Science.gov

Sample records for neutron current formulations

  1. A quasilinear formulation of turbulence driven current

    NASA Astrophysics Data System (ADS)

    McDevitt, C. J.; Tang, Xian-Zhu; Guo, Zehua

    2014-02-01

    Non-inductive current drive mechanisms, such as the familiar neoclassical bootstrap current correspond to an essential component to the realization of steady state tokamak operation. In this work, we discuss a novel collisionless mechanism through which a mean plasma current may be driven in the presence of microturbulence. In analogy with the traditional neoclassical bootstrap current drive mechanism, in which the collisional equilibrium established between trapped and passing electrons results in the formation of a steady state plasma current, here we show that resonant scattering of electrons by drift wave microturbulence provides an additional means of determining the equilibrium between trapped and passing electrons. The resulting collisionless equilibrium is shown to result in the formation of an equilibrium current whose magnitude is a function of the thermodynamic forces. A mean field formulation is utilized to incorporate the above components into a unified framework through which both collisional as well as collisionless current drive mechanisms may be self-consistently treated. Utilizing a linearized Fokker-Planck collision operator, the plasma current in the presence of both collisions as well as turbulent stresses is computed, allowing for the relative strength of these two mechanisms to be quantified as a function of collisionality and fluctuation amplitude.

  2. A Quasilinear Formulation of Turbulence Driven Current

    NASA Astrophysics Data System (ADS)

    McDevitt, C. J.; Tang, X. Z.; Guo, Z. H.

    2012-10-01

    Non-inductive current drive mechanisms such as the familiar bootstrap current correspond to an essential component to the realization of steady state tokamak operation. In this work we discuss a novel collisionless mechanism through which a mean plasma current may be driven in the presence of microturbulence (as seen in [1]). In analogy with the traditional bootstrap current drive mechanism, in which the collisional equilibrium established between trapped and passing particles results in the formation of a steady state plasma current, here we show that velocity space scattering by drift wave microturbulence is capable of modifying the equilibrium between trapped and passing particles leading to the generation of a mean plasma current. In the collisionless limit, this current drive mechanism can in turn be balanced either by turbulence mediated electron-ion momentum exchange or radial electron momentum transport. A mean field formulation is utilized to incorporate the above components into a unified framework through which both collisional as well as collisionless current drive mechanisms may be self-consistently treated. [4pt] [1] W. X. Wang et al., 53rd APS-DPP, Salt Lake City, Utah, 2011

  3. A quasilinear formulation of turbulence driven current

    SciTech Connect

    McDevitt, C. J.; Tang, Xian-Zhu; Guo, Zehua

    2014-02-15

    Non-inductive current drive mechanisms, such as the familiar neoclassical bootstrap current correspond to an essential component to the realization of steady state tokamak operation. In this work, we discuss a novel collisionless mechanism through which a mean plasma current may be driven in the presence of microturbulence. In analogy with the traditional neoclassical bootstrap current drive mechanism, in which the collisional equilibrium established between trapped and passing electrons results in the formation of a steady state plasma current, here we show that resonant scattering of electrons by drift wave microturbulence provides an additional means of determining the equilibrium between trapped and passing electrons. The resulting collisionless equilibrium is shown to result in the formation of an equilibrium current whose magnitude is a function of the thermodynamic forces. A mean field formulation is utilized to incorporate the above components into a unified framework through which both collisional as well as collisionless current drive mechanisms may be self-consistently treated. Utilizing a linearized Fokker-Planck collision operator, the plasma current in the presence of both collisions as well as turbulent stresses is computed, allowing for the relative strength of these two mechanisms to be quantified as a function of collisionality and fluctuation amplitude.

  4. Equivalent source current formulation in impedance tomography

    NASA Astrophysics Data System (ADS)

    Ilmoniemi, Risto J.; Ahlfors, Seppo P.

    1994-04-01

    Changes in the conductivity distribution of a body modify the electromagnetic field due to injected current in the same way as an equivalent source current distribution J(sup eq)(r) does. In the limit of small perturbations, it is shown that J(sup eq)(r) = Sigma(sup 1)(r)E(sup 0)(r), where Sigma(sup 1)(r) is a deviation in the conductivity and E(sup 0)(r) is the non-perturbed electric field. A model experiment demonstrates how a conductivity anomaly can be located using the minimum-norm estimate of the equivalent currents. The minimum-norm solution for small perturbation Sigma(sup 1)(r) is derived as well. The equivalent-source formulation allows the direct application of biomagnetic and bioelectric source-determination methods to conductivity imaging.

  5. SPALLATION NEUTRON SOURCE BEAM CURRENT MONITOR ELECTRONICS.

    SciTech Connect

    KESSELMAN,M.; DAWSON,W.C.

    2002-05-06

    This paper will discuss the present electronics design for the beam current monitor system to be used throughout the Spallation Neutron Source (SNS) under construction at Oak Ridge National Laboratory. The beam is composed of a micro-pulse structure due to the 402.5MHz RF, and is chopped into mini-pulses of 645ns duration with a 300ns gap, providing a macro-pulse of 1060 mini-pulses repeating at a 60Hz rate. Ring beam current will vary from about 15ma peak during studies, to about 50Amps peak (design to 100 amps). A digital approach to droop compensation has been implemented and initial test results presented.

  6. Flexibility in formulating and processing SYNROC D: a current assessment

    SciTech Connect

    Campbell, J.H.; Ryerson, F.J.; Rozsa, R.B.; Hoenig, C.L.

    1982-03-01

    In a recent series of papers, the authors have addressed the formulation, preparation, characterization and performance testing of SYNROC containing SRP defense wastes. They have also recently published a brief description of the SYNROC process flow sheets and a schematic layout of an associate processing facility. In this brief paper they summarize current data and discuss the implications of: (1) the flexibility of the SYNROC formulation to accommodate unanticipated changes in feed composition; and (2) recent reductions in complexity of the SYNROC process. In regard to formulation, it is important to realize that only four additives (TiO/sub 2/, ZrO/sub 2/, CaO and SiO/sub 2/) are used in the preparation of SYNROC containing SRP defense waste. Further, they have found that components in the waste sludge feed can vary by as much as +- 50% in composition without affecting either the quantity of SYNROC additives needed or the quality of the final product. Their experience shows the SYNROC formulation to be very tolerant of wide variations in feed composition and thus very forgiving of feed stream upsets. The SNROC-D process, at the present state (2 years R and D) is less developed than the more mature (greater than 15 years R and D) borosilicate glass process. This is expected. SYNROC is a new waste form and nearly all research has been directed toward lab synthesis and testing of the product. However, over the past year, the authors have undertaken an engineering research effort that has reduced the number of major process unit operations from six to three and increased our production capacity 50 fold. The major advances have been in: (1) simplifying the mixing and blending of additives with waste; and (2) combining and simplifying drying, calcination and redox-control operations. We expect further significant reductions in the number, size and complexity of the SYNROC process steps as engineering R and D continues.

  7. Accurate Relations Between the Neutron Current Densities and the Neutron Fluxes

    SciTech Connect

    Ronen, Yigal

    2004-02-15

    Accurate relations between neutron current densities and neutron flux are obtained using the integral transport equation. Using these relations and Fick's Law, diffusion constants can be calculated. These diffusion constants are better than those usually used for the cases in which {sigma}{sub a}/{sigma}{sub s} is not small.

  8. Gyrotron-driven high current ECR ion source for boron-neutron capture therapy neutron generator

    NASA Astrophysics Data System (ADS)

    Skalyga, V.; Izotov, I.; Golubev, S.; Razin, S.; Sidorov, A.; Maslennikova, A.; Volovecky, A.; Kalvas, T.; Koivisto, H.; Tarvainen, O.

    2014-12-01

    Boron-neutron capture therapy (BNCT) is a perspective treatment method for radiation resistant tumors. Unfortunately its development is strongly held back by a several physical and medical problems. Neutron sources for BNCT currently are limited to nuclear reactors and accelerators. For wide spread of BNCT investigations more compact and cheap neutron source would be much more preferable. In present paper an approach for compact D-D neutron generator creation based on a high current ECR ion source is suggested. Results on dense proton beams production are presented. A possibility of ion beams formation with current density up to 600 mA/cm2 is demonstrated. Estimations based on obtained experimental results show that neutron target bombarded by such deuteron beams would theoretically yield a neutron flux density up to 6·1010 cm-2/s. Thus, neutron generator based on a high-current deuteron ECR source with a powerful plasma heating by gyrotron radiation could fulfill the BNCT requirements significantly lower price, smaller size and ease of operation in comparison with existing reactors and accelerators.

  9. A neutron diagnostic for high current deuterium beams

    SciTech Connect

    Rebai, M.; Perelli Cippo, E.; Cavenago, M.; Dalla Palma, M.; Pasqualotto, R.; Tollin, M.; Croci, G.; Gervasini, G.; Ghezzi, F.; Grosso, G.; Tardocchi, M.; Murtas, F.; Gorini, G.

    2012-02-15

    A neutron diagnostic for high current deuterium beams is proposed for installation on the spectral shear interferometry for direct electric field reconstruction (SPIDER, Source for Production of Ion of Deuterium Extracted from RF plasma) test beam facility. The proposed detection system is called Close-contact Neutron Emission Surface Mapping (CNESM). The diagnostic aims at providing the map of the neutron emission on the beam dump surface by placing a detector in close contact, right behind the dump. CNESM uses gas electron multiplier detectors equipped with a cathode that also serves as neutron-proton converter foil. The cathode is made of a thin polythene film and an aluminium film; it is designed for detection of neutrons of energy >2.2 MeV with an incidence angle < 45 deg. CNESM was designed on the basis of simulations of the different steps from the deuteron beam interaction with the beam dump to the neutron detection in the nGEM. Neutron scattering was simulated with the MCNPX code. CNESM on SPIDER is a first step towards the application of this diagnostic technique to the MITICA beam test facility, where it will be used to resolve the horizontal profile of the beam intensity.

  10. Neutron detection using a current biased kinetic inductance detector

    NASA Astrophysics Data System (ADS)

    Shishido, Hiroaki; Miyajima, Shigeyuki; Narukami, Yoshito; Oikawa, Kenichi; Harada, Masahide; Oku, Takayuki; Arai, Masatoshi; Hidaka, Mutsuo; Fujimaki, Akira; Ishida, Takekazu

    2015-12-01

    We demonstrate neutron detection using a solid state superconducting current biased kinetic inductance detector (CB-KID), which consists of a superconducting Nb meander line of 1 μm width and 40 nm thickness. 10B-enriched neutron absorber layer of 150 nm thickness is placed on top of the CB-KID. Our neutron detectors are able to operate in a wide superconducting region in the bias current-temperature diagram. This is in sharp contrast with our preceding current-biased transition edge detector, which can operate only in a narrow range just below the superconducting critical temperature. The full width at half maximum of the signals remains of the order of a few tens of ns, which confirms the high speed operation of our detectors.

  11. Neutron detection using a current biased kinetic inductance detector

    SciTech Connect

    Shishido, Hiroaki Miyajima, Shigeyuki; Ishida, Takekazu; Narukami, Yoshito; Oikawa, Kenichi; Harada, Masahide; Oku, Takayuki; Arai, Masatoshi; Hidaka, Mutsuo; Fujimaki, Akira

    2015-12-07

    We demonstrate neutron detection using a solid state superconducting current biased kinetic inductance detector (CB-KID), which consists of a superconducting Nb meander line of 1 μm width and 40 nm thickness. {sup 10}B-enriched neutron absorber layer of 150 nm thickness is placed on top of the CB-KID. Our neutron detectors are able to operate in a wide superconducting region in the bias current–temperature diagram. This is in sharp contrast with our preceding current-biased transition edge detector, which can operate only in a narrow range just below the superconducting critical temperature. The full width at half maximum of the signals remains of the order of a few tens of ns, which confirms the high speed operation of our detectors.

  12. Electromagnetic Emission from Long-lived Binary Neutron Star Merger Remnants. I. Formulation of the Problem

    NASA Astrophysics Data System (ADS)

    Siegel, Daniel M.; Ciolfi, Riccardo

    2016-03-01

    Binary neutron star (BNS) mergers are the leading model to explain the phenomenology of short gamma-ray bursts (SGRBs). Recent observations of long-lasting X-ray afterglows of SGRBs challenge standard paradigms and indicate that in a large fraction of events a long-lived neutron star (NS) may be formed rather than a black hole. Understanding the mechanisms underlying these afterglows is necessary in order to address the open questions concerning the nature of SGRB central engines. However, recent theoretical progress has been hampered by the fact that the timescales of interest for the afterglow emission are inaccessible to numerical relativity simulations. Here we present a detailed model to bridge the gap between numerical simulations of the merger process and the relevant timescales for the afterglows, assuming that the merger results in a long-lived NS. This model is formulated in terms of a set of coupled differential equations that follow the evolution of the post-merger system and predict its electromagnetic (EM) emission in a self-consistent way, starting from initial data that can be extracted from BNS merger simulations. The model presented here also allows us to search for suitable EM counterparts for multimessenger astronomy, which is expected to become reality within the next few years thanks to ground-based GW detectors such as advanced LIGO and Virgo. This paper discusses the formulation and implementation of the model. In a companion paper, we employ this model to predict the EM emission from ∼ {10}-2 to ∼ {10}7 {{s}} after a BNS merger and discuss the implications in the context of SGRBs and multimessenger astronomy.

  13. Induced electric current-based formulation in computations of low magnetic Reynolds number magnetohydrodynamic flows

    NASA Astrophysics Data System (ADS)

    Smolentsev, S.; Cuevas, S.; Beltrán, A.

    2010-03-01

    We use the induced electric current as the main electromagnetic variable to compute low magnetic Reynolds number magnetohydrodynamic (MHD) flows. The equation for the induced electric current is derived by taking the curl of the induction equation and using Ampère's law. Boundary conditions on the induced electric current are derived at the interface between the liquid and the thin conducting wall by considering the current loop closing in the wall and the adjacent liquid. These boundary conditions at the liquid-solid interface include the Robin boundary condition for the wall-normal component of the current and an additional equation for the wall potential to compute the tangential current component. The suggested formulation (denominated j-formulation) is applied to three common types of MHD wall-bounded flows by implementing the finite-difference technique: (i) high Hartmann number fully developed flows in a rectangular duct with conducting walls; (ii) quasi-two-dimensional duct flow in the entry into a magnet; and (iii) flow past a magnetic obstacle. Comparisons have been performed against the traditional formulation based on the induced magnetic field ( B-formulation), demonstrating very good agreement.

  14. Current status of the PSG Monte Carlo neutron transport code

    SciTech Connect

    Leppaenen, J.

    2006-07-01

    PSG is a new Monte Carlo neutron transport code, developed at the Technical Research Centre of Finland (VTT). The code is mainly intended for fuel assembly-level reactor physics calculations, such as group constant generation for deterministic reactor simulator codes. This paper presents the current status of the project and the essential capabilities of the code. Although the main application of PSG is in lattice calculations, the geometry is not restricted in two dimensions. This paper presents the validation of PSG against the experimental results of the three-dimensional MOX fuelled VENUS-2 reactor dosimetry benchmark. (authors)

  15. A time-dependent neutron transport method of characteristics formulation with time derivative propagation

    NASA Astrophysics Data System (ADS)

    Hoffman, Adam J.; Lee, John C.

    2016-02-01

    A new time-dependent Method of Characteristics (MOC) formulation for nuclear reactor kinetics was developed utilizing angular flux time-derivative propagation. This method avoids the requirement of storing the angular flux at previous points in time to represent a discretized time derivative; instead, an equation for the angular flux time derivative along 1D spatial characteristics is derived and solved concurrently with the 1D transport characteristic equation. This approach allows the angular flux time derivative to be recast principally in terms of the neutron source time derivatives, which are approximated to high-order accuracy using the backward differentiation formula (BDF). This approach, called Source Derivative Propagation (SDP), drastically reduces the memory requirements of time-dependent MOC relative to methods that require storing the angular flux. An SDP method was developed for 2D and 3D applications and implemented in the computer code DeCART in 2D. DeCART was used to model two reactor transient benchmarks: a modified TWIGL problem and a C5G7 transient. The SDP method accurately and efficiently replicated the solution of the conventional time-dependent MOC method using two orders of magnitude less memory.

  16. CURRENT PROBLEMS AND EXPECTED IMPROVEMENTS IN PERSONAL NEUTRON DOSIMETRY

    SciTech Connect

    McDonald, Joseph C.

    2004-12-15

    Recent progress has been made in the development of devices and techniques for the measurement and calibration of neutron personal dosimeters. The quantities and units used to express neutron dose equivalents are being improved and clarified. Therefore, it is expected that a number of remaining difficulties with neutron dosimetry will be mitigated.

  17. Current and emerging formulation strategies for the effective transdermal delivery of HIV inhibitors

    PubMed Central

    Ham, Anthony S; Buckheit, Robert W

    2015-01-01

    Current and emerging formulation strategies for skin permeation are poised to open the transdermal drug delivery to a broader range of small molecule compounds that do not fit the traditional requirements for successful transdermal drug delivery, allowing the development of new patch technologies to deliver antiretroviral drugs that were previously incapable of being delivered through transdermal means. Transdermal drug delivery offers several distinct advantages over traditional dosage forms. Current antiretroviral drugs used for the treatment of HIV infection include a variety of highly active small molecule compounds with significantly limited skin permeability, and thus new and novel means of enhancing transport through the skin are needed. Current and emerging formulation strategies are poised to open the transdermal drug delivery to a broader range of compounds that do not fit the traditional requirements for successful transdermal drug delivery, allowing the development of new patch technologies to deliver antiretroviral drugs that were previously incapable of being delivered through transdermal means. Thus, with continuing research into skin permeability and patch formulation strategies, there is a large potential for antiretroviral transdermal drug delivery. PMID:25690088

  18. 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.

  19. Formulation approaches to pediatric oral drug delivery: benefits and limitations of current platforms

    PubMed Central

    Lopez, Felipe L; Ernest, Terry B; Tuleu, Catherine; Gul, Mine Orlu

    2015-01-01

    Introduction: Most conventional drug delivery systems are not acceptable for pediatric patients as they differ in their developmental status and dosing requirements from other subsets of the population. Technology platforms are required to aid the development of age-appropriate medicines to maximize patient acceptability while maintaining safety, efficacy, accessibility and affordability. Areas covered: The current approaches and novel developments in the field of age-appropriate drug delivery for pediatric patients are critically discussed including patient-centric formulations, administration devices and packaging systems. Expert opinion: Despite the incentives provided by recent regulatory modifications and the efforts of formulation scientists, there is still a need for implementation of pharmaceutical technologies that enable the manufacture of licensed age-appropriate formulations. Harmonization of endeavors from regulators, industry and academia by sharing learning associated with data obtained from pediatric investigation plans, product development pathways and scientific projects would be the way forward to speed up bench-to-market age appropriate formulation development. A collaborative approach will benefit not only pediatrics, but other patient populations such as geriatrics would also benefit from an accelerated patient-centric approach to drug delivery. PMID:26165848

  20. 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

  1. Current Status and Future Works of Neutron Scattering Laboratory at BATAN in Serpong

    SciTech Connect

    Ikram, A.

    2008-03-17

    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 and 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

  2. 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

  3. High-Current Experiments for Accelerator-Based Neutron Capture Therapy Applications

    SciTech Connect

    Gierga, D.P.; Klinkowstein, R.E.; Hughey, B.H.; Shefer, R.E.; Yanch, J.C.; Blackburn, B.W.

    1999-06-06

    Several accelerator-based neutron capture therapy applications are under development. These applications include boron neutron capture therapy for glioblastoma multiform and boron neutron capture synovectomy (BNCS) for rheumatoid arthritis. These modalities use accelerator-based charged-particle reactions to create a suitable neutron source. Neutrons are produced using a high-current, 2-MV terminal tandem accelerator. For these applications to be feasible, high accelerator beam currents must be routinely achievable. An effort was undertaken to explore the operating regime of the accelerator in the milliampere range. In preparation for high-current operation of the accelerator, computer simulations of charged-particle beam optics were performed to establish high-current operating conditions. Herein we describe high beam current simulations and high beam current operation of the accelerator.

  4. A review on bioadhesive buccal drug delivery systems: current status of formulation and evaluation methods

    PubMed Central

    Chinna Reddy, P; Chaitanya, K.S.C.; Madhusudan Rao, Y.

    2011-01-01

    Owing to the ease of the administration, the oral cavity is an attractive site for the delivery of drugs. Through this route it is possible to realize mucosal (local effect) and transmucosal (systemic effect) drug administration. In the first case, the aim is to achieve a site-specific release of the drug on the mucosa, whereas the second case involves drug absorption through the mucosal barrier to reach the systemic circulation. The main obstacles that drugs meet when administered via the buccal route derive from the limited absorption area and the barrier properties of the mucosa. The effective physiological removal mechanisms of the oral cavity that take the formulation away from the absorption site are the other obstacles that have to be considered. The strategies studied to overcome such obstacles include the employment of new materials that, possibly, combine mucoadhesive, enzyme inhibitory and penetration enhancer properties and the design of innovative drug delivery systems which, besides improving patient compliance, favor a more intimate contact of the drug with the absorption mucosa. This presents a brief description of advantages and limitations of buccal drug delivery and the anatomical structure of oral mucosa, mechanisms of drug permeation followed by current formulation design in line with developments in buccal delivery systems and methodology in evaluating buccal formulations. PMID:23008684

  5. Ring energy and current considerations for spallation neutron source

    SciTech Connect

    Blumberg, L.N.

    1994-04-01

    The most desirable energy E{sub o} of protons from the synchrotron and thus beam current {bar I} to produced a given beam power P{sub B} involves a balanced consideration of neutron production capability, accelerator beam stability, user requirements, and cost considerations. The present solution consists of two 3.6-GeV rings with a 600-MeV Linac injector, a compromise between conflicting factors of cost and technical concern. The authors believe that the design is a conservative one. They could increase the beam energy and/or the repetition rate and thereby decrease the requirement for the number of protons N{sub o} in the ring which in the present design is an extrapolation of about a factor of 7 from existing ring intensities. However, the specified ring acceptance appears quite adequate to contain the required 1.45 10{sup 14} protons/ring and the resulting loss in the target window and target are reasonable. The beam power and current are indeed modest in terms of window and target integrity compared to the 200 MW, 200mA 1-GeV design for the APT. The two-ring approach also offers several practical advantages -- the project is stageable in the sense that only one ring may be required initially to achieve P{sub B} = 2.5 MW power on the target with subsequent expansion to 5 MW with addition of the second ring. Two rings also provide additional reliability in the sense that the user program need not be interrupted by failure of one ring.

  6. On variational formulation of current drive problem in uniformly magnetized relativistic plasma

    NASA Astrophysics Data System (ADS)

    Hu, Y. M.; Hu, Y. J.

    2016-01-01

    A fully relativistic extension of the variational principle with the modified test function for the Spitzer function with momentum conservation in the electron-electron collision is investigated in uniformly magnetized plasma. The term of the momentum conserving constraint in Hirshman’s variational calculation is studied. The model developed is extended for arbitrary temperatures and covers exactly the asymptotic for u\\gg 1 when {{Z}\\text{eff}}\\gg 1 , and the results obtained are suited to facilitate the development of a rigorous variational formulation of current drive efficiency in tokamak plasma.

  7. High neutronic efficiency, low current targets for accelerator-based BNCT applications

    SciTech Connect

    Powell, J.R.; Ludewig, H.; Todosow, M.

    1998-08-01

    The neutronic efficiency of target/filters for accelerator-based BNCT applications is measured by the proton current required to achieve a desirable neutron current at the treatment port (10{sup 9} n/cm{sup 2}/s). In this paper the authors describe two possible targeyt/filter concepts wihch minimize the required current. Both concepts are based on the Li-7 (p,n)Be-7 reaction. Targets that operate near the threshold energy generate neutrons that are close tothe desired energy for BNCT treatment. Thus, the filter can be extremely thin ({approximately} 5 cm iron). However, this approach has an extremely low neutron yield (n/p {approximately} 1.0({minus}6)), thus requiring a high proton current. The proposed solutino is to design a target consisting of multiple extremely thin targets (proton energy loss per target {approximately} 10 keV), and re-accelerate the protons between each target. Targets operating at ihgher proton energies ({approximately} 2.5 MeV) have a much higher yield (n/p {approximately} 1.0({minus}4)). However, at these energies the maximum neutron energy is approximately 800 keV, and thus a neutron filter is required to degrade the average neutron energy to the range of interest for BNCT (10--20 keV). A neutron filter consisting of fluorine compounds and iron has been investigated for this case. Typically a proton current of approximately 5 mA is required to generate the desired neutron current at the treatment port. The efficiency of these filter designs can be further increased by incorporating neutron reflectors that are co-axial with the neutron source. These reflectors are made of materials which have high scattering cross sections in the range 0.1--1.0 MeV.

  8. An eddy current vector potential formulation for estimating hysteresis losses of superconductors with FEM

    NASA Astrophysics Data System (ADS)

    Stenvall, A.; Tarhasaari, T.

    2010-12-01

    Many people these days employ only commercial finite element method (FEM) software when solving for the hysteresis losses of superconductors. Thus, the knowledge of a modeller is in the capability of using the black boxes of software efficiently. This has led to a relatively superficial examination of different formulations while the discussion stays mainly on the usage of the user interfaces of these programs. Also, if we stay only at the mercy of commercial software producers, we end up having less and less knowledge on the details of solvers. Then, it becomes more and more difficult to conceptually solve new kinds of problem. This may prevent us finding new kinds of method to solve old problems more efficiently, or finding a solution for a problem that was considered almost impossible earlier. In our earlier research, we presented the background of a co-tree gauged T-phiv FEM solver for computing the hysteresis losses of superconductors. In this paper, we examine the feasibility of FEM and eddy current vector potential formulation in the same problem.

  9. 3D transient eddy current fields using the u-v integral-eigenvalue formulation

    NASA Astrophysics Data System (ADS)

    Davey, Kent R.; Han, Hsiu Chi; Turner, Larry

    1988-02-01

    The three-dimensional eddy current transient field problem is formulated using the u-v method. This method breaks the vector Helmholtz equation into two scalar Helmholtz equations. Null field integral equations and the appropriate boundary conditions are used to set up an identification matrix which is independent of null field point locations. Embedded in the identification matrix are the unknown eigenvalues of the problem representing its impulse response in time. These eigenvalues are found by equating the determinant of the identification matrix to zero. When the initial transient forcing function is Fourier decomposed into its spatial harmonics, each Fourier component can be associated with a unique eigenvalue by this technique. The true transient solution comes through a convolution of the impulse response, so obtained with the particular external field decay governing the problem at hand. The technique is applied to the FELIX (fusion electromagnetic induction experiments) medium cylinder experiment; computed results are compared with data. A pseudoanalytic confirmation of the eigenvalues so obtained is formulated to validate the procedure.

  10. 3D transient eddy current fields using the u-v integral-eigenvalue formulation

    SciTech Connect

    Davey, K.R.; Han, H.C.; Turner, L.

    1988-02-15

    The three-dimensional eddy current transient field problem is formulated using the u-v method. This method breaks the vector Helmholtz equation into two scalar Helmholtz equations. Null field integral equations and the appropriate boundary conditions are used to set up an identification matrix which is independent of null field point locations. Embedded in the identification matrix are the unknown eigenvalues of the problem representing its impulse response in time. These eigenvalues are found by equating the determinant of the identification matrix to zero. When the initial transient forcing function is Fourier decomposed into its spatial harmonics, each Fourier component can be associated with a unique eigenvalue by this technique. The true transient solution comes through a convolution of the impulse response, so obtained with the particular external field decay governing the problem at hand. The technique is applied to the FELIX (fusion electromagnetic induction experiments) medium cylinder experiment; computed results are compared with data. A pseudoanalytic confirmation of the eigenvalues so obtained is formulated to validate the procedure.

  11. Topological currents in neutron stars: kicks, precession, toroidal fields, and magnetic helicity

    SciTech Connect

    Charbonneau, James; Zhitnitsky, Ariel E-mail: arz@phas.ubc.ca

    2010-08-01

    The effects of anomalies in high density QCD are striking. We consider a direct application of one of these effects, namely topological currents, on the physics of neutron stars. All the elements required for topological currents are present in neutron stars: degenerate matter, large magnetic fields, and parity violating processes. These conditions lead to the creation of vector currents capable of carrying momentum and inducing magnetic fields. We estimate the size of these currents for many representative states of dense matter in the neutron star and argue that they could be responsible for the large proper motion of neutron stars (kicks), the toroidal magnetic field and finite magnetic helicity needed for stability of the poloidal field, and the resolution of the conflict between type-II superconductivity and precession. Though these observational effects appear unrelated, they likely originate from the same physics — they are all P-odd phenomena that stem from a topological current generated by parity violation.

  12. Current applications of neutron scattering in condensed matter physics, materials science and engineering

    NASA Astrophysics Data System (ADS)

    Cywinski, R.

    1997-02-01

    A brief review is presented of the current applications of neutron scattering in the fields of magnetism, highly correlated electron systems, materials science and industrial applications, as represented by presentations at ECNS'96.

  13. High yield neutron generator based on a high-current gasdynamic electron cyclotron resonance ion source

    NASA Astrophysics Data System (ADS)

    Skalyga, V.; Izotov, I.; Golubev, S.; Sidorov, A.; Razin, S.; Strelkov, A.; Tarvainen, O.; Koivisto, H.; Kalvas, T.

    2015-09-01

    In present paper, an approach for high yield compact D-D neutron generator based on a high current gasdynamic electron cyclotron resonance ion source is suggested. Results on dense pulsed deuteron beam production with current up to 500 mA and current density up to 750 mA/cm2 are demonstrated. Neutron yield from D2O and TiD2 targets was measured in case of its bombardment by pulsed 300 mA D+ beam with 45 keV energy. Neutron yield density at target surface of 109 s-1 cm-2 was detected with a system of two 3He proportional counters. Estimations based on obtained experimental results show that neutron yield from a high quality TiD2 target bombarded by D+ beam demonstrated in present work accelerated to 100 keV could reach 6 × 1010 s-1 cm-2. It is discussed that compact neutron generator with such characteristics could be perspective for a number of applications like boron neutron capture therapy, security systems based on neutron scanning, and neutronography.

  14. High yield neutron generator based on a high-current gasdynamic electron cyclotron resonance ion source

    SciTech Connect

    Skalyga, V.; Sidorov, A.; Izotov, I.; Golubev, S.; Razin, S.; Strelkov, A.; Tarvainen, O.; Koivisto, H.; Kalvas, T.

    2015-09-07

    In present paper, an approach for high yield compact D-D neutron generator based on a high current gasdynamic electron cyclotron resonance ion source is suggested. Results on dense pulsed deuteron beam production with current up to 500 mA and current density up to 750 mA/cm{sup 2} are demonstrated. Neutron yield from D{sub 2}O and TiD{sub 2} targets was measured in case of its bombardment by pulsed 300 mA D{sup +} beam with 45 keV energy. Neutron yield density at target surface of 10{sup 9} s{sup −1} cm{sup −2} was detected with a system of two {sup 3}He proportional counters. Estimations based on obtained experimental results show that neutron yield from a high quality TiD{sub 2} target bombarded by D{sup +} beam demonstrated in present work accelerated to 100 keV could reach 6 × 10{sup 10} s{sup −1} cm{sup −2}. It is discussed that compact neutron generator with such characteristics could be perspective for a number of applications like boron neutron capture therapy, security systems based on neutron scanning, and neutronography.

  15. Parameter Estimation of Ion Current Formulations Requires Hybrid Optimization Approach to Be Both Accurate and Reliable

    PubMed Central

    Loewe, Axel; Wilhelms, Mathias; Schmid, Jochen; Krause, Mathias J.; Fischer, Fathima; Thomas, Dierk; Scholz, Eberhard P.; Dössel, Olaf; Seemann, Gunnar

    2016-01-01

    Computational models of cardiac electrophysiology provided insights into arrhythmogenesis and paved the way toward tailored therapies in the last years. To fully leverage in silico models in future research, these models need to be adapted to reflect pathologies, genetic alterations, or pharmacological effects, however. A common approach is to leave the structure of established models unaltered and estimate the values of a set of parameters. Today’s high-throughput patch clamp data acquisition methods require robust, unsupervised algorithms that estimate parameters both accurately and reliably. In this work, two classes of optimization approaches are evaluated: gradient-based trust-region-reflective and derivative-free particle swarm algorithms. Using synthetic input data and different ion current formulations from the Courtemanche et al. electrophysiological model of human atrial myocytes, we show that neither of the two schemes alone succeeds to meet all requirements. Sequential combination of the two algorithms did improve the performance to some extent but not satisfactorily. Thus, we propose a novel hybrid approach coupling the two algorithms in each iteration. This hybrid approach yielded very accurate estimates with minimal dependency on the initial guess using synthetic input data for which a ground truth parameter set exists. When applied to measured data, the hybrid approach yielded the best fit, again with minimal variation. Using the proposed algorithm, a single run is sufficient to estimate the parameters. The degree of superiority over the other investigated algorithms in terms of accuracy and robustness depended on the type of current. In contrast to the non-hybrid approaches, the proposed method proved to be optimal for data of arbitrary signal to noise ratio. The hybrid algorithm proposed in this work provides an important tool to integrate experimental data into computational models both accurately and robustly allowing to assess the often non

  16. Current status of the neutron application program at TRR-II

    NASA Astrophysics Data System (ADS)

    Huang, Yuhao

    2002-01-01

    This paper describes the current status of the neutron application program at the Taiwan Research Reactor-II (TRR-II) project. It has been more than two years since the project was officially approved in October 1998. In addition to the completion of the basic designs of the core, the core block, and the experimental facilities, some achievements related to the application promotion are also accomplished. In the past two years, the project team invited more than 50 foreign experts to TRR-II to discuss various design issues related to the reactor and experimental facilities. As a multi-purpose research reactor, its scope includes facilities such as fuel/material irradiation, isotope production, neutron activation analysis, neutron transmutation doping, cold neutron source and guides, and neutron spectrometers. A special task force was organized in the early stage to promote these applications, especially focused on the area of neutron scattering, which had not been well organized before. Up to now, the team has completed the preliminary market planning for general irradiation facilities, and the following are the major achievements for promotion of neutron scattering applications: Establish collaboration agreements with NIST (formal), ILL, and FRM-II for personnel training. Subcontract with domestic professors to promote neutron scattering related research in Taiwan. Co-Sponsor large-scale workshops and conferences (average two times per year). Invite foreign experts specialized in neutron scattering for mini-workshops or topical meetings (average 5-8 times per year). Discussion on establishing an independent “Neutron Application Research Center” to encourage the involvement of domestic professors and students.

  17. Hamiltonian Formulation for Wave-Current Interactions in Stratified Rotational Flows

    NASA Astrophysics Data System (ADS)

    Constantin, A.; Ivanov, R. I.; Martin, C.-I.

    2016-09-01

    We show that the Hamiltonian framework permits an elegant formulation of the nonlinear governing equations for the coupling between internal and surface waves in stratified water flows with piecewise constant vorticity.

  18. Current Aspects of Formulation Efforts and Pore Lifetime Related to Microneedle Treatment of Skin

    PubMed Central

    Milewski, Mikolaj; Brogden, Nicole K.; Stinchcomb, Audra L.

    2010-01-01

    Importance of this field The efficacy of microneedles in the area of transdermal drug delivery is well-documented. Multiple studies have shown that enhancement of skin permeation via creation of microscopic pores in the stratum corneum can greatly improve the delivery rates of drugs. However, skin pretreatment with microneedles is not the only factor affecting drug transport rates. Other factors including drug formulation and rate of micropore closure are also important for optimizing delivery via this route. Areas covered in this review This review aims at highlighting work that has been done in these areas, with an emphasis on drug formulation parameters that affect transdermal flux. What the reader will gain This review creates an appreciation for the many factors affecting microneedle-enhanced delivery. Most results clearly indicate that microneedle skin pretreatment by itself may have different effects on drug transport depending on the formulation used, and formulation characteristics have different effects on the transport through untreated skin and microneedle-treated skin. Several formulation approaches are reported to optimize microneedle-enhanced drug delivery, including cosolvent use, vesicular, nanoparticulate and gel systems. Take home message In addition to well-established factors that affect microneedle-assisted delivery (geometry, type of microneedles, etc), formulation and pore viability are also critical factors that must be considered. PMID:20205604

  19. Neutron generator for BNCT based on high current ECR ion source with gyrotron plasma heating.

    PubMed

    Skalyga, V; Izotov, I; Golubev, S; Razin, S; Sidorov, A; Maslennikova, A; Volovecky, A; Kalvas, T; Koivisto, H; Tarvainen, O

    2015-12-01

    BNCT development nowadays is constrained by a progress in neutron sources design. Creation of a cheap and compact intense neutron source would significantly simplify trial treatments avoiding use of expensive and complicated nuclear reactors and accelerators. D-D or D-T neutron generator is one of alternative types of such sources for. A so-called high current quasi-gasdynamic ECR ion source with plasma heating by millimeter wave gyrotron radiation is suggested to be used in a scheme of D-D neutron generator in the present work. Ion source of that type was developed in the Institute of Applied Physics of Russian Academy of Sciences (Nizhny Novgorod, Russia). It can produce deuteron ion beams with current density up to 700-800 mA/cm(2). Generation of the neutron flux with density at the level of 7-8·10(10) s(-1) cm(-2) at the target surface could be obtained in case of TiD2 target bombardment with deuteron beam accelerated to 100 keV. Estimations show that it is enough for formation of epithermal neutron flux with density higher than 10(9) s(-1) cm(-2) suitable for BNCT. Important advantage of described approach is absence of Tritium in the scheme. First experiments performed in pulsed regime with 300 mA, 45 kV deuteron beam directed to D2O target demonstrated 10(9) s(-1) neutron flux. This value corresponds to theoretical estimations and proofs prospects of neutron generator development based on high current quasi-gasdynamic ECR ion source. PMID:26302662

  20. Effects of Cosmetic Formulations Containing Hydroxyacids on Sun-Exposed Skin: Current Applications and Future Developments

    PubMed Central

    Kornhauser, Andrija; Coelho, Sergio G.; Hearing, Vincent J.

    2012-01-01

    This paper describes recent data on the effects of various skin formulations containing hydroxyacids (HAs) and related products on sun-exposed skin. The most frequently used classes of these products, such as α- and β-hydroxyacids, polyhydroxy acids, and bionic acids, are reviewed, and their application in cosmetic formulations is described. Special emphasis is devoted to the safety evaluation of these formulations, particularly on the effects of their prolonged use on sun-exposed skin. We also discuss the important contribution of cosmetic vehicles in these types of studies. Data on the effects of HAs on melanogenesis and tanning are also included. Up-to-date methods and techniques used in those explorations, as well as selected future developments in the cosmetic area, are presented. PMID:22675344

  1. Simple Field Assays to Check Quality of Current Artemisinin-Based Antimalarial Combination Formulations

    PubMed Central

    Ioset, Jean-Robert; Kaur, Harparkash

    2009-01-01

    Introduction Malaria continues to be one of the major public health problems in Africa, Asia and Latin America. Artemisinin derivatives (ARTs; artesunate, artemether, and dihydroartemisinin) derived from the herb, Artemisia annua, are the most effective antimalarial drugs available providing rapid cures. The World Health Organisation (WHO) has recommended that all antimalarials must be combined with an artemisinin component (artemisinin-based combination therapy; ACT) for use as first line treatment against malaria. This class of drugs is now first-line policy in most malaria-endemic countries. Reports of ad hoc surveys from South East Asia show that up to 50% of the artesunate currently sold is counterfeit. Drug quality is rarely assessed in resource poor countries in part due to lack of dedicated laboratory facilities which are expensive to build, equip and maintain. With a view to address this unmet need we developed two novel colour reaction assays that can be used in the field to check the quality of ARTs. Methods and Findings Our assays utilise thin layer chromatography silica gel sheets and 2, 4 dinitrophenylhydrazine or 4-Benzoylamino-2, 5-dimethoxybenzenediazonium chloride hemi (zinc chloride) salt as the reagents showing a pink or blue product respectively only in the presence ARTs. We are able to detect as low as 10% of ARTs in ACTs (WINTHROP - artesunate/amodiaquine, Coartem®-artemether/lumefantrine and Duocortexcin - dihydroartemisinin/piperaquine). The assays have been validated extensively by testing eighty readily accessible and widely used drugs in malaria endemic countries. None of the other antimalarial drugs or a range of commonly used excipients, antiretroviral drugs or other frequently used drugs from the WHO essential drugs list such as analgesics or antibiotics are detected with our assays. Conclusions Our two independent assays requiring no specialist training are specific, simple to use, rapid, robust, reproducible, inexpensive and, have

  2. Current perspectives on stability of protein drug products during formulation, fill and finish operations.

    PubMed

    Rathore, Nitin; Rajan, Rahul S

    2008-01-01

    Commercialization of protein-based therapeutics is a challenging task in part due to the difficulties in maintaining protein solutions safe and efficacious throughout the drug product development process, storage, transportation and patient administration. Bulk drug substance goes through a series of formulation, fill and finish operations to provide the final dosage form in the desired formulation and container or delivery device. Different process parameters during each of these operations can affect the purity, activity and efficacy of the final product. Common protein degradation pathways and the various physical and chemical factors that can induce such reactions have been extensively studied for years. This review presents an overview of the various formulation-fill-finish operations with a focus on processing steps and conditions that can impact product quality. Various manufacturing operations including bulk freeze-thaw, formulation, filtration, filling, lyophilization, inspection, labeling, packaging, storage, transport and delivery have been reviewed. The article highlights our present day understanding of protein instability issues during biopharmaceutical manufacturing and provides guidance on process considerations that can help alleviate these concerns. PMID:18484778

  3. CVD Diamond Detectors for Current Mode Neutron Time-of-Flight Spectroscopy at OMEGA/NIF

    SciTech Connect

    G. J. Schmid; V. Yu. Glebov; A. V. Friensehner; D. R. Hargrove; S. P. Hatchett; N. Izumi; R. A. Lerche; T. W. Phillips; T. C. Sangster; C. Silbernagel; C. Stoecki

    2001-07-01

    We have performed pulsed neutron and pulsed laser tests of a CVD diamond detector manufactured from DIAFILM, a commercial grade of CVD diamond. The laser tests were performed at the short pulse UV laser at Bechtel Nevada in Livermore, CA. The pulsed neutrons were provided by DT capsule implosions at the OMEGA laser fusion facility in Rochester, NY. From these tests, we have determined the impulse response to be 250 ps fwhm for an applied E-field of 500 V/mm. Additionally, we have determined the sensitivity to be 2.4 mA/W at 500 V/mm and 4.0 mA/W at 1000 V/mm. These values are approximately 2 to 5x times higher than those reported for natural Type IIa diamond at similar E-field and thickness (1mm). These characteristics allow us to conceive of a neutron time-of-flight current mode spectrometer based on CVD diamond. Such an instrument would sit inside the laser fusion target chamber close to target chamber center (TCC), and would record neutron spectra fast enough such that backscattered neutrons and x-rays from the target chamber wall would not be a concern. The acquired neutron spectra could then be used to extract DD fuel areal density from the downscattered secondary to secondary ratio.

  4. CVD Diamond Detectors for Current Mode Neutron Time-of-Flight Spectroscopy at OMEGA/NIF

    SciTech Connect

    Schmid, G J; Friensehner, A F; Glebov, V Y; Hargrove, D R; Hatchett, S P; Izumi, N; Lerche, R A; Phillips, T W; Sangster, T C; Sibernagel, C; Stoeckl, C

    2001-06-19

    As part of a laser fusion diagnostic development program, we have performed pulsed neutron and pulsed laser tests of a CVD diamond detector manufactured from DIAFILM, a commercial grade of CVD diamond. The laser tests were performed at the short pulse UV laser at Bechtel Nevada in Livermore, CA. The pulsed neutrons were provided by DT capsule implosions at the OMEGA laser fusion facility in Rochester, NY. From these tests, we have determined the impulse response to be 250 ps fwhm for an applied E-field of 500 V/mm. Additionally, we have determined the sensitivity to be 2.8 mA/W at 500 V/mm and 4.5 mA/W at 1000 V/mm (2 to 6x times higher than reported values for natural Type IIa diamond). These detector characteristics allow us to conceive of a neutron time-of-flight current mode spectrometer based on CVD diamond. Such an instrument would sit inside the laser fusion target chamber close to TCC, and would record neutron spectra fast enough such that backscattered neutrons and y rays from the target chamber wall would not be a concern. However, the data we have taken show that the Electromagnetic Pulse (EMP) noise could be a limiting factor in performance. Determining the degree to which this noise can be shielded will be an important subject of future tests.

  5. Orbit Correction Methods - Basic Formulation, Current Applications at Jefferson Lab, and Future Possibilities

    SciTech Connect

    Chao, Y.C.

    1999-12-01

    A. Orbit Correction System Optimization: Recipes for optimizing an orbit correction system configuration at the design level are presented. Linear algebraic tools are applied to various flavors of response matrices to uniformly control unobservability, uncorrectability, and response matrix singularity. Application at Jefferson Lab is discussed. B. Orbit Correction at Jefferson Lab: Unique challenges posed by orbit correction, as well as algorithms and tools developed at the CEBAF accelerator at Jefferson Lab are discussed. C. Orbit Interpretation and Virtual Monitors: A new approach to developing an orbit correction package with software structural, algorithmic and operational advantages is introduced. It consists of an orbit interpretation module, a virtual monitor module, and a generic steering engine. Mathematical formulation, algorithms prototyped and tested on simulated and real data, and future possibilities are discussed.

  6. Radiative neutron capture as a counting technique at pulsed spallation neutron sources: a review of current progress.

    PubMed

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

    2016-09-01

    Neutron scattering techniques are attracting an increasing interest from scientists in various research fields, ranging from physics and chemistry to biology and archaeometry. The success of these neutron scattering applications is stimulated by the development of higher performance instrumentation. The development of new techniques and concepts, including radiative capture based neutron detection, is therefore a key issue to be addressed. Radiative capture based neutron detectors utilize the emission of prompt gamma rays after neutron absorption in a suitable isotope and the detection of those gammas by a photon counter. They can be used as simple counters in the thermal region and (simultaneously) as energy selector and counters for neutrons in the eV energy region. Several years of extensive development have made eV neutron spectrometers operating in the so-called resonance detector spectrometer (RDS) configuration outperform their conventional counterparts. In fact, the VESUVIO spectrometer, a flagship instrument at ISIS serving a continuous user programme for eV inelastic neutron spectroscopy measurements, is operating in the RDS configuration since 2007. In this review, we discuss the physical mechanism underlying the RDS configuration and the development of associated instrumentation. A few successful neutron scattering experiments that utilize the radiative capture counting techniques will be presented together with the potential of this technique for thermal neutron diffraction measurements. We also outline possible improvements and future perspectives for radiative capture based neutron detectors in neutron scattering application at pulsed neutron sources. PMID:27502571

  7. Radiative neutron capture as a counting technique at pulsed spallation neutron sources: a review of current progress

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    Neutron scattering techniques are attracting an increasing interest from scientists in various research fields, ranging from physics and chemistry to biology and archaeometry. The success of these neutron scattering applications is stimulated by the development of higher performance instrumentation. The development of new techniques and concepts, including radiative capture based neutron detection, is therefore a key issue to be addressed. Radiative capture based neutron detectors utilize the emission of prompt gamma rays after neutron absorption in a suitable isotope and the detection of those gammas by a photon counter. They can be used as simple counters in the thermal region and (simultaneously) as energy selector and counters for neutrons in the eV energy region. Several years of extensive development have made eV neutron spectrometers operating in the so-called resonance detector spectrometer (RDS) configuration outperform their conventional counterparts. In fact, the VESUVIO spectrometer, a flagship instrument at ISIS serving a continuous user programme for eV inelastic neutron spectroscopy measurements, is operating in the RDS configuration since 2007. In this review, we discuss the physical mechanism underlying the RDS configuration and the development of associated instrumentation. A few successful neutron scattering experiments that utilize the radiative capture counting techniques will be presented together with the potential of this technique for thermal neutron diffraction measurements. We also outline possible improvements and future perspectives for radiative capture based neutron detectors in neutron scattering application at pulsed neutron sources.

  8. Current progress and future prospects of the VITA based neutron source.

    PubMed

    Aleynik, V; Bashkirtsev, A; Kanygin, V; Kasatov, D; Kuznetsov, A; Makarov, A; Schudlo, I; Sorokin, I; Taskaev, S; Tiunov, M

    2014-06-01

    At the BINP, a pilot accelerator based epithermal neutron source is now in use. Most recent investigations on the facility are related with studying the dark current, X-ray radiation measuring, optimization of H(-)-beam injection and new gas stripping target calibrating. The results of these studies, ways of providing stability to the accelerator are presented and discussed, as well as the ways of creating the therapeutic beam and strategies of applying the facility for clinical use. PMID:24369890

  9. Integrating advances in insulin into clinical practice: Overview of current insulin formulations.

    PubMed

    Rhinehart, Andrew S

    2013-09-01

    Defects in both insulin secretion and function play a fundamental role in the pathophysiologic mechanisms underlying both type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM). As the most physiologic treatment option available, insulin plays a central role in the management of patients with T1DM and a growing role in the management of patients with T2DM, as is reflected in current treatment guidelines. PMID:24080572

  10. High-current negative-ion sources for pulsed spallation neutron sources: LBNL workshop, October 1994

    SciTech Connect

    Alonso, J.R.

    1995-09-01

    The neutron scattering community has endorsed the need for a high-power (1 to 5 MW) accelerator-driven source of neutrons for materials research. Properly configured, the accelerator could produce very short (sub-microsecond) bursts of cold neutrons, said time structure offering advantages over the continuous flux from a reactor. The recent cancellation of the ANS reactor project has increased the urgency to develop a comprehensive strategy based on the best technological scenarios. Studies to date have built on the experience from ISIS (the 160 kW source in the UK), and call for a high-current (approx. 100 mA peak) H- source-linac combination injecting into one or more accumulator rings in which beam may be further accelerated. The I to 5 GeV proton beam is extracted in a single turn and brought to the target-moderator stations. The high current, high duty-factor, high brightness and high reliability required of the ion source present a very large challenge to the ion source community. The Workshop reported on here, held in Berkeley in October 1994, analyzed in detail the source requirements for proposed accelerator scenarios, the present performance capabilities of different H- source technologies, and identified necessary R&D efforts to bridge the gap.

  11. Fluctuating volume-current formulation of electromagnetic fluctuations in inhomogeneous media: Incandescence and luminescence in arbitrary geometries

    NASA Astrophysics Data System (ADS)

    Polimeridis, Athanasios G.; Reid, M. T. H.; Jin, Weiliang; Johnson, Steven G.; White, Jacob K.; Rodriguez, Alejandro W.

    2015-10-01

    We describe a fluctuating volume-current formulation of electromagnetic fluctuations that extends our recent work on heat exchange and Casimir interactions between arbitrarily shaped homogeneous bodies [A. W. Rodriguez, M. T. H. Reid, and S. G. Johnson, Phys. Rev. B 88, 054305 (2013), 10.1103/PhysRevB.88.054305] to situations involving incandescence and luminescence problems, including thermal radiation, heat transfer, Casimir forces, spontaneous emission, fluorescence, and Raman scattering, in inhomogeneous media. Unlike previous scattering formulations based on field and/or surface unknowns, our work exploits powerful techniques from the volume-integral equation (VIE) method, in which electromagnetic scattering is described in terms of volumetric, current unknowns throughout the bodies. The resulting trace formulas (boxed equations) involve products of well-studied VIE matrices and describe power and momentum transfer between objects with spatially varying material properties and fluctuation characteristics. We demonstrate that thanks to the low-rank properties of the associated matrices, these formulas are susceptible to fast-trace computations based on iterative methods, making practical calculations tractable. We apply our techniques to study thermal radiation, heat transfer, and fluorescence in complicated geometries, checking our method against established techniques best suited for homogeneous bodies as well as applying it to obtain predictions of radiation from complex bodies with spatially varying permittivities and/or temperature profiles.

  12. Neutron production in deuterium gas-puff z-pinch with outer plasma shell at current of 3 MA

    NASA Astrophysics Data System (ADS)

    Cikhardt, J.; Klir, D.; Rezac, K.; Cikhardtova, B.; Kravarik, J.; Kubes, P.; Sila, O.; Shishlov, A. V.; Cherdizov, R. K.; Frusov, F. I.; Kokshenev, V. A.; Kurmaev, N. E.; Labetsky, A. Yu.; Ratakhin, N. A.; Dudkin, G. N.; Garapatsky, A. A.; Padalko, V. N.; Varlachev, V. A.; Turek, K.; Krasa, J.

    2015-11-01

    Z-pinch experiments at the current of about 3 MA were carried out on the GIT-12 generator. The outer plasma shell of deuterium gas-puff was generated by the system of 48 plasma guns. This configuration exhibits a high efficiency of the production of DD fusion neutrons with the yield of above 1012 neutrons produced in a single shot with the duration of about 20 ns. The maximum energy of the neutrons produced in this pulse exceeded 30 MeV. The neutron radiation was measured using scintillation TOF detectors, CR-39 nuclear track detectors, bubble detectors BD-PND and BDS-10000 and by several types of nuclear activation detectors. These diagnostic tools were used to measure the anisotropy of neutron fluence and neutron energy spectra. It allows us to estimate the total number of DD neutrons, the contribution of other nuclear reactions, the amount of scattered neutrons, and other parameters of neutron production. This work was supported by the MSMT grants LH13283, LD14089.

  13. Numerical studies of the flux-to-current ratio method in the KIPT neutron source facility

    SciTech Connect

    Cao, Y.; Gohar, Y.; Zhong, Z.

    2013-07-01

    The reactivity of a subcritical assembly has to be monitored continuously in order to assure its safe operation. In this paper, the flux-to-current ratio method has been studied as an approach to provide the on-line reactivity measurement of the subcritical system. Monte Carlo numerical simulations have been performed using the KIPT neutron source facility model. It is found that the reactivity obtained from the flux-to-current ratio method is sensitive to the detector position in the subcritical assembly. However, if multiple detectors are located about 12 cm above the graphite reflector and 54 cm radially, the technique is shown to be very accurate in determining the k{sub eff} this facility in the range of 0.75 to 0.975. (authors)

  14. Current Issues in Nuclear Data Evaluation Methodology: {sup 235}U Prompt Fission Neutron Spectra and Multiplicity for Thermal Neutrons

    SciTech Connect

    Trkov, A.; Capote, R.; Pronyaev, V.G.

    2015-01-15

    Issues in evaluation methodology of the prompt fission neutron spectra (PFNS) and neutron multiplicity for the thermal-neutron-induced fission of the {sup 235}U are discussed. The inconsistency between the experimental differential and integral data is addressed. By using differential data as ”shape data” good consistency was achieved between available sets of differential data. Integral dosimetry data have been used to define the PFNS slope at high outgoing neutron energies, where the quality of the differential data is poor. The inclusion into the fit of measured integral (spectrum-averaged) cross sections had a very small impact in the region where differential PFNS data are abundant and accurate, but removed the discrepancy with integral data at higher neutron emission energies. All experimental data are consistently fitted giving a PFNS average energy of 2.008 MeV. The impact on criticality prediction of the newly evaluated PFNS was tested. The highly enriched {sup 235}U solution assemblies with high leakage HEU-SOL-THERM-001 and HEU-SOL-THERM-009 benchmarks are the most sensitive to the PFNS. Criticality calculations for those solutions show a significant increase in reactivity if the average neutron energy of the fission neutrons is reduced from the ENDF/B-VI.5 value of 2.03 MeV. The proposed reduction of the PFNS average energy by 1.1% can be compensated by reducing the average number of neutrons per fission ν{sup ¯} at the thermal energy to the Gwin et al. measured value. The simple least-squares PFNS fit was confirmed by a more sophisticated combined fit of differential PFNS data for {sup 233,235}U, {sup 239}Pu and {sup 252}Cf nuclides with the generalised least-squares method using the GMA and GANDR codes.

  15. Current Issues in Nuclear Data Evaluation Methodology: 235U Prompt Fission Neutron Spectra and Multiplicity for Thermal Neutrons

    NASA Astrophysics Data System (ADS)

    Trkov, A.; Capote, R.; Pronyaev, V. G.

    2015-01-01

    Issues in evaluation methodology of the prompt fission neutron spectra (PFNS) and neutron multiplicity for the thermal-neutron-induced fission of the 235U are discussed. The inconsistency between the experimental differential and integral data is addressed. By using differential data as "shape data" good consistency was achieved between available sets of differential data. Integral dosimetry data have been used to define the PFNS slope at high outgoing neutron energies, where the quality of the differential data is poor. The inclusion into the fit of measured integral (spectrum-averaged) cross sections had a very small impact in the region where differential PFNS data are abundant and accurate, but removed the discrepancy with integral data at higher neutron emission energies. All experimental data are consistently fitted giving a PFNS average energy of 2.008 MeV. The impact on criticality prediction of the newly evaluated PFNS was tested. The highly enriched 235U solution assemblies with high leakage HEU-SOL-THERM-001 and HEU-SOL-THERM-009 benchmarks are the most sensitive to the PFNS. Criticality calculations for those solutions show a significant increase in reactivity if the average neutron energy of the fission neutrons is reduced from the ENDF/B-VI.5 value of 2.03 MeV. The proposed reduction of the PFNS average energy by 1.1% can be compensated by reducing the average number of neutrons per fission νbar at the thermal energy to the Gwin et al. measured value. The simple least-squares PFNS fit was confirmed by a more sophisticated combined fit of differential PFNS data for 233,235U, 239Pu and 252Cf nuclides with the generalised least-squares method using the GMA and GANDR codes.

  16. Formulation and experimental evaluation of closed-form control laws for the rapid maneuvering of reactor neutronic power

    SciTech Connect

    Bernard, J.A. . Nuclear Reactor Lab.)

    1989-09-01

    This report describes both the theoretical development and the experimental evaluation of a novel, robust methodology for the time-optimal adjustment of a reactor's neutronic power under conditions of closed-loop digital control. Central to the approach are the MIT-SNL Period-Generated Minimum Time Control Laws' which determine the rate at which reactivity should be changed in order to cause a reactor's neutronic power to conform to a specified trajectory. Using these laws, reactor power can be safely raised by five to seven orders of magnitude in a few seconds. The MIT-SNL laws were developed to facilitate rapid increases of neutronic power on spacecraft reactors operating in an SDI environment. However, these laws are generic and have other applications including the rapid recovery of research and test reactors subsequent to an unanticipated shutdown, power increases following the achievement of criticality on commercial reactors, power adjustments on commercial reactors so as to minimize thermal stress, and automated startups. The work reported here was performed by the Massachusetts Institute of Technology under contract to the Sandia National Laboratories. Support was also provided by the US Department of Energy's Division of University and Industry Programs. The work described in this report is significant in that a novel solution to the problem of time-optimal control of neutronic power was identified, in that a rigorous description of a reactor's dynamics was derived in that the rate of change of reactivity was recognized as the proper control signal, and in that extensive experimental trials were conducted of these newly developed concepts on actual nuclear reactors. 43 refs., 118 figs., 11 tabs.

  17. Implementation and modification of a three-dimensional radiation stress formulation for surf zone and rip-current applications

    USGS Publications Warehouse

    Kumar, N.; Voulgaris, G.; Warner, J.C.

    2011-01-01

    Regional Ocean Modeling System (ROMS v 3.0), a three-dimensional numerical ocean model, was previously enhanced for shallow water applications by including wave-induced radiation stress forcing provided through coupling to wave propagation models (SWAN, REF/DIF). This enhancement made it suitable for surf zone applications as demonstrated using examples of obliquely incident waves on a planar beach and rip current formation in longshore bar trough morphology (Haas and Warner, 2009). In this contribution, we present an update to the coupled model which implements a wave roller model and also a modified method of the radiation stress term based on Mellor (2008, 2011a,b,in press) that includes a vertical distribution which better simulates non-conservative (i.e., wave breaking) processes and appears to be more appropriate for sigma coordinates in very shallow waters where wave breaking conditions dominate. The improvements of the modified model are shown through simulations of several cases that include: (a) obliquely incident spectral waves on a planar beach; (b) obliquely incident spectral waves on a natural barred beach (DUCK'94 experiment); (c) alongshore variable offshore wave forcing on a planar beach; (d) alongshore varying bathymetry with constant offshore wave forcing; and (e) nearshore barred morphology with rip-channels. Quantitative and qualitative comparisons to previous analytical, numerical, laboratory studies and field measurements show that the modified model replicates surf zone recirculation patterns (onshore drift at the surface and undertow at the bottom) more accurately than previous formulations based on radiation stress (Haas and Warner, 2009). The results of the model and test cases are further explored for identifying the forces operating in rip current development and the potential implication for sediment transport and rip channel development. Also, model analysis showed that rip current strength is higher when waves approach at angles of 5

  18. Critical current anisotropy in Nd-1111 single crystals and the influence of neutron irradiation

    NASA Astrophysics Data System (ADS)

    Eisterer, M.; Mishev, V.; Zehetmayer, M.; Zhigadlo, N. D.; Katrych, S.; Karpinski, J.

    2014-04-01

    We report on angle-resolved magnetization measurements on NdFeAsO0.65F0.35 (Nd-1111) single crystals. The field dependence of the critical current density, Jc, is non-monotonic in these crystals at all orientations and temperatures due to the fishtail effect, which strongly influences the angular dependence of Jc. The currents decrease as the field is tilted from the crystallographic c-axis at low fields, but increase at high fields. A peak occurs in the angular dependence of Jc at intermediate fields. The critical currents are significantly enhanced after irradiation with fast neutrons and the fishtail disappears. The different current anisotropies at low and high fields, however, persist. We discuss the data in the framework of the anisotropic scaling approach and propose a transition from dominant pinning by large defects of low density at low fields to pinning by small defects of high density at high fields in the pristine crystal. Strong pinning dominates at all fields after the irradiation, and the angular dependence of Jc can be described via anisotropic scaling only after an appropriate extension to this pinning regime.

  19. Review of the Mechanism of Action and Clinical Efficacy of Recombinant Human Hyaluronidase Coadministration with Current Prandial Insulin Formulations

    PubMed Central

    Muchmore, Douglas B.; Vaughn, Daniel E.

    2010-01-01

    For patients with type 1 or type 2 diabetes, achieving good glycemic control is critical for successful treatment outcomes. As many patients remain unable to reach glycemic goals with currently available rapid-acting analog insulins, ultrafast insulin products are being developed that provide an even faster pharmacokinetic profile compared with current rapid prandial insulin products. The overall strategy of these ultrafast insulin products is to better mimic the normal physiologic response to insulin that occurs in healthy individuals to further improve glycemic control. Recombinant human hyaluronidase (rHuPH20) is a genetically engineered soluble hyaluronidase approved by the U.S. Food and Drug Administration as an adjuvant to increase the absorption and dispersion of other injected drugs; mammalian hyaluronidases as a class have over 6 decades of clinical use supporting the safety and/or efficacy of hyaluronidase coadministration. Clinical findings have demonstrated that coadministration of rHuPH20 with insulin or an insulin analog achieved faster systemic absorption, reduced inter- and intrapatient variability of insulin absorption, and achieved faster metabolic effects compared with injection of either insulin formulation alone. The magnitude of this acceleration is similar to the incrementally faster absorption of prandial insulin analogs as compared with regular insulin. In addition, coadministration of rHuPH20 with regular insulin or insulin analog also improved the achievement of prandial glycemic targets. Thus, rHuPH20 coadministration shows promise as a method of establishing a more rapid insulin profile to prandial insulin in patients with diabetes and has the potential to yield substantial improvements in postprandial glycemic excursion. PMID:20307403

  20. Current Status of the Experiment on Direct Measurement of Neutron-Neutron Scattering Length at the Reactor YAGUAR

    SciTech Connect

    Furman, W. I.; Muzichka, A. Yu.; Lychagin, E. V.; Nekhaev, G. V.; Sharapov, E. I.; Shvetsov, V. N.; Strelkov, A. V.; Crawford, B. E.; Stephenson, S. L.; Howell, C. R.; Tornow, W.; Kandiev, Ya.; Levakov, B. G.; Litvin, V. I.; Lyzhin, A. E.; Tchernukhin, Yu. I.; Mitchell, G. E.

    2009-03-31

    A new experiment was proposed in 2002 to perform the first direct measurement of neutron-neutron scattering on the powerful pulsed reactor YAGUAR located at Snezhinsk, Ural region, Russia. Extensive efforts were made to model the background conditions and to optimize the set-up design. To make the experiment feasible it was necessary to suppress the background from various origins by more than 16 orders of magnitude for thermal neutrons and 14 orders of magnitude for fast neutrons. In 2003 a channel was drilled under the reactor and equipped for time-of-flight measurements. During the next two years at this channel there were carried out a series of test experiments aimed at verifying the accuracy of the background modeling. Good agreement of the measured results with the calculated values enabled us to make the final design of the full scale set-up. During 2005-2006 the experimental system was manufactured. After vacuum tests at JINR the set-up was mounted at the YAGUAR reactor hall. In 2006-2007 calibration measurements with noble gases were performed. The results confirmed the validity of the modeling of the full scale experiment and verified the calibration. The first preliminary experiments for nn-scattering were performed in April 2008. These recent results are discussed.

  1. Current Status of the Experiment on Direct Measurement of Neutron-Neutron Scattering Length at the Reactor YAGUAR

    NASA Astrophysics Data System (ADS)

    Furman, W. I.; Muzichka, A. Yu.; Crawford, B. E.; Howell, C. R.; Kandiev, Ya.; Levakov, B. G.; Litvin, V. I.; Lychagin, E. V.; Lyzhin, A. E.; Mitchell, G. E.; Nekhaev, G. V.; Sharapov, E. I.; Shvetsov, V. N.; Stephenson, S. L.; Strelkov, A. V.; Tchernukhin, Yu. I.; Tornow, W.

    2009-03-01

    A new experiment was proposed in 2002 to perform the first direct measurement of neutron-neutron scattering on the powerful pulsed reactor YAGUAR located at Snezhinsk, Ural region, Russia. Extensive efforts were made to model the background conditions and to optimize the set-up design. To make the experiment feasible it was necessary to suppress the background from various origins by more than 16 orders of magnitude for thermal neutrons and 14 orders of magnitude for fast neutrons. In 2003 a channel was drilled under the reactor and equipped for time-of-flight measurements. During the next two years at this channel there were carried out a series of test experiments aimed at verifying the accuracy of the background modeling. Good agreement of the measured results with the calculated values enabled us to make the final design of the full scale set-up. During 2005-2006 the experimental system was manufactured. After vacuum tests at JINR the set-up was mounted at the YAGUAR reactor hall. In 2006-2007 calibration measurements with noble gases were performed. The results confirmed the validity of the modeling of the full scale experiment and verified the calibration. The first preliminary experiments for nn-scattering were performed in April 2008. These recent results are discussed.

  2. Self-powered micro-structured solid state neutron detector with very low leakage current and high efficiency

    SciTech Connect

    Dahal, R.; Huang, K. C.; LiCausi, N.; Lu, J.-Q.; Bhat, I.; Clinton, J.; Danon, Y.

    2012-06-11

    We report on the design, fabrication, and performance of solid-state neutron detector based on three-dimensional honeycomb-like silicon micro-structures. The fabricated detectors use boron filled deep holes with aspect ratio of over 12 and showed a very low leakage current density of {approx}7 Multiplication-Sign 10{sup -7} A/cm{sup 2} at -1 V for device sizes varying from 2 Multiplication-Sign 2 to 5 Multiplication-Sign 5 mm{sup 2}. A thermal neutron detection efficiency of 4.5% {+-} 0.5% with discrimination setting of 500 keV and gamma to neutron sensitivity of (1.1 {+-} 0.1) Multiplication-Sign 10{sup -5} for single layer was measured without external bias for these devices. Monte-Carlo simulation predicts a maximum efficiency of 45% for such devices filled with 95% enriched {sup 10}boron.

  3. Self-powered micro-structured solid state neutron detector with very low leakage current and high efficiency

    NASA Astrophysics Data System (ADS)

    Dahal, R.; Huang, K. C.; Clinton, J.; LiCausi, N.; Lu, J.-Q.; Danon, Y.; Bhat, I.

    2012-06-01

    We report on the design, fabrication, and performance of solid-state neutron detector based on three-dimensional honeycomb-like silicon micro-structures. The fabricated detectors use boron filled deep holes with aspect ratio of over 12 and showed a very low leakage current density of ˜7 × 10-7 A/cm2 at -1 V for device sizes varying from 2 × 2 to 5 × 5 mm2. A thermal neutron detection efficiency of 4.5% ± 0.5% with discrimination setting of 500 keV and gamma to neutron sensitivity of (1.1 ± 0.1) × 10-5 for single layer was measured without external bias for these devices. Monte-Carlo simulation predicts a maximum efficiency of 45% for such devices filled with 95% enriched 10boron.

  4. Glass Property Models and Constraints for Estimating the Glass to be Produced at Hanford by Implementing Current Advanced Glass Formulation Efforts

    SciTech Connect

    Vienna, John D.; Kim, Dong-Sang; Skorski, Daniel C.; Matyas, Josef

    2013-07-31

    Recent glass formulation and melter testing data have suggested that significant increases in waste loading in HLW and LAW glasses are possible over current system planning estimates. The data (although limited in some cases) were evaluated to determine a set of constraints and models that could be used to estimate the maximum loading of specific waste compositions in glass. It is recommended that these models and constraints be used to estimate the likely HLW and LAW glass volumes that would result if the current glass formulation studies are successfully completed. It is recognized that some of the models are preliminary in nature and will change in the coming years. Plus the models do not currently address the prediction uncertainties that would be needed before they could be used in plant operations. The models and constraints are only meant to give an indication of rough glass volumes and are not intended to be used in plant operation or waste form qualification activities. A current research program is in place to develop the data, models, and uncertainty descriptions for that purpose. A fundamental tenet underlying the research reported in this document is to try to be less conservative than previous studies when developing constraints for estimating the glass to be produced by implementing current advanced glass formulation efforts. The less conservative approach documented herein should allow for the estimate of glass masses that may be realized if the current efforts in advanced glass formulations are completed over the coming years and are as successful as early indications suggest they may be. Because of this approach there is an unquantifiable uncertainty in the ultimate glass volume projections due to model prediction uncertainties that has to be considered along with other system uncertainties such as waste compositions and amounts to be immobilized, split factors between LAW and HLW, etc.

  5. The relative anticaries effectiveness of sodium monofluorophosphate and sodium fluoride as contained in currently available dentifrice formulations.

    PubMed

    DePaola, P F; Soparkar, P M; Triol, C; Volpe, A R; Garcia, L; Duffy, J; Vaughan, B

    1993-09-01

    A 36-month double-blind clinical caries study was conducted to determine the comparative anticaries efficacy of sodium monofluorophosphate (MFP) and sodium fluoride (NaF) as incorporated in dentifrice formulations. The test dentifrices which were utilized are commercially available in the United States and all have been granted the American Dental Association Seal of Acceptance for anticaries efficacy. The study was conducted in accordance with the 1988 Guidelines of the American Dental Association Council on Dental Therapeutics. The two formulations used in the NaF versus MFP comparison were Colgate Winterfresh Gel with 0.76% sodium monofluorophosphate in a silica base and Crest Regular Flavor Toothpaste with 0.24% sodium fluoride in a silica base. A third commercially-available NaF dentifrice, Colgate Junior Toothpaste with 0.243% sodium fluoride in a silica base, was included in the study for further comparison. Schoolchildren residing in Maine, U.S.A. received a baseline caries clinical examination and then were randomly assigned to the twice-daily use of one of the three dentifrices which were purchased in the marketplace and repackaged in plain white tubes. Caries clinical examinations were subsequently conducted after 2 and 3 years' use of the dentifrices. A total of 2,222 children participated in both the 2 and 3-year caries clinical examinations. The 36-month DFS (decayed and filled surfaces) and the DFT (decayed and filled teeth) mean caries increments for the three dentifrice groups were virtually identical. The children using the MFP formulation experienced a DFS of 1.50 and a DFT of 1.08; those using the Crest NaF formulation experienced a DFS of 1.48 and a DFT of 1.07; subjects in the third group (Colgate Junior Toothpaste, 0.243% NaF) had a DFS of 1.49 and DFT of 1.06. The statistical evaluation of the data consisted of the calculation of 90% confidence bounds for the ratio of (true) mean increments, in accordance with the 1988 American Dental

  6. Clinical evaluation of neutron beam therapy. Current results and prospects, 1983

    SciTech Connect

    Cohen, L.; Hendrickson, F.R.; Kurup, P.D.; Mansell, J.A.; Awschalom, M.; Rosenberg, I.; Ten Haken, R.K.

    1985-01-01

    Some 9000 patients throughout the world have been treated by some form of neutron beam therapy. These include patients with advanced nonresectable tumors in many different sites treated with a variety of neutron beam generators varying widely in beam energy. Protocols were largely nonrandomized and included both mixed beam studies (neutrons + photons) and neutrons alone in varying doses. In spite of wide variation in equipment, treatment technique, and philosophy, some consistent trends have been identified: (1) in general, the neutron results have been at least as good as those of the photon controls measured in terms of local control, although the incidence of significant side effects have been higher; (2) in none of the randomized studies conducted so far, largely comprising epidermoid carcinomas of the head and neck, has a clear survival advantage for neutrons over photon controls been demonstrated at a statistically significant level; (3) results with mixed beam studies have been uniformly equivocal, with marginally significant differences in favor of the experimental groups compared with the photon controls; (4) adenocarcinomas of the gastrointestinal tract (GI) tract, including tumors of the salivary gland, pancreas, stomach, and bowel, appear to be responsive to high linear energy transfer (LET) radiation; (5) nonepidermoid, radioresistant tumors (sarcoma of bone and soft tissue and melanoma) yield a consistantly high local control rate, with neutron irradiation strikingly superior to those reported with photon therapy; and (6) in the central nervous system, both normal tissues and tumors appear to be exceptionally sensitive to neutron irradiation, therapeutic ratios are small, and the prospect of cure remains remote. It is concluded that neutrons are efficacious for certain specific tumor types, but that essentially new study designs, based on nonrandomized matched case comparisons, will be required to prove the merit of the new modality.

  7. Neutron Emission Characteristics of a High-Current Plasma Focus: Initial Studies

    SciTech Connect

    L. H. Ziegler; B. L. Freeman; J. C. Boydston

    2002-06-01

    The Texas A and M University plasma focus machine is operational and is beginning to provide good experimental data. It has its origins in several earlier machines and is located in a former service station building with a shield wall that provides a good geometry for neutron measurements. We are operating in the high pressure mode for a plasma focus, similar to previous efforts in the US. Early neutron measurements are providing some insight for the machine's operation.

  8. Pixel pitch and particle energy influence on the dark current distribution of neutron irradiated CMOS image sensors.

    PubMed

    Belloir, Jean-Marc; Goiffon, Vincent; Virmontois, Cédric; Raine, Mélanie; Paillet, Philippe; Duhamel, Olivier; Gaillardin, Marc; Molina, Romain; Magnan, Pierre; Gilard, Olivier

    2016-02-22

    The dark current produced by neutron irradiation in CMOS Image Sensors (CIS) is investigated. Several CIS with different photodiode types and pixel pitches are irradiated with various neutron energies and fluences to study the influence of each of these optical detector and irradiation parameters on the dark current distribution. An empirical model is tested on the experimental data and validated on all the irradiated optical imagers. This model is able to describe all the presented dark current distributions with no parameter variation for neutron energies of 14 MeV or higher, regardless of the optical detector and irradiation characteristics. For energies below 1 MeV, it is shown that a single parameter has to be adjusted because of the lower mean damage energy per nuclear interaction. This model and these conclusions can be transposed to any silicon based solid-state optical imagers such as CIS or Charged Coupled Devices (CCD). This work can also be used when designing an optical imager instrument, to anticipate the dark current increase or to choose a mitigation technique. PMID:26907077

  9. Measurement of the ratio of total and differential cross sections on neutrons and protons for charged-current neutrino events

    NASA Astrophysics Data System (ADS)

    Armenise, N.; Calicchio, M.; Erriquez, O.; Fogli-Muciaccia, M. T.; Natali, S.; Nuzzo, S.; Romano, F.; Belusevic, R.; Colley, D. C.; Jones, G. T.; O'Neale, S.; Sewell, S. J.; Votruba, M. F.; Bertrand, D.; Moreels, J.; Sacton, J.; Vander Velde-Wilquet, C.; Van Doninck, W.; Wilquet, G.; Brisson, V.; Francois, T.; Petiau, P.; Cooper, A. M.; Guy, J. G.; Michette, A. G.; Tyndel, M.; Venus, W.; Alitti, J.; Baton, J. P.; Gerbier, G.; Iori, M.; Kochowski, C.; Neveu, M.; Azemoon, T.; Bartley, J. H.; Bullock, F. W.; Davis, D. H.; Jones, T. W.; Parker, M. A.; BEBC TST Neutrino Collaboration

    1981-06-01

    Charged-current neutrino interactions have been analysed in a sample of pictures from BEBC equipped with a TST. Using a method independent of both the neutrino flux and nuclear interaction corrections, the ratio R= σn/ σp has been measured. The result is R=1.98±0.19 for the ratio of total cross sections. Bjorken x distributions for proton and neutron targets and for u and d quarks are compared.

  10. Self-consistent quasiparticle formulation of a multiphonon method and its application to the neutron-rich O20 nucleus

    NASA Astrophysics Data System (ADS)

    De Gregorio, G.; Knapp, F.; Lo Iudice, N.; Vesely, P.

    2016-04-01

    A Bogoliubov quasiparticle formulation of an equation-of-motion phonon method, suited for open-shell nuclei, is derived. Like its particle-hole version, it consists of deriving a set of equations of motions whose iterative solution generates an orthonormal basis of n -phonon states (n =0 ,1 ,2 ,... ), built of quasiparticle Tamm-Dancoff phonons, which simplifies the solution of the eigenvalue problem. The method is applied to the open-shell neutron-rich O20 for illustrative purposes. A Hartree-Fock-Bogoliubov canonical basis, derived from an intrinsic two-body optimized chiral Hamiltonian, is used to derive and solve the eigenvalue equations in a space encompassing a truncated two-phonon basis. The spurious admixtures induced by the violation of the particle number and the center-of-mass motion are eliminated to a large extent by a Gram-Schmidt orthogonalization procedure. The calculation takes into account the Pauli principle, is self-consistent, and is parameter free except for the energy cutoff used to truncate the two-phonon basis, which induces an increasing depression of the ground state through its strong coupling to the quasiparticle vacuum. Such a cutoff is fixed so as to reproduce the first 1- level. The two-phonon states are shown to enhance the level density of the low-energy spectrum, consistently with the data, and to induce a fragmentation of the E 1 strength which, while accounting for the very low E 1 transitions, is not sufficient to reproduce the experimental cross section in the intermediate energy region. This and other discrepancies suggest the need of including the three-phonon states. These are also expected to offset the action of the two phonons on the quasiparticle vacuum and, therefore, free the calculation from any parameter.

  11. Current status of boron neutron capture therapy of high grade gliomas and recurrent head and neck cancer

    PubMed Central

    2012-01-01

    Boron neutron capture therapy (BNCT) is a biochemically targeted radiotherapy based on the nuclear capture and fission reactions that occur when non-radioactive boron-10, which is a constituent of natural elemental boron, is irradiated with low energy thermal neutrons to yield high linear energy transfer alpha particles and recoiling lithium-7 nuclei. Clinical interest in BNCT has focused primarily on the treatment of high grade gliomas, recurrent cancers of the head and neck region and either primary or metastatic melanoma. Neutron sources for BNCT currently have been limited to specially modified nuclear reactors, which are or until the recent Japanese natural disaster, were available in Japan, the United States, Finland and several other European countries, Argentina and Taiwan. Accelerators producing epithermal neutron beams also could be used for BNCT and these are being developed in several countries. It is anticipated that the first Japanese accelerator will be available for therapeutic use in 2013. The major hurdle for the design and synthesis of boron delivery agents has been the requirement for selective tumor targeting to achieve boron concentrations in the range of 20 μg/g. This would be sufficient to deliver therapeutic doses of radiation with minimal normal tissue toxicity. Two boron drugs have been used clinically, a dihydroxyboryl derivative of phenylalanine, referred to as boronophenylalanine or “BPA”, and sodium borocaptate or “BSH” (Na2B12H11SH). In this report we will provide an overview of other boron delivery agents that currently are under evaluation, neutron sources in use or under development for BNCT, clinical dosimetry, treatment planning, and finally a summary of previous and on-going clinical studies for high grade gliomas and recurrent tumors of the head and neck region. Promising results have been obtained with both groups of patients but these outcomes must be more rigorously evaluated in larger, possibly randomized

  12. Current conservation and analytic determination of the magnetic moment of the Δ resonance in the πN bremsstrahlung: II. Formulation with quark degrees of freedom. III. Magnetic moment of the Δo and Δ- resonances

    NASA Astrophysics Data System (ADS)

    Machavariani, A. I.; Faessler, Amand

    2011-03-01

    Our previous paper (Machavariani and Faessler 2010 J. Phys. G: Nucl. Part. Phys. 37 075004) is generalized within the field-theoretical formulation with the quark-gluon degrees of freedom (Huang and Weldon 1975 Phys. Rev. D11 257; Haag 1958 Phys. Rev. 112 669; Nishijima 1958 Phys. Rev. 111 995; Zimmermann 1958 Nuovo Cimento 10 598), where pions and nucleons are treated as the bound (cluster) systems of quarks. It is shown that current conservation for the on-shell πN bremsstrahlung amplitude with the composite nucleons and pions has the same form as in the usual quantum field theory (Itzykson and Zuber 1980 Quantum Field Theory (New York: McGraw-Hill); Bjorken and Drell 1965 Relativistic Quantum Fields (New York: McGraw-Hill)) without quark-gluon degrees of freedom (Machavariani and Faessler 2010). The model-independent representation of the Δ - γ'Δ vertex through the π - γ'π', N - γ'N', Δ - πN vertices remain the same in the quantum field theory with the quark-gluon degrees of freedom. Correspondingly, the magnetic dipole moments of the Δ+ and Δ++ resonances in the field-theoretical formulations with and without quark-gluons are identical. These results are extended for the magnetic dipole moments of the Δo and Δ- resonances which are determined via the anomalous magnetic moment of the neutron μn as \\mu _{\\Delta ^o}={ {M_{\\Delta }}\\over {m_p}} \\mu _n and \\mu _{\\Delta ^{-}}={3\\over 2}\\mu _{\\Delta ^o}.

  13. Current and anticipated uses of thermalhydraulic and neutronic codes at PSI

    SciTech Connect

    Aksan, S.N.; Zimmermann, M.A.; Yadigaroglu, G.

    1997-07-01

    The thermalhydraulic and/or neutronic codes in use at PSI mainly provide the capability to perform deterministic safety analysis for Swiss NPPs and also serve as analysis tools for experimental facilities for LWR and ALWR simulations. In relation to these applications, physical model development and improvements, and assessment of the codes are also essential components of the activities. In this paper, a brief overview is provided on the thermalhydraulic and/or neutronic codes used for safety analysis of LWRs, at PSI, and also of some experiences and applications with these codes. Based on these experiences, additional assessment needs are indicated, together with some model improvement needs. The future needs that could be used to specify both the development of a new code and also improvement of available codes are summarized.

  14. Solutions Network Formulation Report. Improving NOAA's Tides and Currents Through Enhanced Data Inputs from NASA's Ocean Surface Topography Mission

    NASA Technical Reports Server (NTRS)

    Guest, DeNeice C.

    2006-01-01

    The Nation uses water-level data for a variety of practical purposes, including hydrography, nautical charting, maritime navigation, coastal engineering, and tsunami and storm surge warnings (NOAA, 2002; Digby et al., 1999). Long-term applications include marine boundary determinations, tidal predictions, sea-level trend monitoring, oceanographic research, and climate research. Accurate and timely information concerning sea-level height, tide, and ocean current is needed to understand their impact on coastal management, disaster management, and public health. Satellite altimeter data products are currently used by hundreds of researchers and operational users to monitor ocean circulation and to improve scientists understanding of the role of the oceans in climate and weather. The NOAA (National Oceanic and Atmospheric Administration) National Ocean Service has been monitoring sea-level variations for many years (NOAA, 2006). NOAA s Tides & Currents DST (decision support tool, managed by the Center for Operational Oceanographic Products and Services, is the portal to a vast collection of oceanographic and meteorological data (historical and real-time), predictions, and nowcasts and forecasts. This report assesses the capacity of NASA s satellite altimeter data to meet societal decision support needs through incorporation into NOAA s Tides & Currents.

  15. A novel method for modeling the neutron time of flight detector response in current mode to inertial confinement fusion experiments (invited)

    SciTech Connect

    Nelson, A. J.; Cooper, G. W.; Ruiz, C. L.; Chandler, G. A.; Fehl, D. L.; Hahn, K. D.; Leeper, R. J.; Smelser, R.; Torres, J. A.

    2012-10-15

    A novel method for modeling the neutron time of flight (nTOF) detector response in current mode for inertial confinement fusion experiments has been applied to the on-axis nTOF detectors located in the basement of the Z-Facility. It will be shown that this method can identify sources of neutron scattering, and is useful for predicting detector responses in future experimental configurations, and for identifying potential sources of neutron scattering when experimental set-ups change. This method can also provide insight on how much broadening neutron scattering contributes to the primary signals, which is then subtracted from them. Detector time responses are deconvolved from the signals, allowing a transformation from dN/dt to dN/dE, extracting neutron spectra at each detector location; these spectra are proportional to the absolute yield.

  16. Critical current densities in neutron irradiated Tl 2Ca 2Ba 2Cu 3O 10 single crystals

    NASA Astrophysics Data System (ADS)

    Brandstätter, G.; Sauerzopf, F. M.; Weber, H. W.; Aghaei, A.; Schwarzmann, F.

    1994-12-01

    A Tl 2Ca 2Ba 2Cu 3O 10 single crystal with a transition temperature of 117.5 K was subjected to fast neutron irradiation to fluences of 2·10 21, 4·10 21, 8·10 21, and 1.6·10 22 m 2 (E>0.1 MeV). The superconducting transition temperatures T c, the hysteresis loops and the irreversibility lines were measured before and after each irradiation step. The critical current densities J c were calculated from the magnetization loops using an anisotropic Bean model. With increasing fluence we find a decrease of T c, as observed in YBCO-123 and other high temperature superconductors, and an increase of J c. The irreversibility line is shifted to higher fields and temperatures.

  17. Commissioning of the NPDGamma Detector Array: Counting Statistics in Current Mode Operation and Parity Violation in the Capture of Cold Neutrons on B4C and 27Al

    PubMed Central

    Gericke, M. T.; Bowman, J. D.; Carlini, R. D.; Chupp, T. E.; Coulter, K. P.; Dabaghyan, M.; Desai, D.; Freedman, S. J.; Gentile, T. R.; Gillis, R. C.; Greene, G. L.; Hersman, F. W.; Ino, T.; Ishimoto, S.; Jones, G. L.; Lauss, B.; Leuschner, M. B.; Losowski, B.; Mahurin, R.; Masuda, Y.; Mitchell, G. S.; Muto, S.; Nann, H.; Page, S. A.; Penttila, S. I.; Ramsay, W. D.; Santra, S.; Seo, P.-N.; Sharapov, E. I.; Smith, T. B.; Snow, W. M.; Wilburn, W. S.; Yuan, V.; Zhu, H.

    2005-01-01

    The NPDGamma γ-ray detector has been built to measure, with high accuracy, the size of the small parity-violating asymmetry in the angular distribution of gamma rays from the capture of polarized cold neutrons by protons. The high cold neutron flux at the Los Alamos Neutron Scattering Center (LANSCE) spallation neutron source and control of systematic errors require the use of current mode detection with vacuum photodiodes and low-noise solid-state preamplifiers. We show that the detector array operates at counting statistics and that the asymmetries due to B4C and 27Al are zero to with- in 2 × 10−6 and 7 × 10−7, respectively. Boron and aluminum are used throughout the experiment. The results presented here are preliminary. PMID:27308124

  18. Current risk estimates based on the A-bomb survivors data - a discussion in terms of the ICRP recommendations on the neutron weighting factor.

    PubMed

    Rühm, W; Walsh, L

    2007-01-01

    Currently, most analyses of the A-bomb survivors' solid tumour and leukaemia data are based on a constant neutron relative biological effectiveness (RBE) value of 10 that is applied to all survivors, independent of their distance to the hypocentre at the time of bombing. The results of these analyses are then used as a major basis for current risk estimates suggested by the International Commission on Radiological Protection (ICRP) for use in international safety guidelines. It is shown here that (i) a constant value of 10 is not consistent with weighting factors recommended by the ICRP for neutrons and (ii) it does not account for the hardening of the neutron spectra in Hiroshima and Nagasaki, which takes place with increasing distance from the hypocentres. The purpose of this paper is to present new RBE values for the neutrons, calculated as a function of distance from the hypocentres for both cities that are consistent with the ICRP60 neutron weighting factor. If based on neutron spectra from the DS86 dosimetry system, these calculations suggest values of about 31 at 1000 m and 23 at 2000 m ground range in Hiroshima, while the corresponding values for Nagasaki are 24 and 22. If the neutron weighting factor that is consistent with ICRP92 is used, the corresponding values are about 23 and 21 for Hiroshima and 21 and 20 for Nagasaki, respectively. It is concluded that the current risk estimates will be subject to some changes in view of the changed RBE values. This conclusion does not change significantly if the new doses from the Dosimetry System DS02 are used. PMID:17533156

  19. Direct current H- source for boron neutron capture therapy tandem acceleratora)

    NASA Astrophysics Data System (ADS)

    Belchenko, Yu.; Sanin, A.; Gusev, I.; Khilchenko, A.; Kvashnin, A.; Rashchenko, V.; Savkin, V.; Zubarev, P.

    2008-02-01

    One year experience of dc H- source operation at 2MeV tandem accelerator is described. The source delivers H- ion beams with controlled current in the range of 1-8mA and energy up to 25keV. Normalized 1rms emittance for 8mA beam is less than 0.2πmmmrad. Negative ions are produced on the cesiated anode of the Penning discharge, driven by plasma injection from the hollow cathode inserts.

  20. Direct current H{sup -} source for boron neutron capture therapy tandem accelerator

    SciTech Connect

    Belchenko, Yu.; Sanin, A.; Gusev, I.; Khilchenko, A.; Kvashnin, A.; Rashchenko, V.; Savkin, V.; Zubarev, P.

    2008-02-15

    One year experience of dc H{sup -} source operation at 2 MeV tandem accelerator is described. The source delivers H{sup -} ion beams with controlled current in the range of 1-8 mA and energy up to 25 keV. Normalized 1 rms emittance for 8 mA beam is less than 0.2{pi} mm mrad. Negative ions are produced on the cesiated anode of the Penning discharge, driven by plasma injection from the hollow cathode inserts.

  1. Formal analysis of the urban 'Dutch model' with aims of re-formulating spatial quality concerns for pedestrian precincts in current New Town developments.

    PubMed

    Ishida, Toshikazu

    2005-01-01

    In the Japanese post WWII urban planning and design field, concerns for formal features regarding the sequential street-front visual image in new high-density urban spaces have been a rather subordinated subject. Famous New Town schemes such as Tsukuba Science City (1963), or Minato Mirai 21 (1965) for instance, are typical inland and reclaimed land examples that summarize the validity and limitations of functional zoning systems applied to these artificial urban developments for the last half century. In those examples, the interaction between space mobility and land use has not been explored sufficiently in order to create attractive street-front images, yet such interaction is essential to the way the cityscape and its character are perceived by the eye. However, current insight regarding the sustainable New Town paradigm has brought a renewed perspective regarding design policy of the pedestrian precinct. This study investigates the formal features of the sequential street-front image of Dutch late-medieval town examples which could help re-formulate the existing design policies regarding the quality of pedestrian space especially in the artificial reclaimed land design field. The purpose is to find out how the principles of those old high-density artificial environmental design models generate such effective interaction between mobility and land usage, creating an enriched aesthetic visual image of street-front space as a result. PMID:15684563

  2. Optical absorption and thermally stimulated depolarization current studies of nickel chloride-doped poly(vinyl alcohol) irradiated with low-level fast neutron doses

    SciTech Connect

    Abd El-Kader, F.H.; Ibrahim, S.S. . Physics Dept.); Attia, G. . Faculty of Education)

    1993-11-15

    The influence of neutron irradiation on ultraviolet/visible absorption and thermally stimulated depolarization current in nickel chloride-poly(vinyl alcohol) (PVA) cast films has been investigated. The spectral measurements indicate the responsibility of the Ni[sup 2][sup +] ion in its octahedral symmetry. Dopant concentrations higher than 10 wt % NiCl[sub 2] are found to make the samples more resistant to a degradation effect caused by neutron irradiation. The thermally stimulated depolarization currents (TSDC) of pure PVA revealed the existence of the glass transition T[sub g] and space charge relaxation peaks, whereas doped-PVA samples show a new sub-T[sub g] relaxation peak. A proposed mechanism is introduced to account for the neutron effects on both glass transition and space charge relaxation peaks. The peak positions, peak currents, and stored charges of the sub-T[sub g] relaxation peak are strongly affected by both the concentration of the dopant and neutron exposure doses.

  3. Formulation techniques for nanofluids.

    PubMed

    Rivera-Solorio, Carlos I; Payán-Rodríguez, Luis A; García-Cuéllar, Alejandro J; Ramón-Raygoza, E D; L Cadena-de-la-Peña, Natalia; Medina-Carreón, David

    2013-11-01

    Fluids with suspended nanoparticles, commonly known as nanofluids, may be formulated to improve the thermal performance of industrial heat transfer systems and applications. Nanofluids may show enhanced thermal and electrical properties such as thermal conductivity, viscosity, heat transfer coefficient, dielectric strength, etc. However, stability problems may arise as nanoparticles usually have the tendency to agglomerate and sediment producing deterioration in the increment of these properties. In this review, we discuss patents that report advances in the formulation of nanofluids including: production methods, selection of components (nanoparticles, base fluid and surfactants), their chemical compositions and morphologies, and characterization techniques. Finally, current and future directions in the development of nanofluid formulation are discussed. PMID:24330043

  4. Toward Mega-pixel Neutron Imager Using Current-Biased Kinetic Inductance Detectors of Nb Nanowires with $(10) $ 10 B Converter

    NASA Astrophysics Data System (ADS)

    Ishida, Takekazu; Yoshioka, Naohito; Narukami, Yoshito; Shishido, Hiroaki; Miyajima, Shigeyuki; Fujimaki, Akira; Miki, Shigehito; Wang, Zhen; Hidaka, Mutsuo

    2014-08-01

    We present not the results but the idea of a superconducting nanowire detector with B conversion layer for sensing a single neutron. We use Li ion and He ion emitted as two independent heat sources, which appear in opposite direction associated with nuclear reaction B(n,He)Li. We probe a change in the kinetic inductance coming from inertia of the Cooper pairs. Our detector is different from a conventional kinetic inductance detector (KID), but is named as a current-biased KID. We use two sets of Nb nanowires with superconducting readout taps to monitor the local signal. In between the X meander and the Y meander, we inserted a B layer acting as a conversion layer from neutrons to charged particles. We plan to fabricate a mega-pixel neutron imager by coupling 10 bit linear position-sensitive arrays along the X and Y directions with the single flux quantum readout circuits.

  5. Design of a high-current low-energy beam transport line for an intense D-T/D-D neutron generator

    NASA Astrophysics Data System (ADS)

    Lu, Xiaolong; Wang, Junrun; Zhang, Yu; Li, Jianyi; Xia, Li; Zhang, Jie; Ding, Yanyan; Jiang, Bing; Huang, Zhiwu; Ma, Zhanwen; Wei, Zheng; Qian, Xiangping; Xu, Dapeng; Lan, Changlin; Yao, Zeen

    2016-03-01

    An intense D-T/D-D neutron generator is currently being developed at the Lanzhou University. The Cockcroft-Walton accelerator, as a part of the neutron generator, will be used to accelerate and transport the high-current low-energy beam from the duoplasmatron ion source to the rotating target. The design of a high-current low-energy beam transport (LEBT) line and the dynamics simulations of the mixed beam were carried out using the TRACK code. The results illustrate that the designed beam line facilitates smooth transportation of a deuteron beam of 40 mA, and the number of undesired ions can be reduced effectively using two apertures.

  6. Research on anisotropy of fusion-produced protons and neutrons emission from high-current plasma-focus discharges.

    PubMed

    Malinowski, K; Skladnik-Sadowska, E; Sadowski, M J; Szydlowski, A; Czaus, K; Kwiatkowski, R; Zaloga, D; Paduch, M; Zielinska, E

    2015-01-01

    The paper concerns fast protons and neutrons from D-D fusion reactions in a Plasma-Focus-1000U facility. Measurements were performed with nuclear-track detectors arranged in "sandwiches" of an Al-foil and two PM-355 detectors separated by a polyethylene-plate. The Al-foil eliminated all primary deuterons, but was penetrable for fast fusion protons. The foil and first PM-355 detector were penetrable for fast neutrons, which were converted into recoil-protons in the polyethylene and recorded in the second PM-355 detector. The "sandwiches" were irradiated by discharges of comparable neutron-yields. Analyses of etched tracks and computer simulations of the fusion-products behavior in the detectors were performed. PMID:25638081

  7. Research on anisotropy of fusion-produced protons and neutrons emission from high-current plasma-focus discharges

    SciTech Connect

    Malinowski, K. Sadowski, M. J.; Szydlowski, A.; Skladnik-Sadowska, E.; Czaus, K.; Kwiatkowski, R.; Zaloga, D.; Paduch, M.; Zielinska, E.

    2015-01-15

    The paper concerns fast protons and neutrons from D-D fusion reactions in a Plasma-Focus-1000U facility. Measurements were performed with nuclear-track detectors arranged in “sandwiches” of an Al-foil and two PM-355 detectors separated by a polyethylene-plate. The Al-foil eliminated all primary deuterons, but was penetrable for fast fusion protons. The foil and first PM-355 detector were penetrable for fast neutrons, which were converted into recoil-protons in the polyethylene and recorded in the second PM-355 detector. The “sandwiches” were irradiated by discharges of comparable neutron-yields. Analyses of etched tracks and computer simulations of the fusion-products behavior in the detectors were performed.

  8. A novel method for modeling the neutron time of flight (nTOF) detector response in current mode to inertial confinement fusion experiments.

    SciTech Connect

    Nelson, Alan J.; Cooper, Gary Wayne; Ruiz, Carlos L.; Chandler, Gordon Andrew; Fehl, David Lee; Hahn, Kelly Denise; Leeper, Ramon Joe; Smelser, Ruth Marie; Torres, Jose A.

    2013-09-01

    There are several machines in this country that produce short bursts of neutrons for various applications. A few examples are the Zmachine, operated by Sandia National Laboratories in Albuquerque, NM; the OMEGA Laser Facility at the University of Rochester in Rochester, NY; and the National Ignition Facility (NIF) operated by the Department of Energy at Lawrence Livermore National Laboratory in Livermore, California. They all incorporate neutron time of flight (nTOF) detectors which measure neutron yield, and the shapes of the waveforms from these detectors contain germane information about the plasma conditions that produce the neutrons. However, the signals can also be %E2%80%9Cclouded%E2%80%9D by a certain fraction of neutrons that scatter off structural components and also arrive at the detectors, thereby making analysis of the plasma conditions more difficult. These detectors operate in current mode - i.e., they have no discrimination, and all the photomultiplier anode charges are integrated rather than counted individually as they are in single event counting. Up to now, there has not been a method for modeling an nTOF detector operating in current mode. MCNPPoliMiwas developed in 2002 to simulate neutron and gammaray detection in a plastic scintillator, which produces a collision data output table about each neutron and photon interaction occurring within the scintillator; however, the postprocessing code which accompanies MCNPPoliMi assumes a detector operating in singleevent counting mode and not current mode. Therefore, the idea for this work had been born: could a new postprocessing code be written to simulate an nTOF detector operating in current mode? And if so, could this process be used to address such issues as the impact of neutron scattering on the primary signal? Also, could it possibly even identify sources of scattering (i.e., structural materials) that

  9. Effect of high current electron beam in a 30 MeV radio frequency linac for neutron-time-of-flight applications

    NASA Astrophysics Data System (ADS)

    Nayak, B.; Acharya, S.; Rajawat, R. K.; DasGupta, K.

    2016-01-01

    A high power pulsed radio frequency electron linac is designed by BARC, India to accelerate 30 MeV, 10 A, 10 ns beam for neutron-time-of-flight applications. It will be used as a neutron generator and will produce ˜1012-1013 n/s. It is essential to reduce the beam instability caused by space charge effect and the beam cavity interaction. In this paper, the wakefield losses in the accelerating section due to bunch of RMS (Root mean square) length 2 mm (at the gun exit) is analysed. Loss and kick factors are numerically calculated using CST wakefield solver. Both the longitudinal and transverse wake potentials are incorporated in beam dynamics code ELEGANT to find the transverse emittance growth of the beam propagating through the linac. Beam loading effect is examined by means of numerical computation carried out in ASTRA code. Beam break up start current has been estimated at the end of the linac which arises due to deflecting modes excited by the high current beam. At the end, transverse beam dynamics of such high current beam has been analysed.

  10. Correlated evolution of barrier capacitance charging, generation, and drift currents and of carrier lifetime in Si structures during 25 MeV neutrons irradiation

    SciTech Connect

    Gaubas, E.; Ceponis, T.; Jasiunas, A.; Uleckas, A.; Vaitkus, J.; Cortina, E.; Militaru, O.

    2012-12-03

    The in situ examination of barrier capacitance charging, of generation and drift currents, and of carrier lifetime in Si structures during 25 MeV neutrons irradiation has been implemented to correlate radiation induced changes in carrier recombination, thermal release, and drift characteristics and to clarify their impact on detector performance. It has been shown that microwave probed photo-conductivity technique implemented in contact-less and distant manner can be a powerful tool for examination in wide dynamic range of carrier lifetime modified by radiation defects and for rather precise prediction of detector performance.

  11. An Improved Neutron Transport Algorithm for HZETRN

    NASA Technical Reports Server (NTRS)

    Slaba, Tony C.; Blattnig, Steve R.; Clowdsley, Martha S.; Walker, Steven A.; Badavi, Francis F.

    2010-01-01

    Long term human presence in space requires the inclusion of radiation constraints in mission planning and the design of shielding materials, structures, and vehicles. In this paper, the numerical error associated with energy discretization in HZETRN is addressed. An inadequate numerical integration scheme in the transport algorithm is shown to produce large errors in the low energy portion of the neutron and light ion fluence spectra. It is further shown that the errors result from the narrow energy domain of the neutron elastic cross section spectral distributions, and that an extremely fine energy grid is required to resolve the problem under the current formulation. Two numerical methods are developed to provide adequate resolution in the energy domain and more accurately resolve the neutron elastic interactions. Convergence testing is completed by running the code for various environments and shielding materials with various energy grids to ensure stability of the newly implemented method.

  12. Plutonium Immobilization Project Baseline Formulation

    SciTech Connect

    Ebbinghaus, B.

    1999-02-01

    A key milestone for the Immobilization Project (AOP Milestone 3.2a) in Fiscal Year 1998 (FY98) is the definition of the baseline composition or formulation for the plutonium ceramic form. The baseline formulation for the plutonium ceramic product must be finalized before the repository- and plant-related process specifications can be determined. The baseline formulation that is currently specified is given in Table 1.1. In addition to the baseline formulation specification, this report provides specifications for two alternative formulations, related compositional specifications (e.g., precursor compositions and mixing recipes), and other preliminary form and process specifications that are linked to the baseline formulation. The preliminary specifications, when finalized, are not expected to vary tremendously from the preliminary values given.

  13. Entrainment coefficient and effective mass for conduction neutrons in neutron star crust: simple microscopic models

    NASA Astrophysics Data System (ADS)

    Carter, Brandon; Chamel, Nicolas; Haensel, Pawel

    2005-02-01

    In the inner crust of a neutron star, at densities above the "drip" threshold, unbound "conduction" neutrons can move freely past through the ionic lattice formed by the nuclei. The relative current density ni=nv¯i of such conduction neutrons will be related to the corresponding mean particle momentum pi by a proportionality relation of the form ni=Kpi in terms of a physically well defined mobility coefficient K whose value in this context has not been calculated before. Using methods from ordinary solid state and nuclear physics, a simple quantum mechanical treatment based on the independent particle approximation, is used here to formulate K as the phase space integral of the relevant group velocity over the neutron Fermi surface. The result can be described as an "entrainment" that changes the ordinary neutron mass m to a macroscopic effective mass per neutron that will be given—subject to adoption of a convention specifying the precise number density n of the neutrons that are considered to be "free"—by m⋆=n/K. The numerical evaluation of the mobility coefficient is carried out for nuclear configurations of the "lasagna" and "spaghetti" type that may be relevant at the base of the crust. Extrapolation to the middle layers of the inner crust leads to the unexpected prediction that m⋆ will become very large compared with m.

  14. Current difficulties and recent advances in bypass therapy for the management of hemophilia with inhibitors: a new and practical formulation of recombinant factor VIIa.

    PubMed

    Butros, Linda; Boayue, Koh; Mathew, Prasad

    2011-01-01

    Bypassing agents are the mainstay of treatment for patients with hemophilia with high-titer inhibitors. Whereas the availability of these agents has greatly advanced the management of bleeding episodes in this population, timely administration of bypassing agents continues to be hampered by a number of practical limitations, including the need for refrigerated storage of the agent and its reconstitution at room temperature prior to administration, among others. In this review, the importance of early treatment of bleeds and factors that influence this more timely therapeutic approach are highlighted, together with the advantages offered by the use of a new formulation of recombinant activated factor VII that permits improved storage and portability, potentially optimizing timely bypassing agent administration. PMID:21625417

  15. Flux-lines lattice order and critical current studied by time-of-flight small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Pautrat, Alain; Brulet, Annie; Simon, Charles; Mathieu, Patrice

    2012-05-01

    Small-angle neutron scattering is a historical technique to study the flux-lines lattice (FLL) in a superconductor. Structural characteristics of the FLL can be revealed, providing fundamental information for the physics of a vortex lattice. However, the spatial resolution is limited and all of the correlation lengths of order are difficult to extract with precision. We show here that a time-of-flight technique reveals the Bragg peak of the FLL, and also its translational order with a better resolution. We discuss the implication of these results for pinning mechanisms in a niobium sample.

  16. FOREWORD: Neutron metrology Neutron metrology

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    industry, from the initial fuel enrichment and fabrication processes right through to storage or reprocessing, and neutron metrology is clearly important in this area. Neutron fields do, however, occur in other areas, for example where neutron sources are used in oil well logging and moisture measurements. They also occur around high energy accelerators, including photon linear accelerators used for cancer therapy, and are expected to be a more serious problem around the new hadron radiation therapy facilities. Roughly 50% of the cosmic ray doses experienced by fliers at the flight altitudes of commercial aircraft are due to neutrons. Current research on fusion presents neutron metrology with a whole new range of challenges because of the very high fluences expected. One of the most significant features of neutron fields is the very wide range of possible neutron energies. In the nuclear industry, for example, neutrons occur with energies from those of thermal neutrons at a few meV to the upper end of the fission spectrum at perhaps 10 MeV. For cosmic ray dosimetry the energy range extends into the GeV region. This enormous range sets a challenge for designing measuring devices and a parallel challenge of developing measurement standards for characterizing these devices. One of the major considerations when deciding on topics for this special issue was agreeing on what not to include. Modelling, i.e. the use of radiation transport codes, is now a very important aspect of neutron measurements. These calculations are vital for shielding and for instrument design; nevertheless, the topic has only been included here where it has a direct bearing on metrology and the development of standards. Neutron spectrometry is an increasingly important technique for unravelling some of the problems of dose equivalent measurements and for plasma diagnostics in fusion research. However, this topic is at least one step removed from primary metrology and so it was felt that it should not be

  17. FOREWORD: Neutron metrology Neutron metrology

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    industry, from the initial fuel enrichment and fabrication processes right through to storage or reprocessing, and neutron metrology is clearly important in this area. Neutron fields do, however, occur in other areas, for example where neutron sources are used in oil well logging and moisture measurements. They also occur around high energy accelerators, including photon linear accelerators used for cancer therapy, and are expected to be a more serious problem around the new hadron radiation therapy facilities. Roughly 50% of the cosmic ray doses experienced by fliers at the flight altitudes of commercial aircraft are due to neutrons. Current research on fusion presents neutron metrology with a whole new range of challenges because of the very high fluences expected. One of the most significant features of neutron fields is the very wide range of possible neutron energies. In the nuclear industry, for example, neutrons occur with energies from those of thermal neutrons at a few meV to the upper end of the fission spectrum at perhaps 10 MeV. For cosmic ray dosimetry the energy range extends into the GeV region. This enormous range sets a challenge for designing measuring devices and a parallel challenge of developing measurement standards for characterizing these devices. One of the major considerations when deciding on topics for this special issue was agreeing on what not to include. Modelling, i.e. the use of radiation transport codes, is now a very important aspect of neutron measurements. These calculations are vital for shielding and for instrument design; nevertheless, the topic has only been included here where it has a direct bearing on metrology and the development of standards. Neutron spectrometry is an increasingly important technique for unravelling some of the problems of dose equivalent measurements and for plasma diagnostics in fusion research. However, this topic is at least one step removed from primary metrology and so it was felt that it should not be

  18. Saltcrete formulation

    SciTech Connect

    Semones, G.B.; Connell, J.M.; Jorgensen, S.C.

    1994-09-28

    The information gathered since the first report shows that the currently generated waste and most of the waste in inventory has low concentrations of hazardous chemicals and is certifiable for disposable. This is based on preliminary analyses. Sampling and analysis for the purpose of gathering the legally defensible data required for certification and permanent disposal is in progress. The main technical issue is the expansion of the waste form. Some of the cemented waste expands and damages the containers. According to a petrology study, the expansion is caused by the formation of darapskite, a nitrate-sulfate salt. Darapskite occurs when there is high porosity causing microfractures and waste form expansion.

  19. Contributions of the electronic spin and orbital current to the CoCl{sub 4}{sup 2-} magnetic field probed in polarised neutron diffraction experiments

    SciTech Connect

    Cassam-Chenaie, Patrick; Jayatilaka, Dylan

    2012-08-14

    Polarised neutron diffraction experiments conducted at 4.2 K on Cs{sub 3}CoCl{sub 5} crystals have been analysed by using a four-dimensional model Hilbert space made of ab initio n-electron wave functions of the CoCl{sub 4}{sup 2-} molecular ion. Two spin-orbit mixing coefficients and several configuration interaction coefficients have been optimized by fitting calculated magnetic structure factors to experimental ones, to obtain the best ensemble density operator that is representable in the model space. A goodness of fit, {chi}{sup 2}, less then 1 has been obtained for the first time for the two experimental data sets available. In the present article, the optimized density operators are used to calculate the magnetic field densities that are the genuine observables probed in neutron diffraction experiments. Density maps of such observables are presented for the first time and numerical details are provided. The respective contributions of spin density and orbital current to the magnetic field density are analyzed.

  20. Outline of a proposal for a new neutron source: The pulsed neutron research facility

    SciTech Connect

    Brown, B.S.; Carpenter, J.M.; Kustom, R.L.

    1992-04-01

    Accelerator-based, pulsed spallation neutron sources have been performing neutron scattering research for about fifteen years. During this time beam intensities have increased by a factor of 100 and more than 50 spectrometers are now operating on four major sources worldwide. The pulsed sources have proven to be highly effective and complementary to reactor-based sources in that there are important scientific areas for which each type of source has unique capabilities. We describe a proposal for a new pulsed neutron facility based on a Fixed Field Alternating Gradient synchrotron. The specifications for this new machine, which are now only being formulated, are for an accelerator that will produce (100 {divided_by} 200) {mu}A of time-averaged proton current at (500 {divided_by} 1000) MeV, in short pulses at 30 Hz. Appropriate target and moderator systems and an array of scattering instruments will be provided to make the facility a full-blown research installation. The neutron source, named the Pulsed Neutron Research Facility (PNRF), will be as powerful as any pulsed source now operating in the world and will also act as a test bed for the Fixed Field Alternating Gradient Synchrotron concept as a basis for more powerful sources in the future. The peak thermal neutron flux in PNRF will be about 5{center_dot}10{sup 15}n/cm{sup 2}{center_dot}s.

  1. Outline of a proposal for a new neutron source: The pulsed neutron research facility

    SciTech Connect

    Brown, B.S.; Carpenter, J.M.; Kustom, R.L.

    1992-04-01

    Accelerator-based, pulsed spallation neutron sources have been performing neutron scattering research for about fifteen years. During this time beam intensities have increased by a factor of 100 and more than 50 spectrometers are now operating on four major sources worldwide. The pulsed sources have proven to be highly effective and complementary to reactor-based sources in that there are important scientific areas for which each type of source has unique capabilities. We describe a proposal for a new pulsed neutron facility based on a Fixed Field Alternating Gradient synchrotron. The specifications for this new machine, which are now only being formulated, are for an accelerator that will produce (100 {divided by} 200) {mu}A of time-averaged proton current at (500 {divided by} 1000) MeV, in short pulses at 30 Hz. Appropriate target and moderator systems and an array of scattering instruments will be provided to make the facility a full-blown research installation. The neutron source, named the Pulsed Neutron Research Facility (PNRF), will be as powerful as any pulsed source now operating in the world and will also act as a test bed for the Fixed Field Alternating Gradient Synchrotron concept as a basis for more powerful sources in the future. The peak thermal neutron flux in PNRF will be about 5{center dot}10{sup 15}n/cm{sup 2}{center dot}s.

  2. Liposomal formulations for inhalation.

    PubMed

    Cipolla, David; Gonda, Igor; Chan, Hak-Kim

    2013-08-01

    No marketed inhaled products currently use sustained release formulations such as liposomes to enhance drug disposition in the lung, but that may soon change. This review focuses on the interaction between liposomal formulations and the inhalation technology used to deliver them as aerosols. There have been a number of dated reviews evaluating nebulization of liposomes. While the information they shared is still accurate, this paper incorporates data from more recent publications to review the factors that affect aerosol performance. Recent reviews have comprehensively covered the development of dry powder liposomes for aerosolization and only the key aspects of those technologies will be summarized. There are now at least two inhaled liposomal products in late-stage clinical development: ARIKACE(®) (Insmed, NJ, USA), a liposomal amikacin, and Pulmaquin™ (Aradigm Corp., CA, USA), a liposomal ciprofloxacin, both of which treat a variety of patient populations with lung infections. This review also highlights the safety of inhaled liposomes and summarizes the clinical experience with liposomal formulations for pulmonary application. PMID:23919478

  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 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)

  6. Naval fuel saltstone formulation change

    SciTech Connect

    Harley, J.P. Jr.; Langton, C.A.

    1987-10-19

    Laboratory results support a formulation change for Naval Fuels saltstone from a cement-only waste form to a cement and Class F fly ash waste form. The recommended base formulation is waste, concentrated to a SpG of 1.35, mixed with a 1:1 ratio of Type 1 Portland cement and class F fly ash to achieve a water to cementitious materials (includes fly ash) ratio of 0.4. Due to variations in waste water chemistry, permit modifications should specify formulation ranges such that saltstone physical and chemical properties are enhanced. Operations should be based on pretesting each waste batch and adjusting the base formulation within specified ranges (ie. Draft DPSOL 247 WW-0312, ``Saltcrete Formulation Testing for Rapid Set and Excess Water.``) EP toxicity and TCLP tests are included and show comparable results for both cement-only and cement/fly ash waste forms. Heat generation due to hydration, a current problem with the cementonly formulation, is significantly reduced in the cement/fly ash mixture. In addition to the improved physical characteristics of the cement/fly ash formulation, savings of approximately 33% in raw materials cost may be obtained due to the substitution of the lower cost fly ash for cement in the Naval Fuels waste solidification process.

  7. Naval fuel saltstone formulation change

    SciTech Connect

    Harley, J.P. Jr. and Co., Aiken, SC . Savannah River Plant); Langton, C.A. )

    1987-10-19

    Laboratory results support a formulation change for Naval Fuels saltstone from a cement-only waste form to a cement and Class F fly ash waste form. The recommended base formulation is waste, concentrated to a SpG of 1.35, mixed with a 1:1 ratio of Type 1 Portland cement and class F fly ash to achieve a water to cementitious materials (includes fly ash) ratio of 0.4. Due to variations in waste water chemistry, permit modifications should specify formulation ranges such that saltstone physical and chemical properties are enhanced. Operations should be based on pretesting each waste batch and adjusting the base formulation within specified ranges (ie. Draft DPSOL 247 WW-0312, Saltcrete Formulation Testing for Rapid Set and Excess Water.'') EP toxicity and TCLP tests are included and show comparable results for both cement-only and cement/fly ash waste forms. Heat generation due to hydration, a current problem with the cementonly formulation, is significantly reduced in the cement/fly ash mixture. In addition to the improved physical characteristics of the cement/fly ash formulation, savings of approximately 33% in raw materials cost may be obtained due to the substitution of the lower cost fly ash for cement in the Naval Fuels waste solidification process.

  8. Current-carrying element based on second-generation high-temperature superconductor for the magnet system of a fusion neutron source

    NASA Astrophysics Data System (ADS)

    Novikov, M. S.; Ivanov, D. P.; Novikov, S. I.; Shuvaev, S. A.

    2015-12-01

    Application of current-carrying elements (CCEs) made of second-generation high-temperature superconductor (2G HTS) in magnet systems of a fusion neutron source (FNS) and other fusion devices will allow their magnetic field and thermodynamic stability to be increased substantially in comparison with those of low-temperature superconductor (LTS) magnets. For a toroidal magnet of the FNS, a design of a helical (partially transposed) CCE made of 2G HTS is under development with forced-flow cooling by helium gas, a current of 20-30 kA, an operating temperature of 10-20 K, and a magnetic field on the winding of 12-15 T (prospectively ~20 T). Short-sized samples of the helical flexible heavy-current CCE are being fabricated and investigated; a pilot-line unit for production of long-sized CCE pieces is under construction. The applied fabrication technique allows the CCE to be produced which combines a high operating current, thermal and mechanical stability, manufacturability, and low losses in the alternating modes. The possibility of fabricating the CCE with the outer dimensions and values of the operating parameter required for the FNS (and with a significant margin) using already available serial 2G HTS tapes is substantiated. The maximum field of toroidal magnets with CCEs made of 2G HTS will be limited only by mechanical properties of the magnet's casing and structure, while the thermal stability will be approximately two orders of magnitude higher than that of toroidal magnets with LTS-based CCEs. The helical CCE made of 2G HTS is very promising for fusion and hybrid electric power plants, and its design and technologies of production, as well as the prototype coils made of it for the FNS and other tokamaks, are worth developing now.

  9. Current-carrying element based on second-generation high-temperature superconductor for the magnet system of a fusion neutron source

    SciTech Connect

    Novikov, M. S. Ivanov, D. P. E-mail: denis.ivanov30@mail.ru; Novikov, S. I. Shuvaev, S. A. E-mail: sergey.shuvaev@phystech.edu

    2015-12-15

    Application of current-carrying elements (CCEs) made of second-generation high-temperature superconductor (2G HTS) in magnet systems of a fusion neutron source (FNS) and other fusion devices will allow their magnetic field and thermodynamic stability to be increased substantially in comparison with those of low-temperature superconductor (LTS) magnets. For a toroidal magnet of the FNS, a design of a helical (partially transposed) CCE made of 2G HTS is under development with forced-flow cooling by helium gas, a current of 20–30 kA, an operating temperature of 10–20 K, and a magnetic field on the winding of 12–15 T (prospectively ∼20 T). Short-sized samples of the helical flexible heavy-current CCE are being fabricated and investigated; a pilot-line unit for production of long-sized CCE pieces is under construction. The applied fabrication technique allows the CCE to be produced which combines a high operating current, thermal and mechanical stability, manufacturability, and low losses in the alternating modes. The possibility of fabricating the CCE with the outer dimensions and values of the operating parameter required for the FNS (and with a significant margin) using already available serial 2G HTS tapes is substantiated. The maximum field of toroidal magnets with CCEs made of 2G HTS will be limited only by mechanical properties of the magnet’s casing and structure, while the thermal stability will be approximately two orders of magnitude higher than that of toroidal magnets with LTS-based CCEs. The helical CCE made of 2G HTS is very promising for fusion and hybrid electric power plants, and its design and technologies of production, as well as the prototype coils made of it for the FNS and other tokamaks, are worth developing now.

  10. The COHERENT collaboration: an effort to observe coherent, elastic, neutral-current neutrino-nucleus scattering at the Spallation Neutron Source

    NASA Astrophysics Data System (ADS)

    Rich, Grayson; Coherent Collaboration

    2014-09-01

    The phenomenon of coherent, neutral-current scattering of neutrinos from nuclei was first proposed by D.Z. Freedman in 1974, who posited that an effort to observe this effect experimentally ``may be an act of hubris'' owing to extreme experimental difficulties. Taking advantage of technologies which have come to maturity and new experience gained in the intervening 40 years, the newly-formed COHERENT collaboration seeks to measure for the first time coherent, elastic neutrino-nucleus scattering (CE ν NS). Using neutrinos created by stopped pions at the Spallation Neutron Source (SNS) of Oak Ridge National Laboratory, several detector systems will be deployed to limit systematic uncertainties and unambiguously observe the N2 -dependence on the cross section. The current status of the efforts of the collaboration will be addressed, focusing on detector technologies and calibration of these detectors for low-energy nuclear recoils. We will also discuss the longer-term physics goals of the collaboration, including astrophysical implications of the measurements and the use CE ν NS as a probe to search for non-standard neutrino interactions and as a way to measure the weak mixing angle.

  11. Neutron detection technique

    SciTech Connect

    Oblath, N.S.; Poon, A.W.P.

    2000-09-14

    The Sudbury Neutrino Observatory (SNO) has the ability to measure the total flux of all active flavors of neutrinos using the neutral current reaction, whose signature is a neutron. By comparing the rates of the neutral current reaction to the charged current reaction, which only detects electron neutrinos, one can test the neutrino oscillation hypothesis independent of solar models. It is necessary to understand the neutron detection efficiency of the detector to make use of the neutral current reaction. This report demonstrates a coincidence technique to identify neutrons emitted from the {sup 252}Cf neutron calibration source. The source releases on average four neutrons when a {sup 252}Cf nucleus spontaneously fissions. Each neutron is detected as a separate event when the neutron is captured by a deuteron, releasing a gamma ray of approximately 6.25 MeV. This gamma ray is in turn detected by the photomultiplier tube (PMT) array. By investigating the time and spatial separation between neutron-like events, it is possible to obtain a pure sample of neutrons for calibration study. Preliminary results of the technique applied to two calibration runs are presented.

  12. 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.

  13. Neutron star models

    NASA Technical Reports Server (NTRS)

    Canuto, V.; Bowers, R. L.

    1981-01-01

    The current state of neutron star structure calculations is reviewed. Uncertainties in the equation of state for matter at and above nuclear density remain. The role of the delta resonance, pion condensates, and quark matter is reviewed. It is found that recent models yield stable neutron star masses which are consistent with observational estimates.

  14. Determination of the Neutron Lifetime Using Magnetically Trapped Neutrons

    PubMed Central

    Dzhosyuk, S. N.; Copete, A.; Doyle, J. M.; Yang, L.; Coakley, K. J.; Golub, R.; Korobkina, E.; Kreft, T.; Lamoreaux, S. K.; Thompson, A. K.; Yang, G. L.; Huffman, P. R.

    2005-01-01

    We report progress on an experiment to measure the neutron lifetime using magnetically trapped neutrons. Neutrons are loaded into a 1.1 T deep superconducting Ioffe-type trap by scattering 0.89 nm neutrons in isotopically pure superfluid 4He. Neutron decays are detected in real time using the scintillation light produced in the helium by the beta-decay electrons. The measured trap lifetime at a helium temperature of 300 mK and with no ameliorative magnetic ramping is substantially shorter than the free neutron lifetime. This is attributed to the presence of neutrons with energies higher than the magnetic potential of the trap. Magnetic field ramping is implemented to eliminate these neutrons, resulting in an 833−63+74s trap lifetime, consistent with the currently accepted value of the free neutron lifetime. PMID:27308147

  15. Neutronic reactor

    DOEpatents

    Wende, Charles W. J.; Babcock, Dale F.; Menegus, Robert L.

    1983-01-01

    A nuclear reactor includes an active portion with fissionable fuel and neutron moderating material surrounded by neutron reflecting material. A control element in the active portion includes a group of movable rods constructed of neutron-absorbing material. Each rod is movable with respect to the other rods to vary the absorption of neutrons and effect control over neutron flux.

  16. Feed Formulation and Manufacture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This chapter provides information on feed formulation and manufacture. To formulate and manufacture high quality fish feeds, including tilapia feeds, one should have knowledge of nutrient requirements, nutrient composition, digestibility, and availability of feed ingredients; impacts of manufacturin...

  17. Highly concentrated foam formulation for blast mitigation

    DOEpatents

    Tucker, Mark D.; Gao, Huizhen

    2010-12-14

    A highly concentrated foam formulation for blast suppression and dispersion mitigation for use in responding to a terrorism incident involving a radiological dispersion device. The foam formulation is more concentrated and more stable than the current blast suppression foam (AFC-380), which reduces the logistics burden on the user.

  18. Neutron densities from muon capture

    NASA Astrophysics Data System (ADS)

    Huan Ching, Chiang; Oset, Eulogio

    1991-10-01

    We show that, because of Pauli blocking and renormalization of the weak currents in nuclei, the muon capture rates are rather sensitive to the neutron distributions. We also show that, because of intrinsic theoretical uncertainties, neutron radia cannot be determined with precision but some reasonable limits can be given. However, the ratio of capture rates in different isotopes serves to determine the neutron radii of the isotopes provided the neutron density distribution for one of them is known.

  19. Boron nitride solid state neutron detector

    DOEpatents

    Doty, F. Patrick

    2004-04-27

    The present invention describes an apparatus useful for detecting neutrons, and particularly for detecting thermal neutrons, while remaining insensitive to gamma radiation. Neutrons are detected by direct measurement of current pulses produced by an interaction of the neutrons with hexagonal pyrolytic boron nitride.

  20. The Fundamental Neutron Physics Beamline at the Spallation Neutron Source

    PubMed Central

    Greene, Geoffrey; Cianciolo, Vince; Koehler, Paul; Allen, Richard; Snow, William Michael; Huffman, Paul; Gould, Chris; Bowman, David; Cooper, Martin; Doyle, John

    2005-01-01

    The Spallation Neutron Source (SNS), currently under construction at Oak Ridge National Laboratory with an anticipated start-up in early 2006, will provide the most intense pulsed beams of cold neutrons in the world. At a projected power of 1.4 MW, the time averaged fluxes and fluences of the SNS will approach those of high flux reactors. One of the flight paths on the cold, coupled moderator will be devoted to fundamental neutron physics. The fundamental neutron physics beamline is anticipated to include two beam-lines; a broad band cold beam, and a monochromatic beam of 0.89 nm neutrons for ultracold neutron (UCN) experiments. The fundamental neutron physics beamline will be operated as a user facility with experiment selection based on a peer reviewed proposal process. An initial program of five experiments in neutron decay, hadronic weak interaction and time reversal symmetry violation have been proposed. PMID:27308112

  1. Current and potential role of specially formulated foods and food supplements for preventing malnutrition among 6- to 23-month-old children and for treating moderate malnutrition among 6- to 59-month-old children.

    PubMed

    de Pee, Saskia; Bloem, Martin W

    2009-09-01

    Reducing child malnutrition requires nutritious food, breastfeeding, improved hygiene, health services, and (prenatal) care. Poverty and food insecurity seriously constrain the accessibility of nutritious diets that have high protein quality, adequate micronutrient content and bioavailability, macrominerals and essential fatty acids, low antinutrient content, and high nutrient density. Diets based largely on plant sources with few animal-source and fortified foods do not meet these requirements and need to be improved by processing (dehulling, germinating, fermenting), fortification, and adding animal-source foods, e.g., milk, or other specific nutrients. Options include using specially formulated foods (fortified blended foods, commercial infant cereals, or ready-to-use foods [RUFs; pastes, compressed bars, or biscuits]) or complementary food supplements (micronutrient powders or powdered complementary food supplements containing micronutrients, protein, amino acids, and/or enzymes or lipid-based nutrient supplements (120 to 250 kcal/day), typically containing milk powder, high-quality vegetable oil, peanut paste, sugar, and micronutrients. Most supplementary feeding programs for moderately malnourished children supply fortified blended foods, such as corn-soy blend, with oil and sugar, which have shortcomings, including too many antinutrients, no milk (important for growth), suboptimal micronutrient content, high bulk, and high viscosity. Thus, for feeding young or malnourished children, fortified blended foods need to be improved or replaced. Based on success with ready-to-use therapeutic foods (RUTFs) for treating severe acute malnutrition, modifying these recipes is also considered. Commodities for reducing child malnutrition should be chosen on the basis of nutritional needs, program circumstances, availability of commodities, and likelihood of impact. Data are urgently required to compare the impact of new or modified commodities with that of current

  2. Formulation of Nematodes.

    PubMed

    Peters, Arne

    2016-01-01

    The enduring stages of entomopathogenic nematodes of the genera Steinernema and Heterorhabditis are infective juveniles, which require a high humidity and sufficient ventilation for survival. Formulations must account for these requirements. Nematodes may be formulated inside the insects in which they reproduced or they need to be cleaned and mixed with a suitable binder to maintain humidity but allowing for gas exchange. Another method for formulation is the encapsulation in beads of Ca-alginate. Generic procedures for these formulation techniques are described. PMID:27565496

  3. Psychiatrists' use of formulation

    PubMed Central

    Hughes, Patricia M.

    2016-01-01

    Both psychologists and psychiatrists are trained to write formulations of their patients' illnesses, with some differences in how they do this. Psychologists focus on psychological understanding, while psychiatrists' formulation brings together aetiology, functioning and a management plan. Mohtashemi et al's study records how some psychiatrists understand formulation and its usefulness. Time pressure was an important barrier to making a full formulation, and some believed the medical role of the psychiatrist was a priority. The study illustrates some of the challenges facing psychiatrists working in the NHS in terms of maintaining high clinical standards and a holistic approach to patient care. PMID:27512593

  4. Coated Fiber Neutron Detector Test

    SciTech Connect

    Lintereur, Azaree T.; Ely, James H.; Kouzes, Richard T.; Stromswold, David C.

    2009-10-23

    Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive neutron detection systems. The main reason for having neutron detection capability is to detect fission neutrons from plutonium. The currently deployed radiation portal monitors (RPMs) from Ludlum and Science Applications International Corporation (SAIC) use neutron detectors based upon 3He-filled gas proportional counters, which are the most common large neutron detector. There is a declining supply of 3He in the world, and thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and sensitivity to cargo-borne neutrons are being investigated. Reported here are the results of tests of the 6Li/ZnS(Ag)-coated non-scintillating plastic fibers option. This testing measured the required performance for neutron detection efficiency and gamma ray rejection capabilities of a system manufactured by Innovative American Technology (IAT).

  5. Crystallization of dense neutron matter

    NASA Technical Reports Server (NTRS)

    Canuto, V.; Chitre, S. M.

    1974-01-01

    The equation of state for cold neutron matter at high density is studied in the t-matrix formulation, and it is shown that energetically it is convenient to have neutrons in a crystalline configuration rather than in a liquid state for values of the density exceeding 1600 Tg/cu cm. The study of the mechanical properties indicates that the system is stable against shearing stresses. A solid core in the deep interior of heavy neutron stars appears to offer the most plausible explanation of speed-ups observed in the Vela pulsar.

  6. 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.

  7. Neutron stars - General review

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

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

  8. Out-of-field neutron and leakage photon exposures and the associated risk of second cancers in high-energy photon radiotherapy: current status.

    PubMed

    Takam, R; Bezak, E; Marcu, L G; Yeoh, E

    2011-10-01

    Determination and understanding of out-of-field neutron and photon doses in accelerator-based radiotherapy is an important issue since linear accelerators operating at high energies (>10 MV) produce secondary radiations that irradiate parts of the patient's anatomy distal to the target region, potentially resulting in detrimental health effects. This paper provides a compilation of data (technical and clinical) reported in the literature on the measurement and Monte Carlo simulations of peripheral neutron and photon doses produced from high-energy medical linear accelerators and the reported risk and/or incidence of second primary cancer of tissues distal to the target volume. Information in the tables facilitates easier identification of (1) the various methods and measurement techniques used to determine the out-of-field neutron and photon radiations, (2) reported linac-dependent out-of-field doses, and (3) the risk/incidence of second cancers after radiotherapy due to classic and modern treatment methods. Regardless of the measurement technique and type of accelerator, the neutron dose equivalent per unit photon dose ranges from as low as 0.1 mSv/Gy to as high as 20.4 mSv/Gy. This radiation dose potentially contributes to the induction of second primary cancer in normal tissues outside the treated area. PMID:21756083

  9. Accelerator based epithermal neutron source

    NASA Astrophysics Data System (ADS)

    Taskaev, S. Yu.

    2015-11-01

    We review the current status of the development of accelerator sources of epithermal neutrons for boron neutron capture therapy (BNCT), a promising method of malignant tumor treatment. Particular attention is given to the source of epithermal neutrons on the basis of a new type of charged particle accelerator: tandem accelerator with vacuum insulation and lithium neutron-producing target. It is also shown that the accelerator with specialized targets makes it possible to generate fast and monoenergetic neutrons, resonance and monoenergetic gamma-rays, alpha-particles, and positrons.

  10. Audits of radiopharmaceutical formulations.

    PubMed

    Castronovo, F P

    1992-03-01

    A procedure for auditing radiopharmaceutical formulations is described. To meet FDA guidelines regarding the quality of radiopharmaceuticals, institutional radioactive drug research committees perform audits when such drugs are formulated away from an institutional pharmacy. All principal investigators who formulate drugs outside institutional pharmacies must pass these audits before they can obtain a radiopharmaceutical investigation permit. The audit team meets with the individual who performs the formulation at the site of drug preparation to verify that drug formulations meet identity, strength, quality, and purity standards; are uniform and reproducible; and are sterile and pyrogen free. This team must contain an expert knowledgeable in the preparation of radioactive drugs; a radiopharmacist is the most qualified person for this role. Problems that have been identified by audits include lack of sterility and apyrogenicity testing, formulations that are open to the laboratory environment, failure to use pharmaceutical-grade chemicals, inadequate quality control methods or records, inadequate training of the person preparing the drug, and improper unit dose preparation. Investigational radiopharmaceutical formulations, including nonradiolabeled drugs, must be audited before they are administered to humans. A properly trained pharmacist should be a member of the audit team. PMID:1598931

  11. 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.

  12. 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.

  13. Reactive decontamination formulation

    DOEpatents

    Giletto, Anthony; White, William; Cisar, Alan J.; Hitchens, G. Duncan; Fyffe, James

    2003-05-27

    The present invention provides a universal decontamination formulation and method for detoxifying chemical warfare agents (CWA's) and biological warfare agents (BWA's) without producing any toxic by-products, as well as, decontaminating surfaces that have come into contact with these agents. The formulation includes a sorbent material or gel, a peroxide source, a peroxide activator, and a compound containing a mixture of KHSO.sub.5, KHSO.sub.4 and K.sub.2 SO.sub.4. The formulation is self-decontaminating and once dried can easily be wiped from the surface being decontaminated. A method for decontaminating a surface exposed to chemical or biological agents is also disclosed.

  14. Therapy of infections in mice irradiated in mixed neutron/photon fields and inflicted with wound trauma: A review of current work. (Reannouncement with new availability information)

    SciTech Connect

    Ledney, G.D.; Madonna, G.S.; Elliott, T.B.; Moore, M.M.; Jackson, W.E.

    1991-12-31

    When host antimicrobial defenses are severely compromised by radiation or trauma in conjunction with radiation, death from sepsis results. To evaluate therapies for sepsis in radiation casualties, the authors developed models of acquired and induced bacterial infections in irradiated and irradiated-wounded mice. Animals were exposed to either a mixed radiation field of equal proportions of neutrons and gamma rays (n/gamma = 1) from a TRIGA reactor or pure gamma rays from 60 (Co sources). Skin wounds (15% of total body surface area) were inflicted under methoxyflurane anesthesia 1 h after irradiation. In all mice, wounding after irradiation decreased resistance to infection. Treatments with the immunomodulator synthetic trehalose dicorynomycolate (S-TDCM) before or after mixed neutron-gamma irradiation or gamma irradiation increased survival. Therapy with S-TDCM for mice irradiated with either a mixed field or gamma rays increased resistance to Klebsiella pneumoniae-induced infections.

  15. Producing persistent, high-current, high-duty-factor H{sup -} beams for routine 1 MW operation of Spallation Neutron Source (invited)

    SciTech Connect

    Stockli, Martin P.; Han, B. X.; Hardek, T. W.; Kang, Y. W.; Murray, S. N.; Pennisi, T. R.; Piller, C.; Santana, M.; Welton, R.

    2012-02-15

    Since 2009, the Spallation Neutron Source (SNS) has been producing neutrons with ion beam powers near 1 MW, which requires the extraction of {approx}50 mA H{sup -} ions from the ion source with a {approx}5% duty factor. The 50 mA are achieved after an initial dose of {approx}3 mg of Cs and heating the Cs collar to {approx}170 deg. C. The 50 mA normally persist for the entire 4-week source service cycles. Fundamental processes are reviewed to elucidate the persistence of the SNS H{sup -} beams without a steady feed of Cs and why the Cs collar temperature may have to be kept near 170 deg. C.

  16. Using instrumental neutron activation analysis for geochemical analyses of terrestrial impact structures: current analytical procedures at the university of vienna geochemistry activation analysis laboratory.

    PubMed

    Mader, Dieter; Koeberl, Christian

    2009-12-01

    The Instrumental Neutron Activation Analysis Gamma Spectroscopy Laboratory at the Department of Lithospheric Research, University of Vienna, has been upgraded in the year 2006. This paper describes the sample preparation, new instrumentation and data evaluation for hundreds of rock samples of two terrestrial impact structures. The measurement and data evaluation are done by using Genie 2000 and a custom-made batch software for the used analysis sequences. PMID:19481467

  17. 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.

  18. 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.

  19. 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.

  20. First neutron generation in the BINP accelerator based neutron source.

    PubMed

    Bayanov, B; Burdakov, A; Chudaev, V; Ivanov, A; Konstantinov, S; Kuznetsov, A; Makarov, A; Malyshkin, G; Mekler, K; Sorokin, I; Sulyaev, Yu; Taskaev, S

    2009-07-01

    Pilot innovative facility for neutron capture therapy was built at Budker Institute of Nuclear Physics, Novosibirsk. This facility is based on a compact vacuum insulation tandem accelerator designed to produce proton current up to 10 mA. Epithermal neutrons are proposed to be generated by 1.915 MeV protons bombarding a lithium target using (7)Li(p,n)(7)Be threshold reaction. The results of the first experiments on neutron generation are reported and discussed. PMID:19375928

  1. Neutron Laue macromolecular crystallography

    SciTech Connect

    Meilleur, Flora; Myles, Dean A A; Blakeley, M. P.

    2006-01-01

    Recent progress in neutron protein crystallography such as the use of the Laue technique and improved neutron optics and detector technologies have dramatically improved the speed and precision with which neutron protein structures can now be determined. These studies are providing unique and complementary insights on hydrogen and hydration in protein crystal structures that are not available from X-ray structures alone. Parallel improvements in modern molecular biology now allow fully (per)deuterated protein samples to be produced for neutron scattering that essentially eradicate the large--and ultimately limiting--hydrogen incoherent scattering background that has hampered such studies in the past. High quality neutron data can now be collected to near atomic resolution ({approx}2.0 Angstroms) for proteins of up to {approx}50 kDa molecular weight using crystals of volume {approx}0.1 mm3 on the Laue diffractometer at ILL. The ability to flash-cool and collect high resolution neutron data from protein crystals at cryogenic temperature (15 K) has opened the way for kinetic crystallography on freeze trapped systems. Current instrument developments now promise to reduce crystal volume requirements by a further order of magnitude, making neutron protein crystallography a more accessible and routine technique.

  2. Saltstone Clean Cap Formulation

    SciTech Connect

    Langton, C

    2005-04-22

    The current operation strategy for using Saltstone Vault 4 to receive 0.2 Ci/gallon salt solution waste involves pouring a clean grout layer over the radioactive grout prior to initiating pour into another cell. This will minimize the radiating surface area and reduce the dose rate at the vault and surrounding area. The Clean Cap will be used to shield about four feet of Saltstone poured into a Z-Area vault cell prior to moving to another cell. The minimum thickness of the Clean Cap layer will be determined by the cesium concentration and resulting dose levels and it is expected to be about one foot thick based on current calculations for 0.1 Ci Saltstone that is produced in the Saltstone process by stabilization of 0.2 Ci salt solution. This report documents experiments performed to identify a formulation for the Clean Cap. Thermal transient calculations, adiabatic temperature rise measurements, pour height, time between pour calculations and shielding calculations were beyond the scope and time limitations of this study. However, data required for shielding calculations (composition and specific gravity) are provided for shielding calculations. The approach used to design a Clean Cap formulation was to produce a slurry from the reference premix (10/45/45 weight percent cement/slag/fly ash) and domestic water that resembled as closely as possible the properties of the Saltstone slurry. In addition, options were investigated that may offer advantages such as less bleed water and less heat generation. The options with less bleed water required addition of dispersants. The options with lower heat contained more fly ash and less slag. A mix containing 10/45/45 weight percent cement/slag/fly ash with a water to premix ratio of 0.60 is recommended for the Clean Cap. Although this mix may generate more than 3 volume percent standing water (bleed water), it has rheological, mixing and flow properties that are similar to previously processed Saltstone. The recommended

  3. 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.

  4. 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.

  5. Excision technique in constrained formulations of Einstein equations: collapse scenario

    NASA Astrophysics Data System (ADS)

    Cordero-Carrión, I.; Vasset, N.; Novak, J.; Jaramillo, J. L.

    2015-04-01

    We present a new excision technique used in constrained formulations of Einstein equations to deal with black hole in numerical simulations. We show the applicability of this scheme in several scenarios. In particular, we present the dynamical evolution of the collapse of a neutron star to a black hole, using the CoCoNuT code and this excision technique.

  6. Neutron phase spin echo

    NASA Astrophysics Data System (ADS)

    Piegsa, Florian M.; Hautle, Patrick; Schanzer, Christian

    2016-04-01

    A novel neutron spin resonance technique is presented based on the well-known neutron spin echo method. In a first proof-of-principle measurement using a monochromatic neutron beam, it is demonstrated that relative velocity changes of down to a precision of 4 ×10-7 can be resolved, corresponding to an energy resolution of better than 3 neV. Currently, the sensitivity is only limited by counting statistics and not by systematic effects. An improvement by another two orders of magnitude can be achieved with a dedicated setup, allowing energy resolutions in the 10 peV regime. The new technique is ideally suited for investigations in the field of precision fundamental neutron physics, but will also be beneficial in scattering applications.

  7. Low dose neutron late effects: Cataractogenesis

    SciTech Connect

    Worgul, B.V.

    1991-12-01

    The work is formulated to resolve the uncertainty regarding the relative biological effectiveness (RBE) of low dose neutron radiation. The study exploits the fact that cataractogenesis is sensitive to the inverse dose-rate effect as has been observed with heavy ions and was an endpoint considered in the follow-up of the A-bomb survivors. The neutron radiations were initiated at the Radiological Research Accelerator facility (RARAF) of the Nevis Laboratory of Columbia University. Four week old ({plus minus} 1 day) rats were divided into eight dose groups each receiving single or fractionated total doses of 0.2, 1.0, 5.0 and 25.0 cGy of monoenergetic 435 KeV neutrons. Special restraining jigs insured that the eye, at the midpoint of the lens, received the appropriate energy and dose with a relative error of {plus minus}5%. The fractionation regimen consisted of four exposures, each administered at three hour ({plus minus}) intervals. The neutron irradiated groups are being compared to rats irradiated with 250kVp X-rays in doses ranging from 0.5 to 7 Gy. The animals are being examined on a biweekly basis utilizing conventional slit-lamp biomicroscopy and the Scheimpflug Slit Lamp Imaging System (Zeiss). The follows-ups, entering their second year, will continue throughout the life-span of the animals. This is essential inasmuch as given the extremely low doses which are being utilized clinically detectable opacities were not anticipated until a significant fraction of the life span has lapsed. Current data support this contention. At this juncture cataracts in the irradiated groups are beginning to exceed control levels.

  8. A National Spallation Neutron Source for neutron scattering

    SciTech Connect

    Appleton, B.R.

    1996-10-01

    The National Spallation Neutron Source is a collaborative project or perform the conceptual design for a next generation neutron source for the Department of Energy. This paper reviews the need and justification for a new neutron source, the origins and structure of the collaboration formed to address this need, and the community input leading up to the current design approach. A reference design is presented for an accelerator based spallation neutron source that would begin operation at about 1 megawatt of power but designed so that it could be upgraded to significantly higher powers in the future. The technology approach, status, and progress on the conceptual design to date are presented.

  9. Granulated decontamination formulations

    DOEpatents

    Tucker, Mark D.

    2007-10-02

    A decontamination formulation and method of making that neutralizes the adverse health effects of both chemical and biological compounds, especially chemical warfare (CW) and biological warfare (BW) agents, and toxic industrial chemicals. The formulation provides solubilizing compounds that serve to effectively render the chemical and biological compounds, particularly CW and BW compounds, susceptible to attack, and at least one reactive compound that serves to attack (and detoxify or kill) the compound. The formulation includes at least one solubilizing agent, a reactive compound, a sorbent additive, and water. A highly adsorbent sorbent additive (e.g., amorphous silica, sorbitol, mannitol, etc.) is used to "dry out" one or more liquid ingredients into a dry, free-flowing powder that has an extended shelf life, and is more convenient to handle and mix in the field.

  10. Advanced protein formulations

    PubMed Central

    Wang, Wei

    2015-01-01

    It is well recognized that protein product development is far more challenging than that for small-molecule drugs. The major challenges include inherent sensitivity to different types of stresses during the drug product manufacturing process, high rate of physical and chemical degradation during long-term storage, and enhanced aggregation and/or viscosity at high protein concentrations. In the past decade, many novel formulation concepts and technologies have been or are being developed to address these product development challenges for proteins. These concepts and technologies include use of uncommon/combination of formulation stabilizers, conjugation or fusion with potential stabilizers, site-specific mutagenesis, and preparation of nontraditional types of dosage forms—semiaqueous solutions, nonfreeze-dried solid formulations, suspensions, and other emerging concepts. No one technology appears to be mature, ideal, and/or adequate to address all the challenges. These gaps will likely remain in the foreseeable future and need significant efforts for ultimate resolution. PMID:25858529

  11. Neutron diffraction on pulsed sources

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    The current capabilities of and major scientific problems solved by time-of-flight neutron diffraction are reviewed. The reasons for the rapid development of the method over the last two decades have been mainly the emergence of third-generation pulsed sources with a megawatt time-averaged power and advances in neutron optical devices and detector systems. The paper discusses some historical aspects of time-of-flight neutron diffraction and examines the contribution to this method from F L Shapiro, the centennial of whose birth was celebrated in 2015. The state of the art with respect to neutron sources for studies on extracted beams is reviewed in a special section.

  12. 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.

  13. Alternative formulation of the monokinetic transport equation

    SciTech Connect

    Coppa, G.; Ravetto, P.; Sumini, M.

    1985-03-01

    After recalling a technique already exploited in stationary neutron transport, the dynamic linear monokinetic equation for general geometry is cast into an integro-differential form where a second order space Laplace operator and both a second and first time derivatives appear. The introduced unknowns are given a physical interpretation for plane geometry and their relations with the total flux and current are derived.

  14. Gravitational Waves from Neutron Stars

    NASA Astrophysics Data System (ADS)

    Kokkotas, Konstantinos

    2016-03-01

    Neutron stars are the densest objects in the present Universe, attaining physical conditions of matter that cannot be replicated on Earth. These unique and irreproducible laboratories allow us to study physics in some of its most extreme regimes. More importantly, however, neutron stars allow us to formulate a number of fundamental questions that explore, in an intricate manner, the boundaries of our understanding of physics and of the Universe. The multifaceted nature of neutron stars involves a delicate interplay among astrophysics, gravitational physics, and nuclear physics. The research in the physics and astrophysics of neutron stars is expected to flourish and thrive in the next decade. The imminent direct detection of gravitational waves will turn gravitational physics into an observational science, and will provide us with a unique opportunity to make major breakthroughs in gravitational physics, in particle and high-energy astrophysics. These waves, which represent a basic prediction of Einstein's theory of general relativity but have yet to be detected directly, are produced in copious amounts, for instance, by tight binary neutron star and black hole systems, supernovae explosions, non-axisymmetric or unstable spinning neutron stars. The focus of the talk will be on the neutron star instabilities induced by rotation and the magnetic field. The conditions for the onset of these instabilities and their efficiency in gravitational waves will be presented. Finally, the dependence of the results and their impact on astrophysics and especially nuclear physics will be discussed.

  15. Theory of cooling neutron stars versus observations

    SciTech Connect

    Yakovlev, D. G.; Gnedin, O. Y.; Kaminker, A. D.; Potekhin, A. Y.

    2008-02-27

    We review current state of neutron star cooling theory and discuss the prospects to constrain the equation of state, neutrino emission and superfluid properties of neutron star cores by comparing the cooling theory with observations of thermal radiation from isolated neutron stars.

  16. Rational formulation design.

    PubMed

    Lane, M E; Hadgraft, J; Oliveira, G; Vieira, R; Mohammed, D; Hirata, K

    2012-12-01

    To be efficacious and to satisfy the requirements for claim substantiation, a cosmetic formulation must achieve effective targeting of an active in the skin. Although the basic principles governing the skin permeation and disposition of molecules have been known for many years, attention has been far less focused on the role of the vehicle, particularly at cosmetically relevant doses. In this article, we discuss the necessity to understand the fate of the formulation components as well as the active once applied onto skin. Recent data confirm that the residence time of the formulation constituents can have a profound impact on the fate of the active. Approaches to identify the ideal vehicle for skin delivery are considered critically, specifically the recent work on 'formulating for efficacy' (FFE) by the late Johann Wiechers. Essentially, FFE aims to match the active with the optimal vehicle for skin delivery based on matching polarity/solubility values of the trinity of skin, active and vehicle. The emerging importance of techniques that provide insight to how the vehicle distributes in and on skin is highlighted. PMID:22882873

  17. Payloads minimum EIRP formulations

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The effective isotropic radiated power (EIRP) of the payloads is formulated. The EIRP consists of three components; EIRP = P sub T + G sub T + L sub TX, where P sub T is the transmitter total RF output power, G sub T is the transmitting antenna gain, and L sub TX is all transmitter circuit losses.

  18. FORMULATIONS OF BIOPESTICIDES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Formulation development is one of many steps required for commercialization of biological pesticides and holds the promise to bridge the gap between production of the active agent and use by consumers. A biological pesticide begins with discovery of an agent capable of controlling a pest. Active a...

  19. Neutron Nucleic Acid Crystallography.

    PubMed

    Chatake, Toshiyuki

    2016-01-01

    The hydration shells surrounding nucleic acids and hydrogen-bonding networks involving water molecules and nucleic acids are essential interactions for the structural stability and function of nucleic acids. Water molecules in the hydration shells influence various conformations of DNA and RNA by specific hydrogen-bonding networks, which often contribute to the chemical reactivity and molecular recognition of nucleic acids. However, X-ray crystallography could not provide a complete description of structural information with respect to hydrogen bonds. Indeed, X-ray crystallography is a powerful tool for determining the locations of water molecules, i.e., the location of the oxygen atom of H2O; however, it is very difficult to determine the orientation of the water molecules, i.e., the orientation of the two hydrogen atoms of H2O, because X-ray scattering from the hydrogen atom is very small.Neutron crystallography is a specialized tool for determining the positions of hydrogen atoms. Neutrons are not diffracted by electrons, but are diffracted by atomic nuclei; accordingly, neutron scattering lengths of hydrogen and its isotopes are comparable to those of non-hydrogen atoms. Therefore, neutron crystallography can determine both of the locations and orientations of water molecules. This chapter describes the current status of neutron nucleic acid crystallographic research as well as the basic principles of neutron diffraction experiments performed on nucleic acid crystals: materials, crystallization, diffraction experiments, and structure determination. PMID:26227050

  20. Fast-neutron spectrometer developments

    NASA Technical Reports Server (NTRS)

    Moler, R. B.; Zagotta, W. E.; Baker, S. I.

    1973-01-01

    Li6 sandwich-type neutron spectrometer is equipped with proportional counter for particle identification. System uses current-sensitive preamplifiers to minimize pile-up of gamma-ray and particle pulses.

  1. Micromegas neutron beam monitor neutronics.

    PubMed

    Stephan, Andrew C; Miller, Laurence F

    2005-01-01

    The Micromegas is a type of ionising radiation detector that consists of a gas chamber sandwiched between two parallel plate electrodes, with the gas chamber divided by a Frisch grid into drift and amplification gaps. Investigators have applied it to a number of different applications, such as charged particle, X-ray and neutron detection. A Micromegas device has been tested as a neutron beam monitor at CERN and is expected to be used for that purpose at the Spallation Neutron Source (SNS) under construction in Oak Ridge, TN. For the Micromegas to function effectively as neutron beam monitor, it should cause minimal disruption to the neutron beam in question. Specifically, it should scatter as few neutrons as possible and avoid neutron absorption when it does not contribute to generating useful information concerning the neutron beam. Here, we present the results of Monte Carlo calculations of the effect of different types of wall materials and detector gases on neutron beams and suggest methods for minimising disruption to the beam. PMID:16381746

  2. Compact neutron generator development at LBNL

    SciTech Connect

    Reijonen, J.; English, G.; Firestone, R.; Giquel, F.; King, M.; Leung, K-N.; Sun, M.

    2003-12-31

    A wide variety of applications ranging from medical (BNCT, Boron Neutron Capture Therapy) and basic science (neutron imaging, material studies) to homeland security (explosive detection and nuclear material non-proliferation) are in need of compact, high flux neutron generators. The Plasma and Ion Source Technology Group in the Lawrence Berkeley National Laboratory is developing various neutron generators for these applications. These neutron generators employed either the D-D or the D-T fusion reaction for the neutron production. The deuterium or deuterium-tritium gas mixture is ionized in an RF-driven plasma source. The ions are then accelerated to {approx}100 keV energy using high current, high voltage DC-power supply to a target where the 2.45 MeV (for D-D reaction) or 14 MeV (for the D-T reaction) neutrons are generated. The development of two different types of neutron tubes are being discussed in this presentation, namely compact, pulsed operation neutron generators and cw, high yield neutron generators. These generators are currently operating at D-D neutron yields of 108 n/s and 109 n/s respectively. A facility, incorporating the larger neutron generator, has been constructed for Prompt Gamma Activation Analysis (PGAA) and Neutron Activation Analysis (NAA) measurements.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Equivalence of Dirac formulations

    NASA Astrophysics Data System (ADS)

    Joyce, William P.; Martin, Jeremy G.

    2002-06-01

    We construct general Dirac theories in both ⊗ ℓ(3, 1) and ⊗ ℓ(1, 3) using a first order left acting Dirac operator. Any two such theories are equivalent provided they have the same dimension. We also show that every 16- or 8-dimensional real Dirac theory in ℓ(3, 1) is equivalent to some (complex) Dirac theory in ⊗ ℓ(1, 3). As an immediate consequence of this we have that the Hestenes and original Dirac formulations are equivalent.

  8. Neutron star structure from QCD

    NASA Astrophysics Data System (ADS)

    Fraga, Eduardo S.; Kurkela, Aleksi; Vuorinen, Aleksi

    2016-03-01

    In this review article, we argue that our current understanding of the thermodynamic properties of cold QCD matter, originating from first principles calculations at high and low densities, can be used to efficiently constrain the macroscopic properties of neutron stars. In particular, we demonstrate that combining state-of-the-art results from Chiral Effective Theory and perturbative QCD with the current bounds on neutron star masses, the Equation of State of neutron star matter can be obtained to an accuracy better than 30% at all densities.

  9. Iterative Reconstruction of Coded Source Neutron Radiographs

    SciTech Connect

    Santos-Villalobos, Hector J; Bingham, Philip R; Gregor, Jens

    2012-01-01

    Use of a coded source facilitates high-resolution neutron imaging but requires that the radiographic data be deconvolved. In this paper, we compare direct deconvolution with two different iterative algorithms, namely, one based on direct deconvolution embedded in an MLE-like framework and one based on a geometric model of the neutron beam and a least squares formulation of the inverse imaging problem.

  10. 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.

  11. Formulations of entomopathogens as bioinsecticides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Developing a proper formulation is a necessary component for commercialization of entomopathogenic microbes as biological insecticides. The objective of this chapter is to present broad-ranging information about formulations to foster research toward developing commercial microbial-based insecticide...

  12. Nonlocal formulation of spin Coulomb drag

    NASA Astrophysics Data System (ADS)

    D'Amico, I.; Ullrich, C. A.

    2013-10-01

    The spin Coulomb drag (SCD) effect occurs in materials and devices where charged carriers with different spins exchange momentum via Coulomb scattering. This causes frictional forces between spin-dependent currents that lead to intrinsic dissipation, which may limit spintronics applications. A nonlocal formulation of SCD is developed which is valid for strongly inhomogeneous systems such as nanoscale spintronics devices. This nonlocal formulation of SCD is successfully applied to linewidths of intersubband spin plasmons in semiconductor quantum wells, where experiments have shown that the local approximation fails.

  13. Accelerator based epithermal neutron source for neutron capture therapy

    SciTech Connect

    Brugger, R.; Kunze, J.

    1991-05-01

    Several investigators have suggested that a charged particle accelerator with light element reactions might be able to produce enough epithermal neutrons to be useful in Neutron Capture Therapy. The reaction choice so far has been the Li(p,n) reaction with protons up to 2.5 MeV. A moderator around the target would reduce the faster neutrons down to the epithermal energy region. The goals of the present research are: identify better reactions; improve the moderators; and find better combinations of 1 and 2. The target is to achieve, at the patient location, an epithermal neutron current of greater than 10{sup 9}n/cm{sup 2}sec, with a dose to tissue from the neutrons alone of less than 10{sup {minus}10} rads/n and a dose from the gamma rays in the beam of less than 10{sup {minus}10} rads/n.

  14. Formal descriptions for formulation.

    PubMed

    This, Hervé

    2007-11-01

    Two formalisms used to describe the physical microstructure and the organization of formulated products are given. The first, called "complex disperse systems formalism" (CDS formalism) is useful for the description of the physical nature of disperse matter. The second, called "non periodical organizational space formalism" (NPOS formalism) has the same operators as the CDS formalism, but different elements; it is useful to describe the arrangement of any objects in space. Both formalisms can be viewed as the same, applied to different orders of magnitude for spatial size. PMID:17875375

  15. 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.

  16. Neutron sources: Present practice and future potential

    SciTech Connect

    Cierjacks, S.; Smith, A.B.

    1988-01-01

    The present capability and future potential of accelerator-based monoenergetic and white neutron sources are outlined in the context of fundamental and applied neutron-nuclear research. The neutron energy range extends from thermal to 500 MeV, and the time domain from steady-state to pico-second pulsed sources. Accelerator technology is summarized, including the production of intense light-ion, heavy-ion and electron beams. Target capabilities are discussed with attention to neutron-producing efficiency and power-handling capabilities. The status of underlying neutron-producing reactions is summarized. The present and future use of neutron sources in: fundamental neutron-nuclear research, nuclear data acquisition, materials damage studies, engineering tests, and biomedical applications are discussed. Emphasis is given to current status, near-term advances well within current technology, and to long-range projections. 90 refs., 4 figs.

  17. Neutron sources: present practice and future potential

    SciTech Connect

    Cierjacks, S.; Smith, A.B.

    1988-01-01

    The present capability and future potential of accelerator-based monoenergetic and white neutron sources are outlined in the context of fundamental and applied neutron-nuclear research. The neutron energy range extends from thermal to 500+ MeV, and the time domain from steady-state to pico-second pulsed sources. Accelerator technology is summarized, including the production of intense light-ion, heavy-ion and electron beams. Target capabilities are discussed with attention to neutron-production efficiency and power-handling capabilities. The status of underlying neutron-producing reactions is summarized. The present and future use of neutron sources in: (i) fundamental neutron-nuclear research, (ii) nuclear-data acquisition, (iii) materials-damage studies, (iv) engineering test, and (v) biomedical applications are discussed. Emphasis is given to current status, near-term advances well within current technology, and to long-range projections.

  18. 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/.

  19. 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)

  20. 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)

  1. Grand unification of neutron stars

    PubMed Central

    Kaspi, Victoria M.

    2010-01-01

    The last decade has shown us that the observational properties of neutron stars are remarkably diverse. From magnetars to rotating radio transients, from radio pulsars to isolated neutron stars, from central compact objects to millisecond pulsars, observational manifestations of neutron stars are surprisingly varied, with most properties totally unpredicted. The challenge is to establish an overarching physical theory of neutron stars and their birth properties that can explain this great diversity. Here I survey the disparate neutron stars classes, describe their properties, and highlight results made possible by the Chandra X-Ray Observatory, in celebration of its 10th anniversary. Finally, I describe the current status of efforts at physical “grand unification” of this wealth of observational phenomena, and comment on possibilities for Chandra’s next decade in this field. PMID:20404205

  2. Neutron range spectrometer

    DOEpatents

    Manglos, S.H.

    1988-03-10

    A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are colliminated 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. 1 fig.

  3. 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.

  4. Self-Setting Calcium Orthophosphate Formulations

    PubMed Central

    Dorozhkin, Sergey V.

    2013-01-01

    In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are bioactive and biodegradable grafting bioceramics in the form of a powder and a liquid. After mixing, both phases form pastes, which set and harden forming either a non-stoichiometric calcium deficient hydroxyapatite or brushite. Since both of them are remarkably biocompartible, bioresorbable and osteoconductive, self-setting calcium orthophosphate formulations appear to be promising bioceramics for bone grafting. Furthermore, such formulations possess excellent molding capabilities, easy manipulation and nearly perfect adaptation to the complex shapes of bone defects, followed by gradual bioresorption and new bone formation. In addition, reinforced formulations have been introduced, which might be described as calcium orthophosphate concretes. The discovery of self-setting properties opened up a new era in the medical application of calcium orthophosphates and many commercial trademarks have been introduced as a result. Currently such formulations are widely used as synthetic bone grafts, with several advantages, such as pourability and injectability. Moreover, their low-temperature setting reactions and intrinsic porosity allow loading by drugs, biomolecules and even cells for tissue engineering purposes. In this review, an insight into the self-setting calcium orthophosphate formulations, as excellent bioceramics suitable for both dental and bone grafting applications, has been provided. PMID:24956191

  5. Subscale Testing of Prompt Agent Defeat Formulations

    NASA Astrophysics Data System (ADS)

    Milby, Christopher; Stamatis, Demitrios; Daniels, Amber; Svingala, Forrest; Lightstone, Jim; Miller, Kendra; Bensman, Misty; Bohmke, Matthew

    2015-06-01

    There is a need to improve the current bioagent defeat systems with formulations that produce lower peak pressure, impulse, sustained high temperatures, and release of biocidal species for prompt defeat applications. In this work, explosive charge configurations similar to fuel-air explosives were detonated in a semi-enclosed chamber configuration. Binder type and fuel-to-oxidizer ratios were varied to observe the effects on combustion performance. Thermocouple measurements and high-speed video were used to monitor the combustion of the dispersed formulation. The down-selected formulations were then tested in a sub-scale vented agent defeat system developed to evaluate performance of formulations against aerosolized Bacillus thuringiensis (BT) spores. Diagnostics such as thermocouples, piezoelectric pressure gauges, and pyrometry were utilized to characterize the detonation event. Biological sampling with surface coupons, liquid impingement, and filters of the post detonation environment were utilized to determine spore survivability and rank the relative effectiveness of each formulation. Distribution Statement A: Approved for Public Release; Distribution is Unlimited

  6. Long Term Storage of Lyophilized Liposomal Formulations

    PubMed Central

    Payton, N.M.; Wempe, M.F.; Xu, Y.; Anchordoquy, T.J.

    2014-01-01

    Because aqueous liposomal formulations containing multiply unsaturated lipids are susceptible to chemical degradation, these formulations are often lyophilized. Despite their limited chemical stability, interest in the use of multiply unsaturated lipids to promote intracellular delivery has increased considerably in recent years. The goal of the current study was to examine the long term storage stability of lyophilized formulations containing lipids with increasing levels of unsaturation, and various strategies which can be employed to improve stability. Aqueous lipid-trehalose formulations containing 1,2-dilinolenoyl-sn-glycero-3-phosphocholine (DLPC), 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (DLinPC) or 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) were lyophilized and stored at temperatures ranging from 4°C to 60°C. We observed that the lipid degradation rate increased as the storage temperature and unsaturation level were increased. Even the cleanest sugars which are available commercially contain iron contaminants, and it was observed that the chelation of these iron contaminants significantly improved the stability of DLPC during storage. However, the glass transition temperature of the sugar which was included in the formulation, the reduction of the oxygen in the aqueous sample prior to lyophilization, the inclusion of helper lipids (i.e., cholesterol), and the rate of freezing did not significantly improve stability. PMID:25308534

  7. High-Order Entropy Stable Formulations for Computational Fluid Dynamics

    NASA Technical Reports Server (NTRS)

    Carpenter, Mark H.; Fisher, Travis C.

    2013-01-01

    A systematic approach is presented for developing entropy stable (SS) formulations of any order for the Navier-Stokes equations. These SS formulations discretely conserve mass, momentum, energy and satisfy a mathematical entropy inequality. They are valid for smooth as well as discontinuous flows provided sufficient dissipation is added at shocks and discontinuities. Entropy stable formulations exist for all diagonal norm, summation-by-parts (SBP) operators, including all centered finite-difference operators, Legendre collocation finite-element operators, and certain finite-volume operators. Examples are presented using various entropy stable formulations that demonstrate the current state-of-the-art of these schemes.

  8. Nanoliposomal Dry Powder Formulations

    PubMed Central

    Patel, Gaurang; Chougule, Mahavir; Singh, Mandip; Misra, Ambikanandan

    2013-01-01

    Liposomal dry powder formulations (DPFs) have proven their superiority over conventional DPFs due to favorably improved pharmacokinetics and pharmacodynamics of entrapped drugs, and thus, reduced local and systemic toxicities. Nanoliposomal DPFs (NLDPFs) provide stable, high aerosolization efficiency to deep lung, prolonged drug release, slow systemic dilution, and avoid macrophage uptake of encapsulated drug by carrier-based delivery of nano-range liposomes. This chapter describes methods of preparation of nanoliposomes (NLs) and NLDPFs, using various techniques, and their characterization with respect to size distribution, flow behavior, in vitro drug release profile, lung deposition, cellular uptake and cytotoxicity, and in vivo pharmacokinetics and pharmacodynamics. Some examples have been detailed for better understanding of the methods of preparation and evaluation of NLDPFs by investigators. PMID:19903555

  9. Prompt neutron multiplicity measurements with portable detectors

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Sanjoy; Wolff, Ronald; Maurer, Richard; Mitchell, Stephen; Smith, Ethan X.; Guss, Paul; Lacy, Jeffrey L.; Sun, L.; Athanasiades, A.

    2011-09-01

    Mobile detection of kilogram quantities of special nuclear materials (SNM) during maritime transportation is a challenging problem for the U.S. Department of Homeland Security. Counting neutrons emitted by the SNM and partitioning them from background neutrons of multiple origins is the most effective passive means of detecting the SNM. Unfortunately, neutron detection, counting, and partitioning in a maritime environment is complex due to the presence of spallation neutrons (commonly known as "ship effect") and to the complicated nature of the neutron scattering in that environment. This work studied the possibilities of building a prototype neutron detector using boron- 10 (10B) as the converter in a novel form factor called "straws" that would address the above problem by examining multiplicity distributions of neutrons originating from a fissioning source. Currently, commercially manufactured fission meters (FM) are available that separate cosmic neutrons from non-cosmic neutrons and quantitatively determine the strength of a fissioning source; however, these FMs use 3He, which is becoming increasingly difficult to procure; also the size and weight of a commercial FM is not conducive to manual neutron detection operations in a maritime environment. The current project may provide a near-term solution to the crisis that has arisen from the global scarcity of 3He by offering a viable alternative to the FM. The prototype detector provides a large-area, efficient, lightweight, more granular neutron responsive detection surface (to facilitate imaging) to ease the application of the new FMs.

  10. Imaging with cold neutrons

    NASA Astrophysics Data System (ADS)

    Lehmann, E. H.; Kaestner, A.; Josic, L.; Hartmann, S.; Mannes, D.

    2011-09-01

    Neutrons for imaging purposes are provided mainly from thermal beam lines at suitable facilities around the world. The access to cold neutrons is presently limited to very few places only. However, many challenging options for imaging with cold neutrons have been found out, given by the interaction behavior of the observed materials with neutrons in the cold energy range (3-10 Å). For absorbing materials, the interaction probability increases proportionally with the wavelength with the consequence of more contrast but less transmission with cold neutrons. Many materials are predominantly scattering neutrons, in particular most of crystalline structural materials. In these cases, cold neutrons play an important role by covering the energy range of the most important Bragg edges given by the lattice planes of the crystallites. This particular behavior can be used for at least two important aspects—choosing the right energy of the initial beam enables to have a material more or less transparent, and a direct macroscopic visualization of the crystalline structure and its change in a manufacturing process. Since 2006, PSI operates its second beam line for neutron imaging, where cold neutrons are provided from a liquid deuterium cold source (operated at 25 K). It has been designed to cover the most current aspects in neutron imaging research with the help of high flexibility. This has been done with changeable inlet apertures, a turbine based velocity selector, two beam positions and variable detector systems, satisfying the demands of the individual investigation. The most important detection system was found to be a micro-tomography system that enables studies in the presently best spatial resolution. In this case, the high contrast from the sample interaction process and the high detection probability for the cold neutrons combines in an ideal combination for the best possible performance. Recently, it was found out that the energy selective studies might become a

  11. Measuring neutron spectra in radiotherapy using the nested neutron spectrometer

    SciTech Connect

    Maglieri, Robert Evans, Michael; Seuntjens, Jan; Kildea, John; Licea, Angel

    2015-11-15

    Purpose: Out-of-field neutron doses resulting from photonuclear interactions in the head of a linear accelerator pose an iatrogenic risk to patients and an occupational risk to personnel during radiotherapy. To quantify neutron production, in-room measurements have traditionally been carried out using Bonner sphere systems (BSS) with activation foils and TLDs. In this work, a recently developed active detector, the nested neutron spectrometer (NNS), was tested in radiotherapy bunkers. Methods: The NNS is designed for easy handling and is more practical than the traditional BSS. Operated in current-mode, the problem of pulse pileup due to high dose-rates is overcome by measuring current, similar to an ionization chamber. In a bunker housing a Varian Clinac 21EX, the performance of the NNS was evaluated in terms of reproducibility, linearity, and dose-rate effects. Using a custom maximum-likelihood expectation–maximization algorithm, measured neutron spectra at various locations inside the bunker were then compared to Monte Carlo simulations of an identical setup. In terms of dose, neutron ambient dose equivalents were calculated from the measured spectra and compared to bubble detector neutron dose equivalent measurements. Results: The NNS-measured spectra for neutrons at various locations in a treatment room were found to be consistent with expectations for both relative shape and absolute magnitude. Neutron fluence-rate decreased with distance from the source and the shape of the spectrum changed from a dominant fast neutron peak near the Linac head to a dominant thermal neutron peak in the moderating conditions of the maze. Monte Carlo data and NNS-measured spectra agreed within 30% at all locations except in the maze where the deviation was a maximum of 40%. Neutron ambient dose equivalents calculated from the authors’ measured spectra were consistent (one standard deviation) with bubble detector measurements in the treatment room. Conclusions: The NNS may

  12. 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.

  13. a Portable Pulsed Neutron Generator

    NASA Astrophysics Data System (ADS)

    Skoulakis, A.; Androulakis, G. C.; Clark, E. L.; Hassan, S. M.; Lee, P.; Chatzakis, J.; Bakarezos, M.; Dimitriou, V.; Petridis, C.; Papadogiannis, N. A.; Tatarakis, M.

    2014-02-01

    The design and construction of a pulsed plasma focus device to be used as a portable neutron source for material analysis such as explosive detection using gamma spectroscopy is presented. The device is capable of operating at a repetitive rate of a few Hz. When deuterium gas is used, up to 105 neutrons per shot are expected to be produced with a temporal pulse width of a few tens of nanoseconds. The pulsed operation of the device and its portable size are its main advantage in comparison with the existing continuous neutron sources. Parts of the device include the electrical charging unit, the capacitor bank, the spark switch (spark gap), the trigger unit and the vacuum-fuel chamber / anode-cathode. Numerical simulations are used for the simulation of the electrical characteristics of the device including the scaling of the capacitor bank energies with total current, the pinch current, and the scaling of neutron yields with energies and currents. The MCNPX code is used to simulate the moderation of the produced neutrons in a simplified geometry and subsequently, the interaction of thermal neutrons with a test target and the corresponding prompt γ-ray generation.

  14. 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.

  15. Insulin formulations--a review.

    PubMed

    Gualandi-Signorini, A M; Giorgi, G

    2001-01-01

    Although the improvement on insulin therapy since it was first conceived, it is still far from mimicking physiological secretion of pancreatic b-cells and research to find new insulin formulations and new routes of administration continues. Human biosynthetic insulin (rapid-acting, intermediate-acting and long-acting), produced by recombinant DNA technique, is currently available. The pharmacokinetic profile of rapid-acting insulin (regular) does not adequately reproduce the physiological post-prandial insulin response. This has led to the development of molecular analogues with slight modifications that prevent the spontaneous polymerisation underlying delayed absorption. Fast-acting analogues such as Lyspro and Aspart can be injected immediately before the meal, inducing a very fast and substantial peak of insulin, similar to that produced by b-cells, but have the disadvantage of short duration of action. For this reason, and because of the difficulty of obtaining sufficient basal insulin concentrations to control preprandial blood glucose levels with current long-acting insulins, analogues known as Glargine and Detemir have been synthesized. They have virtually no plasma peak and acts for about 24 h. These characteristics make it ideal to cover basal insulin requirement. With insulin analogues, it also seems possible to overcome the problem of intra- and inter-individual variability in absorption after subcutaneous injection. This variability is directly proportional to the duration of insulin action. Research into new routes of administration has led to production of inhaled insulin powder, soon to become commercially available. Insulin is absorbed through the lung alveoli. Trials to evaluate efficacy and toleration have shown that inhaled insulin has a similar kinetic profile to the fast-acting injected analogue and can therefore be used for mealtime requirement, combined with a single daily injection of long-acting insulin. Oral insulin is currently being

  16. Gauge-Invariant Formulation of Circular Dichroism.

    PubMed

    Raimbault, Nathaniel; de Boeij, Paul L; Romaniello, Pina; Berger, J A

    2016-07-12

    Standard formulations of magnetic response properties, such as circular dichroism spectra, are plagued by gauge dependencies, which can lead to unphysical results. In this work, we present a general gauge-invariant and numerically efficient approach for the calculation of circular dichroism spectra from the current density. First we show that in this formulation the optical rotation tensor, the response function from which circular dichroism spectra can be obtained, is independent of the origin of the coordinate system. We then demonstrate that its trace is independent of the gauge origin of the vector potential. We also show how gauge invariance can be retained in practical calculations with finite basis sets. As an example, we explain how our method can be applied to time-dependent current-density-functional theory. Finally, we report gauge-invariant circular dichroism spectra obtained using the adiabatic local-density approximation. The circular dichroism spectra we thus obtain are in good agreement with experiment. PMID:27295541

  17. The Fundamental Neutron Physics Facilities at NIST

    PubMed Central

    Nico, J. S.; Arif, M.; Dewey, M. S.; Gentile, T. R.; Gilliam, D. M.; Huffman, P. R.; Jacobson, D. L.; Thompson, A. K.

    2005-01-01

    The program in fundamental neutron physics at the National Institute of Standards and Technology (NIST) began nearly two decades ago. The Neutron Interactions and Dosimetry Group currently maintains four neutron beam lines dedicated to studies of fundamental neutron interactions. The neutrons are provided by the NIST Center for Neutron Research, a national user facility for studies that include condensed matter physics, materials science, nuclear chemistry, and biological science. The beam lines for fundamental physics experiments include a high-intensity polychromatic beam, a 0.496 nm monochromatic beam, a 0.89 nm monochromatic beam, and a neutron interferometer and optics facility. This paper discusses some of the parameters of the beam lines along with brief presentations of some of the experiments performed at the facilities. PMID:27308110

  18. 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.

  19. NEUTRON SOURCE

    DOEpatents

    Foster, J.S. Jr.

    1960-04-19

    A compact electronic device capable of providing short time high density outputs of neutrons is described. The device of the invention includes an evacuated vacuum housing adapted to be supplied with a deuterium, tritium, or other atmosphere and means for establishing an electrical discharge along a path through the gas. An energized solenoid is arranged to constrain the ionized gas (plasma) along the path. An anode bearing adsorbed or adherent target material is arranged to enclose the constrained plasma. To produce neutrons a high voltage is applied from appropriate supply means between the plasma and anode to accelerate ions from the plasma to impinge upcn the target material, e.g., comprising deuterium.

  20. Explosive Formulation Code Naming SOP

    SciTech Connect

    Martz, H. E.

    2014-09-19

    The purpose of this SOP is to provide a procedure for giving individual HME formulations code names. A code name for an individual HME formulation consists of an explosive family code, given by the classified guide, followed by a dash, -, and a number. If the formulation requires preparation such as packing or aging, these add additional groups of symbols to the X-ray specimen name.

  1. Baseline LAW Glass Formulation Testing

    SciTech Connect

    Kruger, Albert A.; Mooers, Cavin; Bazemore, Gina; Pegg, Ian L.; Hight, Kenneth; Lai, Shan Tao; Buechele, Andrew; Rielley, Elizabeth; Gan, Hao; Muller, Isabelle S.; Cecil, Richard

    2013-06-13

    The major objective of the baseline glass formulation work was to develop and select glass formulations that are compliant with contractual and processing requirements for each of the LAW waste streams. Other objectives of the work included preparation and characterization of glasses with respect to the properties of interest, optimization of sulfate loading in the glasses, evaluation of ability to achieve waste loading limits, testing to demonstrate compatibility of glass melts with melter materials of construction, development of glass formulations to support ILAW qualification activities, and identification of glass formulation issues with respect to contract specifications and processing requirements.

  2. Surface Mounted Neutron Generators

    NASA Astrophysics Data System (ADS)

    Elizondo-Decanini, Juan M.

    2012-10-01

    A deuterium-tritium (DT) base reaction pulsed neutron generator packaged in a flat computer chip shape of 1.54 cm (0.600 in) wide by 3.175 cm (1.25 in) length and 0.3 cm (0.120 in) thick has been successfully demonstrated to produce 14 MeV neutrons at a rate of 10^9 neutrons per second. The neutron generator is based on a deuterium ion beam accelerated to impact a tritium loaded target. The accelerating voltage is in the 15 to 20 kV in a 3 mm (0.120 in) gap, the ion beam is shaped by using a lens design to produce a flat ion beam that conforms to the flat rectangular target. The ion source is a simple surface mounted deuterium filled titanium film with a fused gap that operates at a current-voltage design to release the deuterium during a pulse length of about 1 μs. We present the general description of the working prototypes, which we have labeled the ``NEUTRISTOR.''[4pt] Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration. Work funded by the LDRD office.

  3. Alternative Neutron Detection Testing Summary

    SciTech Connect

    Kouzes, Richard T.; Ely, James H.; Erikson, Luke E.; Kernan, Warnick J.; Lintereur, Azaree T.; Siciliano, Edward R.; Stromswold, David C.; Woodring, Mitchell L.

    2010-04-08

    Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive neutron detection systems. The main reason for having neutron detection capability is to detect fission neutrons from plutonium. Most currently deployed radiation portal monitors (RPMs) use neutron detectors based upon 3He-filled gas proportional counters, which are the most common large area neutron detector. This type of neutron detector is used in the TSA and other RPMs installed in international locations and in the Ludlum and Science Applications International Corporation RPMs deployed primarily for domestic applications. There is a declining supply of 3He in the world and, thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and sensitivity to cargo-borne neutrons are being investigated. Four technologies have been identified as being currently commercially available, potential alternative neutron detectors to replace the use of 3He in RPMs. These technologies are: 1) Boron trifluoride-filled proportional counters, 2) Boron-lined proportional counters, 3) Lithium-loaded glass fibers, and 4) Coated wavelength-shifting plastic fibers. Reported here is a summary of the testing carried out at Pacific Northwest National Laboratory on these technologies to date, as well as measurements on 3He tubes at various pressures. Details on these measurements are available in the referenced reports. Sponsors of these tests include the Department of Energy (DOE), Department of Homeland Security (DHS), and the Department of Defense (DoD), as well as internal Pacific Northwest National Laboratory funds.

  4. 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.

  5. 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.

  6. Analysis of Cadmium Based Neutron Detector Configurations

    NASA Astrophysics Data System (ADS)

    James, Brian; Rees, Lawrence; Czirr, J. Bart

    2012-10-01

    Due to national security concerns pertaining to the smuggling of special nuclear materials and a small supply of He-3 for use in neutron detectors, there is currently a need for a new kind of neutron detector. Using Monte Carlo techniques I have studied the neutron capture efficiency of an array of cadmium wedge detectors in the presence of a californium source. By using varying numbers of wedges and comparing their capture ratios we will be better able to design future detectors.

  7. 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)

  8. 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.

  9. Operator Formulation of Classical Mechanics.

    ERIC Educational Resources Information Center

    Cohn, Jack

    1980-01-01

    Discusses the construction of an operator formulation of classical mechanics which is directly concerned with wave packets in configuration space and is more similar to that of convential quantum theory than other extant operator formulations of classical mechanics. (Author/HM)

  10. Biopsychosocial Formulation: Recognizing Educational Shortcomings

    ERIC Educational Resources Information Center

    McClain, Tina; O'Sullivan, Patricia S.; Clardy, James A.

    2004-01-01

    Objective: Since Engel introduced the biopsychosocial model, it has been extensively examined. The authors expect psychiatrists to formulate cases using the biopsychosocial model. However, resident psychiatrists' ability to generate formulations using this model has received little attention. Methods: The authors evaluated resident biopsychosocial…

  11. LANSCE beam current limiter

    SciTech Connect

    Gallegos, F.R.

    1996-06-01

    The Radiation Security System (RSS) at the Los Alamos Neutron Science Center (LANSCE) provides personnel protection from prompt radiation due to accelerated beam. Active instrumentation, such as the Beam Current Limiter, is a component of the RSS. The current limiter is designed to limit the average current in a beam line below a specific level, thus minimizing the maximum current available for a beam spill accident. The beam current limiter is a self-contained, electrically isolated toroidal beam transformer which continuously monitors beam current. It is designed as fail-safe instrumentation. The design philosophy, hardware design, operation, and limitations of the device are described.

  12. LANSCE beam current limiter

    SciTech Connect

    Gallegos, F.R.

    1997-01-01

    The Radiation Security System (RSS) at the Los Alamos Neutron Science Center (LANSCE) provides personnel protection from prompt radiation due to accelerated beam. Active instrumentation, such as the beam current limiter, is a component of the RSS. The current limiter is designed to limit the average current in a beamline below a specific level, thus minimizing the maximum current available for a beam spill accident. The beam current limiter is a self-contained, electrically isolated toroidal beam transformer which continuously monitors beam current. It is designed as fail-safe instrumentation. The design philosophy, hardware design, operation, and limitations of the device are described. {copyright} {ital 1997 American Institute of Physics.}

  13. 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.

  14. 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.

  15. 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)

  16. Materials for spallation neutron sources

    SciTech Connect

    Sommer, W.F.; Daemen, L.L.

    1996-03-01

    The Workshop on Materials for Spallation Neutron Sources at the Los Alamos Neutron Science Center, February 6 to 10, 1995, gathered scientists from Department of Energy national laboratories, other federal institutions, universities, and industry to discuss areas in which work is needed, successful designs and use of materials, and opportunities for further studies. During the first day of the workshop, speakers presented overviews of current spallation neutron sources. During the next 3 days, seven panels allowed speakers to present information on a variety of topics ranging from experimental and theoretical considerations on radiation damage to materials safety issues. An attempt was made to identify specific problems that require attention within the context of spallation neutron sources. This proceedings is a collection of summaries from the overview sessions and the panel presentations.

  17. Neutron multiplicity analysis tool

    SciTech Connect

    Stewart, Scott L

    2010-01-01

    I describe the capabilities of the EXCOM (EXcel based COincidence and Multiplicity) calculation tool which is used to analyze experimental data or simulated neutron multiplicity data. The input to the program is the count-rate data (including the multiplicity distribution) for a measurement, the isotopic composition of the sample and relevant dates. The program carries out deadtime correction and background subtraction and then performs a number of analyses. These are: passive calibration curve, known alpha and multiplicity analysis. The latter is done with both the point model and with the weighted point model. In the current application EXCOM carries out the rapid analysis of Monte Carlo calculated quantities and allows the user to determine the magnitude of sample perturbations that lead to systematic errors. Neutron multiplicity counting is an assay method used in the analysis of plutonium for safeguards applications. It is widely used in nuclear material accountancy by international (IAEA) and national inspectors. The method uses the measurement of the correlations in a pulse train to extract information on the spontaneous fission rate in the presence of neutrons from ({alpha},n) reactions and induced fission. The measurement is relatively simple to perform and gives results very quickly ({le} 1 hour). By contrast, destructive analysis techniques are extremely costly and time consuming (several days). By improving the achievable accuracy of neutron multiplicity counting, a nondestructive analysis technique, it could be possible to reduce the use of destructive analysis measurements required in safeguards applications. The accuracy of a neutron multiplicity measurement can be affected by a number of variables such as density, isotopic composition, chemical composition and moisture in the material. In order to determine the magnitude of these effects on the measured plutonium mass a calculational tool, EXCOM, has been produced using VBA within Excel. This

  18. Neutron Generators for Spent Fuel Assay

    SciTech Connect

    Ludewigt, Bernhard A

    2010-12-30

    The Next Generation Safeguards Initiative (NGSI) of the U.S. DOE has initiated a multi-lab/university collaboration to quantify the plutonium (Pu) mass in, and detect the diversion of pins from, spent nuclear fuel (SNF) assemblies with non-destructive assay (NDA). The 14 NDA techniques being studied include several that require an external neutron source: Delayed Neutrons (DN), Differential Die-Away (DDA), Delayed Gammas (DG), and Lead Slowing-Down Spectroscopy (LSDS). This report provides a survey of currently available neutron sources and their underlying technology that may be suitable for NDA of SNF assemblies. The neutron sources considered here fall into two broad categories. The term 'neutron generator' is commonly used for sealed devices that operate at relatively low acceleration voltages of less than 150 kV. Systems that employ an acceleration structure to produce ion beam energies from hundreds of keV to several MeV, and that are pumped down to vacuum during operation, rather than being sealed units, are usually referred to as 'accelerator-driven neutron sources.' Currently available neutron sources and future options are evaluated within the parameter space of the neutron generator/source requirements as currently understood and summarized in section 2. Applicable neutron source technologies are described in section 3. Commercially available neutron generators and other source options that could be made available in the near future with some further development and customization are discussed in sections 4 and 5, respectively. The pros and cons of the various options and possible ways forward are discussed in section 6. Selection of the best approach must take a number of parameters into account including cost, size, lifetime, and power consumption, as well as neutron flux, neutron energy spectrum, and pulse structure that satisfy the requirements of the NDA instrument to be built.

  19. The possible use of a spallation neutron source for neutron capture therapy with epithermal neutrons

    SciTech Connect

    Grusell, E.; Conde, H.; Larsson, B.; Roennqvist, T.; Sornsuntisook, O.; Crawford, J.; Reist, H.; Dahl, B.; Sjoestrand, N.G.; Russel, G. . Dept. of Radiation Sciences; Paul Scherrer Inst. , Villigen; Chalmers Univ. of Tech., Goeteborg . Dept. of Reactor Physics; Los Alamos National Lab., NM )

    1989-01-01

    Spallation is induced in a heavy material by 72 MeV protons. The hereby produced neutrons with essentially an evaporation spectrum with a peak energy of less than 2 MeV are moderated in two steps, first in iron, and then in carbon. Results from neutron fluence measurements in a perspex phantom placed close to the moderator are presented. Monte Carlo calculations of neutron fluence in a water phantom are also presented under some chosen configurations of spallation source and moderator. The calculations and measurements show a good agreement and also show that useful thermal neutron fluences are attainable in the depth of the brain, at proton currents of less than 0.5 mA. 3 refs., 5 figs., 4 tabs.

  20. A neutron spectrometer for neutron energies between 1 eV and 10 keV

    SciTech Connect

    Wang, C.K.; Blue, T.E.

    1988-01-01

    In boron neutron capture therapy (BNCT), it is the consensus that epithermal neutron beams have advantages over thermal beams in treating deep-seated brain tumors, and large neutron fields have advantages over narrow beams, since whole-brain irradiations are thought to be necessary in many cases. Epithermal neutron sources for BNCT, which include filtered reactor neutron beams and moderated reactor neutron fields, are currently being developed at many institutions around the world. Neutrons with energies between 1 eV and 10 keV are most suitable for treating brain tumors. However, techniques for measuring neutron spectra in a vacuum in this energy range are not well developed. This paper describes a new type of neutron spectrometer that has a set of response functions that peak at equally spaced intervals on a logarithmic energy scale ranging from 1 eV to 10 keV; therefore, neutron spectra (or histograms) in this energy range can be obtained by properly applying spectrum unfolding techniques to the measured data. The spectrometer is applicable for measurements in a vacuum for both narrow neutron beams and wide neutron fields.

  1. CR-39 detector based thermal neutron flux measurements, in the photo neutron project

    NASA Astrophysics Data System (ADS)

    Mameli, A.; Greco, F.; Fidanzio, A.; Fusco, V.; Cilla, S.; D'Onofrio, G.; Grimaldi, L.; Augelli, B. G.; Giannini, G.; Bevilacqua, R.; Totaro, P.; Tommasino, L.; Azario, L.; Piermattei, A.

    2008-08-01

    PhoNeS (photo neutron source) is a project aimed at the production and moderation of neutrons by exploiting high energy linear accelerators, currently used in radiotherapy. A feasibility study has been carried out with the scope in mind to use the high energy photon beams from these accelerators for the production of neutrons suitable for boron neutron capture therapy (BNCT). Within these investigations, it was necessary to carry out preliminary measurements of the thermal neutron component of neutron spectra, produced by the photo-conversion of X-ray radiotherapy beams supplied by three LinAcs: 15 MV, 18 MV and 23 MV. To this end, a simple passive thermal neutron detector has been used which consists of a CR-39 track detector facing a new type of boron-loaded radiator. Once calibrated, this passive detector has been used for the measurement of both the thermal neutron component and the cadmium ratio of different neutron spectra. In addition, bubble detectors with a response highly sensitive to thermal neutrons have also been used. Both thermal neutron detectors are simple to use, very compact and totally insensitive to low-ionizing radiation such as electrons and X-rays. The resultant thermal neutron flux was above 10 6 n/cm 2s and the cadmium ratio was no greater than 15 for the first attempt of photo-conversion of X-ray radiotherapy beams.

  2. The Need for Pediatric Formulations to Treat Children with HIV

    PubMed Central

    2016-01-01

    Over 3.2 million children worldwide are infected with HIV, but only 24% of these children receive antiretroviral therapy (ART). ART adherence among children is a crucial part of managing human-immunodeficiency virus (HIV) infection and extending the life and health of infected children. Important causes of poor adherence are formulation- and regimen-specific properties, including poor palatability, large pill burden, short dosing intervals, and the complex storage and transportation of drugs. This review aims to summarize the various regimen- and formulation-based barriers to ART adherence among children to support the need for new and innovative pediatric formulations for antiretroviral therapy (ART). Detailing the arguments both for and against investing in the development of pediatric HIV medications, as well as highlighting recent advances in pediatric ART formulation research, provides a synopsis of the current data related to pediatric ART formulations and adherence. PMID:27413548

  3. Advances in device and formulation technologies for pulmonary drug delivery.

    PubMed

    Chan, John Gar Yan; Wong, Jennifer; Zhou, Qi Tony; Leung, Sharon Shui Yee; Chan, Hak-Kim

    2014-08-01

    Inhaled pharmaceuticals are formulated and delivered differently according to the therapeutic indication. However, specific device-formulation coupling is often fickle, and new medications or indications also demand new strategies. The discontinuation of chlorofluorocarbon propellants has seen replacement of older metered dose inhalers with dry powder inhaler formulations. High-dose dry powder inhalers are increasingly seen as an alternative dosage form for nebulised medications. In other cases, new medications have completely bypassed conventional inhalers and been formulated for use with unique inhalers such as the Staccato® device. Among these different devices, integration of software and electronic assistance has become a shared trend. This review covers recent device and formulation advances that are forming the current landscape of inhaled therapeutics. PMID:24728868

  4. Applications of novel drug delivery system for herbal formulations.

    PubMed

    Ajazuddin; Saraf, S

    2010-10-01

    Over the past several years, great advances have been made on development of novel drug delivery systems (NDDS) for plant actives and extracts. The variety of novel herbal formulations like polymeric nanoparticles, nanocapsules, liposomes, phytosomes, nanoemulsions, microsphere, transferosomes, and ethosomes has been reported using bioactive and plant extracts. The novel formulations are reported to have remarkable advantages over conventional formulations of plant actives and extracts which include enhancement of solubility, bioavailability, protection from toxicity, enhancement of pharmacological activity, enhancement of stability, improved tissue macrophages distribution, sustained delivery, and protection from physical and chemical degradation. The present review highlights the current status of the development of novel herbal formulations and summarizes their method of preparation, type of active ingredients, size, entrapment efficiency, route of administration, biological activity and applications of novel formulations. PMID:20471457

  5. The Need for Pediatric Formulations to Treat Children with HIV.

    PubMed

    Schlatter, Adrienne F; Deathe, Andrew R; Vreeman, Rachel C

    2016-01-01

    Over 3.2 million children worldwide are infected with HIV, but only 24% of these children receive antiretroviral therapy (ART). ART adherence among children is a crucial part of managing human-immunodeficiency virus (HIV) infection and extending the life and health of infected children. Important causes of poor adherence are formulation- and regimen-specific properties, including poor palatability, large pill burden, short dosing intervals, and the complex storage and transportation of drugs. This review aims to summarize the various regimen- and formulation-based barriers to ART adherence among children to support the need for new and innovative pediatric formulations for antiretroviral therapy (ART). Detailing the arguments both for and against investing in the development of pediatric HIV medications, as well as highlighting recent advances in pediatric ART formulation research, provides a synopsis of the current data related to pediatric ART formulations and adherence. PMID:27413548

  6. Formulation of diclofenac for dermal delivery.

    PubMed

    Goh, Choon Fu; Lane, Majella E

    2014-10-01

    Diclofenac (DF) was first synthesized in the 1960's and is currently available as ophthalmic, oral, parenteral, rectal and skin preparations. This review focuses on the administration of DF to the skin. As a member of the non-steroidal anti-inflammatory (NSAID) group of drugs the primary indications of DF are for the management of inflammation and pain but it is also used to treat actinic keratosis. The specific aims of this paper are to: (i) provide an overview of the pharmacokinetics and metabolism of DF following oral and topical administration; (ii) examine critically the various formulation approaches which have been investigated to enhance dermal delivery of DF; and (iii) identify new formulation strategies for enhanced DF skin penetration. PMID:25091375

  7. Novel Formulations for Antimicrobial Peptides

    PubMed Central

    Carmona-Ribeiro, Ana Maria; Carrasco, Letícia Dias de Melo

    2014-01-01

    Peptides in general hold much promise as a major ingredient in novel supramolecular assemblies. They may become essential in vaccine design, antimicrobial chemotherapy, cancer immunotherapy, food preservation, organs transplants, design of novel materials for dentistry, formulations against diabetes and other important strategical applications. This review discusses how novel formulations may improve the therapeutic index of antimicrobial peptides by protecting their activity and improving their bioavailability. The diversity of novel formulations using lipids, liposomes, nanoparticles, polymers, micelles, etc., within the limits of nanotechnology may also provide novel applications going beyond antimicrobial chemotherapy. PMID:25302615

  8. Burst Oscillations: Watching Neutron Stars Spin

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod

    2010-01-01

    It is now almost 15 years since the first detection of rotationally modulated emission from X-ray bursting neutron stars, "burst oscillations," This phenomenon enables us to see neutron stars spin, as the X-ray burst flux asymmetrically lights up the surface. It has enabled a new way to probe the neutron star spin frequency distribution, as well as to elucidate the multidimensional nature of nuclear burning on neutron stars. I will review our current observational understanding of the phenomenon, with an eye toward highlighting some of the interesting remaining puzzles, of which there is no shortage.

  9. BINP accelerator based epithermal neutron source.

    PubMed

    Aleynik, V; Burdakov, A; Davydenko, V; Ivanov, A; Kanygin, V; Kuznetsov, A; Makarov, A; Sorokin, I; Taskaev, S

    2011-12-01

    Innovative facility for neutron capture therapy has been built at BINP. This facility is based on compact vacuum insulation tandem accelerator designed to produce proton current up to 10 mA. Epithermal neutrons are proposed to be generated by 1.915-2.5 MeV protons bombarding a lithium target using (7)Li(p,n)(7)Be threshold reaction. In the article, diagnostic techniques for proton beam and neutrons developed are described, results of experiments on proton beam transport and neutron generation are shown, discussed, and plans are presented. PMID:21439836

  10. Gamma compensated, self powered neutron detector

    DOEpatents

    Brown, Donald P.

    1977-01-01

    An improved, self-powered, gamma compensated, neutron detector having two electrically conductive concentric cylindrical electrodes and a central rod emitter formed from a material which emits beta particles when bombarded by neutrons. The outer electrode and emitter are maintained at a common potential and the neutron representative current is furnished at the inner cylindrical electrode which serves as a collector. The two concentric cylindrical electrodes are designed to exhibit substantially equal electron emission induced by Compton scattering under neutron bombardment to supply the desired gamma compensation.

  11. PLANS FOR A NEUTRON EDM EXPERIMENT AT SNS

    SciTech Connect

    ITO, TAKEYASU

    2007-01-31

    The electric dipole moment of the neutron, leptons, and atoms provide a unique window to Physics Beyond the Standard Model. They are currently developing a new neutron EDM experiment (the nEDM Experiment). This experiment, which will be run at the 8.9 {angstrom} Neutron Line at the Fundamental Neutron Physics Beamline (FNPB) at the Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory, will search for the neutron EDM with a sensitivity two orders of magnitude higher than the present limit. In this paper, the motivation for the experiment, the experimental method, and the present status of the experiment are discussed.

  12. Compact neutron generator developement and applications

    SciTech Connect

    Leung, Ka-Ngo; Reijonen, Jani; Gicquel, Frederic; Hahto, Sami; Lou, Tak-Pui

    2004-01-18

    The Plasma and Ion Source Technology Group at the Lawrence Berkeley National Laboratory has been engaging in the development of high yield compact neutron generators for the last ten years. Because neutrons in these generators are formed by using either D-D, T-T or D-T fusion reaction, one can produce either mono-energetic (2.4 MeV or 14 MeV) or white neutrons. All the neutron generators being developed by our group utilize 13.5 MHz RF induction discharge to produce a pure deuterium or a mixture of deuterium-tritium plasma. As a result, ion beams with high current density and almost pure atomic ions can be extracted from the plasma source. The ion beams are accelerated to {approx}100 keV and neutrons are produced when the beams impinge on a titanium target. Neutron generators with different configurations and sizes have been designed and tested at LBNL. Their applications include neutron activation analysis, oil-well logging, boron neutron capture therapy, brachytherapy, cargo and luggage screening. A novel small point neutron source has recently been developed for radiography application. The source size can be 2 mm or less, making it possible to examine objects with sharper images. The performance of these neutron generators will be described in this paper.

  13. Neutrons scattering studies in the actinide region

    SciTech Connect

    Kegel, G.H.R.; Egan, J.J.

    1992-09-01

    During the report period were investigated the following areas: prompt fission neutron energy spectra measurements; neutron elastic and inelastic scattering from [sup 239]Pu; neutron scattering in [sup 181]Ta and [sup 197]Au; response of a [sup 235]U fission chamber near reaction thresholds; two-parameter data acquisition system; black'' neutron detector; investigation of neutron-induced defects in silicon dioxide; and multiple scattering corrections. Four Ph.D. dissertations and one M.S. thesis were completed during the report period. Publications consisted of three journal articles, four conference papers in proceedings, and eleven abstracts of presentations at scientific meetings. There are currently four Ph.D. and one M.S. candidates working on dissertations directly associated with the project. In addition, three other Ph.D. candidates are working on dissertations involving other aspects of neutron physics in this laboratory.

  14. Cold Neutrons Trapped in External Fields

    SciTech Connect

    Gandolfi, S.; Carlson, J.; Pieper, Steven C.

    2011-01-07

    The properties of inhomogeneous neutron matter are crucial to the physics of neutron-rich nuclei and the crust of neutron stars. Advances in computational techniques now allow us to accurately determine the binding energies and densities of many neutrons interacting via realistic microscopic interactions and confined in external fields. We perform calculations for different external fields and across several shells to place important constraints on inhomogeneous neutron matter, and hence the large isospin limit of the nuclear energy density functionals that are used to predict properties of heavy nuclei and neutron star crusts. We find important differences between microscopic calculations and current density functionals; in particular, the isovector gradient terms are significantly more repulsive than in traditional models, and the spin-orbit and pairing forces are comparatively weaker.

  15. Cold neutrons trapped in external fields.

    SciTech Connect

    Gandolfi, S.; Carlson, J.; Pieper, S. C.

    2011-01-05

    The properties of inhomogeneous neutron matter are crucial to the physics of neutron-rich nuclei and the crust of neutron stars. Advances in computational techniques now allow us to accurately determine the binding energies and densities of many neutrons interacting via realistic microscopic interactions and confined in external fields. We perform calculations for different external fields and across several shells to place important constraints on inhomogeneous neutron matter, and hence the large isospin limit of the nuclear energy density functionals that are used to predict properties of heavy nuclei and neutron star crusts. We find important differences between microscopic calculations and current density functionals; in particular, the isovector gradient terms are significantly more repulsive than in traditional models, and the spin-orbit and pairing forces are comparatively weaker.

  16. Neutrons scattering studies in the actinide region

    NASA Astrophysics Data System (ADS)

    Kegel, G. H. R.; Egan, J. J.

    1992-09-01

    During the last report period, we investigated the following areas: prompt fission neutron energy spectra measurements; neutron elastic and inelastic scattering from Pu-239; neutron scattering in Ta-181 and Au-197; response of a U-235 fission chamber near reaction thresholds; two-parameter data acquisition system; 'black' neutron detector; investigation of neutron-induced defects in silicon dioxide; and multiple scattering corrections. Four Ph.D. dissertations and one M.S. thesis were completed during the report period. Publications consisted of three journal articles, four conference papers in proceedings, and eleven abstracts of presentations at scientific meetings. There are currently four Ph.D. and one M.S. candidates working on dissertations directly associated with the project. In addition, three other Ph.D. candidates are working on dissertations involving other aspects of neutron physics in this laboratory.

  17. Simple formulation of magnetoplasmadynamic acceleration

    SciTech Connect

    Sasoh, A. )

    1994-03-01

    A simple formulation of magnetoplasmadynamic acceleration has been made based on energy conservation relations and a generalized Ohm's law. An exhaust velocity is expressed using three characteristic parameters: (1) a dimensionless characteristic velocity [ital [tilde U

  18. Application of an ultraminiature thermal neutron monitor for irradiation field study of accelerator-based neutron capture therapy

    PubMed Central

    Ishikawa, Masayori; Tanaka, Kenichi; Endo, Satrou; Hoshi, Masaharu

    2015-01-01

    Phantom experiments to evaluate thermal neutron flux distribution were performed using the Scintillator with Optical Fiber (SOF) detector, which was developed as a thermal neutron monitor during boron neutron capture therapy (BNCT) irradiation. Compared with the gold wire activation method and Monte Carlo N-particle (MCNP) calculations, it was confirmed that the SOF detector is capable of measuring thermal neutron flux as low as 105 n/cm2/s with sufficient accuracy. The SOF detector will be useful for phantom experiments with BNCT neutron fields from low-current accelerator-based neutron sources. PMID:25589504

  19. Formulation Optimization of Arecoline Patches

    PubMed Central

    Wu, Pao-Chu; Tsai, Pi-Ju; Lin, Shin-Chen; Huang, Yaw-Bin

    2014-01-01

    The response surface methodology (RSM) including polynomial equations has been used to design an optimal patch formulation with appropriate adhesion and flux. The patch formulations were composed of different polymers, including Eudragit RS 100 (ERS), Eudragit RL 100 (ERL) and polyvinylpyrrolidone K30 (PVP), plasticizers (PEG 400), and drug. In addition, using terpenes as enhancers could increase the flux of the drug. Menthol showed the highest enhancement effect on the flux of arecoline. PMID:24707220

  20. Neonates need tailored drug formulations

    PubMed Central

    Allegaert, Karel

    2013-01-01

    Drugs are very strong tools used to improve outcome in neonates. Despite this fact and in contrast to tailored perfusion equipment, incubators or ventilators for neonates, we still commonly use drug formulations initially developed for adults. We would like to make the point that drug formulations given to neonates need to be tailored for this age group. Besides the obvious need to search for active compounds that take the pathophysiology of the newborn into account, this includes the dosage and formulation. The dosage or concentration should facilitate the administration of low amounts and be flexible since clearance is lower in neonates with additional extensive between-individual variability. Formulations need to be tailored for dosage variability in the low ranges and also to the clinical characteristics of neonates. A specific focus of interest during neonatal drug development therefore is a need to quantify and limit excipient exposure based on the available knowledge of their safety or toxicity. Until such tailored vials and formulations become available, compounding practices for drug formulations in neonates should be evaluated to guarantee the correct dosing, product stability and safety. PMID:25254168

  1. Cryogenic Neutron Spectrometer Development

    SciTech Connect

    Niedermayr, T; Hau, I D; Friedrich, S; Burger, A; Roy, U N; Bell, Z W

    2006-03-08

    and the instrument is transportable. We are currently developing a fast neutron spectrometer with 0.1% energy resolution at 1 MeV neutron energy with an efficiency of > 1%. Our fast-neutron spectrometers use boron-based and {sup 6}LiF absorber crystals with Mo/Cu thermistors readout. They have achieved an energy resolution of 5.5 keV FWHM for 2.79 MeV deposited in {sup 10}B by thermal neutron capture (fig. 1), and 46 keV FWHM for fast (MeV) neutrons absorbed in {sup 6}LiF (fig. 2). Since the energy resolution does not depend on the neutron energy, we expect a similar energy resolution for MeV neutron energies. The response function is given simply by the cross section of the capture reaction, offset from zero by the Q-value of the capture reaction. This allows straightforward discrimination against gamma-events, most of which deposit less that Q{sub 6Li} = 4.79 MeV in the {sup 6}LiF absorber, and easy deconvolution of the neutron spectrum, since there is only a single capture reaction in {sup 6}Li and the spectrum is not affected by edge effects or geometric broadening. The current challenge for microcalorimeters is their necessarily small effective pixel area, {approx}1cm{sup 3} for neutron spectrometer pixels, and their slow decay time, {approx}10ms for neutron spectrometers. The pixel size is limited by the requirement for low Cabs for high energy resolution; the decay time is set by the intrinsically weak thermal coupling between materials at low temperatures. Both issues can be addressed by fabricating large detector arrays. This will enable high-precision neutron spectrometry with high statistics, such as simulated for Pu analysis in fig 3.

  2. Full Scale Coated Fiber Neutron Detector Measurements

    SciTech Connect

    Kouzes, Richard T.; Ely, James H.; Erikson, Luke E.; Kernan, Warnick J.; Stromswold, David C.; Woodring, Mitchell L.

    2010-03-17

    Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive neutron detection systems. The main reason for having neutron detection capability is to detect fission neutrons from plutonium. The currently deployed radiation portal monitors (RPMs) from Ludlum and Science Applications International Corporation (SAIC) use neutron detectors based upon 3He-filled gas proportional counters, which are the most common large neutron detector. There is a declining supply of 3He in the world, and thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and sensitivity to cargo-borne neutrons are being investigated. Four technologies have been identified as being currently commercially available, potential alternative neutron detectors to replace the use of 3He in RPMs. These technologies are: 1) Boron trifluoride (BF3)-filled proportional counters, 2) Boron-lined proportional counters, 3) Lithium-loaded glass fibers, and 4) Coated non-scintillating plastic fibers. Reported here are the results of tests of the full-scale 6Li/ZnS(Ag)-coated non-scintillating plastic fibers option. This testing measured the required performance for neutron detection efficiency and gamma ray rejection capabilities of a system manufactured by Innovative American Technology (IAT) and Saint Gobain, and is a follow-up report to an earlier one on a smaller prototype system.

  3. Lithium Loaded Glass Fiber Neutron Detector Tests

    SciTech Connect

    Ely, James H.; Erikson, Luke E.; Kouzes, Richard T.; Lintereur, Azaree T.; Stromswold, David C.

    2009-11-12

    Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive neutron detection systems. The main reason for having neutron detection capability is to detect fission neutrons from plutonium. The currently deployed radiation portal monitors (RPMs) from Ludlum and Science Applications International Corporation (SAIC) use neutron detectors based upon 3He-filled gas proportional counters, which are the most common large neutron detector. There is a declining supply of 3He in the world and, thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and sensitivity to cargo-borne neutrons are being investigated. Four technologies have been identified as being currently commercially available, potential alternative neutron detectors to replace the use of 3He in RPMs. Reported here are the results of tests of the lithium-loaded glass fibers option. This testing measured the neutron detection efficiency and gamma ray rejection capabilities of a small system manufactured by Nucsafe (Oak Ridge, TN).

  4. High energy neutron radiography

    SciTech Connect

    Gavron, A.; Morley, K.; Morris, C.; Seestrom, S.; Ullmann, J.; Yates, G.; Zumbro, J.

    1996-06-01

    High-energy spallation neutron sources are now being considered in the US and elsewhere as a replacement for neutron beams produced by reactors. High-energy and high intensity neutron beams, produced by unmoderated spallation sources, open potential new vistas of neutron radiography. The authors discuss the basic advantages and disadvantages of high-energy neutron radiography, and consider some experimental results obtained at the Weapons Neutron Research (WNR) facility at Los Alamos.

  5. An Evaluation of Grazing-Incidence Optics for Neutron Imaging

    NASA Technical Reports Server (NTRS)

    Gubarev, M. V.; Ramsey, B. D.; Engelhaupt, D. E.; Burgess, J.; Mildner, D. F. R.

    2007-01-01

    The focusing capabilities of neutron imaging optic based on the Wolter-1 geometry have been successfully demonstrated with a beam of long wavelength neutrons with low angular divergence.. A test mirror was fabricated using an electroformed nickel replication process at Marshall Space Flight Center. The neutron current density gain at the focal spot of the mirror is found to be at least 8 for neutron wavelengths in the range from 6 to 20 A. Possible applications of the optics are briefly discussed.

  6. Personnel neutron dosimetry at Department of Energy facilities

    SciTech Connect

    Brackenbush, L.W.; Endres, G.W.R.; Selby, J.M.; Vallario, E.J.

    1980-08-01

    This study assesses the state of personnel neutron dosimetry at DOE facilities. A survey of the personnel dosimetry systems in use at major DOE facilities was conducted, a literature search was made to determine recent advances in neutron dosimetry, and several dosimetry experts were interviewed. It was concluded that personnel neutron dosimeters do not meet current needs and that serious problems exist now and will increase in the future if neutron quality factors are increased and/or dose limits are lowered.

  7. Continuum quasiparticle random-phase approximation for astrophysical direct neutron capture reactions on neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Matsuo, Masayuki

    2015-03-01

    I formulate a many-body theory to calculate the cross section of direct radiative neutron capture reaction by means of the Hartree-Fock-Bogoliubov mean-field model and the continuum quasiparticle random-phase approximation (QRPA). A focus is put on very-neutron-rich nuclei and low-energy neutron kinetic energy in the range from 1 keV to several MeV, which is relevant to the rapid neutron capture process of nucleosynthesis. I begin with the photoabsorption cross section and the E 1 strength function. Next, in order to apply the reciprocity theorem, I decompose the cross section into partial cross sections corresponding to different channels of one- and two-neutron emission decays of photo-excited states. A numerical example is shown for the photo-absorption of 142Sn and the neutron capture of 141Sn .

  8. 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.

  9. Calculations of neutron spectra after neutron neutron scattering

    NASA Astrophysics Data System (ADS)

    Crawford, B. E.; Stephenson, S. L.; Howell, C. R.; Mitchell, G. E.; Tornow, W.; Furman, W. I.; Lychagin, E. V.; Muzichka, A. Yu; Nekhaev, G. V.; Strelkov, A. V.; Sharapov, E. I.; Shvetsov, V. N.

    2004-09-01

    A direct neutron-neutron scattering length, ann, measurement with the goal of 3% accuracy (0.5 fm) is under preparation at the aperiodic pulsed reactor YAGUAR. A direct measurement of ann will not only help resolve conflicting results of ann by indirect means, but also in comparison to the proton-proton scattering length, app, shed light on the charge-symmetry of the nuclear force. We discuss in detail the analysis of the nn-scattering data in terms of a simple analytical expression. We also discuss calibration measurements using the time-of-flight spectra of neutrons scattered on He and Ar gases and the neutron activation technique. In particular, we calculate the neutron velocity and time-of-flight spectra after scattering neutrons on neutrons and after scattering neutrons on He and Ar atoms for the proposed experimental geometry, using a realistic neutron flux spectrum—Maxwellian plus epithermal tail. The shape of the neutron spectrum after scattering is appreciably different from the initial spectrum, due to collisions between thermal-thermal and thermal-epithermal neutrons. At the same time, the integral over the Maxwellian part of the realistic scattering spectrum differs by only about 6 per cent from that of a pure Maxwellian nn-scattering spectrum.

  10. 40 CFR 152.43 - Alternate formulations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... PESTICIDE REGISTRATION AND CLASSIFICATION PROCEDURES Registration Procedures § 152.43 Alternate formulations... label text of the alternate formulation product must be identical to that of the basic formulation....