using the MEG II beam of 7 ×107μ+ / s and the basic functionality was tested.

  1. A gas scintillation proportional detector to search for 17 keV neutrinos

    SciTech Connect

    Okx, W.J.C.; Bom, V.R.; Eijk, C.W.E. van; Hollander, R.W. )

    1993-08-01

    Evidence for the existence of a 17 keV neutrino was first reported in 1985. Since then many experiments have been performed with contradicting results. In this paper the authors describe an experiment with a new approach to the problem by the introduction of a Gas Scintillation Proportional Detector.

  2. SCINTILLATOR COMPOSITION FOR COUNTERS AND METHOD OF MAKING

    DOEpatents

    Buck, W.L.; Swank, R.K.

    1958-02-25

    This patent deals with a new composition for plastic scintillators and the method of making them. This is accomplished by mixing a solvent, selected from the group consisting of styrene, methylstyrene where the methyl group is attached to the ring, and p-vinylbiphenyl with p-terphenyl as a primary fluor. Marked improvement in the fluorescent properties of this scintillator composition is obtained by incorporating as a second fluor, a small amount of a highly conjugated hydrocarbon having four phenyl groups such as quaterphenyl or 1,1,4,4- tetraphenyl-1,3-butadiene. It is advisable to use very pure monomers in this composition, and to carry out its preparation in the absence of air.

  3. A liquid scintillator neutron multiplicity counter for assaying special nuclear material

    NASA Astrophysics Data System (ADS)

    Sheets, Steven; Glenn, A. M.; Kerr, P. L.; Kim, K. S.; Nakae, L. F.; Newby, R. J.; Prasad, M. K.; Snyderman, N. J.; Verbeke, J. M.; Wurtz, R. E.

    2010-11-01

    The use of 3-He detectors to infer the mass of a fissioning source from the statistical properties of the neutron multiplicity distribution is a mature technology. We describe a new neutron multiplicity counter using the fast timing of liquid scintillators for the non-destructive assay of special nuclear materials (SNM). A liquid scintillator multiplicity counter (LSMC) that detects fast fission neutrons makes possible a coincidence gate on the order of nanoseconds (vs. tens of microseconds for thermal counters). This allows a LSMC to assay SNM in high rate environments where the fission chains would overlap for a thermal counter. This includes items such as impure Pu with high (α,n) rates as well as low mass HEU where an active interrogation source is needed. Furthermore, the time-of-flight of correlated n-γ pairs allows the LSMC to act as an imager of SNM. We report on the development of a liquid scintillator multiplicity counter at Lawrence Livermore National Laboratory. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  4. Shielding concepts for low-background proportional counter arrays in surface laboratories

    SciTech Connect

    Aalseth, Craig E.; Humble, Paul H.; Mace, Emily K.; Orrell, John L.; Seifert, Allen; Williams, Richard M.

    2016-02-01

    Development of ultra low background gas proportional counters has made the contribution from naturally occurring radioactive isotopes – primarily and activity in the uranium and thorium decay chains – inconsequential to instrumental sensitivity levels when measurements are performed in above ground surface laboratories. Simple lead shielding is enough to mitigate against gamma rays as gas proportional counters are already relatively insensitive to naturally occurring gamma radiation. The dominant background in these surface laboratory measurements using ultra low background gas proportional counters is due to cosmic ray generated muons, neutrons, and protons. Studies of measurements with ultra low background gas proportional counters in surface and underground laboratories as well as radiation transport Monte Carlo simulations suggest a preferred conceptual design to achieve the highest possible sensitivity from an array of low background gas proportional counters when operated in a surface laboratory. The basis for a low background gas proportional counter array and the preferred shielding configuration is reported, especially in relation to measurements of radioactive gases having low energy decays such as 37Ar.

  5. Shielding concepts for low-background proportional counter arrays in surface laboratories.

    PubMed

    Aalseth, C E; Humble, P H; Mace, E K; Orrell, J L; Seifert, A; Williams, R M

    2016-02-01

    Development of ultra low background gas proportional counters has made the contribution from naturally occurring radioactive isotopes - primarily α and β activity in the uranium and thorium decay chains - inconsequential to instrumental sensitivity levels when measurements are performed in above ground surface laboratories. Simple lead shielding is enough to mitigate against gamma rays as gas proportional counters are already relatively insensitive to naturally occurring gamma radiation. The dominant background in these surface laboratory measurements using ultra low background gas proportional counters is due to cosmic ray generated muons, neutrons, and protons. Studies of measurements with ultra low background gas proportional counters in surface and underground laboratories as well as radiation transport Monte Carlo simulations suggest a preferred conceptual design to achieve the highest possible sensitivity from an array of low background gas proportional counters when operated in a surface laboratory. The basis for a low background gas proportional counter array and the preferred shielding configuration is reported, especially in relation to measurements of radioactive gases having low energy decays such as (37)Ar.

  6. Neutron spectroscopy with the Spherical Proportional Counter based on nitrogen gas

    NASA Astrophysics Data System (ADS)

    Bougamont, E.; Dastgheibi, A.; Derre, J.; Galan, J.; Gerbier, G.; Giomataris, I.; Gros, M.; Katsioulas, I.; Jourde, D.; Magnier, P.; Navick, X. F.; Papaevangelou, T.; Savvidis, I.; Tsiledakis, G.

    2017-03-01

    A novel large volume spherical proportional counter, recently developed, is used for neutron measurements. The pure N2 gas is studied for thermal and fast neutron detection, providing a new way for neutron spectroscopy. The neutrons are detected via the 14N (n , p)C14 and 14N (n , α)B11 reactions. The detector is tested for thermal and fast neutrons detection with 252Cf and 241Am -9Be neutron sources. The atmospheric neutrons are successfully measured from thermal up to several MeV, well separated from the cosmic ray background. A comparison of the spherical proportional counter with the current available neutron counters is also presented.

  7. Characteristics of a high pressure gas proportional counter filled with xenon

    NASA Technical Reports Server (NTRS)

    Sakurai, H.; Ramsey, B. D.

    1991-01-01

    The characteristics of a conventional cylindrical geometry proportional counter filled with high pressure xenon gas up to 10 atm. were fundamentally investigated for use as a detector in hard X-ray astronomy. With a 2 percent methane gas mixture the energy resolutions at 10 atm. were 9.8 percent and 7.3 percent for 22 keV and 60 keV X-rays, respectively. From calculations of the Townsend ionization coefficient, it is shown that proportional counters at high pressure operate at weaker reduced electric field than low pressure counters. The characteristics of a parallel grid proportional counter at low pressure showed similar pressure dependence. It is suggested that this is the fundamental reason for the degradation of resolution observed with increasing pressure.

  8. New cathode design boron lined proportional counters for neutron area monitoring application

    NASA Astrophysics Data System (ADS)

    Dighe, Priyamvada M.

    2007-06-01

    A new cathode design boron lined proportional counter of 26 mm ID×100 mm sensitive length SS304 cathode has been developed with boron-coated baffles separated by 3 mm spacers inserted in the sensitive volume perpendicular to the axis. The baffles and the spacers were coated with indigenously available 27.7% enriched 10B. The introduction of baffles enhanced the boron coated surface area by a factor of 2.8. Tests in 120 nv thermal neutron flux show that the counter has 0.84 cps/nv thermal neutron sensitivity, which shows enhancement in the sensitivity by a factor of 2.78 due to baffle structure. For comparison standard cylindrical cathode geometry counter coated with 92% enriched 10B on its inner wall with a coating thickness of 0.8 mg/cm2 is developed with same outer dimensions for neutron area monitoring applications. The counter has 1 cps/nv thermal neutron sensitivity. Comparative tests carried out on counters with and without baffle structure show that the baffles enhance the neutron sensitivity and in 2 kR/h gamma background the effect of gamma pile up is similar on both the counters. The variation in cathode internal diameter due to baffle structure gives higher voltage plateau slope (2.8%/10 V) as compared to conventional cylindrical geometry counter (1.2%/10 V). The usability of boron lined counters for neutron area monitoring applications for the cylindrical geometry counter has been studied.

  9. Development of a low background liquid scintillation counter for a shallow underground laboratory

    SciTech Connect

    Erchinger, Jennifer L.; Aalseth, Craig E.; Bernacki, Bruce E.; Douglas, Matthew; Fuller, Erin S.; Keillor, Martin E.; Morley, Shannon M.; Mullen, Crystal A.; Orrell, John L.; Panisko, Mark E.; Warren, Glen A.; Williams, Russell O.; Wright, Michael E.

    2015-08-20

    Pacific Northwest National Laboratory has recently opened a shallow underground laboratory intended for measurement of lowconcentration levels of radioactive isotopes in samples collected from the environment. The development of a low-background liquid scintillation counter is currently underway to further augment the measurement capabilities within this underground laboratory. Liquid scintillation counting is especially useful for measuring charged particle (e.g., B, a) emitting isotopes with no (orvery weak) gamma-ray yields. The combination of high-efficiency detection of charged particle emission in a liquid scintillation cocktail coupled with the low-background environment of an appropriately-designed shield located in a clean underground laboratory provides the opportunity for increased-sensitivity measurements of a range of isotopes. To take advantage of the 35-meter water-equivalent overburden of the underground laboratory, a series of simulations have evaluated the instrumental shield design requirements to assess the possible background rate achievable. This report presents the design and background evaluation for a shallow underground, low background liquid scintillation counter design for sample measurements.

  10. Calibration methodology for proportional counters applied to yield measurements of a neutron burst.

    PubMed

    Tarifeño-Saldivia, Ariel; Mayer, Roberto E; Pavez, Cristian; Soto, Leopoldo

    2014-01-01

    This paper introduces a methodology for the yield measurement of a neutron burst using neutron proportional counters. This methodology is to be applied when single neutron events cannot be resolved in time by nuclear standard electronics, or when a continuous current cannot be measured at the output of the counter. The methodology is based on the calibration of the counter in pulse mode, and the use of a statistical model to estimate the number of detected events from the accumulated charge resulting from the detection of the burst of neutrons. The model is developed and presented in full detail. For the measurement of fast neutron yields generated from plasma focus experiments using a moderated proportional counter, the implementation of the methodology is herein discussed. An experimental verification of the accuracy of the methodology is presented. An improvement of more than one order of magnitude in the accuracy of the detection system is obtained by using this methodology with respect to previous calibration methods.

  11. Effect of air on energy and rise-time spectra measured by proportional gas counter

    SciTech Connect

    Kawano, T.; Tanaka, M.; Isozumi, S.; Isozumi, Y.; Tosaki, M.; Sugiyama, T.

    2015-03-15

    Air exerts a negative effect on radiation detection using a gas counter because oxygen contained in air has a high electron attachment coefficient and can trap electrons from electron-ion pairs created by ionization from incident radiation in counting gas. This reduces radiation counts. The present study examined the influence of air on energy and rise-time spectra measurements using a proportional gas counter. In addition, a decompression procedure method was proposed to reduce the influence of air and its effectiveness was investigated. For the decompression procedure, the counting gas inside the gas counter was decompressed below atmospheric pressure before radiation detection. For the spectrum measurement, methane as well as various methane and air mixtures were used as the counting gas to determine the effect of air on energy and rise-time spectra. Results showed that the decompression procedure was effective for reducing or eliminating the influence of air on spectra measurement using a proportional gas counter. (authors)

  12. On reachable energy resolution of SiPM based scintillation counters for X-ray detection

    NASA Astrophysics Data System (ADS)

    Kuper, K. E.; Oleynikov, V. P.; Porosev, V. V.; Savinov, G. A.; Drozdowski, W.

    2017-01-01

    Presently, silicon photomultipliers (SiPMs) are very attractive devices to replace photomultipliers for light detection in many different fields. For example, they could be used in detectors of photons with energies of 20-150 keV for medical and nondestructive testing applications. The small size and high electron gain of SiPMs make them very attractive candidates for pixelated X-ray detectors operating in a photon counting mode. In this research we evaluated the detector performance that can be reached with up-to-date Lu-based scintillators. Application of LYSO:Ce and LFS-3 scintillators provides high count rate capability because of a short scintillator decay time of ~ 40 ns but enables reaching just a moderate energy resolution. Meanwhile, with a LuYAG:Pr scintillator of quite low non-proportionality one can attain much better energy resolution at a reduced rate.

  13. Novel concept for neutron detection: proportional counter filled with 10B nanoparticle aerosol

    NASA Astrophysics Data System (ADS)

    Amaro, F. D.; Monteiro, C. M. B.; Dos Santos, J. M. F.; Antognini, A.

    2017-02-01

    The high neutron detection efficiency, good gamma-ray discrimination and non-toxicity of 3He made of proportional counters filled with this gas the obvious choice for neutron detection, particularly in radiation portal monitors (RPM), used to control the illicit transport of nuclear material, of which neutron detectors are key components. 3He is very rare and during the last decade this gas has become increasingly difficult to acquire. With the exception of BF3, which is toxic, no other gas can be used for neutron detection in proportional counters. We present an alternative where the 3He atoms are replaced by nanoparticles made of another neutron sensitive material, 10B. The particles are dispersed in a gaseous volume, forming an aerosol with neutron sensitive properties. A proportional counter filled with such aerosol was exposed to a thermal neutron beam and the recorded response indicates that the neutrons have interacted with the particles in the aerosol. This original technique, which transforms a standard proportional gas mixture into a neutron sensitive aerosol, is a breakthrough in the field of radiation detection and has the potential to become an alternative to the use of 3He in proportional counters.

  14. Novel concept for neutron detection: proportional counter filled with (10)B nanoparticle aerosol.

    PubMed

    Amaro, F D; Monteiro, C M B; Dos Santos, J M F; Antognini, A

    2017-02-09

    The high neutron detection efficiency, good gamma-ray discrimination and non-toxicity of (3)He made of proportional counters filled with this gas the obvious choice for neutron detection, particularly in radiation portal monitors (RPM), used to control the illicit transport of nuclear material, of which neutron detectors are key components. (3)He is very rare and during the last decade this gas has become increasingly difficult to acquire. With the exception of BF3, which is toxic, no other gas can be used for neutron detection in proportional counters. We present an alternative where the (3)He atoms are replaced by nanoparticles made of another neutron sensitive material, (10)B. The particles are dispersed in a gaseous volume, forming an aerosol with neutron sensitive properties. A proportional counter filled with such aerosol was exposed to a thermal neutron beam and the recorded response indicates that the neutrons have interacted with the particles in the aerosol. This original technique, which transforms a standard proportional gas mixture into a neutron sensitive aerosol, is a breakthrough in the field of radiation detection and has the potential to become an alternative to the use of (3)He in proportional counters.

  15. Novel concept for neutron detection: proportional counter filled with 10B nanoparticle aerosol

    PubMed Central

    Amaro, F. D.; Monteiro, C. M. B.; dos Santos, J. M. F.; Antognini, A.

    2017-01-01

    The high neutron detection efficiency, good gamma-ray discrimination and non-toxicity of 3He made of proportional counters filled with this gas the obvious choice for neutron detection, particularly in radiation portal monitors (RPM), used to control the illicit transport of nuclear material, of which neutron detectors are key components. 3He is very rare and during the last decade this gas has become increasingly difficult to acquire. With the exception of BF3, which is toxic, no other gas can be used for neutron detection in proportional counters. We present an alternative where the 3He atoms are replaced by nanoparticles made of another neutron sensitive material, 10B. The particles are dispersed in a gaseous volume, forming an aerosol with neutron sensitive properties. A proportional counter filled with such aerosol was exposed to a thermal neutron beam and the recorded response indicates that the neutrons have interacted with the particles in the aerosol. This original technique, which transforms a standard proportional gas mixture into a neutron sensitive aerosol, is a breakthrough in the field of radiation detection and has the potential to become an alternative to the use of 3He in proportional counters. PMID:28181520

  16. Initial evaluation of proportional scintillation in liquid Xenon for direct dark matter detection

    NASA Astrophysics Data System (ADS)

    Ye, T.; Giboni, K. L.; Ji, X.

    2014-12-01

    The Liquid Xenon Time Projection Chamber (LXeTPC) is often seen as an ideal detector for the direct Dark Matter (DM) search. In such experiments an efficient γ-ray background discrimination is essential. This can be achieved by distinguishing the ionization density, different for γ-rays and Nuclear Recoils. Two quantities are used for this measurement, the direct scintillation light generated by the ionizing event, and the free charges swept away by an electric field before recombination occurs. Present LXe detectors apply the Dual Phase principle, i.e. the charges are extracted into the gas phase and are measured by the proportional light they produce in a strong electric field in the gas. With ever growing dimensions of the detectors it is difficult to meet the tight mechanical tolerances required. Proportional scintillation also occurs in the liquid phase, although at much higher field strengths. Such field strengths can be reached in the 1/r field close to thin wires. All the limitations due to the extraction of electrons into the gas phase are avoided. Since the liquid level has not to be crossed, the design of the detector becomes simpler with many advantages over Dual Phase detectors. Our initial tests clearly show the pulses. They are much shorter, and their length is limited by longitudinal diffusion of the drifting charges. The threshold for proportional light production seems significantly lower, and estimates of the gain are more favorable than previously predicted. We attribute these discrepancies to our improved liquid purity.

  17. TACI: a code for interactive analysis of neutron data produced by a tissue equivalent proportional counter

    SciTech Connect

    Cummings, F.M.

    1984-06-01

    The TEPC analysis code (TACI) is a computer program designed to analyze pulse height data generated by a tissue equivalent proportional counter (TEPC). It is written in HP BASIC and is for use on an HP-87XM personal computer. The theory of TEPC analysis upon which this code is based is summarized.

  18. The calculation of proportional counter energy-deposition spectra from experimental data.

    NASA Technical Reports Server (NTRS)

    Steigerwalt, J. E.; Baily, N. A.

    1973-01-01

    The experimental approach considered requires the measurement of energy-absorption distributions for a set of pathlengths which define a biological volume. A suitable folding procedure is necessary to produce composite energy-absorption distributions. The investigation is concerned with the quality of the prediction of energy-deposition distributions, taking into account distributions measured with a proportional counter.

  19. New method of proportional counter feedback biasing for wide-range radiation dose-rate monitors

    SciTech Connect

    Kopp, M.K.; Valentine, K.H.; Guerrant, G.C.; Manning, F.W.

    1984-01-01

    A prototypic wide-range radiation dose-rate monitor for civil defense applications has been developed and tested. The specified dose-rate range (0 to 500 R/h) was displayed on a single readout scale by using feedback-controlled biasing of a proportional counter. This new method is based on controlling the avalanche multiplication factor (gas gain) of the counter by varying its bias voltage in response to its measured output current (i.e., detected dose rate). The counter output current varies between 0 and 1.5 nA in a quasi-logarithmic response to dose rates between 0 and 500 R/h. The corresponding values of gas gain and bias voltage range from 1 to 300 and 200 to 1900 V respectively.

  20. Multiwire proportional counters for use in area X-ray diffractometers

    SciTech Connect

    Hamlin, R.

    1982-01-01

    The multiwire proportional counter is at the time of this writing the only type of two dimensional position sensitive X-ray detector capable of collecting diffraction data accurate enough for solution of new protein structures. The first diffractometer system to use this type of detector (the Mark I diffractometer system) was assembled at the University of California, San Diego and has collected the data used to solve four new protein structures. Similar diffractometer systems using a single thin, flat multiwire counter are now being constructed in many other laboratories around the world, and several of these will routinely be collecting good diffraction data from protein and perhaps even virus crystals within two years. A table describing these other systems is included here. The next step in the evolution of area diffractometer systems based on the multiwire proportional counter is more complete coverage of the solid angle of the diffraction pattern: more complete than the 10% to 40% coverage possible with one flat multiwire counter. The phenomenon called ''parallax'' makes it impractical to intercept the whole diffraction pattern with one flat xenon-filled multiwire counter. Two strategies for dealing with parallax are now being pursued. One strategy involves adding a spherical drift region to the front of a flat multiwire counter and adetector using this idea will be described. The other strategy, the one being pursued by the author, involves building an array of flat detectors arranged to approximate a section of the surface of a sphere. The array of flat detectors gives more flexibility in crystal-to-detector distance and distributes the dead time over many detectors, allowing the full array to have a high counting rate capacity even using only medium speed (2 microsecond) position readout circuits for each individual detector.

  1. Position-sensitive proportional counter with low-resistance metal-wire anode

    DOEpatents

    Kopp, Manfred K.

    1980-01-01

    A position-sensitive proportional counter circuit is provided which allows the use of a conventional (low-resistance, metal-wire anode) proportional counter for spatial resolution of an ionizing event along the anode of the counter. A pair of specially designed active-capacitance preamplifiers are used to terminate the anode ends wherein the anode is treated as an RC line. The preamplifiers act as stabilized active capacitance loads and each is composed of a series-feedback, low-noise amplifier, a unity-gain, shunt-feedback amplifier whose output is connected through a feedback capacitor to the series-feedback amplifier input. The stabilized capacitance loading of the anode allows distributed RC-line position encoding and subsequent time difference decoding by sensing the difference in rise times of pulses at the anode ends where the difference is primarily in response to the distributed capacitance along the anode. This allows the use of lower resistance wire anodes for spatial radiation detection which simplifies the counter construction and handling of the anodes, and stabilizes the anode resistivity at high count rates (>10.sup.6 counts/sec).

  2. The response of tissue-equivalent proportional counters to heavy ions

    NASA Technical Reports Server (NTRS)

    Nikjoo, Hooshang; Khvostunov, Igor K.; Cucinotta, Francis A.

    2002-01-01

    The paper presents a theoretical model for the response of a tissue-equivalent proportional counter (TEPC) irradiated with charged particles. Heavy ions and iron ions in particular constitute a significant part of radiation in space. TEPCs are used for all space shuttle and International Space Station (ISS) missions to estimate the dose and radiation quality (in terms of lineal energy) inside spacecraft. The response of the tissue-equivalent proportional counters shows distortions at the wall/cavity interface. In this paper, we present microdosimetric investigation using Monte Carlo track structure calculations to simulate the response of a TEPC to charged particles of various LET (1 MeV protons, 2.4 MeV alpha particles, 46 MeV/nucleon 20Ne, 55 MeV/nucleon 20Ne, 45 MeV/nucleon 40Ar, and 1.05 GeV/nucleon 56Fe). Data are presented for energy lost and energy absorbed in the counter cavity and wall. The model calculations are in good agreement with the results of Rademacher et al. (Radiat. Res. 149, 387-389, 1998), including the study of the interface between the wall and the sensitive region of the counter. It is shown that the anomalous response observed at large event sizes in the experiment is due to an enhanced entry of secondary electrons from the wall into the gas cavity.

  3. Use of the small gas proportional counters for the carbon-14 measurement of very small samples

    SciTech Connect

    Sayre, E.V.; Harbottle, G.; Stoenner, R.W.; Otlet, R.L.; Evans, G.V.

    1981-01-01

    Two recent developments are: the first is the mass-spectrometric separation of /sup 14/C and /sup 12/C ions, followed by counting of the /sup 14/C, while the second is the extension of conventional proportional counter operation, using CO/sub 2/ as counting gas, to very small counters and samples. Although the second method is slow (months of counting time are required for 10 mg of carbon) it does not require operator intervention and many samples may be counted simultaneously. Also, it costs only a fraction of the capital expense of an accelerator installation. The development, construction and operation of suitable small counters are described, and results of three actual dating studies involving milligram scale carbon samples will be given. None of these could have been carried out if conventional, gram-sized samples had been needed. New installations, based on the use of these counters, are under construction or in the planning stages. These are located at Brookhaven Laboratory, the National Bureau of Standards (USA) and Harwell (UK). The Harwell installation, which is in advanced stages of construction, will be described in outline. The main significance of the small-counter method is, that although it will not suffice to measure the smallest (much less than 10 mg) or oldest samples, it will permit existing radiocarbon laboratories to extend their capability considerably, in the direction of smaller samples, at modest expense.

  4. A boron-lined proportional counter (BLPC) used in a mixed field of reactors

    NASA Astrophysics Data System (ADS)

    Chen, Guo-Yun; Wei, Zhi-Yong; Xin, Yong; Lei, Sheng-Jie; Huang, Fu-Cheng; Huang, San-Bo; Zhu, Li; Zhao, Jing-Wu; Ma, Jia-Yi

    2012-05-01

    A boron-lined proportional counter (BLPC) with a count rate limit close to the multi-wire proportional counter was manufactured to measure the mixed field around reactors. After measurement with a standard Am-Be neutron source (activity: 100 mCi), the results show that the operating voltage of the BLPC is 800 V, the plateau length is 100 V and the slope is 13.2%/100 V. The width and rise time of the output pulse of the BLPC are 1.26 μs and 370 ns, respectively. When the BLPC works at a count rate of 1.0×105 count/s, the pulse pile-up probability of the BLPC is 3.6%. A clear peak can be seen in the pulse height spectrum of the BLPC. and the performances illustrate that a BLPC working in pulse mode can serve as a source range detector of reactors.

  5. 39Ar/Ar measurements using ultra-low background proportional counters

    SciTech Connect

    Hall, Jeter C.; Aalseth, Craig E.; Bonicalzi, Ricco; Brandenberger, Jill M.; Day, Anthony R.; Humble, Paul H.; Mace, Emily K.; Panisko, Mark E.; Seifert, Allen

    2016-01-08

    Age dating groundwater and seawater using 39Ar/Ar ratios is an important tool to understand water mass flow rates and mean residence time. For modern or contemporary argon, the 39Ar activity is 1.8 mBq per liter of argon. Radiation measurements at these activity levels require ultra low-background detectors. Low-background proportional counters have been developed at Pacific Northwest National Laboratory. These detectors use traditional mixtures of argon and methane as counting gas, and the residual 39Ar from commercial argon has become a predominant source of background activity in these detectors. We demonstrated sensitivity to 39Ar by using geological or ancient argon from gas wells in place of commercial argon. The low level counting performance of these proportional counters is then demonstrated for sensitivities to 39Ar/Ar ratios sufficient to date water masses as old as 1000 years.

  6. Design of a Low Background Liquid Scintillation Counter for a Shallow Underground Laboratory

    NASA Astrophysics Data System (ADS)

    Orrell, John; Aalseth, Craig; Bernacki, Bruce; Douglas, Matt; Erchinger, Jennifer; Fuller, Erin; Keillor, Martin; Morley, Shannon; Mullen, Crystal; Panisko, Mark; Shaff, Sarah; Warren, Glen; Wright, Michael

    2014-09-01

    Pacific Northwest National Laboratory operates a 35-meter water-equivalent overburden, shallow underground laboratory for measuring low-concentration radioactive isotopes in environmental samples collected. A low-background liquid scintillation counter is under development. Liquid scintillation counting is useful for beta-emitting isotopes without (or low) gamma ray yields. The high-efficiency beta detection in a liquid scintillation cocktail coupled with the low-background environment of a shield located in a clean underground laboratory provides for increased-sensitivity measurements to a range of isotopes. Benchmarked simulations have evaluated the shield design requirements to assess the background rate achievable. Assay of shield construction materials provides the basis for the shield design development. The low background design is informed by efforts in experimental design of neutrinoless double beta decay experiments, direct detection dark matter experiments, and low energy neutrino detection experiments. In this vein a background budget for the instrument is presented with attention to low background methods directed toward applications of nuclear measurements.

  7. Development of an Ultra-Low Background Liquid Scintillation Counter for Trace Level Analysis

    SciTech Connect

    Erchinger, Jennifer L.; Orrell, John L.; Aalseth, Craig E.; Bernacki, Bruce E.; Douglas, Matthew; Finn, Erin C.; Fuller, Erin S.; Keillor, Martin E.; Morley, Shannon M.; Mullen, Crystal A.; Panisko, Mark E.; Shaff, Sarah M.; Warren, Glen A.; Wright, Michael E.

    2015-09-01

    Low-level liquid scintillation counting (LSC) has been established as one of the radiation detection techniques useful in elucidating environmental processes and environmental monitoring around nuclear facilities. The Ultra-Low Background Liquid Scintillation Counter (ULB-LSC) under construction in the Shallow Underground Laboratory at Pacific Northwest National Laboratory aims to further reduce the MDAs and/or required sample processing. Through layers of passive shielding in conjunction with an active veto and 30 meters water equivalent overburden, the background reduction is expected to be 10 to 100 times below typical analytic low-background liquid scintillation systems. Simulations have shown an expected background of around 14 counts per day. A novel approach to the light collection will use a coated hollow light guide cut into the inner copper shielding. Demonstration LSC measurements will show low-energy detection, spectral deconvolution, and alpha/beta discrimination capabilities, from trials with standards of tritium, strontium-90, and actinium-227, respectively. An overview of the system design and expected demonstration measurements will emphasize the potential applications of the ULB-LSC in environmental monitoring for treaty verification, reach-back sample analysis, and facility inspections.

  8. Demand-type gas supply system for rocket borne thin-window proportional counters

    NASA Technical Reports Server (NTRS)

    Acton, L. W.; Caravalho, R.; Catura, R. C.; Joki, E. G.

    1977-01-01

    A simple closed loop control system has been developed to maintain the gas pressure in thin-window proportional counters during rocket flights. This system permits convenient external control of detector pressure and system flushing rate. The control system is activated at launch with the sealing of a reference volume at the existing system pressure. Inflight control to plus or minus 2 torr at a working pressure of 760 torr has been achieved on six rocket flights.

  9. Sensitivity to x-ray polarization of a microgap gas proportional counter

    NASA Astrophysics Data System (ADS)

    Soffitta, Paolo; Costa, Enrico; Morelli, Ennio; Bellazzini, Ronaldo; Brez, Alessandro; Raffo, R.

    1995-10-01

    We measured the average anisotropy of the primary charge cloud produced by photoelectron when an x-ray beam linearly polarized is absorbed on a Ne-DME gas mixture by using a micro-gap proportional counter. This average anisotropy is not present when an Fe55 unpolarized x-ray source is used. We discuss the results of our measurement in terms of performances of this detector as an x-ray polarimeter.

  10. An array of low-background 3He proportional counters for the Sudbury Neutrino Observatory

    NASA Astrophysics Data System (ADS)

    Amsbaugh, J. F.; Anaya, J. M.; Banar, J.; Bowles, T. J.; Browne, M. C.; Bullard, T. V.; Burritt, T. H.; Cox-Mobrand, G. A.; Dai, X.; Deng, H.; Di Marco, M.; Doe, P. J.; Dragowsky, M. R.; Duba, C. A.; Duncan, F. A.; Earle, E. D.; Elliott, S. R.; Esch, E.-I.; Fergani, H.; Formaggio, J. A.; Fowler, M. M.; Franklin, J. E.; Geissbühler, P.; Germani, J. V.; Goldschmidt, A.; Guillian, E.; Hallin, A. L.; Harper, G.; Harvey, P. J.; Hazama, R.; Heeger, K. M.; Heise, J.; Hime, A.; Howe, M. A.; Huang, M.; Kormos, L. L.; Kraus, C.; Krauss, C. B.; Law, J.; Lawson, I. T.; Lesko, K. T.; Loach, J. C.; Majerus, S.; Manor, J.; McGee, S.; Miknaitis, K. K. S.; Miller, G. G.; Morissette, B.; Myers, A.; Oblath, N. S.; O'Keeffe, H. M.; Ollerhead, R. W.; Peeters, S. J. M.; Poon, A. W. P.; Prior, G.; Reitzner, S. D.; Rielage, K.; Robertson, R. G. H.; Skensved, P.; Smith, A. R.; Smith, M. W. E.; Steiger, T. D.; Stonehill, L. C.; Thornewell, P. M.; Tolich, N.; VanDevender, B. A.; Van Wechel, T. D.; Wall, B. L.; Wan Chan Tseung, H.; Wendland, J.; West, N.; Wilhelmy, J. B.; Wilkerson, J. F.; Wouters, J. M.

    2007-09-01

    An array of Neutral-Current Detectors (NCDs) has been built in order to make a unique measurement of the total active flux of solar neutrinos in the Sudbury Neutrino Observatory (SNO). Data in the third phase of the SNO experiment were collected between November 2004 and 2006, after the NCD array was added to improve the neutral-current sensitivity of the SNO detector. This array consisted of 36 strings of proportional counters filled with a mixture of 3He and CF 4 gas capable of detecting the neutrons liberated by the neutrino-deuteron neutral-current reaction in the D 2O, and four strings filled with a mixture of 4He and CF 4 gas for background measurements. The proportional counter diameter is 5 cm. The total deployed array length was 398 m. The SNO NCD array is the lowest-radioactivity large array of proportional counters ever produced. This article describes the design, construction, deployment, and characterization of the NCD array, discusses the electronics and data acquisition system, and considers event signatures and backgrounds.

  11. Digital dual-parameter data acquisition for SP2 hydrogen-filled proportional counters.

    PubMed

    Hawkes, N P; Roberts, N J

    2014-10-01

    Hydrogen-filled proportional counters perform well as neutron spectrometers in the energy region from a few tens of keV up to ∼1.5 MeV. Unfortunately, gamma rays also generate signals in these detectors. It is possible in principle to distinguish the two types of event via the rise time of their respective signal pulses, but the data acquisition system needed for this is complex to assemble and adjust if one uses conventional modular analogue electronics. In this work a digital sampling system, in conjunction with custom software, was used to measure and acquire amplitude and rise time data from type SP2 counters. The interpretation of the data was supported by a Monte Carlo calculation. The performance of the system is compared with that of a conventional 1-parameter analogue system, and the potential of the digital technique to supplant conventional methods is discussed.

  12. High-resolution position-sensitive proportional counter camera for radiochromatographic imaging

    SciTech Connect

    Schuresko, D.D.; Kopp, M.K.; Harter, J.A.; Bostick, W.D.

    1988-12-01

    A high-resolution proportional counter camera for imaging two- dimensional (2-D) distributions of radionuclides is described. The camera can accommodate wet or dry samples that are separated from the counter gas volume by a 6-..mu..m Mylar membrane. Using 95% Xe-5% CO/sub 2/ gas at 3-MPa pressure and electronic collimation based upon pulse energy discrimination, the camera's performance characteristics for /sup 14/C distributions are as follows: active area--10 by 10 cm, position resolution--0.5 mm, total background--300 disintegrations per minute, and count-rate capability--10/sup 5/ disintegrations per second. With computerized data acquisition, the camera is a significant improvement in analytical instrumentation for imaging 2-D radionuclide distributions over present-day commercially available technology. (Note: This manuscript was completed in July 1983). 13 refs., 10 figs.

  13. Lineal energy calibration of mini tissue-equivalent gas-proportional counters (TEPC)

    NASA Astrophysics Data System (ADS)

    Conte, V.; Moro, D.; Grosswendt, B.; Colautti, P.

    2013-07-01

    Mini TEPCs are cylindrical gas proportional counters of 1 mm or less of sensitive volume diameter. The lineal energy calibration of these tiny counters can be performed with an external gamma-ray source. However, to do that, first a method to get a simple and precise spectral mark has to be found and then the keV/μm value of this mark. A precise method (less than 1% of uncertainty) to identify this markis described here, and the lineal energy value of this mark has been measured for different simulated site sizes by using a 137Cs gamma source and a cylindrical TEPC equipped with a precision internal 244Cm alpha-particle source, and filled with propane-based tissue-equivalent gas mixture. Mini TEPCs can be calibrated in terms of lineal energy, by exposing them to 137Cesium sources, with an overall uncertainty of about 5%.

  14. Lineal energy calibration of mini tissue-equivalent gas-proportional counters (TEPC)

    SciTech Connect

    Conte, V.; Moro, D.; Colautti, P.; Grosswendt, B.

    2013-07-18

    Mini TEPCs are cylindrical gas proportional counters of 1 mm or less of sensitive volume diameter. The lineal energy calibration of these tiny counters can be performed with an external gamma-ray source. However, to do that, first a method to get a simple and precise spectral mark has to be found and then the keV/{mu}m value of this mark. A precise method (less than 1% of uncertainty) to identify this markis described here, and the lineal energy value of this mark has been measured for different simulated site sizes by using a {sup 137}Cs gamma source and a cylindrical TEPC equipped with a precision internal {sup 244}Cm alpha-particle source, and filled with propane-based tissue-equivalent gas mixture. Mini TEPCs can be calibrated in terms of lineal energy, by exposing them to {sup 137}Cesium sources, with an overall uncertainty of about 5%.

  15. Reference drums used in calibration of a plastic scintillation counter in a 4π counting geometry.

    PubMed

    Yeh, Chin-Hsien; Yuan, Ming-Chen

    2016-03-01

    In this study, two kinds of reference drums were developed. One type was constructed with nine layers of large-area sources filled with different materials having five different densities. The other type of reference drums was constructed with nine rod sources filled with the same materials of different densities. The efficiency calibration of a plastic scintillation counter in 4π counting geometry using these two kinds of drums showed that rod-source drums resulted in higher counting efficiency than layered source drums. The counting rates obtained from rod-source drums were closer to those obtained from a standard drum with water solution than counting rates from drums with layered sources. The results of this study recommend to use reference drums with rod-sources to compensate the drawbacks of standard drums with water solution of not being able to adjust the density of material. The proposed reference drums improve the accuracy of radioactivity analysis for waste drums of different densities.

  16. Scintillation counter and wire chamber front end modules for high energy physics experiments

    SciTech Connect

    Baldin, Boris; DalMonte, Lou; /Fermilab

    2011-01-01

    This document describes two front-end modules developed for the proposed MIPP upgrade (P-960) experiment at Fermilab. The scintillation counter module was developed for the Plastic Ball detector time and charge measurements. The module has eight LEMO 00 input connectors terminated with 50 ohms and accepts negative photomultiplier signals in the range 0.25...1000 pC with the maximum input voltage of 4.0 V. Each input has a passive splitter with integration and differentiation times of {approx}20 ns. The integrated portion of the signal is digitized at 26.55 MHz by Analog Devices AD9229 12-bit pipelined 4-channel ADC. The differentiated signal is discriminated for time measurement and sent to one of the four TMC304 inputs. The 4-channel TMC304 chip allows high precision time measurement of rising and falling edges with {approx}100 ps resolution and has internal digital pipeline. The ADC data is also pipelined which allows deadtime-less operation with trigger decision times of {approx}4 {micro}s. The wire chamber module was developed for MIPP EMCal detector charge measurements. The 32-channel digitizer accepts differential analog signals from four 8-channel integrating wire amplifiers. The connection between wire amplifier and digitizer is provided via 26-wire twist-n-flat cable. The wire amplifier integrates input wire current and has sensitivity of 275 mV/pC and the noise level of {approx}0.013 pC. The digitizer uses the same 12-bit AD9229 ADC chip as the scintillator counter module. The wire amplifier has a built-in test pulser with a mask register to provide testing of the individual channels. Both modules are implemented as a 6Ux220 mm VME size board with 48-pin power connector. A custom europack (VME) 21-slot crate is developed for housing these front-end modules.

  17. Apparatus for positioning an external radioactive standard in a liquid scintillation counter

    SciTech Connect

    Horrocks, D.L.; Kampf, R.S.

    1987-07-07

    This patent describes a liquid scintillation counter having a counting chamber for receiving a sample containing a scintillator substance and a sample of a radioactive substance to be counted. The improved apparatus positions a radioactive source in an operating location to irradiate the sample in the counting chamber comprising, in combination: (1) a continuous bidirectionally flexible conveyor forming a closed loop for conveying the radioactive source through on operating location and a storage location; (2) means supporting the radioactive source at a position along the flexible conveyor for conveyance; (3) guide means for supporting the conveyor and for guiding conveyor movement along a selected path, the path transversing at spaced positions the storage location for the radioactive source remote from the counting chamber and the operating location for the radioactive source near to the counting chamber; and (4) drive means coupled to the continuous flexible conveyor to draw the conveyor around the path for conveying the radioactive source through the spaced storage and operating locations.

  18. Use of tissue equivalent proportional counters to characterize radiation quality on the space shuttle

    SciTech Connect

    Braby, L.A.; Conroy, T.J.; Elegy, D.C.; Brackenbush, L.W.

    1992-04-01

    Tissue equivalent proportional counters (TEPC) are essentially cavity ionization chambers operating at low pressure and with gas gain. A small, battery powered, TEPC spectrometer, which records lineal energy spectra at one minute intervals, has been used on several space shuttle missions. The data it has collected clearly show the South Atlantic anomaly and indicate a mean quality factor somewhat higher than expected. An improved type of instrument has been developed with sufficient memory to record spectra at 10 second intervals, and with increased resolution for low LET events. This type of instrument will be used on most future space shuttle flights and in some international experiments.

  19. Search for magnetic monopoles using proportional counters filled with helium gas

    NASA Technical Reports Server (NTRS)

    Cho, C.; Higashi, S.; Hiraoka, N.; Maruyama, A.; Ozaki, S.; Tsuji, K.

    1985-01-01

    Slow magnetic monopoles in cosmic rays have been searched at sea level with the detector which consists of seven layers of proportional counters filled with a mixture of He + 20% CH4. The velocities and the energy losses of the incident particles are measured. The upper limit of flux for the monopoles in the velocity range of 1 x 0.001 Beta 4 x 0.001 is 2.78 x 10 to the minus 12th power square centimeters sr sec of 90% confidence level.

  20. Simulations of electron avalanches in an ultra-low-background proportional counter

    SciTech Connect

    Robinson, John W.; Aalseth, Craig; Dion, Michael P.; Overman, Cory; Seifert, Allen; VanDevender, Brent

    2016-02-01

    New classes have been added to the simulation package Garfield++ to import the potential and electric field solutions generated by ANSYS R MaxwellTM v.16. Using these tools we report results on the simulation of electron avalanches and induced signal waveforms in comparison to experimental data of the ultra-lowbackground gas proportional counters being developed at Pacific Northwest National Laboratory. Furthermore, an improved mesh search algorithm based on Delaunay triangulation was implemented and provided at least a three order of magnitude time savings when compared to the built-in point-location search class of Garfield++.

  1. ³⁹Ar/Ar measurements using ultra-low background proportional counters.

    PubMed

    Hall, Jeter; Aalseth, Craig E; Bonicalzi, Ricco M; Brandenberger, Jill M; Day, Anthony R; Humble, Paul H; Mace, Emily K; Panisko, Mark E; Seifert, Allen

    2016-01-01

    Age-dating groundwater and seawater using the (39)Ar/Ar ratio is an important tool to understand water mass-flow rates and mean residence time. Low-background proportional counters developed at Pacific Northwest National Laboratory use mixtures of argon and methane as counting gas. We demonstrate sensitivity to (39)Ar by comparing geological (ancient) argon recovered from a carbon dioxide gas well and commercial argon. The demonstrated sensitivity to the (39)Ar/Ar ratio is sufficient to date water masses as old as 1000 years.

  2. Calibration of an ultra-low-background proportional counter for measuring {sup 37}Ar

    SciTech Connect

    Seifert, A.; Aalseth, C. E.; Bonicalzi, R. M.; Bowyer, T. W.; Day, A. R.; Fuller, E. S.; Haas, D. A.; Hayes, J. C.; Hoppe, E. W.; Humble, P. H.; Keillor, M. E.; LaFerriere, B. D.; Mace, E. K.; McIntyre, J. I.; Merriman, J. H.; Miley, H. S.; Myers, A. W.; Orrell, J. L.; Overman, C. T.; Panisko, M. E.; and others

    2013-08-08

    An ultra-low-background proportional counter design has been developed at Pacific Northwest National Laboratory (PNNL) using clean materials, primarily electro-chemically-purified copper. This detector, along with an ultra-low-background counting system (ULBCS), was developed to complement a new shallow underground laboratory (30 meters water-equivalent) at PNNL. The ULBCS design includes passive neutron and gamma shielding, along with an active cosmic-veto system. This system provides a capability for making ultra-sensitive measurements to support applications like age-dating soil hydrocarbons with {sup 14}C/{sup 3}H, age-dating of groundwater with {sup 39}Ar, and soil-gas assay for {sup 37}Ar to support On-Site Inspection (OSI). On-Site Inspection is a key component of the verification regime for the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Measurements of radionuclides created by an underground nuclear explosion are valuable signatures of a Treaty violation. For OSI, the 35-day half-life of {sup 37}Ar, produced from neutron interactions with calcium in soil, provides both high specific activity and sufficient time for inspection before decay limits sensitivity. This work describes the calibration techniques and analysis methods developed to enable quantitative measurements of {sup 37}Ar samples over a broad range of proportional counter operating pressures. These efforts, along with parallel work in progress on gas chemistry separation, are expected to provide a significant new capability for {sup 37}Ar soil gas background studies.

  3. Calibration of an ultra-low-background proportional counter for measuring 37Ar

    NASA Astrophysics Data System (ADS)

    Seifert, A.; Aalseth, C. E.; Bonicalzi, R. M.; Bowyer, T. W.; Day, A. R.; Fuller, E. S.; Haas, D. A.; Hayes, J. C.; Hoppe, E. W.; Humble, P. H.; Keillor, M. E.; LaFerriere, B. D.; Mace, E. K.; McIntyre, J. I.; Merriman, J. H.; Miley, H. S.; Myers, A. W.; Orrell, J. L.; Overman, C. T.; Panisko, M. E.; Williams, R. M.

    2013-08-01

    An ultra-low-background proportional counter design has been developed at Pacific Northwest National Laboratory (PNNL) using clean materials, primarily electro-chemically-purified copper. This detector, along with an ultra-low-background counting system (ULBCS), was developed to complement a new shallow underground laboratory (30 meters water-equivalent) at PNNL. The ULBCS design includes passive neutron and gamma shielding, along with an active cosmic-veto system. This system provides a capability for making ultra-sensitive measurements to support applications like age-dating soil hydrocarbons with 14C/3H, age-dating of groundwater with 39Ar, and soil-gas assay for 37Ar to support On-Site Inspection (OSI). On-Site Inspection is a key component of the verification regime for the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Measurements of radionuclides created by an underground nuclear explosion are valuable signatures of a Treaty violation. For OSI, the 35-day half-life of 37Ar, produced from neutron interactions with calcium in soil, provides both high specific activity and sufficient time for inspection before decay limits sensitivity. This work describes the calibration techniques and analysis methods developed to enable quantitative measurements of 37Ar samples over a broad range of proportional counter operating pressures. These efforts, along with parallel work in progress on gas chemistry separation, are expected to provide a significant new capability for 37Ar soil gas background studies.

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

    SciTech Connect

    Amsbaugh, J.F.; Anaya, J.M.; Banar, J.; Bowles, T.J.; Browne,M.C.; Bullard, T.V.; Burritt, T.H.; Cox-Mobrand, G.A.; Dai, X.; H.Deng,X.; Di Marco, M.; Doe, P.J.; Dragowsky, M.R.; Duba, C.A.; Duncan, F.A.; Earle, E.D.; Elliott, S.R.; Esch, E.-I.; Fergani, H.; Formaggio, J.A.; Fowler, M.M.; Franklin, J.E.; Geissbuehler, P.; Germani, J.V.; Goldschmidt, A.; Guillian, E.; Hallin, A.L.; Harper, G.; Harvey, P.J.; Hazama, R.; Heeger, K.M.; Heise, J.; Hime, A.; Howe, M.A.; Huang, M.; Kormos, L.L.; Kraus, C.; Krauss, C.B.; Law, J.; Lawson, I.T.; Lesko,K.T.; Loach, J.C.; Majerus, S.; Manor, J.; McGee, S.; Miknaitis, K.K.S.; Miller, G.G.; Morissette, B.; Myers, A.; Oblath, N.S.; O'Kee, H.M.; Ollerhead, R.W.; Peeters, S.J.M.; Poon, A.W.P.; Prior, G.; Reitzner,S.D.; Rielage, K.; Robertson, R.G.H.; Skensved, P.; Smith, A.R.; Smith,M.W.E.; Steiger, T.D.; Stonehill,L.C.; Thornewell, P.M.; Tolich, N.; VanDevender, B.A.; VanWechel, T.D.; Wall, B.L.; Tseung, H.W.C.; Wendland,J.; West, N.; Wilhelmy, J.B.; Wilkerson, J.F.; Wouters, J.M.

    2007-02-01

    An array of Neutral-Current Detectors (NCDs) has been builtin order to make a unique measurement of the total active ux of solarneutrinos in the Sudbury Neutrino Observatory (SNO). Data in the thirdphase of the SNO experiment were collected between November 2004 andNovember 2006, after the NCD array was added to improve theneutral-current sensitivity of the SNO detector. This array consisted of36 strings of proportional counters lled with a mixture of 3He and CF4gas capable of detecting the neutrons liberated by the neutrino-deuteronneutral current reaction in the D2O, and four strings lled with a mixtureof 4He and CF4 gas for background measurements. The proportional counterdiameter is 5 cm. The total deployed array length was 398 m. The SNO NCDarray is the lowest-radioactivity large array of proportional countersever produced. This article describes the design, construction,deployment, and characterization of the NCD array, discusses theelectronics and data acquisition system, and considers event signaturesand backgrounds.

  5. Miniature proportional counter for compression measurements of laser-fusion targets

    SciTech Connect

    Lane, S.M.; Dellis, J.H.; Bennett, C.K.; Campbell, E.M.

    1981-10-01

    Direct drive laser fusion targets consisting of DT gas encapsulated in glass microshells produce 14.1 MeV neutrons that can interact with silicon-28 nuclei in the glass to produce a 2.2 minute aluminum-28 activity. From the number of /sup 28/Al nuclei created and the neutron yield, the compressed glass areal density can be found. To determine the number of activated atoms created, we collect approximately one-half of the target debris on a thin metal foil which is transferred to our beta-gamma coincidence detector. This detector consists of a 25 cm x 25 cm NaI(Tl) crystal having a 5 cm x 15 cm well. We have recently built a miniature proportional counter that fits into this well and is used to detect beta particles. It is constructed of .025 cm thick copper and has nine separate chambers through which methane flows. The coincidence background is 0.14 cpm and the measured beta efficiency is 45%. We are now building a .0125 cm thick counter made of aluminum having a predicted efficiency of > 90%.

  6. Use of the small proportional counter for carbon 14 measurement in 10 milligram carbon samples

    SciTech Connect

    Sayre, E.V.; Harbottle, G.; Stoenner, R.W.; Otlet, R.L.

    1981-01-01

    Ten years ago, the measurement of C-14/C-12 ratios in 10 milligram carbon samples seemed to be technically out of reach. However, two developments that make this goal possible have recently occurred: the first is an entirely new mass-spectrometric separation of C-14 and C-12 ions and their subsequent estimation by counting, while the second is simply the extension of conventional proportional counter operation (using CO/sub 2/ as counter gas) to very small size carbon samples. The first method is very fast, precise, and capable of treating samples of even sub-milligram size, but requires an expensive installation. The second method is slow (counting times of two months or more are necessary), can probably be made sufficiently precise to handle most problems, works down to sample sizes of 10 mg carbon, and is relatively inexpensive, especially to install in already existing radiocarbon laboratories. It is this second method and its implications that are discussed in the present paper.

  7. A continuous mode data acquisition technique for proton recoil proportional counter neutron spectrometers

    SciTech Connect

    Bennett, E.F.

    1989-03-01

    The existing proton recoil proportional counter measurement technique used at FNS for joint FNS-ANL fusion blanket neutron spectroscopy requires that numerous piece-wise (but overlapping) measurements be carried out at a sequence of fixed counter voltages. The composite results of all of these independent measurements are required to construct a single neutron spectrum. This approach has been found to be both inefficient and subject to systematic errors. An alternative approach, in which data is acquired continuously using a slow time modulation of the high voltage bias supply, is here described. The electronics requirements are consistent with the basic detector/amplifier systems now operable at FNS. Some additional hardware including a programmable high voltage bias supply and a random amplitude test pulse generator are necessary. A description of the electronics and data acquisition hardware for these measurements will be provided at a later date. In this report we emphasize the numerical procedures involved to acquire and reduce data, and provide an illustrative example using one of the hardest neutron spectra readily available for this work at ANL. 6 refs., 26 figs.

  8. Microdosimetry study of THOR BNCT beam using tissue equivalent proportional counter.

    PubMed

    Hsu, F Y; Hsiao, H W; Tung, C-J; Liu, H M; Chou, F I

    2009-07-01

    Boron neutron capture therapy (BNCT) is a cancer treatment modality using a nuclear reactor and a boron compound drug. In Taiwan, Tsing Hua open-pool reactor (THOR) has been modulated for the basic research of BNCT for years. A new BNCT beam port was built in 2004 and used to prepare the first clinical trial in the near future. This work reports the microdosimetry study of the THOR BNCT beam by means of the tissue equivalent proportional counter (TEPC). Two self-fabricated TEPCs (the boron-doped versus the boron-free counter wall) were introduced. These dual TEPCs were applied to measure the lineal energy distributions in air and water phantom irradiated by the THOR BNCT mixed radiation field. Dose contributions from component radiations of different linear energy transfers (LETs) were analyzed. Applying a lineal energy dependent biological weighting function, r(y), to the total and individual lineal energy distributions, the effective relative biological effectiveness (RBE), neutron RBE, photon RBE, and boron capture RBE (BNC RBE) were all determined at various depths of the water phantom. Minimum and maximum values of the effective RBE were 1.68 and 2.93, respectively. The maximum effective RBE occurred at 2cm depth in the phantom. The average neutron RBE, photon RBE, and BNC RBE values were 3.160+/-0.020, 1.018+/-0.001, and 1.570+/-0.270, respectively, for the THOR BNCT beam.

  9. Gamma camera for medical applications, using a multiwire proportional counter. [Dogs, pigs

    SciTech Connect

    Lacy, L.J.; LeBlanc, A.D.; Babich, J.W.; Bungo, M.W.; Latson, L.A.; Lewis, R.M.; Poliner, L.R.; Jones, R.H.; Johnson, P.C.

    1984-09-01

    A multiwire proportional counter gamma camera, specially designed for nuclear medicine applications, is portable and weighs less than 50 lb including shielding and collimator. The basic operating characteristics have been investigated with various radioactive sealed sources. The camera demonstrates a peak count rate of 850,000 cps, an intrinsic spatial resolution of 2.5 mm, and excellent image uniformity when used with x-ray sources in the range of 22-81 keV. Tests of the device with Ta-178 using 20 mCi injections provided images of quality comparable to those obtained from 15 mCi Tc-99m studies with conventional imaging devices. The camera used with Ta-178 offers particular promise in first-pass nuclear cardiology studies.

  10. Calibration of the Rossi X-ray Timing Explorer Proportional Counter Array

    NASA Technical Reports Server (NTRS)

    Jahoda, Keith; Markwardt, Craig B.; Radeva, Yana; Rots, Arnold H.; Stark, Michael J.; Swank, Jean H.; Strohmayer, Tod E.; Zhang, William

    2004-01-01

    We present the calibration and background model for the Proportional Counter Array (PCA) aboard the Rossi X-ray Timing Explorer (RXTE). The energy calibration is systematics limited below 10 keV with deviations from a power law fit to the Crab nebula plus pulsar loss than 1%. Unmodelled variations in the instrument background amount to less than 2% of the observed background below 10 keV and less than 1% between 10 and 20 keV. Individual photon arrival times are accurate to 4.4 microseconds at all times during the mission and to 2.5 microseconds after 29 April 1997. The peak pointing direction of the five collimators is known at few arcsecond precision.

  11. Alpha-beta monitoring system based on pair of simultaneous Multi-Wire Proportional Counters

    NASA Astrophysics Data System (ADS)

    Wengrowicz, U.; Amidan, D.; Orion, I.

    2016-08-01

    A new approach for a simultaneous alpha-beta Multi-wire Proportional Counter (MWPC) is presented. The popular approach for alpha-beta monitoring systems consists of a large area MWPC using noble gas flow such as Argon Methane. This method of measurement is effective but requires large-scale and expensive maintenance due to the needs of gas flow control and periodic replacements. In this work, a pair of simultaneous MWPCs for alpha-beta measuring is presented. The developed detector consists of a sealed gas MWPC sensor for beta particles, behind a free air alpha sensor. This approach allows effective simultaneous detection and discrimination of both alpha and beta radiation without the maintenance cost noble gas flow required for unsealed detectors.

  12. Shielding experiment of heavy-ion produced neutrons using a tissue-equivalent proportional counter.

    PubMed

    Nunomiya, T; Yonai, S; Takada, M; Fukumura, A; Nakamura, T

    2003-01-01

    A shielding experiment was performed at the HIMAC (Heavy Ion Medical Accelerator in Chiba), of National Institute of Radiological Sciences (NIRS), to measure neutron dose using a spherical TEPC (tissue-equivalent proportional counter) of 12.55 cm inner diameter. Neutrons are produced from a 5 cm thick stopping length Cu target bombarded by 400 MeV/nucleon C6+ ions and penetrate concrete or iron shields of various thicknesses at 0 degree to the beam direction. From this shielding experiment. y-distribution, mean lineal energy, absorbed dose, dose equivalent and mean-quality factor were obtained behind the shield as a function of shield thickness. The neutron dose attenuation lengths were also obtained as 126 g cm(-2) for concrete and 211 g cm(-2) for iron. The measured results were compared with the calculated results using the MARS Monte Carlo code.

  13. High-Sensitivity X-ray Polarimetry with Amorphous Silicon Active-Matrix Pixel Proportional Counters

    NASA Technical Reports Server (NTRS)

    Black, J. K.; Deines-Jones, P.; Jahoda, K.; Ready, S. E.; Street, R. A.

    2003-01-01

    Photoelectric X-ray polarimeters based on pixel micropattern gas detectors (MPGDs) offer order-of-magnitude improvement in sensitivity over more traditional techniques based on X-ray scattering. This new technique places some of the most interesting astronomical observations within reach of even a small, dedicated mission. The most sensitive instrument would be a photoelectric polarimeter at the focus of 2 a very large mirror, such as the planned XEUS. Our efforts are focused on a smaller pathfinder mission, which would achieve its greatest sensitivity with large-area, low-background, collimated polarimeters. We have recently demonstrated a MPGD polarimeter using amorphous silicon thin-film transistor (TFT) readout suitable for the focal plane of an X-ray telescope. All the technologies used in the demonstration polarimeter are scalable to the areas required for a high-sensitivity collimated polarimeter. Leywords: X-ray polarimetry, particle tracking, proportional counter, GEM, pixel readout

  14. Evaluation of 2-PI liquid scintillation whole body counter using MCNP

    NASA Astrophysics Data System (ADS)

    Mireles-Garcia, Fernando

    The 2-pi liquid scintillation whole body counter (WBC) at the University of Missouri-Columbia has been evaluated using MCNP-4A (a general Monte Carlo Neutron-Photon transport code, Version 4A). This facility is of importance to a wide variety of applications, such as determination of body fat content in human and animal subjects and measurement of radioactive tracers in animals. Phantoms and mathematical models were used in this research to upgrade the calibration procedures of the WBC. Since the existing protocol assumes a simple efficiency calibration based only upon body mass, it does not account for body shape and gives no methodology for placement of the subject below the detectors. Mathematical models were developed to calculate geometry efficiency for a variety of subjects and geometries utilizing the MCNP-4A transport code. Comparison of the results from simulation with experimental data shows excellent agreement not only in the shape of the curves as a function of subject position but also in absolute magnitude. In the case of the WBC and a phantom consisting of 40 liters of water containing 800 grams of sp+K the error in the magnitude is within 6%, which is easily attributable to the experimental calibration of the detectors. The efficiency of the WBC has been calculated for different weights for modified Adam-E through Adam-L model geometries; hence weight and shape can be modeled carefully and correction can be applied to actual human measurements based upon this work.

  15. (Development of an inexpensive high resolution positron multiwire proportional counter). Progress report, 1981

    SciTech Connect

    Not Available

    1982-01-01

    The development of surgical and medical techniques for the treatment of coronary artery disease has dramatized the need for a safe, relatively non-traumatic measure of regional perfusion. This is particularly critical during the early stages of coronary artery disease, well before symptoms become severe enough to warrant characterization. The primary limitation in the implementation of this new technique is the lack of a high resolution, relatively inexpensive positron detecting system to enable myocardial perfusion scintigraphy with rubidium-82 to be performed as a screening test in hospitals without direct access to cyclotron facilities. The positron multiwire proportional counter which will result from the proposed projects will solve this problem. The dispersion of the absorbing material will be achieved by stringing wires of high Z material, such as tungsten, in a cross pattern. By stacking the wires, an efficiency of 30% can be obtained for 0.5 MeV photons. The wire layers will be at graded voltages; the ionization from the photoelectrons is thereby drifted through the stack and picked up by sense wires operating in the proportional mode. Resolutions within the 3 mm range should also be achievable. 15 figs.

  16. Design and performance of A 3He-free coincidence counter based on parallel plate boron-lined proportional technology

    NASA Astrophysics Data System (ADS)

    Henzlova, D.; Menlove, H. O.; Marlow, J. B.

    2015-07-01

    Thermal neutron counters utilized and developed for deployment as non-destructive assay (NDA) instruments in the field of nuclear safeguards traditionally rely on 3He-based proportional counting systems. 3He-based proportional counters have provided core NDA detection capabilities for several decades and have proven to be extremely reliable with range of features highly desirable for nuclear facility deployment. Facing the current depletion of 3He gas supply and the continuing uncertainty of options for future resupply, a search for detection technologies that could provide feasible short-term alternative to 3He gas was initiated worldwide. As part of this effort, Los Alamos National Laboratory (LANL) designed and built a 3He-free full scale thermal neutron coincidence counter based on boron-lined proportional technology. The boron-lined technology was selected in a comprehensive inter-comparison exercise based on its favorable performance against safeguards specific parameters. This paper provides an overview of the design and initial performance evaluation of the prototype High Level Neutron counter-Boron (HLNB). The initial results suggest that current HLNB design is capable to provide ~80% performance of a selected reference 3He-based coincidence counter (High Level Neutron Coincidence Counter, HLNCC). Similar samples are expected to be measurable in both systems, however, slightly longer measurement times may be anticipated for large samples in HLNB. The initial evaluation helped to identify potential for further performance improvements via additional tailoring of boron-layer thickness.

  17. Design and performance of A 3He-free coincidence counter based on parallel plate boron-lined proportional technology

    DOE PAGES

    Henzlova, D.; Menlove, H. O.; Marlow, J. B.

    2015-07-01

    Thermal neutron counters utilized and developed for deployment as non-destructive assay (NDA) instruments in the field of nuclear safeguards traditionally rely on 3He-based proportional counting systems. 3He-based proportional counters have provided core NDA detection capabilities for several decades and have proven to be extremely reliable with range of features highly desirable for nuclear facility deployment. Facing the current depletion of 3He gas supply and the continuing uncertainty of options for future resupply, a search for detection technologies that could provide feasible short-term alternative to 3He gas was initiated worldwide. As part of this effort, Los Alamos National Laboratory (LANL) designedmore » and built a 3He-free full scale thermal neutron coincidence counter based on boron-lined proportional technology. The boronlined technology was selected in a comprehensive inter-comparison exercise based on its favorable performance against safeguards specific parameters. This paper provides an overview of the design and initial performance evaluation of the prototype High Level Neutron counter – Boron (HLNB). The initial results suggest that current HLNB design is capable to provide ~80% performance of a selected reference 3He-based coincidence counter (High Level Neutron Coincidence Counter, HLNCC). Similar samples are expected to be measurable in both systems, however, slightly longer measurement times may be anticipated for large samples in HLNB. The initial evaluation helped to identify potential for further performance improvements via additional tailoring of boron-layer thickness.« less

  18. FInal Report: First Principles Modeling of Mechanisms Underlying Scintillator Non-Proportionality

    SciTech Connect

    Aberg, Daniel; Sadigh, Babak; Zhou, Fei

    2015-01-01

    This final report presents work carried out on the project “First Principles Modeling of Mechanisms Underlying Scintillator Non-Proportionality” at Lawrence Livermore National Laboratory during 2013-2015. The scope of the work was to further the physical understanding of the microscopic mechanisms behind scintillator nonproportionality that effectively limits the achievable detector resolution. Thereby, crucial quantitative data for these processes as input to large-scale simulation codes has been provided. In particular, this project was divided into three tasks: (i) Quantum mechanical rates of non-radiative quenching, (ii) The thermodynamics of point defects and dopants, and (iii) Formation and migration of self-trapped polarons. The progress and results of each of these subtasks are detailed.

  19. ROSAT Position Sensitive Proportional Counter spectra of six Seyfert 1 galaxies

    NASA Technical Reports Server (NTRS)

    Turner, T. J.; George, I. M.; Mushotzky, R. F.

    1993-01-01

    We present the results from ROSAT Position Sensitive Proportional Counter observations of six Seyfert 1 galaxies in the soft (0.1-2.0 keV) X-ray band. The sources (Mrk 335, ESO 198-G24, ESO 141-G55, Mrk 509, NGC 7469, and MCG-2-58-22) were chosen to have low absorbing column densities along the line of sight. As expected, it is found that all the sources possess significantly steeper spectra below about 1 keV than observed at higher X-ray energies. Assuming a simple absorbed power-law spectral model, the mean (photon) spectral index for the sample is Gamma = 2.38 +/- 0.25, compared to the canonical 1.7 typically observed in the 2-10 keV band. Furthermore, we find strong evidence for soft X-ray spectral features in half the sources. In NGC 7469 and ESO 198-G24, we find that the addition of a narrow emission line or an absorption edge to the underlying continuum is a significant improvement to the parameterization of the spectra. Mrk 335 also shows evidence for spectral complexity, but from these data it is not possible to unambiguously distinguish between an absorption edge and a steepening of the spectrum at low energies. We examine these results in the light of the accuracy of the PSPC spectral calibration.

  20. Simulated Response of a Tissue-equivalent Proportional Counter on the Surface of Mars.

    PubMed

    Northum, Jeremy D; Guetersloh, Stephen B; Braby, Leslie A; Ford, John R

    2015-10-01

    Uncertainties persist regarding the assessment of the carcinogenic risk associated with galactic cosmic ray (GCR) exposure during a mission to Mars. The GCR spectrum peaks in the range of 300(-1) MeV n to 700 MeV n(-1) and is comprised of elemental ions from H to Ni. While Fe ions represent only 0.03% of the GCR spectrum in terms of particle abundance, they are responsible for nearly 30% of the dose equivalent in free space. Because of this, radiation biology studies focusing on understanding the biological effects of GCR exposure generally use Fe ions. Acting as a thin shield, the Martian atmosphere alters the GCR spectrum in a manner that significantly reduces the importance of Fe ions. Additionally, albedo particles emanating from the regolith complicate the radiation environment. The present study uses the Monte Carlo code FLUKA to simulate the response of a tissue-equivalent proportional counter on the surface of Mars to produce dosimetry quantities and microdosimetry distributions. The dose equivalent rate on the surface of Mars was found to be 0.18 Sv y(-1) with an average quality factor of 2.9 and a dose mean lineal energy of 18.4 keV μm(-1). Additionally, albedo neutrons were found to account for 25% of the dose equivalent. It is anticipated that these data will provide relevant starting points for use in future risk assessment and mission planning studies.

  1. HILT - A heavy ion large area proportional counter telescope for solar and anomalous cosmic rays

    NASA Technical Reports Server (NTRS)

    Klecker, Berndt; Hovestadt, Dietrich; Scholer, M.; Arbinger, H.; Ertl, M.; Kaestle, H.; Kuenneth, E.; Laeverenz, P.; Seidenschwang, E.; Blake, J. B.

    1993-01-01

    The HILT sensor has been designed to measure heavy ion elemental abundances, energy spectra, and direction of incidence in the mass range from He to Fe and in the energy range 4 to 250 MeV/nucleon. With its large geometric factor of 60 sq cm sr the sensor is optimized to provide compositional and spectral measurements for low intensity cosmic rays (i.e. for small solar energetic particle events and for the anomalous component of cosmic rays). The instrument combines a large area ion drift chamber-proportional counter system with two arrays of 16 Li-drift solid state detectors and 16 CsI crystals. The multi dE/dx-E technique provides a low background mass and energy determination. The sensor also measures particle direction. Combining these measurements with the information on the spacecraft position and attitude in the low-altitude polar orbit, it will be possible to infer the ionic charge of the ions from the local cutoff of the Earth's magnetic field. The ionic charge in this energy range is of particular interest because it provides unique clues to the origin of these particles and has not been investigated systematically so far. Together with the other instruments on board SAMPEX (LEICA, MAST, and PET), a comprehensive measurement of the entire solar and anomalous particle population will be achieved.

  2. Compact Tissue-equivalent Proportional Counter for Deep Space Human Missions

    PubMed Central

    Straume, T.; Braby, L.A.; Borak, T.B.; Lusby, T.; Warner, D.W.; Perez-Nunez, D.

    2015-01-01

    Abstract Effects on human health from the complex radiation environment in deep space have not been measured and can only be simulated here on Earth using experimental systems and beams of radiations produced by accelerators, usually one beam at a time. This makes it particularly important to develop instruments that can be used on deep-space missions to measure quantities that are known to be relatable to the biological effectiveness of space radiation. Tissue-equivalent proportional counters (TEPCs) are such instruments. Unfortunately, present TEPCs are too large and power intensive to be used beyond low Earth orbit (LEO). Here, the authors describe a prototype of a compact TEPC designed for deep space applications with the capability to detect both ambient galactic cosmic rays and intense solar particle event radiation. The device employs an approach that permits real-time determination of (and thus quality factor) using a single detector. This was accomplished by assigning sequential sampling intervals as detectors “1” and “2” and requiring the intervals to be brief compared to the change in dose rate. Tests with γ rays show that the prototype instrument maintains linear response over the wide dose-rate range expected in space with an accuracy of better than 5% for dose rates above 3 mGy h−1. Measurements of for 200 MeV n−1 carbon ions were better than 10%. Limited tests with fission spectrum neutrons show absorbed dose-rate accuracy better than 15%. PMID:26313585

  3. Calibration of an Ultra-Low-Background Proportional Counter for Measuring 37Ar

    SciTech Connect

    Seifert, Allen; Aalseth, Craig E.; Bonicalzi, Ricco; Bowyer, Ted W.; Day, Anthony R.; Fuller, Erin S.; Haas, Derek A.; Hayes, James C.; Hoppe, Eric W.; Humble, Paul H.; Keillor, Martin E.; LaFerriere, Brian D.; Mace, Emily K.; McIntyre, Justin I.; Merriman, Jason H.; Miley, Harry S.; Myers, Allan W.; Orrell, John L.; Overman, Cory T.; Panisko, Mark E.; Williams, Richard M.

    2013-08-08

    Abstract. An ultra-low-background proportional counter (ULBPC) design has been developed at Pacific Northwest National Laboratory (PNNL) using clean materials, primarily electrochemically-purified copper. This detector, along with an ultra-low-background counting system (ULBCS), was developed to complement a new shallow underground laboratory (30 meters water-equivalent) constructed at PNNL. The ULBCS design includes passive neutron and gamma shielding, along with an active cosmic-veto system. This system provides a capability for making ultra-sensitive measurements to support applications like age-dating soil hydrocarbons with 14C/3H, age-dating of groundwater with 39Ar, and soil-gas assay for 37Ar to support On-Site Inspection (OSI). On-Site Inspection is a key component of the verification regime for the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Measurements of radionuclides created by an underground nuclear explosion are valuable signatures of a Treaty violation. For OSI, the 35-day half-life of 37Ar, produced from neutron interactions with calcium in soil, provides both high specific activity and sufficient time for inspection before decay limits sensitivity. This work describes the calibration techniques and analysis methods developed to enable quantitative measurements of 37Ar samples over a broad range of pressures. These efforts, along with parallel work in progress on gas chemistry separation, are expected to provide a significant new capability for 37Ar soil gas background studies.

  4. Large-area proportional counter camera for the US National Small-Angle Neutron Scattering Facility

    SciTech Connect

    Abele, R.K.; Allin, G.W.; Clay, W.T.; Fowler, C.E.; Kopp, M.K.

    1980-01-01

    An engineering model of a multiwire position-sensitive proportional-counter (PSPC) was developed, tested, and installed at the US National Small-Angle Neutron Scattering Facility at ORNL. The PSPC is based on the RC-encoding and time-difference decoding method to measure the spatial coordinates of the interaction loci of individual scattered neutrons. The active area of the PSPC is 65 cm x 65 cm, and the active depth is 3.6 cm. The spatial uncertainty in both coordinates is approx. 1.0 cm (fwhm) for thermal neutrons; thus, a matrix of 64 x 64 picture elements is resolved. The count rate capability for randomly detected neutrons is 10/sup 4/ counts per second, with < 3% coincidence loss. The PSPC gas composition is 63% /sup 3/He, 32% Xe, and 5% CO/sub 2/ at an absolute pressure of approx. 3 x 10/sup 5/ Pa (3 atm). The detection efficiency is approx. 90% for the 0.475-nm (4.75-A) neutrons used in the scattering experiments.

  5. SINGLE ANODE TRIPLE GEM TISSUE EQUIVALENT PROPORTIONAL COUNTER AS THE BASIS FOR A PERSONAL NEUTRON DOSIMETER.

    PubMed

    Seydaliev, M; Dubeau, J; Ali, F

    2016-08-29

    This paper reports on a tissue-equivalent proportional counter (TEPC) based on a triple gas electron multiplier structure, with a single pad readout, as a basis for a personal neutron dosimeter. Its dosimetric response was studied using the (252)Cf neutron source at the Health Physics Generator Facility of the Canadian Nuclear Laboratories. Measured lineal energy spectra were found to be in agreement with numerical simulations performed with Monte Carlo N-Particle eXtended (MCNPX). Both simulations and measurements showed that the mean pathlength of secondary charged particles in the TEPC gas was best represented by the thickness of the drift region of the device. It was determined that the Cauchy Theorem, used to calculate the mean chord length in spherical and cylindrical TEPCs, overestimated the simulated mean chord length by nearly a factor of two. Important operational characteristics of the device were investigated, including gas gain, sensitivity and dosimetric response, as functions of tissue-equivalent gas pressure. This work demonstrates that the proposed design can serve as the basis for a personal neutron dosimeter device, which would satisfy the angular dosimetric response criteria of the personal dosimeter standard IEC61526.

  6. Large Area X-ray Proportional Counter (LAXPC) instrument onboard ASTROSAT

    NASA Astrophysics Data System (ADS)

    Yadav, J. S.; Agrawal, P. C.; Antia, H. M.; Chauhan, Jai Verdhan; Dedhia, Dhiraj; Katoch, Tilak; Madhwani, P.; Manchanda, R. K.; Misra, Ranjeev; Pahari, Mayukh; Paul, B.; Shah, Parag

    2016-07-01

    ASTROSAT, India's first dedicated astronomy space mission was launched on September 28, 2015. The Large Area X-ray Proportional Counter (LAXPC) is one of the major payloads on ASTROSAT. A cluster of three co-aligned identical LAXPC detectors provide large area of collection .The large detection volume (15 cm depth) filled with mixture of xenon gas (90(%) and methane (10%) at 2 atmospheres pressure, results in detection efficiency greater than 50%, above 30 keV. The LAXPC instrument is best suited for X-ray timing and spectral studies. It will provide the largest effective area in 3-80 keV range among all the satellite missions flown so far worldwide and will remain so for the next 5-10 years. The LAXPC detectors have been calibrated using radioactive sources in the laboratory. GEANT4 simulation for LAXPC detectors was carried out to understand detector background and its response. The LAXPC instrument became fully operational on 19th October 2015 for the first time in space. We have performed detector calibration in orbit. The LAXPC instrument is functioning well and has achieved all detector parameters proposed initially. In this paper, we will describe LAXPC detector calibration in lab as well as in orbit along with first results.

  7. Compact Tissue-equivalent Proportional Counter for Deep Space Human Missions.

    PubMed

    Straume, T; Braby, L A; Borak, T B; Lusby, T; Warner, D W; Perez-Nunez, D

    2015-10-01

    Effects on human health from the complex radiation environment in deep space have not been measured and can only be simulated here on Earth using experimental systems and beams of radiations produced by accelerators, usually one beam at a time. This makes it particularly important to develop instruments that can be used on deep-space missions to measure quantities that are known to be relatable to the biological effectiveness of space radiation. Tissue-equivalent proportional counters (TEPCs) are such instruments. Unfortunately, present TEPCs are too large and power intensive to be used beyond low Earth orbit (LEO). Here, the authors describe a prototype of a compact TEPC designed for deep space applications with the capability to detect both ambient galactic cosmic rays and intense solar particle event radiation. The device employs an approach that permits real-time determination of yD (and thus quality factor) using a single detector. This was accomplished by assigning sequential sampling intervals as detectors “1” and “2” and requiring the intervals to be brief compared to the change in dose rate. Tests with g rays show that the prototype instrument maintains linear response over the wide dose-rate range expected in space with an accuracy of better than 5% for dose rates above 3 mGy h(-1). Measurements of yD for 200 MeV n(-1) carbon ions were better than 10%. Limited tests with fission spectrum neutrons show absorbed dose-rate accuracy better than 15%.

  8. Initial characterization of unequal-length, low-background proportional counters for absolute gas-counting applications

    SciTech Connect

    Mace, E. K.; Aalseth, C. E.; Bonicalzi, R.; Day, A. R.; Fuller, E. S.; Hayes, J. C.; Hoppe, E. W.; LaFerriere, B. D.; Merriman, J. H.; Overman, C. T.; Seifert, A.; Williams, R. M.

    2013-08-08

    Characterization of two sets of custom unequal length proportional counters is underway at Pacific Northwest National Laboratory (PNNL). These detectors will be used in measurements to determine the absolute activity concentration of gaseous radionuclides (e.g., {sup 37}Ar). A set of three detectors has been fabricated based on previous PNNL ultra-low-background proportional counter designs and now operate in PNNL's shallow underground counting laboratory. A second set of four counters has also been fabricated using clean assembly of Oxygen-Free High-Conductivity copper components for use in a shielded above-ground counting laboratory. Characterization of both sets of detectors is underway with measurements of background rates, gas gain, and energy resolution. These results will be presented along with a shielding study for the above-ground cave.

  9. Use of Proportional Counters for Yield Measurement in Extremely Short Pulses of Fast Neutrons: Counting Statistics and Absolute Calibration

    NASA Astrophysics Data System (ADS)

    Tarifeño-Saldivia, A.; Mayer, R. E.; Pavez, C.; Soto, L.

    2010-08-01

    A method for absolute calibration of proportional counters for pulsed fast neutrons is presented. The method is based on the use of an isotopic standard source and development of a model for counting detected events from area of a signal compounded by single piled up neutron pulses. Effects of detection counting statistics and electrical background noise are also considered.

  10. Tissue Equivalent Proportional Counter Microdosimetry Measurements Utilized Aboard Aircraft and in Accelerator Based Space Radiation Shielding Studies

    NASA Technical Reports Server (NTRS)

    Gersey, Brad B.; Wilkins, Richard T.

    2010-01-01

    This slide presentation reviews the Tissue Equivalent Proportional Counter (TEPC), a description of the spatially restricted LET Model, high energy proton TEPC and the results of modeling, the study of shielding and the results from the flight exposures with the TEPC.

  11. RADIATION COUNTER

    DOEpatents

    Goldsworthy, W.W.

    1958-02-01

    This patent relates to a radiation counter, and more particularly, to a scintillation counter having high uniform sensitivity over a wide area and capable of measuring alpha, beta, and gamma contamination over wide energy ranges, for use in quickly checking the contami-nation of personnel. Several photomultiplier tubes are disposed in parallel relationship with a light tight housing behind a wall of scintillation material. Mounted within the housing with the photomultipliers are circuit means for producing an audible sound for each pulse detected, and a range selector developing a voltage proportional to the repetition rate of the detected pulses and automatically altering its time constant when the voltage reaches a predetermined value, so that manual range adjustment of associated metering means is not required.

  12. Time resolution of time-of-flight detector based on multiple scintillation counters readout by SiPMs

    NASA Astrophysics Data System (ADS)

    Cattaneo, P. W.; De Gerone, M.; Gatti, F.; Nishimura, M.; Ootani, W.; Rossella, M.; Shirabe, S.; Uchiyama, Y.

    2016-08-01

    A new timing detector measuring ∼ 50 MeV / c positrons is under development for the MEG II experiment, aiming at a time resolution σt ∼ 30 ps. The resolution is expected to be achieved by measuring each positron time with multiple counters made of plastic scintillator readout by silicon photomultipliers (SiPMs). The purpose of this work is to demonstrate the time resolution for ∼ 50 MeV / c positrons using prototype counters. Counters with dimensions of 90 × 40 × 5mm3 readout by six SiPMs (three on each 40 × 5mm2 plane) were built with SiPMs from Hamamatsu Photonics and AdvanSiD and tested in a positron beam at the DAΦNE Beam Test Facility. The time resolution was found to improve nearly as the square root of the number of counter hits. A time resolution σt = 26.2 ± 1.3 ps was obtained with eight counters with Hamamatsu SiPMs. These results suggest that the design resolution is achievable in the MEG II experiment.

  13. Isomer Tagging with a Dual Multi-Wire Proportional Counter and a Differential Plunger

    SciTech Connect

    Cullen, D. M.; Mason, P. J. R.; Khan, S.; Kishada, A. M.; Varley, B. J.; Rigby, S. V.; Scholey, C.; Greenlees, P.; Rahkila, P.; Jones, P. M.; Julin, R.; Juutinen, S.; Leino, M.; Leppaenen, A. P.; Nyman, M.; Uusitalo, J.; Grahn, T.; Pakarinen, J.; Nieminen, P.

    2008-05-12

    This report details the status of an experimental research programme which has studied isomeric states in the mass 130-160 region of the nuclear chart. Several new isomers have been established and characterised near the proton drip line using a recoil isomer tagging technique at the University of Jyvaeskylae, Finland. The latest experiments have been performed with a modified setup where the standard GREAT focal-plane double-sided silicon-strip detector was changed to a dual multi-wire proportional-counter arrangement. This new setup has improved capability for short-lived isomer studies where large focal-plane rates can be tolerated. The results of key recent experiments for nuclei situated above ({sup 153}Yb, {sup 152}Tm) and below ({sup 144}Ho, {sup 142}Tb) the N = 82 shell gap were presented. These studies have charted the evolution of isomeric states across the neutron shell from K-Isomers at N = 74, to shape isomers at N = 77 and shell-model isomers at N = 82, 83. The excitation energies for some of the lowest-lying excited states in these isomeric nuclei show behaviour which is characteristic of an X(5) symmetry falling midway between the limits expected for pure vibrational and rotational behaviour. The future prospects for studies of these nuclei were discussed using an isomer-tagged differential-plunger setup. This technique will be capable of establishing the deformation of the states above the isomers and will aid in determining whether their behaviour is indeed well described by the X(5) symmetry limit.

  14. ADVANCES IN THE RXTE PROPORTIONAL COUNTER ARRAY CALIBRATION: NEARING THE STATISTICAL LIMIT

    SciTech Connect

    Shaposhnikov, Nikolai; Jahoda, Keith; Markwardt, Craig; Swank, Jean; Strohmayer, Tod

    2012-10-01

    During its 16 years of service, the Rossi X-Ray Timing Explorer (RXTE) mission has provided an extensive archive of data, which will serve as a primary source of high cadence observations of variable X-ray sources for fast timing studies. It is, therefore, very important to have the most reliable calibration of RXTE instruments. The Proportional Counter Array (PCA) is the primary instrument on board RXTE which provides data in 3-50 keV energy range with submillisecond time resolution in up to 256 energy channels. In 2009, the RXTE team revised the response residual minimization method used to derive the parameters of the PCA physical model. The procedure is based on the residual minimization between the model spectrum for Crab Nebula emission and a calibration data set consisting of a number of spectra from the Crab and the on-board Am{sub 241} calibration source, uniformly covering the whole RXTE mission operation period. The new method led to a much more effective model convergence and allowed for better understanding of the PCA energy-to-channel relationship. It greatly improved the response matrix performance. We describe the new version of the RXTE/PCA response generator PCARMF v11.7 (HEASOFT Release 6.7) along with the corresponding energy-to-channel conversion table (version e05v04) and their difference from the previous releases of PCA calibration. The new PCA response adequately represents the spectrum of the calibration sources and successfully predicts the energy of the narrow iron emission line in Cas-A throughout the RXTE mission.

  15. Advances in the RXTE Proportional Counter Array Calibration: Nearing the Statistical Limit

    NASA Technical Reports Server (NTRS)

    Shaposhnikov, Nikolai; Jahoda, Keith; Markwardt, Craig; Swank, Jean; Strohmayer, Tod

    2012-01-01

    During its 16 years of service Rossi X-ray Timing Explorer (RXTE) mission has provided an extensive archive of data, which will serve as a primary source of high cadence observation of variable X-ray sources for fast timing studies. It is, therefore, very important to have the most reliable calibration of RXTE instruments. The Proportional Counter Array (PCA) is the primary instrument on-board RXTE which provides data in 2-50 keY with higher than millisecond time resolution in up to 256 energy channels. In 2009 RXTE team revised the response residual minimization method used to derive the parameters of the PCA physical model. The procedure is now based on the residual minimization between the model spectrum for Crab nebula emission and a calibration data set consisting of a number of spectra from the Crab and the on-board Am241 calibration source, uniformly covering a whole RXTE span. The new method led to a much more effective model convergence and allowed for better understanding of the behavior of the PCA energy-to-channel relationship. It greatly improved the response matrix performance. We describe the new version of the RXTE/PCA response generator PCARMF vll.7 along with the corresponding energy-to-channel conversion table (version e05v04) and their difference from the previous releases of PCA calibration. The new PCA response adequately represents the spectrum of the calibration sources and successfully predicts the energy of the narrow iron emission line in Cas-A throughout the RXTE mission.

  16. Miniature Tissue Equivalent Proportional Counter dosimeter for active personal radiation monitoring of astronauts

    NASA Astrophysics Data System (ADS)

    Watson Huber, Aubrey

    The accurate measurement of spaceflight crew radiation exposure is of utmost importance. If onboard instrumentation shows that the pre-determined limit for radiation exposure has been met or exceeded during a mission, that mission can be greatly affected by the implementation of precautionary measures, or, in more extreme cases, the crew's health being negatively affected. Large active regional monitors determine real-time radiation risks of the crew during spaceflight, while small passive personal badges detect individual astronaut total exposure levels upon their return to Earth. At present, there are no personal active radiation dosimeters that can assess the continuous radiation risk to individual astronauts during spaceflight. Personal active radiation devices would be ideal for current operations in low-Earth orbit (LEO), as well as upcoming extravehicular activities on the Moon, Mars, or other planetary bodies. This project focused on the miniaturization of the Tissue Equivalent Proportional Counters (TEPCs) presently being utilized on the International Space Station (ISS) and Space Shuttle, enabling them to become personal crew dosimeters. The miniaturized TEPC prototype design has dimensions of 7.6 x 10.1 x 2.54 cm (3 x 4 x 1 in). It is composed of a 3 x 4 array of 1.27 cm (0.5 in) spherical detectors for measurements equivalent to a 4.39 cm (1.73 in) spherical detector, with an additional standalone sphere of diameter 1.27 cm (0.5 in) for taking measurements in high-flux environments. The detector simulates a tissue-equivalent diameter of 2 microns, is sensitive to lineal energies of 0.3 -- 1000 keV/micron, and can measure charged particles and neutrons ranging from 0.01 -- 100 mGy/hr.

  17. Simple model relating recombination rates and non-proportional light yield in scintillators

    SciTech Connect

    Moses, William W.; Bizarri, Gregory; Singh, Jai; Vasil'ev, Andrey N.; Williams, Richard T.

    2008-09-24

    We present a phenomenological approach to derive an approximate expression for the local light yield along a track as a function of the rate constants of different kinetic orders of radiative and quenching processes for excitons and electron-hole pairs excited by an incident {gamma}-ray in a scintillating crystal. For excitons, the radiative and quenching processes considered are linear and binary, and for electron-hole pairs a ternary (Auger type) quenching process is also taken into account. The local light yield (Y{sub L}) in photons per MeV is plotted as a function of the deposited energy, -dE/dx (keV/cm) at any point x along the track length. This model formulation achieves a certain simplicity by using two coupled rate equations. We discuss the approximations that are involved. There are a sufficient number of parameters in this model to fit local light yield profiles needed for qualitative comparison with experiment.

  18. The analysis of the X-ray event analyzer proportional counter data: A comment

    NASA Technical Reports Server (NTRS)

    Wilson, R. M.

    1977-01-01

    The findings, based on a comparison of simultaneous observations of a number of flares obtained with the X-REA and SOLRAD 9 instruments, which reveal the degree of deterioration of the counters with time are presented.

  19. Factors limiting the linearity of response of tissue equivalent proportional counters used in micro- and nano-dosimetry

    NASA Astrophysics Data System (ADS)

    Kowalski, T. Z.

    2017-01-01

    Proportional counters filled with tissue equivalent gas mixtures are extremely useful instruments and are being used extensively as sensitive detectors for all types of radiations to measure the energy transferred to small tissue volumes. The linearity of their response is of primary importance. So the investigation and clarification of the physical phenomena taking place in the counter and of the limits within which useful results may be obtained would contribute to a more efficient use and a wider application of these counters. The linearity of response in the dose and in the gas gain has been determined. Linearity in the dose is limited by the total count rate effect, while linearity in the gas gain is limited by secondary processes occurring in the electron avalanche and by the self-induced space charge effect.

  20. TMAE vapour of CsI layers as photocathodes in a multiwire proportional counter working at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Guerard, B.; Bruyndonckx, P.; Tavernier, S.; Shuping, Zhang

    1991-12-01

    A multiwire proportional counter (MWPC) coupled to a BaF 2 crystal has been tested at atmospheric pressure for the detection of 511 keV photons. If TMAE is used as a photosensitive agent, we found that addition of H 2O vapour to the chamber gas is very well suited for the detection of single-photoelectrons. Encouraging first results were also obtained with caesium iodide photocathodes.

  1. Separately measuring radon and thoron concentrations exhaled from soil using AlphaGUARD and liquid scintillation counter methods.

    PubMed

    Yasuoka, Y; Sorimachi, A; Ishikawa, T; Hosoda, M; Tokonami, S; Fukuhori, N; Janik, M

    2010-10-01

    It was shown that radon and thoron concentrations exhaled from soil were separately measured using the AlphaGUARD and liquid scintillation counter (LSC) methods. The thoron concentrations from the RAD 7 were used to create the conversion equation to calculate thoron levels with the AlphaGUARD. However, the conversion factor was found to depend on the air flow rate. When air containing thoron of ∼60 kBq m(-3) was fed to the scintillation cocktail, thoron and thoron progeny could not be measured with the LSC method. The radon concentration of about 10 kBq m(-3) was measured with three methods, first with the LSC method and then with two AlphaGUARDs (one in the diffusion mode and the other in the flow mode (0.5 l min(-1))). There were no significant differences between these results. Finally, it was shown that the radon and thoron concentrations in air could be measured with the AlphaGUARD and LSC methods.

  2. Searches for a sterile-neutrino admixture in detecting tritium decays in a proportional counter: New possibilities

    SciTech Connect

    Abdurashitov, D. N.; Berlev, A. I.; Likhovid, N. A.; Lokhov, A. V. Tkachev, I. I.; Yants, V. E.

    2015-03-15

    An experiment aimed at searches for an admixture of a sterile neutrino whosemass is 1 to 8 keV via detecting electrons from tritium decay in a proportional counter is proposed. The admixture in question can be discovered by a specific distortion of the energy spectrum of these electrons. For the above masses, the distortion extends over the whole spectrum; therefore, use can bemade of detectors that have a relatively low energy resolution (about 10 to 15%). A classic proportional counter is a simple and natural choice of detector for the decays of a gaseous tritium. The approach that we propose is novel in two respects. On one hand, the proportional counter used is made as a discrete unit in the form of a fully fused quartz tube. This permits a readout of current signals directly from the anode filament and ensures a high stability in the case of long-term measurements. At the same time, the application of state-of-the-art digital data-acquisition methods will make it possible to perform measurements under conditions of high counting rates—up to 10{sup 6} Hz. As a result, the energy spectrum of electrons from tritium decays that is formed by 10{sup 12} counts could be accumulated within about a month. This data sample would make it possible to set an upper limit in the range of 10{sup −3}–10{sup −5} on a sterile-neutrino admixture at a confidence level of three standard deviations (3σ) for m{sub s} in the range of 1–8 keV, this being one to two orders of magnitude more stringent than present-day limits.

  3. Development of advanced x-ray imaging crystal spectrometer utilizing a large area segmented proportional counter for KSTAR

    SciTech Connect

    Lee, S. G.; Bak, J. G.; Nam, U. W.; Moon, M. K.; Cheon, J. K.

    2007-06-15

    An advanced x-ray imaging crystal spectrometer (XICS) for KSTAR tokamak has been developed by utilizing a segmented two dimensional (2D) position-sensitive multiwire proportional counter. The XICS for the KSTAR tokamak provides time-resolved measurements of the radial ion and electron temperature profiles, toroidal plasma rotation velocity, and ionization equilibrium. The segmented 2D detector with delay-line readout and supporting electronics has been adopted to improve the photon count rate capability. The current fabrication status of the XICS for the KSTAR tokamak and the first performance test results of the prototype segmented 2D detector are presented.

  4. Development of advanced x-ray imaging crystal spectrometer utilizing a large area segmented proportional counter for KSTAR

    NASA Astrophysics Data System (ADS)

    Lee, S. G.; Bak, J. G.; Nam, U. W.; Moon, M. K.; Cheon, J. K.

    2007-06-01

    An advanced x-ray imaging crystal spectrometer (XICS) for KSTAR tokamak has been developed by utilizing a segmented two dimensional (2D) position-sensitive multiwire proportional counter. The XICS for the KSTAR tokamak provides time-resolved measurements of the radial ion and electron temperature profiles, toroidal plasma rotation velocity, and ionization equilibrium. The segmented 2D detector with delay-line readout and supporting electronics has been adopted to improve the photon count rate capability. The current fabrication status of the XICS for the KSTAR tokamak and the first performance test results of the prototype segmented 2D detector are presented.

  5. Development of advanced x-ray imaging crystal spectrometer utilizing a large area segmented proportional counter for KSTAR.

    PubMed

    Lee, S G; Bak, J G; Nam, U W; Moon, M K; Cheon, J K

    2007-06-01

    An advanced x-ray imaging crystal spectrometer (XICS) for KSTAR tokamak has been developed by utilizing a segmented two dimensional (2D) position-sensitive multiwire proportional counter. The XICS for the KSTAR tokamak provides time-resolved measurements of the radial ion and electron temperature profiles, toroidal plasma rotation velocity, and ionization equilibrium. The segmented 2D detector with delay-line readout and supporting electronics has been adopted to improve the photon count rate capability. The current fabrication status of the XICS for the KSTAR tokamak and the first performance test results of the prototype segmented 2D detector are presented.

  6. A technique for searching for the 2K capture in {sup 124}Xe with a copper proportional counter

    SciTech Connect

    Gavrilyuk, Yu. M.; Gangapshev, A. M.; Kazalov, V. V.; Kuzminov, V. V.; Panasenko, S. I.; Ratkevich, S. S.; Tekueva, D. A. Yakimenko, S. P.

    2015-12-15

    An experimental technique for searching for the 2K capture in {sup 124}Xe with a large low-background copper proportional counter is described. Such an experiment is conducted at the Baksan Neutrino Observatory of the Institute for Nuclear Research of the Russian Academy of Sciences. The experimental setup is located in the Low-Background Deep-Level Laboratory at a depth of 4900 m.w.e., where the flux of muons of cosmic rays is suppressed by a factor of 10{sup 7} relative to that at the Earth’s surface. The setup incorporates a proportional counter and low-background shielding (18 cm of copper, 15 cm of lead, and 8 cm of borated polyethylene). The results of processing the data obtained in 5 months of live measurement time are presented. A new limit on the half-life of {sup 124}Xe with respect to the 2K capture is set at the level of 2.5 × 10{sup 21} years.

  7. Proportional counter device for detecting electronegative species in an air sample

    DOEpatents

    Allman, S.L.; Chen, F.C.; Chen, C.H.

    1994-03-08

    Apparatus for detecting an electronegative species comprises an analysis chamber, an inlet communicating with the analysis chamber for admitting a sample containing the electronegative species and an ionizable component, a radioactive source within the analysis chamber for emitting radioactive energy for ionizing a component of the sample, a proportional electron detector within the analysis chamber for detecting electrons emitted from the ionized component, and a circuit for measuring the electrons and determining the presence of the electronegative species by detecting a reduction in the number of available electrons due to capture of electrons by the electronegative species. 2 figures.

  8. Proportional counter device for detecting electronegative species in an air sample

    DOEpatents

    Allman, Steve L.; Chen, Fang C.; Chen, Chung-Hsuan

    1994-01-01

    Apparatus for detecting an electronegative species comprises an analysis chamber, an inlet communicating with the analysis chamber for admitting a sample containing the electronegative species and an ionizable component, a radioactive source within the analysis chamber for emitting radioactive energy for ionizing a component of the sample, a proportional electron detector within the analysis chamber for detecting electrons emitted from the ionized component, and a circuit for measuring the electrons and determining the presence of the electronegative species by detecting a reduction in the number of available electrons due to capture of electrons by the electronegative species.

  9. Basic design of a multi wire proportional counter using Garfield++ for ILSF

    NASA Astrophysics Data System (ADS)

    Ghahremani Gol, M.; Ashrafi, S.; Rahighi, J.

    2016-12-01

    The Iranian Light Source Facility (ILSF) is a new 3 GeV third generation synchrotron radiation facility in Middle East, which at the time being is in its design stage. An important aspect for the scientific success of this new source will be the availability of well adapted detectors. Position-sensitive X-ray detectors have played an important role in synchrotron radiation X-ray experiments for many years and are still in use. An operational one-dimensional multiwire position sensitive detector with delay line readout produced by ILSF showed a position resolution of 230 μm. In this paper, we introduce a 2-D position sensitive gas detector based on a multiwire proportional chamber which will be used in small/wide angle scattering and diffraction experiments with synchrotron radiation at the ILSF. The parameters of its components, including the gas filling, gas pressure, temperature, the geometry of anode and cathodes planes as well as the expected performance of the designed system will be described in the following. For the design and the simulation of MWPC the Elmer and Garfield++ codes have been employed. We have built and tested a MWPC as a prototype at ILSF. The results obtained so far show a good position sensing. After primary test the detector has been optimized and is now ready for test at Elettra.

  10. A Combined Neutron and Gamma-Ray Multiplicity Counter Based on Liquid Scintillation Detectors

    SciTech Connect

    Andreas Enqvist; Marek Flaska; Jennifer Dolan; David L. Chichester; Sara A. Pozzi

    2011-10-01

    Multiplicity counters for neutron assay have been extensively used in materials control and accountability for nonproliferation and nuclear safeguards. Typically, neutron coincidence counters are utilized in these fields. In this work, we present a measurement system that makes use not only of neutron (n) multiplicity counting but also of gamma-ray (g) multiplicity counting and the combined higher-order multiples containing both neutrons and gamma rays. The benefit of this approach is in using both particle types available from the sample, leading to a reduction in measurement times needed when using more measurables. We present measurement results of n, g, nn, ng, gg, nnn, nng, ngg, and ggg multiples emitted by Mixed-Oxide (MOX) samples measured at Idaho National Laboratory (INL). The MOX measurement is compared to initial validation of the detection system done using a 252Cf source. The dual radiation measuring system proposed here uses extra measurables to improve the statistics when compared to a neutron-only system and allows for extended analysis and interpretation of sample parameters. New challenges such as the effect of very high intrinsic gamma-ray sources in the case of MOX samples is discussed. Successful measurements of multiples rates can be performed also when using high-Z shielding.

  11. A combined neutron and gamma-ray multiplicity counter based on liquid scintillation detectors

    NASA Astrophysics Data System (ADS)

    Enqvist, Andreas; Flaska, Marek; Dolan, Jennifer L.; Chichester, David L.; Pozzi, Sara A.

    2011-10-01

    Multiplicity counters for neutron assay have been extensively used in materials control and accountability for nonproliferation and nuclear safeguards. Typically, neutron coincidence counters are utilized in these fields. In this work, we present a measurement system that makes use not only of neutron (n) multiplicity counting but also of gamma-ray ( γ) multiplicity counting and the combined higher-order multiples containing both neutrons and gamma rays. The benefit of this approach is in using both particle types available from the sample, leading to a reduction in measurement times compared with single-particle measurements. We present measurement results of n, γ, nn, nγ, γγ, nnn, nnγ, nγγ and γγγ multiples emitted by Mixed-Oxide (MOX) samples measured at Idaho National Laboratory (INL). The MOX measurement is compared to initial validation of the detection system done using a 252Cf source. The dual radiation measuring system proposed here uses extra measurables to improve the statistics when compared to a neutron-only system and allows for extended analysis and interpretation of sample parameters. New challenges such as the effect of very high intrinsic gamma-ray sources in the case of MOX samples are discussed. Successful measurements of multiple rates can be performed also when using high-Z shielding.

  12. A low power X-ray diffractometer for soil analysis in remote locations employing a multiwire proportional counter detector array.

    NASA Technical Reports Server (NTRS)

    Gregory, J. C.; Parnell, T. A.

    1972-01-01

    A low power X-ray powder diffraction system suitable for remote mineralogical analysis of lunar, planetary, or asteroid soils has been designed. A one Curie Fe-55 source provides a monochromatic X-ray beam of 5.9 keV. Seeman-Bohlin focusing geometry is employed in the camera, allowing peak detection to proceed simultaneously at all angles and obviating the need for moving parts. The detector system is an array of 500-600 proportional counters with a wire-spacing of 1 mm. An electronics unit comprising preamplifier, postamplifier, window discriminators, and storage flip-flops requiring only 3.5 milliwatts has been designed and tested. Total instrument power is less than 5 W.

  13. Use of propane as a quench gas in argon-filled proportional counters and comparison with other quench gases

    NASA Technical Reports Server (NTRS)

    Agrawal, P. C.; Ramsey, B. D.

    1988-01-01

    An experimental investigation of propane and six other quench gases was carried out in argon-filled proportional counters. The objective of the study was to find the best gas mixture for optimizing the gas gain and the energy resolution as well as to understand the role of the ionization potential of quench gases in determining these parameters. It was found that the best gas gains and energy resolutions are obtained with propane, ethane, and isobutane in that order. The ionization potentials of these three lie below the argon metastable potentials and have the lowest value of resonance defect compared to the other quench gases. The better results obtained with these mixtures can be explained by an increased ionization yield resulting from the Penning effect. Propylene and trans-2-butene give inferior performance compared to the above three gases. Methane and carbon dioxide, the most commonly used quench gases in the argon-filled detectors, provide the worst results.

  14. Validation of a procedure for the analysis of (226)Ra in naturally occurring radioactive materials using a liquid scintillation counter.

    PubMed

    Kim, Hyuncheol; Jung, Yoonhee; Ji, Young-Yong; Lim, Jong-Myung; Chung, Kun Ho; Kang, Mun Ja

    2017-01-01

    An analytical procedure for detecting (226)Ra in naturally occurring radioactive materials (NORMs) using a liquid scintillation counter (LSC) was developed and validated with reference materials (zircon matrix, bauxite matrix, coal fly ash, and phosphogypsum) that represent typical NORMs. The (226)Ra was released from samples by a fusion method and was separated using sulfate-coprecipitation. Next, a (222)Rn-emanation technique was applied for the determination of (226)Ra. The counting efficiency was 238 ± 8% with glass vials. The recovery for the reference materials was 80 ± 11%. The linearity of the method was tested with different masses of zircon matrix reference materials. Using 15 types of real NORMs, including raw materials and by-products, this LSC method was compared with γ-spectrometry, which had already been validated for (226)Ra analysis. The correlation coefficient for the results from the LSC method and γ-spectrometry was 0.993 ± 0.058.

  15. Design and performance of A 3He-free coincidence counter based on parallel plate boron-lined proportional technology

    SciTech Connect

    Henzlova, D.; Menlove, H. O.; Marlow, J. B.

    2015-07-01

    Thermal neutron counters utilized and developed for deployment as non-destructive assay (NDA) instruments in the field of nuclear safeguards traditionally rely on 3He-based proportional counting systems. 3He-based proportional counters have provided core NDA detection capabilities for several decades and have proven to be extremely reliable with range of features highly desirable for nuclear facility deployment. Facing the current depletion of 3He gas supply and the continuing uncertainty of options for future resupply, a search for detection technologies that could provide feasible short-term alternative to 3He gas was initiated worldwide. As part of this effort, Los Alamos National Laboratory (LANL) designed and built a 3He-free full scale thermal neutron coincidence counter based on boron-lined proportional technology. The boronlined technology was selected in a comprehensive inter-comparison exercise based on its favorable performance against safeguards specific parameters. This paper provides an overview of the design and initial performance evaluation of the prototype High Level Neutron counter – Boron (HLNB). The initial results suggest that current HLNB design is capable to provide ~80% performance of a selected reference 3He-based coincidence counter (High Level Neutron Coincidence Counter, HLNCC). Similar samples are expected to be measurable in both systems, however, slightly longer measurement times may be anticipated for large samples in HLNB. The initial evaluation helped to identify potential for further performance improvements via additional tailoring of boron-layer thickness.

  16. Low-level gamma and neutron monitoring based on use of proportional counter filled with 3He in polythene moderator: study of the responses to gamma and neutrons.

    PubMed

    Pszona, S; Bantsar, A; Tulik, P; Wincel, K; Zaręba, B

    2014-10-01

    It has been shown that a proportional counter filled with (3)He placed centrally inside a polythene sphere opens a new possibility for measuring gamma photons and neutrons in the separate pulse-height windows. The responses to gamma and neutrons (in terms of ambient dose equivalent) of the detector assembly consisting of 203-mm polythene sphere with centrally positioned 40-mm diameter (3)He proportional counter have been studied. The response to secondary gammas from capture process in hydrogen has also been studied. The rather preliminary studies indicate that the proposed measuring system has very promising features as an ambient dose equivalent device for mixed gamma-neutron fields.

  17. An analytical comparison of gas gain in spherical, cylindrical and hemispherical low-pressure proportional counters intended for use in experimental microdosimetry

    NASA Astrophysics Data System (ADS)

    Broughton, David; Waker, Anthony J.

    2016-12-01

    Traditionally experimental microdosimetry has employed low pressure single cavity spherical Tissue Equivalent Proportional Counters (TEPCs). Multi-Element Tissue Equivalent Proportional Counters (METEPCs) with numerous cylindrical cavities have been constructed in order to increase sensitivity per unit volume; however existing METEPC designs are prohibitively complex and sensitive to motion and audible noise. This work proposes a novel hemispherical element with a wire-less anode ball as a solution to these issues. The gas gain characteristics of this hemispherical METEPC element were analyzed first for a single hemispherical TEPC to evaluate performance relative to current cylindrical and spherical counter designs that have been demonstrated experimentally to perform very well. This gain analysis evaluated relative avalanche size and the uniformity in maximum gain for electrons originating throughout the gas cavities of each of the three counters. Radial gas gain distributions for each counter were determined using both theoretical potential distributions as well as analytical equipotential distributions generated with ANSYS Maxwell (V. 14.0) to solve the Townsend equation. It was found that the hemispherical counter exhibits completely uniform gas gain for electrons approaching the anode from all directions and its avalanche region occupies only 3.5×10-3% of the entire gas cavity volume, whereas in the cylindrical and spherical counters the avalanche occupies 0.6% and 0.12% of the total respective gas cavity volumes. These analytical gas gain results are promising, suggesting that the hemisphere should exhibit uniform signal amplification throughout the gas cavity and if the recommended follow-up experimental work demonstrates the hemispherical counter works as anticipated it will be ready to be incorporated into an METEPC design.

  18. Energy-Dependent Scintillation Pulse Shape and Proportionality of Decay Components for CsI:Tl: Modeling with Transport and Rate Equations

    NASA Astrophysics Data System (ADS)

    Lu, X.; Gridin, S.; Williams, R. T.; Mayhugh, M. R.; Gektin, A.; Syntfeld-Kazuch, A.; Swiderski, L.; Moszynski, M.

    2017-01-01

    Relatively recent experiments on the scintillation response of CsI:Tl have found that there are three main decay times of about 730 ns, 3 μ s , and 16 μ s , i.e., one more principal decay component than had been previously reported; that the pulse shape depends on gamma-ray energy; and that the proportionality curves of each decay component are different, with the energy-dependent light yield of the 16 -μ s component appearing to be anticorrelated with that of the 0.73 -μ s component at room temperature. These observations can be explained by the described model of carrier transport and recombination in a particle track. This model takes into account processes of hot and thermalized carrier diffusion, electric-field transport, trapping, nonlinear quenching, and radiative recombination. With one parameter set, the model reproduces multiple observables of CsI:Tl scintillation response, including the pulse shape with rise and three decay components, its energy dependence, the approximate proportionality, and the main trends in proportionality of different decay components. The model offers insights on the spatial and temporal distributions of carriers and their reactions in the track.

  19. Performance and field tests of a handheld Compton camera using 3-D position-sensitive scintillators coupled to multi-pixel photon counter arrays

    NASA Astrophysics Data System (ADS)

    Kishimoto, A.; Kataoka, J.; Nishiyama, T.; Fujita, T.; Takeuchi, K.; Okochi, H.; Ogata, H.; Kuroshima, H.; Ohsuka, S.; Nakamura, S.; Hirayanagi, M.; Adachi, S.; Uchiyama, T.; Suzuki, H.

    2014-11-01

    After the nuclear disaster in Fukushima, radiation decontamination has become particularly urgent. To help identify radiation hotspots and ensure effective decontamination operation, we have developed a novel Compton camera based on Ce-doped Gd3Al2Ga3O12 scintillators and multi-pixel photon counter (MPPC) arrays. Even though its sensitivity is several times better than that of other cameras being tested in Fukushima, we introduce a depth-of-interaction (DOI) method to further improve the angular resolution. For gamma rays, the DOI information, in addition to 2-D position, is obtained by measuring the pulse-height ratio of the MPPC arrays coupled to ends of the scintillator. We present the detailed performance and results of various field tests conducted in Fukushima with the prototype 2-D and DOI Compton cameras. Moreover, we demonstrate stereo measurement of gamma rays that enables measurement of not only direction but also approximate distance to radioactive hotspots.

  20. Measurement and simulation of lineal energy distribution at the CERN high energy facility with a tissue equivalent proportional counter.

    PubMed

    Rollet, S; Autischer, M; Beck, P; Latocha, M

    2007-01-01

    The response of a tissue equivalent proportional counter (TEPC) in a mixed radiation field with a neutron energy distribution similar to the radiation field at commercial flight altitudes has been studied. The measurements have been done at the CERN-EU High-Energy Reference Field (CERF) facility where a well-characterised radiation field is available for intercomparison. The TEPC instrument used by the ARC Seibersdorf Research is filled with pure propane gas at low pressure and can be used to determine the lineal energy distribution of the energy deposition in a mass of gas equivalent to a 2 microm diameter volume of unit density tissue, of similar size to the nuclei of biological cells. The linearity of the detector response was checked both in term of dose and dose rate. The effect of dead-time has been corrected. The influence of the detector exposure location and orientation in the radiation field on the dose distribution was also studied as a function of the total dose. The microdosimetric distribution of the absorbed dose as a function of the lineal energy has been obtained and compared with the same distribution simulated with the FLUKA Monte Carlo transport code. The dose equivalent was calculated by folding this distribution with the quality factor as a function of linear energy transfer. The comparison between the measured and simulated distributions show that they are in good agreement. As a result of this study the detector is well characterised, thanks also to the numerical simulations the instrument response is well understood, and it's currently being used onboard the aircrafts to evaluate the dose to aircraft crew caused by cosmic radiation.

  1. Comparison of plastics used in tissue equivalent proportional counters (TEPC) and development of a balloon borne TEPC

    NASA Astrophysics Data System (ADS)

    Collums, Tyler L.

    This study investigates alternatives to A-150 tissue equivalent plastic for use in the construction of tissue equivalent gas-filled detectors for the measurement of dosimetric quantities. This study looks at four different alternative plastics: acrylic, Nylon, polyethylene, and polystyrene. These alternative materials are more readily available and easier to machine than A-150 tissue equivalent plastic. In this study they are compared to A-150 tissue equivalent plastic to determine how they compare in the measurement of lineal energy spectra from energetic protons and heavy ions as found in the space radiation environment, as well as at relevant clinical energies used in proton and heavy ion therapy. In experiments carried out at the ProCure proton therapy center in Oklahoma City, five proportional counters possessing ionization cavities constructed of five different materials (A-150 tissue equivalent plastic, acrylic, Nylon, polyethylene, and polystyrene) were used to measure the lineal energy spectra of energetic proton beams of 87 MeV, 162 MeV, and 222 MeV. Exposures to energetic heavy ions were carried out at HIMAC in Japan using beams of 143 MeV/amu He, 265 MeV/amu C, 440 MeV/amu Si, 430 MeV/amu Ar, and 421 MeV/amu Fe. Monte Carlo simulations using FLUKA were also done for each detector for each proton beam and each heavy ion beam. Comparison of the measured data obtained at ProCure and HIMAC, as well as simulation results using the Monte Carlo code FLUKA, indicate that the responses of the four alternative plastics tested are very similar to the response of A-150 tissue equivalent plastic. FLUKA simulations done for a detector made of ICRU muscle are also shown to have a response similar to that of all five plastics. A flight version of the TEPCs has also been developed for a high altitude flight on a balloon or other vehicle.

  2. First results of a simultaneous measurement of tritium and 14C in an ultra-low-background proportional counter for environmental sources of methane

    SciTech Connect

    Mace, Emily K.; Aalseth, Craig E.; Day, Anthony R.; Hoppe, Eric W.; Keillor, Martin E.; Moran, James J.; Panisko, Mark E.; Seifert, Allen; Tatishvili, Gocha; Williams, Richard M.

    2016-02-01

    Abstract Simultaneous measurement of tritium and 14C would provide an added tool for tracing organic compounds through environmental systems and is possible via beta energy spectroscopy of sample-derived methane in internal-source gas proportional counters. Since the mid-1960’s atmospheric tritium and 14C have fallen dramatically as the isotopic injections from above-ground nuclear testing have been diluted into the ocean and biosphere. In this work, the feasibility of simultaneous tritium and 14C measurements via proportional counters is revisited in light of significant changes in both the atmospheric and biosphere isotopics and the development of new ultra-low-background gas proportional counting capabilities for small samples (roughly 50 cc methane). A Geant4 Monte Carlo model of a Pacific Northwest National Laboratory (PNNL) proportional counter response to tritium and 14C is used to analyze small samples of two different methane sources to illustrate the range of applicability of contemporary simultaneous measurements and their limitations. Because the two methane sources examined were not sample size limited, we could compare the small-sample measurements performed at PNNL with analysis of larger samples performed at a commercial laboratory. The dual-isotope simultaneous measurement is well matched for methane samples that are atmospheric or have an elevated source of tritium (i.e. landfill gas). For samples with low/modern tritium isotopics (rainwater), commercial separation and counting is a better fit.

  3. First results of a simultaneous measurement of tritium and (14)C in an ultra-low-background proportional counter for environmental sources of methane.

    PubMed

    Mace, E K; Aalseth, C E; Day, A R; Hoppe, E W; Keillor, M E; Moran, J J; Panisko, M E; Seifert, A; Tatishvili, G; Williams, R M

    2016-05-01

    Simultaneous measurement of tritium and (14)C would provide an added tool for tracing organic compounds through environmental systems and is possible via beta energy spectroscopy of sample-derived methane in internal-source gas proportional counters. Since the mid-1960's atmospheric tritium and (14)C have fallen dramatically as the isotopic injections from aboveground nuclear testing have been diluted into the ocean and biosphere. In this work, the feasibility of simultaneous tritium and (14)C measurements via proportional counters is revisited in light of significant changes in both the atmospheric and biosphere isotopics and the development of new ultra-low-background gas proportional counting capabilities for small samples (roughly 50 cc methane). A Geant4 Monte Carlo model of a Pacific Northwest National Laboratory (PNNL) proportional counter response to tritium and (14)C is used to analyze small samples of two different methane sources to illustrate the range of applicability of contemporary simultaneous measurements and their limitations. Because the two methane sources examined were not sample size limited, we could compare the small-sample measurements performed at PNNL with analysis of larger samples performed at a commercial laboratory. These first results show that the dual-isotope simultaneous measurement is well matched for methane samples that are atmospheric or have an elevated source of tritium (i.e. landfill gas). However, for samples with low/modern tritium isotopics (rainwater), commercial separation and counting is a better fit.

  4. Tissue equivalent proportional counter microdosimetry measurements utililzed aboard aircraft and in accelerator based space radiation shielding studies

    NASA Astrophysics Data System (ADS)

    Gersey, Brad; Wilkins, Richard

    The space radiation environment presents a potential hazard to the humans, electronics and materials that are exposed to it. Particle accelerator facilities such as the NASA Space Ra-diation Laboratory (NSRL) and Loma Linda University Medical Center (LLUMC) provide particle radiation of specie and energy within the range of that found in the space radiation environment. Experiments performed at these facilities determine various endpoints for bio-logical, electronic and materials exposures. A critical factor in the performance of rigorous scientific studies of this type is accurate dosimetric measurements of the exposures. A Tissue Equivalent Proportional Counter (TEPC) is a microdosimeter that may be used to measure absorbed dose, average quality factor (Q) and dose equivalent of the particle beam utilized in these experiments. In this work, results from a variety of space radiation shielding studies where a TEPC was used to perform dosimetry in the particle beam will be presented. These results compare the absorbed dose and dose equivalent measured downstream of equal density thicknesses of stan-dard and multifunctional shielding materials. The standard materials chosen for these shielding studies included High-Density Polyethylene (HDPE) and aluminum alloy, while the multifunc-tional materials included carbon composite infused with single walled carbon nanotubes. High energy particles including proton, silicon and iron nuclei were chosen as the incident radia-tion for these studies. Further, TEPC results from measurements taken during flights aboard ER-2 and KC-135 aircraft will also be discussed. Results from these flight studies include TEPC measurements for shielded and unshielded conditions as well as the effect of vibration and electromagnetic exposures on the TEPC operation. The data selected for presentation will highlight the utility of the TEPC in space radiation studies, and in shielding studies in particular. The lineal energy response function of the

  5. Study of microdosimetric energy deposition patterns in tissue-equivalent medium due to low-energy neutron fields using a graphite-walled proportional counter.

    PubMed

    Waker, A J; Aslam

    2011-06-01

    To improve radiation protection dosimetry for low-energy neutron fields encountered in nuclear power reactor environments, there is increasing interest in modeling neutron energy deposition in metrological instruments such as tissue-equivalent proportional counters (TEPCs). Along with these computational developments, there is also a need for experimental data with which to benchmark and test the results obtained from the modeling methods developed. The experimental work described in this paper is a study of the energy deposition in tissue-equivalent (TE) medium using an in-house built graphite-walled proportional counter (GPC) filled with TE gas. The GPC is a simple model of a standard TEPC because the response of the counter at these energies is almost entirely due to the neutron interactions in the sensitive volume of the counter. Energy deposition in tissue spheres of diameter 1, 2, 4 and 8 µm was measured in low-energy neutron fields below 500 keV. We have observed a continuously increasing trend in microdosimetric averages with an increase in neutron energy. The values of these averages decrease as we increase the simulated diameter at a given neutron energy. A similar trend for these microdosimetric averages has been observed for standard TEPCs and the Rossi-type, TE, spherical wall-less counter filled with propane-based TE gas in the same energy range. This implies that at the microdosimetric level, in the neutron energy range we employed in this study, the pattern of average energy deposited by starter and insider proton recoil events in the gas is similar to those generated cumulatively by crosser and stopper events originating from the counter wall plus starter and insider recoil events originating in the sensitive volume of a TEPC.

  6. Measurement of lineal-energy distributions for neutrons of 8 keV to 65 MeV by using a tissue-equivalent proportional counter.

    PubMed

    Nunomiya, T; Kim, E; Kurosaw, T; Taniguchi, S; Nakamura, T; Nakane, Y; Sakamoto, Y; Tanaka, S

    2002-01-01

    The lineal-energy spectra for monoenergetic and quasi-monoenergetic neutrons of 8 keV to 65 MeV were obtained using a tissue-equivalent proportional counter (TEPC). The frequency-mean lineal energy, the dose-average lineal energy and mean quality factor were estimated from the measured data. The neutron absorbed doses obtained with this TEPC were compared with the kerma coefticient for A-150 plastic defined by ICRP 26 and the mean quality factors were compared with the data of ICRP 74. respectively. These comparisons indicated good agreement between them.

  7. Einstein Observatory SSS and MPC observations of the complex X-ray spectra of Seyfert galaxies. [Solid State Spectrometer and Monitor Proportional Counter

    NASA Technical Reports Server (NTRS)

    Turner, T. J.; Weaver, K. A.; Mushotzky, R. F.; Holt, S. S.; Madejski, G. M.

    1991-01-01

    The X-ray spectra of 25 Seyfert galaxies measured with the Solid State Spectrometer on the Einstein Observatory have been investigated. This new investigation utilizes simultaneous data from the Monitor Proportional Counter, and automatic correction for systematic effects in the Solid State Spectrometer which were previously handled subjectively. It is found that the best-fit single-power-law indices generally agree with those previously reported, but that soft excesses of some form are inferred for about 48 percent of the sources. One possible explanation of the soft excess emission is a blend of soft X-ray lines, centered around 0.8 keV. The implications of these results for accretion disk models are discussed.

  8. Comparisons of LET distributions measured in low-earth orbit using tissue-equivalent proportional counters and the position-sensitive silicon-detector telescope (RRMD-III).

    PubMed

    Doke, T; Hayashi, T; Borak, T B

    2001-09-01

    Determinations of the LET distribution, phi(L), of charged particles within a spacecraft in low-Earth orbit have been made. One method used a cylindrical tissue-equivalent proportional counter (TEPC), with the assumption that for each measured event, lineal energy, y, is equal to LET and thus phi(L) = phi(y). The other was based on the direct measurement of LETs for individual particles using a charged-particle telescope consisting of position-sensitive silicon detectors called RRMD-III. There were differences of up to a factor of 10 between estimates of phi(L) using the two methods on the same mission. This caused estimates of quality factor to vary by a factor of two between the two methods.

  9. Joint observations of 4U1223-62 by the SAS-3 satellite and Columbia University proportional counter experiment on NASA rocket 26.054 UH

    NASA Technical Reports Server (NTRS)

    Novick, R.; Wolff, R. S.

    1978-01-01

    The pulsating X-ray binary 4U1223-62 and Vela X-1 were observed by Aerobee rocket-borne proportional counters. Valid X-ray events were telemetered and analyzed for possible flaring, quasiperiodic, and periodic pulsations, and for other nonstatistical behavior in the source. Both fast Fourier transform and autocorrelation programs were used. For several hours four days before and after the rocket flight, the SAS-3 satellite scanned the galactic plane in order to identify X-ray sources in the vicinity of 4U1223-62 and their intensities, and to provide positional accuracy of 0.25 for sources with intensity greater than 10% of the target. Observations of the source near the main peak of its pulsating period as defined by SAS-3 are discussed. There is no evidence of a spectral feature although twice as many photons were received as than from Vela X-1.

  10. Independent measurement of the total active 8B solar neutrino flux using an array of 3He proportional counters at the Sudbury Neutrino Observatory.

    PubMed

    Aharmim, B; Ahmed, S N; Amsbaugh, J F; Anthony, A E; Banar, J; Barros, N; Beier, E W; Bellerive, A; Beltran, B; Bergevin, M; Biller, S D; Boudjemline, K; Boulay, M G; Bowles, T J; Browne, M C; Bullard, T V; Burritt, T H; Cai, B; Chan, Y D; Chauhan, D; Chen, M; Cleveland, B T; Cox-Mobrand, G A; Currat, C A; Dai, X; Deng, H; Detwiler, J; DiMarco, M; Doe, P J; Doucas, G; Drouin, P-L; Duba, C A; Duncan, F A; Dunford, M; Earle, E D; Elliott, S R; Evans, H C; Ewan, G T; Farine, J; Fergani, H; Fleurot, F; Ford, R J; Formaggio, J A; Fowler, M M; Gagnon, N; Germani, J V; Goldschmidt, A; Goon, J T M; Graham, K; Guillian, E; Habib, S; Hahn, R L; Hallin, A L; Hallman, E D; Hamian, A A; Harper, G C; Harvey, P J; Hazama, R; Heeger, K M; Heintzelman, W J; Heise, J; Helmer, R L; Henning, R; Hime, A; Howard, C; Howe, M A; Huang, M; Jagam, P; Jamieson, B; Jelley, N A; Keeter, K J; Klein, J R; Kormos, L L; Kos, M; Krüger, A; Kraus, C; Krauss, C B; Kutter, T; Kyba, C C M; Lange, R; Law, J; Lawson, I T; Lesko, K T; Leslie, J R; Loach, J C; MacLellan, R; Majerus, S; Mak, H B; Maneira, J; Martin, R; McBryde, K; McCauley, N; McDonald, A B; McGee, S; Mifflin, C; Miller, G G; Miller, M L; Monreal, B; Monroe, J; Morissette, B; Myers, A; Nickel, B G; Noble, A J; Oblath, N S; O'Keeffe, H M; Ollerhead, R W; Gann, G D Orebi; Oser, S M; Ott, R A; Peeters, S J M; Poon, A W P; Prior, G; Reitzner, S D; Rielage, K; Robertson, B C; Robertson, R G H; Rollin, E; Schwendener, M H; Secrest, J A; Seibert, S R; Simard, O; Simpson, J J; Sinclair, L; Skensved, P; Smith, M W E; Steiger, T D; Stonehill, L C; Tesić, G; Thornewell, P M; Tolich, N; Tsui, T; Tunnell, C D; Van Wechel, T; Van Berg, R; VanDevender, B A; Virtue, C J; Walker, T J; Wall, B L; Waller, D; Tseung, H Wan Chan; Wendland, J; West, N; Wilhelmy, J B; Wilkerson, J F; Wilson, J R; Wouters, J M; Wright, A; Yeh, M; Zhang, F; Zuber, K

    2008-09-12

    The Sudbury Neutrino Observatory (SNO) used an array of 3He proportional counters to measure the rate of neutral-current interactions in heavy water and precisely determined the total active (nu_x) 8B solar neutrino flux. This technique is independent of previous methods employed by SNO. The total flux is found to be 5.54_-0.31;+0.33(stat)-0.34+0.36(syst)x10(6) cm(-2) s(-1), in agreement with previous measurements and standard solar models. A global analysis of solar and reactor neutrino results yields Deltam2=7.59_-0.21;+0.19x10(-5) eV2 and theta=34.4_-1.2;+1.3 degrees. The uncertainty on the mixing angle has been reduced from SNO's previous results.

  11. Proton recoil scintillator neutron rem meter

    DOEpatents

    Olsher, Richard H.; Seagraves, David T.

    2003-01-01

    A neutron rem meter utilizing proton recoil and thermal neutron scintillators to provide neutron detection and dose measurement. In using both fast scintillators and a thermal neutron scintillator the meter provides a wide range of sensitivity, uniform directional response, and uniform dose response. The scintillators output light to a photomultiplier tube that produces an electrical signal to an external neutron counter.

  12. Preliminary development of a wall-less gas-flow proportional counter for in-situ field analysis of nuclear contamination in soil

    SciTech Connect

    Bush, S.P.; Hamby, D.M.; Martin, J.E.

    1997-03-01

    This study resulted in the design, construction and testing of a gas flow proportional counter for in-situ determination of soil contamination. The uniqueness of this detector is the screened material used for the cathode. A Pu-239 source of 0.006 {micro}Ci was mounted to the outside of the cathode to simulate radioactive soil. The detector probe was placed into a laboratory mock-up and tested to determine operating voltage, efficiency and energy resolution. Two gas flow proportional counters were built and tested. The detectors are cylindrical, each with a radius of 1.905 cm, having an anode wire with a radius of 0.0038 cm. The length of the smaller detector S anode was 2.54 cm, and the length of the larger detector S anode was 7.64 cm. Therefore, the active volumes were 28.96 cm{sup 3} and 87.10 cm{sup 3}, respectively, for the small and large detector. An operating voltage of 1975 volts was determined to be sufficient for both detectors. The average efficiency was 2.59 {+-} 0.12% and 76.71 {+-} 10.81% for the small volume and large volume detectors, respectively. The average energy resolution for the low-energy peak of the small detector was 4.24 {+-} 1.28% and for the large-energy peak was 1.37 {+-} 0.66%. The large detectors energy resolution was 17.75 {+-} 3.74%. The smaller detector, with better energy resolution, exhibited a bi-modal spectrum, whereas the larger detector S spectrum centered around a single broad peak.

  13. A Scintillation Counter System Design To Detect Antiproton Annihilation using the High Performance Antiproton Trap(HiPAT)

    NASA Technical Reports Server (NTRS)

    Martin, James J.; Lewis, Raymond A.; Stanojev, Boris

    2003-01-01

    The High Performance Antiproton Trap (HiPAT), a system designed to hold up to l0(exp 12) charge particles with a storage half-life of approximately 18 days, is a tool to support basic antimatter research. NASA's interest stems from the energy density represented by the annihilation of matter with antimatter, 10(exp 2)MJ/g. The HiPAT is configured with a Penning-Malmberg style electromagnetic confinement region with field strengths up to 4 Tesla, and 20kV. To date a series of normal matter experiments, using positive and negative ions, have been performed evaluating the designs performance prior to operations with antiprotons. The primary methods of detecting and monitoring stored normal matter ions and antiprotons within the trap includes a destructive extraction technique that makes use of a micro channel plate (MCP) device and a non-destractive radio frequency scheme tuned to key particle frequencies. However, an independent means of detecting stored antiprotons is possible by making use of the actual annihilation products as a unique indicator. The immediate yield of the annihilation event includes photons and pie mesons, emanating spherically from the point of annihilation. To "count" these events, a hardware system of scintillators, discriminators, coincident meters and multi channel scalars (MCS) have been configured to surround much of the HiPAT. Signal coincidence with voting logic is an essential part of this system, necessary to weed out the single cosmic ray events from the multi-particle annihilation shower. This system can be operated in a variety of modes accommodating various conditions. The first is a low-speed sampling interval that monitors the background loss or "evaporation" rate of antiprotons held in the trap during long storage periods; provides an independent method of validating particle lifetimes. The second is a high-speed sample rate accumulating information on a microseconds time-scale; useful when trapped antiparticles are extracted

  14. Experimental and computational results on exciton/free-carrier ratio, hot/thermalized carrier diffusion, and linear/nonlinear rate constants affecting scintillator proportionality

    SciTech Connect

    Williams, Richard; Grim, Joel; Li, Qi; Ucer, K. B.; Bizarri, G. A.; Kerisit, Sebastien N.; Gao, Fei; Bhattacharya, Pijush; Tupitsyn, Eugene; Rowe, Emmanuel; Buliga, Vladimir M.; Burger, Arnold

    2013-10-01

    Models of nonproportional response in scintillators have highlighted the importance of parameters such as branching ratios, carrier thermalization times, diffusion, kinetic order of quenching, associated rate constants, and radius of the electron track. For example, the fraction ηeh of excitations that are free carriers versus excitons was shown by Payne and coworkers to have strong correlation with the shape of electron energy response curves from Compton-coincidence studies. Rate constants for nonlinear quenching are implicit in almost all models of nonproportionality, and some assumption about track radius must invariably be made if one is to relate linear energy deposition dE/dx to volume-based excitation density n (eh/cm3) in terms of which the rates are defined. Diffusion, affecting time-dependent track radius and thus density of excitations, has been implicated as an important factor in nonlinear light yield. Several groups have recently highlighted diffusion of hot electrons in addition to thermalized carriers and excitons in scintillators. However, experimental determination of many of these parameters in the insulating crystals used as scintillators has seemed difficult. Subpicosecond laser techniques including interband z scan light yield, fluence-dependent decay time, and transient optical absorption are now yielding experimental values for some of the missing rates and ratios needed for modeling scintillator response. First principles calculations and Monte Carlo simulations can fill in additional parameters still unavailable from experiment. As a result, quantitative modeling of scintillator electron energy response from independently determined material parameters is becoming possible on an increasingly firmer data base. This paper describes recent laser experiments, calculations, and numerical modeling of scintillator response.

  15. Experimental and computational results on exciton/free-carrier ratio, hot/thermalized carrier diffusion, and linear/nonlinear rate constants affecting scintillator proportionality

    SciTech Connect

    Williams, R. T.; Grim, Joel Q.; Li, Qi; Ucer, K. B.; Bizarri, G. A.; Kerisit, S.; Gao, Fei; Bhattacharya, P.; Tupitsyn, E.; Rowe, E.; Buliga, V. M.; Burger, A.

    2013-09-26

    Models of nonproportional response in scintillators have highlighted the importance of parameters such as branching ratios, carrier thermalization times, diffusion, kinetic order of quenching, associated rate constants, and radius of the electron track. For example, the fraction ηeh of excitations that are free carriers versus excitons was shown by Payne and coworkers to have strong correlation with the shape of electron energy response curves from Compton-coincidence studies. Rate constants for nonlinear quenching are implicit in almost all models of nonproportionality, and some assumption about track radius must invariably be made if one is to relate linear energy deposition dE/dx to volume-based excitation density n (eh/cm3) in terms of which the rates are defined. Diffusion, affecting time-dependent track radius and thus density of excitations, has been implicated as an important factor in nonlinear light yield. Several groups have recently highlighted diffusion of hot electrons in addition to thermalized carriers and excitons in scintillators. However, experimental determination of many of these parameters in the insulating crystals used as scintillators has seemed difficult. Subpicosecond laser techniques including interband z scan light yield, fluence-dependent decay time, and transient optical absorption are now yielding experimental values for some of the missing rates and ratios needed for modeling scintillator response. First principles calculations and Monte Carlo simulations can fill in additional parameters still unavailable from experiment. As a result, quantitative modeling of scintillator electron energy response from independently determined material parameters is becoming possible on an increasingly firmer data base. This study describes recent laser experiments, calculations, and numerical modeling of scintillator response.

  16. Experimental and computational results on exciton/free-carrier ratio, hot/thermalized carrier diffusion, and linear/nonlinear rate constants affecting scintillator proportionality

    DOE PAGES

    Williams, R. T.; Grim, Joel Q.; Li, Qi; ...

    2013-09-26

    Models of nonproportional response in scintillators have highlighted the importance of parameters such as branching ratios, carrier thermalization times, diffusion, kinetic order of quenching, associated rate constants, and radius of the electron track. For example, the fraction ηeh of excitations that are free carriers versus excitons was shown by Payne and coworkers to have strong correlation with the shape of electron energy response curves from Compton-coincidence studies. Rate constants for nonlinear quenching are implicit in almost all models of nonproportionality, and some assumption about track radius must invariably be made if one is to relate linear energy deposition dE/dx tomore » volume-based excitation density n (eh/cm3) in terms of which the rates are defined. Diffusion, affecting time-dependent track radius and thus density of excitations, has been implicated as an important factor in nonlinear light yield. Several groups have recently highlighted diffusion of hot electrons in addition to thermalized carriers and excitons in scintillators. However, experimental determination of many of these parameters in the insulating crystals used as scintillators has seemed difficult. Subpicosecond laser techniques including interband z scan light yield, fluence-dependent decay time, and transient optical absorption are now yielding experimental values for some of the missing rates and ratios needed for modeling scintillator response. First principles calculations and Monte Carlo simulations can fill in additional parameters still unavailable from experiment. As a result, quantitative modeling of scintillator electron energy response from independently determined material parameters is becoming possible on an increasingly firmer data base. This study describes recent laser experiments, calculations, and numerical modeling of scintillator response.« less

  17. Radiation Counters

    DOEpatents

    Simpson, Jr, J A

    1950-01-31

    Geiger-Mueller and proportional counters operating at low potentials (about 125-300 v) obtained by utilizing certain ratios of diameters of the electrodes and particular mixtures of noble gases as the ionizing medium are covered in this application.

  18. The response of a spherical tissue-equivalent proportional counter to iron particles from 200-1000 MeV/nucleon

    NASA Technical Reports Server (NTRS)

    Gersey, B. B.; Borak, T. B.; Guetersloh, S. B.; Zeitlin, C.; Miller, J.; Heilbronn, L.; Murakami, T.; Iwata, Y.; Chatterjee, A. (Principal Investigator)

    2002-01-01

    The radiation environment on board the space shuttle and the International Space Station includes high-Z and high-energy (HZE) particles that are part of the galactic cosmic radiation (GCR) spectrum. Iron-56 particles are considered to be one of the most biologically important parts of the GCR spectrum. Tissue-equivalent proportional counters (TEPCs) are used as active dosimeters on manned space flights. These TEPCs are further used to determine the average quality factor for each space mission. A TEPC simulating a 1-microm-diameter sphere of tissue was exposed as part of a particle spectrometer to (56)Fe particles at energies from 200-1000 MeV/nucleon. The response of TEPCs in terms of mean lineal energy, y(F), and dose mean lineal energy, y(D), as well as the energy deposited at different impact parameters through the detector was determined for six different incident energies of (56)Fe particles in this energy range. Calculations determined that charged-particle equilibrium was achieved for each of the six experiments. Energy depositions at different impact parameters were calculated using a radial dose distribution model, and the results were compared to experimental data.

  19. The response of a spherical tissue-equivalent proportional counter to 56-Fe particles from 200-1000 MeV/nucleon

    SciTech Connect

    Gersey, Bradford B.; Borak, Thomas B.; Guetersloh, Stephen B.; Zeitlin, Cary J.; Miller, J.; Heilbronn, L.; Murakami, T.; Iwata, Y.

    2001-09-04

    The radiation environment aboard the space shuttle and the International Space Station includes high-Z and high-energy (HZE) particles that are part of the galactic cosmic radiation (GCR) spectrum. Iron-56 is considered to be one of the most biologically important parts of the GCR spectrum. Tissue-equivalent proportional counters (TEPC) are used as active dosimeters on manned space flights. These TEPC's are further used to determine average quality factor for each space mission. A TEPC simulating a 1 micron diameter sphere of tissue was exposed as part of a particle spectrometer to iron-56 at energies from 200-1000 MeV/nucleon. The response of TEPC in terms of frequency-averaged lineal energy, dose-averaged lineal energy, as well as energy deposited at different impact parameters through detector was determined for six different incident energies of iron-56 in this energy range. Calculations determined that charged particle equilibrium was achieved for each of the six experiments. Energy depositions at different impact parameters were calculated using a radial dose distribution model and the results compared to experimental data.

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

    SciTech Connect

    SNO Colla

    2008-06-05

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

  1. Independent Measurement of the Total Active {sup 8}B Solar Neutrino Flux Using an Array of {sup 3}He Proportional Counters at the Sudbury Neutrino Observatory

    SciTech Connect

    Aharmim, B.; Chauhan, D.; Farine, J.; Fleurot, F.; Hallman, E. D.; Krueger, A.; Schwendener, M. H.; Virtue, C. J.; Ahmed, S. N.; Cai, B.; Chen, M.; DiMarco, M.; Earle, E. D.; Evans, H. C.; Ewan, G. T.; Guillian, E.; Harvey, P. J.; Keeter, K. J.; Kormos, L. L.; Kos, M.

    2008-09-12

    The Sudbury Neutrino Observatory (SNO) used an array of {sup 3}He proportional counters to measure the rate of neutral-current interactions in heavy water and precisely determined the total active ({nu}{sub x}) {sup 8}B solar neutrino flux. This technique is independent of previous methods employed by SNO. The total flux is found to be 5.54{sub -0.31}{sup +0.33}(stat){sub -0.34}{sup +0.36}(syst)x10{sup 6} cm{sup -2} s{sup -1}, in agreement with previous measurements and standard solar models. A global analysis of solar and reactor neutrino results yields {delta}m{sup 2}=7.59{sub -0.21}{sup +0.19}x10{sup -5} eV{sup 2} and {theta}=34.4{sub -1.2}{sup +1.3} degrees. The uncertainty on the mixing angle has been reduced from SNO's previous results.

  2. Results of time-resolved radiation exposure measurements made during U.S. shuttle missions with a tissue equivalent proportional counter

    NASA Astrophysics Data System (ADS)

    Golightly, M. J.; Hardy, A. C.; Hardy, K.

    1994-10-01

    Time resolved exposure measurements inside the crew compartment have been made during recent shuttle missions with the USAF Radiation Monitoring Equipment-III (RME-III), a portable four-channel tissue equivalent proportional counter. Results from the first six missions are presented and discussed. The missions had orbital inclinations ranging from 28 degrees to 57 degrees, and altitudes from 200-600km. Dose equivalent rates ranged from 40-5300 micro Sv/dy. The RME-III measurements are in good agreement with other dosimetry measurements made aboard the vehicle. Measurements indicate that medium- and high- Linear Energy Transfer (LET) particles contribute less than 2% of the particle fluence for all missions, but up to 50% of the dose equivalent, depending on the spacecraft's altitude and orbital inclination. Isa-dose rate contours have been developed from measurements made during the ST-28 mission. The drift rate of the South Atlantic Anomaly (SAA) is estimated to be 0.49 degrees W/yr and 0.12 degrees N/yr. The calculated trapped proton and Galactic Cosmic Radiation (GCR) dose for the STS-28 mission were significantly lower than the measured values.

  3. Results of time-resolved radiation exposure measurements made during U.S. shuttle missions with a tissue equivalent proportional counter

    NASA Technical Reports Server (NTRS)

    Golightly, M. J.; Hardy, A. C.; Hardy, K.

    1994-01-01

    Time resolved exposure measurements inside the crew compartment have been made during recent shuttle missions with the USAF Radiation Monitoring Equipment-III (RME-III), a portable four-channel tissue equivalent proportional counter. Results from the first six missions are presented and discussed. The missions had orbital inclinations ranging from 28 degrees to 57 degrees, and altitudes from 200-600km. Dose equivalent rates ranged from 40-5300 micro Sv/dy. The RME-III measurements are in good agreement with other dosimetry measurements made aboard the vehicle. Measurements indicate that medium- and high- Linear Energy Transfer (LET) particles contribute less than 2% of the particle fluence for all missions, but up to 50% of the dose equivalent, depending on the spacecraft's altitude and orbital inclination. Isa-dose rate contours have been developed from measurements made during the ST-28 mission. The drift rate of the South Atlantic Anomaly (SAA) is estimated to be 0.49 degrees W/yr and 0.12 degrees N/yr. The calculated trapped proton and Galactic Cosmic Radiation (GCR) dose for the STS-28 mission were significantly lower than the measured values.

  4. Results of time-resolved radiation exposure measurements made during U.S. Shuttle missions with a tissue equivalent proportional counter.

    PubMed

    Golightly, M J; Hardy, A C; Hardy, K

    1994-10-01

    Time-resolved radiation exposure measurements inside the crew compartment have been made during recent Shuttle missions with the USAF Radiation Monitoring Equipment-III (RME-III), a portable four-channel tissue equivalent proportional counter. Results from the first six missions are presented and discussed. The missions had orbital inclinations ranging from 28.5 degrees to 57 degrees, and altitudes from 200-600 km. Dose equivalent rates ranged from 40-5300 micro Sv/dy. The RME-III measurements are in good agreement with other dosimetry measurements made aboard the vehicle. Measurements indicate that medium- and high-LET particles contribute less than 2% of the particle fluence for all missions, but up to 50% of the dose equivalent, depending on the spacecraft's altitude and orbital inclination. Iso-dose rate contours have been developed from measurements made during the STS-28 mission. The drift rate of the South Atlantic Anomaly (SAA) is estimated to be 0.49 degrees W/yr and 0.12 degrees N/yr. The calculated trapped proton and Galactic Cosmic Radiation (GCR) dose for the STS-28 mission were significantly lower than the measured values.

  5. Nuclear Science Symposium, 21st, Scintillation and Semiconductor Counter Symposium, 14th, and Nuclear Power Systems Symposium, 6th, Washington, D.C., December 11-13, 1974, Proceedings

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Papers are presented dealing with latest advances in the design of scintillation counters, semiconductor radiation detectors, gas and position sensitive radiation detectors, and the application of these detectors in biomedicine, satellite instrumentation, and environmental and reactor instrumentation. Some of the topics covered include entopistic scintillators, neutron spectrometry by diamond detector for nuclear radiation, the spherical drift chamber for X-ray imaging applications, CdTe detectors in radioimmunoassay analysis, CAMAC and NIM systems in the space program, a closed loop threshold calibrator for pulse height discriminators, an oriented graphite X-ray diffraction telescope, design of a continuous digital-output environmental radon monitor, and the optimization of nanosecond fission ion chambers for reactor physics. Individual items are announced in this issue.

  6. Scintillating pad detectors

    SciTech Connect

    Adams, D.; Baumbaugh, B.; Borcherding, F.

    1996-12-31

    We have been investigating the performance of scintillating pad detectors, individual small tiles of scintillator that are read out with wavelength-shifting fibers and visible light photon counters, for application in high luminosity colliding beam experiments such as the D0 Upgrade. Such structures could provide {open_quotes}pixel{close_quotes} type readout over large fiducial volumes for tracking, preshower detection and triggering.

  7. A study of neutron radiation quality with a tissue-equivalent proportional counter for a low-energy accelerator-based in vivo neutron activation facility.

    PubMed

    Aslam; Waker, A J

    2011-02-01

    The accelerator-based in vivo neutron activation facility at McMaster University has been used successfully for the measurement of several minor and trace elements in human hand bones due to their importance to health. Most of these in vivo measurements have been conducted at a proton beam energy (E(p)) of 2.00 MeV to optimise the activation of the selected element of interest with an effective dose of the same order as that received in chest X rays. However, measurement of other elements at the same facility requires beam energies other than 2.00 MeV. The range of energy of neutrons produced at these proton beam energies comes under the region where tissue-equivalent proportional counters (TEPCs) are known to experience difficulty in assessing the quality factor and dose equivalent. In this study, the response of TEPCs was investigated to determine the quality factor of neutron fields generated via the (7)Li(p, n)(7)Be reaction as a function of E(p) in the range 1.884-2.56 MeV at the position of hand irradiation in the facility. An interesting trend has been observed in the quality factor based on ICRP 60, Q(ICRP60), such that the maximum value was observed at E(p)=1.884 MeV (E(n)=33±16 keV) and then continued to decline with increasing E(p) until achieving a minimum value at E(p)=2.0 MeV despite a continuous increase in the mean neutron energy with E(p). This observation is contrary to what has been observed with direct fast neutrons where the quality factor was found to increase continuously with an increase in E(p) (i.e. increasing E(n)). The series of measurements conducted with thermal and fast neutron fields demonstrate that the (14)N(n, p)(14)C produced 580 keV protons in the detector play an important role in the response of the counter under 2.0 MeV proton energy (E(n) ≤ 250 keV). In contrast to the lower response of TEPCs to low-energy neutrons, the quality factor is overestimated in the range 1-2 depending on beam energy <2.0 MeV. This study provides

  8. Study of the effect of high dose rate on tissue equivalent proportional counter microdosimetric measurements in mixed photon and neutron fields

    NASA Astrophysics Data System (ADS)

    Aslam; Qashua, N.; Waker, A. J.

    2011-10-01

    This study describes the measurement of lineal energy spectra carried out with a 5.1 cm (2 in.) diameter spherical tissue equivalent proportional counter (TEPC) simulating 2 μm tissue equivalent (TE) site diameter in low energy mixed photon-neutron fields with varying dose rates generated by employing the McMaster University 1.25 MV double stage Tandetron accelerator. The 7Li (p, n) 7Be reaction was employed to generate a variety of mixed fields of photons and low energy neutrons using proton beam energy ranging 1.89-2.56 MeV. The dose rate at a given beam energy was varied by changing the beam current. Dose rates that resulted in dead times as high as 75% were employed to study the effect of dose rate on quality, microdosimetric averages ( y¯F and y¯D), absorbed dose and dose equivalent. We have observed that high dose rates due to both photons and neutrons in a mixed field of radiation result in pile up of pulses and distort the lineal energy spectrum measured under these conditions. The pile up effect and hence the distortion in the lineal energy spectrum becomes prominent with dose rates, which result in dead times larger than 25% for the high linear energy transfer (LET) radiation component. Intense neutron fields, which may amount to 75% dead time, could result in a 50% or even larger increase in the values of the microsdosimetric averages and the neutron quality factor. This study demonstrates moderate dose rates that do not result in dead times of more than 20-25% due to either of the component radiation or due to both components of mixed field radiation generate results that are acceptable for radiation monitoring.

  9. The design of the TASD (totally active scintillator detector) prototype

    SciTech Connect

    Mefodiev, A. V. Kudenko, Yu. G.

    2015-12-15

    Totally active and magnetic segmented scintillation neutrino detectors are developed for the nextgeneration accelerator neutrino experiments. Such detectors will incorporate scintillation modules with scintillation counters that form X and Y planes. A single counter is a 7 × 10 × 90 mm{sup 3} scintillation bar with gluedin wavelength-shifting fibers and micropixel avalanche photodiodes. The results of measurements of the parameters of these detectors are presented.

  10. Development of a System for Survey of Radon Concentration of the Dayton Area Using a Liquid Scintillation Counter and Analysis of the Data

    DTIC Science & Technology

    1992-03-01

    conversion, a calibration factor, an elution time constant, and adsorption time constant were calculated . The procedure for handling the vials...the vials were done on Packard Tri- Carb 2200CA Liquid Scintillation Analyzer. To calculate radon concentration in pCi/l from net counts per minute...started to set up a system for a large scale survey of radon concentration. He used one of Sharp’s protocol for calculating the radon concentration. Using

  11. Nuclear Science Symposium, 23rd, Scintillation and Semiconductor Counter Symposium, 15th, and Nuclear Power Systems Symposium, 8th, New Orleans, La., October 20-22, 1976, Proceedings

    NASA Technical Reports Server (NTRS)

    Wagner, L. J.

    1977-01-01

    The volume includes papers on semiconductor radiation detectors of various types, components of radiation detection and dosimetric systems, digital and microprocessor equipment in nuclear industry and science, and a wide variety of applications of nuclear radiation detectors. Semiconductor detectors of X-rays, gamma radiation, heavy ions, neutrons, and other nuclear particles, plastic scintillator arrays, drift chambers, spark wire chambers, and radiation dosimeter systems are reported on. Digital and analog conversion systems, digital data and control systems, microprocessors, and their uses in scientific research and nuclear power plants are discussed. Large-area imaging and biomedical nucleonic instrumentation, nuclear power plant safeguards, reactor instrumentation, nuclear power plant instrumentation, space instrumentation, and environmental instrumentation are dealt with. Individual items are announced in this issue.

  12. Comparisons of LET Distributions for Protons with Energies between50 and 200 MeV Determined Using a Spherical Tissue-EquivalentProportional Counter (TEPC) and a Position-Sensitive Silicon Spectrometer(RRMD-III)

    SciTech Connect

    Borak, Thomas B.; Doke, Tadayoshi; Fuse, T.; Guetersloh, StephenB.; Heilbronn, Lawrence H.; Hara, K.; Moyers, Michael; Suzuki, S.; Taddei, Phillip; Terasawa, K.; Zeitlin, Cary J.

    2004-12-01

    Experiments have been performed to measure the response of a spherical tissue-equivalent proportional counter (TEPC) and a silicon-based LET spectrometer (RRMD-III) to protons with energies ranging from 50 200 MeV. This represents a large portion of the energy distribution for trapped protons encountered by astronauts in low-Earth orbit. The beam energies were obtained using plastic polycarbonate degraders with a monoenergetic beam that was extracted from a proton synchrotron. The LET spectrometer provided excellent agreement with the expected LET distribution emerging from the energy degraders. The TEPC cannot measure the LET distribution directly. However, the frequency mean value of lineal energy, y bar f, provided a good approximation to LET. This is in contrast to previous results for high-energy heavy ions wherey barf underestimated LET, whereas the dose-averaged lineal energy, y barD, provided a good approximation to LET.

  13. Scintillator material

    DOEpatents

    Anderson, D.F.; Kross, B.J.

    1992-07-28

    An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography. 4 figs.

  14. Scintillator material

    DOEpatents

    Anderson, David F.; Kross, Brian J.

    1994-01-01

    An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography.

  15. Scintillator material

    DOEpatents

    Anderson, David F.; Kross, Brian J.

    1992-01-01

    An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography.

  16. Scintillator material

    DOEpatents

    Anderson, D.F.; Kross, B.J.

    1994-06-07

    An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography. 4 figs.

  17. AUTOMATIC COUNTER

    DOEpatents

    Robinson, H.P.

    1960-06-01

    An automatic counter of alpha particle tracks recorded by a sensitive emulsion of a photographic plate is described. The counter includes a source of mcdulated dark-field illumination for developing light flashes from the recorded particle tracks as the photographic plate is automatically scanned in narrow strips. Photoelectric means convert the light flashes to proportional current pulses for application to an electronic counting circuit. Photoelectric means are further provided for developing a phase reference signal from the photographic plate in such a manner that signals arising from particle tracks not parallel to the edge of the plate are out of phase with the reference signal. The counting circuit includes provision for rejecting the out-of-phase signals resulting from unoriented tracks as well as signals resulting from spurious marks on the plate such as scratches, dust or grain clumpings, etc. The output of the circuit is hence indicative only of the tracks that would be counted by a human operator.

  18. On method of muon spectrum measurements by the scintillation detectors of a large thickness T4t sub o

    NASA Technical Reports Server (NTRS)

    Ryazhskaya, O. G.

    1985-01-01

    Various methods for the study of muon spectrum are presented. The direct ones include the muon energy measurements by magnetic spectrometers. The indirect ones deal with the reconstruction of the muon spectrum from the spectrum of secondary particles obtained by burst or calorimeter technique. The burst technique is based on the measurement of the number of cascade particles, mainly in the cascade maximum, by the detectors of small thickness T sub 0. The calorimeter method consist in determination of the cascade energy with help of the cascade curve shape. The multilayer detectors are used for this purpose. They are usually comprised of proportional counters, X-ray emulsion chambers or scintillation counters with the target material placed between them. The scintillation detectors of a large thickness measures the total cascade energy directly and the detector works as a true calorimeter. When the total energy is detected, the cascade spectrum differs from the muon one.

  19. Detection of Neutrons with Scintillation Counters

    DOE R&D Accomplishments Database

    Hofstadter, R.

    1948-11-01

    Detection of slow neutrons by: detection of single gamma rays following capture by cadmium or mercury; detection of more than one gamma ray by observing coincidences after capture; detection of heavy charged particles after capture in lithium or baron nuclei; possible use of anthracene for counting fast neutrons investigated briefly.

  20. Results of experiments devoted to searches for 2K capture on {sup 78}Kr and for the double-beta decay of {sup 136}Xe with the aid of proportional counters

    SciTech Connect

    Gavrilyuk, Yu. M.; Gangapshev, A. M.; Zhantudueva, Dj. A.; Kazalov, V. V.; Kuz'minov, V. V.; Panasenko, S. I.; Ratkevich, S. S.; Efendiev, K. V.; Yakimenko, S. P.

    2013-09-15

    A brief description of two low-background setups deployed at the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences) and intended for searches for two types of double-beta decay of inert-gas isotopes-2K capture on {sup 78}Kr and the double-beta decay of {sup 136}Xe-is given. The two setups in question have similar structures and employ identical large high-pressure copper proportional counters as detectors. Upon a treatment of data from measurements with krypton samples differing in the content of the isotope {sup 78}Kr, the spectrum for an enriched sample revealed an excess of events at a statistical-significance level of about two standard deviations (2{sigma}). If one attributes this excess to 2K(2{nu}) capture on {sup 78}Kr, the respective half-life is T{sub 1/2} = 1.4{sub -0.7}{sup +2.3} Multiplication-Sign 10{sup 22} yr at a 90% C.L. A treatment of data from measurements with xenon samples differing in content of the isotope {sup 136}Xe led to the appearance of an excess of events in the spectrum for an enriched sample at a statistical-significance level of about 2.2{sigma}. If one assumes that this excess is due to the two-neutrino double-beta decay of {sup 136}Xe, then the respective half-life is T{sub 1/2} = 5.8{sub -1.8}{sup +4.7} Multiplication-Sign 10{sup 21} yr.

  1. A New Neutron Calibration Technique with Fast Scintillators on DIII-D Tokamak

    NASA Astrophysics Data System (ADS)

    Zhu, Y. B.; Heidbrink, W. W.; Taylor, P. L.; Carrig, W.

    2015-11-01

    Absolute calibrations are necessary for conventional neutron measurements based on proportional counters and fission chambers, at regular intervals. For the DIII-D tokamak, the wide span of fusion rates, approximately between 1.e9 - 1.e17 neutrons per second, from pure Ohmic to high power auxiliary heating plasmas requires careful cross-calibrations of a variety of neutron detectors with stepwise and overlapped sensitivities, with an intense isotope neutron source, e.g. californium-252 and real plasmas. Scintillators have been successfully utilized for fast time resolved neutron detection for decades. A new calibration approach with the help of scintillators is shown to be straightforward, simpler and trustworthy while the conventional approach is complicated, time consuming and costly. Details on the calibration setup and results will be presented. Supported by US DOE SC-G903402 and DE-FC02-04ER54698.

  2. SCINTILLATION SPECTROMETER

    DOEpatents

    Bell, P.R.; Francis, J.E.

    1960-06-21

    A portable scintillation spectrometer is described which is especially useful in radio-biological studies for determining the uptake and distribution of gamma -emitting substances in tissue. The spectrometer includes a collimator having a plurality of apertures that are hexagonal in cross section. Two crystals are provided: one is activated to respond to incident rays from the collimator; the other is not activated and shields the first from external radiation.

  3. Neutron detection by scintillation of noble-gas excimers

    NASA Astrophysics Data System (ADS)

    McComb, Jacob Collin

    Neutron detection is a technique essential to homeland security, nuclear reactor instrumentation, neutron diffraction science, oil-well logging, particle physics and radiation safety. The current shortage of helium-3, the neutron absorber used in most gas-filled proportional counters, has created a strong incentive to develop alternate methods of neutron detection. Excimer-based neutron detection (END) provides an alternative with many attractive properties. Like proportional counters, END relies on the conversion of a neutron into energetic charged particles, through an exothermic capture reaction with a neutron absorbing nucleus (10B, 6Li, 3He). As charged particles from these reactions lose energy in a surrounding gas, they cause electron excitation and ionization. Whereas most gas-filled detectors collect ionized charge to form a signal, END depends on the formation of diatomic noble-gas excimers (Ar*2, Kr*2,Xe* 2) . Upon decaying, excimers emit far-ultraviolet (FUV) photons, which may be collected by a photomultiplier tube or other photon detector. This phenomenon provides a means of neutron detection with a number of advantages over traditional methods. This thesis investigates excimer scintillation yield from the heavy noble gases following the boron-neutron capture reaction in 10B thin-film targets. Additionally, the thesis examines noble-gas excimer lifetimes with relationship to gas type and gas pressure. Experimental data were collected both at the National Institute of Standards and Technology (NIST) Center for Neutron Research, and on a newly developed neutron beamline at the Maryland University Training Reactor. The components of the experiment were calibrated at NIST and the University of Maryland, using FUV synchrotron radiation, neutron imaging, and foil activation techniques, among others. Computer modeling was employed to simulate charged-particle transport and excimer photon emission within the experimental apparatus. The observed excimer

  4. Plastic scintillation dosimetry: Optimal selection of scintillating fibers and scintillators

    SciTech Connect

    Archambault, Louis; Arsenault, Jean; Gingras, Luc; Sam Beddar, A.; Roy, Rene; Beaulieu, Luc

    2005-07-15

    Scintillation dosimetry is a promising avenue for evaluating dose patterns delivered by intensity-modulated radiation therapy plans or for the small fields involved in stereotactic radiosurgery. However, the increase in signal has been the goal for many authors. In this paper, a comparison is made between plastic scintillating fibers and plastic scintillator. The collection of scintillation light was measured experimentally for four commercial models of scintillating fibers (BCF-12, BCF-60, SCSF-78, SCSF-3HF) and two models of plastic scintillators (BC-400, BC-408). The emission spectra of all six scintillators were obtained by using an optical spectrum analyzer and they were compared with theoretical behavior. For scintillation in the blue region, the signal intensity of a singly clad scintillating fiber (BCF-12) was 120% of that of the plastic scintillator (BC-400). For the multiclad fiber (SCSF-78), the signal reached 144% of that of the plastic scintillator. The intensity of the green scintillating fibers was lower than that of the plastic scintillator: 47% for the singly clad fiber (BCF-60) and 77% for the multiclad fiber (SCSF-3HF). The collected light was studied as a function of the scintillator length and radius for a cylindrical probe. We found that symmetric detectors with nearly the same spatial resolution in each direction (2 mm in diameter by 3 mm in length) could be made with a signal equivalent to those of the more commonly used asymmetric scintillators. With augmentation of the signal-to-noise ratio in consideration, this paper presents a series of comparisons that should provide insight into selection of a scintillator type and volume for development of a medical dosimeter.

  5. Emulation workbench for position sensitive gaseous scintillation detectors

    NASA Astrophysics Data System (ADS)

    Pereira, L.; Margato, L. M. S.; Morozov, A.; Solovov, V.; Fraga, F. A. F.

    2015-12-01

    Position sensitive detectors based on gaseous scintillation proportional counters with Anger-type readout are being used in several research areas such as neutron detection, search for dark matter and neutrinoless double beta decay. Design and optimization of such detectors are complex and time consuming tasks. Simulations, while being a powerful tool, strongly depend on the light transfer models and demand accurate knowledge of many parameters, which are often not available. Here we describe an alternative approach based on the experimental evaluation of a detector using an isotropic point-like light source with precisely controllable light emission properties, installed on a 3D positioning system. The results obtained with the developed setup at validation conditions, when the scattered light is strongly suppressed show good agreement with simulations.

  6. Response of a lithium gadolinium borate scintillator in monoenergetic neutron fields.

    PubMed

    Williams, A M; Beeley, P A; Spyrou, N M

    2004-01-01

    Accurate estimation of neutron dose requires knowledge of the neutron energy distribution in the working environment. Existing neutron spectrometry systems, Bonner spheres for example, are large and bulky, and require long data acquisition times. A portable system that could indicate the approximate neutron energy spectrum in a short time would be extremely useful in radiation protection. A composite scintillator, consisting of lithium gadolinium borate crystals in a plastic scintillator matrix, produced by Photogenics is being tested for this purpose. A prototype device based on this scintillator and digital pulse processing electronics has been calibrated using quasi-monoenergetic neutron fields at the low-scatter facility of the UK National Physical Laboratory (NPL). Energies selected were 144, 250, 565, 1400, 2500 and 5000 keV, with correction for scattered neutrons being made using the shadow cone technique. Measurements were also made in the NPL thermal neutron field. Pulse distributions collected with the digitiser in capture-gated mode are presented, and detection efficiency and energy resolution derived. For comparison, neutron spectra were also collected using the commercially available Microspec N-Probe from Bubble Technology Industries, which consists of an NE213 scintillator and a 3He proportional counter.

  7. Multifrequency equatorial ionospheric scintillations in American and Indian zones

    NASA Technical Reports Server (NTRS)

    Rastogi, R. G.; Aarons, J.; Whitney, H. E.; Mullen, J. P.; Pantoja, J.; Deshpande, M. R.; Vats, H. O.; Chandra, H.; Davies, K.

    1980-01-01

    Amplitude scintillations of 40/41, 140 and 360 MHz transmissions recorded at Huancayo (phase I) and at Ootacamund (phase II) of the ATS-6 program are compared. The scintillations were found to be strongest between 20 and 24 hr LT with another peak around midday. The daytime scintillations do not show a significant seasonal variation at either of these stations. The nighttime scintillations were maximum during December solstices at Huancayo and during equinoxes at Ootacamund and suggested to be due to non-q type of sporadic E following the occurrence of counter-electrojet.

  8. Scintillating glass fiber neutron senors

    SciTech Connect

    Abel, K.H.; Arthur, R.J.; Bliss, M.

    1994-04-01

    Cerium-doped lithium-silicate glass fibers have been developed at Pacific Northwest Laboratory (PNL) for use as thermal neutron detectors. By using highly-enriched {sup 6} Li , these fibers efficiently capture thermal neutrons and produce scintillation light that can be detected at the ends of the fibers. Advantages of scintillating fibers over {sup 3}He or BF{sub 3} proportional tubes include flexibility in geometric configuration, ruggedness in high-vibration environments, and less detector weight for the same neutron sensitivity. This paper describes the performance of these scintillating fibers with regard to count rates, pulse height spectra, absolute efficiencies, and neutron/gamma discrimination. Fibers with light transmission lengths (1/e) of greater than 2 m have been produced at PNL. Neutron sensors in fiber form allow development of a variety of neutron detectors packaged in previously unavailable configurations. Brief descriptions of some of the devices already produced are included to illustrate these possibilities.

  9. Scintillating fiber detector performance, detector geometries, trigger, and electronics issues for scintillating fiber tracking

    SciTech Connect

    Baumbaugh, A.E.

    1994-06-01

    Scintillating Fiber tracking technology has made great advances and has demonstrated great potential for high speed charged particle tracking and triggering. The small detector sizes and fast scintillation fluors available make them very promising for use at high luminosity experiments at today`s and tomorrow`s colliding and fixed target experiments where high rate capability is essential. This talk will discuss the current state of Scintillating fiber performance and current Visual Light Photon Counter (VLPC) characteristics. The primary topic will be some of the system design and integration issues which should be considered by anyone attempting to design a scintillating fiber tracking system which includes a high speed tracking trigger. Design. constraints placed upon the detector system by the electronics and mechanical sub-systems will be discussed. Seemingly simple and unrelated decisions can have far reaching effects on overall system performance. SDC and DO example system designs will be discussed.

  10. Scintillators and applications thereof

    DOEpatents

    Williams, Richard T.

    2015-09-01

    Scintillators of various constructions and methods of making and using the same are provided. In some embodiments, a scintillator comprises at least one radiation absorption region and at least one spatially discrete radiative exciton recombination region.

  11. Scintillators and applications thereof

    DOEpatents

    Williams, Richard T.

    2014-07-15

    Scintillators of various constructions and methods of making and using the same are provided. In some embodiments, a scintillator comprises at least one radiation absorption region and at least one spatially discrete radiative exciton recombination region.

  12. Scintillator materials for calorimetry

    SciTech Connect

    Weber, M.J.

    1994-09-01

    Requirements for fast, dense scintillator materials for calorimetry in high energy physics and approaches to satisfying these requirements are reviewed with respect to possible hosts and luminescent species. Special attention is given to cerium-activated crystals, core-valence luminescence, and glass scintillators. The present state of the art, limitations, and suggestions for possible new scintillator materials are presented.

  13. Scintillator manufacture at Fermilab

    SciTech Connect

    Mellott, K.; Bross, A.; Pla-Dalmau, A.

    1998-08-01

    A decade of research into plastic scintillation materials at Fermilab is reviewed. Early work with plastic optical fiber fabrication is revisited and recent experiments with large-scale commercial methods for production of bulk scintillator are discussed. Costs for various forms of scintillator are examined and new development goals including cost reduction methods and quality improvement techniques are suggested.

  14. Lead carbonate scintillator materials

    DOEpatents

    Derenzo, Stephen E.; Moses, William W.

    1991-01-01

    Improved radiation detectors containing lead carbonate or basic lead carbonate as the scintillator element are disclosed. Both of these scintillators have been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to other known scintillator materials. The radiation detectors disclosed are favorably suited for use in general purpose detection and in medical uses.

  15. Scintillator reflective layer coextrusion

    DOEpatents

    Yun, Jae-Chul; Para, Adam

    2001-01-01

    A polymeric scintillator has a reflective layer adhered to the exterior surface thereof. The reflective layer comprises a reflective pigment and an adhesive binder. The adhesive binder includes polymeric material from which the scintillator is formed. A method of forming the polymeric scintillator having a reflective layer adhered to the exterior surface thereof is also provided. The method includes the steps of (a) extruding an inner core member from a first amount of polymeric scintillator material, and (b) coextruding an outer reflective layer on the exterior surface of the inner core member. The outer reflective layer comprises a reflective pigment and a second amount of the polymeric scintillator material.

  16. Scintillation of Un-doped ZnO Single Crystals

    SciTech Connect

    Colosimo, A. M.; Ji, Jianfeng; Stepanov, P. S.; Boatner, L. A.; Selim, F. A.

    2016-01-07

    In this paper, scintillation properties are often studied by photo-luminescence (PL) and scintillation measurements. In this work, we combine X-ray-induced luminescence (XRIL) spectroscopy [Review of Scientific Instruments 83, 103112 (2012)] with PL and standard scintillation measurements to give insight into the scintillation properties of un-doped ZnO single crystals. XRIL revealed that ZnO luminescence proportionally increases with X-ray power and exhibits excellent linearity - indicating the possibility of developing radiation detectors with good energy resolution. Finally, by coupling ZnO crystals to fast photomultiplier tubes and monitoring the anode signal, rise times as fast as 0.9 ns were measured.

  17. PULSE COUNTER

    DOEpatents

    Trumbo, D.E.

    1959-02-10

    A transistorized pulse-counting circuit adapted for use with nuclear radiation detecting detecting devices to provide a small, light weight portable counter is reported. The small size and low power requirements of the transistor are of particular value in this instance. The circuit provides an adjustable count scale with a single transistor which is triggered by the accumulated charge on a storage capacitor.

  18. Elpasolite scintillators.

    SciTech Connect

    Doty, F. Patrick; Zhou, Xiao Wang; Yang, Pin; Rodriguez, Mark A

    2012-12-01

    This work was funded by the U.S. Department of Energy Office of Nonproliferation Research to develop elpasolite materials, with an emphasis on high-atomic-number rare-earth elpasolites for gamma-ray spectrometer applications. Low-cost, high-performance gamma-ray spectrometers are needed for detection of nuclear proliferation. Cubic materials, such as some members of the elpasolite family (A2BLnX6; Ln-lanthanide and X-halogen), hold promise due to their high light output, proportionality, and potential for scale-up. Using both computational and experimental studies, a systematic investigation of the compositionstructureproperty relationships of these high-atomic-number elpasolite halides was performed. The results reduce the barrier to commercialization of large single crystals or transparent ceramics, and will facilitate economical scale-up of elpasolites for high-sensitivity gamma-ray spectroscopy.

  19. Passive neutron coincidence counting with plastic scintillators for the characterization of radioactive waste drums

    SciTech Connect

    Deyglun, C.; Simony, B.; Perot, B.; Carasco, C.; Saurel, N.; Colas, S.; Collot, J.

    2015-07-01

    The quantification of radioactive material is essential in the fields of safeguards, criticality control of nuclear processes, dismantling of nuclear facilities and components, or radioactive waste characterization. The Nuclear Measurement Laboratory (LMN) of CEA is involved in the development of time-correlated neutron detection techniques using plastic scintillators. Usually, 3He proportional counters are used for passive neutron coincidence counting owing to their high thermal neutron capture efficiency and gamma insensitivity. However, the global {sup 3}He shortage in the past few years has made these detectors extremely expensive. In addition, contrary to {sup 3}He counters for which a few tens of microseconds are needed to thermalize fast neutrons, in view to maximize the {sup 3}He(n,p){sup 3}H capture cross section, plastic scintillators are based on elastic scattering and therefore the light signal is formed within a few nanoseconds, correlated pulses being detected within a few dozen- or hundred nanoseconds. This time span reflects fission particles time of flight, which allows reducing accordingly the duration of the coincidence gate and thus the rate of random coincidences, which may totally blind fission coincidences when using {sup 3}He counters in case of a high (α,n) reaction rate. However, plastic scintillators are very sensitive to gamma rays, requiring the use of a thick metallic shield to reduce the corresponding background. Cross talk between detectors is also a major issue, which consists on the detection of one particle by several detectors due to elastic or inelastic scattering, leading to true but undesired coincidences. Data analysis algorithms are tested to minimize cross-talk in simultaneously activated detectors. The distinction between useful fission coincidences and the correlated background due to cross-talk, (α,n) and induced (n,2n) or (n,n'γ) reactions, is achieved by measuring 3-fold coincidences. The performances of a passive

  20. Cherenkov Counters

    SciTech Connect

    Barbero, Marlon

    2012-04-19

    When a charged particle passes through an optically transparent medium with a velocity greater than the phase velocity of light in that medium, it emits prompt photons, called Cherenkov radiation, at a characteristic polar angle that depends on the particle velocity. Cherenkov counters are particle detectors that make use of this radiation. Uses include prompt particle counting, the detection of fast particles, the measurement of particle masses, and the tracking or localization of events in very large, natural radiators such as the atmosphere, or natural ice fields, like those at the South Pole in Antarctica. Cherenkov counters are used in a number of different fields, including high energy and nuclear physics detectors at particle accelerators, in nuclear reactors, cosmic ray detectors, particle astrophysics detectors and neutrino astronomy, and in biomedicine for labeling certain biological molecules.

  1. Direct determination of lead-210 by liquid-scintillation counting

    NASA Technical Reports Server (NTRS)

    Fairman, W. D.; Sedlet, J.

    1969-01-01

    Soft betas, the internal conversion electrons, and unconverted gamma rays from lead-210 are efficiently detected in a liquid scintillation counting system with efficiency of 97 percent. The counter is interfaced with a multichannel pulse height analyzer. The spectra obtained is stored on paper tape and plotted on an x-y plotter.

  2. Shifting scintillator neutron detector

    DOEpatents

    Clonts, Lloyd G; Cooper, Ronald G; Crow, Jr., Morris Lowell; Hannah, Bruce W; Hodges, Jason P; Richards, John D; Riedel, Richard A

    2014-03-04

    Provided are sensors and methods for detecting thermal neutrons. Provided is an apparatus having a scintillator for absorbing a neutron, the scintillator having a back side for discharging a scintillation light of a first wavelength in response to the absorbed neutron, an array of wavelength-shifting fibers proximate to the back side of the scintillator for shifting the scintillation light of the first wavelength to light of a second wavelength, the wavelength-shifting fibers being disposed in a two-dimensional pattern and defining a plurality of scattering plane pixels where the wavelength-shifting fibers overlap, a plurality of photomultiplier tubes, in coded optical communication with the wavelength-shifting fibers, for converting the light of the second wavelength to an electronic signal, and a processor for processing the electronic signal to identify one of the plurality of scattering plane pixels as indicative of a position within the scintillator where the neutron was absorbed.

  3. The Timing Counter of the MEG Experiment

    NASA Astrophysics Data System (ADS)

    Fratini, K.

    2010-04-01

    The MEG experiment is searching for the rare μ+ → e+γ decay with a sensitivity on the BR at the level of 10-13. This kind of precision needs stringent requirements on the performances of the detectors involved in the project. In particular, the Timing Counter detector has been designed to measure the time and the position of the positron at the end of its path inside the MEG detector, reaching a resolution of 100 ps FWHM and 1 cm, respectively. The Timing Counter consists of two subdetectors: one made of contiguous scintillator bars having PMTs at their opposite ends, and the other one made of scintillating fibers read by APDs. Both sub-detectors also generate a first level trigger signal for timing and direction of the positron, respectively.

  4. Study of equatorial scintillations

    NASA Technical Reports Server (NTRS)

    Pomalaza, J.; Woodman, R.; Tisnado, G.; Nakasone, E.

    1972-01-01

    Observations of the amplitude scintillations produced by the F-region in equatorial areas are presented. The equipment used for conducting the observations is described. The use of transmissions from the ATS-1, ATS-3, and ATS-5 for obtaining data is described. The two principal subjects discussed are: (1) correlation between satellite and incoherent radar observations of scintillations and (2) simultaneous observations of scintillations at 136 MHz and 1550 MHz.

  5. Lead carbonate scintillator materials

    DOEpatents

    Derenzo, S.E.; Moses, W.W.

    1991-05-14

    Improved radiation detectors containing lead carbonate or basic lead carbonate as the scintillator element are disclosed. Both of these scintillators have been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to other known scintillator materials. The radiation detectors disclosed are favorably suited for use in general purpose detection and in medical uses. 3 figures.

  6. Standardization of 241Am by digital coincidence counting, liquid scintillation counting and defined solid angle counting.

    PubMed

    Balpardo, C; Capoulat, M E; Rodrigues, D; Arenillas, P

    2010-01-01

    The nuclide (241)Am decays by alpha emission to (237)Np. Most of the decays (84.6%) populate the excited level of (237)Np with energy of 59.54 keV. Digital coincidence counting was applied to standardize a solution of (241)Am by alpha-gamma coincidence counting with efficiency extrapolation. Electronic discrimination was implemented with a pressurized proportional counter and the results were compared with two other independent techniques: Liquid scintillation counting using the logical sum of double coincidences in a TDCR array and defined solid angle counting taking into account activity inhomogeneity in the active deposit. The results show consistency between the three methods within a limit of a 0.3%. An ampoule of this solution will be sent to the International Reference System (SIR) during 2009. Uncertainties were analysed and compared in detail for the three applied methods.

  7. The GlueX Start Counter

    NASA Astrophysics Data System (ADS)

    Llodra, Anthony; Pooser, Eric; GlueX Collaboration

    2015-04-01

    The GlueX experiment, which is online as of October of 2014, will study meson photo production with unprecedented precision. This experiment will use the coherent bremsstrahlung technique to produce a 9 GeV linearly polarized photon beam incident on a liquid H2 target kept at a few degrees Kelvin. A Start Counter detector has been fabricated to identify the accelerator electron beam buckets, approximately 2 nanoseconds apart, and to provide accurate timing information. This detector is designed to operate at photon intensities of up to 108 γ/s in the coherent peak and provide a timing resolution of less than 350 picoseconds so as to provide successful identification of the electron beam buckets. It consists of a cylindrical array of 30 scintillators with pointed ends that bend towards the beam at the downstream end. The EJ-200 scintillator is best suited for the Start Counter due to its fast decay time on the order of 2 nanoseconds and long attenuation length. Silicon Photo Multiplier (SiPM) detectors have been selected as the readout system and are to be placed as close as possible, less than 300 micron, to the upstream end of each scintillator. The methods/details of the assembly and the optimization of the surface quality of scintillator paddles are discussed. This work was supported in part by DoE Contracts DE-FG02-99ER41065 and DE-AC05-06OR23177.

  8. Scintillating-glass-fiber neutron sensors

    NASA Astrophysics Data System (ADS)

    Abel, K. H.; Arthur, R. J.; Bliss, M.; Brite, D. W.; Brodzinski, R. L.; Craig, R. A.; Geelhood, B. D.; Goldman, D. S.; Griffin, J. W.; Perkins, R. W.; Reeder, P. L.; Richey, W. R.; Stahl, K. A.; Sunberg, D. S.; Warner, R. A.; Wogman, N. A.; Weber, M. J.

    1994-12-01

    Cerium-doped lithium-silicate glass fibers have been developed at Pacific Northwest Laboratory (PNL) for use as thermal neutron detectors. By using highly-enriched 6Li, these fibers efficiently capture thermal neutrons and produce scintillation light that can be detected at the ends of the fibers. Advantages of scintillating fibers over 3He or BF 3 proportional tubes include flexibility in geometric configuration, ruggedness in high-vibration environments, and less detector weight for the same neutron sensitivity. This paper describes the performance of these scintillating fibers with regard to count rates, pulse height spectra, absolute efficiencies, and neutron/gamma discrimination. Fibers with light transmission lengths ( {1}/{e}) of greater than 2 m have been produced at PNL. Neutron sensors in fiber form allow development of a variety of neutron detectors packaged in previously unavailable configurations. Brief descriptions of some of the devices already produced are included to illustrate these possibilities.

  9. Predicted performance of neutron spectrometers using scintillating fibers

    SciTech Connect

    RA Craig; M Bliss

    2000-02-14

    A variety of needs exists for knowing the energy spectral content of a neutron flux. Among these needs are arms-control and national-security applications, which arise because different neutron sources produce different neutron energy spectra. This work is primarily directed at these applications. The concept described herein is a spectrometer in the same sense as a Bonner sphere. The instrument response reflects a statistical average of the energy spectrum. The Bonner sphere is an early rendition of this class. In this, a neutron detector is placed at the center of a moderating (and absorbing) sphere (of varying thickness and composition). Spectral unfolding is required, and the resolution and efficiency are, typically, poor, although the potential bandwidth is very large. A recent variation on the Bonner-sphere approach uses {sup 3}He gas proportional counters with resistive wires to locate the position of the event (Toyokawa et al 1996). The spectrometer concept investigated here has the potential for better resolution and much improved neutron efficiency compared to Bonner spheres and similar devices. These improvements are possible because of the development of neutron-sensitive, scintillating-glass fibers. These fibers can be precisely located in space, which allows a corresponding precision in energy resolution. Also, they can be fabricated into arrays that intercept a large fraction of incident thermal neutrons, providing the improvement in neutron economy.

  10. The 12B counter: an active dosemeter for high-energy neutrons.

    PubMed

    Leuschner, A

    2005-01-01

    High-energy accelerators can produce strong time-structured radiation fields. Such dose shots are generated at linear machines with low duty cycles as well as at circular machines when complete fills are instantaneously lost. The main dose component behind thick shielding is due to high-energy neutrons occurring at that time structure. Dosemeters based on Geiger-Mueller tubes or proportional counters fail here completely. The 12B counter, a novel dosemeter made of a plastic scintillator using carbon activation for event-like exposure, has been introduced. High-energy neutrons activate the carbon nuclei by three inelastic reactions. The decay patterns with half-lives between 20 ms and 20 min can be exploited depending on the time structure of the radiation field. The response of the 12B counter was measured along with some other dosemeters, both active and passive, in the radiation field behind the lateral concrete shielding of a 7.5 GeV proton transfer line.

  11. Cherenkov and Scintillation Properties of Cubic Zirconium

    NASA Technical Reports Server (NTRS)

    Christl, M.J.; Adams, J.H.; Parnell, T.A.; Kuznetsov, E.N.

    2008-01-01

    Cubic zirconium (CZ) is a high index of refraction (n =2.17) material that we have investigated for Cherenkov counter applications. Laboratory and proton accelerator tests of an 18cc sample of CZ show that the expected fast Cherenkov response is accompanied by a longer scintillation component that can be separated by pulse shaping. This presents the possibility of novel particle spectrometers which exploits both properties of CZ. Other high index materials being examined for Cherenkov applications will be discussed. Results from laboratory tests and an accelerator exposure will be presented and a potential application in solar energetic particle instruments will be discussed

  12. Data Analysis for the Scintillating Optical Fiber Calorimeter (SOFCAL)

    NASA Technical Reports Server (NTRS)

    Christl, Mark J.

    1997-01-01

    The scintillating optical fiber calorimeter is a hybrid instrument with both active and passive components for measuring the proton and helium cosmic ray spectra from 0.2 to IO TeV kinetic energy. A thin emulsion/x-ray film chamber is situated between a cerenkov counter and an imaging calorimeter. Scintillating optical fibers sample the electromagnetic showers that develop in the calorimeter and identify the trajectory of cosmic rays that interact in SOFCAL. The emulsion/x-ray film data provide an in flight calibration for SOFCAL. The data reduction techniques used will be discussed and interim results of the analysis from a 20 hour balloon flight will be presented.

  13. Scintillation Detector for the Measurement of Ultra-Heavy Cosmic Rays on the Super-TIGER Experiment

    NASA Technical Reports Server (NTRS)

    Link, Jason

    2011-01-01

    We discuss the design and construction of the scintillation detectors for the Super-TIGER experiment. Super-TIGER is a large-area (5.4sq m) balloon-borne experiment designed to measure the abundances of cosmic-ray nuclei between Z= 10 and Z=56. It is based on the successful TIGER experiment that flew in Antarctica in 2001 and 2003. Super-TIGER has three layers of scintillation detectors, two Cherenkov detectors and a scintillating fiber hodoscope. The scintillation detector employs four wavelength shifter bars surrounding the edges of the scintillator to collect the light from particles traversing the detector. PMTs are optically coupled at both ends of the bars for light collection. We report on laboratory performance of the scintillation counters using muons. In addition we discuss the design challenges and detector response over this broad charge range including the effect of scintilator saturation.

  14. Measurements of the performance of multiwire proportional chambers

    NASA Technical Reports Server (NTRS)

    Austin, R. W.; Eglitis, A.; Gregory, J. C.; Metzger, S. A.; Parnell, T. A.; Rutledge, H. F.; Selig, W.; Cumings, N. P.

    1973-01-01

    Data are presented that may be useful in formulating engineering specifications and test procedures for the proportional counter hodoscope to be flown as part of the High Energy Cosmic Ray Experiment on the High Energy Astronomy Observatory (HEAO), Mission A. A collection of preliminary data taken in laboratory tests of multiwire counters with an anode wire spacing of 5 mm and cathode gap spacing of 1 cm is presented. The data are from laboratory development models or counters for balloon flights and were selected to illustrate several aspects of proper and improper counter performance. Most of the data were taken from a large proportional counter hodoscope which has an active area of 0.5 by 0.5 m and 104 wires per plane.

  15. Distributed performance counters

    DOEpatents

    Davis, Kristan D; Evans, Kahn C; Gara, Alan; Satterfield, David L

    2013-11-26

    A plurality of first performance counter modules is coupled to a plurality of processing cores. The plurality of first performance counter modules is operable to collect performance data associated with the plurality of processing cores respectively. A plurality of second performance counter modules are coupled to a plurality of L2 cache units, and the plurality of second performance counter modules are operable to collect performance data associated with the plurality of L2 cache units respectively. A central performance counter module may be operable to coordinate counter data from the plurality of first performance counter modules and the plurality of second performance modules, the a central performance counter module, the plurality of first performance counter modules, and the plurality of second performance counter modules connected by a daisy chain connection.

  16. Performance and Application of VUV-sensitive MPPCs for Liquid Argon Scintillation Light

    NASA Astrophysics Data System (ADS)

    Washimi, Tatsuki; Tanaka, Masashi; Yorita, Kohei

    A new type of the Multi-Pixel Photon Counter (MPPC), sensitive to liquid argon (LAr) scintillation light (wavelength = 128 nm), is recently developed and produced by Hamamatsu Photonics K.K. In this talk, we report the basic properties of the new MPPCs and the absolute photon detection efficiency (PDE) for LAr scintillation light. Comparisons of different MPPC types (with or without cross-talk supression and pixel sizes of 50 and 100 µm) are also presented.

  17. Position sensitive counter development at the linac

    SciTech Connect

    Becker, J.A.

    1981-05-20

    In a novel application of the multiwire proportional counter we have imaged a collimated neutron beam. Although preliminary, the results are of sufficient import to be described here because of the potential wide application of the multiwire proportional counter to Laboratory problems. The counter was operated with a counting gas pressure of 20 Torr; the counting gas was pure C/sub 4/H/sub 10/. The radiator was a /sup 235/U foil. Under these conditions, the counter is (1) relatively insensitive to charged particles (other than fission fragments), (2) insensitive to ..gamma..-radiation, and (3) has an efficiency for the detection of fission fragments independent of incident neutron energy over a wide range of neutron energies.

  18. Scintillator Measurements for SNO+

    NASA Astrophysics Data System (ADS)

    Kaptanoglu, Tanner; SNO+ Collaboration

    2016-03-01

    SNO+ is a neutrino detector located 2km underground in the SNOLAB facility with the primary goal of searching for neutrinoless double beta decay. The detector will be filled with a liquid scintillator target primarily composed of linear alkyl benzene (LAB). As charged particles travel through the detector the LAB produces scintillation light which is detected by almost ten thousand PMTs. The LAB is loaded with Te130, an isotope known to undergo double beta decay. Additionally, the LAB is mixed with an additional fluor and wavelength shifter to improve the light output and shift the light to a wavelength regime in which the PMTs are maximally efficient. The precise scintillator optics drastically affect the ultimate sensitivity of SNO+. I will present work being done to measure the optical properties of the SNO+ scintillator cocktail. The measured properties are used as input to a scintillation model that allows us to extrapolate to the SNO+ scale and ultimately predict the sensitivity of the experiment. Additionally, I will present measurements done to characterize the R5912 PMT, a candidate PMT for the second phase of SNO+ that provides better light collection, improved charge resolution, and a narrower spread in timing.

  19. Development of a novel scintillation-trigger detector for the MTV experiment using aluminum-metallized film tapes

    NASA Astrophysics Data System (ADS)

    Tanaka, S.; Ozaki, S.; Sakamoto, Y.; Tanuma, R.; Yoshida, T.; Murata, J.

    2014-07-01

    A new type of a trigger-scintillation counter array designed for the MTV experiment at TRIUMF-ISAC has been developed, which uses aluminum-metallized film tape for wrapping to achieve the required assembling precision of ±0.5 mm. The MTV experiment uses a cylindrical drift chamber (CDC) as the main electron-tracking detector. The barrel-type trigger counter is placed inside the CDC to generate a trigger signal using 1 mm thick, 300 mm long thin plastic scintillation counters. Detection efficiency and light attenuation compared with conventional wrapping materials are studied.

  20. Radioactivity observed in scintillation counters during the HEAO-1 mission

    NASA Technical Reports Server (NTRS)

    Gruber, D. E.; Jung, G. V.; Matteson, J. L.

    1989-01-01

    Results are reported from an analysis of radioactivity induced in the NaI medium-energy detector of the hard X-ray and low-energy gamma-ray experiment during the HEAO-1 satellite mission (1977-1978). Consideration is given to the instrument characteristics, the origin and variability of background, and the separation of cosmic-ray activity from the internal activity due to South Atlantic Anomaly trapped protons. Energy spectra and tables listing the nuclide identifications are provided.

  1. Scintillator plate calorimetry

    SciTech Connect

    Price, L.E.

    1990-01-01

    Calorimetry using scintillator plates or tiles alternated with sheets of (usually heavy) passive absorber has been proven over multiple generations of collider detectors. Recent detectors including UA1, CDF, and ZEUS have shown good results from such calorimeters. The advantages offered by scintillator calorimetry for the SSC environment, in particular, are speed (<10 nsec), excellent energy resolution, low noise, and ease of achieving compensation and hence linearity. On the negative side of the ledger can be placed the historical sensitivity of plastic scintillators to radiation damage, the possibility of nonuniform response because of light attenuation, and the presence of cracks for light collection via wavelength shifting plastic (traditionally in sheet form). This approach to calorimetry is being investigated for SSC use by a collaboration of Ames Laboratory/Iowa State University, Argonne National Laboratory, Bicron Corporation, Florida State University, Louisiana State University, University of Mississippi, Oak Ridge National Laboratory, Virginia Polytechnic Institute and State University, Westinghouse Electric Corporation, and University of Wisconsin.

  2. Real-time {sup 90}Sr Counter

    SciTech Connect

    Kaneko, Naomi; Kawai, Hideyuki; Kodama, Satoshi; Kobayashi, Atsushi; Tabata, Makoto; Ito, Hiroshi; Han, Soorim

    2015-07-01

    Radioisotopes have been emitted around Japan due to a nuclear accident at the Fukushima Daiichi nuclear power station in March 2011. A problem is the contaminated water including the atomic nucleus which relatively has a long half- life time and soluble such as {sup 90}Sr, {sup 137}Cs. Internal exposures by {sup 90}Sr are more dangerous than {sup 137}Cs's because Sr has effective half-life time of 18 years and property of accumulation in a born. We have developed real-time {sup 90}Sr counter which is sensitive beta-ray of maximum kinematic energy of 2.28 MeV from {sup 90}Sr and insensitive of beta-ray of maximum kinematic energy of 1.17 MeV and gamma-ray from {sup 90}Sr by Cherenkov detection. This counter composes of Cerenkov counter, trigger scintillation counter and veto counter. Silica aerogel for Cherenkov counter can obtain refractive index between 1.017 and 1.049 easily. And wavelength shifting fiber (WLSF) is used as a light guide for extending effective area and producing lower cost. A mechanism of the identification of {sup 90}Sr is explained in following. In case of {sup 90}Sr, when the trigger counter reacts on the beta-ray from {sup 90}Sr, aerogel emits the Cherenkov light and WLSF reacts and read the Cherenkov light. On the other hand, in case of {sup 137}Cs, the trigger counter reacts on the beta-ray, aerogel stops the beta- ray and Cherenkov light is not emitted. Therefore, aerogel has a function as a radiator and shielding material. the gamma-ray is not reacted on the lower density detector. Cosmic rays would be also reacted by the veto counter. A prototype counter whose the effective area is 30 cm x 10 cm was obtained (2.0±1.2){sup 3} of mis-identification as {sup 137}Cs/{sup 90}Sr. Detection limit in the surface contamination inspection depends on measurement time and effective area mainly. The sensitivity of wide range, 10{sup -2} - 10{sup 4} Bq/cm{sup 2}, is obtained by adjustment of detection level in circuit of this counter. A lower

  3. Measurement of Scintillation and Ionization Yield and Scintillation Pulse Shape from Nuclear Recoils in Liquid Argon

    DOE PAGES

    Cao, H.

    2015-05-26

    We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow band neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We also report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.3 keV and for median applied electric fields from 0more » to 970 V/cm. For the ionization yields, we report measurements from 16.9 to 57.3 keV and for electric fields from 96.4 to 486 V/cm. Furthermore, we report the observation of an anticorrelation between scintillation and ionization from nuclear recoils, which is similar to the anticorrelation between scintillation and ionization from electron recoils. Assuming that the energy loss partitions into excitons and ion pairs from 83mKr internal conversion electrons is comparable to that from 207Bi conversion electrons, we obtained the numbers of excitons (Nex) and ion pairs (Ni) and their ratio (Nex/Ni) produced by nuclear recoils from 16.9 to 57.3 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.« less

  4. Measurement of scintillation and ionization yield and scintillation pulse shape from nuclear recoils in liquid argon

    NASA Astrophysics Data System (ADS)

    Cao, H.; Alexander, T.; Aprahamian, A.; Avetisyan, R.; Back, H. O.; Cocco, A. G.; Dejongh, F.; Fiorillo, G.; Galbiati, C.; Grandi, L.; Guardincerri, Y.; Kendziora, C.; Lippincott, W. H.; Love, C.; Lyons, S.; Manenti, L.; Martoff, C. J.; Meng, Y.; Montanari, D.; Mosteiro, P.; Olvitt, D.; Pordes, S.; Qian, H.; Rossi, B.; Saldanha, R.; Sangiorgio, S.; Siegl, K.; Strauss, S. Y.; Tan, W.; Tatarowicz, J.; Walker, S.; Wang, H.; Watson, A. W.; Westerdale, S.; Yoo, J.; Scene Collaboration

    2015-05-01

    We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow band neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.3 keV and for median applied electric fields from 0 to 970 V /cm . For the ionization yields, we report measurements from 16.9 to 57.3 keV and for electric fields from 96.4 to 486 V /cm . We also report the observation of an anticorrelation between scintillation and ionization from nuclear recoils, which is similar to the anticorrelation between scintillation and ionization from electron recoils. Assuming that the energy loss partitions into excitons and ion pairs from Krm83 internal conversion electrons is comparable to that from 207Bi conversion electrons, we obtained the numbers of excitons (Nex) and ion pairs (Ni) and their ratio (Nex/Ni ) produced by nuclear recoils from 16.9 to 57.3 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.

  5. Measurement of Scintillation and Ionization Yield and Scintillation Pulse Shape from Nuclear Recoils in Liquid Argon

    SciTech Connect

    Cao, H.

    2015-05-26

    We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow band neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We also report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.3 keV and for median applied electric fields from 0 to 970 V/cm. For the ionization yields, we report measurements from 16.9 to 57.3 keV and for electric fields from 96.4 to 486 V/cm. Furthermore, we report the observation of an anticorrelation between scintillation and ionization from nuclear recoils, which is similar to the anticorrelation between scintillation and ionization from electron recoils. Assuming that the energy loss partitions into excitons and ion pairs from 83mKr internal conversion electrons is comparable to that from 207Bi conversion electrons, we obtained the numbers of excitons (Nex) and ion pairs (Ni) and their ratio (Nex/Ni) produced by nuclear recoils from 16.9 to 57.3 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.

  6. Studies of air showers produced by primaries 10(16) eV using a combined scintillation and water-Cerenkov array

    NASA Technical Reports Server (NTRS)

    Brooke, G.; Perrett, J. C.; Watson, A. A.

    1986-01-01

    An array of 8 x 1.0 sq m plastic scintillation counters and 13 water-Cerenkov detectors (1 to 13.5 sq m) were operated at the center of the Haverah Park array to study some features of air showers produced by 10(16) eV primaries. Measurements of the scintillator lateral distribution function, the water-Cerenkov lateral distribution function, and of the distance dependence of the Cerenkov/scintillator ratio are described.

  7. Scintillator Waveguide For Sensing Radiation

    DOEpatents

    Bliss, Mary; Craig, Richard A.; Reeder; Paul L.

    2003-04-22

    The present invention is an apparatus for detecting ionizing radiation, having: a waveguide having a first end and a second end, the waveguide formed of a scintillator material wherein the therapeutic ionizing radiation isotropically generates scintillation light signals within the waveguide. This apparatus provides a measure of radiation dose. The apparatus may be modified to permit making a measure of location of radiation dose. Specifically, the scintillation material is segmented into a plurality of segments; and a connecting cable for each of the plurality of segments is used for conducting scintillation signals to a scintillation detector.

  8. Scintillator requirements for medical imaging

    SciTech Connect

    Moses, William W.

    1999-09-01

    Scintillating materials are used in a variety of medical imaging devices. This paper presents a description of four medical imaging modalities that make extensive use of scintillators: planar x-ray imaging, x-ray computed tomography (x-ray CT), SPECT (single photon emission computed tomography) and PET (positron emission tomography). The discussion concentrates on a description of the underlying physical principles by which the four modalities operate. The scintillator requirements for these systems are enumerated and the compromises that are made in order to maximize imaging performance utilizing existing scintillating materials are discussed, as is the potential for improving imaging performance by improving scintillator properties.

  9. SCINTILLATION EXPOSURE RATE DETECTOR

    DOEpatents

    Spears, W.G.

    1960-11-01

    A radiation detector for gamma and x rays is described. The detector comprises a scintillation crystal disposed between a tantalum shield and the input of a photomultiplier tube, the crystal and the shield cooperating so that their combined response to a given quantity of radiation at various energy levels is substantially constant.

  10. Boron loaded scintillator

    SciTech Connect

    Bell, Zane William; Brown, Gilbert Morris; Maya, Leon; Sloop, Jr., Frederick Victor; Sloop, Jr., Frederick Victor

    2009-10-20

    A scintillating composition for detecting neutrons and other radiation comprises a phenyl containing silicone rubber with carborane units and at least one phosphor molecule. The carbonate units can either be a carborane molecule dispersed in the rubber with the aid of a compatibilization agent or can be covalently bound to the silicone.

  11. Polysiloxane scintillator composition

    DOEpatents

    Walker, J.K.

    1992-05-05

    A plastic scintillator useful for detecting ionizing radiation comprising a matrix which comprises an optically transparent polysiloxane having incorporated therein at least one ionizing radiation-hard fluor capable of converting electromagnetic energy produced in the polysiloxane upon absorption of ionizing radiation to detectable light.

  12. Polysiloxane scintillator composition

    DOEpatents

    Walker, James K.

    1992-01-01

    A plastic scintillator useful for detecting ionizing radiation comprising a matrix which comprises an optically transparent polysiloxane having incorporated therein at least one ionizing radiation-hard fluor capable of converting electromagnetic energy produced in the polysiloxane upon absorption of ionizing radiation to detectable light.

  13. Quenching equation for scintillation

    NASA Astrophysics Data System (ADS)

    Kato, Takahisa

    1980-06-01

    A mathematical expression is postulated showing the relationship between counting rate and quenching agent concentration in a liquid scintillation solution. The expression is more suited to a wider range of quenching agent concentrations than the Stern-Volmer equation. An estimation of the quenched correction is demonstrated using the expression.

  14. Investigating the Anisotropic Scintillation Response in Organic Crystal Scintillator Detectors

    NASA Astrophysics Data System (ADS)

    Schuster, Patricia Frances

    This dissertation presents several studies that experimentally characterize the scintillation anisotropy in organic crystal scintillators. These include measurements of neutron, gamma-ray and cosmic muon interactions in anthracene, a historical benchmark among organic scintillator materials, to confirm and extend measurements previously available in the literature. The gamma-ray and muon measurements provide new experimental confirmation that no scintillation anisotropy is present in their interactions. Observations from these measurements have updated the hypothesis for the physical mechanism that is responsible for the scintillation anisotropy concluding that a relatively high dE/dx is required in order to produce a scintillation anisotropy. The directional dependence of the scintillation output in liquid and plastic materials was measured to experimentally confirm that no scintillation anisotropy correlated to detector orientation exists in amorphous materials. These observations confirm that the scintillation anisotropy is not due to an external effect on the measurement system, and that a fixed, repeating structure is required for a scintillation anisotropy. The directional dependence of the scintillation output in response to neutron interactions was measured in four stilbene crystals of various sizes and growth-methods. The scintillation anisotropy in these materials was approximately uniform, indicating that the crystal size, geometry, and growth method do not significantly impact the effect. Measurements of three additional pure crystals and two mixed crystals were made. These measurements showed that 1) the magnitude of the effect varies with energy and material, 2) the relationship between the light output and pulse shape anisotropy varies across materials, and 3) the effect in mixed materials is very complex. These measurements have informed the hypothesis of the mechanism that produces the directional dependence. By comparing the various relationships

  15. DETECTORS AND EXPERIMENTAL METHODS: Studies of timing properties for a TOF counter at an external target facility

    NASA Astrophysics Data System (ADS)

    Yu, Yu-Hong; Xu, Hua-Gen; Xu, Hu-Shan; Zhan, Wen-Long; Sun, Zhi-Yu; Guo, Zhong-Yan; Hu, Zheng-Guo; Chen, Jun-Ling; Tang, Shu-Wen

    2009-09-01

    Timing and amplitude properties of a prototype scintillator TOF counter at an external target facility are studied with a cosmic rays test. The dependence of signal pulse height and time resolution on the coordinate along the scintillator TOF counter is investigated with two different discriminators. A time resolution of 165 ps can be achieved at the center of the counter with a constant fraction discriminator. Time resolution better than 150 ps is obtained at the center with a leading edge discriminator after time walk correction is applied for off-line analysis.

  16. Double phase (liquid/gas) xenon scintillation detector for WIMPs direct search

    NASA Astrophysics Data System (ADS)

    Yamashita, M.; Doke, T.; Kikuchi, J.; Suzuki, S.

    2003-10-01

    A double phase (liquid/gas) xenon prototype detector of a 0.3 l active volume for WIMPs direct search has been constructed and tested. Proportional scintillation signals are observed by a multi-wire anode mounted in gas phase after ionization electrons drifted successfully long distance in liquid xenon. Both direct and proportional scintillation were used to discriminate electron recoil from nuclear recoil. Basic performances of the detector and the rejection efficiency of background gamma rays were demonstrated.

  17. Forward shower counters for diffractive physics at the LHC

    NASA Astrophysics Data System (ADS)

    Albrow, Michael; Collins, Paula; Penzo, Aldo

    2014-11-01

    The LHC detectors have incomplete angular coverage in the forward direction, for example in the region 6 ≲ |η| ≲ 8, which can be improved with the addition of simple scintillation counters around the beam pipes about 50 m to 120 m from the intersection point. These counters detect showers created by particles hitting the beam pipes and nearby material. The absence of signals in these counters in low pileup conditions is an indication of a forward rapidity gap as a signature of diffraction. In addition, they can be used to detect hadrons from low mass diffractive excitations of the proton, not accompanied by a leading proton but adjacent to a rapidity gap over (e.g.) 3 ≲ |η| ≲ 6. Such a set of forward shower counters, originally used at CDF, was used in CMS (FSC) for high-β* running with TOTEM during LHC Run-1. During LS1 the CMS FSC system is being upgraded for future low pileup runs. A similar system, called HERSCHEL is being installed in LHCb. ALICE is implementing scintillation counters, ADA and ADC, with 4.5 ≲ |η| ≲ 6.4.

  18. Composite scintillator screen

    DOEpatents

    Zeman, Herbert D.

    1994-01-01

    A scintillator screen for an X-ray system includes a substrate of low-Z material and bodies of a high-Z material embedded within the substrate. By preselecting the size of the bodies embedded within the substrate, the spacial separation of the bodies and the thickness of the screen, the sensitivity of the screen to X-rays within a predetermined energy range can be predicted.

  19. A study of the characteristics of scintillation detectors with a diffuse reflector

    NASA Astrophysics Data System (ADS)

    Baranov, V. A.; Filchenkov, V. V.; Konin, A. D.; Zhuk, V. V.

    1996-02-01

    The process of light collection in a scintillation counter with a diffuse reflector is studied using the Monte-Carlo codes "PHOTON" and "LIGHT". The results obtained are compared with the simple model estimations and employed to describe the time shape of the signal for several different detectors including the full absorption neutron spectrometer, and reanalyze the previous NE-213 transparency measurements.

  20. A large Scintillating Fibre Tracker for LHCb

    NASA Astrophysics Data System (ADS)

    Greim, R.

    2017-02-01

    The LHCb experiment will be upgraded during LHC Long Shutdown 2 to be able to record data at a higher instantaneous luminosity. The readout rate is currently limited to 1 MHz by the Level 1 trigger. In order to achieve the target integrated luminosity of 50 fb‑1 during LHC Run 3, all subdetectors have to be read out by a 40 MHz trigger-less readout system. Especially, the current tracking detectors downstream of the LHCb dipole magnet suffer from large detector dead times and a small granularity in the Outer Tracker, which consists of proportional straw tubes. Therefore, the Downstream Tracker will be replaced by a Scintillating Fibre Tracker with Silicon Photomultiplier readout. The total sensitive area of 340 m2 is made up of 2.5 m long fibre mats consisting of six staggered layers of 250 μm thin scintillating fibres. The scintillation light created by the charged particles traversing the fibre mats is transported to the fibre ends via total internal reflection and detected by state-of-the-art multi-channel SiPM arrays. This paper presents the detector concept, design, challenges, custom-made readout chips, as well as laboratory and beam test results.

  1. Adaptation through proportion

    NASA Astrophysics Data System (ADS)

    Xiong, Liyang; Shi, Wenjia; Tang, Chao

    2016-08-01

    Adaptation is a ubiquitous feature in biological sensory and signaling networks. It has been suggested that adaptive systems may follow certain simple design principles across diverse organisms, cells and pathways. One class of networks that can achieve adaptation utilizes an incoherent feedforward control, in which two parallel signaling branches exert opposite but proportional effects on the output at steady state. In this paper, we generalize this adaptation mechanism by establishing a steady-state proportionality relationship among a subset of nodes in a network. Adaptation can be achieved by using any two nodes in the sub-network to respectively regulate the output node positively and negatively. We focus on enzyme networks and first identify basic regulation motifs consisting of two and three nodes that can be used to build small networks with proportional relationships. Larger proportional networks can then be constructed modularly similar to LEGOs. Our method provides a general framework to construct and analyze a class of proportional and/or adaptation networks with arbitrary size, flexibility and versatile functional features.

  2. Crystal growth and scintillation properties of strontium iodide scintillators

    SciTech Connect

    van Loef, Edgar; Wilson, Cody; Cherepy, Nerine; Payne, Steven; Choong, Woon-Seng; Moses, William W.; Shah, Kanai

    2009-06-01

    Single crystals of SrI{sub 2}:Eu and SrI{sub 2}:Ce/Na were grown from anhydrous iodides by the vertical Bridgman technique in evacuated silica ampoules. Growth rates were of the order of 5-30 mm/day. Radioluminescence spectra of SrI{sub 2}:Eu and SrI{sub 2}:Ce/Na exhibit a broad band due to Eu{sup 2+} and Ce{sup 3+} emission, respectively. The maximum in the luminescence spectrum of SrI{sub 2}:Eu is found at 435 nm. The spectrum of SrI{sub 2}:Ce/Na exhibits a doublet peaking at 404 and 435 nm attributed to Ce{sup 3+} emission, while additional impurity - or defected - related emission is present at approximately 525 nm. The strontium iodide scintillators show very high light yields of up to 120,000 photons/MeV, have energy resolutions down to 3% at 662 keV (Full Width Half Maximum) and exhibit excellent light yield proportionality with a standard deviation of less than 5% between 6 and 460 keV.

  3. Neutron crosstalk between liquid scintillators

    SciTech Connect

    Verbeke, J. M.; Prasad, M. K.; Snyderman, N. J.

    2015-05-01

    We propose a method to quantify the fractions of neutrons scattering between liquid scintillators. Using a spontaneous fission source, this method can be utilized to quickly characterize an array of liquid scintillators in terms of crosstalk. The point model theory due to Feynman is corrected to account for these multiple scatterings. Using spectral information measured by the liquid scintillators, fractions of multiple scattering can be estimated, and mass reconstruction of fissile materials under investigation can be improved. Monte Carlo simulations of mono-energetic neutron sources were performed to estimate neutron crosstalk. A californium source in an array of liquid scintillators was modeled to illustrate the improvement of the mass reconstruction.

  4. Neutron crosstalk between liquid scintillators

    NASA Astrophysics Data System (ADS)

    Verbeke, J. M.; Prasad, M. K.; Snyderman, N. J.

    2015-09-01

    A method is proposed to quantify the fractions of neutrons scattering between liquid scintillators. Using a spontaneous fission source, this method can be utilized to quickly characterize an array of liquid scintillators in terms of crosstalk. The point model theory due to Feynman is corrected to account for these multiple scatterings. Using spectral information measured by the liquid scintillators, fractions of multiple scattering can be estimated, and mass reconstruction of fissile materials under investigation can be improved. Monte Carlo simulations of mono-energetic neutron sources were performed to estimate neutron crosstalk. A californium source in an array of liquid scintillators was modeled to illustrate the improvement of the mass reconstruction.

  5. FLEXIBLE GEIGER COUNTER

    DOEpatents

    Richter, H.G.; Gillespie, A.S. Jr.

    1963-11-12

    A flexible Geiger counter constructed from materials composed of vinyl chloride polymerized with plasticizers or co-polymers is presented. The counter can be made either by attaching short segments of corrugated plastic sleeving together, or by starting with a length of vacuum cleaner hose composed of the above materials. The anode is maintained substantially axial Within the sleeving or hose during tube flexing by means of polystyrene spacer disks or an easily assembled polyethylene flexible cage assembly. The cathode is a wire spiraled on the outside of the counter. The sleeving or hose is fitted with glass end-pieces or any other good insulator to maintain the anode wire taut and to admit a counting gas mixture into the counter. Having the cathode wire on the outside of the counter substantially eliminates the objectional sheath effect of prior counters and permits counting rates up to 300,000 counts per minute. (AEC)

  6. Countering Internet Extremism

    DTIC Science & Technology

    2009-01-01

    literally examine hundreds of books and speeches. Since the purpose of this work is examining ways to counter an extremist’s Internet use of the...provide differing perspectives on how to counter extremist Internet use . A 2008 New York Times article indirectly offers some methods. Writers Eric...or scholars have the most potential to effectively counter extremist Internet use . Such efforts could help to stifle some of the issues that

  7. Selecting Proportional Reasoning Tasks

    ERIC Educational Resources Information Center

    de la Cruz, Jessica A.

    2013-01-01

    With careful consideration given to task selection, students can construct their own solution strategies to solve complex proportional reasoning tasks while the teacher's instructional goals are still met. Several aspects of the tasks should be considered including their numerical structure, context, difficulty level, and the strategies they are…

  8. Monte Carlo Shower Counter Studies

    NASA Technical Reports Server (NTRS)

    Snyder, H. David

    1991-01-01

    Activities and accomplishments related to the Monte Carlo shower counter studies are summarized. A tape of the VMS version of the GEANT software was obtained and installed on the central computer at Gallaudet University. Due to difficulties encountered in updating this VMS version, a decision was made to switch to the UNIX version of the package. This version was installed and used to generate the set of data files currently accessed by various analysis programs. The GEANT software was used to write files of data for positron and proton showers. Showers were simulated for a detector consisting of 50 alternating layers of lead and scintillator. Each file consisted of 1000 events at each of the following energies: 0.1, 0.5, 2.0, 10, 44, and 200 GeV. Data analysis activities related to clustering, chi square, and likelihood analyses are summarized. Source code for the GEANT user subprograms and data analysis programs are provided along with example data plots.

  9. ATLAS ALFA—measuring absolute luminosity with scintillating fibres

    NASA Astrophysics Data System (ADS)

    Franz, S.; Barrillon, P.

    2009-10-01

    ALFA is a high-precision scintillating fibre tracking detector under construction for the absolute determination of the LHC luminosity at the ATLAS interaction point. This detector, mounted in so-called Roman Pots, will track protons elastically scattered under μrad angles at IP1.In total there are four pairs of vertically arranged detector modules which approach the LHC beam axis to mm distance. Each detector module consists of ten layers of two times 64 scintillating fibres each (U and V planes). The fibres are coupled to 64 channels Multi-Anodes PhotoMultipliers Tubes read out by compact front-end electronics. Each detector module is complemented by so-called overlap detectors: Three layers of two times 30 scintillating fibres which will be used to measure the relative positioning of two vertically arranged main detectors. The total number of channels is about 15000. Conventional plastic scintillator tiles are mounted in front of the fibre detectors and will serve as trigger counter. The extremely restricted space inside the pots makes the coupling to the read out devices very challenging. Several technologies have been tested in a beam at DESY and a cosmic-ray setup at CERN. A possible upgrade of the photo detection could consist in the replacement of the PMT by Geiger-mode avalanche photodiodes. Preliminary tests are being performed comparing the performance of these devices with the ones of the PMTs.

  10. GPS Scintillation Analysis.

    DTIC Science & Technology

    2007-11-02

    Rev. 2-89) Prescribed by ANSI Std. Z39-1 298-102 TABLE OF CONTENTS 1. INTRODUCTION 1 2. GPS COMPARISON WITH ALL-SKY IMAGES OVER AGUA VERDE...Depletions from 1 October 1994 2 3. GPS data from Agua Verde, Chile on the night of 1 October 1994 3 4. PL-SCINDA display of GPS ionospheric...comparison of GPS measurements with GOES8 L-band scintillation data, are discussed. 2. GPS COMPARISON WITH ALL-SKY IMAGES OVER AGUA VERDE, CHILE As

  11. Scintillation detector for carbon-14

    NASA Technical Reports Server (NTRS)

    Knoll, G. F.; Rogers, W. L.

    1971-01-01

    Detector consists of plastic, cylindrical double-wall scintillation cell, which is filled with gas to be analyzed. Thin, inner cell wall is isolated optically from outer (guard) scintillator wall by evaporated-aluminum coating. Bonding technique provides mechanical support to cell wall when device is exposed to high temperatures.

  12. Development of radiation hard scintillators

    SciTech Connect

    Markley, F.; Davidson, M.; Keller, J.; Foster, G.; Pla-Dalmau, A.; Harmon, J.; Biagtan, E.; Schueneman, G.; Senchishin, V.; Gustfason, H.; Rivard, M.

    1993-11-01

    The authors have demonstrated that the radiation stability of scintillators made from styrene polymer is very much improved by compounding with pentaphenyltrimethyltrisiloxane (DC 705 vacuum pump oil). The resulting scintillators are softer than desired, so they decided to make the scintillators directly from monomer where the base resin could be easily crosslinked to improve the mechanical properties. They can now demonstrate that scintillators made directly from the monomer, using both styrene and 4-methyl styrene, are also much more radiation resistant when modified with DC705 oil. In fact, they retain from 92% to 95% of their original light output after gamma irradiation to 10 Mrads in nitrogen with air annealing. When these scintillators made directly from monomer are compared with scintillators of the same composition made from polymer the latter have much higher light outputs. They commonly reach 83% while those made form monomer give only 50% to 60% relative to the reference, BC408. When oil modified scintillators using both p-terphenyl and tetraphenylbutadiene are compared with identical scintillators except that they use 3 hydroxy-flavone as the only luminophore the radiation stability is the same. However the 3HF system gives only 30% as much light as BC408 instead of 83% when both are measured with a green extended Phillips XP2081B phototube.

  13. Hybrid scintillators for neutron discrimination

    DOEpatents

    Feng, Patrick L; Cordaro, Joseph G; Anstey, Mitchell R; Morales, Alfredo M

    2015-05-12

    A composition capable of producing a unique scintillation response to neutrons and gamma rays, comprising (i) at least one surfactant; (ii) a polar hydrogen-bonding solvent; and (iii) at least one luminophore. A method including combining at least one surfactant, a polar hydrogen-bonding solvent and at least one luminophore in a scintillation cell under vacuum or an inert atmosphere.

  14. Extruding plastic scintillator at Fermilab

    SciTech Connect

    Anna Pla-Dalmau; Alan D. Bross; Victor V. Rykalin

    2003-10-31

    An understanding of the costs involved in the production of plastic scintillators and the development of a less expensive material have become necessary with the prospects of building very large plastic scintillation detectors. Several factors contribute to the high cost of plastic scintillating sheets, but the principal reason is the labor-intensive nature of the manufacturing process. In order to significantly lower the costs, the current casting procedures had to be abandoned. Since polystyrene is widely used in the consumer industry, the logical path was to investigate the extrusion of commercial-grade polystyrene pellets with dopants to yield high quality plastic scintillator. This concept was tested and high quality extruded plastic scintillator was produced. The D0 and MINOS experiments are already using extruded scintillator strips in their detectors. An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. This paper will discuss the characteristics of extruded plastic scintillator and its raw materials, the different manufacturing techniques and the current R&D program at Fermilab.

  15. Development of intrinsic IPT scintillator

    SciTech Connect

    Bross, A.D.

    1989-07-31

    We report on the development of a new polystyrene based plastic scintillator. Optical absorption, fluorescence and light output measurements are presented. Preliminary results of radiation damage effects are also given and compared to the effects on a commercial plastic scintillator, NE 110. 6 refs., 12 figs.

  16. Multiwire proportional chamber development

    NASA Technical Reports Server (NTRS)

    Doolittle, R. F.; Pollvogt, U.; Eskovitz, A. J.

    1973-01-01

    The development of large area multiwire proportional chambers, to be used as high resolution spatial detectors in cosmic ray experiments is described. A readout system was developed which uses a directly coupled, lumped element delay-line whose characteristics are independent of the MWPC design. A complete analysis of the delay-line and the readout electronic system shows that a spatial resolution of about 0.1 mm can be reached with the MWPC operating in the strictly proportional region. This was confirmed by measurements with a small MWPC and Fe-55 X-rays. A simplified analysis was carried out to estimate the theoretical limit of spatial resolution due to delta-rays, spread of the discharge along the anode wire, and inclined trajectories. To calculate the gas gain of MWPC's of different geometrical configurations a method was developed which is based on the knowledge of the first Townsend coefficient of the chamber gas.

  17. An Inexpensive Radiation Counter.

    ERIC Educational Resources Information Center

    Holton, Brian; Balla, Zsolt

    1985-01-01

    Describes a radiation counter comparable to commercial units which costs less than $100. It consists of six sections: Geiger-Mueller tube and holder; high voltage supply; low voltage supply; pulse shaping circuit; "start/stop counts" gating circuit; and counter/display. List of materials needed and schematic diagrams are included. (JN)

  18. The GlueX Start Counter

    NASA Astrophysics Data System (ADS)

    Pooser, Eric; GlueX Collaboration

    2015-03-01

    The GlueX experiment will study meson photoproduction with unprecedented precision. This experiment will use the coherent bremsstrahlung technique to produce a 9 GeV linearly polarized photon beam incident on a liquid H2 target. A Start Counter detector has been fabricated to identify the accelerator electron beam buckets, approximately 2 ns apart, and to provide accurate timing information which is used in the level-1 trigger of the experiment. This detector is designed to operate at photon intensities of up to 108 γ / s in the coherent peak and provide a timing resolution < 350 ps so as to provide successful identification of the electron beam buckets to within 99 % accuracy. Furthermore, the Start Counter detector will provide excellent solid angle coverage, ~ 90 % of 4 π hermeticity , and a high degree of segmentation for background rejection. It consists of a cylindrical array of 30 scintillators with pointed ends that bend towards the beam at the downstream end. Silicon PhotoMultiplier (SiPM) detectors have been selected as the readout system. The physical properties of the Start Counter have been studied extensively. The results of theses studies are discussed. This material is based upon work supported by the U.S. Department of Energy, Office of Science, and Office of Nuclear Physics under Contracts DE-AC05-06OR23177 & DE-FG02-99ER41065.

  19. The GlueX Start Counter

    NASA Astrophysics Data System (ADS)

    Pooser, Eric; GlueX Collaboration

    2015-04-01

    The GlueX experiment will study meson photoproduction with unprecedented precision. This experiment will use the coherent bremsstrahlung technique to produce a 9 GeV linearly polarized photon beam incident on a liquid H2 target. A Start Counter detector has been fabricated to identify the accelerator electron beam buckets, approximately 2 ns apart, and to provide accurate timing information which is used in the level-1 trigger of the experiment. This detector is designed to operate at photon intensities of up to 108 γ / s in the coherent peak and provide a timing resolution < 350ps so as to provide successful identification of the electron beam buckets to within 99 % accuracy. Furthermore, the Start Counter detector will provide excellent solid angle coverage, ~ 90 % of 4 π hermeticity , and a high degree of segmentation for background rejection. It consists of a cylindrical array of 30 scintillators with pointed ends that bend towards the beam at the downstream end. Silicon PhotoMultiplier (SiPM) detectors have been selected as the readout system. The physical properties of the Start Counter have been studied extensively. The results of theses studies are discussed. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contracts DE-AC05-06OR23177 & DE-FG02-99ER41065.

  20. Scintillation Proximity Radioimmunoassay Utilizing 125I-Labeled Ligands

    NASA Astrophysics Data System (ADS)

    Udenfriend, Sidney; Diekmann Gerber, Louise; Brink, Larry; Spector, Sydney

    1985-12-01

    A unique type of radioimmunoassay is described that does not require centrifugation or separation. Microbeads containing a fluorophor are covalently linked to antibody. When an 125I-labeled antigen is added it binds to the beads and, by its proximity, the emitted short-range electrons of the 125I excite the fluorophor in the beads. The light emitted can be measured in a standard scintillation counter. Addition of unlabeled antigen from tissue extracts displaces the labeled ligand and diminishes the fluorescent signal. Application of scintillation proximity immunoassay to tissue enkephalins, serum thyroxin, and urinary morphine is described. Applications of the principle to study the kinetics of interaction between receptors and ligands are discussed.

  1. Scintillation proximity radioimmunoassay utilizing 125I-labeled ligands

    SciTech Connect

    Udenfriend, S.; Gerber, L.D.; Brink, L.; Spector, S.

    1985-12-01

    A unique type of radioimmunoassay is described that does not require centrifugation or separation. Microbeads containing a fluorophor are covalently linked to antibody. When an /sup 125/I-labeled antigen is added it binds to the beads and, by its proximity, the emitted short-range electrons of the /sup 125/I excite the fluorophor in the beads. The light emitted can be measured in a standard scintillation counter. Addition of unlabeled antigen from tissue extracts displaces the labeled ligand and diminishes the fluorescent signal. Application of scintillation proximity immunoassay to tissue enkephalins, serum thyroxin, and urinary morphine is described. Applications of the principle to study the kinetics of interaction between receptors and ligands are discussed.

  2. A high resolution Timing Counter for the MEG II experiment

    NASA Astrophysics Data System (ADS)

    De Gerone, M.; Bevilacqua, A.; Biasotti, M.; Boca, G.; Cattaneo, P. W.; Gatti, F.; Nishimura, M.; Ootani, W.; Pizzigoni, G.; Rossella, M.; Shibata, N.; Siccardi, F.; Simonetta, M.; Uchiyama, Y.; Yoshida, K.

    2016-07-01

    The development of a Timing Counter detector designed for the MEGII upgrade of the MEG experiment, which strives to improve the sensitivity on the μ+ →e+ γ decay of an order of magnitude, is presented. It is based on two sets of counters (sectors) arranged on a semi-cylindrical structure; each sector consists of 256 counters. Each counter consists of tile of fast scintillator with a dual-side read-out based on SiPM arrays in series connection. The high granularity has two advantages: optimized size for achieving high resolution (75 ps) for the single counter, and a signal e+ crosses several counters, so that resolution improves by averaging multiple time measurements. A prototype has been built and tested both in BTF and PSI facilities in order to prove the multi-hit scheme in MEG-like beam conditions. A 35 ps resolution with eight hits has been obtained with a e+ beam at 100 kHz. The first sector will be tested in the MEG II pre-engineering run planned at the end of 2015.

  3. Samus Counter Lifting Fixture

    SciTech Connect

    Stredde, H.; /Fermilab

    1998-05-27

    A lifting fixture has been designed to handle the Samus counters. These counters are being removed from the D-zero area and will be transported off site for further use at another facility. This fixture is designed specifically for this particular application and will be transferred along with the counters. The future use of these counters may entail installation at a facility without access to a crane and therefore a lift fixture suitable for both crane and/or fork lift usage has been created The counters weigh approximately 3000 lbs. and have threaded rods extended through the counter at the top comers for lifting. When these counters were first handled/installed these rods were used in conjunction with appropriate slings and handled by crane. The rods are secured with nuts tightened against the face of the counter. The rod thread is M16 x 2({approx}.625-inch dia.) and extends 2-inch (on average) from the face of the counter. It is this cantilevered rod that the lift fixture engages with 'C' style plates at the four top comers. The strongback portion of the lift fixture is a steel rectangular tube 8-inch (vertical) x 4-inch x .25-inch wall, 130-inch long. 1.5-inch square bars are welded perpendicular to the long axis of the rectangular tube at the appropriate lift points and the 'C' plates are fastened to these bars with 3/4-10 high strength bolts -grade 8. Two short channel sections are positioned-welded-to the bottom of the rectangular tube on 40 feet centers, which are used as locators for fork lift tines. On the top are lifting eyes for sling/crane usage and are rated at 3500 lbs. safe working load each - vertical lift only.

  4. Liquid scintillator tiles for calorimetry

    SciTech Connect

    Amouzegar, M.; Belloni, A.; Bilki, B.; Calderon, J.; Barbaro, P. De; Eno, S. C.; Hatakeyama, K.; Hirschauer, J.; Jeng, G. Y.; Pastika, N. J.; Pedro, K.; Rumerio, Paolo; Samuel, J.; Sharp, E.; Shin, Y. H.; Tiras, E.; Vishnevskiy, D.; Wetzel, J.; Yang, Z.; Yao, Y.; Youn, S. W.

    2016-11-28

    Future experiments in high energy and nuclear physics may require large, inexpensive calorimeters that can continue to operate after receiving doses of 50 Mrad or more. Also, the light output of liquid scintillators suffers little degradation under irradiation. However, many challenges exist before liquids can be used in sampling calorimetry, especially regarding developing a packaging that has sufficient efficiency and uniformity of light collection, as well as suitable mechanical properties. We present the results of a study of a scintillator tile based on the EJ-309 liquid scintillator using cosmic rays and test beam on the light collection efficiency and uniformity, and some preliminary results on radiation hardness.

  5. Liquid scintillator tiles for calorimetry

    NASA Astrophysics Data System (ADS)

    Amouzegar, M.; Belloni, A.; Bilki, B.; Calderon, J.; De Barbaro, P.; Eno, S. C.; Hatakeyama, K.; Hirschauer, J.; Jeng, G. Y.; Pastika, N. J.; Pedro, K.; Rumerio, Paolo; Samuel, J.; Sharp, E.; Shin, Y. H.; Tiras, E.; Vishnevskiy, D.; Wetzel, J.; Yang, Z.; Yao, Y.; Youn, S. W.

    2016-11-01

    Future experiments in high energy and nuclear physics may require large, inexpensive calorimeters that can continue to operate after receiving doses of 50 Mrad or more. The light output of liquid scintillators suffers little degradation under irradiation. However, many challenges exist before liquids can be used in sampling calorimetry, especially regarding developing a packaging that has sufficient efficiency and uniformity of light collection, as well as suitable mechanical properties. We present the results of a study of a scintillator tile based on the EJ-309 liquid scintillator using cosmic rays and test beam on the light collection efficiency and uniformity, and some preliminary results on radiation hardness.

  6. Scintillator materials containing lanthanum fluorides

    DOEpatents

    Moses, William W.

    1991-01-01

    An improved radiation detector containing a crystalline mixture of LaF.sub.3 and CeF.sub.3 as the scintillator element is disclosed. Scintillators made with from 25% to 99.5% LaF.sub.3 and the remainder CeF.sub.3 have been found to provide a balance of good stopping power, high light yield and short decay constant that is equal to or superior to other known scintillator materials, and which may be processed from natural starting materials containing both rare earth elements. The radiation detectors disclosed are favorably suited for use in general purpose detection and in positron emission tomography.

  7. High energy resolution plastic scintillator

    NASA Astrophysics Data System (ADS)

    van Loef, Edgar V.; Feng, Patrick; Markosyan, Gary; Shirwadkar, Urmila; Doty, Patrick; Shah, Kanai S.

    2016-09-01

    In this paper we present results on a novel tin-loaded plastic scintillator. We will show that this particular plastic scintillator has a light output similar to that of BGO, a fast scintillation decay (< 10 ns), exhibits good neutron/gamma PSD with a Figure-of-Merit of 1.3 at 2.5 MeVee cut-off energy, and excellent energy resolution of about 12% (FWHM) at 662 keV. Under X-ray excitation, the radioluminescence spectrum exhibits a broad band between 350 and 500 nm peaking at 420 nm which is well-matched to bialkali photomultiplier tubes and UV-enhanced photodiodes.

  8. Ionospheric scintillation studies

    NASA Technical Reports Server (NTRS)

    Rino, C. L.; Freemouw, E. J.

    1973-01-01

    The diffracted field of a monochromatic plane wave was characterized by two complex correlation functions. For a Gaussian complex field, these quantities suffice to completely define the statistics of the field. Thus, one can in principle calculate the statistics of any measurable quantity in terms of the model parameters. The best data fits were achieved for intensity statistics derived under the Gaussian statistics hypothesis. The signal structure that achieved the best fit was nearly invariant with scintillation level and irregularity source (ionosphere or solar wind). It was characterized by the fact that more than 80% of the scattered signal power is in phase quadrature with the undeviated or coherent signal component. Thus, the Gaussian-statistics hypothesis is both convenient and accurate for channel modeling work.

  9. Properties of scintillator solutes

    SciTech Connect

    Fluornoy, J.M.

    1998-06-01

    This special report summarizes measurements of the spectroscopic and other properties of the solutes that were used in the preparation of several new liquid scintillators developed at EG and G/Energy Measurements/Santa Barbara Operations (the precursor to Bechtel Nevada/Special Technologies Laboratory) on the radiation-to-light converter program. The data on the individual compounds are presented in a form similar to that used by Prof. Isadore Berlman in his classic handbook of fluorescence spectra. The temporal properties and relative efficiencies of the new scintillators are presented in Table 1, and the efficiencies as a function of wavelength are presented graphically in Figure 1. In addition, there is a descriptive glossary of the abbreviations used herein. Figure 2 illustrates the basic structures of some of the compounds and of the four solvents reported in this summary. The emission spectra generally exhibit more structure than the absorption spectra, with the result that the peak emission wavelength for a given compound may lie several nm away from the wavelength, {lambda}{sub avg}, at the geometric center of the emission spectrum. Therefore, the author has chosen to list absorption peaks, {lambda}{sub max}, and emission {lambda}{sub avg} values in Figures 3--30, as being most illustrative of the differences between the compounds. The compounds, BHTP, BTPB, ADBT, and DPTPB were all developed on this program. P-terphenyl, PBD, and TPB are commercially available blue emitters. C-480 and the other longer-wavelength emitters are laser dyes available commercially from Exciton Corporation. 1 ref., 30 figs.

  10. Gated strip proportional detector

    DOEpatents

    Morris, Christopher L.; Idzorek, George C.; Atencio, Leroy G.

    1987-01-01

    A gated strip proportional detector includes a gas tight chamber which encloses a solid ground plane, a wire anode plane, a wire gating plane, and a multiconductor cathode plane. The anode plane amplifies the amount of charge deposited in the chamber by a factor of up to 10.sup.6. The gating plane allows only charge within a narrow strip to reach the cathode. The cathode plane collects the charge allowed to pass through the gating plane on a set of conductors perpendicular to the open-gated region. By scanning the open-gated region across the chamber and reading out the charge collected on the cathode conductors after a suitable integration time for each location of the gate, a two-dimensional image of the intensity of the ionizing radiation incident on the detector can be made.

  11. Gated strip proportional detector

    DOEpatents

    Morris, C.L.; Idzorek, G.C.; Atencio, L.G.

    1985-02-19

    A gated strip proportional detector includes a gas tight chamber which encloses a solid ground plane, a wire anode plane, a wire gating plane, and a multiconductor cathode plane. The anode plane amplifies the amount of charge deposited in the chamber by a factor of up to 10/sup 6/. The gating plane allows only charge within a narrow strip to reach the cathode. The cathode plane collects the charge allowed to pass through the gating plane on a set of conductors perpendicular to the open-gated region. By scanning the open-gated region across the chamber and reading out the charge collected on the cathode conductors after a suitable integration time for each location of the gate, a two-dimensional image of the intensity of the ionizing radiation incident on the detector can be made.

  12. Portable multiplicity counter

    DOEpatents

    Newell, Matthew R.; Jones, David Carl

    2009-09-01

    A portable multiplicity counter has signal input circuitry, processing circuitry and a user/computer interface disposed in a housing. The processing circuitry, which can comprise a microcontroller integrated circuit operably coupled to shift register circuitry implemented in a field programmable gate array, is configured to be operable via the user/computer interface to count input signal pluses receivable at said signal input circuitry and record time correlations thereof in a total counting mode, coincidence counting mode and/or a multiplicity counting mode. The user/computer interface can be for example an LCD display/keypad and/or a USB interface. The counter can include a battery pack for powering the counter and low/high voltage power supplies for biasing external detectors so that the counter can be configured as a hand-held device for counting neutron events.

  13. Development and Testing of Scintillating Detectors for the Muon g-2 Experiment

    NASA Astrophysics Data System (ADS)

    Martinez, Benjamin; Diamond, Edward; Sblendorio, Alec; Gray, Frederick

    2016-09-01

    The precise value of the muon's anomalous magnetic moment that was measured at Brookhaven National Laboratory E821 differed by more than three standard deviations from predictions of the Standard Model. The Muon g-2 Experiment at Fermilab will attain a more precise measurement by a factor of three by observing the muon spin precession frequency in a magnetic field. This improved measurement could lead to evidence of physics beyond the Standard Model. A thin-scintillator entrance (T0) counter prototype is being tested for possible use in the experiment to determine the intensity and temporal profile of the beam as it is injected into the muon storage ring. The counter is also being evaluated to determine whether it can monitor undesired particles that arrive after the main beam pulse. The unique design of the entrance counter uses a silicon photomultiplier to read the light output from a scintillator. The progress of the design of the T0 entrance counter along with the results of light output tests from a beta source and the SLAC high-energy electron beam are the primary foci of this presentation. The status of scintillating fiber harp beam monitor detectors that will also be used in the g-2 Experiment to detect the position and width of the muon beam will also be presented. This material is based upon work supported by the National Science Foundation under Grant No. PHY-1505887.

  14. Search for fractionally charged particles in the Mont Blanc LSD scintillation detector

    NASA Astrophysics Data System (ADS)

    Aglietta, M.; Antonioli, P.; Badino, G.; Castagnoli, C.; Castellina, A.; Dadykin, V. L.; Fulgione, W.; Galeotti, P.; Khalchukov, F. F.; Korolkova, E. V.; Kortchaguin, P. V.; Kortchaguin, V. B.; Kudryavtsev, V. A.; Malguin, A. S.; Marchetti, G.; Periale, L.; Ryassny, V. G.; Ryazhskaya, O. G.; Saavedra, O.; Trinchero, G. C.; Vernetto, S.; Yakushev, V. F.; Zatsepin, G. T.

    1994-02-01

    An analysis of the events recorded by the Mont Blanc Neutrino Scintillation Detector was performed in order to search for fractionally charged particles with |Q| = 1/3and |Q| = 2/3. In a live time of 2378 days, the obtained 90% C. L. upper limits on the fluxes of fractionally charged particles in the core of our detector are Φ(|Q| = 1/3) < 2. 3 10 -13cm-2s-1sr-1and Φ(|Q| = 2/3) < 2. 7 10 -13cm-2s-1sr-1, the best available limits obtained by scintillation counters technique.

  15. Comparison of a designed virtual counter with a real counter

    NASA Astrophysics Data System (ADS)

    Tektas, G.; Celiktas, C.

    2017-02-01

    A counter is a device which counts the incident pulses within a fixed time. In this work, a virtual counter was designed by developing a code by LabVIEW software. Generator signals were sent to the virtual counter via a National Instruments multifunction data acquisition device. Analog and PFI (Programmable Function Interface) inputs of the device was used for the process. A real counter was also used for comparison. Counts acquired from both counters in different time intervals were compared with each other. It was concluded from the obtained results that the developed virtual counter could be used as a real counter.

  16. Neutron crosstalk between liquid scintillators

    DOE PAGES

    Verbeke, J. M.; Prasad, M. K.; Snyderman, N. J.

    2015-05-01

    We propose a method to quantify the fractions of neutrons scattering between liquid scintillators. Using a spontaneous fission source, this method can be utilized to quickly characterize an array of liquid scintillators in terms of crosstalk. The point model theory due to Feynman is corrected to account for these multiple scatterings. Using spectral information measured by the liquid scintillators, fractions of multiple scattering can be estimated, and mass reconstruction of fissile materials under investigation can be improved. Monte Carlo simulations of mono-energetic neutron sources were performed to estimate neutron crosstalk. A californium source in an array of liquid scintillators wasmore » modeled to illustrate the improvement of the mass reconstruction.« less

  17. About NICADD extruded scintillating strips

    SciTech Connect

    Dyshkant, A.; Beznosko, D.; Blazey, G.; Chakraborty, D.; Francis, K.; Kubik, D.; Lima, J.G.; Rykalin, V.; Zutshi, v.; Baldina, E.; Bross, A.; Deering, P.; Nebel, T.; Pla-Dalmau, A.; Schellpfeffer, J.; Serritella, C.; Zimmerman, J.; /Fermilab

    2005-04-01

    The results of control measurements of extruded scintillating strip responses to a radioactive source Sr-90 are provided, and details of strip choice, preparation, and method of measurement are included. About four hundred one meter long extruded scintillating strips were measured at four different points. These results were essential for prototyping a tail catcher and muon tracker for a future international electron positron linear collider detector.

  18. Response of organic liquid scintillators to fast neutrons and gamma radiation

    NASA Astrophysics Data System (ADS)

    Hoertz, Paul G.; Mills, Karmann; Davis, Lynn; Baldasaro, Nicholas; Gupta, Vijay

    2013-03-01

    Liquid organic scintillators are cocktails of aromatic fluorophores in an aromatic solvent. They find widespread use in Liquid Scintillation Counters with applications in medical diagnostics as well as fundamental nuclear and particle physics. Ultima Gold™ XR, a commercially available organic liquid scintillator from Perkin Elmer, can be used in both aqueous and non-aqueous systems and is typically used for beta detection in medical diagnostics. Its performance under gamma radiation and neutron radiation is less well-characterized. Special and normal Ultima Gold™ XR liquid scintillators were exposed in separate experiments to fast neutrons and high energy photons from a nuclear reactor and to gamma rays from a Co-60 source. To perform the measurements in the radiation chamber, a custom light collection system consisting of a fiber optic cable, spectrometer and a diffuse reflecting optical cavity was fabricated. Advanced calibration procedures, traceable to NIST standards, were developed to determine photon fluxes and flux densities of the scintillators under ionizing radiation conditions. The scintillator emission spectra under gamma radiation from a Co-60 source and neutron radiation from a pool-type nuclear reactor were recorded and compared. Results on the spectrometer design and comparison of the spectra under different exposure are presented.

  19. Extruded plastic scintillator including inorganic powders

    DOEpatents

    Bross, Alan D.; Mellott, Kerry L.; Pla-Dalmau, Anna

    2006-06-27

    A method for producing a plastic scintillator is disclosed. A plurality of nano-sized particles and one or more dopants can be combined with a plastic material for the formation of a plastic scintillator thereof. The nano-sized particles, the dopant and the plastic material can be combined within the dry inert atmosphere of an extruder to produce a reaction that results in the formation of a plastic scintillator thereof and the deposition of energy within the plastic scintillator, such that the plastic scintillator produces light signifying the detection of a radiative element. The nano-sized particles can be treated with an inert gas prior to processing the nano-sized particles, the dopant and the plastic material utilizing the extruder. The plastic scintillator can be a neutron-sensitive scintillator, x-ray sensitive scintillator and/or a scintillator for the detection of minimum ionizing particles.

  20. Development of a new scintillation-trigger detector for the MTV experiment using aluminum-metallized film tape

    NASA Astrophysics Data System (ADS)

    Sakamoto, Yuko; Ozaki, Sachi; Tanaka, Saki; Tanuma, Ryosuke; Yoshida, Tatsuru; Murata, Jiro

    2014-09-01

    A new type of trigger-scintillation counter array designed for the MTV experiment at TRIUMF-ISAC has been developed, using aluminum-metallized film tape for wrapping. The MTV experiment aims to perform the finest precision test of time reversal symmetry in nuclear beta decay. In that purpose, we search non-zero T-Violating transverse polarization of electrons emitted from polarized Li-8 nuclei. It uses a cylindrical drift chamber (CDC) as the main electron-tracking detector. The trigger-scintillation counter consists of 12-segmented 1 mm thick 300 mm long thin plastic scintillation counters. This counter is placed inside the CDC to generate a trigger signal. The required assembling precision of +-0.5 mm was a tricky point when we tried to use conventional total reflection mode. Indeed, produce an air-layer surrounding the scintillating bar to keep good light transmission was the main issue. For this reason, we tried to use a new wrapping material made of metallized-aluminum tape, which has a good mirror-like reflecting surface on both sides of the tape. Through this report, we will compare detection efficiency and light attenuation between conventional and new wrapping materials.

  1. An alpha–gamma coincidence spectrometer based on the Photon–Electron Rejecting Alpha Liquid Scintillation (PERALS®) system

    DOE PAGES

    Cadieux, J. R.; Fugate, G. A.; King, III, G. S.

    2015-02-07

    Here, an alpha–gamma coincidence spectrometer has been developed for the measurement of selected actinide isotopes in the presence of high beta/gamma fields. The system is based on a PERALS® liquid scintillation counter for beta/alpha discrimination and was successfully tested with both high purity germanium and bismuth germanate, gamma-ray detectors using conventional analog electronics.

  2. Liquid argon scintillation light studies in LArIAT

    SciTech Connect

    Kryczynski, Pawel

    2016-10-12

    The LArIAT experiment is using its Liquid Argon Time Projection Chamber (LArTPC) in the second run of data-taking at the Fermilab Test Beam Facility. The goal of the experiment is to study the response of LArTPCs to charged particles of energies relevant for planned neutrino experiments. In addition, it will help to develop and evaluate the performance of the simulation, analysis, and reconstruction software used in other LAr neutrino experiments. Particles from a tertiary beam detected by LArIAT (mainly protons, pions and muons) are identified using a set of beamline detectors, including Wire Chambers, Time of Flight counters and Cherenkov counters, as well as a simplified sampling detector used to detect muons. In its effort towards augmenting LArTPC technology for other neutrino experiments, LArIAT also takes advantage of the scintillating capabilities of LAr and is testing the possibility of using the light signal to help reconstruct calorimetric information and particle ID. In this report, we present results from these studies of the scintillation light signal to evaluate detector performance and calorimetry.

  3. Introduction to Neutron Coincidence Counter Design Based on Boron-10

    SciTech Connect

    Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Siciliano, Edward R.

    2012-01-22

    The Department of Energy Office of Nonproliferation Policy (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is ultimately to design, build and demonstrate a boron-lined proportional tube based alternative system in the configuration of a coincidence counter. This report, providing background information for this project, is the deliverable under Task 1 of the project.

  4. First-principles Electronic Structure Calculations for Scintillation Phosphor Nuclear Detector Materials

    NASA Astrophysics Data System (ADS)

    Canning, Andrew

    2013-03-01

    Inorganic scintillation phosphors (scintillators) are extensively employed as radiation detector materials in many fields of applied and fundamental research such as medical imaging, high energy physics, astrophysics, oil exploration and nuclear materials detection for homeland security and other applications. The ideal scintillator for gamma ray detection must have exceptional performance in terms of stopping power, luminosity, proportionality, speed, and cost. Recently, trivalent lanthanide dopants such as Ce and Eu have received greater attention for fast and bright scintillators as the optical 5d to 4f transition is relatively fast. However, crystal growth and production costs remain challenging for these new materials so there is still a need for new higher performing scintillators that meet the needs of the different application areas. First principles calculations can provide a useful insight into the chemical and electronic properties of such materials and hence can aid in the search for better new scintillators. In the past there has been little first-principles work done on scintillator materials in part because it means modeling f electrons in lanthanides as well as complex excited state and scattering processes. In this talk I will give an overview of the scintillation process and show how first-principles calculations can be applied to such systems to gain a better understanding of the physics involved. I will also present work on a high-throughput first principles approach to select new scintillator materials for fabrication as well as present more detailed calculations to study trapping process etc. that can limit their brightness. This work in collaboration with experimental groups has lead to the discovery of some new bright scintillators. Work supported by the U.S. Department of Homeland Security and carried out under U.S. Department of Energy Contract no. DE-AC02-05CH11231 at Lawrence Berkeley National Laboratory.

  5. Cerium-activated rare-earth orthophosphate and double-phosphate scintillators for x-and gamma-ray detection

    SciTech Connect

    Boatner, Lynn A; Keefer, Lara A; Farmer, James Matthew; Wisniewski, D.; Wojtowicz, A. J.

    2004-01-01

    When activated with an appropriate rare-earth ion (e.g., Ce or Nd), rare-earth orthophosphates of the form REPO4 (where RE = a rare-earth cation) and alkali rare-earth double phosphates of the form A{sub 3}RE(PO{sub 4}){sub 2} (where A = K, Rb, or Cs) are characterized by light yields and decay times that make these materials of interest for radiation-detection applications. Crystals of the compound Rb{sub 3}Lu(PO{sub 4}){sub 2} when activated with {approx}0.1 mol % Ce exhibit a light yield that is {approx}250% that of BGO with a decay time on the order of {approx}40 nsec. The cerium-activated rare-earth orthophosphate LuPO{sub 4}:Ce is also characterized by a high light yield and a relatively fast decay time of {approx}25 nsec. Additionally, the rare-earth orthophosphates are extremely chemically, physically, and thermally durable hosts that recover easily from radiation damage effects. The properties of the rare-earth orthophosphates and double phosphates that pertain to their use as X- and gamma-ray detectors are reviewed. This review includes information related to the use of Nd-doped LuPO{sub 4} as a scintillator with a sufficiently energetic, short-wavelength output ({lambda} = 90 nm) so that it can be used in conjunction with appropriately activated proportional counters. Information is presented on the details of the synthesis, structure, and luminescence properties of lanthanide double phosphates that, when activated with cerium, are efficient scintillators with output wavelengths that are sufficiently long to be well matched to the response of silicon photodiode detectors.

  6. Compressor surge counter

    DOEpatents

    Castleberry, Kimberly N.

    1983-01-01

    A surge counter for a rotating compressor is provided which detects surging by monitoring the vibration signal from an accelerometer mounted on the shaft bearing of the compressor. The circuit detects a rapid increase in the amplitude envelope of the vibration signal, e.g., 4 dB or greater in less than one second, which is associated with a surge onset and increments a counter. The circuit is rendered non-responsive for a period of about 5 seconds following the detection which corresponds to the duration of the surge condition. This prevents multiple registration of counts during the surge period due to rapid swings in vibration amplitude during the period.

  7. Counter-propeller

    NASA Technical Reports Server (NTRS)

    De Caria, Ugo

    1931-01-01

    A counter-propeller is a fixed propeller smaller than the main propeller, mounted either fore or aft of the latter and performing the function of changing the direction of motion of the fluid filaments, which naturally tend to adopt a helicoidal form. This paper presents a consideration of the real advantage of counter-propellers on aircraft and the best shape of the blades. First, the author determines the possible energy absorption by the tangential increments. This process will be facilitated by the examination of the polygons of the relative velocities fore and aft of the generic section, of radius r, of one of the blades of the propeller.

  8. Molecular origins of scintillation in organic scintillators (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Feng, Patrick; Mengesha, Wondwosen; Myllenbeck, Nicholas

    2016-09-01

    Organic-based scintillators are indispensable materials for radiation detection owing to their high sensitivity to fast neutrons, low cost, and tailorable properties. There has been a recent resurgence of interest in organic scintillators due to exciting discoveries related to neutron discrimination and gamma-ray spectroscopy, which represent capabilities previously thought not possible in these materials. I will discuss our development of crystalline and polymer-based scintillators for these applications. Structure-property relationships related to intermolecular interactions and host-guest electronic exchange will be discussed in the context of energy-transfer pathways relevant to scintillation. An emphasis will be placed on the rational design of these materials, as guided by first principles and DFT calculations. Two related topics will be discussed: 1) Incorporation of organometallic triplet-harvesting additives to plastic scintillator matrices to confer a 'two-state' (singlet and triplet) luminescence signature to different types of ionizing radiation. This approach relies upon energetic and spatial overlap between the donor and acceptor excited states for efficient electronic exchange. Key considerations also include synthetic modification of the luminescence spectra and kinetics, as well as the addition of secondary additives to increase the recombination efficiency. 2) Design of organotin-containing plastic scintillators as a route towards gamma-ray spectroscopy. Organometallic compounds were selected on the basis of distance-dependent quenching relationships, phase compatibility with the polymer matrix, and the gamma-ray cross sections. This approach is guided by molecular modeling and radiation transport modeling to achieve the highest possible detection sensitivity luminescence intensity.

  9. FNAL-NICADD extruded scintillator

    SciTech Connect

    Beznosko, D.; Bross, A.; Dyshkant, A.; Pla-Dalmau, A.; Rykalin, V.; /Northern Illinois U.

    2005-09-01

    The possibility to produce a scintillator that satisfies the demands of physicists from different science areas has emerged with the installation of an extrusion line at Fermi National Accelerator Laboratory (FNAL). The extruder is the product of the fruitful collaboration between FNAL and Northern Illinois Center for Accelerator and Detector Development (NICADD) at Northern Illinois University (NIU). The results from the light output, light attenuation length and mechanical tolerance indicate that FNAL-NICADD scintillator is of high quality. Improvements in the extrusion die will yield better scintillator profiles and decrease the time needed for initial tuning. This paper will present the characteristics of the FNAL-NICADD scintillator based on the measurements performed. They include the response to MIPs from cosmic rays for individual extruded strips and irradiation studies where extruded samples were irradiated up to 1 Mrad. We will also discuss the results achieved with a new die design. The attractive perspective of using the extruded scintillator with MRS (Metal Resistive Semiconductor) photodetector readout will also be shown.

  10. Scintillation Characterization of Doped Cesium Hafnium Chloride (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Rowe, Emmanuel; Goodwin, Brandon; Bhattacharya, Pijush; Burger, Arnold; Stowe, Ashley; Cherepy, Nerine; Payne, Steve

    2016-09-01

    The scintillators currently providing the best energy resolution lower than 2.6% at 662 keV and sizes larger than 1 in. dia. 1 in. height are LaBr3(Ce) and SrI2(Eu). Despite energy resolution and decay time performance of LaBr3(Ce), the intrinsic radioactivity, due to naturally occurring 138La isotope in the matrix is a limitation for low count rate applications such as radioisotope identification of weak sources. Cesium Hafnium Chloride (CHC) is a high effective atomic number (Zeff=58) moderate density (3.86 g/cm3) scintillator for gamma spectroscopy, offering a cubic crystal structure, no intrinsic radioactivity, and highly proportional light yield, without intentional doping. CHC boasts a cubic crystal structure that is isostructural to K2HfCl6 and analogous to calcium fluoride with cesium ions in the fluorine ion position and the [HfCl6]2- octahedral replacing calcium ions. The scintillation of CHC is centered at 400 nm, with a principal decay time of 4.37 μs, a light yield of up to 54,000 photons/MeV and energy resolution of 3.3% at 662 keV and we report on the effects of doping on the scintillation properties of CHC.

  11. Neutron counter based on beryllium activation

    SciTech Connect

    Bienkowska, B.; Prokopowicz, R.; Kaczmarczyk, J.; Paducha, M.; Scholz, M.; Igielski, A.; Karpinski, L.; Pytel, K.

    2014-08-21

    The fusion reaction occurring in DD plasma is followed by emission of 2.45 MeV neutrons, which carry out information about fusion reaction rate and plasma parameters and properties as well. Neutron activation of beryllium has been chosen for detection of DD fusion neutrons. The cross-section for reaction {sup 9}Be(n, α){sup 6}He has a useful threshold near 1 MeV, which means that undesirable multiple-scattered neutrons do not undergo that reaction and therefore are not recorded. The product of the reaction, {sup 6}He, decays with half-life T{sub 1/2} = 0.807 s emitting β{sup −} particles which are easy to detect. Large area gas sealed proportional detector has been chosen as a counter of β–particles leaving activated beryllium plate. The plate with optimized dimensions adjoins the proportional counter entrance window. Such set-up is also equipped with appropriate electronic components and forms beryllium neutron activation counter. The neutron flux density on beryllium plate can be determined from the number of counts. The proper calibration procedure needs to be performed, therefore, to establish such relation. The measurements with the use of known β–source have been done. In order to determine the detector response function such experiment have been modeled by means of MCNP5–the Monte Carlo transport code. It allowed proper application of the results of transport calculations of β{sup −} particles emitted from radioactive {sup 6}He and reaching proportional detector active volume. In order to test the counter system and measuring procedure a number of experiments have been performed on PF devices. The experimental conditions have been simulated by means of MCNP5. The correctness of simulation outcome have been proved by measurements with known radioactive neutron source. The results of the DD fusion neutron measurements have been compared with other neutron diagnostics.

  12. Radiopure metal-loaded liquid scintillator

    SciTech Connect

    Rosero, Richard; Yeh, Minfang

    2015-08-17

    Metal-loaded liquid scintillator plays a key role in particle and nuclear physics experiments. The applications of metal ions in various neutrino experiments and the purification methods for different scintillator components are discussed in this paper.

  13. Radiopure Metal-Loaded Liquid Scintillator

    SciTech Connect

    Rosero, Richard; Yeh, Minfang

    2015-03-18

    Metal-loaded liquid scintillator plays a key role in particle and nuclear physics experiments. The applications of metal ions in various neutrino experiments and the purification methods for different scintillator components are discussed in this paper.

  14. Advances in scintillators for medical imaging applications

    NASA Astrophysics Data System (ADS)

    van Loef, Edgar V.; Shah, Kanai S.

    2014-09-01

    A review is presented of some recent work in the field of inorganic scintillator research for medical imaging applications, in particular scintillation detectors for Single-Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET).

  15. Visual Manipulatives for Proportional Reasoning.

    ERIC Educational Resources Information Center

    Moore, Joyce L.; Schwartz, Daniel L.

    The use of a visual representation in learning about proportional relations was studied, examining students' understandings of the invariance of a multiplicative relation on both sides of a proportion equation and the invariance of the structural relations that exist in different semantic types of proportion problems. Subjects were 49 high-ability…

  16. Hybrid shower counter for CDF

    SciTech Connect

    Nodulman, L.

    1980-01-01

    A hybrid scintillator/strip chamber electromagnetic calorimeter has been proposed for the Collider Detector Facility at Fermilab. Large modules of lead/scintillator with wavebar readout are to contain one or more bidimensional wire chambers near shower maximum. Results of the ongoing program of computer simulation and prototype testing are discussed.

  17. Scintillation-Hardened GPS Receiver

    NASA Technical Reports Server (NTRS)

    Stephens, Donald R.

    2015-01-01

    CommLargo, Inc., has developed a scintillation-hardened Global Positioning System (GPS) receiver that improves reliability for low-orbit missions and complies with NASA's Space Telecommunications Radio System (STRS) architecture standards. A software-defined radio (SDR) implementation allows a single hardware element to function as either a conventional radio or as a GPS receiver, providing backup and redundancy for platforms such as the International Space Station (ISS) and high-value remote sensing platforms. The innovation's flexible SDR implementation reduces cost, weight, and power requirements. Scintillation hardening improves mission reliability and variability. In Phase I, CommLargo refactored an open-source GPS software package with Kalman filter-based tracking loops to improve performance during scintillation and also demonstrated improved navigation during a geomagnetic storm. In Phase II, the company generated a new field-programmable gate array (FPGA)-based GPS waveform to demonstrate on NASA's Space Communication and Navigation (SCaN) test bed.

  18. Liquid scintillator tiles for calorimetry

    DOE PAGES

    Amouzegar, M.; Belloni, A.; Bilki, B.; ...

    2016-11-28

    Future experiments in high energy and nuclear physics may require large, inexpensive calorimeters that can continue to operate after receiving doses of 50 Mrad or more. Also, the light output of liquid scintillators suffers little degradation under irradiation. However, many challenges exist before liquids can be used in sampling calorimetry, especially regarding developing a packaging that has sufficient efficiency and uniformity of light collection, as well as suitable mechanical properties. We present the results of a study of a scintillator tile based on the EJ-309 liquid scintillator using cosmic rays and test beam on the light collection efficiency and uniformity,more » and some preliminary results on radiation hardness.« less

  19. Unitary scintillation detector and system

    DOEpatents

    McElhaney, Stephanie A.; Chiles, Marion M.

    1994-01-01

    The invention is a unitary alpha, beta, and gamma scintillation detector and system for sensing the presence of alpha, beta, and gamma radiations selectively or simultaneously. The scintillators are mounted in a light-tight housing provided with an entrance window for admitting alpha, beta, and gamma radiation and excluding ambient light from the housing. Light pulses from each scintillator have different decay constants that are converted by a photosensitive device into corresponding differently shaped electrical pulses. A pulse discrimination system identifies the electrical pulses by their respective pulse shapes which are determined by decay time. The identified electrical pulses are counted in separate channel analyzers to indicate the respective levels of sensed alpha, beta, and gamma radiations.

  20. Unitary scintillation detector and system

    DOEpatents

    McElhaney, S.A.; Chiles, M.M.

    1994-05-31

    The invention is a unitary alpha, beta, and gamma scintillation detector and system for sensing the presence of alpha, beta, and gamma radiations selectively or simultaneously. The scintillators are mounted in a light-tight housing provided with an entrance window for admitting alpha, beta, and gamma radiation and excluding ambient light from the housing. Light pulses from each scintillator have different decay constants that are converted by a photosensitive device into corresponding differently shaped electrical pulses. A pulse discrimination system identifies the electrical pulses by their respective pulse shapes which are determined by decay time. The identified electrical pulses are counted in separate channel analyzers to indicate the respective levels of sensed alpha, beta, and gamma radiations. 10 figs.

  1. Fracture-resistant lanthanide scintillators

    DOEpatents

    Doty, F. Patrick

    2011-01-04

    Lanthanide halide alloys have recently enabled scintillating gamma ray spectrometers comparable to room temperature semiconductors (<3% FWHM energy resolutions at 662 keV). However brittle fracture of these materials upon cooling hinders the growth of large volume crystals. Efforts to improve the strength through non-lanthanide alloy substitution, while preserving scintillation, have been demonstrated. Isovalent alloys having nominal compositions of comprising Al, Ga, Sc, Y, and In dopants as well as aliovalent alloys comprising Ca, Sr, Zr, Hf, Zn, and Pb dopants were prepared. All of these alloys exhibit bright fluorescence under UV excitation, with varying shifts in the spectral peaks and intensities relative to pure CeBr.sub.3. Further, these alloys scintillate when coupled to a photomultiplier tube (PMT) and exposed to .sup.137Cs gamma rays.

  2. Development of radiation hard scintillators

    SciTech Connect

    Markley, F.; Woods, D.; Pla-Dalmau, A.; Foster, G. ); Blackburn, R. )

    1992-05-01

    Substantial improvements have been made in the radiation hardness of plastic scintillators. Cylinders of scintillating materials 2.2 cm in diameter and 1 cm thick have been exposed to 10 Mrads of gamma rays at a dose rate of 1 Mrad/h in a nitrogen atmosphere. One of the formulations tested showed an immediate decrease in pulse height of only 4% and has remained stable for 12 days while annealing in air. By comparison a commercial PVT scintillator showed an immediate decrease of 58% and after 43 days of annealing in air it improved to a 14% loss. The formulated sample consisted of 70 parts by weight of Dow polystyrene, 30 pbw of pentaphenyltrimethyltrisiloxane (Dow Corning DC 705 oil), 2 pbw of p-terphenyl, 0.2 pbw of tetraphenylbutadiene, and 0.5 pbw of UVASIL299LM from Ferro.

  3. Electromagnetically Operated Counter

    DOEpatents

    Goldberg, H D; Goldberg, M I

    1951-12-18

    An electromagnetically operated counter wherein signals to be counted are applied to cause stepwise rotation of a rotatable element which is connected to a suitable register. The mechanism involved consists of a rotatable armature having three spaced cores of magnetic material and a pair of diametrically opposed electromagnets with a suitable pulsing circuit to actuate the magnets.

  4. Nanophosphor composite scintillator with a liquid matrix

    DOEpatents

    McKigney, Edward Allen; Burrell, Anthony Keiran; Bennett, Bryan L.; Cooke, David Wayne; Ott, Kevin Curtis; Bacrania, Minesh Kantilal; Del Sesto, Rico Emilio; Gilbertson, Robert David; Muenchausen, Ross Edward; McCleskey, Thomas Mark

    2010-03-16

    An improved nanophosphor scintillator liquid comprises nanophosphor particles in a liquid matrix. The nanophosphor particles are optionally surface modified with an organic ligand. The surface modified nanophosphor particle is essentially surface charge neutral, thereby preventing agglomeration of the nanophosphor particles during dispersion in a liquid scintillator matrix. The improved nanophosphor scintillator liquid may be used in any conventional liquid scintillator application, including in a radiation detector.

  5. Hygroscopicity Evaluation of Halide Scintillators

    SciTech Connect

    Zhuravleva, M; Stand, L; Wei, H; Hobbs, C. L.; Boatner, Lynn A; Ramey, Joanne Oxendine; Burger, Arnold; Rowe, E; Bhattacharya, P.; Tupitsyn, E; Melcher, Charles L

    2014-01-01

    A collaborative study of relative hygroscopicity of anhydrous halide scintillators grown at various laboratories is presented. We have developed a technique to evaluate moisture sensitivity of both raw materials and grown crystals, in which the moisture absorption rate is measured using a gravimetric analysis. Degradation of the scintillation performance was investigated by recording gamma-ray spectra and monitoring the photopeak position, count rate and energy resolution. The accompanying physical degradation of the samples exposed to ambient atmosphere was photographically recorded as well. The results were compared with ben

  6. Characteristics of High Latitude Ionosphere Scintillations

    NASA Astrophysics Data System (ADS)

    Morton, Y.

    2012-12-01

    As we enter a new solar maximum period, global navigation satellite systems (GNSS) receivers, especially the ones operating in high latitude and equatorial regions, are facing an increasing threat from ionosphere scintillations. The increased solar activities, however, also offer a great opportunity to collect scintillation data to characterize scintillation signal parameters and ionosphere irregularities. While there are numerous GPS receivers deployed around the globe to monitor ionosphere scintillations, most of them are commercial receivers whose signal processing mechanisms are not designed to operate under ionosphere scintillation. As a result, they may distort scintillation signal parameters or lose lock of satellite signals under strong scintillations. Since 2008, we have established and continuously improved a unique GNSS receiver array at HAARP, Alaska. The array contains high ends commercial receivers and custom RF front ends which can be automatically triggered to collect high quality GPS and GLONASS satellite signals during controlled heating experiments and natural scintillation events. Custom designed receiver signal tracking algorithms aim to preserve true scintillation signatures are used to process the raw RF samples. Signal strength, carrier phase, and relative TEC measurements generated by the receiver array since its inception have been analyzed to characterize high latitude scintillation phenomena. Daily, seasonal, and solar events dependency of scintillation occurrence, spectral contents of scintillation activities, and plasma drifts derived from these measurements will be presented. These interesting results demonstrate the feasibility and effectiveness of our experimental data collection system in providing insightful details of ionosphere responses to active perturbations and natural disturbances.

  7. Composite scintillators for detection of ionizing radiation

    DOEpatents

    Dai, Sheng [Knoxville, TN; Stephan, Andrew Curtis [Knoxville, TN; Brown, Suree S [Knoxville, TN; Wallace, Steven A [Knoxville, TN; Rondinone, Adam J [Knoxville, TN

    2010-12-28

    Applicant's present invention is a composite scintillator having enhanced transparency for detecting ionizing radiation comprising a material having optical transparency wherein said material comprises nano-sized objects having a size in at least one dimension that is less than the wavelength of light emitted by the composite scintillator wherein the composite scintillator is designed to have selected properties suitable for a particular application.

  8. Photonic crystal scintillators and methods of manufacture

    SciTech Connect

    Torres, Ricardo D.; Sexton, Lindsay T.; Fuentes, Roderick E.; Cortes-Concepcion, Jose

    2015-08-11

    Photonic crystal scintillators and their methods of manufacture are provided. Exemplary methods of manufacture include using a highly-ordered porous anodic alumina membrane as a pattern transfer mask for either the etching of underlying material or for the deposition of additional material onto the surface of a scintillator. Exemplary detectors utilizing such photonic crystal scintillators are also provided.

  9. Auger recombination in scintillator materials from first principles

    NASA Astrophysics Data System (ADS)

    McAllister, Andrew; Kioupakis, Emmanouil; Åberg, Daniel; Schleife, André

    2015-03-01

    Scintillators convert high energy radiation into lower energy photons which are easier to detect and analyze. One of the uses of these devices is identifying radioactive materials being transported across national borders. However, scintillating materials have a non-proportional light yield in response to incident radiation, which makes this task difficult. One possible cause of the non-proportional light yield is non-radiative Auger recombination. Auger recombination can occur in two ways - direct and phonon-assisted. We have studied both types of Auger recombination from first principles in the common scintillating material sodium iodide. Our results indicate that the phonon-assisted process, assisted primarily by short-range optical phonons, dominates the direct process. The corresponding Auger coefficients are 5 . 6 +/- 0 . 3 ×10-32cm6s-1 for the phonon-assisted process versus 1 . 17 +/- 0 . 01 ×10-33cm6s-1 for the direct process. At higher electronic temperatures the direct Auger recombination rate increases but remains lower than the phonon-assisted rate. This research was supported by the National Science Foundation CAREER award through Grant No. DMR-1254314 and NA-22. Computational Resources provide by LLNL and DOE NERSC Facility.

  10. Synthesis of plastic scintillation microspheres: Evaluation of scintillators

    NASA Astrophysics Data System (ADS)

    Santiago, L. M.; Bagán, H.; Tarancón, A.; Garcia, J. F.

    2013-01-01

    The use of plastic scintillation microspheres (PSm) appear to be an alternative to liquid scintillation for the quantification of alpha and beta emitters because it does not generate mixed wastes after the measurement (organic and radioactive). In addition to routine radionuclide determinations, PSm can be used for further applications, e.g. for usage in a continuous monitoring equipment, for measurements of samples with a high salt concentration and for an extractive scintillation support which permits the separation, pre-concentration and measurement of the radionuclides without additional steps of elution and sample preparation. However, only a few manufacturers provide PSm, and the low number of regular suppliers reduces its availability and restricts the compositions and sizes available. In this article, a synthesis method based on the extraction/evaporation methodology has been developed and successfully used for the synthesis of plastic scintillation microspheres. Seven different compositions of plastic scintillation microspheres have been synthesised; PSm1 with polystyrene, PSm2 with 2,5-Diphenyloxazol(PPO), PSm3 with p-terphenyl (pT), PSm4 with PPO and 1,4-bis(5-phenyloxazol-2-yl) (POPOP), PSm5 pT and (1,4-bis [2-methylstyryl] benzene) (Bis-MSB), PSm6 with PPO, POPOP and naphthalene and PSm7 with pT, Bis-MSB and naphthalene. The synthesised plastic scintillation microspheres have been characterised in terms of their morphology, detection capabilities and alpha/beta separation capacity. The microspheres had a median diameter of approximately 130 μm. Maximum detection efficiency values were obtained for the PSm4 composition as follows 1.18% for 3H, 51.2% for 14C, 180.6% for 90Sr/90Y and 76.7% for 241Am. Values of the SQP(E) parameter were approximately 790 for PSm4 and PSm5. These values show that the synthesised PSm exhibit good scintillation properties and that the spectra are at channel numbers higher than in commercial PSm. Finally, the addition of

  11. Performance of Large Neutron Detectors Containing Lithium-Gadolinium-Borate Scintillator

    SciTech Connect

    Slaughter, David M.; Stuart, Cory R.; Klaass, R. Fred; Merrill, David B.

    2015-07-01

    This paper describes the development and testing of a neutron counter, spectrometer, and dosimeter that is compact, efficient, and accurate. A self-contained neutron detection instrument has wide applications in health physics, scientific research, and programs to detect, monitor, and control strategic nuclear materials (SNM). The 1.3 liter detector head for this instrument is a composite detector with an organic scintillator containing uniformly distributed {sup 6}Li{sub 6}{sup nat}Gd{sup 10}B{sub 3}O{sub 9}:Ce (LGB:Ce) microcrystals. The plastic scintillator acts to slow impinging neutrons and emits light proportional to the energy lost by the neutrons as they moderate in the detector body. Moderating neutrons that have slowed sufficiently capture in one of the Lithium-6, Boron-10, or Gadolinium-157 atoms in the LGB:Ce scintillator, which then releases the capture energy in a characteristic cerium emission pulse. The measured captured pulses indicate the presence of neutrons. When a scintillating fluor is present in the plastic, the light pulse resulting from the neutron moderating in the plastic is paired with the LGB:Ce capture pulse to identify the energy of the neutron. About 2% of the impinging neutrons lose all of their energy in a single collision with the detector. There is a linear relationship between the pulse areas of this group of neutrons and energy. The other 98% of neutrons have a wide range of collision histories within the detector body. When these neutrons are 'binned' into energy groups, each group contains a distribution of pulse areas. This data was used to assist in the unfolding of the neutron spectra. The unfolded spectra were then validated with known spectra, at both neutron emitting isotopes and fission/accelerator facilities. Having validated spectra, the dose equivalent and dose rate are determined by applying standard, regulatory damage coefficients to the measured neutron counts for each energy bin of the spectra. Testing at the

  12. Extruded plastic scintillator for MINERvA

    SciTech Connect

    Pla-Dalmau, Anna; Bross, Alan D.; Rykalin, Victor V.; Wood, Brian M.; /NICADD, DeKalb

    2005-11-01

    An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. Since polystyrene is widely used in the consumer industry, the logical path was to investigate the extrusion of commercial-grade polystyrene pellets with dopants to yield high quality plastic scintillator. The D0 and MINOS experiments are already using extruded scintillator strips in their detectors. A new experiment at Fermilab is pursuing the use of extruded plastic scintillator. A new plastic scintillator strip is being tested and its properties characterized. The initial results are presented here.

  13. Auger recombination in sodium-iodide scintillators from first principles

    NASA Astrophysics Data System (ADS)

    McAllister, Andrew; Åberg, Daniel; Schleife, André; Kioupakis, Emmanouil

    2015-04-01

    Scintillator radiation detectors suffer from low energy resolution that has been attributed to non-linear light yield response to the energy of the incident gamma rays. Auger recombination is a key non-radiative recombination channel that scales with the third power of the excitation density and may play a role in the non-proportionality problem of scintillators. In this work, we study direct and phonon-assisted Auger recombination in NaI using first-principles calculations. Our results show that phonon-assisted Auger recombination, mediated primarily by short-range phonon scattering, dominates at room temperature. We discuss our findings in light of the much larger values obtained by numerical fits to z-scan experiments.

  14. Auger recombination in sodium-iodide scintillators from first principles

    SciTech Connect

    McAllister, Andrew; Åberg, Daniel; Schleife, André; Kioupakis, Emmanouil

    2015-04-06

    Scintillator radiation detectors suffer from low energy resolution that has been attributed to non-linear light yield response to the energy of the incident gamma rays. Auger recombination is a key non-radiative recombination channel that scales with the third power of the excitation density and may play a role in the non-proportionality problem of scintillators. In this work, we study direct and phonon-assisted Auger recombination in NaI using first-principles calculations. Our results show that phonon-assisted Auger recombination, mediated primarily by short-range phonon scattering, dominates at room temperature. We discuss our findings in light of the much larger values obtained by numerical fits to z-scan experiments.

  15. SNO+ Scintillator Purification and Assay

    SciTech Connect

    Ford, R.; Vazquez-Jauregui, E.; Chen, M.; Chkvorets, O.; Hallman, D.

    2011-04-27

    We describe the R and D on the scintillator purification and assay methods and technology for the SNO+ neutrino and double-beta decay experiment. The SNO+ experiment is a replacement of the SNO heavy water with liquid scintillator comprised of 2 g/L PPO in linear alkylbenzene (LAB). During filling the LAB will be transported underground by rail car and purified by multi-stage distillation and steam stripping at a flow rate of 19 LPM. While the detector is operational the scintillator can be recirculated at 150 LPM (full detector volume in 4 days) to provide repurification as necessary by either water extraction (for Ra, K, Bi) or by functional metal scavenger columns (for Pb, Ra, Bi, Ac, Th) followed by steam stripping to remove noble gases and oxygen (Rn, O{sub 2}, Kr, Ar). The metal scavenger columns also provide a method for scintillator assay for ex-situ measurement of the U and Th chain radioactivity. We have developed ''natural'' radioactive spikes of Pb and Ra in LAB and use these for purification testing. Lastly, we present the planned operating modes and purification strategies and the plant specifications and design.

  16. SNO+ Scintillator Purification and Assay

    NASA Astrophysics Data System (ADS)

    Ford, R.; Chen, M.; Chkvorets, O.; Hallman, D.; Vázquez-Jáuregui, E.

    2011-04-01

    We describe the R&D on the scintillator purification and assay methods and technology for the SNO+ neutrino and double-beta decay experiment. The SNO+ experiment is a replacement of the SNO heavy water with liquid scintillator comprised of 2 g/L PPO in linear alkylbenzene (LAB). During filling the LAB will be transported underground by rail car and purified by multi-stage distillation and steam stripping at a flow rate of 19 LPM. While the detector is operational the scintillator can be recirculated at 150 LPM (full detector volume in 4 days) to provide repurification as necessary by either water extraction (for Ra, K, Bi) or by functional metal scavenger columns (for Pb, Ra, Bi, Ac, Th) followed by steam stripping to remove noble gases and oxygen (Rn, O2, Kr, Ar). The metal scavenger columns also provide a method for scintillator assay for ex-situ measurement of the U and Th chain radioactivity. We have developed "natural" radioactive spikes of Pb and Ra in LAB and use these for purification testing. Lastly, we present the planned operating modes and purification strategies and the plant specifications and design.

  17. Multiple Ways to Solve Proportions

    ERIC Educational Resources Information Center

    Ercole, Leslie K.; Frantz, Marny; Ashline, George

    2011-01-01

    When solving problems involving proportions, students may intuitively draw on strategies that connect to their understanding of fractions, decimals, and percents. These two statements--"Instruction in solving proportions should include methods that have a strong intuitive basis" and "Teachers should begin instruction with more intuitive…

  18. Proportional Reasoning as Essential Numeracy

    ERIC Educational Resources Information Center

    Dole, Shelley; Hilton, Annette; Hilton, Geoff

    2015-01-01

    This paper reports an aspect of a large research and development project that aimed to promote middle years school teachers' understanding and awareness of the pervasiveness of proportional reasoning as integral to numeracy. Teacher survey data of proportional reasoning across the curriculum were mapped on to a rich model of numeracy. Results…

  19. Characterization of the scintillation anisotropy in crystalline stilbene scintillator detectors

    SciTech Connect

    Schuster, P.; Brubaker, E.

    2016-11-23

    This study reports a series of measurements that characterize the directional dependence of the scintillation response of crystalline melt-grown and solution-grown trans-stilbene to incident DT and DD neutrons. These measurements give the amplitude and pulse shape dependence on the proton recoil direction over one hemisphere of the crystal, confirming and extending previous results in the literature for melt-grown stilbene and providing the first measurements for solution-grown stilbene. In similar measurements of liquid and plastic detectors, no directional dependence was observed, confirming the hypothesis that the anisotropy in stilbene and other organic crystal scintillators is a result of internal effects due to the molecular or crystal structure and not an external effect on the measurement system.

  20. Characterization of the scintillation anisotropy in crystalline stilbene scintillator detectors

    DOE PAGES

    Schuster, P.; Brubaker, E.

    2016-11-23

    This study reports a series of measurements that characterize the directional dependence of the scintillation response of crystalline melt-grown and solution-grown trans-stilbene to incident DT and DD neutrons. These measurements give the amplitude and pulse shape dependence on the proton recoil direction over one hemisphere of the crystal, confirming and extending previous results in the literature for melt-grown stilbene and providing the first measurements for solution-grown stilbene. In similar measurements of liquid and plastic detectors, no directional dependence was observed, confirming the hypothesis that the anisotropy in stilbene and other organic crystal scintillators is a result of internal effects duemore » to the molecular or crystal structure and not an external effect on the measurement system.« less

  1. Test and characterisation of SiPMs for the MEGII high resolution Timing Counter

    NASA Astrophysics Data System (ADS)

    Simonetta, M.; Biasotti, M.; Boca, G.; Cattaneo, P. W.; De Gerone, M.; Gatti, F.; Nardò, R.; Nishimura, M.; Ootani, W.; Pizzigoni, G.; Prata, M. C.; Rossella, M.; Shibata, N.; Uchiyama, Y.; Yoshida, K.

    2016-07-01

    The MEGII Timing Counter will measure the positron time of arrival with a resolution of ~ 30 ps relying on two arrays of scintillator pixels read out by 6144 Silicon Photomultipliers (SiPMs) from AdvanSiD. They are characterised, measuring their breakdown voltage, to assure that the gains of the SiPMs of each pixel are as uniform as possible, to maximise the pixel resolution. Gain measurements have also been performed.

  2. Characterization of GNSS amplitude scintillations over Addis Ababa during 2009-2013

    NASA Astrophysics Data System (ADS)

    Akala, A. O.; Ejalonibu, A. H.; Doherty, P. H.; Radicella, S. M.; Groves, K. M.; Carrano, C. S.; Bridgwood, C. T.; Stoneback, R. A.

    2017-04-01

    This study characterizes GNSS amplitude scintillations over an African equatorial station: Addis Ababa (Lat 9.03°N, Lon 38.77°E, Mag. lat 0.18°N), Ethiopia during a five-year period (2009-2013). Scintillations were majorly localized within the hours of 2200-2400 LT. On a monthly basis, the highest occurrences of scintillation at Addis Ababa were recorded in April, and the lowest in June. Seasonally, the highest occurrences were recorded in equinoxes, and the lowest in June solstices. On a yearly scale, scintillations recorded the highest occurrences in 2012 and the lowest in 2009. Large proportions of the scintillations were localized within the northern sky of Addis Ababa. Supporting the characterization of the GNSS data with C/NOFS data, we noted that small-spatial scale density depletions are more detrimental to GNSS signals than their large-scale counterparts. Finally, EGNOS geostationary satellites' signals also scintillated steadily at Addis Ababa, with noticeable occurrences on the low elevation EGNOS satellite's (PRN 120) data. These events commenced around local sunset terminator, forming plateaus that vanished around local midnight.

  3. LHCb Upgrade: Scintillating Fibre Tracker

    NASA Astrophysics Data System (ADS)

    Tobin, Mark

    2016-07-01

    The LHCb detector will be upgraded during the Long Shutdown 2 (LS2) of the LHC in order to cope with higher instantaneous luminosities and to read out the data at 40 MHz using a trigger-less read-out system. All front-end electronics will be replaced and several sub-detectors must be redesigned to cope with higher occupancy. The current tracking detectors downstream of the LHCb dipole magnet will be replaced by the Scintillating Fibre (SciFi) Tracker. The SciFi Tracker will use scintillating fibres read out by Silicon Photomultipliers (SiPMs). State-of-the-art multi-channel SiPM arrays are being developed to read out the fibres and a custom ASIC will be used to digitise the signals from the SiPMs. The evolution of the design since the Technical Design Report in 2014 and the latest R & D results are presented.

  4. Scintillation Monitoring Using Asymmetry Index

    NASA Astrophysics Data System (ADS)

    Shaikh, Muhammad Mubasshir; Mahrous, Ayman; Abdallah, Amr; Notarpietro, Riccardo

    Variation in electron density can have significant effect on GNSS signals in terms of propagation delay. Ionospheric scintillation can be caused by rapid change of such delay, specifically, when they last for a longer period of time. Ionospheric irregularities that account for scintillation may vary significantly in spatial range and drift with the background plasma at speeds of 45 to 130 m/sec. These patchy irregularities may occur several times during night, e.g. in equatorial region, with the patches move through the ray paths of the GNSS satellite signals. These irregularities are often characterized as either ‘large scale’ (which can be as large as several hundred km in East-West direction and many times that in the North-South direction) or ‘small scale’ (which can be as small as 1m). These small scale irregularities are regarded as the main cause of scintillation [1,2]. In normal solar activity conditions, the mid-latitude ionosphere is not much disturbed. However, during severe magnetic storms, the aurora oval extends towards the equator and the equator anomaly region may stretched towards poles extending the scintillation phenomena more typically associated with those regions into mid-latitudes. In such stormy conditions, the predicted TEC may deviate largely from the true value of the TEC both at low and mid-latitudes due to which GNSS applications may be strongly degraded. This work is an attempt to analyze ionospheric scintillation (S4 index) using ionospheric asymmetry index [3]. The asymmetry index is based on trans-ionospheric propagation between GPS and LEO satellites in a radio occultation (RO) scenario, using background ionospheric data provided by MIDAS [4]. We attempted to simulate one of the recent geomagnetic storms (NOAA scale G4) occurred over low/mid-latitudes. The storm started on 26 September 2011 at UT 18:00 and lasted until early hours of 27 September 2011. The scintillation data for the storm was taken from an ionospheric

  5. Countering antivaccination attitudes

    PubMed Central

    Horne, Zachary; Powell, Derek; Hummel, John E.; Holyoak, Keith J.

    2015-01-01

    Three times as many cases of measles were reported in the United States in 2014 as in 2013. The reemergence of measles has been linked to a dangerous trend: parents refusing vaccinations for their children. Efforts have been made to counter people’s antivaccination attitudes by providing scientific evidence refuting vaccination myths, but these interventions have proven ineffective. This study shows that highlighting factual information about the dangers of communicable diseases can positively impact people’s attitudes to vaccination. This method outperformed alternative interventions aimed at undercutting vaccination myths. PMID:26240325

  6. The homestake surface-underground scintillators: Initial results

    NASA Technical Reports Server (NTRS)

    Cherry, M. L.; Corbato, S.; Daily, T.; Fenyves, E. J.; Kieda, D.; Lande, K.; Lee, C. K.

    1986-01-01

    The first 70 tons of the 140-ton Large Area Scintillation Detector (LASD) have been operating since Jan. 1985 at a depth of 4850 ft. (4200 m.w.e.) in the Homestake Gold Mine, Lead, S.D. A total of 4 x 10(4) high-energy muons (E sub mu is approx. 2.7 TeV at the surface) have been detected. The remainder of the detector is scheduled to be in operation by the Fall of 1985. In addition, a surface air shower array is under construction. The first 27 surface counters, spaced out over an area of 270' x 500', began running in June, 1985. The LASD performance, the potential of the combined shower array and underground muon experiment for detecting point sources, and the initial results of a search for periodic emission from Cygnus X-3 are discussed.

  7. Detecting scintillations in liquid helium

    NASA Astrophysics Data System (ADS)

    Huffman, P. R.; McKinsey, D. N.

    2013-09-01

    We review our work in developing a tetraphenyl butadiene (TPB)-based detection system for a measurement of the neutron lifetime using magnetically confined ultracold neutrons (UCN). As part of the development of the detection system for this experiment, we studied the scintillation properties of liquid helium itself, characterized the fluorescent efficiencies of different fluors, and built and tested three detector geometries. We provide an overview of the results from these studies as well as references for additional information.

  8. Study of a detector system for high-energy astrophysical objects using a combination of plastic scintillator and MPPC

    NASA Astrophysics Data System (ADS)

    Nakaoka, Tatsuya; Mizuno, Tsunefumi; Takahashi, Hiromitsu; Fukazawa, Yasushi

    2016-09-01

    We have investigated a hard X-ray detector system using a combination of a plastic scintillator and multi-pixel photon counters (MPPC). Photomultiplier tubes (PMTs) have typically been adopted to read scintillators because of their high gain and large photoelectric surface, and studies on PMT and scintillator systems are well advanced. However, PMTs have limitations; for example, they are relatively large in size, require high voltage to operate, and cannot be used in strong magnetic fields. On the other hand, MPPCs do not have such limitations and instead possess high quantum efficiency and a large compact size. Therefore, we have studied a detector system that combines an MPPC with a plastic scintillator. The system is primarily intended to be used for polarization measurements of high-energy astrophysical objects. We achieved an energy threshold of as low as ~5 keV while operating the detector at low temperature (-10 °C), reading the signal with short integration time (50 ns), and using a low-noise MPPC. We also confirmed that the light yield of our MPPC+plastic scintillator system is comparable to that obtained using a conventional PMT to read the scintillator signal. Herein, we report test results and future prospects.

  9. Scintillation Forecasting Using NPOESS Data

    NASA Astrophysics Data System (ADS)

    Basu, B.; Retterer, J.; Demajistre, R.; de La Beaujardiere, O.; Scro, K.

    2005-12-01

    We have conducted a theoretical study of the use of NPOESS data for the forecasting of equatorial radio scintillation using knowledge of the equatorial Appleton anomaly, e.g., the peak-to-valley ratio of TEC (Total Electron Content) between the anomaly crests and the magnetic equator. The peak-to-valley ratio can be obtained from the UV (ultraviolet) imagery of the anomaly region that will be provided by the NPOESS sensors. The post-sunset enhancement of the upward drift velocity of the equatorial plasma has been shown, both theoretically and observationally, to be an important determinant of both the onset of scintillation and the strength of the anomaly. The technical approach is to run PBMOD, the AFRL low-latitude ionosphere model, with a range of post-sunset vertical drift velocities to determine the quantitative relationship between the peak-to-valley ratio and the maximum value of the pot-sunset upward drift velocity of equatorial plasma. Once the relationship is validated, it will be used to estimate the maximum value of the drift velocity from the peak-to-valley ratio, which is derived from the UV imagery data provided by NPOESS-like sensor, such as GUVI on TIMED satellite. The drift velocity will then be used in PBMOD to simulate the formation and evolution of equatorial plasma `bubbles' and calculate the distribution of the amplitude scintillation index S4. Results of the study will be discussed.

  10. Seeing the invisible: Direct visualization of therapeutic radiation beams using air scintillation

    SciTech Connect

    Fahimian, Benjamin; Türkcan, Silvan; Kapp, Daniel S.; Pratx, Guillem; Ceballos, Andrew

    2014-01-15

    Purpose: To assess whether air scintillation produced during standard radiation treatments can be visualized and used to monitor a beam in a nonperturbing manner. Methods: Air scintillation is caused by the excitation of nitrogen gas by ionizing radiation. This weak emission occurs predominantly in the 300–430 nm range. An electron-multiplication charge-coupled device camera, outfitted with an f/0.95 lens, was used to capture air scintillation produced by kilovoltage photon beams and megavoltage electron beams used in radiation therapy. The treatment rooms were prepared to block background light and a short-pass filter was utilized to block light above 440 nm. Results: Air scintillation from an orthovoltage unit (50 kVp, 30 mA) was visualized with a relatively short exposure time (10 s) and showed an inverse falloff (r{sup 2} = 0.89). Electron beams were also imaged. For a fixed exposure time (100 s), air scintillation was proportional to dose rate (r{sup 2} = 0.9998). As energy increased, the divergence of the electron beam decreased and the penumbra improved. By irradiating a transparent phantom, the authors also showed that Cherenkov luminescence did not interfere with the detection of air scintillation. In a final illustration of the capabilities of this new technique, the authors visualized air scintillation produced during a total skin irradiation treatment. Conclusions: Air scintillation can be measured to monitor a radiation beam in an inexpensive and nonperturbing manner. This physical phenomenon could be useful for dosimetry of therapeutic radiation beams or for online detection of gross errors during fractionated treatments.

  11. A Review of Ionospheric Scintillation Models.

    PubMed

    Priyadarshi, S

    This is a general review of the existing climatological models of ionospheric radio scintillation for high and equatorial latitudes. Trans-ionospheric communication of radio waves from transmitter to user is affected by the ionosphere which is highly variable and dynamic in both time and space. Scintillation is the term given to irregular amplitude and phase fluctuations of the received signals and related to the electron density irregularities in the ionosphere. Key sources of ionospheric irregularities are plasma instabilities; every irregularities model is based on the theory of radio wave propagation in random media. It is important to understand scintillation phenomena and the approach of different theories. Therefore, we have briefly discussed the theories that are used to interpret ionospheric scintillation data. The global morphology of ionospheric scintillation is also discussed briefly. The most important (in our opinion) analytical and physical models of scintillation are reviewed here.

  12. Study of nonproportionality in the light yield of inorganic scintillators

    SciTech Connect

    Singh, Jai

    2011-07-15

    Using a phenomenological approach, the light yield is derived for inorganic scintillators as a function of the rates of linear, bimolecular, and Auger processes occurring in the electron track initiated by an x ray or a {gamma}-ray photon. A relation between the track length and incident energy is also derived. It is found that the nonproportionality in the light yield can be eliminated if either nonlinear processes of interaction among the excited electrons, holes, and excitons can be eliminated from occurring or the high density situation can be relieved by diffusion of carriers from the track at a faster rate than the rate of activation of nonlinear processes. The influence of the track length and radius on the yield nonproportionality is discussed in view of the known experimental results. Inventing new inorganic scintillating materials with high carrier mobility can lead to a class of proportional inorganic scintillators. Results agree qualitatively with experimental results for the dependence of light yield on the incident energy.

  13. Recording of relativistic particles in thin scintillators

    SciTech Connect

    Tolstukhin, I A.; Somov, Alexander S.; Somov, S. V.; Bolozdynya, A. I.

    2014-11-01

    Results of investigating an assembly of thin scintillators and silicon photomultipliers for registering relativistic particles with the minimum ionization are presented. A high efficiency of registering relativistic particles using an Ej-212 plastic scintillator, BSF-91A wavelength-shifting fiber (Saint-Gobain), and a silicon photomultiplier (Hamamtsu) is shown. The measurement results are used for creating a scintillation hodoscope of the magnetic spectrometer for registering γ quanta in the GlueX experiment.

  14. Scintillator tiles read out with silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Pooth, O.; Radermacher, T.; Weingarten, S.; Weinstock, L.

    2015-10-01

    A detector prototype based on a fast plastic scintillator read out with silicon photomultipliers is presented. All studies have been done with cosmic muons and focus on parameter optimization such as coupling the SiPM to the scintillator or wrapping the scintillator with reflective material. The prototype shows excellent results regarding the light-yield and offers a detection efficiency of 99.5% with a signal purity of 99.9% for cosmic muons.

  15. Spacecraft Radio Scintillation and Solar System Exploration

    NASA Technical Reports Server (NTRS)

    Woo, Richard

    1993-01-01

    When a wave propagates through a turbulent medium, scattering by the random refractive index inhomogeneities can lead to a wide variety of phenomena that have been the subject of extensive study. The observed scattering effects include amplitude or intensity scintillation, phase scintillation, angular broadening, and spectral broadening, among others. In this paper, I will refer to these scattering effects collectively as scintillation. Although the most familiar example is probably the twinkling of stars (light wave intensity scintillation by turbulence in the Earth's atmosphere), scintillation has been encountered and investigated in such diverse fields as ionospheric physics, oceanography, radio astronomy, and radio and optical communications. Ever since planetary spacecraft began exploring the solar system, scintillation has appeared during the propagation of spacecraft radio signals through planetary atmospheres, planetary ionospheres, and the solar wind. Early studies of these phenomena were motivated by the potential adverse effects on communications and navigation, and on experiments that use the radio link to conduct scientific investigations. Examples of the latter are radio occultation measurements (described below) of planetary atmospheres to deduce temperature profiles, and the search for gravitational waves. However,these concerns soon gave way to the emergence of spacecraft radio scintillation as a new scientific tool for exploring small-scale dynamics in planetary atmospheres and structure in the solar wind, complementing in situ and other remote sensing spacecraft measurements, as well as scintillation measurements using natural (celestial) radio sources. The purpose of this paper is to briefly describe and review the solar system spacecraft radio scintillation observations, to summarize the salient features of wave propagation analyses employed in interpreting them, to underscore the unique remote sensing capabilities and scientific relevance of

  16. Low latency counter event indication

    DOEpatents

    Gara, Alan G.; Salapura, Valentina

    2010-08-24

    A hybrid counter array device for counting events with interrupt indication includes a first counter portion comprising N counter devices, each for counting signals representing event occurrences and providing a first count value representing lower order bits. An overflow bit device associated with each respective counter device is additionally set in response to an overflow condition. The hybrid counter array includes a second counter portion comprising a memory array device having N addressable memory locations in correspondence with the N counter devices, each addressable memory location for storing a second count value representing higher order bits. An operatively coupled control device monitors each associated overflow bit device and initiates incrementing a second count value stored at a corresponding memory location in response to a respective overflow bit being set. The incremented second count value is compared to an interrupt threshold value stored in a threshold register, and, when the second counter value is equal to the interrupt threshold value, a corresponding "interrupt arm" bit is set to enable a fast interrupt indication. On a subsequent roll-over of the lower bits of that counter, the interrupt will be fired.

  17. Low latency counter event indication

    DOEpatents

    Gara, Alan G.; Salapura, Valentina

    2008-09-16

    A hybrid counter array device for counting events with interrupt indication includes a first counter portion comprising N counter devices, each for counting signals representing event occurrences and providing a first count value representing lower order bits. An overflow bit device associated with each respective counter device is additionally set in response to an overflow condition. The hybrid counter array includes a second counter portion comprising a memory array device having N addressable memory locations in correspondence with the N counter devices, each addressable memory location for storing a second count value representing higher order bits. An operatively coupled control device monitors each associated overflow bit device and initiates incrementing a second count value stored at a corresponding memory location in response to a respective overflow bit being set. The incremented second count value is compared to an interrupt threshold value stored in a threshold register, and, when the second counter value is equal to the interrupt threshold value, a corresponding "interrupt arm" bit is set to enable a fast interrupt indication. On a subsequent roll-over of the lower bits of that counter, the interrupt will be fired.

  18. New Scintillators for Photosensitive Gaseous Detectors

    NASA Astrophysics Data System (ADS)

    Charpak, G.; Peskov, V.; Scigocki, D.; Valbis, J.

    A new family of scintillators are presented. Their properties are similar to those of barium fluoride, and the spectrum of the scintillation emission is between 140 and 300 nm. Our latest efficiency measurements of ethyl ferrocene and triethylamine liquid or caesium iodide solid photocathodes, in parallel-plate avalanche chambers (PPACs) at high electric field, are also presented. We discuss the revolutionary consequences of the combination of the new scintillators with PPACs with semitransparent photocathodes deposited on the crystals, such as high speed, high resistance to radiation damage, compacity, high gamma efficiency, and applications to tracking devices with scintillation optical fibres.

  19. Divalent fluoride doped cerium fluoride scintillator

    DOEpatents

    Anderson, David F.; Sparrow, Robert W.

    1991-01-01

    The use of divalent fluoride dopants in scintillator materials comprising cerium fluoride is disclosed. The preferred divalent fluoride dopants are calcium fluoride, strontium fluoride, and barium fluoride. The preferred amount of divalent fluoride dopant is less than about two percent by weight of the total scintillator. Cerium fluoride scintillator crystals grown with the addition of a divalent fluoride have exhibited better transmissions and higher light outputs than crystals grown without the addition of such dopants. These scintillators are useful in radiation detection and monitoring applications, and are particularly well suited for high-rate applications such as positron emission tomography (PET).

  20. Waveshifters and Scintillators for Ionizing Radiation Detection

    SciTech Connect

    B.Baumgaugh; J.Bishop; D.Karmgard; J.Marchant; M.McKenna; R.Ruchti; M.Vigneault; L.Hernandez; C.Hurlbut

    2007-12-11

    Scintillation and waveshifter materials have been developed for the detection of ionizing radiation in an STTR program between Ludlum Measurements, Inc. and the University of Notre Dame. Several new waveshifter materials have been developed which are comparable in efficiency and faster in fluorescence decay than the standard material Y11 (K27) used in particle physics for several decades. Additionally, new scintillation materials useful for fiber tracking have been developed which have been compared to 3HF. Lastly, work was done on developing liquid scintillators and paint-on scintillators and waveshifters for high radiation environments.

  1. Radio wave scintillations at equatorial regions

    NASA Technical Reports Server (NTRS)

    Poularikas, A. D.

    1972-01-01

    Radio waves, passing through the atmosphere, experience amplitude and phase fluctuations know as scintillations. A characterization of equatorial scintillation, which has resulted from studies of data recorded primarily in South America and equatorial Africa, is presented. Equatorial scintillation phenomena are complex because they appear to vary with time of day (pre-and postmidnight), season (equinoxes), and magnetic activity. A wider and more systematic geographical coverage is needed for both scientific and engineering purposes; therefore, it is recommended that more observations should be made at earth stations (at low-geomagnetic latitudes) to record equatorial scintillation phenomena.

  2. Space and power efficient hybrid counters array

    DOEpatents

    Gara, Alan G.; Salapura, Valentina

    2010-03-30

    A hybrid counter array device for counting events. The hybrid counter array includes a first counter portion comprising N counter devices, each counter device for receiving signals representing occurrences of events from an event source and providing a first count value corresponding to a lower order bits of the hybrid counter array. The hybrid counter array includes a second counter portion comprising a memory array device having N addressable memory locations in correspondence with the N counter devices, each addressable memory location for storing a second count value representing higher order bits of the hybrid counter array. A control device monitors each of the N counter devices of the first counter portion and initiates updating a value of a corresponding second count value stored at the corresponding addressable memory location in the second counter portion. Thus, a combination of the first and second count values provide an instantaneous measure of number of events received.

  3. Space and power efficient hybrid counters array

    DOEpatents

    Gara, Alan G.; Salapura, Valentina

    2009-05-12

    A hybrid counter array device for counting events. The hybrid counter array includes a first counter portion comprising N counter devices, each counter device for receiving signals representing occurrences of events from an event source and providing a first count value corresponding to a lower order bits of the hybrid counter array. The hybrid counter array includes a second counter portion comprising a memory array device having N addressable memory locations in correspondence with the N counter devices, each addressable memory location for storing a second count value representing higher order bits of the hybrid counter array. A control device monitors each of the N counter devices of the first counter portion and initiates updating a value of a corresponding second count value stored at the corresponding addressable memory location in the second counter portion. Thus, a combination of the first and second count values provide an instantaneous measure of number of events received.

  4. Bayesian Inference on Proportional Elections

    PubMed Central

    Brunello, Gabriel Hideki Vatanabe; Nakano, Eduardo Yoshio

    2015-01-01

    Polls for majoritarian voting systems usually show estimates of the percentage of votes for each candidate. However, proportional vote systems do not necessarily guarantee the candidate with the most percentage of votes will be elected. Thus, traditional methods used in majoritarian elections cannot be applied on proportional elections. In this context, the purpose of this paper was to perform a Bayesian inference on proportional elections considering the Brazilian system of seats distribution. More specifically, a methodology to answer the probability that a given party will have representation on the chamber of deputies was developed. Inferences were made on a Bayesian scenario using the Monte Carlo simulation technique, and the developed methodology was applied on data from the Brazilian elections for Members of the Legislative Assembly and Federal Chamber of Deputies in 2010. A performance rate was also presented to evaluate the efficiency of the methodology. Calculations and simulations were carried out using the free R statistical software. PMID:25786259

  5. Simultaneous measurement of tritium and radiocarbon by ultra-low-background proportional counting

    DOE PAGES

    Mace, Emily; Aalseth, Craig; Alexander, Tom; ...

    2016-12-21

    Use of ultra-low-background capabilities at Pacific Northwest National Laboratory provide enhanced sensitivity for measurement of low-activity sources of tritium and radiocarbon using proportional counters. Tritium levels are nearly back to pre-nuclear test backgrounds (~2-8 TU in rainwater), which can complicate their dual measurement with radiocarbon due to overlap in the beta decay spectra. In this paper, we present results of single-isotope proportional counter measurements used to analyze a dual-isotope methane sample synthesized from ~120 mg of H2O and present sensitivity results.

  6. Simultaneous measurement of tritium and radiocarbon by ultra-low-background proportional counting

    SciTech Connect

    Mace, Emily; Aalseth, Craig; Alexander, Tom; Back, Henning; Day, Anthony; Hoppe, Eric; Keillor, Martin; Moran, Jim; Overman, Cory; Panisko, Mark; Seifert, Allen

    2016-12-21

    Use of ultra-low-background capabilities at Pacific Northwest National Laboratory provide enhanced sensitivity for measurement of low-activity sources of tritium and radiocarbon using proportional counters. Tritium levels are nearly back to pre-nuclear test backgrounds (~2-8 TU in rainwater), which can complicate their dual measurement with radiocarbon due to overlap in the beta decay spectra. In this paper, we present results of single-isotope proportional counter measurements used to analyze a dual-isotope methane sample synthesized from ~120 mg of H2O and present sensitivity results.

  7. Over-the-Counter Medicines

    MedlinePlus

    Over-the-counter (OTC) medicines are drugs you can buy without a prescription. Some OTC medicines relieve aches, pains and itches. Some prevent or cure ... the Food and Drug Administration decides whether a medicine is safe enough to sell over-the-counter. ...

  8. Counter-Learning under Oppression

    ERIC Educational Resources Information Center

    Kucukaydin, Ilhan

    2010-01-01

    This qualitative study utilized the method of narrative analysis to explore the counter-learning process of an oppressed Kurdish woman from Turkey. Critical constructivism was utilized to analyze counter-learning; Frankfurt School-based Marcusian critical theory was used to analyze the sociopolitical context and its impact on the oppressed. Key…

  9. Neutron flux measurement using activated radioactive isotopes at the Baksan underground scintillation telescope

    NASA Astrophysics Data System (ADS)

    Kochkarov, M. M.; Alikhanov, I. A.; Boliev, M. M.; Dzaparova, I. M.; Novoseltseva, R. V.; Novoseltsev, Yu. F.; Petkov, V. B.; Volchenko, V. I.; Volchenko, G. V.; Yanin, A. F.

    2016-11-01

    Preliminary results of a neutron background measurement at the Baksan underground scintillation telescope (BUST) are presented. The external planes of the BUST are fully covered with standard scintillation detectors shielding the internal planes and suppressing thus background events due to cosmogenic and local radioactivity. The shielded internal planes were used as target for the neutron flux registration. The experimental method is based on the delayed coincidences between signals from any of the BUST counters. It is assumed that the first signal is due to inelastic interaction of a neutron with the organic scintillator, while the second signal comes from the decay of an unstable radioactive isotope formed when the fast neutron interacts with the 12C nuclei. Using the Monte-Carlo method (GEANT4) we also simulated propagation of neutrons through a layer of scintillator. The experimentally found muon induced neutron flux is j =1.3 -0.3 +0.7 ×10-10cm-2s-1 for neutron energies E ≥ 22MeV, which is in a qualitative agreement with similar measurements of other underground laboratories as well as with predictions of the GEANT4.

  10. High luminosity operation of large solid angle scintillator arrays in Jefferson Lab Hall A

    SciTech Connect

    Shneor, Ran

    2003-12-01

    This thesis describes selected aspects of high luminosity operation of large solid angle scintillator arrays in Hall A of the CEBAF (Central Electron Beam Accelerator Facility) at TJNAF (Thomas Jefferson National Accelerator Facility ). CEBAF is a high current, high duty factor electron accelerator with a maximum beam energy of about 6 GeV and a maximum current of 200 μA. Operating large solid angle scintillator arrays in high luminosity environment presents several problems such as high singles rates, low signal to noise ratios and shielding requirements. To demonstrate the need for large solid angle and momentum acceptance detectors as a third arm in Hall A, we will give a brief overview of the physics motivating five approved experiments, which utilize scintillator arrays. We will then focus on the design and assembly of these scintillator arrays, with special focus on the two new detector packages built for the Short Range Correlation experiment E01-015. This thesis also contains the description and results of different tests and calibrations which where conducted for these arrays. We also present the description of a number of tests which were done in order to estimate the singles rates, data reconstruction, filtering techniques and shielding required for these counters.

  11. Compensated gadolinium-loaded plastic scintillators for thermal neutron detection (and counting)

    SciTech Connect

    Dumazert, Jonathan; Coulon, Romain; Bertrand, Guillaume H. V.; Hamel, Matthieu; Sguerra, Fabien; Dehe-Pittance, Chrystele; Normand, Stephane; Mechin, Laurence

    2015-07-01

    Plastic scintillator loading with gadolinium-rich organometallic complexes shows a high potential for the deployment of efficient and cost-effective neutron detectors. Due to the low-energy photon and electron signature of thermal neutron capture by gadolinium-155 and gadolinium-157, alternative treatment to Pulse Shape Discrimination has to be proposed in order to display a trustable count rate. This paper discloses the principle of a compensation method applied to a two-scintillator system: a detection scintillator interacts with photon radiation and is loaded with gadolinium organometallic compound to become a thermal neutron absorber, while a non-gadolinium loaded compensation scintillator solely interacts with the photon part of the incident radiation. Posterior to the nonlinear smoothing of the counting signals, a hypothesis test determines whether the resulting count rate after photon response compensation falls into statistical fluctuations or provides a robust image of a neutron activity. A laboratory prototype is tested under both photon and neutron irradiations, allowing us to investigate the performance of the overall compensation system in terms of neutron detection, especially with regards to a commercial helium-3 counter. The study reveals satisfactory results in terms of sensitivity and orientates future investigation toward promising axes. (authors)

  12. Proportional Hazards Models of Graduation

    ERIC Educational Resources Information Center

    Chimka, Justin R.; Reed-Rhoads, Teri; Barker, Kash

    2008-01-01

    Survival analysis is a statistical tool used to describe the duration between events. Many processes in medical research, engineering, and economics can be described using survival analysis techniques. This research involves studying engineering college student graduation using Cox proportional hazards models. Among male students with American…

  13. Saving Money Using Proportional Reasoning

    ERIC Educational Resources Information Center

    de la Cruz, Jessica A.; Garney, Sandra

    2016-01-01

    It is beneficial for students to discover intuitive strategies, as opposed to the teacher presenting strategies to them. Certain proportional reasoning tasks are more likely to elicit intuitive strategies than other tasks. The strategies that students are apt to use when approaching a task, as well as the likelihood of a student's success or…

  14. Social Justice and Proportional Reasoning

    ERIC Educational Resources Information Center

    Simic-Muller, Ksenija

    2015-01-01

    Ratio and proportional reasoning tasks abound that have connections to real-world situations. Examples in this article demonstrate how textbook tasks can easily be transformed into authentic real-world problems that shed light on issues of equity and fairness, such as population growth and crime rates. A few ideas are presented on how teachers can…

  15. Understanding Proportional Reasoning for Teaching

    ERIC Educational Resources Information Center

    Kastberg, Signe E.; D'Ambrosio, Beatriz; Lynch-Davis, Kathleen

    2012-01-01

    Proportional reasoning is an important cornerstone in children's mathematical development. This sort of reasoning has been shown to develop across the early years of schooling (ages 8 to 10) through the middle years (ages 11-14). In the early years, children tend to use additive reasoning to generate solutions to problems, while later comparisons…

  16. Proportional Reasoning with a Pyramid

    ERIC Educational Resources Information Center

    Mamolo, Ami; Sinclair, Margaret; Whiteley, Walter J.

    2011-01-01

    Proportional reasoning pops up in math class in a variety of places, such as while making scaled drawings; finding equivalent fractions; converting units of measurement; comparing speeds, prices, and rates; and comparing lengths, areas, and volume. Students need to be exposed to a variety of representations to develop a sound understanding of this…

  17. Accelerated discovery of elpasolite scintillators

    SciTech Connect

    Doty, F. Patrick; Yang, Pin; Zhou, Xiaowang

    2014-12-01

    Elpasolite scintillators are a large family of halides which includes compounds reported to meet the NA22 program goals of <3% energy resolution at 662 keV1. This work investigated the potential to produce quality elpasolite compounds and alloys of useful sizes at reasonable cost, through systematic experimental and computational investigation of crystal structure and properties across the composition space. Discovery was accelerated by computational methods and models developed previously to efficiently identify cubic members of the elpasolite halides, and to evaluate stability of anion and cation exchange alloys.

  18. Improving γ-ray energy resolution, non-proportionality, and decay time of NaI:Tl+ with Sr2+ and Ca2+ co-doping

    NASA Astrophysics Data System (ADS)

    Yang, K.; Menge, P. R.

    2015-12-01

    Commercially available thallium activated sodium iodide scintillators are typically characterized by a γ-ray energy resolution of 6.5% at 662 keV and a scintillation decay time constant of 230 ns. Energy resolution, non-proportionality, and scintillation decay time are improved when the crystal is co-doped with alkaline earth metals (Sr2+ and Ca2+). The energy resolution of NaI:Tl+ is improved to 5.3%, and the decay time is simultaneously reduced to 170 ns with Sr2+ and Ca2+ co-doping. The improvement in energy resolution, non-proportionality, and decay time are likely due to the suppression of the slow scintillation processes in NaI:Tl+.

  19. Transparent ceramic garnet scintillator optimization via composition and co-doping for high-energy resolution gamma spectrometers (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Cherepy, Nerine J.; Payne, Stephen A.; Seeley, Zachary M.; Beck, Patrick R.; Swanberg, Erik L.; Hunter, Steven L.

    2016-09-01

    Breakthrough energy resolution, R(662keV) <4%, has been achieved with an oxide scintillator, Cerium-doped Gadolinium Yttrium Gallium Aluminum Garnet, or GYGAG(Ce), by optimizing fabrication conditions. Here we describe the dependence of scintillation light yield and energy resolution on several variables: (1) Stoichiometry, in particular Gd/Y and Ga/Al ratios which modify the bandgap energy, (2) Processing methods, including vacuum vs. oxygen sintering, and (3) Trace co-dopants that influence the formation of Ce4+ and modify the intra-bandgap trap distribution. To learn about how chemical composition influences the scintillation properties of transparent ceramic garnet scintillators, we have measured: scintillation decay component amplitudes; intensity and duration of afterglow; thermoluminescence glow curve peak positions and amplitudes; integrated light yield; light yield non-proportionality, as measured in the Scintillator Light Yield Non-Proportionality Characterization Instrument (SLYNCI); and energy resolution for gamma spectroscopy. Optimized GYGAG(Ce) provides R(662 keV) =3.0%, for 0.05 cm3 size ceramics with Silicon photodiode readout, and R(662 keV) =4.6%, at 2 in3 size with PMT readout.

  20. Current status on plastic scintillators modifications

    SciTech Connect

    Hamel, Matthieu; Bertrand, Guillaume H.V.; Carrel, Frederick; Coulon, Romain; Dumazert, Jonathan; Montbarbon, Eva; Sguerra, Fabien

    2015-07-01

    Recent developments of plastic scintillators are reviewed, from 2000 to March 2015. All examples are distributed into the main purpose, i.e. the nature of the radionuclide provided with the scope of detection of various radiation particles. The main characteristics of these newly created scintillators and their detection properties are given. (authors)

  1. Binderless composite scintillator for neutron detection

    DOEpatents

    Hodges, Jason P [Knoxville, TN; Crow, Jr; Lowell, M [Oak Ridge, TN; Cooper, Ronald G [Oak Ridge, TN

    2009-03-10

    Composite scintillator material consisting of a binderless sintered mixture of a Lithium (Li) compound containing .sup.6Li as the neutron converter and Y.sub.2SiO.sub.5:Ce as the scintillation phosphor, and the use of this material as a method for neutron detection. Other embodiments of the invention include various other Li compounds.

  2. Epoxy resins produce improved plastic scintillators

    NASA Technical Reports Server (NTRS)

    Markley, F. W.

    1967-01-01

    Plastic scintillator produced by the substitution of epoxy resins for the commonly used polystyrene is easy to cast, stable at room temperature, and has the desirable properties of a thermoset or cross-linked system. Such scintillators can be immersed directly in strong solvents, an advantage in many chemical and biological experiments.

  3. Scintillator handbook with emphasis on cesium iodide

    NASA Technical Reports Server (NTRS)

    Tidd, J. L.; Dabbs, J. R.; Levine, N.

    1973-01-01

    This report provides a background of reasonable depth and reference material on scintillators in general. Particular attention is paid to the cesium iodide scintillators as used in the High Energy Astronomy Observatory (HEAO) experiments. It is intended especially for use by persons such as laboratory test personnel who need to obtain a working knowledge of these materials and their characteristics in a short time.

  4. SrI2 scintillator for gamma ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Cherepy, N. J.; Sturm, B. W.; Drury, O. B.; Hurst, T. A.; Sheets, S. A.; Ahle, L. E.; Saw, C. K.; Pearson, M. A.; Payne, S. A.; Burger, A.; Boatner, L. A.; Ramey, J. O.; van Loef, E. V.; Glodo, J.; Hawrami, R.; Higgins, W. M.; Shah, K. S.; Moses, W. W.

    2009-08-01

    We are working to perfect the growth of divalent Eu-doped strontium iodide single crystals and to optimize the design of SrI2(Eu)-based gamma ray spectrometers. SrI2(Eu) offers a light yield in excess of 100,000 photons/MeV and light yield proportionality surpassing that of Ce-doped lanthanum bromide. Thermal and x-ray diffraction analyses of SrI2 and EuI2 indicate an excellent match in melting and crystallographic parameters, and very modest thermal expansion anisotropy. We have demonstrated energy resolution with SrI2(4-6%Eu) of 2.6% at 662 keV and 7.6% at 60 keV with small crystals, while the resolution degrades somewhat for larger sizes. Our experiments suggest that digital techniques may be useful in improving the energy resolution in large crystals impaired by light-trapping, in which scintillation light is re-absorbed and re-emitted in large and/or highly Eu2+ -doped crystals. The light yield proportionality of SrI2(Eu) is found to be superior to that of other known scintillator materials, such as LaBr3(Ce) and NaI(Tl).

  5. Extruded scintillator for the calorimetry applications

    SciTech Connect

    Dyshkant, A.; Rykalin, V.; Pla-Dalmau, A.; Beznosko, D.; /SUNY, Stony Brook

    2006-08-01

    An extrusion line has been installed and successfully operated at FNAL (Fermi National Accelerator Laboratory) in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new Facility will serve to further develop and improve extruded plastic scintillator. Recently progress has been made in producing co-extruded plastic scintillator, thus increasing the potential HEP applications of this Facility. The current R&D work with extruded and co-extruded plastic scintillator for a potential ALICE upgrade, the ILC calorimetry program and the MINERvA experiment show the attractiveness of the chosen strategy for future experiments and calorimetry. We extensively discuss extruded and co-extruded plastic scintillator in calorimetry in synergy with new Solid State Photomultipliers. The characteristics of extruded and co-extruded plastic scintillator will be presented here as well as results with non-traditional photo read-out.

  6. Extruded scintillator for the Calorimetry applications

    NASA Astrophysics Data System (ADS)

    Dyshkant, A.; Rykalin, V.; Pla-Dalmau, A.; Beznosko, D.

    2006-10-01

    An extrusion line has been installed and successfully operated at FNAL (Fermi National Accelerator Laboratory) in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new Facility will serve to further develop and improve extruded plastic scintillator. Recently progress has been made in producing co-extruded plastic scintillator, thus increasing the potential HEP applications of this Facility. The current R&D work with extruded and co-extruded plastic scintillator for a potential ALICE upgrade, the ILC calorimetry program and the MINERvA experiment show the attractiveness of the chosen strategy for future experiments and calorimetry. We extensively discuss extruded and co-extruded plastic scintillator in calorimetry in synergy with new Solid State Photomultipliers. The characteristics of extruded and co-extruded plastic scintillator will be presented here as well as results with non-traditional photo read-out.

  7. Scintillation Effects on Space Shuttle GPS Data

    NASA Technical Reports Server (NTRS)

    Goodman, John L.; Kramer, Leonard

    2001-01-01

    Irregularities in ionospheric electron density result in variation in amplitude and phase of Global Positioning System (GPS) signals, or scintillation. GPS receivers tracking scintillated signals may lose carrier phase or frequency lock in the case of phase sc intillation. Amplitude scintillation can cause "enhancement" or "fading" of GPS signals and result in loss of lock. Scintillation can occur over the equatorial and polar regions and is a function of location, time of day, season, and solar and geomagnetic activity. Mid latitude regions are affected only very rarely, resulting from highly disturbed auroral events. In the spring of 1998, due to increasing concern about scintillation of GPS signals during the upcoming solar maximum, the Space Shuttle Program began to assess the impact of scintillation on Collins Miniaturized Airborne GPS Receiver (MAGR) units that are to replace Tactical Air Control and Navigation (TACAN) units on the Space Shuttle orbiters. The Shuttle Program must determine if scintillation effects pose a threat to safety of flight and mission success or require procedural and flight rule changes. Flight controllers in Mission Control must understand scintillation effects on GPS to properly diagnose "off nominal" GPS receiver performance. GPS data from recent Space Shuttle missions indicate that the signals tracked by the Shuttle MAGR manifest scintillation. Scintillation is observed as anomalous noise in velocity measurements lasting for up to 20 minutes on Shuttle orbit passes and are not accounted for in the error budget of the MAGR accuracy parameters. These events are typically coincident with latitude and local time occurrence of previously identified equatorial spread F within about 20 degrees of the magnetic equator. The geographic and seasonal history of these events from ground-based observations and a simple theoretical model, which have potential for predicting events for operational purposes, are reviewed.

  8. Simulation of optical interstellar scintillation

    NASA Astrophysics Data System (ADS)

    Habibi, F.; Moniez, M.; Ansari, R.; Rahvar, S.

    2013-04-01

    Aims: Stars twinkle because their light propagates through the atmosphere. The same phenomenon is expected on a longer time scale when the light of remote stars crosses an interstellar turbulent molecular cloud, but it has never been observed at optical wavelengths. The aim of the study described in this paper is to fully simulate the scintillation process, starting from the molecular cloud description as a fractal object, ending with the simulations of fluctuating stellar light curves. Methods: Fast Fourier transforms are first used to simulate fractal clouds. Then, the illumination pattern resulting from the crossing of background star light through these refractive clouds is calculated from a Fresnel integral that also uses fast Fourier transform techniques. Regularisation procedure and computing limitations are discussed, along with the effect of spatial and temporal coherency (source size and wavelength passband). Results: We quantify the expected modulation index of stellar light curves as a function of the turbulence strength - characterised by the diffraction radius Rdiff - and the projected source size, introduce the timing aspects, and establish connections between the light curve observables and the refractive cloud. We extend our discussion to clouds with different structure functions from Kolmogorov-type turbulence. Conclusions: Our study confirms that current telescopes of ~4 m with fast-readout, wide-field detectors have the capability of discovering the first interstellar optical scintillation effects. We also show that this effect should be unambiguously distinguished from any other type of variability through the observation of desynchronised light curves, simultaneously measured by two distant telescopes.

  9. High resolution time interval counter

    NASA Technical Reports Server (NTRS)

    Zhang, Victor S.; Davis, Dick D.; Lombardi, Michael A.

    1995-01-01

    In recent years, we have developed two types of high resolution, multi-channel time interval counters. In the NIST two-way time transfer MODEM application, the counter is designed for operating primarily in the interrupt-driven mode, with 3 start channels and 3 stop channels. The intended start and stop signals are 1 PPS, although other frequencies can also be applied to start and stop the count. The time interval counters used in the NIST Frequency Measurement and Analysis System are implemented with 7 start channels and 7 stop channels. Four of the 7 start channels are devoted to the frequencies of 1 MHz, 5 MHz or 10 MHz, while triggering signals to all other start and stop channels can range from 1 PPS to 100 kHz. Time interval interpolation plays a key role in achieving the high resolution time interval measurements for both counters. With a 10 MHz time base, both counters demonstrate a single-shot resolution of better than 40 ps, and a stability of better than 5 x 10(exp -12) (sigma(sub chi)(tau)) after self test of 1000 seconds). The maximum rate of time interval measurements (with no dead time) is 1.0 kHz for the counter used in the MODEM application and is 2.0 kHz for the counter used in the Frequency Measurement and Analysis System. The counters are implemented as plug-in units for an AT-compatible personal computer. This configuration provides an efficient way of using a computer not only to control and operate the counters, but also to store and process measured data.

  10. [Invariants of the anthropometrical proportions].

    PubMed

    Smolianinov, V V

    2012-01-01

    In this work a general interpretation of a modulor as scales of segments proportions of anthropometrical modules (extremities and a body) is made. The objects of this study were: 1) to reason the idea of the growth modulor; 2) using the modern empirical data, to prove the validity of a principle of linear similarity for anthropometrical segments; 3) to specify the system of invariants for constitutional anthropometrics.

  11. Metacarpal proportions in Australopithecus africanus.

    PubMed

    Green, David J; Gordon, Adam D

    2008-05-01

    Recent work has shown that, despite being craniodentally more derived, Australopithecus africanus had more apelike limb-size proportions than A. afarensis. Here, we test whether the A. africanus hand, as judged by metacarpal shaft and articular proportions, was similarly apelike. More specifically, did A. africanus have a short and narrow first metacarpal (MC1) relative to the other metacarpals? Proportions of both MC breadth and length were considered: the geometric mean (GM) of articular and midshaft measurements of MC1 breadth was compared to those of MC2-4, and MC1 length was compared to MC3 length individually and also to the GM of MC2 and 3 lengths. To compare the extant hominoid sample with an incomplete A. africanus fossil record (11 attributed metacarpals), a resampling procedure imposed sampling constraints on the comparative groups that produced composite intrahand ratios. Resampled ratios in the extant sample are not significantly different from actual ratios based on associated elements, demonstrating the methodological appropriateness of this technique. Australopithecus africanus metacarpals do not differ significantly from the great apes in the comparison of breadth ratios but are significantly greater than chimpanzees and orangutans in both measures of relative length. Conversely, A. africanus has a significantly smaller breadth ratio than modern humans, but does not significantly differ from this group in either measure of relative length. We conclude that the first metacarpals of A. africanus are more apelike in relative breadth while also being more humanlike in relative length, a finding consistent with previous work on A. afarensis hand proportions. This configuration would have likely promoted a high degree of manipulative dexterity, but the relatively slender, apelike first metacarpal suggests that A. africanus did not place the same mechanical demands on the thumb as more recent, stone-tool-producing hominins.

  12. Oscillatory counter-centrifugation

    NASA Astrophysics Data System (ADS)

    Xu, Shujing; Nadim, Ali

    2016-02-01

    In ordinary centrifugation, a suspended particle that is heavier than the displaced fluid migrates away from the rotation axis when the fluid-filled container rotates steadily about that axis. In contrast a particle that is lighter than the displaced fluid (e.g., a bubble) migrates toward the rotation axis in a centrifuge. In this paper, we show theoretically that if a fluid-filled container rotates in an oscillatory manner as a rigid body about an axis, at high enough oscillation frequencies, the sense of migration of suspended particles is reversed. That is, in that case particles denser than the fluid migrate inward, while those that are lighter than the fluid move outward. We term this unusual phenomenon "Oscillatory Counter-Centrifugation" or OCC, for short. Through application of the method of averaging to the equations of motion, we derive a simple criterion to predict the occurrence of OCC. The analysis also reveals that the time-average of the Coriolis force in the radial direction is the term that is responsible for this effect. In addition, we analyze the effects of the Basset history force and the Rubinow-Keller lift force on particle trajectories and find that OCC persists even when these forces are active. The phenomenon awaits experimental verification.

  13. Multiple channel programmable coincidence counter

    DOEpatents

    Arnone, Gaetano J.

    1990-01-01

    A programmable digital coincidence counter having multiple channels and featuring minimal dead time. Neutron detectors supply electrical pulses to a synchronizing circuit which in turn inputs derandomized pulses to an adding circuit. A random access memory circuit connected as a programmable length shift register receives and shifts the sum of the pulses, and outputs to a serializer. A counter is input by the adding circuit and downcounted by the seralizer, one pulse at a time. The decoded contents of the counter after each decrement is output to scalers.

  14. Development of liquid scintillator containing a zirconium complex for neutrinoless double beta decay experiment

    NASA Astrophysics Data System (ADS)

    Fukuda, Yoshiyuki; Moriyama, Shigetaka; Ogawa, Izumi

    2013-12-01

    An organic liquid scintillator containing a zirconium complex has been developed for a new neutrinoless double beta decay experiment. In order to produce a detector that has good energy resolution (4% at 2.5 MeV) and low background (0.1 counts/(t·year)) and that can monitor tons of target isotope, we chose a zirconium β-diketone complex having high solubility (over 10 wt%) in anisole. However, the absorption peak of the diketone ligand overlaps with the luminescence of anisole. Therefore, the light yield of the liquid scintillator decreases in proportion to the concentration of the complex. To avoid this problem, we synthesized a β-keto ester complex introducing -OC3H7 or -OC2H5 substituent groups in the β-diketone ligand, which shifted the absorption peak to around 245 nm, which is shorter than the emission peak of anisole (275 nm). However, the shift of the absorption peak depends on the polarity of the scintillation solvent. Therefore we must choose a low polarity solvent for the liquid scintillator. We also synthesized a Zr-ODZ complex, which has a high quantum yield (30%) and good emission wavelength (425 nm) with a solubility 5 wt% in benzonitrile. However, the absorption peak of the Zr-ODZ complex was around 240 nm. Therefore, it is better to use the scintillation solvent which has shorter luminescence wavelength than that of the aromatic solvent.

  15. Measurement of radiation damage of water-based liquid scintillator and liquid scintillator

    DOE PAGES

    Bignell, L. J.; Diwan, M. V.; Hans, S.; ...

    2015-10-19

    Liquid scintillating phantoms have been proposed as a means to perform real-time 3D dosimetry for proton therapy treatment plan verification. We have studied what effect radiation damage to the scintillator will have upon this application. We have performed measurements of the degradation of the light yield and optical attenuation length of liquid scintillator and water-based liquid scintillator after irradiation by 201 MeV proton beams that deposited doses of approximately 52 Gy, 300 Gy, and 800 Gy in the scintillator. Liquid scintillator and water-based liquid scintillator (composed of 5% scintillating phase) exhibit light yield reductions of 1.74 ± 0.55 % andmore » 1.31 ± 0.59 % after ≈ 800 Gy of proton dose, respectively. Some increased optical attenuation was observed in the irradiated samples, the measured reduction to the light yield is also due to damage to the scintillation light production. Based on our results and conservative estimates of the expected dose in a clinical context, a scintillating phantom used for proton therapy treatment plan verification would exhibit a systematic light yield reduction of approximately 0.1% after a year of operation.« less

  16. Measurement of radiation damage of water-based liquid scintillator and liquid scintillator

    SciTech Connect

    Bignell, L. J.; Diwan, M. V.; Hans, S.; Jaffe, D. E.; Rosero, R.; Vigdor, S.; Viren, B.; Worcester, E.; Yeh, M.; Zhang, C.

    2015-10-19

    Liquid scintillating phantoms have been proposed as a means to perform real-time 3D dosimetry for proton therapy treatment plan verification. We have studied what effect radiation damage to the scintillator will have upon this application. We have performed measurements of the degradation of the light yield and optical attenuation length of liquid scintillator and water-based liquid scintillator after irradiation by 201 MeV proton beams that deposited doses of approximately 52 Gy, 300 Gy, and 800 Gy in the scintillator. Liquid scintillator and water-based liquid scintillator (composed of 5% scintillating phase) exhibit light yield reductions of 1.74 ± 0.55 % and 1.31 ± 0.59 % after ≈ 800 Gy of proton dose, respectively. Some increased optical attenuation was observed in the irradiated samples, the measured reduction to the light yield is also due to damage to the scintillation light production. Based on our results and conservative estimates of the expected dose in a clinical context, a scintillating phantom used for proton therapy treatment plan verification would exhibit a systematic light yield reduction of approximately 0.1% after a year of operation.

  17. How well proportioned are lens and prism spaces?

    NASA Astrophysics Data System (ADS)

    Aurich, R.; Lustig, S.

    2012-09-01

    The cosmic microwave background (CMB) anisotropies in spherical 3-spaces with a non-trivial topology are analysed with a focus on lens- and prism-shaped fundamental cells. The conjecture is tested that well-proportioned spaces lead to a suppression of large-scale anisotropies according to the observed CMB. The focus is put on lens spaces L(p, q) which are supposed to be oddly proportioned. However, there are inhomogeneous lens spaces whose shape of the Voronoi domain depends on the position of the observer within the manifold. Such manifolds possess no fixed measure of the well-proportioned property and allow a predestined test of the well-proportioned conjecture. Topologies having the same Voronoi domain are shown to possess distinct CMB statistics which thus provide a counter-example to the well-proportioned conjecture. The CMB properties are analysed in terms of cyclic subgroups Zp, and a new point of view for the superior behaviour of the Poincaré dodecahedron is found.

  18. Effect of temperature on performance of {sup 3}He filled neutron proportional counters

    SciTech Connect

    Desai, Shraddha S.

    2014-04-24

    Neutron detectors used for cosmic neutron monitoring and various other applications are mounted in hostile environment. It is essential for detectors to sustain extreme climatic conditions, such as extreme temperature and humidity. Effort is made to evaluate the performance of detectors in extreme temperature in terms of pulse height distribution and avalanche formation. Neutron detectors filled with {sup 3}He incorporate an additive gas with quantity optimized for a particular application. Measurements are performed on neutron detectors filled with {sup 3}He and stopping gases Kr and CF{sub 4}. Detector performance for these fill gas combinations in terms of pulse height distribution is evaluated. Gas gain and Diethorn gas constants measured and analyzed for the microscopic effect on pulse formation. Results from these investigations are presented.

  19. A semi-microscopic derivation of gas gain formula for proportional counters

    NASA Astrophysics Data System (ADS)

    Mazed, D.; Baaliouamer, M.

    1999-11-01

    Using the microscopic definition of the Townsend coefficient and based on theoretical considerations related to the physical behaviour of electrons in gases in conjunction with a set of empirical results, a semi-microscopic formula of α/ N, the first Townsend coefficient to gas density ratio, is developed in the form α/N=KS exp[-(S 0/S) 1+m] , where S= E/ N is the electric field strength to gas density ratio, and K, S 0 and m (0≤m≤1) characterize the gaseous medium. It is shown that when m=0 the α/ N formula reduces to the product of the analytical forms suggested by Diethorn as well as Williams and Sara. Moreover, it is shown that Diethorn and Zastawny formulae are simply deduced, respectively, as the first- and the second-order expansions of the combined formula. Applicability of the obtained gas gain formula for different sets of experimental gas gain data bring out a good consistency of the proposed gas amplification model.

  20. Evaluation of a High Pressure Proportional Counter for the Detection of Radioactive Noble Gases

    DTIC Science & Technology

    1986-03-10

    109, and cobalt-57. ’K ’ 3 1 [,. %. . . . . . . . -Americium-241 has a half-life of 432.2 years and decays by alpha emission to neptunium - 237 ...Approximately 86 percent of these decays result in an excited state 59.537 keV above the ground state (17:430). Neptunium - 237 returns to the ground state by...to cause the resolu- tion to deteriorate to 5 percent (2.97 keY) (25: 237 ). For the anode wire used in this experiment (diameter = 0.0003" ± 2 percent

  1. Protein, DNA, and Virus Crystallography with a Focused Imaging Proportional Counter

    NASA Astrophysics Data System (ADS)

    Durbin, R. M.; Burns, R.; Moulai, J.; Metcalf, P.; Freymann, D.; Blum, M.; Anderson, J. E.; Harrison, S. C.; Wiley, D. C.

    1986-05-01

    A set of programs has been developed for rapid collection of x-ray intensity data from protein and virus crystals with a commercially available two-dimensional focused geometry electronic detector. The detector is compact and portable, with unusually high spatial resolution comparable to that used in oscillation photography. It has allowed x-ray data collection on weakly diffracting crystals with large unit cells, as well as more conventional ``diffractometer-quality'' crystals. The quality of the data is compared with that from oscillation photography and automated diffractometry in the range of unit cells from 96.3 to 383.2 angstroms. Isomorphous and anomalous difference Pattersons, based on detector data, are shown for a variable surface glycoprotein mercury derivative and for a repressor-DNA bromine derivative, which has been solved at 7 angstroms with detector data only.

  2. Discrimination of non-radiation backgrounds in the proportional counter of MARDS

    NASA Astrophysics Data System (ADS)

    Na, Liang; Xiaofeng, Guo; Fei, Luo; Fanhua, Hao; RenDe, Ze; Qingpei, Xiang; Chengsheng, Chu; Yongchun, Xiang; Zhaotong, Yan; Wei, Li

    2017-03-01

    The Movable 37Ar Rapid Detection System (MARDS) was developed by the Institute of Nuclear Physics and Chemistry of the China Academy of Engineering Physics in 2006 for on-site inspections under the Comprehensive Test Ban Treaty. It is a small and portable system that can quickly acquire data at suspected nuclear test sites. In this work, digital pulse shape discrimination (PSD) was used to process data from test samples to reduce electronic noise. The experimental results demonstrate that PSD combined with principal component analysis can classify and reject many noise sources. Thus, the threshold for the signal can be set low, expanding MARDS valid data acquisition capability, especially in very low-level and low-energy counting situations.

  3. Scintillation Breakdowns in Chip Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2008-01-01

    Scintillations in solid tantalum capacitors are momentarily local breakdowns terminated by a self-healing or conversion to a high-resistive state of the manganese oxide cathode. This conversion effectively caps the defective area of the tantalum pentoxide dielectric and prevents short-circuit failures. Typically, this type of breakdown has no immediate catastrophic consequences and is often considered as nuisance rather than a failure. Scintillation breakdowns likely do not affect failures of parts under surge current conditions, and so-called "proofing" of tantalum chip capacitors, which is a controllable exposure of the part after soldering to voltages slightly higher than the operating voltage to verify that possible scintillations are self-healed, has been shown to improve the quality of the parts. However, no in-depth studies of the effect of scintillations on reliability of tantalum capacitors have been performed so far. KEMET is using scintillation breakdown testing as a tool for assessing process improvements and to compare quality of different manufacturing lots. Nevertheless, the relationship between failures and scintillation breakdowns is not clear, and this test is not considered as suitable for lot acceptance testing. In this work, scintillation breakdowns in different military-graded and commercial tantalum capacitors were characterized and related to the rated voltages and to life test failures. A model for assessment of times to failure, based on distributions of breakdown voltages, and accelerating factors of life testing are discussed.

  4. Estimation of Fano factor in inorganic scintillators

    PubMed Central

    Bora, Vaibhav; Barrett, Harrison H.; Fastje, David; Clarkson, Eric; Furenlid, Lars; Bousselham, Abdelkader; Shah, Kanai S.; Glodo, Jarek

    2015-01-01

    The Fano factor of an integer-valued random variable is defined as the ratio of its variance to its mean. Correlation between the outputs of two photomultiplier tubes on opposite faces of a scintillation crystal was used to estimate the Fano factor of photoelectrons and scintillation photons. Correlations between the integrals of the detector outputs were used to estimate the photoelectron and photon Fano factor for YAP:Ce, SrI2:Eu and CsI:Na scintillator crystals. At 662 keV, SrI2:Eu was found to be sub-Poisson, while CsI:Na and YAP:Ce were found to be super-Poisson. An experiment setup inspired from the Hanbury Brown and Twiss experiment was used to measure the correlations as a function of time between the outputs of two photomultiplier tubes looking at the same scintillation event. A model of the scintillation and the detection processes was used to generate simulated detector outputs as a function of time for different values of Fano factor. The simulated outputs from the model for different Fano factors was compared to the experimentally measured detector outputs to estimate the Fano factor of the scintillation photons for YAP:Ce, LaBr3:Ce scintillator crystals. At 662 keV, LaBr3:Ce was found to be sub-Poisson, while YAP:Ce was found to be close to Poisson. PMID:26644631

  5. Equatorial scintillations: advances since ISEA-6

    SciTech Connect

    Not Available

    1985-01-01

    Our understanding of the morphology of equatorial scintillations has advanced due to more intensive observations at the equatorial anomaly locations in the different longitude zones. The unmistakable effect of the sunspot cycle in controlling irregularity belt width and electron concentration responsible for strong scintillation in the controlling the magnitude of scintillations has been recognized by interpreting scintillation observations inthe light of realistic models of total electron content at various longitudes. A hypothesis based on the alignment of the solar terminator with the geomagnetic flux tubes as an indicator of enhanced scintillation occurrence and another based on the influence of a transequatorial thermospheric neutral wind have been postulated to describe the observed longitudinal variation. A distinct class of equatorial irregularities known as the bottomside sinusoidal (BSS) type was identified. These irregularities occur in very large patches, sometimes in excess of several thousand kilometers in the E-W direction and are associated with frequency spread on ionograms. Scintillations caused by such irregularities exist only in the VHF band, exhibit Fresnel oscillations in intensity spectra and are found to give rise to extremely long durations (approx. several hours) of uninterrrupted scintillations.

  6. Passive Measurement of Organic-Scintillator Neutron Signatures for Nuclear Safeguards Applications

    SciTech Connect

    Jennfier L. Dolan; Eric C. Miller; Alexis C. Kaplan; Andreas Enqvist; Marek Flaska; Alice Tomanin; Paolo Peerani; David L. Chichester; Sara A. Pozzi

    2012-10-01

    At nuclear facilities, domestically and internationally, most measurement systems used for nuclear materials’ control and accountability rely on He-3 detectors. Due to resource shortages, alternatives to He-3 systems are needed. This paper presents preliminary simulation and experimental efforts to develop a fast-neutron-multiplicity counter based on liquid organic scintillators. This mission also provides the opportunity to broaden the capabilities of such safeguards measurement systems to improve current neutron-multiplicity techniques and expand the scope to encompass advanced nuclear fuels.

  7. THE MICROARCSECOND STRUCTURE OF AN ACTIVE GALACTIC NUCLEUS JET VIA INTERSTELLAR SCINTILLATION

    SciTech Connect

    Macquart, J.-P.; Godfrey, L. E. H.; Bignall, H. E.

    2013-03-10

    We describe a new tool for studying the structure and physical characteristics of ultracompact active galactic nucleus (AGN) jets and their surroundings with {mu}as precision. This tool is based on the frequency dependence of the light curves observed for intra-day variable radio sources, where the variability is caused by interstellar scintillation. We apply this method to PKS 1257-326 to resolve the core-shift as a function of frequency on scales well below {approx}12 {mu}as. We find that the frequency dependence of the position of the scintillating component is r{proportional_to}{nu}{sup -0.1{+-}0.24} (99% confidence interval) and the frequency dependence of the size of the scintillating component is d{proportional_to}{nu}{sup -0.64{+-}0.006}. Together, these results imply that the jet opening angle increases with distance along the jet: d{proportional_to}r{sup n{sub d}} with n{sub d} > 1.8. We show that the flaring of the jet, and flat frequency dependence of the core position is broadly consistent with a model in which the jet is hydrostatically confined and traversing a steep pressure gradient in the confining medium with p{proportional_to}r{sup -n{sub p}} and n{sub p} {approx}> 7. Such steep pressure gradients have previously been suggested based on very long baseline interferometry studies of the frequency dependent core shifts in AGNs.

  8. Evaluation of B10Plus+* proportional detectors for neutron coincidence counting

    SciTech Connect

    Beddingfield, David H.; Yoon, Seokryung

    2015-07-01

    GE-Reuter-Stokes (GERS) has developed a new line of neutron proportional counters, the B10Plus+* proportional counter. The detector design is intended to serve as a cost-effective alternative to traditional {sup 3}He proportional counters in a variety of applications. The detector is a hybrid design 10B-lined tube optimized with the addition of a small quantity of 3He gas to improve the detector performance and efficiency. As a demonstration of the B10Plus+* detector, GERS has constructed a Uranium Neutron Collar (UNCL) system consisting of B-10Plus+* proportional counters. GERS has designed and built a demonstration UNCL system intended to match the performance of a Type-I UNCL design in Pressurized Water Reactor (PWR) geometry operating in thermal mode. GERS offered their system on loan to the International Atomic Energy Agency (IAEA) Safeguards Division of Technical and Scientific Services for an assessment of the detector technology and the demonstration system. We have characterized the demonstration UNCL system and compared its performance with a traditional Type-I UNCL design in regular use by the IAEA. This paper summarizes our findings and observations during the characterization and testing activity. (authors)

  9. Scintillating Track Image Camera-SCITIC

    NASA Astrophysics Data System (ADS)

    Sato, Akira; Asai, Jyunkichi; Ieiri, Masaharu; Iwata, Soma; Kadowaki, Tetsuhito; Kurosawa, Maki; Nagae, Tomohumi; Nakai, Kozi

    2004-04-01

    A new type of track detector, scintillating track image camera (SCITIC) has been developed. Scintillating track images of particles in a scintillator are focused by an optical lens system on a photocathode on image intesifier tube (IIT). The image signals are amplified by an IIT-cascade and stored by a CCD camera. The performance of the detector has been tested with cosmic-ray muons and with pion- and proton-beams from the KEK 12-GeV proton synchrotron. Data of the test experiments have shown promising features of SCITIC as a triggerable track detector with a variety of possibilities.

  10. Measurement of light emission in scintillation vials

    SciTech Connect

    Duran Ramiro, M. Teresa; Garcia-Torano, Eduardo

    2005-09-15

    The efficiency and energy resolution of liquid scintillation counting (LSC) systems are strongly dependent on the optical characteristics of scintillators, vials, and reflectors. This article presents the results of measurements of the light-emission profile of scintillation vials. Two measurement techniques, autoradiographs and direct measurements with a photomultiplier tube, have been used to obtain light-emission distribution for standard vials of glass, etched glass and polyethylene. Results obtained with both techniques are in good agreement. For the first time, the effect of the meniscus in terms of light contribution has been numerically estimated. These results can help design LSC systems that are more efficient in terms of light collection.

  11. Advanced plastic scintillators for fast neutron discrimination

    SciTech Connect

    Feng, Patrick L; Anstey, Mitchell; Doty, F. Patrick; Mengesha, Wondwosen

    2014-09-01

    The present work addresses the need for solid-state, fast neutron discriminating scintillators that possess higher light yields and faster decay kinetics than existing organic scintillators. These respective attributes are of critical importance for improving the gamma-rejection capabilities and increasing the neutron discrimination performance under high-rate conditions. Two key applications that will benefit from these improvements include large-volume passive detection scenarios as well as active interrogation search for special nuclear materials. Molecular design principles were employed throughout this work, resulting in synthetically tailored materials that possess the targeted scintillation properties.

  12. Large volume flow-through scintillating detector

    DOEpatents

    Gritzo, Russ E.; Fowler, Malcolm M.

    1995-01-01

    A large volume flow through radiation detector for use in large air flow situations such as incinerator stacks or building air systems comprises a plurality of flat plates made of a scintillating material arranged parallel to the air flow. Each scintillating plate has a light guide attached which transfers light generated inside the scintillating plate to an associated photomultiplier tube. The output of the photomultiplier tubes are connected to electronics which can record any radiation and provide an alarm if appropriate for the application.

  13. Research and Development of Scintillation fiber Trackers

    SciTech Connect

    Kobayashi, A.; ITO, H.; Kawai, H.; Kodama, S.; Kaneko, N.; Han, S.

    2015-07-01

    We are developing the scintillation fiber trackers. This detector is consist of 0.5 mm diameter scintillation fibers and PPDs. This detector has the doughnut shape with outer diameter of 50 cm and inner diameter of 10 cm and thickness of 2 mm. The position resolution is 70 μm. There are no ineffective area. And the cost is several million yen. (authors)

  14. Liquid scintillators for optical fiber applications

    DOEpatents

    Franks, Larry A.; Lutz, Stephen S.

    1982-01-01

    A multicomponent liquid scintillator solution for use as a radiation-to-light converter in conjunction with a fiber optic transmission system. The scintillator includes a quantity of 1, 2, 4, 5, 3H, 6H, 1 OH, tetrahydro-8-trifluoromethyl (1) benzopyrano (9, 9a, 1-gh) quinolizin-10-one (Coumarin) as a solute in a fluor solvent such as benzyl alcohol or pseudo-cumene. The use of BIBUQ as an additional or primary solute is also disclosed.

  15. Liquid scintillators for optical fiber applications

    SciTech Connect

    Franks, L.A.; Lutz, S.S.

    1982-11-16

    A multicomponent liquid scintillator solution for use as a radiation-to-light converter in conjunction with a fiber optic transmission system. The scintillator includes a quantity of 1, 2 , 4, 5, 3H, 6H, 1 OH, tetrahydro-8-trifluoromethyl (1) benzopyrano (9, 9a, 1-gh) quinolizin-10-one (Coumarin) as a solute in a fluor solvent such as benzyl alcohol or pseudocumene. The use of bibuq as an additional or primary solute is also disclosed.

  16. Ternary liquid scintillator for optical fiber applications

    DOEpatents

    Franks, Larry A.; Lutz, Stephen S.

    1982-01-01

    A multicomponent liquid scintillator solution for use as a radiation-to-light converter in conjunction with a fiber optic transmission system. The scintillator includes a quantity of 5-amino-9-diethylaminobenz (a) phenoxazonium nitrate (Nile Blue Nitrate) as a solute in a fluor solvent such as benzyl alcohol. The use of PPD as an additional solute is also disclosed. The system is controllable by addition of a suitable quenching agent, such as phenol.

  17. Current status on plastic scintillators modifications.

    PubMed

    Bertrand, Guillaume H V; Hamel, Matthieu; Sguerra, Fabien

    2014-11-24

    Recent developments of plastic scintillators are reviewed, from 2000 to March 2014, distributed in two different chapters. First chapter deals with the chemical modifications of the polymer backbone, whereas modifications of the fluorescent probe are presented in the second chapter. All examples are provided with the scope of detection of various radiation particles. The main characteristics of these newly created scintillators and their detection properties are given.

  18. Real-time volumetric scintillation dosimetry

    NASA Astrophysics Data System (ADS)

    Beddar, S.

    2015-01-01

    The goal of this brief review is to review the current status of real-time 3D scintillation dosimetry and what has been done so far in this area. The basic concept is to use a large volume of a scintillator material (liquid or solid) to measure or image the dose distributions from external radiation therapy (RT) beams in three dimensions. In this configuration, the scintillator material fulfills the dual role of being the detector and the phantom material in which the measurements are being performed. In this case, dose perturbations caused by the introduction of a detector within a phantom will not be at issue. All the detector configurations that have been conceived to date used a Charge-Coupled Device (CCD) camera to measure the light produced within the scintillator. In order to accurately measure the scintillation light, one must correct for various optical artefacts that arise as the light propagates from the scintillating centers through the optical chain to the CCD chip. Quenching, defined in its simplest form as a nonlinear response to high-linear energy transfer (LET) charged particles, is one of the disadvantages when such systems are used to measure the absorbed dose from high-LET particles such protons. However, correction methods that restore the linear dose response through the whole proton range have been proven to be effective for both liquid and plastic scintillators. Volumetric scintillation dosimetry has the potential to provide fast, high-resolution and accurate 3D imaging of RT dose distributions. Further research is warranted to optimize the necessary image reconstruction methods and optical corrections needed to achieve its full potential.

  19. Multi-GNSS for Ionospheric Scintillation Studies

    NASA Astrophysics Data System (ADS)

    Morton, Y.

    2015-12-01

    GNSS have been widely used for ionospheric monitoring. We anticipate over 160 GNSS satellites broadcasting 400 signals by 2023, nearly double the number today. With their well-defined signal structures, high spatial density and spectral diversity, GNSS offers low cost and distributed passive sensing of ionosphere effects. There are, however, many challenges to utilize GNSS resources to characterize and forecast ionospheric scintillation. Originally intended for navigation purposes, GNSS receivers are designed to filter out nuisance effects due to ionosphere effects. GNSS measurements are plagued with errors from multipath, oscillator jitters, processing artifacts, and neutral atmosphere effects. Strong scintillation events are often characterized by turbulent structures in ionosphere, causing simultaneous deep amplitude fading and abrupt carrier phase changes. The combined weak signal and high carrier dynamics imposes conflicting requirements for GNSS receiver design. Therefore, GNSS receivers often experience cycle slips and loss of lock of signals during strong scintillation events. High quality, raw GNSS signals bearing space weather signatures and robust receiver algorithms designed to capture these signatures are needed in order for GNSS to be a reliable and useful agent for scintillation monitoring and forecasting. Our event-driven, reconfigurable data collection system is designed to achieve this purpose. To date, our global network has collected ~150TB of raw GNSS data during space weather events. A suite of novel receiver processing algorithms has been developed by exploitating GNSS spatial, frequency, temporal, and constellation diversity to process signals experiencing challenging scintillation impact. The algorithms and data have advanced our understanding of scintillation impact on GNSS, lead to more robust receiver technologies, and enabled high spatial and temporal resolution depiction of ionosphere responses to solar and geomagnetic conditions. This

  20. Proportional Reasoning: A Review of the Literature.

    ERIC Educational Resources Information Center

    Tourniaire, Francoise; Pulos, Steven

    1985-01-01

    The literature on proportional reasoning is reviewed. After methodology is discussed, strategies used to solve proportion problems, variables that influence performance, and training studies are each considered. (MNS)

  1. The statistical distribution of the number of counted scintillation photons in digital silicon photomultipliers: model and validation.

    PubMed

    van Dam, Herman T; Seifert, Stefan; Schaart, Dennis R

    2012-08-07

    In the design and application of scintillation detectors based on silicon photomultipliers (SiPMs), e.g. in positron emission tomography imaging, it is important to understand and quantify the non-proportionality of the SiPM response due to saturation, crosstalk and dark counts. A new type of SiPM, the so-called digital silicon photomultiplier (dSiPM), has recently been introduced. Here, we develop a model of the probability distribution of the number of fired microcells, i.e. the number of counted scintillation photons, in response to a given amount of energy deposited in a scintillator optically coupled to a dSiPM. Based on physical and functional principles, the model elucidates the statistical behavior of dSiPMs. The model takes into account the photon detection efficiency of the detector; the light yield, excess variance and time profile of the scintillator; and the crosstalk probability, dark count rate, integration time and the number of microcells of the dSiPM. Furthermore, relations for the expectation value and the variance of the number of fired cells are deduced. These relations are applied in the experimental validation of the model using a dSiPM coupled to a LSO:Ce,Ca scintillator. Finally, we propose an accurate method for the correction of energy spectra measured with dSiPM-based scintillation detectors.

  2. Development of Novel Polycrystalline Ceramic Scintillators

    SciTech Connect

    Wisniewska, Monika; Boatner, Lynn A; Neal, John S; Jellison Jr, Gerald Earle; Ramey, Joanne Oxendine; North, Andrea L; Wisniewski, Monica; Payzant, E Andrew; Howe, Jane Y; Lempicki, Aleksander; Brecher, Charlie; Glodo, J.

    2008-01-01

    For several decades most of the efforts to develop new scintillator materials have concentrated on high-light-yield inorganic single-crystals while polycrystalline ceramic scintillators, since their inception in the early 1980 s, have received relatively little attention. Nevertheless, transparent ceramics offer a promising approach to the fabrication of relatively inexpensive scintillators via a simple mechanical compaction and annealing process that eliminates single-crystal growth. Until recently, commonly accepted concepts restricted the polycrystalline ceramic approach to materials exhibiting a cubic crystal structure. Here, we report our results on the development of two novel ceramic scintillators based on the non-cubic crystalline materials: Lu SiO:Ce (LSO:Ce) and LaBr:Ce. While no evidence for texturing has been found in their ceramic microstructures, our LSO:Ce ceramics exhibit a surprisingly high level of transparency/ translucency and very good scintillation characteristics. The LSO:Ce ceramic scintillation reaches a light yield level of about 86% of that of a good LSO:Ce single crystal, and its decay time is even faster than in single crystals. Research on LaBr:Ce shows that translucent ceramics of the high-light-yield rare-earth halides can also be synthesized. Our LaBr:Ce ceramics have light yields above 42 000 photons/MeV (i.e., 70%of the single-crystal light yield).

  3. Validating the use of scintillation proxies to study ionospheric scintillation over the Ugandan region

    NASA Astrophysics Data System (ADS)

    Amabayo, Emirant B.; Jurua, Edward; Cilliers, Pierre J.

    2015-06-01

    In this study, we compare the standard scintillation indices (S4 and σΦ) from a SCINDA receiver with scintillation proxies (S4p and | sDPR |) derived from two IGS GPS receivers. Amplitude (S4) and phase (σΦ) scintillation data were obtained from the SCINDA installed at Makerere University (0.34°N, 32.57°E). The corresponding amplitude (S4p) and phase (| sDPR |) scintillation proxies were derived from data archived by IGS GPS receivers installed at Entebbe (0.04°N, 32.44°E) and Mbarara (0.60°S, 30.74°E). The results show that for most of the cases analysed in this study, σΦ and | sDPR | are in agreement. Amplitude scintillation occurrence estimated using the S4p are fairly consistent with the standard S4, mainly between 17:00 UT and 21:00 UT, despite a few cases of over and under estimation of scintillation levels by S4p. Correlation coefficients between σΦ and the | sDPR | proxy revealed positive correlation. Generally, S4p and S4 exhibits both moderate and strong positive correlation. TEC depletions associated with equatorial plasma bubbles are proposed as the cause of the observed scintillation over the region. These equatorial plasma bubbles were evident along the ray paths to satellites with PRN 2, 15, 27 and 11 as observed from MBAR and EBBE. In addition to equatorial plasma bubbles, atmospheric gravity waves with periods similar to those of large scale traveling ionospheric disturbances were also observed as one of the mechanisms for scintillation occurrence. The outcome of this study implies that GPS derived scintillation proxies can be used to quantify scintillation levels in the absence of standard scintillation data in the equatorial regions.

  4. Pyrochemical neutron multiplicity counter design

    SciTech Connect

    Langner, D.G.; Ensslin, N.; Krick, M.S.

    1990-01-01

    Pyrochemical process materials are difficult to measure using conventional neutron counting methods because of significant self- multiplication and variable ({alpha},n) reaction rates. Multiplicity counters measure the first three moments of the neutron multiplicity distribution and thus make it possible to determine sample mass even when multiplication and ({alpha},n) rate are unknown. A new multiplicity counter suitable for inplant measurement of pyrochemical process materials has been designed using Monte Carlo simulations. The goals were to produce a counter that has high neutron detection efficiency, low die-away time, a flat spatial efficiency profile, and is insensitive to the neutron energy spectrum. Monte Carlo calculations were performed for several prototype models consisting of four rings of 71-cm active length {sup 3}He tubes in a polyethylene body. The cadmium-lined sample well is 25 cm in diameter to accommodate a wide variety of inplant sample containers. The counter can be free-standing or in-line without mechanical modification. The calculations were performed to determine the above design criteria for several configurations of tube spacing, cadmium liners, and sample height. Calculations were also performed for distributed sample sources to understand the integrated effects of variable neutron spectra on the counter. 5 refs., 8 figs., 1 tab.

  5. Analytical expressions for the gate utilization factors of passive multiplicity counters including signal build-up

    SciTech Connect

    Croft, Stephen; Evans, Louise G; Schear, Melissa A

    2010-01-01

    In the realm of nuclear safeguards, passive neutron multiplicity counting using shift register pulse train analysis to nondestructively quantify Pu in product materials is a familiar and widely applied technique. The approach most commonly taken is to construct a neutron detector consisting of {sup 3}He filled cylindrical proportional counters embedded in a high density polyethylene moderator. Fast neutrons from the item enter the moderator and are quickly slowed down, on timescales of the order of 1-2 {micro}s, creating a thermal population which then persists typically for several 10's {micro}s and is sampled by the {sup 3}He detectors. Because the initial transient is of comparatively short duration it has been traditional to treat it as instantaneous and furthermore to approximate the subsequent capture time distribution as exponential in shape. With these approximations simple expressions for the various Gate Utilization Factors (GUFs) can be obtained. These factors represent the proportion of time correlated events i.e. Doubles and Triples signal present in the pulse train that is detected by the coincidence gate structure chosen (predelay and gate width settings of the multiplicity shift register). More complicated expressions can be derived by generalizing the capture time distribution to multiple time components or harmonics typically present in real systems. When it comes to applying passive neutron multiplicity methods to extremely intense (i.e. high emission rate and highly multiplying) neutron sources there is a drive to use detector types with very fast response characteristics in order to cope with the high rates. In addition to short pulse width, detectors with a short capture time profile are also desirable so that a short coincidence gate width can be set in order to reduce the chance or Accidental coincidence signal. In extreme cases, such as might be realized using boron loaded scintillators, the dieaway time may be so short that the build

  6. Optimization of screening for radioactivity in urine by liquid scintillation.

    SciTech Connect

    Shanks, Sonoya Toyoko; Reese, Robert P.; Preston, Rose T.

    2007-08-01

    Numerous events have or could have resulted in the inadvertent uptake of radionuclides by fairly large populations. Should a population receive an uptake, valuable information could be obtained by using liquid scintillation counting (LSC) techniques to quickly screen urine from a sample of the affected population. This study investigates such LSC parameters as discrimination, quench, volume, and count time to yield guidelines for analyzing urine in an emergency situation. Through analyzing variations of the volume and their relationships to the minimum detectable activity (MDA), the optimum ratio of sample size to scintillating chemical cocktail was found to be 1:3. Using this optimum volume size, the alpha MDA varied from 2100 pCi/L for a 30-second count time to 35 pCi/L for a 1000-minute count time. The typical count time used by the Sandia National Laboratories Radiation Protection Sample Diagnostics program is 30 minutes, which yields an alpha MDA of 200 pCi/L. Because MDA is inversely proportional to the square root of the count time, count time can be reduced in an emergency situation to achieve the desired MDA or response time. Note that approximately 25% of the response time is used to prepare the samples and complete the associated paperwork. It was also found that if the nuclide of interest is an unknown, pregenerated discriminator settings and efficiency calibrations can be used to produce an activity value within a factor of two, which is acceptable for a screening method.

  7. LiF/ZnS Neutron Multiplicity Counter

    SciTech Connect

    Stave, Sean C.; Bliss, Mary; Kouzes, Richard T.; Lintereur, Azaree T.; Robinson, Sean M.; Siciliano, Edward R.; Wood, Lynn S.

    2015-06-01

    Abstract: Alternatives to the use of 3He for the detection of thermal neutrons are being investigated. One of the most challenging applications for 3He alternatives is in neutron multiplicity counters. Neutron multiplicity counters are used to provide rapid assay of samples which contain an unknown amount of plutonium in a potentially unknown configuration. With appropriate detector design, the neutron single, double, and triple coincidence events can be used to extract information of three unknown parameters such as the 240Pu-effective mass, the sample self-multiplication, and the (α,n) rate. A project at PNNL has investigated replacing 3He-based tubes with LiF/ZnS neutron-scintillator sheets and wavelength shifting plastic for light pipes. A four-panel demonstrator module has been constructed, tested, and compared with detailed modeling results. The findings indicate that a full-scale system can be constructed with the same overall size as the most efficient 3He-based system and with improved performance. Remaining design challenges include electronics and robust neutron/gamma-ray discrimination based on pulse shape analysis at high rates. A review of the current effort and the most recent findings will be presented.

  8. From Cigala to Calibra: AN Infrastructure for Ionospheric Scintillation Monitoring in Brazil

    NASA Astrophysics Data System (ADS)

    Monico, J. G.; Camargo, P. D.; Alves, D. B.; Aquino, M.; Pereira, V. S.; Vani, B.

    2013-05-01

    The CIGALA (Concept for Ionospheric Scintillation Mitigation for Professional GNSS in Latin America) project was funded by the European Commission (EC) in the framework of the FP7-GALILEO-2009-GSA (European GNSS Agency ) activity. It was concluded in February 2012 but the network of GNSS receivers deployed in Brazil remain in operation, continuously collecting data. One of the aims of the project was to create a data base of ionospheric parameters to help analyze TEC and scintillation effects on GNSS. Details of the project can be found at http://is-cigala-calibra.fct.unesp.br/cigala2/#. Following CIGALA, the CALIBRA (Countering GNSS high Accuracy applications Limitations due to Ionospheric disturbances in BRAzil) project was approved, also funded by the EC/GSA. CALIBRA aims to improve existing algorithms and develop new ones that can be applied to high accuracy GNSS techniques in order to tackle the effects of ionospheric disturbances. Through this project the CIGALA network will be expanded. The objective of this presentation is to give details of the CALIBRA and CIGALA projects, mainly concerning the infrastructure setup in Brazil aiming to study effects related to Ionospheric Scintillation.

  9. Measurement of tritium with plastic scintillator surface improvement with plasma treatment

    SciTech Connect

    Yoshihara, Y.; Furuta, E.; Ohyama, R.I.; Yokota, S.; Kato, Y.; Yoshimura, T.; Ogiwara, K.

    2015-03-15

    Tritium is usually measured by using a liquid scintillation counter. However, liquid scintillator used for measurement will become radioactive waste fluid. To solve this issue, we have developed a method of measuring tritium samples with plasma-treated plastic scintillator (PS)sheets (Plasma method). The radioactive sample is held between 2 PS sheets and the whole is enclosed in a a low-potassium glass vial. With the Plasma method of 2-min plasma treatment, we have obtained measurement efficiency of 48 ± 2 % for 2 min measurement of tritium except for tritiated water. The plasma treatment makes the PS surface rough and hydrophilic which contributes to improve the contact between tritium and PS. On the other hand, it needed almost 6 hours to obtain constant measurement efficiency. The reason was that the dry-up handling in the vial needed longer time to vaporize H{sub 2}O molecules than in the air. We tried putting silica gel beads into vials to remove H{sub 2}O molecules from PS sheet surface quickly. The silica gel beads worked well and we got constant measurement efficiency within 1-3 hours. Also, we tried using other kinds of PS treated with plasma to obtain higher measurement efficiencies of tritium samples.

  10. Validation of the MCNPX-PoliMi Code to Design a Fast-Neutron Multiplicity Counter

    SciTech Connect

    J. L. Dolan; A. C. Kaplan; M. Flaska; S. A. Pozzi; D. L. Chichester

    2012-07-01

    Many safeguards measurement systems used at nuclear facilities, both domestically and internationally, rely on He-3 detectors and well established mathematical equations to interpret coincidence and multiplicity-type measurements for verifying quantities of special nuclear material. Due to resource shortages alternatives to these existing He-3 based systems are being sought. Work is also underway to broaden the capabilities of these types of measurement systems in order to improve current multiplicity analysis techniques. As a part of a Material Protection, Accounting, and Control Technology (MPACT) project within the U.S. Department of Energy's Fuel Cycle Technology Program we are designing a fast-neutron multiplicity counter with organic liquid scintillators to quantify important quantities such as plutonium mass. We are also examining the potential benefits of using fast-neutron detectors for multiplicity analysis of advanced fuels in comparison with He-3 detectors and testing the performance of such designs. The designs are being developed and optimized using the MCNPX-PoliMi transport code to study detector response. In the full paper, we will discuss validation measurements used to justify the use of the MCNPX-PoliMi code paired with the MPPost multiplicity routine to design a fast neutron multiplicity counter with liquid scintillators. This multiplicity counter will be designed with the end goal of safeguarding advanced nuclear fuels. With improved timing qualities associated with liquid scintillation detectors, we can design a system that is less limited by nuclear materials of high activities. Initial testing of the designed system with nuclear fuels will take place at Idaho National Laboratory in a later stage of this collaboration.

  11. The use of caesium iodide mini scintillation counters for dual isotope pulmonary capillary permeability studies.

    PubMed

    Hunter, D N; Lawrence, R; Morgan, C J; Evans, T W

    1990-12-01

    A commercially available system of caesium iodide crystal mini-detectors (Oakfield Instruments, Oxon, UK) was modified so that it was suitable for dual isotopic measurement of the plasma protein accumulation index (PPA)- a measure of pulmonary endothelial permeability. Using this modified system the mean PPA x 10(-3) min-1 +/- (S.E.M.) recorded in 11 normal subjects (22 lungs) was 0.18 (0.08) and in 6 patients (9 lungs) with the adult respiratory distress syndrome was 2.88 (0.63) (P less than 0.02). These values for PPA concur with those found by other groups using larger sodium iodide detectors. We conclude that with simple modification caesium iodide mini-detectors may be used successfully for the measurement of PPA in the intensive care setting.

  12. Strontium and barium iodide high light yield scintillators

    NASA Astrophysics Data System (ADS)

    Cherepy, Nerine J.; Hull, Giulia; Drobshoff, Alexander D.; Payne, Stephen A.; van Loef, Edgar; Wilson, Cody M.; Shah, Kanai S.; Roy, Utpal N.; Burger, Arnold; Boatner, Lynn A.; Choong, Woon-Seng; Moses, William W.

    2008-02-01

    Europium-doped strontium and barium iodide are found to be readily growable by the Bridgman method and to produce high scintillation light yields. SrI2(Eu ) emits into the Eu2+ band, centered at 435nm, with a decay time of 1.2μs and a light yield of ˜90000photons/MeV. It offers energy resolution better than 4% full width at half maximum at 662keV, and exhibits excellent light yield proportionality. BaI2(Eu ) produces >30000photons/MeV into the Eu2+ band at 420nm (<1μs decay). An additional broad impurity-mediated recombination band is present at 550nm (>3μs decay), unless high-purity feedstock is used.

  13. Set-up of a new TDCR counter at IRA-METAS.

    PubMed

    Nedjadi, Youcef; Bailat, Claude; Caffari, Yvan; Cassette, Philippe; Bochud, François

    2015-03-01

    A triple-to-double coincidence ratio (TDCR) counter was recently constructed at IRA-METAS for liquid scintillation based primary activity standardisations. A description of its optical chamber, efficiency change tools, photomultiplier tubes (PMTs) and electronics is given. This TDCR system was validated by measuring several standard solutions of beta emitters including (45)Ca, (14)C, (63)Ni and (3)H. The activity concentrations, obtained from these measurements and efficiencies computed with a FORTRAN code we developed for symmetric and asymmetric PMTs, agree with the certified values within uncertainties.

  14. The Eros of Counter Education

    ERIC Educational Resources Information Center

    Luzon, Pinhas

    2016-01-01

    Erotic Counter Education (ECE) is the educational position of the late Ilan Gur-Ze'ev. In ECE Gur-Ze'ev combines two opposing positions in the philosophy of education, one teleological and anti-utopian, the other teleological and utopian. In light of this unique combination, I ask what mediates between these two poles and suggest that the answer…

  15. High resolution time interval counter

    DOEpatents

    Condreva, K.J.

    1994-07-26

    A high resolution counter circuit measures the time interval between the occurrence of an initial and a subsequent electrical pulse to two nanoseconds resolution using an eight megahertz clock. The circuit includes a main counter for receiving electrical pulses and generating a binary word--a measure of the number of eight megahertz clock pulses occurring between the signals. A pair of first and second pulse stretchers receive the signal and generate a pair of output signals whose widths are approximately sixty-four times the time between the receipt of the signals by the respective pulse stretchers and the receipt by the respective pulse stretchers of a second subsequent clock pulse. Output signals are thereafter supplied to a pair of start and stop counters operable to generate a pair of binary output words representative of the measure of the width of the pulses to a resolution of two nanoseconds. Errors associated with the pulse stretchers are corrected by providing calibration data to both stretcher circuits, and recording start and stop counter values. Stretched initial and subsequent signals are combined with autocalibration data and supplied to an arithmetic logic unit to determine the time interval in nanoseconds between the pair of electrical pulses being measured. 3 figs.

  16. High resolution time interval counter

    DOEpatents

    Condreva, Kenneth J.

    1994-01-01

    A high resolution counter circuit measures the time interval between the occurrence of an initial and a subsequent electrical pulse to two nanoseconds resolution using an eight megahertz clock. The circuit includes a main counter for receiving electrical pulses and generating a binary word--a measure of the number of eight megahertz clock pulses occurring between the signals. A pair of first and second pulse stretchers receive the signal and generate a pair of output signals whose widths are approximately sixty-four times the time between the receipt of the signals by the respective pulse stretchers and the receipt by the respective pulse stretchers of a second subsequent clock pulse. Output signals are thereafter supplied to a pair of start and stop counters operable to generate a pair of binary output words representative of the measure of the width of the pulses to a resolution of two nanoseconds. Errors associated with the pulse stretchers are corrected by providing calibration data to both stretcher circuits, and recording start and stop counter values. Stretched initial and subsequent signals are combined with autocalibration data and supplied to an arithmetic logic unit to determine the time interval in nanoseconds between the pair of electrical pulses being measured.

  17. Mercuric iodide photodetectors for scintillation spectroscopy

    SciTech Connect

    Markakis, J.; Dabrowski, A.; Iwanczyk, J.; Ortale, C.; Schnepple, W.

    1985-02-01

    We have measured the responses to /sup 137/Cs (662 keV) of both a 1-inch-diam by 2-inch-thick NaI(Tl) scintillator optically coupled to a 1-inch-diam by 800-..mu..mthick mercuric iodide (HgI/sub 2/) photodetector, and a 1-cmdiam by 1-cm-thick CaWO/sub 4/ scintillator coupled to a 1.3-cm-diam by 600-..mu..m-thick HgI/sub 2/ photodetector. Best spectral resolution to /sup 137/Cs was 7.8% FWHM for the NaI(Tl)-HgI/sub 2/ and 12.5% FWHM for the CaWO/sub 4/-HgI/sub 2/ detectors; peak-to-valley ratios were 26:1 and 16:1, respectively. HgI/sub 2/ detectors operate at room temperature and their use in scintillation spectroscopy presents the ultimate miniaturization of scintillation detectors, limited mainly by the size of the scintillation crystal.

  18. Mercuric iodide photodetectors for scintillation spectroscopy

    SciTech Connect

    Markakis, J.; Ortale, C.; Schnepple, W.; Iwanczyk, J.; Dabrowski, A.

    1984-01-01

    We have measured the responses to /sup 137/Cs (662 keV) of both a 1-inch-diam by 2-inch-thick NaI(Tl) scintillator optically coupled to a 1-inch-diam by 800-..mu..m-thick mercuric iodide (HgI/sub 2/) photodetector, and a 1-cm-diam by 1-cm-thick CaWO/sub 4/ scintillator coupled to a 1.3-cm-diam by 600-..mu..m-thick HgI/sub 2/ photodetector. Best spectral resolution to /sup 137/Cs was 7.8% FWHM for the NaI(Tl)-HgI/sub 2/ and 12.5% FWHM for the CaWO/sub 4/-HgI/sub 2/ detectors; peak-to-valley ratios were 26:1 and 16:1, respectively. HgI/sub 2/ detectors operate at room temperature and their use in scintillation spectroscopy presents the ultimate miniaturization of scintillation detectors, limited mainly by the size of the scintillation crystal.

  19. Characteristics of Un doped and Europium-dopedSrI2 Scintillator Detectors

    SciTech Connect

    Sturm, Benjamin; Cherepy, Nerine; Drury, Owen; Thelin, P; Fisher, S E; O’Neal, S P; Payne, Stephen A.; Burger, Arnold; Boatner, Lynn A; Ramey, Joanne Oxendine; Shah, Kanai; Hawrami, Rastgo

    2012-01-01

    High energy resolution gamma-ray detectors that can be formed into relatively large sizes while operating at room temperature offer many advantages for national security applications. We are working toward that goal through the development of SrI{sub 2}(Eu) scintillator detectors, which routinely provide <;3.0% energy resolution at 662 keV with volumes >;10 cm{sup 3}. In this study, we have tested pure, undoped SrI{sub 2} to gain a better understanding of the scintillation properties and spectroscopic performance achievable without activation. An undoped crystal grown from 99.999% pure SrI{sub 2} pellets was tested for its spectroscopic performance, its light yield, and uniformity of scintillation light collection as a function of gamma-ray interaction position relative to the crystal growth direction. Undoped SrI{sub 2} was found to provide energy resolution of 5.3% at 662 keV, and the light collection nonuniformity varied by only 0.72% over the length of the crystal. Measurements of both a 3% Eu-doped and the undoped SrI{sub 2} crystal were carried out in the SLYNCI facility and indicate differences in their light yield non-proportionality. The surprisingly good scintillation properties of the pure SrI{sub 2} crystal suggests that with high-purity feedstock, further reduction of the Eu concentration can be made to grow larger crystals while not adversely impacting the spectroscopic performance.

  20. Imaging Gas Counters for X- and Gamma Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Ramsey, Brian D.

    1995-01-01

    Gas-filled detectors, such as proportional counters, have long been used in x-ray astronomy. They are robust, relatively easy to fabricate, and can provide large collecting areas with reasonable spatial and energy resolution. Despite coming of age in the 50's and 60's, their versatility is such that they are still planned for future missions. A vigorous development program, led mostly by the high energy physics community, has ensured continued improvements in proportional counter technology. These include multistep counters, microstrip technologies and optical avalanche chambers. High fill-gas pressures and the use of suitable converters permit operation up to 100s of GeV. The current status of imaging gas-filled detectors will be reviewed, concentrating on the lower energy region (less than 100 keV) but also briefly covering higher energy applications up to the GeV region. This review is not intended to be exhaustive and draws heavily on work currently in progress at MSFC.

  1. Basic Research Needs for Countering Terrorism

    SciTech Connect

    Stevens, W.; Michalske, T.; Trewhella, J.; Makowski, L.; Swanson, B.; Colson, S.; Hazen, T.; Roberto, F.; Franz, D.; Resnick, G.; Jacobson, S.; Valdez, J.; Gourley, P.; Tadros, M.; Sigman, M.; Sailor, M.; Ramsey, M.; Smith, B.; Shea, K.; Hrbek, J.; Rodacy, P.; Tevault, D.; Edelstein, N.; Beitz, J.; Burns, C.; Choppin, G.; Clark, S.; Dietz, M.; Rogers, R.; Traina, S.; Baldwin, D.; Thurnauer, M.; Hall, G.; Newman, L.; Miller, D.; Kung, H.; Parkin, D.; Shuh, D.; Shaw, H.; Terminello, L.; Meisel, D.; Blake, D.; Buchanan, M.; Roberto, J.; Colson, S.; Carling, R.; Samara, G.; Sasaki, D.; Pianetta, P.; Faison, B.; Thomassen, D.; Fryberger, T.; Kiernan, G.; Kreisler, M.; Morgan, L.; Hicks, J.; Dehmer, J.; Kerr, L.; Smith, B.; Mays, J.; Clark, S.

    2002-03-01

    To identify connections between technology needs for countering terrorism and underlying science issues and to recommend investment strategies to increase the impact of basic research on efforts to counter terrorism.

  2. Tomographic analysis of neutron and gamma pulse shape distributions from liquid scintillation detectors at Joint European Torus

    SciTech Connect

    Giacomelli, L.; Conroy, S.; Gorini, G.; Horton, L.; Murari, A.; Popovichev, S.; Syme, D. B.

    2014-02-15

    The Joint European Torus (JET, Culham, UK) is the largest tokamak in the world devoted to nuclear fusion experiments of magnetic confined Deuterium (D)/Deuterium-Tritium (DT) plasmas. Neutrons produced in these plasmas are measured using various types of neutron detectors and spectrometers. Two of these instruments on JET make use of organic liquid scintillator detectors. The neutron emission profile monitor implements 19 liquid scintillation counters to detect the 2.45 MeV neutron emission from D plasmas. A new compact neutron spectrometer is operational at JET since 2010 to measure the neutron energy spectra from both D and DT plasmas. Liquid scintillation detectors are sensitive to both neutron and gamma radiation but give light responses of different decay time such that pulse shape discrimination techniques can be applied to identify the neutron contribution of interest from the data. The most common technique consists of integrating the radiation pulse shapes within different ranges of their rising and/or trailing edges. In this article, a step forward in this type of analysis is presented. The method applies a tomographic analysis of the 3-dimensional neutron and gamma pulse shape and pulse height distribution data obtained from liquid scintillation detectors such that n/γ discrimination can be improved to lower energies and additional information can be gained on neutron contributions to the gamma events and vice versa.

  3. Isotopic response with small scintillator based gamma-ray spectrometers

    DOEpatents

    Madden, Norman W [Sparks, NV; Goulding, Frederick S [Lafayette, CA; Asztalos, Stephen J [Oakland, CA

    2012-01-24

    The intrinsic background of a gamma ray spectrometer is significantly reduced by surrounding the scintillator with a second scintillator. This second (external) scintillator surrounds the first scintillator and has an opening of approximately the same diameter as the smaller central scintillator in the forward direction. The second scintillator is selected to have a higher atomic number, and thus has a larger probability for a Compton scattering interaction than within the inner region. Scattering events that are essentially simultaneous in coincidence to the first and second scintillators, from an electronics perspective, are precluded electronically from the data stream. Thus, only gamma-rays that are wholly contained in the smaller central scintillator are used for analytic purposes.

  4. Cosmic ray studies with a gas Cerenkov counter in association with an ionization spectrometer

    NASA Technical Reports Server (NTRS)

    Balasubrahmanyan, V. K.; Ormes, J. F.; Arens, J. F.; Siohan, F.; Simon, M.; Spiegelhauer, H.; Yodh, G. B.

    1980-01-01

    The results from a balloon-borne gas Cerenkov counter (threshold 16.5 GeV/nuc) and an ionization spectrometer are presented. The gas Cerenkov counter provides an absolute energy calibration for the response of the calorimeter for the Z range of 5-26 nuclei of cosmic rays. The contribution of scintillation to the gas Cerenkov pulse height has been obtained by independently selecting particles below the gas Cerenkov threshold using the ionization spectrometer. Energy spectra were derived by minimizing the chi-squared between a Monte Carlo simulated data and flight data. Best fit power laws were determined for C, N, O, Ne, Mg, and Si. The power laws, all consistent with E exp-2.7, are not good fits to the data. A better fit is obtained using the spectrum derived from the spectrometer.

  5. Cosmic ray studies with a gas Cherenkov counter in association with an ionization spectrometer

    NASA Technical Reports Server (NTRS)

    Balasubrahmanyan, V. K.; Ormes, J. F.; Arens, J. F.; Siohan, F.; Yodh, G. B.; Simon, M.; Spiegelhauer, H.

    1980-01-01

    The results from a balloon-borne gas Cherenkov counter (threshold 16.5 GeV/nucleon) and an ionization spectrometer are presented. The gas Cherenkov counter provides an absolute energy distribution for the response of the calorimeter for 5 or = Z 26 nuclei of cosmic rays. The contribution of scintillation to the gas Cherenkov pulse height was obtained by independently selecting particles below the gas Cherenkov threshold using the ionization spectrometer. Energy spectra were derived by minimizing the chi squared between Monte Carlo simulted data and flight data. Best fit power laws, dN/dE = AE-gamma, were determined for C, N, O, Ne, Mg, and Si. The power laws, all consistent with E (-2.7) are not good fits to the data. A better fit is obtained using the spectrum derived from the spectrometer. The data from the ionization calorimeter and the gas Cherenkov are thus completely self-consistent.

  6. Optimization of simultaneous tritium–radiocarbon internal gas proportional counting

    SciTech Connect

    Bonicalzi, R. M.; Aalseth, C. E.; Day, A. R.; Hoppe, E. W.; Mace, E. K.; Moran, J. J.; Overman, C. T.; Panisko, M. E.; Seifert, A.

    2016-03-01

    Specific environmental applications can benefit from dual tritium and radiocarbon measurements in a single compound. Assuming typical environmental levels, it is often the low tritium activity relative to the higher radiocarbon activity that limits the dual measurement. In this paper, we explore the parameter space for a combined tritium and radiocarbon measurement using a methane sample mixed with an argon fill gas in low-background proportional counters of a specific design. We present an optimized methane percentage, detector fill pressure, and analysis energy windows to maximize measurement sensitivity while minimizing count time. The final optimized method uses a 9-atm fill of P35 (35% methane, 65% argon), and a tritium analysis window from 1.5 to 10.3 keV, which stops short of the tritium beta decay endpoint energy of 18.6 keV. This method optimizes tritium counting efficiency while minimizing radiocarbon beta decay interference.

  7. Optimization of simultaneous tritium-radiocarbon internal gas proportional counting

    NASA Astrophysics Data System (ADS)

    Bonicalzi, R. M.; Aalseth, C. E.; Day, A. R.; Hoppe, E. W.; Mace, E. K.; Moran, J. J.; Overman, C. T.; Panisko, M. E.; Seifert, A.

    2016-03-01

    Specific environmental applications can benefit from dual tritium and radiocarbon measurements in a single compound. Assuming typical environmental levels, it is often the low tritium activity relative to the higher radiocarbon activity that limits the dual measurement. In this paper, we explore the parameter space for a combined tritium and radiocarbon measurement using a natural methane sample mixed with an argon fill gas in low-background proportional counters of a specific design. We present an optimized methane percentage, detector fill pressure, and analysis energy windows to maximize measurement sensitivity while minimizing count time. The final optimized method uses a 9-atm fill of P35 (35% methane, 65% argon), and a tritium analysis window from 1.5 to 10.3 keV, which stops short of the tritium beta decay endpoint energy of 18.6 keV. This method optimizes tritium-counting efficiency while minimizing radiocarbon beta-decay interference.

  8. Recent Developments In Fast Neutron Detection And Multiplicity Counting With Verification With Liquid Scintillator

    SciTech Connect

    Nakae, L; Chapline, G; Glenn, A; Kerr, P; Kim, K; Ouedraogo, S; Prasad, M; Sheets, S; Snyderman, N; Verbeke, J; Wurtz, R

    2011-09-30

    For many years at LLNL, we have been developing time-correlated neutron detection techniques and algorithms for applications such as Arms Control, Threat Detection and Nuclear Material Assay. Many of our techniques have been developed specifically for the relatively low efficiency (a few percent) attainable by detector systems limited to man-portability. Historically, we used thermal neutron detectors (mainly {sup 3}He), taking advantage of the high thermal neutron interaction cross-sections. More recently, we have been investigating the use of fast neutron detection with liquid scintillators, inorganic crystals, and in the near future, pulse-shape discriminating plastics which respond over 1000 times faster (nanoseconds versus tens of microseconds) than thermal neutron detectors. Fast neutron detection offers considerable advantages, since the inherent nanosecond production time-scales of spontaneous fission and neutron-induced fission are preserved and measured instead of being lost by thermalization required for thermal neutron detectors. We are now applying fast neutron technology to the safeguards regime in the form of fast portable digital electronics as well as faster and less hazardous scintillator formulations. Faster detector response times and sensitivity to neutron momentum show promise for measuring, differentiating, and assaying samples that have modest to very high count rates, as well as mixed fission sources like Cm and Pu. We report on measured results with our existing liquid scintillator array, and progress on the design of a nuclear material assay system that incorporates fast neutron detection, including the surprising result that fast liquid scintillator detectors become competitive and even surpass the precision of {sup 3}He-based counters measuring correlated pairs in modest (kg) samples of plutonium.

  9. Sensitive and transportable gadolinium-core plastic scintillator sphere for neutron detection and counting

    NASA Astrophysics Data System (ADS)

    Dumazert, Jonathan; Coulon, Romain; Carrel, Frédérick; Corre, Gwenolé; Normand, Stéphane; Méchin, Laurence; Hamel, Matthieu

    2016-08-01

    Neutron detection forms a critical branch of nuclear-related issues, currently driven by the search for competitive alternative technologies to neutron counters based on the helium-3 isotope. The deployment of plastic scintillators shows a high potential for efficient detectors, safer and more reliable than liquids, more easily scalable and cost-effective than inorganic. In the meantime, natural gadolinium, through its 155 and mostly 157 isotopes, presents an exceptionally high interaction probability with thermal neutrons. This paper introduces a dual system including a metal gadolinium core inserted at the center of a high-scale plastic scintillator sphere. Incident fast neutrons are thermalized by the scintillator shell and then may be captured with a significant probability by gadolinium 155 and 157 nuclei in the core. The deposition of a sufficient fraction of the capture high-energy prompt gamma signature inside the scintillator shell will then allow discrimination from background radiations by energy threshold, and therefore neutron detection. The scaling of the system with the Monte Carlo MCNPX2.7 code was carried out according to a tradeoff between the moderation of incident fast neutrons and the probability of slow neutron capture by a moderate-cost metal gadolinium core. Based on the parameters extracted from simulation, a first laboratory prototype for the assessment of the detection method principle has been synthetized. The robustness and sensitivity of the neutron detection principle are then assessed by counting measurement experiments. Experimental results confirm the potential for a stable, highly sensitive, transportable and cost-efficient neutron detector and orientate future investigation toward promising axes.

  10. Recent Developments in Fast Neutron Detection and Multiplicity Counting with Liquid Scintillator

    SciTech Connect

    Nakae, L. F.; Chapline, G. F.; Glenn, A. M.; Kerr, P. L.; Kim, K. S.; Ouedraogo, S. A.; Prasad, M. K.; Sheets, S. A.; Snyderman, N. J.; Verbeke, J. M.; Wurtz, R. E.

    2011-12-13

    For many years, LLNL researchers have been developing time-correlated neutron detection techniques and algorithms for applications such as Arms Control, Threat Detection and Nuclear Material Assay. Many of the techniques have been developed specifically for the relatively low efficiency (a few percent) attainable by detector systems limited to man-portability. Historically, thermal neutron detectors (mainly {sup 3}He) were used, taking advantage of the high thermal neutron interaction cross sections. More recently, we have been investigating the use of fast neutron detection with liquid scintillators, inorganic crystals, and in the near future, pulse-shape discriminating plastics that respond over 1000 times faster (ns versus tens of {mu}s) than thermal neutron detectors. Fast neutron detection offers considerable advantages since the inherent ns production timescales of spontaneous fission and neutron-induced fission are preserved and measured instead of being lost by thermalization required for thermal neutron detectors. We are now applying fast neutron technology to the safeguards regime in the form of fast portable digital electronics as well as faster and less hazardous scintillator formulations. Faster detector response times and sensitivity to neutron momentum show promise for measuring, differentiating, and assaying samples that have modest to very high count rates, as well as mixed fission sources like Cm and Pu. We report on measured results with our existing liquid scintillator array and progress on the design of a nuclear material assay system that incorporates fast neutron detection, including the surprising result that fast liquid scintillator detectors become competitive and even surpass the precision of {sup 3}He-based counters measuring correlated pairs in modest (kg) samples of plutonium.

  11. Purification of large liquid scintillators for Borexino

    SciTech Connect

    Benziger, J.B.; Calaprice, F.P.; Vogelaar, R.B.

    1993-10-01

    Distillation extraction and crystallization have been used on scintillator mixtures for solar neutrino physics to remove cosmo- genically produced impurities ({sup 7}Be) and naturally occurring impurities ({sup 238}U, {sup 232}Th, and {sup 40}K), and to improve the optical transmission. Distillation was effective at removing {sup 7}Be and other impurities from aromatic solvents (p-xylene and pseudocumene) used as scintillator solvents. Distillation also provided the greatest improvement in the optical clarity of the solvents. Commercially available fluors (PPO and PMP) have high levels of potassium, far in excess of those tolerable for Borexino. Extraction techniques have been found to be effective at removing radioactive impurities, particularly potassium, from the fluors. An overall strategy for on-line purification of the scintillator for Borexino will be presented.

  12. Current trends in scintillator detectors and materials

    SciTech Connect

    Moses, William W.

    2001-10-23

    The last decade has seen a renaissance in inorganic scintillator development for gamma ray detection. Lead tungstate (PbWO4) has been developed for high energy physics experiments, and possesses exceptionally high density and radiation hardness, albeit with low luminous efficiency. Lutetium orthosilicate or LSO (Lu2SiO5:Ce) possesses a unique combination of high luminous efficiency, high density, and reasonably short decay time, and is now incorporated in commercial positron emission tomography (PET) cameras. There have been advances in understanding the fundamental mechanisms that limit energy resolution, and several recently discovered materials (such as LaBr3:Ce) possess energy resolution that approaches that of direct solid state detectors. Finally, there are indications that a neglected class of scintillator materials that exhibit near band-edge fluorescence could provide scintillators with sub-nanosecond decay times and high luminescent efficiency.

  13. On the scintillation efficiency of carborane-loaded liquid scintillators for thermal neutron detection

    NASA Astrophysics Data System (ADS)

    Chang, Zheng; Okoye, Nkemakonam C.; Urffer, Matthew J.; Green, Alexander D.; Childs, Kyle E.; Miller, Laurence F.

    2015-01-01

    The scintillation efficiency in response to thermal neutrons was studied by loading different concentrations of carborane (0-8.5 wt%) and naphthalene (0 and 100 g/L) in five liquid organic scintillators. The sample was characterized in Pb and Cd shields under the irradiation of the thermal neutrons from a 252Cf source. A method was developed to extract the net neutron response from the pulse-height spectra. It was found that the order of scintillation efficiencies for both γ-rays and thermal neutrons is as follows: diisopropylnaphthalene>toluene (concentrated solutes)>toluene~pseudocumene~m-xylene. The quench constants, obtained by fitting the Stern-Volmer model to the plots of light output versus carborane concentration, are in the range of 0.35-1.4 M-1 for all the scintillators. The Birks factors, estimated using the specific energy loss profiles of the incident particles, are in the range of 9.3-14 mg cm-2 MeV-1 for all the samples. The light outputs are in the range of 63-86 keV electron equivalents (keVee) in response to thermal neutrons. Loading naphthalene generally promotes the scintillation efficiency of the scintillator with a benzene derivative solvent. Among all the scintillators tested, the diisopropylnaphthalene-based scintillator shows the highest scintillation efficiency, lowest Birks factor, and smallest quench constants. These properties are primarily attributed to the double fused benzene-ring structure of the solvent, which is more efficient to populate to the excited singlet state under ionizing radiation and to transfer the excitation energy to the fluorescent solutes.

  14. Lossy Counter Machines Decidability Cheat Sheet

    NASA Astrophysics Data System (ADS)

    Schnoebelen, Philippe

    Lossy counter machines (LCM's) are a variant of Minsky counter machines based on weak (or unreliable) counters in the sense that they can decrease nondeterministically and without notification. This model, introduced by R. Mayr [TCS 297:337-354 (2003)], is not yet very well known, even though it has already proven useful for establishing hardness results.

  15. Science Experimenter: Experimenting with a Geiger Counter.

    ERIC Educational Resources Information Center

    Mims, Forrest M., III

    1992-01-01

    Describes the use of geiger counters for scientific investigations and experiments. Presents information about background radiation, its sources and detection. Describes how geiger counters work and other methods of radiation detection. Provides purchasing information for geiger counters, related computer software and equipment. (MCO)

  16. Lu1-xI3:Cex--A Scintillator for gamma ray spectroscopy and time-of-flight PET

    DOEpatents

    Shah, Kanai S.

    2009-03-17

    The present invention concerns very fast scintillator materials comprising lutetium iodide doped with Cerium Lu.sub.1-xI.sub.3:Ce.sub.x; LuI.sub.3:Ce). The LuI.sub.3 scintillator material has surprisingly good characteristics including high light output, high gamma ray stopping efficiency, fast response, low cost, good proportionality, and minimal afterglow that the material is useful for gamma ray spectroscopy, medical imaging, nuclear and high energy physics research, diffraction, non-destructive testing, nuclear treaty verification and safeguards, and geological exploration. The timing resolution of the scintillators of the present invention provide compositions capable of resolving the position of an annihilation event within a portion of a human body cross-section.

  17. Statistics of time averaged atmospheric scintillation

    SciTech Connect

    Stroud, P.

    1994-02-01

    A formulation has been constructed to recover the statistics of the moving average of the scintillation Strehl from a discrete set of measurements. A program of airborne atmospheric propagation measurements was analyzed to find the correlation function of the relative intensity over displaced propagation paths. The variance in continuous moving averages of the relative intensity was then found in terms of the correlation functions. An empirical formulation of the variance of the continuous moving average of the scintillation Strehl has been constructed. The resulting characterization of the variance of the finite time averaged Strehl ratios is being used to assess the performance of an airborne laser system.

  18. Plastic scintillator centrality detector for BRAHMS

    NASA Astrophysics Data System (ADS)

    Lee, Y. K.; Debbe, R.; Lee, J. H.; Ito, Hironori; Sanders, S. J.

    2004-01-01

    An array of 40 tiles of thin plastic scintillators is used to construct the outer layer of the charged particle multiplicity detector for the BRAHMS experiment at the Relativistic Heavy Ion Collider (RHIC). Each tile is a square with 12 cm long sides and 5 mm thickness. The light from each of the scintillators is collected by wavelength shifting fibers embedded on the periphery. The light collection is uniform within 5% over the tile with the edge effect limited to 4 mm along the edge. The response is found to be linear in the high-multiplicity environment at RHIC with Au+Au beams at s NN of 200 GeV.

  19. Quality study of the purified liquid scintillator

    NASA Astrophysics Data System (ADS)

    Konno, Y.; Nakajima, K.; Kibe, Y.

    2008-07-01

    We have been distilling the KamLAND liquid scintillator (LS) for the low energy solar neutrino observation. The distillation removes radioactive impurities from LS efficiently. We developed two types of high sensitivity radon detectors to monitor 222Rn contamination which causes a primary background source 210Pb. Their required sensitivity is several mBq/m3. The features and the measurement results of these detectors are presented. We also report the study of liquid scintillator properties after the distillation: attenuation length, light output and PPO density.

  20. Effects of radiation on scintillating fiber performance

    SciTech Connect

    Bauer, M.L.; Cohn, H.; Efremenko, Yu.; Gordeev, A.; Kamyshkov, Yu.; Onopienko, D.; Savin, S.; Shmakov, K.; Tarkovsky, E.; Young, K.G.; Carey, R.; Rothman, M.; Sulak, L.; Worstell, W.; Parr, H.

    1992-12-31

    Continued rapid improvements in formulations for scintillating fibers require the ability to parameterize and predict effects of radiation on detector performance. Experimental techniques necessary to obtain needed information and calculational procedures used in performing predications for hadron scintillating fiber calorimetry in the Superconducting Supercollider environment are described. The experimental techniques involve control of the testing environment, consideration of dose rate effects, and other factors. These calculations involve the behavior of particle showers in the detector, expected levels of radiation, and parameterization of the radiation effects. A summary of significant work is also presented.

  1. Effects of radiation on scintillating fiber performance

    SciTech Connect

    Young, K.G.; Bauer, M.L.; Cohn, H.; Efremenko, Yu.; Gordeev, A.; Kamyshkov, Yu.; Onopienko, D.; Savin, S.; Shmakov, K.; Tarkovsky, E. ); Carey, R.; Rothman, M.; Sulak, L.; Worstell, W. ); Paar, H. )

    1993-08-01

    Continued rapid improvements in formulations for scintillating fibers require the ability to parameterize and predict effects of radiation on detector performance. Experimental techniques necessary to obtain desired information and calculational procedures used in performing predictions for hadron scintillating fiber calorimetry in the Superconducting Supercollider environment are described. The experimental techniques involve control of the testing environment, consideration of dose rate effects, and other factors. The calculations involve the behavior of particle showers in the detector, expected levels of radiation, and parameterization of the radiation effects. A summary of significant work is also presented.

  2. Near-infrared scintillation of liquid argon

    SciTech Connect

    Alexander, T.; Escobar, C. O.; Lippincott, W. H.; Rubinov, P.

    2016-03-03

    Since the 1970s it has been known that noble gases scintillate in the near infrared (NIR) region of the spectrum (0.7 $\\mu$m < $\\lambda$; < 1.5$\\mu$m). More controversial has been the question of the NIR light yield for condensed noble gases. We first present the motivation for using the NIR scintillation in liquid argon detectors, then briefly review early as well as more recent efforts and finally show encouraging preliminary results of a test performed at Fermilab.

  3. The homestake surface-underground scintillations: Description

    NASA Technical Reports Server (NTRS)

    Cherry, M. L.; Corbato, S.; Daily, T.; Fenyves, E. J.; Kieda, D.; Lande, K.; Lee, C. K.

    1985-01-01

    Two new detectors are currently under construction at the Homestake Gold Mine a 140-ton Large Area Scintillation Detector (LASD) with an upper surface area of 130 square meters, a geometry factor (for an isotropic flux) of 1200 square meters, sr, and a depth of 4200 m.w.e.; and a surface air shower array consisting of 100 scintillator elements, each 3 square meters, spanning an area of approximately square kilometers. Underground, half of the LASD is currently running and collecting muon data; on the surface, the first section of the air shower array will begin operation in the spring of 1985. The detectors and their capabilities are described.

  4. Plastic scintillators modifications for a selective radiation detection

    SciTech Connect

    Hamel, Matthieu; Bertrand, Guillaume H.V.; Carrel, Frederick; Coulon, Romain; Dumazert, Jonathan; Montbarbon, Eva; Sguerra, Fabien

    2015-07-01

    Recent developments of plastic scintillators are reviewed, from January 2000 to June 2015. All examples are distributed into the main application, i.e. how the plastic scintillator was modified to enhance the detection towards a given radiation particle. The main characteristics of these newly created scintillators and their detection properties are given. (authors)

  5. New liquid scintillators for fiber-optic applications

    SciTech Connect

    Lutz, S.S.; Franks, L.A.; Flournoy, J.M.; Lyons, P.B.

    1981-01-01

    New long-wavelength-emitting, high-speed, liquid scintillators have been developed and tailored specifically for plasma diagnostic experiments employing fiber optics. These scintillators offer significant advantages over commercially available plastic scintillators in terms of sensitivity and bandwidth. FWHM response times as fast as 350 ps have been measured. Emission spectra, time response data, and relative sensitivity information are presented.

  6. Upconverting nanoparticles for optimizing scintillator based detection systems

    DOEpatents

    Kross, Brian; McKisson, John E; McKisson, John; Weisenberger, Andrew; Xi, Wenze; Zom, Carl

    2013-09-17

    An upconverting device for a scintillation detection system is provided. The detection system comprises a scintillator material, a sensor, a light transmission path between the scintillator material and the sensor, and a plurality of upconverting nanoparticles particles positioned in the light transmission path.

  7. Cognitive and Metacognitive Aspects of Proportional Reasoning

    ERIC Educational Resources Information Center

    Modestou, Modestina; Gagatsis, Athanasios

    2010-01-01

    In this study we attempt to propose a new model of proportional reasoning based both on bibliographical and research data. This is impelled with the help of three written tests involving analogical, proportional, and non-proportional situations that were administered to pupils from grade 7 to 9. The results suggest the existence of a…

  8. Body proportions in children with Kabuki syndrome.

    PubMed

    Penders, Bas; Schott, Nina; Gerver, Willem-Jan M; Stumpel, Constance T R M

    2016-03-01

    Facial characteristics, short stature, and skeletal anomalies have been described for the clinical diagnosis of Kabuki Syndrome (KS) in children. However, no studies have investigated body proportions in KS. Knowledge of body proportions in KS may contribute to better insight into the growth pattern and characterization of this genetic disorder. Therefore we compared body proportions of children with KS to normally proportioned controls to investigate if atypical body proportions are part of this genetic disorder. This study was designed and conducted within the setting of the Maastricht University Medical Centre (MUMC+), the official Dutch expert center for Kabuki syndrome. We conducted a cross-sectional study in 32 children (11 children with KS and 21 controls). Body proportions were determined by means of photogrammetric anthropometry, measurements based on digital photography. Body proportions, quantified as body ratios, differ significantly in children with KS from normally proportioned children. Children with KS have larger heads and longer arms proportional to their trunks and have been found to have longer upper arms proportional to their tibia length and feet. Based on deviations in body proportions it was shown possible to discern children with KS from normally proportioned controls.

  9. Assessment of scintillation proxy maps for a scintillation study during geomagnetically quiet and disturbed conditions over Uganda

    NASA Astrophysics Data System (ADS)

    Amabayo, Emirant B.; Jurua, Edward; Cilliers, Pierre J.

    2017-02-01

    The objective of this paper is demonstrate the validity and usefulness of scintillation proxies derived from IGS data, through its comparison with data from dedicated scintillation monitors and its application to GNSS scintillation patterns. The paper presents scintillation patterns developed by using data from the dedicated scintillation monitors of the scintillation network decision aid (SCINDA) network, and proxy maps derived from IGS GPS data for 2011 and 2012 over low latitude stations in Uganda. The amplitude and phase scintillation indicies (S4 and σΦ) were obtained from the Novatel GSV4004B ionospheric scintillation and total electron content (TEC) monitor managed by SCINDA at Makerere (0.340N, 32.570E). The corresponding IGS GPS proxy data were obtained from the receivers at Entebbe (0.040N, 32.440E) and Mbarara (0.600S, 30.740E). The derived amplitude (S4p) and phase (sDPR) scintillation proxy maps were compared with maps of S4 and σΦ during geomagnetic storms (moderate and strong) and geomagnetically quiet conditions. The scintillation patterns using S4 and σΦ and their respective proxies revealed similar diurnal and seasonal patterns of strong scintillation occurrence. The peaks of scintillation occurrence with mean values in the range 0.3 < (S4p , sDPR) ≤ 0.6 were observed during nighttime (17:00-22:00 UT) and in the months of March-April and September-October. The results also indicate that high level scintillations occur during geomagnetically disturbed (moderate and strong) and quiet conditions over the Ugandan region. The results show that SCINDA and IGS based scintillation patterns reveal the same nighttime and seasonal occurrence of irregularities over Uganda irrespective of the geomagnetic conditions. Therefore, the amplitude and phase scintillation proxies presented here can be used to fill gaps in low-latitude data where there are no data available from dedicated scintillation receivers, irrespective of the geomagnetic conditions.

  10. Development of new Polysiloxane Based Liquid Scintillators

    SciTech Connect

    Dalla Palma, M.; Quaranta, A.; Gramegna, F.; Marchi, T.; Cinausero, M.; Carturan, S.; Collazuol, G.; Checchia, C.; Degerlier, M.

    2015-07-01

    In the last decade, attention toward neutron detection has been growing in the scientific community, driven by new requirements in different fields of application ranging from homeland security to medical and material analysis, from research physics, to nuclear energy production. So far neutron detection, with particular attention to fast neutrons, has been mainly based on organic liquid scintillators, owing to their good efficiency and pulse shape discrimination (PSD) capability. Most of these liquids have however some main drawbacks given by toxicity, flammability, volatility and sensitivity to dissolved oxygen that limits the duration and the quality of their performances with worse handiness and increased costs. Phenyl-substituted polysiloxanes could address most of these issues, being characterized by low toxicity, low volatility and low flammability. Their optical properties can be tailored by changing the phenyl distribution and concentration thus allowing to increase the solubility of organic dyes, to modify the fluorescence spectra and to vary the refractive index of the medium. Furthermore, polysiloxanes have been recently exploited for the production of plastic scintillators with very good chemical and thermal stability and very good radiation hardness and the development of polysiloxane liquid scintillators could allow to combine these interesting properties with the supremacy of liquid scintillators as regarding PSD over plastics. For these reasons, the properties of several phenyl-substituted polysiloxane with different phenyl amounts and different viscosities have been investigated, with particular attention to the scintillation response and the pulse shape discrimination capability, and the results of the investigation are reported in this work. More in details, the scintillation light yield towards gamma rays ({sup 60}Co and {sup 137}Cs) of several polysiloxane liquids has been analyzed and compared with the light yield of a commercial non

  11. Robust GPS carrier tracking under ionospheric scintillation

    NASA Astrophysics Data System (ADS)

    Susi, M.; Andreotti, M.; Aquino, M. H.; Dodson, A.

    2013-12-01

    Small scale irregularities present in the ionosphere can induce fast and unpredictable fluctuations of Radio Frequency (RF) signal phase and amplitude. This phenomenon, known as scintillation, can degrade the performance of a GPS receiver leading to cycle slips, increasing the tracking error and also producing a complete loss of lock. In the most severe scenarios, if the tracking of multiple satellites links is prevented, outages in the GPS service can also occur. In order to render a GPS receiver more robust under scintillation, particular attention should be dedicated to the design of the carrier tracking stage, that is the receiver's part most sensitive to these types of phenomenon. This paper exploits the reconfigurability and flexibility of a GPS software receiver to develop a tracking algorithm that is more robust under ionospheric scintillation. For this purpose, first of all, the scintillation level is monitored in real time. Indeed the carrier phase and the post correlation terms obtained by the PLL (Phase Locked Loop) are used to estimate phi60 and S4 [1], the scintillation indices traditionally used to quantify the level of phase and amplitude scintillations, as well as p and T, the spectral parameters of the fluctuations PSD. The effectiveness of the scintillation parameter computation is confirmed by comparing the values obtained by the software receiver and the ones provided by a commercial scintillation monitoring, i.e. the Septentrio PolarxS receiver [2]. Then the above scintillation parameters and the signal carrier to noise density are exploited to tune the carrier tracking algorithm. In case of very weak signals the FLL (Frequency Locked Loop) scheme is selected in order to maintain the signal lock. Otherwise an adaptive bandwidth Phase Locked Loop (PLL) scheme is adopted. The optimum bandwidth for the specific scintillation scenario is evaluated in real time by exploiting the Conker formula [1] for the tracking jitter estimation. The performance

  12. The SNO+ Scintillator Purification Plant and Projected Sensitivity to Solar Neutrinos in the Pure Scintillator Phase

    NASA Astrophysics Data System (ADS)

    Pershing, Teal; SNO+ Collaboration

    2016-03-01

    The SNO+ detector is a neutrino and neutrinoless double-beta decay experiment utilizing the renovated SNO detector. In the second phase of operation, the SNO+ detector will contain 780 tons of organic liquid scintillator composed of 2 g/L 2,5-diphenyloxazole (PPO) in linear alkylbenzene (LAB). In this phase, SNO+ will strive to detect solar neutrinos in the sub-MeV range, including CNO production neutrinos and pp production neutrinos. To achieve the necessary detector sensitivity, a four-part scintillator purification plant has been constructed in SNOLAB for the removal of ionic and radioactive impurities. We present an overview of the SNO+ scintillator purification plant stages, including distillation, water extraction, gas stripping, and metal scavenger columns. We also give the projected SNO+ sensitivities to various solar-produced neutrinos based on the scintillator plant's projected purification efficiency.

  13. Characterizing Scintillation and Cherenkov Light in Water-Based Liquid Scintillators

    NASA Astrophysics Data System (ADS)

    Land, Benjamin; Caravaca, Javier; Descamps, Freija; Orebi Gann, Gabriel

    2016-09-01

    The recent development of Water-based Liquid Scintillator (WbLS) has made it possible to produce scintillating materials with highly tunable light yields and excellent optical clarity. This allows for a straightforward combination of the directional properties of Cherenkov light with the greater energy resolution afforded by the typically brighter scintillation light which lends itself well to a broad program of neutrino physics. Here we explore the light yields and time profiles of WbLS materials in development for Theia (formerly ASDC) as measured in CheSS: our bench-top Cherenkov and scintillation separation R&D project at Berkeley Lab. This work was supported by the Laboratory Directed Research and Development Program of Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC02-05CH11231.

  14. Development of scintillator plates with high energy resolution for alpha particles made of GPS scintillator grains

    NASA Astrophysics Data System (ADS)

    Shimaoka, Takehiro; Kaneko, Junichi H.; Izaki, Kenji; Tsubota, Youichi; Higuchi, Mikio; Nishiyama, Shusuke

    2014-01-01

    A scintillator plate with high energy resolution was developed to produce an alpha particle monitor used in nuclear fuel reprocessing plants and mixed plutonium-uranium oxide (MOX) fuel plants. Grains of a Gd2Si2O7 (GPS) scintillator of several 10 to 550 μm were fixed on a glass substrate and were then mechanically polished. By increasing the size of scintillator grains and removing fine powders, the collected light yield and energy resolution for alpha particles were drastically improved. Energy resolution of 9.3% was achieved using average grain size of 91 μm. Furthermore, the ratios between counts in a peak and total counts were improved by more than 60% by the further increase of grain size and adoption of mechanically polished surfaces on both sides. Beta and gamma ray influences were suppressed sufficiently by the thin 100 μm scintillator plates.

  15. Equatorial scintillation calculations based on coherent scatter radar and C/NOFS data

    NASA Astrophysics Data System (ADS)

    Costa, Emanoel; de Paula, Eurico R.; Rezende, L. F. C.; Groves, Keith M.; Roddy, Patrick A.; Dao, Eugene V.; Kelley, Michael C.

    2011-04-01

    During its transit through a region of equatorial ionospheric irregularities, sensors on board the Communication/Navigation Outage Forecasting System (C/NOFS) satellite provide a one-dimensional description of the medium, which can be extended to two dimensions if the structures are assumed to be elongated in the direction of the magnetic field lines. The C/NOFS scintillation calculation approach assumes that the medium is equivalent to a diffracting screen with random phase fluctuations that are proportional to the irregularities in the total electron content, specified through the product of the directly measured electron density by an estimated extent of the irregularity layer along the raypaths. Within the international collaborative effort anticipated by the C/NOFS Science Definition Team, the present work takes the vertical structure of the irregularities into more detailed consideration, which could lead to improved predictions of scintillation. Initially, it describes a flexible model for the power spectral density of the equatorial ionospheric irregularities, estimates its shape parameters from C/NOFS in situ data and uses the signal-to-noise ratio S/N measurements by the São Luís coherent scatter radar to estimate the mean square electron density fluctuation <ΔN2> within the corresponding sampled volume. Next, it presents an algorithm for the wave propagation through a three-dimensional irregularity layer which considers the variations of <ΔN2> along the propagation paths according to observations by the radar. Data corresponding to several range-time-intensity maps from the radar is used to predict time variations of the scintillation index S4 at the L1 Global Positioning System (GPS) frequency (1575.42 MHz). The results from the scintillation calculations are compared with corresponding measurements by the colocated São Luís GPS scintillation monitor for an assessment of the prediction capability of the present formulation.

  16. Liquid Scintillator Production for the NOvA Experiment

    DOE PAGES

    Mufson, S.; Baugh, B.; Bower, C.; ...

    2015-04-15

    The NOvA collaboration blended and delivered 8.8 kt (2.72M gal) of liquid scintillator as the active detector medium to its near and far detectors. The composition of this scintillator was specifically developed to satisfy NOvA's performance requirements. A rigorous set of quality control procedures was put in place to verify that the incoming components and the blended scintillator met these requirements. The scintillator was blended commercially in Hammond, IN. The scintillator was shipped to the NOvA detectors using dedicated stainless steel tanker trailers cleaned to food grade.

  17. Liquid scintillator production for the NOvA experiment

    NASA Astrophysics Data System (ADS)

    Mufson, S.; Baugh, B.; Bower, C.; Coan, T. E.; Cooper, J.; Corwin, L.; Karty, J. A.; Mason, P.; Messier, M. D.; Pla-Dalmau, A.; Proudfoot, M.

    2015-11-01

    The NOvA collaboration blended and delivered 8.8 kt (2.72M gal) of liquid scintillator as the active detector medium to its near and far detectors. The composition of this scintillator was specifically developed to satisfy NOvA's performance requirements. A rigorous set of quality control procedures was put in place to verify that the incoming components and the blended scintillator met these requirements. The scintillator was blended commercially in Hammond, IN. The scintillator was shipped to the NOvA detectors using dedicated stainless steel tanker trailers cleaned to food grade.

  18. Light propagation and fluorescence quantum yields in liquid scintillators

    NASA Astrophysics Data System (ADS)

    Buck, C.; Gramlich, B.; Wagner, S.

    2015-09-01

    For the simulation of the scintillation and Cherenkov light propagation in large liquid scintillator detectors a detailed knowledge about the absorption and emission spectra of the scintillator molecules is mandatory. Furthermore reemission probabilities and quantum yields of the scintillator components influence the light propagation inside the liquid. Absorption and emission properties are presented for liquid scintillators using 2,5-Diphenyloxazole (PPO) and 4-bis-(2-Methylstyryl)benzene (bis-MSB) as primary and secondary wavelength shifter. New measurements of the quantum yields for various aromatic molecules are shown.

  19. Bridgman bulk growth and scintillation measurements of SrI2:Eu2+

    NASA Astrophysics Data System (ADS)

    Hawrami, R.; Glodo, J.; Shah, K. S.; Cherepy, N.; Payne, S.; Burger, A.; Boatner, L.

    2013-09-01

    Large diameter Bridgman growth of europium activated strontium iodide SrI2:Eu2+ produces crystals with light yield of up to 115,000 ph/MeV with an excellent light yield proportionality. SrI2:Eu2+ exhibits an outstanding energy resolution of better than 3% FWHM at 662 keV. Its emission is centered at 435 nm. The scintillation decays with a 1 μs time constant for small samples and up to 5 μs to larger crystals. This paper presents successful progress made in the vertical Bridgman crystal growth of SrI2:Eu2+ and its scintillator properties. Large diameter, crack-free and transparent SrI2:Eu2+single crystals with diameters of 1 in., 1.3 in., 1.5 in. and 2 in. were all successfully grown.

  20. High-throughput combinatorial database of electronic band structures for inorganic scintillator materials.

    PubMed

    Setyawan, Wahyu; Gaume, Romain M; Lam, Stephanie; Feigelson, Robert S; Curtarolo, Stefano

    2011-07-11

    For the purpose of creating a database of electronic structures of all the known inorganic compounds, we have developed a computational framework based on high-throughput ab initio calculations (AFLOW) and an online repository (www.aflowlib.org). In this article, we report the first step of this task: the calculation of band structures for 7439 compounds intended for the research of scintillator materials for γ-ray radiation detection. Data-mining is performed to select the candidates from 193,456 compounds compiled in the Inorganic Crystal Structure Database. Light yield and scintillation nonproportionality are predicted based on semiempirical band gaps and effective masses. We present a list of materials, potentially bright and proportional, and focus on those exhibiting small effective masses and effective mass ratios.

  1. High resolution scintillation detector with semiconductor readout

    DOEpatents

    Levin, Craig S.; Hoffman, Edward J.

    2000-01-01

    A novel high resolution scintillation detector array for use in radiation imaging such as high resolution Positron Emission Tomography (PET) which comprises one or more parallelepiped crystals with at least one long surface of each crystal being in intimate contact with a semiconductor photodetector such that photons generated within each crystal by gamma radiation passing therethrough is detected by the photodetector paired therewith.

  2. Fluorescent compounds for plastic scintillation applications

    SciTech Connect

    Pla-Dalmau, A.; Bross, A.D.

    1994-04-01

    Several 2-(2{prime}-hydroxyphenyl)benzothiazole, -benzoxazole, and -benzimidazole derivatives have been prepared. Transmittance, fluorescence, light yield, and decay time characteristics of these compounds have been studied in a polystyrene matrix and evaluated for use in plastic scintillation detectors. Radiation damage studies utilizing a {sup 60}C source have also been performed.

  3. Scintillator Development for the PROSPECT Experiment

    NASA Astrophysics Data System (ADS)

    Yeh, Minfang

    2014-03-01

    Doped scintillator is the target material of choice for antineutrino detection as it utilizes the time-delayed coincidence signature of the positron annihilation and neutron capture resulting from the Inverse Beta Decay (IBD) interaction. Additionally, the multiple gamma rays or heavy ions emitted after neutron capture on either Gd or 6Li respectively provide a distinct signal for the identification of antineutrino events and therefore significantly enhance accidental background reduction. The choice of scintillator and dopant depends on the detector requirements and scintillator performance criteria. Both Gd and 6Li doped scintillators have been used in past reactor antineutrino experiments such as Double Chooz, Daya Bay, RENO, and Bugey3 and are currently under investigation by the PROSPECT collaboration. Their properties in terms of light yield, optical transparency, chemical stability and background rejection efficiency using Pulse Shape Discrimination (PSD) will be reported. Research sponsored by the U.S. Department of Energy, Office of Nuclear Physics and Office of High Energy Physics, under contract with Brookhaven National Laboratory-Brookhaven Science Associates.

  4. Optimization of Shielded Scintillator for Neutron Detection

    NASA Astrophysics Data System (ADS)

    Belancourt, Patrick; Morrison, John; Akli, Kramer; Freeman, Richard; High Energy Density Physics Team

    2011-10-01

    The High Energy Density Physics group is interested in the basic science of creating a neutron and gamma ray source. The neutrons and gamma rays are produced by accelerating ions via a laser into a target and creating fusion neutrons and gamma rays. A scintillator and photomultiplier tube will be used to detect these neutrons. Neutrons and photons produce ionizing radiation in the scintillator which then activates metastable states. These metastable states have both short and long decay rates. The initial photon count is orders of magnitude higher than the neutron count and poses problems for accurately detecting the neutrons due to the long decay state that is activated by the photons. The effects of adding lead shielding on the temporal response and signal level of the neutron detector will be studied in an effort to minimize the photon count without significant reduction to the temporal resolution of the detector. MCNP5 will be used to find the temporal response and energy deposition into the scintillator by adding lead shielding. Results from the simulations will be shown. Optimization of our scintillator neutron detection system is needed to resolve the neutron energies and neutron count of a novel neutron and gamma ray source.

  5. Equitorial Scintillations: Advances Since ISEA-6.

    DTIC Science & Technology

    1985-01-01

    thermospheric neutral wind have been postulated to describe the observe l longitudinal variation._--.-, A distinct class of equatorial irregularities...Unclassified SECURITY CLASSIFICATION OF THIS PAGE associated with frequency spread on ionograms . Scintillations caused by such irregularities exist only...another based on the influence of a transequatorial thermospheric neutral wind have been postu- lated to describe the observed longitudinal variation. A

  6. Outward atmospheric scintillation effects and inward atmospheric scintillation effects comparisons for direct detection ladar applications

    NASA Astrophysics Data System (ADS)

    Youmans, Douglas G.

    2014-06-01

    Atmospheric turbulence produces intensity modulation or "scintillation" effects on both on the outward laser-mode path and on the return backscattered radiation path. These both degrade laser radar (ladar) target acquisition, ranging, imaging, and feature estimation. However, the finite sized objects create scintillation averaging on the outgoing path and the finite sized telescope apertures produce scintillation averaging on the return path. We expand on previous papers going to moderate to strong turbulence cases by starting from a 20kft altitude platform and propagating at 0° elevation (with respect to the local vertical) for 100km range to a 1 m diameter diffuse sphere. The outward scintillation and inward scintillation effects, as measured at the focal plane detector array of the receiving aperture, will be compared. To eliminate hard-body surface speckle effects in order to study scintillation, Goodman's M-parameter is set to 106 in the analytical equations and the non-coherent imaging algorithm is employed in Monte Carlo realizations. The analytical equations of the signal-to-noise ratio (SNRp), or mean squared signal over a variance, for a given focal plane array pixel window of interest will be summarized and compared to Monte Carlo realizations of a 1m diffuse sphere.

  7. Systematic study of particle quenching in organic scintillators

    NASA Astrophysics Data System (ADS)

    Santiago, L. M.; Bagán, H.; Tarancón, A.; Rauret, G.; Garcia, J. F.

    2013-01-01

    Among the different factors that affect measurements by organic scintillators, the majority of attention has been focused on those related to the scintillator (i.e., ionization, chemical, color and optical quenching), and less attention has been paid to the loss of energy before the particle (i.e., alpha or beta) arrives at the scintillator (i.e., particle quenching). This study evaluates the effect of particle quenching in different scintillation methods (i.e., using two plastic scintillation microspheres (PSm1 and PSm2), liquid scintillator and gel scintillator) by measuring solutions that contain increasing concentrations of NaCl, BaCl2 and glycerin. The results show the importance of particle quenching in PSm measurements because detection efficiency decreases with increasing concentrations of the quenching component, although the spectrum position and external standard parameter remain constant. The results have shown evidence of particle quenching, although at a lower magnitude, in the liquid scintillation or gel scintillation measurements. Moreover, the use of two PSm with different diameters and salty compound that alters the equilibrium of the liquid and gel emulsions also exemplified the importance of the transmission of optical photons through different scintillation media (i.e., optical quenching). Improvement and deterioration of the optical conditions on the scintillation media is manifested as a movement of the spectrum to higher and lower energies, respectively. The results obtained with PSm were confirmed by Monte Carlo simulation.

  8. Non-Carbon Dyes For Platic Scintillators- Report

    SciTech Connect

    Teprovich, J.; Colon-Mercado, H.; Gaillard, J.; Sexton, L.; Washington, A.; Ward, P.; Velten, J.

    2015-10-19

    Scintillation based detectors are desirable for many radiation detection applications (portal and border monitoring, safeguards verification, contamination detection and monitoring). The development of next generation scintillators will require improved detection sensitivity for weak gamma ray sources, and fast and thermal neutron quantification. Radiation detection of gamma and neutron sources can be accomplished with organic scintillators, however, the single crystals are difficult to grow for large area detectors and subject to cracking. Alternatives to single crystal organic scintillators are plastic scintillators (PS) which offer the ability to be shaped and scaled up to produce large sized detectors. PS is also more robust than the typical organic scintillator and are ideally suited for deployment in harsh real-world environments. PS contain a mixture of dyes to down-convert incident radiation into visible light that can be detected by a PMT. This project will evaluate the potential use of nano-carbon dyes in plastic scintillators.

  9. Time correlated measurements using plastic scintillators with neutron-photon pulse shape discrimination

    NASA Astrophysics Data System (ADS)

    Richardson, Norman E., IV

    nuclear and radiological material. Moreover, the production of 3He isotope as a byproduct of security programs was drastically decreased. This isotope shortage coupled with the disadvantages of relying on a detector that requires neutron moderation before the detection of fission neutrons, poses a significant challenge in supporting the existing detection systems and the development of future technologies. To address this problem, a reliable and accurate alternative technology to detect neutrons emitted in fissions must be developed. One such alternative technology that shows promise in this application is the use of scintillators based on solid state materials (plastics) which are sensitive to fast neutrons. However, plastic scintillators are also sensitive to photons. Hence, it is necessary to separate the neutron signals from the photon signals, using the pulse shape discrimination (PSD) analysis. The PSD is based on the comparison of the pulse shapes of digitized signal waveforms. This approach allows for the measurement of fast neutrons without the necessity of their moderation. Because the fission spectrum neutrons are mainly fast, methods employing fast neutron detection are applicable for the assay of fissile materials. In addition, the average time of scintillation of the plastic medium is much shorter than those of the gaseous counters, thus allowing scintillation detectors to be used in high count rate environments. Furthermore, the temporal information of the fast neutron detection using multiple sensors enables the time correlation analysis of the fission neutron multiplicity. The study of time correlation measurements of fast neutrons using the array of plastic scintillators is the basis of this work. The array of four plastic scintillator detectors equipped with the digital data acquisition and analysis system was developed. The digital PSD analysis of detector signals "on-the-fly" was implemented for the array. The time coincidence measurement technique

  10. Search for improved-performance scintillator candidates among the electronic structures of mixed halides

    NASA Astrophysics Data System (ADS)

    Li, Qi; Williams, Richard T.; Burger, Arnold; Adhikari, Rajendra; Biswas, Koushik

    2014-09-01

    The application of advanced theory and modeling techniques has become an essential component to understand material properties and hasten the design and discovery of new ones. This is true for diverse applications. Therefore, current efforts aimed towards finding new scintillator materials are also aligned with this general predictive approach. The need for large scale deployment of efficient radiation detectors requires discovery and development of high-performance, yet low-cost, scintillators. While Tl-doped NaI and CsI are still some of the widely used scintillators, there are promising new developments, for example, Eu-doped SrI2 and Ce-doped LaBr3. The newer candidates have excellent light yield and good energy resolution, but challenges persist in the growth of large single crystals. We will discuss a theoretical basis for anticipating improved proportionality as well as light yield in solid solutions of certain systems, particularly alkali iodides, based on considerations of hot-electron group velocity and thermalization. Solid solutions based on NaI and similar alkali halides are attractive to consider in more detail because the end point compositions are inexpensive and easy to grow. If some of this quality can be preserved while reaping improved light yield and possibly improved proportionality of the mixture, the goal of better performance at the low price of NaI:Tl might be attainable by such a route. Within this context, we will discuss a density functional theory (DFT) based study of two prototype systems: mixed anion NaIxBr1-x and mixed cation NaxK1-xI. Results obtained from these two prototype candidates will lead to further targeted theoretical and experimental search and discovery of new scintillator hosts.

  11. Safeguards Technology Factsheet 3He-free Neutron Coincidence Counter

    SciTech Connect

    Henzlova, Daniela; Menlove, Howard Olsen

    2016-04-21

    A full scale thermal neutron coincidence counter (High Level Neutron Counter – Boron: HLNB) based on 3He alternative detection technology was designed and built at LANL and field tested at Plutonium Conversion Development Facility (PCDF) of Japan Atomic Energy Agency (JAEA) during FY15. HLNB is based on boron-lined proportional plates that replace the traditional 3He proportional tubes and was designed as a direct alternative to 3He-based High Level Neutron Coincidence Counter (HLNC-II). During the JAEA field trial the HLNB demonstrated comparable performance to HLNC-II, which represents a key development in the area of 3He alternative technologies and provides a complete demonstration of the technology for nuclear safeguards applications including high mass MOX samples.

  12. Tree-augmented Cox proportional hazards models.

    PubMed

    Su, Xiaogang; Tsai, Chih-Ling

    2005-07-01

    We study a hybrid model that combines Cox proportional hazards regression with tree-structured modeling. The main idea is to use step functions, provided by a tree structure, to 'augment' Cox (1972) proportional hazards models. The proposed model not only provides a natural assessment of the adequacy of the Cox proportional hazards model but also improves its model fitting without loss of interpretability. Both simulations and an empirical example are provided to illustrate the use of the proposed method.

  13. Condensation Particle Counter Instrument Handbook

    SciTech Connect

    Kuang, C.

    2016-02-01

    The Model 3772 CPC is a compact, rugged, and full-featured instrument that detects airborne particles down to 10 nm in diameter, at an aerosol flow rate of 1.0 lpm, over a concentration range from 0 to 1x104 #/cc. This CPC is ideally suited for applications without high concentration measurements, such as basic aerosol research, filter and air-cleaner testing, particle counter calibrations, environmental monitoring, mobile aerosol studies, particle shedding and component testing, and atmospheric and climate studies.

  14. Real-time Scintillation Monitoring in Alaska from a Longitudinal Chain of ASTRA's SM-211 GPS TEC and Scintillation Receivers

    NASA Astrophysics Data System (ADS)

    Crowley, G.; Azeem, S. I.; Reynolds, A.; Santana, J.; Hampton, D. L.

    2013-12-01

    Amplitude and phase scintillation can cause serious difficulties for GPS receivers. Intense scintillation can cause loss of lock. High latitude studies generally show that phase scintillation can be severe, but the amplitude scintillation tends to be small. The reason for this is not yet understood. Furthermore, the actual causes of the ionospheric irregularities that produce high latitude scintillation are not well understood. While the gradient drift instability is thought to be important in the F-region, there may be other structures present in either the E- or F-regions. The role of particle precipitation is also not well understood. Four of ASTRA's CASES GPS receivers were deployed in Alaska to demonstrate our ability to map scintillation in realtime, to provide space weather services to GPS users, and to initiate a detailed investigation of these effects. These dual-frequency GPS receivers measure total electron content (TEC) and scintillation. The scintillation monitors were deployed in a longitudinal chain at sites in Kaktovic, Fort Yukon, Poker Flat, and Gakona. Scintillation statistics show phase scintillations to be largest at Kaktovic and smallest at Gakona. We present GPS phase scintillation and auroral emission results from the Alaska chain to characterize the correspondence between scintillation and auroral features, and to investigate the role of high latitude auroral features in driving the phase scintillations. We will also present data showing how phase scintillation can cause other GPS receivers to lose lock. The data and results are particularly valuable because they illustrate some of the challenges of using GPS systems for positioning and navigation in an auroral region like Alaska. These challenges for snowplough drivers were recently highlighted, along with the CASES SM-211 space weather monitor, in a special video in which ASTRA and three other small businesses were presented with an entrepreneurial award from William Shatner (http://youtu.be/bIVKEQH_YPk).

  15. Nonproportionality of Scintillator Detectors: Theory and Experiment

    SciTech Connect

    Payne, Stephen; Cherepy, Nerine; Hull, Giulia; Valentine, John; Moses, William; Choong, Woon-Seng

    2009-08-17

    On the basis of nonproportionality data obtained for several scintillators, we have developed a theory to describe the carrier dynamics to fit the light yield versus electron energy. The theory of Onsager was adapted to explain how the carriers form excitons or sequentially arrive at the activators to promote the ion to an excited state, and the theory of Birks was employed to allow for exciton-exciton annihilation. We then developed a second theory to deduce the degradation in resolution that results from nonproportionality by evoking Landau fluctuations, which are essentially variations in the deposited energy density that occur as the high energy electron travels along its trajectory. In general there is good agreement with the data, in terms of fitting the nonproportionality curves and reproducing the literature values of nonproportionality's contribution to the scintillator resolution. With the resurgence of interest in developing scintillator detectors that have good energy resolution, an improved understanding of nonproportionality has become a crucial matter since it presents the fundamental limit to the achievable resolution. In order to hasten an improved understanding of scintillator nonproportionality, we have constructed an instrument referred to as SLYNCI (Scintillator Light Yield Nonproportionality Compton Instrument). This is a second-generation instrument to the original device developed by Valentine and coworkers, wherein several new principles of operation have served to increase the data rate by an order of magnitude as discussed in detail in References. In the present article, the focus is on a theory to describe the measured electron response, which is the light yield as a function of the electron energy. To do this, we account for transport of carriers and excitons, in terms of how they transfer their energy to the activators with competition from nonradiative decay pathways. This work builds on the original work of Murray and coworkers, and

  16. Neutron spectroscopy with scintillation detectors using wavelets

    NASA Astrophysics Data System (ADS)

    Hartman, Jessica

    The purpose of this research was to study neutron spectroscopy using the EJ-299-33A plastic scintillator. This scintillator material provided a novel means of detection for fast neutrons, without the disadvantages of traditional liquid scintillation materials. EJ-299-33A provided a more durable option to these materials, making it less likely to be damaged during handling. Unlike liquid scintillators, this plastic scintillator was manufactured from a non-toxic material, making it safer to use, as well as easier to design detectors. The material was also manufactured with inherent pulse shape discrimination abilities, making it suitable for use in neutron detection. The neutron spectral unfolding technique was developed in two stages. Initial detector response function modeling was carried out through the use of the MCNPX Monte Carlo code. The response functions were developed for a monoenergetic neutron flux. Wavelets were then applied to smooth the response function. The spectral unfolding technique was applied through polynomial fitting and optimization techniques in MATLAB. Verification of the unfolding technique was carried out through the use of experimentally determined response functions. These were measured on the neutron source based on the Van de Graff accelerator at the University of Kentucky. This machine provided a range of monoenergetic neutron beams between 0.1 MeV and 24 MeV, making it possible to measure the set of response functions of the EJ-299-33A plastic scintillator detector to neutrons of specific energies. The response of a plutonium-beryllium (PuBe) source was measured using the source available at the University of Nevada, Las Vegas. The neutron spectrum reconstruction was carried out using the experimentally measured response functions. Experimental data was collected in the list mode of the waveform digitizer. Post processing of this data focused on the pulse shape discrimination analysis of the recorded response functions to remove the

  17. Monitoring and Forecasting Ionospheric Scintillation at High Latitudes (Invited)

    NASA Astrophysics Data System (ADS)

    Prikryl, P.; Jayachandran, P. T.; Chadwick, R.; Kelly, T.

    2013-12-01

    Ionospheric scintillation (rapid signal amplitude fading and phase fluctuation) poses a threat to reliable and safe operation of modern technology that relies on Global Navigation Satellite Systems (GNSS). Ionospheric scintillation of GNSS signal severely degrades positional accuracy, causes cycle slips leading to loss of lock that affects performance of radio communication and navigation systems. At high latitudes, the scintillation is caused by ionospheric irregularities produced through coupling between solar wind plasma and the magnetosphere. Climatology of GPS scintillation at high latitudes in both hemispheres shows that phase scintillation occurs predominantly on the dayside in the cusp and in the nightside auroral oval. Solar wind disturbances, in particular the co-rotating interaction regions (CIR) on the leading edge of high-speed streams (HSS) and interplanetary coronal mass ejections (ICME), have been closely correlated with the occurrence of scintillation at high latitudes. These results demonstrated a technique of probabilistic forecast of high-latitude phase scintillation occurrence relative to arrival times of HSS and ICME. The Canadian High Arctic Ionospheric Network (CHAIN) has been monitoring GPS ionospheric scintillation and total electron content (TEC) since November 2007. One-minute amplitude and phase scintillation indices from L1 GPS signals and TEC from L1 and L2 GPS signals are computed from amplitude and phase data sampled at 50 Hz. Since 2012, significant expansion of CHAIN has begun with installation of new receivers, each capable of tracking up to 30 satellites including GLONASS and Galileo. The receivers log the raw phase and amplitude of the signal up to a 100-Hz rate for scintillation measurements. We briefly review observations of ionospheric scintillation and highlight new results from CHAIN, including the climatology of scintillation occurrence, collocation with aurora and HF radar backscatter, correlation with CIRs and ICMEs

  18. CCSSM Challenge: Graphing Ratio and Proportion

    ERIC Educational Resources Information Center

    Kastberg, Signe E.; D'Ambrosio, Beatriz S.; Lynch-Davis, Kathleen; Mintos, Alexia; Krawczyk, Kathryn

    2013-01-01

    A renewed emphasis was placed on ratio and proportional reasoning in the middle grades in the Common Core State Standards for Mathematics (CCSSM). The expectation for students includes the ability to not only compute and then compare and interpret the results of computations in context but also interpret ratios and proportions as they are…

  19. Prospective Elementary School Teachers' Proportional Reasoning

    ERIC Educational Resources Information Center

    Valverde, Gabriela; Castro, Encarnación

    2012-01-01

    We present the findings of a study on prospective elementary teachers' proportional reasoning. After describing some of the teachers' performance in solving multiplicative structure problems that involve ratios and relations of direct proportionality between quantities, we were able to establish classifications of their answers according to…

  20. Examining Prospective Teachers' Understanding of Proportional Reasoning

    ERIC Educational Resources Information Center

    Kitchen, Richard; DePree, Julie

    2004-01-01

    In this article, the authors describe their efforts to assess prospective K-8 teachers' knowledge of proportional reasoning. Based upon their analysis of prospective K-8 teachers' work on a mathematics performance task, they discuss the implications for preparing prospective teachers to teach proportional reasoning to their students. In general,…