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Equivalence of two formalisms for calculating higher order synchrotron sideband spin resonances (open access)

Equivalence of two formalisms for calculating higher order synchrotron sideband spin resonances

Synchrotron sideband resonances of a first order spin resonance are generally regarded as the most important higher order spin resonances in a high-energy storage ring. Yokoya's formula for these resonances is rederived, including some extra terms, which he neglected, but which turn out to be of comparable magnitude to the terms retained. Including these terms, Yokoya's formalism and the SMILE algorithm are shown to be equivalent to leading order in the resonance strengths. The theoretical calculations are shown to agree with certain measurements from SPEAR.
Date: May 11, 1988
Creator: Mane, S.R.
System: The UNT Digital Library
Final focus plasma lenses in linear colliders (open access)

Final focus plasma lenses in linear colliders

In this paper we analyze the optics of a high energy beam which is focused by its own wake-fields in an overdense plasma. We calculate the effects of lens aberration on the focusing strength of the lens and on the dilution of the beam's phase space density. From this we derive the minimum spot size achievable using a cylindrically symmetric bi-Gaussian beam and, after inclusion of the beam-beam disruption effect, the luminosity enhancement that can be gained in principle. We estimate the luminosity enhancement in the case of SLC design parameters and discuss limitations and possible improvements in plasma lens performance. Motivated by the need to reduce the background event rate due to beam-ion collisions, we discuss the optics of the underdense plasma lens and introduce the concept of bootstrap disruption. Possible use of the underdense plasma lens in a TLC-type collider is examined. 14 refs., 5 figs., 1 tab.
Date: October 11, 1988
Creator: Rosenzweig, J.B. & Chen, Pisin
System: The UNT Digital Library
A general purpose calibration facility for use in x-ray astronomy (open access)

A general purpose calibration facility for use in x-ray astronomy

An x-ray calibration facility for use in the 0.2--25 keV region is described. The facility employs several types of specially modified sources and detectors to produce and detect both line and continuum radiation in this energy range. We describe an inexpensive commercial x-ray source which has been modified for efficient high intensity operation as well as production of x-rays up to 25 keV. We also describe a system that utilizes multilayer mirrors alone or in a double Bragg geometry to select an energy bandpass. This system is controlled by a microcomputer which translates and rotates the multilayers to provide an easily selectable monochromatic beam with good resolution over a broad energy range. A long focal length Kirkpatrick--Baez mirror pair has been coupled to a pivoting beam line in order to accurately characterize gratings for use in soft x-ray astronomy. The beam line is scanned through the various grating orders. All aspects of the facility incorporate high degree of flexibility so that a wide variety of calibrations can be easily performed. 12 refs., 5 figs.
Date: August 11, 1988
Creator: Craig, W. W.; Hailey, C. J.; Morales, R. I.; Kahn, S. M. & Wargelin, B. J.
System: The UNT Digital Library
Improvements in power, precision, and shot rate from the Nova target irradiation facility (open access)

Improvements in power, precision, and shot rate from the Nova target irradiation facility

Recent improvements in the Nova amplifier system allow us to deliver higher energy and power to targets and to perform experiments with higher precision. Improved operating efficiency has increased the shot rate. 4 refs., 2 figs.
Date: November 11, 1988
Creator: Speck, D. R.; Bibeau, C.; Ehrlich, R. B.; Henesian, M. A.; Hermes, G. L.; Kyrazis, D. T. et al.
System: The UNT Digital Library
Dynamical evolution of cosmic strings (open access)

Dynamical evolution of cosmic strings

The author have studied by means of numerical simulations the dynamical evolution of a network of cosmic strings, both in the radiation and matter era. Our basic conclusion is that a scaling solution exists, i.e., the string energy density evolves as t/sup -2/. This means that the process by which long strings dump their energy into closed loops (which can gravitationally radiate away) is efficient enough to prevent the string domination over other forms of energy. This conclusion does not depend on the initial string energy density, nor on the various numerical parameters. On the other hand, the generated spectrum of loop sizes does depend on the value of our numerical lower cutoff (i.e., the minimum length of loop we allow to be chopped off the network). Furthermore, the network evolution is very different from what was assumed before), namely the creation of a few horizon sized loops per horizon volume and per hubble time, which subsequently fragment into about 10 smaller daughter loops. Rather, many tiny loops are directly cut from the network of infinite strings, and it appears that the only fundamental scale (the horizon) has been lost. This is probably because a fundamental ingredient had been overlooked, …
Date: May 11, 1988
Creator: Bouchet, F. R.
System: The UNT Digital Library
Non-linear scale invariance in a cold-dark-matter universe (open access)

Non-linear scale invariance in a cold-dark-matter universe

The observed decomposition of the lowest (N = 3,4) N-point correlation functions in symmetrized (N - 1) products of two-point correlation functions suggest the possibility that the Universe may obey a specific scale invariance, at least in some range. Assuming that this scale invariance is strictly verified for all N, some specific predictions concerning the void probability function P(sub O), and more generally the count probabilities P(sub N), as well as the fractal dimensions of the system can be made. In this report, the authors investigate the possibility that the non-linear evolution in a CDM Universe indeed to such a scale invariance.
Date: May 11, 1988
Creator: Bouchet, F. R.
System: The UNT Digital Library
Palladium on kieselguhr (open access)

Palladium on kieselguhr

Palladium supported in kieselguhr (Pd/K) is a candidate material for processing of hydrogen isotopes at Savannah River Laboratory (SRL) and Savannah River Plant (SRP). Kieselguhr is a porous, sedimentary rock composed of silicified skeletal remains of single-celled aquatic plants called diatoms. SRL has developed a process for deposition of palladium on kieselguhr particles using immersion in an ammonical palladium chloride solution followed by heating in hydrogen to decompose the chloride to metallic palladium. The goal is to produce Pd/K particles with less than 250 ppm chlorine.
Date: January 11, 1988
Creator: Mosley, W. C.
System: The UNT Digital Library
The classical nova outburst. [None] (open access)

The classical nova outburst. [None]

The classical nova outburst occurs on the white dwarf component in a close binary system. Nova systems are members of the general class of cataclysmic variables and other members of the class are the Dwarf Novae, AM Her variables, Intermediate Polars, Recurrent Novae, and some of the Symbiotic variables. Although multiwavelength observations have already provided important information about all of these systems, in this review I will concentrate on the outbursts of the classical and recurrent novae and refer to other members of the class only when necessary. 140 refs., 1 tab.
Date: April 11, 1988
Creator: Starrfield, S. G.
System: The UNT Digital Library