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Determination of the beta energy (E/sub max/) using thin window instruments (open access)

Determination of the beta energy (E/sub max/) using thin window instruments

The use of simple survey instruments for beta-energy analysis is complicated by large differences that exist in the beta spectra shapes. These spectral shapes are often complex and change continuously as the betas are absorbed in air. Changes are also caused by absorbing material between the source and the detector. One may frequently encounter a combination of beta energies, either from multiple emissions from a single isotope or from several isotopes in the sample being evaluated. There may also be monoenergetic conversion electrons present in the sample or low-energy X rays which are absorbed in a similar fashion to betas. Obviously, a complete analysis of compelx beta spectra cannot be performed using only survey instruments. We present two methods which will give the approximate E/sub max/ of the beta energy responsible for the most significant portion of the beta dose. Either technique should give adequate information about the beta spectra to provide necessary guidance for the health physics evaluation of the exposure.
Date: August 12, 1983
Creator: Hankins, D.E.
System: The UNT Digital Library
National Low-Temperature Neutron-Irradiation Facility (open access)

National Low-Temperature Neutron-Irradiation Facility

The Materials Sciences Division of the United States Department of Energy will establish a National Low Temperature Neutron Irradiation Facility (NLTNIF) which will utilize the Bulk Shielding Reactor (BSR) located at Oak Ridge National Laboratory. The facility will provide high radiation intensities and special environmental and testing conditions for qualified experiments at no cost to users. This report describes the planned experimental capabilities of the new facility.
Date: August 1, 1983
Creator: Coltman, R.R. Jr.; Klabunde, C.E. & Young, F.W. Jr.
System: The UNT Digital Library
Evolution of the mirror machine (open access)

Evolution of the mirror machine

The history of the magnetic-mirror approach to a fusion reactor is primarily the history of our understanding and control of several crucial physics issues, coupled with progress in the technology of heating and confining a reacting plasma. The basic requirement of an MHD-stable plasma equilibrium was achieved following the early introduction of minimum-B multipolar magnetic fields. In refined form, the same magnetic-well principle carries over to our present experiments and to reactor designs. The higher frequency microinstabilities, arising from the non-Maxwellian particle distributions inherent in mirror machines, have gradually come under control as theoretical prescriptions for distribution functions have been applied in the experiments. Even with stability, the classical plasma leakage through the mirrors posed a serious question for reactor viability until the principle of electrostatic axial stoppering was applied in the tandem mirror configuration. Experiments to test this principle successfully demonstrated the substantial improvement in confinement predicted. Concurrent with advances in mirror plasma physics, development of both high-power neutral beam injectors and high-speed vacuum pumping techniques has played a crucial role in ongoing experiments. Together with superconducting magnets, cryogenic pumping, and high-power radiofrequency heating, these technologies have evolved to a level that extrapolates readily to meet the requirements of …
Date: August 18, 1983
Creator: Damm, C. C.
System: The UNT Digital Library
Preliminary study of magnet design for an SSC (open access)

Preliminary study of magnet design for an SSC

The overriding design consideration for the SSC magnets is that cost of the facility be minimized; at 8 T, approximately 40 km of bending magnets is required for each ring of a 20 TeV collider. We present some results of a parametric study of two-in-one, iron-core magnets for an SSC. These results are necessarily preliminary in nature, and are intended only to show some of the trade-offs for a wide range of the variables. We show also some results for a reference design that produces 6.5 T in the aperture at 4.4 K for a coil inside diameter of 40 mm. It is not to be inferred that we have established this to be an optimum in any sense.
Date: August 1, 1983
Creator: Taylor, C.E. & Meuser, R.B.
System: The UNT Digital Library
Progress toward 10 tesla accelerator dipoles (open access)

Progress toward 10 tesla accelerator dipoles

A 9.1 T central field has been achieved in a Nb-Ti dipole operating in pressurized helium II at 1.8 K. Three different Nb-Ti dipoles, without iron yokes, have achieved central fields of 8.0, 8.6, and 9.1 T - all short sample performance for the conductors at 1.8 K. In helium I, at 4.3 K, the maximum central fields are from 1.5 to 2.0 T lower. Ten-tesla magnets have been designed for both Nb-Ti operating at 1.8 K and Nb/sub 3/Sn operating at 4.2 K. They are based on a very small beam aperture, (40 to 45 mm), very high current density in the superconductors (over 1000 A/mm/sup 2/), and a very low ratio of stabilizing copper to superconductor (about 1). Both layer and block designs have been developed that utilize Rutherford Cable. Magnet cycling from 0 to 6 T has been carried out for field change rate up to 1 T/s; the cyclic heating at 1 T/s is 36 W per meter. At a more representative rate of 0.2 T/s the heating rate is only 2 W/m. Progress in the program to use Nb/sub 3/Sn and NbTi superconductor, in 10 T accelerator magnets is also discussed.
Date: August 1, 1983
Creator: Hassenzahl, W.; Gilbert, G.; Taylor, C. & Meuser, R.
System: The UNT Digital Library
Summary of well-testing activities at Lawrence Berkeley Laboratory, 1975-1983 (open access)

Summary of well-testing activities at Lawrence Berkeley Laboratory, 1975-1983

Well test data collected from various geothermal fields by the geothermal group at Lawrence Berkeley Laboratory are presented. The type of well tests conducted, the instrumentation used and the data collected are described. Experience gained through interpretation of the data has helped identify problems in test procedures and interpretative methods.
Date: August 1, 1983
Creator: Bodvarsson, M.G. & Benson, S.M.
System: The UNT Digital Library
Chromatic properties and tracking studies of a 20 TeV pp collider (open access)

Chromatic properties and tracking studies of a 20 TeV pp collider

The chromatic properties of a lattice for the 20 TeV pp collider described in an accompanying paper have been investigated. Since this machine has a low ..beta..-function value at the interaction points (..beta../sub x,y/ = 2 m), the large value in the nearby quadrupoles is a major source of perturbations for off-momentum particles. Preliminary tracking studies have been performed in an attempt to determine the dynamic aperture. The model includes the effects of chromaticity sextupoles, octupoles to straighten the working line, random multipoles simulating magnet construction errors and closed orbit distortions.
Date: August 1, 1983
Creator: Garren, A.; Cornacchia, M. & Dell, F.
System: The UNT Digital Library
Vacuum measurements on the Tandem Mirror Experiment Upgrade (TMX-U) fusion experiment (open access)

Vacuum measurements on the Tandem Mirror Experiment Upgrade (TMX-U) fusion experiment

The gas inventory of the Tandem Mirror Experiment Upgrade (TMX-U) must be carefully controlled, if it is to successfully create various plasma configurations for thermal-barrier experiments designed to provide an improved performance for tandem-mirror experiments. This paper is a progress report on the calibration methods and pressure measurements of machine conditions deriving from recently improved neutral-beam gas control, and changes to the internal baffling geometry and the gettering system.
Date: August 12, 1983
Creator: Calderon, M. O.; Hunt, A. L.; Lang, D. D.; Nexsen, W. E.; Pickles, W. L. & Turner, W. C.
System: The UNT Digital Library
Shock Hugoniot measurements on Ta to 0. 78 TPa (open access)

Shock Hugoniot measurements on Ta to 0. 78 TPa

Symmetric impact shock Hugoniot measurements have been made on Ta with an electrically exploded foil gun system. The results obtained to date for the Hugoniot of Ta cover the range 0.19 to 0.78 TPa (impact velocities from 4.0 to 9.7 km/s) and agree with data obtained by other researchers to within 2.7% rms. Recent improvements in the system include electromagnetic shielding of impactor and target, continuous measurement of impactor velocity with a Fabry-Perot interferometer and computer-aided analysis of shot film. Conservative extrapolation from current operating conditions indicate that pressures of 1.1 to 1.5 TPa could be achieved with little difficulty.
Date: August 18, 1983
Creator: Froeschner, K. E.; Lee, R. S.; Chau, H. H. & Weingart, R. C.
System: The UNT Digital Library
Spectroscopy of gluonic states at LAMPF II (open access)

Spectroscopy of gluonic states at LAMPF II

The properties of QCD which imply the existence of gluonic states are reviewed. The problem of discovering the spectrum of gluonic states is discussed in general and illustrated with examples from current data. Higher statistics fixed target experiments, such as could be performed at LAMPF II, are essential for further progress.
Date: August 1, 1983
Creator: Chanowitz, Michael S.
System: The UNT Digital Library
Status of perturbative QCD (open access)

Status of perturbative QCD

In this talk is discussed, within the framework of perturbative QCD, four topics which have received theoretical attention in the last year. They are: (1) jets at the CERN Sp anti p S collider, (2) power corrections to leptoproduction, (3) hard scattering off nuclear targets, and (4) the photon structure function. 28 references.
Date: August 1, 1983
Creator: Ellis, R.K.
System: The UNT Digital Library
Welding superalloy sheet for superconducting cable jackets (open access)

Welding superalloy sheet for superconducting cable jackets

Autogenous gas tungsten arc welds produced in A-286 exhibit significantly lower yield and ultimate tensile strengths than comparably heat-treated base metal. Deformation in the aged weld metal is highly localized and delineates the dendritic microstructure. The observed mechanical properties are caused by the formation of precipitate-free regions located at the dendrite cores. These regions form as the result of titanium segregation during weld pool solidification which yields dendrite cores sufficiently lean in titanium as to prevent nucleation of the hardening phase.
Date: August 1, 1983
Creator: Summers, L.T.; Strum, M.J. & Morris, J.W. Jr.
System: The UNT Digital Library
Molecular surface science of heterogeneous catalysis. History and perspective (open access)

Molecular surface science of heterogeneous catalysis. History and perspective

A personal account is given of how the author became involved with modern surface science and how it was employed for studies of the chemistry of surfaces and heterogeneous catalysis. New techniques were developed for studying the properties of the surface monolayers: Auger electron spectroscopy, LEED, XPS, molecular beam surface scattering, etc. An apparatus was developed and used to study hydrocarbon conversion reactions on Pt, CO hydrogenation on Rh and Fe, and NH/sub 3/ synthesis on Fe. A model has been developed for the working Pt reforming catalyst. The three molecular ingredients that control catalytic properties are atomic surface structure, an active carbonaceous deposit, and the proper oxidation state of surface atoms. 40 references, 21 figures. (DLC)
Date: August 1, 1983
Creator: Somorjai, G.A.
System: The UNT Digital Library
Neutron diffraction studies of natural glasses (open access)

Neutron diffraction studies of natural glasses

A neutron diffraction investigation has been carried out of the structures of several naturally occurring glasses, viz. Libyan Desert glass, a Fulgurite, Wabar glass, Lechatelierite from Canon Diablo, a Tektite, Obsidian (3 samples), and Macusani glass. Libyan Desert sand has also been examined, together with crystalline ..cap alpha..-quartz and ..cap alpha..-cristobalite. A comparison of data for the natural glasses and synthetic vitreous silica (Spectrosil B) in both reciprocal and real space allows a categorisation into Silicas, which closely resemble synthetic vitreous silica, and Silicates, for which the resemblance to silica is consistently less striking. The data support the view that Libyan Desert glass and sand have a common origin, while the Tektite has a structure similar to that of volcanic glasses.
Date: August 1, 1983
Creator: Wright, A.C.; Erwin Desa, J.A.; Weeks, R.A.; Sinclair, R.N. & Bailey, D.K.
System: The UNT Digital Library
Fission-gas-bubble mobility in oxide fuel: a critical analysis (open access)

Fission-gas-bubble mobility in oxide fuel: a critical analysis

The available volatile fission product release data has confirmed the general viability of the scaling model of volatile fission product release in which the fractional release rates of the volatile fission products scale as that of the fission gas. The question of whether fission gas bubbles can move sufficiently fast to be a significant mechanism responsible for fission gas release from the fuel is considered. The mean jump distance per jump of the hopping process in gas bubble motion is analyzed. Surface roughness is also considered.
Date: August 1, 1983
Creator: Tam, S. W. & Johnson, C. E.
System: The UNT Digital Library
Fuel debris assessment for Three Mile Island Unit 2 (TMI-2) reactor recovery by gamma-ray and neutron dosimetry (open access)

Fuel debris assessment for Three Mile Island Unit 2 (TMI-2) reactor recovery by gamma-ray and neutron dosimetry

As a result of the accident on March 28, 1979, fuel debris was dispersed into the primary coolant system of the Three Mile Island Unit 2 (TMI-2) reactor. Location and quantification of fuel debris is essential for TMI-2 recovery. TMI-2 fuel debris assessments can be carried out nondestructively by neutron and gamma-ray dosimetry. Efforts to date have been directed toward fuel debris characterization of the makeup and purification demineralizers, will maintain reactor coolant water purity. Two highly specialized dosimetry methods were applied: solid state track recorder (SSTR) neutron dosimetry and continuous gamma-ray spectrometry. The most recent dosimetry results are reviewed and compared. To reduce the intense background radiation from /sup 137/Cs, the Si(Li) detector was surrounded by a 5.5 diameter lead shield 8'' shield in length. The spectral data were used to determine the intensity of the 2.18 MeV gamma ray from the fission product /sup 144/Ce. Assuming this fission product does not migrate out of the fuel, the quantity of /sup 144/Ce is directly related to the quantity of fuel present. Based on the observed source geometry and the measured flux of the /sup 144/Ce 2.18 MeV gamma rays, the fuel content of the A demineralizer was calculated to …
Date: August 22, 1983
Creator: Gold, R.; Roberts, J. H.; McNeece, J. P.; Kaiser, B. J.; Ruddy, F. H.; Preston, C. C. et al.
System: The UNT Digital Library
LBL program of 1 meter long, 50 mm diameter bore, dipoles with fields greater than 8 tesla (open access)

LBL program of 1 meter long, 50 mm diameter bore, dipoles with fields greater than 8 tesla

Model dipole superconducting magnets with central fields above 8 tesla are being developed for future multi-TeV colliding beam accelerators. The first three models are 1 meter long, have nominal 50 mm diameter cold bores, and utilize Nb-Ti superconductor operating in He II at 1.8 K. None of the three models had an iron flux-return yoke. The maximum central fields achieved are 8.0, 8.6, and 9.1 tesla - all short-sample performance at 1.8 K for the conductors used. At 4.3 K the maximum central fields are from 1.5 to 2.0 tesla lower. In one design, the superconductor is arranged in four concentric cylindrical layers, sometimes called a four-shell geometry. With higher current density Nb-Ti we expect this design to reach 10 tesla central field and a two layer design to reach 8 tesla. The other design uses 8 flat pancakes with upturned ends. Improved Nb-Ti should also allow this design to reach 10 tesla central field. This geometry is being used for our Nb/sub 3/Sn wind-and-react dipole to be operated in He I at 4.3 K.
Date: August 1, 1983
Creator: Hassenzahl, W.; Gilbert, W.; Taylor, C. & Meuser, R.
System: The UNT Digital Library
Statistical properties of deep inelastic reactions (open access)

Statistical properties of deep inelastic reactions

The multifaceted aspects of deep-inelastic heavy-ion collisions are discussed in terms of the statistical equilibrium limit. It is shown that a conditional statistical equilibrium, where a number of degrees of freedom are thermalized while others are still relaxing, prevails in most of these reactions. The individual degrees of freedom that have been explored experimentally are considered in their statistical equilibrium limit, and the extent to which they appear to be thermalized is discussed. The interaction between degrees of freedom on their way towards equilibrium is shown to create complex feedback phenomena that may lead to self-regulation. A possible example of self-regulation is shown for the process of energy partition between fragments promoted by particle exchange. 35 references.
Date: August 1, 1983
Creator: Moretto, Luciano G.
System: The UNT Digital Library
Ion microstability in tandem mirrors (open access)

Ion microstability in tandem mirrors

The formalism describing ion-cyclotron modes in mirror traps will be developed. Emphasis will be placed on the effects of finite axial boundaries on the normal modes of the system. Wave properties are a composite picture of: positive energy waves (plasma oscillation, shear Alfven and drift waves), negative energy waves (ion Bernstein waves in a loss-cone media), positive dissipation (electron Landau damping, outgoing waves), and negative dissipation (ion cyclotron damping in a loss-cone and anisotropic temperature medium). Stability boundaries in this bounded media is affected by scale lengths along the magnetic field; first, because they determine the widths of the resonances, and second, because they restrict the parallel structure of the modes.
Date: August 29, 1983
Creator: Pearlstein, L.D.
System: The UNT Digital Library
Application of the implicit Fourier-expansion method to the calculation of three-dimensional equilibria by the iterative method (open access)

Application of the implicit Fourier-expansion method to the calculation of three-dimensional equilibria by the iterative method

The iterative method of finding solutions to three-dimensional equilibria is discussed. The implicit Fourier-expansion method is briefly described and applied to the linear problems arising in the iterative loops. The paper shows how to efficiently solve for the magnetic field induced by the plasma.
Date: August 1, 1983
Creator: Shestakov, A.I.
System: The UNT Digital Library
Factorisation of long distance contributions to the Drell-Yan cross section (open access)

Factorisation of long distance contributions to the Drell-Yan cross section

We review the status of the hypothesis that all long distance contributions to the Drell-Yan cross section can be absorbed into parton distribution functions.
Date: August 1, 1983
Creator: Sachrajda, C.T.
System: The UNT Digital Library
Magnetic-mirror principle as applied to fusion research (open access)

Magnetic-mirror principle as applied to fusion research

A tutorial account is given of the key physics issues in the confinement of high temperature plasma in magnetic mirror systems. The role of adiabatic invariants and particle drifts and their relationship to equilibrium and stability are discussed, in the context of the various forms of mirror field geometry. Collisional effects and the development and the control of ambipolar potentials are reviewed. The topic of microinstabilities is discussed together with the means for their control. The properties and advantages for fusion power purposes of various special embodiments of the mirror idea, including tandem mirrors, are discussed.
Date: August 11, 1983
Creator: Post, Richard F.
System: The UNT Digital Library
Neutral beams for mirrors (open access)

Neutral beams for mirrors

An important demonstration of negative ion technology is proposed for FY92 in the MFTF-..cap alpha..+T, an upgrade of the Mirror Fusion Test Facility at the Lawrence Livermore National Laboratory. This facility calls for 200-keV negative ions to form neutral beams that generate sloshing ions in the reactor end plugs. Three different beam lines are considered for this application. Their advantages and disadvantages are discussed.
Date: August 31, 1983
Creator: Fink, J.H.
System: The UNT Digital Library
Summary of modeling studies of the Krafla geothermal field, Iceland (open access)

Summary of modeling studies of the Krafla geothermal field, Iceland

A comprehensive modeling study of the Krafla geothermal field in Iceland has been carried out. The study consists of four tasks: the analysis of well test data, modeling of the natural state of the field, the determination of the generating capability of the field, and modeling of well performance. The results of all four tasks are consistent with field observations.
Date: August 1, 1983
Creator: Bodvarsson, G. S.; Pruess, K.; Stefansson, V. & Eliasson, E. T.
System: The UNT Digital Library