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Beamstrahlung monitors at SLC (open access)

Beamstrahlung monitors at SLC

Some properties of beamstrahlung are discussed, and plans to observe the effect at SLC by the use of Cherenkov counters are illustrated.
Date: March 1, 1987
Creator: Field, R. C.
System: The UNT Digital Library
Status of ECR (Electron Cyclotron Resonance) source technology (open access)

Status of ECR (Electron Cyclotron Resonance) source technology

ECR (Electron Cyclotron Resonance) ion sources are now in widespread use for the production of high quality multiply charged ion beams for accelerators and atomic physics experiments, and industrial applications are being explored. Several general characteristics of ECR sources explain their widespread acceptance. For use with cyclotrons which require CW multiply charged ion beams, the ECR source has many advantages over heavy-ion PIG sources. Most important is the ability to produce higher charge states at useful intensities for nuclear physics experiments. Since the maximum energy set by the bending limit of a cyclotron scales with the square of the charge state, the installation of ECR sources on cyclotrons has provided an economical path to raise the energy. Another characteristic of ECR sources is that the discharge is produced without cathodes, so that only the source material injected into an ECR source is consumed. As a result, ECR sources can be operated continuously for periods of weeks without interruption. Techniques have been developed in the last few years, which allow these sources to produce beams from solid materials. The beam emittance from ECR sources is in the range of 50 to 200 ..pi.. mm-mrad at 10 kV. The principles of ECR …
Date: March 1, 1987
Creator: Lyneis, C.M.
System: The UNT Digital Library
Field measuring probe for SSC (Superconducting Super Collider) magnets (open access)

Field measuring probe for SSC (Superconducting Super Collider) magnets

The field probe developed for measuring the field in SSC dipole magnets is an adaptation of the rotating tangential coil system in use at Brookhaven for several years. Also known as the MOLE, it is a self-contained room-temperature mechanism that is pulled through the aperture of the magnet with regular stops to measure the local field. Several minutes are required to measure the field at each point. The probe measures the multipole components of the field as well as the field angle relative to gravity. The sensitivity of the coil and electronics is such that the field up to the full 6.6 T excitation of the magnet as well as the field when warm with only 0.01 T excitation can be measured. Tethers are attached to both ends of the probe to carry electrical connections and to supply dry nitrogen to the air motors that rotate the tangential windings as well as the gravity sensor. A small computer is attached to the probe for control and for data collection, analysis and storage. Digital voltmeters are used to digitize the voltages from the rotating coil and several custom circuits control motor speeds in the probe. The overall diameter of the probe …
Date: March 1, 1987
Creator: Ganetis, G.; Herrera, J.; Hogue, R.; Skaritka, J.; Wanderer, P. & Willen, E.
System: The UNT Digital Library
Pulsers for the induction linac experiment, MBE-4 (open access)

Pulsers for the induction linac experiment, MBE-4

The MBE-4 proof-of-principle experiment uses an induction linac to accelerate four Cs+ beams from injection at 200 kV to almost 1MV. When completed in the summer of 1987 it will be 17.2 meters long and have 24 acceleration gaps and 6 diagnostic gaps. Careful tailoring of the accelerating voltage waveforms at each gap is required to accelerate the beam, amplify the current and provide longitudinal focusing. The ideal voltage waveforms required at the first 4 gaps are almost triangular with an amplitude of about 20 kV and an approximate width of 3 ..mu..sec, becoming flatter and shorter with an amplitude of 30 kV at subsequent gaps as the beam current increases and the pulse width narrows. These waveforms (1) are shown in Fig. 1. Pulser voltage waveforms at each gap are adjusted in both amplitude and firing time in conjunction with beam experiments to determine the required voltage waveforms of the subsequent pulsers. Existing cores and previous experience with thyratron pulsers provided the basis for the pulsers for the first half of the machine. During this fabrication period, additional cores and spark gap pulsers capable of generating higher voltages than the thyratron pulsers became available and a combination of both …
Date: March 1987
Creator: Gough, D.; Brodzik, D.; Faltens, A.; Pike, C. & Stoker, J.
System: The UNT Digital Library
Electroweak radiative corrections and neutral current phenomenology (open access)

Electroweak radiative corrections and neutral current phenomenology

Precision measurements of sin/sup 2/ theta/sub W/ including the effects of radiative corrections are surveyed. A world average sin/sup 2/ theta/sub W/ = 0.231 +- 0.004 is obtained. Comparison of deep-inelastic nu/sub ..mu../N scattering and m/sub W/ or m/sub Z/ is shown to test the standard model at the quantum loop level and constrain new physics. Implications for extra Z' bosons and grand unified theories are briefly discussed. 25 refs., 2 figs.
Date: March 1, 1987
Creator: Marciano, William J.
System: The UNT Digital Library
The Light Ion Biomedical Research Accelerator (LIBRA) (open access)

The Light Ion Biomedical Research Accelerator (LIBRA)

LIBRA is a concept to place a light-ion, charged-particle facility in a hospital environment, and to dedicate it to applications in biology and medicine. There are two aspects of the program envisaged for LIBRA: a basic research effort coupled with a program in clinical applications of accelerated charged particles. The operational environment to be provided for LIBRA is one in which both of these components can coexist and flourish, and one that will promote the transfer of technology and knowledge from one to the other. In order to further investigate the prospects for a Light Ion Biomedical Research Accelerator (LIBRA), discussions are underway with the Merritt Peralta Medical Center (MPMC) in Oakland, California, and the University of California at San Francisco (UCSF). In this paper, a brief discussion of the technical requirements for such a facility is given, together with an outline of the accelerator technology required. While still in a preliminary stage, it is possible nevertheless to develop an adequate working description of the type, size, performance and cost of the accelerator facilities required to meet the preliminary goals for LIBRA.
Date: March 1, 1987
Creator: Gough, R.A.
System: The UNT Digital Library
An overview of copper-laser development for isotope separation (open access)

An overview of copper-laser development for isotope separation

We have developed a copper-laser pumped dye-laser system that addresses all of the requirements for atomic vapor laser isotope separation. The requirement for high average power for the laser system has led to the development of copper-laser chains with injection-locked oscillators and multihundred-watt amplifiers. By continuously operating the Laser Demonstration Facility, we gain valuable data for further upgrade and optimization.
Date: March 13, 1987
Creator: Warner, B.E.
System: The UNT Digital Library
Measurement of electron beam polarization at the SLC (open access)

Measurement of electron beam polarization at the SLC

The polarimeters needed to monitor and measure electron beam polarization at the Stanford Linear Collider are discussed. Two types of polarimeters, are to be used. The first is based on the spin dependent elastic scattering of photons from high energy electrons. The second utilizes the spin dependence of elastic electron-electron scattering. The plans of the SLC polarization group to measure and monitor electron beam polarization are discussed. A brief discussion of the physics and the demands it imposes on beam polarization measurements is presented. The Compton polarimeter and the essential characteristics of two Moeller polarimeters are presented. (LEW)
Date: March 1, 1987
Creator: Steiner, H.
System: The UNT Digital Library
Drift chamber vertex detectors for SLC/LEP (open access)

Drift chamber vertex detectors for SLC/LEP

The short but measurable lifetimes of the b and c quarks and the tau lepton have motivated the development of high precision tracking detectors capable of providing information on the decay vertex topology of events containing these particles. This paper reviews the OPAL, L3, and MARK II experiments vertex drift chambers.
Date: March 1, 1987
Creator: Hayes, K.G.
System: The UNT Digital Library
Operating Results for the Beam Profile Monitor System Currently in Use at Bevalac Facility (open access)

Operating Results for the Beam Profile Monitor System Currently in Use at Bevalac Facility

Three stations of a soon to be completed multi-station, multi-wire beam monitoring system have been installed in the Bevalac transfer line. The following article will provide a cursory analysis of the electronic circuitry, discuss new design additions and summarize the operating results obtained over the last year.
Date: March 1987
Creator: Stover, G. & Fowler, K.
System: The UNT Digital Library
Simulation of space charge effects and transition crossing in the Fermilab Booster (open access)

Simulation of space charge effects and transition crossing in the Fermilab Booster

The longitudinal phase space program ESME, modified for space charge and wall impedance effects, has been used to simulate transition crossing in the Fermilab Booster. The simulations yield results in reasonable quantitative agreement with measured parameters. They further indicate that a transition jump scheme currently under construction will significantly reduce emittance growth, while attempts to alter machine impedance are less obviously beneficial. In addition to presenting results, this paper points out a serious difficulty, related to statistical fluctuations, in the space charge calculation. False indications of emittance growth can appear if care is not taken to minimize this problem.
Date: March 1, 1987
Creator: Lucas, P. & MacLachlan, J.
System: The UNT Digital Library
The magnet lattice of the LBL 1-2 GeV Synchrotron Radiation Source (open access)

The magnet lattice of the LBL 1-2 GeV Synchrotron Radiation Source

This paper describes the magnet chosen for the LBL 1-2 GeV Synchrotron Radiation Source. The structure has a circumference of 196.8 m, with 12 dispersion free straight sections that can accommodate insertion devices up to 5 m long. The achromatic arcs that connect these straight sections feature combined function (gradient) bending magnets. Utilization of three such magnets in the so-called three-bend-achromat (TBA) arrangement, has several beneficial effects: (1) it reduces the amplitude of the vertical beta-function in the bending magnets, thereby minimizing the required aperture; (2) it changes the damping partition number in such a way as to reduce the natural emittance; and (3) it produces separation of the beta-functions such that relatively low sextupole strengths are sufficient for chromatic correction. The result is a structure with very low emittance (4 nm-rad at 1.5 GeV) that is correctable with only two families of sextupoles while maintaining excellent chromatic properties and acceptable dynamic aperture. In this paper we describe the details of the storage ring and discuss the characteristic features of the lattice.
Date: March 1, 1987
Creator: Jackson, A.
System: The UNT Digital Library
The effect of nonlinear forces on coherently oscillating space-charge-dominated beams (open access)

The effect of nonlinear forces on coherently oscillating space-charge-dominated beams

A particle-in-cell computer simulation code has been used to study the transverse dynamics of nonrelativistic misaligned space-charge-dominated coasting beams in an alternating gradient focusing channel. In the presence of nonlinear forces due to dodecapole or octupole imperfections of the focusing fields or to image forces, the transverse rms emittance grows in a beat pattern. Analysis indicates that this emittance dilution is due to the driving of coherent modes of the beam near their resonant frequencies by the nonlinear force. The effects of the dodecapole and images forces can be made to effectively cancel for some boundary conditions, but the mechanism is not understood at this time.
Date: March 1, 1987
Creator: Celata, C. M.
System: The UNT Digital Library
Experimental Measurement of Emittance Growth in Mismatched Space-Charge-Dominated Beams (open access)

Experimental Measurement of Emittance Growth in Mismatched Space-Charge-Dominated Beams

Using the Single Beam Transport Experiment (SBTE) at LBL, we have measured the emittance of a well-matched 4.6-mA beam of 122-keV Cs/sup +/ to be conserved from injection into through exit from an 80-lens segment of the AG focussing channel. We then mismatched the beam into the same channel such that the maximum (minimum) radius of the beam at the midplane between lenses was about 1.5 (0.5) times the former value. We caused mismatches in the envelope of the beam in both transverse dimensions (labeled a and b) in modes both symmetric (deltaa = deltab) and antisymmetric (deltaa = -deltab). We found the mismatch amplitude to decay during the beam transit through the channel for both modes of mismatch, although more so for the antisymmetric mode. We also found the emittance of the symmetrically mismatched beam to be the same as for the matched beam, while the emittance of the antisymmetrically mismatched beam grew by as much as a factor of four over that for the matched beam.
Date: March 1987
Creator: Tiefenback, M. G.
System: The UNT Digital Library
Experimental search for W/Z pairs and Higgs bosons at very high energy hadron-hadron colliders (open access)

Experimental search for W/Z pairs and Higgs bosons at very high energy hadron-hadron colliders

We study, from an experimental point of view, the main ways to detect standard high mass Higgs bosons (from 300 GeV up to about 1 TeV) when they decay into W- and Z-pairs at the SSC. We also consider the corresponding W- and Z/sup 0/-pair continuum which may itself provide interesting physics, and we pay some attention to the case of an intermediate mass charged Higgs decaying into tau..nu../sub tau/ (m/sub H+-/ = 300 GeV). We first explain why and how high energy pp colliders may search for Higgs' and we compare their possible performances to those of the e/sup +/e/sup -/ and ep colliders at all possible mass scale (from few tens of GeV's up to 1 TeV). We then estimate the rates of the signals and the main backgrounds. We define the main characteristics of these events as reproduced by M.C. generators (especially implemented with these processes) and simulated through an idealized 4..pi.. fine-grained calorimeter. A trigger strategy for W- and Z-pairs is derived from this study. 26 refs., 28 figs.
Date: March 1, 1987
Creator: Alverson, G.; Bengtsson, H.U.; Hauptman, J.; Hedin, D.; Herrero, M.J.; Wang, E. et al.
System: The UNT Digital Library
Trapped ions and beam lifetime in NSLS (National Synchrotron Light Source) storage rings (open access)

Trapped ions and beam lifetime in NSLS (National Synchrotron Light Source) storage rings

Ion trapping observed in most electron storage rings causes various degree of deleterious effects both on brightness and on beam lifetime. Ion trapping is worst in the initial stages of operation when pressure due to synchrotron desorption is high. Based on these observations, various theories to explain the phenomenon have been developed. Depending on specific machines and on the seriousness of their problem, individualized cures have been adopted to eliminate or to cope with ion trapping. It is fair to say that the present understanding of ion trapping is incomplete partially due to lack of quantitative comparison between theory and experimental investigation and partially due to very different behavior among various machines. Preliminary results are presented of continuous studies to understand the ion trapping mechanism in the National Synchrotron Light Source (NSLS) electron storage rings.
Date: March 1, 1987
Creator: Chou, T.S. & Halama, H.J.
System: The UNT Digital Library
Z/sup 0/. -->. N/sub 4/ anti nu. -->. monojet (open access)

Z/sup 0/. -->. N/sub 4/ anti nu. -->. monojet

We discuss flavor-changing Z decays involving a heavy fourth generation neutrino with mass bigger than M/sub Z//2.
Date: March 1, 1987
Creator: Sun, Hong Rhie
System: The UNT Digital Library
Phase detector and phase feedback for a single bunch in a two-bunch damping ring for the SLAC Linear Collider (open access)

Phase detector and phase feedback for a single bunch in a two-bunch damping ring for the SLAC Linear Collider

The synchronous phase of a bunch of positrons or electrons being damped in a SLAC Linear Collider (SLC) damping ring is dependent on beam intensity. Injection for alternate bunches into the SLC linac from the damping rings should occur at a constant phase. A phase detector was developed allowing the measurement of phase of a single-stored bunch in the presence of a second bunch in reference to the phase of the linac. The single-bunch phase is derived from beam position monitor signals using a switching scheme to separate the two bunches circulating in each damping ring. The hardware is described including feedback loops to stabilize the extraction phase.
Date: March 1, 1987
Creator: Schwarz, H.D. & Judkins, J.G.
System: The UNT Digital Library
Bounds on neutrino masses from particle physics and cosmology (open access)

Bounds on neutrino masses from particle physics and cosmology

We study the constraints imposed on the masses of nu/sub e/, nu/sub ..mu../ and nu/sub tau/ on the basis of direct experimental bounds, cosmological bounds, theoretical calculations of neutrino decay rates, experimental bounds on related decays of charged leptons and the structure of neutrino mass matrices in the ''see-saw'' mechanism. We consider standard model amplitudes as well as contributions from all ''beyond standard'' models. Assuming a simple ''reasonable'' form of the see-saw mechanism, we derive the bounds: m(nu/sub tau/) less than or equal to 65 eV, m(nu/sub ..mu../) less than or equal to 4 eV, m(nu/sub e/) less than or equal to 0.02 eV, M(W/sub R/) greater than or equal to 50 PeV.
Date: March 1, 1987
Creator: Nir, Y.
System: The UNT Digital Library
Perturbation method for the measurement of longitudinal and transverse beam impedance (open access)

Perturbation method for the measurement of longitudinal and transverse beam impedance

A perturbation method utilizing metallic and dielectric spheres to measure longitudinal and transverse beam and pickup impedances in accelerator components is described. The method was used to measure the longitudinal and transverse beam impedances of the 1 to 2 GeV light source beam pipe. In addition, the technique was used to measure the transverse pickup impedance of a 2 GHz cavity type Schottky signal monitor currently being installed in the FNAL Tevatron. Measurement results for both cases are presented.
Date: March 1, 1987
Creator: Barry, W. & Lambertson, G.R.
System: The UNT Digital Library
The geometry of continuum regularization (open access)

The geometry of continuum regularization

This lecture is primarily an introduction to coordinate-invariant regularization, a recent advance in the continuum regularization program. In this context, the program is seen as fundamentally geometric, with all regularization contained in regularized DeWitt superstructures on field deformations.
Date: March 1, 1987
Creator: Halpern, M.B.
System: The UNT Digital Library
Phenomenology of heavy quark systems (open access)

Phenomenology of heavy quark systems

The spectroscopy of heavy quark systems is examined with regards to spin independent and spin dependent potentials. It is shown that a qualitative picture exists of the spin-independent forces, and that a semi-quantitative understanding exists for the spin-dependent effects. A brief review is then given of the subject of the decays of hadrons containing heavy quarks, including weak decays at the quark level, and describing corrections to the spectator model. (LEW)
Date: March 1, 1987
Creator: Gilman, Frederick J.
System: The UNT Digital Library
CDF (Collider Detector at Fermilab) calorimetry (open access)

CDF (Collider Detector at Fermilab) calorimetry

The Collider Detector at Fermilab (CDF) is a large detector built to study 2 TeV anti p p collisions at the Fermilab Tevatron. The calorimetry, which has polar angle coverage from 2 to 178, and complete azimuthal coverage within this region, forms the subject of this paper. It consists of both electromagnetic shower counters (EM calorimeters) and hadron calorimeters, and is segmented into about 5000 ''towers'' or solid angle elements.
Date: March 1, 1987
Creator: Jensen, H.B.
System: The UNT Digital Library
Ignition physics study group support of the engineering test reactor program (open access)

Ignition physics study group support of the engineering test reactor program

This paper consists of a series of vugraphs concerning the Engineering Fast Reactor Program. Design goals for the reactor are discussed and presented graphically. (JDH)
Date: March 24, 1987
Creator: Sheffield, J.
System: The UNT Digital Library