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Precision electron polarimetry

Description: A new generation of precise Parity-Violating experiments will require a sub-percent accuracy of electron beam polarimetry. Compton polarimetry can provide such accuracy at high energies, but at a few hundred MeV the small analyzing power limits the sensitivity. M{\o}ller polarimetry provides a high analyzing power independent on the beam energy, but is limited by the properties of the polarized targets commonly used. Options for precision polarimetry at ~300 MeV will be discussed, in particular a proposal to use ultra-cold atomic hydrogen traps to provide a 100\%-polarized electron target for M{\o}ller polarimetry.
Date: November 1, 2013
Creator: Chudakov, Eugene A.
Partner: UNT Libraries Government Documents Department

Induced star formation and morphological evolution in very high redshift radio galaxies

Description: Near-infrared, sub-arcsecond seeing images obtained with the W M Keck I Telescope of show strong evolution at rest-frame optical wavelengths in the morphologies of high redshift radio galaxies (HzRGs) with 1 9 < z < 4 4 The structures change from large-scale low surface brightness regions surrounding bright, multiple component and often radio-aligned features at z > 3, to much more compact and symmetrical shapes at z < 3 The linear sizes ({approximately} 10 kpc) and luminosities (M{sub B} {approximately} -20 to -22) of the individual components in the z > 3 HzRGs are similar to the total sizes and luminosities of normal, radio-quiet, star forming galaxies seen at z = 3 - 4 `R`-band, 0 1`` resolution images with the Hubble Space Telescope of one of these HzRGs, 4C41 17 at z = 3 800, show that at rest-frame UV wavelengths the galaxy morphology breaks up in even smaller, {approximately} 1 kpc-sized components embedded in a large halo of low suface brightness emission The brightest UV emission is from a radio-aligned, edge-brightened feature (4C41 17.North) downstream from a bright radio knot A narrow-band Ly-{alpha} image, also obtained with HST, shows an arc-shaped Ly-{alpha} feature at this same location, suggestive of a strong jet/cloud collision Deep spectropolarimetric observations with the W M Keck II Telescope of 4C41 17 show that the radio-aligned UV continuum is unpolarized Instead the total light spectrum shows ahsorption lines and P-Cygni type features that are similar to the radio-quiet z = 3 - 4 star forming galaxies This shows that the rest-frame UV light in 4C41 17 is dominated by starlight, not scattered light from a hidden AGN The combined HST and Keck data suggest that the radio--aligned rest-frame UV continuum is probably caused by jet-induced star formation The strong morphological evolution suggests that we ...
Date: October 1, 1997
Creator: van Breugel, W. J. M.
Partner: UNT Libraries Government Documents Department

The EBEX Experiment

Description: EBEX is a balloon-borne polarimeter designed to measure the intensity and polarization of the cosmic microwave background radiation. The measurements would probe the inflationary epoch that took place shortly after the big bang and would significantly improve constraints on the values of several cosmological parameters. EBEX is unique in its broad frequency coverage and in its ability to provide critical information about the level of polarized Galactic foregrounds which will be necessary for all future CMB polarization experiments. EBEX consists of a 1.5 m Dragone-type telescope that provides a resolution of less than 8 arcminutes over four focal planes each of 4. diffraction limited field of view at frequencies up to 450 GHz. The experiment is designed to accommodate 330 transition edge bolometric detectors per focal plane, for a total of up to 1320 detectors. EBEX will operate with frequency bands centered at 150, 250, 350, and 450 GHz. Polarimetry is achieved with a rotating achromatic half-wave plate. EBEX is currently in the design and construction phase, and first light is scheduled for 2008.
Date: January 6, 2005
Creator: Oxley, P.; Ade, P.; Baccigalupi, C.; deBernardis, P.; Cho, H-M.; Devlin, M.J. et al.
Partner: UNT Libraries Government Documents Department

A compton backscattering polarimeter for measuring longitudinal electron polarization

Description: 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 a stored longitudinally polarized electron beam, are presented in this paper.
Date: August 1, 1997
Creator: Passchier, I.; Higinbotham, Douglas W.; Vodinas, N.; Papadakis, N.; Jager, Kees de; Alarcon, Ricardo et al.
Partner: UNT Libraries Government Documents Department

Electron beam polarimetry

Description: Along with its well known charge and mass, the electron also carries an intrinsic angular momentum, or ''spin.'' The rules of quantum mechanics allow one to measure only the probability that the electron spin is in one of two allowed spin states. When a beam carries a net excess of electrons in one of these two allowed spin states, the beam is said to be ''polarized.'' The beam polarization may be measured by observing a sufficient number of electrons scattered by a spin-dependent interaction. For electrons, the useful scattering processes involve coulomb scattering by heavy nuclei, or scattering from either polarized photons or other polarized electrons (known as Mott, Compton, or Moller scattering, respectively). In this tutorial, the authors briefly review how beam polarization is measured through a general scattering process, followed by a discussion of how the three scattering processes above are used to measure electron beam polarization. Descriptions of electron polarimeters based on the three scattering processes will be given.
Date: January 1, 1998
Creator: Sinclair, Charles K.
Partner: UNT Libraries Government Documents Department

The polarized electron beam for the SLAC Linear Collider

Description: The SLAC Linear Collider has been colliding a polarized electron beam with an unpolarized positron beam at the Z{sup 0} resonance for the SLD experiment since 1992. An electron beam polarization of close to 80% has been achieved for the experiment at luminosities up to 8 {center_dot} 10{sup 29} cm{sup {minus}2} s{sup {minus}1}. This is the world`s first and only linear collider, and is a successful prototype for the next generation of high energy electron linear colliders. This paper discusses polarized beam operation for the SLC, and includes aspects of the polarized source, spin transport and polarimetry.
Date: October 1, 1996
Creator: Woods, M.
Partner: UNT Libraries Government Documents Department

Note on RHIC polarimetry.

Description: For physics measurements with polarized colliding beams, beam polarizations and relative luminosities must both be determined. Predictions for spin observables of many interesting physics processes at RHIC are quite small in magnitude. This requires high statistics measurements of relative luminosities and careful control of systematic errors. Discussions about the polarized beams at RHIC often presume that the polarization and intensity of each bunch within a will be known quite well from measurements by the RHIC polarimeters. The purpose of this note is to give a description of the knowledge that can actually be obtained from these polarimeters.
Date: November 12, 1999
Creator: Spinka, H.
Partner: UNT Libraries Government Documents Department

POLARIZED PROTON ACCELERATION IN AGS AND RHIC.

Description: 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 RHIC.
Date: September 10, 2007
Creator: ROSER,T.
Partner: UNT Libraries Government Documents Department

p-Carbon polarimetry at RHIC.

Description: The polarization measurement through elastic ({rvec p},C) reaction plays a crucial role in the polarized proton beam operation of Relativistic Heavy Ion collider at Brookhaven National Laboratory. As well as measuring the polarization, the unknown analyzing power A{sub N} of elastic ({rvec p},C) is determined as well in combination with the absolute polarization measurement by a H-jet polarimeter. The systematic uncertainty of the Run05 measurements are discussed as well as introducing the experimental apparatus of the polarimeter system.
Date: September 10, 2007
Creator: Nakagawa,I.; Makdisi,Y.; Alekseev, I.; Bazilesky, A.; Bravar, A.; Bunce, G. et al.
Partner: UNT Libraries Government Documents Department

A Study of Laser System Requirements for Application in Beam Diagnostics And Polarimetry at the ILC

Description: Advanced laser systems will be essential for a range of diagnostics devices and polarimetry at the ILC. High average power, high beam quality, excellent stability and reliability will be crucial in order to deliver the information required to attain the necessary ILC luminosity as well as for efficient polarimetry. The key parameters are listed together with the R & D required to achieve the necessary laser system performance.
Date: February 12, 2007
Creator: Dixit, S.; Delerue, N.; Foster, B.; Howell, D. F.; Peach, K.; Quelch, G. et al.
Partner: UNT Libraries Government Documents Department

Polarimetry on RGB BL lacs

Description: We present results on polarimetry on RGB BL Lacs. This sample has its roots in ROSAT and Green Bank catalogues. The broad band spectral energy distribution of RGB BL Lacs differs from the ''traditional'' BL Lacs, filling the gap between two extremes, HBLs and LBLs. We found that the polarization properties of the sample are also intermediate to HBLs and LBLs. The highest measured polarization was {minus}19% and {minus}60% of the objects had high polarization. Our results suggests that there is a connection between HBLs and LBLs and between the synchrotron peak frequency and the degree of polarization.
Date: June 1, 1998
Creator: Heinamaki, S; Katajainen, A; Muehleisen, S L; Nilsson, P; Pursimo, T; Schmidt, G et al.
Partner: UNT Libraries Government Documents Department

PROCEEDINGS OF RIKEN BNL RESEARCH CENTER, VOLUME 37, RHIC SPIN COLLABORATION MEETING VI (PART 2).

Description: The second part of the sixth RHIC Spin Collaboration (RSC) meeting was held on November 15, 2001 at Brookhaven National Laboratory. Previous meetings have elaborated on the new generation of proton spin-structure studies (e.g. gluon polarization and flavor separation of q and {bar q} polarizations via real W{sup {+-}} production) enabled by studying polarized proton collisions at energies and momentum transfers where perturbative QCD models are expected to be applicable. The focus of this meeting was on many of the experimental issues that must be resolved to achieve these physics goals. This summary is written with the benefit of hindsight following the completion of the first-ever run of a polarized proton collider. This first run can be considered as a successfully completed milestone of the RHIC Spin Collaboration. Other milestones remain important. Long term machine items were identified in Waldo Mackay's talk, the most important being the completion of the spin rotator magnets that will be installed in 2002 to allow the flexible orientation of the proton beam polarization at the PHENM and STAR experiments. At the meeting Waldo discussed a stronger partial snake magnet for the AGS as a means of producing highly polarized proton beams to inject into RHIC. Developments subsequent to this meeting suggest that a superconducting helical dipole magnet may be feasible for the AGS, and is likely to be needed to achieve the 70% beam polarization in RHIC. Longer term items were also presented, including potential increases in luminosity by the addition of electron cooling to RHIC and the possibility of increasing the collision energy by {approx}20% by replacement of the DX magnets. These items could be considered for a second generation of RHIC spin experiments. The other topics covered at the meeting were related to polarimetry and to the absolute calibration of the proton ...
Date: November 15, 2001
Creator: BLAND, L. & SAITO, N.
Partner: UNT Libraries Government Documents Department

5 MeV Mott polarimeter for rapid precise electron beam polarization measurements

Description: Low energy (E{sub k} = 100 keV) Mott scattering polarimeters are ill-suited to support operations foreseen for the polarized electron injector at Jefferson Lab. One solution is to measure the polarization at 5 MeV where multiple and plural scattering are unimportant and precision beam monitoring is straightforward. The higher injector beam current offsets the lower cross-sections; measured rates scale to 1 kHz/{mu}A with a 1 {mu}m thick gold target foil.
Date: November 1, 1997
Creator: Price, J.S.; Poelker, B.M. & Sinclair, C.K.
Partner: UNT Libraries Government Documents Department

Portable Imaging Polarimeter and Imaging Experiments

Description: Polarimetry is the method of recording the state of polarization of light. Imaging polarimetry extends this method to recording the spatially resolved state of polarization within a scene. Imaging-polarimetry data have the potential to improve the detection of manmade objects in natural backgrounds. We have constructed a midwave infrared complete imaging polarimeter consisting of a fixed wire-grid polarizer and rotating form-birefringent retarder. The retardance and the orientation angles of the retarder were optimized to minimize the sensitivity of the instrument to noise in the measurements. The optimal retardance was found to be 132{degree} rather than the typical 90{degree}. The complete imaging polarimeter utilized a liquid-nitrogen cooled PtSi camera. The fixed wire-grid polarizer was located at the cold stop inside the camera dewar. The complete imaging polarimeter was operated in the 4.42-5 {micro}m spectral range. A series of imaging experiments was performed using as targets a surface of water, an automobile, and an aircraft. Further analysis of the polarization measurements revealed that in all three cases the magnitude of circular polarization was comparable to the noise in the calculated Stokes-vector components.
Date: November 1, 1999
Creator: PHIPPS,GARY S.; KEMME,SHANALYN A.; SWEATT,WILLIAM C.; DESCOUR,M.R.; GARCIA,J.P. & DERENIAK,E.L.
Partner: UNT Libraries Government Documents Department

Spectropolarimetry of FIRST 0840 + 3633

Description: We present Keck spectropolarimetry of a rare ``Iron Lo- BALQSO,`` FIRST 0840+3633. The continuum is {approximately}4% polarized near 2000{Angstrom} rest-frame, but falls to {approximately}2% at longer wavelengths, and maintains a relatively constant position angle of 50{degrees}. The emission lines are unpolarized. The polarization increases up to {approximately}8% in the low-ionization absorption troughs of Mg II {lambda}2800 and Al III {lambda}1860. The polarization and its position angle vary in a complicated manner across the metastable Fe II absorption lines, suggesting that more than one mechanism is at work or that the system geometry is complex.
Date: February 1, 1997
Creator: Brotherton, M.S.; Van Breugel, N.; Dey, A. & Antonucci, R.
Partner: UNT Libraries Government Documents Department

Measurement of the neutrino-spin correlation parameter B neutron decay using ultracold neutrons

Description: We present a new approach to measuring the neutrino-spin correlation parameter B in neutron decay. The approach combines the technology of large-area ion-implanted silicon detectors being developed for the abBA experiment, with an ultracold neutron source to provide more precise neutron polarimetry. The technique detects both proton and electron from the neutron decay in coincidence. B is determined from an electron-energy-dependent measurement of the proton spin asymmetry. This approach will provide a statistical precision of 1 x 10-4 . The systematic precision is still being evaluated, but is expected to be below 1 x 10-3 , and could approach 1 x 10-4 . A measurement of B with this precision would place constraints on supersymmetric extensions to the Standard Model.
Date: January 1, 2009
Creator: Wilburn, Wesley S
Partner: UNT Libraries Government Documents Department

ELLIPSOMETRY OF ELECTROCHEMICAL SURFACE LAYERS

Description: Ellipsometry is concerned with the analysis and interpretation of changes in the state of polarization caused by reflection. The technique has found increasing interest in recent years for the measurement of thin films because it is unusually sensitive, disturbs the object minimally and can be applied to surfaces contained in any optically transparent medium. Film thicknesses amenable to measurement range from fractional monoatomic coverage to microscopic thicknesses. The measurement of changes in the state of polarization of light due to reflection provides an unusually sensitive tool for observing surface layers in any optically transparent environment. A fast, self-compensating ellipsometer has been used to observe the electrochemical formation of reacted surface layers. The optical effect of mass-transport boundary layers and component imperfections have been taken into account in the interpretation of results.
Date: June 1, 1977
Creator: Muller, R.H.
Partner: UNT Libraries Government Documents Department

Unique electron polarimeter comparison and spin-based energy measurement

Description: A careful intercomparison of the relative analyzing power of five electron beam polarimeters was performed at Jefferson Lab during a dedicated two day machine development period. This is the first time such a comparison between Mott, Compton, and Moller polarimeters has been made. A Wien-style spin manipulator at the injector was used to vary the spin orientation of the electron beam at each polarimeter. A series of measurements as a function of spin orientation provides determination of the relative analyzing power of each polarimeter, and more importantly, quantifies the instrumental systematics which help realize high precision absolute electron polarimetry. In addition, a comparison of the value of the injector spin angle that. provides precise longitudinal beam polarization at each experimental hall leads to an independent and potentially high precision measurement (dE/E = 10-5) of the final electron beam energy. Results and discussion of the tests of the polarimeters and energy measurement will be presented.
Date: June 1, 2001
Creator: Grames, J.M.
Partner: UNT Libraries Government Documents Department

Cosmological Consequences of String Axions

Description: Axion fluctuations generated during inflation lead to isocurvature and non-Gaussian temperature fluctuations in the cosmic microwave background radiation. Following a previous analysis for the model independent string axion we consider the consequences of a measurement of these fluctuations for two additional string axions. We do so independent of any cosmological assumptions except for the axions being massless during inflation. The first axion has been shown to solve the strong CP problem for most compactifications of the heterotic string while the second axion, which does not solve the strong CP problem, obeys a mass formula which is independent of the axion scale. We find that if gravitational waves interpreted as arising from inflation are observed by the PLANCK polarimetry experiment with a Hubble constant during inflation of H{sub inf} {approx}&gt; 10{sup 13} GeV the existence of the first axion is ruled out and the second axion cannot obey the scale independent mass formula. In an appendix we quantitatively justify the often held assumption that temperature corrections to the zero temperature QCD axion mass may be ignored for temperatures T {approx}&lt; {Lambda}{sub QCD}.
Date: December 15, 2005
Creator: Kain, Ben
Partner: UNT Libraries Government Documents Department

ABSOLUTE POLARIMETRY AT RHIC.

Description: Precise and absolute beam polarization measurements are critical for the RHIC spin physics program. Because all experimental spin-dependent results are normalized by beam polarization, the normalization uncertainty contributes directly to final physics uncertainties. We aimed to perform the beam polarization measurement to an accuracy Of {Delta}P{sub beam}/P{sub beam} &lt; 5%. The absolute polarimeter consists of Polarized Atomic Hydrogen Gas Jet Target and left-right pairs of silicon strip detectors and was installed in the RHIC-ring in 2004. This system features proton-proton elastic scattering in the Coulomb nuclear interference (CNI) region. Precise measurements of the analyzing power A{sub N} of this process has allowed us to achieve {Delta}P{sub beam}/P{sub beam} = 4.2% in 2005 for the first long spin-physics run. In this report, we describe the entire set up and performance of the system. The procedure of beam polarization measurement and analysis results from 2004-2005 are described. Physics topics of AN in the CNI region (four-momentum transfer squared 0.001 &lt; -t &lt; 0.032 (GeV/c){sup 2}) are also discussed. We point out the current issues and expected optimum accuracy in 2006 and the future.
Date: September 10, 2007
Creator: OKADA; BRAVAR, A.; BUNCE, G.; GILL, R.; HUANG, H.; MAKDISI, Y. et al.
Partner: UNT Libraries Government Documents Department

Application of Stark Tuned Laser for Interferometry and Polarimetry in Plasmas

Description: A Stark-tuned optically pumped far-infrared CH(subscript ''3'')OH laser at 119 mm has been successfully applied in the Far Infrared Tangential Interferometer/Polarimeter (FIReTIP) system for the National Spherical Torus Experiment (NSTX). The system will provide temporally and radially resolved 2-D electron density profile [n(subscript ''e'')(r,t)] and toroidal field profile [B(subscript ''T'')(r,t)] data. In the 2001 campaign, a single channel interferometer system has been operated and tested for the Faraday rotation measurement. A plan for improvement and upgrading of the FIReTIP is discussed.
Date: September 7, 2001
Creator: Park, H.K.; Lee, K.C.; Deng, B.; Domier, C.W.; Johnson, M.; Nathan, B. et al.
Partner: UNT Libraries Government Documents Department

Hadron spin-flip at RHIC energies: Volume 3. Proceedings of RIKEN BNL Research Center workshop

Description: From July 21 to August 22, 1997 a working group sponsored by the RIKEN BNL Research Center was convened to consider ``Hadron Spin-Flip at RHIC Energies.`` The original motivation for this arose from the importance of understanding the hadronic part of the proton-proton spin flip amplitude in using the Coulomb-Nuclear Interference for polarimetry. This is a very difficult, non-perturbative problem and it is not possible to make a calculation with controlled approximations, so a number of approaches were followed: (1) methods to extract the necessary information from past experiments and from RHIC experiments were examined; (2) phenomenological, Regge models--some of them very old--were reviewed; (3) the predictions of several non-perturbative theoretical models were evaluated; (4) the use of nuclei for the CNI experiment was quantitatively considered; (5) alternative methods of polarimetry were critically studied. These included Primikoff effect, large-t pp scattering, and pe double spin asymmetry.
Date: October 1, 1997
Partner: UNT Libraries Government Documents Department

PROPOSAL FOR A CAVITY POLARIMETER AT MIT-BATES.

Description: The possibility of successfully implementing a cavity polarimeter[1] has been greatly improved by the discovery[2] of a cavity mode for which the magnitude of the Stern-Gerlach force experienced by a magnetic moment traversing the cavity varies as the square of the relativistic factor gamma, so that the signal power varies as the fourth power of gamma. In addition, the interaction of this cavity mode with the beam charge varies as the inverse of the interaction with the magnetic moment, so that the background due to the beam charge varies as the inverse fourth power of gamma, If these gamma dependencies of moment and charge interaction with the pickup cavity do in fact exists the possibility is opened for very fast, accurate, and inexpensive polarimetry at accelerators like MIT-Bates and RHIC. In addition, it might become possible to seriously consider Stern-Gerlach polarization of beams at LHC. We present details of a quick polarimeter test at the electron storage ring at MIT-Bates, and of an extension of this test to a working polarimeter in the RHIC rings.
Date: June 18, 2001
Creator: Cameron, P.; Barry, W.; Conte, M.; Goldberg, D. A.; Jacobs, K.; Luccio, A. et al.
Partner: UNT Libraries Government Documents Department

Proton polarimetry by undulator radiation

Description: The authors show how spin light from an undulator can be used to measure the spin polarization of a proton beam in a high energy circular collider. They propose to perform left-right asymmetry measurements, employing lock-in amplification techniques.
Date: December 31, 1998
Creator: Luccio, A. U. & Conte, M.
Partner: UNT Libraries Government Documents Department