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Impurity complex formation in ultra-pure germanium
Several unknown, hydrogenic acceptors and donors were recently discovered in ultra-pure germanium by photoelectric spectroscopy. These centers are not created by elemental impurities. Comparative analysis of a large number of crystals grown under various conditions lead to the conclusion that copper, a fast diffusing multivalent acceptor, together with lithium and/or hydrogen, is responsible for several of the unknown centers. This is the first time that hydrogen has been recognized as playing the role of a donor pairing with an acceptor. Hall effect measurements complementing the photoelectric spectroscopy results lead to a tentative assignment of the following energy levels: (Cu, Li) complexes: E/sub V/ + 20.5 meV/super */, E/sub V/ + 25.0 meV/super */, E/sub V/ + 275 meV(/super */hydrogenic acceptor); (Cu, H) complexes: E/sub V/ + 17.0 meV/super */, E/sub V/ + 17.5 meV/super */, E/sub V/ + 175 meV. Experiments which may help determine the structure of the complexes are proposed.
Date:
May 1, 1977
Creator:
Haller, E. E. & Hubbard, G. S.
System:
The UNT Digital Library
Calculation of higher order modes in the RHIC 27 MHz rf cavity
The URMEL code was used to calculate the frequencies, quality factors, and shunt impedances of the lowest modes of the proposed RHIC accelerating cavity. These values can be used as input for the calculation of the longitudinal and transverse coupled-bunch instabilities. The cavity dimensions were taken from the RHIC conceptual design report.
Date:
May 1, 1988
Creator:
Schoessow, P.
System:
The UNT Digital Library
Edge ion dynamics in H-mode discharges in DIII-D
The goal of this paper is to present detailed measurements of T{sub i} and E{sub r} at the plasma edge in L- and H-mode with high spatial resolution in order the study the edge ion dynamics. Of primary interest is the relationship between T{sub i} and E{sub r} and the behavior of the edge T{sub i} profile in H-mode. The principle findings are: there appears to be a threshold temperature for T{sub i} required for the transition to occur with T{sub i} at the LCFS in the range of 0.2--0.3 keV at the transition; a correlation between the edge E{sub r} profile and the edge T{sub i} profile has been observed; and values of T{sub i} of 2--3 keV within a few cm of the LCFS and of dT{sub i}/dr of up to 1 keV/cm are observed in the transport barrier in H-mode, with the scale length for T{sub i} being of the order of a poloidal gyroradius.
Date:
May 1, 1992
Creator:
Groebner, R. J.; Burrell, K. H.; Gohil, P.; Kim, J. & Seraydarian, R. P.
System:
The UNT Digital Library
Algorithms for the self-consistent simulation of high power klystrons
We discuss an improvement to the algorithm developed by Yu for modelling rf cavities in klystrons using the port approximation. In this method, the cavity is simulated by imposing an rf voltage as a boundary condition across the outer wall. The voltage and phase are chosen to be consistent with the cavity impedence and with the rf current induced by the electron beam. In the original method, each cavity was calculated successively using either linear theory or an iterative method to achieve a self-consistent voltage. The new method relaxes the voltage and phase of several cavities simultaneously during the simulation. The time dependence of the voltages are calculated from a relaxation equation. The new algorithm reduces the total computation time by about a factor of five for a complete klystron.
Date:
May 1, 1988
Creator:
Eppley, K.
System:
The UNT Digital Library
Effect of ion implantation on the corrosion behavior of lead and lead-antimony alloy
None
Date:
May 1, 1992
Creator:
Muller, R. H. & Zhang, S. T.
System:
The UNT Digital Library
Spectral quality of ALS U5. 0 undulator and field error effects
The first insertion device of the Advanced Light Source (ALS), a U5.0 undulator, has been carefully adjusted and qualified with a specially designed magnetic measurement system. The magnetic field of the undulator has been fully mapped at a series of gaps with very high accuracy. Based upon these measured field data, the authors evaluate the radiation spectral quality of this device in terms of an ideal sinusoidal device and examine the field error effects. Moreover, statistical correlation between the field errors and radiation degradation is examined by using the large quantity of magnetic field data sets accumulated in the process of adjusting and qualifying the U5.0 undulator.
Date:
May 1, 1993
Creator:
Wang, C.; Marks, S. & Kincaid, B.
System:
The UNT Digital Library
Hadron collisions at TEV energies
This paper discusses the need for higher energy accelerators to probe the mysteries of the subatomic universe. Intermediate vector bosons are discussed as well as symmetry breaking and the standard model. (LSP)
Date:
May 10, 1988
Creator:
Cahn, R. N.
System:
The UNT Digital Library
Performance of a total-flow impulse turbine for geothermal applications
A new, axial-flow impulse turbine was tested at LLL as part of the geothermal energy development program. Engine efficiency of this single-stage, two-phase expander was measured at 23% during a single-nozzle test. Performance predictions of a numerical model agreed with these results. Full-admission performance (based on the numerical-model and attainable nozzle thrust coefficients) indicates that engine efficiency can reach between 38 and 40% with present technology. Improved techniques for analyzing two-phase flow and further reduction of droplet sizes should provide 70% engine efficiency.
Date:
May 16, 1977
Creator:
Comfort, W. J., III
System:
The UNT Digital Library
Identification and decay of /sup 190/W, /sup 196/Os, /sup 230/Ra, and /sup 230/Ac. [Half-life]
Several new or poorly characterized neutron-rich nuclides were produced and studied at the Brookhaven Medium Energy Intense Neutron facility, MEIN. /sup 190/W decays with T/sub 1/2/ = 30.0 +- 1.5 min, E/sub beta/ = 0.93 +- 0.07 MeV, and ..gamma..'s of 157.6 and 162.1 keV. /sup 196/Os decays with T/sub 1/2/ = 35.0 +- 0.4 min and ..gamma..'s at 126.1, 200.7, 207.0, 257.0, 315.3, 407.6, 522.2, and 628.9 keV. /sup 230/Ra decays with T/sub 1/2/ = 93 +- 2 min to 122 +- 3 sec /sup 230/Ac; ..gamma..-ray energies and intensities are tabulated. A decay scheme is proposed for /sup 190/W, and many of the transitions following the decay of /sup 230/Ac are between known levels in /sup 230/Th.
Date:
May 19, 1976
Creator:
Katcoff, S.; Gilat, J.; Haustein, P. E.; Franz, E. M.; Morcos, N. A.; Ward, T. E. et al.
System:
The UNT Digital Library