Search Results - (Author, Cooperation:G. Cooper)
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1Latest Papers from Table of Contents or Articles in PressMorphometric analysis of slipface processes of an aeolian dune: Implications for grain-flow dynamicsStaff View
Publication Date: 2018-01-22Publisher: Wiley-BlackwellPrint ISSN: 0037-0746Electronic ISSN: 1365-3091Topics: GeosciencesPublished by: -
2Latest Papers from Table of Contents or Articles in PressP. Jenniskens ; M. D. Fries ; Q. Z. Yin ; M. Zolensky ; A. N. Krot ; S. A. Sandford ; D. Sears ; R. Beauford ; D. S. Ebel ; J. M. Friedrich ; K. Nagashima ; J. Wimpenny ; A. Yamakawa ; K. Nishiizumi ; Y. Hamajima ; M. W. Caffee ; K. C. Welten ; M. Laubenstein ; A. M. Davis ; S. B. Simon ; P. R. Heck ; E. D. Young ; I. E. Kohl ; M. H. Thiemens ; M. H. Nunn ; T. Mikouchi ; K. Hagiya ; K. Ohsumi ; T. A. Cahill ; J. A. Lawton ; D. Barnes ; A. Steele ; P. Rochette ; K. L. Verosub ; J. Gattacceca ; G. Cooper ; D. P. Glavin ; A. S. Burton ; J. P. Dworkin ; J. E. Elsila ; S. Pizzarello ; R. Ogliore ; P. Schmitt-Kopplin ; M. Harir ; N. Hertkorn ; A. Verchovsky ; M. Grady ; K. Nagao ; R. Okazaki ; H. Takechi ; T. Hiroi ; K. Smith ; E. A. Silber ; P. G. Brown ; J. Albers ; D. Klotz ; M. Hankey ; R. Matson ; J. A. Fries ; R. J. Walker ; I. Puchtel ; C. T. Lee ; M. E. Erdman ; G. R. Eppich ; S. Roeske ; Z. Gabelica ; M. Lerche ; M. Nuevo ; B. Girten ; S. P. Worden
American Association for the Advancement of Science (AAAS)
Published 2012Staff ViewPublication Date: 2012-12-22Publisher: American Association for the Advancement of Science (AAAS)Print ISSN: 0036-8075Electronic ISSN: 1095-9203Topics: BiologyChemistry and PharmacologyComputer ScienceMedicineNatural Sciences in GeneralPhysicsPublished by: -
3Latest Papers from Table of Contents or Articles in PressStaff View
Publication Date: 2018-03-07Publisher: Institute of Physics Publishing (IOP)Electronic ISSN: 1748-0221Topics: PhysicsPublished by: -
4Latest Papers from Table of Contents or Articles in PressRoberts, B. S., Hardigan, A. A., Moore, D. E., Ramaker, R. C., Jones, A. L., Fitz-Gerald, M. B., Cooper, G. M., Wilcox, C. M., Kimberly, R. P., Myers, R. M.
The American Association for Cancer Research (AACR)
Published 2018Staff ViewPublication Date: 2018-05-02Publisher: The American Association for Cancer Research (AACR)Print ISSN: 1078-0432Electronic ISSN: 1557-3265Topics: MedicinePublished by: -
5Articles: DFG German National LicensesRuiz, C. L. ; Leeper, R. J. ; Schmidlapp, F. A. ; Cooper, G. ; Malbrough, D. J.
[S.l.] : American Institute of Physics (AIP)
Published 1992Staff ViewISSN: 1089-7623Source: AIP Digital ArchiveTopics: PhysicsElectrical Engineering, Measurement and Control TechnologyNotes: Progress in Z-pinch experiments at Sandia's Saturn facility have underscored a need for an absolute yield measurement for DD fusion neutrons. The technique chosen for making this absolute yield measurement was neutron activation of indium metal samples. To calibrate the technique, a 175-keV deuteron beam was allowed to impinge on a 3.0-μm-thick erbium deuteride target, producing neutrons through the 2H(d,n)3He fusion reaction. The neutron flux produced at 0° and incident on nominal 5-g indium samples was determined by the associated particle method. This method employed protons measured from the 2H(d,p)3H reaction to infer the neutron flux produced. After neutron irradiation, the activity of the indium samples was measured with a Ge gamma-ray detector. The total activity of the metastable state 115mIn (336.23 keV) was measured, compared with the total incident flux, and a calibration factor (indium counts/neutron/gram of indium) determined. For completeness, a calibration factor for DT neutrons from the 3H(d,n)4He fusion reaction was also obtained through the measured activity of the metastable state 114mIn(190.29 keV). The experiment and the measured calibration factors for both reactions are described in the paper.Type of Medium: Electronic ResourceURL: -
6Articles: DFG German National LicensesCollopy, M. T. ; Carpenter, P. ; Harmon, C. D. ; Vandenberg, J. ; Cooper, G. W. ; Ruiz, C. L. ; Reyes, P. ; Stygar, W. A. ; Schmidlapp, A. ; Malbrough, D. J. ; Becker, R.
[S.l.] : American Institute of Physics (AIP)
Published 1992Staff ViewISSN: 1089-7623Source: AIP Digital ArchiveTopics: PhysicsElectrical Engineering, Measurement and Control TechnologyNotes: We have measured the efficiency (tracks per incident neutron) of pure CR-39 for detecting DD and DT neutrons. Neutrons having average energies of 2.9 MeV (DD) and 14.8 MeV (DT) were produced by a 200-keV electrostatic accelerator and the neutron yields were measured using the associated particle counting technique. All CR-39 samples irradiated by DD or DT neutrons were etched for 2 h in a 70°, 6.25-N(underbar) NaOH bath. For bare CR-39, the efficiencies for detecting 2.9- and 14.8-MeV neutrons were found to be (1.3±0.4)×10−4 and (5.0±1.8)×10−5, respectively. We also investigated using CR-39 and polyimide as proton radiators. For detecting 2.9-MeV neutrons, the radiators had no significant effect on efficiency; but for detecting 14.8-MeV neutrons the polyimide radiator increased the efficiency to (7.8±2.8)×10−5.Type of Medium: Electronic ResourceURL: -
7Articles: DFG German National LicensesLapin, S. N. ; Cooper, G. W. ; Davis, L. ; Bailey, J. E. ; Stygar, W. A. ; Carlson, A. ; Reyes, P.
[S.l.] : American Institute of Physics (AIP)
Published 1992Staff ViewISSN: 1089-7623Source: AIP Digital ArchiveTopics: PhysicsElectrical Engineering, Measurement and Control TechnologyNotes: The CR-39/range-filter technique measures ion energy by determining the maximum filter thickness which ions can penetrate. CR-39 located behind the filter records the ions. This method is used to measure peak voltage in pulsed power accelerators. We investigated range and straggling effects in this diagnostic by exposing it to 8- and 15-MeV protons for both Al and Ta filters. The range agreed with published values to better than ±6%. The range straggling decreased for higher incident ion energy and lower atomic number, as expected, although there were differences up to a factor of 1.7 between the experimental values and predictions. The dependence of the track diameter distribution on ion energy enabled us to establish a signature which is characteristic of ions which penetrate a filter, via straggling. These results can be used to evaluate the errors present when this diagnostic is used to measure accelerator voltage.Type of Medium: Electronic ResourceURL: -
8Articles: DFG German National LicensesNash, T. J. ; Derzon, M. S. ; Chandler, G. A. ; Leeper, R. ; Fehl, D. ; Lash, J. ; Ruiz, C. ; Cooper, G. ; Seaman, J. F. ; McGurn, J. ; Lazier, S. ; Torres, J. ; Jobe, D. ; Gilliland, T. ; Hurst, M. ; Mock, R. ; Ryan, P. ; Nielsen, D. ; Armijo, J. ; McKenney, J. ; Hawn, R. ; Hebron, D.
[S.l.] : American Institute of Physics (AIP)
Published 1999Staff ViewISSN: 1089-7674Source: AIP Digital ArchiveTopics: PhysicsNotes: In the concept of the dynamic hohlraum an imploding Z pinch is optically thick to its own radiation. Radiation may be trapped inside the pinch to give a radiation temperature inside the pinch greater than that outside the pinch. The radiation is typically produced by colliding an outer Z-pinch liner onto an inner liner. The collision generates a strongly radiating shock, and the radiation is trapped by the outer liner. As the implosion continues after the collision, the radiation temperature may continue to increase due to ongoing PdV (pressure times change in volume) work done by the implosion. In principal, the radiation temperature may increase to the point at which the outer liner burns through, becomes optically thin, and no longer traps the radiation. One application of the dynamic hohlraum is to drive an ICF (inertial confinement fusion) pellet with the trapped radiation field. Members of the dynamic hohlraum team at Sandia National Labs have used the pulsed power driver Z (20 MA, 100 ns) to create a dynamic hohlraum with temperature linearly ramping from 100 to 180 eV over 5 ns. On this shot zp214 a nested tungsten wire array of 4 and 2 cm diam with masses of 2 and 1 mg imploded onto a 2.5 mg plastic annulus at 5 mm diam. The current return can on this shot was slotted. It is likely the radiation temperature may be increased to over 200 eV by stabilizing the pinch with a solid current return can. A current return can with nine slots imprints nine filaments onto the imploding pinch. This degrades the optical trapping and the quality of the liner collision. A 1.6 mm diam capsule situated inside this dynamic hohlraum of zp214 would see 15 kJ of radiation impinging on its surface before the pinch itself collapses to a 1.6 mm diam. Dynamic hohlraum shots including pellets were scheduled to take place on Z in September of 1998. © 1999 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
9Articles: DFG German National LicensesNash, T. J. ; Derzon, M. S. ; Chandler, G. A. ; Fehl, D. L. ; Leeper, R. J. ; Porter, J. L. ; Spielman, R. B. ; Ruiz, C. ; Cooper, G. ; McGurn, J. ; Hurst, M. ; Jobe, D. ; Torres, J. ; Seaman, J. ; Struve, K. ; Lazier, S. ; Gilliland, T. ; Ruggles, L. A. ; Simpson, W. A. ; Adams, R. ; Seaman, J. A. ; Wenger, D. ; Nielsen, D. ; Riley, P. ; French, R.
[S.l.] : American Institute of Physics (AIP)
Published 2001Staff ViewISSN: 1089-7623Source: AIP Digital ArchiveTopics: PhysicsElectrical Engineering, Measurement and Control TechnologyNotes: The 100 ns, 20 MA pinch-driver Z is surrounded by an extensive set of diagnostics. There are nine radial lines of sight set at 12° above horizontal and each of these may be equipped with up to five diagnostic ports. Instruments routinely fielded viewing the pinch from the side with these ports include x-ray diode arrays, photoconducting detector arrays, bolometers, transmission grating spectrometers, time-resolved x-ray pinhole cameras, x-ray crystal spectrometers, calorimeters, silicon photodiodes, and neutron detectors. A diagnostic package fielded on axis for viewing internal pinch radiation consists of nine lines of sight. This package accommodates virtually the same diagnostics as the radial ports. Other diagnostics not fielded on the axial or radial ports include current B-dot monitors, filtered x-ray scintillators coupled by fiber optics to streak cameras, streaked visible spectroscopy, velocity interferometric system for any reflector, bremsstrahlung cameras, and active shock breakout measurement of hohlraum temperature. The data acquisition system is capable of recording up to 500 channels and the data from each shot is available on the Internet. A major new diagnostic presently under construction is the BEAMLET backlighter. We will briefly describe each of these diagnostics and present some of the highest-quality data from them. © 2001 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
10Articles: DFG German National LicensesStaff View
ISSN: 1089-7623Source: AIP Digital ArchiveTopics: PhysicsElectrical Engineering, Measurement and Control TechnologyNotes: A direct nuclear activation diagnostic for the measurement of the kinetic energy of deuterium ions in the energy range of 1–3 MeV has been successfully developed. This diagnostic is based on the fact that the ratio of two different thick-target yields which are generated by the same incident ion species can be a sensitive function of incident ion energy. Targets for this diagnostic are made of α-boron nitride (BN) and use the two reactions: 10B(d,n) 11C(β+) and 14N(d,n) 15O(β+). The ratio of thick-target yields depends only on the deuterium ion energy and is independent of ion fluence and detector efficiency. The calibrated diagnostic was then fielded to measure the voltage in a plasma opening switch (POS). Electrical measurements of the POS voltage and the voltage inferred from the BN nuclear activation diagnostic were in good agreement. © 1999 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
11Articles: DFG German National LicensesKilkenny, J. D. ; Cable, M. D. ; Clower, C. A. ; Hammel, B. A. ; Karpenko, V. P. ; Kauffman, R. L. ; Kornblum, H. N. ; MacGowan, B. J. ; Olson, W. ; Orzechowski, T. J. ; Phillion, D. W. ; Tietbohl, G. L. ; Trebes, J. E. ; Chrien, B. ; Failor, B. ; Hauer, A. ; Hockaday, R. ; Oertel, J. ; Watt, R. ; Ruiz, C. ; Cooper, G. ; Hebron, D. ; Leeper, R. ; Porter, J. ; Knauer, J.
[S.l.] : American Institute of Physics (AIP)
Published 1995Staff ViewISSN: 1089-7623Source: AIP Digital ArchiveTopics: PhysicsElectrical Engineering, Measurement and Control TechnologyNotes: A tentative schedule of experiments for the ignition campaign on the National Ignition Facility (NIF) has been developed. These experiments will be used to validate beam pointing and balance, to tune time history and symmetry of drive of NIF hohlraums, and to implode subignition and igniting targets. The initial target diagnostics are designed to validate beam pointing and to demonstrate the properties of the hohlraums. © 1995 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
12Articles: DFG German National LicensesEvans, C. Brad ; Cooper, G. W. ; Ruiz, C. L. ; Leeper, R. J.
[S.l.] : American Institute of Physics (AIP)
Published 1995Staff ViewISSN: 1089-7623Source: AIP Digital ArchiveTopics: PhysicsElectrical Engineering, Measurement and Control TechnologyNotes: An indirect nuclear activation diagnostic was developed to measure the proton fluence onto a thick target of lithium metal located in the diode region of pulsed power accelerators. This diagnostic uses the nuclear reaction sequence 7Li(p,γ)8Be→141Pr(γ,n)140Pr(β+) to relate the proton fluence to induced 140Pr activity. This diagnostic was calibrated using a Van de Graaff accelerator. Energetic protons were focused onto a thick lithium target driving the 7Li(p,γ)8Be reaction. The resulting prompt gamma rays activated a secondary 141Pr target via the reaction 141Pr(γ,n)140Pr(β+). A NaI gamma-gamma coincidence detector system was used to measure the induced 140Pr activity as a function of proton energy and proton fluence. These data yielded a calibration curve for proton energies ranging from 2 to 12 MeV. Since deuterium impurities can interfere with this diagnostic by driving the reaction sequence 7Li(d,n)8Be→141Pr(n,2n)140Pr, a similar calibration experiment was conducted using deuterium ions. These data yielded a correction factor that can be used to determine the deuterium contribution to the 140Pr activity, providing that the deuterium beam fraction is known. © 1995 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
13Articles: DFG German National LicensesLeeper, R. J. ; Chandler, G. A. ; Cooper, G. W. ; Derzon, M. S. ; Fehl, D. L. ; Hebron, D. E. ; Moats, A. R. ; Noack, D. D. ; Porter, J. L. ; Ruggles, L. E. ; Ruiz, C. L. ; Torres, J. A.
[S.l.] : American Institute of Physics (AIP)
Published 1997Staff ViewISSN: 1089-7623Source: AIP Digital ArchiveTopics: PhysicsElectrical Engineering, Measurement and Control TechnologyNotes: A review of recent progress on the design of a diagnostic system proposed for ignition target experiments on the National Ignition Facility (NIF) will be presented. This diagnostic package contains an extensive suite of optical, x ray, gamma ray, and neutron diagnostics that enable measurements of the performance of both direct and indirect driven NIF targets. The philosophy used in designing all of the diagnostics in the set has emphasized redundant and independent measurement of fundamental physical quantities relevant to the operation of the NIF target. A unique feature of these diagnostics is that they are being designed to be capable of operating in the high radiation, electromagnetic pulse, and debris backgrounds expected on the NIF facility. The diagnostic system proposed can be categorized into three broad areas: laser characterization, hohlraum characterization, and capsule performance diagnostics. The operating principles of a representative instrument from each class of diagnostic employed in this package will be summarized and illustrated with data obtained in recent prototype diagnostic tests. © 1997 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
14Articles: DFG German National LicensesHumphries, S. ; Burkhart, C. ; Coffey, S. ; Cooper, G. ; Len, L. K. ; Savage, M. ; Woodall, D. M. ; Rutkowski, H. ; Oona, H. ; Shurter, R.
[S.l.] : American Institute of Physics (AIP)
Published 1986Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Experimental results are presented on a method for extracting well-focused ion beams from plasma sources with time-varying properties. An electrostatic grid was used to stop the flow of plasma electrons so that only ions entered the extraction gap. In this case, ion flow in the gap was controlled by space-charge effects as it would be with a thermionic ion source. Constant extracted current was observed even with large variations of source flux. An insulator spark source and a metal-vapor vacuum arc were used to generate pulsed ion beams. With a hydrocarbon spark, current densities of 44 mA/cm2 were achieved at 20-kV extractor voltage for an 8-μs pulse. With an aluminum-vapor arc, a current density of 15 mA/cm2 (0.3 A total) was measured for a 50-μs pulse.Type of Medium: Electronic ResourceURL: -
15Articles: DFG German National LicensesDerzon, M. ; Nash, T. ; Chandler, G. ; Cooper, G. ; Fehl, D. ; Hall, C. ; Lash, J. ; Leeper, R. ; McGuire, E. ; Mock, R. ; Olsen, R. ; Olson, C. ; Rochau, G. E. ; Rochau, G. A. ; Ruiz, C. ; Seamen, J. ; Slutz, S. ; Stygar, W. ; Sweeney, M. A.
[S.l.] : American Institute of Physics (AIP)
Published 1999Staff ViewISSN: 1089-7623Source: AIP Digital ArchiveTopics: PhysicsElectrical Engineering, Measurement and Control TechnologyNotes: High-energy photons and electrons on the Sandia National Laboratories "Z" accelerator, a z-pinch device, will deposit energy into a capsule and fuel; this may create a potential preheat problem for inertial confinement infusion (ICF). In this article we discuss heating of the capsule and fuel by high-energy photons and electrons. The fuel is heated to 〈2 eV, in a time-integrated sense, on Z by these particles. Because peak implosion occurs at the peak in the soft x-ray emission on Z, the heating at times of interest is reduced roughly an order of magnitude to ∼0.2 eV for times of interest and fuel preheat from this mechanism is concluded to be small. These estimates are generated from time-integrated bremsstrahlung measurements. The uncertainty in the heating is high because the electron spectrum is not known directly, but inferred. In addition, the influence of photons and electrons at energies between 5 and 60 keV is not known. Given the uncertainties at this point, we do not know the impact on the feasibility of internal dynamic hohlraums for a z-pinch-driven ICF implosion. We discuss these issues and suggest directions for further study. © 1999 American Institute of Physics.Type of Medium: Electronic ResourceURL: -
16Articles: DFG German National LicensesLeeper, R. J. ; Stygar, W. A. ; Maenchen, J. ; Ruiz, C. L. ; Kensek, R. P. ; Johnson, D. J. ; Lockner, T. R. ; Bailey, J. ; Cooper, G. ; Lee, J. R. ; Mehlhorn, T. A. ; Mix, L. P. ; Stinnett, R. W.
[S.l.] : American Institute of Physics (AIP)
Published 1988Staff ViewISSN: 1089-7623Source: AIP Digital ArchiveTopics: PhysicsElectrical Engineering, Measurement and Control TechnologyNotes: A review of the diagnostics used at Sandia National Laboratories to measure the parameters of intense proton and lithium beams generated on the PBFA-II accelerator will be presented. These diagnostics consist of several types, namely: Kα x-ray pinhole cameras, a multiframe dE/dx ion pinhole camera, a p-i-n array ion pinhole camera, Thomson parabola spectrographs, a Rutherford magnetic spectrograph, plasma visible spectroscopy, and several nuclear activation diagnostics. These components, when taken together, enable a rather thorough description of the 5-MV, 10-TW ion beams presently being produced. A unique feature of these diagnostics is that they are capable of operating in hard (several MeV) x-ray bremsstrahlung backgrounds of some 109–1010 rad/s. Details of each diagnostic, its integration, data reduction procedures, and recent PBFA-II data will be discussed.Type of Medium: Electronic ResourceURL: -
17Articles: DFG German National LicensesHumphries, S. ; Coffey, S. ; Savage, M. ; Len, L. K. ; Cooper, G. W. ; Woodall, D. M.
[S.l.] : American Institute of Physics (AIP)
Published 1985Staff ViewISSN: 1089-7550Source: AIP Digital ArchiveTopics: PhysicsNotes: Experiments are described on a plasma cathode with biased grids to prevent entry of ions into the electron extraction gap. The cathode has potential applications to the generation of high-current pulsed electron beams. Operation at 20 A/cm2 is theoretically possible. The source combines the low average power consumption of a plasma cathode with many of the attractive features of thermionic cathodes, such as space-charge-limited extractor gap electron flow, fast turn-on, and no diode closure. Initial experiments are reported at the 2 A/cm2 level for pulse lengths to 160 μs.Type of Medium: Electronic ResourceURL: -
18Articles: DFG German National LicensesCooper, G. R. ; Petrie, G. ; Smith, A. D. N. ; Sowton, M. ; Atkinson, K. B.
Oxford, UK : Blackwell Publishing Ltd
Published 1969Staff ViewISSN: 1477-9730Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: Architecture, Civil Engineering, SurveyingNotes: The International Society for Photogrammetry held the Xlth International Congress at Lausanne during July 1968. The authors review the activities of five of the seven I.S.P. Commissions.Type of Medium: Electronic ResourceURL: -
19Articles: DFG German National LicensesStaff View
ISSN: 1365-2044Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: MedicineNotes: Sixty unpremedicated patients undergoing dilatation and curettage were allocated randomly to receive one of three inhalational agents (halothane, enflurane or isoflurane) to supplement 67% nitrous oxide in oxygen after induction of anaesthesia with methohexitone. Recovery was assessed by the time patients took to open their eyes, to give their correct date of birth, to regain their pre-operative level of manipulative skill with a children's postbox toy, and by comparing pre-operative and postoperative performance of a paper and pencil test (the p-deletion test). There was no difserence in the time to open eyes or to regain their pre-operative score with the postbox whether the patients received halothane, enflurune or isoflurane. Patients in the isoflurane group took longer than patients in the enflurane group to give their correct date of birth, but they performed better in the p-deletion test postoperatively, completing more lines with the same number of errors. Patients receiving enflurane committed more errors postoperatively in the p-deletion test. The incidence of complications was low and was not influenced by the choice of inhalational agent.Type of Medium: Electronic ResourceURL: -
20Articles: DFG German National LicensesStaff View
ISSN: 1365-2044Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: MedicineType of Medium: Electronic ResourceURL: