192 Matching Results

Search Results

Advanced search parameters have been applied.

Measurements of {Delta}{sigma}{sub L}(pp) and {Delta}{sigma}{sub L}({bar p}p) at 200 GeV/c

Description: A measurement was made at Fermilab of the difference in the total cross sections between states with beam and target polarizations aligned antiparallel and parallel, {Delta}{sigma}{sub L} = {Delta}{sigma}({r_reversible}) - {Delta}{sigma}({R_arrow}), using 200-GeV/c, polarized proton and antiproton beams and a polarized proton target. This measurement explores the spin dependence of particle interactions and the constituent dynamics. A difference in the spin-dependent total cross sections has been observed in previous experiments at lower energies, and this experiment was the first to explore possible spin effects in {Delta}{sigma}{sub L} at much higher energies. The polarized proton beam is produced from parity-nonconserving decays of the {Lambda}{sup 0} hyperon, where protons emitted from these decays have their spins aligned along the direction of their momenta. The {Lambda} hyperons are produced, along with other particles, when unpolarized, 800-GeV/c protons strike a beryllium target. A virtual source of protons is produced at the target from these decays and the proton polarization is correlated to the transverse distance from the target. A beam of polarized antiprotons can be produced in an analogous manner using {bar {Lambda}{sup 0}} decays. The beam transport system goal was to produce no net spin precession and to preserve the correlation between the beam particle polarization and the transverse position at the virtual source. The beam transport used four sets of quadrupole magnets to focus the beam at intermediate and final focal points. An electronic, particle-tagging system was located at the intermediate focus, while the polarized target was near the final focus.
Date: February 1, 1995
Creator: Grosnick, D.P.
Partner: UNT Libraries Government Documents Department

Performance of the laser driven polarized hydrogen source at IUCF

Description: A laser driven source of polarized hydrogen and deuterium has been installed in the Cooler Ring at the Indiana University Cyclotron Facility. Polarized nuclei from the source are injected into a storage tube, and the resulting target has been used in a scattering experiment with 200 MeV proton beam. This paper discusses the performance of the source, including measurements of atomic fraction and electron polarization.
Date: October 1997
Creator: Cadman, R. V.; Bailey, K. & Brack, J.
Partner: UNT Libraries Government Documents Department

The Argonne laser-driven D target: Recent developments and progress

Description: The first direct measurements of nuclear tensor polarization p{sub zz} in a laser-driven polarized D target have been performed at Argonne. We present p{sub zz} and electron polarization P{sub e} data taken at a magnetic field of 600 G in the optical pumping cell. These results are highly indicative that spin-temperature equilibrium is achieved in the system. To prevent spin relaxation of D and K atoms as well as the molecular recombination of D atoms, the walls of the laser-driven D target are coated with organosilane compounds. We discuss a new coating technique, the {open_quotes}afterwash{close_quotes}, developed at Argonne which has yielded stable atomic fraction results when the coating is exposed to K. We also present new coating techniques for glass and Cu substrates.
Date: November 1, 1997
Creator: Fedchak, J.A.; Bailey, K. & Cummings, W.J.
Partner: UNT Libraries Government Documents Department

Fiber optic applications for laser polarized targets

Description: For the past two years, the laser polarized target group at Argonne has been used multi-mode fiber optic patch cords for a variety of applications. In this paper, the authors describe the design for transporting high power laser beams with optical fibers currently in use at IUCF.
Date: October 1, 1997
Creator: Cummings, W.J. & Kowalczyk, R.S.
Partner: UNT Libraries Government Documents Department

Effective neutron targets

Description: Because of the lack of a free neutron target, deuterium targets have been used extensively in studying the neutron structure. The unique spin structure of the {sup 3}He ground state wave function and the recent developments in laser technologies made polarized {sup 3}He targets widely used in many experiments from neutron electromagnetic form factor studies to nucleon spin structure function measurements at all major electron accelerator facilities. In this talk, the current status of the polarized {sup 3}He targets will be reviewed. The author will focus on neutron electromagnetic form factor studies using polarized {sup 3}He targets. The polarized nucleon spin structure function measurements using polarized {sup 3}He targets will also be discussed.
Date: July 1, 1997
Creator: Gao, H.
Partner: UNT Libraries Government Documents Department

Time reversal tests in polarized neutron reactions

Description: 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-violation because of the nuclear enhancements. The author has designed experiments to search for time-reversal violation in neutron-nucleus interactions. He has also developed techniques to polarize neutrons with laser-polarized {sup 3}He gas targets. Using the polarized {sup 3}He neutron spin filter, he has performed two experiments at LANSCE: an absolute neutron beam polarization measurement with an accuracy of 0.2--0.3% and a neutron spin-rotation measurement on a {sup 139}La sample.
Date: November 1, 1998
Creator: Asahi, Koichiro; Bowman, J.D. & Crawford, B.
Partner: UNT Libraries Government Documents Department

Nucleon Form Factors

Description: A review of data on the nucleon electro-weak form factors in the space-like region is presented. Recent results from experiments using polarized beams and either polarized targets or nucleon recoil polarimeters have yielded a significant improvement on the precision of the electromagnetic data obtained with the traditional Rosenbluth separation. An outlook is presented of planned experiments.
Date: October 1, 2002
Creator: Jager, Kees de
Partner: UNT Libraries Government Documents Department

Nucleon Magnetic Form Factors

Description: 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
Partner: UNT Libraries Government Documents Department

Polarized hydrogen gas target. Closeout report

Description: The purpose of the equipment was to produce a polarized gas target for use as an internal target in storage rings. The part funded under this grant was the construction of the atomic-beam apparatus. In addition to the $300,000 award, $13,267 from DOE operating funds and $19,700 provided by the University was spent on the construction of the atomic beam apparatus. Certain other parts required for the experiments, like the target cell, the target vacuum chamber, and the detectors, were funded by the University of Wisconsin. The cost for installation of the target in the cooler ring at the Indiana University Cyclotron Facility was $2,400. The equipment became operational for the first time in August 1992, after the sixpole magnets, the delivery of which was delayed by more than 6 months because of manufacturing problems, were delivered. There followed a period of measurements to optimize the atomic-beam intensity. In 1992, further work was done using other sources of funds to augment the performance of the polarized gas target by means of radiofrequency (RF) transitions intended to double the degree of polarization of the target. Immediately after the above tests, the polarized gas target equipment was shipped to Bloomington, Indiana where installation in the proton storage ring was completed in July 1993.
Date: December 31, 1994
Partner: UNT Libraries Government Documents Department

Azimuthal and single spin asymmetry in deep-inelasticlepton-nucleon scattering

Description: The collinear expansion technique is generalized to thefactorization of unintegrated parton distributions and other higher twistparton correlations from the corresponding collinear hard parts thatinvolve multiple parton final state interaction. Such a generalizedfactorization provides a consistent approach to the calculation ofinclusive and semi-inclusive cross sections of deep-inelasticlepton-nucleon scattering. As an example, the azimuthal asymmetry iscalculated to the order of 1/Q in semi-inclusive deeply inelasticlepton-nucleon scattering with transversely polarized target. Anon-vanishing single-spin asymmetry in the "triggered inclusive process"is predicted to be 1/Q suppressed with a part of the coefficient relatedto a moment of the Sivers function.
Date: September 21, 2006
Creator: Liang, Zuo-tang & Wang, Xin-Nian
Partner: UNT Libraries Government Documents Department

PION SCATTERING FROM A POLARIZED TARGET

Description: This report describes the use of a target containing polarized protons in a particle-scattering experiment. Positive pions of 246-MeV kinetic energy were scattered from the polarized protons. The parameter P that was measured is equivalent to that determined by analyzing the recoil-proton polarization in scattering from an unpolarized target. It has been measured to a higher accuracy than heretofore achieved in pion-proton scattering, at an energy and at angles inconvenient for double-scattering techniques.
Date: August 7, 1963
Creator: Chamberlain, Owen; Jeffries, Carson D.; Schultz, Claude H.; Shapiro, Gilbert & Van Rossum, Ludwig.
Partner: UNT Libraries Government Documents Department

POLARIZATION IN PION-PROTON SCATTERING FROM 670-3750 MeV/c

Description: Using a polarized proton target, we have measured the polarization parameter P({theta}) in pion-proton scattering for both positive and negative pions. Because there seems to be a great deal of current interest in the analysis of pion-proton scattering we wish to present these experimental results at this time even though we have not yet completed their analysis. The measurement consisted of scattering pions from polarized target protons and observing the asymmetry in scattered intensity, I({theta}), as the target protons spin directions were reversed. The intensity for scattering from a target of polarization P{sub T} is I({theta}){sub pol.} = I({theta}){sub unpol.} (1 + P({theta})P{sub T}), where the parameter P({theta}) is the same as the recoil proton polarization in scattering pions from unpolarized protons under the assumption that parity is conserved in the process.
Date: October 1, 1966
Creator: Chamberlain, Owen; Hansroul, Michel J.; Johnson, Claiborne H.; Grannis, Paul D.; Holloway, Leland E.; Valentin, Luc et al.
Partner: UNT Libraries Government Documents Department

Realizations of polarized targets in storage rings

Description: While particle storage rings generally provide a large average current, they require ultra-thin targets in order to maintain a reasonable lifetime of the beam. Targets composed of polarized atomic gas are well-suited for use in storage rings because of their thinness and the high degree of purity and polarization possible. Several of these so-called internal targets have been developed and successfully used to measure scattering asymmetries at Novosibirsk; future experiments have been proposed at Bates, NIKHEF, and HERA, for example, which also rely on these techniques. The methods that have so far proved feasible for producing and storing highly polarized atoms will be reviewed. 6 refs., 1 fig.
Date: January 1, 1990
Creator: Kinney, E.R.
Partner: UNT Libraries Government Documents Department

Calibration of the LAMPF E-960 polarized target

Description: This note is mainly about the offline corrections for the target polarization measurements of E-960. For the sake of minimizing the number of separate documents, I have also included my recent thoughts about the target constant, in Sec. 6. The E-960 data-taking was done in two separate runs. With respect to having an operative NMR system, the runs dated from 27-AUG-87 to 10-DEC-87 and from 14-AUG-88 to 6-OCT-88.These runs will be referred to as the ``1987`` and ``1988`` runs, respectively. Because of the press of intervening projects, I have been unable until now to give my attention to the 1988 run of E-960. The information developed below in Secs. 3--5 is the result of my (belated) attempt to do so. A draft memo dated January 4, 1988 was previously distributed, which concerned the polarization correction factors for the 1987 run. I have reproduced the material from that memo in Sec. 2, for the sake of completeness. Also, since the analysis of the 1988 run has raised some questions about the appropriateness of the older analysis, I have augmented the material from that memo with some of the background observations and calculations that underlay its conclusions, to facilitate a comparison of the two runs. In Sec. 4 I have made a final synthesis of the observations made during the two runs, and it is there that one wig find my best estimate of the offline polarization corrections for both runs.
Date: December 23, 1992
Creator: Hill, D. A.
Partner: UNT Libraries Government Documents Department

Review of the SLAC and Les Houches workshops

Description: Polarized Electron Source workshops have been held at varying intervals, beginning in 1983 when Charles Sinclair convened the first at SLAC. Since that time, three workshops were held in conjunction with the International Spin Symposia and two at other occasions. The increasing importance of polarized electron beams at accelerators has stimulated interest in these workshops. Two workshops have been held since the last International Spin Symposium in Nagoya. In 1993, a workshop was held at SLAC, and in 1994 at Les Houches, a polarized electron beam session was held as part of a polarized beam and targets workshop. This report summarizes highlights from the latter two workshops.
Date: December 1, 1994
Creator: Prescott, C. Y.
Partner: UNT Libraries Government Documents Department

Progress on Polarized Target Materials With Pure Carbon Background

Description: A previous note reviewed methods for the paramagnetic doping of materials for spin-polarized solid targets and some of the history of attempts to apply those methods to hydrocarbons. Since the earlier work on hydrocarbons had yielded, at best, rather mediocre results, that note also speculated on some ways to extend and, possibly, to improve upon the earlier work. The sharpest focus was on the light (number of carbons less than six) alkanes, since these are the hydrocarbons that have the highest hydrogen contents ({approx_gt} 17wt %) and therefore require the least degree of polarization to be interesting. This present note summarizes the subsequent work done, to date, exploring some of the issues related to the chemical doping method. The main areas of progress have been in the literature search, experimental results on glass formation by alkanes, and a polarizing test of a ``prototype`` hydrocarbon.
Date: March 24, 1993
Creator: Hill, D. A.; Crabb, D. G. & Krumpolc, M.
Partner: UNT Libraries Government Documents Department

Polarized proton target-IV. Operations manual

Description: Standard operating procedures are presented for the vacuum, cryogenic, and electronic systems of a polarized proton target. The systems are comprised of (1) a target cryostat; (2) a $sup 4$He pumping system; (3) a $sup 3$He pumping system; (4) a microwave system; (5) a magnet and power supply; (6) a computerized polarization monitor; and (7) miscellaneous auxiliary equipment. (PMA)
Date: January 1, 1976
Creator: Hill, D.; Fletcher, O.; Moretti, A. & Onesto, F.
Partner: UNT Libraries Government Documents Department

Polarized Targets for the CLAS Detector at Jefferson Lab

Description: The CEBAF Large Acceptance Spectrometer is utilized for a wide ranging physics program at Jefferson Lab, including measurements of polarized structure functions and future tests of the Gerasimov-Drell-Hearn sum rule. To realize the entire extent of the program, polarized targets that can function inside the spectrometer without severely affecting its performance are necessary. In these proceedings, I describe a continuously polarized solid target of protons and deuterons that operated inside CLAS for a total of ten months from 1998 to 2001. The conceptual design of a frozen spin target that will more fully exploit the 4 pi acceptance of CLAS is also introduced.
Date: July 1, 2002
Creator: Keith, C.D.
Partner: UNT Libraries Government Documents Department

Measurements of the total cross section difference {Delta}{sigma}{sub T} in np trnasmission between 0.86 and 0.94 GeV

Description: We present results of the total cross section difference {triangle}{sigma} {sub T} (np) obtained in transmission measurements at the energies 0.86, 0.88, 0.91 and 0.94 GeV. The SATURNE II polarized beam of free neutrons obtained from the break-up of polarized deuterons was transmitted through the polarized Saclay frozen-spin proton target. The beam and target polarizations were oriented in the vertical direction. The present results agree with previous SATURNE measurements and improve the amplitude analysis 4-n the forward direction.
Date: March 1, 1993
Creator: Ball, J.; Chesny, Ph. & Combet, M.
Partner: UNT Libraries Government Documents Department

Precision measurement of the neutron spin dependent structure functions

Description: In experiment E154 at the Stanford Linear Accelerator Center the spin dependent structure function g{sub 1}{sup n} (x, Q{sup 2}) of the neutron was measured by scattering longitudinally polarized 48.3 GeV electrons off a longitudinally polarized {sup 3}He target. The high beam energy allowed the author to extend the kinematic coverage compared to the previous SLAC experiments to 0.014 {le} x {le} 0.7 with an average Q{sup 2} of 5 GeV{sup 2}. The author reports the integral of the spin dependent structure function in the measured range to be {integral}{sub 0.014}{sup 0.7} dx g{sub 1}{sup n}(x, 5 GeV{sup 2}) = {minus}0.036 {+-} 0.004(stat.) {+-} 0.005(syst.). The author observes relatively large values of g{sub 1}{sup n} at low x that call into question the reliability of data extrapolation to x {r_arrow} 0. Such divergent behavior disagrees with predictions of the conventional Regge theory, but is qualitatively explained by perturbative QCD. The author performs a Next-to-Leading Order perturbative QCD analysis of the world data on the nucleon spin dependent structure functions g{sub 1}{sup p} and g{sub 1}{sup n} paying careful attention to the experimental and theoretical uncertainties. Using the parameterizations of the helicity-dependent parton distributions obtained in the analysis, the author evolves the data to Q{sup 2} = 5 GeV{sup 2}, determines the first moments of the polarized structure functions of the proton and neutron, and finds agreement with the Bjorken sum rule.
Date: February 1, 1997
Creator: Kolomensky, Y.G.
Partner: UNT Libraries Government Documents Department

Precise measurement of the neutron magnetic form factor from quasielastic {sup 3}{rvec H}e({rvec e},e`)

Description: Polarized {sup 3}He targets have proven to be a useful tool for studying the electric and magnetic form factors of the neutron, and the spin structure of the neutron. The neutron magnetic form factor at low Q{sup 2} was determined previously at MIT-Bates from the quasielastic {sup 3}{ital {rvec H}e({rvec e}, e{sup `})} process. New experiment was planned at TJNAF to systematically measure the inclusive {sup 3}He quasielastic transverse asymmetry, A{sub T{sup `}}, at Q{sup 2} = 0.1 - 0.5 (GeV/c){sup 2} with high statistical and systematic accuracy. A 2% statistical uncertainty is aimed at all the pro- posed values of Q{sup 2} , and 3% systematic uncertainty for A{sub T{sup `}} can be achieved for this experiment. The precise data will constrain theoretical calculations of {sup 3}He quasielastic asymmetry. Furthermore, the neutron magnetic form factor at Q{sup 2} = 0.1 - 0.5 (GeV/c){sup 2} will be extracted from the measured asymmetries with an overall uncertainty of 2%. Precise measurements of {ital G{sup n}{sub M}} at low Q{sup 2} will resolve the discrepancy among the existing data in the same Q{sup 2} region.
Date: February 1, 1997
Creator: Gao, H.
Partner: UNT Libraries Government Documents Department

Nucleon electromagnetic form factors

Description: 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: January 1, 2000
Creator: Jager, Kees de
Partner: UNT Libraries Government Documents Department