89 Matching Results

Search Results

Advanced search parameters have been applied.

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

Analyzing Power $A_n$ in High P-Transverse Squared Proton-Proton Elestic Scattering

Description: This is a proposal to measure the Analyzing Power $A_n$ in Proton-Proton Elestic Scattering at High P-Transverse Squared of 1 to 12 (GeV/c)<sup>2</sup> using a 120 GeV unpolarized extracted proton beam from Fermilab's Main Injector starting in 2001.
Date: August 1, 1998
Creator: Anferov, V. A.; Blinov, B. B.; Courant, E. D.; Derbenev, Ya. S.; Gladycheva, S. E.; Fidecaro, G. et al.
Partner: UNT Libraries Government Documents Department

Direct Measurement of A{sub b} using Charged Kaons at the SLD Detector

Description: We report a new measurement of A{sub b} using data obtained by SLD in 1997-98. This measurement uses a vertex tag technique, where the selection of a b hemisphere is based on the reconstructed mass of the bottom hadron decay vertex. The method uses the 3D vertexing capabilities of SLD's CCD vertex detector and the small and stable SLC beams to obtain a high b-event tagging efficiency and purity of 78% and 97%, respectively. Charged kaons identified by the CRID detector provide an efficient quark-antiquark tag, with the analyzing power calibrated from the data. We obtain a preliminary result of A{sub b} = 0.997 {+-} 0.044 {+-} 0.067.
Date: July 29, 1999
Creator: Wright, Thomas R
Partner: UNT Libraries Government Documents Department

Direct Measurement of A{sub c} using Inclusive Charm Tagging at the SLD Detector

Description: We report a new measurement of A{sub c} using data obtained by SLD in 1993-98. This measurement uses a vertex tag technique, where the selection of a c hemisphere is based on the reconstructed mass of the charm hadron decay vertex. The method uses the 3D vertexing capabilities of SLD's CCD vertex detector and the small and stable SLC beams to obtain a high c-event tagging efficiency and purity of 28% and 82%, respectively. Charged kaons identified by the CRID detector and the charge of the reconstructed vertex provide an efficient quark-antiquark tag, with the analyzing power calibrated from the data. We obtain a preliminary result of A{sub c} = 0.603 {+-} 0.028 {+-} 0.023.
Date: July 14, 1999
Creator: Abe, K
Partner: UNT Libraries Government Documents Department

Direct Measurement of A{sub b} using Charged Kaons at the SLD Detector

Description: We report a new measurement of A{sub b} using data obtained by SLD in 1997-98. This measurement uses a vertex tag technique, where the selection of a b hemisphere is based on the reconstructed mass of the bottom hadron decay vertex. The method uses the 3D vertexing capabilities of SLD's CCD vertex detector and the small and stable SLC beams to obtain a high b-event tagging efficiency and purity of 78% and 97%, respectively. Charged kaons identified by the CRID detector provide an efficient quark-antiquark tag, with the analyzing power calibrated from the data. We obtain a preliminary result of A{sub b} = 0.997 {+-} 0.044 {+-} 0.067.
Date: July 14, 1999
Creator: Wright, Thomas R
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

Proton-proton Scattering Above 3 GeV/c

Description: A large set of data on proton-proton differential cross sections, analyzing powers and the double-polarization parameter A{sub NN} is analyzed employing the Regge formalism. We find that the data available at proton beam momenta from 3 GeV/c to 50 GeV/c exhibit features that are very well in line with the general characteristics of Regge phenomenology and can be described with a model that includes the {rho}, {omega}, f{sub 2}, and a{sub 2} trajectories and single-Pomeron exchange. Additional data, specifically for spin-dependent observables at forward angles, would be very helpful for testing and refining our Regge model.
Date: January 1, 2010
Creator: Sibirtsev, A.; Haidenbauer, J.; Hammer, H.-W.; Krewald, S. & Meissner, Ulf-G.
Partner: UNT Libraries Government Documents Department

Tensor Analyzing Powers for Quasi-Elastic Electron Scattering from Deuterium

Description: We report on a first measurement of tensor analyzing powers in quasi-elastic electron-deuteron scattering at an average three-momentum transfer of 1.7 fm{sup -1}. Data sensitive to the spin-dependent nucleon density in the deuteron were obtained for missing momenta up to 150 MeV/c with a tensor polarized {sup 2}H target internal to an electron storage ring. The data are well described by a calculation that includes the effects of final-state interaction, meson-exchange and isobar currents, and leading-order relativistic contributions.
Date: January 1, 1999
Creator: Zhou, Z.-L.; Bouwhuis, M.; Ferro-Luzzi, M.; Passchier, E.; Alarcon, R.; Anghinolfi, M. 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

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

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

A Preliminary Direct Measurement of the Parity Violating Coupling of the Z{sup 0} to Strange Quarks, A{sub s}

Description: We present a preliminary direct measurement of the parity violating coupling of the Z{sup 0} to strange quarks, A{sub s}, derived from a sample of approximately 300,000 hadronic decays of Z{sup 0} produced with a polarized electron beam and recorded by the SLD experiment at SLAC between 1993 and 1997. Z{sup 0} {r_arrow} s{bar s} events are tagged by the presence in each event hemisphere of a high-momentum K{sup {+-}}, K{sub s}{sup 0} or {Lambda}{sup 0}/{bar {Lambda}}{sup 0} identified using the Cherenkov Ring Imaging Detector and/or a mass tag. The CCD vertex detector is used to suppress the background from heavy flavor events. The strangeness of the tagged particle is used to sign the event thrust axis in the direction of the initial strange quark. The coupling A{sub s} is obtained directly from a measurement of the left-right-forward-backward production asymmetry in polar angle of the tagged strange quark. To reduce the model dependence of the measurement, the background from primary up and down events is measured from the data, as is the analyzing power of the method for primary strange events. We measure: A{sub s} = 0.82 {+-} 0.10(stat.) {+-} 0.08(syst.)(preliminary).
Date: March 4, 1999
Creator: Staengle, H
Partner: UNT Libraries Government Documents Department

Left-right forward-backward asymmetry for c and b quarks

Description: This report reviews preliminary direct measurements of A{sub b} and A{sub c} from a sample of 100,000 hadronic Z{sup 0} decays accumulated during the 1994-1995 run with a luminosity-weighted average e{sup -} polarization {vert_bar}P{sub e}{vert_bar} {approx} 77.3 {+-} 0.6% combined with another 50,000 events from the 1993 run with {vert_bar}P{sub e}{vert_bar} = 63.0 {+-} 1.1%. The description of SLD detector components can be found in references of the individual analysis papers. All asymmetry measurement results described in this paper apply cos{theta}-dependent QCD corrections.
Date: October 1, 1995
Creator: Huber, J.
Partner: UNT Libraries Government Documents Department

A Preliminary Direct Measurement of the Parity-Violating Coupling of the Z{sup 0} to Strange Quarks, A{sub s}

Description: We present an updated direct measurement of the parity-violating coupling of the Z{sup 0} to strange quarks, A{sub s}, derived from the full SLD data sample of approximately 550,000 hadronic decays of Z{sup 0} bosons produced with a polarized electron beam and recorded by the SLD experiment at SLAC between 1993 and 1998. Z{sup 0} {r_arrow} s{bar s} events are tagged by the presence in each event hemisphere of a high-momentum K{sup {+-}}, K{sub s} or {Lambda}{sup 0}/{bar {Lambda}}{sup 0} identified using the Cherenkov Ring Imaging Detector and/or a mass tag. The CCD vertex detector is used to suppress the background from heavy-flavor events. The strangeness of the tagged particle is used to sign the event thrust axis in the direction of the initial s quark. The coupling A{sub s} is obtained directly from a measurement of the left-right-forward-backward production asymmetry in polar angle of the tagged s quark. The background from u{bar u} and d{bar d} events is measured from the data, as is the analyzing power of the method for s{bar s} events. We measure: A{sub s} = 0.85 {+-} 0.06(stat.) {+-} 0.07(syst.)(preliminary).
Date: July 9, 1999
Creator: Muller, David
Partner: UNT Libraries Government Documents Department

Analysis of polarimeter data for the 2001-2002 RHIC run.

Description: The results of several studies of the 200-MeV (LINAC), AGS (E880), and RHIC polarimeter data from the polarized proton run in 2001/2002 are presented. Much of this work occurred during or immediately after the run. Some of these analyses have implications for the understanding of the performance of the polarized ion source, AGS, and RHIC with polarized protons. Some of the conclusions include: (A) A recalibration of the 200-MeV polarimeter gives results consistent with the older calibration, but high rates in the 200-MeV polarimeter are still a problem. (B) No evidence of sizable systematic effects was found in several tests of the AGS polarimeter with a thin carbon fiber target. (C) Significant polarization loss in the AGS was observed above G{sub {gamma}} = 7.5 but not between injection and G{sub {gamma}} = 7.5. (D) The magnitude of the flattop asymmetry in the RHIC polarimeters decreases with time in a fill. (E) The RHIC polarimeter analyzing power on flattop is greater than or equal to that at injection. (F) Unexplained systematic effects were observed in the RHIC polarimeter, but the implications for the measured polarization asymmetry are not clear. These effects were not isolated events, but occurred throughout the run. Conceivably the data could indicate that the present RHIC polarimeter design will not be able to achieve a goal of a {+-} 5% measurement of the beam polarization.
Date: December 22, 2003
Creator: Bravar, A.; Bunce, G.; Cadman, R. V.; Huang, H.; Jinnouchi, O.; Krueger, K. et al.
Partner: UNT Libraries Government Documents Department

Studies and proposed changes to the RHIC p-Carbon polarimeters for the upcoming RUN-11

Description: The RHIC polarized proton complex utilizes polarimeters in each of the Blue and Yellow beams that measure the beam polarization through the p-Carbon elastic scattering process in the Coulomb Nuclear Interference kinematic region. This along with a Polarized Hydrogen Jet Target that utilizes the proton-proton elastic scattering process to first measure the analyzing power of the reaction and using the reverse process to measure the beam polarization. The latter is used to calibrate the p-Carbon polarimeters at the desired beam energy. In Run 9 RHIC ran with beams at center-of-mass energies of 200 and 500 GeV respectively. The higher beam intensities as well as the fact that the 250 GeV beam size is much smaller than that at 100 GeV resulted in significantly higher rates seen by the polarimeters and led to observed instability. In this paper, we will discuss the problems encountered and the tests that were carried out using the AGS as a proxy in an attempt to solve the problems and the path forward we took towards the upcoming polarized proton Run11.
Date: September 27, 2010
Creator: Makdisi, Y.; Alekseev, I.; Aschenauer, E.; Atoian, G.; Bazilevsky, A.; Gill, R. et al.
Partner: UNT Libraries Government Documents Department

HIGH ENERGY HADRON POLARIMETRY.

Description: Proton polarimetry at RHIC uses the interference of electromagnetic (EM) and hadronic scattering amplitudes. The EM spin-flip amplitude for protons is responsible for the proton's anomalous magnetic moment, and is large. This then generates a significant analyzing power for small angle elastic scattering. RHIC polarimetry has reached a 5% uncertainty on the beam polarization, and seem capable of reducing this uncertainty further. Polarized neutron beams ax also interesting for RHIC and for a polarized electron-polarized proton/ion collider in the fume. In this case, deuterons, for example, have a very small anomalous magnetic moment, making the approach used for protons impractical. Although it might be possible to use quasielastic scattering from the protons in the deuteron to monitor the polarization. 3-He beams can provide polarized neutrons, and do have a large anomalous magnetic moment, making a similar approach to proton polarimetry possible.
Date: September 10, 2007
Creator: BUNCE,G.
Partner: UNT Libraries Government Documents Department

Polarimetery for SuperB

Description: We provide an overview description of a Compton polarimeter for measuring electron beam polarization near the IR in the Low Energy Ring of SuperB. The polarimeter is designed to achieve 1.0% accuracy. A scheme for measuring the electron beam polarization at SuperB near the IR has been described. The Compton polarimeter has been designed to fit into the existing lattice of the SuperB ring and results in a Compton IP measuring the polarization located where the beam is almost longitudinal with opposite helicity to that at the IR. The polarization at the IR is expected to be determined with an accuracy of {approx}1% from the measurement at the Compton IP provided the beam direction at the electron-positron interaction region and the Compton IP are well known and the beam energy is measured to better than 20 MeV. Detailed detector studies are needed to study resolution and acceptance effects on detector analyzing powers, and to determine sensitivity to beam and machine parameters.
Date: July 6, 2012
Creator: Sullivan, Michael; /SLAC; Field, R.; /SLAC; Moffeit, Kenneth; /SLAC et al.
Partner: UNT Libraries Government Documents Department

SPIN EFFECTS IN LARGE RAPIDITY NEUTRAL PION PRODUCTION AT STAR.

Description: Measurements by the STAR collaboration of neutral pion production at large Feynman x (x{sub F}) in the first polarized proton collisions at {radical}s = 200 GeV were reported previously. During the following two runs additional statistics were acquired with an improved forward calorimeter for the {pi}{sup 0} cross-section and analyzing power measurements. First data from pp collisions at {radical}s = 410 GeV were taken during the RHIC run that ended in June, 2005. The cross section was measured at {eta} = 3.3, 3.8 and 4.0 and was found to be consistent with next-to-leading order perturbative QCD calculations. The analyzing power was found to be zero at negative 23 and at positive x{sub F} up to 0.3, then increased with increasing x{sub F}. This behavior can be described by phenomenological models including the Sivers effect, the Collins effect or higher twist contributions in initial and final states. Results for the analyzing power at {eta} = 3.7 and 4.0 from all data acquired at {radical}s = 200 GeV and the status of the analysis of the {radical}s = 410 GeV data will be presented. Future upgrade plans and status will also be discussed.
Date: September 27, 2005
Creator: MOROZOV, D.A. (FOR THE STAR COLLABORATION)
Partner: UNT Libraries Government Documents Department

Strong interaction physics with pions at LAMPF: Report of the study group on future opportunities at LAMPF

Description: The LAMPF accelerator, with its high-intensity teams of pions and array of high-resolution spectrometers, provides opportunities for investigations of nuclear structure as well as of strong-interaction hadron dynamics. During operation of LAMPF as a national users facility, Nuclear Physics has undergone an evolution in the way it pictures nuclei: from a system of nucleons interacting through potentials to a system of mutually coupled nucleons, {Delta}(1232)`s, and mesons. While nuclear physics is in the midst of yet another shift of paradigm, with quarks and gluons playing a central role, the traditional picture still has great predictive power, and LAMPF has new opportunities to contribute to solving problems of current interest. At the same time, LAMPF is poised to make important contributions to the evolving area of nonperturbative QCD, where we will be learning how to connect phenomena at large momentum transfer to those at lower momentum scales. where the physically observable hadrons are the natural degrees of freedom. Within the traditional area, exploration of nuclei having extreme ratios of neutron/proton number is of growing interest in a variety of contexts, including astrophysics. Pion double charge exchange (the ({pi}{sup {plus_minus}}, {pi}{sup {plus_minus}}) processes) can produce proton-rich nuclei such as {sup 9}C, {sup 10}C, and {sup 11}N as well as neutron-rich nuclei such as {sup 10}He, {sup 11}Li, {sup 14}Be, and {sup 17}B. With spectrometers available for analyzing the outgoing pion spectra, one can study interesting and controversial modes of motion (soft-dipole modes) and obtain angular distributions that explore the spatial extent of neutron halos.
Date: July 1, 1995
Creator: Johnson, M.B. & Matthews, J.L.
Partner: UNT Libraries Government Documents Department

Asymmetry in inclusive {pi}{sup {+-}}, p production at 22 GeV, BNL E925

Description: Preliminary results from Experiment E925 on inclusive pion asymmetries from a 22 GeV/c polarized proton beam on a carbon target show significant asymmetries for {pi}{sup {+-}} production similar to those observed earlier at the ZGS and Fermilab with beams of 12 and 200 GeV respectively. This experiment demonstrates the viability of using the analyzing power in inclusive pion production for high energy beam polarimetry at RHIC. Inclusive proton asymmetries are consistent with zero.
Date: December 31, 1998
Creator: Makdisi, Y.; Allgower, C. & Bai, M.
Partner: UNT Libraries Government Documents Department

Spin physics at RHIC a new twist on the heavy ion experiments

Description: Operation of RHIC with two beams of highly polarized protons (70%, either longitudinal or transverse) at high luminosity ???? = 2 {circ} 10{sup 32} cm{sup -2} sec{sup -1} for two months/year will allow high statistics studies of polarization phenomena in the perturbative region of hard scattering where both QCD and ElectroWeak theory make detailed predictions for polarization effects. The collision c.m energy, {radical}s = 200 - 500 GeV, represents a new domain for the study of spin. Direct photon production win be used to measure the gluon polarization in the polarized proton. A new twist comes from W-boson production which is expected to be 100% parity violating and will thus allow measurements of flavor separated quark and antiquark (u, u, d, d) polarization distributions. Searches for parity violation in strong interaction processes such as jet and leading particle production will be a sensitive way to look for new physics beyond the standard model, one possibility being quark substructure.
Date: July 3, 1996
Creator: Tannenbaum, M.J.
Partner: UNT Libraries Government Documents Department

Determination of electroweak parameters at the SLC

Description: We present an improved measurement of the left-right cross section asymmetry (A{sub LR}) for Z{sup 0} boson production by e{sup +}e{sup -} collisions. The measurement was performed at a center-of-mass energy of 91.28 GeV with the SLD detector at the SLAC Linear Collider (SLC) during the 1994-95 running period. The luminosity-weighted average polarization of the SLC electron beam during this run was measured to be (77.23 {+-} 0.52)%. Using a sample of 93,644 hadronic Z{sup 0} decays, we measure the pole asymmetry A{sub LR}{sup 0} to be 0.1512 {+-} 0.0042(stat.) {+-} 0.0011(syst.) which is equivalent to an effective weak mixing angle of sin{sup 2} {theta}{sub W}{sup eff} = 0.23100 {+-} 0.00054(stat.) {+-} 0.00014(syst.). We also present a preliminary direct measurement of the Z{sup 0}-lepton coupling asymmetries A{sub e}, A{sub {mu}}, and A{sub {tau}} extracted from the differential cross section observed in leptonic Z{sup 0} decays. We combine these results with our previous A{sub LR} measurement to obtain a combined determination of the weak mixing angle sin{sup 2} {theta}{sub W}{sup eff} = 0.23061 {+-} 0.00047.
Date: September 1, 1996
Creator: Torrence, E.
Partner: UNT Libraries Government Documents Department

Spin physics at RHIC

Description: Operation of RHIC with two beams of highly polarized protons (70%, either longitudinal or transverse) at high luminosity L = 2 x 10{sup 32} cm{sup -2} sec{sup -1} for two months/year will allow the STAR and PHENIX detectors to perform high statististics studies of polarization phenomena in the perturbative region of hard scattering where both QCD and ElectroWeak theory make detailed predictions for polarization effects. The collision c.m. energy, {radical}s = 200 - 500 GeV, represents a new domain for the study of spin. Direct photon production will be used to measure the gluon polarization in the polarized proton. A new twist comes from W-boson production which is expected to be 100% parity violating and will thus allow measurements of flavor separated Quark and antiquark (u, {bar u}, d, {bar d}) polarization distributions. Searches for parity violation in strong interaction processes such as jet and leading particle production will be a sensitive way to look for new physics beyond the standard model, one possibility being quark substructure.
Date: September 6, 1996
Creator: Tannenbaum, M.J.
Partner: UNT Libraries Government Documents Department