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Infrared Frequency Selective Surfaces Fabricated using Optical Lithography and Phase-Shift Masks

Description: A frequency selective surface (FSS) structure has been fabricated for use in a thermophotovoltaic system. The FSS provides a means for reflecting the unusable light below the bandgap of the thermophotovoltaic cell while transmitting the usable light above the bandgap. This behavior is relatively independent of the light's incident angle. The fabrication of the FSS was done using optical lithography and a phase-shift mask. The FSS cell consisted of circular slits spaced by 1100 nm. The diameters and widths of the circular slits were 870 nm and 120 nm, respectively. The FSS was predicted to pass wavelengths near 7 {micro}m and reflect wavelengths outside of this pass-band. The FSSs fabricated performed as expected with a pass-band centered near 5 {micro}m.
Date: June 15, 2001
Creator: Spector, S.J.; Astolfi, D.K.; Doran, S.P.; Lyszczarz, T.M. & Raynolds, J.E.
Partner: UNT Libraries Government Documents Department

Characterization and Suppression of the Electromagnetic Interference Induced Phase Shift in the JLab FEL Photo - Injector Advanced Drive Laser System

Description: The drive laser for the photo-cathode gun used in the JLab Free Electron Laser (FEL) facility had been experiencing various phase shifts on the order of tens of degrees (>20{sup o} at 1497 MHz or >40ps) when changing the Advanced Drive Laser (ADL) [2][3][4] micro-pulse frequencies. These phase shifts introduced multiple complications when trying to setup the accelerator for operation, ultimately inhibiting the robustness and overall performance of the FEL. Through rigorous phase measurements and systematic characterizations, we determined that the phase shifts could be attributed to electromagnetic interference (EMI) coupling into the ADL phase control loop, and subsequently resolved the issue of phase shift to within tenths of a degree (<0.5{sup o} at 1497 MHz or <1ps). The diagnostic method developed and the knowledge gained through the entire process will prove to be invaluable for future designs of similar systems.
Date: September 1, 2011
Creator: F. G. Wilson, D. Sexton, S. Zhang
Partner: UNT Libraries Government Documents Department

Extreme Ultraviolet Phase Contrast Imaging

Description: The conclusions of this report are: (1) zone plate microscopy provides high resolution imaging of EUV masks; (2) using phase plates in the back focal plane of the objective lens can provide contrast mechanisms for measurement of the phase shift from defects on the mask; (3) the first high resolution EUV Zernike phase contrast images have been acquired; and (4) future work will include phase contrast mode in reflection from an EUV mask to directly measure the reflectivity and phase shift from defects.
Date: November 1, 2005
Creator: Denbeaux, Gregory; Garg, Rashi; Aquila, Andy; Barty, Anton; Goldberg, Kenneth; Gullikson, Eric et al.
Partner: UNT Libraries Government Documents Department

The Structure of 12N using 11C + p resonance scattering

Description: The level structure of {sup 12}N has been investigated from 2.2 to 11.0 MeV in excitation energy using a {sup 11}C + p resonance interaction with thick targets and inverse kinematics. Excitation functions were fitted using an R-matrix approach. Sixteen levels in {sup 12}N were included in the analysis, several of them are new. Spin-parity assignments, excitation energies and widths are proposed for these levels. To fit the high energy part of the excitation function, imaginary phase shifts had to be added to the phase shifts generated by the hard sphere scattering.
Date: March 2, 2006
Creator: Perajarvi, K.; Chang, Bo Fu; Rogachev, G.V.; Chubarian, G.; Goldberg, V.Z.; Guo, Q. et al.
Partner: UNT Libraries Government Documents Department

Simulation and Analysis of Microwave Transmission through an Electron Cloud, a Comparison of Results

Description: Simulation studies for transmission of microwaves through electron cloudes show good agreement with analytic results. The elctron cloud produces a shift in phase of the microwave. Experimental observation of this phenomena would lead to a useful diagnostic tool for acessing the local density of electron clouds in an accelerator. These experiments are being carried out at the CERN SPS and the PEP-II LER at SLAC and is proposed to be done at the Fermilab maininjector. In this study, a brief analysis of the phase shift is provided and the results are compared with that obtained from simulations.
Date: March 12, 2007
Creator: Sonnad, Kiran; Sonnad, Kiran; Furman, Miguel; Veitzer, Seth; Stoltz, Peter & Cary, John
Partner: UNT Libraries Government Documents Department

Multilayer Phase-Only Diffraction Gratings: Fabrication andApplication to EUV Optics

Description: The use of phase-only diffractive devices has long played an important role in advanced optical systems in varying fields. Such devices include gratings, diffractive and holographic optical elements, diffractive lenses, and phase-shift masks for advanced lithography. Extending such devices to the increasingly important regime of extreme ultraviolet (EUV) wavelengths, however, is not trivial. Here, we present an effective fabrication and etch process enabling high-resolution patterning of Mo/Si multilayers for use in EUV phase devices, providing another method for fabrication of high numerical aperture diffractive devices or high-resolution EUV phase shift masks.
Date: May 1, 2007
Creator: Salmassi, Farhad; Gullikson, Eric M.; Anderson, Erik H. & Naulleau, Patrick P.
Partner: UNT Libraries Government Documents Department

SIMULATION AND ANALYSIS OF MICROWAVE TRANSMISSION THROUGH ANELECTRON CLOUD, A COMPARISON OF RESULTS

Description: Simulation studies for transmission of microwaves through electron clouds show good agreement with analytic results. The electron cloud produces a shift in phase of the microwave. Experimental observation of this phenomena would lead to a useful diagnostic tool for accessing the local density of electron clouds in an accelerator. These experiments are being carried out at the CERN SPS and the PEP-II LER at SLAC and is proposed to be done at the Fermilab main injector. In this study, a brief analysis of the phase shift is provided and the results are compared with that obtained from simulations.
Date: April 15, 2006
Creator: Sonnad, Kiran G.; Furman, Miguel; Veitzer, Seth A. & Cary, John
Partner: UNT Libraries Government Documents Department

Assessment of a Single-Shot Pixelated Phase-Shifting Interferometer Utilizing a Liquid Crystal Spatial Light Modulator

Description: This article introduces a novel phase shifting pixelated interferometer based on a liquid crystal spatial light modulator and simulates the expected performance. The phase shifted frames are captured simultaneously which reduces the problems arising from vibrations and air turbulence. The liquid crystal spatial light modulator is very flexible and can be configured to provide a large number of phase shift levels and geometries to reduce the measurement error.
Date: October 1, 2005
Creator: Baker, K L & Stappaerts, E A
Partner: UNT Libraries Government Documents Department

ACCURACY LIMITATIONS IN LONG TRACE PROFILOMETRY.

Description: As requirements for surface slope error quality of grazing incidence optics approach the 100 nanoradian level, it is necessary to improve the performance of the measuring instruments to achieve accurate and repeatable results at this level. We have identified a number of internal error sources in the Long Trace Profiler (LTP) that affect measurement quality at this level. The LTP is sensitive to phase shifts produced within the millimeter diameter of the pencil beam probe by optical path irregularities with scale lengths of a fraction of a millimeter. We examine the effects of mirror surface ''macroroughness'' and internal glass homogeneity on the accuracy of the LTP through experiment and theoretical modeling. We will place limits on the allowable surface ''macroroughness'' and glass homogeneity required to achieve accurate measurements in the nanoradian range.
Date: August 25, 2003
Creator: TAKACS,P.Z. & QIAN,S.
Partner: UNT Libraries Government Documents Department

DESIGN OF A MICROFABRICATED, TWO-ELECTRODE PHASE-CONTRAST ELEMENTSUITABLE FOR ELECTRON MICROSCOPY

Description: A miniature electrostatic element has been designed to selectively apply a ninety-degree phase shift to the unscattered beam in the back focal plane of the objective lens, in order to realize Zernike-type, in-focus phase contrast in an electron microscope. The design involves a cylindrically shaped, biased-voltage electrode, which is surrounded by a concentric grounded electrode. Electrostatic calculations have been used to determine that the fringing fields in the region of the scattered electron beams will cause a negligible phase shift as long as the ratio of electrode length to the transverse feature-size is greater than 5:1. Unlike the planar, three-electrode einzel lens originally proposed by Boersch for the same purpose, this new design does not require insulating layers to separate the biased and grounded electrodes, and it can thus be produced by a very simple microfabrication process. Scanning electron microscope images confirm that mechanically robust devices with feature sizes of {approx}1 {micro}m can be easily fabricated. Preliminary experimental images demonstrate that these devices do apply a 90-degree phase shift between the scattered and unscattered electrons, as expected.
Date: September 20, 2006
Creator: Cambie, Rossana; Downing, Kenneth H.; Typke, Dieter; Glaeser,Robert M. & Jin, Jian
Partner: UNT Libraries Government Documents Department

Longitudinal Bunch Position Control for the Super-B Accelerator

Description: The use of normal conducting cavities and an ion-clearing gap will cause a significant RF accelerating voltage gap transient and longitudinal phase shift of the individual bunches along the bunch train in both rings of the SuperB accelerator. Small relative centroid position shifts between bunches of the colliding beams will have a large adverse impact on the luminosity due to the small {beta}*{sub y} at the interaction point (IP). We investigate the possibility of minimizing the relative longitudinal position shift between bunches by reducing the gap transient in each ring and matching the longitudinal bunch positions of the two rings at the IP using feedback/feedforward techniques in the LLRF. The analysis is conducted assuming maximum use of the klystron power installed in the system.
Date: May 15, 2009
Creator: Bertsche, Kirk; Rivetta, Claudio; Sullivam, Michael K.; /SLAC; Drago, Alessandro & /Frascati
Partner: UNT Libraries Government Documents Department

Orbit dynamics for unstable linear motion

Description: A treatment is given of the orbit dynamics for linear unstable motion that allows for the zeros in the beta function and makes no assumptions about the realness of the betatron and phase functions. The phase shift per turn is shown to be related to the beta function and the number of zeros the beta function goes through per turn. The solutions of the equations of motion are found in terms of the beta function.
Date: July 1997
Creator: Parzen, G.
Partner: UNT Libraries Government Documents Department

Bunched beam echos in the AGS

Description: Beam echos have been measured at FNAL and CERN in coasting beams. A coherent oscillation introduced by a short RF burst decoheres quickly, but a coherent echo of this oscillation can be observed if the decohered oscillation is bounced off a second RF burst. In this report the authors describe first longitudinal echo measurements of bunched beam in the AGS accelerator. They applied a method proposed by Stupakov for transverse beam echos, where the initial oscillation is produced by a dipole kick and is bounced off a quadrupole kick. In the longitudinal case the dipole and quadrupole kicks are produced by cavities operating at a 90 and 0{degree} phase shift, respectively.
Date: August 1, 1998
Creator: Kewisch, J. & Brennan, J.M.
Partner: UNT Libraries Government Documents Department

A Sampled Master Oscillator for the PEP-II B Factory

Description: A sampled phase-locked loop synchronizes the PEP-II B Factory rings to their SLAC Linac injector. The injection of both electrons and positrons into the separate rings and into their proper rf buckets requires phase shifting the linac rf with respect to the PEP rings. One of every three machine cycles provides the PEP ring an undisturbed reference while the other two thirds of the time the reference is unusable due to the injection scheme. The ring rf must be tunable about its nominal frequency for machine physics use. A sampled phase-locked loop handles the task of synchronizing the PEP-II rf to the linac while maintaining good phase noise. The input reference is sampled at 120 Hz and provides a ring rf signal with less than 0.1{degree} of rms phase jitter at 476 MHz.
Date: May 18, 1999
Partner: UNT Libraries Government Documents Department

High-accuracy calibration of an adaptive optics system using a phase shifting diffraction interferometer

Description: A phase-shifting diffraction interferometer (PSDI) has been integrated into an adaptive optics (AO) system developed by LLNL for use on the three meter Shane telescope at Lick Observatory. The interferometer is an all fiber optic design, which is extremely compact. It is useful for calibrating the control sensors, measuring the aberrations of the entire AO optical train, and measuring the influence functions of the individual actuators on the deformable mirror. The PSDI is particularly well suited for this application because it measures converging, quasi-spherical wavefronts, such as are produced by an AO imaging system. Thus, a PSDI can be used to measure the aberrations of the entire AO system, in-situ and without errors introduced by auxiliary optics. This provides an extremely accurate measurement ({approximately} 5 nm RMS) of the optical properties of the AO system.
Date: June 23, 1999
Creator: Bauman, B J; Campbell, E W; Olivier, S S & Sweider, D R
Partner: UNT Libraries Government Documents Department

Low Current, Long Beam Pulse with SLED

Description: The 3 km long linac at the Stanford Linear Accelerator Center (SLAC) is used for fixed target experiments such as E-155, with energies up to 50 GeV. The SLAC Energy Development (SLED) system increase the maximum no-load energy by a factor of 1.6, but it also causes a varying beam energy curve. To provide a long pulse or bunch train for the experiment the energy profile has to be flat. Besides more sophisticated methods such as varying the phase of two klystrons feeding one structure section as proposed in the NLC design, we describe the method used for E-155 in spring of 1997. The desired low charged beam didn't have any significant beam loading, but by inserting a 180{degree} phase notch during the SLED pulse, a beam pulse of up to 500 ns was achieved. The energy range without compensation would have been 15%, while with compensation the energy spread was reduced to about 0.15%. The phase notch was achieved by triggering a pair of two additional 180{degree} phase switches about half a structure fill-time after the SLED pulse was triggered. Simulations are compared with the experimental result.
Date: April 7, 1999
Creator: Decker, Franz-Josef
Partner: UNT Libraries Government Documents Department

BUNCHED BEAM ECHOS IN THE AGS.

Description: Beam echos have been measured at FNAL [3] and CERN [5] in coasting beams. A coherent oscillation introduced by a short RF burst decoheres quickly, but a coherent echo of this oscillation can be observed if the decohered oscillation is ''bounced off'' a second RF burst. In this report we describe first longitudinal echo measurements of bunched beam in the AGS accelerator. We applied a method proposed by Stupakov [1] for transverse beam echos, where the initial oscillation is produced by a dipole kick and is bounced off a quadrupole kick. In the longitudinal case the dipole and quadrupole kicks are produced by a cavities operating at a 90{degree} and 0{degree} phase shift, respectively.
Date: June 26, 1998
Creator: KEWISCH, J.
Partner: UNT Libraries Government Documents Department

Indicators of the energy error in the Linac to Booster transfer

Description: The match between the Linac beam energy and the energy determined by the bending field of the Booster magnets is crucial for rf capture, beam quality, and the transmission efficiency in a Booster cycle. The observation of the injection energy match is important for injection tuning. Several signals, such as phase shift drive (PSD), radial position error (RPOS), synchrotron phase (SPD), and fast phase error (FPERR), provide consistent information on the energy match and can be used for an injection match tuning.
Date: April 16, 2004
Creator: Yang, Xi & MacLachlan, James
Partner: UNT Libraries Government Documents Department

A low-cost non-intercepting beam current and phase monitor for heavy ions

Description: A low cost ion beam measurement system has been developed for use at ATLAS. The system provides nondestructive phase and intensity measurement of passing ion beam bunches by sensing their electric fields. Bunches traverse a short tubular electrode thereby inducing displacement currents. These currents are brought outside the vacuum jacket where a lumped inductance resonates electrode capacitance at one of the bunching harmonic frequencies. This configuration yields a basic sensitivity of a few hundred millivolts signal per microampere of beam current. Beam induced radiofrequency signals are summed against an offset frequency generated by the master oscillator. The resulting difference frequency conveys beam intensity and bunch phase information which is sent to separate processing channels. One channel utilizes a phase locked loop to stabilize phase readings during microsecond beam drop outs. The other channel uses a linear full-wave active rectifier circuit which converts sine wave signal amplitude to a DC voltage representing beam current. Plans are in progress to install this new diagnostic at several locations in ATLAS which should help shorten the tuning cycle of new ion species.
Date: July 1, 1995
Creator: Bogaty, J.M. & Clifft, B.E.
Partner: UNT Libraries Government Documents Department

Proton polarization in neutral pion photo-production.

Description: The authors present measurements of recoil proton polarization for {sup 1}H({rvec {gamma}},{rvec p}){pi}{sup 0} in and above the resonance region. These are the first data in this reaction for polarization transfer with circularly polarized photons. The results are compared to phase shift analyses and quark model calculations.
Date: July 16, 2002
Creator: Wijesooriya, K. & Collaboration, Jefferson Lab Hall A
Partner: UNT Libraries Government Documents Department