The Fermilab upgrade (open access)

The Fermilab upgrade

This paper discusses the upgrades needed at Fermilab Tevatron facility to meet the future physics needs. Historical aspects are also discussed. 3 figs.
Date: September 25, 1988
Creator: Lederman, L.M.
System: The UNT Digital Library
Synthesis of Accretion Disk and Nonthermal Source Models for AGN (open access)

Synthesis of Accretion Disk and Nonthermal Source Models for AGN

A scenario for the central engine of AGN has been developed consisting of a massive black hole (MBH) onto which gas accretes through an accretion disk. The accretion disk radiates the observed optical and ultraviolet continua. Surrounding the MBH is a nonthermal source which produces the infrared and soft x-ray continua by synchrotron emission, and the x-ray spectrum by inverse Compton scattering of the optical-ultraviolet photons from the accretion disk. Previously we modeled the accretion disk (M.A.M.) and nonthermal source (D.L.B.) separately, and here we combine the two models to form a unified description of the AGN engine. This combined model can be inverted to determine source parameters from observed spectra. A group of AGN for which multiband observations exist can then be modeled to: demonstrate the validity of the combined model for a large number of objects; establish the range of parameter values that describe the source; and search for any correlations between source description and type.
Date: May 25, 1988
Creator: Band, D. L. & Malkan, M. A.
System: The UNT Digital Library
Atomic processes in matter-antimatter interactions (open access)

Atomic processes in matter-antimatter interactions

Atomic processes dominate antiproton stopping in matter at nearly all energies of interest. They significantly influence or determine the antiproton annihilation rate at all energies around or below several MeV. This article reviews what is known about these atomic processes. For stopping above about 10 eV the processes are antiproton-electron collisions, effective at medium keV through high MeV energies, and elastic collisions with atoms and adiabatic ionization of atoms, effective from medium eV through low keB energies. For annihilation above about 10 eV is the enhancement of the antiproton annihilation rate due to the antiproton-nucleus coulomb attraction, effective around and below a few tens of MeV. At about 10 eV and below, the atomic rearrangement/annihilation process determines both the stopping and annihilation rates. Although a fair amount of theoretical and some experimental work relevant to these processes exist, there are a number of energy ranges and material types for which experimental data does not exist and for which the theoretical information is not as well grounded or as accurate as desired. Additional experimental and theoretical work is required for accurate prediction of antiproton stopping and annihilation for energies and material relevant to antiproton experimentation and application.
Date: January 25, 1988
Creator: Morgan, D. L.
System: The UNT Digital Library
Cryogenic analysis of forced-cooled, superconducting TF magnets for compact tokamak reactors (open access)

Cryogenic analysis of forced-cooled, superconducting TF magnets for compact tokamak reactors

Current designs for compact tokamak reactors require the toroidal- field (TF) superconducting magnets to produce fields from 10 to 15 T at the winding pack, using high-current densities to high nuclear heat loads (greater than 1 kW/coil in some instances), which are significantly greater than the conduction and radiation heat loads for which cryogenic systems are usually designed. A cryogenic system for the TF winding pack for two such tokamak designs has been verified by performing a detailed, steady-state heat-removal analysis. Helium properties along the forced-cooled conductor flow path for a range of nuclear heat loads have been calculated. The results and implications of this analysis are presented. 12 refs., 6 figs.
Date: October 25, 1988
Creator: Kerns, J. A.; Slack, D. S. & Miller, J. R.
System: The UNT Digital Library
Measurements of Neutrons in Enclosures and Outside of Shielding at the Tevatron (open access)

Measurements of Neutrons in Enclosures and Outside of Shielding at the Tevatron

The characteristics of the spectra of neutrons produced by the losses of accelerated proton beams both within accelerator enclosures and outside of shielding has been determined from measurements at various locations around the Fermilab Tevatron and its associated experimental areas. The measurements were performed with a multisphere spectrometer consisting of either /sup 6/LiI scintillators or /sup 6,7/LiF TLD's placed at the centers of moderating polyethylene spheres with diameters ranging from 5.08 to 45.7 cm. The fluence and dose equivalent energy distributions and average quality factors obtained from spectrum unfolding calculations are summarized for this accelerator environment. 22 refs., 8 figs., 3 tabs.
Date: August 25, 1988
Creator: Cossairt, J. D.; Elwyn, A. J.; Freeman, W. S.; Salsbury, W. C. & Yurista, P. M.
System: The UNT Digital Library
Dynamical Processes in Heavy Ion Reactions (open access)

Dynamical Processes in Heavy Ion Reactions

In this report I review the physical assumptions of the Boltzmann Master Equation (BME). Comparisons of the model with experimental neutron spectra gated on evaporation residues for a range of incident projectile energies and masses are presented; next, I compare n spectra gated on projectile-like fragments, followed by comparisons with ungated, inclusive proton spectra. I will then consider secondary effects from the nucleon-nucleon processes involved in the heavy ion relaxation processes, specifically the high energy ..gamma..-rays which have been observed at energies up to 140 MeV in collisions of heavy ions of 20/endash/84 MeV/..mu... Another secondary effect, subthreshold pion production, was covered in the XVII School and will not be repeated. 39 refs., 16 figs.
Date: July 25, 1988
Creator: Blann, M. & Remington, B. A.
System: The UNT Digital Library