Science.gov

Sample records for neutron signal transfer

  1. Neutron behavior, reactor control, and reactor heat transfer. Volume four

    SciTech Connect

    Not Available

    1986-01-01

    Volume four covers neutron behavior (neutron absorption, how big are nuclei, neutron slowing down, neutron losses, the self-sustaining reactor), reactor control (what is controlled in a reactor, controlling neutron population, is it easy to control a reactor, range of reactor control, what happens when the fuel burns up, controlling a PWR, controlling a BWR, inherent safety of reactors), and reactor heat transfer (heat generation in a nuclear reactor, how is heat removed from a reactor core, heat transfer rate, heat transfer properties of the reactor coolant).

  2. Coherent and semi-coherent neutron transfer reactions

    SciTech Connect

    Hagelstein, P.L.

    1992-01-01

    Neutron transfer reactions are proposed to account for anomalies reported in Pons-Fleischmann experiments. The prototypical reaction involves the transfer of a neutron (mediated by low frequency electric or magnetic fields) from a donor nucleus to virtual continuum states, followed by the capture of the virtual neutron by an acceptor nucleus. In this work we summarize basic principles, recent results and the ultimate goals of the theoretical effort.

  3. Coherent and semi-coherent neutron transfer reactions

    SciTech Connect

    Hagelstein, P.L.

    1992-12-31

    Neutron transfer reactions are proposed to account for anomalies reported in Pons-Fleischmann experiments. The prototypical reaction involves the transfer of a neutron (mediated by low frequency electric or magnetic fields) from a donor nucleus to virtual continuum states, followed by the capture of the virtual neutron by an acceptor nucleus. In this work we summarize basic principles, recent results and the ultimate goals of the theoretical effort.

  4. Neutron Transfer Reactions: Surrogates for Neutron Capture for Basic and Applied Nuclear Science

    NASA Astrophysics Data System (ADS)

    Cizewski, J. A.; Jones, K. L.; Kozub, R. L.; Pain, S. D.; Peters, W. A.; Adekola, A.; Allen, J.; Bardayan, D. W.; Becker, J. A.; Blackmon, J. C.; Chae, K. Y.; Chipps, K. A.; Erikson, L.; Gaddis, A.; Harlin, C.; Hatarik, R.; Howard, J.; Jandel, M.; Johnson, M. S.; Kapler, R.; Krolas, W.; Liang, F.; Livesay, R. J.; Ma, Z.; Matei, C.; Matthews, C.; Moazen, B.; Nesaraja, C. D.; O'Malley, P.; Patterson, N.; Paulauskas, S. V.; Pelham, T.; Pittman, S. T.; Radford, D.; Rogers, J.; Schmitt, K.; Shapira, D.; Shriner, J. F.; Sissom, D. J.; Smith, M. S.; Swan, T.; Thomas, J. S.; Vieira, D. J.; Wilhelmy, J. B.; Wilson, G. L.

    2009-03-01

    Neutron capture reactions on unstable nuclei are important for both basic and applied nuclear science. A program has been developed at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory to study single-neutron transfer (d,p) reactions with rare isotope beams to provide information on neutron-induced reactions on unstable nuclei. Results from (d,p) studies on 130,132Sn, 134Te and 75As are discussed.

  5. Neutron transfer reactions: Surrogates for neutron capture for basic and applied nuclear science

    SciTech Connect

    Cizewski, J. A.; Jones, K. L.; Kozub, R. L.; Pain, Steven D; Peters, W. A.; Adekola, Aderemi S; Allen, J.; Bardayan, Daniel W; Becker, J.; Blackmon, Jeff C; Chae, K. Y.; Chipps, K.; Erikson, Luke; Gaddis, A. L.; Harlin, Christopher W; Hatarik, Robert; Howard, Joshua A; Jandel, M.; Johnson, Micah; Kapler, R.; Krolas, W.; Liang, J Felix; Livesay, Jake; Ma, Zhanwen; Matei, Catalin; Matthews, C.; Moazen, Brian; Nesaraja, Caroline D; O'Malley, Patrick; Patterson, N. P.; Paulauskas, Stanley; Pelham, T.; Pittman, S. T.; Radford, David C; Rogers, J.; Schmitt, Kyle; Shapira, Dan; ShrinerJr., J. F.; Sissom, D. J.; Smith, Michael Scott; Swan, T. P.; Thomas, J. S.; Vieira, D. J.; Wilhelmy, J. B.; Wilson, Gemma L

    2009-04-01

    Neutron capture reactions on unstable nuclei are important for both basic and applied nuclear science. A program has been developed at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory to study single-neutron transfer (d,p) reactions with rare isotope beams to provide information on neutron-induced reactions on unstable nuclei. Results from (d,p) studies on {sup 130,132}Sn, {sup 134}Te and {sup 75}As are discussed.

  6. Multi-neutron transfer reactions at sub-barrier energies.

    SciTech Connect

    Rehm, K. E.

    1998-01-20

    The optimum conditions for multi-neutron transfer have been studied in the system {sup 58}Ni + {sup 124}Sn at bombarding energies at and below the Coulomb barrier. The experiments were performed in inverse kinematics with a {sup 124}Sn beam bombarding a {sup 58}Ni target. The particles were identified with respect to mass and Z in the split-pole spectrograph with a hybrid focal plane detector with mass and Z-resolutions of A/{Delta}A = 150 and Z/{Delta}Z = 70. At all energies the transfer of up to 6 neutrons was observed. The yields for these transfer reactions are found to decrease by about a factor of four for each transferred neutron.

  7. Neutron transfer measurements on neutron-rich N=82 nuclei

    SciTech Connect

    Pain, Steven D; Jones, K. L.; Bardayan, Daniel W; Blackmon, Jeff C; Chae, K. Y.; Chipps, K.; Cizewski, J. A.; Hatarik, Robert; Kapler, R.; Kozub, R. L.; Liang, J Felix; Moazen, Brian; Nesaraja, Caroline D; Shapira, Dan; ShrinerJr., J. F.; Smith, Michael Scott

    2009-01-01

    Calculations of r-process nucleosynthesis rely significantly on nuclear structure models as input, which are not well tested in the neutron-rich regime, due to the paucity of experimental data on the majority of these nuclei. High quality radioactive beams have recently made possible the measurement of (d,p) reactions on unstable nuclei in inverse kinematics, which can yield information on the development of single-neutron structure away from stability in close proximity to suggested r-process paths. The Oak Ridge Rutgers University Barrel Array (ORRUBA) has been developed for the measurement of such reactions. An early partial implementation of ORRUBA has been utilized to measure the {sup 132}Sn(d,p){sup 133}Sn and {sup 134}Te(d,p){sup 135}Te reactions for the first time.

  8. Ionization signals from diamond detectors in fast-neutron fields

    NASA Astrophysics Data System (ADS)

    Weiss, C.; Frais-Kölbl, H.; Griesmayer, E.; Kavrigin, P.

    2016-09-01

    In this paper we introduce a novel analysis technique for measurements with single-crystal chemical vapor deposition (sCVD) diamond detectors in fast-neutron fields. This method exploits the unique electronic property of sCVD diamond sensors that the signal shape of the detector current is directly proportional to the initial ionization profile. In fast-neutron fields the diamond sensor acts simultaneously as target and sensor. The interaction of neutrons with the stable isotopes 12 C and 13 C is of interest for fast-neutron diagnostics. The measured signal shapes of detector current pulses are used to identify individual types of interactions in the diamond with the goal to select neutron-induced reactions in the diamond and to suppress neutron-induced background reactions as well as γ-background. The method is verified with experimental data from a measurement in a 14.3 MeV neutron beam at JRC-IRMM, Geel/Belgium, where the 13C(n, α)10Be reaction was successfully extracted from the dominating background of recoil protons and γ-rays and the energy resolution of the 12C(n, α)9Be reaction was substantially improved. The presented analysis technique is especially relevant for diagnostics in harsh radiation environments, like fission and fusion reactors. It allows to extract the neutron spectrum from the background, and is particularly applicable to neutron flux monitoring and neutron spectroscopy.

  9. Information transfer for small-amplitude signals

    NASA Astrophysics Data System (ADS)

    Kostal, Lubomir; Lansky, Petr

    2010-05-01

    We study the optimality conditions of information transfer in systems with memory in the low signal-to-noise ratio regime of vanishing input amplitude. We find that the optimal mutual information is represented by a maximum variance of the signal time course, with correlation structure determined by the Fisher information matrix. We provide illustration of the method on a simple biologically inspired model of electrosensory neuron. Our general results apply also to the study of information transfer in single neurons subject to weak stimulation, with implications to the problem of coding efficiency in biological systems.

  10. Transfer of Predictive Signals Across Saccades

    PubMed Central

    Vetter, Petra; Edwards, Grace; Muckli, Lars

    2012-01-01

    Predicting visual information facilitates efficient processing of visual signals. Higher visual areas can support the processing of incoming visual information by generating predictive models that are fed back to lower visual areas. Functional brain imaging has previously shown that predictions interact with visual input already at the level of the primary visual cortex (V1; Harrison et al., 2007; Alink et al., 2010). Given that fixation changes up to four times a second in natural viewing conditions, cortical predictions are effective in V1 only if they are fed back in time for the processing of the next stimulus and at the corresponding new retinotopic position. Here, we tested whether spatio-temporal predictions are updated before, during, or shortly after an inter-hemifield saccade is executed, and thus, whether the predictive signal is transferred swiftly across hemifields. Using an apparent motion illusion, we induced an internal motion model that is known to produce a spatio-temporal prediction signal along the apparent motion trace in V1 (Muckli et al., 2005; Alink et al., 2010). We presented participants with both visually predictable and unpredictable targets on the apparent motion trace. During the task, participants saccaded across the illusion whilst detecting the target. As found previously, predictable stimuli were detected more frequently than unpredictable stimuli. Furthermore, we found that the detection advantage of predictable targets is detectable as early as 50–100 ms after saccade offset. This result demonstrates the rapid nature of the transfer of a spatio-temporally precise predictive signal across hemifields, in a paradigm previously shown to modulate V1. PMID:22701107

  11. Intercellular transfer of apoptotic signals via electrofusion

    SciTech Connect

    Park, Jin Suk; Lee, Wilson; McCulloch, Christopher A.

    2012-05-01

    We determined whether cells that are induced to undergo anoikis by matrix detachment can initiate apoptosis in healthy cells following electroporation-induced fusion. Separate populations of MDCK cells undergoing anoikis and stained with FITC-annexin or viable MDCK cells that were labeled with spectrally discrete fluorescent beads were electroporated. Cells were analyzed by flow cytometry for enumeration of viable cells with beads, apoptotic cells or fused cells. Electroporation promoted a 49-fold increase of the percentage of viable cells that had fused with apoptotic cells. Apoptotic cell-viable cell fusions were 8-fold more likely to not attach to cell culture plastic and 2.3-fold less likely to proliferate after 24 hr incubation than viable cell fusion controls. These data demonstrate that apoptotic signals can be transferred between cells by electrofusion, possibly suggesting a novel investigative approach for optimizing targeted cell deletion in cancer treatment.

  12. Observation of the one- to six-neutron transfer reactions at sub-barrier energies

    SciTech Connect

    Jiang, C.L.; Rehm, K.E.; Gehring, J.

    1995-08-01

    It was suggested many years ago that when two heavy nuclei are in contact during a grazing collision, the transfer of several correlated neutron-pairs could occur. Despite considerable experimental effort, however, so far only cross sections for up to four-neutron transfers have been uniquely identified. The main difficulties in the study of multi-neutron transfer reactions are the small cross sections encountered at incident energies close to the barrier, and various experimental uncertainties which can complicate the analysis of these reactions. We have for the first time found evidence for multi-neutron transfer reactions covering the full sequence from one- to six-neutron transfer reactions at sub-barrier energies in the system {sup 58}Ni + {sup 100}Mo.

  13. Determination of fission neutron transmission through waste matrix material using neutron signal correlation from active assay of {sup 239}Pu

    SciTech Connect

    Hollas, C.L.; Arnone, G.; Brunson, G.; Coop, K.

    1996-09-01

    The accuracy of TRU (transuranic) waste assay using the differential die-away technique depends upon significant corrections to compensate for the effects of the matrix material in which the TRU waste is located. The authors have used a new instrument, the Combined Thermal/Epithermal Neutron (CTEN) instrument for the assay of TRU waste, to develop methods to improve the accuracy of these corrections. Neutrons from a pulsed 14-MeV neutron generator are moderated in the walls of the CTEN cavity and induce fission in the TRU material. The prompt neutrons from these fission events are detected in cadmium-wrapped {sup 3}He neutron detectors. They report new methods of data acquisition and analysis to extract correlation in the neutron signals resulting form fission during active interrogation. They use the correlation information in conjunction with the total number of neutrons to determine the fraction of fission neutrons transmitted through the matrix material into the {sup 3}He detectors. This determination allows them to cleanly separate the matrix effects into two processes: matrix modification upon the neutron interrogating flux and matrix modification upon the fraction of fission neutrons transmitted to the neutron detectors. This transmission information is also directly applied in a neutron multiplicity analysis in the passive assay of {sup 240}Pu.

  14. Fission signal detection using helium-4 gas fast neutron scintillation detectors

    SciTech Connect

    Lewis, J. M. Kelley, R. P.; Jordan, K. A.; Murer, D.

    2014-07-07

    We demonstrate the unambiguous detection of the fission neutron signal produced in natural uranium during active neutron interrogation using a deuterium-deuterium fusion neutron generator and a high pressure {sup 4}He gas fast neutron scintillation detector. The energy deposition by individual neutrons is quantified, and energy discrimination is used to differentiate the induced fission neutrons from the mono-energetic interrogation neutrons. The detector can discriminate between different incident neutron energies using pulse height discrimination of the slow scintillation component of the elastic scattering interaction between a neutron and the {sup 4}He atom. Energy histograms resulting from this data show the buildup of a detected fission neutron signal at higher energies. The detector is shown here to detect a unique fission neutron signal from a natural uranium sample during active interrogation with a (d, d) neutron generator. This signal path has a direct application to the detection of shielded nuclear material in cargo and air containers. It allows for continuous interrogation and detection while greatly minimizing the potential for false alarms.

  15. Development of the prototype pneumatic transfer system for ITER neutron activation system.

    PubMed

    Cheon, M S; Seon, C R; Pak, S; Lee, H G; Bertalot, L

    2012-10-01

    The neutron activation system (NAS) measures neutron fluence at the first wall and the total neutron flux from the ITER plasma, providing evaluation of the fusion power for all operational phases. The pneumatic transfer system (PTS) is one of the key components of the NAS for the proper operation of the system, playing a role of transferring encapsulated samples between the capsule loading machine, irradiation stations, counting stations, and disposal bin. For the validation and the optimization of the design, a prototype of the PTS was developed and capsule transfer tests were performed with the developed system.

  16. Delayed neutron signal characterization in a fast reactor

    SciTech Connect

    Gross, K.C.; Strain, R.V.

    1980-01-01

    Experimental and analytical techniques have been developed for delayed neutron (DN) signal analysis and characterization that can provide diagnostic information to augment data from cover-gas analyses in the detection and identification of breached elements in an LMFBR. Eleven flow reduction tests have been run in EBR-II to provide base data support for predicting DN signal characteristics during exposed fuel operation. Results from the tests demonstrate the feasibility and practicability of response-analysis techniques for determining the transit time, T/sub tr/, for DN emitters traveling from the core to the detector, and the isotopic holdup time, T/sub h/, of DN precursors in the fuel element. T/sub tr/ has been found to vary with the relative grid location of the DN source, and T/sub h/ is affected by the form of fuel exposed to the coolant as well as the condition of the breach site. These parameters are incorporated into a mathematical formulism that enables one to compute for any exposed-fuel test an equivalent recoil area. This concept provides a basis for comparison of different run-beyond-cladding-breach tests in fast reactors.

  17. Observation of the one- to six-neutron transfer reactions at sub- barrier energies

    SciTech Connect

    Jiang, C.L.; Rehm, K.E.; Gehring, J.; Glagola, B.; Kutschera, W.; Rhein, M.; Wuosmaa, A.H.

    1994-04-01

    An unambiguous determination of the cross sections for the one- to six neutron transfer reactions has been made in the system {sup 58}Ni + {sup 100}Mo. The cross sections for multi-neutron transfer processes show an exponential falloff in agreement with recent theoretical calculations. Upper limits for the absolute yields to the ground states have been extracted which are smaller by a factor of ten as compared to theoretical predictions.

  18. Nonlocal Quantum Information Transfer Without Superluminal Signalling and Communication

    NASA Astrophysics Data System (ADS)

    Walleczek, Jan; Grössing, Gerhard

    2016-09-01

    It is a frequent assumption that—via superluminal information transfers—superluminal signals capable of enabling communication are necessarily exchanged in any quantum theory that posits hidden superluminal influences. However, does the presence of hidden superluminal influences automatically imply superluminal signalling and communication? The non-signalling theorem mediates the apparent conflict between quantum mechanics and the theory of special relativity. However, as a `no-go' theorem there exist two opposing interpretations of the non-signalling constraint: foundational and operational. Concerning Bell's theorem, we argue that Bell employed both interpretations, and that he finally adopted the operational position which is associated often with ontological quantum theory, e.g., de Broglie-Bohm theory. This position we refer to as "effective non-signalling". By contrast, associated with orthodox quantum mechanics is the foundational position referred to here as "axiomatic non-signalling". In search of a decisive communication-theoretic criterion for differentiating between "axiomatic" and "effective" non-signalling, we employ the operational framework offered by Shannon's mathematical theory of communication, whereby we distinguish between Shannon signals and non-Shannon signals. We find that an effective non-signalling theorem represents two sub-theorems: (1) Non-transfer-control (NTC) theorem, and (2) Non-signification-control (NSC) theorem. Employing NTC and NSC theorems, we report that effective, instead of axiomatic, non-signalling is entirely sufficient for prohibiting nonlocal communication. Effective non-signalling prevents the instantaneous, i.e., superluminal, transfer of message-encoded information through the controlled use—by a sender-receiver pair —of informationally-correlated detection events, e.g., in EPR-type experiments. An effective non-signalling theorem allows for nonlocal quantum information transfer yet—at the same time

  19. Nonlocal Quantum Information Transfer Without Superluminal Signalling and Communication

    NASA Astrophysics Data System (ADS)

    Walleczek, Jan; Grössing, Gerhard

    2016-01-01

    It is a frequent assumption that—via superluminal information transfers—superluminal signals capable of enabling communication are necessarily exchanged in any quantum theory that posits hidden superluminal influences. However, does the presence of hidden superluminal influences automatically imply superluminal signalling and communication? The non-signalling theorem mediates the apparent conflict between quantum mechanics and the theory of special relativity. However, as a `no-go' theorem there exist two opposing interpretations of the non-signalling constraint: foundational and operational. Concerning Bell's theorem, we argue that Bell employed both interpretations, and that he finally adopted the operational position which is associated often with ontological quantum theory, e.g., de Broglie-Bohm theory. This position we refer to as "effective non-signalling". By contrast, associated with orthodox quantum mechanics is the foundational position referred to here as "axiomatic non-signalling". In search of a decisive communication-theoretic criterion for differentiating between "axiomatic" and "effective" non-signalling, we employ the operational framework offered by Shannon's mathematical theory of communication, whereby we distinguish between Shannon signals and non-Shannon signals. We find that an effective non-signalling theorem represents two sub-theorems: (1) Non-transfer-control (NTC) theorem, and (2) Non-signification-control (NSC) theorem. Employing NTC and NSC theorems, we report that effective, instead of axiomatic, non-signalling is entirely sufficient for prohibiting nonlocal communication. Effective non-signalling prevents the instantaneous, i.e., superluminal, transfer of message-encoded information through the controlled use—by a sender-receiver pair —of informationally-correlated detection events, e.g., in EPR-type experiments. An effective non-signalling theorem allows for nonlocal quantum information transfer yet—at the same time

  20. Improved neutron-gamma discrimination for a 6Li-glass neutron detector using digital signal analysis methods

    DOE PAGESBeta

    Wang, Cai -Lin; Riedel, Richard A.

    2016-01-14

    A 6Li-glass scintillator (GS20) based neutron Anger camera was developed for time-of-flight single-crystal diffraction instruments at SNS. Traditional pulse-height analysis (PHA) for neutron-gamma discrimination (NGD) resulted in the neutron-gamma efficiency ratio (defined as NGD ratio) on the order of 104. The NGD ratios of Anger cameras need to be improved for broader applications including neutron reflectometers. For this purpose, five digital signal analysis methods of individual waveforms from PMTs were proposed using: i). pulse-amplitude histogram; ii). power spectrum analysis combined with the maximum pulse amplitude; iii). two event parameters (a1, b0) obtained from Wiener filter; iv). an effective amplitude (m)more » obtained from an adaptive least-mean-square (LMS) filter; and v). a cross-correlation (CC) coefficient between an individual waveform and a reference. The NGD ratios can be 1-102 times those from traditional PHA method. A brighter scintillator GS2 has better NGD ratio than GS20, but lower neutron detection efficiency. The ultimate NGD ratio is related to the ambient, high-energy background events. Moreover, our results indicate the NGD capability of neutron Anger cameras can be improved using digital signal analysis methods and brighter neutron scintillators.« less

  1. Theory of Radiation Transfer in Neutron Star Atmospheres

    NASA Technical Reports Server (NTRS)

    Zavlin, Vyacheslav

    2006-01-01

    The possibility for direct investigation of thermal emission from isolated neutron stars opened about a quarter of century ago with the launch of the first X-ray observatories Einstein and EXOSAT stimulated developing models of the neutron star surface radiation which began at the end of 80's. Confronting observational data with theoretical models of thermal emission allows one to infer the surface temperatures, magnetic fields, chemical composition, and neutron star masses and radii. This information, supplemented with the model equations of state and neutron star cooling models, provides an opportunity to understand the fundamental properties of the superdense matter in the stars' interiors. Almost all available models are based on the assumption that thermal radiation emitted by a neutron star is formed in the superficial star's layers--atmosphere. The neutron star atmospheres are very different from those of usual stars due to the immense gravity and huge magnetic fields. In this presentation we review the current status of the neutron star atmosphere modeling, present most important results, discuss problems and possible future developments.

  2. Neutron Transfer Reactions on Neutron-Rich N=50 and N=82 Nuclei Near the r-Process Path

    SciTech Connect

    Cizewski, J. A.; Jones, K. L.; Kozub, R. L.; Pain, S. D.; Thomas, J. S.; Arbanas, Goran; Adekola, Aderemi S; Bardayan, Daniel W; Blackmon, Jeff C; Chae, K. Y.; Chipps, K.; Dean, David Jarvis; Erikson, Luke; Gaddis, A. L.; Harlin, Christopher W; Hatarik, Robert; Howard, Joshua A; Johnson, Micah; Kapler, R.; Krolas, W.; Liang, J Felix; Livesay, Jake; Ma, Zhanwen; Matei, Catalin; Moazen, Brian; Nesaraja, Caroline D; O'Malley, Patrick; Paulauskas, Stanley V; Shapira, Dan; ShrinerJr., J. F.; Sissom, D. J.; Smith, Michael Scott; Swan, T. P.; Wilson, Gemma L

    2009-01-01

    Neutron transfer (d,p) reaction studies on the N = 50 isotones, 82Ge and 84Se, and A{approx}130 nuclei, 130,132Sn and 134Te, have been measured. Direct neutron capture cross sections for 82Ge and 84Se (n,?) have been calculated and are combined with Hauser-Feshbach expectations to estimate total (n,?) cross sections. The A{approx}130 studies used an early implementation of the ORRUBA array of position-sensitive silicon strip detectors for reaction proton measurements. Preliminary excitation energy and angular distribution results from the A{approx}130 measurements are reported.

  3. Improved neutron-gamma discrimination for a (6)Li-glass neutron detector using digital signal analysis methods.

    PubMed

    Wang, C L; Riedel, R A

    2016-01-01

    A (6)Li-glass scintillator (GS20) based neutron Anger camera was developed for time-of-flight single-crystal diffraction instruments at Spallation Neutron Source. Traditional Pulse-Height Analysis (PHA) for Neutron-Gamma Discrimination (NGD) resulted in the neutron-gamma efficiency ratio (defined as NGD ratio) on the order of 10(4). The NGD ratios of Anger cameras need to be improved for broader applications including neutron reflectometers. For this purpose, six digital signal analysis methods of individual waveforms acquired from photomultiplier tubes were proposed using (i) charge integration, (ii) pulse-amplitude histograms, (iii) power spectrum analysis combined with the maximum pulse-amplitude, (iv) two event parameters (a1, b0) obtained from a Wiener filter, (v) an effective amplitude (m) obtained from an adaptive least-mean-square filter, and (vi) a cross-correlation coefficient between individual and reference waveforms. The NGD ratios are about 70 times those from the traditional PHA method. Our results indicate the NGD capabilities of neutron Anger cameras based on GS20 scintillators can be significantly improved with digital signal analysis methods. PMID:26827314

  4. Improved neutron-gamma discrimination for a 6Li-glass neutron detector using digital signal analysis methods

    NASA Astrophysics Data System (ADS)

    Wang, C. L.; Riedel, R. A.

    2016-01-01

    A 6Li-glass scintillator (GS20) based neutron Anger camera was developed for time-of-flight single-crystal diffraction instruments at Spallation Neutron Source. Traditional Pulse-Height Analysis (PHA) for Neutron-Gamma Discrimination (NGD) resulted in the neutron-gamma efficiency ratio (defined as NGD ratio) on the order of 104. The NGD ratios of Anger cameras need to be improved for broader applications including neutron reflectometers. For this purpose, six digital signal analysis methods of individual waveforms acquired from photomultiplier tubes were proposed using (i) charge integration, (ii) pulse-amplitude histograms, (iii) power spectrum analysis combined with the maximum pulse-amplitude, (iv) two event parameters (a1, b0) obtained from a Wiener filter, (v) an effective amplitude (m) obtained from an adaptive least-mean-square filter, and (vi) a cross-correlation coefficient between individual and reference waveforms. The NGD ratios are about 70 times those from the traditional PHA method. Our results indicate the NGD capabilities of neutron Anger cameras based on GS20 scintillators can be significantly improved with digital signal analysis methods.

  5. Flow-dependent mass transfer may trigger endothelial signaling cascades.

    PubMed

    Vandrangi, Prashanthi; Sosa, Martha; Shyy, John Y-J; Rodgers, Victor G J

    2012-01-01

    It is well known that fluid mechanical forces directly impact endothelial signaling pathways. But while this general observation is clear, less apparent are the underlying mechanisms that initiate these critical signaling processes. This is because fluid mechanical forces can offer a direct mechanical input to possible mechanotransducers as well as alter critical mass transport characteristics (i.e., concentration gradients) of a host of chemical stimuli present in the blood stream. However, it has recently been accepted that mechanotransduction (direct mechanical force input), and not mass transfer, is the fundamental mechanism for many hemodynamic force-modulated endothelial signaling pathways and their downstream gene products. This conclusion has been largely based, indirectly, on accepted criteria that correlate signaling behavior and shear rate and shear stress, relative to changes in viscosity. However, in this work, we investigate the negative control for these criteria. Here we computationally and experimentally subject mass-transfer limited systems, independent of mechanotransduction, to the purported criteria. The results showed that the negative control (mass-transfer limited system) produced the same trends that have been used to identify mechanotransduction-dominant systems. Thus, the widely used viscosity-related shear stress and shear rate criteria are insufficient in determining mechanotransduction-dominant systems. Thus, research should continue to consider the importance of mass transfer in triggering signaling cascades.

  6. 46 CFR 153.953 - Signals during cargo transfer.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Signals during cargo transfer. 153.953 Section 153.953 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo...

  7. Unequal mass binary neutron star mergers and multimessenger signals

    NASA Astrophysics Data System (ADS)

    Lehner, Luis; Liebling, Steven L.; Palenzuela, Carlos; Caballero, O. L.; O'Connor, Evan; Anderson, Matthew; Neilsen, David

    2016-09-01

    We study the merger of binary neutron stars with different mass ratios adopting three different realistic, microphysical nuclear equations of state, as well as incorporating neutrino cooling effects. In particular, we concentrate on the influence of the equation of state on the gravitational wave signature and also on its role, in combination with neutrino cooling, in determining the properties of the resulting hypermassive neutron star, of the neutrinos produced, and of the ejected material. The ejecta we find are consistent with other recent studies that find that small mass ratios produce more ejecta than equal mass cases (up to some limit) and this ejecta is more neutron rich. This trend indicates the importance with future kilonovae observations of measuring the individual masses of an associated binary neutron star system, presumably from concurrent gravitational wave observations, in order to be able to extract information about the nuclear equation of state.

  8. SERODS optical data storage with parallel signal transfer

    DOEpatents

    Vo-Dinh, Tuan

    2003-06-24

    Surface-enhanced Raman optical data storage (SERODS) systems having increased reading and writing speeds, that is, increased data transfer rates, are disclosed. In the various SERODS read and write systems, the surface-enhanced Raman scattering (SERS) data is written and read using a two-dimensional process called parallel signal transfer (PST). The various embodiments utilize laser light beam excitation of the SERODS medium, optical filtering, beam imaging, and two-dimensional light detection. Two- and three-dimensional SERODS media are utilized. The SERODS write systems employ either a different laser or a different level of laser power.

  9. SERODS optical data storage with parallel signal transfer

    DOEpatents

    Vo-Dinh, Tuan

    2003-09-02

    Surface-enhanced Raman optical data storage (SERODS) systems having increased reading and writing speeds, that is, increased data transfer rates, are disclosed. In the various SERODS read and write systems, the surface-enhanced Raman scattering (SERS) data is written and read using a two-dimensional process called parallel signal transfer (PST). The various embodiments utilize laser light beam excitation of the SERODS medium, optical filtering, beam imaging, and two-dimensional light detection. Two- and three-dimensional SERODS media are utilized. The SERODS write systems employ either a different laser or a different level of laser power.

  10. Cluster-transfer reactions with radioactive beams: A spectroscopic tool for neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Bottoni, S.; Leoni, S.; Fornal, B.; Raabe, R.; Rusek, K.; Benzoni, G.; Bracco, A.; Crespi, F. C. L.; Morales, A. I.; Bednarczyk, P.; Cieplicka-Oryńczak, N.; Królas, W.; Maj, A.; Szpak, B.; Callens, M.; Bouma, J.; Elseviers, J.; De Witte, H.; Flavigny, F.; Orlandi, R.; Reiter, P.; Seidlitz, M.; Warr, N.; Siebeck, B.; Hellgartner, S.; Mücher, D.; Pakarinen, J.; Vermeulen, M.; Bauer, C.; Georgiev, G.; Janssens, R. V. F.; Balabanski, D.; Sferrazza, M.; Kowalska, M.; Rapisarda, E.; Voulot, D.; Lozano Benito, M.; Wenander, F.

    2015-08-01

    An exploratory experiment performed at REX-ISOLDE to investigate cluster-transfer reactions with radioactive beams in inverse kinematics is presented. The aim of the experiment was to test the potential of cluster-transfer reactions at the Coulomb barrier as a mechanism to explore the structure of exotic neutron-rich nuclei. The reactions 7Li(98Rb,α xn ) and 7Li(98Rb,t xn ) were studied through particle-γ coincidence measurements, and the results are presented in terms of the observed excitation energies and spins. Moreover, the reaction mechanism is qualitatively discussed as a transfer of a clusterlike particle within a distorted-wave Born approximation framework. The results indicate that cluster-transfer reactions can be described well as a direct process and that they can be an efficient method to investigate the structure of neutron-rich nuclei at medium-high excitation energies and spins.

  11. Structure of Light Neutron-rich Nuclei Studied with Transfer Reactions

    SciTech Connect

    Wuosmaa, A. H.

    2015-01-01

    Transfer reactions have been used for many years to understand the shell structure of nuclei. Recent studies with rare-isotope beams extend this work and make it possible to probe the evolution of shell structure far beyond the valley of stability, requiring measurements in inverse kinematics. We present a novel technical approach to measurements in inverse kinematics, and apply this method to different transfer reactions, each of which probes different properties of light, neutron-rich nuclei.

  12. Two-neutron transfer reactions with heavy-deformed nuclei

    SciTech Connect

    Price, C.; Landowne, S.; Esbensen, H.

    1988-01-01

    In a recent communication we pointed out that one can combine the macroscopic model for two-particle transfer reactions on deformed nuclei with the sudden limit approximation for rotational excitation, and thereby obtain a practical method for calculating transfer reactions leading to high-spin states. As an example, we presented results for the reaction WSDy(VYNi,WNi) WDy populating the ground-state rotational band up to the spin I = 14 state. We have also tested the validity of the sudden limit for the inelastic excitation of high spin states and we have noted how the macroscopic model may be modified to allow for more microscopic nuclear structure effects in an application to diabolic pair-transfer processes. This paper describes our subsequent work in which we investigated the systematic features of pair-transfer reactions within the macroscopic model by using heavier projectiles to generate higher spins and by decomposing the cross sections according to the multipolarity of the transfer interaction. Particular attention is paid to characteristic structures in the angular distributions for the lower spin states and how they depend on the angular momentum carried by the transferred particles. 11 refs., 3 figs.

  13. Pair neutron transfer in 60Ni+116Sn probed via γ -particle coincidences

    NASA Astrophysics Data System (ADS)

    Montanari, D.; Corradi, L.; Szilner, S.; Pollarolo, G.; Goasduff, A.; Mijatović, T.; Bazzacco, D.; Birkenbach, B.; Bracco, A.; Charles, L.; Courtin, S.; Désesquelles, P.; Fioretto, E.; Gadea, A.; Görgen, A.; Gottardo, A.; Grebosz, J.; Haas, F.; Hess, H.; Jelavić Malenica, D.; Jungclaus, A.; Karolak, M.; Leoni, S.; Maj, A.; Menegazzo, R.; Mengoni, D.; Michelagnoli, C.; Montagnoli, G.; Napoli, D. R.; Pullia, A.; Recchia, F.; Reiter, P.; Rosso, D.; Salsac, M. D.; Scarlassara, F.; Söderström, P.-A.; Soić, N.; Stefanini, A. M.; Stezowski, O.; Theisen, Ch.; Ur, C. A.; Valiente-Dobón, J. J.; Varga Pajtler, M.

    2016-05-01

    We performed a γ -particle coincidence experiment for the 60Ni + 116Sn system to investigate whether the population of the two-neutron pickup channel leading to 62Ni is mainly concentrated in the ground-state transition, as has been found in a previous work [D. Montanari et al., Phys. Rev. Lett. 113, 052501 (2014), 10.1103/PhysRevLett.113.052501]. The experiment has been performed by employing the PRISMA magnetic spectrometer coupled to the Advanced Gamma Tracking Array (AGATA) demonstrator. The strength distribution of excited states corresponding to the inelastic, one- and two-neutron transfer channels has been extracted. We found that in the two-neutron transfer channel the strength to excited states corresponds to a fraction (less than 24%) of the total, consistent with the previously obtained results that the 2 n channel is dominated by the ground-state to ground-state transition.

  14. Neutron Transfer Reactions on Neutron-Rich N = 50 and N = 82 Nuclei Near the r-Process Path

    SciTech Connect

    Cizewski, J. A.; Hatarik, R.; Jones, K. L.; Kozub, R. L.; Paulauskas, S. V.; Shriner, J. F.; Sissom, D. J.; Pain, S. D.; Thomas, J. S.; Swan, T.; Wilson, G. L.; Arbanas, G.; Bardayan, D. W.; Blackmon, J. C.; Dean, D.; Liang, F.; Shapira, D.; Smith, M. S.; Adekola, A.; Chae, K. Y.

    2009-01-28

    Neutron transfer (d,p) reaction studies on the N = 50 isotones, {sup 82}Ge and {sup 84}Se, and A{approx_equal}130 nuclei, {sup 130,132}Sn and {sup 134}Te, have been measured. Direct neutron capture cross sections for {sup 82}Ge and {sup 84}Se (n,{gamma}) have been calculated and are combined with Hauser-Feshbach expectations to estimate total (n,{gamma}) cross sections. The A{approx_equal}130 studies used an early implementation of the ORRUBA array of position-sensitive silicon strip detectors for reaction proton measurements. Preliminary excitation energy and angular distribution results from the A{approx_equal}130 measurements are reported.

  15. Transfer Reactions on Neutron-rich Nuclei at REX-ISOLDE

    NASA Astrophysics Data System (ADS)

    Kröll, Th.; Bildstein, V.; Wimmer, K.; Krücken, R.; Gernhäuser, R.; Lutter, R.; Schwerdtfeger, W.; Thirolf, P.; Bastin, B.; Bree, N.; Diriken, J.; Huyse, M.; Patronis, N.; Raabe, R.; Van Duppen, P.; Vermaelen, P.; Cederkäll, J.; Clément, E.; Van de Walle, J.; Voulot, D.; Wenander, F.; Blazhev, A.; Kalkühler, M.; Reiter, P.; Seidlitz, M.; Warr, N.; Deacon, A.; Fitzpatrick, C.; Freeman, S.; Das Gupta, S.; Lo Bianco, G.; Nardelli, S.; Fiori, E.; Georgiev, G.; Scheck, M.; Fraile, L. M.; Balabanski, D.; Nilsson, T.; Tengborn, E.; Butterworth, J.; Singh, B. S. Nara; Angus, L.; Chapman, R.; Hadinia, B.; Orlandi, R.; Smith, J. F.; Wady, P.; Schrieder, G.; Labiche, M.; Johansen, J.; Riisager, K.; Jeppesen, H. B.; Macchiavelli, A. O.; Davinson, T.

    2009-08-01

    We report on one- and two-neutron transfer reactions to study the single-particle properties of nuclei at the border of the "island of inversion." The (d, p)- and (t, p)-reactions in inverse kinematics on the neutron-rich isotope 30Mg, delivered as radioactive beam by the REX-ISOLDE facility, have been investigated. The outgoing protons have been detected and identified by a newly built array of Si detectors. The γ-decay of excited states has been detected in coincidence by the MINIBALL array. First results for 31Mg and from the search for the second, spherical, 0+ state in 32Mg are presented.

  16. A New Automated Sample Transfer System for Instrumental Neutron Activation Analysis

    PubMed Central

    Ismail, S. S.

    2010-01-01

    A fully automated and fast pneumatic transport system for short-time activation analysis was recently developed. It is suitable for small nuclear research reactors or laboratories that are using neutron generators and other neutron sources. It is equipped with a programmable logic controller, software package, and 12 devices to facilitate optimal analytical procedures. 550 ms were only necessary to transfer the irradiated capsule (diameter: 15 mm, length: 50 mm, weight: 4 gram) to the counting chamber at a distance of 20 meters using pressurized air (4 bars) as a transport gas. PMID:20369063

  17. Fast digitization and discrimination of prompt neutron and photon signals using a novel silicon carbide detector

    SciTech Connect

    Brandon W. Blackburn; James T. Johnson; Scott M. Watson; David L. Chichester; James L. Jones; Frank H. Ruddy; John G. Seidel; Robert W. Flammang

    2007-04-01

    Current requirements of some Homeland Security active interrogation projects for the detection of Special Nuclear Material (SNM) necessitate the development of faster inspection and acquisition capabilities. In order to do so, fast detectors which can operate during and shortly after intense interrogation radiation flashes are being developed. Novel silicon carbide (SiC) semiconductor Schottky diodes have been utilized as robust neutron and photon detectors in both pulsed photon and pulsed neutron fields and are being integrated into active inspection environments to allow exploitation of both prompt and delayed emissions. These detectors have demonstrated the capability of detecting both photon and neutron events during intense photon flashes typical of an active inspection environment. Beyond the inherent insensitivity of SiC to gamma radiation, fast digitization and processing has demonstrated that pulse shape discrimination (PSD) in combination with amplitude discrimination can further suppress unwanted gamma signals and extract fast neutron signatures. Usable neutron signals have been extracted from mixed radiation fields where the background has exceeded the signals of interest by >1000:1.

  18. One and two-neutron transfer reactions at REX-ISOLDE

    NASA Astrophysics Data System (ADS)

    Wimmer, Kathrin; T-REX Collaboration

    2011-10-01

    In this contribution we will report on one and two neutron transfer reaction experiments in inverse kinematics at the REX-ISOLDE facility (CERN). Light charged target-like reaction products were detected and identified by the T-REX particle detector while coincident γ-rays were detected by the MINIBALL Germanium detector array. Recent results on (d,p) as well as (t,p) reactions with radioactive beams ranging from 11Be to 78Zn isotopes will be presented. The two-neutron transfer reactions involved for the first time the use of a radioactive tritium target in combination with a radioactive heavy ion beam. Supported by BMBF 06MT238, 06DA9036I, EURONS (No. 506065), and the DFG cluster of excellence Universe.

  19. Discovery of the Shape Coexisting 0+ State in Mg32 by a Two Neutron Transfer Reaction

    NASA Astrophysics Data System (ADS)

    Wimmer, K.; Kröll, T.; Krücken, R.; Bildstein, V.; Gernhäuser, R.; Bastin, B.; Bree, N.; Diriken, J.; van Duppen, P.; Huyse, M.; Patronis, N.; Vermaelen, P.; Voulot, D.; van de Walle, J.; Wenander, F.; Fraile, L. M.; Chapman, R.; Hadinia, B.; Orlandi, R.; Smith, J. F.; Lutter, R.; Thirolf, P. G.; Labiche, M.; Blazhev, A.; Kalkühler, M.; Reiter, P.; Seidlitz, M.; Warr, N.; Macchiavelli, A. O.; Jeppesen, H. B.; Fiori, E.; Georgiev, G.; Schrieder, G.; Das Gupta, S.; Lo Bianco, G.; Nardelli, S.; Butterworth, J.; Johansen, J.; Riisager, K.

    2010-12-01

    The “island of inversion” nucleus Mg32 has been studied by a (t, p) two neutron transfer reaction in inverse kinematics at REX-ISOLDE. The shape coexistent excited 0+ state in Mg32 has been identified by the characteristic angular distribution of the protons of the ΔL=0 transfer. The excitation energy of 1058 keV is much lower than predicted by any theoretical model. The low γ-ray intensity observed for the decay of this 0+ state indicates a lifetime of more than 10 ns. Deduced spectroscopic amplitudes are compared with occupation numbers from shell-model calculations.

  20. Discovery of the shape coexisting 0+ state in 32 Mg by a two neutron transfer reaction.

    PubMed

    Wimmer, K; Kröll, T; Krücken, R; Bildstein, V; Gernhäuser, R; Bastin, B; Bree, N; Diriken, J; Van Duppen, P; Huyse, M; Patronis, N; Vermaelen, P; Voulot, D; Van de Walle, J; Wenander, F; Fraile, L M; Chapman, R; Hadinia, B; Orlandi, R; Smith, J F; Lutter, R; Thirolf, P G; Labiche, M; Blazhev, A; Kalkühler, M; Reiter, P; Seidlitz, M; Warr, N; Macchiavelli, A O; Jeppesen, H B; Fiori, E; Georgiev, G; Schrieder, G; Das Gupta, S; Lo Bianco, G; Nardelli, S; Butterworth, J; Johansen, J; Riisager, K

    2010-12-17

    The "island of inversion" nucleus 32 Mg has been studied by a (t, p) two neutron transfer reaction in inverse kinematics at REX-ISOLDE. The shape coexistent excited 0+ state in 32 Mg has been identified by the characteristic angular distribution of the protons of the Δ L=0 transfer. The excitation energy of 1058 keV is much lower than predicted by any theoretical model. The low γ-ray intensity observed for the decay of this 0+ state indicates a lifetime of more than 10 ns. Deduced spectroscopic amplitudes are compared with occupation numbers from shell-model calculations.

  1. Spectroscopy of 46Ar by the (t ,p ) two-neutron transfer reaction

    NASA Astrophysics Data System (ADS)

    Nowak, K.; Wimmer, K.; Hellgartner, S.; Mücher, D.; Bildstein, V.; Diriken, J.; Elseviers, J.; Gaffney, L. P.; Gernhäuser, R.; Iwanicki, J.; Johansen, J. G.; Huyse, M.; Konki, J.; Kröll, T.; Krücken, R.; Lutter, R.; Orlandi, R.; Pakarinen, J.; Raabe, R.; Reiter, P.; Roger, T.; Schrieder, G.; Seidlitz, M.; Sorlin, O.; Van Duppen, P.; Warr, N.; De Witte, H.; Zielińska, M.

    2016-04-01

    States in the N =28 nucleus 46Ar have been studied by a two-neutron transfer reaction at REX-ISOLDE (CERN). A beam of radioactive 44Ar at an energy of 2.16 AMeV and a tritium-loaded titanium target were used to populate 46Ar by the 3H(44Ar,p ) two-neutron transfer reaction. Protons emitted from the target were identified in the T-REX silicon detector array. The excitation energies of states in 46Ar have been reconstructed from the measured angles and energies of recoil protons. Angular distributions for three final states were measured and based on the shape of the differential cross section an excited state at 3695 keV was identified as Jπ=0+ . The angular differential cross section for the population of different states are compared to calculations using a reaction model employing both sequential and direct transfer of two neutrons. Results are compared to shell-model calculations using state-of-the-art effective interactions.

  2. Conditions for Lorentz-invariant superluminal information transfer without signaling

    NASA Astrophysics Data System (ADS)

    Grössing, G.; Fussy, S.; Mesa Pascasio, J.; Schwabl, H.

    2016-03-01

    We understand emergent quantum mechanics in the sense that quantum mechanics describes processes of physical emergence relating an assumed sub-quantum physics to macroscopic boundary conditions. The latter can be shown to entail top-down causation, in addition to usual bottom-up scenarios. With this example it is demonstrated that definitions of “realism” in the literature are simply too restrictive. A prevailing manner to define realism in quantum mechanics is in terms of pre-determination independent of the measurement. With our counter-example, which actually is ubiquitous in emergent, or self-organizing, systems, we argue for realism without pre-determination. We refer to earlier results of our group showing how the guiding equation of the de Broglie-Bohm interpretation can be derived from a theory with classical ingredients only. Essentially, this corresponds to a “quantum mechanics without wave functions” in ordinary 3-space, albeit with nonlocal correlations. This, then, leads to the central question of how to deal with the nonlocality problem in a relativistic setting. We here show that a basic argument discussing the allegedly paradox time ordering of events in EPR-type two-particle experiments falls short of taking into account the contextuality of the experimental setup. Consequently, we then discuss under which circumstances (i.e. physical premises) superluminal information transfer (but not signaling) may be compatible with a Lorentz-invariant theory. Finally, we argue that the impossibility of superluminal signaling - despite the presence of superluminal information transfer - is not the result of some sort of conspiracy (á la “Nature likes to hide”), but the consequence of the impossibility to exactly reproduce in repeated experimental runs a state's preparation, or of the no-cloning theorem, respectively.

  3. Transfer Function between EEG and BOLD Signals of Epileptic Activity

    PubMed Central

    Leite, Marco; Leal, Alberto; Figueiredo, Patrícia

    2013-01-01

    Simultaneous electroencephalogram (EEG)-functional Magnetic Resonance Imaging (fMRI) recordings have seen growing application in the evaluation of epilepsy, namely in the characterization of brain networks related to epileptic activity. In EEG-correlated fMRI studies, epileptic events are usually described as boxcar signals based on the timing information retrieved from the EEG, and subsequently convolved with a hemodynamic response function to model the associated Blood Oxygen Level Dependent (BOLD) changes. Although more flexible approaches may allow a higher degree of complexity for the hemodynamics, the issue of how to model these dynamics based on the EEG remains an open question. In this work, a new methodology for the integration of simultaneous EEG-fMRI data in epilepsy is proposed, which incorporates a transfer function from the EEG to the BOLD signal. Independent component analysis of the EEG is performed, and a number of metrics expressing different models of the EEG-BOLD transfer function are extracted from the resulting time courses. These metrics are then used to predict the fMRI data and to identify brain areas associated with the EEG epileptic activity. The methodology was tested on both ictal and interictal EEG-fMRI recordings from one patient with a hypothalamic hamartoma. When compared to the conventional analysis approach, plausible, consistent, and more significant activations were obtained. Importantly, frequency-weighted EEG metrics yielded superior results than those weighted solely on the EEG power, which comes in agreement with previous literature. Reproducibility, specificity, and sensitivity should be addressed in an extended group of patients in order to further validate the proposed methodology and generalize the presented proof of concept. PMID:23355832

  4. Heat transfer and core neutronics considerations of the heat pipe cooled thermionic reactor

    NASA Astrophysics Data System (ADS)

    Determan, W. R.; Lewis, Brian

    The authors summarize the results of detailed neutronic and thermal-hydraulic evaluations of the heat pipe cooled thermionic (HPTI) reactor design, identify its key design attributes, and quantify its performance characteristics. The HPTI core uses modular, liquid-metal core heat transfer assemblies to replace the liquid-metal heat transport loop employed by in-core thermionic reactor designs of the past. The nuclear fuel, power conversion, heat transport, and heat rejection functions are all combined into a single modular unit. The reactor/converter assembly uses UN fuel pins to obtain a critical core configuration with in-core safety rods and reflector controls added to complete the subassembly. By thermally bonding the core heat transfer assemblies during the reactor core is coupled neutronically, thermally, and electrically into a modular assembly of individual power sources with cross-tied architecture. A forward-facing heat pipe radiator assembly extends from the reactor head in the shape of a frustum of a cone on the opposite side of the power system from the payload. Important virtues of the concept are the absence of any single-point failures and the ability of the core to effectively transfer the TFE waste heat load laterally to other in-core heat transfer assemblies in the event of multiple failures in either in-core and radiator heat pipes.

  5. Heat transfer and core neutronics considerations of the heat pipe cooled thermionic reactor

    NASA Technical Reports Server (NTRS)

    Determan, W. R.; Lewis, Brian

    1991-01-01

    The authors summarize the results of detailed neutronic and thermal-hydraulic evaluations of the heat pipe cooled thermionic (HPTI) reactor design, identify its key design attributes, and quantify its performance characteristics. The HPTI core uses modular, liquid-metal core heat transfer assemblies to replace the liquid-metal heat transport loop employed by in-core thermionic reactor designs of the past. The nuclear fuel, power conversion, heat transport, and heat rejection functions are all combined into a single modular unit. The reactor/converter assembly uses UN fuel pins to obtain a critical core configuration with in-core safety rods and reflector controls added to complete the subassembly. By thermally bonding the core heat transfer assemblies during the reactor core is coupled neutronically, thermally, and electrically into a modular assembly of individual power sources with cross-tied architecture. A forward-facing heat pipe radiator assembly extends from the reactor head in the shape of a frustum of a cone on the opposite side of the power system from the payload. Important virtues of the concept are the absence of any single-point failures and the ability of the core to effectively transfer the TFE waste heat load laterally to other in-core heat transfer assemblies in the event of multiple failures in either in-core and radiator heat pipes.

  6. Simultaneous multichannel signal transfers via chaos in a recurrent neural network.

    PubMed

    Soma, Ken-ichiro; Mori, Ryota; Sato, Ryuichi; Furumai, Noriyuki; Nara, Shigetoshi

    2015-05-01

    We propose neural network model that demonstrates the phenomenon of signal transfer between separated neuron groups via other chaotic neurons that show no apparent correlations with the input signal. The model is a recurrent neural network in which it is supposed that synchronous behavior between small groups of input and output neurons has been learned as fragments of high-dimensional memory patterns, and depletion of neural connections results in chaotic wandering dynamics. Computer experiments show that when a strong oscillatory signal is applied to an input group in the chaotic regime, the signal is successfully transferred to the corresponding output group, although no correlation is observed between the input signal and the intermediary neurons. Signal transfer is also observed when multiple signals are applied simultaneously to separate input groups belonging to different memory attractors. In this sense simultaneous multichannel communications are realized, and the chaotic neural dynamics acts as a signal transfer medium in which the signal appears to be hidden.

  7. Transfer Reactions on Neutron-rich Nuclei at REX-ISOLDE

    SciTech Connect

    Kroell, Th.; Bildstein, V.; Wimmer, K.; Kruecken, R.; Gernhaeuser, R.; Lutter, R.; Schwerdtfeger, W.; Thirolf, P.; Bastin, B.; Bree, N.; Diriken, J.; Huyse, M.; Patronis, N.; Raabe, R.; Van Duppen, P.; Vermaelen, P.; Cederkaell, J.; Clement, E.; Van de Walle, J.; Voulot, D.

    2009-08-26

    We report on one- and two-neutron transfer reactions to study the single-particle properties of nuclei at the border of the ''island of inversion.'' The (d, p)- and (t, p)-reactions in inverse kinematics on the neutron-rich isotope {sup 30}Mg, delivered as radioactive beam by the REX-ISOLDE facility, have been investigated. The outgoing protons have been detected and identified by a newly built array of Si detectors. The {gamma}-decay of excited states has been detected in coincidence by the MINIBALL array. First results for {sup 31}Mg and from the search for the second, spherical, 0{sup +} state in {sup 32}Mg are presented.

  8. Signal transfer in passive dendrites with nonuniform membrane conductance.

    PubMed

    London, M; Meunier, C; Segev, I

    1999-10-01

    In recent years it became clear that dendrites possess a host of ion channels that may be distributed nonuniformly over their membrane surface. In cortical pyramids, for example, it was demonstrated that the resting membrane conductance G(m)(x) is higher (the membrane is "leakier") at distal dendritic regions than at more proximal sites. How does this spatial nonuniformity in G(m)(x) affect the input-output function of the neuron? The present study aims at providing basic insights into this question. To this end, we have analytically studied the fundamental effects of membrane non-uniformity in passive cable structures. Keeping the total membrane conductance over a given modeled structure fixed (i.e., a constant number of passive ion channels), the classical case of cables with uniform membrane conductance is contrasted with various nonuniform cases with the following general conclusions. (1) For cylindrical cables with "sealed ends," monotonic increase in G(m)(x) improves voltage transfer from the input location to the soma. The steeper the G(m)(x), the larger the improvement. (2) This effect is further enhanced when the stimulation is distal and consists of a synaptic input rather than a current source. (3) Any nonuniformity in G(m)(x) decreases the electrotonic length, L, of the cylinder. (4) The system time constant tau(0) is larger in the nonuniform case than in the corresponding uniform case. (5) When voltage transients relax with tau(0), the dendritic tree is not isopotential in the nonuniform case, at variance with the uniform case. The effect of membrane nonuniformity on signal transfer in reconstructed dendritic trees and on the I/f relation of the neuron is also considered, and experimental methods for assessing membrane nonuniformity in dendrites are discussed.

  9. Mechanisms of sequential particle transfer and characteristics of light neutron-excess and oriented nuclei

    NASA Astrophysics Data System (ADS)

    Galanina, L. I.; Zelenskaya, N. S.

    2012-03-01

    The procedure for evaluating the second-order corrections to the matrix elements of the reaction A( x, y) B, which are obtained using the method of distorted waves with a finite radius of intercluster interaction (DWBAFR), is developed. It is based on the assumption of a virtual cluster structure of light nuclei and uses integral equations for a four-body problem in the Alt-Grassberger-Sandhas formalism. These corrections are related with the mechanisms of sequential particles transfer. The latter are represented by the quadrangle diagrams. Their matrix elements are summed up coherently with those given by the pole and triangle diagrams which were calculated by using DWBAFR. The computer code QUADRO is written for the numerical implementation of the method proposed. The statistical tensors of nucleus B formed in the reaction A( x, y) B at incident particle energies of about 10 MeV/nucleon in the center of mass frame are determined. Specific calculations allowed for description of both the experimental cross sections (0-rank statistical tensors) of various reactions (including those where nucleus B has some excess neutrons) and polarized characteristics of nucleus B* (in the case of the latter produced in the exited state). A two-neutron periphery of nuclei 6He, 10Be, 12B (both in dineutron and cigarlike configurations) is restored by analyzing the differential cross sections of elastic alpha-6He-scattering and 9Be( d, p)10Be and 10B( t, p)12B reactions. It is shown that the structure of neutron peripheries is fundamentally different for these nuclei and its feature depends on the way those neutron-excess nuclei are formed: in 6He both configurations contribute to a two-neutron halo, while in 10Be there is a barely noticeable one-neutron halo, and in 12B there is a "dineutron skin". Orientation characteristics of nuclei B* are calculated. Their comparison with experimental data made it possible to draw important conclusions about a contribution to the statistical

  10. Two-neutron transfer analysis of the 16O(18O,16O)18O reaction

    NASA Astrophysics Data System (ADS)

    Ermamatov, M. J.; Cappuzzello, F.; Lubian, J.; Cubero, M.; Agodi, C.; Carbone, D.; Cavallaro, M.; Ferreira, J. L.; Foti, A.; Garcia, V. N.; Gargano, A.; Lay, J. A.; Lenzi, S. M.; Linares, R.; Santagati, G.; Vitturi, A.

    2016-08-01

    Recently a quantitative description of the two-neutron transfer reaction 12C(18O,16O)14C was performed and the measured cross sections were successfully reproduced [M. Cavallaro et al., Phys. Rev. C 88, 054601 (2013), 10.1103/PhysRevC.88.054601]. This task was accomplished by combining nuclear structure calculations of spectroscopic amplitudes and a full quantum description of the reaction mechanism. Verification of such a theoretical approach to other heavy nuclear systems is mandatory in order to use (18O,16O ) reactions to assess pair configurations in nuclear states. In this work we apply this methodology to the 16O(18O,16O)18O reaction at 84 MeV. Experimental angular distributions for the two-neutron transfer to the ground state and 21+ state of 18O were obtained using the MAGNEX spectrometer at INFN-LNS. The roles of one- and two-step processes are analyzed under the exact finite range coupled reaction channel and the second order distorted wave Born approximation. We conclude that the one-step transfer mechanism is dominant in this system.

  11. Analysis of the role of neutron transfer in asymmetric fusion reactions at subbarrier energies

    SciTech Connect

    Ogloblin, A. A.; Zhang, H. Q.; Lin, C. J.; Jia, H. M.; Khlebnikov, S. V.; Kuzmin, E. A.; Danilov, A. N.; Demyanova, A. S.; Trzaska, W. H.; Xu, X. X.; Yang, F.; Sargsyan, V. V. Adamian, G. G.; Antonenko, N. V.; Scheid, W.

    2015-12-15

    The excitation functions were measured for the {sup 28}Si + {sup 208}Pb complete-fusion (capture) reaction at deep subbarrier energies. The results were compared with the cross sections predicted within the quantum diffusion approach. The role of neutron transfer in the case of positive Q values in the {sup 28}Si + {sup 124}Sn, {sup 208}Pb; {sup 30}Si + {sup 124}Sn, {sup 208}Pb; {sup 20}Ne + {sup 208}Pb; {sup 40}Ca + {sup 96}Zr; and {sup 134}Te + {sup 40}Ca complete-fusion (capture) reactions is discussed.

  12. Studies of Nuclei Close to 132Sn Using Single-Neutron Transfer Reactions

    SciTech Connect

    Jones, K. L.; Pain, S. D.; Kozub, R. L.; Adekola, Aderemi S; Bardayan, Daniel W; Blackmon, Jeff C; Catford, Wilton N; Chae, K. Y.; Chipps, K.; Cizewski, J. A.; Erikson, Luke; Gaddis, A. L.; Greife, U.; Grzywacz, R. K.; Harlin, Christopher W; Hatarik, Robert; Howard, Joshua A; James, J.; Kapler, R.; Krolas, W.; Liang, J Felix; Ma, Zhanwen; Matei, Catalin; Moazen, Brian; Nesaraja, Caroline D; O'Malley, Patrick; Patterson, N. P.; Paulauskas, Stanley; Shapira, Dan; ShrinerJr., J. F.; Sikora, M.; Sissom, D. J.; Smith, Michael Scott; Swan, T. P.; Thomas, J. S.; Wilson, Gemma L

    2009-01-01

    Neutron transfer reactions were performed in inverse kinematics using radioactive ion beams of 132Sn, 130Sn, and 134Te and deuterated polyethylene targets. Preliminary results are presented. The Q-value spectra for 133Sn, 131Sn and 135Te reveal a number of previously unobserved peaks. The angular distributions are compatible with the expected lf7/2 nature of the ground state of 133Sn, and 2p3/2 for the 3.4 MeV state in 131Sn.

  13. {sup 10}Li low-lying resonances populated by one-neutron transfer

    SciTech Connect

    Cavallaro, M. Agodi, C.; Carbone, D.; Cunsolo, A.; De Napoli, M.; Cappuzzello, F.; Bondì, M.; Davids, B.; Galinski, N.; Ruiz, C.; Davinson, T.; Sanetullaev, A.; Foti, A.; Kanungo, R.; Lenske, H.; Orrigo, S. E. A.

    2015-10-15

    The {sup 9}Li + {sup 2}H → {sup 10}Li + {sup 1}H one-neutron transfer reaction has been performed at 100 MeV incident energy at TRIUMF using a {sup 9}Li beam delivered by the ISAC-II facility. A setup based on double-sided silicon strip detectors has been used in order to detect and identify the outgoing {sup 9}Li produced by the {sup 10}Li breakup at forward angles and the recoil protons emitted at backward angles. The {sup 10}Li low-lying resonances, whose energies, widths and configurations are still unclear, have been populated with significant statistics.

  14. Studies of nuclei close to {sup 132}Sn using single-neutron transfer reactions

    SciTech Connect

    Jones, K. J.; Pain, S. D.; Kozub, R. L.; Howard, J. A.; O'Malley, P. D.; Paulauskas, S. V.; Shriner, J. F.; Sissom, D. J.; Adekola, A. S.; Bardayan, D. W.; Blackmon, J. C.; Liang, J. F.; Nesaraja, C. D.; Shapira, D.; Smith, M. S.; Catford, W. N.; Harlin, C.; Patterson, N. P.; Swan, T. P.; Wilson, G. L.

    2009-03-04

    Neutron transfer reactions were performed in inverse kinematics using radioactive ion beams of {sup 132}Sn, {sup 130}Sn, and {sup 134}Te and deuterated polyethylene targets. Preliminary results are presented. The Q-value spectra for {sup 133}Sn, {sup 131}Sn and {sup 135}Te reveal a number of previously unobserved peaks. The angular distributions are compatible with the expected lf{sub 7/2} nature of the ground state of {sup 133}Sn, and 2p{sub 3/2} for the 3.4 MeV state in {sup 131}Sn.

  15. Correlation of Radiation and Electron and Neutron Signals at PF-1000

    SciTech Connect

    Kubes, P.; Kravarik, J.; Barvir, P.; Klir, D.; Scholz, M.; Paduch, M.; Tomaszewski, K.; Ivanova-Stanik, I.; Bienkowska, B.; Ryc, L.; Karpinski, L.; Juha, L.; Krasa, J.; Sadowski, M. J.; Skladnik-Sadowska, E.; Jakubowski, L.; Szydlowski, A.; Malinowska, A.; Malinowski, K.; Schmidt, H.

    2006-01-15

    At the signals of x-rays usually 2 peaks were observed. The first peak corresponded to the time of the minimum diameter of the imploding plasma sheath (pinch phase) recorded by the visible frames. The second peak occurred 150-200 ns later at the time of the development of instabilities. High-energy electrons registered in the upstream and downstream directions differed in the intensity (ratio 3:1) and in the time of production. Their peaks correlated with x-rays. The energy of neutrons and time of their generation were determined by time-of-flight method from the pulses of seven scintillation detectors positioned in the axial direction. At the rise-time, each neutron pulse has registered downstream energies in range of 2.7-3.2 MeV. The final part of neutron pulse has isotropic energy distribution with energies up to 2.6-2.7 MeV. The evolution of the neutron pulses correlates with the visible frames. The first pulse correlates with the fast downstream zipper-effect of the dense plasma in the pinch and with the forming of the radiating ball-shaped structure at the bottom of the dilating plasma sheath. The second neutron pulse correlates with the second pinching and exploding of the plasma of lower density and with existence of the structure of the dense plasma positioned at the bottom of the dilating current sheath, similarly to the first pulse. The neutrons have a non-thermal beam-target origin. A possible influence of the zipper-effect on the acceleration of deuterons and on the plasma heating is discussed.

  16. 46 CFR 153.953 - Signals during cargo transfer.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... red flag in the day and a red light at night when transferring cargo while fast to a dock; (b) The tankship displays a red flag when transferring cargo while at anchor; and (c) The red flag or the red...

  17. 46 CFR 153.953 - Signals during cargo transfer.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... red flag in the day and a red light at night when transferring cargo while fast to a dock; (b) The tankship displays a red flag when transferring cargo while at anchor; and (c) The red flag or the red...

  18. Gravitational-wave signal from binary neutron stars: A systematic analysis of the spectral properties

    NASA Astrophysics Data System (ADS)

    Rezzolla, Luciano; Takami, Kentaro

    2016-06-01

    A number of works have shown that important information on the equation of state of matter at nuclear density can be extracted from the gravitational waves emitted by merging neutron-star binaries. We present a comprehensive analysis of the gravitational-wave signal emitted during the inspiral, merger, and postmerger of 56 neutron-star binaries. This sample of binaries, arguably the largest studied to date with realistic equations of state, spans six different nuclear-physics equations of state and ten masses, allowing us to sharpen a number of results recently obtained on the spectral properties of the gravitational-wave signal. Overall we find the following: (i) for binaries with masses differing no more than 20%, the frequency at gravitational-wave amplitude's maximum is related quasiuniversally with the tidal deformability of the two stars; (ii) the spectral properties vary during the postmerger phase, with a transient phase lasting a few milliseconds after the merger and followed by a quasistationary phase; (iii) when distinguishing the spectral peaks between these two phases, a number of ambiguities in the identification of the peaks disappear, leaving a simple and robust picture; (iv) using properly identified frequencies, quasiuniversal relations are found between the spectral features and the properties of the neutron stars; (v) for the most salient peaks analytic fitting functions can be obtained in terms of the stellar tidal deformability or compactness. Altogether, these results support the idea that the equation of state of nuclear matter can be constrained tightly when a signal in gravitational waves from binary neutron stars is detected.

  19. Development of Fast Measurement System of Neutron Emission Profile Using a Digital Signal Processing Technique in JT-60U

    SciTech Connect

    Ishikawa, M.; Shinohara, K.; Itoga, T.; Okuji, T.; Nakhostin, M.; Baba, M.; Nishitani, T.

    2008-03-12

    Neutron emission profiles are routinely measured in JT-60U Tokamak. Stinbene neuron detectors (SNDs), which combine a Stilbene organic crystal scintillation detector (Stilbene detector) with an analog neutron-gamma pulse shape discrimination (PSD) circuit, have been used to measure neutron flux efficiently. Although the SND has many advantages as a neutron detector, the maximum count rate is limited up to {approx}1x 10{sup 5} counts/s due to the dead time of the analog PSD circuit. To overcome this issue, a digital signal processing (DSP) system using a Flash-ADC has been developed. In this system, anode signals from the photomultiplier of the Stilbene detector are fed to the Flash ADC and digitized. Then, the PSD between neutrons and gamma-rays are performed using software. The photomultiplier tube is also modified to suppress and correct gain fluctuation of the photomultiplier. The DSP system has been installed in the center channel of the vertical neutron collimator system in JT-60U and applied to measurements of neutron flux in JT-60U experiments. Neutron flux are successfully measured with count rate up to {approx}1x 10{sup 6} counts/s without the effect of pile up of detected pulses. The performance of the DSP system as a neutron detector is demonstrated.

  20. Modeling and signal analysis of semiconducting B(5)C neutron detectors

    NASA Astrophysics Data System (ADS)

    Harken, Andrew D.

    Neutron detectors are needed for a myriad of applications ranging from military uses to power generation monitors to medical radiation therapy. Recently, a class of semiconducting boron carbide (B5C)/silicon heterojunction diodes were demonstrated to detect thermal neutrons.[1] The B5C-based devices have advantageous features of requiring low operating voltage, low power, are robust and extremely thin while maintaining detection efficiency. A simple model was developed for the analysis of the neutron capture output spectrum from the detectors, which allowed the comparison of several differing styles of planar geometry detectors. The model was also utilized to obtain the functional dependence of the device efficiencies, capture product spectral features, and the capture product energy deposition on capture layer thickness. An all-B5C device construction was determined by the model to be the most efficient form of a B5C-based detector, which reaches nearly 100% detection efficiency with a low probability of false positives. This model showed agreement with output from a full-physics simulation package, GEANT4, and experimental neutron detection spectra from a B5C/Si device. The signals generated in a B5C/Si heterojunction diode during neutron and alpha particle detection experiments were analyzed through fitting of the output current pulses and through capture output spectra. The output current pulse analysis confirmed charge generation and collection from both materials in the diode and demonstrated the suitability of the B5C material for use in an all-semiconducting B5C neutron detector. The experimental output spectra were analyzed and determined to be lower in detected capture product energy than expected, but retained the spectral features that allowed analysis of the detection results. The development of the model and the results from the particle detection experiments show great promise for the future development of B5C neutron detectors. [1]B. W. Robertson, S

  1. Coulomb renormalization of the pole singularity of the neutron-transfer-reaction amplitude

    SciTech Connect

    Borbely, I.; Kayumov, S.S.; Mukhamedzhanov, A.M.; Yarmukhamedov, R. )

    1989-05-01

    The behavior of the neutron-transfer-reaction amplitude has been determined in the DWBA near the cos{theta} singularity ({theta} being the scattering angle in the c. m. s.) corresponding to the pole mechanism of neutron transfer. The Coulomb renormalization factor (CRF) of the pole residue of the differential cross section has been obtained. The exact CRF {vert bar}{ital N}{vert bar}{sup 2} (in the three-body model), the CRF {vert bar}{ital N}{sup {ital DW}}{vert bar}{sup 2} determined by the total DWBA amplitude, and the CRF {vert bar}{ital N}{sup {ital DW}}{sub post}{vert bar}{sup 2} given by the DWBA amplitude in the post approximation are compared. It is shown that the factors {vert bar}{ital N}{sup {ital DW}}{vert bar}{sup 2} and {vert bar}{ital N}{vert bar}{sup 2} are practically the same, and always {vert bar}{ital N}{vert bar}{sup 2}{gt}{vert bar}{ital N}{sup {ital DW}}{sub post}{vert bar}{sup 2}. As the energy increases, the difference between {vert bar}{ital N}{sup {ital DW}}{sub post}{vert bar}{sup 2} and {vert bar}{ital N}{vert bar}{sup 2} decreases.

  2. m =1 instability and gravitational wave signal in binary neutron star mergers

    NASA Astrophysics Data System (ADS)

    Lehner, Luis; Liebling, Steven L.; Palenzuela, Carlos; Motl, Patrick M.

    2016-08-01

    We examine the development and detectability of the m =1 instability in the remnant of binary neutron star mergers. The detection of the gravitational mode associated with the m =1 degree of freedom could potentially reveal details of the equation of state. We analyze the postmerger epoch of simulations of both equal- and nonequal-mass neutron star mergers using three realistic, microphysical equations of state and neutrino cooling. Our studies show such an instability develops generically and within a short dynamical time to strengths that are comparable to or stronger than the m =2 mode, which is the strongest during the early postmerger stage. We estimate the signal to noise ratio that might be obtained for the m =1 mode and discuss the prospects for observing this signal with available Earth-based detectors. Because the m =1 occurs at roughly half the frequency of the more powerful m =2 signal and because it can potentially be long lived, targeted searches could be devised to observe it. We estimate that with constant amplitude direct detection of the mode could occur up to a distance of roughly 14 Mpc, whereas a search triggered by the inspiral signal could extend this distance to roughly 100 Mpc.

  3. The influence of the 2-neutron elastic transfer on the fusion of 42Ca + 40Ca

    NASA Astrophysics Data System (ADS)

    Stefanini, A. M.; Montagnoli, G.; Corradi, L.; Fioretto, E.; Goasduff, A.; Grebosz, J.; Haas, F.; Mazzocco, M.; Scarlassara, F.; Strano, E.

    2016-05-01

    Strong coupling to a single channel with zero Q-value is predicted to produce a characteristic fusion barrier distribution with two peaks, one on each side of the original uncoupled Coulomb barrier. In practical cases, only coupling to an elastic transfer channel may produce such a distribution which, however, has never been observed sofar, probably because low-lying surface vibrations usually have a dominant role, and this may obscure the two-peak structure. The case of the two-neutron (2n) elastic transfer in 42Ca + 40Ca is particularly attractive, because of the relatively rigid nature of the two nuclei. We have measured the fusion excitation function of this system using the 42Ca beam of the XTU Tandem of LNL on a thin 40Ca target enriched to 99.96% in mass 40. Cross sections have been measured down to ≤1 mb. The extracted barrier distribution shows clearly two main peaks. We have performed preliminary CC calculations where the 2+ coupling strengths have been taken from the literature and the schematic 2n pair transfer form factor has been used, with a deformation length σt= 0.39 fm. The excitation function is well reproduced by the calculation including the 2n transfer channel. However, including the octupole excitations destroys the agreement.

  4. 1. Exterior view of Signal Transfer Building (T28A), looking southwest. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Exterior view of Signal Transfer Building (T-28A), looking southwest. This structure houses controls for propellant transfer, instrumentation for testing, test data transmission receivers, data verification equipment, and centralized utilities for the Systems Integration Laboratory complex. The gantries of the Systems Integration Laboratory Building (T-28) are visible to the rear of this structure. - Air Force Plant PJKS, Systems Integration Laboratory, Signal Transfer Building, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

  5. Transmission and signal loss in mask designs for a dual neutron and gamma imager applied to mobile standoff detection

    NASA Astrophysics Data System (ADS)

    Ayaz-Maierhafer, Birsen; Hayward, Jason P.; Ziock, Klaus P.; Blackston, Matthew A.; Fabris, Lorenzo

    2013-06-01

    In order to design a next-generation, dual neutron and gamma imager for mobile standoff detection which uses coded aperture imaging as its primary detection modality, the following design parameters have been investigated for gamma and neutron radiation incident upon a hybrid, coded mask: (1) transmission through mask elements for various mask materials and thicknesses; and (2) signal attenuation in the mask versus angle of incidence. Each of these parameters directly affects detection significance, as quantified by the signal-to-noise ratio. The hybrid mask consists of two or three layers: organic material for fast neutron attenuation and scattering, Cd for slow neutron absorption (if applied), and one of three of the following photon or photon and slow neutron attenuating materials—Linotype alloy, CLYC, or CZT. In the MCNP model, a line source of gamma rays (100-2500 keV), fast neutrons (1000-10,000 keV) or thermal neutrons was positioned above the hybrid mask. The radiation penetrating the mask was simply tallied at the surface of an ideal detector, which was located below the surface of the last mask layer. The transmission was calculated as the ratio of the particles transmitted through the fixed aperture to the particles passing through the closed mask. In order to determine the performance of the mask considering relative motion between the source and detector, simulations were used to calculate the signal attenuation for incident radiation angles of 0-50°. The results showed that a hybrid mask can be designed to sufficiently reduce both transmission through the mask and signal loss at large angles of incidence, considering both gamma ray and fast neutron radiations. With properly selected material thicknesses, the signal loss of a hybrid mask, which is necessarily thicker than the mask required for either single mode imaging, is not a setback to the system's detection significance.

  6. The gravitational-wave signal generated by a galactic population of double neutron-star binaries

    NASA Astrophysics Data System (ADS)

    Yu, Shenghua; Jeffery, C. Simon

    2015-04-01

    We investigate the gravitational wave (GW) signal generated by a population of double neutron-star (DNS) binaries with eccentric orbits caused by kicks during supernova collapse and binary evolution. The DNS population of a standard Milky Way-type galaxy has been studied as a function of star formation history, initial mass function (IMF) and metallicity and of the binary-star common-envelope ejection process. The model provides birthrates, merger rates and total number of DNS as a function of time. The GW signal produced by this population has been computed and expressed in terms of a hypothetical space GW detector (eLISA) by calculating the number of discrete GW signals at different confidence levels, where `signal' refers to detectable GW strain in a given frequency-resolution element. In terms of the parameter space explored, the number of DNS-originating GW signals is greatest in regions of recent star formation, and is significantly increased if metallicity is reduced from 0.02 to 0.001, consistent with Belczynski et al. Increasing the IMF power-law index (from -2.5 to -1.5) increases the number of GW signals by a large factor. This number is also much higher for models where the common-envelope ejection is treated using the α-mechanism (energy conservation) than when using the γ-mechanism (angular-momentum conservation). We have estimated the total number of detectable DNS GW signals from the Galaxy by combining contributions from thin disc, thick disc, bulge and halo. The most probable numbers for an eLISA-type experiment are 0-1600 signals per year at S/N ≥ 1, 0-900 signals per year at S/N ≥ 3, and 0-570 at S/N ≥ 5, coming from about 0-65, 0-60 and 0-50 resolved DNS, respectively.

  7. Experimental study of the 66Ni(d ,p ) 67Ni one-neutron transfer reaction

    NASA Astrophysics Data System (ADS)

    Diriken, J.; Patronis, N.; Andreyev, A.; Antalic, S.; Bildstein, V.; Blazhev, A.; Darby, I. G.; De Witte, H.; Eberth, J.; Elseviers, J.; Fedosseev, V. N.; Flavigny, F.; Fransen, Ch.; Georgiev, G.; Gernhauser, R.; Hess, H.; Huyse, M.; Jolie, J.; Kröll, Th.; Krücken, R.; Lutter, R.; Marsh, B. A.; Mertzimekis, T.; Muecher, D.; Orlandi, R.; Pakou, A.; Raabe, R.; Randisi, G.; Reiter, P.; Roger, T.; Seidlitz, M.; Seliverstov, M.; Sotty, C.; Tornqvist, H.; Van De Walle, J.; Van Duppen, P.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.

    2015-05-01

    The quasi-SU(3) sequence of the positive parity ν g9 /2,d5 /2,s1 /2 orbitals above the N =40 shell gap are assumed to induce strong quadrupole collectivity in the neutron-rich Fe (Z =26 ) and Cr (Z =24 ) isotopes below the nickel region. In this paper the position and strength of these single-particle orbitals are characterized in the neighborhood of 68Ni (Z =28 ,N =40 ) through the 66Ni(d ,p )67Ni one-neutron transfer reaction at 2.95 MeV/nucleon in inverse kinematics, performed at the REX-ISOLDE facility in CERN. A combination of the Miniball γ -array and T-REX particle-detection setup was used and a delayed coincidence technique was employed to investigate the 13.3-μ s isomer at 1007 keV in 67Ni. Excited states up to an excitation energy of 5.8 MeV have been populated. Feeding of the ν g9 /2 (1007 keV) and ν d5 /2 (2207 keV and 3277 keV) positive-parity neutron states and negative parity (ν p f ) states have been observed at low excitation energy. The extracted relative spectroscopic factors, based on a distorted-wave Born approximation analysis, show that the ν d5 /2 single-particle strength is mostly split over these two excited states. The results are also compared to the distribution of the proton single-particle strength in the 90Zr region (Z =40 ,N =50 ) .

  8. Neutron transfer reactions induced by {sup 8}Li on {sup 9}Be

    SciTech Connect

    Guimaraes, V.; Lichtenthaeler, R.; Camargo, O.; Barioni, A.; Assuncao, M.; Kolata, J. J.; Amro, H.; Becchetti, F. D.; Jiang, Hao; Aguilera, E. F.; Lizcano, D.; Martines-Quiroz, E.; Garcia, H.

    2007-05-15

    Angular distributions for the elastic scattering of {sup 8}Li on {sup 9}Be and the neutron transfer reactions {sup 9}Be({sup 8}Li,{sup 7}Li){sup 10}Be and {sup 9}Be({sup 8}Li,{sup 9}Li){sup 8}Be were measured with a 27 MeV {sup 8}Li radioactive nuclear beam. Spectr- oscopic factors for {sup 8}Li (multiply-in-circle sign)n{sup 9}Li and {sup 7}Li (multiply-in-circle sign)n{sup 8}Li bound systems were obtained from the comparison between the experimental differential cross section and finite-range distorted-wave Born approximation calculations with the code FRESCO. The spectroscopic factors obtained were compared to shell model calculations and to other experimental values from (d,p) reactions. Using the present values for the spectroscopic factor, cross sections for the direct neutron-capture reactions {sup 7}Li(n,{gamma}){sup 8}Li and {sup 8}Li(n,{gamma}){sup 9}Li were calculated in the framework of a potential model.

  9. Development of a methodology for analysis of delayed-neutron signals. [LMFBR

    SciTech Connect

    Gross, K. C.; Strain, R. V.; Fryer, R. M.

    1980-02-01

    Experimental and analytical techniques have been developed for analysis and characterization of delayed-neutron (DN) signals that can provide diagnostic information to augment data from cover-gas analyses in the detection and identification of breached elements in an LMFBR. Eleven flow-reduction tests have been run in EBR-II to provide base data support for predicting DN signal characteristics during exposed-fuel operation. Results from the tests demonstrate the feasibility and practicability of response-analysis techniques for determining (a) the transit time, T/sub tr/, for DN emitters traveling from the core to the detector and (b) the isotropic holdup time, T/sub h/, of DN precursors in the fuel element.

  10. Neutrons and the structural biology of second messenger signaling and regulation

    SciTech Connect

    Trewhella, J.

    2004-03-28

    Neutron contrast variation is a powerful technique for studying biomolecular complexes and the conformational flexibility that is inherent in bio-molecular signaling and regulation. We use this technique to study intra-cellular signaling and regulatory mechanisms mediated by second messengers such as calcium and cyclic nucleotides. Our recent results on the multifunctional, multi-subunit cyclic nucleotide-dependent protein kinases as well as kinases that play a role in regulating muscle mechanics will be presented. From this work we see common mechanistic themes in kinase activation as well as distinctive attributes that provide for specificity and functional diversity in this important class of enzymes that catalyze the most common type of reversible protein modification used to modulate protein function.

  11. Possibility of production of neutron-rich Zn and Ge isotopes in multinucleon transfer reactions at low energies

    NASA Astrophysics Data System (ADS)

    Adamian, G. G.; Antonenko, N. V.; Sargsyan, V. V.; Scheid, W.

    2010-02-01

    The production cross sections of new neutron-rich Zn84,86 and Ge90,92 isotopes beyond N=50 are estimated for the first time in the multinucleon transfer reactions Ca48 + U238 and Ca48 + Pu244. The production of new isotopes in reactions with a Ca48 beam is discussed for future experiments.

  12. Evaluation of water transfer from saturated lightweight aggregate to cement paste matrix by neutron radiography

    NASA Astrophysics Data System (ADS)

    Maruyama, I.; Kanematsu, M.; Noguchi, T.; Iikura, H.; Teramoto, A.; Hayano, H.

    2009-06-01

    In high-strength concrete with low water-cement ratio, self-desiccation occurs due to cement hydration and causes shrinkage and an increased risk of cracking. While high-strength concrete has a denser matrix than normal-strength concrete, resulting in lower permeability, early-age cracks would cancel out this advantage. For the mitigation of this self-desiccation and resultant shrinkage, water-saturated porous aggregate, such as artificial lightweight aggregate, may be used in high-strength concrete. In this contribution, for the purpose of clarification of the volume change of high-strength concrete containing water-saturated lightweight aggregate, water transfer from the lightweight aggregate to cement paste matrix is visualized by neutron radiography. As a result, it is clear that water was supplied to the cement paste matrix in the range 3-8 mm from the surface of the aggregate, and the osmotic forces may yield water transfer around lightweight aggregate in a few hours after mixing.

  13. Long-Range Electrostatics-Induced Two-Proton Transfer Captured by Neutron Crystallography in an Enzyme Catalytic Site.

    PubMed

    Gerlits, Oksana; Wymore, Troy; Das, Amit; Shen, Chen-Hsiang; Parks, Jerry M; Smith, Jeremy C; Weiss, Kevin L; Keen, David A; Blakeley, Matthew P; Louis, John M; Langan, Paul; Weber, Irene T; Kovalevsky, Andrey

    2016-04-11

    Neutron crystallography was used to directly locate two protons before and after a pH-induced two-proton transfer between catalytic aspartic acid residues and the hydroxy group of the bound clinical drug darunavir, located in the catalytic site of enzyme HIV-1 protease. The two-proton transfer is triggered by electrostatic effects arising from protonation state changes of surface residues far from the active site. The mechanism and pH effect are supported by quantum mechanics/molecular mechanics (QM/MM) calculations. The low-pH proton configuration in the catalytic site is deemed critical for the catalytic action of this enzyme and may apply more generally to other aspartic proteases. Neutrons therefore represent a superb probe to obtain structural details for proton transfer reactions in biological systems at a truly atomic level.

  14. Long-range electrostatics-induced two-proton transfer captured by neutron crystallography in an enzyme catalytic site

    DOE PAGESBeta

    Gerlits, Oksana; Wymore, Troy; Das, Amit; Shen, Chen -Hsiang; Parks, Jerry M.; Smith, Jeremy C.; Weiss, Kevin L.; Keen, David A.; Blakeley, Matthew P.; Louis, John M.; et al

    2016-03-09

    Neutron crystallography was used to directly locate two protons before and after a pH-induced two-proton transfer between catalytic aspartic acid residues and the hydroxy group of the bound clinical drug darunavir, located in the catalytic site of enzyme HIV-1 protease. The two-proton transfer is triggered by electrostatic effects arising from protonation state changes of surface residues far from the active site. The mechanism and pH effect are supported by quantum mechanics/molecular mechanics (QM/MM) calculations. The low-pH proton configuration in the catalytic site is deemed critical for the catalytic action of this enzyme and may apply more generally to other asparticmore » proteases. Neutrons therefore represent a superb probe to obtain structural details for proton transfer reactions in biological systems at a truly atomic level.« less

  15. Long-Range Electrostatics-Induced Two-Proton Transfer Captured by Neutron Crystallography in an Enzyme Catalytic Site.

    PubMed

    Gerlits, Oksana; Wymore, Troy; Das, Amit; Shen, Chen-Hsiang; Parks, Jerry M; Smith, Jeremy C; Weiss, Kevin L; Keen, David A; Blakeley, Matthew P; Louis, John M; Langan, Paul; Weber, Irene T; Kovalevsky, Andrey

    2016-04-11

    Neutron crystallography was used to directly locate two protons before and after a pH-induced two-proton transfer between catalytic aspartic acid residues and the hydroxy group of the bound clinical drug darunavir, located in the catalytic site of enzyme HIV-1 protease. The two-proton transfer is triggered by electrostatic effects arising from protonation state changes of surface residues far from the active site. The mechanism and pH effect are supported by quantum mechanics/molecular mechanics (QM/MM) calculations. The low-pH proton configuration in the catalytic site is deemed critical for the catalytic action of this enzyme and may apply more generally to other aspartic proteases. Neutrons therefore represent a superb probe to obtain structural details for proton transfer reactions in biological systems at a truly atomic level. PMID:26958828

  16. Studying 10Be and 11Be Halo States through the (p,d) Single-Neutron Transfer Reaction

    NASA Astrophysics Data System (ADS)

    Kuhn, Keri; Sarazin, Fred; (Pcb)2 Collaboration; Tigress Collaboration

    2015-10-01

    One-neutron transfer reactions are being used to study single-particle neutron states in nuclei. For one-neutron halo nuclei, such as 11Be, the (p,d) reaction enables the removal of the halo neutron or of one of the core neutrons. This way, it is possible to simultaneously study the halo wavefunction of the 11Be ground-state but also a possible excited halo state in 10Be. The 11Be(p, d)10Be transfer reaction at 10 MeV/nucleon is being investigated at the TRIUMF-ISAC II facility with the Printed Circuit Board Based Charged Particle ((PCB)2) array inside the TRIUMF ISAC Gamma-Ray Escape-Suppressed Spectrometer (TIGRESS). The ground state and first excited state of 10Be can be directly identified using deuteron identification and kinematics from the charged particle array, while the four excited states in10Be around 6 MeV, including the suspected halo state (2- state), are identified using coincident gamma rays from TIGRESS with the identified deuterons. Angular distributions for the 10Be populated states will be shown along with their FRESCO fits. This work is partially supported by the US Department of Energy through Grant/Contract No. DE-FG03-93ER40789 (Colorado School of Mines).

  17. Pneumatic sample-transfer system for use with the Lawrence Livermore National Laboratory rotating target neutron source (RTNS-I)

    SciTech Connect

    Williams, R.E.

    1981-07-01

    A pneumatic sample-transfer system is needed to be able to rapidly retrieve samples irradiated with 14-MeV neutrons at the Rotating Target Neutron Source (RTNS-I). The rabbit system, already in place for many years, has been refurbished with modern system components controlled by an LSI-11 minicomputer. Samples can now be counted three seconds after an irradiation. There are many uses for this expanded 14-MeV neutron activation capability. Several fission products difficult to isolate from mixed fission fragments can be produced instead through (n,p) or (n,..cap alpha..) reactions with stable isotopes. Mass-separated samples of Nd, Mo, and Se, for example, can be irradiated to produce Pr, Nb, and As radionuclides sufficient for decay scheme studies. The system may also be used for multielement fast-neutron activation analysis because the neutron flux is greater than 2 x 10/sup 11/ n/cm/sup 2/-sec. Single element analyses of Si and O are also possible. Finally, measurements of fast-neutron cross sections producing short-lived activation products can be performed with this system. A description of the rabbit system and instructions for its use are presented in this report.

  18. Production of neutron-rich Ca, Sn, and Xe isotopes in transfer-type reactions with radioactive beams

    SciTech Connect

    Adamian, G. G.; Antonenko, N. V.; Lacroix, D.

    2010-12-15

    The production cross sections of neutron-rich isotopes {sup 52,54,56,58,60}Ca, {sup 136,138,140,142}Sn, and {sup 146,148,150,152}Xe are predicted for future experiments in the diffusive multinucleon transfer reactions {sup 86,90,92,94}Kr, {sup 124,130,132,134}Sn, {sup 136,140,142,146}Xe, and {sup 138,144,146}Ba+{sup 48}Ca with stable and radioactive beams at incident energies close to the Coulomb barrier. Because of the small cross sections, the production of neutron-rich isotopes requires the optimal choice of projectile-target combinations and bombarding energies.

  19. Non-transferable signals on ant queen eggs

    NASA Astrophysics Data System (ADS)

    D'Ettorre, Patrizia; Tofilski, Adam; Heinze, Jürgen; Ratnieks, Francis L. W.

    2006-03-01

    How biological systems resolve internal conflicts is a major evolutionary question. Social insect workers cooperate but also pursue individual interests, such as laying male eggs. The rewards of this individual selfishness can be reduced by policing, such as by killing worker-laid eggs. However, selfish individuals may evade policing. What factors prevent individuals from being able to evade policing? In the ant Pachycondyla inversa, workers kill (police) worker-laid eggs. Because the colony keeps eggs in piles and worker-laid and queen-laid eggs are chemically distinct, worker-laid eggs might become more acceptable once placed in the egg pile by odour transfer from touching queen-laid eggs. Here, we show that such “cue scrambling” does not occur. Worker-laid eggs that were sandwiched between three queen-laid eggs for 45 min were not more acceptable in a policing bioassay than control worker-laid eggs. Chemical analyses also showed that the surface hydrocarbon profile of these eggs was unchanged. Policing, therefore, is stable against this potential cheating mechanism probably because queen-laid eggs are made chemically distinct using chemicals, that are not easily transferred by physical contact.

  20. Optimization of combined delayed neutron and differential die-away prompt neutron signal detection for characterization of spent nuclear fuel assemblies

    SciTech Connect

    Blanc, Pauline; Tobin, Stephen J; Croft, Stephen; Menlove, Howard O; Swinhoe, M; Lee, T

    2010-12-02

    The Next Generation Safeguards Initiative (NGSI) of the U.S. Department of Energy (DOE) has funded multiple laboratories and universities to develop a means to accurately quantify the Plutonium (Pu) mass in spent nuclear fuel assemblies and ways to also detect potential diversion of fuel pins. Delayed Neutron (DN) counting provides a signature somewhat more sensitive to {sup 235}U than Pu while Differential Die-Away (DDA) is complementary in that it has greater sensitivity to Pu. The two methods can, with care, be combined into a single instrument which also provides passive neutron information. Individually the techniques cannot robustly quantify the Pu content but coupled together the information content in the signatures enables Pu quantification separate to the total fissile content. The challenge of merging DN and DDA, prompt neutron (PN) signal, capabilities in the same design is the focus of this paper. Other possibilities also suggest themselves, such as a direct measurement of the reactivity (multiplication) by either the boost in signal obtained during the active interrogation itself or by the extension of the die-away profile. In an early study, conceptual designs have been modeled using a neutron detector comprising fission chambers or 3He proportional counters and a {approx}14 MeV neutron Deuterium-Tritium (DT) generator as the interrogation source. Modeling was performed using the radiation transport code Monte Carlo N-Particles eXtended (MCNPX). Building on this foundation, the present paper quantifies the capability of a new design using an array of {sup 3}He detectors together with fission chambers to optimize both DN and PN detections and active characterization, respectively. This new design was created in order to minimize fission in {sup 238}U (a nuisance DN emitter), to use a realistic neutron generator, to reduce the cost and to achieve near spatial interrogation and detection of the DN and PN, important for detection of diversion, all within

  1. In vessel detection of delayed neutron emitters from clad failure in sodium cooled nuclear reactors: An estimation of the signal

    NASA Astrophysics Data System (ADS)

    Filliatre, P.; Jammes, C.; Chapoutier, N.; Jeannot, J.-P.; Jadot, F.; Batail, R.; Verrier, D.

    2014-04-01

    The detection of clad failures is mandatory in sodium-cooled fast neutron reactors in compliance with the "clean sodium" concept. An in-vessel detection system, sensitive to delayed neutrons from fission products released into the primary coolant by failures, partially tested in SUPERPHENIX, is foreseen in current SFR projects in order to reduce significantly the delay before an alarm is issued. In this paper, an estimation of the signal received by such a system in case of a failure is derived, taking the French project ASTRID as a working example. This failure induced signal is compared to that of the contribution of the neutrons from the core itself. The sensitivity of the system is defined in terms of minimal detectable surface of clad failure. Possible solutions to improve this sensitivity are discussed, involving either the sensor itself, or the hydraulic design of the vessel in the early stage of the reactor conception.

  2. Inferring directional interactions from transient signals with symbolic transfer entropy

    NASA Astrophysics Data System (ADS)

    Martini, Marcel; Kranz, Thorsten A.; Wagner, Tobias; Lehnertz, Klaus

    2011-01-01

    We extend the concept of symbolic transfer entropy to enable the time-resolved investigation of directional relationships between coupled dynamical systems from short and transient noisy time series. For our approach, we consider an observed ensemble of a sufficiently large number of time series as multiple realizations of a process. We derive an index that quantifies the preferred direction of transient interactions and assess its significance using a surrogate-based testing scheme. Analyzing time series from noisy chaotic systems, we demonstrate numerically the applicability and limitations of our approach. Our findings obtained from an analysis of event-related brain activities underline the importance of our method to improve understanding of gross neural interactions underlying cognitive processes.

  3. Insights into the Proton Transfer Mechanism of a Bilin Reductase PcyA Following Neutron Crystallography.

    PubMed

    Unno, Masaki; Ishikawa-Suto, Kumiko; Kusaka, Katsuhiro; Tamada, Taro; Hagiwara, Yoshinori; Sugishima, Masakazu; Wada, Kei; Yamada, Taro; Tomoyori, Katsuaki; Hosoya, Takaaki; Tanaka, Ichiro; Niimura, Nobuo; Kuroki, Ryota; Inaka, Koji; Ishihara, Makiko; Fukuyama, Keiichi

    2015-04-29

    Phycocyanobilin, a light-harvesting and photoreceptor pigment in higher plants, algae, and cyanobacteria, is synthesized from biliverdin IXα (BV) by phycocyanobilin:ferredoxin oxidoreductase (PcyA) via two steps of two-proton-coupled two-electron reduction. We determined the neutron structure of PcyA from cyanobacteria complexed with BV, revealing the exact location of the hydrogen atoms involved in catalysis. Notably, approximately half of the BV bound to PcyA was BVH(+), a state in which all four pyrrole nitrogen atoms were protonated. The protonation states of BV complemented the protonation of adjacent Asp105. The "axial" water molecule that interacts with the neutral pyrrole nitrogen of the A-ring was identified. His88 Nδ was protonated to form a hydrogen bond with the lactam O atom of the BV A-ring. His88 and His74 were linked by hydrogen bonds via H3O(+). These results imply that Asp105, His88, and the axial water molecule contribute to proton transfer during PcyA catalysis. PMID:25872660

  4. Insights into the Proton Transfer Mechanism of a Bilin Reductase PcyA Following Neutron Crystallography.

    PubMed

    Unno, Masaki; Ishikawa-Suto, Kumiko; Kusaka, Katsuhiro; Tamada, Taro; Hagiwara, Yoshinori; Sugishima, Masakazu; Wada, Kei; Yamada, Taro; Tomoyori, Katsuaki; Hosoya, Takaaki; Tanaka, Ichiro; Niimura, Nobuo; Kuroki, Ryota; Inaka, Koji; Ishihara, Makiko; Fukuyama, Keiichi

    2015-04-29

    Phycocyanobilin, a light-harvesting and photoreceptor pigment in higher plants, algae, and cyanobacteria, is synthesized from biliverdin IXα (BV) by phycocyanobilin:ferredoxin oxidoreductase (PcyA) via two steps of two-proton-coupled two-electron reduction. We determined the neutron structure of PcyA from cyanobacteria complexed with BV, revealing the exact location of the hydrogen atoms involved in catalysis. Notably, approximately half of the BV bound to PcyA was BVH(+), a state in which all four pyrrole nitrogen atoms were protonated. The protonation states of BV complemented the protonation of adjacent Asp105. The "axial" water molecule that interacts with the neutral pyrrole nitrogen of the A-ring was identified. His88 Nδ was protonated to form a hydrogen bond with the lactam O atom of the BV A-ring. His88 and His74 were linked by hydrogen bonds via H3O(+). These results imply that Asp105, His88, and the axial water molecule contribute to proton transfer during PcyA catalysis.

  5. A self-consistent method to analyze the effects of the positive Q-value neutron transfers on fusion

    NASA Astrophysics Data System (ADS)

    Jia, H. M.; Lin, C. J.; Yang, L.; Xu, X. X.; Ma, N. R.; Sun, L. J.; Yang, F.; Wu, Z. D.; Zhang, H. Q.; Liu, Z. H.; Wang, D. X.

    2016-04-01

    Considering the present limitation of the need for external parameters to describe the nucleus-nucleus potential and the couplings in the coupled-channels calculations, this work introduces an improved method without adjustable parameter to overcome the limitation and then sort out the positive Q-value neutron transfers (PQNT) effects based on the CCFULL calculations. The corresponding analysis for Ca +Ca, S ,Ca +Sn, and S ,Ca +Zr provides a reliable proof and a quantitative evaluation for the residual enhancement (RE) related to PQNT. In addition, the RE for 32S ,40Ca +94Zr shows an unexpected larger enhancement than 32S ,40Ca +96Zr despite the similar multi-neutron transfer Q-values. This method should rather strictly test the fusion models and be helpful for excavating the underlying physics.

  6. Mass ejection from neutron star mergers: different components and expected radio signals

    NASA Astrophysics Data System (ADS)

    Hotokezaka, Kenta; Piran, Tsvi

    2015-06-01

    In addition to producing a strong gravitational signal, a short gamma-ray burst (GRB), and a compact remnant, neutron star mergers eject significant masses (up to a few per cent of M⊙) at significant kinetic energies. The different components of the ejected mass include a dynamical ejected mass, a GRB jet and also a shock-breakout material, a cocoon resulting from the interaction of the jet with other ejecta, and viscous- and neutrino-driven winds. The interaction of these ejecta with the surrounding interstellar medium will produce a long-lasting radio flare. We estimate here the expected radio flares arising from these outflows. The flares are rather weak and uncertainties in the kinetic energy, the velocity, and the external density make exact estimates of these signals difficult. The relative strength of the different signals depends strongly on the viewing angle. An observer along the jet axis or close to it will detect a strong signal at a few dozen days from the radio afterglow (or the orphan radio afterglow) produced by the highly relativistic GRB jet. A generic observer at larger viewing angles will generally observe the dynamical ejecta, whose contribution peaks a year or so after the event. Depending on the observed frequency and the external density, other components may also give rise to a significant contribution. If the short GRB 130603B was a merger event, its radio flare from the dynamical ejecta might be detectable with the EVLA and the LOFAR for the higher range of external densities n ≳ 0.5 cm-3

  7. Signaling completion of a message transfer from an origin compute node to a target compute node

    DOEpatents

    Blocksome, Michael A.; Parker, Jeffrey J.

    2011-05-24

    Signaling completion of a message transfer from an origin node to a target node includes: sending, by an origin DMA engine, an RTS message, the RTS message specifying an application message for transfer to the target node from the origin node; receiving, by the origin DMA engine, a remote get message containing a data descriptor for the message and a completion notification descriptor, the completion notification descriptor specifying a local direct put transfer operation for transferring data locally on the origin node; inserting, by the origin DMA engine in an injection FIFO buffer, the data descriptor followed by the completion notification descriptor; transferring, by the origin DMA engine to the target node, the message in dependence upon the data descriptor; and notifying, by the origin DMA engine, the application that transfer of the message is complete in dependence upon the completion notification descriptor.

  8. Signaling completion of a message transfer from an origin compute node to a target compute node

    DOEpatents

    Blocksome, Michael A.

    2011-02-15

    Signaling completion of a message transfer from an origin node to a target node includes: sending, by an origin DMA engine, an RTS message, the RTS message specifying an application message for transfer to the target node from the origin node; receiving, by the origin DMA engine, a remote get message containing a data descriptor for the message and a completion notification descriptor, the completion notification descriptor specifying a local memory FIFO data transfer operation for transferring data locally on the origin node; inserting, by the origin DMA engine in an injection FIFO buffer, the data descriptor followed by the completion notification descriptor; transferring, by the origin DMA engine to the target node, the message in dependence upon the data descriptor; and notifying, by the origin DMA engine, the application that transfer of the message is complete in dependence upon the completion notification descriptor.

  9. Possibility of production of neutron-rich Zn and Ge isotopes in multinucleon transfer reactions at low energies

    SciTech Connect

    Adamian, G. G.; Antonenko, N. V.; Sargsyan, V. V.; Scheid, W.

    2010-02-15

    The production cross sections of new neutron-rich {sup 84,86}Zn and {sup 90,92}Ge isotopes beyond N=50 are estimated for the first time in the multinucleon transfer reactions {sup 48}Ca + {sup 238}U and {sup 48}Ca + {sup 244}Pu. The production of new isotopes in reactions with a {sup 48}Ca beam is discussed for future experiments.

  10. Mutant screen distinguishes between residues necessary for light-signal perception and signal transfer by phytochrome B.

    PubMed

    Oka, Yoshito; Matsushita, Tomonao; Mochizuki, Nobuyoshi; Quail, Peter H; Nagatani, Akira

    2008-08-15

    The phytochromes (phyA to phyE) are a major plant photoreceptor family that regulate a diversity of developmental processes in response to light. The N-terminal 651-amino acid domain of phyB (N651), which binds an open tetrapyrrole chromophore, acts to perceive and transduce regulatory light signals in the cell nucleus. The N651 domain comprises several subdomains: the N-terminal extension, the Per/Arnt/Sim (PAS)-like subdomain (PLD), the cGMP phosphodiesterase/adenyl cyclase/FhlA (GAF) subdomain, and the phytochrome (PHY) subdomain. To define functional roles for these subdomains, we mutagenized an Arabidopsis thaliana line expressing N651 fused in tandem to green fluorescent protein, beta-glucuronidase, and a nuclear localization signal. A large-scale screen for long hypocotyl mutants identified 14 novel intragenic missense mutations in the N651 moiety. These new mutations, along with eight previously identified mutations, were distributed throughout N651, indicating that each subdomain has an important function. In vitro analysis of the spectral properties of these mutants enabled them to be classified into two principal classes: light-signal perception mutants (those with defective spectral activity), and signaling mutants (those normal in light perception but defective in intracellular signal transfer). Most spectral mutants were found in the GAF and PHY subdomains. On the other hand, the signaling mutants tend to be located in the N-terminal extension and PLD. These observations indicate that the N-terminal extension and PLD are mainly involved in signal transfer, but that the C-terminal GAF and PHY subdomains are responsible for light perception. Among the signaling mutants, R110Q, G111D, G112D, and R325K were particularly interesting. Alignment with the recently described three-dimensional structure of the PAS-GAF domain of a bacterial phytochrome suggests that these four mutations reside in the vicinity of the phytochrome light-sensing knot.

  11. Discovery of the Shape Coexisting 0{sup +} State in {sup 32}Mg by a Two Neutron Transfer Reaction

    SciTech Connect

    Wimmer, K.; Kroell, T.; Kruecken, R.; Bildstein, V.; Gernhaeuser, R.; Bastin, B.; Bree, N.; Diriken, J.; Van Duppen, P.; Huyse, M.; Patronis, N.; Vermaelen, P.; Voulot, D.; Van de Walle, J.; Wenander, F.; Fraile, L. M.; Chapman, R.; Hadinia, B.; Orlandi, R.; Smith, J. F.

    2010-12-17

    The ''island of inversion'' nucleus {sup 32}Mg has been studied by a (t, p) two neutron transfer reaction in inverse kinematics at REX-ISOLDE. The shape coexistent excited 0{sup +} state in {sup 32}Mg has been identified by the characteristic angular distribution of the protons of the {Delta}L=0 transfer. The excitation energy of 1058 keV is much lower than predicted by any theoretical model. The low {gamma}-ray intensity observed for the decay of this 0{sup +} state indicates a lifetime of more than 10 ns. Deduced spectroscopic amplitudes are compared with occupation numbers from shell-model calculations.

  12. Wire transfer of charge packets for on-chip CCD signal processing

    NASA Astrophysics Data System (ADS)

    Fossum, Eric R.

    A structure for the virtual transfer of charge packets across metal wires is described theoretically and is experimentally verified. The structure is a hybrid of charge-coupled device (CCD) and bucket-brigade device (BBD) elements and permits the topological crossing of charge-domain signals in low power signal processing circuits. A test vehicle consisting of 8-, 32- and 96-stage delay lines of various geometries implemented in a double-poly, double-metal foundry process was used to characterize the wire-transfer operation. Transfer efficiency ranging between 0.998 and 0.999 was obtained for surface n-channel devices with clock cycle times in the range from 40 nsec to 0.3 msec. Transfer efficiency as high as 0.9999 was obtained for buried n-channel devices. Good agreement is found between experiment and simulation.

  13. Signal Delay Stability of a Ku-Band Two-Way Satellite Time Transfer Terminal

    NASA Technical Reports Server (NTRS)

    Kirchner, Dieter; Robnik, R.

    1996-01-01

    A fully automated two-way time and frequency transfer (TWSTFT) system including a satellite simulator, which allows the user to carry out signal delay measurements in conjunction with each time transfer measurement, is operated at the Technical University of Graz (TUG). After a brief description of the system, results obtained during fifteen months of operation are presented and discussed. Finally, envisaged experiments are mentioned.

  14. Transfer functions for protein signal transduction: application to a model of striatal neural plasticity.

    PubMed

    Scheler, Gabriele

    2013-01-01

    We present a novel formulation for biochemical reaction networks in the context of protein signal transduction. The model consists of input-output transfer functions, which are derived from differential equations, using stable equilibria. We select a set of "source" species, which are interpreted as input signals. Signals are transmitted to all other species in the system (the "target" species) with a specific delay and with a specific transmission strength. The delay is computed as the maximal reaction time until a stable equilibrium for the target species is reached, in the context of all other reactions in the system. The transmission strength is the concentration change of the target species. The computed input-output transfer functions can be stored in a matrix, fitted with parameters, and even recalled to build dynamical models on the basis of state changes. By separating the temporal and the magnitudinal domain we can greatly simplify the computational model, circumventing typical problems of complex dynamical systems. The transfer function transformation of biochemical reaction systems can be applied to mass-action kinetic models of signal transduction. The paper shows that this approach yields significant novel insights while remaining a fully testable and executable dynamical model for signal transduction. In particular we can deconstruct the complex system into local transfer functions between individual species. As an example, we examine modularity and signal integration using a published model of striatal neural plasticity. The modularizations that emerge correspond to a known biological distinction between calcium-dependent and cAMP-dependent pathways. Remarkably, we found that overall interconnectedness depends on the magnitude of inputs, with higher connectivity at low input concentrations and significant modularization at moderate to high input concentrations. This general result, which directly follows from the properties of individual transfer

  15. Excited states in neutron-rich 188W produced by an 18O-induced 2-neutron transfer reaction

    NASA Astrophysics Data System (ADS)

    Shizuma, T.; Ishii, T.; Makii, H.; Hayakawa, T.; Shigematsu, S.; Matsuda, M.; Ideguchi, E.; Zheng, Y.; Liu, M.; Morikawa, T.; Walker, P. M.; Oi, M.

    2006-11-01

    Excited states in neutron-rich 188W have been populated using a 186W(18O,16O) reaction. In-beam γ-rays were measured in coincidence with scattered particles detected by a high-resolution ΔE-E Si telescope. In this experiment, the ground-state band has been identified up to I π = 8+. The γ band, the K π = 2- octupole band, and a 2-quasiparticle state were also observed. The results are compared with predictions of self-consistent HFB cranking calculations and blocked-BCS multi-quasiparticle calculations.

  16. Exosome-mediated transfer from the tumor microenvironment increases TGFβ signaling in squamous cell carcinoma.

    PubMed

    Languino, Lucia R; Singh, Amrita; Prisco, Marco; Inman, Gareth J; Luginbuhl, Adam; Curry, Joseph M; South, Andrew P

    2016-01-01

    Transforming growth factor-beta (TGFβ) signaling in cancer is context dependent and acts either as a tumor suppressor or a tumor promoter. Loss of function mutation in TGFβ type II receptor (TβRII) is a frequent event in oral cavity squamous cell carcinoma (SCC). Recently, heterogeneity of TGFβ response has been described at the leading edge of SCC and this heterogeneity has been shown to influence stem cell renewal and drug resistance. Because exosome transfer from stromal to breast cancer cells regulates therapy resistance pathways we investigated whether exosomes contain components of the TGFβ signaling pathway and whether exosome transfer between stromal fibroblasts and tumor cells can influence TGFβ signaling in SCC. We demonstrate that exosomes purified from stromal fibroblasts isolated from patients with oral SCC contains TβRII. We also demonstrate that transfer of fibroblast exosomes increases TGFβ signaling in SCC keratinocytes devoid of TβRII which remain non-responsive to TGFβ ligand in the absence of exosome transfer. Overall our data show that stromal communication with tumor cells can direct TGFβ signaling in SCC. PMID:27347352

  17. Sensitivity Enhancement by Exchange Mediated MagnetizationTransfer of the Xenon Biosensor Signal

    SciTech Connect

    Garcia, Sandra; Chavez, Lana; Lowery, Thomas J.; Han, Song-I.; Wemmer, David E.; Pines, Alexander

    2006-08-31

    Hyperpolarized xenon associated with ligand derivitized cryptophane-A cages has been developed as a NMR based biosensor. To optimize the detection sensitivity we describe use of xenon exchange between the caged and bulk dissolved xenon as an effective signal amplifier. This approach, somewhat analogous to 'remote detection' described recently, uses the chemical exchange to repeatedly transfer spectroscopic information from caged to bulk xenon, effectively integrating the caged signal. After an optimized integration period, the signal is read out by observation of the bulk magnetization. The spectrum of the caged xenon is reconstructed through use of a variable evolution period before transfer and Fourier analysis of the bulk signal as a function of the evolution time.

  18. SEMICONDUCTOR DEVICES: Simulation for signal charge transfer of charge coupled devices

    NASA Astrophysics Data System (ADS)

    Zujun, Wang; Yinong, Liu; Wei, Chen; Benqi, Tang; Zhigang, Xiao; Shaoyan, Huang; Minbo, Liu; Yong, Zhang

    2009-12-01

    Physical device models and numerical processing methods are presented to simulate a linear buried channel charge coupled devices (CCDs). The dynamic transfer process of CCD is carried out by a three-phase clock pulse driver. By using the semiconductor device simulation software MEDICI, dynamic transfer pictures of signal charges cells, electron concentration and electrostatic potential are presented. The key parameters of CCD such as charge transfer efficiency (CTE) and dark electrons are numerically simulated. The simulation results agree with the theoretic and experimental results.

  19. ALARA Review of the Spallation Neutron Source Accumulator Ring and Transfer Lines

    SciTech Connect

    Haire, M.J.

    2003-06-30

    The Spallation Neutron Source (SNS) is designed to meet the growing need for new tools that will deepen our understanding in materials science, life science, chemistry, fundamental and nuclear physics, earth and environmental sciences, and engineering sciences. The SNS is an accelerator-based neutron-scattering facility that when operational will produce an average beam power of 2 MW at a repetition rate of 60 Hz. The accelerator complex consists of the front-end systems, which will include an ion source; a 1-GeV full-energy linear accelerator; a single accumulator ring and its transfer lines; and a liquid mercury target. This report documents an as-low-as-reasonably-achievable (ALARA) review of the accumulator ring and transfer lines at their early design stage. An ALARA working group was formed and conducted a review of the SNS ring and transfer lines at the {approx}25% complete design stage to help ensure that ALARA principles are being incorporated into the design. The radiological aspects of the SNS design criteria were reviewed against regulatory requirements and ALARA principles. Proposed features and measures were then reviewed against the SNS design criteria. As part of the overall review, the working group reviewed the design manual; design drawings and process and instrumentation diagrams; the environment, safety, and health manual; and other related reports and literature. The group also talked with SNS design engineers to obtain explanations of pertinent subject matter. The ALARA group found that ALARA principles are indeed being incorporated into the early design stage. Radiation fields have been characterized, and shielding calculations have been performed. Radiological issues are being adequately addressed with regard to equipment selection, access control, confinement structure and ventilation, and contamination control. Radiation monitoring instrumentation for worker and environment protection are also being considered--a good practice at this

  20. Coulomb Excitation and One-Neutron Transfer Studies of Stable and Radioactive Nuclei at HRIBF-ORNL

    SciTech Connect

    Allmond, James M

    2015-01-01

    Several stable and radioactive nuclei ranging from $A=58$ to 208 were recently studied in inverse kinematics by Coulomb excitation and heavy-ion induced one-neutron transfer at the Holifield Radioactive Ion Beam Facility of Oak Ridge National Laboratory. These studies used a CsI-HPGe detector array to detect scattered charged particles and emitted $\\gamma$ rays from the in-beam reactions. A Bragg-curve detector was used to measure the energy loss of the various beams through the targets and to measure the radioactive beam compositions. Stable nickel, strontium, zirconium, molybdenum, tin, tellurium, and lead isotopes and neutron-rich radioactive tin and tellurium isotopes were among the nuclei recently studied. Coulomb excitation was used to measure the electromagnetic moments of the first excited states and heavy-ion induced one-neutron transfer was used to measure the absolute cross sections and lifetimes of the excited single-particle states. A sample of these results are presented here with an emphasis on the tin isotopes. In particular, a survey of the Bragg-curve measurements, Doppler corrections, and inconclusive $i_{13/2}$ candidate in $^{133}$\\textrm{Sn} are presented.

  1. Proton transfer to flavin stabilizes the signaling state of the blue light receptor plant cryptochrome.

    PubMed

    Hense, Anika; Herman, Elena; Oldemeyer, Sabine; Kottke, Tilman

    2015-01-16

    Plant cryptochromes regulate the circadian rhythm, flowering time, and photomorphogenesis in higher plants as responses to blue light. In the dark, these photoreceptors bind oxidized FAD in the photolyase homology region (PHR). Upon blue light absorption, FAD is converted to the neutral radical state, the likely signaling state, by electron transfer via a conserved tryptophan triad and proton transfer from a nearby aspartic acid. Here we demonstrate, by infrared and time-resolved UV-visible spectroscopy on the PHR domain, that replacement of the aspartic acid Asp-396 with cysteine prevents proton transfer. The lifetime of the radical is decreased by 6 orders of magnitude. This short lifetime does not permit to drive conformational changes in the C-terminal extension that have been associated with signal transduction. Only in the presence of ATP do both the wild type and mutant form a long-lived radical state. However, in the mutant, an anion radical is formed instead of the neutral radical, as found previously in animal type I cryptochromes. Infrared spectroscopic experiments demonstrate that the light-induced conformational changes of the PHR domain are conserved in the mutant despite the lack of proton transfer. These changes are not detected in the photoreduction of the non-photosensory d-amino acid oxidase to the anion radical. In conclusion, formation of the anion radical is sufficient to generate a protein response in plant cryptochromes. Moreover, the intrinsic proton transfer is required for stabilization of the signaling state in the absence of ATP. PMID:25471375

  2. ABC Transporter Required for Intercellular Transfer of Developmental Signals in a Heterocystous Cyanobacterium

    PubMed Central

    Videau, Patrick; Rivers, Orion S.; Higa, Kelly C.

    2015-01-01

    ABSTRACT In the filamentous cyanobacterium Anabaena, patS and hetN encode peptide-derived signals with many of the properties of morphogens. These signals regulate the formation of a periodic pattern of heterocysts by lateral inhibition of differentiation. Here we show that intercellular transfer of the patS- and hetN-dependent developmental signals from heterocysts to vegetative cells requires HetC, a predicted ATP-binding cassette transporter (ABC transporter). Relative to the wild type, in a hetC mutant differentiation resulted in a reduced number of heterocysts that were incapable of nitrogen fixation, but deletion of patS or hetN restored heterocyst number and function in a hetC background. These epistasis results suggest that HetC is necessary for conferring self-immunity to the inhibitors on differentiating cells. Nine hours after induction of differentiation, HetC was required for neither induction of transcription of patS nor intercellular transfer of the patS-encoded signal to neighboring cells. Conversely, in strains lacking HetC, the patS- and hetN-encoded signals were not transferred from heterocyst cells to adjacent vegetative cells. The results support a model in which the patS-dependent signal is initially transferred between vegetative cells in a HetC-independent fashion, but some time before morphological differentiation of heterocysts is complete, transfer of both signals transitions to a HetC-dependent process. IMPORTANCE How chemical cues that regulate pattern formation in multicellular organisms move from one cell to another is a central question in developmental biology. In this study, we show that an ABC transporter, HetC, is necessary for transport of two developmental signals between different types of cells in a filamentous cyanobacterium. ABC transporters are found in organisms as diverse as bacteria and humans and, as the name implies, are often involved in the transport of molecules across a cellular membrane. The activity of HetC was

  3. Near-barrier neutron transfer in reactions 3,6He + 45Sc and 3,6He + 197Au

    NASA Astrophysics Data System (ADS)

    Samarin, V. V.; Naumenko, M. A.; Penionzhkevich, Yu E.; Skobelev, N. K.; Kroha, V.; Mrazek, J.

    2016-06-01

    Experimental cross sections for formation of 196,198Au isotopes in reactions 3,6He + 197Au and cross sections for formation of 44,46Sc isotopes in reactions 3,6He + 45Sc have been analyzed. To calculate neutron transfer probabilities and cross sections the time- dependent Schrödinger equation for external neutrons of 3He, 6He, 45Sc and 197Au nuclei has been solved numerically. It is shown that the contribution of fusion and subsequent evaporation is significant in the case of reactions 3,6He + 45Sc, whereas in the case of reactions 3,6He + 197Au, it is negligible. Fusion-evaporation was taken into account using NRV evaporation code. Results of calculations demonstrate overall satisfactory agreement with experimental data.

  4. Physics of gamma-ray bursts and multi-messenger signals from double neutron star mergers

    NASA Astrophysics Data System (ADS)

    Gao, He

    My dissertation includes two parts: Physics of Gamma-Ray Bursts (GRBs): Gamma-ray bursts are multi-wavelength transients, with both prompt gamma-ray emission and late time afterglow emission observed by telescopes in different wavelengths. I have carried out three investigations to understand GRB prompt emission and afterglow. Chapter 2 develops a new method, namely, "Stepwise Filter Correlation" method, to decompose the variability components in a light curve. After proving its reliability through simulations, we apply this method to 266 bright GRBs and find that the majority of the bursts have clear evidence of superposition of fast and slow variability components. Chapter 3 gives a complete presentation of the analytical approximations for synchrotron self-compton emission for all possible orders of the characteristic synchrotron spectral breaks (nua, nu m, and nuc). We identify a "strong absorption" regime whennua > nuc, and derive the critical condition for this regime. The external shock theory is an elegant theory to model GRB afterglows. It invokes a limit number of model parameters, and has well predicted spectral and temporal properties. Chapter 4 gives a complete reference of all the analytical synchrotron external shock afterglow models by deriving the temporal and spectral indices of all the models in all spectral regimes. This complete reference will serve as a useful tool for afterglow observers to quickly identify relevant models to interpret their data and identify new physics when the models fail. Milti-messenger signals from double neutron star merger: As the multi-messenger era of astronomy ushers in, the second part of the dissertation studies the possible electromagnetic (EM) and neutrino emission counterparts of double neutron star mergers. Chapter 6 suggests that if double neutron star mergers leave behind a massive magnetar rather than a black hole, the magnetar wind could push the ejecta launched during the merger process, and under

  5. Reusable and specific proton transfer signalling by inorganic cyanide in solution and solid phase.

    PubMed

    Kaloo, Masood Ayoub; Sankar, Jeyaraman

    2015-10-01

    A highly specific cyanide mediated proton transfer signalling (PTS) is exhibited by a simple diaminomalenonitrile (DAMN) derivative 1. By virtue of the functional groups on it, the chromophore offered a rigid anchoring on a silica surface via a simple dip method, while retaining the recognition behaviour. The PTS triggered a prompt dual-modal display i.e., chromogenic and fluorogenic. The signal readout can be visualized even in micromolar concentrations. It is noteworthy that PTS can be reversed in both solution and solid phases. The remarkable sensitivity of 1 to detect CN(-) from the solution and solid phase envisages a pivotal step towards field-usable sensing.

  6. Evaluation of the dark signal performance of different SiPM-technologies under irradiation with cold neutrons

    NASA Astrophysics Data System (ADS)

    Durini, Daniel; Degenhardt, Carsten; Rongen, Heinz; Feoktystov, Artem; Schlösser, Mario; Palomino-Razo, Alejandro; Frielinghaus, Henrich; van Waasen, Stefan

    2016-11-01

    In this paper we report the results of the assessment of changes in the dark signal delivered by three silicon photomultiplier (SiPM) detector arrays, fabricated by three different manufacturers, when irradiated with cold neutrons (wavelength λn=5 Å or neutron energy of En=3.27 meV) up to a neutron dose of 6×1012 n/cm2. The dark signals as well as the breakdown voltages (Vbr) of the SiPM detectors were monitored during the irradiation. The system was characterized at room temperature. The analog SiPM detectors, with and without a 1 mm thick Cerium doped 6Li-glass scintillator material located in front of them, were operated using a bias voltage recommended by the respective manufacturer for a proper detector performance. Iout-Vbias measurements, used to determine the breakdown voltage of the devices, were repeated every 30 s during the first hour and every 300 s during the rest of the irradiation time. The digital SiPM detectors were held at the advised bias voltage between the respective breakdown voltage and dark count mappings repeated every 4 min. The measurements were performed on the KWS-1 instrument of the Heinz Maier-Leibnitz Zentrum (MLZ) in Garching, Germany. The two analog and one digital SiPM detector modules under investigation were respectively fabricated by SensL (Ireland), Hamamatsu Photonics (Japan), and Philips Digital Photon Counting (Germany).

  7. Transfer of Neutrons from Deep Below the Fermi Surface via the (p,t) Reaction in the N = 90 Region

    NASA Astrophysics Data System (ADS)

    Humby, P.; Wilson, E.; Beausang, C. W.; Simon, A.; Gell, K.; Tarlow, T.; Vyas, G.; Ross, T. J.; Hughes, R. O.; Burke, J. T.; Casperson, R. J.; Koglin, J.; Ota, S.; Allmond, J. M.; McCleskey, M.; McCleskey, E.; Saastamoinen, A.; Chyzh, R.; Dag, M.

    2015-10-01

    The 152,154Sm(p,t) reactions were used to investigate excited states populated by the transfer of neutrons from deep below the Fermi surface. States corresponding to the transfer of at least one neutron from below the N = 82 shell closure are of particular interest since they provide a sensitive probe of the evolution of the shell closure with increasing deformation. In the present work, large quasi-discrete structures were observed in the triton energy spectra at excitation energies of 2-3 MeV and are interpreted in terms of the underlying Nilsson orbitals. The experiment utilized a 25 MeV proton beam from the K-150 cyclotron at the Cyclotron Institute of Texas A&M University and the outgoing charged particles and γ rays were detected using the STARLiTeR array. This work is supported by the U.S. Department of Energy No. DE-FG02-05ER41379, DE-FG52-09NA29467 and DE-NA0001801, the National Science Foundation under PHY-130581, and by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  8. Simulation of optical configurations and signal processing methods in Anger-type neutron-position scintillation detector

    SciTech Connect

    Roche, C.T.; Strauss, M.G.; Brenner, R.

    1984-01-01

    The spatial linearity and resolution of Anger-type neutron-position scintillation detectors are studied using a semi-empirical model. Detector optics with either an air gap or optical grease between the scintillator and the dispersive light guide are considered. Three signal processing methods which truncate signals from PMT's distant from the scintillation are compared with the linear resistive weighting method. Air gap optics yields a 15% improvement in spatial resolution and 50% reduction in differential and integral nonlinearity relative to grease coupled optics, using linear processing. Using signal truncation instead of linear processing improves the resolution 15-20% for the air gap and 20-30% for the grease coupling case. Thus, the initial discrepancy in the resolution between the two optics nearly vanished, however the linearity of the grease coupled system is still significantly poorer.

  9. Resolution and linearity of Anger-type neutron-position detectors as simulated with different signal processing and optics

    SciTech Connect

    Roche, C.T.; Brenner, R.; Strauss, M.G.

    1985-02-01

    The apatial linearity and resolution of Anger-type neutron-position scintillation detectors are studied using a semi-empirical model. Detector optics with either an air gap or optical grease between the scintillator and the dispersive light guide are considered. An air gap focuses the scintillation light on the photomultiplier tubes nearest the scintillation point. Four signal processing methods which truncate signals from photomultipler tubes distant from the scintillation are compared with the linear resistive weighting method. Using linear processing, air-gap optics yield a 25% improvement in resolution distance and an 80% reduction in integral nonlinearity relative to grease-coupled optics. With either optics, using signal truncation instead of linear processing improves the resolution distance 5-15%.

  10. Simulation of optical configurations and signal processing methods in Anger-type neutron-position scintillation detector

    NASA Astrophysics Data System (ADS)

    Roche, C. T.; Strauss, M. G.; Brenner, R.

    The spatial linearity and resolution of Anger type neutron position scintillation detectors were studied as a semi-empirical model. Detector optics with either an air gap or optical grease between the scintillator and the dispersive light guide are considered. Three signal processing methods which truncate signals from PMT's distant from the scintillation are compared with the linear resistive weighting method. Air gap optics yields a 15% improvement in spatial resolution and 50% reduction in differential and integral nonlinearity relative to grease coupled optics, using linear processing. Using signal truncation instead of linear processing improves the resolution 15% to 20% for the air gap and 20% to 30% for the grease coupling case. The initial discrepancy in the resolution between the two optics nearly vanished, however, the linearity of the grease coupled system is still significantly poorer.

  11. Restoration of β -Adrenergic Signaling in Failing Cardiac Ventricular Myocytes via Adenoviral-Mediated Gene Transfer

    NASA Astrophysics Data System (ADS)

    Akhter, Shahab A.; Skaer, Christine A.; Kypson, Alan P.; McDonald, Patricia H.; Peppel, Karsten C.; Glower, Donald D.; Lefkowitz, Robert J.; Koch, Walter J.

    1997-10-01

    Cardiovascular gene therapy is a novel approach to the treatment of diseases such as congestive heart failure (CHF). Gene transfer to the heart would allow for the replacement of defective or missing cellular proteins that may improve cardiac performance. Our laboratory has been focusing on the feasibility of restoring β -adrenergic signaling deficiencies that are a characteristic of chronic CHF. We have now studied isolated ventricular myocytes from rabbits that have been chronically paced to produce hemodynamic failure. We document molecular β -adrenergic signaling defects including down-regulation of myocardial β -adrenergic receptors (β -ARs), functional β -AR uncoupling, and an upregulation of the β -AR kinase (β ARK1). Adenoviral-mediated gene transfer of the human β 2-AR or an inhibitor of β ARK1 to these failing myocytes led to the restoration of β -AR signaling. These results demonstrate that defects present in this critical myocardial signaling pathway can be corrected in vitro using genetic modification and raise the possibility of novel inotropic therapies for CHF including the inhibition of β ARK1 activity in the heart.

  12. SYSTEMATICS OF DYNAMICAL MASS EJECTION, NUCLEOSYNTHESIS, AND RADIOACTIVELY POWERED ELECTROMAGNETIC SIGNALS FROM NEUTRON-STAR MERGERS

    SciTech Connect

    Bauswein, A.; Janka, H.-T.; Goriely, S.

    2013-08-10

    We investigate systematically the dynamical mass ejection, r-process nucleosynthesis, and properties of electromagnetic counterparts of neutron-star (NS) mergers in dependence on the uncertain properties of the nuclear equation of state (EOS) by employing 40 representative, microphysical high-density EOSs in relativistic, hydrodynamical simulations. The crucial parameter determining the ejecta mass is the radius R{sub 1.35} of a 1.35 M{sub Sun} NS. NSs with smaller R{sub 1.35} (''soft'' EOS) eject systematically higher masses. These range from {approx}10{sup -3} M{sub Sun} to {approx}10{sup -2} M{sub Sun} for 1.35-1.35 M{sub Sun} binaries and from {approx}5 Multiplication-Sign 10{sup -3} M{sub Sun} to {approx}2 Multiplication-Sign 10{sup -2} M{sub Sun} for 1.2-1.5 M{sub Sun} systems (with kinetic energies between {approx}5 Multiplication-Sign 10{sup 49} erg and 10{sup 51} erg). Correspondingly, the bolometric peak luminosities of the optical transients of symmetric (asymmetric) mergers vary between 3 Multiplication-Sign 10{sup 41} erg s{sup -1} and 14 Multiplication-Sign 10{sup 41} erg s{sup -1} (9 Multiplication-Sign 10{sup 41} erg s{sup -1} and 14.5 Multiplication-Sign 10{sup 41} erg s{sup -1}) on timescales between {approx}2 hr and {approx}12 hr. If these signals with absolute bolometric magnitudes from -15.0 to -16.7 are measured, the tight correlation of their properties with those of the merging NSs might provide valuable constraints on the high-density EOS. The r-process nucleosynthesis exhibits a remarkable robustness independent of the EOS, producing a nearly solar abundance pattern above mass number 130. By the r-process content of the Galaxy and the average production per event the Galactic merger rate is limited to 4 Multiplication-Sign 10{sup -5} yr{sup -1} (4 Multiplication-Sign 10{sup -4} yr{sup -1}) for a soft (stiff) NS EOS, if NS mergers are the main source of heavy r-nuclei. The production ratio of radioactive {sup 232}Th to {sup 238}U attains a

  13. Numerical Solution of the Radiative Transfer Equation: X-Ray Spectral Formation from Cylindrical Accretion onto a Magnetized Neutron Star

    NASA Technical Reports Server (NTRS)

    Fairnelli, R.; Ceccobello, C.; Romano, P.; Titarchuk, L.

    2011-01-01

    Predicting the emerging X-ray spectra in several astrophysical objects is of great importance, in particular when the observational data are compared with theoretical models. This requires developing numerical routines for the solution of the radiative transfer equation according to the expected physical conditions of the systems under study. Aims. We have developed an algorithm solving the radiative transfer equation in the Fokker-Planck approximation when both thermal and bulk Comptonization take place. The algorithm is essentially a relaxation method, where stable solutions are obtained when the system has reached its steady-state equilibrium. Methods. We obtained the solution of the radiative transfer equation in the two-dimensional domain defined by the photon energy E and optical depth of the system pi using finite-differences for the partial derivatives, and imposing specific boundary conditions for the solutions. We treated the case of cylindrical accretion onto a magnetized neutron star. Results. We considered a blackbody seed spectrum of photons with exponential distribution across the accretion column and for an accretion where the velocity reaches its maximum at the stellar surface and at the top of the accretion column, respectively. In both cases higher values of the electron temperature and of the optical depth pi produce flatter and harder spectra. Other parameters contributing to the spectral formation are the steepness of the vertical velocity profile, the albedo at the star surface, and the radius of the accretion column. The latter parameter modifies the emerging spectra in a specular way for the two assumed accretion profiles. Conclusions. The algorithm has been implemented in the XPEC package for X-ray fitting and is specifically dedicated to the physical framework of accretion at the polar cap of a neutron star with a high magnetic field (approx > 10(exp 12) G). This latter case is expected to be of typical accreting systems such as X

  14. Momentum and energy dependent resolution function of the ARCS neutron chopper spectrometer at high momentum transfer: Comparing simulation and experiment

    NASA Astrophysics Data System (ADS)

    Diallo, S. O.; Lin, J. Y. Y.; Abernathy, D. L.; Azuah, R. T.

    2016-11-01

    Inelastic neutron scattering at high momentum transfers (i.e. Q ≥ 20 A ˚), commonly known as deep inelastic neutron scattering (DINS), provides direct observation of the momentum distribution of light atoms, making it a powerful probe for studying single-particle motions in liquids and solids. The quantitative analysis of DINS data requires an accurate knowledge of the instrument resolution function Ri(Q , E) at each momentum Q and energy transfer E, where the label i indicates whether the resolution was experimentally observed i = obs or simulated i=sim. Here, we describe two independent methods for determining the total resolution function Ri(Q , E) of the ARCS neutron instrument at the Spallation Neutron Source, Oak Ridge National Laboratory. The first method uses experimental data from an archetypical system (liquid 4He) studied with DINS, which are then numerically deconvoluted using its previously determined intrinsic scattering function to yield Robs(Q , E). The second approach uses accurate Monte Carlo simulations of the ARCS spectrometer, which account for all instrument contributions, coupled to a representative scattering kernel to reproduce the experimentally observed response S(Q , E). Using a delta function as scattering kernel, the simulation yields a resolution function Rsim(Q , E) with comparable lineshape and features as Robs(Q , E), but somewhat narrower due to the ideal nature of the model. Using each of these two Ri(Q , E) separately, we extract characteristic parameters of liquid 4He such as the intrinsic linewidth α2 (which sets the atomic kinetic energy < K > ∼α2) in the normal liquid and the Bose-Einstein condensate parameter n0 in the superfluid phase. The extracted α2 values agree well with previous measurements at saturated vapor pressure (SVP) as well as at elevated pressure (24 bars) within experimental precision, independent of which Ri(Q , y) is used to analyze the data. The actual observed n0 values at each Q vary little

  15. Pseudorandom signals to estimate apparent transfer and coherence functions of nonlinear systems: applications to respiratory mechanics.

    PubMed

    Suki, B; Lutchen, K R

    1992-11-01

    There is an increasing need in physiology to estimate nonparametric linear transfer functions from data originating from biological systems which are invariably nonlinear. For pseudorandom (PRN) input stimuli, we derive general expressions for the apparent transfer (Z) and coherence (gamma 2) functions of nonlinear systems that can be represented by a Volterra series. It is shown that in the case of PRN signals in which the frequency components are integer multiples of other components the estimates of Z are seriously biased due to harmonic distortion and crosstalk among frequency components of the input. When the PRN signal includes components that are not integer multiples of other components harmonic distortion is avoided, but not necessarily cross talk. Here the estimates of Z remain poor without a noticeable influence on gamma 2. To avoid the problems associated with harmonic distortions and minimize the influence of crosstalk, a family of pseudorandom signals is proposed which are especially suited for the estimation of Z and gamma 2 in mechanical measurements of physiological systems at low frequencies. The components in the signals cannot be reproduced as linear combinations of two or more frequency components of the input. In a second-order system, this completely eliminates the bias, while in higher-order, but not strongly nonlinear systems, the interactions among the components are reduced to a level that the response can be considered as if it was measured with independent sine waves of an equivalent amplitude. It is also shown that the values of gamma 2 are not appropriate to assess linearity of the system. The theory is supported by simulation results and experimental examples brought from the field of respiratory mechanics by comparing the input impedance of the respiratory system of a dog measured with various PRN signals. PMID:1487277

  16. Hijacking common mycorrhizal networks for herbivore-induced defence signal transfer between tomato plants

    PubMed Central

    Song, Yuan Yuan; Ye, Mao; Li, Chuanyou; He, Xinhua; Zhu-Salzman, Keyan; Wang, Rui Long; Su, Yi Juan; Luo, Shi Ming; Zeng, Ren Sen

    2014-01-01

    Common mycorrhizal networks (CMNs) link multiple plants together. We hypothesized that CMNs can serve as an underground conduit for transferring herbivore-induced defence signals. We established CMN between two tomato plants in pots with mycorrhizal fungus Funneliformis mosseae, challenged a ‘donor' plant with caterpillar Spodoptera litura, and investigated defence responses and insect resistance in neighbouring CMN-connected ‘receiver' plants. After CMN establishment caterpillar infestation on ‘donor' plant led to increased insect resistance and activities of putative defensive enzymes, induction of defence-related genes and activation of jasmonate (JA) pathway in the ‘receiver' plant. However, use of a JA biosynthesis defective mutant spr2 as ‘donor' plants resulted in no induction of defence responses and no change in insect resistance in ‘receiver' plants, suggesting that JA signalling is required for CMN-mediated interplant communication. These results indicate that plants are able to hijack CMNs for herbivore-induced defence signal transfer and interplant defence communication. PMID:24468912

  17. Radiation linear energy transfer and drop size dependence of the low frequency signal from tiny superheated droplets

    NASA Astrophysics Data System (ADS)

    Seth, Susnata; Das, Mala

    2016-11-01

    The bubble nucleation in superheated tiny droplets of R-12 (CCl2F2, boiling point: -29.8 °C) induced by neutrons and α-particles has been observed using condenser microphone as an acoustic sensor. The superheated droplets used in these experiments are of very small radii having distribution with main peak around 2-3 μm expanding until about 40 μm. The low frequency component of the acoustic shock wave released during bubble nucleation has been measured with condenser microphone and the analysis has been done using ROOT software. Pulses due to bubble nucleation have been recorded in the presence of 241Am-Be neutron source (few keV to about 10 MeV) and 241Am alpha-source (5.48 MeV with intensity 85.2%). The observables related to the power associated with bubble nucleation (P) and the area under the frequency spectrum of the signal (PFreq) have been estimated for the α-particle and neutron induced events. It shows that the α-particle induced bubble nucleation signals are of lower intensity than those obtained from the neutron induced bubble nucleation signals. This phenomenon as observed with tiny droplets is opposite to that observed so far for the larger droplets.

  18. Describing the signal-transfer characteristics of asymmetrical radiographic screen-film systems.

    PubMed

    Van Metter, R

    1992-01-01

    The measurement of modulation transfer function for radiographic screen-film systems depends critically upon a proper linearization of the measured line spread function. This is normally done by photographic photometry (i.e., using the measured density versus log exposure relationship to transform the density line spread function into an exposure line spread function). It has been long appreciated that this procedure may fail for asymmetrical dual screen systems that use film with emulsion coated on both sides of the support. The advent of asymmetrical and near-zero crossover films that can be used with highly asymmetric screen pairs has prompted a reinvestigation of these concerns about the definition and measurement of modulation transfer function. For such cases, it is useful to define the contrast transfer function, which is a function of exposure and spatial frequency. When normalized by its zero frequency value the contrast transfer function can serve as the "effective MTF" for low-contrast input signals in such systems. In the limit of symmetrical systems this quantity approaches the conventionally measured MTF. The utility of this approach is demonstrated by applying it to a commercially available asymmetrical screen-film combination.

  19. Relevance of single-particle and collective excitations in zirconium isotopes populated by neutron transfer reactions in the {sup 90}Zr+{sup 208}Pb system

    SciTech Connect

    Pajtler, M. Varga; Szilner, S.; Malenica, D. Jelavić; Mijatović, T.; Soić, N.; Corradi, L.; Angelis, G. de; Fioretto, E.; Montanari, D.; Stefanini, A. M.; Valiente-Dobón, J. J.; Gadea, A.; Haas, F.; Lunardi, S.; Mengoni, D.; Montagnoli, G.; Recchia, F.; Scarlassara, F.; Märginean, N.; Pollarolo, G.; and others

    2015-10-15

    Multineutron transfer reaction {sup 90}Zr+{sup 208}Pb has been studied at the energy close to the Coulomb barrier energy by using the PRISMA + CLARA set-up. In this fragment-γ coincidence measurement, the selective properties of the reaction mechanism in the population of the specific states have been discussed. Based on the observed γ transitions of neutron transfer channels, namely {sup 89–94}Zr isotopes, their level schemes have been constructed and updated.

  20. [Disease resistance signal transfer between roots of different tomato plants through common arbuscular mycorrhiza networks].

    PubMed

    Xie, Li-Jun; Song, Yuan-Yuan; Zeng, Ren-Sen; Wang, Rui-Long; Wei, Xiao-Chen; Ye, Mao; Hu, Lin; Zhang, Hui

    2012-05-01

    Common mycorrhizal networks (CMNs) are the underground conduits of nutrient exchange between plants. However, whether the CMNs can serve as the underground conduits of chemical communication to transfer the disease resistance signals between plants are unknown. By inoculating arbuscular mycorrhizal fungus (AMF) Glomus mosseae to establish CMNs between 'donor' and 'receiver' tomato plants, and by inoculating Alternaria solani, the causal agent of tomato early blight disease, to the 'donor' plants, this paper studied whether the potential disease resistance signals can be transferred between the 'donor' and 'receiver' plants roots. The real time RT-PCR analysis showed that after inoculation with A. solani, the AMF-inoculated 'donor' plants had strong expression of three test defense-related genes in roots, with the transcript levels of the phenylalanine ammonia-lyase (PAL), lipoxygenase (LOX) and chitinase (PR3) being significantly higher than those in the roots of the 'donor' plants only inoculated with A. solani, not inoculated with both A. solani and AMF, and only inoculated with AMF. More importantly, in the presence of CMNs, the expression levels of the three genes in the roots of the 'receiver' plants were significantly higher than those of the 'receiver' plants without CMNs connection, with the connection blocking, and with the connection but the 'donor' plants not A. solani-inoculated. Compared with the control (without CMNs connection), the transcript level of the PAL, LOX and PR3 in the roots of the 'receiver' plants having CMNs connection with the 'donor' plants was 4.2-, 4.5- and 3.5-fold higher, respectively. In addition, the 'donor' plants activated their defensive responses more quickly than the 'receiver' plants (18 and 65 h vs. 100 and 140 h). These findings suggested that the disease resistance signals produced by the pathogen-induced 'donor' tomato plant roots could be transferred to the 'receiver' plant roots through CMNs.

  1. Dosimetry for Neutrons from 0.25 to 15 MeV by the Measurement of Linear Energy Transfer Distributions for Secondary Charged Particles in CR-39 Plastic

    NASA Astrophysics Data System (ADS)

    Tawara, Hiroko; Eda, Kazuyoshi; Sanami, Toshiya; Sasaki, Shinichi; Takahashi, Kazutoshi; Sonkawade, Rajendra; Nagamatsu, Aiko; Kitajo, Keiichi; Kumagai, Hidenori; Doke, Tadayoshi

    2008-03-01

    In the radiation fields of high energy accelerator facilities, high-altitude aircraft and space flights, high-energy neutron dosimetry of ˜20 MeV or more is a significant issue for radiological protection. We studied the feasibility of experimental measurements of linear energy transfer (LET) distributions for secondary charged particles induced by fast neutrons using CR-39 plastic nuclear track detectors. In order to investigate a method of analyzing the CR-39 detectors that is appropriate for fast neutron dosimetry, two-layer CR-39 stacks were exposed to monochromatic neutrons (0.25, 0.55, 5, and 15 MeV) at the Fast Neutron Laboratory of Tohoku University in Japan. We also conducted Monte Carlo calculations to estimate the detection efficiency of the CR-39 detector for recoil protons. The CR-39 detectors treated by single-step chemical etching were used to obtain LET distributions for LET > 10 keV/µm-water. The results indicated that measurements of short-range particles are very important for obtaining the correct LET distributions. Using the measured LET distributions, we calculated neutron sensitivities, absorbed doses and dose equivalents based on the ICRP 60 Q-L relation and averaged quality factors. The dose equivalents were compared with the neutron fluence-to-dose equivalent conversion factors given by ICRP 74 and the averaged quality factors were compared with weighting factors given by ICRP 60 and ICRP 92.

  2. Predicted yields of new neutron-rich isotopes of nuclei with Z=64-80 in the multinucleon transfer reaction {sup 48}Ca+{sup 238}U

    SciTech Connect

    Adamian, G. G.; Antonenko, N. V.; Sargsyan, V. V.; Scheid, W.

    2010-05-15

    The production cross sections of new neutron-rich isotopes of nuclei with charge numbers Z=64-80 are estimated for future experiments in the multinucleon transfer reaction {sup 48}Ca+{sup 238}U at bombarding energy E{sub c.m.}=189 MeV close to the Coulomb barrier.

  3. Computer program /P1-GAS/ calculates the P-0 and P-1 transfer matrices for neutron moderation in a monatomic gas

    NASA Technical Reports Server (NTRS)

    Collier, G.; Gibson, G.

    1968-01-01

    FORTRAN 4 program /P1-GAS/ calculates the P-O and P-1 transfer matrices for neutron moderation in a monatomic gas. The equations used are based on the conditions that there is isotropic scattering in the center-of-mass coordinate system, the scattering cross section is constant, and the target nuclear velocities satisfy a Maxwellian distribution.

  4. Neutron background signal in superheated droplet detectors of the Phase II SIMPLE dark matter search

    NASA Astrophysics Data System (ADS)

    Fernandes, A. C.; Kling, A.; Felizardo, M.; Girard, T. A.; Ramos, A. R.; Marques, J. G.; Prudêncio, M. I.; Marques, R.; Carvalho, F. P.; Roche, I. L.

    2016-03-01

    The simulation of the neutron background for Phase II of the SIMPLE direct dark matter search experiment is fully reported with various improvements relative to previous estimates. The model employs the Monte Carlo MCNP neutron transport code, using as input a realistic geometry description, measured radioassays and material compositions, and tabulated (α,n) yields and spectra. Developments include the accounting of recoil energy distributions, consideration of additional reactions and materials and examination of the relevant (α,n) data. A thorough analysis of the simulation results is performed that addresses an increased number of non-statistical uncertainties. The referred omissions are seen to provide a net increase of 13% in the previously-reported background estimates whereas the non-statistical uncertainty rises to 25%. The final estimated recoil event rate is 0.372 ± 0.002 (stat.) ± 0.097 (non-stat.) evt/kgd resulting in insignificant changes over the results of the experiment.

  5. Identification of High Energy Solar Particle Signals on the Mexico City Neutron Monitor Database

    NASA Astrophysics Data System (ADS)

    Valdes-Galicia, J. F.; Vargas-Cardenas, B.

    2012-12-01

    We performed a search for ground level solar cosmic ray enhancements on the full five minute database of the Mexico City neutron monitor using wavelet filters and two different statistical tests. We present a detailed analysis of the time series of November 2, 1992, where we found a previously unreported increment matching the onset time of the impulsive phase of GLE 54, thus providing evidence of an effective detection of high energy solar cosmic rays.

  6. The inelastic neutron scattering spectrum of chromous acid at high energy transfers

    NASA Astrophysics Data System (ADS)

    Tomkinson, J.; Taylor, A. D.; Howard, J.; Eckert, J.; Goldstone, J. A.

    1985-02-01

    The inelastic incoherent neutron scattering spectrum of chromous acid, at 77 K, is presented. It is dominated by the intense bending mode at 1254 cm-1 with some modes at lower frequencies showing indications of dispersion. The antisymmetric stretch νas(OHS) {‖1>-‖2>} was assigned to a broad band centered at ˜2050 cm-1, significantly displaced for the IR assignment (1650 cm-1). The breadth of the band is due to the dispersion, and kinematic coupling, that is anticipated for this compound. These new data allows us to fit chromous acid more clearly into the general trend of hydrogen bonded compounds. Chromous acid compares very well in its overall INS spectrum with the isomorphous sodium bifluoride, except that the kinematic coupling between νas(OHO) and the symmetric stretch does not occur in this compound.

  7. Neutron induced bystander effect among zebrafish embryos

    NASA Astrophysics Data System (ADS)

    Ng, C. Y. P.; Kong, E. Y.; Kobayashi, A.; Suya, N.; Uchihori, Y.; Cheng, S. H.; Konishi, T.; Yu, K. N.

    2015-12-01

    The present paper reported the first-ever observation of neutron induced bystander effect (NIBE) using zebrafish (Danio rerio) embryos as the in vivo model. The neutron exposure in the present work was provided by the Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) facility at the National Institute of Radiological Sciences (NIRS), Chiba, Japan. Two different strategies were employed to induce NIBE, namely, through directly partnering and through medium transfer. Both results agreed with a neutron-dose window (20-50 mGy) which could induce NIBE. The lower dose limit corresponded to the threshold amount of neutron-induced damages to trigger significant bystander signals, while the upper limit corresponded to the onset of gamma-ray hormesis which could mitigate the neutron-induced damages and thereby suppress the bystander signals. Failures to observe NIBE in previous studies were due to using neutron doses outside the dose-window. Strategies to enhance the chance of observing NIBE included (1) use of a mono-energetic high-energy (e.g., between 100 keV and 2 MeV) neutron source, and (2) use of a neutron source with a small gamma-ray contamination. It appeared that the NASBEE facility used in the present study fulfilled both conditions, and was thus ideal for triggering NIBE.

  8. Regulatory function of Arabidopsis lipid transfer protein 1 (LTP1) in ethylene response and signaling.

    PubMed

    Wang, Honglin; Sun, Yue; Chang, Jianhong; Zheng, Fangfang; Pei, Haixia; Yi, Yanjun; Chang, Caren; Dong, Chun-Hai

    2016-07-01

    Ethylene as a gaseous plant hormone is directly involved in various processes during plant growth and development. Much is known regarding the ethylene receptors and regulatory factors in the ethylene signal transduction pathway. In Arabidopsis thaliana, REVERSION-TO-ETHYLENE SENSITIVITY1 (RTE1) can interact with and positively regulates the ethylene receptor ETHYLENE RESPONSE1 (ETR1). In this study we report the identification and characterization of an RTE1-interacting protein, a putative Arabidopsis lipid transfer protein 1 (LTP1) of unknown function. Through bimolecular fluorescence complementation, a direct molecular interaction between LTP1 and RTE1 was verified in planta. Analysis of an LTP1-GFP fusion in transgenic plants and plasmolysis experiments revealed that LTP1 is localized to the cytoplasm. Analysis of ethylene responses showed that the ltp1 knockout is hypersensitive to 1-aminocyclopropanecarboxylic acid (ACC), while LTP1 overexpression confers insensitivity. Analysis of double mutants etr1-2 ltp1 and rte1-3 ltp1 demonstrates a regulatory function of LTP1 in ethylene receptor signaling through the molecular association with RTE1. This study uncovers a novel function of Arabidopsis LTP1 in the regulation of ethylene response and signaling. PMID:27097903

  9. General-relativistic simulations of binary black hole-neutron stars: Precursor electromagnetic signals

    NASA Astrophysics Data System (ADS)

    Paschalidis, Vasileios; Etienne, Zachariah B.; Shapiro, Stuart L.

    2013-07-01

    We perform the first general relativistic force-free simulations of neutron star magnetospheres in orbit about spinning and nonspinning black holes. We find promising precursor electromagnetic emission: typical Poynting luminosities at, e.g., an orbital separation of r=6.6RNS are LEM˜6×1042(BNS,p/1013G)2(MNS/1.4M⊙)2erg/s. The Poynting flux peaks within a broad beam of ˜40° in the azimuthal direction and within ˜60° from the orbital plane, establishing a possible lighthouse effect. Our calculations, though preliminary, preview more detailed simulations of these systems that we plan to perform in the future.

  10. Hormone-induced intercellular signal transfer dissociates cyclic AMP- dependent protein kinase

    PubMed Central

    1984-01-01

    We used co-cultures of porcine ovarian granulosa cells and mouse adrenocortical tumor cells (Y-1) to examine the kinetics of contact- dependent intercellular signal transfer and to assess the molecular mechanisms employed by this process. Exposure to follicle-stimulating hormone (FSH) caused cAMP-dependent protein kinase dissociation in granulosa cells and, with time, in Y-1 cells if, and only if, they contacted a responding granulosa cell. Y-1 cells close to a granulosa cell but not touching it failed to respond similarly. In reciprocal experiments, co-cultures were stimulated with adrenocorticotropic hormone (ACTH). Y-1 cells dissociated protein kinase as did granulosa cells in contact with Y-1 cells; however, granulosa cells that were not in contact with Y-1 cells failed to respond to the hormone. Fluorogenic steroids were secreted by Y-1 cells cultured alone and stimulated with ACTH, but were not secreted by cultures exposed to FSH. Neither hormone caused fluorogenic steroid production by granulosa cells. On the other hand these steroids were secreted in co-cultures stimulated with ACTH and to a lesser degree in co-cultures exposed to FSH. Autoradiography revealed that I125-FSH bound only to granulosa cells, never to Y-1 cells, even if they were in contact with an ovarian cell. The possibility of cell fusion was tested by experiments in which Y-1 cell membranes were labeled with cationized ferritin. These cells were then placed in co-culture with ovarian granulosa cells that had previously been allowed to ingest latex spheres. At regions of gap junctions between Y-1 and granulosa cells ferritin remained attached to the adrenal cell membrane and was never observed to migrate to the granulosa cell membrane. From these data, we conclude that hormone specific stimulation of one cell type leads to protein kinase dissociation in heterotypic partners only if they contact a hormone responsive cell. This signal transfer is bidirectional, exhibits temporal kinetics and

  11. Human machine interaction via the transfer of power and information signals

    NASA Technical Reports Server (NTRS)

    Kazerooni, H.; Foslien, W. K.; Anderson, B. J.; Hessburg, T. M.

    1989-01-01

    Robot manipulators are designed to perform tasks which would otherwise be executed by a human operator. No manipulator can even approach the speed and accuracy with which humans execute these tasks. But manipulators have the capability to exceed human ability in one particular area: strength. Through any reasonable observation and experience, the human's ability to perform a variety of physical tasks is limited not by his intelligence, but by his physical strength. If, in the appropriate environment, we can more closely integrate the mechanical power of a machine with intellectually driven human hand under the supervisory control of the human's intellect, we will then have a system which is superior to a loosely-integrated combination of a human and his fully automated robot as in the present day robotic systems. We must therefore develop a fundamental approach to the problem of this extending human mechanical power in certain environments. Extenders will be a class of robots worn by humans to increase human mechanical ability, while the wearer's intellect remains the central intelligent control system for manipulating the extender. The human body, in physical contact with the extender, exchanges information signals and power with the extender. Commands are transferred to the extender via the contact forces between the wearer and the extender as opposed to use of joystick (master arm), push-button or key-board to execute such commands that were used in previous man amplifiers. Instead, the operator becomes an integral part of the extender while executing the task. In this unique configuration the mechanical power transfer between the human and extender occurs in addition to information signal transfer. When the wearer uses the extender to touch and manipulate an object, the extender transfers to the wearer's hand, in feedback fashion, a scaled-down value of the actual external load which the extender is manipulating. This natural feedback force on the wearer's hand

  12. Single Neutron Transfer Experiments Close to the r-Process Path

    SciTech Connect

    Grzywacz-Jones, Kate L; Adekola, Aderemi S; Bardayan, Daniel W; Blackmon, Jeff C; Chae, Kyung Yuk; Chipps, K.; Cizewski, Jolie; Dean, David Jarvis; Erikson, Luke; Fitzgerald, R. P.; Gaddis, A. L.; Greife, U.; Harlin, Christopher W; Hatarik, Robert; Howard, Joshua A; Johnson, Micah; Kozub, R. L.; Liang, J Felix; Livesay, Jake; Ma, Zhanwen; Moazen, Brian; O'Malley, Patrick; Nesaraja, Caroline D; Pain, S. D.; Patterson, N. P.; Paulauskas, Stanley V; Shapira, Dan; ShrinerJr., J. F.; Sissom, D. J.; Smith, Michael Scott; Swan, T. P.; Thomas, J. S.

    2007-01-01

    The first measurements using the (d, p) transfer reaction to study single- particle states in nuclei on the expected r-process path have been made at the Holifield Radioactive Ion Beam Facility. The shell closure at N = 50 has been crossed using the 82Ge(d, p) and 84Se(d, p) reactions. The prop- erties of the lowest-lying states have been determined. Furthermore, the 132Sn(d, p) reaction has been used for the first time to populate single- particle states in 133Sn.

  13. Neutron detector

    DOEpatents

    Stephan, Andrew C.; Jardret; Vincent D.

    2011-04-05

    A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

  14. Neutron detector

    SciTech Connect

    Stephan, Andrew C; Jardret, Vincent D

    2009-04-07

    A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

  15. Joint transfer of time and frequency signals and multi-point synchronization via fiber network

    NASA Astrophysics Data System (ADS)

    Nan, Cheng; Wei, Chen; Qin, Liu; Dan, Xu; Fei, Yang; You-Zhen, Gui; Hai-Wen, Cai

    2016-01-01

    A system of jointly transferring time signals with a rate of 1 pulse per second (PPS) and frequency signals of 10 MHz via a dense wavelength division multiplex-based (DWDM) fiber is demonstrated in this paper. The noises of the fiber links are suppressed and compensated for by a controlled fiber delay line. A method of calibrating and characterizing time is described. The 1PPS is synchronized by feed-forward calibrating the fiber delays precisely. The system is experimentally examined via a 110 km spooled fiber in laboratory. The frequency stabilities of the user end with compensation are 1.8×10-14 at 1 s and 2.0×10-17 at 104 s average time. The calculated uncertainty of time synchronization is 13.1 ps, whereas the direct measurement of the uncertainty is 12 ps. Next, the frequency and 1PPS are transferred via a metropolitan area optical fiber network from one central site to two remote sites with distances of 14 km and 110 km. The frequency stabilities of 14 km link reach 3.0×10-14 averaged in 1 s and 1.4×10-17 in 104 s respectively; and the stabilities of 110 km link are 8.3×10-14 and 1.7×10-17, respectively. The accuracies of synchronization are estimated to be 12.3 ps for the 14 km link and 13.1 ps for the 110 km link, respectively. Project supported by the National Natural Science Foundation of China (Grant No. 61405227).

  16. Nanoluciferase signal brightness using furimazine substrates opens bioluminescence resonance energy transfer to widefield microscopy.

    PubMed

    Kim, Jiho; Grailhe, Regis

    2016-08-01

    Fluorescence and bioluminescence resonance energy transfer (FRET, BRET) techniques are powerful tools for studying protein-protein interactions in cellular assays. In contrast to fluorescent proteins, chemiluminescent proteins do not require excitation light, known to trigger autofluorescence, phototoxicity, and photobleaching. Regrettably, low signal intensity of luciferase systems restricts their usage as they require specialized microscopes equipped with ultra low-light imaging cameras. In this study, we report that bioluminescence quantification in living cells using a standard widefield automated microscope dedicated to screening and high content analysis is possible with the newer luciferase systems, Nanoluciferase (Nluc). With such equipment, we showed that robust intramolecular BRET can be measured using a combination of Nluc and yellow fluorescent protein (YFP). Using the human Superoxide Dismutase 1 (SOD1) dimer model, we next validated that intermolecular BRET could be quantified at a single cell level. The enhanced signal brightness of Nluc enabling BRET imaging to widefield microscopy shows strong potential to open up single cell protein-protein interactions studies to a wider audience. © 2016 International Society for Advancement of Cytometry.

  17. Lyman-alpha radiative transfer during the epoch of reionization: contribution to 21-cm signal fluctuations

    NASA Astrophysics Data System (ADS)

    Semelin, B.; Combes, F.; Baek, S.

    2007-11-01

    During the epoch of reionization, Ly-α photons emitted by the first stars can couple the neutral hydrogen spin temperature to the kinetic gas temperature, providing an opportunity to observe the gas in emission or absorption in the 21-cm line. Given the bright foregrounds, it is particularly important to determine the fluctuation signature of the signal precisely, so as to be able to extract it by its correlation power. LICORICE is a Monte-Carlo radiative transfer code, coupled to the dynamics via an adaptative Tree-SPH code. We present here the Ly-α part of the implementation and validate it through three classical tests. Unlike previous works, we do not assume that P_α, the number of scatterings of Ly-α photons per atom per second, is proportional to the Ly-α background flux, but take the scatterings in the Ly-α line wings into account. The latter have the effect of steepening the radial profile of P_α around each source, and re-inforce the contrast of the fluctuations. In the particular geometry of cosmic filaments of baryonic matter, Ly-α photons are scattered out of the filament, and the large-scale structure of P_α is significantly anisotropic. This could have strong implications for the possible detection of the 21-cm signal.

  18. Quantitative study of coherent pairing modes with two-neutron transfer: Sn isotopes

    NASA Astrophysics Data System (ADS)

    Potel, G.; Idini, A.; Barranco, F.; Vigezzi, E.; Broglia, R. A.

    2013-05-01

    Pairing rotations and pairing vibrations are collective modes associated with a field, the pair field, which changes the number of particles by two. Consequently, they can be studied at profit with the help of two-particle transfer reactions in superfluid and in normal nuclei, respectively. The advent of exotic beams has opened, for the first time, the possibility to carry out such studies in medium heavy nuclei, within the same isotopic chain. The case studied in the present paper is that of the Sn isotopes [essentially from closed (Z=N=50) to closed (Z=50, N=82) shells]. The static and dynamic off-diagonal, long-range order phase coherence in gauge space displayed by pairing rotations and vibrations, respectively, leads to coherent states which behave almost classically. Consequently, these modes are amenable to an accurate nuclear structure description in terms of simple models containing the right physics, in particular, BCS plus quasiparticle random-phase approximation and Hartree-Fock mean field plus random-phase approximation, respectively. The associated two-nucleon transfer spectroscopic amplitudes predicted by such model calculations can thus be viewed as essentially “exact.” This fact, together with the availability of optical potentials for the different real and virtual channels involved in the reactions considered, namely A+2Sn+p, A+1Sn+d, and ASn+t, allows for the calculation of the associated absolute cross sections without, arguably, free parameters. The numerical predictions of the absolute differential cross sections, obtained making use of the above-mentioned nuclear structure and optical potential inputs, within the framework of second-order distorted-wave Born approximation, taking into account simultaneous, successive, and nonorthogonality contributions, provide, within experimental errors in general, and below 10% uncertainty in particular, an overall account of the experimental findings for all of the measured A+2Sn

  19. Signal and noise transfer properties of photoelectric interactions in diagnostic x-ray imaging detectors

    SciTech Connect

    Hajdok, G.; Yao, J.; Battista, J. J.; Cunningham, I. A.

    2006-10-15

    Image quality in diagnostic x-ray imaging is ultimately limited by the statistical properties governing how, and where, x-ray energy is deposited in a detector. This in turn depends on the physics of the underlying x-ray interactions. In the diagnostic energy range (10-100 keV), most of the energy deposited in a detector is through photoelectric interactions. We present a theoretical model of the photoelectric effect that specifically addresses the statistical nature of energy absorption by photoelectrons, K and L characteristic x rays, and Auger electrons. A cascaded-systems approach is used that employs a complex structure of parallel cascades to describe signal and noise transfer through the photoelectric effect in terms of the modulation transfer function, Wiener noise power spectrum, and detective quantum efficiency (DQE). The model was evaluated by comparing results with Monte Carlo calculations for x-ray converters based on amorphous selenium (a-Se) and lead (Pb), representing both low and high-Z materials. When electron transport considerations can be neglected, excellent agreement (within 3%) is obtained for each metric over the entire diagnostic energy range in both a-Se and Pb detectors up to 30 cycles/mm, the highest frequency tested. The cascaded model overstates the DQE when the electron range cannot be ignored. This occurs at approximately two cycles/mm in a-Se at an incident photon energy of 80 keV, whereas in Pb, excellent agreement is obtained for the DQE over the entire diagnostic energy range. However, within the context of mammography (20 keV) and micro-computed tomography (40 keV), the effects of electron transport on the DQE are negligible compared to fluorescence reabsorption, which can lead to decreases of up to 30% and 20% in a-Se and Pb, respectively, at 20 keV; and 10% and 5%, respectively, at 40 keV. It is shown that when Swank noise is identified in a Fourier model, the Swank factor must be frequency dependent. This factor decreases

  20. Signal and noise transfer properties of photoelectric interactions in diagnostic x-ray imaging detectors.

    PubMed

    Hajdok, G; Yao, J; Battista, J J; Cunningham, I A

    2006-10-01

    Image quality in diagnostic x-ray imaging is ultimately limited by the statistical properties governing how, and where, x-ray energy is deposited in a detector. This in turn depends on the physics of the underlying x-ray interactions. In the diagnostic energy range (10-100 keV), most of the energy deposited in a detector is through photoelectric interactions. We present a theoretical model of the photoelectric effect that specifically addresses the statistical nature of energy absorption by photoelectrons, K and L characteristic x rays, and Auger electrons. A cascaded-systems approach is used that employs a complex structure of parallel cascades to describe signal and noise transfer through the photoelectric effect in terms of the modulation transfer function, Wiener noise power spectrum, and detective quantum efficiency (DQE). The model was evaluated by comparing results with Monte Carlo calculations for x-ray converters based on amorphous selenium (a-Se) and lead (Pb), representing both low and high-Z materials. When electron transport considerations can be neglected, excellent agreement (within 3%) is obtained for each metric over the entire diagnostic energy range in both a-Se and Pb detectors up to 30 cycles/mm, the highest frequency tested. The cascaded model overstates the DQE when the electron range cannot be ignored. This occurs at approximately two cycles/mm in a-Se at an incident photon energy of 80 keV, whereas in Pb, excellent agreement is obtained for the DQE over the entire diagnostic energy range. However, within the context of mammography (20 keV) and micro-computed tomography (40 keV), the effects of electron transport on the DQE are negligible compared to fluorescence reabsorption, which can lead to decreases of up to 30% and 20% in a-Se and Pb, respectively, at 20 keV; and 10% and 5%, respectively, at 40 keV. It is shown that when Swank noise is identified in a Fourier model, the Swank factor must be frequency dependent. This factor decreases

  1. Bioelectronome. Integrated approach to receptor chemistry, radicals, electrochemistry, cell signaling, and physiological effects based on electron transfer.

    PubMed

    Kovacic, Peter; Pozos, Robert S

    2007-01-01

    Bioelectronome refers to the host of electron transfer (ET) reactions that occur in living systems. This review presents an integrated approach to receptor chemistry based on electron transfer, radicals, electrochemistry, cell signaling, and end result. First, receptor activity is addressed from the unifying standpoint of redox transformations in which various receptors are discussed. After a listing of receptor-binding modes, receptor chemistry is treated with focus on generation of reactive oxygen species (ROS), activation by ROS, and subsequent cell signaling involving ROS. A general electrostatic mechanism is proposed for receptor-ligand action with supporting evidence. Cell-signaling processes appear to entail electron transfer, ROS, redox chains, and relays. The widespread involvement of phosphate from phosphorylation may be rationalized electrostatically by analogy with DNA phosphate. Extensive evidence supports important participation of ET functionalities in the mechanism of drugs and toxins. The integrated approach is applied to the main ET classes, namely, quinones, metal complexes, iminium species, and aromatic nitro compounds.

  2. Wire transfer of charge packets using a CCD-BBD structure for charge-domain signal processing

    NASA Technical Reports Server (NTRS)

    Fossum, Eric R.

    1991-01-01

    A structure for the virtual transfer of charge packets across metal wires is described theoretically and is experimentally verified. The structure is a hybrid of charge-coupled device (CCD) and bucket-brigade device (BBD) elements and permits the topological crossing of charge-domain signals in low power signal processing circuits. A test vehicle consisting of 8-, 32-, and 96-stage delay lines of various geometries implemented in a double-poly, double-metal foundry process is used to characterize the wire-transfer operation. Transfer efficiency ranging between 0.998 and 0.999 is obtained for surface n-channel devices with clock cycle times in the range from 40 ns to 0.3 ms. Transfer efficiency as high as 0.9999 is obtained for buried n-channel devices. Good agreement is found between experiment and simulation.

  3. Wire transfer of charge packets using a CCD-BBD structure for charge-domain signal processing

    NASA Astrophysics Data System (ADS)

    Fossum, Eric R.

    1991-02-01

    A structure for the virtual transfer of charge packets across metal wires is described theoretically and is experimentally verified. The structure is a hybrid of charge-coupled device (CCD) and bucket-brigade device (BBD) elements and permits the topological crossing of charge-domain signals in low power signal processing circuits. A test vehicle consisting of 8-, 32-, and 96-stage delay lines of various geometries implemented in a double-poly, double-metal foundry process is used to characterize the wire-transfer operation. Transfer efficiency ranging between 0.998 and 0.999 is obtained for surface n-channel devices with clock cycle times in the range from 40 ns to 0.3 ms. Transfer efficiency as high as 0.9999 is obtained for buried n-channel devices. Good agreement is found between experiment and simulation.

  4. Los Alamos Neutron Science Center Area-A beam window heat transfer alalysis

    SciTech Connect

    Poston, D.

    1997-07-01

    Several analyses that investigate heat transfer in the Area-A beam window were conducted. It was found that the Area-A window should be able to withstand the 1-mA, 3-cm beam of the accelerator production of tritium materials test, but that the margins to failure are small. It was also determined that when the window is subjected to the 1-mA, 3-cm beam, the inner window thermocouples should read higher than the current temperature limit of 900{degrees}C, although it is possible that the thermocouples may fail before they reach these temperatures. Another finding of this study was that the actual beam width before April 1997 was 20 to 25% greater than the harp-wire printout indicated. Finally, the effect of a copper-oxide layer on the window coolant passage was studied. The results did not indicate the presence of a large copper-oxide layer; however, the results were not conclusive.

  5. GR simulations of binary black hole-neutron stars: Precursor electromagnetic signals

    NASA Astrophysics Data System (ADS)

    Paschalidis, Vasileios; Etienne, Zachariah B.; Shapiro, Stuart L.

    2014-03-01

    We present a new computational method for smoothly matching general relativistic ideal magnetohydrodynamics (MHD) to its force-free limit. The method is based on a flux-conservative formalism for MHD and its force-free limit, and a vector potential formulation for the induction equation to maintain the zero divergence constraint for the magnetic field. The force-free formulation evolves the magnetic field and the Poynting vector. Our force-free code passes a robust suite of tests, performed both in 1D flat spacetime and in 3D curved (black hole) spacetimes. Our matching technique successfully reproduces the aligned rotator force-free solution. As an application, we performed the first general relativistic, force-free simulations of neutron star (NS) magnetospheres in orbit about spinning and non-spinning black holes with BH:NS mass ratio 3:1. We find promising precursor EM emission: typical Poynting luminosities at, e.g., an orbital separation of 6.6 times the NS radius, are L ~ 6 ×1042 erg/s for a 1 . 4M⊙ NS endowed with a dipolar magnetic field with polar strength 1013G. The Poynting flux peaks within a broad beam of 40 degrees in the azimuthal direction, establishing a possible lighthouse effect.

  6. Nanoscale protein domain motion and long-range allostery in signaling proteins— a view from neutron spin echo sprectroscopy

    PubMed Central

    Callaway, David J. E.; Bu, Zimei

    2015-01-01

    Many cellular proteins are multi-domain proteins. Coupled domain-domain interactions in these multidomain proteins are important for the allosteric relay of signals in the cellular signaling networks. We have initiated the application of neutron spin echo spectroscopy to the study of nanoscale protein domain motions on submicrosecond time scales and on nanometer length scale. Our NSE experiments reveal the activation of protein domain motions over a long distance of over more than 100 Å in a multidomain scaffolding protein NHERF1 upon binding to another protein Ezrin. Such activation of nanoscale protein domains motions is correlated with the allosteric assembly of multi-protein complexes by NHERF1 and Ezrin. Here, we summarize the theoretical framework that we have developed, which uses simple concepts from nonequilibrium statistical mechanics to interpret the NSE data, and employs a mobility tensor to describe nanoscale protein domain motion. Extracting nanoscale protein domain motion from the NSE does not require elaborate molecular dynamics simulations, or complex fits to rotational motion, or elastic network models. The approach is thus more robust than multiparameter techniques that require untestable assumptions. We also demonstrate that an experimental scheme of selective deuteration of a protein subunit in a complex can highlight and amplify specific domain dynamics from the abundant global translational and rotational motions in a protein. We expect NSE to provide a unique tool to determine nanoscale protein dynamics for the understanding of protein functions, such as how signals are propagated in a protein over a long distance to a distal domain. PMID:26005503

  7. The effect of blood pressure calibrations and transcranial Doppler signal loss on transfer function estimates of cerebral autoregulation

    PubMed Central

    Deegan, Brian M.; Serrador, Jorge M.; Nakagawa, Kazuma; Jones, Edward; Sorond, Farzaneh A.; ÓLaighin, Gearóid

    2015-01-01

    There are methodological concerns with combined use of transcranial Doppler (TCD) and Finapres to measure dynamic cerebral autoregulation. The Finapres calibration mechanism (“physiocal”) causes interruptions to blood pressure recordings. Also, TCD is subject to signal loss due to probe movement. We assessed the effects of “physiocals” and TCD signal loss on transfer function estimates in recordings of 45 healthy subjects. We added artificial “physiocals” and removed sections of TCD signal from 5 min Finapres and TCD recordings. We also compared transfer function results from 5 min time series with time series as short as 1 min. Accurate transfer function estimates can be achieved in the 0.03–0.07 Hz band using beat-by-beat data with linear interpolation, while data loss is less than 10 s. At frequencies between 0.07 and 0.5 Hz, transfer function estimates become unreliable with 5 s of data loss every 50 s. 2 s data loss only affects frequency bands above 0.15 Hz. Finally, accurate transfer function assessment of autoregulatory function can be achieved from time series as short as 1 min, although gain and coherence tend to be overestimated at higher frequencies. PMID:21239208

  8. Glucose and ethylene signalling pathways converge to regulate trans-differentiation of epidermal transfer cells in Vicia narbonensis cotyledons.

    PubMed

    Andriunas, Felicity A; Zhang, Hui-Ming; Weber, Hans; McCurdy, David W; Offler, Christina E; Patrick, John W

    2011-12-01

    Transfer cells are specialized transport cells containing invaginated wall ingrowths that provide an amplified plasma membrane surface area with high densities of transporter proteins. They trans-differentiate from differentiated cells at sites where enhanced rates of nutrient transport occur across apo/symplasmic boundaries. Despite their physiological importance, the signal(s) and signalling cascades responsible for initiating their trans-differentiation are poorly understood. In culture, adaxial epidermal cells of Vicia narbonensis cotyledons were induced to trans-differentiate to a transfer cell morphology. Manipulating their intracellular glucose concentrations by transgenic knock-down of ADP-glucose pyrophosphorylase expression and/or culture on a high-glucose medium demonstrated that glucose functioned as a negative regulator of wall ingrowth induction. In contrast, glucose had no detectable effect on wall ingrowth morphology. The effect on wall ingrowth induction of culture on media containing glucose analogues suggested that glucose acts through a hexokinase-dependent signalling pathway. Elevation of an epidermal cell-specific ethylene signal alone, or in combination with glucose analogues, countered the negative effect of glucose on wall ingrowth induction. Glucose modulated the amplitude of ethylene-stimulated wall ingrowth induction by down-regulating the expression of ethylene biosynthetic genes and an ethylene insensitive 3 (EIN3)-like gene (EIL) encoding a key transcription factor in the ethylene signalling cascade. A model is presented describing the interaction between glucose and ethylene signalling pathways regulating the induction of wall ingrowth formation in adaxial epidermal cells.

  9. The orchestra of lipid-transfer proteins at the crossroads between metabolism and signaling.

    PubMed

    Chiapparino, Antonella; Maeda, Kenji; Turei, Denes; Saez-Rodriguez, Julio; Gavin, Anne-Claude

    2016-01-01

    Within the eukaryotic cell, more than 1000 species of lipids define a series of membranes essential for cell function. Tightly controlled systems of lipid transport underlie the proper spatiotemporal distribution of membrane lipids, the coordination of spatially separated lipid metabolic pathways, and lipid signaling mediated by soluble proteins that may be localized some distance away from membranes. Alongside the well-established vesicular transport of lipids, non-vesicular transport mediated by a group of proteins referred to as lipid-transfer proteins (LTPs) is emerging as a key mechanism of lipid transport in a broad range of biological processes. More than a hundred LTPs exist in humans and these can be divided into at least ten protein families. LTPs are widely distributed in tissues, organelles and membrane contact sites (MCSs), as well as in the extracellular space. They all possess a soluble and globular domain that encapsulates a lipid monomer and they specifically bind and transport a wide range of lipids. Here, we present the most recent discoveries in the functions and physiological roles of LTPs, which have expanded the playground of lipids into the aqueous spaces of cells.

  10. Joint neutron crystallographic and NMR solution studies of Tyr residue ionization and hydrogen bonding: Implications for enzyme-mediated proton transfer

    DOE PAGESBeta

    Michalczyk, Ryszard; Unkefer, Clifford J.; Bacik, John -Paul; Schrader, Tobias E.; Ostermann, Andreas; Kovalevsky, Andrey Y.; McKenna, Robert; Fisher, Suzanne Zoe

    2015-05-05

    Proton transfer is a fundamental mechanism at the core of many enzyme-catalyzed reactions. It is also exquisitely sensitive to a number of factors, including pH, electrostatics, proper active-site geometry, and chemistry. Carbonic anhydrase has evolved a fast and efficient way to conduct protons through a combination of hydrophilic amino acid side chains that coordinate a highly ordered H-bonded water network. This study uses a powerful approach, combining NMR solution studies with neutron protein crystallography, to determine the effect of pH and divalent cations on key residues involved in proton transfer in human carbonic anhydrase. Lastly, the results have broad implicationsmore » for our understanding of proton transfer and how subtle changes in ionization and H-bonding interactions can modulate enzyme catalysis.« less

  11. Joint neutron crystallographic and NMR solution studies of Tyr residue ionization and hydrogen bonding: Implications for enzyme-mediated proton transfer

    SciTech Connect

    Michalczyk, Ryszard; Unkefer, Clifford J.; Bacik, John -Paul; Schrader, Tobias E.; Ostermann, Andreas; Kovalevsky, Andrey Y.; McKenna, Robert; Fisher, Suzanne Zoe

    2015-05-05

    Proton transfer is a fundamental mechanism at the core of many enzyme-catalyzed reactions. It is also exquisitely sensitive to a number of factors, including pH, electrostatics, proper active-site geometry, and chemistry. Carbonic anhydrase has evolved a fast and efficient way to conduct protons through a combination of hydrophilic amino acid side chains that coordinate a highly ordered H-bonded water network. This study uses a powerful approach, combining NMR solution studies with neutron protein crystallography, to determine the effect of pH and divalent cations on key residues involved in proton transfer in human carbonic anhydrase. Lastly, the results have broad implications for our understanding of proton transfer and how subtle changes in ionization and H-bonding interactions can modulate enzyme catalysis.

  12. Neutron single-particle states above the N=164 subshell in {sub 98}{sup 251}Cf and {sub 96}{sup 249}Cm studied by neutron transfer reactions

    SciTech Connect

    Ahmad, I.; Chasman, R. R.

    2009-12-15

    Single-particle state assignments in {sup 251}Cf and {sup 249}Cm at {approx}1 MeV excitation have been deduced from cross sections previously measured for the {sup 250}Cf(d,p){sup 251}Cf and {sup 248}Cm({sup 4}He,{sup 3}He){sup 249}Cm reactions. The assignments are supported by observed cross-section signatures and intraband level spacings. The observed energies of these single-particle states, after pairing effects are removed, are in good agreement with values calculated using a Woods-Saxon single-particle potential. Neutron level diagrams, showing level spacings as a function of {nu}{sub 2},{nu}{sub 4}, and {nu}{sub 6}, are extended to include neutron orbitals above N=164.

  13. Measurement of the free neutron-proton analyzing power and spin transfer parameters in the charge exchange region at 790 MeV

    SciTech Connect

    Ransome, R.D.

    1981-07-01

    The free neutron-proton analyzing power and the spin transfer parameters (K/sub NN/, K/sub SS/, K/sub SL/, and K/sub LL/) were measured at the Los Alamos Meson Physics Facility at 790 MeV between 165/sup 0/ and 180/sup 0/ center of mass. A 40% polarized neutron beam incident on a liquid hydrogen target was used. The recoil protons were momentum analyzed with a magnetic spectrometer to isolate elastic scatters. A large solid angle carbon polarimeter was used to measure the proton polarization. The measurements are the first at this energy and are in basic agreement with pre-existing phase shift solutions. The proton-carbon analyzing power was measured between 500 and 750 MeV. An empirical fit to the proton-carbon analyzing power between 100 and 750 MeV was done.

  14. Analysis of linear energy transfers and quality factors of charged particles produced by spontaneous fission neutrons from 252Cf and 244Pu in the human body.

    PubMed

    Endo, Akira; Sato, Tatsuhiko

    2013-04-01

    Absorbed doses, linear energy transfers (LETs) and quality factors of secondary charged particles in organs and tissues, generated via the interactions of the spontaneous fission neutrons from (252)Cf and (244)Pu within the human body, were studied using the Particle and Heavy Ion Transport Code System (PHITS) coupled with the ICRP Reference Phantom. Both the absorbed doses and the quality factors in target organs generally decrease with increasing distance from the source organ. The analysis of LET distributions of secondary charged particles led to the identification of the relationship between LET spectra and target-source organ locations. A comparison between human body-averaged mean quality factors and fluence-averaged radiation weighting factors showed that the current numerical conventions for the radiation weighting factors of neutrons, updated in ICRP103, and the quality factors for internal exposure are valid.

  15. Mutant Screen Distinguishes between Residues Necessary for Light-Signal Perception and Signal Transfer by Phytochrome B

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The phytochromes (phyA to phyE) are a major plant photoreceptor family that regulate a diversity of developmental processes in response to light. The N-terminal 651–amino acid domain of phyB (N651), which binds an open tetrapyrrole chromophore, acts to perceive and transduce regulatory light signals...

  16. Membrane Transfer from Mononuclear Cells to Polymorphonuclear Neutrophils Transduces Cell Survival and Activation Signals in the Recipient Cells via Anti-Extrinsic Apoptotic and MAP Kinase Signaling Pathways

    PubMed Central

    Li, Ko-Jen; Wu, Cheng-Han; Shen, Chieh-Yu; Kuo, Yu-Min; Yu, Chia-Li; Hsieh, Song-Chou

    2016-01-01

    The biological significance of membrane transfer (trogocytosis) between polymorphonuclear neutrophils (PMNs) and mononuclear cells (MNCs) remains unclear. We investigated the biological/immunological effects and molecular basis of trogocytosis among various immune cells in healthy individuals and patients with active systemic lupus erythematosus (SLE). By flow cytometry, we determined that molecules in the immunological synapse, including HLA class-I and-II, CD11b and LFA-1, along with CXCR1, are exchanged among autologous PMNs, CD4+ T cells, and U937 cells (monocytes) after cell-cell contact. Small interfering RNA knockdown of the integrin adhesion molecule CD11a in U937 unexpectedly enhanced the level of total membrane transfer from U937 to PMN cells. Functionally, phagocytosis and IL-8 production by PMNs were enhanced after co-culture with T cells. Total membrane transfer from CD4+ T to PMNs delayed PMN apoptosis by suppressing the extrinsic apoptotic molecules, BAX, MYC and caspase 8. This enhancement of activities of PMNs by T cells was found to be mediated via p38- and P44/42-Akt-MAP kinase pathways and inhibited by the actin-polymerization inhibitor, latrunculin B, the clathrin inhibitor, Pitstop-2, and human immunoglobulin G, but not by the caveolin inhibitor, methyl-β-cyclodextrin. In addition, membrane transfer from PMNs enhanced IL-2 production by recipient anti-CD3/anti-CD28 activated MNCs, and this was suppressed by inhibitors of mitogen-activated protein kinase (PD98059) and protein kinase C (Rottlerin). Of clinical significance, decreased total membrane transfer from PMNs to MNCs in patients with active SLE suppressed mononuclear IL-2 production. In conclusion, membrane transfer from MNCs to PMNs, mainly at the immunological synapse, transduces survival and activation signals to enhance PMN functions and is dependent on actin polymerization, clathrin activation, and Fcγ receptors, while membrane transfer from PMNs to MNCs depends on MAP kinase and

  17. Digital signal processing for a thermal neutron detector using ZnS(Ag):6LiF scintillating layers read out with WLS fibers and SiPMs

    NASA Astrophysics Data System (ADS)

    Mosset, J.-B.; Stoykov, A.; Greuter, U.; Hildebrandt, M.; Schlumpf, N.

    2016-07-01

    We present a digital signal processing system based on a photon counting approach which we developed for a thermal neutron detector consisting of ZnS(Ag):6LiF scintillating layers read out with WLS fibers and SiPMs. Three digital filters have been evaluated: a moving sum, a moving sum after differentiation and a digital CR-RC4 filter. The performances of the detector with these filters are presented. A full analog signal processing using a CR-RC4 filter has been emulated digitally. The detector performance obtained with this analog approach is compared with the one obtained with the best performing digital approach.

  18. 454 Transcriptome Sequencing Suggests a Role for Two-Component Signalling in Cellularization and Differentiation of Barley Endosperm Transfer Cells

    PubMed Central

    Thiel, Johannes; Hollmann, Julien; Rutten, Twan; Weber, Hans; Scholz, Uwe; Weschke, Winfriede

    2012-01-01

    Background Cell specification and differentiation in the endosperm of cereals starts at the maternal-filial boundary and generates the endosperm transfer cells (ETCs). Besides the importance in assimilate transfer, ETCs are proposed to play an essential role in the regulation of endosperm differentiation by affecting development of proximate endosperm tissues. We attempted to identify signalling elements involved in early endosperm differentiation by using a combination of laser-assisted microdissection and 454 transcriptome sequencing. Principal Findings 454 sequencing of the differentiating ETC region from the syncytial state until functionality in transfer processes captured a high proportion of novel transcripts which are not available in existing barley EST databases. Intriguingly, the ETC-transcriptome showed a high abundance of elements of the two-component signalling (TCS) system suggesting an outstanding role in ETC differentiation. All components and subfamilies of the TCS, including distinct kinds of membrane-bound receptors, have been identified to be expressed in ETCs. The TCS system represents an ancient signal transduction system firstly discovered in bacteria and has previously been shown to be co-opted by eukaryotes, like fungi and plants, whereas in animals and humans this signalling route does not exist. Transcript profiling of TCS elements by qRT-PCR suggested pivotal roles for specific phosphorelays activated in a coordinated time flow during ETC cellularization and differentiation. ETC-specificity of transcriptionally activated TCS phosphorelays was assessed for early differentiation and cellularization contrasting to an extension of expression to other grain tissues at the beginning of ETC maturation. Features of candidate genes of distinct phosphorelays and transcriptional activation of genes putatively implicated in hormone signalling pathways hint at a crosstalk of hormonal influences, putatively ABA and ethylene, and TCS signalling

  19. Fast and simple acquisition of solid-state 14N NMR spectra with signal enhancement via population transfer.

    PubMed

    O'Dell, Luke A; Schurko, Robert W

    2009-05-20

    A new approach for the acquisition of static, wideline (14)N NMR powder patterns is outlined. The method involves the use of frequency-swept pulses which serve two simultaneous functions: (1) broad-band excitation of magnetization and (2) signal enhancement via population transfer. The signal enhancement mechanism is described using numerical simulations and confirmed experimentally. This approach, which we call DEISM (Direct Enhancement of Integer Spin Magnetization), allows high-quality (14)N spectra to be acquired at intermediate field strengths in an uncomplicated way and in a fraction of the time required for previously reported methods.

  20. Search of S3 LIGO data for gravitational wave signals from spinning black hole and neutron star binary inspirals

    NASA Astrophysics Data System (ADS)

    Abbott, B.; Abbott, R.; Adhikari, R.; Agresti, J.; Ajith, P.; Allen, B.; Amin, R.; Anderson, S. B.; Anderson, W. G.; Arain, M.; Araya, M.; Armandula, H.; Ashley, M.; Aston, S.; Aufmuth, P.; Aulbert, C.; Babak, S.; Ballmer, S.; Bantilan, H.; Barish, B. C.; Barker, C.; Barker, D.; Barr, B.; Barriga, P.; Barton, M. A.; Bayer, K.; Betzwieser, J.; Beyersdorf, P. T.; Bhawal, B.; Bilenko, I. A.; Billingsley, G.; Biswas, R.; Black, E.; Blackburn, K.; Blackburn, L.; Blair, D.; Bland, B.; Bogenstahl, J.; Bogue, L.; Bork, R.; Boschi, V.; Bose, S.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Brinkmann, M.; Brooks, A.; Brown, D. A.; Bullington, A.; Bunkowski, A.; Buonanno, A.; Burmeister, O.; Busby, D.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Camp, J. B.; Cannizzo, J.; Cannon, K.; Cantley, C. A.; Cao, J.; Cardenas, L.; Castaldi, G.; Cepeda, C.; Chalkley, E.; Charlton, P.; Chatterji, S.; Chelkowski, S.; Chen, Y.; Chiadini, F.; Christensen, N.; Clark, J.; Cochrane, P.; Cokelaer, T.; Coldwell, R.; Conte, R.; Cook, D.; Corbitt, T.; Coyne, D.; Creighton, J. D. E.; Croce, R. P.; Crooks, D. R. M.; Cruise, A. M.; Cumming, A.; Dalrymple, J.; D'Ambrosio, E.; Danzmann, K.; Davies, G.; Debra, D.; Degallaix, J.; Degree, M.; Demma, T.; Dergachev, V.; Desai, S.; Desalvo, R.; Dhurandhar, S.; Díaz, M.; Dickson, J.; di Credico, A.; Diederichs, G.; Dietz, A.; Doomes, E. E.; Drever, R. W. P.; Dumas, J.-C.; Dupuis, R. J.; Dwyer, J. G.; Ehrens, P.; Espinoza, E.; Etzel, T.; Evans, M.; Evans, T.; Fairhurst, S.; Fan, Y.; Fazi, D.; Fejer, M. M.; Finn, L. S.; Fiumara, V.; Fotopoulos, N.; Franzen, A.; Franzen, K. Y.; Freise, A.; Frey, R.; Fricke, T.; Fritschel, P.; Frolov, V. V.; Fyffe, M.; Galdi, V.; Garofoli, J.; Gholami, I.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Goda, K.; Goetz, E.; Goggin, L. M.; González, G.; Gossler, S.; Grant, A.; Gras, S.; Gray, C.; Gray, M.; Greenhalgh, J.; Gretarsson, A. M.; Grosso, R.; Grote, H.; Grunewald, S.; Guenther, M.; Gustafson, R.; Hage, B.; Hammer, D.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G.; Harstad, E.; Hayler, T.; Heefner, J.; Heng, I. S.; Heptonstall, A.; Heurs, M.; Hewitson, M.; Hild, S.; Hirose, E.; Hoak, D.; Hosken, D.; Hough, J.; Hoyland, D.; Huttner, S. H.; Ingram, D.; Innerhofer, E.; Ito, M.; Itoh, Y.; Ivanov, A.; Johnson, B.; Johnson, W. W.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kasprzyk, D.; Katsavounidis, E.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kells, W.; Keppel, D. G.; Khalili, F. Ya.; Kim, C.; King, P.; Kissel, J. S.; Klimenko, S.; Kokeyama, K.; Kondrashov, V.; Kopparapu, R. K.; Kozak, D.; Krishnan, B.; Kwee, P.; Lam, P. K.; Landry, M.; Lantz, B.; Lazzarini, A.; Lei, M.; Leiner, J.; Leonhardt, V.; Leonor, I.; Libbrecht, K.; Lindquist, P.; Lockerbie, N. A.; Longo, M.; Lormand, M.; Lubiński, M.; Lück, H.; Machenschalk, B.; Macinnis, M.; Mageswaran, M.; Mailand, K.; Malec, M.; Mandic, V.; Marano, S.; Márka, S.; Markowitz, J.; Maros, E.; Martin, I.; Marx, J. N.; Mason, K.; Matone, L.; Matta, V.; Mavalvala, N.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McHugh, M.; McKenzie, K.; McWilliams, S.; Meier, T.; Melissinos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messaritaki, E.; Messenger, C. J.; Meyers, D.; Mikhailov, E.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Miyakawa, O.; Mohanty, S.; Moreno, G.; Mossavi, K.; Mowlowry, C.; Moylan, A.; Mudge, D.; Mueller, G.; Mukherjee, S.; Müller-Ebhardt, H.; Munch, J.; Murray, P.; Myers, E.; Myers, J.; Nash, T.; Newton, G.; Nishizawa, A.; Numata, K.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pan, Y.; Papa, M. A.; Parameshwaraiah, V.; Patel, P.; Pedraza, M.; Penn, S.; Pierro, V.; Pinto, I. M.; Pitkin, M.; Pletsch, H.; Plissi, M. V.; Postiglione, F.; Prix, R.; Quetschke, V.; Raab, F.; Rabeling, D.; Radkins, H.; Rahkola, R.; Rainer, N.; Rakhmanov, M.; Ramsunder, M.; Ray-Majumder, S.; Re, V.; Rehbein, H.; Reid, S.; Reitze, D. H.; Ribichini, L.; Riesen, R.; Riles, K.; Rivera, B.; Robertson, N. A.; Robinson, C.; Robinson, E. L.; Roddy, S.; Rodriguez, A.; Rogan, A. M.; Rollins, J.; Romano, J. D.; Romie, J.; Route, R.; Rowan, S.; Rüdiger, A.; Ruet, L.; Russell, P.; Ryan, K.; Sakata, S.; Samidi, M.; Sancho de La Jordana, L.; Sandberg, V.; Sannibale, V.; Saraf, S.; Sarin, P.; Sathyaprakash, B. S.; Sato, S.; Saulson, P. R.; Savage, R.; Savov, P.; Schediwy, S.; Schilling, R.; Schnabel, R.; Schofield, R.; Schutz, B. F.; Schwinberg, P.; Scott, S. M.; Searle, A. C.; Sears, B.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Shawhan, P.; Shoemaker, D. H.; Sibley, A.; Sidles, J. A.; Siemens, X.; Sigg, D.; Sinha, S.; Sintes, A. M.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Somiya, K.; Strain, K. A.; Strom, D. M.; Stuver, A.; Summerscales, T. Z.; Sun, K.-X.; Sung, M.; Sutton, P. J.; Takahashi, H.; Tanner, D. B.; Taylor, R.; Taylor, R.; Thacker, J.; Thorne, K. A.; Thorne, K. S.; Thüring, A.; Tokmakov, K. V.; Torres, C.; Torrie, C.; Traylor, G.; Trias, M.; Tyler, W.; Ugolini, D.; Urbanek, K.; Vahlbruch, H.; Vallisneri, M.; van den Broeck, C.; Varvella, M.; Vass, S.; Vecchio, A.; Veitch, J.; Veitch, P.; Villar, A.; Vorvick, C.; Vyachanin, S. P.; Waldman, S. J.; Wallace, L.; Ward, H.; Ward, R.; Watts, K.; Weidner, A.; Weinert, M.; Weinstein, A.; Weiss, R.; Wen, S.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; Whiting, B. F.; Wilkinson, C.; Willems, P. A.; Williams, L.; Willke, B.; Wilmut, I.; Winkler, W.; Wipf, C. C.; Wise, S.; Wiseman, A. G.; Woan, G.; Woods, D.; Wooley, R.; Worden, J.; Wu, W.; Yakushin, I.; Yamamoto, H.; Yan, Z.; Yoshida, S.; Yunes, N.; Zanolin, M.; Zhang, J.; Zhang, L.; Zhao, C.; Zotov, N.; Zucker, M.; Zur Mühlen, H.; Zweizig, J.

    2008-08-01

    We report on the methods and results of the first dedicated search for gravitational waves emitted during the inspiral of compact binaries with spinning component bodies. We analyze 788 hours of data collected during the third science run (S3) of the LIGO detectors. We searched for binary systems using a detection template family specially designed to capture the effects of the spin-induced precession of the orbital plane. We present details of the techniques developed to enable this search for spin-modulated gravitational waves, highlighting the differences between this and other recent searches for binaries with nonspinning components. The template bank we employed was found to yield high matches with our spin-modulated target waveform for binaries with masses in the asymmetric range 1.0M⊙signals were identified during this search. Assuming a binary population with spinning components and Gaussian distribution of masses representing a prototypical neutron star black hole system with m1≃1.35M⊙ and m2≃5M⊙, we calculate the 90%-confidence upper limit on the rate of coalescence of these systems to be 15.9yr-1L10-1, where L10 is 1010 times the blue light luminosity of the Sun.

  1. The transfer function of a target limits the jitter detection threshold with signals of echolocating FM-bats.

    PubMed

    Beedholm, Kristian

    2006-05-01

    The delay jitter discrimination threshold in bats is a disputed subject. Some investigators have obtained results indicating that bats are able to discriminate alternations in delay down to 10 ns, which appears incredible for purely physical reasons. Using actual bat echolocation sequences recorded during an easy detection task to measure simulated delay jitter, it is shown here that jitter detection thresholds in the order of some tens of nanoseconds are actually physically realizable. However, if the transfer function of the target simulating apparatus is not perfect, the lowest thresholds are in the order of hundreds of nanoseconds and variable between individual bats. This phenomenon is shown to arise as a consequence of the variation in signal parameters from call to call. When the transfer function from a real jitter experiment was artificially applied to the echoes, the jitter detection thresholds again were several hundred nanoseconds. This is the first study to point out a limiting role of the transfer function of a system faced with variations in echolocation signal parameters, something that should be considered in evaluating all sonar systems with variable signal structure.

  2. A bipartite signal mediates the transfer of type IV secretion substrates of Bartonella henselae into human cells.

    PubMed

    Schulein, Ralf; Guye, Patrick; Rhomberg, Thomas A; Schmid, Michael C; Schröder, Gunnar; Vergunst, Annette C; Carena, Ilaria; Dehio, Christoph

    2005-01-18

    Bacterial type IV secretion (T4S) systems mediate the transfer of macromolecular substrates into various target cells, e.g., the conjugative transfer of DNA into bacteria or the transfer of virulence proteins into eukaryotic host cells. The T4S apparatus VirB of the vascular tumor-inducing pathogen Bartonella henselae causes subversion of human endothelial cell (HEC) function. Here we report the identification of multiple protein substrates of VirB, which, upon translocation into HEC, mediate all known VirB-dependent cellular changes. These Bartonella-translocated effector proteins (Beps) A-G are encoded together with the VirB system and the T4S coupling protein VirD4 on a Bartonella-specific pathogenicity island. The Beps display a modular architecture, suggesting an evolution by extensive domain duplication and reshuffling. The C terminus of each Bep harbors at least one copy of the Bep-intracellular delivery domain and a short positively charged tail sequence. This biparte C terminus constitutes a transfer signal that is sufficient to mediate VirB/VirD4-dependent intracellular delivery of reporter protein fusions. The Bep-intracellular delivery domain is also present in conjugative relaxases of bacterial conjugation systems. We exemplarily show that the C terminus of such a conjugative relaxase mediates protein transfer through the Bartonella henselae VirB/VirD4 system into HEC. Conjugative relaxases may thus represent the evolutionary origin of the here defined T4S signal for protein transfer into human cells. PMID:15642951

  3. A Measurement of the neutron electric form factor at very large momentum transfer using polaried electrions scattering from a polarized helium-3 target

    SciTech Connect

    Kelleher, Aidan

    2010-02-01

    Knowledge of the electric and magnetic elastic form factors of the nucleon is essential for an understanding of nucleon structure. Of the form factors, the electric form factor of the neutron has been measured over the smallest range in Q2 and with the lowest precision. Jefferson Lab experiment 02-013 used a novel new polarized 3 He target to nearly double the range of momentum transfer in which the neutron form factor has been studied and to measure it with much higher precision. Polarized electrons were scattered off this target, and both the scattered electron and neutron were detected. Gn E was measured to be 0.0242 ± 0.0020(stat) ± 0.0061(sys) and 0.0247 ± 0.0029(stat) ± 0.0031(sys) at Q2 = 1.7 and 2.5 GeV2 , respectively.

  4. Defoliation of interior Douglas-fir elicits carbon transfer and stress signalling to ponderosa pine neighbors through ectomycorrhizal networks.

    PubMed

    Song, Yuan Yuan; Simard, Suzanne W; Carroll, Allan; Mohn, William W; Zeng, Ren Sen

    2015-02-16

    Extensive regions of interior Douglas-fir (Pseudotsuga menziesii var. glauca, IDF) forests in North America are being damaged by drought and western spruce budworm (Choristoneura occidentalis). This damage is resulting from warmer and drier summers associated with climate change. To test whether defoliated IDF can directly transfer resources to ponderosa pine (Pinus ponderosae) regenerating nearby, thus aiding in forest recovery, we examined photosynthetic carbon transfer and defense enzyme response. We grew pairs of ectomycorrhizal IDF 'donor' and ponderosa pine 'receiver' seedlings in pots and isolated transfer pathways by comparing 35 μm, 0.5 μm and no mesh treatments; we then stressed IDF donors either through manual defoliation or infestation by the budworm. We found that manual defoliation of IDF donors led to transfer of photosynthetic carbon to neighboring receivers through mycorrhizal networks, but not through soil or root pathways. Both manual and insect defoliation of donors led to increased activity of peroxidase, polyphenol oxidase and superoxide dismutase in the ponderosa pine receivers, via a mechanism primarily dependent on the mycorrhizal network. These findings indicate that IDF can transfer resources and stress signals to interspecific neighbors, suggesting ectomycorrhizal networks can serve as agents of interspecific communication facilitating recovery and succession of forests after disturbance.

  5. Defoliation of interior Douglas-fir elicits carbon transfer and stress signalling to ponderosa pine neighbors through ectomycorrhizal networks

    PubMed Central

    Song, Yuan Yuan; Simard, Suzanne W.; Carroll, Allan; Mohn, William W.; Zeng, Ren Sen

    2015-01-01

    Extensive regions of interior Douglas-fir (Pseudotsuga menziesii var. glauca, IDF) forests in North America are being damaged by drought and western spruce budworm (Choristoneura occidentalis). This damage is resulting from warmer and drier summers associated with climate change. To test whether defoliated IDF can directly transfer resources to ponderosa pine (Pinus ponderosae) regenerating nearby, thus aiding in forest recovery, we examined photosynthetic carbon transfer and defense enzyme response. We grew pairs of ectomycorrhizal IDF ‘donor’ and ponderosa pine ‘receiver’ seedlings in pots and isolated transfer pathways by comparing 35 μm, 0.5 μm and no mesh treatments; we then stressed IDF donors either through manual defoliation or infestation by the budworm. We found that manual defoliation of IDF donors led to transfer of photosynthetic carbon to neighboring receivers through mycorrhizal networks, but not through soil or root pathways. Both manual and insect defoliation of donors led to increased activity of peroxidase, polyphenol oxidase and superoxide dismutase in the ponderosa pine receivers, via a mechanism primarily dependent on the mycorrhizal network. These findings indicate that IDF can transfer resources and stress signals to interspecific neighbors, suggesting ectomycorrhizal networks can serve as agents of interspecific communication facilitating recovery and succession of forests after disturbance. PMID:25683155

  6. Defoliation of interior Douglas-fir elicits carbon transfer and stress signalling to ponderosa pine neighbors through ectomycorrhizal networks.

    PubMed

    Song, Yuan Yuan; Simard, Suzanne W; Carroll, Allan; Mohn, William W; Zeng, Ren Sen

    2015-01-01

    Extensive regions of interior Douglas-fir (Pseudotsuga menziesii var. glauca, IDF) forests in North America are being damaged by drought and western spruce budworm (Choristoneura occidentalis). This damage is resulting from warmer and drier summers associated with climate change. To test whether defoliated IDF can directly transfer resources to ponderosa pine (Pinus ponderosae) regenerating nearby, thus aiding in forest recovery, we examined photosynthetic carbon transfer and defense enzyme response. We grew pairs of ectomycorrhizal IDF 'donor' and ponderosa pine 'receiver' seedlings in pots and isolated transfer pathways by comparing 35 μm, 0.5 μm and no mesh treatments; we then stressed IDF donors either through manual defoliation or infestation by the budworm. We found that manual defoliation of IDF donors led to transfer of photosynthetic carbon to neighboring receivers through mycorrhizal networks, but not through soil or root pathways. Both manual and insect defoliation of donors led to increased activity of peroxidase, polyphenol oxidase and superoxide dismutase in the ponderosa pine receivers, via a mechanism primarily dependent on the mycorrhizal network. These findings indicate that IDF can transfer resources and stress signals to interspecific neighbors, suggesting ectomycorrhizal networks can serve as agents of interspecific communication facilitating recovery and succession of forests after disturbance. PMID:25683155

  7. Microscopic time-dependent analysis of neutrons transfers at low-energy nuclear reactions with spherical and deformed nuclei

    NASA Astrophysics Data System (ADS)

    Samarin, Viacheslav

    2014-03-01

    Time-dependent Schrödinger equation is numerically solved by difference method for external neutrons of nuclei 6He, 18O, 48Са, 238U at their grazing collisions with energies in the vicinity of a Coulomb barrier. The spin-orbital interaction and Pauli's exclusion principle were taken into consideration during the solution.

  8. Proton transfer in benzoic acid crystals: A chemical spin-boson problem. Theoretical analysis of nuclear magnetic resonance, neutron scattering, and optical experiments

    NASA Astrophysics Data System (ADS)

    Skinner, J. L.; Trommsdorff, H. P.

    1988-07-01

    The double proton transfer in benzoic acid crystals can be described by a double-minimum potential. At low temperatures one need consider only the two lowest energy eigenstates, which must be coupled to the crystalline phonons in order to obtain relaxation. Thus the benzoic acid system provides a well-defined chemical example of the spin-boson Hamiltonian. Within this model the tunneling relaxation between localized states occurs by one-phonon emission or absorption. Alternatively, at high temperatures the proton transfer is thermally activated. With this simple picture in mind we analyze NMR T1 relaxation experiments. The temperature-dependent proton transfer rate that emerges from the NMR analysis is in good agreement with inelastic neutron scattering experiments. Optical transitions of a dye probe have also been used to determine proton transfer rates in crystalline benzoic acid. Our model allows us to discuss both doped and pure crystal experiments within a unified framework. Thus, we find that all three different experimental probes yield results that are consistent with our simple theoretical picture. From our results we can determine the proton-phonon coupling constant.

  9. G protein-coupled receptor signaling analysis using homogenous time-resolved Förster resonance energy transfer (HTRF®) technology.

    PubMed

    Nørskov-Lauritsen, Lenea; Thomsen, Alex Rojas Bie; Bräuner-Osborne, Hans

    2014-01-01

    Studying multidimensional signaling of G protein-coupled receptors (GPCRs) in search of new and better treatments requires flexible, reliable and sensitive assays in high throughput screening (HTS) formats. Today, more than half of the detection techniques used in HTS are based on fluorescence, because of the high sensitivity and rich signal, but quenching, optical interferences and light scattering are serious drawbacks. In the 1990s the HTRF® (Cisbio Bioassays, Codolet, France) technology based on Förster resonance energy transfer (FRET) in a time-resolved homogeneous format was developed. This improved technology diminished the traditional drawbacks. The optimized protocol described here based on HTRF® technology was used to study the activation and signaling pathways of the calcium-sensing receptor, CaSR, a GPCR responsible for maintaining calcium homeostasis. Stimulation of the CaSR by agonists activated several pathways, which were detected by measuring accumulation of the second messengers D-myo-inositol 1-phosphate (IP1) and cyclic adenosine 3',5'-monophosphate (cAMP), and by measuring the phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2). Here we show how an optimized HTRF® platform with numerous advantages compared to previous assays provides a substantial and robust mode of investigating GPCR signaling. It is furthermore discussed how these assays can be optimized and miniaturized to meet HTS requirements and for screening compound libraries.

  10. Application of advanced signal processing techniques to the rectification and registration of spaceborne imagery. [technology transfer, data transmission

    NASA Technical Reports Server (NTRS)

    Caron, R. H.; Rifman, S. S.; Simon, K. W.

    1974-01-01

    The development of an ERTS/MSS image processing system responsive to the needs of the user community is discussed. An overview of the TRW ERTS/MSS processor is presented, followed by a more detailed discussion of image processing functions satisfied by the system. The particular functions chosen for discussion are evolved from advanced signal processing techniques rooted in the areas of communication and control. These examples show how classical aerospace technology can be transferred to solve the more contemporary problems confronting the users of spaceborne imagery.

  11. MeV-GeV neutrino propagation as a signal of magnetic field amplification in neutron star merger

    NASA Astrophysics Data System (ADS)

    Fraija, N.

    2016-09-01

    Short gamma-ray bursts (sGRBs) have widely been accepted to arise from a compact object binary merger; neutron star-neutron star or neutron star-black hole. During the merger of a binary neutron star system, magnetic field can be amplified beyond magnetar field strength (∼1015-1016 G) by Kelvin-Helmholtz instabilities. Considering this effect on the GRB "fireball" dynamics, we study the emission, propagation and oscillation of multi MeV-GeV neutrinos through their self-energies and using these we compute the neutrino effective potential up to order MW-4. Additionally, we calculate the number of neutrino events and neutrino flavor ratios that we would expect on Hyper-Kamiokande and DeepCore experiments. We found that MeV neutrinos in a strong magnetic field could provide information of the topology of the field, and that the number of GeV neutrinos expected in DeepCore detector would be directly affected by the strength of the field. It is worth noting that our estimates correspond to the only trustworthy method for verifying the effect of the magnetic field amplification.

  12. Proton recoil scintillator neutron rem meter

    DOEpatents

    Olsher, Richard H.; Seagraves, David T.

    2003-01-01

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

  13. Broadband Microwave Wireless Power Transfer for Weak-Signal and Multipath Environments

    NASA Technical Reports Server (NTRS)

    Barton, Richard J.

    2014-01-01

    In this paper, we study the potential benefits of using relatively broadband wireless power transmission WPT strategies in both weak-signal and multipath environments where traditional narrowband strategies can be very inefficient. The paper is primarily a theoretical and analytical treatment of the problem that attempts to derive results that are widely applicable to many different WPT applications, including space solar power SSP.

  14. Fast signal transfer in a large-area X-ray CMOS image sensor

    NASA Astrophysics Data System (ADS)

    Kim, M. S.; Kang, D. U.; Lee, D. H.; Kim, H.; Cho, G.; Jae, M.

    2014-08-01

    For 2-d X-ray imaging, such as mammography and non-destructive test, a sensor should have a large-area because the sensor for typical X-ray beams cannot use optical lens system. To make a large-area 2-d X-ray image sensor using crystal Si, a technique of tiling unit CMOS image sensors into 2 × 2 or 2 × 3 array can be used. In a unit CMOS image sensor made of most common 8-inch Si wafers, the signal line can be up to ~ 180 mm long. Then its parasitic capacitance is up to ~ 25 pF and its resistance is up to ~ 51 kΩ (0.18 μm, 1P3M process). This long signal line may enlarge the row time up to ~ 50 μsec in case of the signal from the top row pixels to the readout amplifiers located at the bottom of the sensor chip. The output signal pulse is typically characterized by three components in sequence; a charging time (a rising part), a reading time and a discharging time (a falling part). Among these, the discharging time is the longest, and it limits the speed or the frame rate of the X-ray imager. We proposed a forced discharging method which uses a bypass transistor in parallel with the current source of the column signal line. A chip for testing the idea was fabricated by a 0.18 μm process. A active pixel sensor with three transistors and a 3-π RC model of the long line were simulated together. The test results showed that the turning on-and-off of the proposed bypass transistor only during the discharging time could dramatically reduce the discharging time from ~ 50 μsec to ~ 2 μsec, which is the physically minimum time determined by the long metal line capacitance.

  15. One-neutron transfer study of 137Xe and systematics of 13 /21+ and 13 /22+ levels in N =83 nuclei

    NASA Astrophysics Data System (ADS)

    Reviol, W.; Sarantites, D. G.; Elson, J. M.; Kinnison, J. E.; Gargano, A.; Bottoni, S.; Janssens, R. V. F.; Allmond, J. M.; Ayangeakaa, A. D.; Carpenter, M. P.; David, H. M.; Galindo-Uribarri, A.; Itaco, N.; Lauritsen, T.; Padilla-Rodal, E.; Zhu, S.

    2016-09-01

    Excited states in 137Xe have been studied by using the near-barrier single-neutron transfer reactions 13C (136Xe ,12C γ ) 137Xe and 9Be (136Xe ,8Be γ ) 137Xe in inverse kinematics. Particle-γ and particle-γ γ coincidence measurements have been performed with the Phoswich Wall and Digital Gammasphere detector arrays. Evidence is found for a 13 /22+ level (E =3137 keV ) and for additional high-lying 3 /2- and 5 /2- states. The results are discussed in the framework of realistic shell-model calculations. These calculations are also extended to the 13 /21+ and 13 /22+ levels in the N =83 isotonic chain. They indicate that there is a need for a value of the neutron 0 i13 /2 single-particle energy (ESPE=2366 keV ) lower than the one proposed in the literature. It is also demonstrated that the population patterns of the j =ℓ ±1 /2 single-particle states in 137Xe are different for the two targets used in these measurements and the implications of this effect are addressed.

  16. Neutron scatter camera

    DOEpatents

    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.

  17. Crystal structure of acetanilide at 15 and 295 K by neutron diffraction. Lack of evidence for proton transfer along the N-H...O hydrogen bond

    SciTech Connect

    Johnson, S.W.; Eckert, J.; Barthes, M.; McMullan, R.K.; Muller, M.

    1995-11-02

    The crystal structure of acetanilide C{sub 8}H{sub 9}NO, M{sub r} = 135.17, orthorhombic, space group Pbca, Z=8, has been determined from neutron diffraction data at 15 and 295 K. The crystal data obtained are presented. This new investigation of the structure of acetanilide has been undertaken in order to assess a recent suggestion that confirmational substates in the amide proton position may be responsible for the vibrational anomalies. We found no evidence for multiple conformations or transfer along the N-H...O hydrogen bond of the amide proton at either temperature. However the intramolecular O...H6 distance from O to the nearest phenyl ring proton is unusually short and the amide proton has relatively close contacts with one of the phenyl and one of the methyl protons, which may well affect the vibrational parameters of the respective molecular groups. 44 refs., 6 figs., 5 tabs.

  18. In-beam gamma-ray spectroscopy of {sup 248,250,252}Cf by neutron-transfer reactions using a Cf target

    SciTech Connect

    Takahashi, R.; Ishii, T.; Asai, M.; Nagae, D.; Makii, H.; Tsukada, K.; Toyoshima, A.; Ishii, Y.; Matsuda, M.; Makishima, A.; Shizuma, T.; Kohno, T.; Ogawa, M.

    2010-05-15

    The ground-state bands of {sup 248,250,252}Cf have been established up to the 10{sup +}, 12{sup +}, and 10{sup +} states, respectively, by in-beam gamma-ray spectroscopy using neutron-transfer reactions with a 153-MeV {sup 18}O beam and a highly radioactive Cf target. The deexcitation gamma rays in {sup 248,250,252}Cf were identified by taking coincidences with outgoing particles of {sup 16-19}O measured with Si DELTAE-E detectors, and by selecting their kinetic energies. Moments of inertia of {sup 248,250,252}Cf were discussed in terms of the N=152 deformed shell gap.

  19. Microbial translocation augments the function of adoptively transferred self/tumor-specific CD8+ T cells via TLR4 signaling

    PubMed Central

    Paulos, Chrystal M.; Wrzesinski, Claudia; Kaiser,, Andrew; Hinrichs, Christian S.; Chieppa, Marcello; Cassard, Lydie; Palmer, Douglas C.; Boni, Andrea; Muranski, Pawel; Yu, Zhiya; Gattinoni, Luca; Antony, Paul A.; Rosenberg, Steven A.; Restifo, Nicholas P.

    2007-01-01

    Lymphodepletion with total body irradiation (TBI) increases the efficacy of adoptively transferred tumor-specific CD8+ T cells by depleting inhibitory lymphocytes and increasing homeostatic cytokine levels. We found that TBI augmented the function of adoptively transferred CD8+ T cells in mice genetically deficient in all lymphocytes, indicating the existence of another TBI mechanism of action. Additional investigation revealed commensal gut microflora in the mesenteric lymph nodes and elevated LPS levels in the sera of irradiated mice. These findings correlated with increased dendritic cell activation and heightened levels of systemic inflammatory cytokines. Reduction of host microflora using antibiotics, neutralization of serum LPS using polymyxin B, or removal of LPS signaling components using mice genetically deficient in CD14 and TLR4 reduced the beneficial effects of TBI on tumor regression. Conversely, administration of microbial ligand–containing serum or ultrapure LPS from irradiated animals to nonirradiated antibody-lymphodepleted mice enhanced CD8+ T cell activation and improved tumor regression. Administration of ultrapure LPS to irradiated animals further enhanced the number and function of the adoptively transferred cells, leading to long-term cure of mice with large B16F10 tumors and enhanced autoimmune vitiligo. Thus, disruption of the homeostatic balance between the host and microbes can enhance cell-based tumor immunotherapy. PMID:17657310

  20. Structural insight into partner specificity and phosphoryl transfer in two-component signal transduction.

    PubMed

    Casino, Patricia; Rubio, Vicente; Marina, Alberto

    2009-10-16

    The chief mechanism used by bacteria for sensing their environment is based on two conserved proteins: a sensor histidine kinase (HK) and an effector response regulator (RR). The signal transduction process involves highly conserved domains of both proteins that mediate autokinase, phosphotransfer, and phosphatase activities whose output is a finely tuned RR phosphorylation level. Here, we report the structure of the complex between the entire cytoplasmic portion of Thermotoga maritima class I HK853 and its cognate, RR468, as well as the structure of the isolated RR468, both free and BeF(3)(-) bound. Our results provide insight into partner specificity in two-component systems, recognition of the phosphorylation state of each partner, and the catalytic mechanism of the phosphatase reaction. Biochemical analysis shows that the HK853-catalyzed autokinase reaction proceeds by a cis autophosphorylation mechanism within the HK subunit. The results suggest a model for the signal transduction mechanism in two-component systems.

  1. Displacement damage induce degradation of COTS array CCDs irradiated by neutron beams from a nuclear reactor

    NASA Astrophysics Data System (ADS)

    Wang, Zujun; Chen, Wei; Xiao, Zhigang; Liu, Minbo; Huang, Shaoyan; He, Baoping; Luo, Tongding

    2015-01-01

    The experiments of displacement damage effects on COTS array charge coupled devices (CCDs) induced by neutron irradiation from a nuclear reactor are presented. The charge transfer inefficiency (CTI), saturation output signal voltage (VS), dynamic range (DR), dark signal, and camera imaging quality versus neutron fluence are investigated. The degradation mechanisms of the CCDs irradiated by reactor neutron beams are also analyzed. The CTI increase due to neutron displacement damage appears to be proportional to displacement damage dose. The experiments show that VS degradation induced by neutron irradiation is much less than that induced by gamma irradiation. The dark images from the CCDs irradiated by neutrons are given to investigate dark signal degradation. The degradation forms and mechanisms of the camera imaging quality are very different between the reactor neutron displacement damage and the gamma total ionization dose damage. The three samples were exposed by 1 MeV neutron-equivalent fluences of 1×1011, 5×1011, and 1×1012 n/cm2, respectively. A sample was exposed by 1 MeV neutron-equivalent fluences up to 2×1013 n/cm2, and the CCD is a functional failure after irradiation.

  2. Dvr1 transfers left-right asymmetric signals from Kupffer's vesicle to lateral plate mesoderm in zebrafish.

    PubMed

    Peterson, Annita G; Wang, Xinghao; Yost, H Joseph

    2013-10-01

    An early step in establishing left-right (LR) symmetry in zebrafish is the generation of asymmetric fluid flow by Kupffer's vesicle (KV). As a result of fluid flow, a signal is generated and propagated from the KV to the left lateral plate mesoderm, activating a transcriptional response of Nodal expression in the left lateral plate mesoderm (LPM). The mechanisms and molecules that aid in this transfer of information from the KV to the left LPM are still not clear. Here we provide several lines of evidence demonstrating a role for a member of the TGFβ family member, Dvr1, a zebrafish Vg1 ortholog. Dvr1 is expressed bilaterally between the KV and the LPM. Knockdown of Dvr1 by morpholino causes dramatically reduced or absent expression of southpaw (spaw, a Nodal homolog), in LPM, and corresponding loss of downstream Lefty (lft1 and lft) expression, and aberrant brain and heart LR patterning. Dvr1 morphant embryos have normal KV morphology and function, normal expression of southpaw (spaw) and charon (cha) in the peri-KV region and normal expression of a variety of LPM markers in LPM. Additionally, Dvr1 knockdown does not alter the capability of LPM to respond to signals that initiate and propagate spaw expression. Co-injection experiments in Xenopus and zebrafish indicate that Dvr1 and Spaw can enhance each other's ability to activate the Nodal response pathway and co-immunoprecipitation experiments reveal differential relationships among activators and inhibitors in this pathway. These results indicate that Dvr1 is responsible for enabling the transfer of a left-right signal from KV to the LPM. PMID:23791819

  3. Dvr1 transfers left-right asymmetric signals from Kupffer's vesicle to lateral plate mesoderm in zebrafish.

    PubMed

    Peterson, Annita G; Wang, Xinghao; Yost, H Joseph

    2013-10-01

    An early step in establishing left-right (LR) symmetry in zebrafish is the generation of asymmetric fluid flow by Kupffer's vesicle (KV). As a result of fluid flow, a signal is generated and propagated from the KV to the left lateral plate mesoderm, activating a transcriptional response of Nodal expression in the left lateral plate mesoderm (LPM). The mechanisms and molecules that aid in this transfer of information from the KV to the left LPM are still not clear. Here we provide several lines of evidence demonstrating a role for a member of the TGFβ family member, Dvr1, a zebrafish Vg1 ortholog. Dvr1 is expressed bilaterally between the KV and the LPM. Knockdown of Dvr1 by morpholino causes dramatically reduced or absent expression of southpaw (spaw, a Nodal homolog), in LPM, and corresponding loss of downstream Lefty (lft1 and lft) expression, and aberrant brain and heart LR patterning. Dvr1 morphant embryos have normal KV morphology and function, normal expression of southpaw (spaw) and charon (cha) in the peri-KV region and normal expression of a variety of LPM markers in LPM. Additionally, Dvr1 knockdown does not alter the capability of LPM to respond to signals that initiate and propagate spaw expression. Co-injection experiments in Xenopus and zebrafish indicate that Dvr1 and Spaw can enhance each other's ability to activate the Nodal response pathway and co-immunoprecipitation experiments reveal differential relationships among activators and inhibitors in this pathway. These results indicate that Dvr1 is responsible for enabling the transfer of a left-right signal from KV to the LPM.

  4. [Study of TGF-β/Smad3 signal pathway using the technology of flurorescence resonance energy transfer].

    PubMed

    Cao, Weiwei; Liu, Wei; Wang, Weishan; Chen, Zhao; He, Renhao; He, Jianwei

    2014-10-01

    The transforming growth factor-β1 (TGF-β1)/Smad3 signal pathway is related to mutiple physiological and pathological generation mechanism of human being. Up to date, however, the spacial and time information on the phosphorylated Smad3 is still unclear. In this study, the process of Smad3 phosphorylation was observed under the physiological state in the living cells. Firstly, the ECFP-Smad3-Citrine (Smad3 biosensor) fusion protein expression vector was constructed and identified. Then the Smad3 biosensor was transfected into 293T cells. The transfection efficiency and the expressions of fusion proteins were observed in 24 hours. Thirdly, Smad3 biosensor flurorescence resonance energy transfer (FRET) was observed with the inversion fluorescence microscope and measured by the MetaFlour FRET 4. 6 software. Smad3 biosensor transfection efficiency was nearly 40% and the fusion protein was seen under the fluorescence microscope. The FRET ratio of Smad3 biosensor in living 293T cells was decreased after 10 minutes incubation with the ligand of TGF-β1. The period of decreasing CFP and enhancing Citrine signals was about 300 seconds. With the technology of FRET, the TGF-β1/Smad3 signal pathway could be real time monitored dynamically under the physiological condition in living cells.

  5. A Perspective on Studying G-Protein–Coupled Receptor Signaling with Resonance Energy Transfer Biosensors in Living Organisms

    PubMed Central

    van Unen, Jakobus; Woolard, Jeanette; Rinken, Ago; Hoffmann, Carsten; Hill, Stephen J.; Goedhart, Joachim; Bruchas, Michael R.; Bouvier, Michel

    2015-01-01

    The last frontier for a complete understanding of G-protein–coupled receptor (GPCR) biology is to be able to assess GPCR activity, interactions, and signaling in vivo, in real time within biologically intact systems. This includes the ability to detect GPCR activity, trafficking, dimerization, protein-protein interactions, second messenger production, and downstream signaling events with high spatial resolution and fast kinetic readouts. Resonance energy transfer (RET)–based biosensors allow for all of these possibilities in vitro and in cell-based assays, but moving RET into intact animals has proven difficult. Here, we provide perspectives on the optimization of biosensor design, of signal detection in living organisms, and the multidisciplinary development of in vitro and cell-based assays that more appropriately reflect the physiologic situation. In short, further development of RET-based probes, optical microscopy techniques, and mouse genome editing hold great potential over the next decade to bring real-time in vivo GPCR imaging to the forefront of pharmacology. PMID:25972446

  6. Transferring intercellular signals and traits between cancer cells: extracellular vesicles as "homing pigeons".

    PubMed

    Cesi, Giulia; Walbrecq, Geoffroy; Margue, Christiane; Kreis, Stephanie

    2016-01-01

    Extracellular vesicles are cell-derived vesicles, which can transport various cargos out of cells. From their cell of origin, the content molecules (proteins, non-coding RNAs including miRNAs, DNA and others) can be delivered to neighboring or distant cells and as such extracellular vesicles can be regarded as vehicles of intercellular communication or "homing pigeons". Extracellular vesicle shuttling is able to actively modulate the tumor microenvironment and can partake in tumor dissemination. In various diseases, including cancer, levels of extracellular vesicle secretion are altered resulting in different amounts and/or profiles of detectable vesicular cargo molecules and these distinct content profiles are currently being evaluated as biomarkers. Apart from their potential as blood-derived containers of specific biomarkers, the transfer of extracellular vesicles to surrounding cells also appears to be involved in the propagation of phenotypic traits. These interesting properties have put extracellular vesicles into the focus of many recent studies.Here we review findings on the involvement of extracellular vesicles in transferring traits of cancer cells to their surroundings and briefly discuss new data on oncosomes, a larger type of vesicle. A pressing issue in cancer treatment is rapidly evolving resistance to many initially efficient drug therapies. Studies investigating the role of extracellular vesicles in this phenomenon together with a summary of the technical challenges that this field is still facing, are also presented. Finally, emerging areas of research such as the analysis of the lipid composition on extracellular vesicles and cutting-edge techniques to visualise the trafficking of extracellular vesicles are discussed. PMID:27282631

  7. Transmembrane signaling and assembly of the cytochrome b6f-lipidic charge transfer complex.

    PubMed

    Saif Hasan, S; Yamashita, Eiki; Cramer, William A

    2013-01-01

    Structure-function properties of the cytochrome b6f complex are sufficiently unique compared to those of the cytochrome bc1 complex that b6f should not be considered a trivially modified bc1 complex. A unique property of the dimeric b6f complex is its involvement in transmembrane signaling associated with the p-side oxidation of plastoquinol. Structure analysis of lipid binding sites in the cyanobacterial b6f complex prepared by hydrophobic chromatography shows that the space occupied by the H transmembrane helix in the cytochrome b subunit of the bc1 complex is mostly filled by a lipid in the b6f crystal structure. It is suggested that this space can be filled by the domain of a transmembrane signaling protein. The identification of lipid sites and likely function defines the intra-membrane conserved central core of the b6f complex, consisting of the seven trans-membrane helices of the cytochrome b and subunit IV polypeptides. The other six TM helices, contributed by cytochrome f, the iron-sulfur protein, and the four peripheral single span subunits, define a peripheral less conserved domain of the complex. The distribution of conserved and non-conserved domains of each monomer of the complex, and the position and inferred function of a number of the lipids, suggests a model for the sequential assembly in the membrane of the eight subunits of the b6f complex, in which the assembly is initiated by formation of the cytochrome b6-subunit IV core sub-complex in a monomer unit. Two conformations of the unique lipidic chlorophyll a, defined in crystal structures, are described, and functions of the outlying β-carotene, a possible 'latch' in supercomplex formation, are discussed. This article is part of a Special Issue entitled: Respiratory complex III and related bc complexes. PMID:23507619

  8. Transmembrane signaling and assembly of the cytochrome b6f-lipidic charge transfer complex.

    PubMed

    Saif Hasan, S; Yamashita, Eiki; Cramer, William A

    2013-01-01

    Structure-function properties of the cytochrome b6f complex are sufficiently unique compared to those of the cytochrome bc1 complex that b6f should not be considered a trivially modified bc1 complex. A unique property of the dimeric b6f complex is its involvement in transmembrane signaling associated with the p-side oxidation of plastoquinol. Structure analysis of lipid binding sites in the cyanobacterial b6f complex prepared by hydrophobic chromatography shows that the space occupied by the H transmembrane helix in the cytochrome b subunit of the bc1 complex is mostly filled by a lipid in the b6f crystal structure. It is suggested that this space can be filled by the domain of a transmembrane signaling protein. The identification of lipid sites and likely function defines the intra-membrane conserved central core of the b6f complex, consisting of the seven trans-membrane helices of the cytochrome b and subunit IV polypeptides. The other six TM helices, contributed by cytochrome f, the iron-sulfur protein, and the four peripheral single span subunits, define a peripheral less conserved domain of the complex. The distribution of conserved and non-conserved domains of each monomer of the complex, and the position and inferred function of a number of the lipids, suggests a model for the sequential assembly in the membrane of the eight subunits of the b6f complex, in which the assembly is initiated by formation of the cytochrome b6-subunit IV core sub-complex in a monomer unit. Two conformations of the unique lipidic chlorophyll a, defined in crystal structures, are described, and functions of the outlying β-carotene, a possible 'latch' in supercomplex formation, are discussed. This article is part of a Special Issue entitled: Respiratory complex III and related bc complexes.

  9. The Si elegans connectome: A neuromimetic emulation of neural signal transfer with DMD-structured light

    NASA Astrophysics Data System (ADS)

    Petrushin, Alexey; Ferrara, Lorenzo; Blau, Axel

    2015-03-01

    Our current understanding of brain function is still too limited to take advantage of the computational power of even the simplest biological nervous systems. To fill this gap, the Si elegans project (www.si-elegans.eu) aims at developing a computational framework that will replicate the nervous system and rich behavior of the nematode Caenorhabditis elegans, a tiny worm with just 302 neurons. One key element of this emulation testbed is an electro-optical, micromirrorbased connectome. Unlike any other current ICT communication protocol, we expect it to accurately mimic the parallel information transfer between neurons. This strategy promises to give new insights into the nature of two hypothesized key mechanisms - the parallel and precisely timed information flow - that make brains excel von-Neumann-type machines. In this contribution, we briefly introduce the overall Si elegans concept to then describe the requirements for designing a light-based connectome within the given boundary conditions imposed by the hardware infrastructure it will be integrated into.

  10. HIV-1 Tat Regulates Occludin and Aβ Transfer Receptor Expression in Brain Endothelial Cells via Rho/ROCK Signaling Pathway

    PubMed Central

    Chen, Yanlan; Jiang, Wenlin; Wu, Xianghong; Ye, Biao; Zhou, Xiaoting

    2016-01-01

    HIV-1 transactivator protein (Tat) has been shown to play an important role in HIV-associated neurocognitive disorders. The aim of the present study was to evaluate the relationship between occludin and amyloid-beta (Aβ) transfer receptors in human cerebral microvascular endothelial cells (hCMEC/D3) in the context of HIV-1-related pathology. The protein expressions of occludin, receptor for advanced glycation end products (RAGE), and low-density lipoprotein receptor-related protein 1 (LRP1) in hCMEC/D3 cells were examined using western blotting and immunofluorescent staining. The mRNA levels of occludin, RAGE, and LRP1 were measured using quantitative real-time polymerase chain reaction. HIV-1 Tat at 1 µg/mL and the Rho inhibitor hydroxyfasudil (HF) at 30 µmol/L, with 24 h exposure, had no significant effect on hCMEC/D3 cell viability. Treatment with HIV-1 Tat protein decreased mRNA and protein levels of occludin and LRP1 and upregulated the expression of RAGE; however, these effects were attenuated by HF. These data suggest that the Rho/ROCK signaling pathway is involved in HIV-1 Tat-mediated changes in occludin, RAGE, and LRP1 in hCMEC/D3 cells. HF may have a beneficial influence by protecting the integrity of the blood-brain barrier and the expression of Aβ transfer receptors. PMID:27563375

  11. How dangerous are phthalate plasticizers? Integrated approach to toxicity based on metabolism, electron transfer, reactive oxygen species and cell signaling.

    PubMed

    Kovacic, Peter

    2010-04-01

    Phthalate plasticizers are the most abundant man-made pollutants that have recently received wide-spread attention. There is uncertainty concerning the toxicity to humans. During the debate, scant attention has been paid to adverse effects at the molecular level which is the focus of this article. Most metabolic reports are concerned only with ester hydrolysis. In addition to that aspect, an important study deals with formation of catechol carboxylic acids which have the potential to redox cycle with the o-quinone counterparts. This electron transfer (ET) process is capable of generating reactive oxygen species (ROS) which are well known toxic agents at elevated levels. Substantial numbers of investigations find the presence of ROS leading to oxidative stress (OS) in living systems containing phthalates. Insults occur to various organs, including the reproductive system, pulmonary, central nervous system, immune system and liver. Toxic reactions are also reported involving inflammation, mitochondria and carcinogenicity. Generally, OS evidently plays a role. Of relevance are prior reviews which document extensive evidence for association of ET-ROS-OS with organ toxicity, and other deleterious reactions. In addition, cell signaling has been related to the physiological effects of phthalates. Various signaling processes participate together with involvement of ROS and association with biological effects. Suggestions for future work are offered.

  12. Comparison of NSTX FIDA, Charge Exchange, and Neutron Fluxes with Calculated Signals Based on CQL3D-FOW Distribution Functions

    NASA Astrophysics Data System (ADS)

    Harvey, R. W.; Petrov, Yu. V.; Kinsey, J. E.; Liu, D.; Heidbrink, W. W.; Taylor, G.; Bonoli, P. T.

    2014-10-01

    Ion distribution function calculations with CQL3D have been substantially advanced through implementation of guiding-center-orbit-based Fokker-Planck Coefficients. The resulting finite-orbit-width (FOW) calculations are carried out with a fast CQL3D-Hybrid-FOW option, and in a slower but neoclassically complete (except no Er yet) CQL3D-FOW option. Good comparison between time-dependent Fast Ion Diagnostic FIDA, NPA, and neutron signals resulting from neutral beaminjection(NBI) and high harmonic fast wave (HHFW) power injected into the NSTX spherical tokamak have been simulated with the CQL3D-Hybrid-FOW, using only the FOW effects on QL diffusion, and particle losses, direct and CX. Comparisons are also made with recent CQL3D-FOW results, as well as between the original FIDA calculation code and a recent fortran version. Supported by USDOE Grants SC0006614, ER54744, and ER44649.

  13. Fusion and neutron transfer reactions with weakly bound nuclei within time-dependent and coupled channel approaches

    NASA Astrophysics Data System (ADS)

    Samarin, V. V.

    2016-05-01

    The time-dependent Schrödinger equation and the coupled channel approach based on the method of perturbed stationary two-center states are used to describe nucleon transfers and fusion in low-energy nuclear reactions. Results of the cross sections calculation for the formation of the 198Au and fusion in the 6He+197Au reaction and for the formation of the 65Zn in 6He+64Zn reaction agree satisfactorily with the experimental data near the barrier. The Feynman's continual integrals calculations for a few-body systems were used for the proposal of the new form of the shell model mean field for helium isotopes.

  14. Simulations of thermally transferred OSL signals in quartz: Accuracy and precision of the protocols for equivalent dose evaluation

    NASA Astrophysics Data System (ADS)

    Pagonis, Vasilis; Adamiec, Grzegorz; Athanassas, C.; Chen, Reuven; Baker, Atlee; Larsen, Meredith; Thompson, Zachary

    2011-06-01

    Thermally-transferred optically stimulated luminescence (TT-OSL) signals in sedimentary quartz have been the subject of several recent studies, due to the potential shown by these signals to increase the range of luminescence dating by an order of magnitude. Based on these signals, a single aliquot protocol termed the ReSAR protocol has been developed and tested experimentally. This paper presents extensive numerical simulations of this ReSAR protocol. The purpose of the simulations is to investigate several aspects of the ReSAR protocol which are believed to cause difficulties during application of the protocol. Furthermore, several modified versions of the ReSAR protocol are simulated, and their relative accuracy and precision are compared. The simulations are carried out using a recently published kinetic model for quartz, consisting of 11 energy levels. One hundred random variants of the natural samples were generated by keeping the transition probabilities between energy levels fixed, while allowing simultaneous random variations of the concentrations of the 11 energy levels. The relative intrinsic accuracy and precision of the protocols are simulated by calculating the equivalent dose (ED) within the model, for a given natural burial dose of the sample. The complete sequence of steps undertaken in several versions of the dating protocols is simulated. The relative intrinsic precision of these techniques is estimated by fitting Gaussian probability functions to the resulting simulated distribution of ED values. New simulations are presented for commonly used OSL sensitivity tests, consisting of successive cycles of sample irradiation with the same dose, followed by measurements of the sensitivity corrected L/T signals. We investigate several experimental factors which may be affecting both the intrinsic precision and intrinsic accuracy of the ReSAR protocol. The results of the simulation show that the four different published versions of the ReSAR protocol can

  15. Resonant tidal excitation of superfluid neutron stars in coalescing binaries

    NASA Astrophysics Data System (ADS)

    Yu, Hang; Weinberg, Nevin N.

    2016-10-01

    We study the resonant tidal excitation of g-modes in coalescing superfluid neutron star binaries and investigate how such tidal driving impacts the gravitational-wave signal of the inspiral. Previous studies of this type treated the neutron star core as a normal fluid and thus did not account for its expected superfluidity. The source of buoyancy that supports the g-modes is fundamentally different in the two cases: in a normal fluid core the buoyancy is due to gradients in the proton-to-neutron fraction whereas in a superfluid core it is due to gradients in the muon-to-electron fraction. The latter yields a stronger stratification and a superfluid neutron star therefore has a denser spectrum of g-modes with frequencies above 10Hz. As a result, many more g-modes undergo resonant tidal excitation as the binary sweeps through the bandwidth of gravitational-wave detectors such as LIGO. We find that ≃ 10 times more orbital energy is transferred into g-mode oscillations if the neutron star has a superfluid core rather than a normal fluid core. However, because this energy is transferred later in the inspiral when the orbital decay is faster, the accumulated phase error in the gravitational waveform is comparable for a superfluid and normal fluid neutron star (˜10-3 - 10-2radians). A phase error of this magnitude is too small to be measured from a single event with the current generation of gravitational wave detectors.

  16. One-neutron transfer study of Xe137 and systematics of 13/21+ and 13/22+ levels in N=83 nuclei

    DOE PAGESBeta

    Reviol, W.; Sarantites, D. G.; Elson, J. M.; Kinnison, J. E.; Gargano, A.; Bottoni, S.; Janssens, R. V. F.; Allmond, James M.; Ayangeakaa, A. D.; Carpenter, M. P.; et al

    2016-09-08

    Excited states in 137Xe have been studied by using the near-barrier single-neutron transfer reactions 13C(136Xe,12C )137Xe and 9Be(136Xe,8Be )137Xe in inverse kinematics.Particle- and particle- coincidence measurements have been performed with the Phoswich Wall and Digital Gammasphere detector arrays. Evidence is found for a 13/2+2 level (E = 3137 keV) and for additional high-lying 3/2– and 5/2– states. The results are discussed in the framework of realistic shell-model calculations. These calculations are also extended to the 13/2+1 and 13/2+2 levels in the N = 83 isotonic chain. Furthermore, they indicate that there is a need for a value of the neutronmore » 0i13/2 single-particle energy (ESPE = 2366 keV) lower than the one proposed in the literature. It is also demonstrated that the population patterns of the j = l ± 1/2 single-particle states in 137Xe are different for the two targets used in these measurements and the implications of this effect are addressed.« less

  17. Ototoxicity and noise trauma: electron transfer, reactive oxygen species, cell signaling, electrical effects, and protection by antioxidants: practical medical aspects.

    PubMed

    Kovacic, Peter; Somanathan, Ratnasamy

    2008-01-01

    Ototoxins are substances of various structures and classes. This review provides extensive evidence for involvement of electron transfer (ET), reactive oxygen species (ROS) and oxidative stress (OS) as a unifying theme. Successful application is made to the large majority of ototoxins, as well as noise trauma. We believe it is not coincidental that these toxins generally incorporate ET functionalities (quinone, metal complex, ArNO(2), or conjugated iminium) either per se or in metabolites, potentially giving rise to ROS by redox cycling. Some categories, e.g., peroxides and noise, appear to operate via non-ET routes in generating OS. These highly reactive entities can then inflict injury via OS upon various constituents of the ear apparatus. The theoretical framework is supported by the extensive literature on beneficial effects of antioxidants, both for toxins and noise. Involvement of cell signaling and electrical effects are discussed. This review is the first comprehensive one based on a unified mechanistic approach. Various practical medical aspects are also addressed. There is extensive documentation for beneficial effects of antioxidants whose use might be recommended clinically for prevention of ototoxicity and noise trauma. Recent research indicates that catalytic antioxidants may be more effective. In addition to ototoxicity, a widespread problem consists of ear infections by bacteria which are demonstrating increasing resistance to conventional therapies. A recent, novel approach to improved drugs involves use of agents which inhibit quorum sensors that play important roles in bacterial functioning. Prevention of ear injury by noise trauma is also discussed, along with ear therapeutics.

  18. Apparatus for measuring a flux of neutrons

    DOEpatents

    Stringer, James L.

    1977-01-01

    A flux of neutrons is measured by disposing a detector in the flux and applying electronic correlation techniques to discriminate between the electrical signals generated by the neutron detector and the unwanted interfering electrical signals generated by the incidence of a neutron flux upon the cables connecting the detector to the electronic measuring equipment at a remote location.

  19. Data analysis of gravitational-wave signals from spinning neutron stars. V. A narrow-band all-sky search

    SciTech Connect

    Astone, Pia; Borkowski, Kazimierz M.; Jaranowski, Piotr; Pietka, Maciej; Krolak, Andrzej

    2010-07-15

    We present theory and algorithms to perform an all-sky coherent search for periodic signals of gravitational waves in narrow-band data of a detector. Our search is based on a statistic, commonly called the F-statistic, derived from the maximum-likelihood principle in Paper I of this series. We briefly review the response of a ground-based detector to the gravitational-wave signal from a rotating neuron star and the derivation of the F-statistic. We present several algorithms to calculate efficiently this statistic. In particular our algorithms are such that one can take advantage of the speed of fast Fourier transform in calculation of the F-statistic. We construct a grid in the parameter space such that the nodes of the grid coincide with the Fourier frequencies. We present interpolation methods that approximately convert the two integrals in the F-statistic into Fourier transforms so that the fast Fourier transform algorithm can be applied in their evaluation. We have implemented our methods and algorithms into computer codes and we present results of the Monte Carlo simulations performed to test these codes.

  20. Evidence of Spin Resonance Signal in Oxygen Free Superconducting CaFe0.88Co0.12AsF: An Inelastic Neutron Scattering Study

    NASA Astrophysics Data System (ADS)

    Price, Stephen; Su, Yixi; Xiao, Yinguo; Adroja, Devashibhai T.; Guidi, Tatiana; Mittal, Ranjan; Nandi, Shibabrata; Matsuishi, Satoru; Hosono, Hideo; Brückel, Thomas

    2013-10-01

    The spin excitation spectrum of optimally doped superconducting CaFe0.88Co0.12AsF (Tc˜ 22 K) was studied by means of time-of-flight (ToF) inelastic neutron scattering experiments on a powder sample for temperatures above and below Tc and energies up to 15 meV. In the superconducting state, the spin resonance signal is observed as an enhancement of spectral weight of particle hole excitations of approximately 1.5 times relative to normal state excitations. The resonance energy ER˜ 7 meV scales to Tc via 3.7 kBTc which is in reasonable agreement to the scaling relation reported for other Fe-based compositions. For energies below 5 meV the spectrum of spin flip particle hole excitations in the superconducting state exhibits a strong reduction in spectral weight, indicating the opening of the spin gap. Nonetheless, a complete suppression of magnetic response cannot be observed. In contrast, the normal state spin excitations are not gapped and strongly two dimensional spin fluctuations persist up to temperatures at least as high as 150 K.

  1. 1Application of Fluorescence Resonance Energy Transfer and Magnetic Twisting Cytometry to Quantitate Mechano-Chemical Signaling Activities in a Living Cell

    PubMed Central

    Na, Sungsoo; Wang, Ning

    2009-01-01

    Mechanotransduction is the process by which living cells sense mechanical forces and then convert them into biochemical signaling. Recently we showed that mechanical stress is transduced from the cell surface to remote cytoplasmic sites within 0.3 s, which is at least 40 to 50 times faster than soluble factor-induced signal transduction, and the sites of mechanotransduction colocalize with sites where mechanical stress causes microtubule displacement. These results suggest that mechanotransduction employs mechanisms different from those of soluble factor-induced signal transduction. Here we describe a protocol that utilizes fluorescence resonance energy transfer (FRET) and a magnetic twisting cytometry (MTC) device to capture rapid mechano-chemical signaling activities in living cells. PMID:18728305

  2. Determination of the 233Pa(n, f) reaction cross section from 0.5 to 10 MeV neutron energy using the transfer reaction 232Th( 3He, p) 234Pa

    NASA Astrophysics Data System (ADS)

    Petit, M.; Aiche, M.; Barreau, G.; Boyer, S.; Carjan, N.; Czajkowski, S.; Dassié, D.; Grosjean, C.; Guiral, A.; Haas, B.; Karamanis, D.; Misicu, S.; Rizea, C.; Saintamon, F.; Andriamonje, S.; Bouchez, E.; Gunsing, F.; Hurstel, A.; Lecoz, Y.; Lucas, R.; Theisen, Ch.; Billebaud, A.; Perrot, L.; Bauge, E.

    2004-05-01

    The fission probability distributions of 232, 233, 234 Pa and 231Th have been measured up to an excitation energy of 15 MeV, using the transfer reactions 232Th( 3He, t) 232Pa, 232Th( 3He, d) 233Pa, 232Th( 3He, p) 234Pa and 232Th( 3He, 4He) 231Th. From these measurements, the neutron induced fission cross sections of 231Pa, 233Pa and 230Th have been determined from the product of the fission probabilities of 232Pa, 233Pa and 231Th respectively with the calculated compound nucleus formation cross sections in the 231Pa+n, 233Pa+n and 230Th+n reactions. The validity of the applied method has been successfully tested with the existing neutron induced fission cross sections of 230Th and 231Pa. Special emphasis is put on the 233Pa(n, f) reaction which is of importance for thorium fueled nuclear reactors. Based on a statistical model analysis of the neutron induced fission cross section as a function of neutron energy, it has been possible to determine the barrier parameters of the 234Pa fissioning nucleus. Cross sections for the compound nucleus inelastic scatttering 233Pa(n, n') and radiative capture 233Pa(n, γ) reactions have also been calculated and compared with recent evaluations.

  3. FPGA Implementation of 2D Signals Encoder Using QMF Based Dyadic DWT: Application to Neutron Tomography Projections

    NASA Astrophysics Data System (ADS)

    Saadi, S.; Touiza, M.; Guessoum, A.

    In this study, we present an implementation on FPGA of 2D signals Encoder/Decoder using dyadic Discrete Wavelet Transform based on quadrature mirror filters, by applying fast wavelet Mallat`s algorithm. The wavelet coefficients will be encoded by Huffman code in order to be transmitted progressively through an Ethernet TCP/IP based connection. The proposed study is implemented and synthesized in VHDL for Xilinx Virtex-IIV2MB1000 FPGA device using ISE 8.1 and simulated on Modelsim PE 6.0d. The synthesis results are presented in detail. The proposed design can substantially accelerate the DWT and the possible reconfiguration can be exploited to reach a higher performance in the future. The system is designed to be integrated as an extension to the nuclear imaging system implemented around our nuclear research reactor. Assuming a Pentium4 processor with clock frequency of 3.3 GHz for the Matlab software implementation, a speed up of over 5 times for a picture size of 256 x 256 was achieved.

  4. THERMAL NEUTRON BACKSCATTER IMAGING.

    SciTech Connect

    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.

  5. Neutron reflectometry: Filling Δq with neutrons

    NASA Astrophysics Data System (ADS)

    Pleshanov, N. K.

    2016-06-01

    Luminosity of the reflectometer is defined as the neutron flux incident onto the sample surface for measurements made with a given momentum transfer resolution Δq. The filling of Δq with neutrons near a certain q depends not only on the source luminance and the source-sample tract transmittance, but also on the neutron beam tailoring. The correct choice of the working wavelength and measurements with optimum neutron beam parameters increase luminosity in several times. New optimization criteria for neutron reflectometers are suggested. Standard schemes of the reflectivity measurement with monochromatic and white beams are re-examined. Optimization of reflectivity measurements generally requires numerical calculations. Analytically, its potential is demonstrated by considering thermalized neutron beams. Such innovations as velocity selector on the basis of aperiodic multilayers, small angle Soller collimator with traps for neutrons reflected from the channel walls and fan beam time-of-flight technique are proposed to further increase the luminosity of reflectometers.

  6. Shifting scintillator neutron detector

    SciTech Connect

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

    2014-03-04

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

  7. Estimation of the propagation direction and spectral properties of the EEG signals registered during sevoflurane anaesthesia using Directed Transfer Function method

    NASA Astrophysics Data System (ADS)

    Olejarczyk, Elzbieta; Kaminski, Maciej; Marciniak, Radoslaw; Byrczek, Tomasz; Stasiowski, Michal; Jalowiecki, Przemyslaw; Sobieszek, Aleksander; Zmyslowski, Wojciech

    2011-01-01

    The aim of this study was to estimate spectral properties and propagation of the EEG signals registered during sevoflurane anaesthesia between individual EEG recording channels. The intensities of activity flows were calculated for delta, theta, alpha and beta waves using the Directed Transfer Function integration procedure. It was found that delta waves played the dominant role in the EEG signal propagation during anesthesia and it was suggested that theta and alpha waves propagation could be related to the processes participating in the wakefulness control. Data obtained with DTF method were compared with data received from the analysis of cerebral blood flow with the use of PET in other laboratory. This study showed that analysis of the EEG signal propagation is useful for better understanding and thus safer induction of anaesthesia procedure.

  8. Compact ion chamber based neutron detector

    DOEpatents

    Derzon, Mark S.; Galambos, Paul C.; Renzi, Ronald F.

    2015-10-27

    A directional neutron detector has an ion chamber formed in a dielectric material; a signal electrode and a ground electrode formed in the ion chamber; a neutron absorbing material filling the ion chamber; readout circuitry which is electrically coupled to the signal and ground electrodes; and a signal processor electrically coupled to the readout circuitry. The ion chamber has a pair of substantially planar electrode surfaces. The chamber pressure of the neutron absorbing material is selected such that the reaction particle ion trail length for neutrons absorbed by the neutron absorbing material is equal to or less than the distance between the electrode surfaces. The signal processor is adapted to determine a path angle for each absorbed neutron based on the rise time of the corresponding pulse in a time-varying detector signal.

  9. NEUTRON IMAGING, RADIOGRAPHY AND TOMOGRAPHY.

    SciTech Connect

    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.

  10. MEASUREMENT OF THE RADIUS OF NEUTRON STARS WITH HIGH SIGNAL-TO-NOISE QUIESCENT LOW-MASS X-RAY BINARIES IN GLOBULAR CLUSTERS

    SciTech Connect

    Guillot, Sebastien; Rutledge, Robert E.; Servillat, Mathieu; Webb, Natalie A. E-mail: rutledge@physics.mcgill.ca

    2013-07-20

    This paper presents the measurement of the neutron star (NS) radius using the thermal spectra from quiescent low-mass X-ray binaries (qLMXBs) inside globular clusters (GCs). Recent observations of NSs have presented evidence that cold ultra dense matter-present in the core of NSs-is best described by ''normal matter'' equations of state (EoSs). Such EoSs predict that the radii of NSs, R{sub NS}, are quasi-constant (within measurement errors, of {approx}10%) for astrophysically relevant masses (M{sub NS}>0.5 M{sub Sun }). The present work adopts this theoretical prediction as an assumption, and uses it to constrain a single R{sub NS} value from five qLMXB targets with available high signal-to-noise X-ray spectroscopic data. Employing a Markov chain Monte-Carlo approach, we produce the marginalized posterior distribution for R{sub NS}, constrained to be the same value for all five NSs in the sample. An effort was made to include all quantifiable sources of uncertainty into the uncertainty of the quoted radius measurement. These include the uncertainties in the distances to the GCs, the uncertainties due to the Galactic absorption in the direction of the GCs, and the possibility of a hard power-law spectral component for count excesses at high photon energy, which are observed in some qLMXBs in the Galactic plane. Using conservative assumptions, we found that the radius, common to the five qLMXBs and constant for a wide range of masses, lies in the low range of possible NS radii, R{sub NS}=9.1{sup +1.3}{sub -1.5} km (90%-confidence). Such a value is consistent with low-R{sub NS} equations of state. We compare this result with previous radius measurements of NSs from various analyses of different types of systems. In addition, we compare the spectral analyses of individual qLMXBs to previous works.

  11. Personnel electronic neutron dosimeter

    DOEpatents

    Falk, R.B.; Tyree, W.H.

    1982-03-03

    A personnel electronic dosimeter includes a neutron-proton and neutron-alpha converter for providing an electrical signal having a magnitude proportional to the energy of a detected proton or alpha particle produced from the converter, a pulse generator circuit for generating a pulse having a duration controlled by the weighed effect of the amplitude of the electrical signal, an oscillator enabled by the pulse for generating a train of clock pulses for a time dependent upon the pulse length, a counter for counting the clock pulses, and an indicator for providing a direct reading and aural alarm when the count indicates that the wearer has been exposed to a selected level of neutron dose equivalent.

  12. Personnel electronic neutron dosimeter

    DOEpatents

    Falk, Roger B.; Tyree, William H.

    1984-12-18

    A personnel electronic dosimeter includes a neutron-proton and neutron-alpha converter for providing an electrical signal having a magnitude proportional to the energy of a detected proton or alpha particle produced from the converter, a pulse generator circuit for generating a pulse having a duration controlled by the weighed effect of the amplitude of the electrical signal, an oscillator enabled by the pulse for generating a train of clock pulses for a time dependent upon the pulse length, a counter for counting the clock pulses, and an indicator for providing a direct reading and aural alarm when the count indicates that the wearer has been exposed to a selected level of neutron dose equivalent.

  13. Atmospheric neutrons

    NASA Technical Reports Server (NTRS)

    Korff, S. A.; Mendell, R. B.; Merker, M.; Light, E. S.; Verschell, H. J.; Sandie, W. S.

    1979-01-01

    Contributions to fast neutron measurements in the atmosphere are outlined. The results of a calculation to determine the production, distribution and final disappearance of atmospheric neutrons over the entire spectrum are presented. An attempt is made to answer questions that relate to processes such as neutron escape from the atmosphere and C-14 production. In addition, since variations of secondary neutrons can be related to variations in the primary radiation, comment on the modulation of both radiation components is made.

  14. Neutron guide

    DOEpatents

    Greene, Geoffrey L.

    1999-01-01

    A neutron guide in which lengths of cylindrical glass tubing have rectangular glass plates properly dimensioned to allow insertion into the cylindrical glass tubing so that a sealed geometrically precise polygonal cross-section is formed in the cylindrical glass tubing. The neutron guide provides easier alignment between adjacent sections than do the neutron guides of the prior art.

  15. Neutron dosimetry

    DOEpatents

    Quinby, Thomas C.

    1976-07-27

    A method of measuring neutron radiation within a nuclear reactor is provided. A sintered oxide wire is disposed within the reactor and exposed to neutron radiation. The induced radioactivity is measured to provide an indication of the neutron energy and flux within the reactor.

  16. Coded source neutron imaging

    SciTech Connect

    Bingham, Philip R; Santos-Villalobos, Hector J

    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.

  17. Neutron-image intensifier

    NASA Technical Reports Server (NTRS)

    Berger, H.

    1970-01-01

    Electronic intensifier tube with a demagnification ratio of 9-1 enhances the usefulness of neutron-radiographic techniques. A television signal can be obtained by optical coupling of a small-output phosphor-light image to a television camera.

  18. Multifunctional reduced graphene oxide trigged chemiluminescence resonance energy transfer: Novel signal amplification strategy for photoelectrochemical immunoassay of squamous cell carcinoma antigen.

    PubMed

    Zhang, Yan; Sun, Guoqiang; Yang, Hongmei; Yu, Jinghua; Yan, Mei; Song, Xianrang

    2016-05-15

    Herein, a photoelectrochemical (PEC) immunoassay is constructed for squamous cell carcinoma antigen (SCCA) detection using zinc oxide nanoflower-bismuth sulfide (Bi2S3) composites as photoactive materials and reduced graphene oxide (rGO) as signal labels. Horseradish peroxidase is used to block sites against nonspecific binding, and then participated in luminol-based chemiluminescence (CL) system. The induced CL emission is acted as an inner light source to excite photoactive materials, simplifying the instrument. A novel signal amplification strategy is stem from rGO because of the rGO acts as an energy acceptor, while luminol serves as a donor to rGO, triggering the CL resonance energy transfer phenomenon between luminol and rGO. Thus, the efficient CL emission to photoactive materials decreases. Furthermore, the signal amplification caused by rGO labeled signal antibodies is related to photogenerated electron-hole pairs: perfect matching of energy levels between rGO and Bi2S3 makes rGO a sink to capture photogenerated electrons from Bi2S3; the increased steric hindrance hinders the electron donor to the surface of Bi2S3 for reaction with the photogenerated holes. On the basis of the novel signal amplification strategy, the proposed immunosensor exhibits excellent analytical performance for PEC detection of SCCA, ranging from 0.8 pg mL(-1) to 80 ng mL(-1) with a low detection limit of 0.21 pg mL(-1). Meanwhile, the designed signal amplification strategy provides a general format for future development of PEC assays. PMID:26686924

  19. Probing neutron rich matter with parity violation

    NASA Astrophysics Data System (ADS)

    Horowitz, Charles

    2016-03-01

    Many compact and energetic astrophysical systems are made of neutron rich matter. In contrast, most terrestrial nuclei involve approximately symmetric nuclear matter with more equal numbers of neutrons and protons. However, heavy nuclei have a surface region that contains many extra neutrons. Precision measurements of this neutron rich skin can determine properties of neutron rich matter. Parity violating electron scattering provides a uniquely clean probe of neutrons, because the weak charge of a neutron is much larger than that of a proton. We describe first results and future plans for the Jefferson Laboratory experiment PREX that measures the thickness of the neutron skin in 208Pb. Another JLAB experiment CREX will measure the neutron radius of 48Ca and test recent microscopic calculations of this neutron rich 48 nucleon system. Finally, we show how measuring parity violation at multiple momentum transfers can determine not just the neutron radius but the full radial structure of the neutron density in 48Ca. A neutron star is eighteen orders of magnitude larger than a nucleus (km vs fm) but both the star and the neutron rich nuclear skin are made of the same neutrons, with the same strong interactions, and the same equation of state. A large pressure pushes neutrons out against surface tension and gives a thick neutron skin. Therefore, PREX will constrain the equation of state of neutron rich matter and improve predictions for the structure of neutron stars. Supported in part by DOE Grants DE-FG02-87ER40365 (Indiana University) and DE-SC0008808 (NUCLEI SciDAC Collaboration).

  20. The master regulator of IncA/C plasmids is recognized by the Salmonella Genomic island SGI1 as a signal for excision and conjugal transfer

    PubMed Central

    Kiss, János; Papp, Péter Pál; Szabó, Mónika; Farkas, Tibor; Murányi, Gábor; Szakállas, Erik; Olasz, Ferenc

    2015-01-01

    The genomic island SGI1 and its variants, the important vehicles of multi-resistance in Salmonella strains, are integrative elements mobilized exclusively by the conjugative IncA/C plasmids. Integration and excision of the island are carried out by the SGI1-encoded site-specific recombinase Int and the recombination directionality factor Xis. Chromosomal integration ensures the stable maintenance and vertical transmission of SGI1, while excision is the initial step of horizontal transfer, followed by conjugation and integration into the recipient. We report here that SGI1 not only exploits the conjugal apparatus of the IncA/C plasmids but also utilizes the regulatory mechanisms of the conjugation system for the exact timing and activation of excision to ensure efficient horizontal transfer. This study demonstrates that the FlhDC-family activator AcaCD, which regulates the conjugation machinery of the IncA/C plasmids, serves as a signal of helper entry through binding to SGI1 xis promoter and activating SGI1 excision. Promoters of int and xis genes have been identified and the binding site of the activator has been located by footprinting and deletion analyses. We prove that expression of xis is activator-dependent while int is constitutively expressed, and this regulatory mechanism is presumably responsible for the efficient transfer and stable maintenance of SGI1. PMID:26209134

  1. Carbon nanotubes as a low background signal platform for a molecular aptamer beacon on the basis of long-range resonance energy transfer.

    PubMed

    Zhen, Shu Jun; Chen, Li Qiang; Xiao, Sai Jin; Li, Yuan Fang; Hu, Ping Ping; Zhan, Lei; Peng, Li; Song, Er Qun; Huang, Cheng Zhi

    2010-10-15

    Although holding the advantages of both an aptamer and a molecular beacon (MB), a molecular aptamer beacon (MAB) needs complicated and expensive modifications at both of its ends and usually has a high background signal because of the low energy transfer efficiency between the donor and the acceptor. To overcome these shortcomings, in this study, we develop a long-range resonance energy transfer (LrRET) system by separating the donor from the acceptor, wherein only one end of the MAB is fluorescently labeled and acts as the energy donor and multiwalled carbon nanotubes (MWCNTs) are introduced as the energy acceptor. To test the feasibility of the newly designed MAB system, adenosine triphosphate (ATP) has been employed as a proof-of-concept target. It is found that the fluorescence of the designed MAB is completely quenched by MWCNTs, supplying a very low background signal. Then the quenched fluorescence is recovered significantly with the addition of ATP, so that ATP can be detected in the range of 0.8-80 μM with a limit of detection of 0.5 μM (3σ). Compared with the conventional fluorescence resonance energy transfer, the efficiency of LrRET between the dye and MWCNTs is much higher. Since only one end of the MAB needs the modification, the present strategy is simple and cost-effective. Furthermore, the use of MWCNTs can greatly reduce the fluorescence background of the MAB and supply a high sensitivity, showing its generality for detection of a variety of targets.

  2. Transfer involving deformed nuclei

    SciTech Connect

    Rasmussen, J.O.; Guidry, M.W.; Canto, L.F.

    1985-03-01

    Results are reviewed of 1- and 2-neutron transfer reactions at near-barrier energies for deformed nuclei. Rotational angular momentum and excitation patterns are examined. A strong tendency to populating high spin states within a few MeV of the yrast line is noted, and it is interpreted as preferential transfer to rotation-aligned states. 16 refs., 12 figs.

  3. A large 2D PSD for thermal neutron detection

    NASA Astrophysics Data System (ADS)

    Knott, R. B.; Smith, G. C.; Watt, G.; Boldeman, J. W.

    1997-02-01

    A 2D PSD based on a MWPC has been constructed for a small angle neutron scattering instrument. The active area of the detector was 640 × 640 mm 2. To meet the specifications for neutron detection efficiency and spatial resolution, and to minimise parallax, the gas mixture was 190 kPa 3He plus 100 kPa CF 4, and the active volume had a thickness of 30 mm. The design maximum neutron count rate of the detector was 10 5 events per secod. The (calculated) neutron detection efficiency was 60% for 2 Å neutrons and the (measured) neutron energy resolution on the anode grid was typically 20% (fwhm). The location of a neutron detection event within the active area was determined using the wire-by-wire method: the spatial resolution (5 × 5 mm 2) was thereby defined by the wire geometry. A 16-channel charge-sensitive preamplifier/amplifier/comparator module has been developed with a channel sensitivity of 0.1 V/fC, noise line width of 0.4 fC (fwhm) and channel-to-channel cross-talk of less than 5%. The Proportional Counter Operating System (PCOS III) (LeCroy Corp, USA) was used for event encoding. The ECL signals produced by the 16 channel modules were latched in PCOS III by a trigger pulse from the anode and the fast encoders produce a position and width for each event. The information was transferred to a UNIX workstation for accumulation and online display.

  4. A large 2D PSD for thermal neutron detection

    SciTech Connect

    Knott, R.B.; Watt, G.; Boldeman, J.W.; Smith, G.C.

    1996-12-31

    A 2D PSD based on a MWPC has been constructed for a small angle neutron scattering instrument. The active area of the detector was 640 x 640 mm{sup 2}. To meet the specifications for neutron detection efficiency and spatial resolution, and to minimize parallax, the gas mixture was 190 kPa {sup 3}He plus 100 kPa CF{sub 4} and the active volume had a thickness of 30 mm. The design maximum neutron count-rate of the detector was 10{sup 5} events per second. The (calculated) neutron detection efficiency was 60% for 2{angstrom} neutrons and the (measured) neutron energy resolution on the anode grid was typically 20% (fwhm). The location of a neutron detection event within the active area was determined using the wire-by-wire method: the spatial resolution (5 x 5 mm{sup 2}) was thereby defined by the wire geometry. A 16 channel charge-sensitive preamplifier/amplifier/comparator module has been developed with a channel sensitivity of 0.1 V/fC, noise linewidth of 0.4 fC (fwhm) and channel-to-channel cross-talk of less than 5%. The Proportional Counter Operating System (PCOS III) (LeCroy Corp USA) was used for event encoding. The ECL signals produced by the 16 channel modules were latched in PCOS III by a trigger pulse from the anode and the fast encoders produce a position and width for each event. The information was transferred to a UNIX workstation for accumulation and online display.

  5. FAST NEUTRON SPECTROMETER USING SPACED SEMICONDUCTORS FOR MEASURING TOTAL ENERGY OF NEUTRONS CAPTURED

    DOEpatents

    Love, T.A.; Murray, R.B.

    1964-04-14

    A fast neutron spectrometer was designed, which utilizes a pair of opposed detectors having a layer of /sup 6/LiF between to produce alpha and T pair for each neutron captured to provide signals, which, when combined, constitute a measure of neutron energy. (AEC)

  6. High-resolution neutron and X-ray diffraction room-temperature studies of an H-FABP-oleic acid complex: study of the internal water cluster and ligand binding by a transferred multipolar electron-density distribution.

    PubMed

    Howard, E I; Guillot, B; Blakeley, M P; Haertlein, M; Moulin, M; Mitschler, A; Cousido-Siah, A; Fadel, F; Valsecchi, W M; Tomizaki, Takashi; Petrova, T; Claudot, J; Podjarny, A

    2016-03-01

    Crystal diffraction data of heart fatty acid binding protein (H-FABP) in complex with oleic acid were measured at room temperature with high-resolution X-ray and neutron protein crystallography (0.98 and 1.90 Å resolution, respectively). These data provided very detailed information about the cluster of water molecules and the bound oleic acid in the H-FABP large internal cavity. The jointly refined X-ray/neutron structure of H-FABP was complemented by a transferred multipolar electron-density distribution using the parameters of the ELMAMII library. The resulting electron density allowed a precise determination of the electrostatic potential in the fatty acid (FA) binding pocket. Bader's quantum theory of atoms in molecules was then used to study interactions involving the internal water molecules, the FA and the protein. This approach showed H⋯H contacts of the FA with highly conserved hydrophobic residues known to play a role in the stabilization of long-chain FAs in the binding cavity. The determination of water hydrogen (deuterium) positions allowed the analysis of the orientation and electrostatic properties of the water molecules in the very ordered cluster. As a result, a significant alignment of the permanent dipoles of the water molecules with the protein electrostatic field was observed. This can be related to the dielectric properties of hydration layers around proteins, where the shielding of electrostatic interactions depends directly on the rotational degrees of freedom of the water molecules in the interface. PMID:27006775

  7. High-resolution neutron and X-ray diffraction room-temperature studies of an H-FABP-oleic acid complex: study of the internal water cluster and ligand binding by a transferred multipolar electron-density distribution.

    PubMed

    Howard, E I; Guillot, B; Blakeley, M P; Haertlein, M; Moulin, M; Mitschler, A; Cousido-Siah, A; Fadel, F; Valsecchi, W M; Tomizaki, Takashi; Petrova, T; Claudot, J; Podjarny, A

    2016-03-01

    Crystal diffraction data of heart fatty acid binding protein (H-FABP) in complex with oleic acid were measured at room temperature with high-resolution X-ray and neutron protein crystallography (0.98 and 1.90 Å resolution, respectively). These data provided very detailed information about the cluster of water molecules and the bound oleic acid in the H-FABP large internal cavity. The jointly refined X-ray/neutron structure of H-FABP was complemented by a transferred multipolar electron-density distribution using the parameters of the ELMAMII library. The resulting electron density allowed a precise determination of the electrostatic potential in the fatty acid (FA) binding pocket. Bader's quantum theory of atoms in molecules was then used to study interactions involving the internal water molecules, the FA and the protein. This approach showed H⋯H contacts of the FA with highly conserved hydrophobic residues known to play a role in the stabilization of long-chain FAs in the binding cavity. The determination of water hydrogen (deuterium) positions allowed the analysis of the orientation and electrostatic properties of the water molecules in the very ordered cluster. As a result, a significant alignment of the permanent dipoles of the water molecules with the protein electrostatic field was observed. This can be related to the dielectric properties of hydration layers around proteins, where the shielding of electrostatic interactions depends directly on the rotational degrees of freedom of the water molecules in the interface.

  8. Separating climate-induced mass transfers and instrumental effects from tectonic signal in repeated absolute gravity measurements

    NASA Astrophysics Data System (ADS)

    Van Camp, M.; Viron, O.; Avouac, J. P.

    2016-05-01

    We estimate the signature of the climate-induced mass transfers in repeated absolute gravity measurements based on satellite gravimetric measurements from the Gravity Recovery and Climate Experiment (GRACE) mission. We show results at the globe scale and compare them with repeated absolute gravity (AG) time behavior in three zones where AG surveys have been published: Northwestern Europe, Canada, and Tibet. For 10 yearly campaigns, the uncertainties affecting the determination of a linear gravity rate of change range 3-4 nm/s2/a in most cases, in the absence of instrumental artifacts. The results are consistent with what is observed for long-term repeated campaigns. We also discuss the possible artifact that can result from using short AG survey to determine the tectonic effects in a zone of high hydrological variability. We call into question the tectonic interpretation of several gravity changes reported from stations in Tibet, in particular the variation observed prior to the 2015 Gorkha earthquake.

  9. Neutron spectrometer for improved SNM search.

    SciTech Connect

    Vance, Andrew L.; Aigeldinger, Georg

    2007-03-01

    With the exception of large laboratory devices with very low sensitivities, a neutron spectrometer have not been built for fission neutrons such as those emitted by special nuclear materials (SNM). The goal of this work was to use a technique known as Capture Gated Neutron Spectrometry to develop a solid-state device with this functionality. This required modifications to trans-stilbene, a known solid-state scintillator. To provide a neutron capture signal we added lithium to this material. This unique triggering signal allowed identification of neutrons that lose all of their energy in the detector, eliminating uncertainties that arise due to partial energy depositions. We successfully implemented a capture gated neutron spectrometer and were able to distinguish an SNM like fission spectrum from a spectrum stemming from a benign neutron source.

  10. Multipolarity analysis for {sup 14}C high-energy resonance populated by ({sup 18}O,{sup 16}O) two-neutron transfer reaction

    SciTech Connect

    Carbone, D. Cavallaro, M.; Bondì, M.; Agodi, C.; Cunsolo, A.; Cappuzzello, F.; Azaiez, F.; Franchoo, S.; Khan, E.; Bonaccorso, A.; Fortunato, L.; Foti, A.; Linares, R.; Lubian, J.; Scarpaci, J. A.; Vitturi, A.

    2015-10-15

    The {sup 12}C({sup 18}O,{sup 16}O){sup 14}C reaction at 84 MeV incident energy has been explored up to high excitation energy of the residual nucleus thanks to the use of the MAGNEX spectrometer to detect the ejectiles. In the region above the two-neutron separation energy, a resonance has been observed at 16.9 MeV. A multipolarity analysis of the cross section angular distribution indicates an L = 0 character for such a transition.

  11. Atmospheric neutrons

    NASA Technical Reports Server (NTRS)

    Preszler, A. M.; Moon, S.; White, R. S.

    1976-01-01

    Additional calibrations of the University of California double-scatter neutron detector and additional analysis corrections lead to slightly changed neutron fluxes. The theoretical angular distributions of Merker (1975) are in general agreement with the reported experimental fluxes but do not give the peaks for vertical upward and downward moving neutrons. The theoretical neutron escape current is in agreement with the experimental values from 10 to 100 MeV. The experimental fluxes obtained agree with those of Kanbach et al. (1974) in the overlap region from 70 to 100 MeV.

  12. Neutron coincidence detectors employing heterogeneous materials

    DOEpatents

    Czirr, J. Bartley; Jensen, Gary L.

    1993-07-27

    A neutron detector relies upon optical separation of different scintillators to measure the total energy and/or number of neutrons from a neutron source. In pulse mode embodiments of the invention, neutrons are detected in a first detector which surrounds the neutron source and in a second detector surrounding the first detector. An electronic circuit insures that only events are measured which correspond to neutrons first detected in the first detector followed by subsequent detection in the second detector. In spectrometer embodiments of the invention, neutrons are thermalized in the second detector which is formed by a scintillator-moderator and neutron energy is measured from the summed signals from the first and second detectors.

  13. The measurement of gamma ray induced heating in a mixed neutron and gamma ray environment

    SciTech Connect

    Chiu, H.K.

    1991-10-01

    The problem of measuring the gamma heating in a mixed DT neutron and gamma ray environment was explored. A new detector technique was developed to make this measurement. Gamma heating measurements were made in a low-Z assembly irradiated with 14-Mev neutrons and (n, n{prime}) gammas produced by a Texas Nuclear Model 9400 neutron generator. Heating measurements were made in the mid-line of the lattice using a proportional counter operating in the Continuously-varied Bias-voltage Acquisition mode. The neutron-induced signal was separated from the gamma-induced signal by exploiting the signal rise-time differences inherent to radiations of different linear energy transfer coefficient, which are observable in a proportional counter. The operating limits of this measurement technique were explored by varying the counter position in the low-Z lattice, hence changing the irradiation spectrum observed. The experiment was modelled numerically to help interpret the measured results. The transport of neutrons and gamma rays in the assembly was modelled using the one- dimensional radiation transport code ANISN/PC. The cross-section set used for these calculations was derived from the ENDF/B-V library using the code MC{sup 2}-2 for the case of DT neutrons slowing down in a low-Z material. The calculated neutron and gamma spectra in the slab and the relevant mass-stopping powers were used to construct weighting factors which relate the energy deposition in the counter fill-gas to that in the counter wall and in the surrounding material. The gamma energy deposition at various positions in the lattice is estimated by applying these weighting factors to the measured gamma energy deposition in the counter at those locations.

  14. Fast neutron dosemeter using pixelated detector Timepix.

    PubMed

    Bulanek, Boris; Ekendahl, Daniela; Prouza, Zdenek

    2014-10-01

    A Timepix detector covered with polyethylene convertors of different thicknesses is presented as a fast neutron real-time dosemeter. The application of different weighting factors in connection with the position of a signal in a Timepix detector enables one to obtain an energy-dependent signal equal to neutron dose equivalents. A simulation of a Timepix detector covered with polyethylene convertors using monoenergetic neutrons is presented. The experimental set-up of a dosemeter was also produced. The first results of detector response using different fast neutron sources are presented.

  15. Neutronic reactor

    DOEpatents

    Wende, Charles W. J.

    1976-08-17

    A safety rod for a nuclear reactor has an inner end portion having a gamma absorption coefficient and neutron capture cross section approximately equal to those of the adjacent shield, a central portion containing materials of high neutron capture cross section and an outer end portion having a gamma absorption coefficient at least equal to that of the adjacent shield.

  16. NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.; Zinn, W.H.; Anderson, H.L.

    1958-09-16

    Means are presenied for increasing the reproduction ratio of a gaphite- moderated neutronic reactor by diminishing the neutron loss due to absorption or capture by gaseous impurities within the reactor. This means comprised of a fluid-tight casing or envelope completely enclosing the reactor and provided with a valve through which the casing, and thereby the reactor, may be evacuated of atmospheric air.

  17. Superconducting thermal neutron detectors

    NASA Astrophysics Data System (ADS)

    Merlo, V.; Pietropaolo, A.; Celentano, G.; Cirillo, M.; Lucci, M.; Ottaviani, I.; Salvato, M.; Scherillo, A.; Schooneveld, E. M.; Vannozzi, A.

    2016-09-01

    A neutron detection concept is presented that is based on superconductive niobium nitride (NbN) strips coated by a boron (B) layer. The working principle is well described by a hot spot mechanism: upon the occurrence of the nuclear reactions n + 10B → α + 7Li + 2.8 MeV, the energy released by the secondary particles into the strip 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 below 11K and current-biased below the critical current IC, are driven into the normal state upon thermal neutron irradiation. Measurements on the counting rate of the device are presented and the basic physical features of the detector are discussed and compared to those of a borated Nb superconducting strip.

  18. Hybrid superconducting neutron detectors

    SciTech Connect

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

    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.

  19. Hybrid superconducting neutron detectors

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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, 10B + n → α + 7Li, 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 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 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.

  20. Charge transfer efficiency measurements at low signal levels on STIS/SOHO TK1024 CCD's. [Space Telescope Imaging Spectrograph / Solar Heliocentric Observatory

    NASA Technical Reports Server (NTRS)

    Orbock, J. D.; Murata-Seawalt, D.; Delamere, W. A.; Blouke, Morley M.

    1990-01-01

    Charge transfer efficiency (CTE) test methods are reviewed, and the results and conclusions of the tests are given. The test methods have been utilized to describe the CTE characteristics of the Tektronix 1024 by 1024 CCD to optimize low dark current, low readout noise, and high CTE at low signal levels. CTE modelling is described, and three test methods are set forth and compared. The Fe-55 X-ray response method utilizes the response of a CCD to X-ray photons from the radioactive source Fe-55. The extended pixel edge response method employs the measurement of the charge lost to successive pixels by a known initial signal as it is shifted through the array. The charge injection method consists of charge injection through the output amplifier reset transistor. These measurements were performed on several devices with known CTEs. The CTEs are found to be in agreement for the three methods, making application and test requirements the principal criteria for their use.

  1. Neutron tubes

    DOEpatents

    Leung, Ka-Ngo; Lou, Tak Pui; Reijonen, Jani

    2008-03-11

    A neutron tube or generator is based on a RF driven plasma ion source having a quartz or other chamber surrounded by an external RF antenna. A deuterium or mixed deuterium/tritium (or even just a tritium) plasma is generated in the chamber and D or D/T (or T) ions are extracted from the plasma. A neutron generating target is positioned so that the ion beam is incident thereon and loads the target. Incident ions cause D-D or D-T (or T-T) reactions which generate neutrons. Various embodiments differ primarily in size of the chamber and position and shape of the neutron generating target. Some neutron generators are small enough for implantation in the body. The target may be at the end of a catheter-like drift tube. The target may have a tapered or conical surface to increase target surface area.

  2. Neutron source

    DOEpatents

    Cason, J.L. Jr.; Shaw, C.B.

    1975-10-21

    A neutron source which is particularly useful for neutron radiography consists of a vessel containing a moderating media of relatively low moderating ratio, a flux trap including a moderating media of relatively high moderating ratio at the center of the vessel, a shell of depleted uranium dioxide surrounding the moderating media of relatively high moderating ratio, a plurality of guide tubes each containing a movable source of neutrons surrounding the flux trap, a neutron shield surrounding one part of each guide tube, and at least one collimator extending from the flux trap to the exterior of the neutron source. The shell of depleted uranium dioxide has a window provided with depleted uranium dioxide shutters for each collimator. Reflectors are provided above and below the flux trap and on the guide tubes away from the flux trap.

  3. Study of the (3He,t) Charge Transfer Reaction as a Surrogate for Neutron Energy Between 10 to 20 MeV

    NASA Astrophysics Data System (ADS)

    Basunia, M. S.; Clark, R. M.; Bernstein, L. A.; Lyles, B. F.; Burke, J. T.; Beausang, C. W.; Bleuel, D. L.; Darakchieva, B.; Dietrich, F. S.; Evtimova, M.; Fallon, P.; Gibelin, J.; Lesher, S. R.; McMahan, M. A.; Phair, L.; Rodriguez-Vieitez, E.; Wiedeking, M.

    2008-04-01

    We have indirectly determined the 237Np(n,f) cross section over an equivalent neutron energy range from 10 to 20 MeV using the surrogate reaction 238U(3He,tf). A self-supporting ˜761 μg/cm2 metallic 238U foil was bombarded with a 42 MeV 3He2+ beam from the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory (LBNL). Outgoing charged particles and fission fragments were identified using the Silicon Telescope Array for Reaction Studies (STARS) consisted of two 140 μm and one 1000 μm Micron S2 type silicon detectors. These results were compared with the 237Np(n,f) cross section data from the direct measurements, the Evaluated Nuclear Data File (ENDF/B-VII.0), and the Japanese Evaluated Nuclear Data Library (JENDL 3.3) and found to closely follow those datasets.

  4. Interactive signal transfer between host and pathogen during successful infection of barley leaves by Blumeria graminis and Bipolaris sorokiniana.

    PubMed

    Felle, Hubert H; Herrmann, Almut; Schäfer, Patrick; Hückelhoven, Ralph; Kogel, Karl-Heinz

    2008-01-01

    Using ion-selective microprobes, interactive signalling between barley and Blumeria graminis or Bipolaris sorokiniana has been investigated. The question was raised whether a biotrophically growing fungus manipulates the electrical driving forces (membrane potential, transmembrane pH), required for H+ cotransport of energy-rich compounds. Electrodes were positioned in the substomatal cavity of open stomata or on the leaf surface, and pH was measured continuously up to several days during fungal development. We demonstrate that surface and apoplastic fluids are electrically coupled and respond in a similar manner to stimuli. Apoplastic pH, monitored from the moment of inoculation with conidia, reveals several phases: 2-4h after inoculation of the barley leaf with either fungus, the host displays rapid transient responses after its first contact with the fungal cell wall; apoplastic pH and pCa increases, cytoplasmic pH and pCa decreases. About 1 day after inoculation, the apoplastic pH increases by up to 2 pH units, which is thought to reflect a resistance response against the intruder. Whereas barley leaf cells possess a membrane potential of -152+/-5 mV, hyphae of B. graminis yield -251+/-8 mV, indicative of a substantial driving force advantage for the fungus. Although the resting membrane potential of barley remains constant during the first days after inoculation, leaves infected with B. sorokiniana get confronted with an energy problem, indicated by a retarded repolarization following a "light-off" stimulus. Five days after inoculation, apoplastic pH has increased to 5.97+/-0.47 (n=11) and does no longer respond to "light-off" when measured within lesions. In contrast, it stays at near normal values outside the lesions and responds to "light-off". It is concluded that biotrophically growing fungi do not manipulate the cotransport driving forces since (i) any change in apoplastic pH would be experienced by both partners; (ii) the resting membrane potential is

  5. MONDE: MOmentum Neutron DEtector

    NASA Astrophysics Data System (ADS)

    Santa Rita, P.; Acosta, L.; Favela, F.; Huerta, A.; Ortiz, M. E.; Policroniades, R.; Chávez, E.

    2016-07-01

    MONDE is a large area neutron momentum detector, consisting of a 70x160x5 cm3 plastic scintillator slab surrounded by 16 photomultiplier tubes, standard NIM signal processing electronics and a CAMAC data acquisition system. In this work we present data from a characterization run using an external trigger. For that purpose, coincident gamma rays from a 60Co radioactive source were used together with a NaI external detector. First results with an "external" trigger are presented.

  6. NEUTRON SOURCE

    DOEpatents

    Bernander, N.K. et al.

    1960-10-18

    An apparatus is described for producing neutrons through target bombardment with deuterons. Deuterium gas is ionized by electron bombardment and the deuteron ions are accelerated through a magnetic field to collimate them into a continuous high intensity beam. The ion beam is directed against a deuteron pervious metal target of substantially the same nnaterial throughout to embed the deuterous therein and react them to produce neutrons. A large quantity of neutrons is produced in this manner due to the increased energy and quantity of ions bombarding the target.

  7. High-resolution neutron and X-ray diffraction room-temperature studies of an H-FABP–oleic acid complex: study of the internal water cluster and ligand binding by a transferred multipolar electron-density distribution

    PubMed Central

    Howard, E. I.; Guillot, B.; Blakeley, M. P.; Haertlein, M.; Moulin, M.; Mitschler, A.; Cousido-Siah, A.; Fadel, F.; Valsecchi, W. M.; Tomizaki, Takashi; Petrova, T.; Claudot, J.; Podjarny, A.

    2016-01-01

    Crystal diffraction data of heart fatty acid binding protein (H-FABP) in complex with oleic acid were measured at room temperature with high-resolution X-ray and neutron protein crystallography (0.98 and 1.90 Å resolution, respectively). These data provided very detailed information about the cluster of water molecules and the bound oleic acid in the H-FABP large internal cavity. The jointly refined X-ray/neutron structure of H-FABP was complemented by a transferred multipolar electron-density distribution using the parameters of the ELMAMII library. The resulting electron density allowed a precise determination of the electrostatic potential in the fatty acid (FA) binding pocket. Bader’s quantum theory of atoms in molecules was then used to study interactions involving the internal water molecules, the FA and the protein. This approach showed H⋯H contacts of the FA with highly conserved hydrophobic residues known to play a role in the stabilization of long-chain FAs in the binding cavity. The determination of water hydrogen (deuterium) positions allowed the analysis of the orientation and electrostatic properties of the water molecules in the very ordered cluster. As a result, a significant alignment of the permanent dipoles of the water molecules with the protein electrostatic field was observed. This can be related to the dielectric properties of hydration layers around proteins, where the shielding of electrostatic interactions depends directly on the rotational degrees of freedom of the water molecules in the interface. PMID:27006775

  8. Thermal neutron detection system

    DOEpatents

    Peurrung, Anthony J.; Stromswold, David C.

    2000-01-01

    According to the present invention, a system for measuring a thermal neutron emission from a neutron source, has a reflector/moderator proximate the neutron source that reflects and moderates neutrons from the neutron source. The reflector/moderator further directs thermal neutrons toward an unmoderated thermal neutron detector.

  9. 233U Assay A Neutron NDA System

    SciTech Connect

    Hensley, D.C.; Lucero, A.J.; Pierce, L.

    1998-11-17

    The assay of highly enriched {sup 233}U material presents some unique challenges. Techniques which apply to the assay of materials of Pu or enriched {sup 235}U do not convert easily over to the assay of {sup 233}U. A specialized neutron assay device is being fabricated to exploit the singles neutron signal, the weak correlated neutron signal, and an active correlated signal. These pieces of information when combined with {gamma} ray isotopics information should give a good overall determination of {sup 233}U material now stored in bldg. 3019 at the Oak Ridge National Laboratory.

  10. Modeling Binary Neutron Stars

    NASA Astrophysics Data System (ADS)

    Park, Conner; Read, Jocelyn; Flynn, Eric; Lockett-Ruiz, Veronica

    2016-03-01

    Gravitational waves, predicted by Einstein's Theory of Relativity, are a new frontier in astronomical observation we can use to observe phenomena in the universe. Laser Interferometer Gravitational wave Observatory (LIGO) is currently searching for gravitational wave signals, and requires accurate predictions in order to best extract astronomical signals from all other sources of fluctuations. The focus of my research is in increasing the accuracy of Post-Newtonian models of binary neutron star coalescence to match the computationally expensive Numerical models. Numerical simulations can take months to compute a couple of milliseconds of signal whereas the Post-Newtonian can generate similar signals in seconds. However the Post-Newtonian model is an approximation, e.g. the Taylor T4 Post-Newtonian model assumes that the two bodies in the binary neutron star system are point charges. To increase the effectiveness of the approximation, I added in tidal effects, resonance frequencies, and a windowing function. Using these observed effects from simulations significantly increases the Post-Newtonian model's similarity to the Numerical signal.

  11. NEUTRONIC REACTOR

    DOEpatents

    Wade, E.J.

    1958-09-16

    This patent relates to a reflector means for a neutronic reactor. A reflector comprised of a plurality of vertically movable beryllium control members is provided surrounding the sides of the reactor core. An absorber of fast neutrons comprised of natural uramum surrounds the reflector. An absorber of slow neutrons surrounds the absorber of fast neutrons and is formed of a plurality of beryllium blocks having natural uranium members distributcd therethrough. in addition, a movable body is positioned directly below the core and is comprised of a beryllium reflector and an absorbing member attached to the botiom thereof, the absorbing member containing a substance selected from the goup consisting of natural urantum and Th/sup 232/.

  12. NEUTRONIC REACTOR

    DOEpatents

    Fraas, A.P.; Mills, C.B.

    1961-11-21

    A neutronic reactor in which neutron moderation is achieved primarily in its reflector is described. The reactor structure consists of a cylindrical central "island" of moderator and a spherical moderating reflector spaced therefrom, thereby providing an annular space. An essentially unmoderated liquid fuel is continuously passed through the annular space and undergoes fission while contained therein. The reactor, because of its small size, is particularly adapted for propulsion uses, including the propulsion of aircraft. (AEC)

  13. NEUTRON SOURCES

    DOEpatents

    Richmond, J.L.; Wells, C.E.

    1963-01-15

    A neutron source is obtained without employing any separate beryllia receptacle, as was formerly required. The new method is safer and faster, and affords a source with both improved yield and symmetry of neutron emission. A Be container is used to hold and react with Pu. This container has a thin isolating layer that does not obstruct the desired Pu--Be reaction and obviates procedures previously employed to disassemble and remove a beryllia receptacle. (AEC)

  14. Calibration of the Al2O3:C optically stimulated luminescence (OSL) signal for linear energy transfer (LET) measurements in therapeutic proton beams.

    PubMed

    Granville, Dal A; Sahoo, Narayan; Sawakuchi, Gabriel O

    2014-08-01

    Optically stimulated luminescence (OSL) detectors (OSLDs) have shown potential for measurements of linear energy transfer (LET) in proton therapy beams. However, the technique lacks the efficiency needed for clinical implementation, and a faster, simpler approach to LET measurements is desirable. The goal of this work was to demonstrate and evaluate the potential of calibrating Al2O3:C OSLDs for LET measurements using new methods. We exposed batches of OSLDs to unmodulated proton beams of varying LET and calibrated three parameters of the resulting OSL signals as functions of fluence-averaged LET (ϕ-LET) and dose-averaged LET (D-LET). These three parameters included the OSL curve shape evaluated under continuous wave stimulation (CW-OSL), the OSL curve shape evaluated under pulsed stimulation (P-OSL), and the intensity ratio of the two main emission bands in the Al2O3:C OSL emission spectrum (ultraviolet [UV]/blue ratio). To test the calibration, we then irradiated new batches of OSLDs in modulated proton beams of varying LET, and used the OSL signal parameters to calculate ϕ-LET and D-LET under these new test conditions. Using the P-OSL curve shape, D-LET was measured within 5.7% of the expected value. We conclude that from a single 10 s readout (following initial calibration), both the absorbed dose and LET in proton therapy beams can be measured using OSLDs. This has potential future applications in the quality assurance of proton therapy treatment plans, particularly for those that may account for LET or relative biological effectiveness in their optimization. The methods demonstrated in this work may also be applicable to other particle therapy beams, including carbon ion beams. PMID:25029434

  15. Calibration of the Al2O3:C optically stimulated luminescence (OSL) signal for linear energy transfer (LET) measurements in therapeutic proton beams

    NASA Astrophysics Data System (ADS)

    Granville, Dal A.; Sahoo, Narayan; Sawakuchi, Gabriel O.

    2014-08-01

    Optically stimulated luminescence (OSL) detectors (OSLDs) have shown potential for measurements of linear energy transfer (LET) in proton therapy beams. However, the technique lacks the efficiency needed for clinical implementation, and a faster, simpler approach to LET measurements is desirable. The goal of this work was to demonstrate and evaluate the potential of calibrating Al2O3:C OSLDs for LET measurements using new methods. We exposed batches of OSLDs to unmodulated proton beams of varying LET and calibrated three parameters of the resulting OSL signals as functions of fluence-averaged LET (ϕ-LET) and dose-averaged LET (D-LET). These three parameters included the OSL curve shape evaluated under continuous wave stimulation (CW-OSL), the OSL curve shape evaluated under pulsed stimulation (P-OSL), and the intensity ratio of the two main emission bands in the Al2O3:C OSL emission spectrum (ultraviolet [UV]/blue ratio). To test the calibration, we then irradiated new batches of OSLDs in modulated proton beams of varying LET, and used the OSL signal parameters to calculate ϕ-LET and D-LET under these new test conditions. Using the P-OSL curve shape, D-LET was measured within 5.7% of the expected value. We conclude that from a single 10 s readout (following initial calibration), both the absorbed dose and LET in proton therapy beams can be measured using OSLDs. This has potential future applications in the quality assurance of proton therapy treatment plans, particularly for those that may account for LET or relative biological effectiveness in their optimization. The methods demonstrated in this work may also be applicable to other particle therapy beams, including carbon ion beams.

  16. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.

    1958-04-22

    A nuclear reactor for isotope production is described. This reactor is designed to provide a maximum thermal neutron flux in a region adjacent to the periphery of the reactor rather than in the center of the reactor. The core of the reactor is generally centrally located with respect tn a surrounding first reflector, constructed of beryllium. The beryllium reflector is surrounded by a second reflector, constructed of graphite, which, in tune, is surrounded by a conventional thermal shield. Water is circulated through the core and the reflector and functions both as a moderator and a coolant. In order to produce a greatsr maximum thermal neutron flux adjacent to the periphery of the reactor rather than in the core, the reactor is designed so tbat the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the materials in the reflector is approximately twice the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the material of the core of the reactor.

  17. FOREWORD: Neutron metrology Neutron metrology

    NASA Astrophysics Data System (ADS)

    Thomas, David J.; Nolte, Ralf; Gressier, Vincent

    2011-12-01

    The International Committee for Weights and Measures (CIPM) has consultative committees covering various areas of metrology. The Consultative Committee for Ionizing Radiation (CCRI) differs from the others in having three sections: Section (I) deals with radiation dosimetry, Section (II) with radionuclide metrology and Section (III) with neutron metrology. In 2003 a proposal was made to publish special issues of Metrologia covering the work of the three Sections. Section (II) was the first to complete their task, and their special issue was published in 2007, volume 44(4). This was followed in 2009 by the special issue on radiation dosimetry, volume 46(2). The present issue, volume 48(6), completes the trilogy and attempts to explain neutron metrology, the youngest of the three disciplines, the neutron only having been discovered in 1932, to a wider audience and to highlight the relevance and importance of this field. When originally approached with the idea of this special issue, Section (III) immediately saw the value of a publication specifically on neutron metrology. It is a topic area where papers tend to be scattered throughout the literature in journals covering, for example, nuclear instrumentation, radiation protection or radiation measurements in general. Review articles tend to be few. People new to the field often ask for an introduction to the various topics. There are some excellent older textbooks, but these are now becoming obsolete. More experienced workers in specific areas of neutron metrology can find it difficult to know the latest position in related areas. The papers in this issue attempt, without presenting a purely historical outline, to describe the field in a sufficiently logical way to provide the novice with a clear introduction, while being sufficiently up-to-date to provide the more experienced reader with the latest scientific developments in the different topic areas. Neutron radiation fields obviously occur throughout the nuclear

  18. FOREWORD: Neutron metrology Neutron metrology

    NASA Astrophysics Data System (ADS)

    Thomas, David J.; Nolte, Ralf; Gressier, Vincent

    2011-12-01

    The International Committee for Weights and Measures (CIPM) has consultative committees covering various areas of metrology. The Consultative Committee for Ionizing Radiation (CCRI) differs from the others in having three sections: Section (I) deals with radiation dosimetry, Section (II) with radionuclide metrology and Section (III) with neutron metrology. In 2003 a proposal was made to publish special issues of Metrologia covering the work of the three Sections. Section (II) was the first to complete their task, and their special issue was published in 2007, volume 44(4). This was followed in 2009 by the special issue on radiation dosimetry, volume 46(2). The present issue, volume 48(6), completes the trilogy and attempts to explain neutron metrology, the youngest of the three disciplines, the neutron only having been discovered in 1932, to a wider audience and to highlight the relevance and importance of this field. When originally approached with the idea of this special issue, Section (III) immediately saw the value of a publication specifically on neutron metrology. It is a topic area where papers tend to be scattered throughout the literature in journals covering, for example, nuclear instrumentation, radiation protection or radiation measurements in general. Review articles tend to be few. People new to the field often ask for an introduction to the various topics. There are some excellent older textbooks, but these are now becoming obsolete. More experienced workers in specific areas of neutron metrology can find it difficult to know the latest position in related areas. The papers in this issue attempt, without presenting a purely historical outline, to describe the field in a sufficiently logical way to provide the novice with a clear introduction, while being sufficiently up-to-date to provide the more experienced reader with the latest scientific developments in the different topic areas. Neutron radiation fields obviously occur throughout the nuclear

  19. Large momentum transfer neutron pickup with the (. pi. /sup +/,p) and (p,d) reactions. [90 and 180 MeV, 800 MeV

    SciTech Connect

    Smith, G.R.

    1980-01-01

    The (p,d) reaction was studied for the first time at 800 MeV on seven targets ranging from /sup 7/Li to /sup 40/Ca. The experimental resolution (approx. 400 keV) attained was sufficient to observe many discrete levels in each of the residual nuclei. A modified version of the one-nucleon model successfully describes the magnitude and angular dependence of almost all of the transitions observed. A specific counter example to the two-nucleon model of the reaction mechanism is suggested. The calculations are also sensitive to the neutron single-particle wave function, in accordance with the expectation that the high-momentum components of this wave function are probed at higher bombarding energies. States that have never been seen before were strongly populated in the high excitation region (up to 25 MeV) of some of the residual nuclei. The relative intensities of the other levels observed suggest that coupled-channels mechanisms play an important role for some of these states. Explicit calculations were performed to confirm this for several examples. The first high-resolution measurements of the (..pi../sup +/,p) reaction were also performed on /sup 6/Li, /sup 7/Li, /sup 12/C, and /sup 13/C at pion bombarding energies on and off the pion-nucleon resonance. Calculations employing a one-nucleon model of the reaction mechanism similar to the model successfully used for the (p,d) reaction are unable to account for transitions in the (..pi../sup +/,p) reaction. It is, however, unclear whether this failure is due to a fundamental inadequacy of the model or improper treatment of details in the calculations. A striking similarity was observed in the spectra of the (..pi../sup +/,p) and 800-MeV (p,d) reactions on the same target; this result implies a similar mechanism for the two reactions. 120 references, 97 figures, 15 tables.

  20. Unifying mechanism for bacterial cell signalers (4,5-dihydroxy-2,3-pentanedione, lactones and oligopeptides): electron transfer and reactive oxygen species. Practical medical features.

    PubMed

    Kovacic, Peter

    2007-01-01

    Cell signaling has attracted much attention involving higher organisms, and more recently is of considerable interest concerning involvement in the bacterial realm. Many aspects can apply, including quorum sensing. Of the participating molecules, designated autoinducers, 4,5-dihydroxy-2,3-pentanedione (DPD) is one of the most important. It is in equilibrium with a furanone and a furanosyl-borate diester (AI-2). A prior hypothesis for cell signaling in higher organisms invoked a key role for electron transfer (ET) and reactive oxygen species (ROS), as well as conduits, relays and electrical effects. The principal ET functionalities are quinones, metal complexes, ArNO(2), and iminium species. A lesser known type is the alpha-dicarbonyl class. Diacetyl, a member, as well as its imine derivatives, can serve as a model for DPD, since the parent possesses a reduction potential amenable to ET in the biological domain. Hence, it is conceivable that DPD and its imine derivatives may be involved in ET-ROS processes. Presence of hydroxy groups should facilitate ET by DPD vs. diacetyl. Extensive prior literature supports participation of ET functionalities in action of therapeutic drugs, toxins and various illnesses. This biochemical behavior also applies to the alpha-dicarbonyl parent models. A second important bacterial autoinducer is the lactone category. Although ET functionality is lacking, the presence of the 1,3-dicarbonyl structure can provide a site for avid chelation with redox metal, e.g., iron or copper, followed by ET-ROS. Findings with added iron furnish support for the proposal. Oligopeptides comprise the third principal type of bacterial signaling agent. A prior review incorporates these within the theoretical framework based on ET by redox amino acids and redox enzymes. In recent years there has been a rapid increase in resistance to antibiotics by pathogenic bacteria. Infectious diseases are the leading cause of death worldwide and the third leading cause in

  1. Modulating the Neutron Flux from a Mirror Neutron Source

    SciTech Connect

    Ryutov, D D

    2011-09-01

    A 14-MeV neutron source based on a Gas-Dynamic Trap will provide a high flux of 14 MeV neutrons for fusion materials and sub-component testing. In addition to its main goal, the source has potential applications in condensed matter physics and biophysics. In this report, the author considers adding one more capability to the GDT-based neutron source, the modulation of the neutron flux with a desired frequency. The modulation may be an enabling tool for the assessment of the role of non-steady-state effects in fusion devices as well as for high-precision, low-signal basic science experiments favoring the use of the synchronous detection technique. A conclusion is drawn that modulation frequency of up to 1 kHz and modulation amplitude of a few percent is achievable. Limitations on the amplitude of modulations at higher frequencies are discussed.

  2. A phosphatidylinositol transfer protein integrates phosphoinositide signaling with lipid droplet metabolism to regulate a developmental program of nutrient stress-induced membrane biogenesis.

    PubMed

    Ren, Jihui; Pei-Chen Lin, Coney; Pathak, Manish C; Temple, Brenda R S; Nile, Aaron H; Mousley, Carl J; Duncan, Mara C; Eckert, Debra M; Leiker, Thomas J; Ivanova, Pavlina T; Myers, David S; Murphy, Robert C; Brown, H Alex; Verdaasdonk, Jolien; Bloom, Kerry S; Ortlund, Eric A; Neiman, Aaron M; Bankaitis, Vytas A

    2014-03-01

    Lipid droplet (LD) utilization is an important cellular activity that regulates energy balance and release of lipid second messengers. Because fatty acids exhibit both beneficial and toxic properties, their release from LDs must be controlled. Here we demonstrate that yeast Sfh3, an unusual Sec14-like phosphatidylinositol transfer protein, is an LD-associated protein that inhibits lipid mobilization from these particles. We further document a complex biochemical diversification of LDs during sporulation in which Sfh3 and select other LD proteins redistribute into discrete LD subpopulations. The data show that Sfh3 modulates the efficiency with which a neutral lipid hydrolase-rich LD subclass is consumed during biogenesis of specialized membrane envelopes that package replicated haploid meiotic genomes. These results present novel insights into the interface between phosphoinositide signaling and developmental regulation of LD metabolism and unveil meiosis-specific aspects of Sfh3 (and phosphoinositide) biology that are invisible to contemporary haploid-centric cell biological, proteomic, and functional genomics approaches. PMID:24403601

  3. A phosphatidylinositol transfer protein integrates phosphoinositide signaling with lipid droplet metabolism to regulate a developmental program of nutrient stress-induced membrane biogenesis

    SciTech Connect

    Ren, Jihui; Lin, Coney Pei-Chen; Pathak, Manish C.; Temple, Brenda R.S.; Nile, Aaron H.; Mousley, Carl J.; Duncan, Mara C.; Eckert, Debra M.; Leiker, Thomas J.; Ivanova, Pavlina T.; Myers, David S.; Murphy, Robert C.; Brown, H. Alex; Verdaasdonk, Jolien; Bloom, Kerry S.; Ortlund, Eric A.; Neiman, Aaron M.; Bankaitis, Vytas A.

    2014-07-11

    Lipid droplet (LD) utilization is an important cellular activity that regulates energy balance and release of lipid second messengers. Because fatty acids exhibit both beneficial and toxic properties, their release from LDs must be controlled. Here we demonstrate that yeast Sfh3, an unusual Sec14-like phosphatidylinositol transfer protein, is an LD-associated protein that inhibits lipid mobilization from these particles. We further document a complex biochemical diversification of LDs during sporulation in which Sfh3 and select other LD proteins redistribute into discrete LD subpopulations. The data show that Sfh3 modulates the efficiency with which a neutral lipid hydrolase-rich LD subclass is consumed during biogenesis of specialized membrane envelopes that package replicated haploid meiotic genomes. These results present novel insights into the interface between phosphoinositide signaling and developmental regulation of LD metabolism and unveil meiosis-specific aspects of Sfh3 (and phosphoinositide) biology that are invisible to contemporary haploid-centric cell biological, proteomic, and functional genomics approaches.

  4. Protein electron transfer (mechanism and reproductive toxicity): iminium, hydrogen bonding, homoconjugation, amino acid side chains (redox and charged), and cell signaling.

    PubMed

    Kovacic, Peter

    2007-03-01

    This contribution presents novel biochemical perspectives of protein electron transfer (ET) with focus on the iminium nature of the peptide link, along with relationships to reproductive toxicity. The favorable influence of hydrogen bonding on protein ET has been widely documented. Hydrogen bonding of the zwitterionic peptide enhances iminium character. A wide array of such bonding agents is available in vivo, with many reports on the peptide link itself. ET proceeds along the backbone, due in part, to homoconjugation. Redox amino acids (AAs), mainly tyrosine (Tyr), tryptophan (Typ), histidine (His), cysteine (Cys), disulfide, and methionine (Met), are involved in the competing processes for radical formation: direct hydrogen atom abstraction versus electron and proton loss. It appears that the radical or radical cation generated during the redox process is capable of interacting with n-electrons of the backbone. Beneficial effects of cationic AAs impact the conduction process. A relationship apparently exists involving cell signaling, protein conduction, and radicals or electrons. In addition, the link between protein ET and reproductive toxicity is examined. A key element is the role of reactive oxygen species (ROS) generated by protein ET. There is extensive evidence for involvement of ROS in generation of birth defects. The radical species arise in protein mainly by ET transformations by enzymes, as illustrated in the case of alcoholism.

  5. {gamma}-ray spectroscopy of the neutron-rich nuclei {sup 89}Rb, {sup 92}Y, and {sup 93}Y with multinucleon transfer reactions

    SciTech Connect

    Bucurescu, D.; Ionescu-Bujor, M.; Iordachescu, A.; Mihai, C.; Suliman, G.; Rusu, C.; Marginean, N.; Ur, C. A.; Marginean, R.; De Angelis, G.; Corradi, L.; Vedova, F. Della; Fioretto, E.; Gadea, A.; Guiot, B.; Napoli, D.; Stefanini, A. M.; Valiente-Dobon, J. J.; Bazzacco, D.; Beghini, S.

    2007-12-15

    The positive-parity yrast states in the {sup 89}Rb, {sup 92}Y, and {sup 93}Y nuclei were studied using {gamma}-ray spectroscopy with heavy-ion induced reactions. In the multinucleon transfer reactions {sup 208}Pb+{sup 90}Zr (590 MeV) and {sup 238}U+{sup 82}Se (505 MeV), several {gamma}-ray transitions were identified in these nuclei by means of coincidences between recoiling ions identified with the PRISMA spectrometer and {gamma} rays detected with the CLARA {gamma}-ray array in thin target experiments. Level schemes were subsequently determined from triple-{gamma} coincidences recorded with the GASP array in a thick target experiment, in the reactions produced by a 470 MeV {sup 82}Se beam with a {sup 192}Os target. The observed level schemes are compared to shell-model calculations.

  6. Enhanced reaction rates in NDP analysis with neutron scattering

    SciTech Connect

    Downing, R. Gregory

    2014-04-15

    Neutron depth profiling (NDP) makes accessible quantitative information on a few isotopic concentration profiles ranging from the surface into the sample a few micrometers. Because the candidate analytes for NDP are few, there is little interference encountered. Furthermore, neutrons have no charge so mixed chemical states in the sample are of no direct concern. There are a few nuclides that exhibit large probabilities for neutron scattering. The effect of neutron scattering on NDP measurements has not previously been evaluated as a basis for either enhancing the reaction rates or as a source of measurement error. Hydrogen is a common element exhibiting large neutron scattering probability found in or around sample volumes being analyzed by NDP. A systematic study was conducted to determine the degree of signal change when neutron scattering occurs during analysis. The relative signal perturbation was evaluated for materials of varied neutron scattering probability, concentration, total mass, and geometry. Signal enhancements up to 50% are observed when the hydrogen density is high and in close proximity to the region of analysis with neutron beams of sub thermal energies. Greater signal enhancements for the same neutron number density are reported for thermal neutron beams. Even adhesive tape used to position the sample produces a measureable signal enhancement. Because of the shallow volume, negligible distortion of the NDP measured profile shape is encountered from neutron scattering.

  7. Neutron therapy of cancer

    NASA Technical Reports Server (NTRS)

    Frigerio, N. A.; Nellans, H. N.; Shaw, M. J.

    1969-01-01

    Reports relate applications of neutrons to the problem of cancer therapy. The biochemical and biophysical aspects of fast-neutron therapy, neutron-capture and neutron-conversion therapy with intermediate-range neutrons are presented. Also included is a computer program for neutron-gamma radiobiology.

  8. NEUTRONIC REACTOR

    DOEpatents

    Hurwitz, H. Jr.; Brooks, H.; Mannal, C.; Payne, J.H.; Luebke, E.A.

    1959-03-24

    A reactor of the heterogeneous, liquid cooled type is described. This reactor is comprised of a central region of a plurality of vertically disposed elongated tubes surrounded by a region of moderator material. The central region is comprised of a central core surrounded by a reflector region which is surrounded by a fast neutron absorber region, which in turn is surrounded by a slow neutron absorber region. Liquid sodium is used as the primary coolant and circulates through the core which contains the fuel elements. Control of the reactor is accomplished by varying the ability of the reflector region to reflect neutrons back into the core of the reactor. For this purpose the reflector is comprised of moderator and control elements having varying effects on reactivity, the control elements being arranged and actuated by groups to give regulation, shim, and safety control.

  9. NEUTRONIC REACTOR

    DOEpatents

    Fermi, E.; Szilard, L.

    1957-09-24

    Reactors of the type employing plates of natural uranium in a moderator are discussed wherein the plates are um-formly disposed in parallel relationship to each other thereby separating the moderator material into distinct and individual layers. Each plate has an uninterrupted sunface area substantially equal to the cross-sectional area of the active portion of the reactor, the particular size of the plates and the volume ratio of moderator to uranium required to sustain a chain reaction being determinable from the known purity of these materials and other characteristics such as the predictable neutron losses due to the formation of radioactive elements of extremely high neutron capture cross section.

  10. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.; Weinberg, A.W.; Young, G.J.

    1958-04-15

    A nuclear reactor which uses uranium in the form of elongated tubes as fuel elements and liquid as a coolant is described. Elongated tubular uranium bodies are vertically disposed in an efficient neutron slowing agent, such as graphite, for example, to form a lattice structure which is disposed between upper and lower coolant tanks. Fluid coolant tubes extend through the uranium bodies and communicate with the upper and lower tanks and serve to convey the coolant through the uranium body. The reactor is also provided with means for circulating the cooling fluid through the coolant tanks and coolant tubes, suitable neutron and gnmma ray shields, and control means.

  11. Spectrum tailoring of the neutron energy spectrum in the context of delayed neutron detection

    SciTech Connect

    Koehler, William E; Tobin, Steve J; Sandoval, Nathan P; Fensin, Mike L

    2010-01-01

    For the purpose of measuring plutonium mass in spent fuel, a delayed neutron instrument is of particular interest since, if properly designed, the delayed neutron signal from {sup 235}U is significantly stronger than the signature from {sup 239}Pu or {sup 241}Pu. A key factor in properly designing a delayed neutron instrument is to minimize the fission of {sup 238}U. This minimization is achieved by keeping the interrogating neutron spectrum below {approx} 1 MeV. In the context of spent fuel measurements it is desirable to use a 14 MeV (deuterium and tritium) neutron generator for economic reasons. Spectrum tailoring is the term used to describe the inclusion of material between the 14 MeV neutrons and the interrogated object that lower the neutron energy through nuclear reactions and moderation. This report quantifies the utility of different material combination for spectrum tailoring.

  12. Neutronic reactor

    DOEpatents

    Carleton, John T.

    1977-01-25

    A graphite-moderated nuclear reactor includes channels between blocks of graphite and also includes spacer blocks between adjacent channeled blocks with an axis of extension normal to that of the axis of elongation of the channeled blocks to minimize changes in the physical properties of the graphite as a result of prolonged neutron bombardment.

  13. NEUTRONIC REACTORS

    DOEpatents

    Anderson, H.L.

    1958-10-01

    The design of control rods for nuclear reactors are described. In this design the control rod consists essentially of an elongated member constructed in part of a neutron absorbing material and having tube means extending therethrough for conducting a liquid to cool the rod when in use.

  14. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.

    1960-09-27

    A unit assembly is described for a neutronic reactor comprising a tube and plurality of spaced parallel sandwiches in the tube extending lengthwise thereof, each sandwich including a middle plate having a central opening for plutonium and other openings for fertile material at opposite ends of the plate.

  15. NEUTRONIC REACTOR CORE

    DOEpatents

    Thomson, W.B.; Corbin, A. Jr.

    1961-07-18

    An improved core for a gas-cooled power reactor which admits gas coolant at high temperatures while affording strong integral supporting structure and efficient moderation of neutrons is described. The multiplicities of fuel elements constituting the critical amassment of fissionable material are supported and confined by a matrix of metallic structure which is interspersed therebetween. Thermal insulation is interposed between substantially all of the metallic matrix and the fuel elements; the insulation then defines the principal conduit system for conducting the coolant gas in heat-transfer relationship with the fuel elements. The metallic matrix itseif comprises a system of ducts through which an externally-cooled hydrogeneous liquid, such as water, is circulated to serve as the principal neutron moderant for the core and conjointly as the principal coolant for the insulated metallic structure. In this way, use of substantially neutron transparent metals, such as aluminum, becomes possible for the supporting structure, despite the high temperatures of the proximate gas. The Aircraft Nuclear Propulsion program's "R-1" reactor design is a preferred embodiment.

  16. Methods for absorbing neutrons

    DOEpatents

    Guillen, Donna P.; Longhurst, Glen R.; Porter, Douglas L.; Parry, James R.

    2012-07-24

    A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

  17. Method and apparatus for determination of temperature, neutron absorption cross section and neutron moderating power

    DOEpatents

    Vagelatos, Nicholas; Steinman, Donald K.; John, Joseph; Young, Jack C.

    1981-01-01

    A nuclear method and apparatus determines the temperature of a medium by injecting fast neutrons into the medium and detecting returning slow neutrons in three first energy ranges by producing three respective detection signals. The detection signals are combined to produce three derived indicia each systematically related to the population of slow neutrons returning from the medium in a respective one of three second energy ranges, specifically exclusively epithermal neutrons, exclusively substantially all thermal neutrons and exclusively a portion of the thermal neutron spectrum. The derived indicia are compared with calibration indicia similarly systematically related to the population of slow neutrons in the same three second energy ranges returning from similarly irradiated calibration media for which the relationships temperature, neutron absorption cross section and neutron moderating power to such calibration indicia are known. The comparison indicates the temperature at which the calibration indicia correspond to the derived indicia and consequently the temperature of the medium. The neutron absorption cross section and moderating power of the medium can be identified at the same time.

  18. Recent Advances in Neutron Physics

    ERIC Educational Resources Information Center

    Feshbach, Herman; Sheldon, Eric

    1977-01-01

    Discusses new studies in neutron physics within the last decade, such as ultracold neutrons, neutron bottles, resonance behavior, subthreshold fission, doubly radiative capture, and neutron stars. (MLH)

  19. Neutron reflecting supermirror structure

    DOEpatents

    Wood, J.L.

    1992-12-01

    An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. 2 figs.

  20. Neutron reflecting supermirror structure

    DOEpatents

    Wood, James L.

    1992-01-01

    An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources.

  1. A neutron multiplicity analysis method for uranium samples with liquid scintillators

    NASA Astrophysics Data System (ADS)

    Zhou, Hao; Lin, Hongtao; Liu, Guorong; Li, Jinghuai; Liang, Qinglei; Zhao, Yonggang

    2015-10-01

    A new neutron multiplicity analysis method for uranium samples with liquid scintillators is introduced. An active well-type fast neutron multiplicity counter has been built, which consists of four BC501A liquid scintillators, a n/γdiscrimination module MPD-4, a multi-stop time to digital convertor MCS6A, and two Am-Li sources. A mathematical model is built to symbolize the detection processes of fission neutrons. Based on this model, equations in the form of R=F*P*Q*T could be achieved, where F indicates the induced fission rate by interrogation sources, P indicates the transfer matrix determined by multiplication process, Q indicates the transfer matrix determined by detection efficiency, T indicates the transfer matrix determined by signal recording process and crosstalk in the counter. Unknown parameters about the item are determined by the solutions of the equations. A 252Cf source and some low enriched uranium items have been measured. The feasibility of the method is proven by its application to the data analysis of the experiments.

  2. Neuronal RARβ Signaling Modulates PTEN Activity Directly in Neurons and via Exosome Transfer in Astrocytes to Prevent Glial Scar Formation and Induce Spinal Cord Regeneration

    PubMed Central

    Goncalves, Maria B.; Malmqvist, Tony; Clarke, Earl; Hubens, Chantal J.; Grist, John; Hobbs, Carl; Trigo, Diogo; Risling, Mårten; Angeria, Maria; Damberg, Peter; Carlstedt, Thomas P.

    2015-01-01

    Failure of axonal regeneration in the central nervous system (CNS) is mainly attributed to a lack of intrinsic neuronal growth programs and an inhibitory environment from a glial scar. Phosphatase and tensin homolog (PTEN) is a major negative regulator of neuronal regeneration and, as such, inhibiting its activity has been considered a therapeutic target for spinal cord (SC) injuries (SCIs). Using a novel model of rat cervical avulsion, we show that treatment with a retinoic acid receptor β (RARβ) agonist results in locomotor and sensory recovery. Axonal regeneration from the severed roots into the SC could be seen by biotinylated dextran amine labeling. Light micrographs of the dorsal root entry zone show the peripheral nervous system (PNS)–CNS transition of regrown axons. RARβ agonist treatment also resulted in the absence of scar formation. Mechanism studies revealed that, in RARβ-agonist-treated neurons, PTEN activity is decreased by cytoplasmic phosphorylation and increased secretion in exosomes. These are taken up by astrocytes, resulting in hampered proliferation and causing them to arrange in a normal-appearing scaffold around the regenerating axons. Attribution of the glial modulation to neuronal PTEN in exosomes was demonstrated by the use of an exosome inhibitor in vivo and PTEN siRNA in vitro assays. The dual effect of RARβ signaling, both neuronal and neuronal–glial, results in axonal regeneration into the SC after dorsal root neurotmesis. Targeting this pathway may open new avenues for the treatment of SCIs. SIGNIFICANCE STATEMENT Spinal cord injuries (SCIs) often result in permanent damage in the adult due to the very limited capacity of axonal regeneration. Intrinsic neuronal programs and the formation of a glial scar are the main obstacles. Here, we identify a single target, neuronal retinoic acid receptor β (RARβ), which modulates these two aspects of the postinjury physiological response. Activation of RARβ in the neuron inactivates

  3. CONTROL SYSTEM FOR NEUTRONIC REACTORS

    DOEpatents

    Crever, F.E.

    1962-05-01

    BS>A slow-acting shim rod for control of major variations in reactor neutron flux and a fast-acting control rod to correct minor flux variations are employed to provide a sensitive, accurate control system. The fast-acting rod is responsive to an error signal which is produced by changes in the neutron flux from a predetermined optimum level. When the fast rod is thus actuated in a given direction, means is provided to actuate the slow-moving rod in that direction to return the fast rod to a position near the midpoint of its control range. (AEC)

  4. NEUTRONIC REACTORS

    DOEpatents

    Vernon, H.C.

    1959-01-13

    A neutronic reactor of the heterogeneous, fluid cooled tvpe is described. The reactor is comprised of a pressure vessel containing the moderator and a plurality of vertically disposed channels extending in spaced relationship through the moderator. Fissionable fuel material is placed within the channels in spaced relationship thereto to permit circulation of the coolant fluid. Separate means are provided for cooling the moderator and for circulating a fluid coolant thru the channel elements to cool the fuel material.

  5. Method and apparatus for detecting neutrons

    DOEpatents

    Perkins, Richard W.; Reeder, Paul L.; Wogman, Ned A.; Warner, Ray A.; Brite, Daniel W.; Richey, Wayne C.; Goldman, Don S.

    1997-01-01

    The instant invention is a method for making and using an apparatus for detecting neutrons. Scintillating optical fibers are fabricated by melting SiO.sub.2 with a thermal neutron capturing substance and a scintillating material in a reducing atmosphere. The melt is then drawn into fibers in an anoxic atmosphere. The fibers may then be coated and used directly in a neutron detection apparatus, or assembled into a geometrical array in a second, hydrogen-rich, scintillating material such as a polymer. Photons generated by interaction with thermal neutrons are trapped within the coated fibers and are directed to photoelectric converters. A measurable electronic signal is generated for each thermal neutron interaction within the fiber. These electronic signals are then manipulated, stored, and interpreted by normal methods to infer the quality and quantity of incident radiation. When the fibers are arranged in an array within a second scintillating material, photons generated by kinetic neutrons interacting with the second scintillating material and photons generated by thermal neutron capture within the fiber can both be directed to photoelectric converters. These electronic signals are then manipulated, stored, and interpreted by normal methods to infer the quality and quantity of incident radiation.

  6. Method and apparatus for detecting neutrons

    DOEpatents

    Perkins, R.W.; Reeder, P.L.; Wogman, N.A.; Warner, R.A.; Brite, D.W.; Richey, W.C.; Goldman, D.S.

    1997-10-21

    The instant invention is a method for making and using an apparatus for detecting neutrons. Scintillating optical fibers are fabricated by melting SiO{sub 2} with a thermal neutron capturing substance and a scintillating material in a reducing atmosphere. The melt is then drawn into fibers in an anoxic atmosphere. The fibers may then be coated and used directly in a neutron detection apparatus, or assembled into a geometrical array in a second, hydrogen-rich, scintillating material such as a polymer. Photons generated by interaction with thermal neutrons are trapped within the coated fibers and are directed to photoelectric converters. A measurable electronic signal is generated for each thermal neutron interaction within the fiber. These electronic signals are then manipulated, stored, and interpreted by normal methods to infer the quality and quantity of incident radiation. When the fibers are arranged in an array within a second scintillating material, photons generated by kinetic neutrons interacting with the second scintillating material and photons generated by thermal neutron capture within the fiber can both be directed to photoelectric converters. These electronic signals are then manipulated, stored, and interpreted by normal methods to infer the quality and quantity of incident radiation. 5 figs.

  7. Neutron Computed Tomography Using Real-Time Neutron Radiography.

    NASA Astrophysics Data System (ADS)

    Sulcoski, Mark Francis

    Conventional neutron radiography of an object records a two-dimensional distribution of the neutron beam intensity after it has passed through an object. The neutron radiograph, whether static film or real-time, may be considered a "shadow graph" of the object. In a shadow graph, internal structures in an object may mask one another making it difficult or impossible to precisely define the internals of the object. This problem can be solved by tomographic imaging. A real-time neutron radiography facility was constructed including the capability of neutron tomography. The neutron beam was measured for total neutron flux ((1.0 (+OR-) 0.2) x 10('11) n/(m('2)-sec)), gold cadmium ratio (52 (+OR-) 3) and effective neutron temperature (83(DEGREES)C (+OR -) 8(DEGREES)C). The angular divergence or nonparallelism of the neutron beam was measured to be \\2.3(DEGREES) (+OR -) 0.1(DEGREES) thereby providing a means of quantifying the collimator effectiveness. The resolution capabilities of both static film and real-time neutron radiographs were quantified using a Fourier transform algorithm to calculate the modulation transfer function of both types of radiographs. The contrast sensitivity of both types of radiographs was measured as 3.1% for film and 4.0% for real-time radiographs. Two tomography algorithms, the simultaneous iterative reconstruction technique (SIRT) and the convolution method, were programmed on an Intellect 100 Image Processing System. The SIRT algorithm was found to be too large and slow on the Intellect 100 to produce useful tomographs. The convolution method produced results near the theoretical resolution limits for a given number of projections. A tomographic resolution of at least 1.3 mm was demonstrated using 200 projections. Computer running time for the convolution method was found to be (TURN)30 seconds for each projection used. A series of experiments were conducted using the convolution method investigating the effect of high and low pass

  8. Diagnostic of fusion neutrons on JET tokamak using diamond detector

    NASA Astrophysics Data System (ADS)

    Nemtsev, G.; Amosov, V.; Marchenko, N.; Meshchaninov, S.; Rodionov, R.; Popovichev, S.; JET EFDA contributors

    2014-08-01

    In 2011-2012, an experimental campaign with a significant yield of fusion neutrons was carried out on the JET tokamak. During this campaign the facility was equipped with two diamond detectors based on natural and artificial CVD diamond. These detectors were designed and manufactured in State Research Center of Russian Federation TRINITI. The detectors measure the flux of fast neutrons with energies above 0.2 MeV. They have been installed in the torus hall and the distance from the center of plasma was about 3 m. For some of the JET pulses in this experiment, the neutron flux density corresponded to the operational conditions in collimator channels of ITER Vertical Neutron Camera. The main objective of diamond monitors was the measurement of total fast neutron flux at the detector location and the estimation of the JET total neutron yield. The detectors operate as threshold counters. Additionally a spectrometric measurement channel has been configured that allowed us to distinguish various energy components of the neutron spectrum. In this paper we describe the neutron signal measuring and calibration procedure of the diamond detector. Fluxes of DD and DT neutrons at the detector location were measured. It is shown that the signals of total neutron yield measured by the diamond detector correlate with signals measured by the main JET neutron diagnostic based on fission chambers with high accuracy. This experiment can be considered as a successful test of diamond detectors in ITER-like conditions.

  9. Diagnostic of fusion neutrons on JET tokamak using diamond detector

    SciTech Connect

    Nemtsev, G.; Amosov, V.; Marchenko, N.; Meshchaninov, S.; Rodionov, R.; Popovichev, S.; Collaboration: JET EFDA Conbributors

    2014-08-21

    In 2011-2012, an experimental campaign with a significant yield of fusion neutrons was carried out on the JET tokamak. During this campaign the facility was equipped with two diamond detectors based on natural and artificial CVD diamond. These detectors were designed and manufactured in State Research Center of Russian Federation TRINITI. The detectors measure the flux of fast neutrons with energies above 0.2 MeV. They have been installed in the torus hall and the distance from the center of plasma was about 3 m. For some of the JET pulses in this experiment, the neutron flux density corresponded to the operational conditions in collimator channels of ITER Vertical Neutron Camera. The main objective of diamond monitors was the measurement of total fast neutron flux at the detector location and the estimation of the JET total neutron yield. The detectors operate as threshold counters. Additionally a spectrometric measurement channel has been configured that allowed us to distinguish various energy components of the neutron spectrum. In this paper we describe the neutron signal measuring and calibration procedure of the diamond detector. Fluxes of DD and DT neutrons at the detector location were measured. It is shown that the signals of total neutron yield measured by the diamond detector correlate with signals measured by the main JET neutron diagnostic based on fission chambers with high accuracy. This experiment can be considered as a successful test of diamond detectors in ITER-like conditions.

  10. Incidental Magnetization Transfer Contrast by Fat Saturation Preparation Pulses in Multi-slice Look-Locker Echo Planar Imaging: Modulation of Signal Intensity and Bias on T1 Measurement

    PubMed Central

    Shin, Wanyong; Gu, Hong; Yang, Yihong

    2009-01-01

    In this study, it is demonstrated that fat saturation (FS) preparation (prep) pulses generate incidental magnetization transfer contrast (MTC) in multi-slice Look-Locker imaging. It is shown that frequency-selective FS prep pulses can invoke MTC through the exchange between free and motion-restricted protons. Simulation reveals that the fractional signal loss by these MTC effects is more severe for smaller flip angles, shorter repetition times, and greater number of slices. These incidental MTC effects result in a signal attenuation at a steady state (up to 30%) and a T1 measurement bias (up to 20%) when using inversion recovery Look-Locker EPI sequences. Furthermore, it is shown that water-selective MR imaging using binominal pulses has the potential to minimize the signal attenuation and provide unbiased T1 measurement without fat artifacts in MR images. PMID:19526506

  11. Neutron tomography developments and applications.

    PubMed

    Richards, W J; Gibbons, M R; Shields, K C

    2004-10-01

    Neutron radiography has been in use as a nondestructive testing technique for the past 50 years. The neutrons' unique ability to image certain elements and isotopes that are either completely undetectable or poorly detected by other NDI methods makes neutron radiography an important tool for the NDI community. Neutron radiography like other imaging techniques takes a number of different forms (i.e., film, radioscopic, transfer methods, tomography, etc.) This paper will describe the neutron tomography system developed at the University of California, Davis McClellan Nuclear Radiation Center (UC Davis/MNRC), and the applications for both research and commercial uses. The neutron radiography system at the UC Davis/MNRC has been under development for 4 years. The initial system was developed to find very low concentrations of hydrogen (i.e., <200 ppm). In order to achieve these low detection levels, it was necessary to perform both pre- and post-processing of the tomographs. The pre-processing steps include corrections for spatial resolution and random noise effects. Images are corrected for systematic noise errors and beam hardening. From these data the attenuation coefficient is calculated. The post-processing steps include alignment of the collected images, determining the center of mass, and, finally, using the filtered back-projection routine from the Donner Algorithms Library to obtain the final images. Since its initial development, the tomography system has been used very successfully to find low levels of hydrogen in a metal matrix. Further uses of the system have been to verify the exact placement, in three dimensions, of "O-rings" in large metal valve bodies, and to map the location and extent of veins in porous and high-density rocks of various different kinds. These examples show that neutron tomography is becoming a needed inspection technique for the 21st century. PMID:15246398

  12. Correlating Petrophysical Well Logs Using Fractal-based Analysis to Identify Changes in the Signal Complexity Across Neutron, Density, Dipole Sonic, and Gamma Ray Tool Types

    NASA Astrophysics Data System (ADS)

    Matthews, L.; Gurrola, H.

    2015-12-01

    Typical petrophysical well log correlation is accomplished by manual pattern recognition leading to subjective correlations. The change in character in a well log is dependent upon the change in the response of the tool to lithology. The petrophysical interpreter looks for a change in one log type that would correspond to the way a different tool responds to the same lithology. To develop an objective way to pick changes in well log characteristics, we adapt a method of first arrival picking used in seismic data to analyze changes in the character of well logs. We chose to use the fractal method developed by Boschetti et al[1] (1996). This method worked better than we expected and we found similar changes in the fractal dimension across very different tool types (sonic vs density vs gamma ray). We reason the fractal response of the log is not dependent on the physics of the tool response but rather the change in the complexity of the log data. When a formation changes physical character in time or space the recorded magnitude in tool data changes complexity at the same time even if the original tool response is very different. The relative complexity of the data regardless of the tool used is dependent upon the complexity of the medium relative to tool measurement. The relative complexity of the recorded magnitude data changes as a tool transitions from one character type to another. The character we are measuring is the roughness or complexity of the petrophysical curve. Our method provides a way to directly compare different log types based on a quantitative change in signal complexity. For example, using changes in data complexity allow us to correlate gamma ray suites with sonic logs within a well and then across to an adjacent well with similar signatures. Our method creates reliable and automatic correlations to be made in data sets beyond the reasonable cognitive limits of geoscientists in both speed and consistent pattern recognition. [1] Fabio Boschetti

  13. Active Neutron Shielding R&D for Dark Matter Searches

    NASA Astrophysics Data System (ADS)

    Henderson, Shawn; Monroe, Jocelyn; Fisher, Peter; Dmtpc Collaboration

    2011-04-01

    Neutrons are a dangerous background to direct dark matter detection searches because they can mimic exactly the signal signature. For this reason, it is desirable to measure the neutron flux directly at underground sites where dark matter experiments are active. We have developed a liquid scintillator-based neutron detector for this purpose, which is currently underground and taking data at the Waste Isolation Pilot Plant (WIPP) in NM. Before being commissioned underground, the response of this detector to neutrons with kinetic energies from 50 MeV to 800 MeV was determined in a beam test at the Los Alamos Neutron Science Center (LANSCE) in NM. The goal of this R&D is to (i) demonstrate the feasibility of a large scale active and passive neutron shield for dark matter searches and (ii) to measure the neutron energy spectrum underground at WIPP above 50 MeV neutron kinetic energies.

  14. Enhanced NIF neutron activation diagnostics

    SciTech Connect

    Yeamans, C. B.; Bleuel, D. L.; Bernstein, L. A.

    2012-10-15

    The NIF neutron activation diagnostic suite relies on removable activation samples, leading to operational inefficiencies and a fundamental lower limit on the half-life of the activated product that can be observed. A neutron diagnostic system measuring activation of permanently installed samples could remove these limitations and significantly enhance overall neutron diagnostic capabilities. The physics and engineering aspects of two proposed systems are considered: one measuring the {sup 89}Zr/{sup 89m}Zr isomer ratio in the existing Zr activation medium and the other using potassium zirconate as the activation medium. Both proposed systems could improve the signal-to-noise ratio of the current system by at least a factor of 5 and would allow independent measurement of fusion core velocity and fuel areal density.

  15. Enhanced NIF neutron activation diagnostics.

    PubMed

    Yeamans, C B; Bleuel, D L; Bernstein, L A

    2012-10-01

    The NIF neutron activation diagnostic suite relies on removable activation samples, leading to operational inefficiencies and a fundamental lower limit on the half-life of the activated product that can be observed. A neutron diagnostic system measuring activation of permanently installed samples could remove these limitations and significantly enhance overall neutron diagnostic capabilities. The physics and engineering aspects of two proposed systems are considered: one measuring the (89)Zr/(89 m)Zr isomer ratio in the existing Zr activation medium and the other using potassium zirconate as the activation medium. Both proposed systems could improve the signal-to-noise ratio of the current system by at least a factor of 5 and would allow independent measurement of fusion core velocity and fuel areal density.

  16. Enhanced NIF neutron activation diagnosticsa)

    NASA Astrophysics Data System (ADS)

    Yeamans, C. B.; Bleuel, D. L.; Bernstein, L. A.

    2012-10-01

    The NIF neutron activation diagnostic suite relies on removable activation samples, leading to operational inefficiencies and a fundamental lower limit on the half-life of the activated product that can be observed. A neutron diagnostic system measuring activation of permanently installed samples could remove these limitations and significantly enhance overall neutron diagnostic capabilities. The physics and engineering aspects of two proposed systems are considered: one measuring the 89Zr/89mZr isomer ratio in the existing Zr activation medium and the other using potassium zirconate as the activation medium. Both proposed systems could improve the signal-to-noise ratio of the current system by at least a factor of 5 and would allow independent measurement of fusion core velocity and fuel areal density.

  17. Neutron energy measurements in emergency response applications

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Sanjoy; Guss, Paul; Hornish, Michael; Wilde, Scott; Stampahar, Tom; Reed, Michael

    2009-08-01

    We present significant results in recent advances in the measurement of neutron energy. Neutron energy measurements are a small but significant part of radiological emergency response applications. Mission critical information can be obtained by analyzing the neutron energy given off from radioactive materials. In the case of searching for special nuclear materials, neutron energy information from an unknown source can be of importance. At the Remote Sensing Laboratory (RSL) of National Security Technologies, LLC, a series of materials, viz., liquid organic scintillator (LOS), Lithium Gadolinium Borate (LGB) or Li6Gd(BO3)3 in a plastic matrix, a recently developed crystal of Cesium Lithium Yttrium Chloride, Cs2LiYCl6: Ce (called CLYC)[1], and normal plastic scintillator (BC-408) with 3He tubes have been used to study their effectiveness as a portable neutron energy spectrometer. Comparisons illustrating the strengths of the various materials will be provided. Of these materials, LGB offers the ability to tailor its response to the neutron spectrum by varying the isotopic composition of the key constituents (Lithium, Gadolinium [Yttrium], and Boron). All three of the constituent elements possess large neutron capture cross section isotopes for highly exothermic reactions. These compounds of composition Li6Gd(Y)(BO3)3 can be activated by Cerium ions Ce3+. CLYC, on the other hand, has a remarkable gamma response in addition to superb neutron discrimination, comparable to that of Europium-doped Lithium Iodide (6LiI: Eu). Comparing these two materials, CLYC has higher light output (4500 phe/MeV) than that from 6LiI: Eu and shows better energy resolution for both gamma and neutron pulse heights. Using CLYC, gamma energy pulses can be discriminated from the neutron signals by simple pulse height separation. For the cases of both LGB and LOS, careful pulse shape discrimination is needed to separate the gamma energy signals from neutron pulses. Both analog and digital

  18. Fast oxygen diffusion in bismuth oxide probed by quasielastic neutron scattering

    DOE PAGESBeta

    Mamontov, Eugene

    2016-09-24

    In this paper, we present the first, to our knowledge, study of solid state oxygen translational diffusion by quasielastic neutron scattering. Such studies in the past might have been precluded by relatively low diffusivities of oxygen anions in the temperature range amenable to neutron scattering experiments. To explore the potential of the quasielastic scattering technique, which can deduce atomic diffusion jump length of oxygen anions through the momentum transfer dependence of the scattering signal, we have selected the fastest known oxygen conductor, bismuth oxide. Finally, we have found the oxygen anion jump length in excellent agreement with the nearest oxygen-vacancymore » distance in the anion sublattice of the fluorite-related structure of bismuth oxide.« less

  19. NEUTRON COUNTER

    DOEpatents

    Curtis, C.D.; Carlson, R.L.; Tubinis, M.P.

    1958-07-29

    An ionization chamber instrument is described for cylindrical electrodes with an ionizing gag filling the channber. The inner electrode is held in place by a hermetic insulating seal at one end of the outer electrode, the other end of the outer electrode being closed by a gas filling tube. The outer surface of the inner electrode is coated with an active material which is responsive to neutron bombardment, such as uranium235 or boron-10, to produce ionizing radiations in the gas. The transverse cross sectional area of the inner electrode is small in relation to that of the channber whereby substantially all of the radiations are directed toward the outer electrode.

  20. NEUTRON SOURCE

    DOEpatents

    Reardon, W.A.; Lennox, D.H.; Nobles, R.G.

    1959-01-13

    A neutron source of the antimony--beryllium type is presented. The source is comprised of a solid mass of beryllium having a cylindrical recess extending therein and a cylinder containing antimony-124 slidably disposed within the cylindrical recess. The antimony cylinder is encased in aluminum. A berylliunn plug is removably inserted in the open end of the cylindrical recess to completely enclose the antimony cylinder in bsryllium. The plug and antimony cylinder are each provided with a stud on their upper ends to facilitate handling remotely.

  1. Search for the Neutron Electric Dipole Moment

    SciTech Connect

    Plaster, Brad

    2010-08-04

    Searches for the neutron electric dipole moment (EDM) are motivated by their highly suppressed Standard Model value. The observation of a non-zero signal in the next generation of experiments would point unambiguously to the existence of new physics beyond the Standard Model. Several ongoing efforts worldwide hold the potential for an up to two-orders-of-magnitude improvement beyond the current upper limit on the neutron EDM of 2.9x10{sup -6} e-cm. In this talk, I review the basic measurement principles of neutron EDM searches, then discuss a new experiment to be carried out in the United States at the Spallation Neutron Source with ultracold neutrons and an in-situ '3He''co-magnetometer'.

  2. Testing The High-Energy Prompt Neutron Signature At Low Beam Energies

    SciTech Connect

    Thompson, Scott J.; Kinlaw, Mathew T.; Hunt, Alan W.

    2011-06-01

    Prompt fission neutrons continue to be examined as a signature for detecting the presence of fissionable material. This technique exploits the neutron energy limitations inherent with photonuclear emissions from non-fissionable material, allowing prompt fission neutrons to be identified and engaged for detecting nuclear material. Prompt neutron signal measurements were acquired with bremsstrahlung endpoint energies of 6 MeV for 18 targets comprised of both fissionable and non-fissionable material; delayed neutron measurements were also collected as a reference. The {sup 238}U target was also shielded with increasing thicknesses of lead or borated polyethylene to compare the resulting detection rates of the prompt and delayed fission neutron signals.

  3. Composite polycrystalline semiconductor neutron detectors

    NASA Astrophysics Data System (ADS)

    Schieber, M.; Zuck, A.; Marom, G.; Khakhan, O.; Roth, M.; Alfassi, Z. B.

    2007-08-01

    Composite polycrystalline semiconductor detectors bound with different binders, both inorganic molten glasses, such as B 2O 3, PbO/B 2O 3, Bi 2O 3/PbO, and organic polymeric binders, such as isotactic polypropylene (iPP), polystyrene or nylon-6, and coated with different metal electrodes were tested at room temperature for α-particles and very weak thermal neutron sources. The detector materials tested were natural occurring hexagonal BN and cubic LiF, where both are not containing enriched isotopes of 10B or 6Li. The radiation sources were 5.5 MeV α's from 241Am, 5.3 MeV from 210Po and also 4.8 MeV from 226Ra. Some of these detectors were also tested with thermal neutrons from very weak 227Ac 9Be, 241Am- 10Be sources and also from a weak 238Pu+ 9Be and somewhat stronger 252Cf sources. The neutrons were thermalized with paraffin. Despite very low signal to noise ratio of only ˜2, the neutrons could be counted by subtracting the noise from the signal.

  4. Gravitomagnetic resonant excitation of Rossby modes in coalescing neutron star binaries

    NASA Astrophysics Data System (ADS)

    Flanagan, Éanna É.; Racine, Étienne

    2007-02-01

    In coalescing neutron star binaries, r-modes in one of the stars can be resonantly excited by the gravitomagnetic tidal field of its companion. This post-Newtonian gravitomagnetic driving of these modes dominates over the Newtonian tidal driving previously computed by Ho and Lai. To leading order in the tidal expansion parameter R/r (where R is the radius of the neutron star and r is the orbital separation), only the l=2, |m|=1, and |m|=2 r-modes are excited. The tidal work done on the star through this driving has an effect on the evolution of the inspiral and on the phasing of the emitted gravitational wave signal. For a neutron star of mass M, radius R, spin frequency fspin, modeled as a Γ=2 polytrope, with a companion also of mass M, the gravitational wave phase shift for the m=2 mode is ˜0.1radians(R/10km)4(M/1.4M⊙)-10/3(fspin/100Hz)2/3 for optimal spin orientation. For canonical neutron star parameters this phase shift will likely not be detectable by gravitational wave detectors such as LIGO, but if the neutron star radius is larger it may be detectable if the signal-to-noise ratio is moderately large. The energy transfer is large enough to drive the mode into the nonlinear regime if fspin≳100Hz. For neutron star—black hole binaries, the effect is smaller; the phase shift scales as companion mass to the -4/3 power for large companion masses. The net energy transfer from the orbit into the star is negative corresponding to a slowing down of the inspiral. This occurs because the interaction reduces the spin of the star, and occurs only for modes which satisfy the Chandrasekhar-Friedman-Schutz instability criterion. A large portion of the paper is devoted to developing a general formalism to treat mode driving in rotating stars to post-Newtonian order, which may be useful for other applications. We also correct some conceptual errors in the literature on the use of energy conservation to deduce the effect of the mode driving on the gravitational wave

  5. Neutron radiography of irradiated nuclear fuel at Idaho National Laboratory

    SciTech Connect

    Craft, Aaron E.; Wachs, Daniel M.; Okuniewski, Maria A.; Chichester, David L.; Williams, Walter J.; Papaioannou, Glen C.; Smolinski, Andrew T.

    2015-09-10

    Neutron radiography of irradiated nuclear fuel provides more comprehensive information about the internal condition of irradiated nuclear fuel than any other non-destructive technique to date. Idaho National Laboratory (INL) has multiple nuclear fuels research and development programs that routinely evaluate irradiated fuels using neutron radiography. The Neutron Radiography reactor (NRAD) sits beneath a shielded hot cell facility where neutron radiography and other evaluation techniques are performed on these highly radioactive objects. The NRAD currently uses the foil-film transfer technique for imaging fuel that is time consuming but provides high spatial resolution. This study describes the NRAD and hot cell facilities, the current neutron radiography capabilities available at INL, planned upgrades to the neutron imaging systems, and new facilities being brought online at INL related to neutron imaging.

  6. Neutron radiography of irradiated nuclear fuel at Idaho National Laboratory

    DOE PAGESBeta

    Craft, Aaron E.; Wachs, Daniel M.; Okuniewski, Maria A.; Chichester, David L.; Williams, Walter J.; Papaioannou, Glen C.; Smolinski, Andrew T.

    2015-09-10

    Neutron radiography of irradiated nuclear fuel provides more comprehensive information about the internal condition of irradiated nuclear fuel than any other non-destructive technique to date. Idaho National Laboratory (INL) has multiple nuclear fuels research and development programs that routinely evaluate irradiated fuels using neutron radiography. The Neutron Radiography reactor (NRAD) sits beneath a shielded hot cell facility where neutron radiography and other evaluation techniques are performed on these highly radioactive objects. The NRAD currently uses the foil-film transfer technique for imaging fuel that is time consuming but provides high spatial resolution. This study describes the NRAD and hot cell facilities,more » the current neutron radiography capabilities available at INL, planned upgrades to the neutron imaging systems, and new facilities being brought online at INL related to neutron imaging.« less

  7. Determination of the Neutron Magnetic Moment

    DOE R&D Accomplishments Database

    Greene, G. L.; Ramsey, N. F.; Mampe, W.; Pendlebury, J. M.; Smith, K.; Dress, W. B.; Miller, P. D.; Perrin, P.

    1981-06-01

    The neutron magnetic moment has been measured with an improvement of a factor of 100 over the previous best measurement. Using a magnetic resonance spectrometer of the separated oscillatory field type capable of determining a resonance signal for both neutrons and protons (in flowing H{sub 2}O), we find ..mu..{sub n}/..mu..{sub p} = 0.68497935(17) (0.25 ppM). The neutron magnetic moment can also be expressed without loss of accuracy in a variety of other units.

  8. Radio Detection of Neutron Star Binary Mergers

    NASA Astrophysics Data System (ADS)

    Bear, Brandon; Cardena, Brett; Dispoto, Dana; Papadopoulos, Joanna; Kavic, Michael; Simonetti, John

    2011-10-01

    Neutron star binary systems lose energy through gravitational radiation, and eventually merge. The gravitational radiation from the merger can be detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO). It is expected that a transient radio pulse will also be produced during the merger event. Detection of such radio transients would allow for LIGO to search for signals within constrained time periods. We calculate the LWA-1 detection rate of transient events from neutron star binary mergers. We calculate the detection rate of transient events from neutron star binary mergers for the Long Wavelength Array and the Eight-meter-wavelength Transient Array.

  9. Methods for Neutron Spectrometry

    DOE R&D Accomplishments Database

    Brockhouse, Bertram N.

    1961-01-09

    The appropriate theories and the general philosophy of methods of measurement and treatment of data neutron spectrometry are discussed. Methods of analysis of results for liquids using the Van Hove formulation, and for crystals using the Born-von Karman theory, are reviewed. The most useful of the available methods of measurement are considered to be the crystal spectrometer methods and the pulsed monoenergetic beam/time-of-flight method. Pulsed-beam spectrometers have the advantage of higher counting rates than crystal spectrometers, especially in view of the fact that simultaneous measurements in several counters at different angles of scattering are possible in pulsed-beam spectrometers. The crystal spectrometer permits several valuable new types of specialized experiments to be performed, especially energy distribution measurements at constant momentum transfer. The Chalk River triple-axis crystal-spectrometer is discussed, with reference to its use in making the specialized experiments. The Chalk River rotating crystal (pulsed-beam) spectrometer is described, and a comparison of this type instrument with other pulsed-beam spectrometers is made. A partial outline of the theory of operation of rotating-crystal spectrometers is presented. The use of quartz-crystal filters for fast neutron elimination and for order elimination is discussed. (auth)

  10. RdgBα reciprocally transfers PA and PI at ER-PM contact sites to maintain PI(4,5)P2 homoeostasis during phospholipase C signalling in Drosophila photoreceptors.

    PubMed

    Cockcroft, Shamshad; Garner, Kathryn; Yadav, Shweta; Gomez-Espinoza, Evelyn; Raghu, Padinjat

    2016-02-01

    Phosphatidylinositol (PI) is the precursor lipid for the synthesis of PI 4,5-bisphosphate [PI(4,5)P2] at the plasma membrane (PM) and is sequentially phosphorylated by the lipid kinases, PI 4-kinase and phosphatidylinositol 4-phosphate (PI4P)-5-kinase. Receptor-mediated hydrolysis of PI(4,5)P2 takes place at the PM but PI resynthesis occurs at the endoplasmic reticulum (ER). Thus PI(4,5)P2 resynthesis requires the reciprocal transport of two key intermediates, phosphatidic acid (PA) and PI between the ER and the PM. PI transfer proteins (PITPs), defined by the presence of the PITP domain, can facilitate lipid transfer between membranes; the PITP domain comprises a hydrophobic cavity with dual specificity but accommodates a single phospholipid molecule. The class II PITP, retinal degeneration type B (RdgB)α is a multi-domain protein and its PITP domain can bind and transfer PI and PA. In Drosophila photoreceptors, a well-defined G-protein-coupled phospholipase Cβ (PLCβ) signalling pathway, phototransduction defects resulting from loss of RdgBα can be rescued by expression of the PITP domain provided it is competent for both PI and PA transfer. We propose that RdgBα proteins maintain PI(4,5)P2 homoeostasis after PLC activation by facilitating the reciprocal transport of PA and PI at ER-PM membrane contact sites.

  11. Independent backup mode transfer and mechanism for digital control computers

    NASA Technical Reports Server (NTRS)

    Tulpule, Bhalchandra R. (Inventor); Oscarson, Edward M. (Inventor)

    1992-01-01

    An interrupt is provided to a signal processor having a non-maskable interrupt input, in response to the detection of a request for transfer to backup software. The signal processor provides a transfer signal to a transfer mechanism only after completion of the present machine cycle. Transfer to the backup software is initiated by the transfer mechanism only upon reception of the transfer signal.

  12. Neutron matter, symmetry energy and neutron stars

    SciTech Connect

    Stefano, Gandolfi; Steiner, Andrew W

    2016-01-01

    Recent progress in quantum Monte Carlo with modern nucleon-nucleon interactions have enabled the successful description of properties of light nuclei and neutron-rich matter. Of particular interest is the nuclear symmetry energy, the energy cost of creating an isospin asymmetry, and its connection to the structure of neutron stars. Combining these advances with recent observations of neutron star masses and radii gives insight into the equation of state of neutron-rich matter near and above the saturation density. In particular, neutron star radius measurements constrain the derivative of the symmetry energy.

  13. Neutron-Resonance Capture Analysis of Materials

    SciTech Connect

    Postma, H.; Bode, P.; Blaauw, M.; Corvi, F.

    1999-11-14

    Epithermal neutron activation analysis is a well-established approach to improve the sensitivity for certain elements by suppressing the activation of interfering elements. If epithermal neutrons of a given energy could be selected, the signal-to-noise ratio might be further improved by taking advantage of resonance capture. This reaction occurs mainly by intermediate and heavy nuclei. Moreover, most of these reactions take place with epithermal or fast neutrons. Intense epithermal neutrons are available as ''white'' beams at accelerator-driven neutron sources. Neutron resonance capture offers interesting analytical opportunities. Low-Z elements have little capture of epithermal neutrons and are thus virtually absent in the time-of-flight spectrum. Relatively large objects can be placed in the neutron beam and analyzed nondestructively. The induced radioactivity is relatively low. If an element has several stable isotopes, each of these isotopes can be recognized by its specific resonances. This would allow for multitracer studies with several isotopically labeled compounds. Different from mass spectrometry, the sample remains intact and can be used for further studies after analysis. Applications may be in the field of archaeology, metallurgy, and certification of reference materials.

  14. Nested neutron microfocusing optics on SNAP

    SciTech Connect

    Ice, Gene E; Choi, Jae-Young; Takacs, P. Z.; Khounsary, Ali; Puzyrev, Yevgeniy S; Molaison, Jamie J; Tulk, Christopher A; Andersen, K H; Bigault, T

    2010-01-01

    The high source intensity of the Spallation Neutron Source (SNS), together with efficient detectors and large detector solid angles, now makes possible neutron experiments with much smaller sample volumes than previously were practical. Nested Kirkpatrick-Baez supermirror optics provide a promising and efficient way to further decrease the useable neutron sample size by focusing polychromatic neutrons into microbeams. Because the optics are nondispersive, they are ideal for spallation sources and for polychromatic and wide bandpass experiments on reactor sources. Theoretical calculations indicate that nested mirrors can preserve source brilliance at the sample for small beams and for modest divergences that are appropriate for diffraction experiments. Although the flux intercepted by a sample can be similar with standard beam-guided approaches, the signal-to-background is much improved with small beams on small samples. Here we describe the design, calibration and performance of a nested neutron mirror pair for the Spallation Neutrons At Pressure (SNAP) beamline at the SNS. High-pressure neutron diffraction is but one example of a large class of neutron experiments that will benefit from spatially-resolved microdiffraction.

  15. The new Cold Neutron Chopper Spectrometer at the Spallation Neutron Source -- Design and Performance

    SciTech Connect

    Ehlers, Georg; Podlesnyak, Andrey A.; Niedziela, Jennifer L.; Iverson, Erik B.; Sokol, Paul E.

    2011-01-01

    The design and performance of the new cold neutron chopper spectrometer (CNCS) at the Spallation Neutron Source in Oak Ridge are described. CNCS is a direct-geometry inelastic time-of-flight spectrometer, designed essentially to cover the same energy and momentum transfer ranges as IN5 at ILL, LET at ISIS, DCS at NIST, TOFTOF at FRM-II, AMATERAS at J-PARC, PHAROS at LANSCE, and NEAT at HZB, at similar energy resolution. Measured values of key figures such as neutron flux at sample position and energy resolution are compared between measurements and ray tracing Monte Carlo simulations, and good agreement (better than 20% of absolute numbers) has been achieved. The instrument performs very well in the cold and thermal neutron energy ranges, and promises to become a workhorse for the neutron scattering community for quasielastic and inelastic scattering experiments.

  16. The new cold neutron chopper spectrometer at the Spallation Neutron Source: Design and performance

    SciTech Connect

    Ehlers, G.; Podlesnyak, A. A.; Niedziela, J. L.; Iverson, E. B.; Sokol, P. E.

    2011-08-15

    The design and performance of the new cold neutron chopper spectrometer (CNCS) at the Spallation Neutron Source in Oak Ridge are described. CNCS is a direct-geometry inelastic time-of-flight spectrometer, designed essentially to cover the same energy and momentum transfer ranges as IN5 at ILL, LET at ISIS, DCS at NIST, TOFTOF at FRM-II, AMATERAS at J-PARC, PHAROS at LANSCE, and NEAT at HZB, at similar energy resolution. Measured values of key figures such as neutron flux at sample position and energy resolution are compared between measurements and ray tracing Monte Carlo simulations, and good agreement (better than 20% of absolute numbers) has been achieved. The instrument performs very well in the cold and thermal neutron energy ranges, and promises to become a workhorse for the neutron scattering community for quasielastic and inelastic scattering experiments.

  17. Neutron reflecting supermirror structure

    DOEpatents

    Wood, James L.

    1992-01-01

    An improved neutron reflecting supermirror structure comprising a plurality of stacked sets of bilayers of neutron reflecting materials. The improved neutron reflecting supermirror structure is adapted to provide extremely good performance at high incidence angles, i.e. up to four time the critical angle of standard neutron mirror structures. The reflection of neutrons striking the supermirror structure at a high critical angle provides enhanced neutron throughput, and hence more efficient and economical use of neutron sources. One layer of each set of bilayers consist of titanium, and the second layer of each set of bilayers consist of an alloy of nickel with carbon interstitially present in the nickel alloy.

  18. NEUTRONIC REACTOR

    DOEpatents

    Stewart, H.B.

    1958-12-23

    A nuclear reactor of the type speclfically designed for the irradiation of materials is discussed. In this design a central cyllndrical core of moderating material ls surrounded by an active portlon comprlsed of an annular tank contalning fissionable material immersed ln a liquid moderator. The active portion ls ln turn surrounded by a reflector, and a well ls provided in the center of the core to accommodate the materlals to be irradiated. The over-all dimensions of the core ln at least one plane are equal to or greater than twice the effective slowing down length and equal to or less than twlce the effective diffuslon length for neutrons in the core materials.

  19. NEUTRONIC REACTORS

    DOEpatents

    Wigner, E.P.; Young, G.J.

    1958-10-14

    A method is presented for loading and unloading rod type fuel elements of a neutronic reactor of the heterogeneous, solld moderator, liquid cooled type. In the embodiment illustrated, the fuel rods are disposed in vertical coolant channels in the reactor core. The fuel rods are loaded and unloaded through the upper openings of the channels which are immersed in the coolant liquid, such as water. Unloading is accomplished by means of a coffer dam assembly having an outer sleeve which is placed in sealing relation around the upper opening. A radiation shield sleeve is disposed in and reciprocable through the coffer dam sleeve. A fuel rod engaging member operates through the axial bore in the radiation shield sleeve to withdraw the fuel rod from its position in the reactor coolant channel into the shield, the shield snd rod then being removed. Loading is accomplished in the reverse procedure.

  20. Direct Measurement of Neutron-Neutron Scattering

    SciTech Connect

    Sharapov, E.I.; Furman, W.I.; Lychagin, W.I.; Muzichka, G.V.; Nekhaev, G.V.; Safronov, Yu.V.; Shvetsov, V.N.; Strelkov, A.V.; Bowman, C.D.; Crawford, B.E.; Stephenson, S.L.; Howell, C.R.; Tornow, W.; Levakov, B.G.; Litvin, V.I.; Lyzhin, A.E.; Magda, E.P.; Mitchell, G.E.

    2003-08-26

    In order to resolve long-standing discrepancies in indirect measurements of the neutron-neutron scattering length ann and contribute to solving the problem of the charge symmetry of the nuclear force, the collaboration DIANNA (Direct Investigation of ann Association) plans to measure the neutron-neutron scattering cross section {sigma}nn. The key issue of our approach is the use of the through-channel in the Russia reactor YAGUAR with a peak neutron flux of 10{sup 18} /cm2/s. The proposed experimental setup is described. Results of calculations are presented to connect {sigma}nn with the nn-collision detector count rate and the neutron flux density in the reactor channel. Measurements of the thermal neutron fields inside polyethylene converters show excellent prospects for the realization of the direct nn-experiment.

  1. Scintillation fiber array detector for measurement of neutron beam profile

    NASA Astrophysics Data System (ADS)

    Kim, Chong; Hong, Byungsik; Jo, Mihee; Lee, Kyong Sei; Sim, Kwang-Souk

    2009-10-01

    We built and tested a detector to measure the profile of fast-neutron beams delivered by the MC50 cyclotron at the Korea Institute of Radiological and Medical Science (KIRAMS). The core component of the detector is a 2×46 array of scintillation fibers. The light output of the scintillation fibers is transformed into a current signal by a 46-channel silicon photodiode and digitized by a current-mode signal processor. This scanning device was designed to cover a neutron beam area of 30×32 cm2. The detector was tested in a neutron beam delivered by the MC50 cyclotron at KIRAMS. We demonstrate that the detector can successfully measure the neutron beam profile at various beam currents from 10 to 20 μA. The proposed neutron beam profile detector will be useful, for example, in radiotherapy applications with neutron intensities above 107 Hz/cm2.

  2. Semiconducting boron carbide polymers devices for neutron detection

    NASA Astrophysics Data System (ADS)

    Echeverria, Elena; Pasquale, Frank L.; James, Robinson; Colón Santana, Juan A.; Adenwalla, Shireen; Kelber, Jeffry A.; Dowben, Peter A.

    2014-03-01

    Boron carbide materials, with aromatic compounds included, prove to be effective materials as solid state neutron detector detectors. The I-V characteristic curves for these heterojunction diodes with silicon show that these modified boron carbides, in the presence of these linking groups such as 1,4-diaminobenzene (DAB) and pyridine, are p-type. Cadmium was used as shield to discriminate between neutron-induced signals and thermal neutrons, and thermal neutron capture is evident, while gamma detection was not realized. Neutron detection signals for these heterojunction diode were observed, a measurable zero bias current noted, even without complete electron-hole collection. This again illustrates that boron carbide devices can be considered a neutron voltaic.

  3. From Source to Sink: Integration and Alteration of Oxygen Isotope Signals during the Transfer from Precipitation to Leaf Water, Leaf Sugars, Twig Phloem Sugars into the Stem Phloem Sugars of Four Mature European Tree Species

    NASA Astrophysics Data System (ADS)

    Brinkmann, N.; Werner, R. A.; Buchmann, N. C.; Kahmen, A.

    2014-12-01

    Stable oxygen isotope ratios (δ18O) of stem cellulose record physiological and ecohydrological information and are increasingly being used for the reconstruction of past environments. Studies that have investigated the environmental and physiological drivers of δ18O values in tree ring cellulose have typically focused either on the source of the signal, e.g. the leaf and the water therein, or on the sink, e.g. the cellulose in the stem. In contrast, hardly any research has investigated the transfer of the δ18O signal from precipitation, to soil water, xylem water, leaf water, leaf sugars, phloem sugars all the way to cellulose in the tree ring. As such, critical uncertainties remain regarding the seasonal integration and precision by which precipitation and leaf water δ18O signals are recorded in the tree ring cellulose δ18O values. In our talk, we will present a unique three year dataset that shows the seasonal variation of δ18O values in precipitation, soil water, xylem water, leaf water, leaf sugars, twig and stem phloem sugars for four common European tree species, which are growing in a mature temperature Swiss mixed broadleaf/evergreen forest. This dataset allows us to assess, (i) to what degree the substantial seasonal variation in precipitation δ18O values influences the δ18O values of tree ring cellulose and (ii) if physiological and environmental δ18O signals imprinted on the tree's leaf water δ18O values and the assimilates formed therein are altered on their way downstream to the tree stem. The new insight that we provide into the integration and possible alteration of δ18O signals along the leaf-stem pathway will contribute significantly to a better understanding of the environmental and physiological signals that can be obtained from tree ring δ18O chronologies. In addition it will be relevant for the incorporation and parameterization of tree ring isotope models into dynamic global vegetation models.

  4. Resonance enhanced neutron standing waves in thin films

    SciTech Connect

    Satija, S.K.; Gallagher, P.D.; Lindstrom, R.M.; Paul, R.L.; Zhang, H. |; Russell, T.P.; Lambooy, P.; Kramer, E.J.

    1995-12-31

    Simultaneous measurements of neutron reflectivity and prompt gamma ray emission, from samples with buried Gd layers, are shown to be of significant aid in determining the depth profile of the entire sample. Because of resonant enhancement of the neutron standing waves in the sample, the gamma ray signals are considerably enhanced making these experiments possible. A possible application of this technique to study grazing angle neutron diffraction is also mentioned.

  5. Registration of Neutrons Within 2 Milliseconds after EAS

    NASA Astrophysics Data System (ADS)

    JȨDRZEJCZAK, K.; Karczmarczyk, J.; Kasztelan, M.; Petrochenkov, S. A.; Polański, A.; Swarzyński, J.; Szabelski, J.; Wibig, T.

    We register an excess of signals from neutron detectors within a few milliseconds after passage of EAS front in Łódź EAS array. The most probable explanation is that neutrons are produced in EAS hadron interactions with lead block of muon detector. These neutrons diffuse and are thermalized before the detection. We present experimental data and results of simulations using MCNP code. This "new EAS observable" can be used as inexpensive hadron detector in EAS.

  6. Layered shielding design for an active neutron interrogation system

    NASA Astrophysics Data System (ADS)

    Whetstone, Zachary D.; Kearfott, Kimberlee J.

    2016-08-01

    The use of source and detector shields in active neutron interrogation can improve detector signal. In simulations, a shielded detector with a source rotated π/3 rad relative to the opening decreased neutron flux roughly three orders of magnitude. Several realistic source and detector shield configurations were simulated. A layered design reduced neutron and secondary photon flux in the detector by approximately one order of magnitude for a deuterium-tritium source. The shield arrangement can be adapted for a portable, modular design.

  7. A white beam neutron spin splitter

    SciTech Connect

    Krist, T.; Klose, F.; Felcher, G.P.

    1997-07-23

    The polarization of a narrow, highly collimated polychromatic neutron beam is tested by a neutron spin splitter that permits the simultaneous measurement of both spin states. The device consists of a Si-Co{sub 0.11} Fe{sub 0.89} supermirror, which totally reflects one spin state up to a momentum transfer q=0.04 {angstrom}{sup -1}, whilst transmits neutrons of the opposite spin state. The supermirror is sandwitched between two thick silicon wafers and is magnetically saturated by a magnetic field of 400 Oe parallel to its surface. The neutron beam enters through the edge of one of the two silicon wavers, its spin components are split by the supermirror and exit from the opposite edges of the two silicon wafers and are recorded at different channels of a position-sensitive detector. The device is shown to have excellent efficiency over a broad range of wavelengths.

  8. Neutron Imaging Calibration to Measure Void Fraction

    SciTech Connect

    Geoghegan, Patrick J; Bilheux, Hassina Z; Sharma, Vishaldeep; Fricke, Brian A

    2015-01-01

    Void fraction is an intuitive parameter that describes the fraction of vapor in a two-phase flow. It appears as a key variable in most heat transfer and pressure drop correlations used to design evaporating and condensing heat exchangers, as well as determining charge inventory in refrigeration systems. Void fraction measurement is not straightforward, however, and assumptions on the invasiveness of the measuring technique must be made. Neutron radiography or neutron imaging has the potential to be a truly non-invasive void fraction measuring technique but has until recently only offered qualitative descriptions of two-phase flow, in terms of flow maldistributions, for example. This paper describes the calibration approach necessary to employ neutron imaging to measure steady-state void fraction. Experiments were conducted at the High Flux Isotope Reactor (HFIR) Cold Guide 1D neutron imaging facility at Oak Ridge National Laboratory (ORNL), Oak Ridge, TN, USA.

  9. Neutron kinetics in moderators and SNM detection through epithermal-neutron-induced fissions

    NASA Astrophysics Data System (ADS)

    Gozani, Tsahi; King, Michael J.

    2016-01-01

    Extension of the well-established Differential Die Away Analysis (DDAA) into a faster time domain, where more penetrating epithermal neutrons induce fissions, is proposed and demonstrated via simulations and experiments. In the proposed method the fissions stimulated by thermal, epithermal and even higher-energy neutrons are measured after injection of a narrow pulse of high-energy 14 MeV (d,T) or 2.5 MeV (d,D) source neutrons, appropriately moderated. The ability to measure these fissions stems from the inherent correlation of neutron energy and time ("E-T" correlation) during the process of slowing down of high-energy source neutrons in common moderating materials such as hydrogenous compounds (e.g., polyethylene), heavy water, beryllium and graphite. The kinetic behavior following injection of a delta-function-shaped pulse (in time) of 14 MeV neutrons into such moderators is studied employing MCNPX simulations and, when applicable, some simple "one-group" models. These calculations served as a guide for the design of a source moderator which was used in experiments. Qualitative relationships between slowing-down time after the pulse and the prevailing neutron energy are discussed. A laboratory system consisting of a 14 MeV neutron generator, a polyethylene-reflected Be moderator, a liquid scintillator with pulse-shape discrimination (PSD) and a two-parameter E-T data acquisition system was set up to measure prompt neutron and delayed gamma-ray fission signatures in a 19.5% enriched LEU sample. The measured time behavior of thermal and epithermal neutron fission signals agreed well with the detailed simulations. The laboratory system can readily be redesigned and deployed as a mobile inspection system for SNM in, e.g., cars and vans. A strong pulsed neutron generator with narrow pulse (<75 ns) at a reasonably high pulse frequency could make the high-energy neutron induced fission modality a realizable SNM detection technique.

  10. Gravitational waves from neutron-star mergers

    NASA Astrophysics Data System (ADS)

    Read, Jocelyn; Cullen, Torrey; Flynn, Eric; Lockett-Ruiz, Veronica; Park, Conner; Vong, Susan

    2016-03-01

    The inspiral and merger of binary neutron stars is expected to provide many signals for Advanced LIGO at design sensitivity. The waveform models currently used to search for and parameterize these signals ignore effects near the merger: as the stars coalesce, the gravitational waves depend additionally on the properties of matter in the core of the stars. In this talk, I will discuss potential systematic error from neglecting these features and present phenomenological waveform models currently being developed to capture the dynamics of merging neutron stars.

  11. Transfer reactions with heavy elements

    SciTech Connect

    Hoffman, D.C.

    1986-04-01

    Transfer reactions for several transuranium elements are studied. (/sup 248/Cm, /sup 249/Bk, /sup 249/CF, /sup 254/Es), /sup 16,18/O, /sup 20,22/Ne, and /sup 40,48/Ca projectiles are used. The production of neutron-rich heavy actinides is enhanced by the use of neutron-rich projectiles /sup 18/O and /sup 22/Ne. The maxima of the isotopic distributions occur at only 2 to 3 mass numbers larger for /sup 48/Ca than for /sup 40/Ca reactions with /sup 248/Cm. The cross sections decrease rapidly with the number of nucleons transferred. The use of neutron-rich targets favors the production of neutron-rich isotopes. ''Cold'' heavy targets are produced. Comparisons with simple calculations of the product excitation energies assuming binary transfers indicate that the maxima of the isotopic distributions occur at the lightest product isotope for which the energy exceeds the reaction barrier. The cross sections for transfer of the same nucleon clusters appear to be comparable for a wide variety of systems. 23 refs., 4 figs., 4 tabs.

  12. Neutron range spectrometer

    DOEpatents

    Manglos, Stephen H.

    1989-06-06

    A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are collimnated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated neutron beam. The counter determines positions along the collimation axis of interactions between the neutrons in the neutron beam and a neutron-absorbing material in the counter. From the interaction positions, a computer analyzes the data and determines the neutron energy spectrum of the neutron beam. The counter is preferably shielded and a suitable neutron-absorbing material is He-3. The computer solves the following equation in the analysis: ##EQU1## where: N(x).DELTA.x=the number of neutron interactions measured between a position x and x+.DELTA.x, A.sub.i (E.sub.i).DELTA.E.sub.i =the number of incident neutrons with energy between E.sub.i and E.sub.i +.DELTA.E.sub.i, and C=C(E.sub.i)=N .sigma.(E.sub.i) where N=the number density of absorbing atoms in the position sensitive counter means and .sigma. (E.sub.i)=the average cross section of the absorbing interaction between E.sub.i and E.sub.i +.DELTA.E.sub.i.

  13. Neutron Backgrounds: 13C({alpha}, n) etc

    SciTech Connect

    Mitsui, Tadao

    2005-09-08

    13C({alpha}, n) reaction is the main neutron source in an underground large-volume liquid-scintillator detector KamLAND. {alpha} sources, targets, cross sections, and neutron transport are studied to estimate the backgrounds of v-bare signal.

  14. NEUTRONIC REACTOR

    DOEpatents

    Ohlinger, L.A.; Wigner, E.P.; Weinberg, A.M.; Young, G.J.

    1958-09-01

    This patent relates to neutronic reactors of the heterogeneous water cooled type, and in particular to a fuel element charging and discharging means therefor. In the embodiment illustrated the reactor contains horizontal, parallel coolant tubes in which the fuel elements are disposed. A loading cart containing a magnzine for holding a plurality of fuel elements operates along the face of the reactor at the inlet ends of the coolant tubes. The loading cart is equipped with a ram device for feeding fuel elements from the magazine through the inlot ends of the coolant tubes. Operating along the face adjacent the discharge ends of the tubes there is provided another cart means adapted to receive irradiated fuel elements as they are forced out of the discharge ends of the coolant tubes by the incoming new fuel elements. This cart is equipped with a tank coataining a coolant, such as water, into which the fuel elements fall, and a hydraulically operated plunger to hold the end of the fuel element being discharged. This inveation provides an apparatus whereby the fuel elements may be loaded into the reactor, irradiated therein, and unloaded from the reactor without stopping the fiow of the coolant and without danger to the operating personnel.

  15. Neutron streak camera

    DOEpatents

    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.

  16. Layered semiconductor neutron detectors

    DOEpatents

    Mao, Samuel S; Perry, Dale L

    2013-12-10

    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  17. Neutron streak camera

    DOEpatents

    Wang, C.L.

    1981-05-14

    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.

  18. Neutron streak camera

    DOEpatents

    Wang, C.L.

    1983-09-13

    Disclosed is an 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. 4 figs.

  19. Organic metal neutron detector

    DOEpatents

    Butler, M.A.; Ginley, D.S.

    1984-11-21

    A device for detection of neutrons comprises: as an active neutron sensing element, a conductive organic polymer having an electrical conductivity and a cross-section for said neutrons whereby a detectable change in said conductivity is caused by impingement of said neutrons on the conductive organic polymer which is responsive to a property of said polymer which is altered by impingement of said neutrons on the polymer; and means for associating a change in said alterable property with the presence of neutrons at the location of said device.

  20. Neutronic Reactor Design to Reduce Neutron Loss

    DOEpatents

    Miles, F. T.

    1961-05-01

    A nuclear reactor construction is described in which an unmoderated layer of the fissionable material is inserted between the moderated portion of the reactor core and the core container steel wall. The wall is surrounded by successive layers of pure fertile material and moderator containing fertile material. The unmoderated layer of the fissionable material will insure that a greater portion of fast neutrons will pass through the steel wall than would thermal neutrons. Since the steel has a smaller capture cross section for the fast neutrons, greater nunnbers of neutrons will pass into the blanket, thereby increasing the over-all efficiency of the reactor. (AEC)

  1. NEUTRONIC REACTOR DESIGN TO REDUCE NEUTRON LOSS

    DOEpatents

    Mills, F.T.

    1961-05-01

    A nuclear reactor construction is described in which an unmoderated layer of the fissionable material is inserted between the moderated portion of the reactor core and the core container steel wall which is surrounded by successive layers of pure fertile material and fertile material having moderator. The unmoderated layer of the fissionable material will insure that a greater portion of fast neutrons will pass through the steel wall than would thermal neutrons. As the steel has a smaller capture cross-section for the fast neutrons, then greater numbers of the neutrons will pass into the blanket thereby increasing the over-all efficiency of the reactor.

  2. Improving Neutron Measurement Capabilities; Expanding the Limits of Correlated Neutron Counting

    SciTech Connect

    Santi, Peter Angelo; Geist, William H.; Dougan, Arden

    2015-11-05

    A number of technical and practical limitations exist within the neutron correlated counting techniques used in safeguards, especially within the algorithms that are used to process and analyze the detected neutron signals. A multi-laboratory effort is underway to develop new and improved analysis and data processing algorithms based on fundamental physics principles to extract additional or more accurate information about nuclear material bearing items.

  3. Fission neutron spectra measurements at LANSCE - status and plans

    SciTech Connect

    Haight, Robert C; Noda, Shusaku; Nelson, Ronald O; O' Donnell, John M; Devlin, Matt; Chatillon, Audrey; Granier, Thierry; Taieb, Julien; Laurent, Benoit; Belier, Gilbert; Becker, John A; Wu, Ching - Yen

    2009-01-01

    A program to measure fission neutron spectra from neutron-induced fission of actinides is underway at the Los Alamos Neutron Science Center (LANSCE) in a collaboration among the CEA laboratory at Bruyeres-le-Chatel, Lawrence Livermore National Laboratory and Los Alamos National Laboratory. The spallation source of fast neutrons at LANSCE is used to provide incident neutron energies from less than 1 MeV to 100 MeV or higher. The fission events take place in a gas-ionization fission chamber, and the time of flight from the neutron source to that chamber gives the energy of the incident neutron. Outgoing neutrons are detected by an array of organic liquid scintillator neutron detectors, and their energies are deduced from the time of flight from the fission chamber to the neutron detector. Measurements have been made of the fission neutrons from fission of {sup 235}U, {sup 238}U, {sup 237}Np and {sup 239}Pu. The range of outgoing energies measured so far is from 1 MeV to approximately 8 MeV. These partial spectra and average fission neutron energies are compared with evaluated data and with models of fission neutron emission. Results to date will be presented and a discussion of uncertainties will be given in this presentation. Future plans are to make significant improvements in the fission chambers, neutron detectors, signal processing, data acquisition and the experimental environment to provide high fidelity data including mea urements of fission neutrons below 1 MeV and improvements in the data above 8 MeV.

  4. Fluorescence resonance energy transfer and complex formation between thiazole orange and various dye-DNA conjugates: implications in signaling nucleic acid hybridization.

    PubMed

    Algar, W Russ; Massey, Melissa; Krull, Ulrich J

    2006-07-01

    Fluorescence resonance energy transfer (FRET) was investigated between the intercalating dye thiazole orange (TO), and the dyes Cyanine 3 (Cy3), Cyanine 5 (Cy5), Carboxytetramethyl Rhodamine (TAMRA), Iowa Black FQ (IabFQ), and Iowa Black RQ (IabRQ), which were covalently immobilized at the end of dsDNA oligonucleotides. In addition to determining that TO was an effective energy donor, FRET efficiency data obtained from fluorescence lifetime measurements indicated that TO intercalated near the middle of the 19mer oligonucleotide sequence that was used in this study. Discrepancies in FRET efficiencies obtained from intensity and lifetime measurements led to the investigation of non-fluorescent complex formation between TAMRA and modified TO. The hydrophobicity of TO was modified by the addition of either an alkyl or polyethylene glycol (PEG) side-chain to study effects of dimer and aggregate formation. It was found that at stoichiometric excesses of modified TO, fluorescence quenching of TAMRA was observed, and that this could be correlated to the hydrophobicity of a TO-chain species. The TAMRA:TO-chain association constant for the TO-alkyl system was 0.043+/-0.002 M(-1), while that obtained for the TO-PEG was 0.037+/-0.002 M(-1). From the perspective of method development for the transduction of hybridization events, we present and evaluate a variety of schemes based on energy transfer between TO and an acceptor dye, and discuss the implications of complex formation in such schemes.

  5. Advanced digital detectors for neutron imaging.

    SciTech Connect

    Doty, F. Patrick

    2003-12-01

    Neutron interrogation provides unique information valuable for Nonproliferation & Materials Control and other important applications including medicine, airport security, protein crystallography, and corrosion detection. Neutrons probe deep inside massive objects to detect small defects and chemical composition, even through high atomic number materials such as lead. However, current detectors are bulky gas-filled tubes or scintillator/PM tubes, which severely limit many applications. Therefore this project was undertaken to develop new semiconductor radiation detection materials to develop the first direct digital imaging detectors for neutrons. The approach relied on new discovery and characterization of new solid-state sensor materials which convert neutrons directly to electronic signals via reactions BlO(n,a)Li7 and Li6(n,a)T.

  6. Improved microphysics in neutron star merger simulations

    NASA Astrophysics Data System (ADS)

    Foucart, Francois

    2014-09-01

    Neutron star mergers are expected to be among the main sources of gravitational waves detectable by the Advance LIGO/VIRGO/KAGRA detector network. In many cases, these mergers are also likely to power bright electromagnetic transients, including short gamma-ray bursts and ``kilonovae,'' the optical/infrared emission due to the radioactive decay of neutron rich elements in material unbound by the merger. These EM counterparts can provide important information on the environment in which the merger takes place and the nature of the binary, and their detection could shed a light on the origin of short gamma-ray bursts and of r-process elements. Numerical simulations of neutron star mergers using general relativistic codes are required to understand the merger dynamics, the impact of the equation of state of the neutron star on the gravitational wave signal, and the potential of a given binary to power electromagnetic counterparts to that signal. Until recently, however, general relativistic codes used very simple models for the neutron star - often a simple gamma-law equation of state without any additional microphysics. Although sufficient to model the gravitational wave signal before merger, this cannot be used to follow the post-merger evolution of the system, or even some aspects of the disruption of the neutron star. To do so, nuclear-theory based equations of state with temperature and composition dependence have to be used, and the effects of neutrinos and magnetic fields should be taken into account. In this talk, I will discuss current efforts to include more advanced microphysics in general relativistic simulations, what we can do so far, and what the remaining computational challenges are. I will also show how existing numerical simulations have helped us constrain the outcome of neutron star mergers, and what remains to be done in order to extract as much information as possible from upcoming gravitational wave and electromagnetic observations. Neutron

  7. Neutron anatomy

    SciTech Connect

    Bacon, G.E.

    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.

  8. Fluorescence Resonance Energy Transfer Based on Interaction of PII and PipX Proteins Provides a Robust and Specific Biosensor for 2-Oxoglutarate, a Central Metabolite and a Signaling Molecule.

    PubMed

    Chen, Hai-Lin; Bernard, Christophe S; Hubert, Pierre; My, Laetitia; Zhang, Cheng-Cai

    2013-12-26

    2-Oxoglutarate is a central metabolite and a signalling molecule in both prokaryotes and eukaryotes. The cellular levels of 2-oxoglutarate vary rapidly in response to environmental changes, but an easy and reliable approach is lacking for the measurement of 2-oxoglutarate. Here we report a biosensor of 2-oxoglutarate based on the 2-oxoglutarate-dependent dissociation of the PII-PipX protein complex from cyanobacteria. Fusions of PII and PipX to either CFP or YFP could form a complex and their interaction could be detected by FRET (Fluorescence Resonance Energy Transfer). Mutations in PII or PipX that affect their interaction strongly decrease the FRET signal. Furthermore, the FRET signal is negatively affected, in a specific and concentration-dependent manner, by the presence of 2-oxoglutarate. This 2-oxoglutarate biosensor responds specifically and rapidly to a large range of 2-oxoglutarate levels, and is highly robust under different conditions, including in bacterial cell extracts. We further used this biosensor to study the interaction between PII and its effectors, and our data indicate that excess in Mg(2+) ions is a key factor for PII to respond efficiently to an increase in 2-oxoglutarate levels. This study paves the way for probing the dynamics of 2-oxoglutarate in various organisms and provides a valuable tool for the understanding of the molecular mechanism in metabolic regulation. PMID:24373496

  9. 3D Radiative Transfer Effects in Multi-Angle/Multi-Spectral Radio-Polarimetric Signals from a Mixture of Clouds and Aerosols Viewed by a Non-Imaging Sensor

    NASA Technical Reports Server (NTRS)

    Davis, Anthony B.; Garay, Michael J.; Xu, Feng; Qu, Zheng; Emde, Claudia

    2013-01-01

    When observing a spatially complex mix of aerosols and clouds in a single relatively large field-of-view, nature entangles their signals non-linearly through polarized radiation transport processes that unfold in the 3D position and direction spaces. In contrast, any practical forward model in a retrieval algorithm will use only 1D vector radiative transfer (vRT) in a linear mixing technique. We assess the difference between the observed and predicted signals using synthetic data from a high-fidelity 3D vRT model with clouds generated using a Large Eddy Simulation model and an aerosol climatology. We find that this difference is signal--not noise--for the Aerosol Polarimetry Sensor (APS), an instrument developed by NASA. Moreover, the worst case scenario is also the most interesting case, namely, when the aerosol burden is large, hence hase the most impact on the cloud microphysics and dynamics. Based on our findings, we formulate a mitigation strategy for these unresolved cloud adjacency effects assuming that some spatial information is available about the structure of the clouds at higher resolution from "context" cameras, as was planned for NASA's ill-fated Glory mission that was to carry the APS but failed to reach orbit. Application to POLDER (POLarization and Directionality of Earth Reflectances) data from the period when PARASOL (Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar) was in the A-train is briefly discussed.

  10. Investigation of neutron converters for production of optically stimulated luminescence (OSL) neutron dosimeters using Al 2O 3:C

    NASA Astrophysics Data System (ADS)

    Mittani, J. C. R.; da Silva, A. A. R.; Vanhavere, F.; Akselrod, M. S.; Yukihara, E. G.

    2007-07-01

    This paper presents the optically stimulated luminescence (OSL) properties of neutron dosimeters in powder and in the form of pellets prepared with a mixture of Al 2O 3:C and neutron converters. The neutron converters investigated were high density polyethylene (HDPE), lithium fluoride (LiF), lithium fluoride 95% enriched with 6Li ( 6LiF), lithium carbonate 95% enriched with 6Li ( 6Li 2CO 3), boric acid enriched with 99% of 10B (H310BO) and gadolinium oxide (Gd 2O 3). The proportion of Al 2O 3:C and neutron converter in the mixture was varied to optimize the total OSL signal and neutron sensitivity. The neutron sensitivity and dose-response were determined for the OSL dosimeters using a bare 252Cf source and compared to the response of Harshaw TLD-600 and TLD-700 dosimeters ( 6LiF:Mg,Ti and 7LiF:Mg,Ti). The results demonstrate the possibility of developing an OSL dosimeter made of Al 2O 3:C powder and neutron converter with a neutron sensitivity (defined as the ratio between the 60Co equivalent gamma dose and the reference neutron absorbed dose) and neutron-gamma discrimination comparable to the TLD-600/TLD-700 combination. It was shown that the shape of the OSL decay curves varied with the type of the neutron converter, demonstrating the influence of the energy deposition mechanism and ionization density on the OSL process in Al 2O 3:C.

  11. Dose equivalent neutron dosimeter

    DOEpatents

    Griffith, Richard V.; Hankins, Dale E.; Tomasino, Luigi; Gomaa, Mohamed A. M.

    1983-01-01

    A neutron dosimeter is disclosed which provides a single measurements indicating the amount of potential biological damage resulting from the neutron exposure of the wearer, for a wide range of neutron energies. The dosimeter includes a detecting sheet of track etch detecting material such as a carbonate plastic, for detecting higher energy neutrons, and a radiator layer containing conversion material such as .sup.6 Li and .sup.10 B lying adjacent to the detecting sheet for converting moderate energy neutrons to alpha particles that produce tracks in the adjacent detecting sheet. The density of conversion material in the radiator layer is of an amount which is chosen so that the density of tracks produced in the detecting sheet is proportional to the biological damage done by neutrons, regardless of whether the tracks are produced as the result of moderate energy neutrons striking the radiator layer or as the result of higher energy neutrons striking the sheet of track etch material.

  12. Ultrafast neutron detector

    DOEpatents

    Wang, C.L.

    1985-06-19

    A neutron detector of very high temporal resolution is described. It may be used to measure distributions of neutrons produced by fusion reactions that persist for times as short as about 50 picoseconds.

  13. On neutron surface waves

    SciTech Connect

    Ignatovich, V. K.

    2009-01-15

    It is shown that neutron surface waves do not exist. The difference between the neutron wave mechanics and the wave physics of electromagnetic and acoustic processes, which allows the existence of surface waves, is analyzed.

  14. Neutron dose equivalent meter

    DOEpatents

    Olsher, Richard H.; Hsu, Hsiao-Hua; Casson, William H.; Vasilik, Dennis G.; Kleck, Jeffrey H.; Beverding, Anthony

    1996-01-01

    A neutron dose equivalent detector for measuring neutron dose capable of accurately responding to neutron energies according to published fluence to dose curves. The neutron dose equivalent meter has an inner sphere of polyethylene, with a middle shell overlying the inner sphere, the middle shell comprising RTV.RTM. silicone (organosiloxane) loaded with boron. An outer shell overlies the middle shell and comprises polyethylene loaded with tungsten. The neutron dose equivalent meter defines a channel through the outer shell, the middle shell, and the inner sphere for accepting a neutron counter tube. The outer shell is loaded with tungsten to provide neutron generation, increasing the neutron dose equivalent meter's response sensitivity above 8 MeV.

  15. Pulsed-neutron monochromator

    DOEpatents

    Mook, H.A. Jr.

    1984-01-01

    In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The waves are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

  16. Pulsed-neutron monochromator

    DOEpatents

    Mook, Jr., Herbert A.

    1985-01-01

    In one aspect, the invention is an improved pulsed-neutron monochromator of the vibrated-crystal type. The monochromator is designed to provide neutron pulses which are characterized both by short duration and high density. A row of neutron-reflecting crystals is disposed in a neutron beam to reflect neutrons onto a common target. The crystals in the row define progressively larger neutron-scattering angles and are vibrated sequentially in descending order with respect to the size of their scattering angles, thus generating neutron pulses which arrive simultaneously at the target. Transducers are coupled to one end of the crystals to vibrate them in an essentially non-resonant mode. The transducers propagate transverse waves in the crystal which progress longitudinally therein. The wave are absorbed at the undriven ends of the crystals by damping material mounted thereon. In another aspect, the invention is a method for generating neutron pulses characterized by high intensity and short duration.

  17. ULTRASONIC NEUTRON DOSIMETER

    DOEpatents

    Truell, R.; de Klerk, J.; Levy, P.W.

    1960-02-23

    A neutron dosimeter is described which utilizes ultrasonic waves in the megacycle region for determination of the extent of neutron damage in a borosilicate glass through ultrasonic wave velocity and attenuation measurements before and after damage.

  18. A nuclear localization signal in the matrix of spleen necrosis virus (SNV) does not allow efficient gene transfer into quiescent cells with SNV-derived vectors

    SciTech Connect

    Caron, Marie-Christine; Caruso, Manuel . E-mail: manuel.caruso@crhdq.ulaval.ca

    2005-08-01

    A major limitation in gene therapy for vectors derived from Moloney murine leukemia virus (MLV) is that they only deliver genes into dividing cells. In this study, a careful comparison of spleen necrosis virus (SNV)-derived vectors with MLV and human immunodeficiency virus (HIV)-1 retroviral vectors indicated that SNV vectors can deliver genes 4-fold more efficiently than MLV vectors into aphidicolin-arrested cells, although at a 25-fold lower efficiency than HIV-1-derived vectors. Furthermore, the addition of a NLS in the SNV matrix (MA) that mimics the one located in HIV-1 MA did not increase the ability of SNV vectors to transfer genes into arrested cells. Also, we found that the RD114 envelope was able to pseudotype SNV viral particles in a very efficient manner.

  19. The Signal Transfer from the Receptor NpSRII to the Transducer NpHtrII Is Not Hampered by the D75N Mutation

    PubMed Central

    Holterhues, Julia; Bordignon, Enrica; Klose, Daniel; Rickert, Christian; Klare, Johann P.; Martell, Swetlana; Li, Lin; Engelhard, Martin; Steinhoff, Heinz-Jürgen

    2011-01-01

    Sensory rhodopsin II (NpSRII) is a phototaxis receptor of Natronomonas pharaonis that performs its function in complex with its cognate transducer (NpHtrII). Upon light activation NpSRII triggers by means of NpHtrII a signal transduction chain homologous to the two component system in eubacterial chemotaxis. The D75N mutant of NpSRII, which lacks the blue-shifted M intermediate and therefore exhibits a significantly faster photocycle compared to the wild-type, mediates normal phototaxis responses demonstrating that deprotonation of the Schiff base is not a prerequisite for transducer activation. Using site-directed spin labeling and time resolved electron paramagnetic-resonance spectroscopy, we show that the mechanism revealed for activation of the wild-type complex, namely an outward tilt motion of the cytoplasmic part of the receptor helix F and a concomitant rotation of the transmembrane transducer helix TM2, is also valid for the D75N variant. Apparently, the D75N mutation shifts the ground state conformation of NpSRII-D75N and its cognate transducer into the direction of the signaling state. PMID:21539797

  20. E1(-)E4(+) adenoviral gene transfer vectors function as a "pro-life" signal to promote survival of primary human endothelial cells.

    PubMed

    Ramalingam, R; Rafii, S; Worgall, S; Brough, D E; Crystal, R G

    1999-05-01

    Although endothelial cells are quiescent and long-lived in vivo, when they are removed from blood vessels and cultured in vitro they die within days to weeks. In studies of the interaction of E1(-)E4(+) replication-deficient adenovirus (Ad) vectors and human endothelium, the cells remained quiescent and were viable for prolonged periods. Evaluation of these cultures showed that E1(-)E4(+) Ad vectors provide an "antiapoptotic" signal that, in association with an increase in the ratio of Bcl2 to Bax levels, induces the endothelial cells to enter a state of "suspended animation," remaining viable for at least 30 days, even in the absence of serum and growth factors. Although the mechanisms initiating these events are unclear, the antiapoptoic signal requires the presence of E4 genes in the vector genome, suggesting that one or more E4 open reading frames of subgroup C Ad initiate a "pro-life" program that modifies cultured endothelial cells to survive for prolonged periods.

  1. Intense fusion neutron sources

    NASA Astrophysics Data System (ADS)

    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.

  2. Dibaryons in neutron stars

    NASA Technical Reports Server (NTRS)

    Olinto, Angela V.; Haensel, Pawel; Frieman, Joshua A.

    1991-01-01

    The effects are studied of H-dibaryons on the structure of neutron stars. It was found that H particles could be present in neutron stars for a wide range of dibaryon masses. The appearance of dibaryons softens the equations of state, lowers the maximum neutron star mass, and affects the transport properties of dense matter. The parameter space is constrained for dibaryons by requiring that a 1.44 solar mass neutron star be gravitationally stable.

  3. Neutron angular distribution in plutonium-240 spontaneous fission

    NASA Astrophysics Data System (ADS)

    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.

  4. Arsenic activation neutron detector

    DOEpatents

    Jacobs, E.L.

    1980-01-28

    A detector of bursts of neutrons from a deuterium-deuteron reaction includes a quantity of arsenic adjacent a gamma detector such as a scintillator and photomultiplier tube. The arsenic is activated by the 2.5-MeV neutrons to release gamma radiation which is detected to give a quantitative representation of detected neutrons.

  5. Arsenic activation neutron detector

    DOEpatents

    Jacobs, Eddy L.

    1981-01-01

    A detector of bursts of neutrons from a deuterium-deuteron reaction includes a quantity of arsenic adjacent a gamma detector such as a scintillator and photomultiplier tube. The arsenic is activated by the 2.5 Mev neutrons to release gamma radiation which is detected to give a quantitative representation of detected neutrons.

  6. Perforated diode neutron sensors

    NASA Astrophysics Data System (ADS)

    McNeil, Walter J.

    A novel design of neutron sensor was investigated and developed. The perforated, or micro-structured, diode neutron sensor is a concept that has the potential to enhance neutron sensitivity of a common solid-state sensor configuration. The common thin-film coated diode neutron sensor is the only semiconductor-based neutron sensor that has proven feasible for commercial use. However, the thin-film coating restricts neutron counting efficiency and severely limits the usefulness of the sensor. This research has shown that the perforated design, when properly implemented, can increase the neutron counting efficiency by greater than a factor of 4. Methods developed in this work enable detectors to be fabricated to meet needs such as miniaturization, portability, ruggedness, and adaptability. The new detectors may be used for unique applications such as neutron imaging or the search for special nuclear materials. The research and developments described in the work include the successful fabrication of variant perforated diode neutron detector designs, general explanations of fundamental radiation detector design (with added focus on neutron detection and compactness), as well as descriptive theory and sensor design modeling useful in predicting performance of these unique solid-state radiation sensors. Several aspects in design, fabrication, and operational performance have been considered and tested including neutron counting efficiency, gamma-ray response, perforation shapes and depths, and silicon processing variations. Finally, the successfully proven technology was applied to a 1-dimensional neutron sensor array system.

  7. Advanced neutron absorber materials

    DOEpatents

    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. LGB neutron detector

    NASA Astrophysics Data System (ADS)

    Quist, Nicole

    2012-10-01

    The double pulse signature of the Gadolinium Lithium Borate Cerium doped plastic detector suggests its effectiveness for analyzing neutrons while providing gamma ray insensitivity. To better understand this detector, a californium gamma/neutron time of flight facility was constructed in our lab. Reported here are efforts to understand the properties and applications of the LGB detector with regards to neutron spectroscopy.

  9. Progress in thermal neutron radiography at LENS

    NASA Astrophysics Data System (ADS)

    Jenkins, Jack; Low Energy Neutron Source (LENS) at Indiana University Collaboration

    2014-09-01

    An end station for thermal neutron radiography and tomography is in operation at the Indiana University LENS facility. Neutrons from proton-induced nuclear reactions in Beryllium are moderated and collimated into a beam which is attenuated by a scanned object on a remotely-controlled rotating table. Neutron signal is then converted to a light signal with a ZnS scintillating screen and recorded in a cooled CCD. The author has performed diagnostics on the radiography hardware and software and has tested the system's capabilities by imaging a stack of high density polyethylene cubes with diverse inlet holes and grooves on an 80/20 aluminum base. The resolution of the radiographs are seen to be less than 1mm and 3D rending software is capable of reconstructing the internal structure of the aluminum. An end station for thermal neutron radiography and tomography is in operation at the Indiana University LENS facility. Neutrons from proton-induced nuclear reactions in Beryllium are moderated and collimated into a beam which is attenuated by a scanned object on a remotely-controlled rotating table. Neutron signal is then converted to a light signal with a ZnS scintillating screen and recorded in a cooled CCD. The author has performed diagnostics on the radiography hardware and software and has tested the system's capabilities by imaging a stack of high density polyethylene cubes with diverse inlet holes and grooves on an 80/20 aluminum base. The resolution of the radiographs are seen to be less than 1mm and 3D rending software is capable of reconstructing the internal structure of the aluminum. NSF.

  10. ULXs: Neutron stars versus black holes

    NASA Astrophysics Data System (ADS)

    King, Andrew; Lasota, Jean-Pierre

    2016-05-01

    We consider ultraluminous X-ray systems (ULXs) where the accretor is a neutron star rather than a black hole. We show that the recently discovered example (M82 X-2) fits naturally into the simple picture of ULXs as beamed X-ray sources fed at super-Eddington rates, provided that its magnetic field is weaker (≃1011G) than a new-born X-ray pulsar, as expected if there has been mass gain. Continuing accretion is likely to weaken the field to the point that pulsing stops, and make the system indistinguishable from a ULX containing a black hole. Accordingly we suggest that a significant fraction of all ULXs may actually contain neutron star accretors rather than black holes, reflecting the neutron-star fraction among their X-ray binary progenitors. We emphasize that neutron-star ULXs are likely to have higher apparent luminosities than black hole ULXs for a given mass transfer rate, as their tighter beaming outweighs their lower Eddington luminosities. This further increases the likely proportion of neutron-star accretors among all ULXs. Cygnus X-2 is probably a typical descendant of neutron-star ULXs, which may therefore ultimately end as millisecond pulsar binaries with massive white dwarf companions.

  11. Neutron Capture Cross Sections for Radioactive Nuclei

    NASA Astrophysics Data System (ADS)

    Tonchev, Anton; Bedrossian, Peter; Escher, Jutta; Scielzo, Nicholas

    2015-10-01

    Accurate neutron-capture cross sections for radioactive nuclei near or far away from the line of beta stability are crucial for understanding the nucleosynthesis of heavy elements. However, neutron-capture cross sections for short-lived radionuclides are difficult to measure due to the fact that the measurements require both highly radioactive samples and intense neutron sources. Essential ingredients for describing the γ decays following neutron capture are the γ-ray strength function and level densities. We will compare different indirect approaches for obtaining observables that can constrain Hauser-Feshbach statistical model calculations of capture cross sections. Specifically, we will consider photon scattering, transfer reactions, and beta-delayed neutron emission. Challenges that exist on the path to obtaining neutron-capture cross sections for reactions on isotopes far from stability will be discussed. This work was performed under the auspices of US DOE by LLNL under contract DE-AC52-07NA27344. Funding was provided via the LDRD-ERD-069 project.

  12. The SOS Response Master Regulator LexA Regulates the Gene Transfer Agent of Rhodobacter capsulatus and Represses Transcription of the Signal Transduction Protein CckA

    PubMed Central

    Kuchinski, Kevin S.; Brimacombe, Cedric A.; Westbye, Alexander B.; Ding, Hao

    2016-01-01

    ABSTRACT The gene transfer agent of Rhodobacter capsulatus (RcGTA) is a genetic exchange element that combines central aspects of bacteriophage-mediated transduction and natural transformation. RcGTA particles resemble a small double-stranded DNA bacteriophage, package random ∼4-kb fragments of the producing cell genome, and are released from a subpopulation (<1%) of cells in a stationary-phase culture. RcGTA particles deliver this DNA to surrounding R. capsulatus cells, and the DNA is integrated into the recipient genome though a process that requires homologs of natural transformation genes and RecA-mediated homologous recombination. Here, we report the identification of the LexA repressor, the master regulator of the SOS response in many bacteria, as a regulator of RcGTA activity. Deletion of the lexA gene resulted in the abolition of detectable RcGTA production and an ∼10-fold reduction in recipient capability. A search for SOS box sequences in the R. capsulatus genome sequence identified a number of putative binding sites located 5′ of typical SOS response coding sequences and also 5′ of the RcGTA regulatory gene cckA, which encodes a hybrid histidine kinase homolog. Expression of cckA was increased >5-fold in the lexA mutant, and a lexA cckA double mutant was found to have the same phenotype as a ΔcckA single mutant in terms of RcGTA production. The data indicate that LexA is required for RcGTA production and maximal recipient capability and that the RcGTA-deficient phenotype of the lexA mutant is largely due to the overexpression of cckA. IMPORTANCE This work describes an unusual phenotype of a lexA mutant of the alphaproteobacterium Rhodobacter capsulatus in respect to the phage transduction-like genetic exchange carried out by the R. capsulatus gene transfer agent (RcGTA). Instead of the expected SOS response characteristic of prophage induction, this lexA mutation not only abolishes the production of RcGTA particles but also impairs the ability

  13. Review of current neutron detection systems for emergency response

    SciTech Connect

    Mukhopadhyay, Sanjoy; Maurer, Richard; Guss, Paul; Kruschwitz, Craig

    2014-09-05

    Neutron detectors are utilized in a myriad of applications—from safeguarding special nuclear materials (SNM) to determining lattice spacing in soft materials. The transformational changes taking place in neutron detection and imaging techniques in the last few years are largely being driven by the global shortage of helium-3 (3He). This article reviews the status of neutron sensors used specifically for SNM detection in radiological emergency response. These neutron detectors must be highly efficient, be rugged, have fast electronics to measure neutron multiplicity, and be capable of measuring direction of the neutron sources and possibly image them with high spatial resolution. Neutron detection is an indirect physical process: neutrons react with nuclei in materials to initiate the release of one or more charged particles that produce electric signals that can be processed by the detection system. Therefore, neutron detection requires conversion materials as active elements of the detection system; these materials may include boron-10 (10B), lithium-6 (6Li), and gadollinium-157 (157Gd), to name a few, but the number of materials available for neutron detection is limited. However, in recent years, pulse-shape-discriminating plastic scintillators, scintillators made of helium-4 (4He) under high pressure, pillar and trench semiconductor diodes, and exotic semiconductor neutron detectors made from uranium oxide and other materials have widely expanded the parameter space in neutron detection methodology. In this article we will pay special attention to semiconductor-based neutron sensors. Finally, modern microfabricated nanotubes covered inside with neutron converter materials and with very high aspect ratios for better charge transport will be discussed.

  14. Gamma-Free Neutron Detector Based upon Lithium Phosphate Nanoparticles

    SciTech Connect

    Steven Wallace

    2007-08-28

    A gamma-free neutron-sensitive scintillator is needed to enhance radiaition sensing and detection for nonproliferation applications. Such a scintillator would allow very large detectors to be placed at the perimeter of spent-fuel storage facilities at commercial nuclear power plants, so that any movement of spontaneously emitted neutrons from spent nuclear fuel or weapons grade plutonium would be noted in real-time. This task is to demonstrate that the technology for manufacturing large panels of fluor-doped plastic containing lithium-6 phosphate nanoparticles can be achieved. In order to detect neutrons, the nanoparticles must be sufficiently small so that the plastic remains transparent. In this way, the triton and alpha particles generated by the capture of the neutron will result in a photon burst that can be coupled to a wavelength shifting fiber (WLS) producing an optical signal of about ten nanoseconds duration signaling the presence of a neutron emitting source.

  15. Development of multichannel low-energy neutron spectrometer

    SciTech Connect

    Arikawa, Y. Nagai, T.; Abe, Y.; Kojima, S.; Sakata, S.; Inoue, H.; Utsugi, M.; Iwasa, Y.; Sarukura, N.; Nakai, M.; Shiraga, H.; Fujioka, S.; Azechi, H.; Murata, T.

    2014-11-15

    A multichannel low-energy neutron spectrometer for down-scattered neutron (DSN) measurements in inertial confinement fusion (ICF) experiments has been developed. Our compact-size 256-channel lithium-glass-scintillator-based spectrometer has been implemented and tested in ICF experiments with the GEKKO XII laser. We have performed time calibration of the 256-channel analog-to-digital convertor system used for DSN measurements via X-ray pulse signals. We have clearly observed the DD-primary fusion neutron signal and have successfully studied the detector's impulse response. Our detector is soon to be implemented in future ICF experiments.

  16. Photon and fast neutron dosimetry using aluminium oxide thermoluminescence dosemeters.

    PubMed

    Santos, J P; Fernandes, A C; Gonçalves, I C; Marques, J G; Carvalho, A F; Santos, L; Cardoso, J; Osvay, M

    2006-01-01

    Al(2)O(3):Mg,Y thermoluminescence (TL) dosemeters were used to measure photon and fast neutron doses in a fast neutron beam recently implemented at the Portuguese Research Reactor, Nuclear and Technological Institute, Portugal. The activation of Al(2)O(3):Mg,Y by fast neutrons provides information about the fast neutron component by measuring the activity of the reaction products and the self-induced TL signal. Additionally, the first TL reading after irradiation determines the photon dose. The elemental composition of the dosemeters was determined by instrumental neutron activation analysis and by particle induced X-ray emission. Results demonstrate that Al(2)O(3):Mg,Y is an adequate material to discriminate photon and fast neutron fields for reactor dosimetry purposes.

  17. Global Maps of Lunar Neutron Fluxes from the LEND Instrument

    NASA Technical Reports Server (NTRS)

    Litvak, M. L.; Mitrofanov, I. G.; Sanin, A.; Malakhov, A.; Boynton, W. V.; Chin, G.; Droege, G.; Evans, L. G.; Garvin, J.; Golovin, D. V.; Harshman, K.; McClanahan, T. P.; Mokrousov, M. I.; Mazarico, E.; Milikh, G.; Neumann, G.; Sagdeev, R.; Smith, D. E.; Starr, R.; Zuber, M. T.

    2012-01-01

    The latest neutron spectrometer measurements with the Lunar Exploration Neutron Detector (LEND) onboard the Lunar Reconnaissance Orbiter (LRO) are presented. It covers more than 1 year of mapping phase starting on 15 September 2009. In our analyses we have created global maps showing regional variations in the flux of thermal (energy range < 0.015 eV) and fast neutrons (>0.5 MeV), and compared these fluxes to variances in soil elemental composition, and with previous results obtained by the Lunar Prospector Neutron Spectrometer (LPNS). We also processed data from LEND collimated detectors and derived a value for the collimated signal of epithermal neutrons based on the comparative analysis with the LEND omnidirectional detectors. Finally, we have compared our final (after the data reduction) global epithermal neutron map with LPNS data.

  18. Neutron detection using boron gallium nitride semiconductor material

    SciTech Connect

    Atsumi, Katsuhiro; Inoue, Yoku; Nakano, Takayuki; Mimura, Hidenori; Aoki, Toru

    2014-03-01

    In this study, we developed a new neutron-detection device using a boron gallium nitride (BGaN) semiconductor in which the B atom acts as a neutron converter. BGaN and gallium nitride (GaN) samples were grown by metal organic vapor phase epitaxy, and their radiation detection properties were evaluated. GaN exhibited good sensitivity to α-rays but poor sensitivity to γ-rays. Moreover, we confirmed that electrons were generated in the depletion layer under neutron irradiation. This resulted in a neutron-detection signal after α-rays were generated by the capture of neutrons by the B atoms. These results prove that BGaN is useful as a neutron-detecting semiconductor material.

  19. Characteristic evaluation of a Lithium-6 loaded neutron coincidence spectrometer.

    PubMed

    Hayashi, M; Kaku, D; Watanabe, Y; Sagara, K

    2007-01-01

    Characteristics of a (6)Li-loaded neutron coincidence spectrometer were investigated from both measurements and Monte Carlo simulations. The spectrometer consists of three (6)Li-glass scintillators embedded in a liquid organic scintillator BC-501A, which can detect selectively neutrons that deposit the total energy in the BC-501A using a coincidence signal generated from the capture event of thermalised neutrons in the (6)Li-glass scintillators. The relative efficiency and the energy response were measured using 4.7, 7.2 and 9.0 MeV monoenergetic neutrons. The measured ones were compared with the Monte Carlo calculations performed by combining the neutron transport code PHITS and the scintillator response calculation code SCINFUL. The experimental light output spectra were in good agreement with the calculated ones in shape. The energy dependence of the detection efficiency was reproduced by the calculation. The response matrices for 1-10 MeV neutrons were finally obtained.

  20. Dosimetry Methods of Fast Neutron Using the Semiconductor Diodes

    NASA Astrophysics Data System (ADS)

    H. Zaki, Dizaji; Kakavand, T.; F. Abbasi, Davani

    2014-01-01

    Semiconductor detectors based on a silicon pin diode are frequently used in the detection of different nuclear radiations. For the detection and dosimetry of fast neutrons, these silicon detectors are coupled with a fast neutron converter. Incident neutrons interact with the converter and produce charged particles that can deposit their energy in the detectors and produce a signal. In this study, three methods are introduced for fast neutron dosimetry by using the silicon detectors, which are: recoil proton spectroscopy, similarity of detector response function with conversion function, and a discriminator layer. Monte Carlo simulation is used to calculate the response of dosimetry systems based on these methods. In the different doses of an 241Am-Be neutron source, dosimetry responses are evaluated. The error values of measured data for dosimetry by these methods are in the range of 15-25%. We find fairly good agreement in the 241Am-Be neutron sources.

  1. PERSONNEL NEUTRON DOSIMETER

    DOEpatents

    Fitzgerald, J.J.; Detwiler, C.G. Jr.

    1960-05-24

    A description is given of a personnel neutron dosimeter capable of indicating the complete spectrum of the neutron dose received as well as the dose for each neutron energy range therein. The device consists of three sets of indium foils supported in an aluminum case. The first set consists of three foils of indium, the second set consists of a similar set of indium foils sandwiched between layers of cadmium, whereas the third set is similar to the second set but is sandwiched between layers of polyethylene. By analysis of all the foils the neutron spectrum and the total dose from neutrons of all energy levels can be ascertained.

  2. Organic metal neutron detector

    DOEpatents

    Butler, Michael A.; Ginley, David S.

    1987-01-01

    A device for detecting neutrons comprises a layer of conductive polymer sandwiched between electrodes, which may be covered on each face with a neutron transmissive insulating material layer. Conventional electrodes are used for a non-imaging integrating total neutron fluence-measuring embodiment, while wire grids are used in an imaging version of the device. The change in conductivity of the polymer after exposure to a neutron flux is determined in either case to provide the desired data. Alternatively, the exposed conductive polymer layer may be treated with a chemical reagent which selectively binds to the sites altered by neutrons to produce an image of the flux detected.

  3. Grazing incidence neutron optics

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    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.

  4. Grazing Incidence Neutron Optics

    NASA Technical Reports Server (NTRS)

    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.

  5. Neutron activation analysis system

    DOEpatents

    Taylor, M.C.; Rhodes, J.R.

    1973-12-25

    A neutron activation analysis system for monitoring a generally fluid media, such as slurries, solutions, and fluidized powders, including two separate conduit loops for circulating fluid samples within the range of radiation sources and detectors is described. Associated with the first loop is a neutron source that emits s high flux of slow and thermal neutrons. The second loop employs a fast neutron source, the flux from which is substantially free of thermal neutrons. Adjacent to both loops are gamma counters for spectrographic determination of the fluid constituents. Other gsmma sources and detectors are arranged across a portion of each loop for deterMining the fluid density. (Official Gazette)

  6. Can neutron stars have auroras ? : electromagnetic coupling process between neutron star and magnetized accretion disk

    NASA Astrophysics Data System (ADS)

    Kimura, T.; Iwakiri, W. B.; Enoto, T.; Wada, T.; Tao, C.

    2015-12-01

    In the binary neutron star system, angular momentum transfer from accretion disk to a star is essential process for spin-up/down of stars. The angular momentum transfer has been well formulated for the accretion disk strongly magnetized by the neutron star [e.g., Ghosh and Lamb, 1978, 1979a, b]. However, the electromagnetic (EM) coupling between the neutron star and accretion disk has not been self-consistently solved in the previous studies although the magnetic field lines from the star are strongly tied with the accretion disk. In this study, we applied the planet-magnetosphere coupling process established for Jupiter [Hill, 1979] to the binary neutron star system. Angular momentum distribution is solved based on the torque balance between the neutron star's surface and accretion disk coupled by the magnetic field tensions. We found the EM coupling can transfer significantly larger fraction of the angular momentum from the magnetized accretion disk to the star than the unmagnetized case. The resultant spin-up rate is estimated to ~10^-14 [sec/sec] for the nominal binary system parameters, which is comparable with or larger than the other common spin-down/up processes: e.g., the magnetic dipole radiation spin-down. The Joule heating energy dissipated in the EM coupling is estimated to be up to ~10^36 [erg/sec] for the nominal binary system parameters. The release is comparable to that of gravitation energy directly caused by the matters accreting onto the neutron star. This suggests the EM coupling at the neutron star can accompany the observable radiation as auroras with a similar manner to those at the rotating planetary magnetospheres like Jupiter, Saturn, and other gas giants.

  7. Neutron Scattering Studies of Fluorite Compounds.

    NASA Astrophysics Data System (ADS)

    Hackett, Michael Andrew

    Available from UMI in association with The British Library. Requires signed TDF. The properties of some important compounds with the fluorite structure have been investigated using neutron scattering techniques. All of the compounds in this study have important technological applications, as well as being of intrinsic scientific interest. Inelastic neutron scattering and high temperature technology have been used to measure phonon energies in thorium dioxide at temperatures above 3000K. These phonon energies have been used to determine the elastic constants as a function of temperature. Thorium dioxide provides an interesting comparison with uranium dioxide which has been studied in order to try and establish the cause of the anomalously large enthalpy of this compound. Quasielastic neutron scattering has been used to demonstrate that the dynamic ionic-disorder which occurs in ThO_2 behaves in a similar way to that observed in UO _2 at high temperature. Whilst at only 12K, splittings have been measured in the crystal field excitations of UO_2 which have a significant effect on the theoretical analysis of its thermodynamic properties. This experiment was performed using neutrons scattered with a high energy transfer. Elastic and quasielastic diffuse scattering have both been used to investigate the vacancy-stabilised cubic structure of yttria doped zirconia. Computer modelling of the measured neutron scattering intensities has played a vital role in this part of the study. By the combination of neutron scattering measurements and computational techniques a three part model has been developed for the defect structure in yttria-stabilised zirconia which can explain the ionic conductivity in this compound. Ionic disorder has been observed in the anti-fluorite compounds lithium oxide and magnesium silicide at high temperature, using diffuse quasielastic neutron scattering. The full phonon energy dispersion relation and the elastic constants at high temperature have also

  8. Sensitivity enhancement of the central-transition signal of half-integer spin quadrupolar nuclei in solid-state NMR: Features of multiple fast amplitude-modulated pulse transfer

    NASA Astrophysics Data System (ADS)

    Goswami, Mithun; Madhu, P. K.

    2008-06-01

    Sensitivity enhancement of solid-state NMR spectrum of half-integer spin quadrupolar nuclei under both magic-angle spinning (MAS) and static cases has been demonstrated by transferring polarisation associated with satellite transitions to the central m = -1/2 → 1/2 transition with suitably modulated radio-frequency pulse schemes. It has been shown that after the application of such enhancement schemes, there still remains polarisation in the satellite transitions that can be transferred to the central transition. This polarisation is available without having to wait for the spin system to return to thermal equilibrium. We demonstrate here the additional sensitivity enhancement obtained by making use of this remaining polarisation with fast amplitude-modulated (FAM) pulse schemes under both MAS and static conditions on a spin-3/2 and a spin-5/2 system. Considerable signal enhancement is obtained with the application of the multiple FAM sequence, denoted as m-FAM. We also report here some of the salient features of these multiple FAM sequences with respect to the nutation frequency of the pulses and the spinning frequency.

  9. NEUTRON DENSITY CONTROL IN A NEUTRONIC REACTOR

    DOEpatents

    Young, G.J.

    1959-06-30

    The method and means for controlling the neutron density in a nuclear reactor is described. It describes the method and means for flattening the neutron density distribution curve across the reactor by spacing the absorbing control members to varying depths in the central region closer to the center than to the periphery of the active portion of the reactor to provide a smaller neutron reproduction ratio in the region wherein the members are inserted, than in the remainder of the reactor thereby increasing the over-all potential power output.

  10. Ion Acceleration in Solar Flares Determined by Solar Neutron Observations

    NASA Astrophysics Data System (ADS)

    Watanabe, K.; Solar Neutron Observation Group

    2013-05-01

    Large amounts of particles can be accelerated to relativistic energy in association with solar flares and/or accompanying phenomena (e.g., CME-driven shocks), and they sometimes reach very near the Earth and penetrate the Earth's atmosphere. These particles are observed by ground-based detectors (e.g., neutron monitors) as Ground Level Enhancements (GLEs). Some of the GLEs originate from high energy solar neutrons which are produced in association with solar flares. These neutrons are also observed by ground-based neutron monitors and solar neutron telescopes. Recently, some of the solar neutron detectors have also been operating in space. By observing these solar neutrons, we can obtain information about ion acceleration in solar flares. Such neutrons were observed in association with some X-class flares in solar cycle 23, and sometimes they were observed by two different types of detectors. For example, on 2005 September 7, large solar neutron signals were observed by the neutron monitor at Mt. Chacaltaya in Bolivia and Mexico City, and by the solar neutron telescopes at Chacaltaya and Mt. Sierra Negra in Mexico in association with an X17.0 flare. The neutron signal continued for more than 20 minutes with high statistical significance. Intense gamma-ray emission was also registered by INTEGRAL, and by RHESSI during the decay phase. We analyzed these data using the solar-flare magnetic-loop transport and interaction model of Hua et al. (2002), and found that the model could successfully fit the data with intermediate values of loop magnetic convergence and pitch angle scattering parameters. These results indicate that solar neutrons were produced at the same time as the gamma-ray line emission and that ions were continuously accelerated at the emission site. In this paper, we introduce some of the solar neutron observations in solar cycle 23, and discuss the tendencies of the physical parameters of solar neutron GLEs, and the energy spectrum and population of the

  11. New opportunities for quasielastic and inelastic neutron scattering at steady-state sources using mechanical selection of the incident and final neutron energy

    DOE PAGESBeta

    Mamantov, Eugene

    2015-06-12

    We propose a modification of the neutron wide-angle velocity selector (WAVES) device that enables inelastic (in particular, quasielastic) scattering measurements not relying on the neutron time-of-flight. The proposed device is highly suitable for a steady-state neutron source, somewhat similar to a triple-axis spectrometer, but with simultaneous selection of the incident and final neutron energy over a broad range of scattering momentum transfer. Both the incident and final neutron velocities are defined by the WAVES geometry and rotation frequency. The variable energy transfer is achieved through the natural variation of the velocity of the transmitted neutrons as a function of themore » scattering angle component out of the equatorial plane.« less

  12. New opportunities for quasielastic and inelastic neutron scattering at steady-state sources using mechanical selection of the incident and final neutron energy

    SciTech Connect

    Mamantov, Eugene

    2015-06-12

    We propose a modification of the neutron wide-angle velocity selector (WAVES) device that enables inelastic (in particular, quasielastic) scattering measurements not relying on the neutron time-of-flight. The proposed device is highly suitable for a steady-state neutron source, somewhat similar to a triple-axis spectrometer, but with simultaneous selection of the incident and final neutron energy over a broad range of scattering momentum transfer. Both the incident and final neutron velocities are defined by the WAVES geometry and rotation frequency. The variable energy transfer is achieved through the natural variation of the velocity of the transmitted neutrons as a function of the scattering angle component out of the equatorial plane.

  13. Los Alamos Neutron Science Center (LANSCE) accelerator timing system upgrade

    SciTech Connect

    Rybarcyk, L.J.; Shelley, F.E. Jr.

    1997-10-01

    The Los Alamos Neutron Science Center (LANSCE) 800 MeV proton linear accelerator (linac) operates at a maximum repetition rate of twice the AC power line frequency, i.e. 120 Hz. The start of each machine cycle occurs a fixed delay after each zero-crossing of the AC line voltage. Fluctuations in the AC line frequency and phase are therefore present on all linac timing signals. Proper beam acceleration along the linac requires that the timing signals remain well synchronized to the AC line. For neutron chopper spectrometers, e.g., PHAROS at the Manuel Lujan Jr. Neutron Scattering Center, accurate neutron energy selection requires that precise synchronization be maintained between the beam-on-target arrival time and the neutron chopper rotor position. This is most easily accomplished when the chopper is synchronized to a stable, fixed frequency signal. A new zero-crossing circuit which employs a Phase-Locked Loop (PLL) has been developed to increase the phase and frequency stability of the linac timing signals and thereby improve neutron chopper performance while simultaneously maintaining proper linac operation. Results of timing signal data analysis and modeling and a description of the PLL circuit are presented.

  14. Neutron-Proton Asymmetry Dependence of Spectroscopic Factors in Ar Isotopes

    SciTech Connect

    Lee, Jenny; Tsang, Betty; Shapira, Dan

    2010-01-01

    Spectroscopic factors have been extracted for proton-rich 34Ar and neutron-rich 46Ar using the (p, d) neutron transfer reaction. The experimental results show little reduction of the ground state neutron spectroscopic factor of the proton-rich nucleus 34Ar compared to that of 46Ar. The results suggest that correlations, which generally reduce such spectroscopic factors, do not depend strongly on the neutron-proton asymmetry of the nucleus in this isotopic region as was reported in knockout reactions. The present results are consistent with results from systematic studies of transfer reactions but inconsistent with the trends observed in knockout reaction measurements.

  15. Dual-fission chamber and neutron beam characterization for fission product yield measurements using monoenergetic neutrons

    NASA Astrophysics Data System (ADS)

    Bhatia, C.; Fallin, B.; Gooden, M. E.; Howell, C. R.; Kelley, J. H.; Tornow, W.; Arnold, C. W.; Bond, E. M.; Bredeweg, T. A.; Fowler, M. M.; Moody, W. A.; Rundberg, R. S.; Rusev, G.; Vieira, D. J.; Wilhelmy, J. B.; Becker, J. A.; Macri, R.; Ryan, C.; Sheets, S. A.; Stoyer, M. A.; Tonchev, A. P.

    2014-09-01

    A program has been initiated to measure the energy dependence of selected high-yield fission products used in the analysis of nuclear test data. We present out initial work of neutron activation using a dual-fission chamber with quasi-monoenergetic neutrons and gamma-counting method. Quasi-monoenergetic neutrons of energies from 0.5 to 15 MeV using the TUNL 10 MV FM tandem to provide high-precision and self-consistent measurements of fission product yields (FPY). The final FPY results will be coupled with theoretical analysis to provide a more fundamental understanding of the fission process. To accomplish this goal, we have developed and tested a set of dual-fission ionization chambers to provide an accurate determination of the number of fissions occurring in a thick target located in the middle plane of the chamber assembly. Details of the fission chamber and its performance are presented along with neutron beam production and characterization. Also presented are studies on the background issues associated with room-return and off-energy neutron production. We show that the off-energy neutron contribution can be significant, but correctable, while room-return neutron background levels contribute less than <1% to the fission signal.

  16. Dynamically polarized samples for neutron protein crystallography at the Spallation Neutron Source

    NASA Astrophysics Data System (ADS)

    Zhao, Jinkui; Pierce, Josh; Myles, Dean; Robertson, J. L.; Herwig, Kenneth W.; Standaert, Bob; Cuneo, Matt; Li, Le; Meilleur, Flora

    2016-09-01

    To prepare for the next generation neutron scattering instruments for the planned second target station at the Spallation Neutron Source (SNS) and to broaden the scientific impact of neutron protein crystallography at the Oak Ridge National Laboratory, we have recently ramped up our efforts to develop a dynamically polarized target for neutron protein crystallography at the SNS. Proteins contain a large amount of hydrogen which contributes to incoherent diffraction background and limits the sensitivity of neutron protein crystallography. This incoherent background can be suppressed by using polarized neutron diffraction, which in the same time also improves the coherent diffraction signal. Our plan is to develop a custom Dynamic Nuclear Polarization (DNP) setup tailored to neutron protein diffraction instruments. Protein crystals will be polarized at a magnetic field of 5 T and temperatures of below 1 K. After the dynamic polarization process, the sample will be brought to a frozen-spin mode in a 0.5 T holding field and at temperatures below 100 mK. In a parallel effort, we are also investigating various ways of incorporating polarization agents needed for DNP, such as site specific spin labels, into protein crystals.

  17. Jets from Merging Neutron Stars

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-06-01

    With the recent discovery of gravitational waves from the merger of two black holes, its especially important to understand the electromagnetic signals resulting from mergers of compact objects. New simulations successfully follow a merger of two neutron stars that produces a short burst of energy via a jet consistent with short gamma-ray burst (sGRB) detections.Still from the authors simulation showing the two neutron stars, and their magnetic fields, before merger. [Adapted from Ruiz et al. 2016]Challenging SystemWe have long suspected that sGRBs are produced by the mergers of compact objects, but this model has been difficult to prove. One major hitch is that modeling the process of merger and sGRB launch is very difficult, due to the fact that these extreme systems involve magnetic fields, fluids and full general relativity.Traditionally, simulations are only able to track such mergers over short periods of time. But in a recent study, Milton Ruiz (University of Illinois at Urbana-Champaign and Industrial University of Santander, Colombia) and coauthors Ryan Lang, Vasileios Paschalidis and Stuart Shapiro have modeled a binary neutron star system all the way through the process of inspiral, merger, and the launch of a jet.A Merger TimelineHow does this happen? Lets walk through one of the teams simulations, in which dipole magnetic field lines thread through the interior of each neutron star and extend beyond its surface(like magnetic fields found in pulsars). In this example, the two neutron stars each have a mass of 1.625 solar masses.Simulation start (0 ms)Loss of energy via gravitational waves cause the neutron stars to inspiral.Merger (3.5 ms)The neutron stars are stretched by tidal effects and make contact. Their merger produces a hypermassive neutron star that is supported against collapse by its differential (nonuniform) rotation.Delayed collapse into a black hole (21.5 ms)Once the differential rotation is redistributed by magnetic fields and partially

  18. Jets from Merging Neutron Stars

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-06-01

    With the recent discovery of gravitational waves from the merger of two black holes, its especially important to understand the electromagnetic signals resulting from mergers of compact objects. New simulations successfully follow a merger of two neutron stars that produces a short burst of energy via a jet consistent with short gamma-ray burst (sGRB) detections.Still from the authors simulation showing the two neutron stars, and their magnetic fields, before merger. [Adapted from Ruiz et al. 2016]Challenging SystemWe have long suspected that sGRBs are produced by the mergers of compact objects, but this model has been difficult to prove. One major hitch is that modeling the process of merger and sGRB launch is very difficult, due to the fact that these extreme systems involve magnetic fields, fluids and full general relativity.Traditionally, simulations are only able to track such mergers over short periods of time. But in a recent study, Milton Ruiz (University of Illinois at Urbana-Champaign and Industrial University of Santander, Colombia) and coauthors Ryan Lang, Vasileios Paschalidis and Stuart Shapiro have modeled a binary neutron star system all the way through the process of inspiral, merger, and the launch of a jet.A Merger TimelineHow does this happen? Lets walk through one of the teams simulations, in which dipole magnetic field lines thread through the interior of each neutron star and extend beyond its surface(like magnetic fields found in pulsars). In this example, the two neutron stars each have a mass of 1.625 solar masses.Simulation start (0 ms)Loss of energy via gravitational waves cause the neutron stars to inspiral.Merger (3.5 ms)The neutron stars are stretched by tidal effects and make contact. Their merger produces a hypermassive neutron star that is supported against collapse by its differential (nonuniform) rotation.Delayed collapse into a black hole (21.5 ms)Once the differential rotation is redistributed by magnetic fields and partially

  19. Review of current neutron detection systems for emergency response

    DOE PAGESBeta

    Mukhopadhyay, Sanjoy; Maurer, Richard; Guss, Paul; Kruschwitz, Craig

    2014-09-05

    Neutron detectors are utilized in a myriad of applications—from safeguarding special nuclear materials (SNM) to determining lattice spacing in soft materials. The transformational changes taking place in neutron detection and imaging techniques in the last few years are largely being driven by the global shortage of helium-3 (3He). This article reviews the status of neutron sensors used specifically for SNM detection in radiological emergency response. These neutron detectors must be highly efficient, be rugged, have fast electronics to measure neutron multiplicity, and be capable of measuring direction of the neutron sources and possibly image them with high spatial resolution. Neutronmore » detection is an indirect physical process: neutrons react with nuclei in materials to initiate the release of one or more charged particles that produce electric signals that can be processed by the detection system. Therefore, neutron detection requires conversion materials as active elements of the detection system; these materials may include boron-10 (10B), lithium-6 (6Li), and gadollinium-157 (157Gd), to name a few, but the number of materials available for neutron detection is limited. However, in recent years, pulse-shape-discriminating plastic scintillators, scintillators made of helium-4 (4He) under high pressure, pillar and trench semiconductor diodes, and exotic semiconductor neutron detectors made from uranium oxide and other materials have widely expanded the parameter space in neutron detection methodology. In this article we will pay special attention to semiconductor-based neutron sensors. Finally, modern microfabricated nanotubes covered inside with neutron converter materials and with very high aspect ratios for better charge transport will be discussed.« less

  20. Simulation of response functions of fast neutron sensors and development of thin neutron silicon sensor.

    PubMed

    Takada, Masashi; Nakamura, Takashi; Matsuda, Mikihiko; Nunomiya, Tomoya

    2014-10-01

    On radiation detection using silicon sensor, signals are produced from collected charges in a depletion layer; however, for high-energy particles, this depletion layer is extended due to funnelling phenomenon. The lengths of charge collection were experimentally obtained from proton peak energies in measured pulse-heights. The length is extended with increasing proton energy of up to 6 MeV, and then, is constant over 6 MeV. The response functions of fast neutron sensors were simulated for 5- and 15-MeV monoenergetic and (252)Cf neutron sources using the Monte Carlo N-Particle eXtended code. The simulation results agree well with the experimental ones, including the effect of funnelling phenomenon. In addition, a thin silicon sensor was developed for a new real-time personal neutron dosemeter. Photon sensitivity is vanishingly smaller than neutron one by a factor of 5×10(-4). PMID:24516186

  1. Simulation of response functions of fast neutron sensors and development of thin neutron silicon sensor.

    PubMed

    Takada, Masashi; Nakamura, Takashi; Matsuda, Mikihiko; Nunomiya, Tomoya

    2014-10-01

    On radiation detection using silicon sensor, signals are produced from collected charges in a depletion layer; however, for high-energy particles, this depletion layer is extended due to funnelling phenomenon. The lengths of charge collection were experimentally obtained from proton peak energies in measured pulse-heights. The length is extended with increasing proton energy of up to 6 MeV, and then, is constant over 6 MeV. The response functions of fast neutron sensors were simulated for 5- and 15-MeV monoenergetic and (252)Cf neutron sources using the Monte Carlo N-Particle eXtended code. The simulation results agree well with the experimental ones, including the effect of funnelling phenomenon. In addition, a thin silicon sensor was developed for a new real-time personal neutron dosemeter. Photon sensitivity is vanishingly smaller than neutron one by a factor of 5×10(-4).

  2. Neutron chopper development at LANSCE

    SciTech Connect

    Nutter, M.; Lewis, L.; Tepper, S.; Silver, R.N.; Heffner, R.H.

    1985-01-01

    Progress is reported on neutron chopper systems for the Los Alamos Neutron Scattering Center pulsed spallation neutron source. This includes the development of 600+ Hz active magnetic bearing neutron chopper and a high speed control system designed to operate with the Proton Storage Ring to phase the chopper to the neutron source. 5 refs., 3 figs.

  3. Neutron metrology laboratory facility simulation.

    PubMed

    Pereira, Mariana; Salgado, Ana P; Filho, Aidano S; Pereira, Walsan W; Patrão, Karla C S; Fonseca, Evaldo S

    2014-10-01

    The Neutron Low Scattering Laboratory in Brazil has been completely rebuilt. Evaluation of air attenuation parameters and neutron component scattering in the room was done using Monte Carlo simulation code. Neutron fields produced by referenced neutron source were used to calculate neutron scattering and air attenuation.

  4. Neutron metrology laboratory facility simulation.

    PubMed

    Pereira, Mariana; Salgado, Ana P; Filho, Aidano S; Pereira, Walsan W; Patrão, Karla C S; Fonseca, Evaldo S

    2014-10-01

    The Neutron Low Scattering Laboratory in Brazil has been completely rebuilt. Evaluation of air attenuation parameters and neutron component scattering in the room was done using Monte Carlo simulation code. Neutron fields produced by referenced neutron source were used to calculate neutron scattering and air attenuation. PMID:24864318

  5. The neutron 'thunder' accompanying the extensive air shower

    NASA Astrophysics Data System (ADS)

    Erlykin, A. D.

    2007-03-01

    Simulations show that neutrons are the most abundant component among extensive air shower (EAS) hadrons. However, multiple neutrons which appear with long delays in neutron monitors nearby the EAS core (neutron thunder) are mostly not the neutrons of the shower, but have a secondary origin. The bulk of them is produced by high energy EAS hadrons hitting the monitors. The delays are due to the thermalization and diffusion of neutrons in the moderator and reflector of the monitor accompanied by the production of secondary gamma quanta. This conclusion raises the important problem of the interaction of EAS with the ground, the stuff of the detectors and their environment since they have often hydrogen-containing materials like polyethilene in neutron monitors. Such interaction can give an additional contribution to the signal in the EAS detectors. It can be particularly important for the signals from scintillator or water tank detectors at kilometre-long distances from the EAS core, where neutrons of the shower become the dominant component after a few microseconds behind the EAS front.

  6. Prompt Fission Neutron Emission in Resonance Fission of 239Pu

    SciTech Connect

    Hambsch, Franz-Josef; Oberstedt, Stephan; Varapai, Natallia; Serot, Olivier

    2005-05-24

    The prompt neutron emission probability from neutron-induced fission in the resonance region is being investigated at the time-of-flight facility GELINA of the IRMM. A double Frisch-gridded ionization chamber is used as a fission-fragment detector. For the data acquisition of both the fission-fragment signals as well as the neutron detector signals the fast digitization technique has been applied. For the neutron detection, large-volume liquid scintillation detectors from the DEMON collaboration are used. A specialized data analysis program taking advantage of the digital filtering technique has been developed to treat the acquired data.Neutron multiplicity investigations for actinides, especially in resonance neutron-induced fission, are rather scarce. They are, however, important for reactor control and safety issues as well as for understanding the basic physics of the fission process. Fission yield measurements on both 235U and 239Pu without prompt neutron emission coincidence have shown that fluctuation of the fission-fragment mass distribution exists from resonance to resonance, larger in the case of 235U. To possibly explain these observations, the question now is whether the prompt neutron multiplicity shows similar fluctuations with resonance energy.

  7. Current Status and Future Works of Neutron Scattering Laboratory at BATAN in Serpong

    NASA Astrophysics Data System (ADS)

    Ikram, A.

    2008-03-01

    Current status of neutron beam instruments using neutrons produced by the Multi Purpose Research Reactor—30MWth (MPR 30, RSG GA Siwabessy) located in Serpong is presented. Description of the reactor as the neutron source is mentioned briefly. There are six neutron beam tubes coming from the beryllium reflector surrounding half of the reactor core providing neutrons in the experimental hall of the reactor (XHR). Four of them are dedicated to R&D in materials science using neutron scattering techniques. Neutron Radiography Facility (NRF), Triple Axis Spectrometer (TAS) and Residual Stress Measurement (RSM) Diffractometer are installed respectively at beam tubes S2, S4 and S6. The largest neutron beam tube (S5) is exploited to accommodate two neutron guide tubes that transfer the neutrons to a neighbouring building called neutron guide hall (NGH). There are three other neutron beam instruments installed in this building, namely Small Angle Neutron Scattering (SANS) Spectrometer (SMARTer), High Resolution SANS (HRSANS) Spectrometer and High Resolution Powder Diffractometer (HRPD). In the XHR, a Four Circle and Texture Diffractometer (FCD/TD) is attached to one of the neutron guide tubes. These seven instruments were installed to utilize the neutrons for materials science research, and recently the RSM diffractometer has shown its capabilities in identifying different amount of stress left due to different treatments of welding in fuel cladding, while the SANS spectrometer is now gaining capabilities in identifying different sizes and shapes of macromolecules in polymers as well as investigations of magnetic samples. In the mean time, non-destructive tests using the NRF is gathering more confidence from some latest real time measurements eventhough there are still some shortcomings in the components and their alignments. Future works including improvement of each facility and its components, even replacement of some parts are necessary and have to be carried out

  8. A Code for the Generation of Group Constants for Reactor Calculations from Neutron Nuclear Data in KEDAK Format.

    1988-09-15

    Version 00 Group averaged neutron cross sections, energy resonance self shielding factors, elastic transfer elements up to P5 approximation, the inelastic, (n,2n) and (n,3n) transfer elements, fission spectra, etc., for coarse groups (26 groups in the standard case) in the fast neutron energy range are calculated.

  9. Search for neutron flux generation in a plasma discharge electrolytic cell

    NASA Astrophysics Data System (ADS)

    Faccini, R.; Pilloni, A.; Polosa, A. D.; Angelone, M.; Castagna, E.; Lecci, S.; Pietropaolo, A.; Pillon, M.; Sansovini, M.; Sarto, F.; Violante, V.; Bedogni, R.; Esposito, A.

    2014-06-01

    Following some recent unexpected hints of neutron production in high-voltage atmospheric discharges, we present a measurement of the neutron flux in plasma discharges in electrolytic cells. We use two different types of neutron detectors, polyallyl diglycol carbonate (PADC, aka CR-39) tracers and indium disks. At 95 % C.L. we provide an upper limit of 1.5 neutrons cm s for the thermal neutron flux at cm from the center of the cell. Allowing for a higher energy neutron component, the largest allowed flux is 64 neutrons cm s. This upper limit is two orders of magnitude smaller than the signal previously claimed in an electrolytic cell plasma discharge experiment. Furthermore the behavior of the CR-39 is discussed to point out possible sources of spurious signals.

  10. Neutron-induced background in charge-coupled device detectors

    SciTech Connect

    Jaanimagi, P. A.; Boni, R.; Keck, R. L.

    2001-01-01

    The inertial confinement fusion (ICF) community must become more cognizant of the neutron-induced background levels in charge-coupled device (CCD) detectors that are replacing film as the recording medium in many ICF diagnostics. This background degrades the signal-to-noise ratio (SNR) of the recorded signals and for the highest-yield shots comprises a substantial fraction of the pixel's full well capacity. CCD detectors located anywhere in the OMEGA Target Bay are precluded from recording high precision signals (SNR>30) for deuterium--tritium neutron yields greater than 10{sup 13}. CCDs make excellent calibrated neutron detectors. The average CCD background level is proportional to the neutron yield, and we have measured a linear response over four decades. The spectrum of deposited energy per pixel is heavily weighted to low energies, <50 keV, with a few isolated saturated pixels. Most of the background recorded by the CCDs is due to secondary radiation produced by interactions of the primary neutrons with all the materials in the Target Bay as well as the shield walls and the floor. Since the noise source comes from all directions it is very difficult to shield. The fallback position of using film instead of CCD cameras for high-neutron-yield target shots is flawed, as we have observed substantially increased fog levels on our x-ray recording film as a function of the neutron yield.

  11. Neutron sources and applications

    SciTech Connect

    Price, D.L.; Rush, J.J.

    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.

  12. Thermal neutron imaging in an active interrogation environment

    SciTech Connect

    Vanier,P.E.; Forman, L., and Norman, D.R.

    2009-03-10

    We have developed a thermal-neutron coded-aperture imager that reveals the locations of hydrogenous materials from which thermal neutrons are being emitted. This imaging detector can be combined with an accelerator to form an active interrogation system in which fast neutrons are produced in a heavy metal target by means of xcitation by high energy photons. The photo-induced neutrons can be either prompt or delayed, depending on whether neutronemitting fission products are generated. Provided that there are hydrogenous materials close to the target, some of the photo-induced neutrons slow down and emerge from the surface at thermal energies. These neutrons can be used to create images that show the location and shape of the thermalizing materials. Analysis of the temporal response of the neutron flux provides information about delayed neutrons from induced fission if there are fissionable materials in the target. The combination of imaging and time-of-flight discrimination helps to improve the signal-to-background ratio. It is also possible to interrogate the target with neutrons, for example using a D-T generator. In this case, an image can be obtained from hydrogenous material in a target without the presence of heavy metal. In addition, if fissionable material is present in the target, probing with fast neutrons can stimulate delayed neutrons from fission, and the imager can detect and locate the object of interest, using appropriate time gating. Operation of this sensitive detection equipment in the vicinity of an accelerator presents a number of challenges, because the accelerator emits electromagnetic interference as well as stray ionizing radiation, which can mask the signals of interest.

  13. ATR neutron spectral characterization

    SciTech Connect

    Rogers, J.W.; Anderl, R.A.

    1995-11-01

    The Advanced Test Reactor (ATR) at INEL provides intense neutron fields for irradiation-effects testing of reactor material samples, for production of radionuclides used in industrial and medical applications, and for scientific research. Characterization of the neutron environments in the irradiation locations of the ATR has been done by means of neutronics calculations and by means of neutron dosimetry based on the use of neutron activation monitors that are placed in the various irradiation locations. The primary purpose of this report is to present the results of an extensive characterization of several ATR irradiation locations based on neutron dosimetry measurements and on least-squares-adjustment analyses that utilize both neutron dosimetry measurements and neutronics calculations. This report builds upon the previous publications, especially the reference 4 paper. Section 2 provides a brief description of the ATR and it tabulates neutron spectral information for typical irradiation locations, as derived from the more historical neutron dosimetry measurements. Relevant details that pertain to the multigroup neutron spectral characterization are covered in section 3. This discussion includes a presentation on the dosimeter irradiation and analyses and a development of the least-squares adjustment methodology, along with a summary of the results of these analyses. Spectrum-averaged cross sections for neutron monitoring and for displacement-damage prediction in Fe, Cr, and Ni are given in section 4. In addition, section4 includes estimates of damage generation rates for these materials in selected ATR irradiation locations. In section 5, the authors present a brief discussion of the most significant conclusions of this work and comment on its relevance to the present ATR core configuration. Finally, detailed numerical and graphical results for the spectrum-characterization analyses in each irradiation location are provided in the Appendix.

  14. Accelerator Based Neutron Beams for Neutron Capture Therapy

    SciTech Connect

    Yanch, Jacquelyn C.

    2003-04-11

    The DOE-funded accelerator BNCT program at the Massachusetts Institute of Technology has resulted in the only operating accelerator-based epithermal neutron beam facility capable of generating significant dose rates in the world. With five separate beamlines and two different epithermal neutron beam assemblies installed, we are currently capable of treating patients with rheumatoid arthritis in less than 15 minutes (knee joints) or 4 minutes (finger joints) or irradiating patients with shallow brain tumors to a healthy tissue dose of 12.6 Gy in 3.6 hours. The accelerator, designed by Newton scientific Incorporated, is located in dedicated laboratory space that MIT renovated specifically for this project. The Laboratory for Accelerator Beam Applications consists of an accelerator room, a control room, a shielded radiation vault, and additional laboratory space nearby. In addition to the design, construction and characterization of the tandem electrostatic accelerator, this program also resulted in other significant accomplishments. Assemblies for generating epithermal neutron beams were designed, constructed and experimentally evaluated using mixed-field dosimetry techniques. Strategies for target construction and target cooling were implemented and tested. We demonstrated that the method of submerged jet impingement using water as the coolant is capable of handling power densities of up to 6 x 10(sup 7) W/m(sup 2) with heat transfer coefficients of 10(sup 6)W/m(sup 2)-K. Experiments with the liquid metal gallium demonstrated its superiority compared with water with little effect on the neutronic properties of the epithermal beam. Monoenergetic proton beams generated using the accelerator were used to evaluate proton RBE as a function of LET and demonstrated a maximum RBE at approximately 30-40 keV/um, a finding consistent with results published by other researchers. We also developed an experimental approach to biological intercomparison of epithermal beams and

  15. Dose spectra from energetic particles and neutrons

    NASA Astrophysics Data System (ADS)

    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.

  16. Introduction to neutron stars

    SciTech Connect

    Lattimer, James M.

    2015-02-24

    Neutron stars contain the densest form of matter in the present universe. General relativity and causality set important constraints to their compactness. In addition, analytic GR solutions are useful in understanding the relationships that exist among the maximum mass, radii, moments of inertia, and tidal Love numbers of neutron stars, all of which are accessible to observation. Some of these relations are independent of the underlying dense matter equation of state, while others are very sensitive to the equation of state. Recent observations of neutron stars from pulsar timing, quiescent X-ray emission from binaries, and Type I X-ray bursts can set important constraints on the structure of neutron stars and the underlying equation of state. In addition, measurements of thermal radiation from neutron stars has uncovered the possible existence of neutron and proton superfluidity/superconductivity in the core of a neutron star, as well as offering powerful evidence that typical neutron stars have significant crusts. These observations impose constraints on the existence of strange quark matter stars, and limit the possibility that abundant deconfined quark matter or hyperons exist in the cores of neutron stars.

  17. Neutron-emission measurements at a white neutron source

    SciTech Connect

    Haight, Robert C

    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.

  18. Measurements of neutron distribution in neutrons-gamma-rays mixed field using imaging plate for neutron capture therapy.

    PubMed

    Tanaka, Kenichi; Endo, Satoru; Hoshi, Masaharu

    2010-01-01

    The imaging plate (IP) technique is tried to be used as a handy method to measure the spatial neutron distribution via the (157)Gd(n,gamma)(158)Gd reaction for neutron capture therapy (NCT). For this purpose, IP is set in a water phantom and irradiated in a mixed field of neutrons and gamma-rays. The Hiroshima University Radiobiological Research Accelerator is utilized for this experiment. The neutrons are moderated with 20-cm-thick D(2)O to obtain suitable neutron field for NCT. The signal for IP doped with Gd as a neutron-response enhancer is subtracted with its contribution by gamma-rays, which was estimated using IP without Gd. The gamma-ray response of Gd-doped IP to non-Gd IP is set at 1.34, the value measured for (60)Co gamma-rays, in estimating the gamma-ray contribution to Gd-doped IP signal. Then measured distribution of the (157)Gd(n,gamma)(158)Gd reaction rate agrees within 10% with the calculated value based on the method that has already been validated for its reproducibility of Au activation. However, the evaluated distribution of the (157)Gd(n,gamma)(158)Gd reaction rate is so sensitive to gamma-ray energy, e.g. the discrepancy of the (157)Gd(n,gamma)(158)Gd reaction rate between measurement and calculation becomes 30% for the photon energy change from 33keV to 1.253MeV.

  19. Short-term natural δ13C variations in pools and fluxes in a beech forest: the transfer of isotopic signal from recent photosynthates to soil respired CO2

    NASA Astrophysics Data System (ADS)

    Gavrichkova, O.; Proietti, S.; Moscatello, S.; Portarena, S.; Battistelli, A.; Matteucci, G.; Brugnoli, E.

    2011-03-01

    The fate of photosynthetic products within the plant-soil continuum determines how long the reduced carbon resides within the ecosystem and when it returns back to the atmosphere in the form of respiratory CO2. We have tested the possibility of measuring natural variation in δ13C to disentangle potential times needed to transfer carbohydrates produced by photosynthesis down to roots and, in general, to belowground up to its further release in the form of soil respiration into the atmosphere in a beech (Fagus sylvatica) forest. For these purposes we have measured the variation in stable carbon and oxygen isotope compositions in plant material and in soil respired CO2 every three hours for three consequent days. Possible steps and different signs of post-photosynthetic fractionation during carbon translocation were also identified. A 12 h-periodicity was observed for variation in δ13C in soluble sugars in the top crown leaves and it can be explained by starch day/night dynamics in synthesis and breakdown and by stomatal limitations under elevated vapour pressure deficits. Photosynthetic products were transported down the trunk and mixed with older carbon pools, therefore causing the dampening of the δ13C signal variation. The strongest periodicity of 24 h was found in δ13C in soil respiration indicating changes in root contribution to the total CO2 efflux. Nevertheless, it was possible to identify the speed of carbon translocation through the plant-soil continuum. A period of 24 h was needed to transfer the C assimilated by photosynthesis from the top crown leaves to the tree trunk at breast height and additional 3 h for further respiration of that C by roots and soil microorganisms and its to subsequent diffusion back to the atmosphere.

  20. A New Method of Prompt Fission Neutron Energy Spectrum Unfolding

    SciTech Connect

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

    2010-11-25

    The prompt neutron emission in spontaneous fission of {sup 252}Cf has been investigated applying digital signal electronics along with associated digital signal processing algorithms. The goal was to find out the reasons of a long time existing discrepancy between theoretical calculations and the measurements of prompt fission neutron (PFN) emission dependence on the total kinetic energy (TKE) of fission fragments (FF). On the one hand the {sup 252}Cf(sf) reaction is one of the main references for nuclear data, on the other hand the understanding of PFN emission mechanism is very important for nuclear fission theory. Using a twin Frisch-grid ionization chamber for fission fragment (FF) detection and a NE213-equivalent neutron detector in total about 10{sup 7} 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. 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.

  1. Thermal neutron scattering in graphite

    NASA Astrophysics Data System (ADS)

    Al-Qasir, Iyad Ibrahim

    Generation IV Very High Temperature Reactor (VHTR) concepts, are graphite moderated and gas cooled thermal spectrum reactors. The characteristics of the low energy (E < 1 eV) neutron spectrum in these reactors will be dictated by the process of neutron slowing-down and thermalization in the graphite moderator. The ability to accurately predict this process in these reactors can have significant neutronic and safety implications. In reactor design calculations, thermal neutron scattering cross section libraries are needed for the prediction of the thermal neutron environment in the core. Currently used libraries (ENDF/B-VII) are a product of the 1960s and remain based on many physical approximations. In addition, these libraries show noticeable discrepancies with experimental data. In this work, investigation of thermal neutron scattering in graphite as a function of temperature was performed. The fundamental input for the calculation of thermal neutron scattering cross sections, i.e., the phonon frequency distribution and/or the dispersion relations, was generated using a modern approach that is based on quantum mechanical electronic structure (ab initio) simulations combined with a lattice dynamics direct method supercell approach. The calculations were performed using the VASP and PHONON codes. The VASP calculations used the local density approximation, and the projector augmented-wave pseudopotential. A supercell of 144 atoms was used; and the integration over the Brillouin zone was confined to a 3x3x4 k-mesh generated by the Monkhorst-Pack scheme. A plane-wave basis set with an energy cutoff of 500 eV was applied. The corresponding dispersion relations, heat capacity, and phonon frequency distribution show excellent agreement with experimental data. Despite the use of the above techniques to produce more accurate input data, the examination of the results indicated persistence of the inconsistencies between calculations and measurements at neutron energies

  2. Binary Neutron Star Mergers with Initial Spin

    NASA Astrophysics Data System (ADS)

    Kastaun, Wolfgang; Galeazzi, Filippo

    2015-04-01

    Recently, we performed simulations of binary neutron star mergers which included both nuclear physics equations of state and stars with initial spin for the first time. The focus was on systems resulting in hyper-massive neutron stars. I will discuss the influence of realistic amounts of spin on the outcome, in particular regarding the gravitational wave signal. We also investigated the structure and dynamics of the remnant in detail, revealing some interesting new aspects. For example, we observe rotational profiles not fitting the standard notion of a rapidly rotating core, and show that strong quasi-radial oscillations in the post merger phase have an impact on the gravitational wave spectrum via a modulation of the m=2 mode frequency, offering an alternative to recent interpretations of high frequency side-peaks as non-linear combination frequencies. Finally, we discuss a possible mechanism in which the initial neutron star spins can influence the amount of ejected matter in some cases.

  3. Transfer Function Control for Biometric Monitoring System

    NASA Technical Reports Server (NTRS)

    Chmiel, Alan J. (Inventor); Humphreys, Bradley T. (Inventor); Grodinsky, Carlos M. (Inventor)

    2015-01-01

    A modular apparatus for acquiring biometric data may include circuitry operative to receive an input signal indicative of a biometric condition, the circuitry being configured to process the input signal according to a transfer function thereof and to provide a corresponding processed input signal. A controller is configured to provide at least one control signal to the circuitry to programmatically modify the transfer function of the modular system to facilitate acquisition of the biometric data.

  4. Novel Materials and Devices for Solid-State Neutron Detection

    SciTech Connect

    Manginell, Ronald P.; Pfeifer, Kent B.

    2015-11-01

    There is a need in many fields, such as nuclear medicine, non-proliferation, energy exploration, national security, homeland security, nuclear energy, etc, for miniature, thermal neutron detectors. Until recently, thermal neutron detection has required physically large devices to provide sufficient neutron interaction and transduction signal. Miniaturization would allow broader use in the fields just mentioned and open up other applications potentially. Recent research shows promise in creating smaller neutron detectors through the combination of high-neutron-cross-section converter materials and solid-state devices. Yet, till recently it is difficult to measure low neutron fluxes by solidstate means given the need for optimized converter materials (purity, chemical composition and thickness) and a lack of designs capable of efficient transduction of the neutron conversion products (x-rays, electrons, gamma rays). Gadolinium-based semiconductor heterojunctions have detected electrons produced by Gd-neutron reactions but only at high neutron fluxes. One of the main limitations to this type of approach is the use of thin converter layers and the inability to utilize all the conversion products. In this LDRD we have optimized the converter material thickness and chemical composition to improve capture of conversion electrons and have detected thermal neutrons with high fidelity at low flux. We are also examining different semiconductor materials and converter materials to attempt to capture a greater percentage of the conversion electrons, both low and higher energy varieties. We have studied detector size and bias scaling, and cross-sensitivity to xrays and shown that we can detect low fluxes of thermal neutrons in less than 30 minutes with high selectivity by our approach. We are currently studying improvements in performance with direct placement of the Gd converter on the detector. The advancement of sensitive, miniature neutron detectors will have benefits in

  5. TRANSFER STUDY.

    ERIC Educational Resources Information Center

    GREIVE, DONALD E.

    THIS 1967 STUDY AT LORAIN COUNTY COMMUNITY COLLEGE (LCCC) WAS UNDERTAKEN TO DISCOVER (1) THE PERCENTAGE OF CREDIT HOURS IN A UNIVERSITY PARALLEL PROGRAM ACCEPTED BY TRANSFER INSTITUTIONS, (2) THE STUDENT'S GPA BEFORE AND AFTER TRANSFER, AND (3) HOW MANY COLLEGES ACCEPTED LCCC'S TRANSFERS. INSTITUTIONS TO WHICH LCCC STUDENTS HAD HAD THEIR…

  6. Signal voter

    DOEpatents

    Goodwin, Roy L.

    1981-01-01

    A voter for providing a single accurate output signal that is derived from the closest two signal levels of three input signals, each of which signals represents a measurement of the same phenomena. By means of the voting circuit, the signals are first sorted by level of amplitude and then ranked as highest, middle or lowest. The highest or lowest signal that is furthest from the middle signal is rejected, while the other highest or lowest signal is selected for processing. The selected high or low signal is then averaged with the middle signal to provide the output signal.

  7. Real-Time Active Cosmic Neutron Background Reduction Methods

    SciTech Connect

    Mukhopadhyay, Sanjoy; Maurer, Richard; Wolff, Ronald; Mitchell, Stephen; Guss, Paul

    2013-09-01

    Neutron counting using large arrays of pressurized 3He proportional counters from an aerial system or in a maritime environment suffers from the background counts from the primary cosmic neutrons and secondary neutrons caused by cosmic ray-induced mechanisms like spallation and charge-exchange reaction. This paper reports the work performed at the Remote Sensing Laboratory–Andrews (RSL-A) and results obtained when using two different methods to reduce the cosmic neutron background in real time. Both methods used shielding materials with a high concentration (up to 30% by weight) of neutron-absorbing materials, such as natural boron, to remove the low-energy neutron flux from the cosmic background as the first step of the background reduction process. Our first method was to design, prototype, and test an up-looking plastic scintillator (BC-400, manufactured by Saint Gobain Corporation) to tag the cosmic neutrons and then create a logic pulse of a fixed time duration (~120 μs) to block the data taken by the neutron counter (pressurized 3He tubes running in a proportional counter mode). The second method examined the time correlation between the arrival of two successive neutron signals to the counting array and calculated the excess of variance (Feynman variance Y2F)1 in the neutron count distribution from Poisson distribution. The dilution of this variance from cosmic background values ideally would signal the presence of man-made neutrons.2 The first method has been technically successful in tagging the neutrons in the cosmic-ray flux and preventing them from being counted in the 3He tube array by electronic veto—field measurement work shows the efficiency of the electronic veto counter to be about 87%. The second method has successfully derived an empirical relationship between the percentile non-cosmic component in a neutron flux and the Y2F of the measured neutron count distribution. By using shielding materials alone, approximately 55% of the neutron flux

  8. Real-time active cosmic neutron background reduction methods

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Sanjoy; Maurer, Richard; Wolff, Ronald; Mitchell, Stephen; Guss, Paul

    2013-09-01

    Neutron counting using large arrays of pressurized 3He proportional counters from an aerial system or in a maritime environment suffers from the background counts from the primary cosmic neutrons and secondary neutrons caused by cosmic ray‒induced mechanisms like spallation and charge-exchange reaction. This paper reports the work performed at the Remote Sensing Laboratory-Andrews (RSL-A) and results obtained when using two different methods to reduce the cosmic neutron background in real time. Both methods used shielding materials with a high concentration (up to 30% by weight) of neutron-absorbing materials, such as natural boron, to remove the lowenergy neutron flux from the cosmic background as the first step of the background reduction process. Our first method was to design, prototype, and test an up-looking plastic scintillator (BC-400, manufactured by Saint Gobain Corporation) to tag the cosmic neutrons and then create a logic pulse of a fixed time duration (~120 μs) to block the data taken by the neutron counter (pressurized 3He tubes running in a proportional counter mode). The second method examined the time correlation between the arrival of two successive neutron signals to the counting array and calculated the excess of variance (Feynman variance Y2F)1 in the neutron count distribution from Poisson distribution. The dilution of this variance from cosmic background values ideally would signal the presence of manmade neutrons.2 The first method has been technically successful in tagging the neutrons in the cosmic-ray flux and preventing them from being counted in the 3He tube array by electronic veto—field measurement work shows the efficiency of the electronic veto counter to be about 87%. The second method has successfully derived an empirical relationship between the percentile non-cosmic component in a neutron flux and the Y2F of the measured neutron count distribution. By using shielding materials alone, approximately 55% of the neutron flux

  9. Position sensitive detection of neutrons in high radiation background field

    SciTech Connect

    Vavrik, D.; Jakubek, J.; Pospisil, S.; Vacik, J.

    2014-01-15

    We present the development of a high-resolution position sensitive device for detection of slow neutrons in the environment of extremely high γ and e{sup −} radiation background. We make use of a planar silicon pixelated (pixel size: 55 × 55 μm{sup 2}) spectroscopic Timepix detector adapted for neutron detection utilizing very thin {sup 10}B converter placed onto detector surface. We demonstrate that electromagnetic radiation background can be discriminated from the neutron signal utilizing the fact that each particle type produces characteristic ionization tracks in the pixelated detector. Particular tracks can be distinguished by their 2D shape (in the detector plane) and spectroscopic response using single event analysis. A Cd sheet served as thermal neutron stopper as well as intensive source of gamma rays and energetic electrons. Highly efficient discrimination was successful even at very low neutron to electromagnetic background ratio about 10{sup −4}.

  10. Status of neutron diagnostics on the experimental advanced superconducting tokamak

    NASA Astrophysics Data System (ADS)

    Zhong, G. Q.; Hu, L. Q.; Pu, N.; Zhou, R. J.; Xiao, M.; Cao, H. R.; Zhu, Y. B.; Li, K.; Fan, T. S.; Peng, X. Y.; Du, T. F.; Ge, L. J.; Huang, J.; Xu, G. S.; Wan, B. N.

    2016-11-01

    Neutron diagnostics have become a significant means to study energetic particles in high power auxiliary heating plasmas on the Experimental Advanced Superconducting Tokamak (EAST). Several kinds of neutron diagnostic systems have been implemented for time-resolved measurements of D-D neutron flux, fluctuation, emission profile, and spectrum. All detectors have been calibrated in laboratory, and in situ calibration using 252Cf neutron source in EAST is in preparation. A new technology of digitized pulse signal processing is adopted in a wide dynamic range neutron flux monitor, compact recoil proton spectrometer, and time of flight spectrometer. Improvements will be made continuously to the system to achieve better adaptation to the EAST's harsh γ-ray and electro-magnetic radiation environment.

  11. Measurements of the neutron source strength at DIII-D

    SciTech Connect

    Heidbrink, W.W.; Taylor, P.L.; Phillips, J.A.

    1997-01-01

    A set of neutron counters and a pair of scintillators measure the 2.5 MeV neutron emission produced by the DIII-D tokamak. The neutron counter set provides a large dynamic range ({approximately}7 orders of magnitude) while the scintillators provide the very fast resolution needed for studying transient events. The counters are absolutely calibrated {ital in situ} with a {sup 252}Cf source and the scintillators are cross calibrated to the counters. The historic variations in the emission measured by the various detectors have been compared and are consistent within the estimated accuracy of the absolute calibration (15{percent}). In the discharges with the highest emission levels (2.4{times}10{sup 16} n/s), the signals from the neutron counters and the scintillators agree well. Comparisons with other diagnostics also corroborate the neutron measurements.{copyright} {ital 1997 American Institute of Physics.}

  12. Digital signal processing: Handbook

    NASA Astrophysics Data System (ADS)

    Goldenberg, L. M.; Matiushkin, B. D.; Poliak, M. N.

    The fundamentals of the theory and design of systems and devices for the digital processing of signals are presented. Particular attention is given to algorithmic methods of synthesis and digital processing equipment in communication systems (e.g., selective digital filtering, spectral analysis, and variation of the signal discretization frequency). Programs for the computer-aided analysis of digital filters are described. Computational examples are presented, along with tables of transfer function coefficients for recursive and nonrecursive digital filters.

  13. Technology transfer

    NASA Technical Reports Server (NTRS)

    Handley, Thomas

    1992-01-01

    The requirements for a successful technology transfer program and what such a program would look like are discussed. In particular, the issues associated with technology transfer in general, and within the Jet Propulsion Laboratory (JPL) environment specifically are addressed. The section on background sets the stage, identifies the barriers to successful technology transfer, and suggests actions to address the barriers either generally or specifically. The section on technology transfer presents a process with its supporting management plan that is required to ensure a smooth transfer process. Viewgraphs are also included.

  14. Neutron capture therapies

    SciTech Connect

    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.

  15. Fundamental Neutron Physics

    NASA Astrophysics Data System (ADS)

    Marciano, William J.

    A precise connection between Vud, gA ≡ GA/GV and rn is reviewed. Implications for CKM unitarity and muon capture are discussed. The neutron electric dipole moment and CP violation in H → yy are related. ΔB = 2 n oscillations are shown to probe the neutron's Majorana nature and provide a possible paradigm for dark matter behavior.

  16. NEUTRONIC REACTOR CONTROL

    DOEpatents

    Untermyer, S.; Hutter, E.

    1959-08-01

    This patent relates to "shadow" control of a nuclear reactor. The control means comprises a plurality ot elongated rods disposed adjacent and parallel to each other, The morphology and effects of gases generated within sections of neutron absorbing materials and equal length sections of neutron permeable materials together with means for longitudinally pcsitioning the rcds relative to each other.

  17. Neutron capture therapies

    DOEpatents

    Yanch, Jacquelyn C.; Shefer, Ruth E.; Klinkowstein, Robert E.

    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.

  18. Compact neutron generator

    DOEpatents

    Leung, Ka-Ngo; Lou, Tak Pui

    2005-03-22

    A compact neutron generator has at its outer circumference a toroidal shaped plasma chamber in which a tritium (or other) plasma is generated. A RF antenna is wrapped around the plasma chamber. A plurality of tritium ion beamlets are extracted through spaced extraction apertures of a plasma electrode on the inner surface of the toroidal plasma chamber and directed inwardly toward the center of neutron generator. The beamlets pass through spaced acceleration and focusing electrodes to a neutron generating target at the center of neutron generator. The target is typically made of titanium tubing. Water is flowed through the tubing for cooling. The beam can be pulsed rapidly to achieve ultrashort neutron bursts. The target may be moved rapidly up and down so that the average power deposited on the surface of the target may be kept at a reasonable level. The neutron generator can produce fast neutrons from a T-T reaction which can be used for luggage and cargo interrogation applications. A luggage or cargo inspection system has a pulsed T-T neutron generator or source at the center, surrounded by associated gamma detectors and other components for identifying explosives or other contraband.

  19. Neutron elastic backscattering with resonance enhancement

    SciTech Connect

    Gomberg, H.J.; McEllistrem, M.T.

    1993-12-31

    Reliable detection of explosives and narcotics depends on generating signatures of compounds which characterize them. Major explosives and also alkaloid narcotics contain unique concentrations of Carbon, Oxygen, and Nitrogen which provide specific elemental ratios and chemical signatures. Neutron-induced reaction methods are rapid and non-invasive means of probing container interiors for special element-ratio signatures which signal the presence of significant amounts of contraband. Among these reactions the highest probabilities occur for neutron from different light elements, allowing determination of relative abundance of these elements. The authors have already demonstrated signature for simulated explosives and simulated narcotics in experimental tests at 1-4 MeV at the University of Kentucky accelerator labs. Intensities of neutron scatter at angles near 150{degrees} from three different elements, C, N, and O, were determined. Fast neutron time-of-flight detection methods enabled measurement of neutron energies, and thus separation of scattering from the different elements. Making measurements on and off strong resonances for specific elements, increases PFD and reduces PFA. Measurements illustrating this resonance enhancement technique will be presented.

  20. Neutron and Gamma Ray Pulse Shape Discrimination with Polyvinyltoluene

    SciTech Connect

    Lintereur, Azaree T.; Ely, James H.; Stave, Jean A.; McDonald, Benjamin S.

    2012-03-01

    The goal of this was research effort was to test the ability of two poly vinyltoluene research samples to produce recordable, distinguishable signals in response to gamma rays and neutrons. Pulse shape discrimination was performed to identify if the signal was generated by a gamma ray or a neutron. A standard figure of merit for pulse shape discrimination was used to quantify the gamma-neutron pulse separation. Measurements were made with gamma and neutron sources with and without shielding. The best figure of merit obtained was 1.77; this figure of merit was achieved with the first sample in response to an un-moderated 252Cf source shielded with 5.08 cm of lead.

  1. Thermal neutron flux monitors based on vibrating wire

    NASA Astrophysics Data System (ADS)

    Arutunian, S. G.; Bergoz, J.; Chung, M.; Harutyunyan, G. S.; Lazareva, E. G.

    2015-10-01

    Two types of neutron monitors with fine spatial resolutions are proposed based on vibrating wires. In the first type, neutrons interact with a vibrating wire, heat it, and lead to the change of its natural frequency, which can be precisely measured. To increase the heat deposition during the neutron scattering, the use of gadolinium layer that has the highest thermal neutron capture cross-section among all elements is proposed. The second type uses the vibrating wire as a "resonant target." Besides the measurement of beam profile according to the average signal, the differential signal synchronized with the wire oscillations defines the beam profile gradient. The monitor's spatial resolution is defined by the wire's diameter.

  2. Fractal Approach in Petrology: Combining Ultra-Small Angle (USANA) and Small Angle Neutron Scattering (SANS)

    SciTech Connect

    LoCelso, F.; Triolo, F.; Triolo, A.; Lin, J.S.; Lucido, G.; Triolo, R.

    1999-10-14

    Ultra small angle neutron scattering instruments have recently covered the gap between the size resolution available with conventional intermediate angle neutron scattering and small angle neutron scattering instruments on one side and optical microscopy on the other side. Rocks showing fractal behavior in over two decades of momentum transfer and seven orders of magnitude of intensity are examined and fractal parameters are extracted from the combined USANS and SANS curves.

  3. Pocked surface neutron detector

    DOEpatents

    McGregor, Douglas; Klann, Raymond

    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.

  4. Neutrons against cancer

    NASA Astrophysics Data System (ADS)

    Dovbnya, A. N.; Kuplennikov, E. L.; Kandybey, S. S.; Krasiljnikov, V. V.

    2014-09-01

    The review is devoted to the analysis and generalization of the research carried out during recent years in industrially advanced countries on the use of fast, epithermal, and thermal neutrons for therapy of malignant tumors. Basic facilities for neutron production used for cancer treatment are presented. Optimal parameters of therapeutic beams are described. Techniques using neutrons of different energy regions are discussed. Results and medical treatment efficiency are given. Comparison of the current state of neutron therapy of tumors and alternative treatments with beams of protons and carbon ions has been conducted. Main attention is given to the possibility of the practical use of accumulated experience of application of neutron beams for cancer therapy.

  5. Pulsed neutron detector

    DOEpatents

    Robertson, deceased, J. Craig; Rowland, Mark S.

    1989-03-21

    A pulsed neutron detector and system for detecting low intensity fast neutron pulses has a body of beryllium adjacent a body of hydrogenous material the latter of which acts as a beta particle detector, scintillator, and moderator. The fast neutrons (defined as having En>1.5 MeV) react in the beryllium and the hydrogenous material to produce larger numbers of slow neutrons than would be generated in the beryllium itself and which in the beryllium generate hellium-6 which decays and yields beta particles. The beta particles reach the hydrogenous material which scintillates to yield light of intensity related to the number of fast neutrons. A photomultiplier adjacent the hydrogenous material (scintillator) senses the light emission from the scintillator. Utilization means, such as a summing device, sums the pulses from the photo-multiplier for monitoring or other purposes.

  6. NEUTRON SHIELDING STRUCTURE

    DOEpatents

    Mattingly, J.T.

    1962-09-25

    A lightweight neutron shielding structure comprises a honeycomb core which is filled with a neutron absorbing powder. The honeycomb core is faced with parallel planar facing sheets to form a lightweight rigid unit. Suitable absorber powders are selected from among the following: B, B/sub 4/C, B/sub 2/O/ sub 3/, CaB/sub 6/, Li/sub 2/CO3, LiOH, LiBO/sub 2/, Li/s ub 2/O. The facing sheets are constructed of a neutron moderating material, so that fast neutrons will be moderated while traversing the facing sheets, and ultimately be absorbed by the absorber powder in the honeycomb. Beryllium is a preferred moderator material for use in the facing sheets. The advantage of the structure is that it combines the rigidity and light weight of a honeycomb construction with the neutron absorption properties of boron and lithium. (AEC)

  7. Simulated workplace neutron fields

    NASA Astrophysics Data System (ADS)

    Lacoste, V.; Taylor, G.; Röttger, S.

    2011-12-01

    The use of simulated workplace neutron fields, which aim at replicating radiation fields at practical workplaces, is an alternative solution for the calibration of neutron dosemeters. They offer more appropriate calibration coefficients when the mean fluence-to-dose equivalent conversion coefficients of the simulated and practical fields are comparable. Intensive Monte Carlo modelling work has become quite indispensable for the design and/or the characterization of the produced mixed neutron/photon fields, and the use of Bonner sphere systems and proton recoil spectrometers is also mandatory for a reliable experimental determination of the neutron fluence energy distribution over the whole energy range. The establishment of a calibration capability with a simulated workplace neutron field is not an easy task; to date only few facilities are available as standard calibration fields.

  8. Final Report on Actinide Glass Scintillators for Fast Neutron Detection

    SciTech Connect

    Bliss, Mary; Stave, Jean A.

    2012-10-01

    This is the final report of an experimental investigation of actinide glass scintillators for fast-neutron detection. It covers work performed during FY2012. This supplements a previous report, PNNL-20854 “Initial Characterization of Thorium-loaded Glasses for Fast Neutron Detection” (October 2011). The work in FY2012 was done with funding remaining from FY2011. As noted in PNNL-20854, the glasses tested prior to July 2011 were erroneously identified as scintillators. The decision was then made to start from “scratch” with a literature survey and some test melts with a non-radioactive glass composition that could later be fabricated with select actinides, most likely thorium. The normal stand-in for thorium in radioactive waste glasses is cerium in the same oxidation state. Since cerium in the 3+ state is used as the light emitter in many scintillating glasses, the next most common substitute was used: hafnium. Three hafnium glasses were melted. Two melts were colored amber and a third was clear. It barely scintillated when exposed to alpha particles. The uses and applications for a scintillating fast neutron detector are important enough that the search for such a material should not be totally abandoned. This current effort focused on actinides that have very high neutron capture energy releases but low neutron capture cross sections. This results in very long counting times and poor signal to noise when working with sealed sources. These materials are best for high flux applications and access to neutron generators or reactors would enable better test scenarios. The total energy of the neutron capture reaction is not the only factor to focus on in isotope selection. Many neutron capture reactions result in energetic gamma rays that require large volumes or high densities to detect. If the scintillator is to separate neutrons from gamma rays, the capture reactions should produce heavy particles and few gamma rays. This would improve the detection of a

  9. SINGLE CRYSTAL NEUTRON DIFFRACTION.

    SciTech Connect

    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.

  10. ESR investigation of joint use of dentin and tooth enamel to estimate photon and neutron dose components of a mixed field.

    PubMed

    Trompier, F; Tikunov, D D; Ivannikov, A; Clairand, I

    2006-01-01

    In the case of mixed photon and neutron field, estimation of photon and neutron dose components from the ESR signal of tooth enamel alone is impossible. To differentiate neutron and photon components using the method described in ICRU 26 for twin chambers, enamel and dentin sensitivities to photon and to neutron were investigated. Enamel and dentin relative sensitivities were, respectively, estimated at 0.03 +/- 0.02 and 0.14 +/- 0.10 for fission neutrons. Basing on this result, calculation of neutron and photon doses was performed in realistic case of criticality accident. Estimation of neutron and photon dose components was found in good agreement with reference dosimetry.

  11. Using singular value decomposition for neutron-gamma discrimination

    NASA Astrophysics Data System (ADS)

    Linczuk, Maciej; Korolczuk, Stefan; Cieszewski, Radosław

    2015-09-01

    A Digital Signal Processing method for Neutron Gamma Discrimination [1] is described in this paper. A Singular Value Decomposition (SVD) was used for estimation noiseless signal shape. Based on this shape, detection method was introduced. This method uses projection operation into signal and noise subspace and Signal to Noise Ratio estimation. This method was compared with another one proposed by [2]. Booth method was implemented in MATLAB. Computation was done on signals from scintillators. Data acquisition was dome with high quality hardware. The Neutron Gamma Discrimination algorithm operate on digital samples from ADC converter. Hardware used for data acquisition in this this paper was described in [3]. On the end, the results of this two methods was presented and compared. The signal model in this methods assume additional, white, Gaussian noise.

  12. Optical polarizing neutron devices designed for pulsed neutron sources

    SciTech Connect

    Takeda, M.; Kurahashi, K.; Endoh, Y.; Itoh, S.

    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.

  13. DESIGN OF A LARGE-AREA FAST NEUTRON DIRECTIONAL DETECTOR.

    SciTech Connect

    VANIER, P.E.

    2006-10-29

    A large-area fast-neutron double-scatter directional detector and spectrometer is being constructed using l-meter-long plastic scintillator paddles with photomultiplier tubes at both ends. The scintillators detect fast neutrons by proton recoil and also gamma rays by Compton scattering. The paddles are arranged in two parallel planes so that neutrons can be distinguished from muons and gamma rays by time of flight between the planes. The signal pulses are digitized with a time resolution of one gigasample per second. The location of an event along each paddle can be determined from the relative amplitudes or timing of the signals at the ends. The angle of deflection of a neutron in the first plane can be estimated from the energy deposited by the recoil proton, combined with the scattered neutron time-of-flight energy. Each scattering angle can be back-projected as a cone, and many intersecting cones define the incident neutron direction from a distant point source. Moreover, the total energy of each neutron can be obtained, allowing some regions of a fission source spectrum to be distinguished from background generated by cosmic rays. Monte Carlo calculations will be compared with measurements.

  14. Diamond detector for high rate monitors of fast neutrons beams

    SciTech Connect

    Giacomelli, L.; Rebai, M.; Cippo, E. Perelli; Tardocchi, M.; Fazzi, A.; Andreani, C.; Pietropaolo, A.; Frost, C. D.; Rhodes, N.; Schooneveld, E.; Gorini, G.

    2012-06-19

    A fast neutron detection system suitable for high rate measurements is presented. The detector is based on a commercial high purity single crystal diamond (SDD) coupled to a fast digital data acquisition system. The detector was tested at the ISIS pulsed spallation neutron source. The SDD event signal was digitized at 1 GHz to reconstruct the deposited energy (pulse amplitude) and neutron arrival time; the event time of flight (ToF) was obtained relative to the recorded proton beam signal t{sub 0}. Fast acquisition is needed since the peak count rate is very high ({approx}800 kHz) due to the pulsed structure of the neutron beam. Measurements at ISIS indicate that three characteristics regions exist in the biparametric spectrum: i) background gamma events of low pulse amplitudes; ii) low pulse amplitude neutron events in the energy range E{sub dep}= 1.5-7 MeV ascribed to neutron elastic scattering on {sup 12}C; iii) large pulse amplitude neutron events with E{sub n} < 7 MeV ascribed to {sup 12}C(n,{alpha}){sup 9}Be and 12C(n,n')3{alpha}.

  15. Testing of Liquid Scintillator Materials for Gamma and Neutron Detection

    SciTech Connect

    Verbeke, J M; Nakae, L; Kerr, P; Dietrich, D; Dougan, A

    2009-06-19

    The key fact about fissile material is that a sufficient quantity of the material can produce chains of fissions, including some very long chains. A chain of fissions will give rise to a detected burst of neutrons with longer chains generally producing larger bursts. These bursts produce distinctive time correlations in a detector near the multiplying material. These correlations are measurable and can be analyzed to infer attributes of the fissile material including fissile material mass, assembly neutron multiplication, characteristic fast fission chain evolution time scale, also known as the {alpha} time scale, thermalization time scale. The correlation signal is very robust with respect to background and to neutron absorbing material.

  16. Neutron detection by scintillation of noble-gas excimers

    NASA Astrophysics Data System (ADS)

    McComb, Jacob Collin

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

  17. Density dependent hadronic models and the relation between neutron stars and neutron skin thickness

    SciTech Connect

    Avancini, S. S.; Marinelli, J. R.; Menezes, D. P.; Moraes, M. M. W.; Providencia, C.

    2007-05-15

    In the present work, we investigate the main differences in the lead neutron skin thickness, binding energy, surface energy, and density profiles obtained with two different density dependent hadron models. Our results are calculated within the Thomas-Fermi approximation with two different numerical prescriptions and compared with results obtained with a common parametrization of the nonlinear Walecka model. The neutron skin thickness is a reflex of the equation of state properties. Hence, a direct correlation is found between the neutron skin thickness and the slope of the symmetry energy. We show that within the present approximations, the asymmetry parameter for low momentum transfer polarized electron scattering is not sensitive to the model differences.

  18. Precision neutron flux measurement with a neutron beam monitor

    NASA Astrophysics Data System (ADS)

    Ino, T.; Otono, H.; Mishima, K.; Yamada, T.

    2014-07-01

    Neutron beam monitors are regularly used in various neutron beam experiments to compare two or more sets of data taken in different experimental conditions. A neutron lifetime experiment at BL05, the NOP beamline, in J-PARC requires to monitor the initial neutron intensity with an precision of 0.1% to measure the neutron lifetime with the same accuracy. The performance of a thin 3He gas neutron beam monitor used for the experiment was studied to estimate the systematic uncertainties in the neutron lifetime measurement.

  19. Development of Grazing Incidence Optics for Neutron Imaging and Scattering

    NASA Technical Reports Server (NTRS)

    Gubarev, M. V.; Khaykovich, B.; Liu, D.; Ramsey, B. D.; Zavlin, V. E.; Kilaru, K.; Romaine, S.; Rosati, R. E.; Bruni, R.; Moncton, D. E.

    2012-01-01

    Because of their wave nature, thermal and cold neutrons can be reflected from smooth surfaces at grazing incidence angles, be reflected by multilayer coatings or be refracted at boundaries of different materials. The optical properties of materials are characterized by their refractive indices which are slightly less than unity for most elements and their isotopes in the case of cold and thermal neutrons as well as for x-rays. The motivation for the optics use for neutrons as well as for x-rays is to increase the signal rate and, by virtue of the optic's angular resolution, to improve the signal-to-noise level by reducing the background so the efficiency of the existing neutron sources use can be significantly enhanced. Both refractive and reflective optical techniques developed for x-ray applications can be applied to focus neutron beams. Typically neutron sources have lower brilliance compared to conventional x-ray sources so in order to increase the beam throughput the neutron optics has to be capable of capturing large solid angles. Because of this, the replicated optics techniques developed for x-ray astronomy applications would be a perfect match for neutron applications, so the electroformed nickel optics under development at the Marshall Space Flight Center (MSFC) can be applied to focus neutron beams. In this technique, nickel mirror shells are electroformed onto a figured and superpolished nickel-plated aluminum cylindrical mandrel from which they are later released by differential thermal contraction. Cylindrical mirrors with different diameters, but the same focal length, can be nested together to increase the system throughput. The throughput can be increased further with the use of the multilayer coatings deposited on the reflectivr surface of the mirror shells. While the electroformed nickel replication technique needs to be adopted for neutron focusing, the technology to coat the inside of cylindrical mirrors with neutron multilayers has to be

  20. Shell structure in neutron rich nuclei by means of binary reactions

    SciTech Connect

    Angelis, G. de

    2014-08-14

    Nuclear structure studies far from stability rely mainly on the availability of radioactive nuclear beams but can complementary be addressed by means of high intensity beams of stable ions. In such contest, deep-inelastic and multinucleon transfer reactions are a powerful tool to populate yrast and non yrast states in neutron-rich nuclei. Particularly successful is here the combination of large acceptance spectrometers with highly segmented gamma-detector arrays. Such devices can provide the necessary channel selectivity to identify very rare signals. The AGATA gamma-ray detector array coupled to the PRISMA spectrometer at the Legnaro National Laboratories (LNL) in Italy is one example. Large data sets have been collected at LNL for nuclei close to the N=20, 28, 40, 50 and 82 shell closures.

  1. Effect of long term target changes on the neutron yield from a low intensity (d, t) neutron generator

    NASA Astrophysics Data System (ADS)

    Dalton, A. W.

    1987-12-01

    Experimental and theoretical techniques have been developed to determine the accuracy with which the integrated neutron output from a low-intensity (d, t) neutron source can be measured during a prolonged irradiation. The experiments involved a neutron generator in which a fixed solid titanium-tritium target and an unanalysed beam of deuterium ions was used. The analysis was based on differential and integral measurements of both the deuterium beam current and the energy spectra of the charged particles emitted from the multiple nuclear interactions in the target during beam bombardment. The overlapping signals produced by the latter are interpreted using an iterative analysis developed at the Lucas Heights Laboratories.

  2. Physics of systems containing neutron stars

    NASA Technical Reports Server (NTRS)

    Shaham, Jacob

    1989-01-01

    The following is a summary of work done during the period of Mar. to Oct. 1989. Three major topics were extensively looked into during this time: the reported 2,000 Hz optical signal from the direction of SNR1987A, the possibility that neutron stellar surface magnetic fields do not decay except when the star is accreting, and the 6 Hz QPOs of LMXBs.

  3. Integrated neutron/gamma-ray portal monitors for nuclear safeguards

    SciTech Connect

    Fehlau, P.E.

    1993-09-01

    Radiation monitoring is one nuclear-safeguards measure used to protect against the theft of special nuclear materials (SNM) by pedestrians departing from SNM access areas. The integrated neutron/gamma-ray portal monitor is an ideal radiation monitor for the task when the SNM is plutonium. It achieves high sensitivity for detecting both bare and shielded plutonium by combining two types of radiation detector. One type is a neutron-chamber detector, comprising a large, hollow, neutron moderator that contains a single thermal-neutron proportional counter. The entrance wall of each chamber is thin to admit slow neutrons from plutonium contained in a moderating shield, while the other walls are thick to moderate fast neutrons from bare or lead-shielded plutonium so that they can be detected. The other type of detector is a plastic scintillator that is primarily for detecting gamma rays from small amounts of unshielded plutonium. The two types of detector are easily integrated by making scintillators part of the thick back wall of each neutron chamber or by inserting them into each chamber void. We compared the influence of the two methods of integration on detecting neutrons and gamma rays, and we examined the effectiveness of other design factors and the methods for signal detection as well.

  4. Short-term natural δ13C and δ18O variations in pools and fluxes in a beech forest: the transfer of isotopic signal from recent photosynthates to soil respired CO2

    NASA Astrophysics Data System (ADS)

    Gavrichkova, O.; Proietti, S.; Moscatello, S.; Portarena, S.; Battistelli, A.; Matteucci, G.; Brugnoli, E.

    2011-10-01

    The fate of photosynthetic products within the plant-soil continuum determines how long the reduced carbon resides within the ecosystem and when it returns back to the atmosphere in the form of respiratory CO2. We have tested the possibility of measuring natural variation in δ13C and δ18O to disentangle the potential times needed to transfer carbohydrates produced by photosynthesis down to trunk, roots and, in general, to belowground up to its further release in the form of soil respiration into the atmosphere in a beech (Fagus sylvatica) forest. We have measured the variation in stable carbon and oxygen isotope compositions in plant material and in soil respired CO2 every three hours for three consecutive days. Possible steps and different signs of post-photosynthetic fractionation during carbon translocation were also identified. A 12 h-periodicity was observed for variation in δ13C in soluble sugars in the top crown leaves and it can be explained by starch day/night dynamics in synthesis and breakdown and by stomatal limitations under elevated vapour pressure deficits. Photosynthetic products were transported down the trunk and mixed with older carbon pools, therefore causing the dampening of the δ13C signal variation. The strongest periodicity of 24 h was found in δ13C in soil respiration indicating changes in root contribution to the total CO2 efflux. Other non-biological causes like diffusion fractionation and advection induced by gas withdrawn from the measurement chamber complicate data interpretation on this step of C transfer path. Nevertheless, it was possible to identify the speed of carbohydrates' translocation from the point of assimilation to the trunk breast height because leaf-imprinted enrichment of δ18O in soluble sugars was less modified along the downward transport and was well related to environmental parameters potentially linked to stomatal conductance. The speed of carbohydrates translocation from the site of assimilation to the trunk

  5. FABRICATION OF NEUTRON SOURCES

    DOEpatents

    Birden, J.H.

    1959-04-21

    A method is presented for preparing a neutron source from polonium-210 and substances, such as beryllium and boron, characterized by emission of neutrons upon exposure to alpha particles from the polonium. According to the invention, a source is prepared by placing powdered beryllium and a platinum foil electroplated with polonium-2;.0 in a beryllium container. The container is sealed and then heated by induction to a temperature of 450 to 1100 deg C to volatilize the polonium off the foil into the powder. The heating step is terminated upon detection of a maximum in the neutron flux level.

  6. METHOD OF PRODUCING NEUTRONS

    DOEpatents

    Imhoff, D.H.; Harker, W.H.

    1964-01-14

    This patent relates to a method of producing neutrons in which there is produced a heated plasma containing heavy hydrogen isotope ions wherein heated ions are injected and confined in an elongated axially symmetric magnetic field having at least one magnetic field gradient region. In accordance with the method herein, the amplitude of the field and gradients are varied at an oscillatory periodic frequency to effect confinement by providing proper ratios of rotational to axial velocity components in the motion of said particles. The energetic neutrons may then be used as in a blanket zone containing a moderator and a source fissionable material to produce heat and thermal neutron fissionable materials. (AEC)

  7. Coupled moderator neutronics

    SciTech Connect

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

    1995-12-01

    Optimizing the neutronic performance of a coupled-moderator system for a Long-Pulse Spallation Source is a new and challenging area for the spallation target-system designer. For optimal performance of a neutron source, it is essential to have good communication with instrument scientists to obtain proper design criteria and continued interaction with mechanical, thermal-hydraulic, and materials engineers to attain a practical design. A good comprehension of the basics of coupled-moderator neutronics will aid in the proper design of a target system for a Long-Pulse Spallation Source.

  8. Fruits of neutron research

    SciTech Connect

    Krause, C.

    1994-12-31

    Car windshields that don`t break during accidents and jets that fly longer without making a refueling stop. Compact discs, credit cards, and pocket calculators. Refrigerator magnets and automatic car window openers. Beach shoes, food packaging, and bulletproof vests made of tough plastics. The quality and range of consumer products have improved steadily since the 1970s. One of the reasons: neutron research. Industries, employing neutron scattering techniques, to study materials properties, to act as diagnostics in tracing system performance, or as sources for radioactive isotopes used in medical fields for diagnostics or treatment, have all benefited from the fruits of advanced work with neutron sources.

  9. NEUTRONIC REACTOR CONTROL

    DOEpatents

    Metcalf, H.E.

    1958-10-14

    Methods of controlling reactors are presented. Specifically, a plurality of neutron absorber members are adjustably disposed in the reactor core at different distances from the center thereof. The absorber members extend into the core from opposite faces thereof and are operated by motive means coupled in a manner to simultaneously withdraw at least one of the absorber members while inserting one of the other absorber members. This feature effects fine control of the neutron reproduction ratio by varying the total volume of the reactor effective in developing the neutronic reaction.

  10. Single-Volume Neutron Scatter Camera for High-Efficiency Neutron Imaging and Source Characterization. Year 2 of 3 Summary

    SciTech Connect

    Brubaker, Erik

    2015-10-01

    The neutron scatter camera (NSC), an imaging spectrometer for fission energy neutrons, is an established and proven detector for nuclear security applications such as weak source detection of special nuclear material (SNM), arms control treaty verification, and emergency response. Relative to competing technologies such as coded aperture imaging, time-encoded imaging, neutron time projection chamber, and various thermal neutron imagers, the NSC provides excellent event-by-event directional information for signal/background discrimination, reasonable imaging resolution, and good energy resolution. Its primary drawback is very low detection efficiency due to the requirement for neutron elastic scatters in two detector cells. We will develop a singlevolume double-scatter neutron imager, in which both neutron scatters can occur in the same large active volume. If successful, the efficiency will be dramatically increased over the current NSC cell-based geometry. If the detection efficiency approaches that of e.g. coded aperture imaging, the other inherent advantages of double-scatter imaging would make it the most attractive fast neutron detector for a wide range of security applications.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Slow dynamics of water molecules in an aqueous solution of lithium chloride probed by neutron spin-echo.

    PubMed

    Mamontov, E; Ohl, M

    2013-07-14

    Aqueous solutions of lithium chloride are uniquely similar to pure water in the parameters such as glass transition temperature, Tg, yet they could be supercooled without freezing down to below 200 K even in the bulk state. This provides advantageous opportunity to study low-temperature dynamics of water molecules in water-like environment in the bulk rather than nano-confined state. Using high-resolution neutron spin-echo data, we argue that the critical temperature, Tc, which is also common between lithium chloride aqueous solutions and pure water, is associated with the split of a secondary relaxation from the main structural relaxation on cooling down. Our results do not allow distinguishing between a well-defined separate secondary relaxation process and the "excess wing" scenario, in which the temperature dependence of the secondary relaxation follows the main relaxation. Importantly, however, in either of these scenarios the secondary relaxation is associated with density-density fluctuations, measurable in a neutron scattering experiment. Neutron scattering could be the only experimental technique with the capability of providing information on the spatial characteristics of the secondary relaxation through the dependence of the signal on the scattering momentum transfer. We propose a simple method for such analysis. PMID:23689686

  13. Solution-grown crystals for neutron radiation detectors, and methods of solution growth

    SciTech Connect

    Zaitseva, Natalia P.; Hull, Giulia; Cherepy, Nerine J.; Payne, Stephen A.; Stoeffl, Wolfgang

    2012-06-26

    A method according to one embodiment includes growing an organic crystal from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source. A system according to one embodiment includes an organic crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source; and a photodetector for detecting the signal response of the organic crystal. A method according to another embodiment includes growing an organic crystal from solution, the organic crystal being large enough to exhibit a detectable signal response signature for neutrons from a radioactive source. An organic crystal according to another embodiment includes an organic crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source, wherein the organic crystal has a length of greater than about 1 mm in one dimension.

  14. Modeling the signal transfer of sea water δ18O to the δ18O of atmospheric oxygen using a diagnostic box model for the terrestrial and marine biosphere

    NASA Astrophysics Data System (ADS)

    Leuenberger, Markus C.

    1997-11-01

    We make use of a simple diagnostic box model to determine the sensitivities of the influencing parameters for the isotopic signal transfer of seawater oxygen to atmospheric oxygen. We calculate the δ18O of atmospheric oxygen from prescribed oxygen fluxes of the living and dead biomes on land and in the ocean, respectively. The model is driven by an assumed (experiment 1) or measured (experiments 2 and 3) temporal seawater δ18O signal and a land biomass estimation. In experiment 1, we calculated the required changes of several model parameters in order to study fast variations of δ18O of atmospheric oxygen as seen in the Greenland Ice Core Project (GRIP) ice at depths assigned to the Eemian time period. Our calculations support evidence of stratigraphic problems at these depths in the GRIP ice core. In experiment 2, we adjusted the model output, which was driven by the benthic seawater δ18O record from V19-30, to the measured Greenland Ice Sheet Project 2 δ18O record of atmospheric oxygen for the last 110,000 years, by varying the model parameter. Single and multi-parameter matchings were performed. The results for single-parameter runs exceed the uncertainty ranges for most of the parameters, while multiparameter variations are well within these ranges. The model calculations are most sensitive to the land respiration factor. Our results support the findings of Van de Water et al. [1994] that the fractionations associated with biomes activities were most probably lower during cold periods, which could point to a combination of fractionations with different temperature dependencies. The model results indicate periods of higher marine biological activity during the ice age than today. Temporal variations of the model parameters show a double peak around 10000 and 8000 years ago, which could be associated with meltwater pulses, as shown in experiment 3. However, they are hardly the well-known Fairbanks [Fairbanks et al., 1992] pulses since these occur 3000 to

  15. Isotope-Identifying neutron reflectometry

    SciTech Connect

    Nikitenko, Yu. V. Petrenko, A. V.; Gundorin, N. A.; Gledenov, Yu. M.; Aksenov, V. L.

    2015-07-15

    The possibilities of an isotope-indentifying study of layered structures in different regimes of a neutron wave field are considered. The detection of specularly reflected neutrons and secondary radiation (caused by neutron capture) in the form of charged particles, γ quanta, and nuclear fission fragments, as well as neutrons spin-flipped in a noncollinear magnetic field and on nuclei of elements with spin, makes it possible to implement isotope-indentifying neutron reflectometry.

  16. Switchable radioactive neutron source device

    DOEpatents

    Boyar, Robert E.; DeVolpi, Alexander; Stanford, George S.; Rhodes, Edgar A.

    1989-01-01

    This invention is a switchable neutron generating apparatus comprised of a pair of plates, the first plate having an alpha emitter section on it and the second plate having a target material portion on it which generates neutrons when its nuclei absorb an alpha particle. In operation, the alpha portion of the first plate is aligned with the neutron portion of the second plate to produce neutrons and brought out of alignment to cease production of neutrons.

  17. Switchable radioactive neutron source device

    DOEpatents

    Stanford, G.S.; Rhodes, E.A.; Devolpi, A.; Boyar, R.E.

    1987-11-06

    This invention is a switchable neutron generating apparatus comprised of a pair of plates, the first plate having an alpha emitter section on it and the second plate having a target material portion on it which generates neutrons when its nuclei absorb an alpha particle. In operation, the alpha portion of the first plate is aligned with the neutron portion of the second plate to produce neutrons and brought out of alignment to cease production of neutrons. 3 figs.

  18. Multigroup neutron dose calculations for proton therapy

    SciTech Connect

    Kelsey Iv, Charles T; Prinja, Anil K

    2009-01-01

    We have developed tools for the preparation of coupled multigroup proton/neutron cross section libraries. Our method is to use NJOY to process evaluated nuclear data files for incident particles below 150 MeV and MCNPX to produce data for higher energies. We modified the XSEX3 program of the MCNPX code system to produce Legendre expansions of scattering matrices generated by sampling the physics models that are comparable to the output of the GROUPR routine of NJOY. Our code combines the low and high energy scattering data with user input stopping powers and energy deposition cross sections that we also calculated using MCNPX. Our code also calculates momentum transfer coefficients for the library and optionally applies an energy straggling model to the scattering cross sections and stopping powers. The motivation was initially for deterministic solution of space radiation shielding calculations using Attila, but noting that proton therapy treatment planning may neglect secondary neutron dose assessments because of difficulty and expense, we have also investigated the feasibility of multi group methods for this application. We have shown that multigroup MCNPX solutions for secondary neutron dose compare well with continuous energy solutions and are obtainable with less than half computational cost. This efficiency comparison neglects the cost of preparing the library data, but this becomes negligible when distributed over many multi group calculations. Our deterministic calculations illustrate recognized obstacles that may have to be overcome before discrete ordinates methods can be efficient alternatives for proton therapy neutron dose calculations.

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

    SciTech Connect

    Cooper, Robert Lee; Marleau, Peter; Griffin, Patrick J.

    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.

  20. SPHERES, Jülich's high-flux neutron backscattering spectrometer at FRM II.

    PubMed

    Wuttke, Joachim; Budwig, Alfred; Drochner, Matthias; Kämmerling, Hans; Kayser, Franz-Joseph; Kleines, Harald; Ossovyi, Vladimir; Pardo, Luis Carlos; Prager, Michael; Richter, Dieter; Schneider, Gerald J; Schneider, Harald; Staringer, Simon

    2012-07-01

    SPHERES is a third-generation neutron backscattering spectrometer, located at the 20 MW German neutron source FRM II and operated by the Jülich Centre for Neutron Science. It offers an energy resolution (fwhm) better than 0.65 μeV, a dynamic range of ± 31 μeV, and a signal-to-noise ratio of up to 1750:1.

  1. SPHERES, Juelich's high-flux neutron backscattering spectrometer at FRM II

    SciTech Connect

    Wuttke, Joachim; Budwig, Alfred; Drochner, Matthias; Kaemmerling, Hans; Kayser, Franz-Joseph; Kleines, Harald; Ossovyi, Vladimir; Pardo, Luis Carlos; Prager, Michael; Richter, Dieter; Schneider, Gerald J.; Schneider, Harald; Staringer, Simon

    2012-07-15

    SPHERES is a third-generation neutron backscattering spectrometer, located at the 20 MW German neutron source FRM II and operated by the Juelich Centre for Neutron Science. It offers an energy resolution (fwhm) better than 0.65 {mu}eV, a dynamic range of {+-} 31 {mu}eV, and a signal-to-noise ratio of up to 1750:1.

  2. Neutron personnel dosimetry

    SciTech Connect

    Griffith, R.V.

    1981-06-16

    The current state-of-the-art in neutron personnel dosimetry is reviewed. Topics covered include dosimetry needs and alternatives, current dosimetry approaches, personnel monitoring devices, calibration strategies, and future developments. (ACR)

  3. NEUTRON-COUNTER

    DOEpatents

    Gunst, S.B.; Bayard, R.T.

    1960-12-20

    A heat- aud pressure-resistant radiation counter adaptable to the counting of thermal neutrons comprising a spheroidal chamber electrode having a coating of fissionable material and containing a spherical electrode is described.

  4. Temperature of neutron stars

    NASA Astrophysics Data System (ADS)

    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.

  5. Cooling of neutron stars

    NASA Technical Reports Server (NTRS)

    Pethick, C. J.

    1992-01-01

    It is at present impossible to predict the interior constitution of neutron stars based on theory and results from laboratory studies. It has been proposed that it is possible to obtain information on neutron star interiors by studying thermal radiation from their surfaces, because neutrino emission rates, and hence the temperature of the central part of a neutron star, depend on the properties of dense matter. The theory predicts that neutron stars cool relatively slowly if their cores are made up of nucleons, and cool faster if the matter is in an exotic state, such as a pion condensate, a kaon condensate, or quark matter. This view has recently been questioned by the discovery of a number of other processes that could lead to copious neutrino emission and rapid cooling.

  6. Neutron resonance averaging

    SciTech Connect

    Chrien, R.E.

    1986-10-01

    The principles of resonance averaging as applied to neutron capture reactions are described. Several illustrations of resonance averaging to problems of nuclear structure and the distribution of radiative strength in nuclei are provided. 30 refs., 12 figs.

  7. NEUTRONIC REACTOR FUEL COMPOSITION

    DOEpatents

    Thurber, W.C.

    1961-01-10

    Uranium-aluminum alloys in which boron is homogeneously dispersed by adding it as a nickel boride are described. These compositions have particular utility as fuels for neutronic reactors, boron being present as a burnable poison.

  8. Cylindrical neutron generator

    DOEpatents

    Leung, Ka-Ngo

    2008-04-22

    A cylindrical neutron generator is formed with a coaxial RF-driven plasma ion source and target. A deuterium (or deuterium and tritium) plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical neutron generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which contain many slots. The plasma generator emanates ions radially over 360.degree. and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired. The plasma generator may be in the center and the neutron target on the outside, or the plasma generator may be on the outside and the target on the inside. In a nested configuration, several concentric targets and plasma generating regions are nested to increase the neutron flux.

  9. Cylindrical neutron generator

    DOEpatents

    Leung, Ka-Ngo

    2005-06-14

    A cylindrical neutron generator is formed with a coaxial RF-driven plasma ion source and target. A deuterium (or deuterium and tritium) plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical neutron generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which contain many slots. The plasma generator emanates ions radially over 360.degree. and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired. The plasma generator may be in the center and the neutron target on the outside, or the plasma generator may be on the outside and the target on the inside. In a nested configuration, several concentric targets and plasma generating regions are nested to increase the neutron flux.

  10. Cylindrical neutron generator

    DOEpatents

    Leung, Ka-Ngo

    2009-12-29

    A cylindrical neutron generator is formed with a coaxial RF-driven plasma ion source and target. A deuterium (or deuterium and tritium) plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical neutron generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which contain many slots. The plasma generator emanates ions radially over 360.degree. and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired. The plasma generator may be in the center and the neutron target on the outside, or the plasma generator may be on the outside and the target on the inside. In a nested configuration, several concentric targets and plasma generating regions are nested to increase the neutron flux.

  11. Boronated antibodies and promazine derivatives for potential neutron capture therapy

    SciTech Connect

    Alam, F.; Soloway, A.H.; Barth, R.F.; Adams, D.M.; Mafune, N.

    1986-01-01

    The theoretical basis for boron neutron capture therapy (BNCT) derives from the irradiation of /sup 10/B with thermal neutrons, resulting in a fission reaction yielding /sup 7/Li and alpha particles. The fission products have short path lengths and high linear energy transfer (LET). Each component of this binary system, thermal neutrons and /sup 10/B, independently are nontumoricidal, but together they can be highly lethal. Success depends on localizing enough of the /sup 10/B (approx.20 ..mu..g/g of tumor) and delivering a requisite fluence of thermal neutrons (approx.10/sup 13/ n/cm/sup 9/) at the site of the tumor. This report describes the boronation of antibodies and the development of boron-containing promazine derivatives to selectively deliver /sup 10/B to tumor cells for BNCT.

  12. Fast neutron-gamma discrimination on neutron emission profile measurement on JT-60U

    SciTech Connect

    Ishii, K.; Okamoto, A.; Kitajima, S.; Sasao, M.; Shinohara, K.; Ishikawa, M.; Baba, M.; Isobe, M.

    2010-10-15

    A digital signal processing (DSP) system is applied to stilbene scintillation detectors of the multichannel neutron emission profile monitor in JT-60U. Automatic analysis of the neutron-{gamma} pulse shape discrimination is a key issue to diminish the processing time in the DSP system, and it has been applied using the two-dimensional (2D) map. Linear discriminant function is used to determine the dividing line between neutron events and {gamma}-ray events on a 2D map. In order to verify the validity of the dividing line determination, the pulse shape discrimination quality is evaluated. As a result, the {gamma}-ray contamination in most of the beam heating phase was negligible compared with the statistical error with 10 ms time resolution.

  13. Proton-transfer dynamics in the hydrogen bond. Inelastic neutron scattering, infrared and Raman spectra of KH(CF 3COO) 2 and CsH(CF 3COO) 2

    NASA Astrophysics Data System (ADS)

    Fillaux, F.; Tomkinson, J.

    1991-12-01

    Inelastic neutron scattering (INS), infrared and Raman spectra of potassium and cesium hydrogen bistrifluoroacetate (KH(CF 3COO) 2 and CsH(CF 3COO) 2, respectively) at 20 K are reported. In both crystals H(CF 3COO) 2- centrosymmetric dimers are linked by strong hydrogen bonds, whose lengths are 2.435 and 2.38 Å, respectively. The principal OH modes appear at the same frequencies for both compounds. The OH stretching band shapes are similar in infrared and in INS. The submaxima are attributed to interactions with other internal modes. Below 200 cm -1, the cesium salt shows three narrow bands which emerge from the density-of-states. They are assigned to localized modes involving the proton. A sharp band at 87 cm -1 corresponds to the "tunnelling" transition in a quasi-symmetric double-minimum potential with a barrier height of 1340 cm -1. The other two narrow bands, at 36 and 49 cm -1, are assigned to the internal torsions of coupled CF 3COO groups. Potential barriers are estimated. A detailed band-shape analysis of the OH bending modes provides clear indications of different dynamics for the two salts. KH(CF 3COO) 2 is rather stiff and phonon wings involving the whole lattice density-of-states are observed for the δOH mode but not for the γOH mode. For this latter, the observed combinations indicate a dynamical coupling with the internal torsion. CsH(CF 3COO) 2 is rather soft and recoil occurs. The INS intensities of the OH bending modes are decreased by Debye-Waller factors and their frequencies are shifted upwards. The estimated masses of the recoiling particles are consistent with strong dynamical coupling of the γOH with the torsional mode on the one hand, and of the δOH with translational modes on the other. The polarizability of the counter ion appears to play a leading role in proton dynamics.

  14. FABRICATION OF NEUTRON SOURCES

    DOEpatents

    Birden, J.H.

    1959-01-20

    A method is presented for preparing a more efficient neutron source comprising inserting in a container a quantity of Po-210, inserting B powder coated with either Ag, Pt, or Ni. The container is sealed and then slowly heated to about 450 C to volatilize the Po and effect combination of the coated powder with the Po. The neutron flux emitted by the unit is moritored and the heating step is terminated when the flux reaches a maximum or selected level.

  15. NEUTRON FLUX INTENSITY DETECTION

    DOEpatents

    Russell, J.T.

    1964-04-21

    A method of measuring the instantaneous intensity of neutron flux in the core of a nuclear reactor is described. A target gas capable of being transmuted by neutron bombardment to a product having a resonance absorption line nt a particular microwave frequency is passed through the core of the reactor. Frequency-modulated microwave energy is passed through the target gas and the attenuation of the energy due to the formation of the transmuted product is measured. (AEC)

  16. Pulsed spallation neutron sources

    SciTech Connect

    Carpenter, J.M.

    1996-05-01

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

  17. Neutron ion temperature measurement

    SciTech Connect

    Strachan, J.D.; Hendel, H.W.; Lovberg, J.; Nieschmidt, E.B.

    1986-11-01

    One important use of fusion product diagnostics is in the determination of the deuterium ion temperature from the magnitude of the 2.5 MeV d(d,n)/sup 3/He neutron emission. The detectors, calibration methods, and limitations of this technique are reviewed here with emphasis on procedures used at PPPL. In most tokamaks, the ion temperature deduced from neutrons is in reasonable agreement with the ion temperature deduced by other techniques.

  18. Pulsed spallation Neutron Sources

    SciTech Connect

    Carpenter, J.M.

    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.

  19. Characterization of a prototype neutron portal monitor detector

    NASA Astrophysics Data System (ADS)

    Nakhoul, Nabil

    The main objective of this thesis is to provide characterization measurements on a prototype neutron portal monitor (NPM) detector constructed at the University of Massachusetts Lowell. NPM detectors are deployed at all United States border crossings and shipping ports to stop the illicit transfer of weapons-grade plutonium (WGPu) into our country. This large prototype detector with its 0.93 square meter face area is based on thermal neutron capture in 6Li as an alternate technology to the current, very expensive, 3He-based NPM. A neutron detection efficiency of 27.5 % is measured with a 252Cf source which has a spontaneous fission neutron spectrum very similar to that of 240Pu in WGPu. Measurements with an intense 137Cs source establish the extreme insensitivity of the prototype NPM to gamma-ray backgrounds with only one additional count registered for 1.1 million incident gamma rays. This detector also has the ability to locate neutron sources to within an angle of a few degrees. Its sensitivity is further demonstrated by discovering in a few-second measurement the presence of a 2 curie PuBe neutron source even at a distance of 95.5 feet. This thesis also covers in considerable detail the design features that give rise to both a high intrinsic neutron detection efficiency and an extreme gamma-ray insensitivity.

  20. Neutron scattering in Australia

    SciTech Connect

    Knott, R.B.

    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.