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Determination of ocean/atmosphere carbon dioxide flux within OMP survey area. Final technical progress report, June, 1 1993--May 31, 1995

Description: Determination of the net flux of atmospheric CO{sub 2} with the ocean at the continental margin is one of the three principal goals of the Ocean Margins Program. The work reported here represents the initial phase of that determination, as carried out during two cruises within the OMP survey area in 1993 and 1994. The interannual variability was addressed through the occupation of hydrographic stations of nearly identical location one year apart, while the spatial variability in the air-sea PCO{sub 2} difference (ApCO{sub 2}), representing the driving force for net CO{sub 2} flux, was addressed during a survey of much of the continental shelf between the survey area off North Carolina and Georges Bank. Not addressed by the initial cruises was the seasonal variability of the net CO{sub 2} flux, since both scoping cruises were mounted during the same season of the respective years.
Date: October 17, 1995
Creator: Chipman, D. W. & Takahashi, T.
Partner: UNT Libraries Government Documents Department

Development of gas chromatographic system for dissolved organic carbon analysis in seawater

Description: During the first six months of this two-year grant, we have completed the construction of the analytical portion of a prototype gas chromatograph-based system for the analysis of dissolved organic carbon in seawater. We also have begun testing the procedures to be used to cryogenically concentrate and transfer carbon dioxide from the oxidizing atmosphere of the high-temperature furnace into the reducing hydrogen carrier gas of the gas chromatograph. During the second half of the first year, we will construct the high-temperature catalytic oxidation furnace and test the entire system on laboratory-prepared aqueous solutions of various organic compounds. Also during this period, we will take part in an initial scoping study within the Cape Hatteras field area on board the R/V Gyre. This study will involve both the collection of samples of seawater for organic and inorganic carbon analysis and the measurement of surface-water pCO[sub 2].
Date: December 1, 1992
Creator: Chipman, D.W. & Takahashi, T.
Partner: UNT Libraries Government Documents Department

Development of gas chromatographic system for dissolved organic carbon analysis in seawater. Annual progress report

Description: During the first six months of this two-year grant, we have completed the construction of the analytical portion of a prototype gas chromatograph-based system for the analysis of dissolved organic carbon in seawater. We also have begun testing the procedures to be used to cryogenically concentrate and transfer carbon dioxide from the oxidizing atmosphere of the high-temperature furnace into the reducing hydrogen carrier gas of the gas chromatograph. During the second half of the first year, we will construct the high-temperature catalytic oxidation furnace and test the entire system on laboratory-prepared aqueous solutions of various organic compounds. Also during this period, we will take part in an initial scoping study within the Cape Hatteras field area on board the R/V Gyre. This study will involve both the collection of samples of seawater for organic and inorganic carbon analysis and the measurement of surface-water pCO{sub 2}.
Date: December 1, 1992
Creator: Chipman, D. W. & Takahashi, T.
Partner: UNT Libraries Government Documents Department

Extremely Fast Acceleration of Cosmic Rays in a Supernova Remnant

Description: Galactic cosmic rays (CRs) are widely believed to be accelerated by shock waves associated with the expansion of supernova ejecta into the interstellar medium. A key issue in this long-standing conjecture is a theoretical prediction that the interstellar magnetic field can be substantially amplified at the shock of a young supernova remnant (SNR) through magnetohydrodynamic waves generated by cosmic rays. Here we report a discovery of the brightening and decay of X-ray hot spots in the shell of theSNRRXJ1713.723946 on a one-year timescale. This rapid variability shows that the X-rays are produced by ultrarelativistic electrons through a synchrotron process and that electron acceleration does indeed take place in a strongly magnetized environment, indicating amplification of the magnetic field by a factor of more than 100. The X-ray variability also implies that we have witnessed the ongoing shock-acceleration of electrons in real time. Independently, broadband X-ray spectrometric measurements of RXJ1713.723946 indicate that electron acceleration proceeds in the most effective ('Bohm-diffusion') regime. Taken together, these two results provide a strong argument for acceleration of protons and nuclei to energies of 1 PeV (10{sup 15} eV) and beyond in young supernova remnants.
Date: October 23, 2007
Creator: Uchiyama, Y.; Aharonian, F. A.; Tanaka, T.; Takahashi, T. & Maeda, Y.
Partner: UNT Libraries Government Documents Department

Transient Tracers in the Oceans (TTO) - hydrographic data and carbon dioxide systems with revised carbon chemistry data

Description: The Transient Tracers in the Ocean (TTO) study was an experiment to investigate ocean mixing as deduced from the distribution of radiochemical tracers introduced into the atmosphere and subsequently into the oceans during the 1958-1962 nuclear bomb tests. The results of this study together with knowledge about the chemistry of oceanic CO{sub 2} can be used to help understand oceanic uptake of fossil fuel CO{sub 2}. The experiment lasted 4 years and consisted of the following parts: (1) (1981); (3) laboratory analysis (1982); and (4) completion, data analysis, and reporting (1983). Shipboard measurements were published by the Scripps Physical and Chemical Oceanographic Data Facility as the T.T.O. Preliminary Hydrographic Data Reports Vols. I-IV. Recently, revisions to some of the previously reported measurements have been made and estimates of total CO{sub 2} have been calculated.
Date: September 1, 1986
Creator: Brewer, P.G.; Takahashi, T. & Williams, R.T.
Partner: UNT Libraries Government Documents Department

Measurements of the total CO[sub 2] concentration and partial pressure of CO[sub 2] in seawater during WOCE expeditions in the South Pacific Ocean

Description: During the first year of the grant, we participated in three WOCE expeditions (a total of 152 days at sea) in the South Pacific Ocean, and the field phase of the proposed investigation has been successfully completed. The total CO[sub 2] concentration and pCO[sub 2] were determined at sea in 4419 water samples collected at 422 stations. On the basis of the shipboard analyses of SIO Reference Solutions for CO, and a comparison with the results of previous expeditions, the overall precision of our total CO[sub 2] determinations is estimated to be about [plus minus]2 uM/kg. The deep water data indicate that there is a CO[sub 2] maximum centered about 2600 meters deep. This appears to represent a southward return flow from the North Pacific. The magnitude and distribution of the CO, maximum observed along the 135.0[degrees]W meridian differ from those observed along the 150.5[degrees]W meridian due to Tuamotu Archipelago, a topographic high which interferes with the southward return flow. The surface water pCO[sub 2] data indicate that the South Pacific sub-tropical gyre water located between about 15[degrees]S and 50[degrees]S is a sink for atmospheric CO[sub 2].
Date: June 29, 1993
Creator: Takahashi, T.; Goddard, J. G.; Chipman, D. W. & Rubin, S. I.
Partner: UNT Libraries Government Documents Department

Measurements of the total CO{sub 2} concentration and partial pressure of CO{sub 2} in seawater during WOCE expeditions in the South Pacific Ocean. Progress report, [January 1, 1993--December 31, 1993]

Description: During the first year of the grant, we participated in three WOCE expeditions (a total of 152 days at sea) in the South Pacific Ocean, and the field phase of the proposed investigation has been successfully completed. The total CO{sub 2} concentration and pCO{sub 2} were determined at sea in 4419 water samples collected at 422 stations. On the basis of the shipboard analyses of SIO Reference Solutions for CO, and a comparison with the results of previous expeditions, the overall precision of our total CO{sub 2} determinations is estimated to be about {plus_minus}2 uM/kg. The deep water data indicate that there is a CO{sub 2} maximum centered about 2600 meters deep. This appears to represent a southward return flow from the North Pacific. The magnitude and distribution of the CO, maximum observed along the 135.0{degrees}W meridian differ from those observed along the 150.5{degrees}W meridian due to Tuamotu Archipelago, a topographic high which interferes with the southward return flow. The surface water pCO{sub 2} data indicate that the South Pacific sub-tropical gyre water located between about 15{degrees}S and 50{degrees}S is a sink for atmospheric CO{sub 2}.
Date: June 29, 1993
Creator: Takahashi, T.; Goddard, J. G.; Chipman, D. W. & Rubin, S. I.
Partner: UNT Libraries Government Documents Department

Measurements of carbon dioxide in the Southern Ocean along the WOCE S-4 section. Annual progress report

Description: During the fist year of this two-year grant, we have completed the data acquisition phase at sea along the WOCE-S4 section located along 67{degree}S between 73{degree}W and 172{degree}E in the Pacific sector of the Southern Ocean. The expedition was carried out aboard the Russian Research Ship ``Akademik IOFFE`` in the period February 14 through April 6, 1992. The total CO{sub 2} concentration and pCO{sub 2} in a total of about 1290 water samples were determined using a coulometer for total CO{sub 2} and an equilibrator/gas chromatograph system for pCO{sub 2}. Surface water samples were analyzed at all the 112 hydrographic stations occupied. Complete or partial profiles were obtained at 58 stations. In addition, a total of 172 determinations were made at sea for 62 bottles of the Standard Reference Solution.
Date: August 1, 1992
Creator: Chipman, D. W.; Rubin, S. I. & Takahashi, T.
Partner: UNT Libraries Government Documents Department

Microstructure and density changes of Li2O during irradiation in BEATRIX-II, Phase 1

Description: BEATRIX-II, Phase 1 was an in situ tritium recovery experiment carried out on Li{sub 2}O to lithium burnups in excess of 4%. Solid Li{sub 2}O specimens were irradiated under a temperature gradient in the range from 700 K at the outer diameter to 1,270 K at the center. A ring specimen of Li{sub 2}O operated at a nearly uniform temperature with the capability of changing temperature in the range from 780 to 920 K. Li{sub 2}O single crystals having two different {sup 6}Li enrichments (0.07 and 1.8 at%) were irradiated at 650 K in nonvented canisters. Microstructures of these specimens, before and after irradiation, were investigated using optical and scanning electron microscopy. Substantial microstructure change was found to have occurred in the solid specimen during irradiation and this change was characterized by the development of large columnar grains, lenticular porosity and a center void. The development of columnar grains and the formation of the center void was attributed to the migration of lenticular pores up the thermal gradient by a vaporization/condensation process. Morphological changes on fracture surfaces were observed both for the polycrystalline (solid and ring) specimens and the single crystal specimens. Measurements of density were used to further characterize the effects of irradiation on the open and closed porosity distributions in all the specimens. Although extensive microstructural and density changes occurred during irradiation, these changes had no significant impact on the integrity of Li{sub 2}O during irradiation, and therefore these results support the use of Li{sub 2}O as fusion solid breeders.
Date: June 1, 1994
Creator: Takahashi, T.; Noda, K.; Slagle, O. D. & Hobbs, F. D.
Partner: UNT Libraries Government Documents Department

Suzaku Observation of TeV Blazar the 1ES 1218+304: Clues on Particle Acceleration in an Extreme TeV Blazar

Description: We observed the TeV blazar 1ES 1218+304 with the X-ray astronomy satellite Suzaku in May 2006. At the beginning of the two-day continuous observation, we detected a large flare in which the 5-10 keV flux changed by a factor of {approx}2 on a timescale of 5 x 10{sup 4} s. During the flare, the increase in the hard X-ray flux clearly lagged behind that observed in the soft X-rays, with the maximum lag of 2.3 x 10{sup 4} s observed between the 0.3?1 keV and 5?10 keV bands. Furthermore we discovered that the temporal profile of the flare clearly changes with energy, being more symmetric at higher energies. From the spectral fitting of multi-wavelength data assuming a one-zone, homogeneous synchrotron self-Compton model, we obtain B {approx} 0.047 G, emission region size R = 3.0 x 10{sup 16} cm for an appropriate beaming with a Doppler factor of {delta} = 20. This value of B is in good agreement with an independent estimate through the model fit to the observed time lag ascribing the energy-dependent variability to differential acceleration timescale of relativistic electrons provided that the gyro-factor {zeta} is 10{sup 5}.
Date: April 22, 2008
Creator: Sato, R.; Kataoka, J.; Takahashi, T.; Madejski, G.M.; Rugamer, S. & Wagner, S.J.
Partner: UNT Libraries Government Documents Department

Solid oxide compounds - properties necessary for fusion applications

Description: An experimental program was conducted in collaboration with the staff at the Japan Atomic Energy Research Institute for the purpose of generating fusion pertinent thermophysical and chemical data on two ternary lithium oxides that have potential as tritium breeder materials, Li/sub 2/ZrO/sub 3/ and Li/sub 2/TiO/sub 3/. The four areas studied were: (1) fabrication, (2) thermal diffusivity/thermal conductivity, (3) compatibility with candidate structural alloys (HT-9, 316 SS, and Ni-plated 316 SS), and (4) tritium release behavior after irradiation. Where possible, the behavior of these materials was compared with lithium oxide.
Date: January 1, 1981
Creator: Finn, P.A.; Kurasawa, T.; Nasu, S.; Noda, K.; Takahashi, T.; Takeshita, H. et al.
Partner: UNT Libraries Government Documents Department

Investigation of carbon dioxide in the central South Pacific Ocean (WOCE Sections P-16C and P-17C) during the TUNES/2 expedition of the R/V Thomas Washington, July--August, 1991. Final technical report

Description: This report summarizes the results of carbon dioxide and associated hydrographic measurements made during the oceanographic expedition, TUNES/2, aboard the R/V Thomas Washington in the central South Pacific Ocean. During the 40 day expedition, the total carbon dioxide concentration in 1000 seawater samples were determined using a coulometer system and the pCO(sub 2) in 940 seawater samples were determined using an equilibrator/gas chromatograph system. The alkalinity values in 900 water samples were computed using these measurements. In addition, 156 coulometric measurements were made for the Certified Reference Solutions (Batch No. 6) and yielded a mean value of 2303.2 +or- 1.5umol/kg. The chemical characteristics for the major water masses have been determined.
Date: December 1, 1993
Creator: Takahashi, T.; Goddard, J. G.; Rubin, S.; Chipman, D. W. & Sutherland, S. C.
Partner: UNT Libraries Government Documents Department

In situ tritium recovery from Li{sub 2}O irradiated in a fast neutron flux: BEATRIX-II, Phase II temperature-change canister

Description: BEATRIX-II, Phase II was an in situ tritium recovery experiment designed to characterize the behavior of lithium ceramics irradiated to high burnup in a fast neutron flux. A thin-walled Li{sub 2}O ring specimen was irradiated at temperatures in the range from 520 to 640 C in helium sweep gases containing 0, 0.01 and 0.1% H{sub 2} to a 5% lithium burnup. The tritium recovery behavior of Li{sub 2}O was characterized by using temperature transients and sweep gas composition changes to effect changes in the tritium inventory.
Date: April 1, 1994
Creator: Slagle, O. D.; Hollenberg, G. W.; Kurasawa, T.; Takahashi, T. & Verrall, R. A.
Partner: UNT Libraries Government Documents Department

Fermi-LAT Observation of Supernova Remnant S147

Description: We present an analysis of gamma-ray data obtained with the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope in the region around SNR S147 (G180.0-1.7). A spatially extended gamma-ray source detected in an energy range of 0.2-10 GeV is found to coincide with SNR S147. We confirm its spatial extension at >5{sigma} confidence level. The gamma-ray flux is (3.8 {+-} 0.6) x 10{sup -8} photons cm{sup -2} s{sup -1}, corresponding to a luminosity of 1.3 x 10{sup 34} (d/1.3 kpc){sup 2} erg s{sup -1} in this energy range. The gamma-ray emission exhibits a possible spatial correlation with prominent H{alpha} filaments of S147. There is no indication that the gamma-ray emission comes from the associated pulsar PSR J0538+2817. The gamma-ray spectrum integrated over the remnant is likely dominated by the decay of neutral {pi} mesons produced through the proton-proton collisions in the filaments. Reacceleration of pre-existing CRs and subsequent adiabatic compression in the filaments is sufficient to provide the required energy density of high-energy protons.
Date: August 17, 2012
Creator: Katsuta, J.; Uchiyama, Y.; Tanaka, T.; Tajima, H.; Bechtol, K.; Funk, S. et al.
Partner: UNT Libraries Government Documents Department

Postirradiation examination of BEATRIX-II, Phase 1

Description: BEATRIX-II is an in situ tritium recovery experiment that was designed to characterize the behavior of lithium ceramics irradiated to high burnup in a fast neutron flux. Postirradiation examination was carried out on the Phase 1 vented canisters: one containing a Li{sub 2}O ring capable of temperature changes and the other a Li{sub 2}O solid specimen with a center temperature of 1,000{degrees}C. The tritium inventory of the ring specimen at 650{degrees}C was determined to be in the range from 0.2--0.6 wppm while for the solid specimen the inventory varied from 1.4 wppm at the surface to 0.06 wppm at the inner surface. Downstream transport of the Li{sub 2}O by the sweep gas was determined to be insignificant from analyses of acid rinses of selected canister surfaces. Densification and restructuring of the solid specimen during irradiation resulted in the development of a central annulus. Ceramography was used to characterize the columnar grain structure and the mechanisms involved in its evolution.
Date: September 1, 1993
Creator: Slagle, O. D.; Hobbs, F. D.; Baldwin, D. L.; Hollenberg, G. W.; Takahashi, T.; Noda, K. et al.
Partner: UNT Libraries Government Documents Department

Recent Results From a Si/CdTe Semiconductor Compton Telescope

Description: We are developing a Compton telescope based on high resolution Si and CdTe detectors for astrophysical observations in sub-MeV/MeV gamma-ray region. Recently, we constructed a prototype Compton telescope which consists of six layers of double-sided Si strip detectors and CdTe pixel detectors to demonstrate the basic performance of this new technology. By irradiating the detector with gamma-rays from radio isotope sources, we have succeeded in Compton reconstruction of images and spectra. The obtained angular resolution is 3.9{sup o} (FWHM) at 511 keV, and the energy resolution is 14 keV (FWHM) at the same energy. In addition to the conventional Compton reconstruction, i.e., drawing cones in the sky, we also demonstrated a full reconstruction by tracking Compton recoil electrons using the signals detected in successive Si layers. By irradiating {sup 137}Cs source, we successfully obtained an image and a spectrum of 662 keV line emission with this method. As a next step, development of larger double-sided Si strip detectors with a size of 4 cm x 4 cm is underway to improve the effective area of the Compton telescope. We are also developing a new low-noise analog ASIC to handle the increasing number of channels. Initial results from these two new technologies are presented in this paper as well.
Date: January 23, 2007
Creator: Tanaka, T.; Watanabe, S.; Takeda, S.; Oonuki, K.; Mitani, T.; Nakazawa, K. et al.
Partner: UNT Libraries Government Documents Department

Fermi-LAT and Suzaku Observations of the Radio Galaxy Centaurus B

Description: CentaurusB is a nearby radio galaxy positioned in the Southern hemisphere close to the Galactic plane. Here we present a detailed analysis of about 43 months accumulation of Fermi-LAT data and of newly acquired Suzaku X-ray data for Centaurus B. The source is detected at GeV photon energies, although we cannot completely exclude the possibility that it is an artifact due to incorrect modeling of the bright Galactic diffuse emission in the region. The LAT image provides a weak hint of a spatial extension of the {gamma} rays along the radio lobes, which is consistent with the lack of source variability in the GeV range. We note that the extension cannot be established statistically due to the low number of the photons. Surprisingly, we do not detect any diffuse emission of the lobes at X-ray frequencies, with the provided upper limit only marginally consistent with the previously claimed ASCA flux. The broad-band modeling shows that the observed {gamma}-ray flux of the source may be produced within the lobes, if the diffuse non-thermal X-ray emission component is not significantly below the derived Suzaku upper limit. This association would imply that efficient in-situ acceleration of the ultrarelativistic particles is occurring and that the lobes are dominated by the pressure from the relativistic particles. However, if the diffuse X-ray emission is much below the Suzaku upper limits, the observed {gamma}-ray flux is not likely to be produced within the lobes, but instead within the unresolved core of Centaurus B. In this case, the extended lobes could be dominated by the pressure of the magnetic field.
Date: August 17, 2012
Creator: Katsuta, Junichiro; Tanaka, Y. T.; Stawarz, L.; O'Sullivan, S. P.; Cheung, C. C.; Kataoka, J. et al.
Partner: UNT Libraries Government Documents Department

Design and performance of soft gamma-ray detector for NeXT mission

Description: The Soft Gamma-ray Detector (SGD) on board NeXT (Japanese future high energy astrophysics mission) is a Compton telescope with narrow field of view, which utilizes Compton kinematics to enhance its background rejection capabilities. It is realized as a hybrid semiconductor gamma-ray detector which consists of silicon and Cadmium Telluride (CdTe) detectors. It can detect photons in an energy band 0.05-1 MeV at a background level of 5 x 10{sup -7} counts/s/cm{sup 2}/keV; the silicon layers are required to improve the performance at a lower energy band (<0.3 MeV). Excellent energy resolution is the key feature of the SGD to achieve both high angular resolution and good background rejection capability. Its ability to measure gamma-ray polarization opens up a new window to study gamma-ray emission in the universe. We will present the development of key technologies to realize the SGD; high quality CdTe, low noise front-end VLSI and bump bonding technology. Energy resolutions of 1.7 keV (FWHM) for CdTe pixel detectors and 1.1 keV for silicon strip detectors have been measured. We also present the validation of Monte Carlo simulation used to evaluate the performance of the SGD.
Date: May 4, 2005
Creator: Tajima, H.; Kamae, T.; Madejski, G.; Takahashi, T.; Nakazawa, K.; Watanabe, S. et al.
Partner: UNT Libraries Government Documents Department

Wide-Range Multiwavelength Observations of Northern TeV Blazars With MAGIC / HESS, Suzaku And KVA

Description: We have conducted multiwavelength observations of several northern TeV blazars employing the ground-based {gamma}-ray observatories MAGIC and HESS, the optical KVA telescope, and the Suzaku X-ray satellite. The data taken in 2006 establish measurements of the contemporaneous spectral energy distributions of the rapidly variable blazar emission over a wide range of frequencies. Results allow us to test leptonic and hadronic emission and particle acceleration models which predict different correlations between the optical, X-ray, and very high energy {gamma}-ray emissions. In this presentation, we report on the highlights of the results of these observations.
Date: November 14, 2007
Creator: Hayashida, M.; Rugamer, S.; Mazin, D.; Firpo, R.; Mannheim, K.; Tavecchio, F. et al.
Partner: UNT Libraries Government Documents Department