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Sample records for in-plant neutron coincidence

  1. Monte Carlo calculations of the neutron coincidence gate utilisation factor for passive neutron coincidence counting

    CERN Document Server

    Bourva, L C A

    1999-01-01

    The general purpose neutron-photon-electron Monte Carlo N-Particle code, MCNP sup T sup M , has been used to simulate the neutronic characteristics of the on-site laboratory passive neutron coincidence counter to be installed, under Euratom Safeguards Directorate supervision, at the Sellafield reprocessing plant in Cumbria, UK. This detector is part of a series of nondestructive assay instruments to be installed for the accurate determination of the plutonium content of nuclear materials. The present work focuses on one aspect of this task, namely, the accurate calculation of the coincidence gate utilisation factor. This parameter is an important term in the interpretative model used to analyse the passive neutron coincidence count data acquired using pulse train deconvolution electronics based on the shift register technique. It accounts for the limited proportion of neutrons detected within the time interval for which the electronics gate is open. The Monte Carlo code MCF, presented in this work, represents...

  2. Neutron coincidence counting with digital signal processing

    Energy Technology Data Exchange (ETDEWEB)

    Bagi, Janos [Institute of Isotopes (IKI)-Budapest (Hungary); Dechamp, Luc; Dransart, Pascal; Dzbikowicz, Zdzislaw [European Commission, Joint Research Centre, IPSC-Ispra, VA (Italy); Dufour, Jean-Luc [Institut de Radioprotection et Surete Nucleaire-Fontenay-aux-Roses (France); Holzleitner, Ludwig [European Commission, Joint Research Centre, IPSC-Ispra (Italy); Huszti, Joseph [Institute of Isotopes (IKI)-Budapest (Hungary); Looman, Marc [Consulenze Tecniche-Cocquio Trevisago (Italy); Marin Ferrer, Montserrat [European Commission, Joint Research Centre, IPSC-Ispra (Italy); Lambert, Thierry [Institut de Radioprotection et Surete Nucleaire-Fontenay-aux-Roses (France); Peerani, Paolo [European Commission, Joint Research Centre, IPSC-Ispra (Italy)], E-mail: paolo.peerani@jrc.it; Rackham, Jamie [VT Nuclear Services-Sellafield, Seascale (United Kingdom); Swinhoe, Martyn; Tobin, Steve [N-1, Safeguards Science and Technology Group, LANL-Los Alamos, NM (United States); Weber, Anne-Laure [Institut de Radioprotection et Surete Nucleaire-Fontenay-aux-Roses (France); Wilson, Mark [VT Nuclear Services-Sellafield, Seascale (United Kingdom)

    2009-09-11

    Neutron coincidence counting is a widely adopted nondestructive assay (NDA) technique used in nuclear safeguards to measure the mass of nuclear material in samples. Nowadays, most neutron-counting systems are based on the original-shift-register technology, like the (ordinary or multiplicity) Shift-Register Analyser. The analogue signal from the He-3 tubes is processed by an amplifier/single channel analyser (SCA) producing a train of TTL pulses that are fed into an electronic unit that performs the time- correlation analysis. Following the suggestion of the main inspection authorities (IAEA, Euratom and the French Ministry of Industry), several research laboratories have started to study and develop prototypes of neutron-counting systems with PC-based processing. Collaboration in this field among JRC, IRSN and LANL has been established within the framework of the ESARDA-NDA working group. Joint testing campaigns have been performed in the JRC PERLA laboratory, using different equipment provided by the three partners. One area of development is the use of high-speed PCs and pulse acquisition electronics that provide a time stamp (LIST-Mode Acquisition) for every digital pulse. The time stamp data can be processed directly during acquisition or saved on a hard disk. The latter method has the advantage that measurement data can be analysed with different values for parameters like predelay and gate width, without repeating the acquisition. Other useful diagnostic information, such as die-away time and dead time, can also be extracted from this stored data. A second area is the development of 'virtual instruments.' These devices, in which the pulse-processing system can be embedded in the neutron counter itself and sends counting data to a PC, can give increased data-acquisition speeds. Either or both of these developments could give rise to the next generation of instrumentation for improved practical neutron-correlation measurements. The paper will

  3. Shift-register coincidence electronics system for thermal neutron counters

    Energy Technology Data Exchange (ETDEWEB)

    Swansen, J.E.; Collinsworth, P.R.; Krick, M.S.

    1980-04-01

    An improved shift-register, coincidence-counting logic circuit, developed for use with thermal neutron well counters, is described in detail. A distinguishing feature of the circuit is its ability to operate usefully at neutron counting rates of several hundred kHz. A portable electronics package incorporating the new coincidence logic and support circuits is also described.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. Computed neutron coincidence counting applied to passive waste assay

    Energy Technology Data Exchange (ETDEWEB)

    Bruggeman, M.; Baeten, P.; De Boeck, W.; Carchon, R. [Nuclear Research Centre, Mol (Belgium)

    1997-11-01

    Neutron coincidence counting applied for the passive assay of fissile material is generally realised with dedicated electronic circuits. This paper presents a software based neutron coincidence counting method with data acquisition via a commercial PC-based Time Interval Analyser (TIA). The TIA is used to measure and record all time intervals between successive pulses in the pulse train up to count-rates of 2 Mpulses/s. Software modules are then used to compute the coincidence count-rates and multiplicity related data. This computed neutron coincidence counting (CNCC) offers full access to all the time information contained in the pulse train. This paper will mainly concentrate on the application and advantages of CNCC for the non-destructive assay of waste. An advanced multiplicity selective Rossi-alpha method is presented and its implementation via CNCC demonstrated. 13 refs., 4 figs., 2 tabs.

  6. Coincidence Prompt Gamma-Ray Neutron Activation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    R.P. gandner; C.W. Mayo; W.A. Metwally; W. Zhang; W. Guo; A. Shehata

    2002-11-10

    The normal prompt gamma-ray neutron activation analysis for either bulk or small beam samples inherently has a small signal-to-noise (S/N) ratio due primarily to the neutron source being present while the sample signal is being obtained. Coincidence counting offers the possibility of greatly reducing or eliminating the noise generated by the neutron source. The present report presents our results to date on implementing the coincidence counting PGNAA approach. We conclude that coincidence PGNAA yields: (1) a larger signal-to-noise (S/N) ratio, (2) more information (and therefore better accuracy) from essentially the same experiment when sophisticated coincidence electronics are used that can yield singles and coincidences simultaneously, and (3) a reduced (one or two orders of magnitude) signal from essentially the same experiment. In future work we will concentrate on: (1) modifying the existing CEARPGS Monte Carlo code to incorporate coincidence counting, (2) obtaining coincidence schemes for 18 or 20 of the common elements in coal and cement, and (3) optimizing the design of a PGNAA coincidence system for the bulk analysis of coal.

  7. A neutron detector for (p,np) coincidence studies

    CERN Document Server

    Carman, D S; Chant, N S; Eads, A; Gu, T; Huber, G M; Huffman, J; Klyachko, A; Markham, B C; Roos, P G; Schwandt, P; Solberg, K

    1999-01-01

    A neutron detector with moderate energy resolution (approx 3 MeV) has been built for neutrons in the energy range 75-175 MeV. The detector was designed for coincidence scattering experiments. The design eliminates the need for long neutron flight paths necessary for comparable energy resolution time-of-flight measurements with a comparable efficiency-solid angle product (0.02 msr). The detector consists of thin plastic scintillators in which the neutron undergoes n-p elastic scattering. The second-scattered protons are tracked by drift chambers and detected in a sodium iodide array. The design motivations and features are presented along with results from detailed in-beam experimental tests.

  8. High-level neutron coincidence counter maintenance manual

    Energy Technology Data Exchange (ETDEWEB)

    Swansen, J.; Collinsworth, P.

    1983-05-01

    High-level neutron coincidence counter operational (field) calibration and usage is well known. This manual makes explicit basic (shop) check-out, calibration, and testing of new units and is a guide for repair of failed in-service units. Operational criteria for the major electronic functions are detailed, as are adjustments and calibration procedures, and recurrent mechanical/electromechanical problems are addressed. Some system tests are included for quality assurance. Data on nonstandard large-scale integrated (circuit) components and a schematic set are also included.

  9. First principle active neutron coincidence counting measurements of uranium oxide

    Science.gov (United States)

    Goddard, Braden; Charlton, William; Peerani, Paolo

    2014-03-01

    Uranium is present in most nuclear fuel cycle facilities ranging from uranium mines, enrichment plants, fuel fabrication facilities, nuclear reactors, and reprocessing plants. The isotopic, chemical, and geometric composition of uranium can vary significantly between these facilities, depending on the application and type of facility. Examples of this variation are: enrichments varying from depleted (~0.2 wt% 235U) to high enriched (>20 wt% 235U); compositions consisting of U3O8, UO2, UF6, metallic, and ceramic forms; geometries ranging from plates, cans, and rods; and masses which can range from a 500 kg fuel assembly down to a few grams fuel pellet. Since 235U is a fissile material, it is routinely safeguarded in these facilities. Current techniques for quantifying the 235U mass in a sample include neutron coincidence counting. One of the main disadvantages of this technique is that it requires a known standard of representative geometry and composition for calibration, which opens up a pathway for potential erroneous declarations by the State and reduces the effectiveness of safeguards. In order to address this weakness, the authors have developed a neutron coincidence counting technique which uses the first principle point-model developed by Boehnel instead of the "known standard" method. This technique was primarily tested through simulations of 1000 g U3O8 samples using the Monte Carlo N-Particle eXtended (MCNPX) code. The results of these simulations showed good agreement between the simulated and exact 235U sample masses.

  10. The optimum choice of gate width for neutron coincidence counting

    Science.gov (United States)

    Croft, S.; Henzlova, D.; Favalli, A.; Hauck, D. K.; Santi, P. A.

    2014-11-01

    In the measurement field of international nuclear safeguards, passive neutron coincidence counting is used to quantify the spontaneous fission rate of certain special nuclear materials. The shift register autocorrelation analysis method is the most commonly used approach. However, the Feynman-Y technique, which is more commonly applied in reactor noise analysis, provides an alternative means to extract the correlation information from a pulse train. In this work we consider how to select the optimum gate width for each of these two time-correlation analysis techniques. The optimum is considered to be that which gives the lowest fractional precision on the net doublets rate. Our theoretical approach is approximate but is instructional in terms of revealing the key functional dependence. We show that in both cases the same performance figure of merit applies so that common design criteria apply to the neutron detector head. Our prediction is that near optimal results, suitable for most practical applications, can be obtained from both techniques using a common gate width setting. The estimated precision is also comparable in the two cases. The theoretical expressions are tested experimentally using 252Cf spontaneous fission sources measured in two thermal well counters representative of the type in common use by international inspectorates. Fast accidental sampling was the favored method of acquiring the Feynman-Y data. Our experimental study confirmed the basic functional dependences predicted although experimental results when available are preferred. With an appropriate gate setting Feynman-Y analysis provides an alternative to shift register analysis for safeguards applications which is opening up new avenues of data collection and data reduction to explore.

  11. The optimum choice of gate width for neutron coincidence counting

    Energy Technology Data Exchange (ETDEWEB)

    Croft, S., E-mail: crofts@ornl.gov [Safeguards and Security Technology (SST), Global Nuclear Security Technology Divisions, PO Box 2008, Building 5700, MS-6166, Oak Ridge, TN 37831-6166 (United States); Henzlova, D.; Favalli, A.; Hauck, D.K.; Santi, P.A. [Safeguards Science and Technology Group (NEN-1), Nuclear Engineering and Nonproliferation Division, MS-E540, Los Alamos, NM 87545 (United States)

    2014-11-11

    In the measurement field of international nuclear safeguards, passive neutron coincidence counting is used to quantify the spontaneous fission rate of certain special nuclear materials. The shift register autocorrelation analysis method is the most commonly used approach. However, the Feynman-Y technique, which is more commonly applied in reactor noise analysis, provides an alternative means to extract the correlation information from a pulse train. In this work we consider how to select the optimum gate width for each of these two time-correlation analysis techniques. The optimum is considered to be that which gives the lowest fractional precision on the net doublets rate. Our theoretical approach is approximate but is instructional in terms of revealing the key functional dependence. We show that in both cases the same performance figure of merit applies so that common design criteria apply to the neutron detector head. Our prediction is that near optimal results, suitable for most practical applications, can be obtained from both techniques using a common gate width setting. The estimated precision is also comparable in the two cases. The theoretical expressions are tested experimentally using {sup 252}Cf spontaneous fission sources measured in two thermal well counters representative of the type in common use by international inspectorates. Fast accidental sampling was the favored method of acquiring the Feynman-Y data. Our experimental study confirmed the basic functional dependences predicted although experimental results when available are preferred. With an appropriate gate setting Feynman-Y analysis provides an alternative to shift register analysis for safeguards applications which is opening up new avenues of data collection and data reduction to explore.

  12. Using anisotropies in prompt fission neutron coincidences to assess the neutron multiplication of highly multiplying subcritical plutonium assemblies

    Science.gov (United States)

    Mueller, J. M.; Mattingly, J.

    2016-07-01

    There is a significant and well-known anisotropy between the prompt neutrons emitted from a single fission event; these neutrons are most likely to be observed at angles near 0° or 180° relative to each other. However, the propagation of this anisotropy through different generations of a fission chain reaction has not been previously studied. We have measured this anisotropy in neutron-neutron coincidences from a subcritical highly-multiplying assembly of plutonium metal. The assembly was a 4.5 kg α-phase plutonium metal sphere composed of 94% 239Pu and 6% 240Pu by mass. Data were collected using two EJ-309 liquid scintillators and two EJ-299 plastic scintillators. The angular distribution of neutron-neutron coincidences was measured at 90° and 180° and found to be largely isotropic. Simulations were performed using MCNPX-PoliMi of similar plutonium metal spheres of varying sizes and a correlation between the neutron multiplication of the assembly and the anisotropy of neutron-neutron coincidences was observed. In principle, this correlation could be used to assess the neutron multiplication of an unknown assembly.

  13. Analysis of calibration data for the uranium active neutron coincidence counting collar with attention to errors in the measured neutron coincidence rate

    Energy Technology Data Exchange (ETDEWEB)

    Croft, Stephen [Oak Ridge National Laboratory (ORNL), One Bethel Valley Road, Oak Ridge, TN (United States); Burr, Tom [International Atomic Energy Agency (IAEA), Vienna (Austria); Favalli, Andrea [Los Alamos National Laboratory (LANL), MS E540, Los Alamos, NM 87545 (United States); Nicholson, Andrew [Oak Ridge National Laboratory (ORNL), One Bethel Valley Road, Oak Ridge, TN (United States)

    2016-03-01

    The declared linear density of {sup 238}U and {sup 235}U in fresh low enriched uranium light water reactor fuel assemblies can be verified for nuclear safeguards purposes using a neutron coincidence counter collar in passive and active mode, respectively. The active mode calibration of the Uranium Neutron Collar – Light water reactor fuel (UNCL) instrument is normally performed using a non-linear fitting technique. The fitting technique relates the measured neutron coincidence rate (the predictor) to the linear density of {sup 235}U (the response) in order to estimate model parameters of the nonlinear Padé equation, which traditionally is used to model the calibration data. Alternatively, following a simple data transformation, the fitting can also be performed using standard linear fitting methods. This paper compares performance of the nonlinear technique to the linear technique, using a range of possible error variance magnitudes in the measured neutron coincidence rate. We develop the required formalism and then apply the traditional (nonlinear) and alternative approaches (linear) to the same experimental and corresponding simulated representative datasets. We find that, in this context, because of the magnitude of the errors in the predictor, it is preferable not to transform to a linear model, and it is preferable not to adjust for the errors in the predictor when inferring the model parameters.

  14. Using anisotropies in prompt fission neutron coincidences to assess the neutron multiplication of highly multiplying subcritical plutonium assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, J.M., E-mail: jonathan_mueller@ncsu.edu; Mattingly, J.

    2016-07-21

    There is a significant and well-known anisotropy between the prompt neutrons emitted from a single fission event; these neutrons are most likely to be observed at angles near 0° or 180° relative to each other. However, the propagation of this anisotropy through different generations of a fission chain reaction has not been previously studied. We have measured this anisotropy in neutron–neutron coincidences from a subcritical highly-multiplying assembly of plutonium metal. The assembly was a 4.5 kg α-phase plutonium metal sphere composed of 94% {sup 239}Pu and 6% {sup 240}Pu by mass. Data were collected using two EJ-309 liquid scintillators and two EJ-299 plastic scintillators. The angular distribution of neutron–neutron coincidences was measured at 90° and 180° and found to be largely isotropic. Simulations were performed using MCNPX-PoliMi of similar plutonium metal spheres of varying sizes and a correlation between the neutron multiplication of the assembly and the anisotropy of neutron–neutron coincidences was observed. In principle, this correlation could be used to assess the neutron multiplication of an unknown assembly.

  15. Variance estimation in neutron coincidence counting using the bootstrap method

    Energy Technology Data Exchange (ETDEWEB)

    Dubi, C., E-mail: chendb331@gmail.com [Physics Department, Nuclear Research Center of the Negev, P.O.B. 9001 Beer Sheva (Israel); Ocherashvilli, A.; Ettegui, H. [Physics Department, Nuclear Research Center of the Negev, P.O.B. 9001 Beer Sheva (Israel); Pedersen, B. [Nuclear Security Unit, Institute for Transuranium Elements, Via E. Fermi, 2749 JRC, Ispra (Italy)

    2015-09-11

    In the study, we demonstrate the implementation of the “bootstrap” method for a reliable estimation of the statistical error in Neutron Multiplicity Counting (NMC) on plutonium samples. The “bootstrap” method estimates the variance of a measurement through a re-sampling process, in which a large number of pseudo-samples are generated, from which the so-called bootstrap distribution is generated. The outline of the present study is to give a full description of the bootstrapping procedure, and to validate, through experimental results, the reliability of the estimated variance. Results indicate both a very good agreement between the measured variance and the variance obtained through the bootstrap method, and a robustness of the method with respect to the duration of the measurement and the bootstrap parameters.

  16. Boron-Coated Straw Collar for Uranium Neutron Coincidence Collar Replacement

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jianwei [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Croft, Stephen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McElroy, Robert Dennis [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-01-01

    The objective of this project was to design and optimize, in simulation space, an active neutron coincidence counter (or collar) using boron-coated straws (BCSs) as a non-3He replacement to the Uranium Neutron Coincidence Collar (UNCL). UNCL has been used by the International Atomic Energy Agency (IAEA) and European Atomic Energy Community (Euratom) since the 1980s to verify the 235U content in fresh light water reactor fuel assemblies for safeguards purposes. This report documents the design and optimization of the BCS collar.

  17. Determination of the time resolution for neutron scintillation detectors by multi-coincidence measurement

    Institute of Scientific and Technical Information of China (English)

    LI Yong-Ming; RUAN Xi-Chao; ZHOU Sin; MA Zhong-Yuan

    2011-01-01

    Based on the multi-coincidence measurement, the time resolution of three liquid scintillation detectors (BC501A) were determined strictly by solving the coincidence equations, where the influence from electronics estimated by self coincidence measurement as well as the background had been considered. The result of this work agreed well with the result that was deduced from the traditional method, and it will be helpful to analyze the energy resolution of neutron time of flight spectra measured by using such detectors at CIAE (China Institute of Atomic Energy).

  18. Sensitive neutron detection method using delayed coincidence transitions in existing iodine-containing detectors

    Science.gov (United States)

    Yakushev, E.; Rozov, S.; Drokhlyansky, A.; Filosofov, D.; Kalaninova, Z.; Timkin, V.; Ponomarev, D.

    2017-03-01

    This work explains a new, highly sensitive method for the detection of neutrons, which uses the T1/2 = 845 ns delay in the decay of 128I at the 137.8 keV energy level, resulting from the capture of thermal neutrons by iodine nuclei in NaI and CsI scintillation detectors. The use of delayed coincidence techniques with a several μs delay time window for delayed events allows for the highly effective discrimination of neutron events from any existing background signals. A comparison of ambient neutron measurements between those identified through the suggested method from a cylindrical, ø 63 mm × 63 mm NaI(Tl) scintillator and those from a low-background proportional 3He counter experimentally demonstrates the efficacy of this neutron detection method. For an isotropic, 4 π , thermal neutron flux of 1 ncm-2s-1 , the absolute sensitivity of the NaI detector was found to be 6.5 ± 1 countss-1 with an accidental coincidence background of 0.8 eventsday-1 for any delay time window of Δt = 1 μs . The proposed method can provide low-background experiments, using NaI or CsI, with measurements of the rate and stability of incoming neutron flux to a greater accuracy than 10-8 ncm-2s-1 .

  19. Simulations of Lithium-Based Neutron Coincidence Counter for Gd-Loaded Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Cowles, Christian C.; Kouzes, Richard T.; Siciliano, Edward R.

    2014-10-31

    The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Lithium-Based Alternative Neutron Detection Technology Coincidence Counting for Gd-loaded Fuels at Pacific Northwest National Laboratory for the development of a lithium-based neutron coincidence counter for nondestructively assaying Gd loaded nuclear fuel. This report provides results from MCNP simulations of a lithium-based coincidence counter for the possible measurement of Gd-loaded nuclear fuel. A comparison of lithium-based simulations and UNCL-II simulations with and without Gd loaded fuel is provided. A lithium-based model, referred to as PLNS3A-R1, showed strong promise for assaying Gd loaded fuel.

  20. Simulations of Lithium-Based Neutron Coincidence Counter for Gd-Loaded Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Cowles, Christian C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kouzes, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Siciliano, Edward R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-10-01

    The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Lithium-Based Alternative Neutron Detection Technology Coincidence Counting for Gd-loaded Fuels at Pacific Northwest National Laboratory for the development of a lithium-based neutron coincidence counter for nondestructively assaying Gd loaded nuclear fuel. This report provides results from MCNP simulations of a lithium-based coincidence counter for the possible measurement of Gd-loaded nuclear fuel. A comparison of lithium-based simulations and UNCL-II simulations with and without Gd loaded fuel is provided. A lithium-based model, referred to as PLNS3A-R1, showed strong promise for assaying Gd loaded fuel.

  1. Safeguards Technology Factsheet 3He-free Neutron Coincidence Counter

    Energy Technology Data Exchange (ETDEWEB)

    Henzlova, Daniela [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Menlove, Howard Olsen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    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.

  2. Development of Monte Carlo code for coincidence prompt gamma-ray neutron activation analysis

    Science.gov (United States)

    Han, Xiaogang

    Prompt Gamma-Ray Neutron Activation Analysis (PGNAA) offers a non-destructive, relatively rapid on-line method for determination of elemental composition of bulk and other samples. However, PGNAA has an inherently large background. These backgrounds are primarily due to the presence of the neutron excitation source. It also includes neutron activation of the detector and the prompt gamma rays from the structure materials of PGNAA devices. These large backgrounds limit the sensitivity and accuracy of PGNAA. Since most of the prompt gamma rays from the same element are emitted in coincidence, a possible approach for further improvement is to change the traditional PGNAA measurement technique and introduce the gamma-gamma coincidence technique. It is well known that the coincidence techniques can eliminate most of the interference backgrounds and improve the signal-to-noise ratio. A new Monte Carlo code, CEARCPG has been developed at CEAR to simulate gamma-gamma coincidence spectra in PGNAA experiment. Compared to the other existing Monte Carlo code CEARPGA I and CEARPGA II, a new algorithm of sampling the prompt gamma rays produced from neutron capture reaction and neutron inelastic scattering reaction, is developed in this work. All the prompt gamma rays are taken into account by using this new algorithm. Before this work, the commonly used method is to interpolate the prompt gamma rays from the pre-calculated gamma-ray table. This technique works fine for the single spectrum. However it limits the capability to simulate the coincidence spectrum. The new algorithm samples the prompt gamma rays from the nucleus excitation scheme. The primary nuclear data library used to sample the prompt gamma rays comes from ENSDF library. Three cases are simulated and the simulated results are benchmarked with experiments. The first case is the prototype for ETI PGNAA application. This case is designed to check the capability of CEARCPG for single spectrum simulation. The second

  3. High-level neutron coincidence counter (HLNCC): users' manual

    Energy Technology Data Exchange (ETDEWEB)

    Krick, M.S.; Menlove, H.O.

    1979-06-01

    This manual describes the portable High-Level Neutron Coincidence Counter (HLNCC) developed at the Los Alamos Scientific Laboratory (LASL) for the assay of plutonium, particularly by inspectors of the International Atomic Energy Agency (IAEA). The counter is designed for the measurement of the effective /sup 240/Pu mass in plutonium samples which may have a high plutonium content. The following topics are discussed: principle of operation, description of the system, operating procedures, and applications.

  4. Application of multiparameter coincidence spectrometry using a Ge detectors array to neutron activation analysis

    CERN Document Server

    Hatsukawa, Y; Hayakawa, T; Toh, Y; Shinohara, N

    2002-01-01

    The method of multiparameter coincidence spectrometry based on gamma-gamma coincidence is widely used for the nuclear structure studies, because of its high sensitivity to gamma-rays. In this study, feasibility of the method of multiparameter coincidence spectrometry for analytical chemistry was examined. Two reference igneous rock samples (JP-1, JB-1a) issued by the Geological Survey of Japan were irradiated at a research reactor, and the gamma-rays from the radioisotopes produced via neutron capture reactions were measured using an array of 12 Ge detectors with BGO Compton suppressors, GEMINI. Simultaneously 24 elements were analyzed without chemical separation. The observed smallest component was Eu contained in JP-1 with abundance of 4 ppb.

  5. Sensitive neutron detection method using delayed coincidence transitions in existing iodine-containing detectors

    CERN Document Server

    Yakushev, E; Drokhlyansky, A; Filosofov, D; Kalaninova, Z; Timkin, V; Ponomarev, D

    2016-01-01

    This letter explains a new, highly sensitive method for the detection of neutrons, which uses the T$_{1/2}=845$ ns delay in the decay of $^{128}$I at the 137.8 keV energy level, resulting from the capture of thermal neutrons by iodine nuclei in NaI and CsI scintillation detectors. The use of delayed coincidence techniques with a several $\\mu {\\rm s}$ time frame for delayed events allows for the highly effective discrimination of neutron events from any existing background signals. A comparison of ambient neutron measurements between those identified through the suggested method from a cylindrical, \\o$\\, 63 \\, {\\rm mm}\\times 63\\, {\\rm mm}$ NaI(Tl) scintillator and those from a low-background proportional $^3$He counter experimentally demonstrates the efficacy of this neutron detection method. For an isotropic, $4\\pi$, thermal neutron flux of 1 ${\\rm n}\\, {\\rm cm}^{-2}\\, {\\rm s}^{-1}$, the absolute sensitivity of the NaI detector was found to be $6.5 \\pm 1\\, {\\rm counts}\\, {\\rm s}^{-1}$ with a background of $0....

  6. The Accelerator Neutrino Neutron Interaction Experiment (ANNIE) Front Anti-Coincidence Counter (FACC) Testing

    Science.gov (United States)

    Chen, Mingqian

    The searching for proton decay (PDK) is going on current Water Cherenkov (WCh) detectors such as Super-Kamiokande. However, PDK-like backgrounds produced by the neutrino interactions will limit the sensitivity of the detectors. The Accelerator Neutrino Neutron Interaction Experiment (ANNIE) is going to measure the neutron yield of neutrino interactions in gadolinium-loaded water by the Booster Neutrino Beam (BNB) with known characteristics. In this thesis, neutrino, neutrino oscillations, Dirac neutrino and Majorana neutrino and neutrino interactions are introduced. ANNIE experiment is also introduced. And two modes of proton decays are discussed. The ANNIE experiment requires detection of the neutrons produced by the BNB interactions with water. However, dirt muons produced by the interaction of the BNB with the rock and dirt upstream of the ANNIE hall will cause a correlated background. Therefore, the Front Anti-Coincidence Counter (FACC) was built to measure the rock muons. This thesis details the design, installation, and commissioning of the ANNIE FACC.

  7. High-level neutron-coincidence-counter (HLNCC) implementation: assay of the plutonium content of mixed-oxide fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Foley, J E; Bosler, G E

    1982-04-01

    The portable High-Level Neutron Coincidence Counter is used to assay the /sup 240/Pu-effective loading of a reference mixed-oxide fuel assembly by neutron coincidence counting. We have investigated the effects on the coincidence count rate of the total fuel loading (UO/sub 2/ + PuO/sub 2/), the fissile loading, the fuel rod diameter, and the fuel rod pattern. The coincidence count rate per gram of /sup 240/Pu-effective per centimeter is primarily dependent on the total fuel loading of the assembly; the higher the loading, the higher the coincidence count rate. Detailed procedures for the assay of mixed-oxide fuel assemblies are developed.

  8. Neutron radiation of an electronic sensor using coincidence method for an active dosimeter

    CERN Document Server

    Ndoye, A; Barelaud, B; Celerier, A; Decossas, J L; Vareille, J C

    1999-01-01

    Results on the modeling and experimentation on a preliminary structure to be used in neutron dosimetry are presented. The structure consists of a thin reactive layer deposited on two facing diodes. The sensor has been developed mainly to solve the problem of neutron dosimetry in the intermediate energy range (0.5 eV to 500 keV) for which the existing electronic systems are ineffective. The use of a coincidence method for the detection of the nuclear reaction products allows the discrimination of the gamma interactions. The system can also be used down to thermal energies for which the sensitivity is considerably higher. The sensor response depends on the thickness of the reactive layer which defines the neutron sensitivity and has an influence on the slowing down and absorption of emitted particles, the depletion layer which has to be optimized for a given energy range, the thickness of the dead layer of each detector. For experimentations with an Am-Be source, we have chosen following parameters: 100 nm for ...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-01

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

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

    Science.gov (United States)

    Koehler, Katrina E.; Henzl, Vladimir; Croft, Stephen S.; Henzlova, Daniela; Santi, Peter A.

    2016-10-01

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

  11. Field test and evaluation of the passive neutron coincidence collar for prototype fast reactor fuel subassemblies

    Energy Technology Data Exchange (ETDEWEB)

    Menlove, H.O.; Keddar, A.

    1982-08-01

    The passive neutron Coincidence Collar, which was developed for the verification of plutonium content in fast reactor fuel subassemblies, has been field tested using Prototype Fast Reactor fuel. For passive applications, the system measures the /sup 240/Pu-effective mass from the spontaneous fission rate, and in addition, a self-interrogation technique is used to determine the fissile content in the subassembly. Both the passive and active modes were evaluated at the Windscale Works in the United Kingdom. The results of the tests gave a standard deviation 0.75% for the passive count and 3 to 7% for the active measurement for a 1000-s counting time. The unit will be used in the future for the verification of plutonium in fresh fuel assemblies.

  12. Gram-scale Plutonium Samples Measured by Experimental Device of Four Detectors Well-type Fast Neutron Coincidence Measurement

    Institute of Scientific and Technical Information of China (English)

    LIU; Guo-rong; LIANG; Qing-lei; LI; Jing-huai; LI; An-li

    2013-01-01

    Experimental device of four detectors well-type fast neutron coincidence measurement(see Fig.1)consists of four?127 mm×50.8 mm BC501A liquid scintillation detectors,DC271A digitizer and other circuits.Application program simultaneously acquires the waveform of each pulse output from each detector,and identifies each pulse from neutron or?particle by offline model,and gets their arrival timing.

  13. Isotopic Distributions of the l8N Fragmentation Products in Coincidence with Neutrons on Targets 197Au and 9Be

    Institute of Scientific and Technical Information of China (English)

    李湘庆; 江栋兴; 叶沿林; 华辉; 陈陶; 李智焕; 葛愉成; 王全进; 吴和宇; 靳根明; 段利敏; 肖志刚; 王宏伟; 李祖玉; 王素芳

    2002-01-01

    We present the experimental isotopic distributions of the 18 N projectile fragmentation products Li, Be,B and Cin coincidence with neutrons, as well as the inclusive ones on 197 Au and 9Be targets. In the framework of theabrasion-ablation model, these distributions are calculated for various nucleon density distributions of the projec-tile. The comparison with experimental isotopic distributions of the projectile-like fragments in coincidence withneutrons shows that the information on the nucleon density distribution of the 18N projectile can be extracted.

  14. Application of the coincidence counting technique to DD neutron spectrometry data at the NIF, OMEGA, and Z.

    Science.gov (United States)

    Lahmann, B; Milanese, L M; Han, W; Gatu Johnson, M; Séguin, F H; Frenje, J A; Petrasso, R D; Hahn, K D; Jones, B

    2016-11-01

    A compact neutron spectrometer, based on a CH foil for the production of recoil protons and CR-39 detection, is being developed for the measurements of the DD-neutron spectrum at the NIF, OMEGA, and Z facilities. As a CR-39 detector will be used in the spectrometer, the principal sources of background are neutron-induced tracks and intrinsic tracks (defects in the CR-39). To reject the background to the required level for measurements of the down-scattered and primary DD-neutron components in the spectrum, the Coincidence Counting Technique (CCT) must be applied to the data. Using a piece of CR-39 exposed to 2.5-MeV protons at the MIT HEDP accelerator facility and DD-neutrons at Z, a significant improvement of a DD-neutron signal-to-background level has been demonstrated for the first time using the CCT. These results are in excellent agreement with previous work applied to DT neutrons.

  15. Application of the coincidence counting technique to DD neutron spectrometry data at the NIF, OMEGA, and Z

    Science.gov (United States)

    Lahmann, B.; Milanese, L. M.; Han, W.; Gatu Johnson, M.; Séguin, F. H.; Frenje, J. A.; Petrasso, R. D.; Hahn, K. D.; Jones, B.

    2016-11-01

    A compact neutron spectrometer, based on a CH foil for the production of recoil protons and CR-39 detection, is being developed for the measurements of the DD-neutron spectrum at the NIF, OMEGA, and Z facilities. As a CR-39 detector will be used in the spectrometer, the principal sources of background are neutron-induced tracks and intrinsic tracks (defects in the CR-39). To reject the background to the required level for measurements of the down-scattered and primary DD-neutron components in the spectrum, the Coincidence Counting Technique (CCT) must be applied to the data. Using a piece of CR-39 exposed to 2.5-MeV protons at the MIT HEDP accelerator facility and DD-neutrons at Z, a significant improvement of a DD-neutron signal-to-background level has been demonstrated for the first time using the CCT. These results are in excellent agreement with previous work applied to DT neutrons.

  16. Application of the coincidence counting technique to DD neutron spectrometry data at the NIF, OMEGA, and Z

    Energy Technology Data Exchange (ETDEWEB)

    Lahmann, B., E-mail: lahmann@mit.edu; Milanese, L. M.; Han, W.; Gatu Johnson, M.; Séguin, F. H.; Frenje, J. A.; Petrasso, R. D. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Hahn, K. D.; Jones, B. [Sandia National Laboratory, Albuquerque, New Mexico 87123 (United States)

    2016-11-15

    A compact neutron spectrometer, based on a CH foil for the production of recoil protons and CR-39 detection, is being developed for the measurements of the DD-neutron spectrum at the NIF, OMEGA, and Z facilities. As a CR-39 detector will be used in the spectrometer, the principal sources of background are neutron-induced tracks and intrinsic tracks (defects in the CR-39). To reject the background to the required level for measurements of the down-scattered and primary DD-neutron components in the spectrum, the Coincidence Counting Technique (CCT) must be applied to the data. Using a piece of CR-39 exposed to 2.5-MeV protons at the MIT HEDP accelerator facility and DD-neutrons at Z, a significant improvement of a DD-neutron signal-to-background level has been demonstrated for the first time using the CCT. These results are in excellent agreement with previous work applied to DT neutrons.

  17. Neutron Production in Coincidence with Fragments from the {sup 40}Ca + H Reactions at E{sub lab} = 357 and 565 A MeV

    Energy Technology Data Exchange (ETDEWEB)

    Tuve, C.; Albergo, S.; Boemi, D.; Caccia, Z.; Chen, C.-X.; Costa, S.; Crawford, H.J.; Cronqvist, M.; Engelage, J.; Greiner, L.; Guzik, T.G.; Insolia, A.; Knott, C.N.; Lindstrom, P.J.; Mitchell, J.W.; Potenza, R.; Russo, G.V.; Soutoul, A.; Testard, O.; Tricomi, A.; Tull, C.E.; Waddington, C.J.; Webber, W.R.; Wefel, J.P.

    2000-12-31

    In the frame of the Transport Collaboration neutrons in coincidence with charged fragments produced in the {sup 40}Ca + H reaction at E{sub lab} = 357 and 565 AMeV have been measured at the Heavy Ion Spectrometer System (HISS) facility of the Lawrence Berkeley National Laboratory, using the multifunctional neutron spectrometer MUFFINS. The detector covered a narrow angular range about the beam in the forward direction (0? - 3.2?). In this contribution we report absolute neutron production cross sections in coincidence with charged fragments (10 {<=} Z {<=} 20). The neutron multiplicities have been estimated from the comparison between the neutron cross sections, in coincidence with the fragments, and the elemental cross sections. We have found evidence for a pre-equilibrium emission of prompt neutrons in superposition to a 'slower' deexcitation of the equilibrated remnant by emission of nucleons and fragments, as already seen in the inclusive rapidity distributions.

  18. The D-D Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Active Well Coincidence Counter

    Energy Technology Data Exchange (ETDEWEB)

    McElroy, Robert Dennis [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cleveland, Steven L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-03-01

    The 235U mass assay of bulk uranium items, such as oxide canisters, fuel pellets, and fuel assemblies, is not achievable by traditional gamma-ray assay techniques due to the limited penetration of the item by the characteristic 235U gamma rays. Instead, fast neutron interrogation methods such as active neutron coincidence counting must be used. For international safeguards applications, the most commonly used active neutron systems, the Active Well Coincidence Counter (AWCC), Uranium Neutron Collar (UNCL) and 252Cf Shuffler, rely on fast neutron interrogation using an isotopic neutron source [i.e., 252Cf or Am(Li)] to achieve better measurement accuracies than are possible using gamma-ray techniques for high-mass, high-density items. However, the Am(Li) sources required for the AWCC and UNCL systems are no longer manufactured, and newly produced systems rely on limited supplies of sources salvaged from disused instruments. The 252Cf shuffler systems rely on the use of high-output 252Cf sources, which while still available have become extremely costly for use in routine operations and require replacement every five to seven years. Lack of a suitable alternative neutron interrogation source would leave a potentially significant gap in the safeguarding of uranium processing facilities. In this work, we made use of Oak Ridge National Laboratory’s (ORNL’s) Large Volume Active Well Coincidence Counter (LV-AWCC) and a commercially available deuterium-deuterium (D-D) neutron generator to examine the potential of the D-D neutron generator as an alternative to the isotopic sources. We present the performance of the LV-AWCC with D-D generator for the assay of 235U based on the results of Monte Carlo N-Particle (MCNP) simulations and measurements of depleted uranium (DU), low enriched uranium (LEU), and highly enriched uranium (HEU) items.

  19. Improvements in Boron Plate Coating Technology for Higher Efficiency Neutron Detection and Coincidence Counting Error Reduction

    Energy Technology Data Exchange (ETDEWEB)

    Menlove, Howard Olsen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Henzlova, Daniela [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-25

    This informal report presents the measurement data and information to document the performance of the advanced Precision Data Technology, Inc. (PDT) sealed cell boron-10 plate neutron detector that makes use of the advanced coating materials and procedures. In 2015, PDT changed the boron coating materials and application procedures to significantly increase the efficiency of their basic corrugated plate detector performance. A prototype sealed cell unit was supplied to LANL for testing and comparison with prior detector cells. Also, LANL had reference detector slabs from the original neutron collar (UNCL) and the new Antech UNCL with the removable 3He tubes. The comparison data is presented in this report.

  20. Evaluation of B10Plus+* proportional detectors for neutron coincidence counting

    Energy Technology Data Exchange (ETDEWEB)

    Beddingfield, David H.; Yoon, Seokryung [International Atomic Energy Agency, Vienna International Centre, PO Box 100, 1400 Vienna, (Austria)

    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)

  1. Isotopic distributions of the sup 1 sup 8 N fragmentation products in coincidence with neutrons on targets sup 1 sup 9 sup 7 Au and sup 9 Be

    CERN Document Server

    Li Xiang Qing; Ye Yan Lin; Hua Hui; Chen Tao; Li Zhi Huan; Ge Yuch Eng; Wang Quan Jin; Wu He Yu; Jin Ge; Duan Li Min; Xiao Zhi Gang; Wang Hong Wei; Li Zhu Yu; Wang Su Fang

    2002-01-01

    The authors present the experimental isotopic distributions of the sup 1 sup 8 N projectile fragmentation products Li, Be, B and C in coincidence with neutrons, as well as the inclusive ones on sup 1 sup 9 sup 7 Au and sup 9 Be targets. In the framework of the abrasion-ablation model, these distributions are calculated for various nucleon density distributions of the projectile. The comparison with experimental isotopic distributions of the projectile-like fragments in coincidence with neutrons shows that the information on the nucleon density distribution of the sup 1 sup 8 N projectile can be extracted

  2. In-plant test and evaluation of the neutron collar for verification of PWR fuel assemblies at Resende, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Menlove, H.O.; Marzo, M.A.S.; de Almeida, S.G.; de Almeida, M.C.; Moitta, L.P.M.; Conti, L.F.; de Paiva, J.R.T.

    1985-11-01

    The neutron-coincidence collar has been evaluated for the measurement of pressurized-water reactor (PWR) fuel assemblies at the Fabrica de Elementos Combustiveis plant in Resende, Brazil. This evaluation was part of the cooperative-bilateral-safeguards technical-exchange program between the United States and Brazil. The neutron collar measures the STVU content per unit length of full fuel assemblies using neutron interrogation and coincidence counting. The STYU content is measured in the passive mode without the AmLi neutron-interrogation source. The extended evaluation took place over a period of 6 months with both scanning and single-zone measurements. The results of the tests gave a coincidence-response standard deviation of 0.7% (sigma = 1.49% for mass) for the active case and 2.5% for the passive case in 1000-s measurement times. The length measurement in the scanning mode was accurate to 0.77%. The accuracies of different calibration methods were evaluated and compared.

  3. The use of computed neutron coincidence counting with time interval analysis for the analysis of Fork-measurements on a fresh MOX-LWR fuel assembly under water

    Energy Technology Data Exchange (ETDEWEB)

    Baeten, P.; Bruggeman, M.; Carchon, R

    1998-06-01

    The objective of this study was to investigate the influence of different important parameters on measurement results for various fork-detectors. Computed Neutron Coincidence Counting (CNCC) with Time Interval Analysis (TIA) was used for this study. The performance of the electronics for the different fork-detectors was studied by investigating the deadtime perturbed zone of the Rossi-alpha distribution in TIA. The measurement revealed anomalies in the performance of the electronics of the IAEA BWR and LANL fork-detector. The IAEA PWR fork-detector functioned well and the deadtime parameter was calculated. The optimal setting for the pre delay was investigated and it was found that a pre delay of 10 micro seconds should be considered as an optimum between excluding from analysis data in the deadtime perturbed zone and keeping a high signal-to-noise ratio. For the shift register electronics used with the fork-detectors, a pre delay of only 4.5 micro seconds was used. The study of the pre delay and the deadtime showed that the calculated triples-rate is strongly dependent on these parameters. An accurate determination of the triple-rate in this type of measurements has proven to be quite difficult and requires proper operation of the electronics, a correct pre delay and an accurate deadtime correction formalism. By varying the boron concentration in water, the change of the decay time of the Rossi-alpha distribution was clearly observed. This change is due to the variation of the thermal multiplication. The variation of this decay time with the boron concentration proves that Boehnel's model for fast neutron multiplication is not valid under these measurement conditions and that a model for fast and thermal multiplication should be used in order to obtain unbiased measurement results. CNCC with TIA has proved to be a valuable tool in which parameter settings can be varied a posterori and the optimal setting can be determined for each measurement. Moreover, the

  4. Study of rare neutron induced processes and coincidence analyses to identify and reduce background contributions in the COBRA experiment; Studien seltener neutroneninduzierter Prozesse und Koinzidenzanalysen zur Bestimmung und Reduktion von Untergrundbeitraegen im COBRA-Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Timm, Jan Horst Karl

    2015-11-15

    The aim of the COBRA experiment is the observation of neutrinoless double-beta decay, primarily of the isotope {sup 116}Cd. The applied semiconductor detectors of cadmium zinc telluride that are 90% to be enriched enable both the detection and the source of this decay. The half-lives of decays of this kind are expected in the range of more than 10{sup 26} years. Therefore, the reduction of contributions to the background is of decisive importance. The main subjects of this work are, on the one hand, the time synchronization of the data, which provides the basis for coincidence analysis. This analysis method has access not only to identification of contributions to the background, but also to observe decays involving positron annihilation and decays into excited states. In this study, the intrinsic detector contamination of some decay products of {sup 238}U and {sup 232}Th was measured and sensitivities to the half-lives of the decays like {sup 120}Te and {sup 128}Te in each case to the first excited state of daughter products are given. On the other hand, qualitative studies on the importance of neutrons in the COBRA experiment were conducted. These have shown that fast neutrons, thus with energies greater than 10 keV, only result in an insignificant contribution to the background for the detection of neutrinoless double-beta decay of the {sup 116}Cd. Previous studies have also shown that the thermal neutron flux can be in situ determined by coincidence analysis.

  5. A coincidence detection system based on real-time software

    Science.gov (United States)

    Ayuso, Sindulfo; José Blanco, Juan; Medina, José; Gómez-Herrero, Raúl; García-Población, Oscar; García Tejedor, Ignacio

    2016-09-01

    Conventional real-time coincidence systems use electronic circuitry to detect coincident pulses (hardware coincidence). In this work, a new concept of coincidence system based on real-time software (software coincidence) is presented. This system is based on the recurrent supervision of the analogue-to-digital converters status, which is described in detail. A prototype has been designed and built using a low-cost development platform. It has been applied to two different experimental sets for cosmic ray muon detection. Experimental muon measurements recorded simultaneously using conventional hardware coincidence and our software coincidence system have been compared, yielding identical results. These measurements have also been validated using simultaneous neutron monitor observations. This new software coincidence system provides remarkable advantages such as higher simplicity of interconnection and adjusting. Thus, our system replaces, at least, three Nuclear Instrument Modules (NIMs) required by conventional coincidence systems, reducing its cost by a factor of 40 and eliminating pulse delay adjustments.

  6. Coincidence Auger spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Penent, F. [LCPMR, Universite Pierre et Marie Curie, 75231 Paris 5 (France) and DIAM, Universite Pierre et Marie Curie, 75252 Paris 5 (France)]. E-mail: penent@ccr.jussieu.fr; Lablanquie, P. [LURE, Universite Paris Sud, 91898 Orsay (France); Hall, R.I. [DIAM, Universite Pierre et Marie Curie, 75252 Paris 5 (France); Palaudoux, J. [LCPMR, Universite Pierre et Marie Curie, 75231 Paris 5 (France); Ito, K. [Photon Factory, IMSS, KEK, Tsukuba 305-0801 (Japan); Hikosaka, Y. [Photon Factory, IMSS, KEK, Tsukuba 305-0801 (Japan); IMS, Okazaki 444-8585 (Japan); Aoto, T. [Photon Factory, IMSS, KEK, Tsukuba 305-0801 (Japan); Eland, J.H.D. [Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford OX1 3DW (United Kingdom)

    2005-06-15

    Auger electron spectroscopy (AES) and photoelectron spectroscopy (PES) are (with X-ray emission spectroscopy, XES) powerful analytical tools for material science and gas phase studies. However, the interpretation of Auger spectra can be very difficult due to the number and complexity of the involved processes. A deeper analysis, that allows a better understanding of relaxation processes following inner shell ionization, is possible with coincidence Auger spectroscopy. This method gives a new insight into electron correlation and allows disentangling of complex Auger electron spectra. In this paper, we present some examples related to gas phase coincidence Auger electron spectroscopy using synchrotron radiation. The detection in coincidence of an Auger electron with a threshold photoelectron presents two main advantages which are good energy resolution and high coincidence count rates. This technique has also provided new results on double Auger decay processes. A further qualitative breakthrough has been made with the development of a new experimental set-up based on a magnetic bottle time-of-flight electron spectrometer. This opens up the field of multi-electron coincidence spectroscopy and allows a most detailed analysis with characterization of all possible decay pathways following inner shell ionization.

  7. Coincidence studies with antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    McGovern, M; Walters, H R J [Department of Applied Mathematics and Theoretical Physics, Queen' s University, Belfast BT7 1NN (United Kingdom); Assafrao, D; Mohallem, J R [Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, P.O Box 702, 30123-970 Belo Horizonte, MG (Brazil); Whelan, Colm T, E-mail: mmcgovern06@qub.ac.u [Department of Physics, Old Dominion University, Norfolk, VA 23529-0116 (United States)

    2010-02-01

    We present a short overview of a new method for calculating fully differential cross sections that is able to describe any aspect of coincidence measurements involving heavy projectiles. The method is based upon impact parameter close coupling with pseudostates. Examples from antiproton impact ionization are shown.

  8. Inductively coupled plasma mass spectrometry in comparison with neutron activation and ion chromatography with UV/VIS detection for the determination of lanthanides in plant materials.

    Science.gov (United States)

    Bulska, Ewa; Danko, Bożena; Dybczyński, Rajmund S; Krata, Agnieszka; Kulisa, Krzysztof; Samczyński, Zbigniew; Wojciechowski, Marcin

    2012-08-15

    Analytical performance of inductively coupled plasma mass spectrometry (ICP-MS) for determination of lanthanides in plant materials was investigated and compared with neutron activation analysis (NAA) as well as ion chromatography (IC) with UV-VIS detection. Two sample preparation protocols were tested: (i) microwave assisted digestion by concentrated nitric acid; (ii) microwave digestion involving silica and fluoride removal, followed by the selective and quantitative lanthanides group separation from the plant matrix. Several Certified Reference Materials (CRM) of plant origin were used for the evaluation of the accuracy of the applied analytical procedures. The consistency of results, obtained by various methods, enabled to establish the tentative recommended values (TRV) for several missing elements in one of CRMs. The ICP-MS, due to its very high sensitivity, has the potential to contribute to this aim. The discrepancy of the results obtained by various methods was discussed in a view of possible matrix effects related to the composition of investigated materials. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Light charged particle and neutron velocity spectra in coincidence with projectile fragments in the reaction sup 4 sup 0 Ar(44 A MeV)+ sup 2 sup 7 Al

    CERN Document Server

    Lanzanò, G; Geraci, M; Pagano, A; Aiello, S; Cunsolo, A; Fonte, R; Foti, A; Sperduto, M L; Volant, C; Charvet, J L; Dayras, R; Legrain, R

    2001-01-01

    We present a three source analysis of velocity spectra of light charged particles (LCP) and neutrons emitted in the reaction sup 4 sup 0 Ar+ sup 2 sup 7 Al at 44 A MeV. The light particle (LP) velocity spectra are studied as a function of the detection angle (1.5 deg.

  10. Coincidence classes in nonorientable manifolds

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available We study Nielsen coincidence theory for maps between manifolds of same dimension regardless of orientation. We use the definition of semi-index of a class, review the definition of defective classes, and study the occurrence of defective root classes. We prove a semi-index product formula for lifting maps and give conditions for the defective coincidence classes to be the only essential classes.

  11. Performance of an active well coincidence counter for HEU samples

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, Francesca, E-mail: fra.ferrari@gmail.co [European Commission, Joint Research Centre, Institute for the Protection and the Security of the Citizen (IPSC), 21020 Ispra (Italy); Peerani, Paolo, E-mail: paolo.peerani@jrc.i [European Commission, Joint Research Centre, Institute for the Protection and the Security of the Citizen (IPSC), 21020 Ispra (Italy)

    2010-10-15

    Neutron coincidence counting is the reference NDA technique used in nuclear safeguards to measure the mass of nuclear material in samples. For high-enriched uranium (HEU) samples active neutron interrogation is generally performed and the most common device used by nuclear inspectors is the Active Well Coincidence Counter (AWCC). Within her master thesis at the Polytechnic of Milan, the first author performed an intensive study on the characteristics and performances of the AWCC in order to assess the {sup 235}U mass in HEU oxide samples at the PERLA laboratory of JRC. The work has been summarised in this paper that starts with the optimisation of the use of AWCC for nuclear safeguards, describing the calibration procedure, reporting results of a series of verification measurements, summarising the performances that can be obtained with this instruments during inspections at fuel production plants and concluding with the discussion of uncertainties related to these measurements.

  12. Video Histories, Memories, and Coincidences

    DEFF Research Database (Denmark)

    Kacunko, Slavko

    2012-01-01

    Looping images allows us to notice things that we have never noticed before. Looping a small but exquisite selection of the video tapes of Marcel Odenbach, Dieter Kiessling and Matthias Neuenhofer may allow the discovering of Histories, Coincidences, and Infinitesimal Aesthetics inscribed...... into the Video medium as its unsurpassed topicality....

  13. Neutrons produced by muons at 25 mwe

    Science.gov (United States)

    Dragić, A.; Aničin, I.; Banjanac, R.; Udovičić, V.; Joković, D.; Maletić, D.; Savić, M.; Veselinović, N.; Puzović, J.

    2013-02-01

    The flux of fast neutrons produced by CR muons in lead at the depth of 25 mwe is measured. Lead is a common shielding material and neutrons produced in it in muon interactions are unavoidable background component, even in sensitive deep underground experiments. A low background gamma spectrometer, equipped with high purity Ge detector in coincidence with muon detector is used for this purpose. Neutrons are identified by the structure at 692 KeV in the spectrum of delayed coincidences, caused by the neutron inelastic scattering on Ge-72 isotope. Preliminary result for the fast neutron rate is 3.1(5) × 10--4n/cm2 · s.

  14. Digital coincidence counting - initial results

    Science.gov (United States)

    Butcher, K. S. A.; Watt, G. C.; Alexiev, D.; van der Gaast, H.; Davies, J.; Mo, Li; Wyllie, H. A.; Keightley, J. D.; Smith, D.; Woods, M. J.

    2000-08-01

    Digital Coincidence Counting (DCC) is a new technique in radiation metrology, based on the older method of analogue coincidence counting. It has been developed by the Australian Nuclear Science and Technology Organisation (ANSTO), in collaboration with the National Physical Laboratory (NPL) of the United Kingdom, as a faster more reliable means of determining the activity of ionising radiation samples. The technique employs a dual channel analogue-to-digital converter acquisition system for collecting pulse information from a 4π beta detector and an NaI(Tl) gamma detector. The digitised pulse information is stored on a high-speed hard disk and timing information for both channels is also stored. The data may subsequently be recalled and analysed using software-based algorithms. In this letter we describe some recent results obtained with the new acquistion hardware being tested at ANSTO. The system is fully operational and is now in routine use. Results for 60Co and 22Na radiation activity calibrations are presented, initial results with 153Sm are also briefly mentioned.

  15. Construction of a {gamma}-{gamma} and {beta}-{gamma} coincidence measurement system for precise determination of nuclear data

    Energy Technology Data Exchange (ETDEWEB)

    Furutaka, Kazuyoshi; Nakamura, Shoji; Harada, Hideo; Katoh, Toshio [Japan Nuclear Cycle Development Institute, Tokai Works, Tokai, Ibaraki (Japan)

    1999-03-01

    A {gamma}-{gamma} and {beta}-{gamma} coincidence measurement system was constructed for the precise determination of nuclear data, such as thermal neutron capture cross sections and {gamma}-ray emission probabilities. The validity of the system was tested by a {gamma}-{gamma} coincidence measurement with a {sup 60}Co standard source. (author)

  16. Using CHIMERA detector at LNS for gamma-particle coincidences

    Directory of Open Access Journals (Sweden)

    Cardella G.

    2016-01-01

    Full Text Available We have recently evaluated the quality of γ-ray angular distributions that can be extracted in particle-gamma coincidence measurements using the CHIMERA detector at LNS. γ-rays have been detected using the CsI(Tl detectors of the spherical part of the CHIMERA array. Very clean γ-rays angular distributions were extracted in reactions induced by different stable beams impinging on 12C thin targets. The results evidenced an effect of projectile spin flip on the γ-rays angular distributions. γ-particle coincidence measurements were also performed in reactions induced by neutron rich exotic beams produced through in-flight fragmentation at LNS. In recent experiments also the Farcos array was used to improve energy and angular resolution measurements of the detected charged particles. Results obtained with both stable and radioactive beams are reported.

  17. Coincidences between gravitational wave interferometers and high energy neutrino telescopes

    Energy Technology Data Exchange (ETDEWEB)

    Pradier, Thierry [Institut Pluridisciplinaire Hubert Curien (IPHC/DRS), University Louis-Pasteur, Strasbourg (France)], E-mail: pradier@in2p3.fr

    2009-04-11

    Sources of gravitational waves (GW) and emitters of high energy neutrinos (HE {nu}) both involve compact objects and matter moving at relativistic speeds. GW emission requires a departure from spherical symmetry, which is the case if clumps of matter are accreted around black holes or neutron stars, and ejected in relativistic jets, where neutrinos are believed to be produced. Both messengers interact weakly with the surrounding matter, hence point directly to the heart of the engines that power these emissions. Coincidences between GW interferometers (e.g. VIRGO) and HE {nu} telescopes (e.g. ANTARES) would then give a unique insight on the physics of the most powerful objects in the Universe. The possibility, observability and detectability for such GW/HE {nu} coincidences are analysed.

  18. Near Threshold Coincident Electrofission of Uranium -238.

    Science.gov (United States)

    Dowell, David Harry

    Using the 100% duty cycle electron beam from the University of Illinois MUSL-2 accelerator, inelastic electron scattering form factors have been measured in coincidence with the fission decay of ('238)U. Data was taken at effective elastic momentum transfers of .36, .41 .45 and .59 fm(' -1) and electron-fission fragment angular correlations were measured perpendicular to and along the momentum transfer axis. The beam energies used were 67.11, 56.91 and 46.49 MeV, with the outgoing electron detected at 60(DEGREES) and 80(DEGREES), relative to the beam direction. The electron energy resolution was .1% and the form factors were measured for excitation energies from 2 to 12 MeV. Thin films of scintillator plastic (.5 mg/cm('2)) were used to detect the fission fragments from a 1 mg/cm('2) UF(,4) target evaporated onto a .240 mg/cm('2) aluminum backing. A prominent, anisotropic threshold peak is seen in the coincident form factors. An analysis of the q-dependence of the data and of the angular correlation indicates the observed strength is E2. Fission threshold for this E2 strength is about 5.7 MeV as compared with 6 MeV for E1 decays. The peak itself is due to the onset of neutron competition at 6.15 MeV. The threshold region, when analyzed using a Gaussian K-distribution to describe the statistical density of K -states near the fission barrier, exhibits a step-like change in the value of K(,0)('2) at .7 MeV above threshold. This indicates a possible energy gap in the E2 transition states. The decay is isotropic above 7.5 MeV excitation energy. From 7 to 11.7 MeV, the distribution of E2/EO strength is relatively flat with the total strength in this region exhausting approximately 10% of an energy weighted sum rule. A comparison with hadron scattering experiments suggests that some of the strength near 11.5 MeV is due to the fission decay of the giant monopole resonance with a fission probability similar to that of E2 transitions.

  19. Search for transient gravitational waves in coincidence with short duration radio transients during 2007-2013

    CERN Document Server

    others,; Abbott, B P; Abbott, R; Abbott, T D; Abernathy, M R; Acernese, F; Ackley, K; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Adya, V B; Affeldt, C; Agathos, M; Agatsuma, K; Aggarwal, N; Aguiar, O D; Aiello, L; Ain, A; Ajith, P; Allen, B; Allocca, A; Altin, P A; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C C; Areeda, J S; Arnaud, N; Arun, K G; Ascenzi, S; Ashton, G; Ast, M; Aston, S M; Astone, P; Aufmuth, P; Aulbert, C; Babak, S; Bacon, P; Bader, M K M; Baker, P T; Baldaccini, F; Ballardin, G; Ballmer, S W; Barayoga, J C; Barclay, S E; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barta, D; Bartlett, J; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Baune, C; Bavigadda, V; Bazzan, M; Behnke, B; Bejger, M; Bell, A S; Bell, C J; Berger, B K; Bergman, J; Bergmann, G; Berry, C P L; Bersanetti, D; Bertolini, A; Betzwieser, J; Bhagwat, S; Bhandare, R; Bilenko, I A; Billingsley, G; Birch, J; Birney, R; Biscans, S; Bisht, A; Bitossi, M; Biwer, C; Bizouard, M A; Blackburn, J K; Blair, C D; Blair, D G; Blair, R M; Bloemen, S; Bock, O; Bodiya, T P; Boer, M; Bogaert, G; Bogan, C; Bohe, A; Bojtos, P; Bond, C; Bondu, F; Bonnand, R; Boom, B A; Bork, R; Boschi, V; Bose, S; Bouffanais, Y; Bozzi, A; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Briant, T; Brillet, A; Brinkmann, M; Brisson, V; Brockill, P; Brooks, A F; Brown, D A; Brown, D D; Brown, N M; Buchanan, C C; Buikema, A; Bulik, T; Bulten, H J; Buonanno, A; Buskulic, D; Buy, C; Byer, R L; Cadonati, L; Cagnoli, G; Cahillane, C; Bustillo, J Calderón; Callister, T; Calloni, E; Camp, J B; Cannon, K C; Cao, J; Capano, C D; Capocasa, E; Carbognani, F; Caride, S; Diaz, J Casanueva; Casentini, C; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Cella, G; Cepeda, C B; Baiardi, L Cerboni; Cerretani, G; Cesarini, E; Chakraborty, R; Chalermsongsak, T; Chamberlin, S J; Chan, M; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, H Y; Chen, Y; Cheng, C; Chincarini, A; Chiummo, A; Cho, H S; Cho, M; Chow, J H; Christensen, N; Chu, Q; Chua, S; Chung, S; Ciani, G; Clara, F; Clark, J A; Cleva, F; Coccia, E; Cohadon, P -F; Colla, A; Collette, C G; Cominsky, L; Constancio, M; Conte, A; Conti, L; Cook, D; Corbitt, T R; Cornish, N; Corsi, A; Cortese, S; Costa, C A; Coughlin, M W; Coughlin, S B; Coulon, J -P; Countryman, S T; Couvares, P; Coward, D M; Cowart, M J; Coyne, D C; Coyne, R; Craig, K; Creighton, J D E; Cripe, J; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Canton, T Dal; Danilishin, S L; D'Antonio, S; Danzmann, K; Darman, N S; Dattilo, V; Dave, I; Daveloza, H P; Davier, M; Davies, G S; Daw, E J; Day, R; DeBra, D; Debreczeni, G; Degallaix, J; De Laurentis, M; Deléglise, S; Del Pozzo, W; Denker, T; Dent, T; Dergachev, V; De Rosa, R; DeRosa, R T; DeSalvo, R; Dhurandhar, S; Díaz, M C; Di Fiore, L; Di Giovanni, M; Di Girolamo, T; Di Lieto, A; Di Pace, S; Di Palma, I; Di Virgilio, A; Dojcinoski, G; Dolique, V; Donovan, F; Dooley, K L; Doravari, S; Douglas, R; Downes, T P; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Ducrot, M; Dwyer, S E; Edo, T B; Edwards, M C; Effler, A; Eggenstein, H -B; Ehrens, P; Eichholz, J; Eikenberry, S S; Engels, W; Essick, R C; Etzel, T; Evans, M; Evans, T M; Everett, R; Factourovich, M; Fafone, V; Fair, H; Fairhurst, S; Fan, X; Fang, Q; Farinon, S; Farr, B; Farr, W M; Favata, M; Fays, M; Fehrmann, H; Fejer, M M; Ferrante, I; Ferreira, E C; Ferrini, F; Fidecaro, F; Fiori, I; Fiorucci, D; Fisher, R P; Flaminio, R; Fletcher, M; Fournier, J -D; Frasca, S; Frasconi, F; Frei, Z; Freise, A; Frey, R; Frey, V; Fricke, T T; Fritschel, P; Frolov, V V; Fulda, P; Fyffe, M; Gabbard, H A G; Gair, J R; Gammaitoni, L; Gaonkar, S G; Garufi, F; Gaur, G; Gehrels, N; Gemme, G; Genin, E; Gennai, A; George, J; Gergely, L; Germain, V; Ghosh, Archisman; Ghosh, S; Giaime, J A; Giardina, K D; Giazotto, A; Gill, K; Glaefke, A; Goetz, E; Goetz, R; Gondan, L; González, G; Castro, J M Gonzalez; Gopakumar, A; Gordon, N A; Gorodetsky, M L; Gossan, S E; Gosselin, M; Gouaty, R; Grado, A; Graef, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greco, G; Green, A C; Groot, P; Grote, H; Grunewald, S; Guidi, G M; Guo, X; Gupta, A; Gupta, M K; Gushwa, K E; Gustafson, E K; Gustafson, R; Hacker, J J; Hall, B R; Hall, E D; Hammond, G; Haney, M; Hanke, M M; Hanks, J; Hanna, C; Hannam, M D; Hanson, J; Hardwick, T; Harms, J; Harry, G M; Harry, I W; Hart, M J; Hartman, M T; Haster, C -J; Haughian, K; Heidmann, A; Heintze, M C; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Hennig, J; Heptonstall, A W; Heurs, M; Hild, S; Hoak, D; Hodge, K A; Hofman, D; Hollitt, S E; Holt, K; Holz, D E; Hopkins, P; Hosken, D J; Hough, J; Houston, E A; Howell, E J; Hu, Y M; Huang, S; Huerta, E A; Huet, D; Hughey, B; Husa, S; Huttner, S H; Huynh-Dinh, T; Idrisy, A; Indik, N; Ingram, D R; Inta, R; Isa, H N; Isac, J -M; Isi, M; Islas, G; Isogai, T; Iyer, B R; Izumi, K; Jacqmin, T; Jang, H; Jani, K; Jaranowski, P; Jawahar, S; Jiménez-Forteza, F; Johnson, W W; Jones, D I; Jones, R; Jonker, R J G; Ju, L; K, Haris; Kalaghatgi, C V; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Karki, S; Kasprzack, M; Katsavounidis, E; Katzman, W; Kaufer, S; Kaur, T; Kawabe, K; Kawazoe, F; Kéfélian, F; Kehl, M S; Keitel, D; Kelley, D B; Kells, W; Kennedy, R; Key, J S; Khalaidovski, A; Khalili, F Y; Khan, I; Khan, S; Khan, Z; Khazanov, E A; Kijbunchoo, N; Kim, Chunglee; Kim, J; Kim, K; Kim, Nam-Gyu; Kim, Namjun; Kim, Y -M; King, E J; King, P J; Kinzel, D L; Kissel, J S; Kleybolte, L; Klimenko, S; Koehlenbeck, S M; Kokeyama, K; Koley, S; Kondrashov, V; Kontos, A; Korobko, M; Korth, W Z; Kowalska, I; Kozak, D B; Kringel, V; Królak, A; Krueger, C; Kuehn, G; Kumar, P; Kuo, L; Kutynia, A; Lackey, B D; Landry, M; Lange, J; Lantz, B; Lasky, P D; Lazzarini, A; Lazzaro, C; Leaci, P; Leavey, S; Lebigot, E O; Lee, C H; Lee, H K; Lee, H M; Lee, K; Lenon, A; Leonardi, M; Leong, J R; Leroy, N; Letendre, N; Levin, Y; Levine, B M; Li, T G F; Libson, A; Littenberg, T B; Lockerbie, N A; Logue, J; Lombardi, A L; Lord, J E; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lough, J D; Lück, H; Lundgren, A P; Luo, J; Lynch, R; Ma, Y; MacDonald, T; Machenschalk, B; MacInnis, M; Macleod, D M; Magaña-Sandoval, F; Magee, R M; Mageswaran, M; Majorana, E; Maksimovic, I; Malvezzi, V; Man, N; Mandic, V; Mangano, V; Mansell, G L; Manske, M; Mantovani, M; Marchesoni, F; Marion, F; Márka, S; Márka, Z; Markosyan, A S; Maros, E; Martelli, F; Martellini, L; Martin, I W; Martin, R M; Martynov, D V; Marx, J N; Mason, K; Masserot, A; Massinger, T J; Masso-Reid, M; Mastrogiovanni, S; Matichard, F; Matone, L; Mavalvala, N; Mazumder, N; Mazzolo, G; McCarthy, R; McClelland, D E; McCormick, S; McGuire, S C; McIntyre, G; McIver, J; McManus, D J; McWilliams, S T; Meacher, D; Meadors, G D; Meidam, J; Melatos, A; Mendell, G; Mendoza-Gandara, D; Mercer, R A; Merilh, E L; Merzougui, M; Meshkov, S; Messenger, C; Messick, C; Metzdorff, R; Meyers, P M; Mezzani, F; Miao, H; Michel, C; Middleton, H; Mikhailov, E E; Milano, L; Miller, A L; Miller, J; Millhouse, M; Minenkov, Y; Ming, J; Mirshekari, S; Mishra, C; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Moggi, A; Mohan, M; Mohapatra, S R P; Montani, M; Moore, B C; Moore, C J; Moraru, D; Moreno, G; Morriss, S R; Mossavi, K; Mours, B; Mow-Lowry, C M; Mueller, C L; Mueller, G; Muir, A W; Mukherjee, Arunava; Mukherjee, D; Mukherjee, S; Mukund, K N; Mullavey, A; Munch, J; Murphy, D J; Murray, P G; Mytidis, A; Nardecchia, I; Naticchioni, L; Nayak, R K; Necula, V; Nedkova, K; Nelemans, G; Neri, M; Neunzert, A; Newton, G; Nguyen, T T; Nielsen, A B; Nissanke, S; Nitz, A; Nocera, F; Nolting, D; Normandin, M E N; Nuttall, L K; Oberling, J; Ochsner, E; O'Dell, J; Oelker, E; Ogin, G H; Oh, J J; Oh, S H; Ohme, F; Oliver, M; Oppermann, P; Oram, Richard J; O'Reilly, B; O'Shaughnessy, R; Ott, C D; Ottaway, D J; Ottens, R S; Overmier, H; Owen, B J; Pai, A; Pai, S A; Palamos, J R; Palashov, O; Palomba, C; Pal-Singh, A; Pan, H; Pankow, C; Pannarale, F; Pant, B C; Paoletti, F; Paoli, A; Papa, M A; Paris, H R; Parker, W; Pascucci, D; Pasqualetti, A; Passaquieti, R; Passuello, D; Patricelli, B; Patrick, Z; Pearlstone, B L; Pedraza, M; Pedurand, R; Pekowsky, L; Pele, A; Penn, S; Pereira, R; Perreca, A; Phelps, M; Piccinni, O J; Pichot, M; Piergiovanni, F; Pierro, V; Pillant, G; Pinard, L; Pinto, I M; Pitkin, M; Pletsch, H J; Poggiani, R; Popolizio, P; Post, A; Powell, J; Prasad, J; Predoi, V; Premachandra, S S; Prestegard, T; Price, L R; Prijatelj, M; Principe, M; Privitera, S; Prodi, G A; Prokhorov, L; Puncken, O; Punturo, M; Puppo, P; Pürrer, M; Qi, H; Qin, J; Quetschke, V; Quintero, E A; Quitzow-James, R; Raab, F J; Rabeling, D S; Radkins, H; Raffai, P; Raja, S; Rakhmanov, M; Rapagnani, P; Raymond, V; Razzano, M; Re, V; Read, J; Reed, C M; Regimbau, T; Rei, L; Reid, S; Reitze, D H; Rew, H; Ricci, F; Riles, K; Robertson, N A; Robie, R; Robinet, F; Rocchi, A; Rolland, L; Rollins, J G; Roma, V J; Romano, J D; Romano, R; Romanov, G; Romie, J H; Rosińska, D; Rowan, S; Rüdiger, A; Ruggi, P; Ryan, K; Sachdev, S; Sadecki, T; Sadeghian, L; Salconi, L; Saleem, M; Salemi, F; Samajdar, A; Sammut, L; Sanchez, E J; Sandberg, V; Sandeen, B; Sanders, J R; Sassolas, B; Sathyaprakash, B S; Saulson, P R; Sauter, O E S; Savage, R L; Sawadsky, A; Schale, P; Schilling, R; Schmidt, J; Schmidt, P; Schnabel, R; Schofield, R M S; Schönbeck, A; Schreiber, E; Schuette, D; Schutz, B F; Scott, J; Scott, S M; Sellers, D; Sentenac, D; Sequino, V; Sergeev, A; Serna, G; Setyawati, Y; Sevigny, A; Shaddock, D A; Shahriar, M S; Shaltev, M; Shao, Z; Shapiro, B; Shawhan, P; Sheperd, A; Shoemaker, D H; Shoemaker, D M; Siellez, K; Siemens, X; Sieniawska, M; Sigg, D; Silva, A D; Simakov, D; Singer, A; Singer, L P; Singh, A; Singh, R; Singhal, A; Sintes, A M; Slagmolen, B J J; Smith, J R; Smith, N D; Smith, R J E; Son, E J; Sorazu, B; Sorrentino, F; Souradeep, T; Srivastava, A K; Staley, A; Steinke, M; Steinlechner, J; Steinlechner, S; Steinmeyer, D; Stephens, B C; Stiles, D; Stone, R; Strain, K A; Straniero, N; Stratta, G; Strauss, N A; Strigin, S; Sturani, R; Stuver, A L; Summerscales, T Z; Sun, L; Sutton, P J; Swinkels, B L; Szczepańczyk, M J; Tacca, M; Talukder, D; Tanner, D B; Tápai, M; Tarabrin, S P; Taracchini, A; Taylor, R; Theeg, T; Thirugnanasambandam, M P; Thomas, E G; Thomas, M; Thomas, P; Thorne, K A; Thrane, E; Tiwari, S; Tiwari, V; Tokmakov, K V; Tomlinson, C; Tonelli, M; Torres, C V; Torrie, C I; Töyrä, D; Travasso, F; Traylor, G; Trifirò, D; Tringali, M C; Trozzo, L; Tse, M; Turconi, M; Tuyenbayev, D; Ugolini, D; Unnikrishnan, C S; Urban, A L; Usman, S A; Vahlbruch, H; Vajente, G; Valdes, G; van Bakel, N; van Beuzekom, M; Brand, J F J van den; Broeck, C Van Den; Vander-Hyde, D C; van der Schaaf, L; van Heijningen, J V; van Veggel, A A; Vardaro, M; Vass, S; Vasúth, M; Vaulin, R; Vecchio, A; Vedovato, G; Veitch, J; Veitch, P J; Venkateswara, K; Verkindt, D; Vetrano, F; Viceré, A; Vinciguerra, S; Vine, D J; Vinet, J -Y; Vitale, S; Vo, T; Vocca, H; Vorvick, C; Voss, D V; Vousden, W D; Vyatchanin, S P; Wade, A R; Wade, L E; Wade, M; Walker, M; Wallace, L; Walsh, S; Wang, G; Wang, H; Wang, M; Wang, X; Wang, Y; Ward, R L; Warner, J; Was, M; Weaver, B; Wei, L -W; Weinert, M; Weinstein, A J; Weiss, R; Welborn, T; Wen, L; Wessels, P; Westphal, T; Wette, K; Whelan, J T; Whitcomb, S E; White, D J; Whiting, B F; Williams, R D; Williamson, A R; Willis, J L; Willke, B; Wimmer, M H; Winkler, W; Wipf, C C; Wittel, H; Woan, G; Worden, J; Wright, J L; Wu, G; Yablon, J; Yam, W; Yamamoto, H; Yancey, C C; Yap, M J; Yu, H; Yvert, M; zny, A Zadro; Zangrando, L; Zanolin, M; Zendri, J -P; Zevin, M; Zhang, F; Zhang, L; Zhang, M; Zhang, Y; Zhao, C; Zhou, M; Zhou, Z; Zhu, X J; Zucker, M E; Zuraw, S E; Zweizig, J; Archibald, A M; Banaszak, S; Berndsen, A; Boyles, J; Cardoso, R F; Chawla, P; Cherry, A; Dartez, L P; Day, D; Epstein, C R; Ford, A J; Flanigan, J; Garcia, A; Hessels, J W T; Hinojosa, J; Jenet, F A; Karako-Argaman, C; Kaspi, V M; Keane, E F; Kondratiev, V I; Kramer, M; Leake, S; Lorimer, D; Lunsford, G; Lynch, R S; Martinez, J G; Mata, A; McLaughlin, M A; McPhee, C A; Penucci, T; Ransom, S; Roberts, M S E; Rohr, M D W; Stairs, I H; Stovall, K; van Leeuwen, J; Walker, A N; Wells, B L

    2016-01-01

    We present an archival search for transient gravitational wave bursts in coincidence with 27 single pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO, Virgo and GEO interferometer network. We also discuss a check for gravitational wave signals in coincidence with Parkes Fast Radio Bursts using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible sources of emission of both short duration radio signals andtransient gravitational wave emission include starquakes on neutron stars, binary coalescence of neutron stars, and cosmic string cusps. While no evidence for gravitational wave emission in coincidence with these radio transients was found, the current analysis serves as a prototype for similar future searches using more sensitive second generation interferometers.

  20. K-causality coincides with stable causality

    OpenAIRE

    Minguzzi, E

    2008-01-01

    It is proven that K-causality coincides with stable causality, and that in a K-causal spacetime the relation K^+ coincides with the Seifert's relation. As a consequence the causal relation "the spacetime is strongly causal and the closure of the causal relation is transitive" stays between stable causality and causal continuity.

  1. From Mere Coincidences to Meaningful Discoveries

    Science.gov (United States)

    Griffiths, Thomas L.; Tenenbaum, Joshua B.

    2007-01-01

    People's reactions to coincidences are often cited as an illustration of the irrationality of human reasoning about chance. We argue that coincidences may be better understood in terms of rational statistical inference, based on their functional role in processes of causal discovery and theory revision. We present a formal definition of…

  2. Sensitivity to coincidences and paranormal belief.

    Science.gov (United States)

    Hadlaczky, Gergö; Westerlund, Joakim

    2011-12-01

    Often it is difficult to find a natural explanation as to why a surprising coincidence occurs. In attempting to find one, people may be inclined to accept paranormal explanations. The objective of this study was to investigate whether people with a lower threshold for being surprised by coincidences have a greater propensity to become believers compared to those with a higher threshold. Participants were exposed to artificial coincidences, which were formally defined as less or more probable, and were asked to provide remarkability ratings. Paranormal belief was measured by the Australian Sheep-Goat Scale. An analysis of the remarkability ratings revealed a significant interaction effect between Sheep-Goat score and type of coincidence, suggesting that people with lower thresholds of surprise, when experiencing coincidences, harbor higher paranormal belief than those with a higher threshold. The theoretical aspects of these findings were discussed.

  3. Knot polynomial identities and quantum group coincidences

    CERN Document Server

    Morrison, Scott; Snyder, Noah

    2010-01-01

    We construct link invariants using the D_2n subfactor planar algebras, and use these to prove new identities relating certain specializations of colored Jones polynomials to specializations of other quantum knot polynomials. These identities can also be explained by coincidences between small modular categories involving the even parts of the D_2n planar algebras. We discuss the origins of these coincidences, explaining the role of SO level-rank duality, Kirby-Melvin symmetry, and properties of small Dynkin diagrams. One of these coincidences involves G_2 and does not appear to be related to level-rank duality.

  4. Obstruction Theory and Coincidences in Positive Codimension

    Institute of Scientific and Technical Information of China (English)

    Daciberg GON(C)ALVES; Jerzy JEZIERSKI; Peter WONG

    2006-01-01

    Let f, g: X → Y be two maps between closed manifolds with dim X ≥ dim Y = n ≥ 3.We study the primary obstruction on(f,g) to deforming f and g to be coincidence free on the n-th skeleton of X. We give examples for which obstructions to deforming f and g to be coincidence free are detected by on (f, g).

  5. Determining activities of radionuclides from coincidence signatures

    Science.gov (United States)

    Warren, Glen A.; Smith, L. Eric; Aalseth, Craig E.; Ellis, Edward; Hossbach, Todd W.; Valsan, Andrei B.

    2006-05-01

    The spectral analysis of simultaneously observed photons in separate detectors may provide an invaluable tool for radioisotope identification applications. A general recursive method to determine the activity of an isotope from the observed coincidence signature rate is discussed. The method coherently accounts for effects of true coincidence summing within a single detector and detection efficiencies. A verification of the approach with computer simulations is also discussed.

  6. Simulation of triple coincidences in PET.

    Science.gov (United States)

    Cal-González, J; Lage, E; Herranz, E; Vicente, E; Udias, J M; Moore, S C; Park, M-A; Dave, S R; Parot, V; Herraiz, J L

    2015-01-07

    Although current PET scanners are designed and optimized to detect double coincidence events, there is a significant amount of triple coincidences in any PET acquisition. Triple coincidences may arise from causes such as: inter-detector scatter (IDS), random triple interactions (RT), or the detection of prompt gamma rays in coincidence with annihilation photons when non-pure positron-emitting radionuclides are used (β(+)γ events). Depending on the data acquisition settings of the PET scanner, these triple events are discarded or processed as a set of double coincidences if the energy of the three detected events is within the scanner's energy window. This latter option introduces noise in the data, as at most, only one of the possible lines-of-response defined by triple interactions corresponds to the line along which the decay occurred. Several novel works have pointed out the possibility of using triple events to increase the sensitivity of PET scanners or to expand PET imaging capabilities by allowing differentiation between radiotracers labeled with non-pure and pure positron-emitting radionuclides. In this work, we extended the Monte Carlo simulator PeneloPET to assess the proportion of triple coincidences in PET acquisitions and to evaluate their possible applications. We validated the results of the simulator against experimental data acquired with a modified version of a commercial preclinical PET/CT scanner, which was enabled to acquire and process triple-coincidence events. We used as figures of merit the energy spectra for double and triple coincidences and the triples-to-doubles ratio for different energy windows and radionuclides. After validation, the simulator was used to predict the relative quantity of triple-coincidence events in two clinical scanners assuming different acquisition settings. Good agreement between simulations and preclinical experiments was found, with differences below 10% for most of the observables considered. For clinical

  7. Neutron angular distribution in plutonium-240 spontaneous fission

    Energy Technology Data Exchange (ETDEWEB)

    Marcath, Matthew J., E-mail: mmarcath@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States); Shin, Tony H.; Clarke, Shaun D. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States); Peerani, Paolo [European Commission at the Joint Research Centre, Ispra (Italy); Pozzi, Sara A. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States)

    2016-09-11

    Nuclear safeguards applications require accurate fission models that exhibit prompt neutron anisotropy. In the laboratory reference frame, an anisotropic neutron angular distribution is observed because prompt fission neutrons carry momentum from fully accelerated fission fragments. A liquid organic scintillation detector array was used with pulse shape discrimination techniques to produce neutron-neutron cross-correlation time distributions and angular distributions from spontaneous fission in a {sup 252}Cf, a 0.84 g {sup 240}Pu{sub eff} metal, and a 1.63 g {sup 240}Pu{sub eff} metal sample. The effect of cross-talk, estimated with MCNPX-PoliMi simulations, is removed from neutron-neutron coincidences as a function of the angle between detector pairs. Fewer coincidences were observed at detector angles near 90°, relative to higher and lower detector angles. As light output threshold increases, the observed anisotropy increases due to spectral effects arising from fission fragment momentum transfer to emitted neutrons. Stronger anisotropy was observed in Cf-252 spontaneous fission prompt neutrons than in Pu-240 neutrons. - Highlights: • Pu-240 prompt fission fast-neutron anisotropy was quantified for the first time. • MCNPX-PoliMi and MPPost codes were used to remove cross-talk neutron detections from experiment results. • Cf-252 spontaneous fission neutrons were found to be more anisotropic than Pu-240 neutrons.

  8. Setting confidence intervals in coincidence search analysis

    CERN Document Server

    Baggio, L; Baggio, Lucio; Prodi, Giovanni A.

    2003-01-01

    The main technique that has been used to estimate the rate of gravitational wave (gw) bursts is to search for coincidence among times of arrival of candidate events in different detectors. Coincidences are modeled as a (possibly non-stationary) random time series background with gw events embedded in it, at random times but constant average rate. It is critical to test whether the statistics of the coincidence counts is Poisson, because the counts in a single detector often are not. At some point a number of parameters are tuned to increase the chance of detection by reducing the expected background: source direction, epoch vetoes based on sensitivity, goodness-of-fit thresholds, etc. Therefore, the significance of the confidence intervals itself has to be renormalized. This review is an insight of the state-of-the-art methods employed in the recent search performed by the International Gravitational Event Collaboration for the worldwide network of resonant bar detectors.

  9. Two neutron correlations in photo-fission

    Science.gov (United States)

    Dale, D. S.; Kosinov, O.; Forest, T.; Burggraf, J.; Stave, S.; Warren, G.; Starovoitova, V.

    2016-09-01

    A large body of experimental work has established the strong kinematical correlation between fission fragments and fission neutrons. Here, we report on the progress of investigations of the potential for strong two neutron correlations arising from the nearly back-to-back nature of the two fission fragments that emit these neutrons in the photo-fission process. In initial measurements, a pulsed electron linear accelerator was used to generate bremsstrahlung photons that impinged upon an actinide target, and the energy and opening angle distributions of coincident neutrons were measured using a large acceptance neutron detector array. A planned comprehensive set of measurements of two neutron correlations in the photo-fission of actinides is expected to shed light on several fundamental aspects of the fission process including the multiplicity distributions associated with the light and heavy fission fragments, the nuclear temperatures of the fission fragments, and the mass distribution of the fission fragments as a function of energy released. In addition to these measurements providing important nuclear data, the unique kinematics of fission and the resulting two neutron correlations have the potential to be the basis for a new tool to detect fissionable materials. A key technical challenge of this program arises from the need to perform coincidence measurements with a low duty factor, pulsed electron accelerator. This has motivated the construction of a large acceptance neutron detector array, and the development of data analysis techniques to directly measure uncorrelated two neutron backgrounds.

  10. A DSP-based multichannel analyzer for simultaneous acquisition of coincidence and anticoincidence spectra

    Energy Technology Data Exchange (ETDEWEB)

    Byun, S.H. [Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON, L8S 4K1 (Canada)], E-mail: soohyun@mcmaster.ca; Chin, K.; Prestwich, W.V.; McNeill, F.E.; Chettle, D.R. [Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON, L8S 4K1 (Canada)

    2007-10-15

    A digital signal processor (DSP) based multichannel analyzer (MCA) has been developed for simultaneous acquisition of coincidence and anticoincidence {gamma}-ray spectra. The shaped pulse from the spectroscopy amplifier is digitized by a flash analog-to-digital converter and then processed by a DSP. The coincidence mode operation is implemented by an external gate signal from a coincidence module. Fundamental performance was tested using NaI(Tl) detectors and compared with that of a standard NIM module. The new MCA is currently used for in vivo neutron activation analysis. Further development is in preparation toward full digital processing, which is free from the remaining analog component, that is the spectroscopy amplifier.

  11. A Precise Analytic Delayed Coincidence Efficiency and Accidental Coincidence Rate Calculation

    CERN Document Server

    Yu, Jingyi; Chen, Shaomin

    2013-01-01

    In a delayed coincidence experiment, for example, the recent reactor neutrino oscillation experiments, a precise analytic determination of the delayed coincidence signal efficiency and the accidental coincidence background rate is important for the high accuracy measurement of the oscillation parameters and to understand systematic uncertainties associated with fluctuations in muon rate and random background rate. In this work, a data model is proposed to describe the full time sequence of all possible events on the live time axis. The acceptance of delayed coincidence signals, the rate of accidental backgrounds and other coincidence possibilities are calculated by assuming that all of the `net muons' are uniformly distributed on the live time axis. The intrinsic relative uncertainties in the event rates are at the $10^{-5}$ level for all combinations. The model and predictions are verified with a high statistics Monte Carlo study with a set of realistic parameters.

  12. Neutron Repulsion

    OpenAIRE

    Manuel, Oliver K.

    2011-01-01

    Earth is connected gravitationally, magnetically and electrically to its heat source - a neutron star that is obscured from view by waste products in the photosphere. Neutron repulsion is like the hot filament in an incandescent light bulb. Excited neutrons are emitted from the solar core and decay into hydrogen that glows in the photosphere like a frosted light bulb. Neutron repulsion was recognized in nuclear rest mass data in 2000 as the overlooked source of energy, the keystone of an arch...

  13. Using Compton scattering for random coincidence rejection

    Science.gov (United States)

    Kolstein, M.; Chmeissani, M.

    2016-12-01

    The Voxel Imaging PET (VIP) project presents a new approach for the design of nuclear medicine imaging devices by using highly segmented pixel CdTe sensors. CdTe detectors can achieve an energy resolution of ≈ 1% FWHM at 511 keV and can be easily segmented into submillimeter sized voxels for optimal spatial resolution. These features help in rejecting a large part of the scattered events from the PET coincidence sample in order to obtain high quality images. Another contribution to the background are random events, i.e., hits caused by two independent gammas without a common origin. Given that 60% of 511 keV photons undergo Compton scattering in CdTe (i.e. 84% of all coincidence events have at least one Compton scattering gamma), we present a simulation study on the possibility to use the Compton scattering information of at least one of the coincident gammas within the detector to reject random coincidences. The idea uses the fact that if a gamma undergoes Compton scattering in the detector, it will cause two hits in the pixel detectors. The first hit corresponds to the Compton scattering process. The second hit shall correspond to the photoelectric absorption of the remaining energy of the gamma. With the energy deposition of the first hit, one can calculate the Compton scattering angle. By measuring the hit location of the coincident gamma, we can construct the geometric angle, under the assumption that both gammas come from the same origin. Using the difference between the Compton scattering angle and the geometric angle, random events can be rejected.

  14. Coincidence velocity map imaging using a single detector

    Science.gov (United States)

    Zhao, Arthur; Sándor, Péter; Weinacht, Thomas

    2017-07-01

    We demonstrate a single-detector velocity map imaging setup which is capable of rapidly switching between coincidence and non-coincidence measurements. By rapidly switching the extraction voltages on the electrostatic lenses, both electrons and ions can be collected in coincidence with a single detector. Using a fast camera as the 2D detector avoids the saturation problem associated with traditional delay line detectors and allows for easy transitions between coincidence and non-coincidence data collection modes. This is a major advantage in setting up a low-cost and versatile coincidence apparatus. We present both coincidence and non-coincidence measurements of strong field atomic and molecular ionization.

  15. A new method to reduce the statistical and systematic uncertainty of chance coincidence backgrounds measured with waveform digitizers

    CERN Document Server

    O'Donnell, J M

    2016-01-01

    A new method for measuring chance-coincidence backgrounds during the collection of coincidence data is presented. The method relies on acquiring data with near-zero dead time, which is now realistic due to the increasing deployment of flash electronic-digitizer (waveform digitizer) techniques. An experiment designed to use this new method is capable of acquiring more coincidence data, and a much reduced statistical fluctuation of the measured background. A statistical analysis is presented, and used to derive a figure of merit for the new method. Factors of four improvement over other analyses are realistic. The technique is illustrated with preliminary data taken as part of a program to make new measurements of the prompt fission neutron spectra at Los Alamos Neutron Science Center. It is expected that the these measurements will occur in a regime where the maximum figure of merit will be exploited.

  16. Search for transient gravitational waves in coincidence with short-duration radio transients during 2007-2013

    Science.gov (United States)

    Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allocca, A.; Altin, P. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Babak, S.; Bacon, P.; Bader, M. K. M.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bavigadda, V.; Bazzan, M.; Behnke, B.; Bejger, M.; Bell, A. S.; Bell, C. J.; Berger, B. K.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Birney, R.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bogan, C.; Bohe, A.; Bojtos, P.; Bond, C.; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerboni Baiardi, L.; Cerretani, G.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, H. Y.; Chen, Y.; Cheng, C.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C. G.; Cominsky, L.; Constancio, M.; Conte, A.; Conti, L.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Darman, N. S.; Dattilo, V.; Dave, I.; Daveloza, H. P.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Engels, W.; Essick, R. C.; Etzel, T.; Evans, M.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H. A. G.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S. G.; Garufi, F.; Gaur, G.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, J.; Gergely, L.; Germain, V.; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gordon, N. A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hacker, J. J.; Hall, B. R.; Hall, E. D.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.

    2016-06-01

    We present an archival search for transient gravitational-wave bursts in coincidence with 27 single-pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO, Virgo, and GEO interferometer network. We also discuss a check for gravitational-wave signals in coincidence with Parkes fast radio bursts using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible sources of emission of both short-duration radio signals and transient gravitational-wave emission include starquakes on neutron stars, binary coalescence of neutron stars, and cosmic string cusps. While no evidence for gravitational-wave emission in coincidence with these radio transients was found, the current analysis serves as a prototype for similar future searches using more sensitive second-generation interferometers.

  17. Grain-boundary structures in hexagonal materials: Coincident and near coincident grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, D. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Materials Science and Engineering)

    1994-07-01

    Embedded atom method (EAM) simulations of the structure of grain boundaries in hexagonal metal, are presented. The simulations use recently developed interatomic potentials for Ti and Co. Structures were calculated for various symmetrical tilt boundaries with the [1,100] tilt axis. The structures obtained for both metals are very similar. The energies for the Co boundaries are higher than those for Ti by a factor of 2. The structural unit model was applied to the computed grain-boundary structures in these hexagonal materials. As in cubic materials, the structural unit model can describe a series of symmetrical tilt coincident boundaries. In addition, when the coincidence ratio in the grain-boundary plane varies with the c/a ratio, a structural unit-type model can describe the variation of grain-boundary structure with c/a ratio. This model is adequate for describing series of symmetrical tilt boundaries with the grain-boundary plane oriented perpendicular to a fixed crystallographic direction and varying c/a ratios. For the structures of the so-called near coincident boundaries that appear in these materials, it was concluded that near coincident boundaries behave similarly to exact coincidence boundaries if there is a coincident periodic structure in the grain-boundary plane. This may occur even without a three-dimensional (3-D) coincident site lattice.

  18. Kinematical coincidence method in transfer reactions

    Energy Technology Data Exchange (ETDEWEB)

    Acosta, L.; Amorini, F. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Auditore, L. [INFN Gruppo Collegato di Messina and Dipartimento di Fisica, Università di Messina (Italy); Berceanu, I. [Institute for Physics and Nuclear Engineering, Bucharest (Romania); Cardella, G., E-mail: cardella@ct.infn.it [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Chatterjiee, M.B. [Saha Institute for Nuclear Physics, Kolkata (India); De Filippo, E. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Francalanza, L.; Gianì, R. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); Grassi, L. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Rudjer Boskovic Institute, Zagreb (Croatia); Grzeszczuk, A. [Institut of Physics, University of Silesia, Katowice (Poland); La Guidara, E. [INFN—Sezione di Catania, Via S. Sofia, 95123 Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Lanzalone, G. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Facoltà di Ingegneria e Architettura, Università Kore, Enna (Italy); Lombardo, I. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Scienze Fisiche, Università Federico II and INFN Sezione di Napoli (Italy); Loria, D.; Minniti, T. [INFN Gruppo Collegato di Messina and Dipartimento di Fisica, Università di Messina (Italy); Pagano, E.V. [INFN—Laboratori Nazionali del Sud, Via S. Sofia, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia, Catania (Italy); and others

    2013-07-01

    A new method to extract high resolution angular distributions from kinematical coincidence measurements in binary reactions is presented. Kinematics is used to extract the center of mass angular distribution from the measured energy spectrum of light particles. Results obtained in the case of {sup 10}Be+p→{sup 9}Be+d reaction measured with the CHIMERA detector are shown. An angular resolution of few degrees in the center of mass is obtained. The range of applicability of the method is discussed.

  19. Neutron Radiography

    Science.gov (United States)

    Heller, A. K.; Brenizer, J. S.

    Neutron radiography and its related two-dimensional (2D) neutron imaging techniques have been established as invaluable nondestructive inspection methods and quantitative measurement tools. They have been used in a wide variety of applications ranging from inspection of aircraft engine turbine blades to study of two-phase fluid flow in operating proton exchange membrane fuel cells. Neutron radiography is similar to X-ray radiography in that the method produces a 2D attenuation map of neutron radiation that has penetrated the object being examined. However, the images produced differ and are often complementary due to the differences between X-ray and neutron interaction mechanisms. The uses and types of 2D neutron imaging have expanded over the past 15 years as a result of advances in imaging technology and improvements in neutron generators/sources and computers. Still, high-intensity sources such as those from reactors and spallation neutron sources, together with conventional film radiography, remain the mainstay of high-resolution, large field-of-view neutron imaging. This chapter presents a summary of the history, methods, and related variations of neutron radiography techniques.

  20. Tagging fast neutrons from a 252Cf fission-fragment source

    CERN Document Server

    Scherzinger, Julius; Annand, John; Fissum, Kevin; Hall-Wilton, Richard; Mauritzson, Nicholai; Messi, Francesco; Perrey, Hanno; Rofors, Emil

    2016-01-01

    Coincidence and time-of-flight measurement techniques are employed to tag fission neutrons emitted from a 252Cf source. Fission fragments detected in a gaseous 4He scintillator detector supply the tag. Neutrons are detected in a NE-213 liquid-scintillator detector. The resulting continuous polychromatic beam of tagged neutrons has an energy dependence that agrees qualitatively with expectations.

  1. Fusion neutronics

    CERN Document Server

    Wu, Yican

    2017-01-01

    This book provides a systematic and comprehensive introduction to fusion neutronics, covering all key topics from the fundamental theories and methodologies, as well as a wide range of fusion system designs and experiments. It is the first-ever book focusing on the subject of fusion neutronics research. Compared with other nuclear devices such as fission reactors and accelerators, fusion systems are normally characterized by their complex geometry and nuclear physics, which entail new challenges for neutronics such as complicated modeling, deep penetration, low simulation efficiency, multi-physics coupling, etc. The book focuses on the neutronics characteristics of fusion systems and introduces a series of theories and methodologies that were developed to address the challenges of fusion neutronics, and which have since been widely applied all over the world. Further, it introduces readers to neutronics design’s unique principles and procedures, experimental methodologies and technologies for fusion systems...

  2. Development of DUPIC safeguards neutron counter

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Gil; Cha, Hong Ryul; Kim, Ho Dong; Hong, Jong Sook; Kang, Hee Young

    1999-08-01

    KAERI, in cooperation with LANL, developed DSNC (DUPIC Safeguards Neutron Counter) for safeguards implementing on DUPIC process which is under development by KAERI for direct use of spent PWR fuel in CANDU reactors. DSNC is a well-type neutron coincidence counter with substantial shielding to protect system from high gamma radiation of spent fuel. General development procedures in terms of design, manufacturing, fabrication, cold and hot test, performance test for DSNC authentication by KAERI-IAEA-LANL are described in this report. It is expected that the techniques related DSNC development and associated neutron detection and evaluation method could be applied for safeguards improvement. (Author). 20 refs., 16 tabs. 98 figs.

  3. Development of DUPIC safeguards neutron counter

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Gil; Cha, Hong Ryul; Kim, Ho Dong; Hong, Jong Sook; Kang, Hee Young

    1999-08-01

    KAERI, in cooperation with LANL, developed DSNC (DUPIC Safeguards Neutron Counter) for safeguards implementing on DUPIC process which is under development by KAERI for direct use of spent PWR fuel in CANDU reactors. DSNC is a well-type neutron coincidence counter with substantial shielding to protect system from high gamma radiation of spent fuel. General development procedures in terms of design, manufacturing, fabrication, cold and hot test, performance test for DSNC authentication by KAERI-IAEA-LANL are described in this report. It is expected that the techniques related DSNC development and associated neutron detection and evaluation method could be applied for safeguards improvement. (Author). 20 refs., 16 tabs. 98 figs.

  4. Neutron Albedo

    CERN Document Server

    Ignatovich, V K

    2005-01-01

    A new, algebraic, method is applied to calculation of neutron albedo from substance to check the claim that use of ultradispersive fuel and moderator of an active core can help to gain in size and mass of the reactor. In a model of isotropic distribution of incident and reflected neutrons it is shown that coherent scattering on separate grains in the case of thermal neutrons increases transport cross section negligibly, however it decreases albedo from a wall of finite thickness because of decrease of substance density. A visible increase of albedo takes place only for neutrons with wave length of the order of the size of a single grain.

  5. A method for coincidence timing resolution enhancement

    Science.gov (United States)

    Ermis, E. E.; Celiktas, C.; Pilicer, E.

    2016-05-01

    A method including the coincidence time resolution improvement for a TOF/positron emission tomography system was suggested. The spectrometer for this aim was composed of two NaI(Tl) and two plastic scintillation detectors. Experimental results were supported by FLUKA Monte Carlo simulation program by constructing the detector setup in software medium. Present experimental results verified our previous results and conclusions obtained from the suggested method. It was concluded that better resolutions would help the improvement not only on the TOF gain but also on the spatial resolution, leading to better images and helping the Physician in his/her diagnosis and treatment.

  6. Performance of coincidence-based PSD on LiF/ZnS Detectors for Multiplicity Counting

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Sean M.; Stave, Sean C.; Lintereur, Azaree; Siciliano, Edward R.; Cowles, Christian C.; Kouzes, Richard T.; Behling, Richard S.

    2016-10-06

    Abstract: Mass accountancy measurement is a nuclear nonproliferation application which utilizes coincidence and multiplicity counters to verify special nuclear material declarations. With a well-designed and efficient detector system, several relevant parameters of the material can be verified simultaneously. 6LiF/ZnS scintillating sheets may be used for this purpose due to a combination of high efficiency and short die-away times in systems designed with this material, but involve choices of detector geometry and exact material composition (e.g., the addition of Ni-quenching in the material) that must be optimized for the application. Multiplicity counting for verification of declared nuclear fuel mass involves neutron detection in conditions where several neutrons arrive in a short time window, with confounding gamma rays. This paper considers coincidence-based Pulse-Shape Discrimination (PSD) techniques developed to work under conditions of high pileup, and the performance of these algorithms with different detection materials. Simulated and real data from modern LiF/ZnS scintillator systems are evaluated with these techniques and the relationship between the performance under pileup and material characteristics (e.g., neutron peak width and total light collection efficiency) are determined, to allow for an optimal choice of detector and material.

  7. Solar Neutron Transport in the Earth's Atmosphere

    Science.gov (United States)

    Valdes-Galicia, J. F.; Dorman, L. I.; Dorman, I. V.

    1998-11-01

    We present results of a numerical simulation and analytical solution of small scale neutron multi-scattering and attenuation in the earth atmosphere. A range of initial zenith angles and different atmpspheric depths are considered. We show that the angular distribution of neutrons remains symetrycal only for vertical arrival. For inclined arrival the distribution becomes asymetrical; the asymmetry grows with increasing zenith angle. This effect is caused by the stronger attenuation of neutrons scattered to zenith angles larger than the arrival angle. Our analytical solution shows reasonable coincidence with the numerical simulation results. These solutions are able to reproduce the normalised observed counting rates of neutron monitors for the event of 24 may 1990, the largest Solar Neutron event observed on Earth.

  8. Neutron dosimetry; Dosimetria de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Fratin, Luciano

    1993-12-31

    A neutron irradiation facility was designed and built in order to establish a procedure for calibrating neutron monitors and dosemeters. A 185 GBq {sup 241} Am Be source of known is used as a reference source. The irradiation facility using this source in the air provides neutron dose rates between 9 nSv s{sup -1} and 0,5 {sup {mu}}Sv s{sup -1}. A calibrated 50 nSv s{sup -1} thermal neutron field is obtained by using a specially designed paraffin block in conjunction with the {sup 241} Am Be source. A Bonner multisphere spectrometer was calibrated, using a procedure based on three methods proposed by international standards. The unfold {sup 241} Am Be neutron spectrum was determined from the Bonner spheres data and resulted in a good agreement with expected values for fluence rate, dose rate and mean energy. A dosimetric system based on the electrochemical etching of CR-39 was developed for personal dosimetry. The dosemeter badge using a (n,{alpha}) converter, the etching chamber and high frequency power supply were designed and built specially for this project. The electrochemical etching (ECE) parameters used were: a 6N KOH solution, 59 deg C, 20 kV{sub pp} cm{sup -1}, 2,0 kHz, 3 hours of ECE for thermal and intermediate neutrons and 6 hours for fast neutrons. The calibration factors for thermal, intermediate and fast neutrons were determined for this personal dosemeter. The sensitivities determined for the developed dosimetric system were (1,46{+-} 0,09) 10{sup 4} tracks cm{sup -2} mSv{sup -1} for thermal neutrons, (9{+-}3) 10{sup 2} tracks cm{sup -2} mSV{sup -1} for intermediate neutrons and (26{+-}4) tracks cm{sup -2} mSv{sup -1} for fast neutrons. The lower and upper limits of detection were respectively 0,002 mSv and 0,6 mSv for thermal neutrons, 0,04 mSv and 8 mSv for intermediate neutrons and 1 mSv and 12 mSv for fast neutrons. In view of the 1990`s ICRP recommendations, it is possible to conclude that the personal dosemeter described in this work is

  9. Measurement of accidental coincidences in beta-gamma coincidence counting using non-equal dead times

    CERN Document Server

    Hwang, H Y; Cho, Y H; Byun, J I; Kim, T S; Park, T S; Lee, J M

    2002-01-01

    It is shown that the multi-channel time-scaling (MCTS) method is particularly suitable for the direct measurement of accidental coincidences even if the dead times of the two counting channels are of different length. We prepared five samples, with activities from 900 to 2100 s sup - sup 1. The dead time of the gamma channel was 12 mu s for all measurements, but for the beta channel it varied from 12 to 20 mu s. The true coincidence rates determined by the MCTS method are compared with those obtained by using conventional technique.

  10. Neutron reflectometry

    DEFF Research Database (Denmark)

    Klösgen-Buchkremer, Beate Maria

    2014-01-01

    films or films with magnetic properties. The reason is the peculiar property of neutron light since the mass of a neutron is close to the one of a proton, and since it bears a magnetic moment. The optical properties of matter, when interacting with neutrons, are described by a refractive index......Neutron (and X-ray) reflectometry constitute complementary interfacially sensitive techniques that open access to studying the structure within thin films of both soft and hard condensed matter. Film thickness starts oxide surfaces on bulk substrates, proceeding to (pauci-)molecular layers and up...... to hundreds of nanometers. Thickness resolution for flat surfaces is in the range of few Ǻngstrøm, and as a peculiar benefit, the presence and properties of buried interfaces are accessible. Focus here will be on neutron reflectometry, a technique that is unique in applications involving composite organic...

  11. Beta-delayed neutron spectroscopy of spherical and deformed neutron emitters with VANDLE

    Science.gov (United States)

    King, Thomas; Gross, C. J.; Grzywacz, R. K.; Paulauskas, S. V.; Rykaczewski, K. P.; Stracener, D. W.,; Taylor, S. Z.; Vandle Collaboration

    2016-09-01

    For many neutron-rich isotopes, the main decay mode is through beta-delayed neutron and gamma emission. Neutron and gamma coincidences provide information necessary to extract the beta-strength distribution. These distributions are inputs to test nuclear models needed for r-process modeling. The detailed data on beta decay feeding to neutron-unbound states are used to calculate reactor decay heat and understand the antineutrino spectrum. A series of measurements with selective ion sources was performed at the On-Line Test Facility (OLTF) at Oak Ridge National Laboratory with the Versatile Array of Neutron Detectors at Low Energy (VANDLE). These experiments revisited decays of spherical and deformed isotopes produced in proton induced fission of 238U, which included beta delayed precursors of bromine, rubidium, cesium, and iodine. Unique data sets with neutron and gamma ray coincidences were collected. Achieving high coincidence efficiency required the addition of high-efficiency gamma-ray detectors consisting of 16 LaBr3 crystals (HAGRiD) and a large volume set of NaI detectors to VANDLE. Preliminary results will be presented. This research was sponsored by DOE under Contracts DE-FG52-08NA2855, DE-AC05-00OR22725 and DE-FG02-96ER40983.

  12. Fabry's disease and psychosis: causality or coincidence?

    Science.gov (United States)

    Gairing, S; Wiest, R; Metzler, S; Theodoridou, A; Hoff, P

    2011-01-01

    A 21-year-old female with Fabry's disease (FD) presented acute psychotic symptoms such as delusions, auditory hallucinations and formal thought disorders. Since the age of 14, she had suffered from various psychiatric symptoms increasing in frequency and intensity. We considered the differential diagnoses of prodromal symptoms of schizophrenia and organic schizophrenia-like disorder. Routine examinations including cognitive testing, electroencephalography and structural magnetic resonance imaging revealed no pathological findings. Additional structural and functional imaging demonstrated a minor CNS involvement of FD, yet without functional limitations. In summary our examination results support the thesis that in the case of our patient a mere coincidence of FD and psychotic symptoms is more likely than a causal connection.

  13. Dark energy, curvature and cosmic coincidence

    CERN Document Server

    Franca, U

    2006-01-01

    The fact that the energy densities of dark energy and matter are similar currently, known as the coincidence problem, is one of the main unsolved problems of cosmology. We present here a phenomenological model in which a spatial curvature of the universe can lead to a transition in the present epoch from a matter dominated universe to a scaling dark energy dominance in a very natural way. In particular, we show that if the exponential potential of the dark energy field depends linearly on the spatial curvature density of a closed universe, the observed values of some cosmological parameters can be obtained assuming acceptable values for the present spatial curvature of the universe, and without fine tuning in the only parameter of the model. We also comment on possible variations of this model.

  14. The Coincident Fission Fragment Detector (CFFD)

    Science.gov (United States)

    Wakhle, A.; Hammerton, K.; Kohley, Z.; Yurkon, J.; Stiefel, K.

    2017-08-01

    A Parallel Plate Avalanche Counter (PPAC) based fission detector system, called the Coincident Fission Fragment Detector (CFFD), has been developed for the ReA3 re-accelerator facility of the National Superconducting Cyclotron Laboratory (NSCL). Binary reaction kinematics are reconstructed based on position and time-of-flight measurements of fission fragments. Large area PPACs provide 1 ns level time resolution and mm level position resolution. The detectors allow measurements of fission product angular and mass distributions of heavy-ion induced fusion reactions. The 30 cm by 40 cm active area of each PPAC provides large solid angle coverage well suited for measurements of low intensity rare-isotope beams (RIBs).

  15. Planned search for LIGO-GBM coincidence in the first advanced LIGO data run

    CERN Document Server

    Camp, Jordan; Briggs, Michael; Christensen, Nelson; Connaughton, Valerie; Singer, Leo; Shawhan, Peter; Veitch, John

    2015-01-01

    In the fall of 2015 the first scientific observing run (O1) of the advanced LIGO detectors will be conducted. Based on the recent commissioning progress at the LIGO Hanford and Livingston sites, the gravitational wave detector range for a neutron star binary inspiral is expected to be of order 60 Mpc. We describe here our planning for an O1 search for coincidence between a LIGO gravitational wave detection and a gamma-ray signal from the Fermi Gamma-ray Burst Monitor. Such a coincidence would constitute measurement of an electromagnetic counterpart to a gravitational wave signal, with significant corresponding scientific benefits, including revealing the central engine powering the gamma-ray burst, enhanced confidence in the event as a genuine astrophysical detection, and a determination of the relative speed of the photon and graviton.

  16. Scintillation neutron detectors based on solid-state photomultipliers and lightguides

    Energy Technology Data Exchange (ETDEWEB)

    Litvin, V. S., E-mail: vlitvin@inr.ru; Marin, V. N.; Karaevsky, S. K.; Trunov, D. N.; Axenov, S. N.; Stolyarov, A. A.; Sadykov, R. A. [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation)

    2016-01-15

    Neutron detectors based on scintillation screens ZnS(Ag)/LiF and solid-state photomultipliers have been developed. Lightguides are used to collect light. The application of a coincidence scheme provides a low dark count and a neutron detection efficiency as high as 70%. A scheme of x-y neutron detector based on wavelength shifting fibers is also proposed. Tests of the proposed versions of detectors in a neutron beam have shown their efficiency.

  17. The underwater coincidence counter for plutonium measurements in mixed-oxide fuel assemblies manual

    Energy Technology Data Exchange (ETDEWEB)

    G. W. Eccleston; H. O. Menlove; M. Abhold; M. Baker; J. Pecos

    1999-05-01

    This manual describes the Underwater Coincidence Counter (UWCC) that has been designed for the measurement of plutonium in mixed-oxide (MOX) fuel assemblies prior to irradiation. The UWCC uses high-efficiency {sup 3}He neutron detectors to measure the spontaneous-fission and induced-fission rates in the fuel assembly. Measurements can be made on MOX fuel assemblies in air or underwater. The neutron counting rate is analyzed for singles, doubles, and triples time correlations to determine the {sup 240}Pu effective mass per unit length of the fuel assembly. The system can verify the plutonium loading per unit length to a precision of less than 1% in a measurement time of 2 to 3 minutes. System design, components, performance tests, and operational characteristics are described in this manual.

  18. Neutron angular distribution in plutonium-240 spontaneous fission

    Science.gov (United States)

    Marcath, Matthew J.; Shin, Tony H.; Clarke, Shaun D.; Peerani, Paolo; Pozzi, Sara A.

    2016-09-01

    Nuclear safeguards applications require accurate fission models that exhibit prompt neutron anisotropy. In the laboratory reference frame, an anisotropic neutron angular distribution is observed because prompt fission neutrons carry momentum from fully accelerated fission fragments. A liquid organic scintillation detector array was used with pulse shape discrimination techniques to produce neutron-neutron cross-correlation time distributions and angular distributions from spontaneous fission in a 252Cf, a 0.84 g 240Pueff metal, and a 1.63 g 240Pueff metal sample. The effect of cross-talk, estimated with MCNPX-PoliMi simulations, is removed from neutron-neutron coincidences as a function of the angle between detector pairs. Fewer coincidences were observed at detector angles near 90°, relative to higher and lower detector angles. As light output threshold increases, the observed anisotropy increases due to spectral effects arising from fission fragment momentum transfer to emitted neutrons. Stronger anisotropy was observed in Cf-252 spontaneous fission prompt neutrons than in Pu-240 neutrons.

  19. Neutron Imaging Developments at LANSCE

    Science.gov (United States)

    Nelson, Ron; Hunter, James; Schirato, Richard; Vogel, Sven; Swift, Alicia; Ickes, Tim; Ward, Bill; Losko, Adrian; Tremsin, Anton

    2015-10-01

    Neutron imaging is complementary to x-ray imaging because of its sensitivity to light elements and greater penetration of high-Z materials. Energy-resolved neutron imaging can provide contrast enhancements for elements and isotopes due to the variations with energy in scattering cross sections due to nuclear resonances. These cross section differences exist due to compound nuclear resonances that are characteristic of each element and isotope, as well as broader resonances at higher energies. In addition, multi-probe imaging, such as combined photon and neutron imaging, is a powerful tool for discerning properties and features in materials that cannot be observed with a single probe. Recently, we have demonstrated neutron imaging, both radiography and computed tomography, using the moderated (Lujan Center) and high-energy (WNR facility) neutron sources at LANSCE. Flat panel x-ray detectors with suitable scintillator-converter screens provide good sensitivity for both low and high neutron energies. Micro-Channel-Plate detectors and iCCD scintillator camera systems that provide the fast time gating needed for energy-resolved imaging have been demonstrated as well. Examples of recent work will be shown including fluid flow in plants and imaging through dense thick objects. This work is funded by the US Department of Energy, National Nuclear Security Administration, and performed by Los Alamos National Security LLC under Contract DE-AC52-06NA25396.

  20. Complex Action Support from Coincidences of Couplings

    CERN Document Server

    Nielsen, Holger Bech

    2011-01-01

    The model of Ninomiya and myself of complex action in a functional integral formulation interpreted by means of path integrals extending over all times, both past and future, is reviewed. A few numerical relations between coupling constants and masses are taken as supporting evidences. The new one such supporting ev- idence among the mentioned "coincidences" is that our model is able to explain (suggestively) that a) the Higgs field expectation value is very small ("scale problem") compared to say some fundamental scale that might be the Planck scale, b) This Higgs VEV scale need not be just zero, but rather is predicted to be so that the running top-quark Yukawa coupling just is about unity at this scale. In this way it is easily becoming an "exponentially" small scale. Instead of the top-Yukawa we should rather here say the highest flavour Yukawa coupling. These predictions are only achieved by allowing the principle of minimization of the imaginary part of the action SI(history) to to a certain extent adju...

  1. Neutron multiplication error in TRU waste measurements

    Energy Technology Data Exchange (ETDEWEB)

    Veilleux, John [Los Alamos National Laboratory; Stanfield, Sean B [CCP; Wachter, Joe [CCP; Ceo, Bob [CCP

    2009-01-01

    Total Measurement Uncertainty (TMU) in neutron assays of transuranic waste (TRU) are comprised of several components including counting statistics, matrix and source distribution, calibration inaccuracy, background effects, and neutron multiplication error. While a minor component for low plutonium masses, neutron multiplication error is often the major contributor to the TMU for items containing more than 140 g of weapons grade plutonium. Neutron multiplication arises when neutrons from spontaneous fission and other nuclear events induce fissions in other fissile isotopes in the waste, thereby multiplying the overall coincidence neutron response in passive neutron measurements. Since passive neutron counters cannot differentiate between spontaneous and induced fission neutrons, multiplication can lead to positive bias in the measurements. Although neutron multiplication can only result in a positive bias, it has, for the purpose of mathematical simplicity, generally been treated as an error that can lead to either a positive or negative result in the TMU. While the factors that contribute to neutron multiplication include the total mass of fissile nuclides, the presence of moderating material in the matrix, the concentration and geometry of the fissile sources, and other factors; measurement uncertainty is generally determined as a function of the fissile mass in most TMU software calculations because this is the only quantity determined by the passive neutron measurement. Neutron multiplication error has a particularly pernicious consequence for TRU waste analysis because the measured Fissile Gram Equivalent (FGE) plus twice the TMU error must be less than 200 for TRU waste packaged in 55-gal drums and less than 325 for boxed waste. For this reason, large errors due to neutron multiplication can lead to increased rejections of TRU waste containers. This report will attempt to better define the error term due to neutron multiplication and arrive at values that are

  2. Analysis of a measured neutron background below 6 MeV for fast-neutron imaging systems

    Science.gov (United States)

    Ide, K.; Becchetti, M. F.; Flaska, M.; Poitrasson-Riviere, A.; Hamel, M. C.; Polack, J. K.; Lawrence, C. C.; Clarke, S. D.; Pozzi, S. A.

    2012-12-01

    Detailed and accurate information on the neutron background is relevant for many applications that involve radiation detection, both for non-coincidence and coincidence countings. In particular, for the purpose of developing advanced neutron-detection techniques for nuclear non-proliferation and nuclear safeguards, the energy-dependent, ground-level, neutron-background information is needed. There are only a few previous studies available about the neutron background below 10 MeV, which is a typical neutron energy range of interest for nuclear non-proliferation and nuclear-safeguards applications. Thus, there is a potential for further investigation in this energy range. In this paper, neutron-background measurement results using organic-liquid scintillation detectors are described and discussed, with a direct application in optimization simulations of a fast-neutron imager based on liquid scintillators. The measurement was performed in summer 2011 in Ann Arbor, Michigan, USA, and the measurement setup consisted of several EJ-309 liquid scintillators and a fast waveform digitizer. The average neutron flux below 6 MeV was measured to be approximately 4e-4 counts/cm2/s. In addition, the relationship between the neutron-background count rate and various environmental quantities, such as humidity, at Earth's ground level was investigated and the results did not reveal any straightforward dependences. The measured pulse height distribution (PHD) was unfolded to determine the energy spectrum of the background neutrons. The unfolded neutron-background spectrum was implemented to a previously-created MCNPX-PoliMi model of the neutron-scatter camera and simple-backprojection images of the background neutrons were acquired. Furthermore, a simulated PHD was obtained with the MCNPX-PoliMi code using the "Cosmic-Ray Shower Library" (CRY) source sub-routine which returns various types of radiation, including neutrons and photons at a surface, and accounts for solar cycle

  3. Measurement of the Surface and Underground Neutron Spectra with the UMD/NIST Fast Neutron Spectrometers

    Science.gov (United States)

    Langford, Thomas J.

    The typical fast neutron detector falls into one of two categories, Bonner sphere spectrometers and liquid scintillator proton recoil detectors. These two detector types have traditionally been used to measure fast neutrons at the surface and in low background environments. The cosmogenic neutron spectrum and flux is an important parameter for a number of experimental efforts, including procurement of low background materials and the prediction of electronic device faults. Fast neutrons can also cause problems for underground low-background experiments, through material activation or signals that mimic rare events. Current detector technology is not sufficient to properly characterize these backgrounds. To this end, the University of Maryland and the National Institute of Standards and Technology designed, developed, and deployed two Fast Neutron Spectrometers (FaNS) comprised of plastic scintillator and 3He proportional counters. The detectors are based upon capture-gated spectroscopy, a technique that demands a delayed coincidence between a neutron scatter and the resulting neutron capture after thermalization. This technique provides both particle identification and knowledge that the detected neutron fully thermalized. This improves background rejection capabilities and energy resolution. Presented are the design, development, and deployment of FaNS-1 and FaNS-2. Both detectors were characterized using standard fields at NIST, including calibrated 252Cf neutron sources and two monoenergetic neutron generators. Measurements of the surface fast neutron spectrum and flux have been made with both detectors, which are compared with previous measurements by traditional detectors. Additionally, FaNS-1 was deployed at the Kimballton Underground Research Facility (KURF) in Ripplemead, VA. A measurement of the fast neutron spectrum and flux at KURF is presented as well. FaNS-2 is currently installed in a shallow underground laboratory where it is measuring the muon

  4. GAMBE: multipurpose sandwich detector for neutrons and photons

    Science.gov (United States)

    Ahmed, A.; Burdin, S.; Casse, G.; van Zalinge, H.; Powel, S.; Rees, J.; Smith, A.; Tsurin, I.

    2016-10-01

    Detectors made with semiconductors such as silicon can be efficiently used for detecting and imaging neutrons when coated with suitable materials. They detect the charged reaction products resulting from the interaction of thermal neutrons with materials with high capture cross section like 10B, 6Li, and 6LiF. This work describes the performance of a thermal neutron detector system, GAMBE, which is based on silicon sensors and a layer of neutron-sensitive material, such as a lithium fluoride film or a lithium-6 foil, in a sandwich configuration. This arrangement has a total detection efficiency of 4 +/- 2 %, 7 +/- 1 %, and12 +/- 1 % for 7 μm 6LiF film, 40 μm and 70 μm 6Li foil respectively. Also, it enhances the rejection of fake hits using a simple coincidence method. The coincidence that defines a true neutron hit is the simultaneous signal recorded by the two sensors facing the conversion layer (or foil). These coincidences provide a very good method for rejecting the spurious hits coming from gamma-rays, which are usually present in the neutron field under measurement. The GAMBE system yields a rejection factor at the level of 108 allowing very pure neutron detection in high gamma background conditions. However, the price to pay is a reduction of the detection efficiency of 1 +/- 1 % or 0:9 +/- 0:3 % for 7 μm 6LiF film and 40 μm 6Li foil respectively.

  5. Neutron Repulsion

    CERN Document Server

    Manuel, Oliver K

    2011-01-01

    Earth is connected gravitationally, magnetically and electrically to its heat source - a neutron star that is obscured from view by waste products in the photosphere. Neutron repulsion is like the hot filament in an incandescent light bulb. Excited neutrons are emitted from the solar core and decay into hydrogen that glows in the photosphere like a frosted light bulb. Neutron repulsion was recognized in nuclear rest mass data in 2000 as the overlooked source of energy, the keystone of an arch that locked together these puzzling space-age observations: 1.) Excess 136Xe accompanied primordial helium in the stellar debris that formed the solar system (Fig. 1); 2.) The Sun formed on the supernova core (Fig. 2); 3.) Waste products from the core pass through an iron-rich mantle, selectively carrying lighter elements and lighter isotopes of each element into the photosphere (Figs. 3-4); and 4.) Neutron repulsion powers the Sun and sustains life (Figs. 5-7). Together these findings offer a framework for understanding...

  6. Multi-Electron Coincidence Studies of Atoms and Molecules

    OpenAIRE

    Andersson, Egil

    2010-01-01

    This thesis concerns multi-ionization coincidence measurements of atoms and small molecules using a magnetic bottle time-of-flight (TOF) spectrometer designed for multi-electron coincidence studies. Also, a time-of-flight mass spectrometer has been used together with the TOF electron  spectrometer for electron-ion coincidence measurements. The multi-ionization processes have been studied by employing a pulsed discharge lamp in the vacuum ultraviolet spectral region and synchrotron radiation i...

  7. New approach to calculate the true-coincidence effect of HpGe detector

    Energy Technology Data Exchange (ETDEWEB)

    Alnour, I. A., E-mail: aaibrahim3@live.utm.my, E-mail: ibrahim.elnour@yahoo.com [Department of Physics, Faculty of Pure and Applied Science, International University of Africa, 12223 Khartoum (Sudan); Wagiran, H. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai,Johor (Malaysia); Ibrahim, N. [Faculty of Defence Science and Technology, National Defence University of Malaysia, Kem Sungai Besi, 57000 Kuala Lumpur (Malaysia); Hamzah, S.; Elias, M. S. [Malaysia Nuclear Agency (MNA), Bangi, 43000 Kajang, Selangor D.E. (Malaysia); Siong, W. B. [Chemistry Department, Faculty of Resource Science & Technology, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak (Malaysia)

    2016-01-22

    The corrections for true-coincidence effects in HpGe detector are important, especially at low source-to-detector distances. This work established an approach to calculate the true-coincidence effects experimentally for HpGe detectors of type Canberra GC3018 and Ortec GEM25-76-XLB-C, which are in operation at neutron activation analysis lab in Malaysian Nuclear Agency (NM). The correction for true-coincidence effects was performed close to detector at distances 2 and 5 cm using {sup 57}Co, {sup 60}Co, {sup 133}Ba and {sup 137}Cs as standard point sources. The correction factors were ranged between 0.93-1.10 at 2 cm and 0.97-1.00 at 5 cm for Canberra HpGe detector; whereas for Ortec HpGe detector ranged between 0.92-1.13 and 0.95-100 at 2 and 5 cm respectively. The change in efficiency calibration curve of the detector at 2 and 5 cm after correction was found to be less than 1%. Moreover, the polynomial parameters functions were simulated through a computer program, MATLAB in order to find an accurate fit to the experimental data points.

  8. Neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Heger, G. [Rheinisch-Westfaelische Technische Hochschule Aachen, Inst. fuer Kristallographie, Aachen (Germany)

    1996-12-31

    X-ray diffraction using conventional laboratory equipment and/or synchrotron installations is the most important method for structure analyses. The purpose of this paper is to discuss special cases, for which, in addition to this indispensable part, neutrons are required to solve structural problems. Even though the huge intensity of modern synchrotron sources allows in principle the study of magnetic X-ray scattering the investigation of magnetic structures is still one of the most important applications of neutron diffraction. (author) 15 figs., 1 tab., 10 refs.

  9. BOUNDS ON COINCIDENCE INDICES ON NON-ORIENTABLE SURFACES

    Institute of Scientific and Technical Information of China (English)

    D.VENDR(U)SCOLO

    2005-01-01

    This paper presents some results about bounds for coincidence indices of Nielsen coincidence classes for maps between nonorientable surfaces. Denoting by Kn the nonorientable surface constructed by a connected sum of n torus with a Klein bottle,the author proves: (i) for pairs of maps between two Klein bottles or for pairs of maps from a Klein bottle to a surface Kn the coincidence class index is bounded. (ii) for pairs of maps from Kn to the Klein bottle the coincidence class index is unbounded.Other boundedness results are given for more technical conditions, including one for self maps.

  10. Neutronics of pulsed spallation neutron sources

    CERN Document Server

    Watanabe, N

    2003-01-01

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

  11. Fusion-neutron measurements for magnetized liner inertial fusion experiments on the Z accelerator

    Science.gov (United States)

    Hahn, K. D.; Chandler, G. A.; Ruiz, C. L.; Cooper, G. W.; Gomez, M. R.; Slutz, S.; Sefkow, A. B.; Sinars, D. B.; Hansen, S. B.; Knapp, P. F.; Schmit, P. F.; Harding, E.; Jennings, C. A.; Awe, T. J.; Geissel, M.; Rovang, D. C.; Torres, J. A.; Bur, J. A.; Cuneo, M. E.; Glebov, V. Yu; Harvey-Thompson, A. J.; Herrman, M. C.; Hess, M. H.; Johns, O.; Jones, B.; Lamppa, D. C.; Lash, J. S.; Martin, M. R.; McBride, R. D.; Peterson, K. J.; Porter, J. L.; Reneker, J.; Robertson, G. K.; Rochau, G. A.; Savage, M. E.; Smith, I. C.; Styron, J. D.; Vesey, R. A.

    2016-05-01

    Several magnetized liner inertial fusion (MagLIF) experiments have been conducted on the Z accelerator at Sandia National Laboratories since late 2013. Measurements of the primary DD (2.45 MeV) neutrons for these experiments suggest that the neutron production is thermonuclear. Primary DD yields up to 3e12 with ion temperatures ∼2-3 keV have been achieved. Measurements of the secondary DT (14 MeV) neutrons indicate that the fuel is significantly magnetized. Measurements of down-scattered neutrons from the beryllium liner suggest ρRliner∼1g/cm2. Neutron bang times, estimated from neutron time-of-flight (nTOF) measurements, coincide with peak x-ray production. Plans to improve and expand the Z neutron diagnostic suite include neutron burn-history diagnostics, increased sensitivity and higher precision nTOF detectors, and neutron recoil-based yield and spectral measurements.

  12. Neutron spectrometer for fast nuclear reactors

    CERN Document Server

    Osipenko, M; Ricco, G; Caiffi, B; Pompili, F; Pillon, M; Angelone, M; Verona-Rinati, G; Cardarelli, R; Mila, G; Argiro, S

    2015-01-01

    In this paper we describe the development and first tests of a neutron spectrometer designed for high flux environments, such as the ones found in fast nuclear reactors. The spectrometer is based on the conversion of neutrons impinging on $^6$Li into $\\alpha$ and $t$ whose total energy comprises the initial neutron energy and the reaction $Q$-value. The $^6$LiF layer is sandwiched between two CVD diamond detectors, which measure the two reaction products in coincidence. The spectrometer was calibrated at two neutron energies in well known thermal and 3 MeV neutron fluxes. The measured neutron detection efficiency varies from 4.2$\\times 10^{-4}$ to 3.5$\\times 10^{-8}$ for thermal and 3 MeV neutrons, respectively. These values are in agreement with Geant4 simulations and close to simple estimates based on the knowledge of the $^6$Li(n,$\\alpha$)$t$ cross section. The energy resolution of the spectrometer was found to be better than 100 keV when using 5 m cables between the detector and the preamplifiers.

  13. Compositional terranes on Mercury: Information from fast neutrons

    Science.gov (United States)

    Lawrence, David J.; Peplowski, Patrick N.; Beck, Andrew W.; Feldman, William C.; Frank, Elizabeth A.; McCoy, Timothy J.; Nittler, Larry R.; Solomon, Sean C.

    2017-01-01

    We report measurements of the flux of fast neutrons at Mercury from 20ºS to the north pole. On the basis of neutron transport simulations and remotely sensed elemental compositions, cosmic-ray-induced fast neutrons are shown to provide a measure of average atomic mass, , a result consistent with earlier studies of the Moon and Vesta. The dynamic range of fast neutron flux at Mercury is 3%, which is smaller than the fast-neutron dynamic ranges of 30% and 6% at the Moon and Vesta, respectively. Fast-neutron data delineate compositional terranes on Mercury that are complementary to those identified with X-ray, gamma-ray, and slow-neutron data. Fast neutron measurements confirm the presence of a region with high , relative to the mean for the planet, that coincides with the previously identified high-Mg region and reveal the existence of at least two additional compositional terranes: a low- region within the northern smooth plains and a high- region near the equator centered near 90ºE longitude. Comparison of the fast-neutron map with elemental composition maps show that variations predicted from the combined element maps are not consistent with the measured variations in fast-neutron flux. This lack of consistency could be due to incomplete coverage for some elements or uncertainties in the interpretations of compositional and neutron data. Currently available data and analyses do not provide sufficient constraints to resolve these differences.

  14. Study on spatial resolution of micromegas as a neutron detector under condition of high neutron flux and γ ray background

    Institute of Scientific and Technical Information of China (English)

    WANG Wen-Xin; ZHANG Yi; WANG Ji-Jin; HU Bi-Tao

    2009-01-01

    In this paper Micromegas has been designed to detect neutrons. The simulation of the spatial reso-lution of Micromegas as neutron detector is carried out by GEANT4 toolkit. The neutron track reconstruction method based on the time coincidence technology is employed in the present work. The influence of the flux of incident 14 MeV neutron and high gamma background on the spatial resolution is carefully studied. Our results show that the spatial resolution of the detector is sensitive to the neutron flux, but insensitive to the intensity of γ background if the neutron track reconstruction method proposed by our group is used. The γ insensitivity makes it possible for us to use the Micromegas detector under condition which has high γ-rays background.

  15. Neutron tomography

    Science.gov (United States)

    Crump, James C., III; Richards, Wade J.; Shields, Kevin C.

    1995-07-01

    The McClellan Nuclear Radiation Center's (MNRC) staff in conjunction with a Cooperative Research and Development Agreement (CRDA) with the U.C. Santa Barbara facility has developed a system that can be used for aircraft inspection of jet engine blades. The problem was to develop an inspection system that can detect very low concentrations of hydrogen (i.e., greater than 100 ppm) in metal matricies. Specifically in Titanium alloy jet engine blades. Entrapment and precipitation of hydrogen in metals is an undesirable phenomenon which occurs in many alloys of steel and titanium. In general, metals suffer a loss of mechanical properties after long exposures to hydrogen, especially at high temperatures and pressures, thereby becoming embrittled. Neutron radiography has been used as a nondestructive testing technique for many years. Neutrons, because of their unique interactions with materials, are especially useful in the detection of hydrogen. They have an extremely high interaction cross section for low atomic number nuclei (i.e., hydrogen). Thus hydrogen in a metal matrix can be visualized using neutrons. Traditional radiography is sensitive to the total attenuation integrated over the path of radiation through the material. Increased sensitivity and quantitative cross section resolution can be obtained using three-dimensional volumetric imaging techniques such as tomography. The solution used to solve the problem was to develop a neutron tomography system. The neutron source is the McClellan Nuclear Radiation Center's 1 MW TRIGA reactor. This paper describes the hardware used in the system as well as some of the preliminary results.

  16. Development of the environmental neutron detection system

    CERN Document Server

    Kume, K

    2002-01-01

    Environmental neutron detection system was proposed and developed. The main goal of this system was set to detect fast and thermal neutrons with the identical detectors setup without degraders. This system consists of a sup 1 sup 0 B doped liquid scintillator for n detection and CsI scintillators for simultaneous gamma emission from sup 1 sup 0 B doped in the liquid scintillator after the n capture reaction. The first setup was optimized for the thermal n detection, while the second setup was for the fast n detection. It was shown that the thermal n flux was obtained in the first setup by using the method of the gamma coincidence method with the help of the Monte Carlo calculation. The second setup was designed to improve the detection efficiency for the fast n, and was shown qualitatively that both the pulse shape discrimination and the coincidence methods are efficient. There will be more improvements, particularly for the quantitative discussion.

  17. An Inexpensive Coincidence Circuit for the Pasco Geiger Sensors

    CERN Document Server

    Fichera, F; Librizzi, F; Riggi, F

    2005-01-01

    A simple coincidence circuit was devised to carry out educational coincidence experiments involving the use of Geiger counters. The system was tested by commercially available Geiger sensors from PASCO, and is intended to be used in collaboration with high school students and teachers

  18. Digital gamma-gamma coincidence HPGe system for environmental analysis

    DEFF Research Database (Denmark)

    Markovic, Nikola; Roos, Per; Nielsen, Sven Poul

    2017-01-01

    The performance of a new gamma-gamma coincidence spectrometer system for environmental samples analysis at the Center for Nuclear Technologies of the Technical University of Denmark (DTU) is reported. Nutech Coincidence Low Energy Germanium Sandwich (NUCLeGeS) system consists of two HPGe detector...

  19. Recovery and normalization of triple coincidences in PET

    Energy Technology Data Exchange (ETDEWEB)

    Lage, Eduardo, E-mail: elage@mit.edu; Parot, Vicente; Dave, Shivang R.; Herraiz, Joaquin L. [Madrid-MIT M+Visión Consortium, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Moore, Stephen C.; Sitek, Arkadiusz; Park, Mi-Ae [Division of Nuclear Medicine, Department of Radiology, Harvard Medical School and Brigham and Women’s Hospital, Boston, Massachusetts 02115 (United States); Udías, Jose M. [Grupo de Física Nuclear, Departamento de Física Atómica Molecular y Nuclear, Universidad Complutense de Madrid, CEI Moncloa, Madrid 28040 (Spain); Vaquero, Juan J. [Departamento de Ingeniería Biomédica e Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Leganés 28911 (Spain)

    2015-03-15

    Purpose: Triple coincidences in positron emission tomography (PET) are events in which three γ-rays are detected simultaneously. These events, though potentially useful for enhancing the sensitivity of PET scanners, are discarded or processed without special consideration in current systems, because there is not a clear criterion for assigning them to a unique line-of-response (LOR). Methods proposed for recovering such events usually rely on the use of highly specialized detection systems, hampering general adoption, and/or are based on Compton-scatter kinematics and, consequently, are limited in accuracy by the energy resolution of standard PET detectors. In this work, the authors propose a simple and general solution for recovering triple coincidences, which does not require specialized detectors or additional energy resolution requirements. Methods: To recover triple coincidences, the authors’ method distributes such events among their possible LORs using the relative proportions of double coincidences in these LORs. The authors show analytically that this assignment scheme represents the maximum-likelihood solution for the triple-coincidence distribution problem. The PET component of a preclinical PET/CT scanner was adapted to enable the acquisition and processing of triple coincidences. Since the efficiencies for detecting double and triple events were found to be different throughout the scanner field-of-view, a normalization procedure specific for triple coincidences was also developed. The effect of including triple coincidences using their method was compared against the cases of equally weighting the triples among their possible LORs and discarding all the triple events. The authors used as figures of merit for this comparison sensitivity, noise-equivalent count (NEC) rates and image quality calculated as described in the NEMA NU-4 protocol for the assessment of preclinical PET scanners. Results: The addition of triple-coincidence events with the

  20. Dose spectra from energetic particles and neutrons

    Science.gov (United States)

    Schwadron, Nathan; Bancroft, Chris; Bloser, Peter; Legere, Jason; Ryan, James; Smith, Sonya; Spence, Harlan; Mazur, Joe; Zeitlin, Cary

    2013-10-01

    spectra from energetic particles and neutrons (DoSEN) are an early-stage space technology research project that combines two advanced complementary radiation detection concepts with fundamental advantages over traditional dosimetry. DoSEN measures not only the energy but also the charge distribution (including neutrons) of energetic particles that affect human (and robotic) health in a way not presently possible with current dosimeters. For heavy ions and protons, DoSEN provides a direct measurement of the lineal energy transfer (LET) spectra behind shielding material. For LET measurements, DoSEN contains stacks of thin-thick Si detectors similar in design to those used for the Cosmic Ray Telescope for the Effects of Radiation. With LET spectra, we can now directly break down the observed spectrum of radiation into its constituent heavy-ion components and through biologically based quality factors that provide not only doses and dose rates but also dose equivalents, associated rates, and even organ doses. DoSEN also measures neutrons from 10 to 100 MeV, which requires enough sensitive mass to fully absorb recoil particles that the neutrons produce. DoSEN develops the new concept of combining these independent measurements and using the coincidence of LET measurements and neutron detection to significantly reduce backgrounds in each measurement. The background suppression through the use of coincidence allows for significant reductions in size, mass, and power needed to provide measurements of dose, neutron dose, dose equivalents, LET spectra, and organ doses. Thus, we introduce the DoSEN concept: a promising low-mass instrument that detects the full spectrum of energetic particles, heavy ions, and neutrons to determine biological impact of radiation in space.

  1. Mean and variance of coincidence counting with deadtime

    CERN Document Server

    Yu, D F

    2002-01-01

    We analyze the first and second moments of the coincidence-counting process for a system affected by paralyzable (extendable) deadtime with (possibly unequal) deadtimes in each singles channel. We consider both 'accidental' and 'genuine' coincidences, and derive exact analytical expressions for the first and second moments of the number of recorded coincidence events under various scenarios. The results include an exact form for the coincidence rate under the combined effects of decay, background, and deadtime. The analysis confirms that coincidence counts are not exactly Poisson, but suggests that the Poisson statistical model that is used for positron emission tomography image reconstruction is a reasonable approximation since the mean and variance are nearly equal.

  2. The effect of albedo neutrons on the neutron multiplication of small plutonium oxide samples in a PNCC chamber

    CERN Document Server

    Bourva, L C A; Weaver, D R

    2002-01-01

    This paper describes how to evaluate the effect of neutrons reflected from parts of a passive neutron coincidence chamber on the neutron leakage self-multiplication, M sub L , of a fissile sample. It is shown that albedo neutrons contribute, in the case of small plutonium bearing samples, to a significant part of M sub L , and that their effect has to be taken into account in the relationship between the measured coincidence count rates and the sup 2 sup 4 sup 0 Pu effective mass of the sample. A simple one-interaction model has been used to write the balance of neutron gains and losses in the material when exposed to the re-entrant neutron flux. The energy and intensity profiles of the re-entrant flux have been parameterised using Monte Carlo MCNP sup T sup M calculations. This technique has been implemented for the On Site Laboratory neutron/gamma counter within the existing MEPL 1.0 code for the determination of the neutron leakage self-multiplication. Benchmark tests of the resulting MEPL 2.0 code with MC...

  3. Roles for Coincidence Detection in Coding Amplitude-Modulated Sounds.

    Directory of Open Access Journals (Sweden)

    Go Ashida

    2016-06-01

    Full Text Available Many sensory neurons encode temporal information by detecting coincident arrivals of synaptic inputs. In the mammalian auditory brainstem, binaural neurons of the medial superior olive (MSO are known to act as coincidence detectors, whereas in the lateral superior olive (LSO roles of coincidence detection have remained unclear. LSO neurons receive excitatory and inhibitory inputs driven by ipsilateral and contralateral acoustic stimuli, respectively, and vary their output spike rates according to interaural level differences. In addition, LSO neurons are also sensitive to binaural phase differences of low-frequency tones and envelopes of amplitude-modulated (AM sounds. Previous physiological recordings in vivo found considerable variations in monaural AM-tuning across neurons. To investigate the underlying mechanisms of the observed temporal tuning properties of LSO and their sources of variability, we used a simple coincidence counting model and examined how specific parameters of coincidence detection affect monaural and binaural AM coding. Spike rates and phase-locking of evoked excitatory and spontaneous inhibitory inputs had only minor effects on LSO output to monaural AM inputs. In contrast, the coincidence threshold of the model neuron affected both the overall spike rates and the half-peak positions of the AM-tuning curve, whereas the width of the coincidence window merely influenced the output spike rates. The duration of the refractory period affected only the low-frequency portion of the monaural AM-tuning curve. Unlike monaural AM coding, temporal factors, such as the coincidence window and the effective duration of inhibition, played a major role in determining the trough positions of simulated binaural phase-response curves. In addition, empirically-observed level-dependence of binaural phase-coding was reproduced in the framework of our minimalistic coincidence counting model. These modeling results suggest that coincidence

  4. Computational program to neutron flux calculation; Programa computacional para calculo de fluxo de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Maria Ines Silvani; Furieri, Rosanne Cefaly de Aranda Amado [Instituto de Engenharia Nuclear (IEN), Rio de Janeiro, RJ (Brazil)

    2000-07-01

    The absolute value of the neutron flux is of paramount importance in reactor physics and other application on the nuclear field. Due to several corrections which should be done, such as radioactive decay of the produced nuclides, normalization factors between different irradiations, neutron spectrum perturbation, cross section behaviour and growing of the reactor power, among other factors, make the calculation of the neutron flux very cumbersome. the software FLUXO was developed to overcome these inconveniences. It is programmed in FORTRAN language, and was written to calculate the absolute flux of thermal, epithermal and fast neutrons, through the foil activation technique. The magnitude of this activation can be measured by a 4{pi} {beta}-{gamma} coincidence measurement or by gamma spectroscopy alone. The software calculates as well, the absolute activity of radioactive sources, and reactor-irradiated samples. (author)

  5. Neutron reflectometry

    DEFF Research Database (Denmark)

    Klösgen-Buchkremer, Beate Maria

    2014-01-01

    to hundreds of nanometers. Thickness resolution for flat surfaces is in the range of few Ǻngstrøm, and as a peculiar benefit, the presence and properties of buried interfaces are accessible. Focus here will be on neutron reflectometry, a technique that is unique in applications involving composite organic...... of desired information. In the course, an introduction into the method and an overview on selected instruments at large scale facilities will be presented. Examples will be given that illustrate the potential of the method, mostly based on organic films. Results from the investigation of layered films...... and the detection on nanoscopic roughnesses will be shown. The potential of neutron reflectometry is not only of academic origin. It may turn out to be useful in the design and development of new functional materials even though it will never develop into a standard method to be applied in the product control...

  6. Measurement of accidental coincidences for higher activity sources

    CERN Document Server

    Yull Hwang, H; Jae-Oh, P; Man-Lee, J; Kie-Lee, M

    1999-01-01

    The multi-channel time-scaling (MCTS) technique has been applied for the measurement of accidental coincidences for the cases of higher activity samples in beta-gamma coincidence counting. Two beta samples of sup 1 sup 3 sup 4 Cs were prepared and the nominal activities observed in the beta counter were about 7000 and 11000 s sup - sup 1 , respectively. The obtained true coincidence rates are independent of resolving times and dead times. They are compared with those calculated from the mathematical model derived by Cox and Isham.

  7. Why Do Deconfinement and Chiral Restoration Coincide at High Temperature?

    Institute of Scientific and Technical Information of China (English)

    杨树; 郭华; 赵恩广; 吕晓夫

    2004-01-01

    The global colour model in free space is extended to finite temperature to study the deconfinement and chiral phase transitions at high temperature T and zero chemical potential in the mean field approximation. Both possibilities of coincidence and non-coincidence of the two distinct phase transitions are found when the model parameters are varied in a certain range. The underlying mechanisms of the coincidence and noncoincidence are analysed and discussed. The validity of the T-dependent model propagator as the input is also discussed.

  8. Neutron pileup algorithms for multiplicity counters

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Sean M.; Stave, Sean; Lintereur, Azaree; Siciliano, Edward; Kouzes, Richard; Bliss, Mary

    2015-06-01

    Abstract The shortage of helium-3 (3He) has created a need to identify alternative neutron detection options for a variety of nuclear nonproliferation applications. One application that may be affected by 3He replacement technology is that of mass accountancy for safeguards, which utilizes coincidence and multiplicity counters to verify special nuclear material declarations. The use of neutron scintillation materials, such as LiF-ZnS sheets, as an alternative to 3He proportional tubes in multiplicity counters requires novel techniques for Pulse Shape Discrimination to distinguish between neutrons and gamma rays. These techniques must work under high count rates, as the maximum momentary rate for incoming neutrons from multiplicity events can be quite large. We have created a fast and accurate neutron discrimination algorithm based on time window filtering and signature comparison that can operate quickly on data with high degrees of gamma ray and neutron pileup. This algorithm is evaluated for its capability to separate signals as the pileup rate increases, and the possibility for implementation on fast hardware (e.g., FPGA hardware) for real-time operation is explored.

  9. Neutron pileup algorithms for multiplicity counters

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Sean M., E-mail: sean.robinson@pnnl.gov [Pacific Northwest National Laboratory, Seattle, WA 98109 (United States); Stave, Sean; Lintereur, Azaree; Siciliano, Edward; Kouzes, Richard; Bliss, Mary [Pacific Northwest National Laboratory, Richland, WA 99352 (United States)

    2015-06-01

    The shortage of helium-3 ({sup 3}He) has created a need to identify alternative neutron detection options for a variety of nuclear nonproliferation applications. One application that may be affected by {sup 3}He replacement technology is that of mass accountancy for safeguards, which utilizes coincidence and multiplicity counters to verify special nuclear material declarations. The use of neutron scintillation materials, such as LiF–ZnS sheets, as an alternative to {sup 3}He proportional tubes in multiplicity counters requires novel techniques for Pulse Shape Discrimination to distinguish between neutrons and gamma rays. These techniques must work under high count rates, as the maximum momentary rate for incoming neutrons from multiplicity events can be quite large. We have created a fast and accurate neutron discrimination algorithm based on time window filtering and signature comparison that can operate quickly on data with high degrees of gamma ray and neutron pileup. This algorithm is evaluated for its capability to separate signals as the pileup rate increases, and the possibility for implementation on fast hardware (e.g., FPGA hardware) for real-time operation is explored.

  10. Spallation Neutron Source (SNS)

    Data.gov (United States)

    Federal Laboratory Consortium — The SNS at Oak Ridge National Laboratory is a next-generation spallation neutron source for neutron scattering that is currently the most powerful neutron source in...

  11. Neutron knockout of 12Be populating neutron-unbound states in 11Be

    CERN Document Server

    Peters, William A; Brown, B A; Brown, J; DeYoung, P A; Finck, J E; Frank, N; Jones, K L; Lecouey, J -L; Luther, B; Peaslee, G F; Rogers, W F; Schiller, A; Thoennessen, M; Tostevin, J A; Yoneda, K

    2011-01-01

    Neutron-unbound resonant states of 11Be were populated in neutron knock-out reactions from 12Be and identified by 10Be-n coincidence measurements. A resonance in the decay-energy spectrum at 80(2) keV was attributed to a highly excited unbound state in 11Be at 3.949(2) MeV decaying to the 2+ excited state in 10Be. A knockout cross section of 15(3) mb was inferred for this 3.949(2) MeV state suggesting a spectroscopic factor near unity for this 0p3/2- level, consistent with the detailed shell model calculations.

  12. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

  13. 48-channel coincidence counting system for multiphoton experiment

    Science.gov (United States)

    Zhang, Chen; Li, Wei; Hu, Yi; Yang, Tao; Jin, Ge; Jiang, Xiao

    2016-11-01

    In this paper, we demonstrate a coincidence counting system with 48 input channels which is aimed to count all coincidence events, up to 531 441 kinds, in a multiphoton experiment. Using the dynamic delay adjusting inside the Field Programmable Gate Array, the alignment of photon signals of 48 channels is achieved. After the alignment, clock phase shifting is used to sample signal pulses. Logic constraints are used to stabilize the pulse width. The coincidence counting data stored in a 1G bit external random access memory will be sent to the computer to analyze the amount of 2-, 3-, 4-, 5-, and 6-fold coincidence events. This system is designed for multiphoton entanglement experiments with multiple degrees of freedom of photons.

  14. A coincidence theorem for holomorphic maps to G/P

    OpenAIRE

    Sankaran, Parameswaran

    2002-01-01

    We show that any two holomorhpic maps, not both of which are constant, from a generalized Hopf manifold to its base must have a coincidence. We prove a similar result for holomorphic maps from a generalized Calabi-Eckmann manifold.

  15. A digital coincidence measurement system using FPGA techniques

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Fengming; Hsieh, S.C.; Yen, W.W. [Department of Engineering and System Science, National Tsing Hua University, Hsinchu, 30043, Taiwan (China); Chou, H.P., E-mail: hpc@ess.nthu.edu.tw [Department of Engineering and System Science, National Tsing Hua University, Hsinchu, 30043, Taiwan (China)

    2011-10-01

    A field programmable gate array (FPGA) based digital coincidence system has been developed to use with NaI scintillators for field applications. The analog output signal from the photomultiplier anode is directly transferred into digital signals by pulse height for pulse width conversion. The digital signal contains the energy and timing information of the radiation events. The pulse width is then measured by a vernier type of time-to-digital converter (TDC). The timing information of radiation events is recorded and analyzed by a coincidence unit. Both the TDC unit and the coincidence unit are implemented using a commercial available FPGA board. The measured data is then sent to a personal computer for spectrum display. Efficiency as well as energy calibration has been performed. The system showed a timing resolution about 13 ns and an energy resolution of 12% for 0.511 MeV annihilation gammas; it also successfully demonstrated the background rejection ability through coincidence measurement.

  16. Glycinergic inhibition tunes coincidence detection in the auditory brainstem.

    Science.gov (United States)

    Myoga, Michael H; Lehnert, Simon; Leibold, Christian; Felmy, Felix; Grothe, Benedikt

    2014-05-07

    Neurons in the medial superior olive (MSO) detect microsecond differences in the arrival time of sounds between the ears (interaural time differences or ITDs), a crucial binaural cue for sound localization. Synaptic inhibition has been implicated in tuning ITD sensitivity, but the cellular mechanisms underlying its influence on coincidence detection are debated. Here we determine the impact of inhibition on coincidence detection in adult Mongolian gerbil MSO brain slices by testing precise temporal integration of measured synaptic responses using conductance-clamp. We find that inhibition dynamically shifts the peak timing of excitation, depending on its relative arrival time, which in turn modulates the timing of best coincidence detection. Inhibitory control of coincidence detection timing is consistent with the diversity of ITD functions observed in vivo and is robust under physiologically relevant conditions. Our results provide strong evidence that temporal interactions between excitation and inhibition on microsecond timescales are critical for binaural processing.

  17. New class of neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Czirr, J.B.

    1997-09-01

    An optimized neutron scattering instrument design must include all significant components, including the detector. For example, useful beam intensity is limited by detector dead time; detector pixel size determines the optimum beam diameter, sample size, and sample to detector distance; and detector efficiency vs. wavelength determines the available energy range. As an example of the next generation of detectors that could affect overall instrumentation design, we will describe a new scintillator material that is potentially superior to currently available scintillators. We have grown and tested several small, single crystal scintillators based upon the general class of cerium-activated lithium lanthanide borates. The outstanding characteristic of these materials is the high scintillation efficiency-as much as five times that of Li-glass scintillators. This increase in light output permits the practical use of the exothermic B (n, alpha) reaction for low energy neutron detection. This reaction provides a four-fold increase in capture cross section relative to the Li (n, alpha) reaction, and the intriguing possibility of demanding a charged-particle/gamma ray coincidence to reduce background detection rates. These new materials will be useful in the thermal and epithermal energy ran at reactors and pulsed neutron sources.

  18. RNA Editing in Plant Mitochondria

    Science.gov (United States)

    Hiesel, Rudolf; Wissinger, Bernd; Schuster, Wolfgang; Brennicke, Axel

    1989-12-01

    Comparative sequence analysis of genomic and complementary DNA clones from several mitochondrial genes in the higher plant Oenothera revealed nucleotide sequence divergences between the genomic and the messenger RNA-derived sequences. These sequence alterations could be most easily explained by specific post-transcriptional nucleotide modifications. Most of the nucleotide exchanges in coding regions lead to altered codons in the mRNA that specify amino acids better conserved in evolution than those encoded by the genomic DNA. Several instances show that the genomic arginine codon CGG is edited in the mRNA to the tryptophan codon TGG in amino acid positions that are highly conserved as tryptophan in the homologous proteins of other species. This editing suggests that the standard genetic code is used in plant mitochondria and resolves the frequent coincidence of CGG codons and tryptophan in different plant species. The apparently frequent and non-species-specific equivalency of CGG and TGG codons in particular suggests that RNA editing is a common feature of all higher plant mitochondria.

  19. Neutron Therapy Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Neutron Therapy Facility provides a moderate intensity, broad energy spectrum neutron beam that can be used for short term irradiations for radiobiology (cells)...

  20. Coincidence rotations of the root lattice $A_4$

    CERN Document Server

    Baake, Michael; Heuer, Manuela; Zeiner, Peter

    2007-01-01

    The coincidence site lattices of the root lattice $A_4$ are considered, and the statistics of the corresponding coincidence rotations according to their indices is expressed in terms of a Dirichlet series generating function. This is possible via an embedding of $A_4$ into the icosian ring with its rich arithmetic structure, which recently (arXiv:math.MG/0702448) led to the classification of the similar sublattices of $A_4$.

  1. Quasifree photoproduction of eta mesons off the neutron

    NARCIS (Netherlands)

    Jaegle, I.; Mertens, T.; Anisovich, A. V.; Bacelar, J. C. S.; Bantes, B.; Bartholomy, O.; Bayadilov, D.; Beck, R.; Beloglazov, Y. A.; Castelijns, R.; Crede, V.; Dutz, H.; Ehmanns, A.; Elsner, D.; Essig, K.; Ewald, R.; Fabry, I.; Fuchs, M.; Funke, Ch.; Gothe, R.; Gregor, R.; Gridnev, A. B.; Gutz, E.; Hoeffgen, S.; Hoffmeister, P.; Horn, I.; Junkersfeld, J.; Kalinowsky, H.; Kammer, S.; Kleber, V.; Klein, Frank; Klein, Friedrich; Klempt, E.; Konrad, M.; Kotulla, M.; Krusche, B.; Lang, M.; Langheinrich, J.; Loehner, H.; Lopatin, I. V.; Lotz, J.; Lugert, S.; Menze, D.; Messchendorp, J. G.; Metag, V.; Morales, C.; Nanova, M.; Nikonov, V. A.; Novinski, D.; Novotny, R.; Ostrick, M.; Pant, L. M.; van Pee, H.; Pfeiffer, M.; Radkov, A.; Roy, A.; Sarantsev, A. V.; Schadmand, S.; Schmidt, C.; Schmieden, H.; Schoch, B.; Shende, S. V.; Sokhoyan, V.; Suele, A.; Sumachev, V. V.; Szczepanek, T.; Thoma, U.; Trnka, D.; Varma, R.; Walther, D.; Weinheimer, Ch.; Wendel, Ch.

    2008-01-01

    Quasifree photoproduction of eta mesons off nucleons bound in the deuteron has been measured with the CBELSA/TAPS detector for incident photon energies up to 2.5 GeV at the Bonn ELSA accelerator. The eta mesons have been detected in coincidence with recoil protons and recoil neutrons, which allows a

  2. Study of an integrated electronic monitor for neutron beams

    Energy Technology Data Exchange (ETDEWEB)

    Barelaud, B.; Nexon-Mokhtari, F.; Barrau, C.; Decossac, J.L.; Vareille, J.C. [Limoges Univ., 87 (France); Sarrabayrouse, G. [Centre National de la Recherche Scientifique (CNRS), 31 - Toulouse (France). Lab. d`Automatique et d`Analyse des Systemes

    1994-12-31

    Many neutron beams monitors in 10 keV - 50 keV range are perturbed by gamma radiation impact. This new monitor uses two silicon (junction) diodes operating coincidence detection, combined with an electronic threshold to eliminate gamma background noise. The results and analyses presented here only concern feasibility studies. (D.L.). 11 refs.

  3. Shape Isomer in 236U Populated by Thermal Neutron Capture

    DEFF Research Database (Denmark)

    Andersen, Verner; Christensen, Carl Jørgen; Borggreen, J.

    1976-01-01

    The 116 ns shape isomer in 236U was populated by thermal neutron capture. Conversion electrons and X-rays were detected simultaneously in delayed coincidence with fission. The ratio of delayed to prompt fission was measured with the result, σIIf/σf = (1.0±0.2) × 10−5. A branching of the isomeric...

  4. Two-neutron decay of excited states of 11Li

    Science.gov (United States)

    Smith, Jenna; MoNA Collaboration

    2013-10-01

    One prominent example of a Borromean nucleus is the two-neutron halo nucleus, 11Li. All excited states of this nucleus are unbound to two-neutron decay. Many theories propose that the two valence neutrons exhibit dineutron behavior in the ground state, but it is unclear what effect such a structure would have on the decay of the excited states. We have recently completed an experiment designed to study the decay of one of these excited states. Unbound 11Li was populated via a two-proton knockout from 13B. The two emitted neutrons were detected with the Modular Neutron Array (MoNA) and the Large-area multi-Institutional Scintillator Array (LISA) in coincidence with the daughter fragment, 9Li. Preliminary results will be discussed.

  5. Electron-ion-ion coincidence experiments for photofragmentation of polyatomic molecules using pulsed electric fields: treatment of random coincidences

    CERN Document Server

    Pruemper, G

    2007-01-01

    In molecular photofragmentation processes by soft X-rays, a number of ionic fragments can be produced, each having a different abundance and correlation with the emitted electron kinetic energy. For investigating these fragmentation processes, electron-ion and electron-ion-ion coincidence experiments, in which the kinetic energy of electrons are analyzed using an electrostatic analyzer while the mass of the ions is analyzed using a pulsed electric field, are very powerful. For such measurements, however, the contribution of random coincidences is substantial and affects the data in a non-trivial way. Simple intuitive subtraction methods cannot be applied. In the present paper, we describe these electron-ion and electron-ion-ion coincidence experiments together with a subtraction method for the contribution from random coincidences. We provide a comprehensive set of equations for the data treatment, including equations for the calculation of error-bars. We demonstrate the method by applying it to the fragmenta...

  6. Time reversal invariance in polarized neutron decay

    Energy Technology Data Exchange (ETDEWEB)

    Wasserman, E.G.

    1994-03-01

    An experiment to measure the time reversal invariance violating (T-violating) triple correlation (D) in the decay of free polarized neutrons has been developed. The detector design incorporates a detector geometry that provides a significant improvement in the sensitivity over that used in the most sensitive of previous experiments. A prototype detector was tested in measurements with a cold neutron beam. Data resulting from the tests are presented. A detailed calculation of systematic effects has been performed and new diagnostic techniques that allow these effects to be measured have been developed. As the result of this work, a new experiment is under way that will improve the sensitivity to D to 3 {times} 10{sup {minus}4} or better. With higher neutron flux a statistical sensitivity of the order 3 {times} 10{sup {minus}5} is ultimately expected. The decay of free polarized neutrons (n {yields} p + e + {bar v}{sub e}) is used to search for T-violation by measuring the triple correlation of the neutron spin polarization, and the electron and proton momenta ({sigma}{sub n} {center_dot} p{sub p} {times} p{sub e}). This correlation changes sign under reversal of the motion. Since final state effects in neutron decay are small, a nonzero coefficient, D, of this correlation indicates the violation of time reversal invariance. D is measured by comparing the numbers of coincidences in electron and proton detectors arranged symmetrically about a longitudinally polarized neutron beam. Particular care must be taken to eliminate residual asymmetries in the detectors or beam as these can lead to significant false effects. The Standard Model predicts negligible T-violating effects in neutron decay. Extensions to the Standard Model include new interactions some of which include CP-violating components. Some of these make first order contributions to D.

  7. Edge localized modes of cold neutrons in periodic condensed media

    Science.gov (United States)

    Belyakov, V. A.

    2017-06-01

    It is found that for certain energies of discreet cold neutrons, quasi-stationary eigen solutions of the corresponding Schrodinger equation, which are localized in the layer of a periodic medium, exist. The localization time of these solutions is strongly dependent on the layer thickness, being finite for a finite layer thickness and increasing indefinitely upon a infinite growth of the layer thickness as the third power of the layer thickness. The problem has been solved in the two-wave approximation of the dynamic diffraction theory for the neutron propagation direction coinciding with the periodicity axes (normal incidence of the neutron beam on the layer). The expressions for neutron eigenwave functions in a periodic medium, the reflection and transmission coefficients, and the neutron wavefunction in the layer as a function of the neutron energy incident on the layer have been determined. It turns out that for the certain discrete neutron energies, the amplitudes of the neutron wavefunction in the layer reach sharp maxima. The corresponding energies are just outside of the neutron stop band (energies forbidden for neutron propagation in the layer) and determine the energies of neutron edge modes (NEMs) localized in the layer, which are direct analogs of the optical edge modes for photonic crystals. The dispersion equation for the localized neutron edge modes has been obtained and analytically solved for the case of thick layers. A rough estimate for the localization length L is L ( db N)-1, where b is the neutron scattering length, d is the crystal period, and N is the density of nuclei in the crystal. The estimates of the localized thermal neutron lifetime show that acheaving of a lifetime close to the free neutron lifetime seems nonrealistic due to absorption of thermal neutrons and requires a perfect large size crystal. Nevertheless, acheaving the localized neutron lifetime exceeding by 104 times the neutron time of flight through the layer appears as

  8. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: Neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

  9. Neutron Capture Nucleosynthesis

    CERN Document Server

    Kiss, Miklos

    2016-01-01

    Heavy elements (beyond iron) are formed in neutron capture nucleosynthesis processes. We have proposed a simple unified model to investigate the neutron capture nucleosynthesis in arbitrary neutron density environment. We have also investigated what neutron density is required to reproduce the measured abundance of nuclei assuming equilibrium processes. We found both of these that the medium neutron density has a particularly important role at neutron capture nucleosynthesis. About these results most of the nuclei can formed at medium neutron capture density environment e.g. in some kind of AGB stars. Besides these observations our model is capable to use educational purpose.

  10. Nuclear reactor neutron shielding

    Energy Technology Data Exchange (ETDEWEB)

    Speaker, Daniel P; Neeley, Gary W; Inman, James B

    2017-09-12

    A nuclear reactor includes a reactor pressure vessel and a nuclear reactor core comprising fissile material disposed in a lower portion of the reactor pressure vessel. The lower portion of the reactor pressure vessel is disposed in a reactor cavity. An annular neutron stop is located at an elevation above the uppermost elevation of the nuclear reactor core. The annular neutron stop comprises neutron absorbing material filling an annular gap between the reactor pressure vessel and the wall of the reactor cavity. The annular neutron stop may comprise an outer neutron stop ring attached to the wall of the reactor cavity, and an inner neutron stop ring attached to the reactor pressure vessel. An excore instrument guide tube penetrates through the annular neutron stop, and a neutron plug comprising neutron absorbing material is disposed in the tube at the penetration through the neutron stop.

  11. Control of time stability of scintillation spectrometer of delayed coincidences

    CERN Document Server

    Morozov, V A

    2002-01-01

    Paper describes a system to control time stability of a two-detector plastic scintillation spectrometer of three-dimensional coincides. A two-reference control system incorporates a light guide base delay optical line, two light diodes and a two-channel generator of nanosecond pulses. A distinguishing feature of the design system is application of one delay line to form both advance and delay time signal as to the real coincidences in the studied radioactive source. The designed system of control enables to measure periods of half-decay of nuclei excited states within 40-100 ns range ensuring control of position of coincidence curve gravity centers within 4 ps limits

  12. CDL, a Precise, Low-Cost Coincidence Detector Latch

    Directory of Open Access Journals (Sweden)

    Ralf Joost

    2015-12-01

    Full Text Available The electronic detection of the coincidence of two events is still a key ingredient for high-performance applications, such as Positron Emission Tomography and Quantum Optics. Such applications are demanding, since the precision of their calculations and thus their conclusions directly depend on the duration of the interval in which two events are considered coincidental. This paper proposes a new circuitry, called coincidence detector latch (CDL, which is derived from standard RS latches. The CDL has the following advantages: low complexity, fully synthesizable, and high scalability. Even in its simple implementation, it achieves a coincidence window width as short as 115 ps, which is more than 10 times better than that reported by recent research.

  13. Implications on the cosmic coincidence by a dynamical extrinsic curvature

    CERN Document Server

    Capistrano, A J S

    2015-01-01

    In this work, we apply the smooth deformation concept in order to obtain a modification of Friedmann equations. It is shown that the cosmic coincidence can be at least alleviated using the dynamical properties of the extrinsic curvature. We investigate the transition from nucleosynthesis to the coincidence era obtaining a very small variation of the ratio $r=\\frac{\\rho_{m}}{\\rho_{ext}}$, that compares the matter energy density to extrinsic energy density, compatible with the known behavior of the deceleration parameter. We also show that the calculated "equivalence" redshift matches the transition redshift from a deceleration to accelerated phase and the coincidence ceases to be. The dynamics on $r$ is also studied based on Hubble parameter observations as the latest Baryons Acoustic Oscillations/Cosmic Microwave Background Radiation (BAO/CMBR) + SNIa.

  14. The ZEPLIN-III Anti-Coincidence Veto Detector

    CERN Document Server

    Akimov, D Yu; Barnes, E J; Belov, V A; Burenkov, A A; Chepel, V; Currie, A; Edwards, B; Francis, V; Ghag, C; Hollingsworth, A; Horn, M; Kalmus, G E; Kobyakin, A S; Kovalenko, A G; Lebedenko, V N; Lindote, A; Lopes, M I; Lüscher, R; Lyons, K; Majewski, P; Murphy, A St J; Neves, F; Paling, S M; da Cunha, J Pinto; Preece, R; Quenby, J J; Reichhart, L; Scovell, P R; Solovov, V N; Smith, N J T; Smith, P F; Stekhanov, V N; Sumner, T J; Taylor, R; Thorne, C; Walker, R J

    2010-01-01

    The design, optimisation and construction of an anti-coincidence veto detector to complement the ZEPLIN-III direct dark matter search instrument is described. One tonne of plastic scintillator is arranged into 52 bars individually read out by photomultipliers and coupled to a gadolinium-loaded passive polypropylene shield. Particular attention has been paid to radiological content. The overall aim has been to achieve a veto detector of low threshold and high efficiency without the creation of additional background in ZEPLIN-III, all at a reasonable cost. Extensive experimental measurements of the components have been made, including radioactivity levels and performance characteristics. These have been used to inform a complete end-to-end Monte Carlo simulation that has then been used to calculate the expected performance of the new instrument, both operating alone and as an anti-coincidence detector for ZEPLIN-III. The veto device will be capable of rejecting over 65% of coincident nuclear recoil events from ...

  15. Ground water and snow sensor based on directional detection of cosmogenic neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, Robert Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Marleau, Peter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Griffin, Patrick J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2011-06-01

    A fast neutron detector is being developed to measure the cosmic ray neutron flux in order to measure soil moisture. Soil that is saturated with water has an enhanced ability to moderate fast neutrons, removing them from the backscatter spectrum. The detector is a two-element, liquid scintillator detector. The choice of liquid scintillator allows rejection of gamma background contamination from the desired neutron signal. This enhances the ability to reconstruct the energy and direction of a coincident neutron event. The ability to image on an event-by-event basis allows the detector to selectively scan the neutron flux as a function of distance from the detector. Calibrations, simulations, and optimization have been completed to understand the detector response to neutron sources at variable distances and directions. This has been applied to laboratory background measurements in preparation for outdoor field tests.

  16. Prompt fission neutron investigation in 235U(nth,f) reaction

    Science.gov (United States)

    Zeynalov, Shakir; Sedyshev, Pavel; Shvetsov, Valery; Sidorova, Olga

    2017-09-01

    The prompt neutron emission in thermal neutron induced fission of 235U has been investigated applying digital signal electronics. The goal was to compare the results of this digital data acquisition and digital signal processing analysis to the results of the pioneering work of Apalin et al. Using a twin Frisch grid ionization chamber for the fission fragment detection and a NE213 equivalent neutron detector in total about 106 neutron coincidences have been registered. The fission fragment kinetic energy, mass and angular distribution has been investigated along with prompt neutron time of flight and pulse shape using a six channel synchronous waveform digitizer with sampling frequency of 250 MHz and 12 bit resolution. The signals have been analyzed using digital pulse processing algorithms, developed by authors. The thermal neutron beam was transported from the IBR-2 reactor to the target with bent mirror neutron guide.

  17. Non-coincident multi-wavelength emission absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Baumann, L.E.

    1995-02-01

    An analysis is presented of the effect of noncoincident sampling on the measurement of atomic number density and temperature by multiwavelength emission absorption. The assumption is made that the two signals, emission and transmitted lamp, are time resolved but not coincident. The analysis demonstrates the validity of averages of such measurements despite fluctuations in temperature and optical depth. At potassium-seeded MHD conditions, the fluctuations introduce additional uncertainty into measurements of potassium atom number density and temperature but do not significantly bias the average results. Experimental measurements in the CFFF aerodynamic duct with coincident and noncoincident sampling support the analysis.

  18. Optical Bell-state analysis in the coincidence basis

    CERN Document Server

    Walborn, S P; Pádua, S; Monken, C H

    2003-01-01

    Many quantum information protocols require a Bell-state measurement of entangled systems. Most optical Bell-state measurements utilize two-photon interference at a beam splitter. By creating polarization-entangled photons with spontaneous parametric down-conversion using a first-order Hermite-Gaussian pump beam, we invert the usual interference behavior and perform an incomplete Bell-state measurement in the coincidence basis. We discuss the possibility of a complete Bell-state measurement in the coincidence basis using hyperentangled states [Phys. Rev. A, \\textbf{58}, R2623 (1998)].

  19. Weapons Neutron Research Facility (WNR)

    Data.gov (United States)

    Federal Laboratory Consortium — The Weapons Neutron Research Facility (WNR) provides neutron and proton beams for basic, applied, and defense-related research. Neutron beams with energies ranging...

  20. ATLAS-TPX: a two-layer pixel detector setup for neutron detection and radiation field characterization

    Science.gov (United States)

    Bergmann, B.; Caicedo, I.; Leroy, C.; Pospisil, S.; Vykydal, Z.

    2016-10-01

    A two-layer pixel detector setup (ATLAS-TPX), designed for thermal and fast neutron detection and radiation field characterization is presented. It consists of two segmented silicon detectors (256 × 256 pixels, pixel pitch 55 μm, thicknesses 300 μm and 500 μm) facing each other. To enhance the neutron detection efficiency a set of converter layers is inserted in between these detectors. The pixelation and the two-layer design allow a discrimination of neutrons against γs by pattern recognition and against charged particles by using the coincidence and anticoincidence information. The neutron conversion and detection efficiencies are measured in a thermal neutron field and fast neutron fields with energies up to 600 MeV. A Geant4 simulation model is presented, which is validated against the measured detector responses. The reliability of the coincidence and anticoincidence technique is demonstrated and possible applications of the detector setup are briefly outlined.

  1. Inelastic scattering of fast neutrons on Fe-56; Inelastische Streuung schneller Neutronen an {sup 56}Fe

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, Roland

    2014-11-24

    The relevant reaction cross sections for the nuclear transmutation will be measured at the neutron flight time facility nELBE in Dresden-Rossendorf. Transmutation by fast neutron irradiation is supposed to reduce the radiotoxicity of high-level radioactive wastes. The thesis is aimed to measure the inelastic neutron scattering cross sections of Fe-56 using a new double flight-time method. With combined plastic and BaF2 scintillation detectors for the first time the emitted neutrons and photons are observed in coincidence.

  2. Study of multi-neutron emission in the $\\beta$-decay of $^{11}$Li

    CERN Multimedia

    A new investigation of neutron emission in the $\\beta$-decay of $^{11}$Li is proposed. The principal goal of this study will be to directly measure, for the first time for any system, two $\\beta$-delayed neutrons in coincidence and determine the energy and angular correlations. This will be possible using liquid scintillator detectors, capable of distinguishing between neutrons and ambient $\\gamma$ and cosmic-rays, coupled to a new digital electronics and acquisition system. In parallel, a considerably more refined picture of the single-neutron emission will be obtained.

  3. Development of Simultaneous Beta-and-Coincidence-Gamma Imager for Plant Imaging Research

    Energy Technology Data Exchange (ETDEWEB)

    Tai, Yuan-Chuan [Washington Univ., St. Louis, MO (United States). School of Medicine

    2016-09-30

    The goal of this project is to develop a novel imaging system that can simultaneously acquire beta and coincidence gamma images of positron sources in thin objects such as leaves of plants. This hybrid imager can be used to measure carbon assimilation in plants quantitatively and in real-time after C-11 labeled carbon-dioxide is administered. A better understanding of carbon assimilation, particularly under the increasingly elevated atmospheric CO2 level, is extremely critical for plant scientists who study food crop and biofuel production. Phase 1 of this project is focused on the technology development with 3 specific aims: (1) develop a hybrid detector that can detect beta and gamma rays simultaneously; (2) develop an imaging system that can differentiate these two types of radiation and acquire beta and coincidence gamma images in real-time; (3) develop techniques to quantify radiotracer distribution using beta and gamma images. Phase 2 of this project is to apply technologies developed in phase 1 to study plants using positron-emitting radionuclide such as 11C to study carbon assimilation in biofuel plants.

  4. A new approach to prompt fission neutron TOF data treatment

    Science.gov (United States)

    Zeynalov, Sh.; Zeynalova, O. V.; Hambsch, F.-J.; Oberstedt, S.

    The prompt neutron emission in spontaneous fission of 252Cf has been investigated applying digital signal electronics along with associated digital signal processing algorithms. A new mathematical approach, applicable to single events, was developed for prompt fission neutron (PFN) time-offlight distribution unfolding. The main goal was to understand the reasons of the long existing discrepancy between theoretical calculations and the measurements of prompt fission neutron (PFN) emission dependence on the total kinetic energy (TKE) of the fission fragments (FF). Since the 252Cf (sf) reaction is one of the main references for nuclear data the understanding of the PFN emission mechanism is very important both for nuclear fission theory and nuclear data. The experimental data were taken with a twin Frisch-grid ionization chamber and a NE213-equivalent neutron detector in an experimental setup similar to the well known work of C. Budtz-Jorgensen and H.-H. Knitter. About 2.5 × 105 coincidences between fission fragment (FF) and neutron detector response to prompt fission neutron detection have been registered (∼ 1.6 × 107 of total recorded fission events). Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12-bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. The main goal of this work was a detailed description of the prompt fission neutron treatment.

  5. Lev Landau and the conception of neutron stars

    CERN Document Server

    Yakovlev, Dmitry G; Baym, Gordon; Pethick, Christopher J

    2012-01-01

    We review the history of neutron star physics in the 1930s that is related to L. Landau. According to recollections of Rosenfeld (1974, Proc. 16th Solvay Conference on Physics, p. 174), Landau improvised the concept of neutron stars in a discussion with Bohr and Rosenfeld just after the news of the discovery of the neutron reached Copenhagen in February 1932. We present arguments that the discussion took place in March 1931, before the discovery of the neutron, and that they in fact discussed the paper written by Landau in Zurich in February 1931 but not published until February 1932 (Phys. Z. Sowjetunion, 1, 285). In his paper Landau mentioned the possible existence of dense stars which look like one giant nucleus; this can be regarded as an early theoretical prediction or anticipation of neutron stars, prior to the discovery of the neutron. The coincidence of the dates of the neutron's discovery and the paper's publication has led to an erroneous association of the paper with the discovery of the neutron. I...

  6. A comparison of coincident GRACE and ICESat data over Antarctica

    NARCIS (Netherlands)

    Gunter, B.; Urban, T.; Riva, R.E.M.; Helsen, M.M.; Harpold, R.; Poole, S.; Nagel, P.; Schutz, B.; Tapley, B.

    2009-01-01

    In this study, we present a comparison of coincident GRACE and ICESat data over Antarctica. The analysis focused on the secular changes over a 4-year period spanning from 2003 to 2007, using the recently reprocessed and publicly available data sets for both missions. The results show that the two in

  7. Limb-nadir matching using non-coincident NO

    NARCIS (Netherlands)

    Adams, Cristen; Normand, Elise N.; McLinden, Chris A.; Bourassa, Adam E.; Lloyd, Nicholas D.; Degenstein, Douglas A.; Krotkov, Nickolay A.; Belmonte Rivas, Maria; Boersma, Folkert; Eskes, Henk

    2016-01-01

    A variant of the limb-nadir matching technique for deriving tropospheric NO2 columns is presented in which the stratospheric component of the NO2 slant column density (SCD) measured by the Ozone Monitoring Instrument (OMI) is removed using non-coincident profiles from the

  8. A {beta} - {gamma} coincidence; Metodo de coincidencias {beta} - {gamma}

    Energy Technology Data Exchange (ETDEWEB)

    Agullo, F.

    1960-07-01

    A {beta} - {gamma} coincidence method for absolute counting is given. The fundamental principles are revised and the experimental part is detailed. The results from {sup 1}98 Au irradiated in the JEN 1 Swimming pool reactor are given. The maximal accuracy is 1 per cent. (Author) 11 refs.

  9. Limb-nadir matching using non-coincident NO

    NARCIS (Netherlands)

    Adams, Cristen; Normand, Elise N.; McLinden, Chris A.; Bourassa, Adam E.; Lloyd, Nicholas D.; Degenstein, Douglas A.; Krotkov, Nickolay A.; Belmonte Rivas, Maria; Boersma, Folkert; Eskes, Henk

    2016-01-01

    A variant of the limb-nadir matching technique for deriving tropospheric NO2 columns is presented in which the stratospheric component of the NO2 slant column density (SCD) measured by the Ozone Monitoring Instrument (OMI) is removed using non-coincident profiles from the Op

  10. Coincident optima for two-facility Weber problems

    DEFF Research Database (Denmark)

    Juel, Henrik

    1983-01-01

    The location problem with two new facilities in continuous space is considered, with distance measured by arbitrary norms. Necessary and sufficient conditions for a proposed solution to be optimal are given for several cases. These cases include situations where the cost function...... is nondifferentiable because facilities coincide...

  11. Modulating lignin in plants

    Science.gov (United States)

    Apuya, Nestor; Bobzin, Steven Craig; Okamuro, Jack; Zhang, Ke

    2013-01-29

    Materials and methods for modulating (e.g., increasing or decreasing) lignin content in plants are disclosed. For example, nucleic acids encoding lignin-modulating polypeptides are disclosed as well as methods for using such nucleic acids to generate transgenic plants having a modulated lignin content.

  12. Chromosome painting in plants.

    NARCIS (Netherlands)

    Schubert, I.; Fransz, P.F.; Fuchs, J.; Jong, de J.H.

    2001-01-01

    The current 'state-of-art' as to chromosome painting in plants is reviewed. We define different situations described as painting so far: i) Genomic in situ hybridisation (GISH) with total genomic DNA to distinguish alien chromosomes on the basis of divergent dispersed repeats, ii) 'Chromosomal in si

  13. Carotenoid metabolism in plants

    Science.gov (United States)

    Carotenoids are mostly C40 terpenoids, a class of hydrocarbons that participate in various biological processes in plants, such as photosynthesis, photomorphogenesis, photoprotection, and development. Carotenoids also serve as precursors for two plant hormones and a diverse set of apocarotenoids. Th...

  14. Chromosome painting in plants.

    NARCIS (Netherlands)

    Schubert, I.; Fransz, P.F.; Fuchs, J.; Jong, de J.H.

    2001-01-01

    The current 'state-of-art' as to chromosome painting in plants is reviewed. We define different situations described as painting so far: i) Genomic in situ hybridisation (GISH) with total genomic DNA to distinguish alien chromosomes on the basis of divergent dispersed repeats, ii) 'Chromosomal in

  15. Methylome evolution in plants

    NARCIS (Netherlands)

    Vidalis, Amaryllis; Živković, Daniel; Wardenaar, René; Roquis, David; Tellier, Aurélien; Johannes, Frank

    2016-01-01

    Despite major progress in dissecting the molecular pathways that control DNA methylation patterns in plants, little is known about the mechanisms that shape plant methylomes over evolutionary time. Drawing on recent intra- and interspecific epigenomic studies, we show that methylome evolution over

  16. Iron stress in plants.

    Science.gov (United States)

    Connolly, Erin L; Guerinot, Mary

    2002-07-30

    Although iron is an essential nutrient for plants, its accumulation within cells can be toxic. Plants, therefore, respond to both iron deficiency and iron excess by inducing expression of different gene sets. Here, we review recent advances in the understanding of iron homeostasis in plants gained through functional genomic approaches

  17. Iron stress in plants

    OpenAIRE

    Connolly, Erin L.; Guerinot, Mary Lou

    2002-01-01

    Although iron is an essential nutrient for plants, its accumulation within cells can be toxic. Plants, therefore, respond to both iron deficiency and iron excess by inducing expression of different gene sets. Here, we review recent advances in the understanding of iron homeostasis in plants gained through functional genomic approaches.

  18. Superheated drop neutron spectrometer

    CERN Document Server

    Das, M; Roy, B; Roy, S C; Das, Mala

    2000-01-01

    Superheated drops are known to detect neutrons through the nucleation caused by the recoil nuclei produced by the interactions of neutrons with the atoms constituting the superheated liquid molecule. A novel method of finding the neutron energy from the temperature dependence response of SDD has been developed. From the equivalence between the dependence of threshold energy for nucleation on temperature of SDD and the dependence of dE/dx of the recoil ions with the energy of the neutron, a new method of finding the neutron energy spectrum of a polychromatic as well as monochromatic neutron source has been developed.

  19. Neutron streak camera

    Science.gov (United States)

    Wang, Ching L.

    1983-09-13

    Apparatus for improved sensitivity and time resolution of a neutron measurement. The detector is provided with an electrode assembly having a neutron sensitive cathode which emits relatively low energy secondary electrons. The neutron sensitive cathode has a large surface area which provides increased sensitivity by intercepting a greater number of neutrons. The cathode is also curved to compensate for differences in transit time of the neutrons emanating from the point source. The slower speeds of the secondary electrons emitted from a certain portion of the cathode are matched to the transit times of the neutrons impinging thereupon.

  20. MCNP modelling of a combined neutron/gamma counter

    CERN Document Server

    Bourva, L C A; Ottmar, H; Weaver, D R

    1999-01-01

    A series of Monte Carlo neutron calculations for a combined gamma/passive neutron coincidence counter has been performed. This type of device, part of a suite of non-destructive assay instruments utilised for the enforcement of the Euratom nuclear safeguards within the European Union, is to be used for high accuracy measurements of the plutonium content of small samples of nuclear materials. The multi-purpose Monte Carlo N-particle (MCNP) code version 4B has been used to model in detail the neutron coincidence detector and to investigate the leakage self-multiplication of PuO sub 2 and mixed U-Pu oxide (MOX) reference samples used to calibrate the instrument. The MCNP calculations have been used together with a neutron coincidence counting interpretative model to determine characteristic parameters of the detector. A comparative study to both experimental and previous numerical results has been performed. Sensitivity curves of the variation of the detector's efficiency, epsilon, to, alpha, the ratio of (alpha...

  1. Determination of rare earth elements in plant protoplasts by MAA

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A preliminary study on the speciation of rare earth elements in plant cells has been carried out by molecular activation analysis (MAA). Mesophyll protoplasts of Brassica napus were isolated by enzymatic digestion. After being washed with isosmotic solution containing EDTA for several times, the protoplasts were purified by gradient centrifugation. Then the concentration of rare earth elements (REEs) in the protoplasts was determined by neutron activation analysis. The result shows that REEs can enter the cells of the plant.

  2. Determining fragmentation dynamics through a study of neutron multiplicity at the NSCL

    Science.gov (United States)

    Stephenson, Sharon; Christ, Peter; Mazza, Maria; MoNA Collaboration

    2017-01-01

    In nuclear fragmentation reactions the number of neutrons and the excitation energy of the final fragment are related to the excitation energies of prefragments, which are produced in the reaction target but not directly observed. The MoNA Collaboration designed and performed an experiment to measure the number of neutrons in coincidence with charged projectile fragments to determine the excitation mechanisms of specific prefragments. All prior MoNA experimental campaigns concentrated on neutrons emitted from discrete levels in near dripline nuclei and treated any evaporation neutrons as an underlying background. This experiment capitalizes on those evaporation neutrons, focusing on sodium, neon and fluorine reaction products. For the experiment a 32Mg secondary beam with energy 86 MeV/u was incident on a Be reaction target. This target is upstream from the Sweeper, a superconducting dipole steering magnet with a bending angle of 43° and a vertical gap that permits forward-focused neutrons to get to the MoNA, the Modular Neutron Array. The rigidity of the Sweeper was varied during this experiment to increase the detection range. Analysis of the neutron-neutron hit distribution in coincidence with each sodium, neon, or fluorine charged fragment will be presented. This work was supported in part by the National Science Foundation Award 1613429 and the Howard Hughes Medical Institute Award 52007540.

  3. Neutron Detection with Mercuric Iodide

    CERN Document Server

    Bell, Z A

    2003-01-01

    Mercuric iodide is a high-density, high-Z semiconducting material useful for gamma ray detection. This makes it convertible to a thermal neutron detector by covering it with a boron rich material and detecting the 478 keV gamma rays resulting from the sup 1 sup 0 B(n, alpha) sup 7 Li* reaction. However, the 374 barn thermal capture cross section of sup n sup a sup t Hg, makes the detector itself an attractive absorber, and this has been exploited previously. Since previous work indicates that there are no low-energy gamma rays emitted in coincidence with the 368 keV capture gamma from the dominant sup 1 sup 9 sup 9 Hg(n, gamma) sup 2 sup 0 sup 0 Hg reaction, only the 368 keV capture gamma is seen with any efficiency a relatively thin (few mm) detector. In this paper we report preliminary measurements of neutrons via capture reactions in a bare mercuric iodide crystal and a crystal covered in sup 1 sup 0 B-loaded epoxy. The covered detector is an improvement over the bare detector because the presence of both ...

  4. Electron-ion-ion coincidence experiments for photofragmentation of polyatomic molecules using pulsed electric fields: Treatment of random coincidences

    Energy Technology Data Exchange (ETDEWEB)

    Pruemper, G. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980 8577 (Japan)]. E-mail: pruemper@tagen.tohoku.ac.jp; Ueda, K. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980 8577 (Japan)

    2007-05-01

    In molecular photofragmentation processes by soft X-rays, a number of ionic fragments can be produced, each having a different abundance and correlation with the kinetic energy of the emitted electron. For investigating these fragmentation processes, electron-ion and electron-ion-ion coincidence experiments, in which the kinetic energy of electrons are analyzed using an electrostatic analyzer while the mass of the ions is analyzed using a pulsed electric field, are very powerful. For such measurements, however, the contribution of random coincidences is substantial and affects the data in a non-trivial way. Simple intuitive subtraction methods cannot be applied. In the present paper, we describe these electron-ion and electron-ion-ion coincidence experiments together with a subtraction method for the contribution from random coincidences. We provide a comprehensive set of equations for the data treatment, including equations for the calculation of error-bars. We demonstrate the method by applying it to the fragmentation of free CF{sub 3}SF{sub 5} molecules.

  5. Excitations of one-valence-proton, one-valence-neutron nucleus {sup 210}Bi from cold-neutron capture

    Energy Technology Data Exchange (ETDEWEB)

    Cieplicka-Oryńczak, N. [INFN sezione di Milano, Via Celoria 16, 20133 Milano (Italy); Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Kraków (Poland); Fornal, B.; Szpak, B. [Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Kraków (Poland); Leoni, S.; Bottoni, S. [INFN sezione di Milano, Via Celoria 16, 20133 Milano (Italy); Università degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Bazzacco, D. [Dipartimento di Fisica e Astronomia dell’Università, I-35131 Padova (Italy); INFN Sezione di Padova, I-35131 Padova (Italy); Blanc, A.; Jentschel, M.; Köster, U.; Mutti, P.; Soldner, T. [Institute Laue-Langevin, 6, rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Bocchi, G. [Università degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); France, G. de [GANIL, Bd. Becquerel, BP 55027, 14076 CAEN Cedex 05 (France); Simpson, G. [LPSC, Université Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, F-38026 Grenoble Cedex (France); Ur, C. [INFN Sezione di Padova, Via F. Marzolo 8, I-35131 Padova (Italy); Urban, W. [Faculty of Physics, University of Warsaw, ul. Hoża 69, 02-681, Warszawa (Poland)

    2015-10-15

    The low-spin structure of one-proton, one-neutron {sup 210}Bi nucleus was investigated in cold-neutron capture reaction on {sup 209}Bi. The γ-coincidence measurements were performed with use of EXILL array consisted of 16 HPGe detectors. The experimental results were compared to shell-model calculations involving valence particles excitations. The {sup 210}Bi nucleus offers the potential to test the effective proton-neutron interactions because most of the states should arise from the proton-neutron excitations. Additionally, it was discovered that a few states should come from the couplings of valence particles to the 3{sup −} octupole vibration in {sup 208}Pb which provides also the possibility of testing the calculations involving the core excitations.

  6. Neutron anatomy

    Energy Technology Data Exchange (ETDEWEB)

    Bacon, G.E. [Univ. of Sheffield (United Kingdom)

    1994-12-31

    The familiar extremes of crystalline material are single-crystals and random powders. In between these two extremes are polycrystalline aggregates, not randomly arranged but possessing some preferred orientation and this is the form taken by constructional materials, be they steel girders or the bones of a human or animal skeleton. The details of the preferred orientation determine the ability of the material to withstand stress in any direction. In the case of bone the crucial factor is the orientation of the c-axes of the mineral content - the crystals of the hexagonal hydroxyapatite - and this can readily be determined by neutron diffraction. In particular it can be measured over the volume of a piece of bone, utilizing distances ranging from 1mm to 10mm. The major practical problem is to avoid the intense incoherent scattering from the hydrogen in the accompanying collagen; this can best be achieved by heat-treatment and it is demonstrated that this does not affect the underlying apatite. These studies of bone give leading anatomical information on the life and activities of humans and animals - including, for example, the life history of the human femur, the locomotion of sheep, the fracture of the legs of racehorses and the life-styles of Neolithic tribes. We conclude that the material is placed economically in the bone to withstand the expected stresses of life and the environment. The experimental results are presented in terms of the magnitude of the 0002 apatite reflection. It so happens that for a random powder the 0002, 1121 reflections, which are neighboring lines in the powder pattern, are approximately equal in intensity. The latter reflection, being of manifold multiplicity, is scarcely affected by preferred orientation so that the numerical value of the 0002/1121 ratio serves quite accurately as a quantitative measure of the degree of orientation of the c-axes in any chosen direction for a sample of bone.

  7. Tungsten Toxicity in Plants

    Science.gov (United States)

    Adamakis, Ioannis-Dimosthenis S.; Panteris, Emmanuel; Eleftheriou, Eleftherios P.

    2012-01-01

    Tungsten (W) is a rare heavy metal, widely used in a range of industrial, military and household applications due to its unique physical properties. These activities inevitably have accounted for local W accumulation at high concentrations, raising concerns about its effects for living organisms. In plants, W has primarily been used as an inhibitor of the molybdoenzymes, since it antagonizes molybdenum (Mo) for the Mo-cofactor (MoCo) of these enzymes. However, recent advances indicate that, beyond Mo-enzyme inhibition, W has toxic attributes similar with those of other heavy metals. These include hindering of seedling growth, reduction of root and shoot biomass, ultrastructural malformations of cell components, aberration of cell cycle, disruption of the cytoskeleton and deregulation of gene expression related with programmed cell death (PCD). In this article, the recent available information on W toxicity in plants and plant cells is reviewed, and the knowledge gaps and the most pertinent research directions are outlined. PMID:27137642

  8. Epigenetic memory in plants.

    Science.gov (United States)

    Iwasaki, Mayumi; Paszkowski, Jerzy

    2014-09-17

    Epigenetics refers to heritable changes in patterns of gene expression that occur without alterations in DNA sequence. The epigenetic mechanisms involve covalent modifications of DNA and histones, which affect transcriptional activity of chromatin. Since chromatin states can be propagated through mitotic and meiotic divisions, epigenetic mechanisms are thought to provide heritable 'cellular memory'. Here, we review selected examples of epigenetic memory in plants and briefly discuss underlying mechanisms.

  9. Application Guide to Neutron Multiplicity Counting

    Energy Technology Data Exchange (ETDEWEB)

    D. G. Langner; J. E. Stewart; M. M. Pickrell; M. S. Krick; N. Ensslin; W. C. Harker

    1998-11-01

    This document is intended to serve as a comprehensive applications guide to passive neutron multiplicity counting, a new nondestructive assay (NDA) technique developed over the past ten years. The document describes the principles of multiplicity counter design, electronics, and mathematics. Existing counters in Department of Energy (DOE) facilities are surveyed, and their operating requirements and procedures and defined. Current applications to plutonium material types found in DOE facilities are described, and estimates of the expected assay precision and bias are given. Lastly, guidelines for multiplicity counter selection and procurement are summarized. The document also includes a detailed collection of references on passive neutron coincidence and multiplicity publications over the last ten to fifteen years.

  10. Gamma spectroscopy of neutron rich actinide nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Birkenbach, Benedikt; Geibel, Kerstin; Vogt, Andreas; Hess, Herbert; Reiter, Peter; Steinbach, Tim; Schneiders, David [Koeln Univ. (Germany). IKP; Collaboration: AGATA-Collaboration

    2013-07-01

    Excited states in neutron-rich actinide Th and U nuclei were investigated after multi nucleon transfer reactions employing the AGATA demonstrator and PRISMA setup at LNL (INFN, Italy). A primary {sup 136}Xe beam of 1 GeV hitting a {sup 238}U target was used to produce the nuclei of interest. Beam-like reaction products of Xe- and Ba isotopes after neutron transfer were selected by the PRISMA spectrometer. The recoil like particles were registered by a MCP detector inside the scattering chamber. Coincident γ-rays from excited states in beam and target like particles were measured with the position sensitive AGATA HPGe detectors. Improved Doppler correction and quality of the γ-spectra is based on the novel γ-ray tracking technique which was successfully exploited. First results on the collective properties of various Th and U isotopes are discussed.

  11. Neutron Capture Cross Section of 239Pu

    Science.gov (United States)

    Mosby, S.; Arnold, C.; Bredeweg, T. A.; Couture, A.; Jandel, M.; O'Donnell, J. M.; Rusev, G.; Ullmann, J. L.; Chyzh, A.; Henderson, R.; Kwan, E.; Wu, C. Y.

    2014-09-01

    The 239Pu(n,γ) cross section has been measured over the energy range 10 eV - 10 keV using the Detector for Advanced Neutron Capture Experiments (DANCE) as part of a campaign to produce precision (n,γ) measurements on 239Pu in the keV region. Fission coincidences were measured with a PPAC and used to characterize the prompt fission γ-ray spectrum in this region. The resulting spectra will be used to better characterize the fission component of another experiment with a thicker target to extend the (n,γ) cross section measurement well into the keV region.

  12. Simulations to Evaluate Accuracy and Patient Dose in Neutron-Stimulated, Emission-Computed Tomography (NSECT) for Diagnosis of Breast Cancer

    Science.gov (United States)

    2009-04-01

    One detector design that could provide the two-dimensional projection image is the Compton coincidence detector (CCD) that has been developed and...detector such as a Compton coincidence detector and to illuminate the entire sample with the neutron beam. a neutron source, (2) a sample and (3) a...Wilderman S J 1998 C-SPRINT: a prototype Compton camera system for low energy gamma ray imaging IEEE Trans. Nucl. Sci. 45 943–9 Margalioth E J, Schenker J

  13. Imaging with Scattered Neutrons

    OpenAIRE

    Ballhausen, H.; Abele, H.; Gaehler, R.; Trapp, M.; Van Overberghe, A.

    2006-01-01

    We describe a novel experimental technique for neutron imaging with scattered neutrons. These scattered neutrons are of interest for condensed matter physics, because they permit to reveal the local distribution of incoherent and coherent scattering within a sample. In contrast to standard attenuation based imaging, scattered neutron imaging distinguishes between the scattering cross section and the total attenuation cross section including absorption. First successful low-noise millimeter-re...

  14. Intense fusion neutron sources

    Science.gov (United States)

    Kuteev, B. V.; Goncharov, P. R.; Sergeev, V. Yu.; Khripunov, V. I.

    2010-04-01

    The review describes physical principles underlying efficient production of free neutrons, up-to-date possibilities and prospects of creating fission and fusion neutron sources with intensities of 1015-1021 neutrons/s, and schemes of production and application of neutrons in fusion-fission hybrid systems. The physical processes and parameters of high-temperature plasmas are considered at which optimal conditions for producing the largest number of fusion neutrons in systems with magnetic and inertial plasma confinement are achieved. The proposed plasma methods for neutron production are compared with other methods based on fusion reactions in nonplasma media, fission reactions, spallation, and muon catalysis. At present, intense neutron fluxes are mainly used in nanotechnology, biotechnology, material science, and military and fundamental research. In the near future (10-20 years), it will be possible to apply high-power neutron sources in fusion-fission hybrid systems for producing hydrogen, electric power, and technological heat, as well as for manufacturing synthetic nuclear fuel and closing the nuclear fuel cycle. Neutron sources with intensities approaching 1020 neutrons/s may radically change the structure of power industry and considerably influence the fundamental and applied science and innovation technologies. Along with utilizing the energy produced in fusion reactions, the achievement of such high neutron intensities may stimulate wide application of subcritical fast nuclear reactors controlled by neutron sources. Superpower neutron sources will allow one to solve many problems of neutron diagnostics, monitor nano-and biological objects, and carry out radiation testing and modification of volumetric properties of materials at the industrial level. Such sources will considerably (up to 100 times) improve the accuracy of neutron physics experiments and will provide a better understanding of the structure of matter, including that of the neutron itself.

  15. Tetrapyrrole Signaling in Plants

    Science.gov (United States)

    Larkin, Robert M.

    2016-01-01

    Tetrapyrroles make critical contributions to a number of important processes in diverse organisms. In plants, tetrapyrroles are essential for light signaling, the detoxification of reactive oxygen species, the assimilation of nitrate and sulfate, respiration, photosynthesis, and programed cell death. The misregulation of tetrapyrrole metabolism can produce toxic reactive oxygen species. Thus, it is not surprising that tetrapyrrole metabolism is strictly regulated and that tetrapyrrole metabolism affects signaling mechanisms that regulate gene expression. In plants and algae, tetrapyrroles are synthesized in plastids and were some of the first plastid signals demonstrated to regulate nuclear gene expression. In plants, the mechanism of tetrapyrrole-dependent plastid-to-nucleus signaling remains poorly understood. Additionally, some of experiments that tested ideas for possible signaling mechanisms appeared to produce conflicting data. In some instances, these conflicts are potentially explained by different experimental conditions. Although the biological function of tetrapyrrole signaling is poorly understood, there is compelling evidence that this signaling is significant. Specifically, this signaling appears to affect the accumulation of starch and may promote abiotic stress tolerance. Tetrapyrrole-dependent plastid-to-nucleus signaling interacts with a distinct plastid-to-nucleus signaling mechanism that depends on GENOMES UNCUOPLED1 (GUN1). GUN1 contributes to a variety of processes, such as chloroplast biogenesis, the circadian rhythm, abiotic stress tolerance, and development. Thus, the contribution of tetrapyrrole signaling to plant function is potentially broader than we currently appreciate. In this review, I discuss these aspects of tetrapyrrole signaling.

  16. Data Acquisition System for Electron Energy Loss Coincident Spectrometers

    Institute of Scientific and Technical Information of China (English)

    Zhang Chi; Yu Xiaoqi; Yang Tao

    2005-01-01

    A Data Acquisition System (DAQ) for electron energy loss coincident spectrometers (EELCS) has been developed. The system is composed of a Multiplex Time-Digital Converter (TDC) that measures the flying time of positive and negative ions and a one-dimension positionsensitive detector that records the energy loss of scattering electrons. The experimental data are buffered in a first-in-first-out(FIFO) memory module, then transferred from the FIFO memory to PC by the USB interface. The DAQ system can record the flying time of several ions in one collision, and allows of different data collection modes. The system has been demonstrated at the Electron Energy Loss Coincident Spectrometers at the Laboratory of Atomic and Molecular Physics, USTC. A detail description of the whole system is given and experimental results shown.

  17. Spatial coincidence modulates interaction between visual and somatosensory evoked potentials.

    Science.gov (United States)

    Schürmann, Martin; Kolev, Vasil; Menzel, Kristina; Yordanova, Juliana

    2002-05-07

    The time course of interaction between concurrently applied visual and somatosensory stimulation with respect to evoked potentials (EPs) was studied. Visual stimuli, either in the left or right hemifield, and electric stimuli to the left wrist were delivered either alone or simultaneously. Visual and somatosensory EPs were summed and compared to bimodal EPs (BiEP, response to actual combination of both modalities). Temporal coincidence of stimuli lead to sub-additive or over-additive amplitudes in BiEPs in several time windows between 75 and 275 ms. Additional effects of spatial coincidence (left wrist with left hemifield) were found between 75 and 300 ms and beyond 450 ms. These interaction effects hint at a temporo-spatial pattern of multiple brain areas participating in the process of multimodal integration.

  18. Subthreshold production of pions in coincidence with light particles

    Energy Technology Data Exchange (ETDEWEB)

    Barbera, R.; Badala, A.; Adorno, A.; Bonasera, A.; Di Toro, M.; Palmeri, A.; Pappalardo, G.S.; Riggi, F.; Russo, G. (Istituto Nazionale di Fisica Nucleare, Catania (Italy)); Bizard, G.; Durand, D.; Laville, J.L. (Caen Univ., 14 (France). Lab. de Physique Corpusculaire); Jin, G.M. (Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France)); Rosato, E. (Naples Univ. (Italy). Dipt. di Scienze Fisiche Istituto Nazionale di Fisica Nucleare, Naples (Italy))

    1990-12-03

    He ions have been detected in coincidence with charged pions in the reaction {sup 16}O on {sup 27}Al at E{sub lab}=94 MeV/u. We analyse velocity spectra and cross-sections of He ions emitted in the angular range 4deg/150deg in coincidence with charged pions detected at 90deg. A two source emission mechanism of the helium particles and a pion statistical production from an equilibrated participant zone is stressed. The absolute yields at different angles are compared with results of a theoretical model for medium energy heavy ion reactions in the frame of a participant-spectator picture. A comparison of the pion energy spectra with Boltzmann-Nordheim-Vlasov calculations and a discussion on the time scale for pion emission is also presented. (orig.).

  19. A coincidence of addiction to "Kratom" and severe primary hypothyroidism.

    Science.gov (United States)

    Sheleg, Sergey V; Collins, Gregory B

    2011-12-01

    Here we present a case of a coincidence of addiction to "Kratom" (botanically known as Mitragyna speciosa Korth) and developed severe primary hypothyroidism. We are discussing a possibility that high dose of indole alkaloid mitragynine (the major alkaloid identified from "Kratom") might reduce the normal response of the thyroid gland to thyroid-stimulating hormone resulting in primary hypothyroidism. Further experimental investigations of mitragynine as a possible suppressor of thyroid gland function would be a matter of interest.

  20. Coincidence of cerebrovascular accident and silent myocardial infarction.

    Science.gov (United States)

    Badui, E; Estañol, B; Garcia-Rubi, D

    1982-11-01

    Although it is well known that a myocardial and a cerebral infarction may be coincident, the nature of this association is not clear. The problem is further complicated because the myocardial infarction may be silent. This is a report of 3 patients with cerebral infarct in whom a silent recent myocardial infarction was found. All patients with cerebrovascular disease should be screened for a possible myocardial lesion.

  1. A catalogue of ULX coincidences with FIRST radio sources

    CERN Document Server

    Sanchez-Sutil, J R; Martí, J; Garrido, J L; Pérez-Ramírez, D; Luque-Escamilla, P

    2006-01-01

    We search for ultra luminous X-ray source (ULXs) radio counterparts located in nearby galaxies in order to constrain their physical nature. Our work is based on a systematic cross-identification of the most recent and extensive available ULX catalogues and archival radio data. A catalogue of 70 positional coincidences is reported. Most of them are located within the galaxy nucleus. Among them, we find 11 new cases of non-nuclear ULX sources with possibly associated radio emission.

  2. Non-minimal quintessence: Dynamics and coincidence problem

    Indian Academy of Sciences (India)

    Fatimah Shojai; Ali Shojai

    2011-12-01

    Brans–Dicke scalar–tensor theory provides a conformal coupling of the scalar field with gravity in Einstein’s frame. This model is equivalent to an interacting quintessence in which dark matter is coupled to dark energy. This provides a natural mechanism to alleviate the coincidence problem. We investigate the dynamics of this model and show that it leads to comparable dark energy and dark matter densities today.

  3. Coincidence Theorems for Certain Classes of Hybrid Contractions

    Directory of Open Access Journals (Sweden)

    Singh SL

    2010-01-01

    Full Text Available Coincidence and fixed point theorems for a new class of hybrid contractions consisting of a pair of single-valued and multivalued maps on an arbitrary nonempty set with values in a metric space are proved. In addition, the existence of a common solution for certain class of functional equations arising in dynamic programming, under much weaker conditions are discussed. The results obtained here in generalize many well known results.

  4. Caristi Type Coincidence Point Theorem in Topological Spaces

    Directory of Open Access Journals (Sweden)

    Jiang Zhu

    2013-01-01

    Full Text Available A generalized Caristi type coincidence point theorem and its equivalences in the setting of topological spaces by using a kind of nonmetric type function are obtained. These results are used to establish variational principle and its equivalences in d-complete spaces, bornological vector space, seven kinds of completed quasi-semimetric spaces equipped with Q-functions, uniform spaces with q-distance, generating spaces of quasimetric family, and fuzzy metric spaces.

  5. Non-Statistical Effects in Neutron Capture

    Science.gov (United States)

    Koehler, P. E.; Bredeweg, T. A.; Guber, K. H.; Harvey, J. A.; O'Donnell, J. M.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wiarda, D.; Wouters, J. M.

    2009-01-01

    There have been many reports of non-statistical effects in neutron-capture measurements. However, reports of deviations of reduced-neutron-width (Γn0) distributions from the expected Porter-Thomas (PT) shape largely have been ignored. Most of these deviations have been reported for odd-A nuclides. Because reliable spin (J) assignments have been absent for most resonances for such nuclides, it is possible that reported deviations from PT might be due to incorrect J assignments. We recently developed a new method for measuring spins of neutron resonances by using the DANCE detector at the Los Alamos Neutron Science Center (LANSCE). Measurements made with a 147Sm sample allowed us to determine spins of almost all known resonances below 1 keV. Furthermore, analysis of these data revealed that the Γn0 distribution was in good agreement with PT for resonances below 350 eV, but in disagreement with PT for resonances between 350 and 700 eV. Our previous (n,α) measurements had revealed that the α strength function also changes abruptly at this energy. There currently is no known explanation for these two non-statistical effects. Recently, we have developed another new method for determining the spins of neutron resonances. To implement this technique required a small change (to record pulse-height information for coincidence events) to a much simpler apparatus: A pair of C6D6 γ-ray detectors which we have employed for many years to measure neutron-capture cross sections at the Oak Ridge Electron Linear Accelerator (ORELA). Measurements with a 95Mo sample revealed that not only does the method work very well for determining spins, but it also makes possible parity assignments. Taken together, these new techniques at LANSCE and ORELA could be very useful for further elucidation of non-statistical effects.

  6. International Neutron Radiography Newsletter

    DEFF Research Database (Denmark)

    Domanus, Joseph Czeslaw

    1986-01-01

    At the First World Conference on Neutron Radiography i t was decided to continue the "Neutron Radiography Newsletter", published previously by J.P. Barton, as the "International Neutron Radiography Newsletter" (INRNL), with J.C. Doraanus as editor. The British Journal of Non-Destructive Testing...

  7. Advanced neutron absorber materials

    Science.gov (United States)

    Branagan, Daniel J.; Smolik, Galen R.

    2000-01-01

    A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials, the neutron absorbing material having a combination of superior neutron capture cross sections coupled with enhanced resistance to corrosion, oxidation and leaching.

  8. Prototype Neutron Energy Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Stephen Mitchell, Sanjoy Mukhopadhyay, Richard Maurer, Ronald Wolff

    2010-06-16

    The project goals are: (1) Use three to five pressurized helium tubes with varying polyethylene moderators to build a neutron energy spectrometer that is most sensitive to the incident neutron energy of interest. Neutron energies that are of particular interest are those from the fission neutrons (typically around 1-2 MeV); (2) Neutron Source Identification - Use the neutron energy 'selectivity' property as a tool to discriminate against other competing processes by which neutrons are generated (viz. Cosmic ray induced neutron production [ship effect], [a, n] reactions); (3) Determine the efficiency as a function of neutron energy (response function) of each of the detectors, and thereby obtain the composite neutron energy spectrum from the detector count rates; and (4) Far-field data characterization and effectively discerning shielded fission source. Summary of the presentation is: (1) A light weight simple form factor compact neutron energy spectrometer ready to be used in maritime missions has been built; (2) Under laboratory conditions, individual Single Neutron Source Identification is possible within 30 minutes. (3) Sources belonging to the same type of origin viz., (a, n), fission, cosmic cluster in the same place in the 2-D plot shown; and (4) Isotopes belonging to the same source origin like Cm-Be, Am-Be (a, n) or Pu-239, U-235 (fission) do have some overlap in the 2-D plot.

  9. LiF/ZnS neutron multiplicity counter

    Energy Technology Data Exchange (ETDEWEB)

    Stave, Sean, E-mail: sean.stave@pnnl.gov; Bliss, Mary; Kouzes, Richard; Lintereur, Azaree; Robinson, Sean; Siciliano, Edward; Wood, Lynn

    2015-06-01

    The availability of {sup 3}He in recent years is becoming restricted with an order of magnitude price increase for this material. Alternatives to the use of {sup 3}He for the detection of thermal neutrons are under investigation. One of the most challenging applications for {sup 3}He alternatives is in neutron multiplicity counters that provide rapid assay of samples which contain an unknown amount of plutonium in a potentially unknown configuration. With appropriate detector design that has minimal gamma-ray sensitivity and a high detection efficiency even for triple coincidence events, the neutron single, double, and triple coincidence events can be used to extract three unknown parameters such as the {sup 240}Pu-effective mass, the sample self-multiplication, and the (α,n) rate. This project is aimed at determining if commercially available {sup 3}He alternatives can satisfy this challenging application. Using MCNP modeling the best alternative identified used 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. However, to attain that desired high-level of performance two primary design challenges must be addressed. They include building a fast electronics system 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.

  10. MCNP-REN a Monte Carlo tool for neutron detector design

    CERN Document Server

    Abhold, M E

    2002-01-01

    The development of neutron detectors makes extensive use of the predictions of detector response through the use of Monte Carlo techniques in conjunction with the point reactor model. Unfortunately, the point reactor model fails to accurately predict detector response in common applications. For this reason, the general Monte Carlo code developed at Los Alamos National Laboratory, Monte Carlo N-Particle (MCNP), was modified to simulate the pulse streams that would be generated by a neutron detector and normally analyzed by a shift register. This modified code, MCNP-Random Exponentially Distributed Neutron Source (MCNP-REN), along with the Time Analysis Program, predicts neutron detector response without using the point reactor model, making it unnecessary for the user to decide whether or not the assumptions of the point model are met for their application. MCNP-REN is capable of simulating standard neutron coincidence counting as well as neutron multiplicity counting. Measurements of mixed oxide fresh fuel w...

  11. Quasifree photoproduction of eta mesons off the neutron.

    Science.gov (United States)

    Jaegle, I; Mertens, T; Anisovich, A V; Bacelar, J C S; Bantes, B; Bartholomy, O; Bayadilov, D; Beck, R; Beloglazov, Y A; Castelijns, R; Crede, V; Dutz, H; Ehmanns, A; Elsner, D; Essig, K; Ewald, R; Fabry, I; Fuchs, M; Funke, Ch; Gothe, R; Gregor, R; Gridnev, A B; Gutz, E; Höffgen, S; Hoffmeister, P; Horn, I; Junkersfeld, J; Kalinowsky, H; Kammer, S; Kleber, V; Klein, Frank; Klein, Friedrich; Klempt, E; Konrad, M; Kotulla, M; Krusche, B; Lang, M; Langheinrich, J; Löhner, H; Lopatin, I V; Lotz, J; Lugert, S; Menze, D; Messchendorp, J G; Metag, V; Morales, C; Nanova, M; Nikonov, V A; Novinski, D; Novotny, R; Ostrick, M; Pant, L M; van Pee, H; Pfeiffer, M; Radkov, A; Roy, A; Sarantsev, A V; Schadmand, S; Schmidt, C; Schmieden, H; Schoch, B; Shende, S V; Sokhoyan, V; Süle, A; Sumachev, V V; Szczepanek, T; Thoma, U; Trnka, D; Varma, R; Walther, D; Weinheimer, Ch; Wendel, Ch

    2008-06-27

    Quasifree photoproduction of eta mesons off nucleons bound in the deuteron has been measured with the CBELSA/TAPS detector for incident photon energies up to 2.5 GeV at the Bonn ELSA accelerator. The eta mesons have been detected in coincidence with recoil protons and recoil neutrons, which allows a detailed comparison of the quasifree n(gamma,eta)n and p(gamma,eta)p reactions. The excitation function for eta production off the neutron shows a pronounced bumplike structure at W=1.68 GeV (E{gamma} approximately 1 GeV), which is absent for the proton.

  12. Portable Neutron Generator with 9-Section Silicon $\\alpha $-Detector

    CERN Document Server

    Bystritsky, V M; Kadyshevskij, V G; Khasaev, T O; Kobzev, A P; Presnyakov, Yu K; Rogov,Yu N; Ryzhkov, V I; Sapozhnikov, M G; Sissakian, A N; Slepnev, V M; Zamyatin, N I

    2006-01-01

    The characteristics of the portable neutron generator with a built-in $\\alpha $-detector are presented. Based on the "tagged" neutron method (TNM) the generator ~is being used for identification of ~the hidden chemical compounds. One of the special features of such generators compared to generators traditionally used and produced in industry is that the generator is a source of monoenergetic "tagged" 14.1 MeV neutrons produced in the binary nuclear reaction $d+t \\to \\alpha $ (3.5 MeV) $+n$ (14.1~MeV). Unambiguous information about the time and direction of the neutron emitted from the target can be obtained by recording an $\\alpha $ particle by the multi-pixel $\\alpha $-detector placed inside the neutron tube. The study of the "tagged" neutron method (TNM) shows that the use of the ($\\alpha $--$\\gamma $) coincidence reduces the gamma background induced by scattered neutrons by a factor of more than 200, which allows the detection and identification of small quantities of explosives, drugs, and toxic agents. T...

  13. Neutron scattering. Experiment manuals

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: The thermal triple axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, neutron polarization analysis with tht time-of-flight spectrometer DNS, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering with the KWS-1 and KWS-2 diffractometers, the very-small-angle neutron scattering diffractrometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  14. Grazing Incidence Neutron Optics

    Science.gov (United States)

    Gubarev, Mikhail V. (Inventor); Ramsey, Brian D. (Inventor); Engelhaupt, Darell E. (Inventor)

    2013-01-01

    Neutron optics based on the two-reflection geometries are capable of controlling beams of long wavelength neutrons with low angular divergence. The preferred mirror fabrication technique is a replication process with electroform nickel replication process being preferable. In the preliminary demonstration test an electroform nickel optics gave the neutron current density gain at the focal spot of the mirror at least 8 for neutron wavelengths in the range from 6 to 20.ANG.. The replication techniques can be also be used to fabricate neutron beam controlling guides.

  15. Neutron scatter camera

    Science.gov (United States)

    Mascarenhas, Nicholas; Marleau, Peter; Brennan, James S.; Krenz, Kevin D.

    2010-06-22

    An instrument that will directly image the fast fission neutrons from a special nuclear material source has been described. This instrument can improve the signal to background compared to non imaging neutron detection techniques by a factor given by ratio of the angular resolution window to 4.pi.. In addition to being a neutron imager, this instrument will also be an excellent neutron spectrometer, and will be able to differentiate between different types of neutron sources (e.g. fission, alpha-n, cosmic ray, and D-D or D-T fusion). Moreover, the instrument is able to pinpoint the source location.

  16. Advances in neutron tomography

    Indian Academy of Sciences (India)

    W Treimer

    2008-11-01

    In the last decade neutron radiography (NR) and tomography (NCT) have experienced a number of improvements, due to the well-known properties of neutrons interacting with matter, i.e. the low attenuation by many materials, the strong attenuation by hydrogenous constituent in samples, the wavelength-dependent attenuation in the neighbourhood of Bragg edges and due to better 2D neutron detectors. So NR and NCT were improved by sophisticated techniques that are based on the attenuation of neutrons or on phase changes of the associated neutron waves if they pass through structured materials. Up to now the interaction of the neutron spin with magnetic fields in samples has not been applied to imaging techniques despite the fact that it was proposed many years ago. About ten years ago neutron depolarization as imaging signal for neutron radiography or tomography was demonstrated and in principle it works. Now one can present much improved test experiments using polarized neutrons for radiographic imaging. For this purpose the CONRAD instrument of the HMI was equipped with polarizing and analysing benders very similar to conventional scattering experiments using polarized neutrons. Magnetic fields in different coils and in samples (superconductors) at low temperatures could be visualized. In this lecture a summary about standard signals (attenuation) and the more `sophisticated' imaging signals as refraction, small angle scattering and polarized neutrons will be given.

  17. TOR signalling in plants.

    Science.gov (United States)

    Rexin, Daniel; Meyer, Christian; Robaglia, Christophe; Veit, Bruce

    2015-08-15

    Although the eukaryotic TOR (target of rapamycin) kinase signalling pathway has emerged as a key player for integrating nutrient-, energy- and stress-related cues with growth and metabolic outputs, relatively little is known of how this ancient regulatory mechanism has been adapted in higher plants. Drawing comparisons with the substantial knowledge base around TOR kinase signalling in fungal and animal systems, functional aspects of this pathway in plants are reviewed. Both conserved and divergent elements are discussed in relation to unique aspects associated with an autotrophic mode of nutrition and adaptive strategies for multicellular development exhibited by plants.

  18. Neutronic Reactor Shield

    Science.gov (United States)

    Fermi, Enrico; Zinn, Walter H.

    The argument of the present Patent is a radiation shield suitable for protection of personnel from both gamma rays and neutrons. Such a shield from dangerous radiations is achieved to the best by the combined action of a neutron slowing material (a moderator) and a neutron absorbing material. Hydrogen is particularly effective for this shield since it is a good absorber of slow neutrons and a good moderator of fast neutrons. The neutrons slowed down by hydrogen may, then, be absorbed by other materials such as boron, cadmium, gadolinium, samarium or steel. Steel is particularly convenient for the purpose, given its effectiveness in absorbing also the gamma rays from the reactor (both primary gamma rays and secondary ones produced by the moderation of neutrons). In particular, in the present Patent a shield is described, made of alternate layers of steel and Masonite (an hydrolized ligno-cellulose material). The object of the present Patent is not discussed in any other published paper.

  19. Identification of neutron-rich isotope 197Os

    Institute of Scientific and Technical Information of China (English)

    YANG Wei-Fan; YUAN Shuang-Gui; XU Yan-Bing; XIAO Yong-Hou; ZHAO Li-Min; WANG Ping-Zhi; LI Heng-Yuan

    2004-01-01

    A new neutron-rich isotope 197Os was produced in the 198Pt(n, 2p) reaction by irradiating natural Pt targets with 14 MeV neutrons. The γ(X) singles spectrum and coincidence spectrum measurements were performed using two HPGe γ-ray detectors. Ten unknown γ-rays at 41.2, 50.7, 196.8, 199.6, 223.9, 233.1, 250.2, 342.1,403.6, and 460.4 keV attributed to the decay of 197Os were observed in the experiments. The half-life of 197Os was found to be (2.8 ± 0.6) min. A partial decay scheme of 197Os was proposed on the basis of decay and coincidence relations. The half-life was compared with the values expected by different theoretical models.

  20. Spectroscopy of {sup 189,187}Pb from gamma-FMA coincidences

    Energy Technology Data Exchange (ETDEWEB)

    Janssens, R.V.F.; Davids, C.N.; Blumenthal, D. [and others

    1995-08-01

    The very neutron-deficient Pb isotopes are of much current interest because they exhibit shape coexistence between a spherical groundstate and a deformed prolate excited configuration located very low in excitation energy. Last year the nucleus {sup 186}Pb was studied at the FMA in an FMA-{gamma}-{gamma} coincidence experiment. The purpose of the present measurement was to delineate, for the first time, the groundstate and near groundstate excitations in the odd Pb isotopes {sup 189,187}Pb in order to identify the orbitals which have an important role in driving the nuclear shape. The experiment was performed only very recently at the FMA with 10 Compton-suppressed Ge detectors from the Argonne Notre Dame BGO Gamma-Ray facility. {sup 187}Pb was studied with the {sup 155}Gd({sup 36}Ar,4n) reaction at 179 MeV, while {sup 189}Pb was reached with the {sup 158}Gd({sup 36}Ar,5n) reaction at the same beam energy. The analysis just began. It can already be stated that transitions in both Pb isotopes were identified and that it should be possible to establish level schemes. The presence of possible isomeric states in {sup 189}Pb will be checked in a follow-up experiment planned in Canberra. A similar measurement on {sup 187}Pb appears very difficult because of the very small cross section involved.

  1. A method to estimate the significance of coincident gravitational-wave observations from compact binary coalescence

    CERN Document Server

    Cannon, Kipp; Keppel, Drew

    2012-01-01

    Coalescing compact binary systems consisting of neutron stars and/or black holes should be detectable with upcoming advanced gravitational-wave detectors such as LIGO, Virgo, GEO and {KAGRA}. Gravitational-wave experiments to date have been riddled with non-Gaussian, non-stationary noise that makes it challenging to ascertain the significance of an event. A popular method to estimate significance is to time shift the events collected between detectors in order to establish a false coincidence rate. Here we propose a method for estimating the false alarm probability of events using variables commonly available to search candidates that does not rely on explicitly time shifting the events while still capturing the non-Gaussianity of the data. We present a method for establishing a statistical detection of events in the case where several silver-plated (3--5$\\sigma$) events exist but not necessarily any gold-plated ($>5\\sigma$) events. We use LIGO data and a simulated, realistic, blind signal population to test ...

  2. Toxic proteins in plants.

    Science.gov (United States)

    Dang, Liuyi; Van Damme, Els J M

    2015-09-01

    Plants have evolved to synthesize a variety of noxious compounds to cope with unfavorable circumstances, among which a large group of toxic proteins that play a critical role in plant defense against predators and microbes. Up to now, a wide range of harmful proteins have been discovered in different plants, including lectins, ribosome-inactivating proteins, protease inhibitors, ureases, arcelins, antimicrobial peptides and pore-forming toxins. To fulfill their role in plant defense, these proteins exhibit various degrees of toxicity towards animals, insects, bacteria or fungi. Numerous studies have been carried out to investigate the toxic effects and mode of action of these plant proteins in order to explore their possible applications. Indeed, because of their biological activities, toxic plant proteins are also considered as potentially useful tools in crop protection and in biomedical applications, such as cancer treatment. Genes encoding toxic plant proteins have been introduced into crop genomes using genetic engineering technology in order to increase the plant's resistance against pathogens and diseases. Despite the availability of ample information on toxic plant proteins, very few publications have attempted to summarize the research progress made during the last decades. This review focuses on the diversity of toxic plant proteins in view of their toxicity as well as their mode of action. Furthermore, an outlook towards the biological role(s) of these proteins and their potential applications is discussed.

  3. Ulcerative colitis six years after colon cancer: only a coincidence?

    Science.gov (United States)

    Sakellakis, Minas; Makatsoris, Thomas; Gkermpesi, Maria; Peroukidis, Stavros; Kalofonos, Haralabos

    2014-01-01

    The association between inflammatory bowel disease and colorectal cancer is well known. Ulcerative colitis is a risk factor for the development of colorectal cancer, and this risk increases with the activity and duration of bowel inflammation. Here we describe the case of a 52-year-old man who developed ulcerative colitis 6 years after the diagnosis and treatment of colon cancer. Although this could be a coincidence, there could be additional possibilities, like pre-existence of quiescent colitis, late effect of therapy, or maybe the existence of common pathogenetic factors contributing to the development of ulcerative colitis and colorectal cancer. PMID:24855393

  4. Radiative Corrections to Polarized Inelastic Scattering in Coincidence

    Energy Technology Data Exchange (ETDEWEB)

    Igor Akushevich; Andrei Afanasev; G.I. Gakh; Mykola Merenkov

    2001-09-01

    The complete analysis of the model-independent leading radiative corrections to cross-section and polarization observables in semi-inclusive deep-inelastic electron-nucleus scattering with detection of a proton and scattered electron in coincidence has been performed. The basis of the calculations consists of the Drell-Yan like representation in electrodynamics for both spin-independent and spin-dependent parts of the cross-section in terms of the electron structure functions. The applications to the polarization transfer effect from longitudinally polarized electron beam to detected proton as well as to scattering by the polarized target are considered.

  5. Coincidence corrected efficiency calibration of Compton-suppressed HPGe detectors

    Energy Technology Data Exchange (ETDEWEB)

    Aucott, Timothy [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Brand, Alexander [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); DiPrete, David [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-04-20

    The authors present a reliable method to calibrate the full-energy efficiency and the coincidence correction factors using a commonly-available mixed source gamma standard. This is accomplished by measuring the peak areas from both summing and non-summing decay schemes and simultaneously fitting both the full-energy efficiency, as well as the total efficiency, as functions of energy. By using known decay schemes, these functions can then be used to provide correction factors for other nuclides not included in the calibration standard.

  6. Absolute cross-sections from X-{gamma} coincidence measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lemasson, A. [GANIL, CEA/DSM - CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France); Shrivastava, A. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Navin, A. [GANIL, CEA/DSM - CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France)], E-mail: navin@ganil.fr; Rejmund, M. [GANIL, CEA/DSM - CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France); Nanal, V. [Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Mumbai 400005 (India); Bhattacharyya, S. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064 (India); Chatterjee, A.; Kailas, S.; Mahata, K.; Parkar, V.V. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Pillay, R.G. [Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Mumbai 400005 (India); Ramachandran, K.; Rout, P.C. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2009-01-11

    An activation technique using coincidences between characteristic X-rays and {gamma}-rays to obtain absolute cross-sections is described. This method is particularly useful in the case of nuclei that decay by electron capture. In addition to the reduction of possible contamination, an improved detection sensitivity is achieved as compared to inclusive measurements, thereby allowing the extraction of absolute fusion cross-sections in the nano-barn range. Results of this technique for {sup 6}Li+{sup 198}Pt system, at energies around the Coulomb barrier are described. Future applications with low intensity radioactive ion beams are also discussed.

  7. Coincident systemic lupus erythematosus and psoriasis vulgaris: a case report.

    Science.gov (United States)

    Wang, Y; Da, G; Yu, Y; Han, J; Li, H

    2015-12-01

    Psoriasis vulgaris is an autoimmune chronic inflammatory skin disease, but its association with other typical autoimmune disease such as systemic lupus erythematosus has only occasionally been reported. We presented a 25-year-old female who developed systemic lupus erythematosus associated with psoriasis vulgaris. Her conditions were in good control after she got administration of prednisolone (5 mg/day) and Tripterygium Wilfordii Hook (20 mg/day). It is necessary to integrate past history and physical examination to diagnose coincident SLE and psoriasis, and combined treatment with prednisolone and Tripterygium Wilfordii Hook proves effective.

  8. Spectroscopy of fission fragments using prompt-delayed coincidence technique

    Indian Academy of Sciences (India)

    R Palit; S Biswas

    2015-09-01

    The time-stamp structure of the digital data acquisition system of the Indian National Gamma Array (INGA) has been utilized to carry out prompt-delayed coincidence technique for the spectroscopic study of fission fragments. This technique was found to be useful to determine the states above the long-lived isomer (with half-life up to ∼5 s), present in the fission fragments. The angular correlation of -rays, emitted by the fission fragments, has also been used in the present INGA geometry to determine the spins of the de-exciting states.

  9. Joint spectrum of photon pairs measured by coincidence Fourier spectroscopy

    CERN Document Server

    Wasilewski, W; Kolenderski, P; Banaszek, K; Radzewicz, C; Wasilewski, Wojciech; Wasylczyk, Piotr; Kolenderski, Piotr; Banaszek, Konrad; Radzewicz, Czeslaw

    2005-01-01

    We propose and demonstrate a method for measuring the joint spectrum of photon pairs via Fourier spectroscopy. The biphoton spectral intensity is computed from a two-dimensional interferogram of coincidence counts. The method has been implemented for a type-I downconversion source using a pair of common-path Mach-Zender interferometers based on Soleil compensators. The experimental results agree well with calculated frequency correlations that take into account the effects of coupling into single-mode fibers. The Fourier method is advantageous over scanning spectrometry when detectors exhibit high dark count rates leading to dominant additive noise.

  10. 2010 American Conference on Neutron Scattering (ACNS 2010)

    Energy Technology Data Exchange (ETDEWEB)

    Billinge, Simon

    2011-06-17

    The ACNS provides a focal point for the national neutron user community to strengthen ties within this diverse group, while at the same time promoting neutron research among colleagues in related disciplines identified as “would-be” neutron users. The American Conference on Neutron Scattering thus serves a dual role as a national user meeting and a scientific meeting. As a venue for scientific exchange, the ACNS showcases recent results and provides forums for scientific discussion of neutron research in diverse fields such as hard and soft condensed matter, liquids, biology, magnetism, engineering materials, chemical spectroscopy, crystal structure, and elementary excitations, fundamental physics and development of neutron instrumentation through a combination of invited talks, contributed talks and poster sessions. As a “super-user” meeting, the ACNS fulfills the main objectives of users' meetings previously held periodically at individual national neutron facilities, with the advantage of a larger and more diverse audience. To this end, each of the major national neutron facilities (NIST, LANSCE, HFIR and SNS) have an opportunity to exchange information and update users, and potential users, of their facility. This is also an appropriate forum for users to raise issues that relate to the facilities. For many of the national facilities, this super-user meeting should obviate the need for separate user meetings that tax the time, energy and budgets of facility staff and the users alike, at least in years when the ACNS is held. We rely upon strong participation from the national facilities. The NSSA intends that the American Conference on Neutron Scattering (ACNS) will occur approximately every two years, but not in years that coincide with the International or European Conferences on Neutron Scattering. The ACNS is to be held in association with one of the national neutron centers in a rotating sequence, with the host facility providing local

  11. Status of spallation neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Oyama, Yukio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-03-01

    Existing and planned facilities using proton accelerator driven spallation neutron source are reviewed. These include new project of neutron science proposed from Japan Atomic Energy Research Institute. The present status of facility requirement and accelerator technology leads us to new era of neutron science such as neutron scattering research and nuclear transmutation study using very intense neutron source. (author)

  12. Radio transient following FRB 150418: afterglow or coincident AGN flare?

    CERN Document Server

    Li, Ye

    2016-01-01

    Recently, Keane et al. reported the discovery of a fading radio transient following FRB 150418, and interpreted it as the afterglow of the FRB. Williams \\& Berger, on the other hand, suggested that the radio transient is analogous to a group of variable radio sources, so that it could be a coincident AGN flare in the observational beam of the FRB. A new observation with VLA showed a re-brightening, which is consistent with the AGN picture. Here, using the radio survey data of Ofek et al., we statistically examine the chance coincidence probability to produce an event like the FRB 150418 transient. We find that the probabilities to produce a variable radio transient with at least the same variability amplitude and signal-to-noise ratio as the FRB 150415 transient, without and with the VLA point, are $P_1 \\sim 6 \\times 10^{-4}$ and $P_1 \\sim 2 \\times 10^{-3}$, respectively. In addition, the chance probability to have a fading transient detected following a random time (FRB time) is less than $P_2 \\sim 10^{-...

  13. Photoelectron-Auger electron coincidence study for condensed matter

    Energy Technology Data Exchange (ETDEWEB)

    Stefani, G. [Department of Physics and Unita' INFM, University Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy)]. E-mail: stefani@fis.uniroma3.it; Gotter, R. [National Laboratory TASC-INFM, Area Science Park, SS 14 Km 163.5, Basovizza, I-34012 Trieste (Italy); Ruocco, A. [Department of Physics and Unita INFM, University Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy); Offi, F. [Department of Physics and Unita INFM, University Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy); Pieve, F. Da [Department of Physics and Unita INFM, University Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy); Iacobucci, S. [IMIP-CNR Area della Ricerca di Roma, via Salaria Km 29, 3 Montelibretti (Italy); Morgante, A. [National Laboratory TASC-INFM, Area Science Park, SS 14 Km 163.5, Basovizza, I-34012 Trieste (Italy); Verdini, A. [National Laboratory TASC-INFM, Area Science Park, SS 14 Km 163.5, Basovizza, I-34012 Trieste (Italy); Liscio, A. [IMIP-CNR Area della Ricerca di Roma, via Salaria Km 29, 3 Montelibretti (Italy); Yao, H. [Department of Physics and Astronomy and Laboratory of Surface Modification, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08855 (United States); Bartynski, R.A. [Department of Physics and Astronomy and Laboratory of Surface Modification, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08855 (United States)

    2004-12-01

    Advances in materials science have produced a wide array of new solid-state systems with tunable properties and previously unattainable combinations of phenomena that hold the promise of entirely new approaches to technological applications. Invariably, these new materials are increasingly complex and include a large number of constituents in a variety of chemical states. Entirely new theoretical and experimental approaches are needed to gain the insights necessary for intelligent engineering of these materials. In the past 20 years, a steadily increasing number of electron-electron coincidence experiments on atoms and molecules have demonstrated the capability of investigating complicated systems with sensitivity and specificity well beyond the limits imposed by conventional electron spectroscopies. Over the past decade or so, Auger-photoelectron coincidence spectroscopy (APECS) has emerged as a powerful technique for obtaining detailed information about complex materials systems. Moreover, the recent advent of angle-resolved (AR)-APECS has introduced a new level of discrimination in studying the distribution of electrons photoemitted from complex systems. In this review, we describe the basic ideas behind APECS and discuss a study of the SiO{sub 2} system as an example of the unique information this technique can provide. We then introduce the concept of AR-APECS, explain its novel state and angular momentum selectivity that can be used to disentangle information about complex systems that is hidden to conventional spectroscopies. Examples of AR-APECS measurements from Cu, Ge, and graphite that exemplify the capabilities of this technique are presented.

  14. CSF biomarkers cutoffs: the importance of coincident neuropathological diseases.

    Science.gov (United States)

    Toledo, Jon B; Brettschneider, Johannes; Grossman, Murray; Arnold, Steven E; Hu, William T; Xie, Sharon X; Lee, Virginia M-Y; Shaw, Leslie M; Trojanowski, John Q

    2012-07-01

    The effects of applying clinical versus neuropathological diagnosis and the inclusion of cases with coincident neuropathological diagnoses have not been assessed specifically when studying cerebrospinal fluid (CSF) biomarker classification cutoffs for patients with neurodegenerative diseases that cause dementia. Thus, 142 neuropathologically diagnosed neurodegenerative dementia patients [71 Alzheimer's disease (AD), 29 frontotemporal lobar degeneration (FTLD), 3 amyotrophic lateral sclerosis, 7 dementia with Lewy bodies, 32 of which cases also had coincident diagnoses] were studied. 96 % had enzyme-linked immunosorbant assay (ELISA) CSF data and 77 % had Luminex CSF data, with 43 and 46 controls for comparison, respectively. Aβ(42), total, and phosphorylated tau(181) were measured. Clinical and neuropathological diagnoses showed an 81.4 % overall agreement. Both assays showed high sensitivity and specificity to classify AD subjects against FTLD subjects and controls, and moderate sensitivity and specificity for classifying FTLD subjects against controls. However, among the cases with neuropathological diagnoses of AD plus another pathology (26.8 % of the sample), 69.4 % (ELISA) and 96.4 % (Luminex) were classified as AD according to their biomarker profiles. Use of clinical diagnosis instead of neuropathological diagnosis led to a 14-17 % underestimation of the biomarker accuracy. These results show that while CSF Aβ and tau assays are useful for diagnosis of AD and neurodegenerative diseases even at MCI stages, CSF diagnostic analyte panels that establish a positive diagnosis of Lewy body disease and FTLD are also needed, and must be established based on neuropathological rather than clinical diagnoses.

  15. Coincidence-anticipation timing requirements are different in racket sports.

    Science.gov (United States)

    Akpinar, Selçuk; Devrilmez, Erhan; Kirazci, Sadettin

    2012-10-01

    The aim of this study was to compare the coincidence-anticipation timing accuracy of athletes of different racket sports with various stimulus velocity requirements. Ninety players (15 girls, 15 boys for each sport) from tennis (M age = 12.4 yr., SD = 1.4), badminton (M age = 12.5 yr., SD = 1.4), and table tennis (M age = 12.4 yr., SD = 1.2) participated in this study. Three different stimulus velocities, low, moderate, and high, were used to simulate the velocity requirements of these racket sports. Tennis players had higher accuracy when they performed under the low stimulus velocity compared to badminton and table tennis players. Badminton players performed better under the moderate speed comparing to tennis and table tennis players. Table tennis players had better performance than tennis and badminton players under the high stimulus velocity. Therefore, visual and motor systems of players from different racket sports may adapt to a stimulus velocity in coincidence-anticipation timing, which is specific to each type of racket sports.

  16. Cellulose metabolism in plants.

    Science.gov (United States)

    Hayashi, Takahisa; Yoshida, Kouki; Park, Yong Woo; Konishi, Teruko; Baba, Kei'ichi

    2005-01-01

    Many bacterial genomes contain a cellulose synthase operon together with a cellulase gene, indicating that cellulase is required for cellulose biosynthesis. In higher plants, there is evidence that cell growth is enhanced by the overexpression of cellulase and prevented by its suppression. Cellulase overexpression could modify cell walls not only by trimming off the paracrystalline sites of cellulose microfibrils, but also by releasing xyloglucan tethers between the microfibrils. Mutants for membrane-anchored cellulase (Korrigan) also show a typical phenotype of prevention of cellulose biosynthesis in tissues. All plant cellulases belong to family 9, which endohydrolyzes cellulose, but are not strong enough to cause the bulk degradation of cellulose microfibrils in a plant body. It is hypothesized that cellulase participates primarily in repairing or arranging cellulose microfibrils during cellulose biosynthesis in plants. A scheme for the roles of plant cellulose and cellulases is proposed.

  17. Metal hyperaccumulation in plants.

    Science.gov (United States)

    Krämer, Ute

    2010-01-01

    During the history of life on Earth, tectonic and climatic change repeatedly generated large territories that were virtually devoid of life and exhibited harsh environmental conditions. The ability of a few specialist pioneer plants to colonize such hostile environments was thus of paramount ecological importance for the continuous maintenance of primary production over time. Yet, we know very little about how extreme traits evolve and function in plants. Recent breakthroughs have given first insights into the molecular basis underlying the complex extreme model trait of metal hyperaccumulation and associated metal hypertolerance. This review gives an introduction into the hyperaccumulator research field and its history; provides an overview of hyperaccumulator germplasm; describes the state of the art of our understanding of the physiological, molecular, and genetic basis underlying metal hyperaccumulation and its evolution; and highlights future research needs and opportunities.

  18. Memristors in plants.

    Science.gov (United States)

    Volkov, Alexander G; Tucket, Clayton; Reedus, Jada; Volkova, Maya I; Markin, Vladislav S; Chua, Leon

    2014-01-01

    We investigated electrical circuitry of the Venus flytrap, Mimosa pudica and Aloe vera. The goal was to discover if these plants might have a new electrical component--a resistor with memory. This element was postulated recently and the researchers were looking for its presence in different systems. The analysis was based on cyclic current-voltage characteristic where the resistor with memory should manifest itself. We found that the electrostimulation of plants by bipolar sinusoidal or triangle periodic waves induces electrical responses in the Venus flytrap, Mimosa pudica and Aloe vera with fingerprints of memristors. Tetraethylammonium chloride, an inhibitor of voltage gated K(+) channels, transforms a memristor to a resistor in plant tissue. Our results demonstrate that a voltage gated K(+) channel in the excitable tissue of plants has properties of a memristor. This study can be a starting point for understanding mechanisms of memory, learning, circadian rhythms, and biological clocks.

  19. Neutron sources and applications

    Energy Technology Data Exchange (ETDEWEB)

    Price, D.L. [ed.] [Argonne National Lab., IL (United States); Rush, J.J. [ed.] [National Inst. of Standards and Technology, Gaithersburg, MD (United States)

    1994-01-01

    Review of Neutron Sources and Applications was held at Oak Brook, Illinois, during September 8--10, 1992. This review involved some 70 national and international experts in different areas of neutron research, sources, and applications. Separate working groups were asked to (1) review the current status of advanced research reactors and spallation sources; and (2) provide an update on scientific, technological, and medical applications, including neutron scattering research in a number of disciplines, isotope production, materials irradiation, and other important uses of neutron sources such as materials analysis and fundamental neutron physics. This report summarizes the findings and conclusions of the different working groups involved in the review, and contains some of the best current expertise on neutron sources and applications.

  20. Prototype Stilbene Neutron Collar

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, M. K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Shumaker, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Snyderman, N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Verbeke, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wong, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-26

    A neutron collar using stilbene organic scintillator cells for fast neutron counting is described for the assay of fresh low enriched uranium (LEU) fuel assemblies. The prototype stilbene collar has a form factor similar to standard He-3 based collars and uses an AmLi interrogation neutron source. This report describes the simulation of list mode neutron correlation data on various fuel assemblies including some with neutron absorbers (burnable Gd poisons). Calibration curves (doubles vs 235U linear mass density) are presented for both thermal and fast (with Cd lining) modes of operation. It is shown that the stilbene collar meets or exceeds the current capabilities of He-3 based neutron collars. A self-consistent assay methodology, uniquely suited to the stilbene collar, using triples is described which complements traditional assay based on doubles calibration curves.

  1. The DIORAMA Neutron Emitter

    Energy Technology Data Exchange (ETDEWEB)

    Terry, James Russell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-05

    Emission of neutrons in a given event is modeled by the DioramaEmitterNeutron object, a subclass of the abstract DioramaEmitterModule object. The GenerateEmission method of this object is the entry point for generation of a neutron population for a given event. Shown in table 1, this method requires a number of parameters to be defined in the event definition.

  2. Observation of a low-lying neutron-unbound state in 19C

    CERN Document Server

    Thoennessen, M; Badger, N S; Baumann, T; Bazin, D; Bennett, M; Brown, J; Christian, G; DeYoung, P A; Finck, J E; Gardner, M; Hook, E A; Luther, B; Meyer, D A; Mosby, M; Rogers, W F; Smith, J K; Spyrou, A; Strongman, M J

    2013-01-01

    Proton removal reactions from a secondary 22N beam were utilized to populate unbound states in neutron-rich carbon isotopes. Neutrons were measured with the Modular Neutron Array (MoNA) in coincidence with carbon fragments. A resonance with a decay energy of 76(14) keV was observed in the system 18C+n corresponding to a state in 19C at an excitation energy of 653(95)keV. This resonance could correspond to the first 5/2+ state which was recently speculated to be unbound in order to describe 1n and 2n removal cross section measurements from 20C.

  3. Neutron scattering. Experiment manuals

    Energy Technology Data Exchange (ETDEWEB)

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2014-07-01

    The following topics are dealt with: The thermal triple-axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot-single-crystal diffractometer HEiDi, the three-axis spectrometer PANDA, the backscattering spectrometer SPHERES, the DNS neutron-polarization analysis, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering at KWS-1 and KWS-2, a very-small-angle neutron scattering diffractometer with focusing mirror, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  4. Neutron-emission measurements at a white neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Haight, Robert C [Los Alamos National Laboratory

    2010-01-01

    Data on the spectrum of neutrons emittcd from neutron-induced reactions are important in basic nuclear physics and in applications. Our program studies neutron emission from inelastic scattering as well as fission neutron spectra. A ''white'' neutron source (continuous in energy) allows measurements over a wide range of neutron energies all in one experiment. We use the tast neutron source at the Los Alamos Neutron Science Center for incident neutron energies from 0.5 MeV to 200 MeV These experiments are based on double time-of-flight techniques to determine the energies of the incident and emitted neutrons. For the fission neutron measurements, parallel-plate ionization or avalanche detectors identify fission in actinide samples and give the required fast timing pulse. For inelastic scattering, gamma-ray detectors provide the timing and energy spectroscopy. A large neutron-detector array detects the emitted neutrons. Time-of-flight techniques are used to measure the energies of both the incident and emitted neutrons. Design considerations for the array include neutron-gamma discrimination, neutron energy resolution, angular coverage, segmentation, detector efficiency calibration and data acquisition. We have made preliminary measurements of the fission neutron spectra from {sup 235}U, {sup 238}U, {sup 237}Np and {sup 239}Pu. Neutron emission spectra from inelastic scattering on iron and nickel have also been investigated. The results obtained will be compared with evaluated data.

  5. The host galaxy and environment of a neutron star merger

    CERN Document Server

    Postigo, A de Ugarte; Rowlinson, A; Garcia-Benito, R; Levan, A J; Gorosabel, J; Goldoni, P; Schulze, S; Zafar, T; Wiersema, K; Sanchez-Ramirez, R; Melandri, A; D'Avanzo, P; Oates, S; D'Elia, V; De Pasquale, M; Kruehler, T; van der Horst, A J; Xu, D; Watson, D; Piranomonte, S; Vergani, S; Milvang-Jensen, B; Kaper, L; Malesani, D; Fynbo, J P U; Cano, Z; Covino, S; Flores, H; Greiss, S; Hammer, F; Hartoog, O E; Hellmich, S; Heuser, C; Hjorth, J; Jakobsson, P; Mottola, S; Sparre, M; Sollerman, J; Tagliaferri, G; Tanvir, N R; Vestergaard, M; Wijers, R A M J

    2013-01-01

    The mergers of neutron stars have been predicted to cause an r-process supernova - a luminous near-infrared transient powered by the radioactive decay of freshly formed heavy metals. An r-process supernova, or kilonova, has recently been discovered coincident with the short-duration gamma-ray burst GRB 130603B, simultaneously confirming the widely-held theory of the origin of most short-durations GRBs in neutron star mergers. We report here the absorption spectrum of the afterglow of this GRB. From it we determine the redshift of the burst and the properties of the host galaxy and the environment in which the merger occurred. The merger is not associated with the most star-forming region of the galaxy; however, it did occur in a dense region, implying a rapid merger or a low natal kick velocity for the neutron star binary.

  6. Sub-wavelength bubble in photon coincidence detection

    CERN Document Server

    Liu, Ruifeng; Zhou, Yu; Gao, Hong; Li, Fuli

    2013-01-01

    Sub-wavelength interference has a potential application in lithography to beat the classical Rayleigh limit of resolution. We carefully study the second-order correlation theory and find there is a bubble of sub-wavelength interference in photon coincidence detection. A Young's double-slit experiment with thermal light is carried out to test the second-order correlation pattern. The result shows that when different scanning ways of two point detectors are chosen, we can get arbitrary-wavelength interference patterns. We then give a theoretical explanation to this surprising result, and find this explanation is also suitable for the result by using entangled light. Furthermore, the question of whether this kind of arbitrary-wavelength interference patterns can be used in quantum lithography is also analyzed.

  7. Ulcerative colitis six years after colon cancer: only a coincidence?

    Directory of Open Access Journals (Sweden)

    Sakellakis M

    2014-04-01

    Full Text Available Minas Sakellakis,1 Thomas Makatsoris,1 Maria Gkermpesi,2 Stavros Peroukidis,1 Haralabos Kalofonos11Division of Oncology, Department of Medicine, 2Department of Pathology, University, Hospital of Patras, Patras, GreeceAbstract: The association between inflammatory bowel disease and colorectal cancer is well known. Ulcerative colitis is a risk factor for the development of colorectal cancer, and this risk increases with the activity and duration of bowel inflammation. Here we describe the case of a 52-year-old man who developed ulcerative colitis 6 years after the diagnosis and treatment of colon cancer. Although this could be a coincidence, there could be additional possibilities, like pre-existence of quiescent colitis, late effect of therapy, or maybe the existence of common pathogenetic factors contributing to the development of ulcerative colitis and colorectal cancer.Keywords: ulcerative, colitis, colorectal, cancer, inflammation

  8. Cardiac Rhabdomyomas and Congenital Hypothyroidism: A Coincidence or Hamartia

    Directory of Open Access Journals (Sweden)

    Anand Agarwal

    2015-11-01

    Full Text Available Cardiac rhabdomyomas are the most common primary cardiac tumors in children. These tumors are generally asymptomatic, although they may be associated with neonatal tuberous sclerosis complex. Despite the fact that thyroid dysfunction rarely occurs in tuberous sclerosis, papillary adenomas (hamartomas of the thyroid gland have been reported in a number of autopsies. Herein, we present the case of an infant with tuberous sclerosis, congenital hypothyroidism and multiple cardiac rhabdomyomas, leading to atrioventricular node dysfunction. Considering the rarity of this co-occurrence, we decided to report the present case. The co-occurrence of these two disorders in one patient may be a mere coincidence or related to hamartoma of the thyroid gland as a consequence of tuberous sclerosis gene products.

  9. Serendipity in Cancer Drug Discovery: Rational or Coincidence?

    Science.gov (United States)

    Prasad, Sahdeo; Gupta, Subash C; Aggarwal, Bharat B

    2016-06-01

    Novel drug development leading to final approval by the US FDA can cost as much as two billion dollars. Why the cost of novel drug discovery is so expensive is unclear, but high failure rates at the preclinical and clinical stages are major reasons. Although therapies targeting a given cell signaling pathway or a protein have become prominent in drug discovery, such treatments have done little in preventing or treating any disease alone because most chronic diseases have been found to be multigenic. A review of the discovery of numerous drugs currently being used for various diseases including cancer, diabetes, cardiovascular, pulmonary, and autoimmune diseases indicates that serendipity has played a major role in the discovery. In this review we provide evidence that rational drug discovery and targeted therapies have minimal roles in drug discovery, and that serendipity and coincidence have played and continue to play major roles. The primary focus in this review is on cancer-related drug discovery.

  10. Commentary on Bayesian coincidence assessment (cross-matching)

    CERN Document Server

    Loredo, Thomas J

    2012-01-01

    This paper is an invited commentary on Tamas Budavari's presentation, "On statistical cross-identification in astronomy," for the Statistical Challenges in Modern Astronomy V conference held at Pennsylvania State University in June 2011. I begin with a brief review of previous work on probabilistic (Bayesian) assessment of directional and spatio-temporal coincidences in astronomy (e.g., cross-matching or cross-identification of objects across multiple catalogs). Then I discuss an open issue in the recent innovative work of Budavari and his colleagues on large-scale probabilistic cross-identification: how to assign prior probabilities that play an important role in the analysis. With a simple toy problem, I show how Bayesian multilevel modeling (hierarchical Bayes) provides a principled framework that justifies and generalizes pragmatic rules of thumb that have been successfully used by Budavari's team to assign priors.

  11. Gamma Efficiency Simulations towards Coincidence Measurements for Fusion Cross Sections

    Science.gov (United States)

    Heine, M.; Courtin, S.; Fruet, G.; Jenkins, D. G.; Montanari, D.; Morris, L.; Regan, P. H.; Rudigier, M.; Symochko, D.

    2016-10-01

    With the experimental station STELLA (STELlar LAboratory) we will measure fusion cross sections of astrophysical relevance making use of the coincident detection of charged particles and gamma rays for background reduction. For the measurement of gamma rays from the de-excitation of fusion products a compact array of 36 UK FATIMA LaBr3 detectors is designed based on efficiency studies with Geant4. The photo peak efficiency in the region of interest compares to other gamma detection systems used in this field. The features of the internal decay of 138La is used in a background study to obtain an online calibration of the gamma detectors. Background data are fit to the Monte Carlo model of the self activity assuming crude exponential behavior of external background. Accuracy in the region of interest is of the order of some keV in this first study.

  12. Evaluation of Am-Li neutron spectra data for active well type neutron multiplicity measurements of uranium

    Science.gov (United States)

    Goddard, Braden; Croft, Stephen; Lousteau, Angela; Peerani, Paolo

    2016-09-01

    Safeguarding nuclear material is an important and challenging task for the international community. One particular safeguards technique commonly used for uranium assay is active neutron correlation counting. This technique involves irradiating unused uranium with (α, n) neutrons from an Am-Li source and recording the resultant neutron pulse signal which includes induced fission neutrons. Although this non-destructive technique is widely employed in safeguards applications, the neutron energy spectra from an Am-Li sources is not well known. Several measurements over the past few decades have been made to characterize this spectrum; however, little work has been done comparing the measured and theoretical spectra of various Am-Li sources to each other. This paper examines fourteen different Am-Li spectra, focusing on how these spectra affect simulated neutron multiplicity results using the code Monte Carlo N-Particle eXtended (MCNPX). Two measurement and simulation campaigns were completed using Active Well Coincidence Counter (AWCC) detectors and uranium standards of varying enrichment. The results of this work indicate that for standard AWCC measurements, the fourteen Am-Li spectra produce similar doubles and triples count rates. The singles count rates varied by as much as 20% between the different spectra, although they are usually not used in quantitative analysis, being dominated by scattering which is highly dependent on item placement.

  13. Praseodymium activation detector for measuring bursts of 14 MeV neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Meehan, Tim, E-mail: meehanbt@nv.doe.go [National Security Technologies, LLC, P.O. Box 98521, North Las Vegas, NV 89030 (United States); Hagen, E.C. [National Security Technologies, LLC, P.O. Box 98521, North Las Vegas, NV 89030 (United States); Ruiz, C.L.; Cooper, G.W. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185 (United States)

    2010-08-21

    A new, accurate, neutron activation detection scheme for measuring pulsed neutrons has been designed and tested. The detection system is sensitive to neutrons with energies above 10 MeV; importantly, it is insensitive to gamma radiation <10 MeV and to lower-energy (e.g., fission and thermal) neutrons. It is based upon the use of {sup 141}Pr, an element that has a single, naturally occurring isotope, a significant n,2n cross-section, and decays by positron emission that result in two coincident 511 keV photons. Neutron fluences are thus inferred by relating measured reaction product decay activity to fluence. Specific sample activity is measured using the sum-peak method to count gamma-ray coincidences from the annihilation of the positron decay products. The system was tested using 14 and 2.45 MeV neutron bursts produced by NSTec Dense Plasma Focus Laboratory fusion sources. Lead, copper, beryllium, and silver activation detectors were compared. The detection method allows measurement of 14 MeV neutron yield with a total error of {approx}18%.

  14. Coincident photoelectron spectroscopy on superconductors; Koinzidente Photoelektronenspektroskopie an Supraleitern

    Energy Technology Data Exchange (ETDEWEB)

    Voss, Stefan

    2011-07-01

    Aim of the performed experiments of this thesis was to attempt to detect Cooper pairs as carriers of the superconducting current directly by means of the photoelectric effect. The method of the coincident photoelectron spectroscopy aims thereby at the detection of two coherently emitted electrons by the interaction with a photon. Because electrostatic analyzers typically cover only a very small spatial angle, which goes along with very low coincidence rates, in connection with this thesis a time-of-flight projection system has been developed, which maps nearly the whole spatial angle on a position-resolving detector. The pulsed light source in form of special synchrotron radiation necessary for the measurement has been adjusted so weak, that only single photons could arrive at the sample. Spectroscoped were beside test measurements on silver layers both a lead monocrystal as representative of the classical BCS superconductors and monocrystalline Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} from the family of the high-temperature superconductors. With excitation energies up to 40 eV could be shown that sufficiently smooth and clean surfaces in the superconducting phase exhibit within the resolving power of about 0.5 eV no recognizable differences in comparison to the normally conducting phase. Beside these studies furthermore the simple photoemission at the different samples and especially in the case of the lead crystal is treated, because here no comparable results are known. Thereby the whole momentum space is discussed and the Fermi surface established as three-dimensional model, by means of which the measurement results are discussed. in the theoretical descriptions different models for the Cooper-pair production are presented, whereby to the momentum exchange with the crystal a special role is attributed, because this can only occur in direct excitations via discrete lattice vectors.

  15. Lipid hydroperoxides in plants.

    Science.gov (United States)

    Griffiths, G; Leverentz, M; Silkowski, H; Gill, N; Sánchez-Serrano, J J

    2000-12-01

    Hydroperoxides are the primary oxygenated products of polyunsaturated fatty acids and were determined spectrophotometrically based on their reaction with an excess of Fe2+ at low pH in the presence of the dye Xylenol Orange. Triphenylphosphine-mediated hydroxide formation was used to authenticate the signal generated by the hydroperoxides. The method readily detected lipid peroxidation in a range of plant tissues including Phaseolus hypocotyls (26 +/- 5 nmol.g of fresh weight(-1); mean +/- S.D.), Alstroemeria floral tissues (sepals, 66+/-13 nmol.g of fresh weight(-1); petals, 49+/-6 nmol.g of fresh weight(-1)), potato leaves (334+/-75 nmol.g of fresh weight(-1)), broccoli florets (568+/-68 nmol.g of fresh weight(-1)) and Chlamydomonas cells (602+/-40 nmol.g of wet weight(-1)). Relative to the total fatty acid content of the tissues, the percentage hydroperoxide content was within the range of 0.6-1.7% for all tissue types (photosynthetic and non-photosynthetic) and represents the basal oxidation level of membrane fatty acids in plant cells. Leaves of transgenic potato with the fatty acid hydroperoxide lyase enzyme expressed in the antisense orientation were elevated by 38%, indicating a role for this enzyme in the maintenance of cellular levels of lipid hydroperoxides.

  16. Polyamines in plant physiology

    Science.gov (United States)

    Galston, A. W.; Sawhney, R. K.

    1990-01-01

    The diamine putrescine, the triamine spermidine, and the tetramine spermine are ubiquitous in plant cells, while other polyamines are of more limited occurrence. Their chemistry and pathways of biosynthesis and metabolism are well characterized. They occur in the free form as cations, but are often conjugated to small molecules like phenolic acids and also to various macromolecules. Their titer varies from approximately micromolar to more than millimolar, and depends greatly on environmental conditions, especially stress. In cereals, the activity of one of the major polyamine biosynthetic enzymes, arginine decarboxylase, is rapidly and dramatically increased by almost every studied external stress, leading to 50-fold or greater increases in putrescine titer within a few hours. The physiological significance of this increase is not yet clear, although most recent work suggests an adaptive, protective role. Polyamines produced through the action of ornithine decarboxylase, by contrast, seem essential for DNA replication and cell division. The application of exogenous polyamines produces effects on patterns of senescence and morphogenesis, suggesting but not proving a regulatory role for polyamines in these processes. The evidence for such a regulatory role is growing.

  17. Engineered minichromosomes in plants.

    Science.gov (United States)

    Birchler, James A

    2015-02-01

    Engineered minichromosomes have been produced in several plant species via telomere-mediated chromosomal truncation. This approach bypasses the complications of the epigenetic nature of centromere function in plants, which has to date precluded the production of minichromosomes by the re-introduction of centromere sequences to a plant cell. Genes to be added to a cleaved chromosome are joined together with telomere repeats on one side. When these constructs are introduced into plant cells, the genes are ligated to the broken chromosomes but the telomere repeats will catalyze the formation of a telomere on the other end cutting the chromosome at that point. Telomere-mediated chromosomal truncation is sufficiently efficient that very small chromosomes can be generated consisting of basically the endogenous centromere and the added transgenes. The added transgenes provide a platform onto which it should be possible to assemble a synthetic chromosome to specification. Combining engineered minichromosomes with doubled haploid breeding should greatly expedite the transfer of transgenes to new lines and to test the interaction of transgenes in new background genotypes. Potential basic and applied applications of synthetic chromosomes are discussed.

  18. Paramutation phenomena in plants.

    Science.gov (United States)

    Pilu, Roberto

    2015-08-01

    Paramutation is a particular epigenetic phenomenon discovered in Zea mays by Alexander Brink in the 1950s, and then also found in other plants and animals. Brink coined the term paramutation (from the Greek syllable "para" meaning beside, near, beyond, aside) in 1958, with the aim to differentiate paramutation from mutation. The peculiarity of paramutation with respect to other gene silencing phenomena consists in the ability of the silenced allele (named paramutagenic) to silence the other allele (paramutable) present in trans. The newly silenced (paramutated) allele remains stable in the next generations even after segregation from the paramutagenic allele and acquires paramutagenic ability itself. The inheritance behaviour of these epialleles permits a fast diffusion of a particular gene expression level/phenotype in a population even in the absence of other evolutionary influences, thus breaking the Hardy-Weinberg law. As with other gene silencing phenomena such as quelling in the fungus Neurospora crassa, transvection in Drosophila, co-suppression and virus-induced gene silencing (VIGS) described in transgenic plants and RNA interference (RNAi) in the nematode Caenorhabditis elegans, paramutation occurs without changes in the DNA sequence. So far the molecular basis of paramutation remains not fully understood, although many studies point to the involvement of RNA causing changes in DNA methylation and chromatin structure of the silenced genes. In this review I summarize all paramutation phenomena described in plants, focusing on the similarities and differences between them.

  19. {sup 6}Li foil scintillation sandwich thermal neutron detector

    Energy Technology Data Exchange (ETDEWEB)

    Ianakiev, K.D., E-mail: ianakiev@lanl.gov [Los Alamos National Laboratory, MS E540, Los Alamos, NM 87545 (United States); Swinhoe, M.T.; Favalli, A.; Chung, K.; MacArthur, D.W. [Los Alamos National Laboratory, MS E540, Los Alamos, NM 87545 (United States)

    2011-10-01

    Increasing needs for neutron detection and limited supply of {sup 3}He have led to the need for replacement neutron detection technology. This paper presents the design and initial results for a neutron detector ({sup 6}Li foil scintillator sandwich) that uses lithium metal foil to detect thermal neutrons. The reaction products, primarily triton, deposit most of their energy in thin scintillator films and create light pulses. Gamma rays can deposit only a small amount of energy in the thin films and so produce only very small light pulses. Lithium is preferable to boron in this application because triton escapes from lithium more easily than does the alpha particle from boron, allowing the use of thicker films and hence greater efficiency. In addition, triton has a higher light output in the scintillator than the boron alpha particle. Lithium metal is preferable to a lithium compound, such as lithium fluoride, because the number of tritons that escape from the metal is greater for the same amount of lithium. Monte Carlo simulations show that good efficiency values can be achieved with reasonably sized detectors, values that are greater than that of comparable {sup 3}He systems for portal monitors. In addition, simulations of a neutron coincidence counting concept show high counting efficiency and short die-away time (16 {mu}s), which imply better performance than that of the high-level neutron coincidence counter (HLNCC)-II. Initial experimental measurements on a prototype detector using alpha particles (having similar light output to the expected tritons) show good light collection and transport properties.

  20. Evidence for beta -delayed neutron emission from /sup 31/Mg and /sup 32/Mg

    CERN Document Server

    Zaidins, C S; De Saint-Simon, M; Détraz, C; Epherre-Rey-Campagnolle, Marcelle; Guillemaud, D; Klapisch, Robert; Langevin, M; Naulin, F; Thibault, C; Touchard, F

    1981-01-01

    Investigates the time spectrum of beta -delayed neutron emission from /sup 30-34/Na and their descendants using beta -neutron coincidence detection. The authors have been able to assign an upper limit of 0,4% to the probability of beta -delayed neutron emission, p/sub n/, from the /sup 30/Na daugher isotope /sup 30/Mg. In fitting the time spectra of beta -delayed neutrons from /sup 31/Na and /sup 32/Na, we find a definitive component from subsequent daughter decay as well. This provides evidence for beta -delayed neutron emission from /sup 31/Mg and /sup 32/Mg with P/sub n/ values of the order of 2% for each. (7 refs).

  1. Detection System for Neutron $\\beta$ Decay Correlations in the UCNB and Nab experiments

    CERN Document Server

    Broussard, L J; Adamek, E R; Baeßler, S; Birge, N; Blatnik, M; Bowman, J D; Brandt, A E; Brown, M; Burkhart, J; Callahan, N B; Clayton, S M; Crawford, C; Cude-Woods, C; Currie, S; Dees, E B; Ding, X; Fomin, N; Frlez, E; Fry, J; Gray, F E; Hasan, S; Hickerson, K P; Hoagland, J; Holley, A T; Ito, T M; Klein, A; Li, H; Liu, C -Y; Makela, M F; McGaughey, P L; Mirabal-Martinez, J; Morris, C L; Ortiz, J D; Pattie, R W; Penttilä, S I; Plaster, B; Počanić, D; Ramsey, J C; Salas-Bacci, A; Salvat, D J; Saunders, A; Seestrom, S J; Sjue, S K L; Sprow, A P; Tang, Z; Vogelaar, R B; Vorndick, B; Wang, Z; Wei, W; Wexler, J; Wilburn, W S; Womack, T L; Young, A R

    2016-01-01

    We describe a detection system designed for precise measurements of angular correlations in neutron $\\beta$ decay. The system is based on thick, large area, highly segmented silicon detectors developed in collaboration with Micron Semiconductor, Ltd. The prototype system meets specifications for $\\beta$ electron detection with energy thresholds below 10 keV, energy resolution of $\\sim$3 keV FWHM, and rise time of $\\sim$50 ns with 19 of the 127 detector pixels instrumented. Using ultracold neutrons at the Los Alamos Neutron Science Center, we have demonstrated the coincident detection of $\\beta$ particles and recoil protons from neutron $\\beta$ decay. The fully instrumented detection system will be implemented in the UCNB and Nab experiments, to determine the neutron $\\beta$ decay parameters $B$, $a$, and $b$.

  2. Neutron-proton analyzing power measurements from 375 to 775 MeV

    Science.gov (United States)

    Newsom, C. R.; Hollas, C. L.; Ransome, R. D.; Riley, P. J.; Bonner, B. E.; Boissevain, J. G. J.; Jarmer, J. J.; McNaughton, M. W.; Simmons, J. E.; Bhatia, T. S.; Glass, G.; Hiebert, J. C.; Northcliffe, L. C.; Tippens, W. B.

    1989-03-01

    As part of an experimental study of the nucleon-nucleon interaction at medium energy, the free neutron-proton analyzing power An(θ*n,Tn) has been measured at nine incident neutron energies in the range 375<=Tn<=775 MeV and for neutron c.m. angles in the range 57°<=θ*n<=159°. Unpolarized neutrons with a broad continuum of energies, produced by interaction of an 800 MeV proton beam with a beryllium target, were scattered from a polarized proton target. At each angle, for the whole energy region, the scattered neutron and conjugate recoil proton were detected in coincidence. A previously unseen minimum is observed in the energy dependence of An(θ*~100°) near 625 MeV.

  3. Measurement and simulation of the muon-induced neutron yield in lead

    CERN Document Server

    Reichhart, L; Akimov, D Yu; Araujo, H M; Barnes, E J; Belov, V A; Bewick, A; Burenkov, A A; Chepel, V; Currie, A; DeViveiros, L; Edwards, B; Francis, V; Ghag, C; Hollingsworth, A; Horn, M; Kalmus, G E; Kobyakin, A S; Kovalenko, A G; Kudryavtsev, V A; Lebedenko, V N; Lopes, M I; Luscher, R; Majewski, P; Murphy, A St J; Neves, F; Paling, S M; da Cunha, J Pinto; Preece, R; Quenby, J J; Scovell, P R; Silva, C; Solovov, V N; Smith, N J T; Smith, P F; Stekhanov, V N; Sumner, T J; Thorne, C; Walker, R J

    2013-01-01

    A measurement is presented of the neutron production rate in lead by high energy cosmic-ray muons at a depth of 2850 m water equivalent (w.e.) and a mean muon energy of 260 GeV. The measurement exploits the delayed coincidences between muons and the radiative capture of induced neutrons in a highly segmented tonne scale plastic scintillator detector. Detailed Monte Carlo simulations reproduce well the measured capture times and multiplicities and, within the dynamic range of the instrumentation, the spectrum of energy deposits. By comparing measurements with simulations of neutron capture rates a neutron yield in lead of (5.8 +/- 0.2) x 10^-3 neutrons/muon/(g/cm^2) has been obtained. Absolute agreement between simulation and data is of order 25%. Consequences for deep underground rare event searches are discussed.

  4. Detection system for neutron β decay correlations in the UCNB and Nab experiments

    Science.gov (United States)

    Broussard, L. J.; Zeck, B. A.; Adamek, E. R.; Baeßler, S.; Birge, N.; Blatnik, M.; Bowman, J. D.; Brandt, A. E.; Brown, M.; Burkhart, J.; Callahan, N. B.; Clayton, S. M.; Crawford, C.; Cude-Woods, C.; Currie, S.; Dees, E. B.; Ding, X.; Fomin, N.; Frlez, E.; Fry, J.; Gray, F. E.; Hasan, S.; Hickerson, K. P.; Hoagland, J.; Holley, A. T.; Ito, T. M.; Klein, A.; Li, H.; Liu, C.-Y.; Makela, M. F.; McGaughey, P. L.; Mirabal-Martinez, J.; Morris, C. L.; Ortiz, J. D.; Pattie, R. W.; Penttilä, S. I.; Plaster, B.; Počanić, D.; Ramsey, J. C.; Salas-Bacci, A.; Salvat, D. J.; Saunders, A.; Seestrom, S. J.; Sjue, S. K. L.; Sprow, A. P.; Tang, Z.; Vogelaar, R. B.; Vorndick, B.; Wang, Z.; Wei, W.; Wexler, J.; Wilburn, W. S.; Womack, T. L.; Young, A. R.

    2017-03-01

    We describe a detection system designed for precise measurements of angular correlations in neutron β decay. The system is based on thick, large area, highly segmented silicon detectors developed in collaboration with Micron Semiconductor, Ltd. The prototype system meets specifications for β electron detection with energy thresholds below 10 keV, energy resolution of ∼3 keV FWHM, and rise time of ∼50 ns with 19 of the 127 detector pixels instrumented. Using ultracold neutrons at the Los Alamos Neutron Science Center, we have demonstrated the coincident detection of β particles and recoil protons from neutron β decay. The fully instrumented detection system will be implemented in the UCNB and Nab experiments to determine the neutron β decay parameters B, a, and b.

  5. Thermal neutron radiative capture cross-section of 186W(n, γ)187W reaction

    Science.gov (United States)

    Tan, V. H.; Son, P. N.

    2016-06-01

    The thermal neutron radiative capture cross section for 186W(n, γ)187W reaction was measured by the activation method using the filtered neutron beam at the Dalat research reactor. An optimal composition of Si and Bi, in single crystal form, has been used as neutron filters to create the high-purity filtered neutron beam with Cadmium ratio of Rcd = 420 and peak energy En = 0.025 eV. The induced activities in the irradiated samples were measured by a high resolution HPGe digital gamma-ray spectrometer. The present result of cross section has been determined relatively to the reference value of the standard reaction 197Au(n, γ)198Au. The necessary correction factors for gamma-ray true coincidence summing, and thermal neutron self-shielding effects were taken into account in this experiment by Monte Carlo simulations.

  6. The coincidence counting technique for orders of magnitude background reduction in data obtained with the magnetic recoil spectrometer at OMEGA and the NIF.

    Science.gov (United States)

    Casey, D T; Frenje, J A; Séguin, F H; Li, C K; Rosenberg, M J; Rinderknecht, H; Manuel, M J-E; Gatu Johnson, M; Schaeffer, J C; Frankel, R; Sinenian, N; Childs, R A; Petrasso, R D; Glebov, V Yu; Sangster, T C; Burke, M; Roberts, S

    2011-07-01

    A magnetic recoil spectrometer (MRS) has been built and successfully used at OMEGA for measurements of down-scattered neutrons (DS-n), from which an areal density in both warm-capsule and cryogenic-DT implosions have been inferred. Another MRS is currently being commissioned on the National Ignition Facility (NIF) for diagnosing low-yield tritium-hydrogen-deuterium implosions and high-yield DT implosions. As CR-39 detectors are used in the MRS, the principal sources of background are neutron-induced tracks and intrinsic tracks (defects in the CR-39). The coincidence counting technique was developed to reduce these types of background tracks to the required level for the DS-n measurements at OMEGA and the NIF. Using this technique, it has been demonstrated that the number of background tracks is reduced by a couple of orders of magnitude, which exceeds the requirement for the DS-n measurements at both facilities.

  7. A first search for coincident gravitational waves and high energy neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Di Palma, Irene

    2012-08-14

    We present the results of the first search for gravitational wave (GW) bursts associated with high energy neutrinos (HEN), detected by the underwater neutrino telescope ANTARES in its 5 lines configuration, during the fifth LIGO science run and first Virgo science run. The data used in this analysis were collected from February 9 to September 30 2007. Cataclysmic cosmic events with burst activity can be plausible sources of concomitant GW and HEN. Such messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, in particular at high energy. In a first stage of the analysis, HEN candidates, detected during the operation of the ANTARES Telescope were selected. In a second stage, GW candidates in time and space correlation with the HEN events were searched for in LIGO and Virgo data. During this first joint GW+HEN search, no coincident event was observed. We set limits on the population density of different types of concurrent GW-HEN sources. For short GRB-like sources, related to the merger of two compact objects, the density upper limit is {rho}{sub GW-HEN}{sup SGRB} neutron star systems of (1.35-1.35)M{sub s}un and black hole- neutron star systems of (5-1.35)M{sub s}un up to distances that are typically of 5 Mpc and 10 Mpc respectively. For generic waveform limits in the low frequency band typical distance limits can be as high as

  8. Neutron resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gunsing, F

    2005-06-15

    The present document has been written in order to obtain the diploma 'Habilitation a Diriger des Recherches'. Since this diploma is indispensable to supervise thesis students, I had the intention to write a document that can be useful for someone starting in the field of neutron resonance spectroscopy. Although the here described topics are already described elsewhere, and often in more detail, it seemed useful to have most of the relevant information in a single document. A general introduction places the topic of neutron-nucleus interaction in a nuclear physics context. The large variations of several orders of magnitude in neutron-induced reaction cross sections are explained in terms of nuclear level excitations. The random character of the resonances make nuclear model calculation predictions impossible. Then several fields in physics where neutron-induced reactions are important and to which I have contributed in some way or another, are mentioned in a first synthetic chapter. They concern topics like parity nonconservation in certain neutron resonances, stellar nucleosynthesis by neutron capture, and data for nuclear energy applications. The latter item is especially important for the transmutation of nuclear waste and for alternative fuel cycles. Nuclear data libraries are also briefly mentioned. A second chapter details the R-matrix theory. This formalism is the foundation of the description of the neutron-nucleus interaction and is present in all fields of neutron resonance spectroscopy. (author)

  9. Development of Neutron Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chang Hee; Lee, J. S.; Seong, B. S. (and others)

    2007-06-15

    Neutron spectrometers which are used in the basic researches such as physics, chemistry and materials science and applied in the industry were developed at the horizontal beam port of HANARO reactor. In addition, the development of core components for neutron scattering and the upgrade of existing facilities are also performed. The vertical neutron reflectometer was fabricated and installed at ST3 beam port. The performance test of the reflectometer was completed and the reflectometer was opened to users. The several core parts and options were added in the polarized neutron spectrometer. The horizontal neutron reflectometer from Brookhaven National Laboratory was moved to HANARO and installed, and the performance of the reflectometer was examined. The HIPD was developed and the performance test was completed. The base shielding for TAS was fabricated. The soller collimator, Cu mosaic monochromator, Si BPC monochromator and position sensitive detector were developed and applied in the neutron spectrometer as part of core component development activities. In addition, the sputtering machine for mirror device are fabricated and the neutron mirror is made using the sputtering machine. The FCD was upgraded and the performance of the FCD are improved over the factor of 10. The integration and upgrade of the neutron detection system were also performed.

  10. Neutron Star Matter

    CERN Document Server

    Wambach, Jochen

    2013-01-01

    In this presentation I discuss two aspects of the neutron-matter equation of state. One relates to the symmetry energy of nuclear matter and empirical constraints on its slope parameter at saturation density. The second deals with spatially inhomogeneous chiral phases of deconfined quark matter in the inner core of a neutron star.

  11. Neutron Multiplicity Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Frame, Katherine Chiyoko [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-06-28

    Neutron multiplicity measurements are widely used for nondestructive assay (NDA) of special nuclear material (SNM). When combined with isotopic composition information, neutron multiplicity analysis can be used to estimate the spontaneous fission rate and leakage multiplication of SNM. When combined with isotopic information, the total mass of fissile material can also be determined. This presentation provides an overview of this technique.

  12. Neutron capture therapies

    Energy Technology Data Exchange (ETDEWEB)

    Yanch, Jacquelyn C. (Cambridge, MA); Shefer, Ruth E. (Newton, MA); Klinkowstein, Robert E. (Winchester, MA)

    1999-01-01

    In one embodiment there is provided an application of the .sup.10 B(n,.alpha.).sup.7 Li nuclear reaction or other neutron capture reactions for the treatment of rheumatoid arthritis. This application, called Boron Neutron Capture Synovectomy (BNCS), requires substantially altered demands on neutron beam design than for instance treatment of deep seated tumors. Considerations for neutron beam design for the treatment of arthritic joints via BNCS are provided for, and comparisons with the design requirements for Boron Neutron Capture Therapy (BNCT) of tumors are made. In addition, exemplary moderator/reflector assemblies are provided which produce intense, high-quality neutron beams based on (p,n) accelerator-based reactions. In another embodiment there is provided the use of deuteron-based charged particle reactions to be used as sources for epithermal or thermal neutron beams for neutron capture therapies. Many d,n reactions (e.g. using deuterium, tritium or beryllium targets) are very prolific at relatively low deuteron energies.

  13. Neutron capture therapies

    Energy Technology Data Exchange (ETDEWEB)

    Yanch, J.C.; Shefer, R.E.; Klinkowstein, R.E.

    1999-11-02

    In one embodiment there is provided an application of the {sup 10}B(n,{alpha}){sup 7}Li nuclear reaction or other neutron capture reactions for the treatment of rheumatoid arthritis. This application, called Boron Neutron Capture Synovectomy (BNCS), requires substantially altered demands on neutron beam design than for instance treatment of deep seated tumors. Considerations for neutron beam design for the treatment of arthritic joints via BNCS are provided for, and comparisons with the design requirements for Boron Neutron Capture Therapy (BNCT) of tumors are made. In addition, exemplary moderator/reflector assemblies are provided which produce intense, high-quality neutron beams based on (p,n) accelerator-based reactions. In another embodiment there is provided the use of deuteron-based charged particle reactions to be used as sources for epithermal or thermal neutron beams for neutron capture therapies. Many d,n reactions (e.g. using deuterium, tritium or beryllium targets) are very prolific at relatively low deuteron energies.

  14. Theoretical Bounds and Practical Constructions for Families of One—Coincidence Sequences in FHMA

    Institute of Scientific and Technical Information of China (English)

    MeiWenhua; YangYixian

    1995-01-01

    Theoretical bounds are given for the number of one-coincidence sequences in syn-chronous FHMA systems,and for the number and period of one-coincidence sequences in asyn-chronous FHMA systems.Several practical constructions for families of one-coincidencesequences are surveyed,and a new model for families of one-coincidence sequences is presented.

  15. National Array of Neutron Detectors (NAND): A versatile tool for nuclear reaction studies

    Energy Technology Data Exchange (ETDEWEB)

    Golda, K.S., E-mail: goldaks@gmail.com [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Jhingan, A.; Sugathan, P. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Singh, Hardev [Department of Physics, Kurukshetra University, Kurukshetra 136119 (India); Singh, R.P. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Behera, B.R. [Department of Physics, Panjab University, Chandigarh 160014 (India); Mandal, S. [Department of Physics and Astrophysics, Delhi University, New Delhi 110007 (India); Kothari, A.; Gupta, Arti; Zacharias, J.; Archunan, M.; Barua, P.; Venkataramanan, S.; Bhowmik, R.K. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Govil, I.M. [Department of Physics, Panjab University, Chandigarh 160014 (India); Datta, S.K.; Chatterjee, M.B. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)

    2014-11-01

    The first phase of the National Array of Neutron Detectors (NAND) consisting of 26 neutron detectors has been commissioned at the Inter University Accelerator Centre (IUAC), New Delhi. The motivation behind setting up of such a detector system is the need for more accurate and efficient study of reaction mechanisms in the projectile energy range of 5–8 MeV/n using heavy ion beams from a 15 UD Pelletron and an upgraded LINAC booster facility at IUAC. The above detector array can be used for inclusive as well as exclusive measurements of reaction products of which at least one product is a neutron. While inclusive measurements can be made using only the neutron detectors along with the time of flight technique and a pulsed beam, exclusive measurements can be performed by detecting neutrons in coincidence with charged particles and/or fission fragments detected with ancillary detectors. The array can also be used for neutron tagged gamma-ray spectroscopy in (HI, xn) reactions by detecting gamma-rays in coincidence with the neutrons in a compact geometrical configuration. The various features and the performance of the different aspects of the array are described in the present paper. -- Highlights: •We report the design, fabrication and installation of a 26 element modular neutron detection system (NAND). •The array has been designed for the fusion–fission studies at near and above the barrier energies. •The relevant characteristics of the array are studied exhaustively and reported. •The efficiency of the detectors are measured and compared with the monte carlo simulations. •The second phase of the array will be augmented with 80 more neutron detectors which will enable the system to measure the neutron multiplicity distribution.

  16. Characterizing ICF Neutron Scintillation Diagnostics on the nTOF line at SUNY Geneseo

    Science.gov (United States)

    Lawson-Keister, Pat; Padawar-Curry, Jonah; Visca, Hannah; Fletcher, Kurt; Padalino, Stephen; Sangster, T. Craig; Regan, Sean

    2015-11-01

    Neutron scintillator diagnostics for ICF and HEDP can be characterized using the neutron time-of-flight (nTOF) line on Geneseo's 1.7 MV tandem Pelletron accelerator. Neutron signals can be differentiated from gamma signals by employing coincidence methods. A 1.8-MeV beam of deuterons incident on a deuterated polyethylene target produces neutrons via the 2H(d,n)3He reaction. Neutrons emerging at a lab angle of 88° have an energy of 2.96 MeV; the 3He ions associated with these neutrons are detected at a scattering angle of 43° using a surface barrier detector. The time of flight of the neutron can be measured by using the 3He detection as a ``start'' signal and the scintillation detection as a ``stop'' signal. This time of flight requirement is used to identify the 2.96-MeV neutron signals in the scintillator. To measure the light curve produced by these monoenergetic neutrons, two photomultiplier (PMT) tubes are attached to the scintillator. The full aperture PMT establishes the nTOF coincidence. The other PMT is fitted with a pinhole to collect single events. The time between the full aperture PMT signal and the arrival of the signal in the pinhole PMT is used to determine the light curve for the scintillator. This system will enable the neutron response of various scintillators to be compared. Supported in part by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  17. Neutron Stars and Pulsars

    CERN Document Server

    Becker, Werner

    2009-01-01

    Neutron stars are the most compact astronomical objects in the universe which are accessible by direct observation. Studying neutron stars means studying physics in regimes unattainable in any terrestrial laboratory. Understanding their observed complex phenomena requires a wide range of scientific disciplines, including the nuclear and condensed matter physics of very dense matter in neutron star interiors, plasma physics and quantum electrodynamics of magnetospheres, and the relativistic magneto-hydrodynamics of electron-positron pulsar winds interacting with some ambient medium. Not to mention the test bed neutron stars provide for general relativity theories, and their importance as potential sources of gravitational waves. It is this variety of disciplines which, among others, makes neutron star research so fascinating, not only for those who have been working in the field for many years but also for students and young scientists. The aim of this book is to serve as a reference work which not only review...

  18. THERMAL NEUTRON BACKSCATTER IMAGING.

    Energy Technology Data Exchange (ETDEWEB)

    VANIER,P.; FORMAN,L.; HUNTER,S.; HARRIS,E.; SMITH,G.

    2004-10-16

    Objects of various shapes, with some appreciable hydrogen content, were exposed to fast neutrons from a pulsed D-T generator, resulting in a partially-moderated spectrum of backscattered neutrons. The thermal component of the backscatter was used to form images of the objects by means of a coded aperture thermal neutron imaging system. Timing signals from the neutron generator were used to gate the detection system so as to record only events consistent with thermal neutrons traveling the distance between the target and the detector. It was shown that this time-of-flight method provided a significant improvement in image contrast compared to counting all events detected by the position-sensitive {sup 3}He proportional chamber used in the imager. The technique may have application in the detection and shape-determination of land mines, particularly non-metallic types.

  19. Pocked surface neutron detector

    Energy Technology Data Exchange (ETDEWEB)

    McGregor, Douglas (Whitmore Lake, MI); Klann, Raymond (Bolingbrook, IL)

    2003-04-08

    The detection efficiency, or sensitivity, of a neutron detector material such as of Si, SiC, amorphous Si, GaAs, or diamond is substantially increased by forming one or more cavities, or holes, in its surface. A neutron reactive material such as of elemental, or any compound of, .sup.10 B, .sup.6 Li, .sup.6 LiF, U, or Gd is deposited on the surface of the detector material so as to be disposed within the cavities therein. The portions of the neutron reactive material extending into the detector material substantially increase the probability of an energetic neutron reaction product in the form of a charged particle being directed into and detected by the neutron detector material.

  20. Neutron stars - General review

    Science.gov (United States)

    Cameron, A. G. W.; Canuto, V.

    1974-01-01

    A review is presented of those properties of neutron stars upon which there is general agreement and of those areas which currently remain in doubt. Developments in theoretical physics of neutron star interiors are summarized with particular attention devoted to hyperon interactions and the structure of interior layers. Determination of energy states and the composition of matter is described for successive layers, beginning with the surface and proceeding through the central region into the core. Problems encountered in determining the behavior of matter in the ultra-high density regime are discussed, and the effects of the magnetic field of a neutron star are evaluated along with the behavior of atomic structures in the field. The evolution of a neutron star is outlined with discussion centering on carbon detonation, cooling, vibrational damping, rotation, and pulsar glitches. The role of neutron stars in cosmic-ray propagation is considered.

  1. OPAL Cold Neutron Guide In-Pile Replacement

    Energy Technology Data Exchange (ETDEWEB)

    Rownes, T.; Eltobaji, A.; Bell, M.; Klose, F. [Nuclear Operations, Baitain (Australia)

    2013-07-01

    The 20 MW{sub th} OPAL research reactor has five neutron beam assemblies. These provide cold and thermal neutrons to various neutron guides and associated neutron beam instruments. In 2010 a project was initiated to install a new cold neutron guide, CG2, in one of the assemblies. This installation would allow up to four new neutron beam instruments to be built, significantly expanding the reactor's capabilities. The project concluded in December 2012 with the successful installation of CG2. Each neutron beam assembly has an in-pile plug, a primary shutter and a front cover. Together these constitute the neutron guide's in-pile components, with a total mass of over 12 tonnes. The CG2 installation required the complete replacement of the existing components. This replacement was scheduled to coincide with OPAL's first major shutdown. With a budget of $2.3 million and an expected dose of 50 man.mSv, the CG2 installation was a large and complex task. Work during the shutdown involved over 40 ANSTO personnel and radiation fields approached 1 Sv/h in some areas. Despite this, the installation team received a collective dose of only 10 man.mSv, and the project was completed to budget and within schedule. This paper will outline the details of the project, focusing on lessons learned and recommended practices. Each OPAL in-pile plug has a design life of 10 years at full power operation, and similar replacements will be performed regularly as the reactor ages. It is hoped that this information will be useful for other research reactors planning large capital engineering projects.

  2. SINGLE CRYSTAL NEUTRON DIFFRACTION.

    Energy Technology Data Exchange (ETDEWEB)

    KOETZLE,T.F.

    2001-03-13

    Single-crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator-based spallation source. Single-crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Angstrom. For high-resolution studies requiring shorter wavelengths (ca. 0.3-0.8 Angstroms), a pulsed spallation source or a high-temperature moderator (a ''hot source'') at a reactor may be used. When complex structures with large unit-cell repeats are under investigation, as is the case in structural biology, a cryogenic-temperature moderator (a ''cold source'') may be employed to obtain longer neutron wavelengths (ca. 4-10 Angstroms). A single-crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean-square displacements, and relevant site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well, from the magnetic contribution to the Bragg intensities. This latter aspect falls beyond the scope of the present unit; for information on magnetic scattering of neutrons see Unit 14.3. Instruments for single-crystal diffraction (single-crystal diffractometers or SCDs) are generally available at the major neutron scattering center facilities. Beam time on many of these instruments is available through a proposal mechanism. A listing of neutron SCD instruments and their corresponding facility contacts is included in an appendix accompanying this unit.

  3. Optical polarizing neutron devices designed for pulsed neutron sources

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, M.; Kurahashi, K.; Endoh, Y. [Tohoku Univ, Sendai (Japan); Itoh, S. [National Lab. for High Energy Physics, Tsukuba (Japan)

    1997-09-01

    We have designed two polarizing neutron devices for pulsed cold neutrons. The devices have been tested at the pulsed neutron source at the Booster Synchrotron Utilization Facility of the National Laboratory for High Energy Physics. These two devices proved to have a practical use for experiments to investigate condensed matter physics using pulsed cold polarized neutrons.

  4. Fail-safe neutron shutter used for thermal neutron radiography

    Energy Technology Data Exchange (ETDEWEB)

    Sachs, R.D.; Morris, R.A.

    1976-11-01

    A fail-safe, reliable, easy-to-use neutron shutter was designed, built, and put into operation at the Omega West Reactor, Los Alamos Scientific Laboratory. The neutron shutter will be used primarily to perform thermal neutron radiography, but is also available for a highly collimated source of thermal neutrons (neutron flux = 3.876 x 10/sup 6/ (neutrons)/(cm/sup 2/.s)). Neutron collimator sizes of either 10.16 by 10.16 cm or 10.16 by 30.48 cm are available.

  5. Methodology for assessing probability of extreme hydrologic events coincidence

    Directory of Open Access Journals (Sweden)

    Prohaska Stevan

    2010-01-01

    Full Text Available The aim of the presented research is improvement of methodology for probability calculation of coinciding occurrence of historic floods and droughts in the same year. The original procedure was developed in order to determine the occurrence probability of such an extreme historic event. There are two phases in calculation procedure for assessment of both extreme drought and flood occurrence probability in the same year. In the first phase outliers are detected as indicators of extreme events, their return periods are calculated and series' statistics adjusted. In the second phase conditional probabilities are calculated: empirical points are plotted, and both extreme drought and flood occurrence probability in the same year is assessed based on the plot. Outlier detection is performed for the territory of Serbia. Results are shown as maps of regions (basins prone to floods, hydrologic drought, or both. Step-by-step numeric example is given for assessing conditional probability of occurrence of flood and drought for GS Raska on the river Raska. Results of assessment of conditional probability in two more cases are given for combination of extreme flood and 30 day minimum flow.

  6. Dubin-Johnson syndrome coinciding with colon cancer and atherosclerosis.

    Science.gov (United States)

    Sticova, Eva; Elleder, Milan; Hulkova, Helena; Luksan, Ondrej; Sauer, Martin; Wunschova-Moudra, Irena; Novotny, Jan; Jirsa, Milan

    2013-02-14

    Hyperbilirubinemia has been presumed to prevent the process of atherogenesis and cancerogenesis mainly by decreasing oxidative stress. Dubin-Johnson syndrome is a rare, autosomal recessive, inherited disorder characterized by biphasic, predominantly conjugated hyperbilirubinemia with no progression to end-stage liver disease. The molecular basis in Dubin-Johnson syndrome is absence or deficiency of human canalicular multispecific organic anion transporter MRP2/cMOAT caused by homozygous or compound heterozygous mutation(s) in ABCC2 located on chromosome 10q24. Clinical onset of the syndrome is most often seen in the late teens or early adulthood. In this report, we describe a case of previously unrecognized Dubin-Johnson syndrome caused by two novel pathogenic mutations (c.2360_2366delCCCTGTC and c.3258+1G>A), coinciding with cholestatic liver disease in an 82-year-old male patient. The patient, suffering from advanced atherosclerosis with serious involvement of coronary arteries, developed colorectal cancer with nodal metastases. The subsequent findings do not support the protective role of Dubin-Johnson type hyperbilirubinemia.

  7. Super sub-wavelength patterns in photon coincidence detection

    Science.gov (United States)

    Liu, Ruifeng; Zhang, Pei; Zhou, Yu; Gao, Hong; Li, Fuli

    2014-02-01

    High-precision measurements implemented with light are desired in all fields of science. However, light acts as a wave, and the Rayleigh criterion in classical optics yields a diffraction limit that prevents obtaining a resolution smaller than the wavelength. Sub-wavelength interference has potential application in lithography because it beats the classical Rayleigh resolution limit. Here, we carefully study second-order correlation theory to establish the physics behind sub-wavelength interference in photon coincidence detection. A Young's double slit experiment with pseudo-thermal light is performed to test the second-order correlation pattern. The results show that when two point detectors are scanned in different ways, super sub-wavelength interference patterns can be obtained. We then provide a theoretical explanation for this surprising result, and demonstrate that this explanation is also suitable for the results found for entangled light. Furthermore, we discuss the limitations of these types of super sub-wavelength interference patterns in quantum lithography.

  8. Coincidence ion imaging with a fast frame camera

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Suk Kyoung; Cudry, Fadia; Lin, Yun Fei; Lingenfelter, Steven; Winney, Alexander H.; Fan, Lin; Li, Wen, E-mail: wli@chem.wayne.edu [Department of Chemistry, Wayne State University, Detroit, Michigan 48202 (United States)

    2014-12-15

    A new time- and position-sensitive particle detection system based on a fast frame CMOS (complementary metal-oxide semiconductors) camera is developed for coincidence ion imaging. The system is composed of four major components: a conventional microchannel plate/phosphor screen ion imager, a fast frame CMOS camera, a single anode photomultiplier tube (PMT), and a high-speed digitizer. The system collects the positional information of ions from a fast frame camera through real-time centroiding while the arrival times are obtained from the timing signal of a PMT processed by a high-speed digitizer. Multi-hit capability is achieved by correlating the intensity of ion spots on each camera frame with the peak heights on the corresponding time-of-flight spectrum of a PMT. Efficient computer algorithms are developed to process camera frames and digitizer traces in real-time at 1 kHz laser repetition rate. We demonstrate the capability of this system by detecting a momentum-matched co-fragments pair (methyl and iodine cations) produced from strong field dissociative double ionization of methyl iodide.

  9. New coincidence between Shroud of Turin and Sudarium of Oviedo

    Directory of Open Access Journals (Sweden)

    Barta C.

    2015-01-01

    Full Text Available The Sudarium of Oviedo and the Shroud of Turin are two relics attributed to Jesus Christ that show a series of amazing coincidences announced in the past. In this contribution, we describe the X-ray fluorescence analysis carried out on the Sudarium. Among the chemical elements detected, calcium shows a statistically significant higher presence in the areas with bloody stains. This fact allows correlating its distribution with the anatomical features of the corpse. A large excess of calcium is observed close to the tip of the nose. It is atypical to find soil dirt in this zone of the anatomy, but it is just the same zone where a particular presence of dust was found in the Shroud. The very low concentration of strontium traces in the Sudarium matches also well with the type of limestone characteristic of the rock of Calvary in Jerusalem. This new finding adds to others recently released and it strengthens the tradition that both cloths have wrapped the body of Jesus of Nazareth.

  10. Analytical model of coincidence resolving time in TOF-PET.

    Science.gov (United States)

    Wieczorek, H; Thon, A; Dey, T; Khanin, V; Rodnyi, P

    2016-06-21

    The coincidence resolving time (CRT) of scintillation detectors is the parameter determining noise reduction in time-of-flight PET. We derive an analytical CRT model based on the statistical distribution of photons for two different prototype scintillators. For the first one, characterized by single exponential decay, CRT is proportional to the decay time and inversely proportional to the number of photons, with a square root dependence on the trigger level. For the second scintillator prototype, characterized by exponential rise and decay, CRT is proportional to the square root of the product of rise time and decay time divided by the doubled number of photons, and it is nearly independent of the trigger level. This theory is verified by measurements of scintillation time constants, light yield and CRT on scintillator sticks. Trapping effects are taken into account by defining an effective decay time. We show that in terms of signal-to-noise ratio, CRT is as important as patient dose, imaging time or PET system sensitivity. The noise reduction effect of better timing resolution is verified and visualized by Monte Carlo simulation of a NEMA image quality phantom.

  11. Strings, boundary fermions and coincident D-branes

    CERN Document Server

    Wulff, L

    2007-01-01

    This thesis describes an attempt to write down covariant actions for coincident D-branes using so-called boundary fermions instead of matrices to describe the non-abelian fields. These fermions can be thought of as Chan-Paton degrees of freedom for the open string. It is shown that by gauge-fixing and by suitably quantizing these boundary fermions the non-abelian action that is known, the Myers action, can be reproduced. Furthermore it is shown that under natural assumptions, unlike the Myers action, the action formulated using boundary fermions also posseses kappa-symmetry when formulated on superspace. Another aspect of string theory discussed in this thesis is that of tensionless strings. These are of great interest for example because of their possible relation to higher spin gauge theories via the AdS/CFT-correspondence. The tensionless superstring in a plane wave background, a Penrose limit of the near-horizon geometry of a stack of D3-branes, is considered and compared to the tensile case.

  12. The Structure of the Cubic Coincident Site Lattice Rotation Group

    Energy Technology Data Exchange (ETDEWEB)

    Reed, B W; Minich, R W; Rudd, R E; Kumar, M

    2004-01-13

    This work is intended to be a mathematical underpinning for the field of grain boundary engineering and its relatives. The interrelationships within the set of rotations producing coincident site lattices in cubic crystals are examined in detail. Besides combining previously established but widely scattered results into a unified context, the present work details newly developed representations of the group structure in terms of strings of generators (based on quaternionic number theory, and including uniqueness proofs and rules for algebraic manipulation) as well as an easily visualized topological network model. Important results that were previously obscure or not universally understood (e.g. the {Sigma} combination rule governing triple junctions) are clarified in these frameworks. The methods also facilitate several general observations, including the very different natures of twin-limited structures in two and three dimensions, the inadequacy of the {Sigma} combination rule to determine valid quadruple nodes, and a curious link between allowable grain boundary assignments and the four-color map theorem. This kind of understanding is essential to the generation of realistic statistical models of grain boundary networks (particularly in twin-dominated systems) and is especially applicable to the field of grain boundary engineering.

  13. Coincident Phosphatidic Acid Interaction Restrains Drp1 in Mitochondrial Division.

    Science.gov (United States)

    Adachi, Yoshihiro; Itoh, Kie; Yamada, Tatsuya; Cerveny, Kara L; Suzuki, Takamichi L; Macdonald, Patrick; Frohman, Michael A; Ramachandran, Rajesh; Iijima, Miho; Sesaki, Hiromi

    2016-09-15

    Mitochondria divide to control their size, distribution, turnover, and function. Dynamin-related protein 1 (Drp1) is a critical mechanochemical GTPase that drives constriction during mitochondrial division. It is generally believed that mitochondrial division is regulated during recruitment of Drp1 to mitochondria and its oligomerization into a division apparatus. Here, we report an unforeseen mechanism that regulates mitochondrial division by coincident interactions of Drp1 with the head group and acyl chains of phospholipids. Drp1 recognizes the head group of phosphatidic acid (PA) and two saturated acyl chains of another phospholipid by penetrating into the hydrophobic core of the membrane. The dual phospholipid interactions restrain Drp1 via inhibition of oligomerization-stimulated GTP hydrolysis that promotes membrane constriction. Moreover, a PA-producing phospholipase, MitoPLD, binds Drp1, creating a PA-rich microenvironment in the vicinity of a division apparatus. Thus, PA controls the activation of Drp1 after the formation of the division apparatus.

  14. Coincidence of Trisomy 18 and Robertsonian (13; 14

    Directory of Open Access Journals (Sweden)

    A Alavi

    2012-07-01

    Full Text Available This case report presents a coincidence of trisomy 18 and balanced Robertsonian translocation (13;14. Aneuploidy was suspected based on anomalies detected in ultrasound scan and confirmed with karyotype. In a 31 years-old healthy woman with a history of one miscarriage, second trimester ultrasound scan reported IUGR (<3rd percentile with normal amniotic fluid, bilateral choroid plexus cysts, suspicious agenesis of corpus callosum and clenched hands. Amniocentesis was performed and karyotype was 46xx,der(13;14 (q10;q10,+18. Maternal karyotype was 45xx,der(13;14(q10;q10. Pregnancy was continued due to legal limitation for termination after 20 weeks gestation. Delivery was done at 36 weeks gestation. A female newborn was borned and a physical feature was hypotonia, small mouth, prominent occiput, low-set and posteriorly rotated ears, clenched hands with overlapping fingers and rocker bottom feet. Ultrasound scan and echocardiography detected agenesis of corpus callosum and VSD, ASD, PDA and cardiomegaly. These features are typical of trisomy 18. Balanced Robertsonian translocation usually has no phenotypic expression. Genetic counseling and prenatal diagnosis for future pregnancy was recommended.

  15. Bi-Modal Model for Neutron Emissions from PuO{sub 2} and MOX Holdup

    Energy Technology Data Exchange (ETDEWEB)

    Menlove, Howard; Lafleur, Adrienne [Los Alamos National Laboratory, Safeguard Science and Technology Group, NEN-1, MS E540, Los Alamos, NM, 87545 (United States)

    2015-07-01

    The measurement of uranium and plutonium holdup in plants during process activity and for decommissioning is important for nuclear safeguards and material control. The amount of plutonium and uranium holdup in glove-boxes, pipes, ducts, and other containers has been measured for several decades using both neutron and gamma-ray techniques. For the larger containers such as hot cells and glove-boxes that contain processing equipment, the gamma-ray techniques are limited by self-shielding in the sample as well as gamma absorption in the equipment and associated shielding. The neutron emission is more penetrating and has been used extensively to measure the holdup for the large facilities such as the MOX processing and fabrication facilities in Japan and Europe. In some case the totals neutron emission rates are used to determine the holdup mass and in other cases the coincidence rates are used such as at the PFPF MOX fabrication plant in Japan. The neutron emission from plutonium and MOX has 3 primary source terms: 1) Spontaneous fission (SF) from the plutonium isotopes, 2) The (α,n) reactions from the plutonium alpha particle emission reacting with the oxygen and other impurities, and 3) Neutron multiplication (M) in the plutonium and uranium as a result of neutrons created by the first two sources. The spontaneous fission yield per gram is independent of thickness, whereas, the above sources 2) and 3) are very dependent on the thickness of the deposit. As the effective thickness of the deposit becomes thin relative to the alpha particle range, the (α,n) reactions and neutrons from multiplication (M) approach zero. In any glove-box, there will always be two primary modes of holdup accumulation, namely direct powder contact and non-contact by air dispersal. These regimes correspond to surfaces in the glove-box that have come into direct contact with the process MOX powder versus surface areas that have not had direct contact with the powder. The air dispersal of Pu

  16. RNA regulatory elements and polyadenylation in plants

    Directory of Open Access Journals (Sweden)

    Arthur G. Hunt

    2012-01-01

    Full Text Available Alternative poly(A site choice (also known as alternative polyadenylation, or APA has the potential to affect gene expression in qualitative and quantitative ways. Alternative polyadenylation may affect as many as 82% of all expressed genes in a plant. The consequences of APA include the generation of transcripts with differing 3’-UTRs (and thus differing potential regulatory potential and of transcripts with differing protein-coding potential. Genome-wide studies of possible APA suggest a linkage with pre-mRNA splicing, and indicate a coincidence of and perhaps cooperation between RNA regulatory elements that affect splicing efficiency and the recognition of novel intronic poly(A sites. These studies also raise the possibility of the existence of a novel class of polyadenylation-related cis elements that are distinct from the well-characterized plant polyadenylation signal. Many potential APA events, however, have not been associated with identifiable cis elements. The present state of the field reveals a broad scope of APA, and also numerous opportunities for research into mechanisms that govern both choice and regulation of poly(A sites in plants.

  17. Neutron scattering in liquids

    Energy Technology Data Exchange (ETDEWEB)

    Barocchi, F. [Florence Univ. (Italy). Ist. di Fisica

    1996-12-31

    Together with X-rays, thermal neutrons are the ideal probe to study the microscopic structure of condensed matter, however the precision attainable usually with neutrons for the measurement of atomic position correlation functions in liquids is, at least, one order of magnitude better than for X-rays. In order to measure properly the microscopic dynamics a wide range of momentum transfer with corresponding energy transfer must be available in the range of liquid state excitations. This again is only attainable, with good resolution, with neutrons. (author) 7 figs., 3 refs.

  18. Neutrons in soft matter

    CERN Document Server

    Imae, Toyoko; Furusaka, Michihiro; Torikai, Naoya

    2011-01-01

    Neutron and synchrotron facilities, which are beyond the scale of the laboratory, and supported on a national level in countries throughout the world.  These tools for probing micro- and nano-structure research and on fast dynamics research of atomic location in materials have been key in the development of new polymer-based materials. Different from several existing professional books on neutron science, this book focuses on theory, instrumentation, an applications. The book is divided into five parts: Part 1 describes the underlying theory of neutron scattering. Part 2 desc

  19. Prompt Neutron Emission in 252CF Spontaneous Fission

    Science.gov (United States)

    Hambsch, F.-J.; Oberstedt, S.; Zeynalov, Sh.

    2011-10-01

    The prompt neutron emission in spontaneous fission of 252Cf has been investigated applying digital signal electronics. The goal was to compare the results from digital data acquisition and digital signal processing analysis with results of the pioneering work of Budtz-Jørgensen and Knitter. Using a twin Frisch-grid ionization chamber for fission fragment (FF) detection and a NE213-equivalent neutron detector in total about 107 fission fragment-neutron coincidences have been registered. Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12 bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. The results are in very good agreement with literature. For the first time the dependence of the number of emitted neutrons as a function of total kinetic energy (TKE) of the fragments is in very good agreement with theoretical calculations in the range of TKE from 140-220 MeV.

  20. High Energy Telescope With Neutron Detection Capabilities (HETn)

    Science.gov (United States)

    Posner, A.; Wimmer-Schweingruber, R. F.; Böhm, E.; Böttcher, s.; Connell, J. J.; Dröge, W.; Hassler, D. M.; Heber, B.; Lopate, C.; McKibben, R. B.; Steigies, C. T.

    2007-01-01

    The High-Energy Telescope with neutron detection capabilities (HETn) for the Solar Orbiter will measure and resolve energetic charged particles, in particular electrons, proton, and heavy ions up to Fe including selected isotopes up to energies equivalen to the penetration depth of 100 MeV protons. The full active anti-coincidence encloses detectors sensitive to 1-30 MeV neutrons and 0.5-5 MeV X-/gamma-rays. The sensor consists of the angle-detecting inclined sensors (ADIS) solid-state detector detector telescope utilizing a shared calorimeter for total energy and X-/gamma-ray measurement. A separate plastic detector provides sensitivity to neutrons via the recoil process. HETn will open a new window on solar eruptive events with its neutron detection capability and allows determination of high-energy close to the Sun. Timing and spectral information on neutral particles (neutrons and X-/gamma rays ), on relativistic electrons and high-energy heavy ions will provide new insights into the processes which accelerate particles to high energies at the sun and into transport processes between the source and the spacecraft in the near-Sun environment.

  1. Coincident Observations of Surface Ozone and NMVOCs over Abu Dhabi

    Science.gov (United States)

    Abbasi, Naveed; Majeed, Tariq; Iqbal, Mazhar; Tarasick, David; Davies, Jonathan; Riemer, Daniel; Apel, Eric

    2016-07-01

    The vertical profiles of ozone are measured coincidently with non-methane volatile organic compounds (NMVOCs) at the meteorological site located at the Abu Dhabi international airport (latitude 24.45N; longitude 54.22E) during the years 2012 - 2014. Some of the profiles show elevated surface ozone >95 ppbv during the winter months (December, January and February). The ground-level NMVOCs obtained from the gas chromatography-flame ionization detection/mass spectrometry system also show elevated values of acetylene, ethane, propane, butane, pentane, benzene, and toluene. NMVOCs and ozone abundances in other seasons are much lower than the values in winter season. NMVOCs are emitted from an extensive number of sources in urban environments including fuel production, distribution, and consumption, and serve as precursor of ozone. Transport sources contribute a substantial portion of the NMVOC burden to the urban atmosphere in developed regions. Abu Dhabi is located at the edge of the Arabian Gulf and is highly affected by emissions from petrochemical industries in the neighboring Gulf region. The preliminary results indicate that wintertime enhancement in ozone is associated with large values of NMVOCs at Abu Dhabi. The domestic production of surface ozone is estimated from the combination of oxygen recombination and NMVOCs and compared with the data. It is estimated that about 40-50% of ozone in Abu Dhabi is transported from the neighbouring petrochemical industries. We will present ozone sounding and NMVOCs data and our model estimates of surface ozone, including a discussion on the high levels of the tropospheric ozone responsible for contaminating the air quality in the UAE. This work is supported by National Research Foundation, UAE.

  2. Coincidence symptomatic gall stone and helicobacter pylori: a brief report

    Directory of Open Access Journals (Sweden)

    Seyed Kazem Nezam

    2013-10-01

    Full Text Available Background: On of the most common gasterointrestinal disease is gallstone disease and it`s prevalence is 11%-36%in autopsies. If gallstone leads to symptoms and side effect cholecystectomy will be inevitable. Gastric infection due to H.P will cause several symptoms of which dyspepsia and epigastric pain are outstanding .Gall stones also usually causes epigastric and/or right upper quadrant pain. Pain in other abdominal quadrant is less common. In this study we investigated the coincidence of gall stone and gastro intestinal H.P regarding the common symptom, between these two conditions to prevent unnecessary operation.Methods: The cases were adopted from cholecystectomy candidates due to gall stone disease (proved by ultrasonography. The control group were normal people who proved to be gall stone free ultrasonographicly. Serum IgG anti H.P was checked and compared between the two groups.Results: Seventy percent of patients entered into the study which consisted of 35 case and 35 controls. The two groups were not significantly different in age and gender. There were 22 (68.8% and 10 (31.2% H.P positive cases in case and control groups respectively. Thirteen (34.2% and 25 (65.8% cases were H.P negative in case and control groups respectively. Comparing these results will reveal a statistically significant difference (P=0.004.Conclusion: The relationship between gastric H.P and gall stone in this study supports the role of H.P in gall stone formation. According to our results and the common symptoms of two conditions specially in atypic biliary colic, it seems that in many cases gastrointestinal H.P causes the pain. Prospective studies are recommended.

  3. Silicon in plant disease control

    Directory of Open Access Journals (Sweden)

    Edson Ampélio Pozza

    2015-06-01

    Full Text Available All essential nutrients can affect the incidence and severity of plant diseases. Although silicon (Si is not considered as an essential nutrient for plants, it stands out for its potential to decrease disease intensity in many crops. The mechanism of Si action in plant resistance is still unclear. Si deposition in plant cell walls raised the hypothesis of a possible physical barrier to pathogen penetration. However, the increased activity of phenolic compounds, polyphenol oxidases and peroxidases in plants treated with Si demonstrates the involvement of this element in the induction of plant defense responses. The studies examined in this review address the role of Si in disease control and the possible mechanisms involved in the mode of Si action in disease resistance in plants.

  4. Simulations of a PSD Plastic Neutron Collar for Assaying Fresh Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Hausladen, Paul [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Newby, Jason [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McElroy, Robert Dennis [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-11-01

    The potential performance of a notional active coincidence collar for assaying uranium fuel based on segmented detectors constructed from the new PSD plastic fast organic scintillator with pulse shape discrimination capability was investigated in simulation. Like the International Atomic Energy Agency s present Uranium Neutron Collar for LEU (UNCL), the PSD plastic collar would also function by stimulating fission in the 235U content of the fuel with a moderated 241Am/Li neutron source and detecting instances of induced fission via neutron coincidence counting. In contrast to the moderated detectors of the UNCL, the fast time scale of detection in the scintillator eliminates statistical errors due to accidental coincidences that limit the performance of the UNCL. However, the potential to detect a single neutron multiple times historically has been one of the properties of organic scintillator detectors that has prevented their adoption for international safeguards applications. Consequently, as part of the analysis of simulated data, a method was developed by which true neutron-neutron coincidences can be distinguished from inter-detector scatter that takes advantage of the position and timing resolution of segmented detectors. Then, the performance of the notional simulated coincidence collar was evaluated for assaying a variety of fresh fuels, including some containing burnable poisons and partial defects. In these simulations, particular attention was paid to the analysis of fast mode measurements. In fast mode, a Cd liner is placed inside the collar to shield the fuel from the interrogating source and detector moderators, thereby eliminating the thermal neutron flux that is most sensitive to the presence of burnable poisons that are ubiquitous in modern nuclear fuels. The simulations indicate that the predicted precision of fast mode measurements is similar to what can be achieved by the present UNCL in thermal mode. For example, the statistical accuracy of a

  5. Mutations induced in plant breeding

    Energy Technology Data Exchange (ETDEWEB)

    Barriga B, P. (Universidad Austral de Chile, Valdivia. Inst. de Produccion y Sanidad Vegetal)

    1984-10-01

    The most significant aspects of the use of ionizing radiations in plant breeding are reviewed. Aspects such as basic principles of mutation, expression and selection in obtention of mutants, methods for using induced mutations and sucess achieved with this methodology in plant breeding are reviewed. Results obtained in a program of induced mutation on wheat for high content of protein and lysine at the Universidad Austral de Chile are presented.

  6. Neutron signal transfer analysis

    CERN Document Server

    Pleinert, H; Lehmann, E

    1999-01-01

    A new method called neutron signal transfer analysis has been developed for quantitative determination of hydrogenous distributions from neutron radiographic measurements. The technique is based on a model which describes the detector signal obtained in the measurement as a result of the action of three different mechanisms expressed by signal transfer functions. The explicit forms of the signal transfer functions are determined by Monte Carlo computer simulations and contain only the distribution as a variable. Therefore an unknown distribution can be determined from the detector signal by recursive iteration. This technique provides a simple and efficient tool for analysis of this type while also taking into account complex effects due to the energy dependency of neutron interaction and single and multiple scattering. Therefore this method provides an efficient tool for precise quantitative analysis using neutron radiography, as for example quantitative determination of moisture distributions in porous buil...

  7. Temperature of neutron stars

    Science.gov (United States)

    Tsuruta, Sachiko

    2016-07-01

    We start with a brief introduction to the historical background in the early pioneering days when the first neutron star thermal evolution calculations predicted the presence of neutron stars hot enough to be observable. We then report on the first detection of neutron star temperatures by ROSAT X-ray satellite, which vindicated the earlier prediction of hot neutron stars. We proceed to present subsequent developments, both in theory and observation, up to today. We then discuss the current status and the future prospect, which will offer useful insight to the understanding of basic properties of ultra-high density matter beyond the nuclear density, such as the possible presence of such exotic particles as pion condensates.

  8. Decoherence Free Neutron Interferometry

    CERN Document Server

    Pushin, Dmitry A; Cory, David G

    2016-01-01

    Perfect single-crystal neutron interferometers are adversely sensitive to environmental disturbances, particularly mechanical vibrations. The sensitivity to vibrations results from the slow velocity of thermal neutrons and the long measurement time that are encountered in a typical experiment. Consequently, to achieve a good interference solutions for reducing vibration other than those normally used in optical experiments must be explored. Here we introduce a geometry for a neutron interferometer that is less sensitive to low-frequency vibrations. This design may be compared with both dynamical decoupling methods and decoherence-free subspaces that are described in quantum information processing. By removing the need for bulky vibration isolation setups, this design will make it easier to adopt neutron interferometry to a wide range of applications and increase its sensitivity.

  9. Neutron Stars Recent Developments

    CERN Document Server

    Heiselberg, H

    1999-01-01

    Recent developments in neutron star theory and observation are discussed. Based on modern nucleon-nucleon potentials more reliable equations of state for dense nuclear matter have been constructed. Furthermore, phase transitions such as pion, kaon and hyperon condensation, superfluidity and quark matter can occur in cores of neutron stars. Specifically, the nuclear to quark matter phase transition and its mixed phases with intriguing structures is treated. Rotating neutron stars with and without phase transitions are discussed and compared to observed masses, radii and glitches. The observations of possible heavy $\\sim 2M_\\odot$ neutron stars in X-ray binaries and QPO's require relatively stiff equation of states and restrict strong phase transitions to occur at very high nuclear densities only.

  10. The intense neutron generator

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, W.B

    1966-07-01

    The presentation discusses both the economic and research contexts that would be served by producing neutrons in gram quantities at high intensities by electrical means without uranium-235. The revenue from producing radioisotopes is attractive. The array of techniques introduced by the multipurpose 65 megawatt Intense Neutron Generator project includes liquid metal cooling, superconducting magnets for beam bending and focussing, super-conductors for low-loss high-power radiofrequency systems, efficient devices for producing radiofrequency power, plasma physics developments for producing and accelerating hydrogen, ions at high intensity that are still far out from established practice, a multimegawatt high voltage D.C. generating machine that could have several applications. The research fields served relate principally to materials science through neutron-phonon and other quantum interactions as well as through neutron diffraction. Nuclear physics is served through {mu}-, {pi}- and K-meson production. Isotope production enters many fields of applied research. (author)

  11. Digital coincidence counting (DCC) and its use in the corrections for out-of-channel gamma events in 4pi beta-gamma coincidence counting.

    Science.gov (United States)

    Keightle, J D; Watt, G C

    2002-01-01

    The digital coincidence counting system developed by NPL and ANSTO is briefly described along with its benefits in the data collection and processing for the 4pi beta-gamma coincidence counting technique of radionuclide standardization. One of these benefits is the automatic detection of and correction for out-of-channel coincidences in the Computer Discrimination method. Where the criteria for the use of the Cox-Isham/Smith correction formulae for dead times and resolving times are not met, a generalized approximation based on the work of Campion is suggested.

  12. Calcium in plant cells

    Directory of Open Access Journals (Sweden)

    V. V. Schwartau

    2014-04-01

    regulation of calcium homeostasis in plant cells are reviewed. Data presented in the paper is important for understanding the role of calcium in the ions’ homeostasis and can be used for developing high-performance technologies of crops nutrition.

  13. Clusters in neutron-rich light nuclei

    Directory of Open Access Journals (Sweden)

    Jelavić Malenica D.

    2016-01-01

    Full Text Available Due to their high selectivity, transfer and sequential decay reactions are powerful tools for studies of both single particle (nucleon and cluster states in light nuclei. Their use is particularly simple for investigations of α-particle clustering (because α-particle has Jπ=0+, which simplifies spin and parity assignments to observed cluster states, but they are also easily applicable to other types of clustering. Recent results on clustering in neutron-rich isotopes of beryllium, boron and carbon obtained measuring the 10B+10B reactions (at 50 and 72 MeV are presented. The highly efficient and segmented detector systems used, built from 4 Double Sided Silicon Strip Detectors (DSSSD allowed detection of double and multiple coincidences and, in that way, studies of states populated in transfer reactions, as well as their sequential decay.

  14. Introduction to neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, W.E. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1996-11-01

    We give here an introduction to the theoretical principles of neutron scattering. The relationship between scattering- and correlation-functions is particularly emphasized. Within the framework of linear response theory (justified by the weakness of the basic interaction) the relation between fluctuation and dissipation is discussed. This general framework explains the particular power of neutron scattering as an experimental method. (author) 4 figs., 4 refs.

  15. Neutron scattering in dimers

    DEFF Research Database (Denmark)

    Gudel, H. U.; Furrer, A.; Kjems, Jørgen

    1986-01-01

    Insulating compounds containing dimers of transition metal and rare earth ions have been studied by inelastic neutron scattering (INS). Energy splittings can be directly determined, and the corresponding parameters are easily extracted from the experimental data. The intensities of dimer excitati......Insulating compounds containing dimers of transition metal and rare earth ions have been studied by inelastic neutron scattering (INS). Energy splittings can be directly determined, and the corresponding parameters are easily extracted from the experimental data. The intensities of dimer...

  16. Pulsed spallation Neutron Sources

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, J.M. [Argonne National Lab., IL (United States)

    1994-12-31

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

  17. Neutron scattering in Australia

    Energy Technology Data Exchange (ETDEWEB)

    Knott, R.B. [Australian Nuclear Science and Technology Organisation, Menai (Australia)

    1994-12-31

    Neutron scattering techniques have been part of the Australian scientific research community for the past three decades. The High Flux Australian Reactor (HIFAR) is a multi-use facility of modest performance that provides the only neutron source in the country suitable for neutron scattering. The limitations of HIFAR have been recognized and recently a Government initiated inquiry sought to evaluate the future needs of a neutron source. In essence, the inquiry suggested that a delay of several years would enable a number of key issues to be resolved, and therefore a more appropriate decision made. In the meantime, use of the present source is being optimized, and where necessary research is being undertaken at major overseas neutron facilities either on a formal or informal basis. Australia has, at present, a formal agreement with the Rutherford Appleton Laboratory (UK) for access to the spallation source ISIS. Various aspects of neutron scattering have been implemented on HIFAR, including investigations of the structure of biological relevant molecules. One aspect of these investigations will be presented. Preliminary results from a study of the interaction of the immunosuppressant drug, cyclosporin-A, with reconstituted membranes suggest that the hydrophobic drug interdigitated with lipid chains.

  18. Coded source neutron imaging

    Energy Technology Data Exchange (ETDEWEB)

    Bingham, Philip R [ORNL; Santos-Villalobos, Hector J [ORNL

    2011-01-01

    Coded aperture techniques have been applied to neutron radiography to address limitations in neutron flux and resolution of neutron detectors in a system labeled coded source imaging (CSI). By coding the neutron source, a magnified imaging system is designed with small spot size aperture holes (10 and 100 m) for improved resolution beyond the detector limits and with many holes in the aperture (50% open) to account for flux losses due to the small pinhole size. An introduction to neutron radiography and coded aperture imaging is presented. A system design is developed for a CSI system with a development of equations for limitations on the system based on the coded image requirements and the neutron source characteristics of size and divergence. Simulation has been applied to the design using McStas to provide qualitative measures of performance with simulations of pinhole array objects followed by a quantitative measure through simulation of a tilted edge and calculation of the modulation transfer function (MTF) from the line spread function. MTF results for both 100um and 10um aperture hole diameters show resolutions matching the hole diameters.

  19. Coded source neutron imaging

    Science.gov (United States)

    Bingham, Philip; Santos-Villalobos, Hector; Tobin, Ken

    2011-03-01

    Coded aperture techniques have been applied to neutron radiography to address limitations in neutron flux and resolution of neutron detectors in a system labeled coded source imaging (CSI). By coding the neutron source, a magnified imaging system is designed with small spot size aperture holes (10 and 100μm) for improved resolution beyond the detector limits and with many holes in the aperture (50% open) to account for flux losses due to the small pinhole size. An introduction to neutron radiography and coded aperture imaging is presented. A system design is developed for a CSI system with a development of equations for limitations on the system based on the coded image requirements and the neutron source characteristics of size and divergence. Simulation has been applied to the design using McStas to provide qualitative measures of performance with simulations of pinhole array objects followed by a quantitative measure through simulation of a tilted edge and calculation of the modulation transfer function (MTF) from the line spread function. MTF results for both 100μm and 10μm aperture hole diameters show resolutions matching the hole diameters.

  20. Neutron Nucleic Acid Crystallography.

    Science.gov (United States)

    Chatake, Toshiyuki

    2016-01-01

    The hydration shells surrounding nucleic acids and hydrogen-bonding networks involving water molecules and nucleic acids are essential interactions for the structural stability and function of nucleic acids. Water molecules in the hydration shells influence various conformations of DNA and RNA by specific hydrogen-bonding networks, which often contribute to the chemical reactivity and molecular recognition of nucleic acids. However, X-ray crystallography could not provide a complete description of structural information with respect to hydrogen bonds. Indeed, X-ray crystallography is a powerful tool for determining the locations of water molecules, i.e., the location of the oxygen atom of H2O; however, it is very difficult to determine the orientation of the water molecules, i.e., the orientation of the two hydrogen atoms of H2O, because X-ray scattering from the hydrogen atom is very small.Neutron crystallography is a specialized tool for determining the positions of hydrogen atoms. Neutrons are not diffracted by electrons, but are diffracted by atomic nuclei; accordingly, neutron scattering lengths of hydrogen and its isotopes are comparable to those of non-hydrogen atoms. Therefore, neutron crystallography can determine both of the locations and orientations of water molecules. This chapter describes the current status of neutron nucleic acid crystallographic research as well as the basic principles of neutron diffraction experiments performed on nucleic acid crystals: materials, crystallization, diffraction experiments, and structure determination.

  1. MAGNETIC NEUTRON SCATTERING

    Energy Technology Data Exchange (ETDEWEB)

    ZALIZNYAK,I.A.; LEE,S.H.

    2004-07-30

    Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern

  2. MAGNETIC NEUTRON SCATTERING

    Energy Technology Data Exchange (ETDEWEB)

    ZALIZNYAK,I.A.; LEE,S.H.

    2004-07-30

    Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern

  3. Obesidade e asma: associação ou coincidência? Obesity and asthma: association or coincidence?

    Directory of Open Access Journals (Sweden)

    Daniella Fernandes Camilo

    2010-02-01

    Full Text Available OBJETIVO: A asma e a obesidade estão entre as maiores causas de morbidade na infância e adolescência. A obesidade precoce aumenta as chances de doenças crônicas degenerativas no adulto. Embora a concomitância de ambas as situações clínicas vem sendo demonstrada em vários estudos, os mecanismos intrínsecos dessa associação ainda são pouco conhecidos. Portanto, o objetivo deste artigo foi revisar os principais trabalhos sobre a associação de obesidade e asma e verificar se existe relação de causa e efeito entre ambas. FONTES DOS DADOS: Revisão sistemática baseada em bases de dados indexadas MEDLINE (PubMed e SciELO. Foram revisados artigos originais (transversal, caso-controle e prospectivo e meta-análises publicados no período de janeiro de 1998 a janeiro de 2008. Foram pesquisados estudos divulgados em língua inglesa, espanhola e portuguesa. SÍNTESE DOS DADOS: Embora existam muitos estudos sobre as crescentes prevalências da asma e da obesidade, poucos estabelecem relações de causa e efeito entre ambas. Os mecanismos fisiopatológicos e os fatores envolvidos nesse processo ainda são pouco conhecidos. CONCLUSÃO: O rigor metodológico em estudos futuros deverá buscar respostas para melhor entender se existe associação entre asma e obesidade, ou se a relação entre ambas as doenças é coincidência.OBJECTIVE: Asthma and obesity are among the major causes of morbidity in childhood and adolescence. Early obesity increases the chances of chronic degenerative diseases in adults. Although the concomitance or both clinical situations are being demonstrated in various studies, the intrinsic mechanisms of this association are still very little known. Therefore, the objective of this article was to review the main studies on the association of obesity and asthma and check if there is a cause-effect relation between them. SOURCES: Systematic review based on indexed data bases MEDLINE (PubMed and SciELO. Original articles

  4. Neutron spectroscopy by thermalization light yield measurement in a composite heterogeneous scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Shi, T.; Nattress, J.; Mayer, Michael F.; Lin, M-W; Jovanovic, Igor

    2016-12-11

    An exothermic neutron capture reaction can be used to uniquely identify neutrons in particle detectors. With the use of a capture-gated coincidence technique, the sequence of scatter events that lead to neutron thermalization prior to the neutron capture can also be used to measure neutron energy. We report on the measurement of thermalization light yield via a time-of-flight technique in a polyvinyl toluene-based scintillator EJ-290 within a heterogeneous composite detector that also includes 6Li-doped glass scintillator. The thermalization light output exhibits a strong correlation with neutron energy because of the preference for near-complete energy deposition prior to the 6Li(n,t)4He neutron capture reaction. The nonproportionality of the light yield from nuclear recoils contributes to the observed broadening of the distribution of thermalization light output. The nonproportional dependence of the scintillation light output in the EJ-290 scintillator as a function of proton recoil energy has been characterized in the range of 0.3–14.1 MeV via the Birks parametrization through a combination of time-of-flight measurement and previously conducted measurements with Monoenergetic neutron sources.

  5. Fundamental neutron physics at LANSCE

    Energy Technology Data Exchange (ETDEWEB)

    Greene, G.

    1995-10-01

    Modern neutron sources and science share a common origin in mid-20th-century scientific investigations concerned with the study of the fundamental interactions between elementary particles. Since the time of that common origin, neutron science and the study of elementary particles have evolved into quite disparate disciplines. The neutron became recognized as a powerful tool for studying condensed matter with modern neutron sources being primarily used (and justified) as tools for neutron scattering and materials science research. The study of elementary particles has, of course, led to the development of rather different tools and is now dominated by activities performed at extremely high energies. Notwithstanding this trend, the study of fundamental interactions using neutrons has continued and remains a vigorous activity at many contemporary neutron sources. This research, like neutron scattering research, has benefited enormously by the development of modern high-flux neutron facilities. Future sources, particularly high-power spallation sources, offer exciting possibilities for continuing this research.

  6. The coincidence of IgA nephropathy and Fabry disease

    Directory of Open Access Journals (Sweden)

    Maixnerová Dita

    2013-01-01

    Full Text Available Abstract Background IgA nephropathy (IgAN is the most common glomerulonephritis, which may also coexist with other diseases. We present two patients with an unusual coincidence of IgAN and Fabry disease (FD. Case presentation A 26 year-old man underwent a renal biopsy in February 2001. Histopathology showed very advanced IgAN and vascular changes as a result of hypertension. Because of his progressive renal insufficiency the patient began hemodialysis in August 2001. By means of the blood spot test screening method the diagnosis of FD was suspected. Low activity of alpha-galactosidase A in the patient’s plasma and leukocytes and DNA analysis confirmed the diagnosis of FD. Enzyme replacement therapy started in July 2004. Then the patient underwent kidney transplantation in November 2005. Currently, his actual serum creatinine level is 250 μmol/l. Other organ damages included hypertrophic cardiomyopathy, neuropathic pain and febrile crisis. After enzyme replacement therapy, myocardial hypertrophy has stabilized and other symptoms have disappeared. No further progression of the disease has been noted. The other patient, a 30 year-old woman, suffered from long-term hematuria with a good renal function. Recently, proteinuria (2.6 g/day appeared and a renal biopsy was performed. Histopathology showed IgAN with remarkably enlarged podocytes. A combination of IgAN and a high suspicion of FD was diagnosed. Electron microscopy revealed dense deposits in paramesangial areas typical for IgAN and podocytes with inclusive zebra bodies and myelin figures characteristic of FD. FD was confirmed by the decreased alpha-galactosidase A activity in plasma and leukocytes and by DNA and RNA analysis. Enzyme replacement therapy and family screening were initiated. Conclusions Our results emphasize the role of complexity in the process of diagnostic evaluation of kidney biopsy samples. Electron microscopy represents an integral part of histopathology, and genetic

  7. The basis for design of a DSP-based coincidence spectrometer

    CERN Document Server

    Khang, Pham Dinh; Dien, Nguyen Nhi; Tuan, Pham Ngoc; Lanh, Dang; Hoa, Nguyen Duc; Son, Nguyen An

    2013-01-01

    Coincidence technique and the coincidence measurement systems have been developed and applied for over 40 years. Most of popular coincidence measurement systems were based on analog electronics techniques such as time to amplitude conversion (TAC) or logic selecting coincidence unit. The above-mentioned systems are relatively cumbersome and complicated to use. With the strong growth of digital electronics techniques and computational science, the coincidence measurement systems will be constructed simpler but more efficient with the sake of application. This article presents the design principle and signal processing of a simple two-channel coincidence system by a new technique called Digital Signal Processing (DSP) using Field Programmable Gate Arrays (FPGA) devices at Nuclear Research Institute (NRI), Dalat.

  8. The basis for design and manufacture of a dsp-based coincidence spectrometer

    CERN Document Server

    Hai, N X; Dien, N N; Lanh, D; Huong, T T T; Khang, P D

    2013-01-01

    The coincidence technique and the coincidence spectroscopy have been developed and applied for over 40 years. Most of popular coincidence measurement systems were based on analog electronics techniques such as time to amplitude conversion (TAC) or logic selecting coincidence unit. The above-mentioned systems are relatively cumbersome and complicated to use. With the strong growth of digital electronics techniques and computational science, the coincidence measurement systems will be constructed simpler but more efficient with the sake of application. This article presents the design principle and signal processing of a simple two-channel coincidence system by a technique of Digital Signal Processing (DSP) using Field Programmable Gate Arrays (FPGA) devices at Nuclear Research Institute (NRI), Dalat.

  9. Coincidence and covariance data acquisition in photoelectron and -ion spectroscopy. II. Analysis and applications

    Science.gov (United States)

    Mikosch, Jochen; Patchkovskii, Serguei

    2013-10-01

    We use an analytical theory of noisy Poisson processes, developed in the preceding companion publication, to compare coincidence and covariance measurement approaches in photoelectron and -ion spectroscopy. For non-unit detection efficiencies, coincidence data acquisition (DAQ) suffers from false coincidences. The rate of false coincidences grows quadratically with the rate of elementary ionization events. To minimize false coincidences for rare event outcomes, very low event rates may hence be required. Coincidence measurements exhibit high tolerance to noise introduced by unstable experimental conditions. Covariance DAQ on the other hand is free of systematic errors as long as stable experimental conditions are maintained. In the presence of noise, all channels in a covariance measurement become correlated. Under favourable conditions, covariance DAQ may allow orders of magnitude reduction in measurement times. Finally, we use experimental data for strong-field ionization of 1,3-butadiene to illustrate how fluctuations in experimental conditions can contaminate a covariance measurement, and how such contamination can be detected.

  10. Radiography with polarised neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Michael L.

    2010-08-20

    In this thesis I present a new technique for the spatially resolved investigation of the magnetic properties of bulk samples. Standard one dimensional neutron depolarisation analysis is combined with neutron radiography to a method we call Neutron Depolarisation Imaging (NDI). The experimental setup which was installed at the neutron radiography beam line ANTARES at FRM II consists of a double crystal monochromator, neutron polariser, spin flipper, polarisation analyser and a position sensitive CCD detector. A comprehensive discussion of the requirements for these components is given and the limitations of the method are shown. The maximum spatial resolution which can be achieved with a neutron radiography setup is determined by the collimation of the neutron beam and the distance between sample and detector. Different types of polarisers have been tested and their advantages and disadvantages are discussed. A double crystal monochromator and a new type of polariser employing polarising neutron supermirrors based on the principle of an optical periscope were developed and tested during this work. Furthermore, NDI measurements on various samples of the weakly ferromagnetic materials Pd{sub 1-x}Ni{sub x} and Ni{sub 3}Al are presented. Neutron depolarisation radiography and tomography measurements were conducted with a spatial resolution as high as 0.3 mm on Pd{sub 1-x}Ni{sub x} and Ni{sub 3}Al samples. The feasibility of NDI experiments under hydrostatic pressures up to 10 kbar was shown on a sample of Ni{sub 3}Al using a modified Cu:Be clamp cell. A decrease of the ordering temperature by 2 K under hydrostatic pressure was determined from the NDI measurements and shows the potential of the method for further high pressure experiments. Additionally a method was developed which in principle allows to obtain the intrinsic dependence of the ordering temperature T{sub C} on the ordered moment Ms from NDI measurements on inhomogeneous samples containing regions with

  11. Studies on the true coincidence correction in measuring filter samples by gamma spectrometry

    CERN Document Server

    Lian Qi; Chang Yong Fu; Xia Bing

    2002-01-01

    The true coincidence correction in measuring filter samples has been studied by high efficiency HPGe gamma detectors. The true coincidence correction for a specific three excited levels de-excitation case has been analyzed, and the typical analytical expressions of true coincidence correction factors have been given. According to the measured relative efficiency on the detector surface with 8 'single' energy gamma emitters and efficiency of filter samples, the peak and total efficiency surfaces are fitted. The true coincidence correction factors of sup 6 sup 0 Co and sup 1 sup 5 sup 2 Eu calculated by the efficiency surfaces agree well with experimental results

  12. Error Analysis of Radar Coincidence Imaging in the Presence of Noise

    Directory of Open Access Journals (Sweden)

    Dai Qiang

    2014-10-01

    Full Text Available Radar coincidence imaging is a new method for high-resolution staring imaging. First, the mathematical model is constructed. Second, the theoretical error for radar coincidence imaging in the presence of noise is derived using the parametric imaging method. Third, the factors that affect the error are analyzed. Fourth, the sparse reconstruction algorithm is used to perform numerical simulations of radar coincidence imaging with different parameters. Finally, the effects of signal bandwidth, array configuration, size of the imaging unit, and target complexity on image error in the presence of noise are discussed. This study provides the theoretical framework for parameters selection and SNR requirements for radar coincidence imaging systems.

  13. Neutron-Induced Failures in Semiconductor Devices

    Energy Technology Data Exchange (ETDEWEB)

    Wender, Stephen Arthur [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-04-06

    This slide presentation explores single event effect, environmental neutron flux, system response, the Los Alamos Neutron Science Center (LANSCE) neutron testing facility, examples of SEE measurements, and recent interest in thermal neutrons.

  14. High-energy Neutron-induced Fission Cross Sections of Natural Lead and Bismuth-209

    CERN Document Server

    Tarrio, D; Carrapico, C; Eleftheriadis, C; Leeb, H; Calvino, F; Herrera-Martinez, A; Savvidis, I; Vlachoudis, V; Haas, B; Koehler, P; Vannini, G; Oshima, M; Le Naour, C; Gramegna, F; Wiescher, M; Pigni, M T; Audouin, L; Mengoni, A; Quesada, J; Becvar, F; Plag, R; Cennini, P; Mosconi, M; Rauscher, T; Couture, A; Capote, R; Sarchiapone, L; Vlastou, R; Domingo-Pardo, C; Dillmann, I; Pavlopoulos, P; Karamanis, D; Krticka, M; Jericha, E; Ferrari, A; Martinez, T; Trubert, D; Oberhummer, H; Karadimos, D; Plompen, A; Isaev, S; Terlizzi, R; Cortes, G; Cox, J; Cano-Ott, D; Pretel, C; Colonna, N; Berthoumieux, E; Vaz, P; Heil, M; Lopes, I; Lampoudis, C; Walter, S; Calviani, M; Gonzalez-Romero, E; Embid-Segura, M; Stephan, C; Igashira, M; Papachristodoulou, C; Aerts, G; Tavora, L; Berthier, B; Rudolf, G; Andrzejewski, J; Villamarin, D; Ferreira-Marques, R; Tain, J L; O'Brien, S; Reifarth, R; Kadi, Y; Neves, F; Poch, A; Kerveno, M; Rubbia, C; Lazano, M; Dahlfors, M; Wisshak, K; Salgado, J; Dridi, W; Ventura, A; Andriamonje, S; Assimakopoulos, P; Santos, C; Voss, F; Ferrant, L; Patronis, N; Chiaveri, E; Guerrero, C; Perrot, L; Vicente, M C; Lindote, A; Praena, J; Baumann, P; Kappeler, F; Rullhusen, P; Furman, W; David, S; Marrone, S; Tassan-Got, L; Gunsig, F; Alvarez-Velarde, F; Massimi, C; Mastinu, P; Pancin, J; Papadopoulos, C; Tagliente, G; Haight, R; Chepel, V; Kossionides, E; Badurek, G; Marganiec, J; Lukic, S; Pavlik, A; Goncalves, I; Duran, I; Alvarez, H; Abbondanno, U; Fujii, K; Milazzo, P M; Moreau, C

    2011-01-01

    The CERN Neutron Time-Of-Flight (n\\_TOF) facility is well suited to measure small neutron-induced fission cross sections, as those of subactinides. The cross section ratios of (nat)Pb and (209)Bi relative to (235)U and (238)U were measured using PPAC detectors. The fragment coincidence method allows to unambiguously identify the fission events. The present experiment provides the first results for neutron-induced fission up to 1 GeV for (nat)Pb and (209)Bi. A good agreement with previous experimental data below 200 MeV is shown. The comparison with proton-induced fission indicates that the limiting regime where neutron-induced and proton-induced fission reach equal cross section is close to 1 GeV.

  15. An alpha particle detector for a portable neutron generator for the Nuclear Materials Identification System (NMIS)

    Science.gov (United States)

    Hausladen, P. A.; Neal, J. S.; Mihalczo, J. T.

    2005-12-01

    A recoil alpha particle detector has been developed for use in a portable neutron generator. The associated particle sealed tube neutron generator (APSTNG) will be used as an interrogation source for the Nuclear Materials Identification System (NMIS). With the coincident emission of 14.1 MeV neutrons and 3.5 MeV alpha particles produced by the D-T reaction, alpha detection determines the time and direction of the neutrons of interest for subsequent use as an active nuclear materials interrogation source. The alpha particle detector uses a ZnO(Ga) scintillator coating applied to a fiber optic face plate. Gallium-doped zinc oxide is a fast (inorganic scintillator with a high melting point (1975 °C). One detector has been installed in an APSTNG and is currently being tested. Initial results include a measured efficiency for 3.5 MeV alphas of 90%.

  16. Proton recoil telescope based on diamond detectors for measurement of fusion neutrons

    CERN Document Server

    Caiffi, B; Ripani, M; Pillon, M; Taiuti, M

    2015-01-01

    Diamonds are very promising candidates for the neutron diagnostics in harsh environments such as fusion reactor. In the first place this is because of their radiation hardness, exceeding that of Silicon by an order of magnitude. Also, in comparison to the standard on-line neutron diagnostics (fission chambers, silicon based detectors, scintillators), diamonds are less sensitive to $\\gamma$ rays, which represent a huge background in fusion devices. Finally, their low leakage current at high temperature suppresses the detector intrinsic noise. In this talk a CVD diamond based detector has been proposed for the measurement of the 14 MeV neutrons from D-T fusion reaction. The detector was arranged in a proton recoil telescope configuration, featuring a plastic converter in front of the sensitive volume in order to induce the (n,p) reaction. The segmentation of the sensitive volume, achieved by using two crystals, allowed to perform measurements in coincidence, which suppressed the neutron elastic scattering backg...

  17. Optimal gate-width setting for passive neutrons multiplicity counting

    Energy Technology Data Exchange (ETDEWEB)

    Croft, Stephen [Los Alamos National Laboratory; Evans, Louise G [Los Alamos National Laboratory; Schear, Melissa A [Los Alamos National Laboratory

    2010-01-01

    When setting up a passive neutron coincidence counter it is natural to ask what coincidence gate settings should be used to optimize the counting precision. If the gate width is too short then signal is lost and the precision is compromised because in a given period only a few coincidence events will be observed. On the other hand if the gate is too large the signal will be maximized but it will also be compromised by the high level of random pile-up or Accidental coincidence events which must be subtracted. In the case of shift register electronics connected to an assay chamber with an exponential dieaway profile operating in the regime where the Accidentals rate dominates the Reals coincidence rate but where dead-time is not a concern, simple arguments allow one to show that the relative precision on the net Reals rate is minimized when the coincidence gate is set to about 1.2 times the lie dieaway time of the system. In this work we show that making the same assumptions it is easy to show that the relative precision on the Triples rates is also at a minimum when the relative precision of the Doubles (or Reals) is at a minimum. Although the analysis is straightforward to our knowledge such a discussion has not been documented in the literature before. Actual measurement systems do not always behave in the ideal we choose to model them. Fortunately however the variation in the relative precision as a function of gate width is rather flat for traditional safeguards counters and so the performance is somewhat forgiving of the exact choice. The derivation further serves to delineate the important parameters which determine the relative counting precision of the Doubles and Triples rates under the regime considered. To illustrate the similarities and differences we consider the relative standard deviation that might be anticipated for a passive correlation count of an axial section of a spent nuclear fuel assembly under practically achievable conditions.

  18. Neutron drip transition in accreting and nonaccreting neutron star crusts

    CERN Document Server

    Chamel, N; Zdunik, J L; Haensel, P

    2015-01-01

    The neutron-drip transition in the dense matter constituting the interior of neutron stars generally refers to the appearance of unbound neutrons as the matter density reaches some threshold density $\\rho_\\textrm{drip}$. This transition has been mainly studied under the cold catalyzed matter hypothesis. However, this assumption is unrealistic for accreting neutron stars. After examining the physical processes that are thought to be allowed in both accreting and nonaccreting neutron stars, suitable conditions for the onset of neutron drip are derived and general analytical expressions for the neutron drip density and pressure are obtained. Moreover, we show that the neutron-drip transition occurs at lower density and pressure than those predicted within the mean-nucleus approximation. This transition is studied numerically for various initial composition of the ashes from X-ray bursts and superbursts using microscopic nuclear mass models.

  19. Alternative Splicing in Plant Immunity

    Directory of Open Access Journals (Sweden)

    Shengming Yang

    2014-06-01

    Full Text Available Alternative splicing (AS occurs widely in plants and can provide the main source of transcriptome and proteome diversity in an organism. AS functions in a range of physiological processes, including plant disease resistance, but its biological roles and functional mechanisms remain poorly understood. Many plant disease resistance (R genes undergo AS, and several R genes require alternatively spliced transcripts to produce R proteins that can specifically recognize pathogen invasion. In the finely-tuned process of R protein activation, the truncated isoforms generated by AS may participate in plant disease resistance either by suppressing the negative regulation of initiation of immunity, or by directly engaging in effector-triggered signaling. Although emerging research has shown the functional significance of AS in plant biotic stress responses, many aspects of this topic remain to be understood. Several interesting issues surrounding the AS of R genes, especially regarding its functional roles and regulation, will require innovative techniques and additional research to unravel.

  20. Parallel Ecological Speciation in Plants?

    Directory of Open Access Journals (Sweden)

    Katherine L. Ostevik

    2012-01-01

    Full Text Available Populations that have independently evolved reproductive isolation from their ancestors while remaining reproductively cohesive have undergone parallel speciation. A specific type of parallel speciation, known as parallel ecological speciation, is one of several forms of evidence for ecology's role in speciation. In this paper we search the literature for candidate examples of parallel ecological speciation in plants. We use four explicit criteria (independence, isolation, compatibility, and selection to judge the strength of evidence for each potential case. We find that evidence for parallel ecological speciation in plants is unexpectedly scarce, especially relative to the many well-characterized systems in animals. This does not imply that ecological speciation is uncommon in plants. It only implies that evidence from parallel ecological speciation is rare. Potential explanations for the lack of convincing examples include a lack of rigorous testing and the possibility that plants are less prone to parallel ecological speciation than animals.

  1. Influence of the neutron transport tube on neutron resonance densitometry

    Directory of Open Access Journals (Sweden)

    Kitatani Fumito

    2017-01-01

    Full Text Available Neutron Resonance Densitometry (NRD is a non-destructive assay technique of nuclear materials in particle-like debris that contains various materials. An aim of NRD is to quantify nuclear materials in a melting fuel of Fukusima Daiichi plant, spent nuclear fuel and annihilation disposal fuel etc. NRD consists of two techniques of Neutron Resonance Transmission Analysis (NRTA and Neutron Resonance Capture Analysis (NRCA or Prompt Gamma-ray Analysis (PGA. A density of nuclear material isotopes is decided with NRTA. The materials absorbing a neutron in a wide energy range such as boron in a sample are identified by NRCA/PGA. The information of NRCA/PGA is used in NRTA analysis to quantify nuclear material isotopes. A neutron time of flight (TOF method is used in NRD measurements. A facility, consisting of a neutron source, a neutron flight path, and a detector is required. A short flight path and a strong neutron source are needed to downsize such a facility and put NRD into practical use. A neutron transport tube covers a flight path to prevent noises. In order to investigate the effect of neutron transport tube and pulse width of a neutron source, we carried out NRTA experiments with a 2-m short neutron transport tube constructed at Kyoto University Research Reactor Institute - Linear Accelerator (KURRI-LINAC, and impacts of shield of neutron transport tube and influence of pulse width of a neutron source were examined. A shield of the neutron transport tube reduced a background and had a good influence on the measurement. The resonance dips of 183W at 27 eV was successfully observed with a pulse width of a neutron source less than 2 μs.

  2. Hybrid superconducting neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Merlo, V.; Lucci, M.; Ottaviani, I. [Dipartimento di Fisica, Università Tor Vergata, Via della Ricerca Scientifica, I-00133 Roma (Italy); Salvato, M.; Cirillo, M. [Dipartimento di Fisica, Università Tor Vergata, Via della Ricerca Scientifica, I-00133 Roma (Italy); CNR SPIN Salerno, Università di Salerno, Via Giovanni Paolo II, n.132, 84084 Fisciano (Italy); Scherillo, A. [Science and Technology Facility Council, ISIS Facility Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Celentano, G. [ENEA Frascati Research Centre, Via. E. Fermi 45, 00044 Frascati (Italy); Pietropaolo, A., E-mail: antonino.pietropaolo@enea.it [ENEA Frascati Research Centre, Via. E. Fermi 45, 00044 Frascati (Italy); Mediterranean Institute of Fundamental Physics, Via Appia Nuova 31, 00040 Marino, Roma (Italy)

    2015-03-16

    A neutron detection concept is presented that is based on superconductive niobium (Nb) strips coated by a boron (B) layer. The working principle of the detector relies on the nuclear reaction, {sup 10}B + n → α + {sup 7}Li, with α and Li ions generating a hot spot on the current-biased Nb strip which in turn induces a superconducting-normal state transition. The latter is recognized as a voltage signal which is the evidence of the incident neutron. The above described detection principle has been experimentally assessed and verified by irradiating the samples with a pulsed neutron beam at the ISIS spallation neutron source (UK). It is found that the boron coated superconducting strips, kept at a temperature T = 8 K and current-biased below the critical current I{sub c}, are driven into the normal state upon thermal neutron irradiation. As a result of the transition, voltage pulses in excess of 40 mV are measured while the bias current can be properly modulated to bring the strip back to the superconducting state, thus resetting the detector. Measurements on the counting rate of the device are presented and the basic physical features of the detector are discussed.

  3. Hybrid Superconducting Neutron Detectors

    CERN Document Server

    Merlo, V; Cirillo, M; Lucci, M; Ottaviani, I; Scherillo, A; Celentano, G; Pietropaolo, A

    2014-01-01

    A new neutron detection concept is presented that is based on superconductive niobium (Nb) strips coated by a boron (B) layer. The working principle of the detector relies on the nuclear reaction 10B+n $\\rightarrow$ $\\alpha$+ 7Li , with $\\alpha$ and Li ions generating a hot spot on the current-biased Nb strip which in turn induces a superconducting-normal state transition. The latter is recognized as a voltage signal which is the evidence of the incident neutron. The above described detection principle has been experimentally assessed and verified by irradiating the samples with a pulsed neutron beam at the ISIS spallation neutron source (UK). It is found that the boron coated superconducting strips, kept at a temperature T = 8 K and current-biased below the critical current Ic, are driven into the normal state upon thermal neutron irradiation. As a result of the transition, voltage pulses in excess of 40 mV are measured while the bias current can be properly modulated to bring the strip back to the supercond...

  4. Neutron counting with cameras

    Energy Technology Data Exchange (ETDEWEB)

    Van Esch, Patrick; Crisanti, Marta; Mutti, Paolo [Institut Laue Langevin, Grenoble (France)

    2015-07-01

    A research project is presented in which we aim at counting individual neutrons with CCD-like cameras. We explore theoretically a technique that allows us to use imaging detectors as counting detectors at lower counting rates, and transits smoothly to continuous imaging at higher counting rates. As such, the hope is to combine the good background rejection properties of standard neutron counting detectors with the absence of dead time of integrating neutron imaging cameras as well as their very good spatial resolution. Compared to Xray detection, the essence of thermal neutron detection is the nuclear conversion reaction. The released energies involved are of the order of a few MeV, while X-ray detection releases energies of the order of the photon energy, which is in the 10 KeV range. Thanks to advances in camera technology which have resulted in increased quantum efficiency, lower noise, as well as increased frame rate up to 100 fps for CMOS-type cameras, this more than 100-fold higher available detection energy implies that the individual neutron detection light signal can be significantly above the noise level, as such allowing for discrimination and individual counting, which is hard to achieve with X-rays. The time scale of CMOS-type cameras doesn't allow one to consider time-of-flight measurements, but kinetic experiments in the 10 ms range are possible. The theory is next confronted to the first experimental results. (authors)

  5. Neutron whispering gallery

    Science.gov (United States)

    Nesvizhevsky, Valery V.; Voronin, Alexei Yu.; Cubitt, Robert; Protasov, Konstantin V.

    2010-02-01

    The `whispering gallery' effect has been known since ancient times for sound waves in air, later in water and more recently for a broad range of electromagnetic waves: radio, optics, Roentgen and so on. It consists of wave localization near a curved reflecting surface and is expected for waves of various natures, for instance, for atoms and neutrons. For matter waves, it would include a new feature: a massive particle would be settled in quantum states, with parameters depending on its mass. Here, we present for the first time the quantum whispering-gallery effect for cold neutrons. This phenomenon provides an example of an exactly solvable problem analogous to the `quantum bouncer'; it is complementary to the recently discovered gravitationally bound quantum states of neutrons . These two phenomena provide a direct demonstration of the weak equivalence principle for a massive particle in a pure quantum state. Deeply bound whispering-gallery states are long-living and weakly sensitive to surface potential; highly excited states are short-living and very sensitive to the wall potential shape. Therefore, they are a promising tool for studying fundamental neutron-matter interactions, quantum neutron optics and surface physics effects.

  6. Gamma-ray spectroscopy of neutron-rich products of heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, M.P.; Janssens, R.V.F.; Ahmad, I. [and others

    1995-08-01

    Thick-target {gamma}{gamma} coincidence techniques are being used to explore the spectroscopy of otherwise hard-to-reach neutron-rich products of deep-inelastic heavy ion reactions. Extensive {gamma}{gamma} coincidence measurements were performed at ATLAS using pulsed beams of {sup 80}Se, {sup 136}Xe, and {sup 238}U on lead-backed {sup 122,124}Sn targets with energies 10-15% above the Coulomb barrier. Gamma-ray coincidence intensities were used to map out yield distributions with A and Z for even-even product nuclei around the target and around the projectile. The main features of the yield patterns are understandable in terms of N/Z equilibration. We had the most success in studying the decays of yrast isomers. Thus far, more than thirty new {mu}s isomers in the Z = 50 region were found and characterized. Making isotopic assignments for previously unknown {gamma}-ray cascades proves to be one of the biggest problems. Our assignments were based (a) on rare overlaps with radioactivity data, (b) on the relative yields with different beams, and (c) on observed cross-coincidences between {gamma} rays from light and heavy reaction partners. However, the primary products of deep inelastic collisions often are sufficiently excited for subsequent neutron evaporation, so {gamma}{gamma} cross-coincidence results require careful interpretation.

  7. High-position-resolution scintillation neutron-imaging detector by crossed-fiber readout with novel centroid-finding method

    CERN Document Server

    Katagiri, M; Sakasai, K; Matsubayashi, M; Birumachi, A; Takahashi, H; Nakazawa, M

    2002-01-01

    Aiming at high-position-resolution and high-counting-rate neutron imaging, a novel centroid-finding method is proposed for a scintillation neutron-imaging detector with crossed-fiber readout. Crossed wavelength-shifting fibers are arranged on and under the scintillator. Luminescences generated in the scintillator are emitted and detected by a few fibers surrounding the incident point of a neutron. In the novel method, X and Y positions of the incident neutron are decided by coincidence of a central signal and neighboring signals, respectively. By fundamental experiments using a ZnS:Ag/ sup 6 LiF scintillator of 0.5-mm thickness and crossed wavelength-shifting fibers with a size of 0.5 x 0.5 mm sup 2 , it was confirmed that the position resolution is about 0.5 mm and the limitation of the neutron-counting rate is 320 kcps. (orig.)

  8. Electron Scattering From a High-Momentum Neutron in Deuterium

    Energy Technology Data Exchange (ETDEWEB)

    Klimenko, Alexei [Old Dominion Univ., Norfolk, VA (United States)

    2004-05-01

    The deuterium nucleus is a system of two nucleons (proton and neutron) bound together. The configuration of the system is described by a quantum-mechanical wave function and the state of the nucleons at a given time is not know a priori. However, by detecting a backward going proton of moderate momentum in coincidence with a reaction taking place on the neutron in deuterium, the initial state of that neutron can be inferred if we assume that the proton was a spectator to the reaction. This method, known as spectator tagging, was used to study the electron scattering from high-momentum neutrons in deuterium. The data were taken with a 5.765 GeV polarized electron beam on a deuterium target in Jefferson Laboratory's Hall B, using the CLAS detector. The accumulated data cover a wide kinematic range, reaching values of the invariant mass of the unobserved final state W* up to 3 GeV. A data sample of approximately 5 - 105 events, with protons detected at large scattering angles (as high as 136 degrees) in coincidence with the forward electrons, was selected. The product of the neutron structure function with the initial nucleon momentum distribution F2n. S was extracted for different values of W*, backward proton momenta ps and momentum transfer Q2. The data were compared to a calculation based on the spectator approximation and using the free nucleon form factors and structure functions. A strong enhancement in the data, not reproduced by the model, was observed at cos(thetapq) > -0.3 (where theta{sub pq} is the proton scattering angle relative to the direction of the momentum transfer) and can be associated with the contribution of final state interactions (FSI) that were not incorporated into the model. The bound nucleon structure function F2n was studied in the region cos(thetapq) < -0.3 as a function of W* and scaling variable x*. At high spectator proton momenta the struck neutron is

  9. Study of $\\beta$-delayed neutron decay of $^{8}$He

    CERN Multimedia

    The goal of the present proposal is to study $\\beta$-delayed neutron decay branch of $^{8}$He. The energy spectra of the emitted neutrons will be measured in the energy range of 0.1 – 6 MeV using the VANDLE spectrometer. Using coincident $\\gamma$-ray measurement, components of the spectrum corresponding to transitions to the ground- and first- excited states of $^{7}$Li will be disentangled. The new data will allow us to get a more complete picture of the $\\beta$-decay of $^{8}$He and to clarify the discrepancy between the B(GT) distributions derived from the $\\beta$-decay and $^{8}$He(p, n)$^{8}$Li reaction studies.

  10. Neutron detector array at IUAC: Design features and instrumentation developments

    Indian Academy of Sciences (India)

    P Sugathan; A Jhingan; K S Golda; T Varughese; S Venkataramanan; N Saneesh; V V Satyanarayana; S K Suman; J Antony; Ruby Shanti; K Singh; S K Saini; A Gupta; A Kothari; P Barua; Rajesh Kumar; J Zacharias; R P Singh; B R Behera; S K Mandal; I M Govil; R K Bhowmik

    2014-11-01

    The characteristics and performance of the newly commissioned neutron detector array at IUAC are described. The array consists of 100 BC501 liquid scintillators mounted in a semispherical geometry and are kept at a distance of 175 cm from the reaction point. Each detector is a 5″ × 5″ cylindrical cell coupled to 5″ diameter photomultiplier tube (PMT). Signal processing is realized using custom-designed home-made integrated electronic modules which perform neutron–gamma discrimination using zero cross timing and time-of-flight (TOF) technique. Compact custom-built high voltage power supply developed using DC–DC converters are used to bias the detector. The neutrons are recorded in coincidence with fission fragments which are detected using multi-wire proportional counters mounted inside a 1m diameter SS target chamber. The detectors and electronics have been tested off-line using radioactive sources and the results are presented.

  11. Passive neutron design study for 200-L waste drums

    Energy Technology Data Exchange (ETDEWEB)

    Menlove, H.O.; Beddingfield, D.B.; Pickrell, M.M. [and others

    1997-09-01

    We have developed a passive neutron counter for the measurement of plutonium in 200-L drums of scrap and waste. The counter incorporates high efficiency for the multiplicity counting in addition to the traditional coincidence counting. The {sup 252}Cf add-a-source feature is used to provide an accurate assay over a wide range of waste matrix materials. The room background neutron rate is reduced by using 30 cm of external polyethylene shielding and the cosmic-ray background is reduced by statistical filtering techniques. Monte Carlo Code calculations were used to determine the optimum detector design, including the gas pressure, size, number, and placement of the {sup 3}He tubes in the moderator. Various moderators, including polyethylene, plastics, teflon, and graphite, were evaluated to obtain the maximum efficiency and minimum detectable mass of plutonium.

  12. Level structures of neutron-rich Xe isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, I.; Lister, C.J.; Morss, L.R. [and others

    1995-08-01

    The level structures of neutron-rich Xe isotopes were determined by observing prompt gamma-ray coincidences in {sup 248}Cm fission fragments. A 5-mg {sup 248}Cm, in the form of {sup 248}Cm-KCl pellet, was placed inside Eurogam array which consisted of 45 Compton-suppressed Ge detectors and 5 Low-Energy Photon Spectrometers. Transitions in Xe isotopes were identified by the appearance of new peaks in the {gamma}-ray spectra obtained by gating on the gamma peaks of the complementary Mo fragments.

  13. Virtual neutron scattering experiments

    DEFF Research Database (Denmark)

    Overgaard, Julie Hougaard; Bruun, Jesper; May, Michael

    2017-01-01

    We describe how virtual experiments can be utilized in a learning design that prepares students for hands-on experiments at large-scale facilities. We illustrate the design by showing how virtual experiments are used at the Niels Bohr Institute in a master level course on neutron scattering....... In the last week of the course, students travel to a large-scale neutron scattering facility to perform real neutron scattering experiments. Through student interviews and survey answers, we argue, that the virtual training prepares the students to engage more fruitfully with experiments by letting them focus...... on physics and data rather than the overwhelming instrumentation. We argue that this is because they can transfer their virtual experimental experience to the real-life situation. However, we also find that learning is still situated in the sense that only knowledge of particular experiments is transferred...

  14. Virtual neutron scattering experiments

    DEFF Research Database (Denmark)

    Overgaard, Julie Hougaard; Bruun, Jesper; May, Michael

    2016-01-01

    We describe how virtual experiments can be utilized in a learning design that prepares students for hands-on experiments at large-scale facilities. We illustrate the design by showing how virtual experiments are used at the Niels Bohr Institute in a master level course on neutron scattering....... In the last week of the course, students travel to a large-scale neutron scattering facility to perform real neutron scattering experiments. Through student interviews and survey answers, we argue, that the virtual training prepares the students to engage more fruitfully with experiments by letting them focus...... on physics and data rather than the overwhelming instrumentation. We argue that this is because they can transfer their virtual experimental experience to the real-life situation. However, we also find that learning is still situated in the sense that only knowledge of particular experiments is transferred...

  15. Direction sensitive neutron detector

    Energy Technology Data Exchange (ETDEWEB)

    Ahlen, Steven; Fisher, Peter; Dujmic, Denis; Wellenstein, Hermann F.; Inglis, Andrew

    2017-01-31

    A neutron detector includes a pressure vessel, an electrically conductive field cage assembly within the pressure vessel and an imaging subsystem. A pressurized gas mixture of CF.sub.4, .sup.3He and .sup.4He at respective partial pressures is used. The field cage establishes a relatively large drift region of low field strength, in which ionization electrons generated by neutron-He interactions are directed toward a substantially smaller amplification region of substantially higher field strength in which the ionization electrons undergo avalanche multiplication resulting in scintillation of the CF.sub.4 along scintillation tracks. The imaging system generates two-dimensional images of the scintillation patterns and employs track-finding to identify tracks and deduce the rate and direction of incident neutrons. One or more photo-multiplier tubes record the time-profile of the scintillation tracks permitting the determination of the third coordinate.

  16. Neutron absorbing alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Masayuki

    1998-12-04

    The neutron absorbing alloy of the present invention comprises Ti or an alloy thereof as a mother material, to which from 2 to 40% by weight of Hf and Gd within a range of from 4 to 50% by weight in total are added respectively. Ti is excellent in specific strength, corrosion resistance and workability, and produces no noxious intermetallic compound with Hf and Gd. In addition, since the alloy can incorporate a great quantity of Hf and Gd, a neutron absorbing material having excellent neutron absorbing performance than usual and excellent in specific strength, corrosion resistance and workability can be manufactured conveniently and economically not by a special manufacturing method. (T.M.)

  17. Carbon neutron star atmospheres

    CERN Document Server

    Suleimanov, V F; Pavlov, G G; Werner, K

    2013-01-01

    The accuracy of measuring the basic parameters of neutron stars is limited in particular by uncertainties in chemical composition of their atmospheres. For example, atmospheres of thermally - emitting neutron stars in supernova remnants might have exotic chemical compositions, and for one of them, the neutron star in CasA, a pure carbon atmosphere has recently been suggested by Ho & Heinke (2009). To test such a composition for other similar sources, a publicly available detailed grid of carbon model atmosphere spectra is needed. We have computed such a grid using the standard LTE approximation and assuming that the magnetic field does not exceed 10^8 G. The opacities and pressure ionization effects are calculated using the Opacity Project approach. We describe the properties of our models and investigate the impact of the adopted assumptions and approximations on the emergent spectra.

  18. Uniformly rotating neutron stars

    CERN Document Server

    Boshkayev, Kuantay

    2016-01-01

    In this chapter we review the recent results on the equilibrium configurations of static and uniformly rotating neutron stars within the Hartle formalism. We start from the Einstein-Maxwell-Thomas-Fermi equations formulated and extended by Belvedere et al. (2012, 2014). We demonstrate how to conduct numerical integration of these equations for different central densities ${\\it \\rho}_c$ and angular velocities $\\Omega$ and compute the static $M^{stat}$ and rotating $M^{rot}$ masses, polar $R_p$ and equatorial $R_{\\rm eq}$ radii, eccentricity $\\epsilon$, moment of inertia $I$, angular momentum $J$, as well as the quadrupole moment $Q$ of the rotating configurations. In order to fulfill the stability criteria of rotating neutron stars we take into considerations the Keplerian mass-shedding limit and the axisymmetric secular instability. Furthermore, we construct the novel mass-radius relations, calculate the maximum mass and minimum rotation periods (maximum frequencies) of neutron stars. Eventually, we compare a...

  19. Corrosion resistant neutron absorbing coatings

    Science.gov (United States)

    Choi, Jor-Shan [El Cerrito, CA; Farmer, Joseph C [Tracy, CA; Lee, Chuck K [Hayward, CA; Walker, Jeffrey [Gaithersburg, MD; Russell, Paige [Las Vegas, NV; Kirkwood, Jon [Saint Leonard, MD; Yang, Nancy [Lafayette, CA; Champagne, Victor [Oxford, PA

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  20. Coincidence Point Theorems, Intersection Theorems and Saddle Point Theorems on FC-spaces

    Institute of Scientific and Technical Information of China (English)

    PIAO YONG-JIE; YIN ZHE

    2009-01-01

    In this paper, we first give the definitions of finitely continuous topological space and FC-subspace generated by some set, and obtain coincidence point theorem, whole intersection theorems and Ky Fan type matching theorems, and finally discuss the existence of saddle point as an application of coincidence point theorem.

  1. On coincidence problem and attractor solutions in ELKO dark energy model

    CERN Document Server

    Sadjadi, H Mohseni

    2011-01-01

    We study the critical points of a Universe dominated by ELKO spinor field dark energy and a barotropic matter in an almost general case. The coincidence problem and attractor solutions are discussed and it is shown the coincidence problem can not be alleviated in this model.

  2. Atmospheres around Neutron Stars

    Science.gov (United States)

    Fryer, Chris L.; Benz, Willy

    1994-12-01

    Interest in the behavior of atmospheres around neutron stars has grown astronomically in the past few years. Some of this interest arrived in the wake of the explosion of Supernova 1987A and its elusive remnant; spawning renewed interest in a method to insure material ``fall-back'' onto the adolescent neutron star in an effort to transform it into a silent black hole. However, the bulk of the activity with atmospheres around neutron stars is concentrated in stellar models with neutron star, rather than white dwarf, cores; otherwise known as Thorne-Zytkow objects. First a mere seed in the imagination of theorists, Thorne-Zytkow objects have grown into an observational reality with an ever-increasing list of formation scenarios and observational prospects. Unfortunately, the analytic work of Chevalier on supernova fall-back implies that, except for a few cases, the stellar simulations of Thorne-Zytkow objects are missing an important aspect of physics: neutrinos. Neutrino cooling removes the pressure support of these atmospheres, allowing accretion beyond the canonical Eddington rate for these objects. We present here the results of detailed hydrodynamical simulations in one and two dimensions with the additional physical effects of neutrinos, advanced equations of state, and relativity over a range of parameters for our atmosphere including entropy and chemical composition as well as a range in the neutron star size. In agreement with Chevalier, we find, under the current list of formation scenarios, that the creature envisioned by Thorne and Zytkow will not survive the enormous appetite of a neutron star. However, neutrino heating (a physical effect not considered in Chevalier's analysis) can play an important role in creating instabilities in some formation schemes, leading to an expulsion of matter rather than rapid accretion. By placing scrutiny upon the formation methods, we can determine the observational prospects for each.

  3. Pixelated neutron image plates

    Science.gov (United States)

    Schlapp, M.; Conrad, H.; von Seggern, H.

    2004-09-01

    Neutron image plates (NIPs) have found widespread application as neutron detectors for single-crystal and powder diffraction, small-angle scattering and tomography. After neutron exposure, the image plate can be read out by scanning with a laser. Commercially available NIPs consist of a powder mixture of BaFBr : Eu2+ and Gd2O3 dispersed in a polymer matrix and supported by a flexible polymer sheet. Since BaFBr : Eu2+ is an excellent x-ray storage phosphor, these NIPs are particularly sensitive to ggr-radiation, which is always present as a background radiation in neutron experiments. In this work we present results on NIPs consisting of KCl : Eu2+ and LiF that were fabricated into ceramic image plates in which the alkali halides act as a self-supporting matrix without the necessity for using a polymeric binder. An advantage of this type of NIP is the significantly reduced ggr-sensitivity. However, the much lower neutron absorption cross section of LiF compared with Gd2O3 demands a thicker image plate for obtaining comparable neutron absorption. The greater thickness of the NIP inevitably leads to a loss in spatial resolution of the image plate. However, this reduction in resolution can be restricted by a novel image plate concept in which a ceramic structure with square cells (referred to as a 'honeycomb') is embedded in the NIP, resulting in a pixelated image plate. In such a NIP the read-out light is confined to the particular illuminated pixel, decoupling the spatial resolution from the optical properties of the image plate material and morphology. In this work, a comparison of experimentally determined and simulated spatial resolutions of pixelated and unstructured image plates for a fixed read-out laser intensity is presented, as well as simulations of the properties of these NIPs at higher laser powers.

  4. POLARIZED NEUTRONS IN RHIC

    Energy Technology Data Exchange (ETDEWEB)

    COURANT,E.D.

    1998-04-27

    There does not appear to be any obvious way to accelerate neutrons, polarized or otherwise, to high energies by themselves. To investigate the behavior of polarized neutrons the authors therefore have to obtain them by accelerating them as components of heavier nuclei, and then sorting out the contribution of the neutrons in the analysis of the reactions produced by the heavy ion beams. The best neutron carriers for this purpose are probably {sup 3}He nuclei and deuterons. A polarized deuteron is primarily a combination of a proton and a neutron with their spins pointing in the same direction; in the {sup 3}He nucleus the spins of the two protons are opposite and the net spin (and magnetic moment) is almost the same as that of a free neutron. Polarized ions other than protons may be accelerated, stored and collided in a ring such as RHIC provided the techniques proposed for polarized proton operation can be adapted (or replaced by other strategies) for these ions. To accelerate polarized particles in a ring, one must make provisions for overcoming the depolarizing resonances that occur at certain energies. These resonances arise when the spin tune (ratio of spin precession frequency to orbit frequency) resonates with a component present in the horizontal field. The horizontal field oscillates with the vertical motion of the particles (due to vertical focusing); its frequency spectrum is dominated by the vertical oscillation frequency and its modulation by the periodic structure of the accelerator ring. In addition, the magnet imperfections that distort the closed orbit vertically contain all integral Fourier harmonics of the orbit frequency.

  5. New compact neutron polarizer

    Science.gov (United States)

    Krist, Th; Kennedy, S. J.; Hicks, T. J.; Mezei, F.

    A new type of a neutron polarizing bender was developed in co-operation with BENSC and ANSTO. It is based upon bent thin silicon wafers coated on one side with SiFeCo polarizing supermirrors and on the other side with Gd. Initial tests at BENSC in a 300 Oe magnetic field yielded a transmission of spin-up neutrons of about 55% over an angle range of 0.75° and flipping ratios > 30. Subsequent tests at ANSTO at 1200 Oe yielded a transmission of 48% with a flipping ratio > 45.

  6. FAST NEUTRONIC REACTOR

    Science.gov (United States)

    Snell, A.H.

    1957-12-01

    This patent relates to a reactor and process for carrying out a controlled fast neutron chain reaction. A cubical reactive mass, weighing at least 920 metric tons, of uranium metal containing predominantly U/sup 238/ and having a U/sup 235/ content of at least 7.63% is assembled and the maximum neutron reproduction ratio is limited to not substantially over 1.01 by insertion and removal of a varying amount of boron, the reactive mass being substantially freed of moderator.

  7. Development of detector technologies for neutron beta decay measurements

    Science.gov (United States)

    Choi, Jin Ha; Cude-Woods, Chris; Young, Albert; Los Alamos UCN Collaboration Collaboration

    2016-09-01

    In the past year we have developed two detector technologies for neutron beta decay measurements. The first is designed specifically to detect the recoil proton from neutron decay. In particular, the PERKEO III experiments planned for the Institut Laue Langevin require detectors with active area greater than about 600 cm2 area to achieve the targeted statistical sensitivity. We have developed an implementation of transmission foil detectors utilizing free standing foils of roughly 100 nm thickness and 700 cm2 area, coated with LiF converting crystal. These foils are placed in an accelerating electric field geometry to first accelerate the protons to 30 kV and then convert them to an electron shower which can be detected with conventional semiconductor or scintillator detectors. We've also begun development of technology that is designed to detect charged particles from neutron-capture reaction on 10B. The UCNtau experiment at the Los Alamos National Laboratories requires non-magnetic neutron sensors that can be used to measure the density of neutrons in a magnetic trap. We are employing a multilayer surface detector recently developed at Los Alamos for the UCN flux monitoring, adapting it for a compact, 1 cm2 detector and ultralow dark rates. The detector consists of 10B on ZnS scintillating sheet that will be adhered to both faces of an acrylic plate with scintillating optical fibers embedded into it. The optical fibers will be coupled to 2, Hamamatsu micro-PMTs for coincident detection of a neutron event.

  8. Helium 3 neutron precision polarimetry

    Science.gov (United States)

    Menard, Christopher

    2009-10-01

    Measuring neutron polarization to a high degree of precision is critical for the next generation of neutron decay correlation experiments. Polarized neutrons are also used in experiments to probe the hadronic weak interaction which contributes a small portion (˜10-7) of the force between nucleons. Using a beam of cold neutrons at Los Alamos Neutron Science Center (LANSCE), we polarized neutrons and measured their absolute polarization to ˜0.1%. Neutrons were polarized by passing them through a ^3He spin filter, relying on the maximally spin dependent 3He neutron absorption cross section. The neutron polarization can be determined by measuring the wavelength-dependent neutron transmission through the ^3He cell. An independent measurement of the neutron polarization was also obtained by passing the polarized beam through an RF spin flipper and a second polarized ^3He cell, used as an analyzer. To measure the efficiency of the spin flipper, the same measurements were made after reversing the ^3He polarization in the polarizer by using NMR techniques (adiabatic fast passage). We will show the consistency of these two measurements and the resulting precision of neutron polarimetry using these techniques.

  9. Regulating nutrient allocation in plants

    Science.gov (United States)

    Udvardi, Michael; Yang, Jiading; Worley, Eric

    2014-12-09

    The invention provides coding and promoter sequences for a VS-1 and AP-2 gene, which affects the developmental process of senescence in plants. Vectors, transgenic plants, seeds, and host cells comprising heterologous VS-1 and AP-2 genes are also provided. Additionally provided are methods of altering nutrient allocation and composition in a plant using the VS-1 and AP-2 genes.

  10. Extracellular nucleotide signaling in plants

    Energy Technology Data Exchange (ETDEWEB)

    Stacey, Gary [Univ. of Missouri, Columbia, MO (United States)

    2016-09-08

    Over the life of this funded project, our research group identified and characterized two key receptor proteins in plants; one mediating the innate immunity response to chitin and the other elucidating the key receptor for extracellular ATP. In the case of chitin recognition, we recently described the quaternary structure of this receptor, shedding light on how the receptor functions. Perhaps more importantly, we demonstrated that all plants have the ability to recognize both chitin oligomers and lipochitooligosacchardes, fundamentally changing how the community views the evolution of these systems and strategies that might be used, for example, to extend symbiotic nitrogen fixation to non-legumes. Our discovery of DORN1 opens a new chapter in plant physiology documenting conclusively that eATP is an important extracellular signal in plants, as it is in animals. At this point, we cannot predict just how far reaching this discovery may prove to be but we are convinced that eATP signaling is fundamental to plant growth and development and, hence, we believe that the future will be very exciting for the study of DORN1 and its overall function in plants.

  11. Regulating nutrient allocation in plants

    Energy Technology Data Exchange (ETDEWEB)

    Udvardi, Michael; Yang, Jiading; Worley, Eric

    2014-12-09

    The invention provides coding and promoter sequences for a VS-1 and AP-2 gene, which affects the developmental process of senescence in plants. Vectors, transgenic plants, seeds, and host cells comprising heterologous VS-1 and AP-2 genes are also provided. Additionally provided are methods of altering nutrient allocation and composition in a plant using the VS-1 and AP-2 genes.

  12. Differential coincidence circuit in the 10{sup -10} second region (1960); Circuit de coincidence differentiel dans le domaine de 10{sup -10} seconde (1960)

    Energy Technology Data Exchange (ETDEWEB)

    Van Zurk, R. [Commissariat a l' Energie Atomique, Lab. de Physique Nucleaire, Grenoble (France).Centre d' Etudes Nucleaires]|[Grenoble-1 Univ., 38 (France)]|[Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1960-07-01

    A coincidence circuit of low resolution time using the differential coincidence Bay principle is described. It uses three 6BN6 tubes ordered to chronotron structure. Results with Radiotechnique 56 AVP photomultipliers and for {sup 60}Co {gamma}-{gamma} coincidences are 4,6.10{sup -10} s (full width at half maximum) if the efficiency is {epsilon} = 40 per cent and also 7,2.10{sup -10} s if {epsilon} = 85 per cent. (author) [French] Un circuit de coincidence differentiel du type de Bay, utilise en selecteur en temps a canal mobile, a ete construit pour la mesure des periodes {gamma} et des periodes d'annihilation du positon dans differents materiaux. Il comporte trois tubes 6BN6 disposes en structure chronotron. On a utilise les nouveaux photomultiplicateurs 56 AVP avec scintillateur plastique. Avec les coincidences {gamma}-{gamma} du {sup 60}Co, on obtient 2T 4,6.10{sup -10} s avec une efficacite de 40 pour cent et 2T = 7,2.10{sup -10} s avec une efficacite de 85 pour cent. (auteur)

  13. Response of diamond detector sandwich to 14 MeV neutrons

    CERN Document Server

    Osipenko, M; Ricco, G; Caiffi, B; Pompili, F; Pillon, M; Verona-Rinati, G; Cardarelli, R

    2015-01-01

    In this paper we present the measurement of the response of 50 $\\mu$m thin diamond detectors to 14 MeV neutrons. Such neutrons are produced in fusion reactors and are of particular interest for ITER neutron diagnostics. Among semiconductor detectors diamond has properties most appropriate for harsh radiation and temperature conditions of a fusion reactor. However, 300-500 $\\mu$m thick diamond detectors suffer significant radiation damage already at neutron fluences of the order of $10^{14}$ n/cm$^2$. It is expected that a 50 $\\mu$m thick diamond will withstand a fluence of $>10^{16}$ n/cm$^2$. We tested two 50 $\\mu$m thick single crystal CVD diamonds, stacked to form a ``sandwich'' detector for coincidence measurements. The detector measured the conversion of 14 MeV neutrons, impinging on one diamond, into $\\alpha$ particles which were detected in the second diamond in coincidence with nuclear recoil. For $^{12}C(n,\\alpha)^{9}Be$ reaction the total energy deposited in the detector gives access to the initial ...

  14. Correlations in prompt neutrons and gamma-rays from Cf-252 spontaneous fission

    Directory of Open Access Journals (Sweden)

    Marcath M.J.

    2017-01-01

    Full Text Available New event-by-event fission models have prompt neutrons and gamma-rays that are correlated in time, energy, and multiplicity, however there is limited measurement data available to validate these models. Measurement of high-order fission neutron and gamma-ray coincidences is difficult and there has previously been little motivation to measure properties of both particle types simultaneously. High-order Cf-252 spontaneous fission neutron and gamma-ray coincidences were measured with a cylindrical array of 22 liquid organic and 8 NaI(Tl scintillation detectors, 50 cm from a central axis. Waveforms were acquired and saved for post-processing using four time-synchronized CAEN V1720 digitizers. Liquid organic scintillator waveforms were analyzed with off-line pulse shape discrimination techniques to categorize neutron and gamma-ray detections. Detected multiplicity was compared with MCNPX-PoliMi simulation results, where built-in fission models and event-by-event fission models, CGMF and FREYA, have been implemented. Additionally, measured neutron energy by time-of-flight and gamma-ray energy correlated by detected multiplicity were compared to simulated results.

  15. Experimental evidence for extreme surface sensitivity in Auger-Photoelectron Coincidence Spectroscopy (APECS) from solids

    Energy Technology Data Exchange (ETDEWEB)

    Liscio, A.; Gotter, R.; Ruocco, A.; Iacobucci, S.; Danese, A.G.; Bartynski, R.A.; Stefani, G

    2004-07-01

    Core hole creation and subsequent Auger decay processes are studied with unprecedented discrimination by Auger-Photoelectron Coincidence Spectroscopy (APECS). Early works in this field have already pointed out the intrinsic surface sensitivity of these experiments. However, it was not until recently that a model calculation was developed to quantitatively evaluate it. Here we present the first attempt to experimentally establish an effective target thickness for such experiments. The angular distribution of 3p{sub 3/2} photoelectron with kinetic energy of 160 eV is measured in coincidence with the M{sub 3}VV Auger electron with kinetic energy of 55 eV on a Cu (1 1 1) surface. Coincidence and non-coincidence photoelectron angular distributions display differences that, to large extent, are explained by confining the source of the coincident signal within the first two layers of Cu target, thus establishing an experimental upper limit for the effective target thickness of the APECS experiment.

  16. Neutron storage time measurement for the neutron EDM experiment

    Science.gov (United States)

    Griffith, W. Clark; Ito, Takeyasu; Ramsey, John; Makela, Mark; Clayton, Steven; Hennings-Yeomans, Raul; Saidur Rahaman, M.; Currie, Scott; Womack, Todd; Sondheim, Walter; Cooper, Martin

    2010-11-01

    A new experiment to search for the neutron electric dipole moment (nEDM) is under development for installation at the Spallation Neutron Source (SNS) at Oakridge National Laboratory. The experiment will use ultra-cold neutrons (UCN) stored in superfluid helium, along with ^3He atoms acting as a neutron spin analyzer and comagnetometer. One crucial factor affecting the ultimate sensitivity of the experiment is the neutron storage time that can be obtained in the acrylic measurement cell. The acrylic cell walls will be coated with deuterated polystyrene (dPS), which is expected to give a wall loss factor of ˜room temperature and below 20 K.

  17. Neutron recognition in LAND detector for large neutron multiplicity

    CERN Document Server

    Pawłowski, P; Leifels, Y; Trautmann, W; Adrich, P; Aumann, T; Bacri, C O; Barczyk, T; Bassini, R; Bianchin, S; Boiano, C; Boretzky, K; Boudard, A; Chbihi, A; Cibor, J; Czech, B; De Napoli, M; Ducret, J -E; Emling, H; Frankland, J D; Gorbinet, T; Hellström, M; Henzlova, D; Hlavac, S; Immè, J; Iori, I; Johansson, H; Kezzar, K; Kupny, S; Lafriakh, A; Fèvre, A Le; Gentil, E Le; Leray, S; Łukasik, J; Lühning, J; Lynch, W G; Lynen, U; Majka, Z; Mocko, M; Müller, W F J; Mykulyak, A; Orth, H; Otte, A N; Palit, R; Panebianco, S; Pullia, A; Raciti, G; Rapisarda, E; Rossi, D; Salsac, M -D; Sann, H; Schwarz, C; Simon, H; Sfienti, C; Sümmerer, K; Tsang, M B; Verde, G; Veselsky, M; Volant, C; Wallace, M; Weick, H; Wiechula, J; Wieloch, A; Zwiegliński, B

    2012-01-01

    The performance of the LAND neutron detector is studied. Using an event-mixing technique based on one-neutron data obtained in the S107 experiment at the GSI laboratory, we test the efficiency of various analytic tools used to determine the multiplicity and kinematic properties of detected neutrons. A new algorithm developed recently for recognizing neutron showers from spectator decays in the ALADIN experiment S254 is described in detail. Its performance is assessed in comparison with other methods. The properties of the observed neutron events are used to estimate the detection efficiency of LAND in this experiment.

  18. Neutron beam imaging at neutron spectrometers at Dhruva

    Science.gov (United States)

    Desai, Shraddha S.; Rao, Mala N.

    2012-06-01

    A low efficiency, 2-Dimensional Position Sensitive Neutron Detector based on delay line position encoding is developed. It is designed to handle beam flux of 106-107 n/cm2/s and for monitoring intensity profiles of neutron beams. The present detector can be mounted in transmission mode, as the hardware allows maximum neutron transmission in sensitive region. Position resolution of 1.2 mm in X and Y directions, is obtained. Online monitoring of beam images and intensity profile of various neutron scattering spectrometers at Dhruva are presented. It shows better dynamic range of intensity over commercial neutron camera and is also time effective over the traditionally used photographic method.

  19. Some Implications of Neutron Mirror Neutron Oscillation

    CERN Document Server

    Mohapatra, Rabindra N; Nussinov, S

    2005-01-01

    We comment on a recently discussed possibility of oscillations between neutrons and degenerate mirror neutrons in the context of mirror models for particles and forces. It has been noted by Bento and Berezhiani that if these oscillations occurred at a rate of $\\tau^{-1}_{NN'}\\sim sec^{-1}$, it would help explain putative super GKZ cosmic ray events provided the temperature of the mirror radiation is $\\sim 0.3-0.4$ times that of familiar cosmic microwave background radiation. We discuss how such oscillation time scales can be realized in mirror models and find that the simplest nonsupersymmetric model for this idea requires the existence of a low mass (30-3000 GeV) color triplet scalar or vector boson. A supersymmetric model, where this constraint can be avoided is severely constrained by the requirement of maintaining a cooler mirror sector. We also find that the reheat temperature after inflation in generic models that give fast $n-n'$ oscillation be less than about 100 GeV in order to maintain the required ...

  20. Selective population and neutron decay of the first excited state of semi-magic O-23

    CERN Document Server

    Schiller, A; Bazin, D; Brown, B A; Brown, J; DeYoung, P A; Finck, J E; Frank, N; Gade, A; Hinnefeld, J; Howes, R; Lecouey, J L; Luther, B; Peters, W A; Scheit, H; Thoennessen, M; Tostevin, J A

    2006-01-01

    We have observed an excited state in the neutron-rich semi-magic nucleus O-23 for the first time. No such states have been found in previous searches using gamma-ray spectroscopy. The observation of a resonance in n-fragment coincidence measurements confirms the speculation in the literature that the lowest excited state is neutron unbound and establishes positive evidence for a 2.8(1) MeV excitation energy of the first excited state in O-23. The non-observation of a predicted second excited state is explained assuming selectivity of inner-shell knockout reactions.

  1. Measurements of prompt fission gamma-rays and neutrons with lanthanide halide scintillation detectors

    CERN Document Server

    Oberstedt, A; Billnert, R; Borcea, R; Brys, T; Chaves, C; Gamboni, T; Geerts, W; Göök, A; Guerrero, C; Hambsch, F-J; Kis, Z; Martinez, T; Oberstedt, S; Szentmiklosi, L; Takács, K; Vivaldi, M

    2014-01-01

    Photons have been measured with lanthanide halide scintillation detectors in coincidence with fission fragments. Using the time-of-flight information, reactions from γ-rays and neutrons could easily be distinguished. In several experiments on $^{252}$Cf(sf), $^{235}$U(n$_{th}$,f) and $^{241}$Pu(n$_{th}$,f) prompt fission γ-ray spectra characteristics were determined with high precision and the results are presented here. Moreover, a measured prompt fission neutron spectrum for $^{235}$U(n$_{th}$,f) is shown in order to demonstrate a new detection technique.

  2. Neutron Scattering Investigations of Correlated Electron Systems and Neutron Instrumentation

    DEFF Research Database (Denmark)

    Holm, Sonja Lindahl

    are a unique probe for studying the atomic and molecular structure and dynamics of materials. Even though neutrons are very expensive to produce, the advantages neutrons provide overshadow the price. As neutrons interact weakly with materials compared to many other probes, e.g. electrons or photons......, it is possible to make a neutron scattering experiment through sample environment equipment like cryostats or pressure cells. Another advantage of neutron experiments is that the wavelength and energy of the neutron match the inter-atomic distances and basic excitations of solid materials. The scattering cross...... is not taken into account in previous reports on the field effect of magnetic scattering, since usually only L 0 is probed. A paper draft submitted for publication describing the results of elastic and inelastic neutron scattering experiments performed on the oxygen-doped La2CuO4+y HTSC is appended (Tc 40 K...

  3. Neutronic studies of the coupled moderators for spallation neutron sources

    Institute of Scientific and Technical Information of China (English)

    Yin Wen; Liang Jiu-Qing

    2005-01-01

    We investigate the neutronic performance of coupled moderators to be implemented in spallation neutron sources by Monte-Carlo simulation and give the slow neutron spectra for the cold and thermal moderators. CH4 moderator can provide slow neutrons with highly desirable characteristics and will be used in low-power spallation neutron soureces. The slow neutron intensity extracted from different angles has been calculated. The capability of moderation of liquid H2 is lower than H2O and liquid CH4 due to lower atomic number density of hydrogen but we can compensate for this disadvantage by using a premoderator. The H2O premoderator of 2cm thickness can reduce the heat deposition in the cold moderator by about 33% without spoiling the neutron pulse.

  4. Discrimination of the wall effect in a thin counter with micro-gap structure for neutron position sensing

    Energy Technology Data Exchange (ETDEWEB)

    Sakae, Takeji; Manabe, Tohru; Kitamura, Yasunori; Nohtomi, Akihiro [Kyushu Univ., Fukuoka (Japan); Sakamoto, Sigeyasu

    1996-07-01

    Simulation by the Monte Carlo method is applied to estimate the wall effect in a thermal neutron counter having a new function for discriminating the effect. The counter is designed to have paralleled electrodes with micro-gap structure. A resistive anode is used for position sensing on the center of a set of the three electrode. The structure can be made by simple arrangement of anode and cathode wires on an insulator plane. The calculation shows discrimination of the wall effect can be achieved by coincident counting of two or three elements included in the counter. By using the coincident counting, the thickness of the neutron counter can be made into 1 mm with the information of the total energy created in the neutron detection. (author)

  5. Measurements of neutrons produced by high-energy muons at the Boulby Underground Laboratory

    CERN Document Server

    Araújo, H M; Bungau, C; Carson, M J; Chagani, H; Daw, E; Edwards, B; Ghag, C; Korolkova, E V; Kudryavtsev, V A; Lightfoot, P K; Lindote, A; Liubarsky, I; Lüscher, R; Majewski, P; Mavrokoridis, K; McMillan, J E; Murphy, A St J; Paling, S M; da Cunha, J Pinto; Preece, R M; Robinson, M; Smith, N J T; Smith, P F; Spooner, N J C; Sumner, T J; Walker, R J; Wang, H; White, J

    2008-01-01

    We present the first measurements of the muon-induced neutron flux at the Boulby Underground Laboratory. The experiment was carried out with an 0.73 tonne liquid scintillator that also served as an anticoincidence system for the ZEPLIN-II direct dark matter search. The experimental method exploited the delayed coincidences between high-energy muon signals and gamma-rays from radiative neutron capture on hydrogen or other elements. The muon-induced neutron rate, defined as the average number of detected neutrons per detected muon, was measured as $0.079 \\pm 0.003$ (stat.) neutrons/muon using neutron-capture signals above 0.55 MeV in a time window of 40-190 $\\mu$s after the muon trigger. Accurate Monte Carlo simulations of the neutron production, transport and detection in a precisely modeled laboratory and experimental setup using the GEANT4 toolkit gave a result 1.8 times higher than the measured value. The difference greatly exceeds all statistical and systematic uncertainties. As the vast majority of neutro...

  6. Efficiency Studies and Simulations of a Neutron Background Veto for Dark Matter Detectors

    Science.gov (United States)

    Westerdale, Shawn; Shields, Emily; Xu, Jingke; Calaprice, Frank

    2013-04-01

    In direct WIMP dark matter detection experiments, neutrons from cosmogenic sources and nuclear reactions in detector materials can provide backgrounds indistinguishable from WIMP signals. To reduce this background, an active neutron veto filled with a boron-loaded scintillator is being developed. The scintillator used will be pseudocumene, mixed with trimethyl borate as a boron source, and a PPO wavelength shifter. Such a veto would detect neutrons in the volume surrounding the detector, allowing coincident background events in the detector to be rejected. Neutrons are captured by the ^10B with a high cross section, resulting in an α and ^7Li. The scintillation from the nuclear products is heavily quenched to an equivalent electron energy as low as 50 keV. To detect this, it is necessary to have high light collection efficiency. To model the neutron veto concept, light yield measurements were taken for a small prototype filled with the scintillator mixture and lined with a Lumirror reflector. These results were reproduced in GEANT4 and in an independent simulation. We then applied the simulations to the DarkSide-50 neutron veto to predict its neutron rejection power. Results from measurements taken with the prototype and from the simulation will be presented.

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

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, J. M.

    1999-01-06

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

  8. Study of [beta][sup +] and electron capture decay of [sup 76]Sr in [gamma]-[gamma] coincidence measurements

    Energy Technology Data Exchange (ETDEWEB)

    Adzic, P.R.; Zupancic, M.T.; Vukanovic, R.B.; Anicin, I.V.; Skoro, G.P.; Kukoc, A.H. (Institute of Nuclear Sciences Vinca' ' , POB 522, 11001 Belgrade (Yugoslavia)); Lindroos, M.; Tengblad, O.; Veskovic, M.; ISOLDE Collaboration (CERN, PPE Division, CH-1211 Geneva 23 (Switzerland))

    1993-12-01

    The main goal of this work is to establish the nuclear decay scheme of [sup 76]Sr and energy levels of its doubly odd daughter nucleus [sup 76]Rb. The extremely neutron deficient nucleus [sup 76]Sr lying at the [ital N]=[ital Z] (=38) line with half-life of 8.9 s was produced in spallation reactions of 600 MeV protons from the CERN Synchrocyclotron (SC) with a Nb multifoil target in conjunction with a W surface ionization source at the ISOLDE facility. The [gamma]-spectroscopy measurements have been performed with two Ge detectors which were positioned at about [plus minus]30[degree] respectively downstream to the [sup 76]Sr beam. The obtained singles and coincidence [gamma] spectra were used to determine energies and intensities of [gamma] lines assigned to the decay of [sup 76]Sr and to establish some details of the nuclear level configuration of its daughter nucleus [sup 76]Rb up to 1000 keV.

  9. A physics investigation of deadtime losses in neutron counting at low rates with Cf252

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Louise G [Los Alamos National Laboratory; Croft, Stephen [CANBERRA INDUSTRIES, INC.

    2009-01-01

    {sup 252}Cf spontaneous fission sources are used for the characterization of neutron counters and the determination of calibration parameters; including both neutron coincidence counting (NCC) and neutron multiplicity deadtime (DT) parameters. Even at low event rates, temporally-correlated neutron counting using {sup 252}Cf suffers a deadtime effect. Meaning that in contrast to counting a random neutron source (e.g. AmLi to a close approximation), DT losses do not vanish in the low rate limit. This is because neutrons are emitted from spontaneous fission events in time-correlated 'bursts', and are detected over a short period commensurate with their lifetime in the detector (characterized by the system die-away time, {tau}). Thus, even when detected neutron events from different spontaneous fissions are unlikely to overlap in time, neutron events within the detected 'burst' are subject to intrinsic DT losses. Intrinsic DT losses for dilute Pu will be lower since the multiplicity distribution is softer, but real items also experience self-multiplication which can increase the 'size' of the bursts. Traditional NCC DT correction methods do not include the intrinsic (within burst) losses. We have proposed new forms of the traditional NCC Singles and Doubles DT correction factors. In this work, we apply Monte Carlo neutron pulse train analysis to investigate the functional form of the deadtime correction factors for an updating deadtime. Modeling is based on a high efficiency {sup 3}He neutron counter with short die-away time, representing an ideal {sup 3}He based detection system. The physics of dead time losses at low rates is explored and presented. It is observed that new forms are applicable and offer more accurate correction than the traditional forms.

  10. A review on neutron reflectometry

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Soo; Lee, Chang Hee; Shim, Hae Seop; Seong, Baek Seok

    1999-03-01

    This report contains principle and characteristic of neutron reflectometry. Therefore, in case of operating neutron reflectometer at HANARO in future, it will be a reference to the user who wishes to use the instrument effectively. Also, the current situation of neutron reflectometer operating in the world was examined. The detail of neutron reflectometer such as GANS(MURR), ADAM(ILL), POSY II(ANL), ROG(IRI) was described. The recent research situation on neutron reflectometry was also examined and it helps us to determine research field. (author)

  11. Neutron proton crystallography station (PCS)

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, Zoe [Los Alamos National Laboratory; Kovalevsky, Andrey [Los Alamos National Laboratory; Johnson, Hannah [Los Alamos National Laboratory; Mustyakimov, Marat [Los Alamos National Laboratory

    2009-01-01

    The PCS (Protein Crystallography Station) at Los Alamos Neutron Science Center (LANSCE) is a unique facility in the USA that is designed and optimized for detecting and collecting neutron diffraction data from macromolecular crystals. PCS utilizes the 20 Hz spallation neutron source at LANSCE to enable time-of-flight measurements using 0.6-7.0 {angstrom} neutrons. This increases the neutron flux on the sample by using a wavelength range that is optimal for studying macromolecular crystal structures. The diagram below show a schematic of PCS and photos of the detector and instrument cave.

  12. Neutron detection efficiency determinations for the TUNL neutron-neutron and neutron-proton scattering-length measurements

    Energy Technology Data Exchange (ETDEWEB)

    Trotter, D.E. Gonzalez [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)], E-mail: crowell@tunl.duke.edu; Meneses, F. Salinas [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Tornow, W. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)], E-mail: tornow@tunl.duke.edu; Crowell, A.S.; Howell, C.R. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Schmidt, D. [Physikalisch-Technische Bundesanstalt, D-38116, Braunschweig (Germany); Walter, R.L. [Department of Physics, Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)

    2009-02-11

    The methods employed and the results obtained from measurements and calculations of the detection efficiency for the neutron detectors used at Triangle Universities Nuclear Laboratory (TUNL) in the simultaneous determination of the {sup 1}S{sub 0} neutron-neutron and neutron-proton scattering lengths a{sub nn} and a{sub np}, respectively, are described. Typical values for the detector efficiency were 0.3. Very good agreement between the different experimental methods and between data and calculation has been obtained in the neutron energy range below E{sub n}=13MeV.

  13. Cooling of Neutron Stars

    Directory of Open Access Journals (Sweden)

    Grigorian H.

    2010-10-01

    Full Text Available We introduce the theoretical basis for modeling the cooling evolution of compact stars starting from Boltzmann equations in curved space-time. We open a discussion on observational verification of different neutron star models by consistent statistics. Particular interest has the question of existence of quark matter deep inside of compact object, which has to have a specific influence on the cooling history of the star. Besides of consideration of several constraints and features of cooling evolution, which are susceptible of being critical for internal structure of hot compact stars we have introduced a method of extraction of the mass distribution of the neutron stars from temperature and age data. The resulting mass distribution has been compared with the one suggested by supernove simulations. This method can be considered as an additional checking tool for the consistency of theoretical modeling of neutron stars. We conclude that the cooling data allowed existence of neutron stars with quark cores even with one-flavor quark matter.

  14. New Neutron Dosimeter

    CERN Multimedia

    2001-01-01

    CERN has been operating an Individual Dosimetry Service for neutrons for about 35 years. The service was based on nuclear emulsions in the form of film packages which were developed and scanned in the Service. In 1999, the supplier of theses packages informed CERN that they will discontinue production of this material. TIS-RP decided to look for an external service provider for individual neutron dosimetry. After an extensive market survey and an invitation for tender, a supplier that met the stringent technical requirements set up by CERN's host states for personal dosimeters was identified. The new dosimeter is based on a track-etching technique. Neutrons have the capability of damaging plastic material. The microscopic damage centres are revealed by etching them in a strong acid. The resulting etch pits can be automatically counted and their density is proportional to dose equivalent from neutrons. On the technical side, the new dosimeter provides an improved independence of its response from energy and th...

  15. Neutron protein crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Niimura, Nobuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-10-01

    X-ray diffraction of single crystal has enriched the knowledge of various biological molecules such as proteins, DNA, t-RNA, viruses, etc. It is difficult to make structural analysis of hydrogen atoms in a protein using X-ray crystallography, whereas neutron diffraction seems usable to directly determine the location of those hydrogen atoms. Here, neutron diffraction method was applied to structural analysis of hen egg-white lysozyme. Since the crystal size of a protein to analyze is generally small (5 mm{sup 3} at most), the neutron beam at the sample position in monochromator system was set to less than 5 x 5 mm{sup 2} and beam divergence to 0.4 degree or less. Neutron imaging plate with {sup 6}Li or Gd mixed with photostimulated luminescence material was used and about 2500 Bragg reflections were recorded in one crystal setting. A total of 38278 reflections for 2.0 A resolution were collected in less than 10 days. Thus, stereo views of Trp-111 omit map around the indol ring of Trp-111 was presented and the three-dimensional arrangement of 696H and 264D atoms in the lysozyme molecules was determined using the omit map. (M.N.)

  16. Neutron capture reactions at DANCE

    Science.gov (United States)

    Bredeweg, T. A.

    2008-05-01

    The Detector for Advanced Neutron Capture Experiments (DANCE) is a 4π BaF2 array consisting of 160 active detector elements. The primary purpose of the array is to perform neutron capture cross section measurements on small (>~100 μg) and/or radioactive (DANCE we have performed neutron capture cross section measurements on a wide array of medium to heavy mass nuclides. Measurements to date include neutron capture cross sections on 241,243Am, neutron capture and neutron-induced fission cross sections and capture-to-fission ratio (α = σγ/σf) for 235U using a new fission-tagging detector as well as neutron capture cross sections for several astrophysics branch-point nuclei. Results from several of these measurements will be presented along with a discussion of additional physics information that can be extracted from the DANCE data.

  17. Nanostructure Neutron Converter Layer Development

    Science.gov (United States)

    Park, Cheol (Inventor); Sauti, Godfrey (Inventor); Kang, Jin Ho (Inventor); Lowther, Sharon E. (Inventor); Thibeault, Sheila A. (Inventor); Bryant, Robert G. (Inventor)

    2016-01-01

    Methods for making a neutron converter layer are provided. The various embodiment methods enable the formation of a single layer neutron converter material. The single layer neutron converter material formed according to the various embodiments may have a high neutron absorption cross section, tailored resistivity providing a good electric field penetration with submicron particles, and a high secondary electron emission coefficient. In an embodiment method a neutron converter layer may be formed by sequential supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In another embodiment method a neutron converter layer may be formed by simultaneous supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In a further embodiment method a neutron converter layer may be formed by in-situ metalized aerogel nanostructure development.

  18. Tight bounds for the Pearle-Braunstein-Caves chained inequality without the fair-coincidence assumption

    Science.gov (United States)

    Jogenfors, Jonathan; Larsson, Jan-Åke

    2017-08-01

    In any Bell test, loopholes can cause issues in the interpretation of the results, since an apparent violation of the inequality may not correspond to a violation of local realism. An important example is the coincidence-time loophole that arises when detector settings might influence the time when detection will occur. This effect can be observed in many experiments where measurement outcomes are to be compared between remote stations because the interpretation of an ostensible Bell violation strongly depends on the method used to decide coincidence. The coincidence-time loophole has previously been studied for the Clauser-Horne-Shimony-Holt and Clauser-Horne inequalities, but recent experiments have shown the need for a generalization. Here, we study the generalized "chained" inequality by Pearle, Braunstein, and Caves (PBC) with N ≥2 settings per observer. This inequality has applications in, for instance, quantum key distribution where it has been used to reestablish security. In this paper we give the minimum coincidence probability for the PBC inequality for all N ≥2 and show that this bound is tight for a violation free of the fair-coincidence assumption. Thus, if an experiment has a coincidence probability exceeding the critical value derived here, the coincidence-time loophole is eliminated.

  19. Search for gravitational waves from galactic and extra--galactic binary neutron stars

    CERN Document Server

    Abbott, B; Adhikari, R; Ageev, A; Allen, B; Amin, R; Anderson, S B; Anderson, W G; Araya, M; Armandula, H; Ashley, M; Asiri, F; Aufmuth, P; Aulbert, C; Babak, S; Balasubramanian, R; Ballmer, S; Barish, B C; Barker, C; Barker, D; Barnes, M; Barr, B; Barton, M A; Bayer, K; Beausoleil, R; Belczynski, K; Bennett, R; Berukoff, S J; Betzwieser, J; Bhawal, B; Bilenko, I A; Billingsley, G; Black, E; Blackburn, K; Blackburn, L; Bland, B; Bochner, B; Bogue, L; Bork, R; Bose, S; Brady, P R; Braginsky, V B; Brau, J E; Brown, D A; Bullington, A; Bunkowski, A; Buonanno, A; Burgess, R; Busby, D; Butler, W E; Byer, R L; Cadonati, L; Cagnoli, G; Camp, J B; Cantley, C A; Cardenas, L; Carter, K; Casey, M M; Castiglione, J; Chandler, A; Chapsky, J; Charlton, P; Chatterji, S; Chelkowski, S; Chen, Y; Chickarmane, V; Chin, D; Christensen, N; Churches, D; Cokelaer, T; Colacino, C; Coldwell, R; Coles, M; Cook, D; Corbitt, T; Coyne, D; Creighton, J D E; Creighton, T D; Crooks, D R M; Csatorday, P; Cusack, B J; Cutler, C; D'Ambrosio, E; Danzmann, K; Daw, E; De Bra, D; DeSalvo, R; Delker, T; Dergachev, V; Dhurandhar, S V; Di Credico, A; Ding, H; Drever, R W P; Dupuis, R J; Edlund, J A; Ehrens, P; Elliffe, E J; Etzel, T; Evans, M; Evans, T; Fairhurst, S; Fallnich, C; Farnham, D; Fejer, M M; Findley, T; Fine, M; Finn, L S; Franzen, K Y; Freise, A; Frey, R; Fritschel, P; Frolov, V V; Fyffe, M; Ganezer, K S; Garofoli, J; Giaime, J A; Gillespie, A; Goda, K; Goler, S; González, G; Grandclément, P; Grant, A; Gray, C; Gretarsson, A M; Grimmett, D; Grote, H; Grünewald, S; Gustafson, E; Gustafson, R; Günther, M; Hamilton, W O; Hammond, M; Hanson, J; Hardham, C; Harms, J; Harry, G; Hartunian, A; Heefner, J; Hefetz, Y; Heinzel, G; Heng, I S; Hennessy, M; Hepler, N; Heptonstall, A; Heurs, M; Hewitson, M; Hild, S; Hindman, N; Hoang, P; Hough, J; Hrynevych, M; Hua, W; Ito, M; Itoh, Y; Ivanov, A; Jennrich, O; Johnson, B; Johnson, W W; Johnston, W R; Jones, D I; Jones, L; Jungwirth, D; Kalogera, V; Katsavounidis, E; Kawabe, K; Kawamura, S; Kells, W; Kern, J; Khan, A; Killbourn, S; Killow, C J; Kim, C; King, C; King, P; Klimenko, S; Koranda, S; Kotter, K; Kovalik, Yu; Kozak, D; Krishnan, B; Landry, M; Langdale, J; Lantz, B; Lawrence, R; Lazzarini, A; Lei, M; Leonor, I; Libbrecht, K; Libson, A; Lindquist, P; Liu, S; Logan, J; Lormand, M; Lubinski, M; Luck, H; Lyons, T T; MacInnis, M; Machenschalk, B; Mageswaran, M; Mailand, K; Majid, W; Malec, M; Mann, F; Marin, A; Marka, S; Maros, E; Mason, J; Mason, K; Matherny, O; Matone, L; Mavalvala, N; McCarthy, R; McClelland, D E; McHugh, M; McNabb, J W C; Mendell, G; Mercer, R A; Meshkov, S; Messaritaki, E; Messenger, C; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Miyakawa, O; Miyoki, S; Mohanty, S; Moreno, G; Mossavi, K; Mukherjee, S; Murray, P; Myers, J; Müller, G; Nagano, S; Nash, T; Nayak, R; Newton, G; Nocera, F; Noel, J S; Nutzman, P; O'Reilly, B; Olson, T; Ottaway, D J; Ottewill, A; Ouimette, D A; Overmier, H; Owen, B J; Pan, Y; Papa, M A; Parameshwaraiah, V; Parameswariah, C; Pedraza, M; Penn, S; Pitkin, M; Plissi, M; Prix, R; Quetschke, V; Raab, F; Radkins, H; Rahkola, R; Rakhmanov, M; Rao, S R; Rawlins, K; Ray-Majumder, S; Re, V; Redding, D; Regehr, M W; Regimbau, T; Reid, S; Reilly, K T; Reithmaier, K; Reitze, D H; Richman, S; Riesen, R; Riles, K; Rivera, B; Rizzi, A; Robertson, D I; Robertson, N A; Robison, L; Roddy, S; Rollins, J; Romano, J D; Romie, J; Rong, H; Rose, D; Rotthoff, E; Rowan, S; Russell, P; Ryan, K; Rüdiger, A; Salzman, I; Sandberg, V; Sanders, G H; Sannibale, V; Sathyaprakash, B; Saulson, P R; Savage, R; Sazonov, A; Schilling, R; Schlaufman, K; Schmidt, V; Schnabel, R; Schofield, R; Schutz, B F; Schwinberg, P; Scott, S M; Seader, S E; Searle, A C; Sears, B; Seel, S; Seifert, F; Sengupta, A S; Shapiro, C A; Shawhan, P; Shoemaker, D H; Shu, Q Z; Sibley, A; Siemens, X; Sievers, L; Sigg, D; Sintes, A M; Smith, J R; Smith, M; Smith, M R; Sneddon, P H; Spero, R; Stapfer, G; Steussy, D; Strain, K A; Strom, D; Stuver, A; Summerscales, T; Sumner, M C; Sutton, P J; Sylvestre, J; Takamori, A; Tanner, D B; Tariq, H; Taylor, I; Taylor, R; Thorne, K A; Thorne, K S; Tibbits, M; Tilav, S; Tinto, M; Tokmakov, K V; Torres, C; Torrie, C; Traylor, G; Tyler, W; Ugolini, D W; Ungarelli, C; Vallisneri, M; Van Putten, M H P M; Vass, S; Vecchio, A; Veitch, J; Vorvick, C; Vyachanin, S P; Wallace, L; Walther, H; Ward, H; Ware, B; Watts, K; Webber, D; Weidner, A; Weiland, U; Weinstein, A; Weiss, R; Welling, H; Wen, L; Wen, S; Whelan, J T; Whitcomb, S E; Whiting, B F; Wiley, S; Wilkinson, C; Willems, P A; Williams, P R; Williams, R; Willke, B; Wilson, A; Winjum, B J; Winkler, W; Wise, S; Wiseman, A G; Woan, G; Wooley, R; Worden, J; Wu, W; Yakushin, I; Yamamoto, H; Yoshida, S; Zaleski, K D; Zanolin, M; Zawischa, I; Zhang, L; Zhu, R; Zotov, N P; Zucker, M; Zweizig, J

    2005-01-01

    We use 373 hours ($\\approx$ 15 days) of data from the second science run of the LIGO gravitational-wave detectors to search for signals from binary neutron star coalescences within a maximum distance of about 1.5 Mpc, a volume of space which includes the Andromeda Galaxy and other galaxies of the Local Group of galaxies. This analysis requires a signal to be found in data from detectors at the two LIGO sites, according to a set of coincidence criteria. The background (accidental coincidence rate) is determined from the data and is used to judge the significance of event candidates. No inspiral gravitational wave events were identified in our search. Using a population model which includes the Local Group, we establish an upper limit of less than 47 inspiral events per year per Milky Way equivalent galaxy with 90% confidence for non-spinning binary neutron star systems with component masses between 1 and 3 $M_\\odot$.

  20. Joint LIGO and TAMA300 Search for Gravitational Waves from Inspiralling Neutron Star Binaries

    CERN Document Server

    Abbott, B; Adhikari, R; Ageev, A; Agresti, J; Ajith, P; Akutsu, T; Allen, B; Allen, J; Amin, R; Anderson, S B; Anderson, W G; Ando, M; Arai, K; Araya, A; Araya, M; Armandula, H; Asada, H; Ashley, M; Asiri, F; Aso, Y; Aufmuth, P; Aulbert, C; Babak, S; Balasubramanian, R; Ballmer, S; Barish, B C; Barker, C; Barker, D; Barnes, M; Barr, B; Barton, M A; Bayer, K; Beausoleil, R; Belczynski, K; Bennett, R; Berukoff, S J; Betzwieser, J; Beyersdorf, P; Bhawal, B; Bilenko, I A; Billingsley, G; Black, E; Blackburn, K; Blackburn, L; Bland, B; Bochner, B; Bogue, L; Bork, R; Bose, S; Brady, P R; Braginsky, V B; Brau, J E; Brown, D A; Bullington, A; Bunkowski, A; Buonanno, A; Burgess, R; Busby, D; Butler, W E; Byer, R L; Cadonati, L; Cagnoli, G; Camp, J B; Cannizzo, J; Cannon, K; Cantley, C A; Cao, J; Cardenas, L; Carter, K; Casey, M M; Castiglione, J; Chandler, A; Chapsky, J; Charlton, P; Chatterji, S; Chelkowski, S; Chen, Y; Chickarmane, V; Chin, D; Christensen, N; Churches, D; Cokelaer, T; Colacino, C; Coldwell, R; Coles, M; Cook, D; Corbitt, T; Coyne, D; Creighton, J D E; Creighton, T D; Crooks, D R M; Csatorday, P; Cusack, B J; Cutler, C; D'Ambrosio, E; Dalrymple, J; Danzmann, K; Davies, G; Daw, E; De Bra, D; DeSalvo, R; Delker, T; Dergachev, V; Desai, S; Dhurandhar, S V; Di Credico, A; Ding, H; Drever, R W P; Dupuis, R J; Díaz, M; Edlund, J A; Ehrens, P; Elliffe, E J; Etzel, T; Evans, M; Evans, T; Fairhurst, S; Fallnich, C; Farnham, D; Fejer, M M; Findley, T; Fine, M; Finn, L S; Franzen, K Y; Freise, A; Frey, R; Fritschel, P; Frolov, V V; Fujiki, Y; Fujimoto, M K; Fujita, R; Fukushima, M; Futamase, T; Fyffe, M; Ganezer, K S; Garofoli, J; Giaime, J A; Gillespie, A; Goda, K; Goggin, L; Goler, S; González, G; Grandclément, P; Grant, A; Gray, C; Gretarsson, A M; Grimmett, D; Grote, H; Grünewald, S; Gustafson, E; Gustafson, R; Günther, M; Hamilton, W O; Hammond, M; Hamuro, Y; Hanna, C; Hanson, J; Hardham, C; Harms, J; Harry, G; Hartunian, A; Haruyama, T; Hayama, K; Heefner, J; Hefetz, Y; Heinzel, G; Heng, I S; Hennessy, M; Hepler, N; Heptonstall, A; Heurs, M; Hewitson, M; Hild, S; Hindman, N; Hoang, P; Hough, J; Hrynevych, M; Hua, W; Iguchi, H; Iida, Y; Ioka, K; Ishitsuka, H; Ito, M; Itoh, Y; Ivanov, A; Jennrich, O; Johnson, B; Johnson, W W; Johnston, W R; Jones, D I; Jones, G; Jones, L; Jungwirth, D; Kalogera, V; Kamikubota, N; Kanda, N; Kaneyama, T; Karasawa, Y; Kasahara, K; Kasai, T; Katsavounidis, E; Katsuki, M; Kawabe, K; Kawamura, M; Kawamura, S; Kawazoe, F; Kells, W; Kern, J; Khan, A; Killbourn, S; Killow, C J; Kim, C; King, C; King, P; Klimenko, S; Kojima, Y; Kokeyama, K; Kondo, K; Koranda, S; Kotter, K; Kovalik, Yu; Kozai, Y; Kozak, D; Krishnan, B; Kudoh, H; Kuroda, K; Kuwabara, T; Landry, M; Langdale, J; Lantz, B; Lawrence, R; Lazzarini, A; Lei, M; Leonor, I; Libbrecht, K; Libson, A; Lindquist, P; Liu, S; Logan, J; Lormand, M; Lubinski, M; Luck, H; Luna, M; Lyons, T T; MacInnis, M; Machenschalk, B; Mageswaran, M; Mailand, K; Majid, W; Malec, M; Mandic, V; Mann, F; Marin, A; Marka, S; Maros, E; Mason, J; Mason, K; Matherny, O; Matone, L; Matsuda, N; Mavalvala, N; McCarthy, R; McClelland, D E; McHugh, M; McNabb, J W C; Melissinos, A C; Mendell, G; Mercer, R A; Meshkov, S; Messaritaki, E; Messenger, C; Mikhailov, E; Mio, N; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Miura, K; Miyakawa, O; Miyama, S; Miyoki, S; Mizusawa, H; Mohanty, S; Moreno, G; Moriwaki, S; Mossavi, K; Mukherjee, S; Murray, P; Musha, M; Myers, E; Myers, J; Müller, G; Nagano, S; Nagayama, Y; Nakagawa, K; Nakamura, T; Nakano, H; Nakao, K; Nash, T; Nayak, R; Newton, G; Nishi, Y; Nocera, F; Noel, J S; Numata, K; Nutzman, P; O'Reilly, B; Ogawa, Y; Ohashi, M; Ohishi, N; Okutomi, A; Olson, T; Oohara, K; Otsuka, S; Ottaway, D J; Ottewill, A; Ouimette, D A; Overmier, H; Owen, B J; Pan, Y; Papa, M A; Parameshwaraiah, V; Parameswariah, C; Pedraza, M; Penn, S; Pitkin, M; Plissi, M; Prix, R; Quetschke, V; Raab, F; Radkins, H; Rahkola, R; Rakhmanov, M; Rao, S R; Rawlins, K; Ray-Majumder, S; Re, V; Redding, D; Regehr, M W; Regimbau, T; Reid, S; Reilly, K T; Reithmaier, K; Reitze, D H; Richman, S; Riesen, R; Riles, K; Rivera, B; Rizzi, A; Robertson, D I; Robertson, N A; Robinson, C; Robison, L; Roddy, S; Rodríguez, A; Rollins, J; Romano, J D; Romie, J; Rong, H; Rose, D; Rotthoff, E; Rowan, S; Ruet, L; Russell, P; Ryan, K; Rüdiger, A; Saitô, Y; Sakata, S; Salzman, I; Sandberg, V; Sanders, G H; Sannibale, V; Sarin, P; Sasaki, M; Sathyaprakash, B; Sato, K; Sato, N; Sato, S; Sato, Y; Saulson, P R; Savage, R; Sazonov, A; Schilling, R; Schlaufman, K; Schmidt, V; Schnabel, R; Schofield, R; Schutz, B F; Schwinberg, P; Scott, S M; Seader, S E; Searle, A C; Sears, B; Seel, S; Seifert, F; Sekido, A; Sellers, D; Sengupta, A S; Seto, N; Shapiro, C A; Shawhan, P; Shibata, M; Shinkai, H; Shintomi, T; Shoemaker, D H; Shu, Q Z; Sibley, A; Siemens, X; Sievers, L; Sigg, D; Sintes, A M; Smith, J R; Smith, M; Smith, M R; Sneddon, P H; Soida, K; Somiya, K; Spero, R; Spjeld, O; Stapfer, G; Steussy, D; Strain, K A; Strom, D; Stuver, A; Summerscales, T; Sumner, M C; Sung, M; Sutton, P J; Suzuki, T; Sylvestre, J; Tagoshi, H; Takahashi, H; Takahashi, R; Takamori, A; Takemoto, S; Takeno, K; Tanaka, T; Taniguchi, K; Tanji, T; Tanner, D B; Tarallo, M; Tariq, H; Tatsumi, D; Taylor, I; Taylor, R; Telada, S; Thorne, K A; Thorne, K S; Tibbits, M; Tilav, S; Tinto, M; Tokmakov, K V; Tokunari, M; Tomaru, T; Torres, C; Torrie, C; Traylor, G; Tsubono, K; Tsuda, N; Tsunesada, Y; Tyler, W; Uchiyama, T; Ueda, A; Ueda, K; Ugolini, D W; Ungarelli, C; Vallisneri, M; Van Putten, M H P M; Vass, S; Vecchio, A; Veitch, J; Vorvick, C; Vyachanin, S P; Wallace, L; Walther, H; Ward, H; Ward, R; Ware, B; Waseda, K; Watts, K; Webber, D; Weidner, A; Weiland, U; Weinstein, A; Weiss, R; Welling, H; Wen, L; Wen, S; Wette, K; Whelan, J T; Whitcomb, S E; Whiting, B F; Wiley, S; Wilkinson, C; Willems, P A; Williams, P R; Williams, R; Willke, B; Wilson, A; Winjum, B J; Winkler, W; Wise, S; Wiseman, A G; Woan, G; Woods, D; Wooley, R; Worden, J; Wu, W; Yakushin, I; Yamamoto, A; Yamamoto, H; Yamamoto, K; Yamazaki, T; Yanagi, Y; Yokoyama, J; Yoshida, S; Yoshida, T; Zaleski, K D; Zanolin, M; Zawischa, I; Zhang, L; Zhu, R; Zhu, Z H; Zotov, N P; Zucker, M; Zweizig, J

    2006-01-01

    We search for coincident gravitational wave signals from inspiralling neutron star binaries using LIGO and TAMA300 data taken during early 2003. Using a simple trigger exchange method, we perform an inter-collaboration coincidence search during times when TAMA300 and only one of the LIGO sites were operational. This data set is complementary to that used in the LIGO S2 search. The observation time of the search is 648 hours. We find no evidence of any gravitational wave signals. We place an observational upper limit on the rate of binary neutron star coalescence with component masses between 1 and 3 M_sun of 49 per year per Milky Way equivalent galaxy at a 90% confidence level.

  1. Amino Acid Catabolism in Plants.

    Science.gov (United States)

    Hildebrandt, Tatjana M; Nunes Nesi, Adriano; Araújo, Wagner L; Braun, Hans-Peter

    2015-11-02

    Amino acids have various prominent functions in plants. Besides their usage during protein biosynthesis, they also represent building blocks for several other biosynthesis pathways and play pivotal roles during signaling processes as well as in plant stress response. In general, pool sizes of the 20 amino acids differ strongly and change dynamically depending on the developmental and physiological state of the plant cell. Besides amino acid biosynthesis, which has already been investigated in great detail, the catabolism of amino acids is of central importance for adjusting their pool sizes but so far has drawn much less attention. The degradation of amino acids can also contribute substantially to the energy state of plant cells under certain physiological conditions, e.g. carbon starvation. In this review, we discuss the biological role of amino acid catabolism and summarize current knowledge on amino acid degradation pathways and their regulation in the context of plant cell physiology.

  2. Observation of Neutron Skyshine from an Accelerator Based Neutron Source

    Energy Technology Data Exchange (ETDEWEB)

    Franklyn, C. B. [Radiation Science Department, Necsa, PO Box 582, Pretoria 0001 (South Africa)

    2011-12-13

    A key feature of neutron based interrogation systems is the need for adequate provision of shielding around the facility. Accelerator facilities adapted for fast neutron generation are not necessarily suitably equipped to ensure complete containment of the vast quantity of neutrons generated, typically >10{sup 11} n{center_dot}s{sup -1}. Simulating the neutron leakage from a facility is not a simple exercise since the energy and directional distribution can only be approximated. Although adequate horizontal, planar shielding provision is made for a neutron generator facility, it is sometimes the case that vertical shielding is minimized, due to structural and economic constraints. It is further justified by assuming the atmosphere above a facility functions as an adequate radiation shield. It has become apparent that multiple neutron scattering within the atmosphere can result in a measurable dose of neutrons reaching ground level some distance from a facility, an effect commonly known as skyshine. This paper describes a neutron detection system developed to monitor neutrons detected several hundred metres from a neutron source due to the effect of skyshine.

  3. Neutron logging tool readings and neutron parameters of formations

    Science.gov (United States)

    Czubek, Jan A.

    1995-03-01

    A case history of the calibration of neutron porosity tools is given in the paper. The calibration of neutron porosity tools is one of the most difficult, complicated, and time consuming tasks in the well logging operations in geophysics. A semi empirical approach to this problem is given in the paper. It is based on the correlation of the tool readings observed in known environments with the apparent neutron parameters sensed by the tools. The apparent neutron parameters are functions of the true neutron parameters of geological formations and of the borehole material, borehole diameter, and the tool position inside the borehole. The true integral neutron transport parameters are obtained by the multigroup diffusion approximation for slowing down of neutrons and by one thermal neutron group for the diffusion. In the latter, the effective neutron temperature is taken into account. The problem of the thermal neutron absorption cross section of rocks is discussed in detail from the point of view of its importance for the well logging results and for the experimental techniques being used.

  4. Molecular marker applications in plants.

    Science.gov (United States)

    Hayward, Alice C; Tollenaere, Reece; Dalton-Morgan, Jessica; Batley, Jacqueline

    2015-01-01

    Individuals within a population of a sexually reproducing species will have some degree of heritable genomic variation caused by mutations, insertion/deletions (INDELS), inversions, duplications, and translocations. Such variation can be detected and screened using molecular, or genetic, markers. By definition, molecular markers are genetic loci that can be easily tracked and quantified in a population and may be associated with a particular gene or trait of interest. This chapter will review the current major applications of molecular markers in plants.

  5. Coincidence Properties for Maps from the Torus to the Klein Bottle

    Institute of Scientific and Technical Information of China (English)

    Daciberg L. GON(C)ALVES; Michael R. KELLY

    2008-01-01

    The authors study the coincidence theory for pairs of maps from the Torus to the Klein bottle. Reidemeister classes and the Nielsen number are computed, and it is shown that any given pair of maps satisfies the Wecken property. The 1-parameter Wecken property is studied and a partial negative answer is derived. That is for all pairs of coincidence free maps a countable family of pairs of maps in the homotopy class is constructed such that no two members may be joined by a coincidence free homotopy.

  6. Application of length vernier in phase coincidence detection and precision frequency measurement.

    Science.gov (United States)

    Miao, Miao; Wei, Zhou; Bin, Wang

    2012-02-01

    For comparison of arbitrary frequency signals, the paper proposed two levels of length vernier based on the time-space relationship are used in three levels of phase coincidence detecting circuits to extract the phase coincidence information by proper logic calculation. The length∕phase of each vernier is respectively corresponding to the accuracy and the resolution of detecting circuit. The time-space relationship is based on high-stability, high-accuracy, and high-speed of signal transmission. The method is effective to reduce the fuzzy region in the phase coincidence information and reach a higher measuring precision.

  7. Neutron beam design for low intensity neutron and gamma-ray radioscopy using small neutron sources

    CERN Document Server

    Matsumoto, T

    2003-01-01

    Two small neutron sources of sup 2 sup 5 sup 2 Cf and sup 2 sup 4 sup 1 Am-Be radioisotopes were used for design of neutron beams applicable to low intensity neutron and gamma ray radioscopy (LINGR). In the design, Monte Carlo code (MCNP) was employed to generate neutron and gamma ray beams suited to LINGR. With a view to variable neutron spectrum and neutron intensity, various arrangements were first examined, and neutron-filter, gamma-ray shield and beam collimator were verified. Monte Carlo calculations indicated that with a suitable filter-shield-collimator arrangement, thermal neutron beam of 3,900 ncm sup - sup 2 s sup - sup 1 with neutron/gamma ratio of 7x10 sup 7 , and 25 ncm sup - sup 2 s sup - sup 1 with very large neutron/gamma ratio, respectively, could be produced by using sup 2 sup 5 sup 2 Cf(122 mu g) and a sup 2 sup 4 sup 1 Am-Be(37GBq)radioisotopes at the irradiation port of 35 cm from the neutron sources.

  8. Comparison of satellite reflectance algorithms for estimating chlorophyll-a in a temperate reservoir using coincident hyperspectral aircraft imagery and dense coincident surface observations

    Science.gov (United States)

    We analyzed 10 established and 4 new satellite reflectance algorithms for estimating chlorophyll-a (Chl-a) in a temperate reservoir in southwest Ohio using coincident hyperspectral aircraft imagery and dense water truth collected within one hour of image acquisition to develop si...

  9. Comparison of satellite reflectance algorithms for estimating chlorophyll-a in a temperate reservoir using coincident hyperspectral aircraft imagery and dense coincident surface observations

    Science.gov (United States)

    We analyzed 10 established and 4 new satellite reflectance algorithms for estimating chlorophyll-a (Chl-a) in a temperate reservoir in southwest Ohio using coincident hyperspectral aircraft imagery and dense water truth collected within one hour of image acquisition to develop si...

  10. Time correlated measurements using plastic scintillators with neutron-photon pulse shape discrimination

    Science.gov (United States)

    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

  11. Neutron Scattering Investigations of Correlated Electron Systems and Neutron Instrumentation

    DEFF Research Database (Denmark)

    Holm, Sonja Lindahl

    are a unique probe for studying the atomic and molecular structure and dynamics of materials. Even though neutrons are very expensive to produce, the advantages neutrons provide overshadow the price. As neutrons interact weakly with materials compared to many other probes, e.g. electrons or photons......, it is possible to make a neutron scattering experiment through sample environment equipment like cryostats or pressure cells. Another advantage of neutron experiments is that the wavelength and energy of the neutron match the inter-atomic distances and basic excitations of solid materials. The scattering cross...... magnetism. This is in contrast to what is observed as the critical temperature is slightly lower for this system compared to other co-doped systems, suggesting that the magnetic and superconducting phases co-exist. A published manuscript describes the study of magnetic and superconducting properties of Ba...

  12. Neutron-gamma competition for $\\beta$-delayed neutron emission

    CERN Document Server

    Mumpower, Matthew; Moller, Peter

    2016-01-01

    We present a coupled Quasi-particle Random Phase Approximation and Hauser-Feshbach (QRPA+HF) model for calculating delayed particle emission. This approach uses microscopic nuclear structure information which starts with Gamow-Teller strength distributions in the daughter nucleus, and then follows the statistical decay until the initial available excitation energy is exhausted. Explicitly included at each particle emission stage is $\\gamma$-ray competition. We explore this model in the context of neutron emission of neutron-rich nuclei and find that neutron-gamma competition can lead to both increases and decreases in neutron emission probabilities, depending on the system considered. A second consequence of this formalism is a prediction of more neutrons on average being emitted after $\\beta$-decay for nuclei near the neutron dripline compared to models that do not consider the statistical decay.

  13. High proportion of smaller ranged hummingbird species coincides with ecological specialization across the Americas

    DEFF Research Database (Denmark)

    Sonne, Jesper; Martín González, Ana M.; Maruyama, Pietro K.

    2016-01-01

    Ecological communities that experience stable climate conditions have been speculated to preserve more specialized interspecific associations and have higher proportions of smaller ranged species (SRS). Thus, areas with disproportionally large numbers of SRS are expected to coincide geographicall...

  14. X-ray fluorescence/Auger-electron coincidence spectroscopy of vacancy cascades in atomic argon

    Energy Technology Data Exchange (ETDEWEB)

    Arp, U. [National Inst. of Standards and Technology, Gaithersburg, MD (United States). Electron and Optical Physics Div.; LeBrun, T.; Southworth, S.H.; Jung, M. [Argonne National Lab., IL (United States). Physics Div.; MacDonald, M.A. [E.P.S.R.C. Daresbury Lab., Warrington (United Kingdom)

    1996-12-01

    Argon L{sub 2.3}-M{sub 2.3}M{sub 2.3} Auger-electron spectra were measured in coincidence with K{alpha} fluorescent x-rays in studies of Ar K-shell vacancy decays at several photon energies above the K-threshold and on the 1s-4p resonance in atomic argon. The complex spectra recorded by conventional electron spectroscopy are greatly simplified when recorded in coincidence with fluorescent x-rays, allowing a more detailed analysis of the vacancy cascade process. The resulting coincidence spectra are compared with Hartree-Fock calculations which include shake-up transitions in the resonant case. Small energy shifts of the coincidence electron spectra are attributed to post-collision interaction with 1s photoelectrons.

  15. A neutron portal monitor for vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Coop, K.L.; Fehlau, P.E.; Atwater, H.F.

    1987-07-12

    We have designed and built a portal vehicle monitoring systems for detecting neutron-emitting special nuclear material (SNM) such as plutonium. Monte Carlo calculations were used to optimize the design of the 15-cm-deep x 122-cm-high x 244-cm-long detector chambers, which utilize /sup 3/He proportional counters inside a hollow polyethylene box. Results for a variety of parametric studies, including polyethylene thickness and detector number, are described. Our experimental measurements are in good agreement with the computer calculations. The monitor's decision logic uses the Sequential Probability Ratio Test (SPRT) on Poisson distributed counting data, which is superior to other statistical tests in many applications. We performed computer simulations of the SPRT logic to determine expected false-positive decision rates. A controller unit of our design that uses this SPRT was built commercially. The cost of the complete monitoring system is similar to that of vehicle portal monitors that detect gamma rays. This new neutron monitor can serve as an addition to standard gamma-ray vehicle portals or as a stand-alone portal monitor in particular safeguards monitoring situations. The monitor is being tested at Los Alamos and is scheduled for in-plant evaluation of another DOE facility in 1987. 7 refs.

  16. Fast neutron imaging device and method

    Science.gov (United States)

    Popov, Vladimir; Degtiarenko, Pavel; Musatov, Igor V.

    2014-02-11

    A fast neutron imaging apparatus and method of constructing fast neutron radiography images, the apparatus including a neutron source and a detector that provides event-by-event acquisition of position and energy deposition, and optionally timing and pulse shape for each individual neutron event detected by the detector. The method for constructing fast neutron radiography images utilizes the apparatus of the invention.

  17. Progress of Neutron Bubble Detectors in CIAE

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Neutron bubble detector is the only personal neutron dosimeter which has adequate neutronsensitivity to meet the implications of the ICRP 60 recommendations for neutron dosimetry. It canmonitor the wide range of neutron energy, for example 100 eV to 10 MeV And it becomes a significanttool for neutron dose monitoring at the environment of nuclear energy.

  18. Measurement of neutron scattering lengths using neutron interferometry

    Science.gov (United States)

    Shahi, Chandra B.

    This thesis describes the details on building a new Neutron Interferometry and Optics Facility (NIOFa), the measurement of the incoherent neutron scattering length bi of 3He, and the measurement of the coherent neutron scattering length bc of 4He at National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR). A new monochromatic beamline and facility has been installed at the NCNR devoted to neutron interferometry in the research areas of spin control, spin manipulation, quantum mechanics, quantum information science, spintronics, and material science. This facility is possible in part because of advances in decoherence free subspace interferometer designs that have demonstrated consistent contrast in the presence of vibrational noise; a major environmental constraint that has prevented neutron interferometry from being applied at other neutron facilities. This new facility, NIOFa, is located in the guide hall of the NCNR upstream of the existing Neutron Interferometry and Optics Facility (NIOF) and has several advantages over the NIOF including higher incident flux, better neutron polarization, and increased accessibility. The measurement of the incoherent neutron scattering length bi of 3He was done using a (220) single silicon crystal skew symmetric interferometer. This experiment requires both a polarized beam and a polarized target. We report bi = -2.35 +/- 0.014 (stat.) +/- 0.014 (syst.). This experiment is a revision of the previous experiment which was done in 2008, and partially explains the non-zero phase shift seen in 2008 experiment even if target cell was completely unpolarized. The measurement of the coherent neutron scattering length b c of the 4He was done using a (111) single silicon crystal interferometer. The neutron interferometry and optics facility at NIST had been used previously to determine the coherent scattering lengths for n- 1H, n-2H, and n-3He to less than 1% relative uncertainty. We report bc of the 4He

  19. Coincidence and covariance data acquisition in photoelectron and -ion spectroscopy. I. Formal theory

    Science.gov (United States)

    Mikosch, Jochen; Patchkovskii, Serguei

    2013-10-01

    We derive a formal theory of noisy Poisson processes with multiple outcomes. We obtain simple, compact expressions for the probability distribution function of arbitrarily complex composite events and its moments. We illustrate the utility of the theory by analyzing properties of coincidence and covariance photoelectron-photoion detection involving single-ionization events. The results and techniques introduced in this work are directly applicable to more general coincidence and covariance experiments, including multiple ionization and multiple-ion fragmentation pathways.

  20. Direction of an approaching stimulus on coincident timing performance of a ballistic striking task.

    Science.gov (United States)

    Coker, Cheryl A

    2005-06-01

    The purpose of this study was to explore the influence of stimulus direction and velocity on the coincident timing performance of a ballistic striking task. 26 subjects randomly performed 20 trials at each of two stimulus velocities (4 and 8 mph) and two striking variations (moving with an approaching stimulus or in opposition to it). Analysis indicated the direction of an approaching stimulus does not appear to influence the coincident timing of a ballistic striking action.

  1. On Approximate Coincidence Point Properties and Their Applications to Fixed Point Theory

    OpenAIRE

    Wei-Shih Du

    2012-01-01

    We first establish some existence results concerning approximate coincidence point properties and approximate fixed point properties for various types of nonlinear contractive maps in the setting of cone metric spaces and general metric spaces. From these results, we present some new coincidence point and fixed point theorems which generalize Berinde-Berinde's fixed point theorem, Mizoguchi-Takahashi's fixed point theorem, and some well-known results in the literature.

  2. Neutron electric polarizability

    CERN Document Server

    Alexandru, Andrei

    2009-01-01

    We use the background field method to extract the "connected" piece of the neutron electric polarizability. We present results for quenched simulations using both clover and Wilson fermions and discuss our experience in extracting the mass shifts and the challenges we encountered when we lowered the quark mass. For the neutron we find that as the pion mass is lowered below $500\\MeV$, the polarizability starts rising in agreement with predictions from chiral perturbation theory. For our lowest pion mass, $m_\\pi=320\\MeV$, we find that $\\alpha_n = 3.8(1.3)\\times 10^{-4}\\fm^3$, which is still only one third of the experimental value. We also present results for the neutral pion; we find that its polarizability turns negative for pion masses smaller than $500\\MeV$ which is puzzling.

  3. Neutron beam measurement dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Amaro, C.R. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1995-11-01

    This report describes animal dosimetry studies and phantom measurements. During 1994, 12 dogs were irradiated at BMRR as part of a 4 fraction dose tolerance study. The animals were first infused with BSH and irradiated daily for 4 consecutive days. BNL irradiated 2 beagles as part of their dose tolerance study using BPA fructose. In addition, a dog at WSU was irradiated at BMRR after an infusion of BPA fructose. During 1994, the INEL BNCT dosimetry team measured neutron flux and gamma dose profiles in two phantoms exposed to the epithermal neutron beam at the BMRR. These measurements were performed as a preparatory step to the commencement of human clinical trials in progress at the BMRR.

  4. Neutron Scattering Stiudies

    Energy Technology Data Exchange (ETDEWEB)

    Kegel, Gunter H.R.; Egan, James J

    2007-04-18

    This project covers four principal areas of research: Elastic and inelastic neutron scattering studies in odd-A terbium, thulium and other highly deformed nuclei near A=160 with special regard to interband transitions and to the investigation of the direct-interaction versus the compound-nucleus excitation process in these nuclei. Examination of new, fast photomultiplier tubes suitable for use in a miniaturized neutron-time-of-flight spectrometer. Measurement of certain inelastic cross sections of 238U. Determination of the multiplicity of prompt fission gamma rays in even-A fissile actinides. Energies and mean lives of fission isomers produced by fast fission of even-Z, even-A actinides. Study of the mean life of 7Be in different host matrices and its possible astro-physical significance.

  5. Neutrons from Antiproton Irradiation

    DEFF Research Database (Denmark)

    Bassler, Niels; Holzscheiter, Michael; Petersen, Jørgen B.B.

    Background: Radiotherapy with Antiprotons is currently investigated by the AD-4/ACE collaboration. The hypothesis is that the additional energy released from the antiprotons annihilating at the target nuclei can enable a reduced dose in the entry channel of the primary beam. Furthermore an enhanced...... relative biological effect (RBE) has already been beam measured in spread out Bragg peaks of antiprotons, relative to that found in the plateau region. However, the antiproton annihilation process is associated with a substantial release of secondary particles which contribute to the dose outside...... the neutron spectrum. Additionally, we used a cylindrical polystyrene loaded with several pairs of thermoluminescent detectors containing Lithium-6 and Lithium-7, which effectively detects thermalized neutrons. The obtained results are compared with FLUKA imulations. Results: The results obtained...

  6. Neutron Transport Simulations for NIST Neutron Lifetime Experiment

    Science.gov (United States)

    Li, Fangchen; BL2 Collaboration Collaboration

    2016-09-01

    Neutrons in stable nuclei can exist forever; a free neutron lasts for about 15 minutes on average before it beta decays to a proton, an electron, and an antineutrino. Precision measurements of the neutron lifetime test the validity of weak interaction theory and provide input into the theory of the evolution of light elements in the early universe. There are two predominant ways of measuring the neutron lifetime: the bottle method and the beam method. The bottle method measures decays of ultracold neutrons that are stored in a bottle. The beam method measures decay protons in a beam of cold neutrons of known flux. An improved beam experiment is being prepared at the National Institute of Science and Technology (Gaithersburg, MD) with the goal of reducing statistical and systematic uncertainties to the level of 1 s. The purpose of my studies was to develop computer simulations of neutron transport to determine the beam collimation and study the neutron distribution's effect on systematic effects for the experiment, such as the solid angle of the neutron flux monitor. The motivation for the experiment and the results of this work will be presented. This work was supported, in part, by a Grant to Gettysburg College from the Howard Hughes Medical Institute through the Precollege and Undergraduate Science Education Program.

  7. High-resolution neutron microtomography with noiseless neutron counting detector

    Energy Technology Data Exchange (ETDEWEB)

    Tremsin, A.S., E-mail: ast@ssl.berkeley.edu [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); McPhate, J.B.; Vallerga, J.V.; Siegmund, O.H.W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Feller, W.B. [Nova Scientific Inc., 10 Picker Road, Sturbridge, MA 01566 (United States); Lehmann, E. [Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Butler, L.G. [Louisiana State University, Baton Rouge, LA 70803 (United States); Dawson, M. [Helmholtz Centre Berlin for Materials and Energy (Germany)

    2011-10-01

    The improved collimation and intensity of thermal and cold neutron beamlines combined with recent advances in neutron imaging devices enable high-resolution neutron radiography and microtomography, which can provide information on the internal structure of objects not achievable with conventional X-ray imaging techniques. Neutron detection efficiency, spatial and temporal resolution (important for the studies of dynamic processes) and low background count rate are among the crucial parameters defining the quality of radiographic images and tomographic reconstructions. The unique capabilities of neutron counting detectors with neutron-sensitive microchannel plates (MCPs) and with Timepix CMOS readouts providing high neutron detection efficiency ({approx}70% for cold neutrons), spatial resolutions ranging from 15 to 55 {mu}m and a temporal resolution of {approx}1 {mu}s-combined with the virtual absence of readout noise-make these devices very attractive for high-resolution microtomography. In this paper we demonstrate the capabilities of an MCP-Timepix detection system applied to microtomographic imaging, performed at the ICON cold neutron facility of the Paul Scherrer Institute. The high resolution and the absence of readout noise enable accurate reconstruction of texture in a relatively opaque wood sample, differentiation of internal tissues of a fly and imaging of individual {approx}400 {mu}m grains in an organic powder encapsulated in a {approx}700 {mu}m thick metal casing.

  8. Neutrons in the moon. [neutron flux and production rate calculations

    Science.gov (United States)

    Kornblum, J. J.; Fireman, E. L.; Levine, M.; Aronson, A.

    1973-01-01

    Neutron fluxes for energies between 15 MeV and thermal at depths of 0 to 300 g/sq cm in the moon are calculated by the discrete ordinate mathod with the ANISN code. With the energy spectrum of Lingenfelter et al. (1972). A total neutron-production rate for the moon of 26 plus or minus neutrons/sq cm sec is determined from the Ar-37 activity measurements in the Apollo 16 drill string, which are found to have a depth dependence in accordance with a neutron source function that decreases exponentially with an attenuation length of 155 g/sq cm.

  9. Are there good probes for the di-neutron correlation in light neutron-rich nuclei?

    CERN Document Server

    Hagino, K

    2015-01-01

    The di-neutron correlation is a spatial correlation with which two valence neutrons are located at a similar position inside a nucleus. We discuss possible experimental probes for the di-neutron correlation. This includes the Coulomb breakup and the pair transfer reactions of neutron-rich nuclei, and the direct two-neutron decays of nuclei beyond the neutron drip-line.

  10. Low level radioactivity measurements with phoswich detectors using coincident techniques and digital pulse processing analysis

    Energy Technology Data Exchange (ETDEWEB)

    Fuente, R. de la [University of Leon, Escuela de Ingenieria Industrial, Leon 24071 (Spain); Celis, B. de [University of Leon, Escuela de Ingenieria Industrial, Leon 24071 (Spain)], E-mail: bcelc@unileon.es; Canto, V. del; Lumbreras, J.M. [University of Leon, Escuela de Ingenieria Industrial, Leon 24071 (Spain); Celis, Alonso B. de [King' s College London, IoP, De Crespigny Park, SE58AF (United Kingdom); Martin-Martin, A. [Laboratorio LIBRA, Edificio I-D, Paseo Belen 3. 47011 Valladolid (Spain); Departamento de Fisica Teorica, Atomica y Optica, Facultad de Ciencias. Po Prado de la Magdalena, s/n. 47005 Valladolid (Spain)], E-mail: alonsomm@libra.uva.es; Gutierrez-Villanueva, J.L. [Laboratorio LIBRA, Edificio I-D, Paseo Belen 3. 47011 Valladolid (Spain); Departamento de Fisica Teorica, Atomica y Optica, Facultad de Ciencias. Po Prado de la Magdalena, s/n. 47005 Valladolid (Spain)], E-mail: joselg@libra.uva.es

    2008-10-15

    A new system has been developed for the detection of low radioactivity levels of fission products and actinides using coincidence techniques. The device combines a phoswich detector for {alpha}/{beta}/{gamma}-ray recognition with a fast digital card for electronic pulse analysis. The phoswich can be used in a coincident mode by identifying the composed signal produced by the simultaneous detection of {alpha}/{beta} particles and X-rays/{gamma} particles. The technique of coincidences with phoswich detectors was proposed recently to verify the Nuclear Test Ban Treaty (NTBT) which established the necessity of monitoring low levels of gaseous fission products produced by underground nuclear explosions. With the device proposed here it is possible to identify the coincidence events and determine the energy and type of coincident particles. The sensitivity of the system has been improved by employing liquid scintillators and a high resolution low energy germanium detector. In this case it is possible to identify simultaneously by {alpha}/{gamma} coincidence transuranic nuclides present in environmental samples without necessity of performing radiochemical separation. The minimum detectable activity was estimated to be 0.01 Bq kg{sup -1} for 0.1 kg of soil and 1000 min counting.

  11. Precision Measurement of 56Fe(n,n γ) Cross Sections Using 14.1 MeV Neutrons

    Science.gov (United States)

    Wang, Haoyu; Koltick, David

    2016-03-01

    Integral production cross sections for 846.8 keV and 1238.3 keV prompt gamma rays from 14.1 MeV neutrons interactions on 56Fe are reported. The experimental technique takes advantage of the 1.5 nanosecond coincidence timing resolution between the neutron production time and the gamma ray detection time to reject noise, together with the large 30% solid angle gamma ray coverage. The scattering angle coverage with respect to the neutron beam direction extends from 60 degrees to 120 degrees. The neutron flux is measured using the detected associated alpha-particle from the D-T fusion reaction produced using an associated particle neutron generator. Present cross section measurements using other techniques with limited timing resolution and solid angle coverage are in agreement at neutron energies lower than 6 MeV. At higher neutron energies reported results can disagree by more than 20%. The more accurate technique used in these measurements can distinguish between the differences in the present reported results at higher neutron energies. The author would like to thank TechSource, Inc. and Advanced Physics Technologies, LLC. for their support in this work.

  12. Fission Multiplicity Detection with Temporal Gamma-Neutron Discrimination from Higher-Order Time Correlation Statistics

    Energy Technology Data Exchange (ETDEWEB)

    Oberer, R.B.

    2002-11-12

    The current practice of nondestructive assay (NDA) of fissile materials using neutrons is dominated by the {sup 3}He detector. This has been the case since the mid 1980s when Fission Multiplicity Detection (FMD) was replaced with thermal well counters and neutron multiplicity counting (NMC). The thermal well counters detect neutrons by neutron capture in the {sup 3}He detector subsequent to moderation. The process of detection requires from 30 to 60 {micro}s. As will be explained in Section 3.3 the rate of detecting correlated neutrons (signal) from the same fission are independent of this time but the rate of accidental correlations (noise) are proportional to this time. The well counters are at a distinct disadvantage when there is a large source of uncorrelated neutrons present from ({alpha}, n) reactions for example. Plastic scintillating detectors, as were used in FMD, require only about 20 ns to detect neutrons from fission. One thousandth as many accidental coincidences are therefore accumulated. The major problem with the use of fast-plastic scintillation detectors, however, is that both neutrons and gamma rays are detected. The pulses from the two are indistinguishable in these detectors. For this thesis, a new technique was developed to use higher-order time correlation statistics to distinguish combinations of neutron and gamma ray detections in fast-plastic scintillation detectors. A system of analysis to describe these correlations was developed based on simple physical principles. Other sources of correlations from non-fission events are identified and integrated into the analysis developed for fission events. A number of ratios and metric are identified to determine physical properties of the source from the correlations. It is possible to determine both the quantity being measured and detection efficiency from these ratios from a single measurement without a separate calibration. To account for detector dead-time, an alternative analytical technique

  13. Precision Cross Sections Measurement of 56Fe(n,n γ) at 14.1 MeV using Associated Particle Neutron Elemental Imaging Technique

    Science.gov (United States)

    Wang, Haoyu; Koltick, David

    2017-01-01

    Integral production cross sections for 846.8 keV and 1238.3 keV prompt gamma rays from 14.1 MeV neutrons interactions on 56Fe and are reported, using Associated Particle Neutron Elemental Imaging technique. The experimental technique involves: (1) The development of a VME standard high speed DAQ system and a MATLAB parallel cluster for offline signal analysis with full control of data flow; (2) The advantage of the <1.5 ns coincidence timing resolution between the neutron production and the gamma ray detection to reject noise; (3) A large 30% solid angle gamma ray coverage by an array of NaI(Tl) detectors. The neutron flux is measured through detecting the associated alpha-particle from the D-T fusion reaction in the neutron generator. Present cross section measurements using other techniques with limited timing resolution and solid angle coverage are in agreement at neutron energies lower than 6 MeV. At higher neutron energies reported results can disagree by more than 20%. This more accurate technique presented can distinguish between the differences in the reported results based on pulse-mode neutron source and neutron time-of-flight techniques, at higher neutron energies.

  14. Neutrons are flying

    CERN Multimedia

    2000-01-01

    View of the n_TOF tube with members of the design and construction team of the facility(from left to right: R. Magnin/LHC, E. Radermacher/EP, P. Cennini/EP and R. Cappi/PS). A new experimental facility was inaugurated at CERN on Wednesday 8 November. The neutron Time Of Flight (n_TOF) facility received its first protons from the PS at 10:55. With an intensity of 1 x 1011 protons per cycle on the n_TOF target, an intense neutron beam has been produced at CERN for the first time, opening the door to many new avenues of research including, for example, neutron induced cross-section measurements. The facility is an offspring of the work by Carlo Rubbia and his group on the novel idea of an Energy Amplifier. The basic idea was successfully tested at the PS with the FEAT experiment and later with the TARC experiment, where the feasibility of transmutation of long-lived products by Adiabatic Resonance Crossing (ARC) was confirmed. This led to the possibility of radio-isotope production for medical applications, fo...

  15. Neutron instrumentation for biology

    Energy Technology Data Exchange (ETDEWEB)

    Mason, S.A. [Institut Laue-Langevin, Grenoble (France)

    1994-12-31

    In the October 1994 round of proposals at the ILL, the external biology review sub- committee was asked to allocate neutron beam time to a wide range of experiments, on almost half the total number of scheduled neutron instruments: on 3 diffractometers, on 3 small angle scattering instruments, and on some 6 inelastic scattering spectrometers. In the 3.5 years since the temporary reactor shutdown, the ILL`s management structure has been optimized, budgets and staff have been trimmed, the ILL reactor has been re-built, and many of the instruments up-graded, many powerful (mainly Unix) workstations have been introduced, and the neighboring European Synchrotron Radiation Facility has established itself as the leading synchrotron radiation source and has started its official user program. The ILL reactor remains the world`s most intense dedicated neutron source. In this challenging context, it is of interest to review briefly the park of ILL instruments used to study the structure and energetics of small and large biological systems. A brief summary will be made of each class of experiments actually proposed in the latest ILL proposal round.

  16. Euratom Neutron Radiography Working Group

    DEFF Research Database (Denmark)

    Domanus, Joseph Czeslaw

    1986-01-01

    In 1979 a Neutron Radiography Working Group (NRWG) was constituted within Buratom with the participation of all centers within the European Community at which neutron facilities were available. The main purpose of NRWG was to standardize methods and procedures used in neutron radiography of nuclear...... reactor fuel as well as establish standards for radiographic image quality of neutron radiographs. The NRWG meets once a year in each of the neutron radiography centers to review the progress made and draw plans for the future. Besides, ad-hoc sub-groups or. different topics within the field of neutron...... radiography are constituted. This paper reviews the activities and achievements of the NRWG and its sub-groups....

  17. Neutron background estimates in GESA

    Directory of Open Access Journals (Sweden)

    Fernandes A.C.

    2014-01-01

    Full Text Available The SIMPLE project looks for nuclear recoil events generated by rare dark matter scattering interactions. Nuclear recoils are also produced by more prevalent cosmogenic neutron interactions. While the rock overburden shields against (μ,n neutrons to below 10−8 cm−2 s−1, it itself contributes via radio-impurities. Additional shielding of these is similar, both suppressing and contributing neutrons. We report on the Monte Carlo (MCNP estimation of the on-detector neutron backgrounds for the SIMPLE experiment located in the GESA facility of the Laboratoire Souterrain à Bas Bruit, and its use in defining additional shielding for measurements which have led to a reduction in the extrinsic neutron background to ∼ 5 × 10−3 evts/kgd. The calculated event rate induced by the neutron background is ∼ 0,3 evts/kgd, with a dominant contribution from the detector container.

  18. Calcium imaging perspectives in plants.

    Science.gov (United States)

    Kanchiswamy, Chidananda Nagamangala; Malnoy, Mickael; Occhipinti, Andrea; Maffei, Massimo E

    2014-03-04

    The calcium ion (Ca2+) is a versatile intracellular messenger. It provides dynamic regulation of a vast array of gene transcriptions, protein kinases, transcription factors and other complex downstream signaling cascades. For the past six decades, intracellular Ca2+ concentration has been significantly studied and still many studies are under way. Our understanding of Ca2+ signaling and the corresponding physiological phenomenon is growing exponentially. Here we focus on the improvements made in the development of probes used for Ca2+ imaging and expanding the application of Ca2+ imaging in plant science research.

  19. Peptide primary messengers in plants

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The peptide primary messengers regulate embryonic development,cell growth and many other activities in animal cells. But recent evidence verified that peptide primary messengers are also involved in plant defense responses, the recognition between pollen and stigma and keep the balance between cell proliferation and differentiations in shoot apical meristems. Those results suggest that plants may actually make wide use of peptide primary messengers, both in embryonic development and late life when they rally their cells to defend against pathogens and insect pests. The recent advance in those aspects is reviewed.

  20. Neutron Imaging by Boric Acid

    CERN Document Server

    Cardone, Fabio; Perconti, Walter; Petrucci, Andrea; Rosada, Alberto

    2013-01-01

    In this paper a new type of passive neutron detector based on the already existing one, CR39, is described. Its operation was verified by three different neutron sources: an Americium-Beryllium (Am241-Be) source; a TRIGA type nuclear reactor; and a fast neutron reactor called TAPIRO. The obtained results, reported here, positively confirm its operation and the accountability of the new developed detecting technique.

  1. NEUTRON IMAGING, RADIOGRAPHY AND TOMOGRAPHY.

    Energy Technology Data Exchange (ETDEWEB)

    SMITH,G.C.

    2002-03-01

    Neutrons are an invaluable probe in a wide range of scientific, medical and commercial endeavors. Many of these applications require the recording of an image of the neutron signal, either in one-dimension or in two-dimensions. We summarize the reactions of neutrons with the most important elements that are used for their detection. A description is then given of the major techniques used in neutron imaging, with emphasis on the detection media and position readout principle. Important characteristics such as position resolution, linearity, counting rate capability and sensitivity to gamma-background are discussed. Finally, the application of a subset of these instruments in radiology and tomography is described.

  2. Centrifugal quantum states of neutrons

    Science.gov (United States)

    Nesvizhevsky, V. V.; Petukhov, A. K.; Protasov, K. V.; Voronin, A. Yu.

    2008-09-01

    We propose a method for observation of the quasistationary states of neutrons localized near a curved mirror surface. The bounding effective well is formed by the centrifugal potential and the mirror Fermi potential. This phenomenon is an example of an exactly solvable “quantum bouncer” problem that can be studied experimentally. It could provide a promising tool for studying fundamental neutron-matter interactions, as well as quantum neutron optics and surface physics effects. We develop a formalism that describes quantitatively the neutron motion near the mirror surface. The effects of mirror roughness are taken into account.

  3. Ukraine experimental neutron source facility.

    Energy Technology Data Exchange (ETDEWEB)

    Gohar, Y.; Bolshinsky, I.; Nekludov, I.; Karnaukhov, I. (Nuclear Engineering Division); (INL); (Kharkov Institute of Physics and Technology)

    2008-01-01

    Kharkov Institute of Physics and Technology (KIPT) of Ukraine has a plan to construct an experimental neutron source facility. The facility has been developed for producing medical isotopes, training young nuclear professionals, supporting the Ukraine nuclear industry, providing capability for performing reactor physics, material research, and basic science experiments. Argonne National Laboratory (ANL) of USA is collaborating with KIPT on developing this facility. A driven subcritical assembly utilizing the KIPT electron accelerator with a target assembly is used to generate the neutron source. The target assembly utilizes tungsten or uranium for neutron production through photonuclear reactions with 100-KW of electron beam power. The neutron source intensity, spectrum, and spatial distribution have been studied to maximize the neutron yield and satisfy different engineering requirements. The subcritical assembly is designed to obtain the highest possible neutron flux intensity with a subcriticality of 0.98. Low enrichment uranium is used for the fuel material because it enhances the neutron source performance. Safety, reliability, and environmental considerations are included in the facility conceptual design. Horizontal neutron channels are incorporated for performing basic research including cold neutron source. This paper describes the conceptual design and summarizes some of the related analyses.

  4. Ultra-Cold Neutrons (UCN)

    Data.gov (United States)

    Federal Laboratory Consortium — Researchers working at the Los Alamos Neutron Science Center and eight other member institutions of an international collaboration are constructing the most intense...

  5. Reactor neutrons in nuclear astrophysics

    Science.gov (United States)

    Reifarth, René; Glorius, Jan; Göbel, Kathrin; Heftrich, Tanja; Jentschel, Michael; Jurado, Beatriz; Käppeler, Franz; Köster, Ulli; Langer, Christoph; Litvinov, Yuri A.; Weigand, Mario

    2017-09-01

    The huge neutron fluxes offer the possibility to use research reactors to produce isotopes of interest, which can be investigated afterwards. An example is the half-lives of long-lived isotopes like 129I. A direct usage of reactor neutrons in the astrophysical energy regime is only possible, if the corresponding ions are not at rest in the laboratory frame. The combination of an ion storage ring with a reactor and a neutron guide could open the path to direct measurements of neutron-induced cross sections on short-lived radioactive isotopes in the astrophysically interesting energy regime.

  6. Experimental characterization of HOTNES: A new thermal neutron facility with large homogeneity area

    Science.gov (United States)

    Bedogni, R.; Sperduti, A.; Pietropaolo, A.; Pillon, M.; Pola, A.; Gómez-Ros, J. M.

    2017-01-01

    A new thermal neutron irradiation facility, called HOTNES (HOmogeneous Thermal NEutron Source), was established in the framework of a collaboration between INFN-LNF and ENEA-Frascati. HOTNES is a polyethylene assembly, with about 70 cmx70 cm square section and 100 cm height, including a large, cylindrical cavity with diameter 30 cm and height 70 cm. The facility is supplied by a 241Am-B source located at the bottom of this cavity. The facility was designed in such a way that the iso-thermal-fluence surfaces, characterizing the irradiation volume, coincide with planes parallel to the cavity bottom. The thermal fluence rate across a given isofluence plane is as uniform as 1% on a disk with 30 cm diameter. Thermal fluence rate values from about 700 cm-2 s-1 to 1000 cm-2 s-1 can be achieved. The facility design, previously optimized by Monte Carlo simulation, was experimentally verified. The following techniques were used: gold activation foils to assess the thermal fluence rate, semiconductor-based active detector for mapping the irradiation volume, and Bonner Sphere Spectrometer to determine the complete neutron spectrum. HOTNES is expected to be attractive for the scientific community involved in neutron metrology, neutron dosimetry and neutron detector testing.

  7. Thunderstorms as probable reason of high background neutron fluxes on L<1.2

    Science.gov (United States)

    Bratolyubova-Tsulukidze, L.; Grachev, E.; Grigoryan, O.; Kunitsyn, V.; Kuzhevskiy, B.; Nechaev, O.; Usanova, M.

    In this paper we analyze the neutron emission observations made in the experiment onboard MIR orbital station (1991), ISS (2002) and Colibri-2002 satellite (2002) at the altitude of 400 km. The helium discharge detectors made it possible to detect neutrons with energies ranging from 0.25eV to 1.9MeV. The spatial distribution of high background neutron fluxes has a longitude dependence. These events have been observed at -200 ... 600 and 1350 ...1800 ...- 1350 longitudinal intervals. The most intensive fluxes near the geomagnetic equator were registered in the African region. They are not found to be associated with increases of proton fluxes (Ep >50MeV). As a statistical set, the events appear to coincide with the most active region of atmospheric weather. In this paper we assess the possibility that the occurrence of high background neutron fluxes in the African region is connected with lightning discharges. To observe neutron emission at the altitude of 400 km ~101 0 neutrons are required to be produced by lightning discharge. These theoretical predictions suggest cloud charge values of about 250-300 Coulomb.

  8. Statistical estimation of the performance of a fast-neutron multiplicity system for nuclear material accountancy

    Energy Technology Data Exchange (ETDEWEB)

    Chichester, David L., E-mail: david.chichester@inl.gov [Idaho National Laboratory, 2525 N. Fremont Avenue, Idaho Falls, ID 83415 (United States); Thompson, Scott J.; Kinlaw, Mathew T.; Johnson, James T. [Idaho National Laboratory, 2525 N. Fremont Avenue, Idaho Falls, ID 83415 (United States); Dolan, Jennifer L.; Flaska, Marek; Pozzi, Sara A. [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109-2104 (United States)

    2015-06-01

    Statistical analyses have been performed to develop bounding estimates of the expected performance of a conceptual fast-neutron multiplicity system (FNMS) for assaying plutonium. The conceptual FNMS design includes 32 cubic liquid scintillator detectors, measuring 7.62 cm per side, configured into 4 stacked rings of 8 detectors each. Expected response characteristics for the individual FNMS detectors, as well as the response characteristics of the entire FNMS, were determined using Monte Carlo simulations based on prior validation experiments. The results from these simulations were then used to estimate the Pu assay capabilities of the FNMS in terms of counting time, assay mass, and assay mass variance, using assay mass variance as a figure of merit. The analysis results are compared against a commonly used thermal-neutron coincidence counter. The advantages of using a fast-neutron counting system versus a thermal-neutron counting system are significant. Most notably, the time required to perform an assay to an equivalent assay mass variance is greatly reduced with a fast-neutron system, by more than an order of magnitude compared with that of the thermal-neutron system, due to the reduced probability of random summing with the fast system. The improved FNMS performance is especially relevant for assays involving Pu masses of 10 g or more.

  9. Measurement of neutron diffraction with compact neutron source RANS

    Science.gov (United States)

    Ikeda, Y.; Takamura, M.; Taketani, A.; Sunaga, H.; Otake, Y.; Suzuki, H.; Kumagai, M.; Oba, Y.; Hama, T.

    2016-11-01

    Diffraction is used as a measurement technique for crystal structure. X-rays or electron beam with wavelength that is close to the lattice constant of the crystal is often used for the measurement. They have sensitivity in surface (0.01mm) of heavy metals due to the mean free path for heavy ions. Neutron diffraction has the probe of the internal structure of the heavy metals because it has a longer mean free path than that of the X-rays or the electrons. However, the neutron diffraction measurement is not widely used because large facilities are required in the many neutron sources. RANS (Riken Accelerator-driven Compact Neutron Source) is developed as a neutron source which is usable easily in laboratories and factories. In RANS, fast neutrons are generated by 7MeV protons colliding on a Be target. Some fast neutrons are moderated with polyethylene to thermal neutrons. The thermal neutrons of 10meV which have wavelength of 10nm can be used for the diffraction measurement. In this study, the texture evolution in steels was measured with RANS and the validity of the compact neutron source was proved. The texture of IF steel sheets with the thickness of 1.0mm was measured with 10minutes run. The resolution is 2% and is enough to analyze a evolution in texture due to compression/tensile deformation or a volume fraction of two phases in the steel sample. These results have proven the possibility to use compact neutron source for the analysis of mesoscopic structure of metallic materials.

  10. T-violation in neutron optics

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, Y. [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

    1996-08-01

    Experimental method to detect a T-odd correlation term in neutron propagation through a nuclear target is discussed. The correlation term is between the neutron spin, neutron momentum and nuclear spin. (author)

  11. Fundamental physics research and neutron interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Ioffe, A. [Hahn-Meitner-Institut Berlin GmbH (Germany)

    1996-08-01

    The possibility of the use of an extremely sensitive neutron interferometry technique for the study of electromagnetic structure of the neutron and the parity non-conservative effects in neutron spin rotation is discussed. (author)

  12. Geant4 simulation of the solar neutron telescope at Sierra Negra, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, L.X., E-mail: xavier@geofisica.unam.m [Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, 04510 D.F. (Mexico); Sanchez, F. [Comision Nacional de Energia Atomica, 1429 Buenos Aires (Argentina); Valdes-Galicia, J.F. [Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, 04510 D.F. (Mexico)

    2010-02-01

    The solar neutron telescope (SNT) at Sierra Negra (19.0 deg. N, 97.3 deg. W and 4580 m.a.s.l) is part of a worldwide network of similar detectors (Valdes-Galicia et al., (2004)). This SNT has an area of 4 m{sup 2}; it is composed by four 1 mx1 mx30 cm plastic scintillators (Sci). The Telescope is completely surrounded by anti-coincidence proportional counters (PRCs) to separate charged particles from the neutron flux. In order to discard photon background it is shielded on its sides by 10 mm thick iron plates and on its top by 5 mm lead plates. It is capable of registering four different channels corresponding to four energy deposition thresholds: E>30, >60, >90 and >120 MeV. The arrival direction of neutrons is determined by gondolas of PRCs in electronic coincidence, four layers of these gondolas orthogonally located underneath the SNT, two in the NS direction and two in the EW direction. We present here simulations of the detector response to neutrons, protons, electrons and gammas in range of energies from 100 to 1000 MeV. We report on the detector efficiency and on its angular resolution for particles impinging the device with different zenith angles. The simulation code was written using the Geant4 package (Agostinelli et al., (2003)), taking into account all relevant physical processes.

  13. Fingerprinting antioxidative activities in plants

    Science.gov (United States)

    Saleh, Livia; Plieth, Christoph

    2009-01-01

    Background A plethora of concurrent cellular activities is mobilised in the adaptation of plants to adverse environmental conditions. This response can be quantified by physiological experiments or metabolic profiling. The intention of this work is to reduce the number of metabolic processes studied to a minimum of relevant parameters with a maximum yield of information. Therefore, we inspected 'summary parameters' characteristic for whole classes of antioxidative metabolites and key enzymes. Results Three bioluminescence assays are presented. A horseradish peroxidase-based total antioxidative capacity (TAC) assay is used to probe low molecular weight antioxidants. Peroxidases are quantified by their luminol converting activity (LUPO). Finally, we quantify high molecular weight superoxide anion scavenging activity (SOSA) using coelenterazine. Experiments with Lepidium sativum L. show how salt, drought, cold, and heat influence the antioxidative system represented here by TAC, LUPO, SOSA, catalase, and glutathione reductase (GR). LUPO and SOSA run anti-parallel under all investigated stress conditions suggesting shifts in antioxidative functions rather than formation of antioxidative power. TAC runs in parallel with GR. This indicates that a majority of low molecular weight antioxidants in plants is represented by glutathione. Conclusion The set of assays presented here is capable of characterising antioxidative activities in plants. It is inexpensive, quick and reproducible and delivers quantitative data. 'Summary parameters' like TAC, LUPO, and SOSA are quantitative traits which may be promising for implementation in high-throughput screening for robustness of novel mutants, transgenics, or breeds. PMID:19171044

  14. Chromosome segregation in plant meiosis

    Science.gov (United States)

    Zamariola, Linda; Tiang, Choon Lin; De Storme, Nico; Pawlowski, Wojtek; Geelen, Danny

    2014-01-01

    Faithful chromosome segregation in meiosis is essential for ploidy stability over sexual life cycles. In plants, defective chromosome segregation caused by gene mutations or other factors leads to the formation of unbalanced or unreduced gametes creating aneuploid or polyploid progeny, respectively. Accurate segregation requires the coordinated execution of conserved processes occurring throughout the two meiotic cell divisions. Synapsis and recombination ensure the establishment of chiasmata that hold homologous chromosomes together allowing their correct segregation in the first meiotic division, which is also tightly regulated by cell-cycle dependent release of cohesin and monopolar attachment of sister kinetochores to microtubules. In meiosis II, bi-orientation of sister kinetochores and proper spindle orientation correctly segregate chromosomes in four haploid cells. Checkpoint mechanisms acting at kinetochores control the accuracy of kinetochore-microtubule attachment, thus ensuring the completion of segregation. Here we review the current knowledge on the processes taking place during chromosome segregation in plant meiosis, focusing on the characterization of the molecular factors involved. PMID:24987397

  15. Peroxiredoxins in plants and cyanobacteria.

    Science.gov (United States)

    Dietz, Karl-Josef

    2011-08-15

    Peroxiredoxins (Prx) are central elements of the antioxidant defense system and the dithiol-disulfide redox regulatory network of the plant and cyanobacterial cell. They employ a thiol-based catalytic mechanism to reduce H2O2, alkylhydroperoxide, and peroxinitrite. In plants and cyanobacteria, there exist 2-CysPrx, 1-CysPrx, PrxQ, and type II Prx. Higher plants typically contain at least one plastid 2-CysPrx, one nucleo-cytoplasmic 1-CysPrx, one chloroplast PrxQ, and one each of cytosolic, mitochondrial, and plastidic type II Prx. Cyanobacteria express variable sets of three or more Prxs. The catalytic cycle consists of three steps: (i) peroxidative reduction, (ii) resolving step, and (iii) regeneration using diverse electron donors such as thioredoxins, glutaredoxins, cyclophilins, glutathione, and ascorbic acid. Prx proteins undergo major conformational changes in dependence of their redox state. Thus, they not only modulate cellular reactive oxygen species- and reactive nitrogen species-dependent signaling, but depending on the Prx type they sense the redox state, transmit redox information to binding partners, and function as chaperone. They serve in context of photosynthesis and respiration, but also in metabolism and development of all tissues, for example, in nodules as well as during seed and fruit development. The article surveys the current literature and attempts a mostly comprehensive coverage of present day knowledge and concepts on Prx mechanism, regulation, and function and thus on the whole Prx systems in plants.

  16. Chromosome segregation in plant meiosis

    Directory of Open Access Journals (Sweden)

    Linda eZamariola

    2014-06-01

    Full Text Available Faithful chromosome segregation in meiosis is essential for ploidy stability over sexual life cycles. In plants, defective chromosome segregation caused by gene mutations or other factors leads to the formation of unbalanced or unreduced gametes creating aneuploid or polyploid progeny, respectively. Accurate segregation requires the coordinated execution of conserved processes occurring throughout the two meiotic cell divisions. Synapsis and recombination ensure the establishment of chiasmata that hold homologous chromosomes together allowing their correct segregation in the first meiotic division, which is also tightly regulated by cell-cycle dependent release of cohesin and monopolar attachment of sister kinetochores to microtubules. In meiosis II, bi-orientation of sister kinetochores and proper spindle orientation correctly segregate chromosomes in four haploid cells. Checkpoint mechanisms acting at kinetochores control the accuracy of kinetochore-microtubule attachment, thus ensuring the completion of segregation. Here we review the current knowledge on the processes taking place during chromosome segregation in plant meiosis, focusing on the characterization of the molecular factors involved.

  17. Transgenerational epigenetic inheritance in plants.

    Science.gov (United States)

    Hauser, Marie-Theres; Aufsatz, Werner; Jonak, Claudia; Luschnig, Christian

    2011-08-01

    Interest in transgenerational epigenetic inheritance has intensified with the boosting of knowledge on epigenetic mechanisms regulating gene expression during development and in response to internal and external signals such as biotic and abiotic stresses. Starting with an historical background of scantily documented anecdotes and their consequences, we recapitulate the information gathered during the last 60 years on naturally occurring and induced epialleles and paramutations in plants. We present the major players of epigenetic regulation and their importance in controlling stress responses. The effect of diverse stressors on the epigenetic status and its transgenerational inheritance is summarized from a mechanistic viewpoint. The consequences of transgenerational epigenetic inheritance are presented, focusing on the knowledge about its stability, and in relation to genetically fixed mutations, recombination, and genomic rearrangement. We conclude with an outlook on the importance of transgenerational inheritance for adaptation to changing environments and for practical applications. This article is part of a Special Issue entitled "Epigenetic control of cellular and developmental processes in plants".

  18. Elicitors in Plant Tissue Culture

    Directory of Open Access Journals (Sweden)

    R. Krishnamurthy

    2013-07-01

    Full Text Available Plants or Plant cells in vitro, show physiological and morphological response to microbial, physical or chemical factors which are known as ‘elicitors’. Elicitation is a process of induced or enhanced synthesis of secondary metabolites by the plants to ensure their survival persistence and competitiveness. The application of elicitors, which is currently the focus of research, has been considered as one of the most effective methods to improve the synthesis of secondary metabolites in medicinal plants. Plant secondary metabolites are unique sources for pharmaceuticals, food additives, flavours and other industrial materials. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Commonly tested chemical elicitors are salicylic acid, methyl salicylate, bezoic acid, chitosan and so forth which affect production of phenolic compounds and activation of various defense-related enzymes in plants. Plants are challenged by a variety of biotic stresses like fungal, bacterial or viral infections. This lead to the great loss to a plant yield. Here we discuss the classification of elicitors, mechanism of elicitor, the use of elicitors and the different features of elicitors.

  19. Probing the Repulsive Core of the Nucleon-Nucleon Interaction via the He4(e ,e'pN) Triple-Coincidence Reaction

    Science.gov (United States)

    Korover, I.; Muangma, N.; Hen, O.; Shneor, R.; Sulkosky, V.; Kelleher, A.; Gilad, S.; Higinbotham, D. W.; Piasetzky, E.; Watson, J. W.; Wood, S. A.; Aguilera, P.; Ahmed, Z.; Albataineh, H.; Allada, K.; Anderson, B.; Anez, D.; Aniol, K.; Annand, J.; Armstrong, W.; Arrington, J.; Averett, T.; Badman, T.; Baghdasaryan, H.; Bai, X.; Beck, A.; Beck, S.; Bellini, V.; Benmokhtar, F.; Bertozzi, W.; Bittner, J.; Boeglin, W.; Camsonne, A.; Chen, C.; Chen, J.-P.; Chirapatpimol, K.; Cisbani, E.; Dalton, M. M.; Daniel, A.; Day, D.; de Jager, C. W.; De Leo, R.; Deconinck, W.; Defurne, M.; Flay, D.; Fomin, N.; Friend, M.; Frullani, S.; Fuchey, E.; Garibaldi, F.; Gaskell, D.; Gilman, R.; Glamazdin, O.; Gu, C.; Gueye, P.; Hamilton, D.; Hanretty, C.; Hansen, J.-O.; Hashemi Shabestari, M.; Holmstrom, T.; Huang, M.; Iqbal, S.; Jin, G.; Kalantarians, N.; Kang, H.; Khandaker, M.; LeRose, J.; Leckey, J.; Lindgren, R.; Long, E.; Mammei, J.; Margaziotis, D. J.; Markowitz, P.; Marti Jimenez-Arguello, A.; Meekins, D.; Meziani, Z.; Michaels, R.; Mihovilovic, M.; Monaghan, P.; Munoz Camacho, C.; Norum, B.; Nuruzzaman, Pan, K.; Phillips, S.; Pomerantz, I.; Posik, M.; Punjabi, V.; Qian, X.; Qiang, Y.; Qiu, X.; Rakhman, A.; Reimer, P. E.; Riordan, S.; Ron, G.; Rondon-Aramayo, O.; Saha, A.; Schulte, E.; Selvy, L.; Shahinyan, A.; Sirca, S.; Sjoegren, J.; Slifer, K.; Solvignon, P.; Sparveris, N.; Subedi, R.; Tireman, W.; Wang, D.; Weinstein, L. B.; Wojtsekhowski, B.; Yan, W.; Yaron, I.; Ye, Z.; Zhan, X.; Zhang, J.; Zhang, Y.; Zhao, B.; Zhao, Z.; Zheng, X.; Zhu, P.; Zielinski, R.; Jefferson Lab Hall A Collaboration

    2014-07-01

    We studied simultaneously the He4(e ,e'p), He4(e ,e'pp), and He4(e ,e'pn) reactions at Q2=2(GeV/c)2 and xB>1, for an (e ,e'p) missing-momentum range of 400 to 830 MeV/c. The knocked-out proton was detected in coincidence with a proton or neutron recoiling almost back to back to the missing momentum, leaving the residual A =2 system at low excitation energy. These data were used to identify two-nucleon short-range correlated pairs and to deduce their isospin structure as a function of missing momentum, in a region where the nucleon-nucleon (NN) force is expected to change from predominantly tensor to repulsive. The abundance of neutron-proton pairs is reduced as the nucleon momentum increases beyond ˜500 MeV/c. The extracted fraction of proton-proton pairs is small and almost independent of the missing momentum. Our data are compared with calculations of two-nucleon momentum distributions in He4 and discussed in the context of probing the elusive repulsive component of the NN force.

  20. Approaching the nucleon-nucleon short-range repulsive core via the 4He(e,e'pN) triple coincidence reaction

    CERN Document Server

    Muangma, I Korover N; Shneor, R; Sulkosky, V; Kelleher, A; Gilad, S; Higinbotham, D W; Watson, E Piasetzky J; Wood, S; Rakhman, Abdurahim; Aguilera, P; Ahmed, Z; Albataineh, H; Allada, K; Anderson, B; Anez, D; Aniol, K; Annand, J; Armstrong, W; Arrington, J; Averett, T; Badman, T; Baghdasaryan, H; Bai, X; Beck, A; Beck, S; Bellini, V; Benmokhtar, F; Bertozzi, W; Bittner, J; Boeglin, W; Camsonne, A; Chen, C; Chen, J -P; Chirapatpimol, K; Cisbani, E; Dalton, M; Daniel, A; Day, D; de Jager, C W; De Leo, R; Deconinck, W; Defurne, M; Flay, D; Fomin, N; Friend, M; Frullani, S; Fuchey, E; Garibaldi, F; Gaskell, D; Gilman, R; Glamazdin, O; Gu, C; Gueye, P; Hamilton, D; Hanretty, C; Hansen, O; Shabestari, M Hashemi; Holmstrom, T; Huang, M; Iqbal, S; Jin, G; Kalantarians, N; Kang, H; Khandaker, M; LeRose, J; Leckey, J; Lindgren, R; Long, E; Mammei, J; Margaziotis, D J; Markowitz, P; Jimenez-Arguello, A Marti; Meekins, D; Meziani, Z; Michaels, R; Mihovilovic, M; Monaghan, P; Camacho, C Munoz; Norum, B; Nuruzzaman,; Pan, K; Phillips, S; Pomerantz, I; Posik, M; Punjabi, V; Qian, X; Qiang, Y; Qiu, X; Reimer, P E; Riordan, S; Ron, G; Rondon-Aramayo, O; Saha, A; Schulte, E; Selvy, L; Shahinyan, A; Sirca, S; Sjoegren, J; Slifer, K; Solvignon, P; Sparveris, N; Subedi, R; Tireman, W; Wang, D; Weinstein, L B; Wojtsekhowski, B; Yan, W; Yaron, I; Ye, Z; Zhan, X; Zhang, J; Zhang, Y; Zhao, B; Zhao, Z; Zheng, X; Zhu, P; Zielinski, R

    2014-01-01

    We measured simultaneously the 4He(eep), 4He(eepp), and 4He(e,e'pn) reactions at Q^2=2 [GeV/c]2 and x_B>1, for a (e,e'p) missing-momentum range of 400 to 830 MeV/c. The knocked-out proton was detected in coincidence with a proton or neutron recoiling almost back to back to the missing momentum, leaving the residual A=2 system at low excitation energy. These data were used to identify two-nucleon short-range correlated pairs and to deduce their isospin structure as a function of missing momentum in a region where the nucleon-nucleon force is expected to change from predominantly tensor to repulsive. Neutron-proton pairs dominate the high-momentum tail of the nucleon momentum distributions, but their abundance is reduced as the nucleon momentum increases beyond ~500 MeV/c. The extracted fraction of proton-proton pairs is small and almost independent of the missing momentum in the range we studied. Our data are compared with ab-initio calculations of two-nucleon momentum distributions in 4He.

  1. Estimating the AmLi Neutron Spectrum from Measured Ring Ratios

    Energy Technology Data Exchange (ETDEWEB)

    Weinmann-Smith, Robert [Univ. of Florida, Gainesville, FL (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Beddingfield, David H. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Enqvist, Andreas [Univ. of Florida, Gainesville, FL (United States); Swinhoe, Martyn Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-11-10

    These are a set of slides on estimating the AmLi neutron spectrum from measured ring ratios. The IAEA uses an AmLi source in the Uranium Neutron Coincidence Collar (UNCL) to verify compliance with nonproliferation treaties. The UNCL requires calibration with known uranium samples. The AmLi spectrum isn’t known well enough to allow simulated calibrations. Alphas lose energy traveling through AmO2 particle of unknown size. Energy reduction below Li threshold enhances O contribution. Unknown Li matrix material affects neutron production and thermalization. There is large variation in spectra from each element. Other topics covered include: applications, physics considerations, current spectra, measurement overview, measurement results - variation between sources, simulations, spectra fitting, other simulations, and conclusions.

  2. A detection system to measure muon-induced neutrons for direct dark matter searches

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, V.Yu.; Chantelauze, A.; Kluck, H.; Eitel, K. [Karlsruhe Institute of Technology, Institut fuer Kernphysik, Postfach 3640, 76021 Karlsruhe (Germany); Armengaud, E.; Besida, O.; Gerbier, G.; Gros, M.; Hannawald, M.; Herve, S.; Lemrani, R.; Navick, X.F.; Paul, B.; Torrento-Coello, A.S. [CEA, Centre d' Etudes Nucleaires de Saclay, IRFU, 91191 Gif-sur-Yvette Cedex (FR); Augier, C.; Charlieux, F.; De Jesus, M.; Di Stefano, P.; Gascon, J.; Juillard, A.; Sanglard, V.; Scorza, S.; Vagneron, L.; Verdier, M.A. [Institut de Physique Nucleaire de Lyon, Universite de Lyon - Universite Claude Bernard Lyon 1 et IN2P3-CNRS, 4 rue Enrico Fermi, 69622 Villeurbanne (FR); Benoit, A. [Institut Neel, CNRS, 25 Avenue des Martyrs, 38042 Grenoble Cedex 9 (FR); Berge, L.; Broniatowski, A.; Chapellier, M.; Chardin, G.; Collin, S.; Defay, X.; Dolgorouki, Y.; Dumoulin, L.; Marnieros, S.; Olivieri, E. [Centre de Spectroscopie Nucleaire et de Spectroscopie de Masse, UMR8609 IN2P3-CNRS, Univ. Paris Sud, bat 108, 91405 Orsay Campus (FR); Bluemer, J. [Karlsruhe Institute of Technology, Institut fuer Kernphysik, Postfach 3640, 76021 Karlsruhe (Germany); Karlsruhe Institute of Technology, Institut fuer Experimentelle Kernphysik, Gaedestr. 1, 76128 Karlsruhe (Germany); Brudanin, V.; Lubashevskiy, A.; Rozov, S.; Semikh, S.; Yakushev, E. [Laboratory of Nuclear Problems, JINR, Joliot-Curie 6, 141980 Dubna, Moscow Region (RU); Domange, J. [CEA, Centre d' Etudes Nucleaires de Saclay, IRFU, 91191 Gif-sur-Yvette Cedex (FR); Centre de Spectroscopie Nucleaire et de Spectroscopie de Masse, UMR8609 IN2P3-CNRS, Univ. Paris Sud, bat 108, 91405 Orsay Campus (FR); Loaiza, P. [Laboratoire Souterrain de Modane, CEA-CNRS, 1125 route de Bardonneche, 73500 Modane (FR); Pari, P. [CEA, Centre d' Etudes Nucleaires de Saclay, IRAMIS, 91191 Gif-sur-Yvette Cedex (FR)

    2010-07-01

    Muon-induced neutrons constitute a prominent background component in a number of low count rate experiments, namely direct searches for dark matter. In this work we describe a neutron detector to measure this background in an underground laboratory, the Laboratoire Souterrain de Modane. The system is based on 1 m{sup 3} of Gd-loaded scintillator and it is linked with the muon veto of the EDELWEISS-II experiment for coincident muon detection. The system was installed in autumn 2008 and passed since then a number of commissioning tests proving its full functionality. The data-taking is continuously ongoing and a count rate of the order of 1 muon-induced neutron per day has been achieved. (authors)

  3. Collective Modes in a Superfluid Neutron Gas within the Quasiparticle Random-Phase Approximation

    CERN Document Server

    Martin, Noël

    2014-01-01

    We study collective excitations in a superfluid neutron gas at zero temperature within the quasiparticle random phase approximation. The particle-hole residual interaction is obtained from a Skyrme functional, while a separable interaction is used in the pairing channel which gives a realistic density dependence of the pairing gap. In accordance with the Goldstone theorem, we find an ungapped collective mode (analogous to the Bogoliubov-Anderson mode). At low momentum, its dispersion relation is approximately linear and its slope coincides with the hydrodynamic speed of sound calculated with the Skyrme equation of state. The response functions are compared with those obtained within the Landau approximation. We also compute the contribution of the collective mode to the specific heat of the neutron gas, which is relevant for the thermodynamic properties of the inner crust of neutron stars.

  4. A Multi-layered target for the Study of Neutron-Unbound Nuclei

    Science.gov (United States)

    Gueye, Paul; Frank, Nathan; Thoennessen, Michael

    2013-04-01

    The MoNA/LISA setup at the National Superconducting Cyclotron Laboratory at Michigan State University has provided an avenue to study the nuclear structure of unbound states/nuclei at and beyond the neutron drip line for the past decade using secondary beams from the Coupled Cyclotron Facility. A new multi-layered Si/Be active target is planned to be built to specifically study neutron unbound nuclei. In these experiments the decay energy is reconstructed from fragment-neutron coincidence measurements which are typically low in count rate. The multi-layered target will allow the use of thicker targets to increase the reaction rates, thus enabling to study currently out of reach nuclei such as 21C, 23C, and 24N. A description of the new setup and physics impact will be discussed.

  5. Observation of a low-lying neutron-unbound state in {sup 19}C

    Energy Technology Data Exchange (ETDEWEB)

    Thoennessen, M., E-mail: thoennessen@nscl.msu.edu [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Mosby, S. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Badger, N.S. [Department of Physics, Rhodes College, Memphis, TN 38112 (United States); Baumann, T.; Bazin, D. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Bennett, M. [Department of Physics, Westmont College, Santa Barbara, CA 93108 (United States); Brown, J. [Department of Physics, Wabash College, Crawfordsville, IN 47933 (United States); Christian, G. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); DeYoung, P.A. [Department of Physics, Hope College, Holland, MI 49423 (United States); Finck, J.E. [Department of Physics, Central Michigan University, Mt. Pleasant, MI 48859 (United States); Gardner, M. [Department of Physics, Westmont College, Santa Barbara, CA 93108 (United States); Hook, E.A. [Department of Physics, Rhodes College, Memphis, TN 38112 (United States); Luther, B. [Department of Physics, Concordia College, Moorhead, MN 56562 (United States); Meyer, D.A. [Department of Physics, Rhodes College, Memphis, TN 38112 (United States); Mosby, M. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Rogers, W.F. [Department of Physics, Westmont College, Santa Barbara, CA 93108 (United States); and others

    2013-08-21

    Proton removal reactions from a secondary {sup 22}N beam were utilized to populate unbound states in neutron-rich carbon isotopes. Neutrons were measured with the Modular Neutron Array (MoNA) in coincidence with carbon fragments. A resonance with a decay energy of 76(14) keV was observed in the system {sup 18}C+n corresponding to a state in {sup 19}C at an excitation energy of 653(95) keV. This resonance could correspond to the first 5/2{sup +} state which was recently speculated to be unbound in order to describe 1n and 2n removal cross section measurements from {sup 20}C.

  6. Quasi-elastic electron-deuteron scattering and the electric form factor of the neutron

    Energy Technology Data Exchange (ETDEWEB)

    Arenhoevel, H.; Kim, Y.E. (Mainz Univ. (Germany, F.R.). Inst. fuer Kernphysik); Craver, B.A. (Purdue Univ., Lafayette, IN (USA). Dept. of Physics); Fabian, W. (State Univ. of New York, Stony Brook (USA). Dept. of Physics); Saylor, D.P. (Worcester Polytechnic Inst., MA (USA). Dept. of Physics)

    1978-09-02

    The possibility of extracting accurately the neutron electric form factor from electron-neutron coincidence measurements in quasi-elastic electron-deuteron scattering is investigated for squared three-momentum transfers q/sup 2/<=30 fm/sup -2/ using the Reid soft-core, Hamada-Johnston and Bryan-Gersten potentials. It is found that contributions of the electric form factor of the neutron to the quasi-elastic cross section can be as large as 5.4% at q/sup 2/ approximately equal to 1 fm/sup -2/ (approximately 3% at q/sup 2/ approximately equal to 10 approximately 20 fm/sup 2/). Potential model dependence and corrections due to meson exchange currents and isobar configurations are found to be small (< or approximately 1%).

  7. Caspases in plants: metacaspase gene family in plant stress responses.

    Science.gov (United States)

    Fagundes, David; Bohn, Bianca; Cabreira, Caroline; Leipelt, Fábio; Dias, Nathalia; Bodanese-Zanettini, Maria H; Cagliari, Alexandro

    2015-11-01

    Programmed cell death (PCD) is an ordered cell suicide that removes unwanted or damaged cells, playing a role in defense to environmental stresses and pathogen invasion. PCD is component of the life cycle of plants, occurring throughout development from embryogenesis to the death. Metacaspases are cysteine proteases present in plants, fungi, and protists. In certain plant-pathogen interactions, the PCD seems to be mediated by metacaspases. We adopted a comparative genomic approach to identify genes coding for the metacaspases in Viridiplantae. We observed that the metacaspase was divided into types I and II, based on their protein structure. The type I has a metacaspase domain at the C-terminus region, presenting or not a zinc finger motif in the N-terminus region and a prodomain rich in proline. Metacaspase type II does not feature the prodomain and the zinc finger, but has a linker between caspase-like catalytic domains of 20 kDa (p20) and 10 kDa (p10). A high conservation was observed in the zinc finger domain (type I proteins) and in p20 and p10 subunits (types I and II proteins). The phylogeny showed that the metacaspases are divided into three principal groups: type I with and without zinc finger domain and type II metacaspases. The algae and moss are presented as outgroup, suggesting that these three classes of metacaspases originated in the early stages of Viridiplantae, being the absence of the zinc finger domain the ancient condition. The study of metacaspase can clarify their assignment and involvement in plant PCD mechanisms.

  8. Calculating and measuring thermal neutrons exiting from neutron diffractometers collimators

    CERN Document Server

    Tafazolee, K

    2000-01-01

    process, effectiveness of them are studied for the enhancement of the available system. Final conclusion from the simulation process, indicates that the heavy water with the thickness of 50 to 60 cm. is the best moderator for gaining the better thermal neutrons flux for enhancement of P.N.D. in the T.R.R. Powder Neutron Diffractometer y (P.N.D.) is relatively good and practical way for identification of the 3 dimensional construction of materials. In order to exploit the capabilities of this method, in one of the neutron beam of the Tehran Research Reactor (T.R.R.), a collimator embedded inside the concrete wall, direct the neutrons produced in the core reactor towards a monochromator e. Neutrons having been monochromated by 2 nd collimator are then directed towards the sample. Then the pattern of diffracted neutrons from the sample are studied. In order to make the best out of it, neutrons coming to sit on the sample must be of the thermal type. That means the number/amount of thermal neutrons flux in compar...

  9. Probing neutron star physics using accreting neutron stars

    Directory of Open Access Journals (Sweden)

    Patruno A.

    2010-10-01

    Full Text Available We give an obervational overview of the accreting neutron stars systems as probes of neutron star physics. In particular we focus on the results obtained from the periodic timing of accreting millisecond X-ray pulsars in outburst and from the measurement of X-ray spectra of accreting neutron stars during quiescence. In the first part of this overview we show that the X-ray pulses are contaminated by a large amount of noise of uncertain origin, and that all these neutron stars do not show evidence of spin variations during the outburst. We present also some recent developments on the presence of intermittency in three accreting millisecond X-ray pulsars and investigate the reason why only a small number of accreting neutron stars show X-ray pulsations and why none of these pulsars shows sub-millisecond spin periods. In the second part of the overview we introduce the observational technique that allows the study of neutron star cooling in accreting systems as probes of neutron star internal composition and equation of state. We explain the phenomenon of the deep crustal heating and present some recent developments on several quasi persistent X-ray sources where a cooling neutron star has been observed.

  10. Sequential measurements of environmental neutron energy spectrum and neutron dose

    Energy Technology Data Exchange (ETDEWEB)

    Nunomiya, Tomoya; Nakamura, Takashi; Suzuki, Hiroyuki; Terunuma, Kazutaka; Hirabayashi, Naoya; Sato, Youichi; Abe, Sigeru; Rasolonjatovo A.H, Danielle [Tohoku Univ., Dept. of Quantum Science and Energy Engineering, Sendai, Miyagi (Japan)

    2003-03-01

    From April 2001, neutron energy spectra and neutron dose were sequentially measured using 5'' -rem counter and {sup 3}He multi-moderator spectrometer (Boner boll) at Kawauchi-campus of Tohoku University. These data were collected about the relation between the dose level and the solar activities. (author)

  11. Magnetic correlations in oxides: Neutron diffraction and neutron depolarization study

    Indian Academy of Sciences (India)

    S M Yusuf

    2008-10-01

    We have studied magnetic correlations in several oxide materials that belong to colossal magnetoresistive, naturally occurring layered oxide showing low-dimensional magnetic ordering, solid oxide fuel cell interconnect materials, and magnetic nanoparticles using neutron diffraction and neutron depolarization techniques. In this paper, an overview of some of these results is given.

  12. Synovectomy by Neutron capture; Sinovectomia por captura de neutrones

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H.R.; Torres M, C. [Centro Regional de Estudios Nucleares, Universidad Autonoma de Zacatecas, C. Cipres 10, Fracc. La Penuela, 98000 Zacatecas (Mexico)

    1998-12-31

    The Synovectomy by Neutron capture has as purpose the treatment of the rheumatoid arthritis, illness which at present does not have a definitive curing. This therapy requires a neutron source for irradiating the articulation affected. The energy spectra and the intensity of these neutrons are fundamental since these neutrons induce nuclear reactions of capture with Boron-10 inside the articulation and the freely energy of these reactions is transferred at the productive tissue of synovial liquid, annihilating it. In this work it is presented the neutron spectra results obtained with moderator packings of spherical geometry which contains in its center a Pu{sup 239} Be source. The calculations were realized through Monte Carlo method. The moderators assayed were light water, heavy water base and the both combination of them. The spectra obtained, the average energy, the neutron total number by neutron emitted by source, the thermal neutron percentage and the dose equivalent allow us to suggest that the moderator packing more adequate is what has a light water thickness 0.5 cm (radius 2 cm) and 24.5 cm heavy water (radius 26.5 cm). (Author)

  13. Neutron flux mapping of Argonauta reactor in the new configuration of its reactor core; Mapeamento do fluxo de neutrons do reator Argonauta na nova configuracao do seu nucleo

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Maria Ines Silvani; Furieri, Rosanne Cefaly de Aranda Amado [Instituto de Engenharia Nuclear (IEN), Rio de Janeiro, RJ (Brazil)

    2000-07-01

    Whenever tasks involving the use of a nuclear reactor are carried out, e.g., radioisotope production, activation analysis, neutrongraphy, etc., it is necessary to know the magnitude of the associate neutron flux. The Argonauta reactor operating in Rio de Janeiro, at Instituto de Engenharia Nuclear - IEN/CNEN, was submitted to some modifications in its core, which made necessary to measure again its new neutronic characteristics, not only in the core itself, but also at the irradiation pads. In this type of research reactor, the neutrons are energetically distributed from values below 1 eV, to values reaching the magnitude of MeV. Therefore, depending on the kind of experiment to be conducted, it may become necessary to know the integrated neutron flux within certain energy ranges. In this work, the neutron flux for thermal and epithermal regions were determined by using the foil activation method. To accomplish this goal, two different techniques were applied. In the first technique {beta}-{gamma} gamma coincidence measurements were performed using a proportional 4{pi}{beta} gaseous detector and a NaI(Tl) scintillation detector, while in the second one, gamma spectroscopy was carried out using Hp-Ge and NaI(Tl) detectors. In both cases, the flux was computed using the FLUXO software, specially developed for this purpose. (author)

  14. Time-resolved neutron imaging at ANTARES cold neutron beamline

    CERN Document Server

    Tremsin, A S; Tittelmeier, K; Schillinger, B; Schulz, M; Lerche, M; Feller, W B

    2015-01-01

    In non-destructive evaluation with X-rays light elements embedded in dense, heavy (or high-Z) matrices show little contrast and their structural details can hardly be revealed. Neutron radiography, on the other hand, provides a solution for those cases, in particular for hydrogenous materials, owing to the large neutron scattering cross section of hydrogen and uncorrelated dependency of neutron cross section on the atomic number. The majority of neutron imaging experiments at the present time is conducted with static objects mainly due to the limited flux intensity of neutron beamline facilities and sometimes due to the limitations of the detectors. However, some applications require the studies of dynamic phenomena and can now be conducted at several high intensity beamlines such as the recently rebuilt ANTARES beam line at the FRM-II reactor. In this paper we demonstrate the capabilities of time resolved imaging for repetitive processes, where different phases of the process can be imaged simultaneously and...

  15. Application of imaging plate neutron detector to neutron radiography

    CERN Document Server

    Fujine, S; Kamata, M; Etoh, M

    1999-01-01

    As an imaging plate neutron detector (IP-ND) has been available for thermal neutron radiography (TNR) which has high resolution, high sensitivity and wide range, some basic characteristics of the IP-ND system were measured at the E-2 facility of the KUR. After basic performances of the IP were studied, images with high quality were obtained at a neutron fluence of 2 to 7x10 sup 8 n cm sup - sup 2. It was found that the IP-ND system with Gd sub 2 O sub 3 as a neutron converter material has a higher sensitivity to gamma-ray than that of a conventional film method. As a successful example, clear radiographs of the flat view for the fuel side plates with boron burnable poison were obtained. An application of the IP-ND system to neutron radiography (NR) is presented in this paper.

  16. TANGRA-Setup for the Investigation of Nuclear Fission Induced by 14.1 MeV Neutrons

    Science.gov (United States)

    Ruskov, I. N.; Kopatch, Yu. N.; Bystritsky, V. M.; Skoy, V. R.; Shvetsov, V. N.; Hambsch, F.-J.; Oberstedt, S.; Noy, R. Capote; Sedyshev, P. V.; Grozdanov, D. N.; Ivanov, I. Zh.; Aleksakhin, V. Yu.; Bogolubov, E. P.; Barmakov, Yu. N.; Khabarov, S. V.; Krasnoperov, A. V.; Krylov, A. R.; Obhođaš, J.; Pikelner, L. B.; Rapatskiy, V. L.; Rogachev, A. V.; Rogov, Yu. N.; Ryzhkov, V. I.; Sadovsky, A. B.; Salmin, R. A.; Sapozhnikov, M. G.; Slepnev, V. M.; Sudac, D.; Tarasov, O. G.; Valković, V.; Yurkov, D. I.; Zamyatin, N. I.; Zeynalov, Sh. S.; Zontikov, A. O.; Zubarev, E. V.

    The new experimental setup TANGRA (Tagged Neutrons & Gamma Rays), for the investigation of neutron induced nuclear reactions, e.g. (n,xn'), (n,xn'γ), (n,γ), (n,f), on a number of important isotopes for nuclear science and engineering (235,238U, 237Np, 239Pu, 244,245,248Cm) is under construction and being tested at the Frank Laboratory of Neutron Physics (FLNP) of the Joint Institute for Nuclear Research (JINR) in Dubna. The TANGRA setup consists of: a portable neutron generator ING-27, with a 64-pixel Si charge-particle detector incorporated into its vacuum chamber for registering of α-particles formed in the T(d, n)4He reaction, as a source of 14.1 MeV steady-state neutrons radiation with an intensity of ∼5x107n/s; a combined iron (Fe), borated polyethylene (BPE) and lead (Pb) compact shielding-collimator; a reconfigurable multi-detector (neutron plus gamma ray detecting system); a fast computer with 2 (x16 channels) PCI-E 100 MHz ADC cards for data acquisition and hard disk storage; Linux ROOT data acquisition, visualization and analysis software. The signals from the α-particle detector are used to 'tag' the neutrons with the coincident α-particles. Counting the coincidences between the α-particle and the reaction-product detectors in a 20ns time-interval improves the effect/background-ratio by a factor of ∼200 as well as the accuracy in the neutron flux determination, which decreases noticeably the overall experimental data uncertainty.

  17. APSTNG: Associated particle sealed-tube neutron generator studies for arms control. Final report on NN-20 Project ST220

    Energy Technology Data Exchange (ETDEWEB)

    Rhodes, E.; Dickerman, C.E.; Brunner, T.; Hess, A.; Tylinski, S.

    1994-12-01

    Argonne National Laboratory has performed research and development on the use of Associated Particle Sealed-Tube Neutron Generator (APSTNG) technology for treaty verification and non-proliferation applications, under funding from the DOE Office of Nonproliferation and National Security. Results indicate that this technology has significant potential for nondestructively detecting elemental compositions inside inspected objects or volumes. The final phase of this project was placement of an order for commercial procurement of an advanced sealed tube, with its high-voltage supply and control systems. Procurement specifications reflected lessons learned during the study. The APSTNG interrogates a volume with a continuous 14-MeV neutron flux. Each neutron is emitted coincident with an {open_quotes}associated{close_quotes} alpha-particle emitted in the opposite direction. Thus detection of an alpha-particle marks the emission of a neutron in a cone opposite to that defined by the alpha detector. Detection of a gamma ray coincident with the alpha indicates that the gamma was emitted from a neutron-induced reaction inside the neutron cone: the gamma spectra can be used to identify fissionable materials and many isotopes having an atomic number larger than that of boron. The differences in gamma-ray and alpha-particle detection times yield a coarse measurement of the distance along the cone axis from the APSTNG emitter to each region containing the identified nuclide. A position-sensitive alpha detector would permit construction of coarse three-dimensional images. The source and emission-detection systems can be located on the same side of the interrogated volume. The neutrons and gamma rays are highly penetrating. A relatively high signal-to-background ratio allows the use of a relatively small neutron source and conventional electronics.

  18. Measurement of the nearly free neutron structure function using spectator tagging in inelastic $^2$H(e, e'p)X scattering with CLAS

    CERN Document Server

    Tkachenko, S; Kuhn, S E; Zhang, J; Arrington, J; Bosted, P; Bültmann, S; Christy, M E; Fenker, H; Griffioen, K A; Kalantarians, N; Keppel, C E; Melnitchouk, W; Tvaskis, V; Adhikari, K P; Aghasyan, M; Amaryan, M J; Pereira, S Anefalos; Avakian, H; Ball, J; Baltzell, N A; Battaglieri, M; Bedlinskiy, I; Biselli, A S; Briscoe, W J; Brooks, W K; Burkert, V D; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Cole, P L; Contalbrigo, M; Cortes, O; Crede, V; D'Angelo, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Dodge, G E; Doughty, D; Dupre, R; Egiyan, H; Alaoui, A El; Fassi, L El; Elouadrhiri, L; Eugenio, P; Fedotov, G; Fleming, J A; Garillon, B; Gevorgyan, N; Ghandilyan, Y; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Golovatch, E; Gothe, R W; Guidal, M; Guo, L; Hafidi, K; Hakobyan, H; Hanretty, C; Harrison, N; Hattawy, M; Hicks, K; Ho, D; Holtrop, M; Hyde, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Jo, H S; Keller, D; Khandaker, M; Kim, A; Kim, W; Klein, A; Klein, F J; Koirala, S; Kubarovsky, V; Kuleshov, S V; Lenisa, P; Lewis, S; Livingston, K; Lu, H; MacCormick, M; MacGregor, I J D; Markov, N; Mayer, M; McKinnon, B; Mineeva, T; Mirazita, M; Mokeev, V; Montgomery, R A; Moutarde, H; Camacho, C Munoz; Nadel-Turonski, P; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Pappalardo, L L; Paremuzyan, R; Park, K; Pasyuk, E; Phillips, J J; Pisano, S; Pogorelko, O; Pozdniakov, S; Price, J W; Procureur, S; Protopopescu, D; Puckett, A J R; Rimal, D; Ripani, M; Rizzo, A; Rosner, G; Rossi, P; Roy, P; Sabatié, F; Schott, D; Schumacher, R A; Seder, E; Senderovich, I; Sharabian, Y G; Simonyan, A; Smith, G D; Sober, D I; Sokhan, D; Stepanyan, S; Stepanyan, S S; Strauch, S; Tang, W; Ungaro, M; Vlassov, A V; Voskanyan, H; Voutier, E; Walford, N K; Watts, D; Wei, X; Weinstein, L B; Wood, M H; Zana, L; Zonta, I

    2014-01-01

    Much less is known about neutron structure than that of the proton due to the absence of free neutron targets. Neutron information is usually extracted from data on nuclear targets such as deuterium, requiring corrections for nuclear binding and nucleon off-shell effects. These corrections are model dependent and have significant uncertainties, especially for large values of the Bjorken scaling variable x. The Barely Off-shell Nucleon Structure (BONuS) experiment at Jefferson Lab measured the inelastic electron deuteron scattering cross section, tagging spectator protons in coincidence with the scattered electrons. This method reduces nuclear binding uncertainties significantly and has allowed for the first time a (nearly) model independent extraction of the neutron structure function. A novel compact radial time projection chamber was built to detect protons with momentum between 70 and 150 MeV/c. For the extraction of the free neutron structure function $F_{2n}$, spectator protons at backward angle and with...

  19. Recovering the triple coincidence of non-pure positron emitters in preclinical PET

    Science.gov (United States)

    Lin, Hsin-Hon; Chuang, Keh-Shih; Chen, Szu-Yu; Jan, Meei-Ling

    2016-03-01

    Non-pure positron emitters, with their long half-lives, allow for the tracing of slow biochemical processes which cannot be adequately examined by the commonly used short-lived positron emitters. Most of these isotopes emit high-energy cascade gamma rays in addition to positron decay that can be detected and create a triple coincidence with annihilation photons. Triple coincidence is discarded in most scanners, however, the majority of the triple coincidence contains true photon pairs that can be recovered. In this study, we propose a strategy for recovering triple coincidence events to raise the sensitivity of PET imaging for non-pure positron emitters. To identify the true line of response (LOR) from a triple coincidence, a framework utilizing geometrical, energy and temporal information is proposed. The geometrical criterion is based on the assumption that the LOR with the largest radial offset among the three sub pairs of triple coincidences is least likely to be a true LOR. Then, a confidence time window is used to test the valid LOR among those within triple coincidence. Finally, a likelihood ratio discriminant rule based on the energy probability density distribution of cascade and annihilation gammas is established to identify the true LOR. An Inveon preclinical PET scanner was modeled with GATE (GEANT4 application for tomographic emission) Monte Carlo software. We evaluated the performance of the proposed method in terms of identification fraction, noise equivalent count rates (NECR), and image quality on various phantoms. With the inclusion of triple coincidence events using the proposed method, the NECR was found to increase from 11% to 26% and 19% to 29% for I-124 and Br-76, respectively, when 7.4-185 MBq of activity was used. Compared to the reconstructed images using double coincidence, this technique increased the SNR by 5.1-7.3% for I-124 and 9.3-10.3% for Br-76 within the activity range of 9.25-74 MBq, without compromising the spatial resolution or

  20. Small angle neutron scattering

    Directory of Open Access Journals (Sweden)

    Cousin Fabrice

    2015-01-01

    Full Text Available Small Angle Neutron Scattering (SANS is a technique that enables to probe the 3-D structure of materials on a typical size range lying from ∼ 1 nm up to ∼ a few 100 nm, the obtained information being statistically averaged on a sample whose volume is ∼ 1 cm3. This very rich technique enables to make a full structural characterization of a given object of nanometric dimensions (radius of gyration, shape, volume or mass, fractal dimension, specific area… through the determination of the form factor as well as the determination of the way objects are organized within in a continuous media, and therefore to describe interactions between them, through the determination of the structure factor. The specific properties of neutrons (possibility of tuning the scattering intensity by using the isotopic substitution, sensitivity to magnetism, negligible absorption, low energy of the incident neutrons make it particularly interesting in the fields of soft matter, biophysics, magnetic materials and metallurgy. In particular, the contrast variation methods allow to extract some informations that cannot be obtained by any other experimental techniques. This course is divided in two parts. The first one is devoted to the description of the principle of SANS: basics (formalism, coherent scattering/incoherent scattering, notion of elementary scatterer, form factor analysis (I(q→0, Guinier regime, intermediate regime, Porod regime, polydisperse system, structure factor analysis (2nd Virial coefficient, integral equations, characterization of aggregates, and contrast variation methods (how to create contrast in an homogeneous system, matching in ternary systems, extrapolation to zero concentration, Zero Averaged Contrast. It is illustrated by some representative examples. The second one describes the experimental aspects of SANS to guide user in its future experiments: description of SANS spectrometer, resolution of the spectrometer, optimization of

  1. New insight into the Auger decay process in O{sub 2}: The coincidence perspective

    Energy Technology Data Exchange (ETDEWEB)

    Arion, Tiberiu, E-mail: tiberiu.arion@cfel.de [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany); Institut fuer Experimentalphysik, Universitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Puettner, Ralph [Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin (Germany); Lupulescu, Cosmin [Technische Universitaet Berlin, Institut fuer Optik und atomare Physik, Hardenbergstr. 36, 10623 Berlin (Germany); Ovsyannikov, Ruslan [Helmholtz-Zentrum Berlin, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Foerstel, Marko [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany); Oehrwall, Gunnar [MAX-lab, Lund University, P.O. Box 118, SE-22100 Lund (Sweden); Lindblad, Andreas [Uppsala University, Department of Physics and Astronomy, Box 516, SE-751 20 Uppsala (Sweden); Ueda, Kiyoshi [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Svensson, Svante [Uppsala University, Department of Physics and Astronomy, Box 516, SE-751 20 Uppsala (Sweden); Bradshaw, Alex M. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany); Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany); Eberhardt, Wolfgang [Technische Universitaet Berlin, Institut fuer Optik und atomare Physik, Hardenbergstr. 36, 10623 Berlin (Germany); Center for Free-Electron Laser Science, Notkestrasse 85, 22607 Hamburg (Germany); and others

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer We developed a new experimental set-up for e,e-coincidence experiments. Black-Right-Pointing-Pointer New information on the potential curves of the final states in O{sub 2} has been extracted. Black-Right-Pointing-Pointer We observed new features, assigned to autoionization of neutral doubly excited states. -- Abstract: Photoelectron-Auger electron coincidence spectroscopy is a powerful tool for the investigation of Auger decay processes with different core-ionized intermediate states. In this paper we describe an investigation into the Auger decay of the O{sub 2} molecule, with the purpose of bringing new insight into the dynamics of the core hole decay mechanism. Using a novel experimental approach to measuring such coincidence spectra we report the highest resolution Auger spectrum of O{sub 2} recorded hitherto. In our approach, we have combined the advantages of these coincidence spectra with the high resolution and excellent signal-to-noise ratios of non-coincident Auger spectra and a state-of-the-art fit analysis. In this way we have derived information about the potential energy curves of the final states W {sup 3}{Delta}{sub u}, B {sup 3}{Pi}{sub g}, and B Prime {sup 3}{Sigma}{sub u}{sup -} and concluded that the corresponding Auger transitions are formed to a large part by strongly overlapping vibrational progressions. The present findings are compared to earlier results reported in the literature confirming some theoretical predictions.

  2. The Generalized Centroid Difference method for lifetime measurements via γ-γ coincidences using large fast-timing arrays

    Directory of Open Access Journals (Sweden)

    Régis J.-M.

    2015-01-01

    Full Text Available A novel method for direct electronic “fast-timing” lifetime measurements of nuclear excited states via γ-γ coincidences using an array equipped with N very fast high-resolution LaBr3(Ce scintillator detectors is presented. The generalized centroid difference method provides two independent “start” and “stop” time spectra obtained without any correction by a superposition of the N(N – 1/2 calibrated γ-γ time difference spectra of the N detector fast-timing system. The two fast-timing array time spectra correspond to a forward and reverse gating of a specific γ-γ cascade and the centroid difference as the time shift between the centroids of the two time spectra provides a picosecond-sensitive mirror-symmetric observable of the set-up. The energydependent mean prompt response difference between the start and stop events is calibrated and used as a single correction for lifetime determination. These combined fast-timing array mean γ-γ zero-time responses can be determined for 40 keV < Eγ < 1.4 MeV with a precision better than 10 ps using a 152Eu γ-ray source. The new method is described with examples of (n,γ and (n,f,γ experiments performed at the intense cold-neutron beam facility PF1B of the Institut Laue-Langevin in Grenoble, France, using 16 LaBr3(Ce detectors within the EXILL&FATIMA campaign in 2013. The results are discussed with respect to possible systematic errors induced by background contributions.

  3. Handbook of neutron optics

    CERN Document Server

    Utsuro, Masahiko

    2010-01-01

    Written by authors with an international reputation, acknowledged expertise and teaching experience, this is the most up-to-date resource on the field. The text is clearly structured throughout so as to be readily accessible, and begins by looking at scattering of a scalar particle by one-dimensional systems. The second section deals with the scattering of neutrons with spin in one-dimensional potentials, while the third treats dynamical diffraction in three-dimensional periodic media. The final two sections conclude with incoherent and small angle scattering, and some problems of quantum mech

  4. Advanced Neutron Spectrometer

    Science.gov (United States)

    Christl, Mark; Dobson, Chris; Norwood, Joseph; Kayatin, Matthew; Apple, Jeff; Gibson, Brian; Dietz, Kurt; Benson, Carl; Smith, Dennis; Howard, David; hide

    2013-01-01

    Energetic neutron measurements remain a challenge for space science investigations and radiation monitoring for human exploration beyond LEO. We are investigating a new composite scintillator design that uses Li6 glass scintillator embedded in a PVT block. A comparison between Li6 and Boron 10 loaded scintillators are being studied to assess the advantages and shortcomings of these two techniques. We present the details of the new Li6 design and results from the comparison of the B10 and Li6 techniques during exposures in a mixed radiation field produced by high energy protons interacting in a target material.

  5. On Magnetized Neutron Stars

    CERN Document Server

    Lopes, Luiz L

    2014-01-01

    In this work we review the formalism normally used in the literature about the effects of density-dependent magnetic fields on the properties of neutron stars, expose some ambiguities that arise and propose a way to solve the related problem. Our approach uses a different prescription for the calculation of the pressure based on the chaotic field formalism for the stress tensor and also a different way of introducing a variable magnetic field, which depends on the energy density rather than on the baryonic density.

  6. Innate immune memory in plants.

    Science.gov (United States)

    Reimer-Michalski, Eva-Maria; Conrath, Uwe

    2016-08-01

    The plant innate immune system comprises local and systemic immune responses. Systemic plant immunity develops after foliar infection by microbial pathogens, upon root colonization by certain microbes, or in response to physical injury. The systemic plant immune response to localized foliar infection is associated with elevated levels of pattern-recognition receptors, accumulation of dormant signaling enzymes, and alterations in chromatin state. Together, these systemic responses provide a memory to the initial infection by priming the remote leaves for enhanced defense and immunity to reinfection. The plant innate immune system thus builds immunological memory by utilizing mechanisms and components that are similar to those employed in the trained innate immune response of jawed vertebrates. Therefore, there seems to be conservation, or convergence, in the evolution of innate immune memory in plants and vertebrates.

  7. Nuclear lamina in plant cells

    Institute of Scientific and Technical Information of China (English)

    汪健; 杨澄; 翟中和

    1996-01-01

    By using selective extraction and diethylene glycol distearate (DGD) embedment and embedment-free electron microscopy, the nuclear lamina was demonstrated in carrot and Ginkgo male generative cells. Western blotting revealed that the nuclear lamina was composed of A-type and B-type lamins which contained at least 66-ku and 84-ku or 66-ku and 86-ku polypeptides, respectively. These lamin proteins were localized at the nudear periphery as shown by immunogold-labelling. In situ hybridization for light microscope and electron microscope showed that plant cells have the homologous sequences of animal lamin cDNA. The sorting site of lamin mRNA is mainly distributed in the cytoplasm near the nudear envelope. The data have verified that there indeed exists nudear lamina in plant cells.

  8. Heavy Metal Pumps in Plants

    Energy Technology Data Exchange (ETDEWEB)

    Harper, J.F.

    2000-10-01

    The long term goal of the funded research is to understand how heavy metals are taken up from the soil and translocated throughout the plant. The potential application of this research is to create plants with better heavy metal uptake systems and thereby improve the ability of these plants to help clean up toxic metals from soils. A rate limiting step is using plant for bioremediation is the normally poor capacity of plants to concentrate toxic metals. Our interest in metal ion transport systems includes those for essential mineral nutrients such as molybdenum, copper, iron, manganese, as well as toxic metals such as cerium, mercury, cesium, cadmium, arsenic and selenium. Understanding the pathways by which toxic metals accumulate in plants will enable the engineering of plants to exclude toxic metals and create healthier food sources, or to extract toxic metals from the soil as a strategy to clean up polluted lands and water.

  9. Mass measurements of neutron rich isotopes in the Fe region and electron capture processes in neutron star crusts

    Energy Technology Data Exchange (ETDEWEB)

    Estrade, Alfredo [National Superconducting Cyclotron Laboratory (NSCL); Matos, M. [Louisiana State University; Schatz, Hendrik [Michigan State University, East Lansing; Amthor, A. M. [National Superconducting Cyclotron Laboratory (NSCL); Beard, Mary [University of Notre Dame, IN; Brown, Edward [Michigan State University, East Lansing; Bazin, D. [National Superconducting Cyclotron Laboratory (NSCL); Becerril, A. [National Superconducting Cyclotron Laboratory (NSCL); Elliot, T [National Superconducting Cyclotron Laboratory (NSCL); Gade, A. [National Superconducting Cyclotron Laboratory (NSCL); Galaviz, D. [National Superconducting Cyclotron Laboratory (NSCL); Gupta, Sanjib [Indian Institute of Technology, Kanpur; Hix, William Raphael [ORNL; Lau, Rita [National Superconducting Cyclotron Laboratory (NSCL); Moeller, Peter [Los Alamos National Laboratory (LANL); Pereira, J. [National Superconducting Cyclotron Laboratory (NSCL); Portillo, M. [National Superconducting Cyclotron Laboratory (NSCL); Rogers, A. M. [National Superconducting Cyclotron Laboratory (NSCL); Shapira, Dan [ORNL; Smith, E. [Ohio State University; Stolz, A. [Michigan State University, East Lansing; Wallace, M. [Los Alamos National Laboratory (LANL); Wiescher, Michael [University of Notre Dame, IN

    2010-01-01

    Experimental knowledge of nuclear masses of exotic nuclei is important for understanding nu- clear structure far from the valley of -stability, and as a direct input into astrophysical models. Electron capture processes in the crust of accreting neutron stars have been proposed as a heat source that can affect the thermal structure of the star. Nuclear masses of very neutron-rich nu- clides are necessary inputs to model the electron capture process. The time-of-flight (TOF) mass measurement technique allows measurements on very short-lived nuclei. It has been effectively applied using the fast fragment beams produced at the National Superconducting Cyclotron Lab (NSCL) to reach masses very far from stability. Measurements were performed for neutron-rich isotopes in the region of the N=32 and N=40 subshells, which coincides with the mass range of carbon superburst ashes. We discuss reaction network calculations performed to investigate the impact of our new measurements and to compare the effect of using different global mass models in the calculations. It is observed that the process is sensitive to the differences in the odd-even mass staggering predicted by the mass models, and our new result for 66Mn has a significant impact on the distribution of heat sources in the crust.

  10. High power neutron production targets

    Energy Technology Data Exchange (ETDEWEB)

    Wender, S. [Los Alamos National Lab., NM (United States)

    1996-06-01

    The author describes issues of concern in the design of targets and associated systems for high power neutron production facilities. The facilities include uses for neutron scattering, accelerator driven transmutation, accelerator production of tritium, short pulse spallation sources, and long pulse spallation sources. Each of these applications requires a source with different design needs and consequently different implementation in practise.

  11. Neutron imaging of radioactive sources

    Science.gov (United States)

    Hameed, F.; Karimzadeh, S.; Zawisky, M.

    2008-08-01

    Isotopic neutron sources have been available for more than six decades. At the Atomic Institute in Vienna, operating a 250 kW TRIGA reactor, different neutron sources are in use for instrument calibration and fast neutron applications but we have only little information about their construction and densities. The knowledge of source design is essential for a complete MCNP5 modeling of the experiments. Neutron radiography (NR) and neutron tomography (NT) are the best choices for the non-destructive inspection of the source geometry and homogeneity. From the transmission analysis we gain information about the shielding components and the densities of the radio-isotopes in the cores. Three neutron sources, based on (alpha, n) reaction, have been investigated, two 239PuBe sources and one 241AmBe source. In the NR images the internal structure was clearly revealed using high-resolving scintillation and imaging plate detectors. In one source tablet a crack was detected which causes asymmetric neutron emission. The tomography inspection of strong absorbing materials is more challenging due to the low beam intensity of 1.3x105 n/cm2s at our NT instrument, and due to the beam hardening effect which requires an extension of reconstruction software. The tomographic inspection of a PuBe neutron source and appropriate measures for background and beam hardening correction are presented.

  12. Physics of Neutron Star Crusts

    Directory of Open Access Journals (Sweden)

    Chamel Nicolas

    2008-12-01

    Full Text Available The physics of neutron star crusts is vast, involving many different research fields, from nuclear and condensed matter physics to general relativity. This review summarizes the progress, which has been achieved over the last few years, in modeling neutron star crusts, both at the microscopic and macroscopic levels. The confrontation of these theoretical models with observations is also briefly discussed.

  13. Axion emission from neutron stars

    Science.gov (United States)

    Iwamoto, N.

    1984-01-01

    It is shown that axion emission from neutron stars is the dominant energy-loss mechanism for a range of values of the Peccei-Quinn symmetry-breaking scale (F) not excluded by previous constraints. This gives the possibility of obtaining a better bound on F from measurements of surface temperature of neutron stars.

  14. Neutrons for technology and science

    Energy Technology Data Exchange (ETDEWEB)

    Aeppli, G.

    1995-10-01

    We reviewed recent work using neutrons generated at nuclear reactors an accelerator-based spallation sources. Provided that large new sources become available, neutron beams will continue to have as great an impact on technology and science as in the past.

  15. Neutron and P, T symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, Y. [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

    1996-05-01

    New ideas for experiments to improve the T-violation limit by a factor of 10 to 100 is discussed for a intensive spallation neutron source. The methods to improve the limit of the right-handed current and the neutron lifetime are also discussed. (author)

  16. Neutron Absorption in Geological Material

    Science.gov (United States)

    Løvhøiden, G.; Andersen, E.

    1990-01-01

    Thermal neutron absorption cross section of geological samples is determined with the steady state neutron source method. Cross section measurements of North Sea sediments demonstrate that also materials with high contents of clay minerals may be investigated with the steady state method.

  17. Magnetic Fields of Neutron Stars

    Indian Academy of Sciences (India)

    Sushan Konar

    2017-09-01

    This article briefly reviews our current understanding of the evolution of magnetic fields in neutron stars, which basically defines the evolutionary pathways between different observational classes of neutron stars. The emphasis here is on the evolution in binary systems and the newly emergent classes of millisecond pulsars.

  18. Measurement of natural background neutron

    CERN Document Server

    Li Jain, Ping; Tang Jin Hua; Tang, E S; Xie Yan Fong

    1982-01-01

    A high sensitive neutron monitor is described. It has an approximate counting rate of 20 cpm for natural background neutrons. The pulse amplitude resolution, sensitivity and direction dependence of the monitor were determined. This monitor has been used for natural background measurement in Beijing area. The yearly average dose is given and compared with the results of KEK and CERN.

  19. Investigation of Isfahan miniature neutron source reactor (MNSR) for boron neutron capture therapy by MCNP simulation

    OpenAIRE

    S. Z. Kalantari; H Tavakoli; Nami, M.

    2015-01-01

    One of the important neutron sources for Boron Neutron Capture Therapy (BNCT) is a nuclear reactor. It needs a high flux of epithermal neutrons. The optimum conditions of the neutron spectra for BNCT are provided by the International Atomic Energy Agency (IAEA). In this paper, Miniature Neutron Source Reactor (MNSR) as a neutron source for BNCT was investigated. For this purpose, we designed a Beam Shaping Assembly (BSA) for the reactor and the neutron transport from the core of the reactor t...

  20. First results of micro-neutron tomography by use of a focussing neutron lens

    CERN Document Server

    Masschaele, B; Cauwels, P; Dierick, M; Jolie, J; Mondelaers, W

    2001-01-01

    Since the appearance of high flux neutron beams, scientists experimented with neutron radiography. This high beam flux combined with modern neutron to visible light converters leads to the possibility of performing fast neutron micro-tomography. The first results of cold neutron tomography with a neutron lens are presented in this article. Samples are rotated in the beam and the projections are recorded with a neutron camera. The 3D reconstruction is performed with cone beam reconstruction software.