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in subjects: "Polarized Beams"

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An electromagnetic helical undulator for polarized x-rays

Linearly and circularly polarized x-rays have been very successfully applied to the study of the properties of materials. Many applications can benefit from the availability of energy-turnable, high-brilliance x-ray beams with adjustable polarization properties. A helical undulator that can generate beams of variable (linear to circular) polarization has been designed and built by the Budker Institute of Nuclear Physics and the Advanced Photon Source. The first harmonic of this 12.8-cm-period d… more

Date: October 28, 1999

Creator: Gluskin, E.; Vinokurov, N.; Tcheskidov, V.; Medvedko, A.; Evtushenko, Y. Kolomogorov, V.; Vobly, P. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Polarized RF guns for linear colliders: An ICFA Workshop

The ICFA Workshop on Polarized RF Guns for Linear Colliders was held at Fermilab during April 18-20, 2001. It was attended by 37 scientists from 14 institutions. A list of participants is appended. An RF photoemission gun that delivers polarized electrons at low emittance would be an attractive electron source for a linear collider. Moreover, recently it has been demonstrated that an RF gun in conjunction with nearby injection system optics can deliver a beam with a high ratio of transverse emi… more

Date: January 31, 2002

Creator: Edwards, D. A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Measurement of a Weak Polarization Sensitivity to the Beam Orbit of the CEBAF Accelerator

An accelerator-based experiment was performed using the CEBAF accelerator of the Thomas Jefferson National Accelerator Facility to investigate a predicted sensitivity of the beam polarization to the vertical betatron orbit in the recirculation arcs. This is the first measurement of any such effect at CEBAF, and provides information about the polarized beam delivery performance of the accelerator. A brief description of the accelerator is given, followed by the experimental methods used and the … more

Date: April 1, 2000

Creator: Grames, Joseph

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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Crossing a Coupling Spin Resonance With an RF Dipole

In accelerators, due to quadrupole roll errors and solenoid fields, the polarized proton acceleration often encounters coupling spin resonances. In the Brookhaven AGS, the coupling effect comes from the solenoid partial snake which is used to overcome imperfection resonances. The coupling spin resonance strength is proportional to the amount of coupling as well as the strength of the corresponding intrinsic spin resonance. The coupling resonance can cause substantial beam polarization loss if i… more

Date: June 18, 2001

Creator: Bai, M. & Roser, T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Grazing incidence neutron diffraction from large scale 2D structures

The distorted wave Born approximation (DWBA) is applied to evaluate the diffraction pattern of neutrons (or X-rays) from a 2D array of dots deposited onto a dissimilar substrate. With the radiation impinging on the surface at a grazing incidence angle {alpha}, the intensities diffracted both in and out the plane of specular reflection are calculated as a function of the periodicity of the array, height and diameter of the dots. The results are presented in the form of diffracted intensity conto… more

Date: January 13, 2000

Creator: Toperverg, B. P.; Felcher, G. P.; Metlushko, V. V.; Leiner, V.; Siebrecht, R. & Nikonov, O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Commissioning and Future Plans for Polarized Protons in Rhic.

Polarized protons were injected and accelerated in the clockwise ring of RHIC to commission the first full helical Siberian snake ever used in an accelerator. With the snake turned on, the stable spin direction is in the horizontal plane. Vertically polarized protons were injected with the snake off. The snake was adiabatically ramped to give a spin rotation of 180{degree} around a horizontal rotation axis about 13{degree} from the longitudinal. When the beam was accelerated from injection G{su… more

Date: June 18, 2001

Creator: MacKay, W. W.; Ahrens, L.; Bai, M.; Bunce, G.; Courant, E.; Deshpande, A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Spin Flipping in RHIC.

At the Relativistic Heavy Ion Collider (RHIC), polarized protons will be accelerated and stored for spin physics experiments. Two full helical snakes will be used to eliminate the depolarization due to imperfection and intrinsic spin resonances. Since no resonances are crossed in RHIC, the beam polarization remains fixed through acceleration. However, in order to reduce systematic errors, the experiment often requires the polarization direction reversed. This paper presents a method of using an… more

Date: June 18, 2001

Creator: Bai, M.; Lehrach, A.; Luccio, A.; MacKay, W. W.; Roser, T. & Tsoupas, N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Polarized Proton Acceleration in AGS and RHIC

As the first hadron accelerator and collider consisting of two independent superconducting rings RHIC has operated with a wide range of beam energies and particle species including polarized proton beams. The acceleration of polarized beams in both the injector and the collider rings is complicated by numerous depolarizing spin resonances. Partial and full Siberian snakes have made it possible to overcome the depolarization and beam polarizations of up to 65% have been reached at 100 GeV in RHI… more

Date: September 10, 2007

Creator: Roser, T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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A compton backscattering polarimeter for measuring longitudinal electron polarization

Compton backscattering polarimetry provides a fast measurement of the polarization of an electron beam in a storage ring. Since the method is non-destructive, the polarization of the electrons can be monitored during internal target experiments. At NIKHEF a Compton polarimeter has been constructed to measure the polarization of the longitudinally polarized electrons stored in the AmPS ring. First results obtained with the polarimeter, the first Compton polarimeter to measure the polarization of… more

Date: August 1, 1997

Creator: Passchier, I.; Higinbotham, Douglas W.; Vodinas, N.; Papadakis, N.; Jager, Kees de; Alarcon, Ricardo et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Magnetic Compton scattering studies of the Invar alloy Fe{sub 3}Pt

The magnetic Compton profiles (MCP) for both ordered and disordered Fe{sub 3}Pt samples have been measured above and below their Curie temperature. These measurements show that the average moment per atom at room temperature is 2.8{sub {mu}{sub B}} {plus_minus} 0.1{sub {mu}{sub B}} for disordered Fe{sub 3}Pt and 1.8{sub {mu}{sub B}} {plus_minus} 0.1{sub {mu}{sub B}} for ordered Fe{sub 3}Pt., At temperatures above {Tc}, we measured a substantial reduction in the moment (0.6{sub {mu}{sub B}} {plu… more

Date: February 1, 1995

Creator: Yahnke, C.J.; Srajer, G.; Haeffner, D.R.; Mills, D.M. & Assoufid, L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Nucleon Magnetic Form Factors

A review of data on the nucleon electromagnetic form factors in the space-like region is presented. Recent results from experiments using polarized beams and polarized targets or nucleon recoil polarimeters have yielded a significant improvement on the precision of the data obtained with the traditional Rosenbluth separation. Future plans for extended measurements are outlined.

Date: December 1, 2001

Creator: Jager, Kees de

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The SLAC polarized electron source

The SLAC polarized electron source employs a photocathode DC high voltage gun with a loadlock and a YAG pumped Ti:sapphire laser system for colliding beam experiments or a flash lamp pumped Ti:sapphire laser for fixed target experiments. It uses a thin, strained GaAs(100) photocathode, and is capable of producing a pulsed beam with a polarization of {ge}80% and a peak current exceeding 10 A. Its operating efficiency has reached 99%. The physics and technology of producing high polarization elec… more

Date: June 1, 1995

Creator: Tang, H.; Alley, R. & Frisch, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Spin tracking study of the AGS

In the recent polarized proton runs in the AGS, a 5% partial snake was used successfully to overcome the imperfection depolarizing resonances. Although some depolarization at intrinsic resonances are expected, the level of the depolarization does not agree with a simple model calculation. A spin tracking program is then used to simulate the real polarized proton beam in the AGS. The results show that, due to the linear coupling introduced by a solenoidal 5% partial snake, the polarized beam wil… more

Date: July 1, 1997

Creator: Huang, H.; Roser, T. & Luccio, A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Effect of SiO{sub 2} overcoat thickness on laser damage morphology of HfO{sub 2}/SiO{sub 2} Brewster`s angle polarizers at 1064 nm

HfO{sub 2}/SiO{sub 2} Brewster`s angle polarizers are being developed at LLNL for the National Ignition Facility. Damage threshold studies using a 3-ns pulse length 1064-nm laser have revealed a number of different damage morphologies such as nodular ejection pits, plasma scalds, flat bottom pits, and overcoat delaminations. Of these laser damage morphologies, delaminations have the most negative impact on the multilayer stability. By selecting the proper SiO{sub 2} overcoat thickness, the dela… more

Date: March 3, 1997

Creator: Stolz, C. J.; Genin, F. Y.; Reitter, T. A.; Molau, N. E.; Bevis, R. P.; von Gunten, M. K. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Polarized neutrons in RHIC

There does not appear to be any obvious way to accelerate neutrons, polarized or otherwise, to high energies by themselves. To investigate the behavior of polarized neutrons the authors therefore have to obtain them by accelerating them as components of heavier nuclei, and then sorting out the contribution of the neutrons in the analysis of the reactions produced by the heavy ion beams. The best neutron carriers for this purpose are probably {sup 3}He nuclei and deuterons. A polarized deuteron … more

Date: April 20, 1998

Creator: Courant, E. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Soft x-ray spectroscopy undulator beamline at the Advanced Photon Source

Construction of the high-resolution soft x ray spectroscopy undulator beamline, 2ID-C, at the Advanced Photon Source (APS) has been completed. The beamline, one of two soft x ray beamlines at the APS, will cover the photon energy range from 500 to 3,000 eV, with a maximum resolving power between 7,000 and 14,000. The optical design is based on a spherical grating monochromator (SGM) giving both high resolution and high flux throughput. Photon flux is calculated to be approximately 10{sup 12}--1… more

Date: September 1, 1997

Creator: Randall, K.J.; Xu, Z.; Moore, J.F. & Gluskin, E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Polarized Source Performance and Developments at Jefferson Lab

The polarized photoinjector at Jefferson Lab continues to provide high average current, high polarization, high quality beam to nuclear physics Users in as many as three endstations simultaneously. Long lifetime operation has been obtained from two identical polarized guns. A new high power mode locked Ti-sapphire laser has been constructed to enhance the effective operating lifetime of the photoinjector. Efforts to enhance beam polarization and reduced helicity correlated beam systematic effec… more

Date: October 1, 2000

Creator: Poelker, Matt; Adderley, P.; Clark, J.; Day, A.; Grames, Joseph; Hansknecht, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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An improved limit on jet handedness in Z{sup 0} decays

We present the results of an improved search for jet handedness in hadronic decays of Z{sup degree} bosons collected by the SLD experiment at SLAC. Quark and antiquark jets, expected to be oppositely polarized in Z{sup degree} decays, were separated using the large forward-backward quark asymmetry induced by the highly polarized SLC electron beam. The larger data sample and beam polarization of the 1994/5 SLC/SLD run yield a factor of two improvement in our sensitivity to jet handedness. Assumi… more

Date: July 1995

Creator: The SLD Collaboration

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Calculation of the Invariant Spin Field by Adiabatically Blowing Up the Beam With an RF Dipole

The Relativistic Heavy Ion Collider RHIC will collide polarized proton beams up to a maximum beam energy of 250 GeV [1]. The invariant spin field in a high energy ring can vary substantially across the beam. This decreases the amount of polarization provided to experiments and makes the polarization strongly dependent on the position in phase space. This paper describes a method to compute the invariant spin field by adiabatically blowing up the beam with an rf dipole. This method will also all… more

Date: May 17, 1999

Creator: Lehrach, A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Spin Flipping in RHIC.

Date: June 18, 2001

Creator: Bai, M.; Lehrach, A.; Luccio, A.; MacKay, W. W.; Roser, T. & Tsoupas, N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Time reversal tests in polarized neutron reactions

This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). In recent years the nuclear weak interaction has been studied in the compound nucleus via parity violation. The observed parity-violating effects are strongly enhanced by nuclear structure. The predictions are that the interaction of polarized neutrons with polarized nuclear targets could be also used to perform sensitive tests of time-reversal-viol… more

Date: November 1, 1998

Creator: Asahi, Koichiro; Bowman, J.D. & Crawford, B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Recent advances in polarized electron sources

Current experimental physics programs at a number of electron accelerator laboratories worldwide require the delivery of high average current highly polarized electron beams for long periods of time. The polarized electrons are produced by near bandgap photoemission from certain semiconductor photocathodes. The authors observe the quantum efficiency of these cathodes to be inversely related to the total charge they have delivered. Recent developments in ultrahigh vacuum technology, electron tra… more

Date: March 1, 1999

Creator: Sinclair, C. K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Ionization of polarized 3He+ ions in EBIS trap with slanted electrostatic mirror.

Methods of producing the nuclear polarized {sup 3}He{sup +} ions and their ionization to {sup 3}H{sup ++} in ion trap of the electron Beam Ion Source (EBIS) are discussed. Computer simulations show that injection and accumulation of {sup 3}He{sup +} ions in the EBIS trap with slanted electrostatic mirror can be very effective for injection times longer than the ion traversal time through the trap.

Date: September 10, 2007

Creator: Pikin, A.; Zelenski, A.; Kponou, A.; Alessi, J.; Beebe, E.; Prelee, K. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Theoretical studies in elementary particle physics. Annual technical progress report

This is a report on research conducted at Penn State University under grant number DE-FG02-90ER-40577, from November 1992 to present. The author is a member of the CTEQ collaboration (Coordinated Theoretical and Experimental Project on Quantitative QCD). Some of the work in CTEQ is described in this report. Topics which the authors work has touched include: polarized hard scattering; hard diffraction; small x and perturbative pomeron physics; gauge-invariant operators; fundamental QCD; heavy qu… more

Date: July 1, 1994

Creator: Collins, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department