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17 tech notes:

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title: New Features in UCLA-PARMELA v 2.1
format: tech note
year: 2005
1 author: R. J. England
abstract: This document describes modifications to the UCLA-PARMELA source code version 2.0. The modifications were made by R. J. England during the period from 2003 to 2005. The changes to the code consist of: (1) the implementation of the "SEXT" card for sextupoles, and (2) changes to the "TRWAVE" card which permit the fields to be printed out to a data file. These changes are detailed in the following subsections. In addition, (3) I document the input structure for the CELL card in versions 2.0 and 2.1 since this was found to differ from the description given in the UCLA-PARMELA manual. The modified code version number has been increased to v 2.1.
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title: New Vacuum Chamber for the Plasma Density Transition-Trapping Experiment
format: tech note
year: 2003
2 authors: M. Schneider | M.C. Thompson
abstract: The plasma density transition trapping experiment is designed to capture an electron beam and modify its quality (emittance, energy spread, and brightness) via a plasma wake-field [1]. The Particle Beam Physics Laboratory (PBPL) transition-trapping plasma experiment requires a chamber to support the confined plasma source, in-vacuum diagnostics and associated hardware. Initial measurements on the plasma source utilized a chamber initially created for an underdense plasma lens experiment [2]. However, current research and future positioning of the plasma source required drastic improvements of nearly all facets of the chamber design. The initial plan was to rearrange the plasma source to move the interaction box onto the opposite side of the pumping-Tee (see picture below). This proved successful to measure plasma densities at or above the required value to carry out the plasma transition-trapping experiment. However, because the original design of the interaction box did not have an exit port for the beamline, a new box design became necessary. A decision was made to redesign the plasma chamber from scratch. The proposed design and specifications are described in this note.
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title: Design Considerations for the UCLA PBPL Slit-based Phase Space Measurement Systems
format: tech note
year: March 2, 1994
2 authors: J.B. Rosenzweig | G. Travish
abstract: The phase space measurement system initially implemented by Spencer Hartmann on the UCLA PBPL rf photocathode gun has been upgraded, and a new system has been designed to measure the emittance at higher energy, after the emittance compensating drift and acceleration in the PWT linac. The purpose of this note is to describe the design criteria and physical principles involved in obtaining systems which provide the resolution in phase space measuremtns that we require. The final lit and detectro hardware designs are included; the video data acquisition and analysis will remain nearly unchanged from Hartmann's system.
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title: Considerations for Conical Horn Antenna Design optimizing Cerenkov radiation from hollow cylindrical dielectric tube
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year: 2004
1 author: H. Badakov
abstract:
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title: Multibunch Operation of the 1GeV Machine
format: tech note
year: 1988
3 authors: Sessler, A. M. | G. Travish | S. Yu
abstract:
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title: Faraday Cup Beam Dumps for the UCLA PBPL
format: tech note
year: May 16, 1994
1 author: D. H. McIntosh
abstract: Two identical Faraday cups have been designed and built to stop a 20 meV, 1 nC electron pulse beam, accelerated at the UCLA Particle Beam Physics Laboratory (PBPL). The dumps were also designed to serve as charge measuring diagnostics. Each device is a simple design using a carbon graphite core, Delrin insulation, vacuum tubing components, and lead brick shielding. The graphite core stops the beam while producing manageable secondary radiation sources. The overall design considerations and final solutions are summarized.
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title: The Beam Break-Up Numerical Simulator
format: tech note
year: 1990
1 author: G. Travish
abstract: Beam Break-Up (BBU) is a severe constraint in accelerator design, limiting beam current and quality. The control of BBU has become the focus of much research in the design of the next generation collider, recirculating and linear induction accelerators and advanced accelerators. Determining the effect on BBU of modifications to cavities, the focusing elements or the beam is frequently beyond the ability of current analytic models. A computer code was written to address this problem. The Beam Break-Up Numerical Simulator (BBUNS) was designed to numerically solve for beam break-up (BBU) due to an arbitrary transverse wakefield. BBUNS was developed to be as user friendly as possible on the Cray computer series. The user is able to control all aspects of input and output by using a single command file. In addition, the wakefield is specified by the user and read in as a table. The program can model energy variations along and within the beam, focusing magnetic field profiles can be specified, and the graphical output can be tailored. In this note we discuss BBUNS, its structure and application. Included are detailed instructions, examples and a sample session of BBUNS. This program is available for distribution.
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title: Optical Transition Radiation
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year: 1992
1 author: B. Gitter
abstract: The use of Optical Transition Radiation (OTR) as an on-line diagnostic system for the UCLA Particle Beam Physics Lab electron beam has been investigated. Beam divergence, energy and profile are some of the properties which have been theoretically and experimentally (past works) shown to be analyzable and measurable from OTR patterns. Calculations regarding the survivability of both the beam and the OTR target are made for various beam energies and target materials. It is found that a 20 MeV beam passing through a thin aluminum target will be unperturbed, in terms of energy and angular divergence, and the target will not be destroyed. Finally, the use of an OTR double-foil interferometer, as a more precise diagnostic tool, is presented for future consideration.
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title: Operating Procedure for Saturnus Modulator
format: tech note
year: 1990
2 authors: Terrien, C. | S. Park
abstract:
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title: Beam Break-Up in a KEK TBA
format: tech note
year: 1989
2 authors: D. Whittum | G. Travish
abstract:
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title: Procedure for the production of a 10 micron aluminum foil OTR window
format: tech note
year: 2004
1 author: M.C. Thompson
abstract:
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title: UCLA PBPL Safety Interlock System Description and Operation Manual
format: tech note
year: 1996
1 author: G. Andonian
abstract: http://pbpl.physics.ucla.edu/Research/Facilities/_PEGASUS/Tech_Notes/Pegasus_Safety_Interlock_System/
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title: Operating Procedures for the UCLA Linear Accelerator Facility
format: tech note
year: February 14, 1991
2 authors: C. Pellegrini | C. Joshi
abstract: An RF laser-driven electron gun is being built at UCLA. This electron injector will be used to study the production of high-brightness electron beams, and to drive a high gain, free-electron laser amplifier. Other particle beam physics experiments include plasma wakefiled acceleration. All these experiments are performed under the umbrella of the Center for Advanced Accelerators located at the UCLA Linear Accelerator Laboratory.
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title: UCLA Neptune CTR Interferometer
format: tech note
year: 2005
1 author: R. J. England
abstract: The purpose of this document is to outline the basic operating theory behind the coherent transition radiation (CTR) interferometry technique employed at the UCLA Neptune Laboratory for diagnosing the bunch length of the electron beam produced by the Neptune 1.6-cell gun and PWT accelerating structure. General theoretical results are presented and then applied specifically to the Neptune interferometer developed by Uwe Happek, which we refer to henceforth as the Uwefarometer. Particular attention is paid to understanding the theory of the wire-grid polarizers which are used in the Uwefarometer to split and recombine the terahertz CTR radiation.
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title: Neptune Second Harmonic Generation Autocorrelator
format: tech note
year: 2005
1 author: R. J. England
abstract: This document provides detailed information on the basic theoretical knowledge required to understand the operational principles of the Second Harmonic Generation Autocorrelator used for measuring the pulse length of the infrared drive laser at the Neptune Laboratory. This autocorrelator was originally assembled by Kari Sanders and Sergei Tochitsky ca. 2000-2001. Some information about its operation may be found in Kari Sanders' master's thesis. In short, the autocorrelator operates by splitting the infrared (1064nm) pulse produced by the Neptune regenerative amplifier and grating compressor and then crossing the two split pulses inside of a nonlinear KDP crystal, via a Type I "ooe" interaction, to produce noncollinear second harmonic frequency upconversion to green (532 nm). The intensity of the green as a function of the delay between the two split pulses produces the autocorrelation of the pulse, which can be used to extract the pulse length and (to some extent) the time structure of the pulse. The theory of autocorrelation will not be discussed in this document.
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title: Micro Pyroelectric Electron Gun
format: tech note
year: 2008
1 author: Urd Horberg Lacroix
abstract: This paper describes an ongoing experiment for construction of a ferroelectric micro electron gun with kinetic energies of 25keV. Described are concepts on electron emission and acceleration with emphasis on using pyroelectric crystals as an electron source. A setup has been build to test pyroelectric crystals as emitters and as generators of electric fields for electron acceleration. The purpose of constructing a micro electron gun is to use it as a part of a high gradient laser powered micro accelerating platform capable of accelerating electrons to energies of ~1 - 2MeV. The construction of this platform is an ongoing project by R. B. Yoder, G. Travish and J. B. Rosenzweig.[2] The applications of an inexpensive near relativistic micro electron source are manifold and include the possibility of treating cancer with electron or X-ray radiation directly at the tumor[12] Ferroelectric electron emission have been studied by many including Rosenman[1] and Brownridge[4] all in which the emitting crystals are much larger than the crystal proposed for the micro gun. So one of the great challenges for this experiment is to measure electron emission from micro crystals. The minimum beam energy for the emitted electrons is approximately 25keV, which is the threshold energy in which the electrons can be accelerated in the laser field. Hence another challenge of this project is to provide a field of at least 25keV.
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title: Polarization Gating Autocorrelator
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year:
4 authors: M. S. Gutierrez | P. Musumeci | C. M. Scoby | J. T. Moody
abstract: We have developed a portable, motorized, multi-shot, third-order autocorrelator capable of measuring the time width of a large bandwidth pulse with femtosecond acuracy. Here we give a detailed description of the device and report measurements made in the Pegasus laboratory on a Coherent Legend Elite laser system, generating a short, (IR) $\lambda=800nm$ $E \sim 3mJ$, and a frequency tripled pulse, (UV) $\lambda= 266nm$ $E \sim 300\mu J$. Pulse lengths were determined to be 35fs and 90fs for the IR and UV pulses respectively. For a calibration we measured the index of refraction for a $\frac{1}{4}$in fused silica window, these results where in good agreement to sellmeier equation with coefficients obtained from 'CVI Melles Griot' website. Furthermore, we measured the dispersion of the IR and UV pulses through the fused silica to justify the assumption of a gaussian pulse with a trivial phase factor.
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