Download or read book Single Spin Asymmetries in Elastic Electron nucleon Scattering written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We discuss the target and beam normal spin asymmetries in elastic electron-nucleon scattering which depend on the imaginary part of two-photon exchange processes between electron and nucleon. In particular, we estimate these transverse spin asymmetries for beam energies below 2 GeV, where the two-photon exchange process is dominated from the resonance contribution to the doubly virtual Compton scattering tensor on the nucleon.
Download or read book Resonance Estimates for Single Spin Asymmetries in Elastic Electron nucleon Scattering written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We discuss the target and beam normal spin asymmetries in elastic electron-nucleon scattering which depend on the imaginary part of two-photon exchange processes between electron and nucleon. We express this imaginary part as a phase space integral over the doubly virtual Compton scattering tensor on the nucleon. We use unitarity to model the doubly virtual Compton scattering tensor in the resonance region in terms of [gamma]* N → [pi] N electroabsorption amplitudes. Taking those amplitudes from a phenomenological analysis of pion electroproduction observables, we present results for beam and target normal single spin asymmetries for elastic electron-nucleon scattering for beam energies below 1 GeV and in the 1-3 GeV region, where several experiments are performed or are in progress.
Download or read book Beam Normal Single Spin Asymmetry in Forward Angle Inelastic Electron Proton Scattering Using the Q Weak Apparatus written by and published by . This book was released on 2014 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Q-weak experiment in Hall-C at the Thomas Jefferson National Accelerator Facility has made the first direct measurement of the weak charge of the proton through the precision measurement of the parity-violating asymmetry in elastic electron-proton scattering at low momentum transfer. There is also a parity conserving Beam Normal Single Spin Asymmetry or transverse asymmetry (B_n) on H_2 with a sin(phi)-like dependence due to two-photon exchange. If the size of elastic B_n is a few ppm, then a few percent residual transverse polarization in the beam, combined with small broken azimuthal symmetries in the detector, would require a few ppb correction to the Q-weak data. As part of a program of B_n background studies, we made the first measurement of B_n in the N-to-Delta(1232) transition using the Q-weak apparatus. The final transverse asymmetry, corrected for backgrounds and beam polarization, was found to be B_n = 42.82 ± 2.45 (stat) ± 16.07 (sys) ppm at beam energy E_beam = 1.155 GeV, scattering angle theta = 8.3 deg, and missing mass W = 1.2 GeV. B_n from electron-nucleon scattering is a unique tool to study the gamma*̂ Delta Delta form factors, and this measurement will help to improve the theoretical models on beam normal single spin asymmetry and thereby our understanding of the doubly virtual Compton scattering process. To help correct false asymmetries from beam noise, a beam modulation system was implemented to induce small position, angle, and energy changes at the target to characterize detector response to the beam jitter. Two air-core dipoles separated by 1̃0 m were pulsed at a time to produce position and angle changes at the target, for virtually any tune of the beamline. The beam energy was modulated using an SRF cavity. The hardware and associated control instrumentation will be described in this dissertation. Preliminary detector sensitivities were extracted which helped to reduce the width of the measured asymmetry. The beam modulation system has also proven valuable for tracking changes in the beamline optics, such as dispersion at the target.
Download or read book Transverse Beam Spin Asymmetries in Forward Angle Elastic Electron Proton Scattering written by and published by . This book was released on 2007 with total page 2301 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have measured the beam-normal single-spin asymmetry in elastic scattering of transversely-polarized 3 GeV electrons from unpolarized protons at Q^2 values of 0.15 and 0.25 (GeV/c)^2 with results of A_n = -4.06 +- 0.99(stat) +- 0.63(syst) and A_n = -4.82 +- 1.87(stat) +- 0.98(syst) ppm. These results are inconsistent with calculations solely using the elastic nucleon intermediate state, and generally agree with calculations with significant inelastic hadronic intermediate state contributions. A_n provides a direct probe of the imaginary component of the two-photon exchange amplitude, the complete description of which is important in the interpretation of data from precision electron-scattering experiments.
Download or read book Single spin Asymmetries from Two photon Exchange in Elastic Electron Proton Scattering written by N. P. Merenkov and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The parity-conserving single-spin beam asymmetry of elastic electron-proton scattering is induced by an absorptive part of the two-photon exchange amplitude. We demonstrate that this asymmetry has logarithmic and double-logarithmic enhancement due to contributions of hard collinear quasi-real photons. An optical theorem is used to evaluate the asymmetry in terms of the total photoproduction cross section on the proton.
Download or read book Measurement of Single Spin Asymmetries in Semi Inclusive Deep Inelastic Scattering Reaction N u2191 e E X at Jefferson Lab written by and published by . This book was released on 2010 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: What constitutes the spin of the nucleon? The answer to this question is still not completely understood. Although we know the longitudinal quark spin content very well, the data on the transverse quark spin content of the nucleon is still very sparse. Semi-inclusive Deep Inelastic Scattering (SIDIS) using transversely polarized targets provide crucial information on this aspect. The data that is currently available was taken with proton and deuteron targets. The E06-010 experiment was performed at Jefferson Lab in Hall-A to measure the single spin asymmetries in the SIDIS reaction n↑(e, e'?±/K±)X using transversely polarized 3He target. The experiment used the continuous electron beam provided by the CEBAF accelerator with a beam energy of 5.9 GeV. Hadrons were detected in a high-resolution spectrometer in coincidence with the scattered electrons detected by the BigBite spectrometer. The kinematic coverage focuses on the valence quark region, x = 0.19 to 0.34, at Q2 = 1.77 to 2.73 (GeV/c)2. This is the first measurement on a neutron target. The data from this experiment, when combined with the world data on the proton and the deuteron, will provide constraints on the transversity and Sivers distribution functions on both the u and d-quarks in the valence region. In this work we report on the single spin asymmetries in the SIDIS n↑(e, e'?+)X reaction.
Download or read book First Measurements of the Parity violating and Beam normal Single spin Asymmetries in Elastic Electron aluminum Scattering written by Kurtis David Bartlett and published by . This book was released on 2018 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Qweak collaboration has made the first measurements of the elastic parity-violating and beam-normal single-spin asymmetries from the $^{27}$Al nucleus. Both are the result of ancillary measurements conducted during the Qweak experiment at Jefferson Lab. The goal of the experimental was to determine the proton's weak charge, $Q_{W}^{p}$, via a measurement of the elastic parity-violating electron-proton scattering asymmetry. During the experiment, ancillary measurements were made with different beam configurations on a separate aluminum alloy target, in an effort to directly measure the aluminum background coming from the experiment's liquid hydrogen target cell. This dissertation discusses three primary results: the parity-violating $^{27}$Al asymmetry analysis used to correct for the aluminum target background in the final Qweak analysis, its extended analysis leading to the extraction of the pure elastic parity-violating {\aluminum} asymmetry, and the determination of the elastic beam-normal single-spin $^{27}$Al asymmetry. The parity-violating result was also used to make a semi model-independent determination of $^{27}$Al neutron distribution radius, an important test for models used to describe neutron-rich matter. The beam-normal single-spin asymmetry stands to possibly shed light on an observed disagreement between theory and a previous measurement performed on $^{208}$Pb, as $^{27}$Al is the next highest atomic mass nucleus to have this observable measured. The elastic parity-violating $^{27}$Al asymmetry was found to be $1.927 \pm 0.173$ ppm at $\langle Q^{2} \rangle = 0.0236 \pm 0.0001$ GeV$^{2}$. This measured parity-violating asymmetry implies a $^{27}$Al neutron distribution radius of $3.024 \pm 0.104$ fm. Calculating the difference between this radius and the $^{27}$Al proton distribution radius yields the neutron skin, which was found to be $0.092 \pm 0.104$ fm. This skin value is consistent with zero, within its uncertainty, and it confirms the naive expectation for a light nucleus like $^{27}$Al. The beam-normal single-spin $^{27}$Al asymmetry was found to be $-16.322 \pm 2.679$ ppm at $\langle Q \rangle = 0.154$ GeV. This value agrees with the previous observed trend of beam-normal single-spin asymmetries measured from light nuclei, which motivates the need for future measurements of higher atomic mass nuclei.
Download or read book Beam Normal Spin Asymmetries written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The beam normal spin asymmetry in elastic electron-nucleon scattering is discussed. This beam normal spin asymmetry depends on the imaginary part of two-photon exchange processes between electron and nucleon, and measures the non-forward structure functions of the nucleon. After briefly reviewing the theoretical formalism, we discuss calculations in the threshold region, in the resonance region, as well as in the diffractive region, corresponding with high energy and forward angles.
Download or read book Measurement of the Target normal Single spin Asymmetry in Quasielastic Scattering from the Reaction He3 u2191 e e written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report the first measurement of the target single-spin asymmetry, Ay, in quasi-elastic scattering from the inclusive reaction 3He↑ (e,e') on a 3He gas target polarized normal to the lepton scattering plane. Assuming time-reversal invariance, this asymmetry is strictly zero for one-photon exchange. A non-zero Ay can arise from the interference between the one- and two-photon exchange processes which is sensitive to the details of the sub-structure of the nucleon. An experiment recently completed at Jefferson Lab yielded asymmetries with high statistical precision at Q2= 0.13, 0.46 and 0.97 GeV2. These measurements demonstrate, for the first time, that the 3He asymmetry is clearly non-zero and negative with a statistical significance of (8-10)?. Using measured proton-to-3He cross-section ratios and the effective polarization approximation, neutron asymmetries of -(1-3)% were obtained. The neutron asymmetry at high Q2 is related to moments of the Generalized Parton Distributions (GPDs). Our measured neutron asymmetry at Q2=0.97 GeV2 agrees well with a prediction based on two-photon exchange using a GPD model and in addition provides a new independent constraint on these distributions.
Download or read book Measurement of Single Spin Asymmetries in Semi Inclusive Deep Inelastic Scattering Reaction N1 e E Pi sup X at Jefferson Lab written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: What constitutes the spin of the nucleon? The answer to this question is still not completely understood. Although we know the longitudinal quark spin content very well, the data on the transverse quark spin content of the nucleon is still very sparse. Semi-inclusive Deep Inelastic Scattering (SIDIS) using transversely polarized targets provide crucial information on this aspect. The data that is currently available was taken with proton and deuteron targets. The E06-010 experiment was performed at Jefferson Lab in Hall-A to measure the single spin asymmetries in the SIDIS reaction n1!e, e'[pi]{sup ±}/K{sup ±})X using transversely polarized 3He target. The experiment used the continuous electron beam provided by the CEBAF accelerator with a beam energy of 5.9 GeV. Hadrons were detected in a high-resolution spectrometer in coincidence with the scattered electrons detected by the BigBite spectrometer. The kinematic coverage focuses on the valence quark region, x = 0.19 to 0.34, at Q2 = 1.77 to 2.73 (GeV/c)2. This is the first measurement on a neutron target. The data from this experiment, when combined with the world data on the proton and the deuteron, will provide constraints on the transversity and Sivers distribution functions on both the u and d-quarks in the valence region. In this work we report on the single spin asymmetries in the SIDIS n1!e, e'[pi])X reaction.
Download or read book Recent Results of Target Single Spin Asymmetry Experiments at Jefferson Lab written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report recent results from Jefferson Lab Hall A "Neutron Transversity" experiment (E06-010). Transversely polarized target single-spin asymmetry AUT and beam-target double-spin asymmetry A{sub LT} have been measured in semi-inclusive deep-inelastic scattering (SIDIS) reactions on a polarized neutron (3He) target. Collins-type and Sivers-type asymmetries have been extracted from A{sub UT} for charged pion SIDIS productions, which are sensitive to quark transversity and Sivers distributions, correspondingly. Double spin asymmetry A{sub LT} is sensitive to a specific quark transverse momentum dependent parton distribution (TMD), the so-called "transverse helicity" (g{sub 1T}) distributions. In addition, target single-spin asymmetries A{sub y} in inclusive electron scattering on a transversely polarized 3He target in quasi-elastic and deep inelastic kinematics were also measured in Hall A.
Download or read book From Parity Violation to Hadronic Structure and more written by Serge Kox and published by Springer Science & Business Media. This book was released on 2007-06-07 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Almost 50 years after the proposal of Lee and Young in 1956 to test the hypothesis of parity violation in weak interactions and the subsequent experimental verification of parity violation by C. S. Wu, parity violation has today become a useful property of weak interactions. This is due to the fact that the focus nowadays has changed: parity violation in weak interactions is no more a topic of investigation but is used as a tool in many different fields ranging from nuclear physics to the search for the hidden extra dimensions requested by string theory. For our first workshop which took place June 5-8, 2002, at the Institut fiir Ke- physik of the Johannes Gutenberg-Universitat Mainz, we concentrated on the in vestigation of the strangeness contribution in the nucleon. This book contains the refereed and selected papers of the second workshop "From Parity Violation to Hadron Structure and more (Part II)", which took place June 8-11, in the Labo- toire de Physique Subatomique et de Cosmologie, in Grenoble. These papers appear in EPJAdirect, the electronic-only part of EPJA, and they are accessible without restrictions. They will also appear in printed form and can be ordered through Springer. The excellent presentations show the dramatic and steady progress in the accuracy of measured parity violating asymmetries over the last few years.
Download or read book Measurement of the Target normal Single spin Asymmetry in Quasielastic Scattering from the Reaction math Display written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report the first measurement of the target single-spin asymmetry, Ay, in quasi-elastic scattering from the inclusive reaction 3He1!(e, e') on a 3He gas target polarized normal to the lepton scattering plane. Assuming time-reversal invariance, this asymmetry is strictly zero for one-photon exchange. A non-zero Ay can arise from the interference between the one- and two-photon exchange processes which is sensitive to the details of the sub-structure of the nucleon. An experiment recently completed at Jefferson Lab yielded asymmetries with high statistical precision at Q2= 0.13, 0.46 and 0.97 GeV2. These measurements demonstrate, for the first time, that the 3He asymmetry is clearly non-zero and negative with a statistical significance of (8-10)[sigma]. Using measured proton-to-3He cross-section ratios and the effective polarization approximation, neutron asymmetries of -(1-3)% were obtained. The neutron asymmetry at high Q2 is related to moments of the Generalized Parton Distributions (GPDs). Our measured neutron asymmetry at Q2=0.97 GeV2 agrees well with a prediction based on two-photon exchange using a GPD model and in addition provides a new independent constraint on these distributions.
Download or read book Spin polarization Observables in Elastic Electron Scattering from Spin 1 written by and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Using the formalism of nucleon-nucleon scattering as a starting point, electron scattering from spin-1/2 nuclei is examined. It is seen that high-energy electron-nucleon scattering, for example, exhibits a remarkable simplicity when compared with that of nucleon-nucleon scattering. The 6 amplitudes and 36 nucleon-nucleon observables are reduced to 3 and 9, respectively, by the relativistic nature of the electron. The one-photon exchange mechanism finally reduces the number of amplitudes and independent observables to 2. This treatment serves to extend the spin-polarization ''language'' of hadronic scattering to that of electron scattering also. 6 refs. (LEW).
Download or read book Measurement of the Target Normal Single Spin Asymmetry Ayn in the Deep Inelastic Region from the Reaction 3He1 e E written by and published by . This book was released on 2011 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: A first measurement of the inclusive target single-spin asymmetry, Any, has been performed in deep-inelastic scattering of electrons from a 3He target polarized normal to the electron scattering plane. This asymmetry is void of contributions at the Born level, and thus is a direct observable for two-photon physics. The experiment was performed in Hall A at Thomas Jefferson National Accelerator Facility from October 2008 through early February 2009. The measurement is the first from a polarized neutron target. The final overall precision is several times better than previously existing SLAC proton data, and significantly extends the kinematic range over which the asymmetry has been measured. The asymmetry was measured at five kinematic points in the deep inelastic scattering region covering Q2 = 1 - 3 GeV2 and xB = 0.16 to 0.41. The asymmetry varied from 0.006 to 0.071 with astatistical precision at the 10-2 level.
Download or read book From Parity Violation to Hadronic Structure and more written by K. de Jager and published by Springer Science & Business Media. This book was released on 2008-06-21 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the proceedings of the third international workshop on From Parity Violation to Hadronic Structure and More. The many applications of parity violation are way beyond the scope of what Lee and Yang could have imagined fifty years after their proposal. For the physics topics discussed during this workshop, the application of parity violation has become a standard work horse allowing for the extraction of many physics topics in different experiments.
Download or read book Measurement of the Target Normal Single Spin Asymmetry Ayn in the Deep Inelastic Region from the Reaction 3He u2191 e e written by and published by . This book was released on 2011 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: A first measurement of the inclusive target single-spin asymmetry, Any, has been performed in deep-inelastic scattering of electrons from a 3He target polarized normal to the electron scattering plane. This asymmetry is void of contributions at the Born level, and thus is a direct observable for two-photon physics. The experiment was performed in Hall A at Thomas Jefferson National Accelerator Facility from October 2008 through early February 2009. The measurement is the first from a polarized neutron target. The final overall precision is several times better than previously existing SLAC proton data, and significantly extends the kinematic range over which the asymmetry has been measured. The asymmetry was measured at five kinematic points in the deep inelastic scattering region covering Q2 = 1 - 3 GeV2 and xB = 0.16 to 0.41. The asymmetry varied from 0.006 to 0.071 with astatistical precision at the 10-2 level.
