68 Matching Results

Results open in a new window/tab.

Enhanced Superconducting Gaps in Trilayer High-Temperature Bi (2) Sr (2) Ca (2) Cu (3) O (10+delta) Cuprate Superconductor (open access)

Enhanced Superconducting Gaps in Trilayer High-Temperature Bi (2) Sr (2) Ca (2) Cu (3) O (10+delta) Cuprate Superconductor

None
Date: November 14, 2012
Creator: Ideta, S.; Takashima, K.; Hashimoto, M.; Yoshida, T.; Fujimori, A.; Anzai, H. et al.
System: The UNT Digital Library
NARAC Modeling During the Response to the Fukushima Dai-ichi Nuclear Power Plant Emergency (open access)

NARAC Modeling During the Response to the Fukushima Dai-ichi Nuclear Power Plant Emergency

This paper summarizes the activities of the National Atmospheric Release Advisory Center (NARAC) during the Fukushima Dai-ichi nuclear power plant crisis. NARAC provided a wide range of products and analyses as part of its support including: (1) Daily Japanese weather forecasts and hypothetical release (generic source term) dispersion predictions to provide situational awareness and inform planning for U.S. measurement data collection and field operations; (2) Estimates of potential dose in Japan for hypothetical scenarios developed by the Nuclear Regulatory Commission (NRC) to inform federal government considerations of possible actions that might be needed to protect U.S. citizens in Japan; (3) Estimates of possible plume arrival times and dose for U.S. locations; and (4) Plume model refinement and source estimation based on meteorological analyses and available field data. The Department of Energy/National Nuclear Security Administration (DOE/NNSA) deployed personnel to Japan and stood up 'home team' assets across the DOE complex to aid in assessing the consequences of the releases from the Fukushima Dai-ichi Nuclear Power Plant. The DOE Nuclear Incident Team (NIT) coordinated response activities, while DOE personnel provided predictive modeling, air and ground monitoring, sample collection, laboratory analysis, and data assessment and interpretation. DOE deployed the Aerial Measuring System (AMS), …
Date: February 14, 2012
Creator: Sugiyama, G.; Nasstrom, J. S.; Probanz, B.; Foster, K. T.; Simpson, M.; Vogt, P. et al.
System: The UNT Digital Library
Systematic Uncertainties in NLO PS Matching (open access)

Systematic Uncertainties in NLO PS Matching

None
Date: December 14, 2012
Creator: Schonherr, Marek; Hoeche, Stefan; Krauss, Frank & Siegert, Frank
System: The UNT Digital Library
The DEEP2 Galaxy Redshift Survey: The Voronoi-Delaunay Method Catalog of Galaxy Groups (open access)

The DEEP2 Galaxy Redshift Survey: The Voronoi-Delaunay Method Catalog of Galaxy Groups

We use the first 25% of the DEEP2 Galaxy Redshift Survey spectroscopic data to identify groups and clusters of galaxies in redshift space. The data set contains 8370 galaxies with confirmed redshifts in the range 0.7 {<=} z {<=} 1.4, over one square degree on the sky. Groups are identified using an algorithm (the Voronoi-Delaunay Method) that has been shown to accurately reproduce the statistics of groups in simulated DEEP2-like samples. We optimize this algorithm for the DEEP2 survey by applying it to realistic mock galaxy catalogs and assessing the results using a stringent set of criteria for measuring group-finding success, which we develop and describe in detail here. We find in particular that the group-finder can successfully identify {approx}78% of real groups and that {approx}79% of the galaxies that are true members of groups can be identified as such. Conversely, we estimate that {approx}55% of the groups we find can be definitively identified with real groups and that {approx}46% of the galaxies we place into groups are interloper field galaxies. Most importantly, we find that it is possible to measure the distribution of groups in redshift and velocity dispersion, n({sigma}, z), to an accuracy limited by cosmic variance, for …
Date: February 14, 2012
Creator: Gerke, Brian F.; Newman, Jeffrey A.; Davis, Marc; Marinoni, Christian; Yan, Renbin; Coil, Alison L. et al.
System: The UNT Digital Library
Branching Fraction Measurements of the Color-Suppressed Decays B0bar to D(*)0 pi0, D(*)0 eta, D(*)0 omega, and D(*)0 eta_prime and Measurement of the Polarization in the Decay B0bar to D*0 omega (open access)

Branching Fraction Measurements of the Color-Suppressed Decays B0bar to D(*)0 pi0, D(*)0 eta, D(*)0 omega, and D(*)0 eta_prime and Measurement of the Polarization in the Decay B0bar to D*0 omega

We report updated branching fraction measurements of the color-suppressed decays {bar B}{sup 0} {yields} D{sup 0}{pi}{sup 0}, D*{sup 0}{pi}{sup 0}, D{sup 0}{eta}, D*{sup 0}{eta}, D{sup 0}{omega}, D*{sup 0}{omega}, D{sup 0}{eta}', and D*{sup 0}{eta}'. We measure the branching fractions (x10{sup -4}): {Beta}({bar B}{sup 0} {yields} D{sup 0}{pi}{sup 0}) = 2.69 {+-} 0.09 {+-} 0.13, {Beta}({bar B}{sup 0} {yields} D*{sup 0}{pi}{sup 0}) = 3.05 {+-} 0.14 {+-} 0.28, {Beta}({bar B}{sup 0} {yields} D{sup 0}{eta}) = 2.53 {+-} 0.09 {+-} 0.11, {Beta}({bar B}{sup 0} {yields} D*{sup 0}{eta}) = 2.69 {+-} 0.14 {+-} 0.23, {Beta}({bar B}{sup 0} {yields} D{sup 0}{omega}) = 2.57 {+-} 0.11 {+-} 0.14, {Beta}({bar B}{sup 0} {yields} D*{sup 0}{omega}) = 4.55 {+-} 0.24 {+-} 0.39, {Beta}({bar B}{sup 0} {yields} D{sup 0}{eta}') = 1.48 {+-} 0.13 {+-} 0.07, and {Beta}({bar B}{sup 0} {yields} D*{sup 0}{eta}') = 1.49 {+-} 0.22 {+-} 0.15. We also present the first measurement of the longitudinal polarization fraction of the decay channel D*{sup 0}{omega}, f{sub L} = (66.5 {+-} 4.7 {+-} 1.5)%. In the above, the first uncertainty is statistical and the second is systematic. The results are based on a sample of (454 {+-} 5) x 10{sup 6} B{bar B} pairs collected at the {Upsilon}(4S) resonance, with …
Date: February 14, 2012
Creator: Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M. et al.
System: The UNT Digital Library
Life extension program for the modular caustic side solvent extraction unit at Savannah River Site (open access)

Life extension program for the modular caustic side solvent extraction unit at Savannah River Site

Caustic Side Solvent Extraction (CSSX) is currently used at the U.S. Department of Energy (DOE) Savannah River Site (SRS) for removal of cesium from the high-level salt-wastes stored in underground tanks. At SRS, the CSSX process is deployed in the Modular CSSX Unit (MCU). The CSSX technology utilizes a multi-component organic solvent and annular centrifugal contactors to extract cesium from alkaline salt waste. Coalescers and decanters process the Decontaminated Salt Solution (DSS) and Strip Effluent (SE) streams to allow recovery and reuse of the organic solvent and to limit the quantity of solvent transferred to the downstream facilities. MCU is operated in series with the Actinide Removal Process (ARP) which removes strontium and actinides from salt waste utilizing monosodium titanate. ARP and MCU were developed and implemented as interim salt processing until future processing technology, the CSSX-based Salt Waste Processing Facility (SWPF), is operational. SWPF is slated to come on-line in October 2014. The three year design life of the ARP/MCU process, however, was reached in April 2011. Nevertheless, most of the individual process components are capable of operating longer. An evaluation determined ARP/MCU can operate until 2015 before major equipment failure is expected. The three year design life of …
Date: November 14, 2012
Creator: Samadi-Dezfouli, Azadeh
System: The UNT Digital Library
Ultracompact Accelerator Technology for a Next-Generation Gamma-Ray Source (open access)

Ultracompact Accelerator Technology for a Next-Generation Gamma-Ray Source

This presentation reported on the technology choices and progress manufacturing and testing the injector and accelerator of the 250 MeV ultra-compact Compton Scattering gamma-ray Source under development at LLNL for homeland security applications. This paper summarizes the status of various facets of current accelerator activities at LLNL. The major components for the X-band test station have been designed, fabricated, and await installation. The XL-4 klystron has been delivered, and will shortly be dressed and installed in the ScandiNova modulator. High power testing of the klystron into RF loads will follow, including adjustment of the modulator for the klystron load as necessary. Assembly of RF transport, test station supports, and accelerator components will follow. Commissioning will focus on processing the RF gun to full operating power, which corresponds to 200 MV/m peak electric field on the cathode surface. Single bunch benchmarking of the Mark 1 design will provide confidence that this first structure operates as designed, and will serve as a solid starting point for subsequent changes, such as a removable photocathode, and the use of various cathode materials for enhanced quantum efficiency. Charge scaling experiments will follow, partly to confirm predictions, as well as to identify important causes of emittance …
Date: May 14, 2012
Creator: Marsh, R A; Albert, F; Anderson, S G; Gibson, D J; Wu, S S; Hartemann, F V et al.
System: The UNT Digital Library
Ab-initio description of quasiparticle band structures and optical near-edge absorption of transparent conducting oxides (open access)

Ab-initio description of quasiparticle band structures and optical near-edge absorption of transparent conducting oxides

None
Date: February 14, 2012
Creator: Schleife, A & Bechstedt, F
System: The UNT Digital Library
Formic Acid Free Flowsheet Development To Eliminate Catalytic Hydrogen Generation In The Defense Waste Processing (open access)

Formic Acid Free Flowsheet Development To Eliminate Catalytic Hydrogen Generation In The Defense Waste Processing

The Defense Waste Processing Facility (DWPF) processes legacy nuclear waste generated at the Savannah River Site (SRS) during production of plutonium and tritium demanded by the Cold War. The nuclear waste is first treated via a complex sequence of controlled chemical reactions and then vitrified into a borosilicate glass form and poured into stainless steel canisters. Converting the nuclear waste into borosilicate glass canisters is a safe, effective way to reduce the volume of the waste and stabilize the radionuclides. Testing was initiated to determine whether the elimination of formic acid from the DWPF's chemical processing flowsheet would eliminate catalytic hydrogen generation. Historically, hydrogen is generated in chemical processing of alkaline High Level Waste sludge in DWPF. In current processing, sludge is combined with nitric and formic acid to neutralize the waste, reduce mercury and manganese, destroy nitrite, and modify (thin) the slurry rheology. The noble metal catalyzed formic acid decomposition produces hydrogen and carbon dioxide. Elimination of formic acid by replacement with glycolic acid has the potential to eliminate the production of catalytic hydrogen. Flowsheet testing was performed to develop the nitric-glycolic acid flowsheet as an alternative to the nitric-formic flowsheet currently being processed at the DWPF. This new …
Date: September 14, 2012
Creator: Lambert, Dan P.; Stone, Michael E.; Newell, J. David; Fellinger, Terri L. & Bricker, Jonathan M.
System: The UNT Digital Library
Lessons Learned From The 200 West Pump And Treatment Facility Construction Project At The US DOE Hanford Site - A Leadership For Energy And Environmental Design (LEED) Gold-Certified Facility (open access)

Lessons Learned From The 200 West Pump And Treatment Facility Construction Project At The US DOE Hanford Site - A Leadership For Energy And Environmental Design (LEED) Gold-Certified Facility

CH2M Hill Plateau Remediation Company (CHPRC) designed, constructed, commissioned, and began operation of the largest groundwater pump and treatment facility in the U.S. Department of Energy's (DOE) nationwide complex. This one-of-a-kind groundwater pump and treatment facility, located at the Hanford Nuclear Reservation Site (Hanford Site) in Washington State, was built in an accelerated manner with American Recovery and Reinvestment Act (ARRA) funds and has attained Leadership in Energy and Environmental Design (LEED) GOLD certification, which makes it the first non-administrative building in the DOE Office of Environmental Management complex to earn such an award. There were many contractual, technical, configuration management, quality, safety, and LEED challenges associated with the design, procurement, construction, and commissioning of this $95 million, 52,000 ft groundwater pump and treatment facility. This paper will present the Project and LEED accomplishments, as well as Lessons Learned by CHPRC when additional ARRA funds were used to accelerate design, procurement, construction, and commissioning of the 200 West Groundwater Pump and Treatment (2W P&T) Facility to meet DOE's mission of treating contaminated groundwater at the Hanford Site with a new facility by June 28, 2012.
Date: November 14, 2012
Creator: Dorr, Kent A.; Ostrom, Michael J. & Freeman-Pollard, Jhivaun R.
System: The UNT Digital Library
Uncertainties in NLO + Parton Shower Matched Simulations of Inclusive Jet and Dijet Production (open access)

Uncertainties in NLO + Parton Shower Matched Simulations of Inclusive Jet and Dijet Production

None
Date: December 14, 2012
Creator: Hoeche, Stefan & Schonherr, Marek
System: The UNT Digital Library
Transport from the Recycler Ring to the Antiproton Source Beamlines (open access)

Transport from the Recycler Ring to the Antiproton Source Beamlines

In the post-NOvA era, the protons are directly transported from the Booster ring to the Recycler ring rather than the Main Injector. For Mu2e and g-2 project, the Debuncher ring will be modified into a Delivery ring to deliver the protons to both Mu2e and g-2 experiments. Therefore, it requires the transport of protons from the Recycler Ring to the Delivery ring. A new transfer line from the Recycler ring to the P1 beamline will be constructed to transport proton beam from the Recycler Ring to existing Antiproton Source beamlines. This new beamline provides a way to deliver 8 GeV kinetic energy protons from the Booster to the Delivery ring, via the Recycler, using existing beam transport lines, and without the need for new civil construction. This paper presents the Conceptual Design of this new beamline.
Date: May 14, 2012
Creator: Xiao, M.
System: The UNT Digital Library
A Natural Language for AdS/CFT Correlators (open access)

A Natural Language for AdS/CFT Correlators

We provide dramatic evidence that 'Mellin space' is the natural home for correlation functions in CFTs with weakly coupled bulk duals. In Mellin space, CFT correlators have poles corresponding to an OPE decomposition into 'left' and 'right' sub-correlators, in direct analogy with the factorization channels of scattering amplitudes. In the regime where these correlators can be computed by tree level Witten diagrams in AdS, we derive an explicit formula for the residues of Mellin amplitudes at the corresponding factorization poles, and we use the conformal Casimir to show that these amplitudes obey algebraic finite difference equations. By analyzing the recursive structure of our factorization formula we obtain simple diagrammatic rules for the construction of Mellin amplitudes corresponding to tree-level Witten diagrams in any bulk scalar theory. We prove the diagrammatic rules using our finite difference equations. Finally, we show that our factorization formula and our diagrammatic rules morph into the flat space S-Matrix of the bulk theory, reproducing the usual Feynman rules, when we take the flat space limit of AdS/CFT. Throughout we emphasize a deep analogy with the properties of flat space scattering amplitudes in momentum space, which suggests that the Mellin amplitude may provide a holographic definition of …
Date: February 14, 2012
Creator: Fitzpatrick, A. Liam; Kaplan, Jared; Penedones, Joao; Raju, Suvrat & van Rees, Balt C.
System: The UNT Digital Library
Constraints on Dark Matter Annihilation in Clusters of Galaxies with the Fermi Large Area Telescope (open access)

Constraints on Dark Matter Annihilation in Clusters of Galaxies with the Fermi Large Area Telescope

None
Date: December 14, 2012
Creator: Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G. et al.
System: The UNT Digital Library
Application of the Principle of Maximum Conformality to the Top-Quark Forward-Backward Asymmetry at the Tevatron (open access)

Application of the Principle of Maximum Conformality to the Top-Quark Forward-Backward Asymmetry at the Tevatron

The renormalization scale uncertainty can be eliminated by the Principle of Maximum Conformality (PMC) in a systematic scheme-independent way. Applying the PMC for the t{bar t}-pair hadroproduction at the NNLO level, we have found that the total cross-sections {sigma}{sub t{bar t}} at both the Tevatron and LHC remain almost unchanged when taking very disparate initial scales {mu}{sub R}{sup init} equal to m{sub t}, 10 m{sub t}, 20 m{sub t} and {radical}s, which is consistent with renormalization group invariance. As an important new application, we apply PMC scale-setting to study the top-quark forward-backward asymmetry. We observe that the more convergent perturbative series after PMC scale-setting leads to a more accurate top-quark forward-backward asymmetry. The resulting PMC prediction on the asymmetry is also free from the initial renormalization scale-dependence. Because the NLO PMC scale has a dip behavior for the (q{bar q})-channel at small subprocess collision energies, the importance of this channel to the asymmetry is increased. We observe that the asymmetries A{sub FB}{sup t{bar t}} and A{sub FB}{sup p{bar p}} at the Tevatron will be increased by 42% in comparison to the previous estimates obtained by using conventional scale-setting; i.e. we obtain A{sub FB}{sup t{bar t}PMC} {approx_equal} 12.5% and A{sub FB}{sup …
Date: May 14, 2012
Creator: Brodsky, Stanley J. & Wu, Xing-Gang
System: The UNT Digital Library
Comparison of CDMS [100] and [111] Oriented Germanium Detectors (open access)

Comparison of CDMS [100] and [111] Oriented Germanium Detectors

The Cryogenic Dark Matter Search (CDMS) utilizes large mass, 3-inch diameter x 1-inch thick target masses as particle detectors. The target is instrumented with both phonon and ionization sensors and comparison of energy in each channel provides event-by-event classification of electron and nuclear recoils. Fiducial volume is determined by the ability to obtain good phonon and ionization signal at a particular location. Due to electronic band structure in germanium, electron mass is described by an anisotropic tensor with heavy mass aligned along the symmetry axis defined by the [111] Miller index (L valley), resulting in large lateral component to the transport. The spatial distribution of electrons varies significantly for detectors which have their longitudinal axis orientations described by either the [100] or [111] Miller indices. Electric fields with large fringing component at high detector radius also affect the spatial distribution of electrons and holes. Both effects are studied in a 3 dimensional Monte Carlo and the impact on fiducial volume is discussed.
Date: September 14, 2012
Creator: Leman, S. W.; Hertel, S. A.; /MIT, MKI; Kim, P.; /SLAC; Cabrera, B. et al.
System: The UNT Digital Library
Improving the Fermilab Booster Notching Efficiency, Beam Losses and Radiation Levels (open access)

Improving the Fermilab Booster Notching Efficiency, Beam Losses and Radiation Levels

A fast vertical 1.08-m long kicker (notcher) located in the Fermilab Booster Long-05 straight section is currently used to remove 3 out of 84 circulating bunches after injection to generate an abort gap. With the maximum magnetic field of 72.5 Gauss, it removes only 87% of the 3-bunch intensity at 400 MeV, with 75% loss on pole tips of the focusing Booster magnets, 11% on the Long-06 collimators, and 1% in the rest of the ring. We propose to improve the notching efficiency and reduce beam loss in the Booster by using three horizontal kickers in the Long-12 section. STRUCT calculations show that using horizontal notchers, one can remove up to 96% of the 3-bunch intensity at 400-700 MeV, directing 95% of it to a new beam dump at the Long-13 section. This fully decouples notching and collimation. The beam dump absorbs most of the impinging proton energy in its jaws. The latter are encapsulated into an appropriate radiation shielding that reduces impact on the machine components, personnel and environment to the tolerable levels. MARS simulations show that corresponding prompt and residual radiation levels can be reduced ten times compared to the current ones.
Date: May 14, 2012
Creator: Rakhno, I. L.; Drozhdin, A. I.; Mokhov, N. V.; Sidorov, V. I. & Tropin, I. S.
System: The UNT Digital Library
Development of Electronics for the ATF2 Interaction Point Region Beam Position Monitor (open access)

Development of Electronics for the ATF2 Interaction Point Region Beam Position Monitor

Nanometer resolution beam position monitors have been developed to measure and control beam position stability at the interaction point region of ATF2. The position of the beam has to be measured to within a few nanometers at the interaction point. In order to achieve this performance, electronics for the low-Q IP-BPM was developed. Every component of the electronics have been simulated and checked on the bench and using the ATF2 beam. We will explain each component and define their working range. Then, we will show the performance of the electronics measured with beam signal. ATF2 is a final focus test beam line for ILC in the framework of the ATF international collaboration. The new beam line was constructed to extend the extraction line at ATF, KEK, Japan. The first goal of ATF2 is the acheiving of a 37 nm vertical beam size at focal point (IP). The second goal is to stabilize the beam at the focal point at a few nanometer level for a long period in order to ensure the high luminosity. To achieve these goals a high resolution IP-BPM is essential. In addition for feedback applications a low-Q system is desirable.
Date: August 14, 2012
Creator: Kim, Youngim; U., /Kyungpook Natl.; Heo, Ae-young; U., /Kyungpook Natl.; Kim, Eun-San; U., /Kyungpook Natl. et al.
System: The UNT Digital Library
Higher Order Modes HOM___s in Coupled Cavities of the Flash Module ACC39 (open access)

Higher Order Modes HOM___s in Coupled Cavities of the Flash Module ACC39

We analyse the higher order modes (HOM's) in the 3.9GHz bunch shaping cavities installed in the FLASH facility at DESY. A suite of finite element computer codes (including HFSS and ACE3P) and globalised scattering matrix calculations (GSM) are used to investigate the modes in these cavities. This study is primarily focused on the dipole component of the multiband expansion of the wakefield, with the emphasis being on the development of a HOM-based BPM system for ACC39. Coupled inter-cavity modes are simulated together with a limited band of trapped modes.
Date: September 14, 2012
Creator: Shinton, I. R. R.; Jones, R. M.; Li, Z. & Zhang, P.
System: The UNT Digital Library
Gravitomagnetism and Spinor Quantum Mechanics (open access)

Gravitomagnetism and Spinor Quantum Mechanics

We give a systematic treatment of a spin 1=2 particle in a combined electromagnetic field and a weak gravitational field that is produced by a slowly moving matter source. This paper continues previous work on a spin zero particle, but it is largely self-contained and may serve as an introduction to spinors in a Riemann space. The analysis is based on the Dirac equation expressed in generally covariant form and coupled minimally to the electromagnetic field. The restriction to a slowly moving matter source, such as the earth, allows us to describe the gravitational field by a gravitoelectric (Newtonian) potential and a gravitomagnetic (frame-dragging) vector potential, the existence of which has recently been experimentally verified. Our main interest is the coupling of the orbital and spin angular momenta of the particle to the gravitomagnetic field. Specifically we calculate the gravitational gyromagnetic ratio as g{sub g} = 1 ; this is to be compared with the electromagnetic gyromagnetic ratio of g{sub e} = 2 for a Dirac electron.
Date: September 14, 2012
Creator: Adler, Ronald J.; /Stanford U., HEPL /San Francisco State U.; Chen, Pisin; /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC; Varani, Elisa & /Unlisted
System: The UNT Digital Library
The Conceptional Design of the Shielding Layout and Beam Absorber at the PXIE (open access)

The Conceptional Design of the Shielding Layout and Beam Absorber at the PXIE

Project X is a high intensity proton facility conceived to support a world-leading physics program at Fermilab. Project X will provide high intensity beams for neutrino, kaon, muon, and nuclei based experiments and for studies supporting energy applications. The Project X Injector Experiment (PIXIE) is a prototype of the Project X front end. A 30 MeV 50 kW beam will be used to validate the design concept of the Project X. This paper discusses a design of the accelerator enclosure radiation shielding and the beam dump.
Date: May 14, 2012
Creator: Eidelman, Yu.; Kerby, J.; Lebedev, V.; Leibfritz, J.; Leveling, T.; Nagaisev, S. et al.
System: The UNT Digital Library
Halo-to-Halo Similarity and Scatter in the Velocity Distribution of Dark Matter (open access)

Halo-to-Halo Similarity and Scatter in the Velocity Distribution of Dark Matter

Examines the velocity distribution function (VDF) in dark matter halos from milky way to cluster mass scales.
Date: December 14, 2012
Creator: Mao, Yao-Yuan; Strigari, Louis E.; Wechsler, Risa H.; Wu, Hao-Yi & Hahn, Oliver
System: The UNT Digital Library
The National Ignition Campaign: Status and Progress (open access)

The National Ignition Campaign: Status and Progress

None
Date: August 14, 2012
Creator: Moses, Edward
System: The UNT Digital Library
A GREEN'S FUNCTION APPROACH FOR DETERMINING DOSE RATES FOR SMALL GRAM QUANTITIES IN SHIPPING PACKAGINGS (open access)

A GREEN'S FUNCTION APPROACH FOR DETERMINING DOSE RATES FOR SMALL GRAM QUANTITIES IN SHIPPING PACKAGINGS

The Small Gram Quantity (SGQ) concept is based on the understanding that small amounts of hazardous materials, in this case radioactive materials (RAM), are significantly less hazardous than large amounts of the same materials. This paper describes a methodology designed to estimate an SGQ for several neutron and gamma emitting isotopes that can be shipped in a package in compliance with 10 CFR Part 71 external radiation level limits regulations. The neutron and photon sources were calculated using both ORIGEN-S and RASTA. The response from a unit source in each neutron and photon group was calculated using MCNP5 with each unshielded and shielded container configuration. Effects of self-shielding on both neutron and photon response were evaluated by including either plutonium oxide or iron in the source region for the case with no shielded container. For the cases of actinides mixed with light elements, beryllium is the bounding light element. The added beryllium (10 to 90 percent of the actinide mass) in the cases studied represents between 9 and 47 percent concentration of the total mixture mass. For beryllium concentrations larger than 50 percent, the increase in the neutron source term and dose rate tend to increase at a much lower …
Date: June 14, 2012
Creator: Nathan, S.
System: The UNT Digital Library