Download or read book Deeply Virtual Compton Scattering Off a Deuterium Target at the HERMES Experiment written by Aram Movsisyan and published by . This book was released on 2011 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Deeply Virtual Compton Scattering of Unpolarised Deuterium at HERMES written by Gordon D. Hill and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The HERMES experiment was a forward angle spectrometer on the HERA storage ring at DESY, Hamburg, Germany. HERMES successfully increased understanding of the 'spin puzzle', the spin structure of the nucleon, by providing high precision measurements of [Delta][Sigma] in the Quark Parton Model, the fraction of the spin carried by the current quarks. Following the link of another piece of the puzzle, the orbital angular momentum of quarks and gluons, to the Generalised Parton Distribution (GPD) theoretical framework, HERMES focused on measurements of the Deeply Virtual Compton Scattering (DVCS) process. These measurements are sensitive to GPDs, allowing further experimental constraints to be made on the components of nucleon spin. In the Winter shutdown period 2005-2006 HERMES was upgraded with a Recoil Detector in the target region. This allowed the experiment to make exclusive measurements of the DVCS process for the first time, reducing background and increasing the resolution of various kinematic variables. The method for reconstructing particle tracks in the inhomogeneous magnetic field is investigated here. DVCS off a deuterium target is measured with all available data prior to the installation of the Recoil Detector. A comparison is made to currently available models of spin-1/2 GPDs. This analysis has been approved for publication by the HERMES collaboration. The data is further employed in an investigation of a model dependent constraint of the total angular momentum of up and down quarks in the nucleon.
Download or read book Deeply Virtual Compton Scattering Off an Unpolarized Hydrogen Target at the HERMES Experiment written by Dietmar Zeiler and published by . This book was released on 2009 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Deeply Virtual Compton Scattering Off Unpolarised Deuterium at HERMES written by Gordon D. Hill and published by . This book was released on 2008 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Deeply Virtual Compton Scattering Off an Unpolarised Hydrogen Target at HERMES written by Jonathan R. T. Burns and published by . This book was released on 2010 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Deeply Virtual Compton Scattering Off an Unpolarised Hydrogen Target Using the Recoil Detector at HERMES written by Jennifer Ruth Bowles and published by . This book was released on 2012 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spin 2004 Proceedings Of The 16th International Spin Physics Symposium And Workshop On Polarized Electron Sources And Polarimeters With Cd rom written by Franco Bradamante and published by World Scientific. This book was released on 2005-08-02 with total page 1065 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comprehensive volume covers the most recent advances in the field of spin physics, including the latest research in high energy and nuclear physics and the study of nuclear spin structure. The comprehensive coverage also includes polarized proton and electron acceleration and storage as well as polarized ion sources and targets. Many significant new results and achievements on the different topics considered at the symposium are presented in this book for the first time.
Download or read book Deeply Virtual Compton Scattering Off Helium 4 written by Mohammad Hattawy and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Generalized Parton Distributions (GPDs) are rich structure functions that contain information on quark/anti-quark correlations, and on correlation between longitudinal momentum and the transverse spatial position of partons. These GPDs are accessible via hard exclusive reactions such as Deeply Virtual Compton Scattering (DVCS), i.e. the leptoproduction of a real photon where the photon is emitted by the target hadron. Nuclear DVCS opens a new avenue to explore the nature of medium modifications at the partonic level. In this work, we present the first exclusive measurement of the DVCS process off helium-4 with a longitudinally polarized electron beam of 6 GeV using the CLAS detector in the experimental Hall-B at Jefferson Lab, USA. The helium-4 is of particular interest since the number of GPDs is reduced to one, because of its spin zero. The aim of this study is to understand the nuclear medium modifications of parton distributions. In our experiment, the CLAS detector was upgraded with a Radial Time Projection Chamber (RTPC) to detect the low-energy recoil nuclei, and an Inner Calorimeter (IC) to detect the forward going photons. The details of the structure, calibration and working principle of the RTPC will be presented. Then, the measurement of the beam-spin asymmetries in the DVCS channel will be presented.
Download or read book The IVth International Conference on Quarks and Nuclear Physics written by Antonio Dobado and published by Springer Science & Business Media. This book was released on 2008-11-07 with total page 615 pages. Available in PDF, EPUB and Kindle. Book excerpt: The QNP series of international conferences on Quarks and Nuclear Physics is by now a well established and highly respected forum where the most recent developments in the field are discussed and communicated. QNP 2006 is the forth edition of this biennial meeting. Selected and refereed original contributions of QNP 2006 have been published in The European Physical Journal A - Hadrons and Nuclei (EPJ A), while the present proceedings book, in addition to reprinting the articles published in EPJ A, further includes all other contributions selected and accepted by the organizing committee for publication and archiving.
Download or read book Deeply Virtual Compton Scattering Off Nuclei written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Deeply virtual Compton scattering (DVCS) is the golden exclusive channel for the study of the partonic structure of hadrons, within the universal framework of generalized parton distributions (GPDs). This paper presents the aim and general ideas of the DVCS experimental program off nuclei at the Jefferson Laboratory. The benefits of the study of the coherent and incoherent channels to the understanding of the EMC (European Muon Collaboration) effect are discussed, along with the case of nuclear targets to access neutron GPDs.
Download or read book Deeply Virtual Compton Scattering at Jefferson Laboratory written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The generalized parton distributions (GPDs) have emerged as a universal tool to describe hadrons in terms of their elementary constituents, the quarks and the gluons. Deeply virtual Compton scattering (DVCS) on a proton or neutron ($N$), $e N \rightarrow e' N' \gamma$, is the process more directly interpretable in terms of GPDs. The amplitudes of DVCS and Bethe-Heitler, the process where a photon is emitted by either the incident or scattered electron, can be accessed via cross-section measurements or exploiting their interference which gives rise to spin asymmetries. Spin asymmetries, cross sections and cross-section differences can be connected to different combinations of the four leading-twist GPDs (${H}$, ${E}$, ${\tilde{H}}$, ${\tilde{E}}$) for each quark flavors, depending on the observable and on the type of target. This paper gives an overview of recent experimental results obtained for DVCS at Jefferson Laboratory in the halls A and B. Several experiments have been done extracting DVCS observables over large kinematics regions. Multiple measurements with overlapping kinematic regions allow to perform a quasi-model independent extraction of the Compton form factors, which are GPDs integrals, revealing a 3D image of the nucleon.
Download or read book Physics Division Annual Report written by Argonne National Laboratory. Physics Division and published by . This book was released on 2004 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Separation of Contributions from Deeply Virtual Compton Scattering and Its Interference with the Bethe Heitler Process in Measurements on a Hydrogen Target written by and published by . This book was released on 2009 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Separation of Contributions from Deeply Virtual Compton Scattering and Its Interference with the Bethe Heitler Process in Measurements on a Hydrogen Target written by and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book SPIN 2002 written by Yousef I. Makdisi and published by American Institute of Physics. This book was released on 2003-09-04 with total page 1198 pages. Available in PDF, EPUB and Kindle. Book excerpt: The SPIN 2002 Proceedings describe the recent advances in the field of spin physics. The topics cover research in high energy and nuclear physics and the study of the nuclear spin structure. The symposium also covers advances in polarized proton and electron acceleration and storage as well as polarized ion sources and targets. The first measurement of spin physics observables in pp collisions at center of mass energy of 200 Gev was announced at this symposium.
Download or read book Deeply Virtual Compton Scattering with CLAS12 written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An overview is given about the capabilities provided by the JLab 12 GeV Upgrade to measure deeply virtual exclusive processes with high statistics and covering a large kinematics range in the parameters that are needed to allow reconstruction of a spatial image of the nucleon's quark structure. The measurements planned with CLAS12 will cross section asymmetries with polarized beams and with longitudinally and transversely polarized proton targets in the constrained kinematics $x = \pm \xi$. In addition, unpolarized DVCS cross sections, and doubly polarized beam target asymmetries will be measured as well. In this talk only the beam and target asymmetries will be discussed.
Download or read book Deeply Virtual Compton Scattering at COMPASS written by Johannes Vincenzo Giarra and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studying hard exclusive reactions in lepton-nulceon scattering like for e.g. hard exclusive photoproduction in Deeply Virtual Compton Scattering (DVCS), allows to study the 3-dimensional nucleon structure in the framework of Generalized Parton Distribution functions (GPDs). From the DVCS cross section, combinations of Compton Form Factors (CFFs) can be extracted, which are used to further constrain the related GPDs. In 2016 and 2017, COMPASS measured DVCS on a 2.5 m long liquid hydrogen target using high energy (160 GeV), positively and negatively charged polarized muon beams provided by the M2 beamline of the SPS at CERN. The scattered muons and the produced real photons were detected by the COMPASS spectrometer, which was supplemented by an additional electromagnetic calorimeter for the detection of large-angle photons. To perform an exclusive measurement of the full final state, the target was surrounded by a barrel-shaped time-of-flight system to detect the recoiling target protons. The exclusive photon event sample is extracted using a dedicated event selection to identify all participating particles. This event selection includes the use of exclusivity conditions like for e.g. restricting the missing mass and is further improved by a kinematic fit under the assumption of the topology of a exclusive photon event. Its quality is used as an additonal selecting criterium. The fit also improves the resolution of the event kinematics, in particular on the square of the four-momentum transfer to the proton |t|. The selected data sample does not only include DVCS events, but also contributions by radiative photons produced in the Bethe-Heitler (BH) process and a background contamination by photons originating from the decay of neutral pions. These contributions are determined using dedicated Monte-Carlo samples and are subtracted from the data sample to obtain the pure DVCS contribution. The DVCS cross section is extracted in bins of |t|, separately for each beam charge and polarization. These cross section values are averaged over both beam charges, which allows to extract the |t|-dependence of the charge spin cross section sum. Studying this dependence allows to extract the slope parameter B by a binned log-likelihood fit using an exponential ansatz of the from: e^-B|t|}. The slope parameter is dominated by the contribution of the imaginary part of CFF H. At the COMPASS kinematics, which covers the x_Bj}-domain of sea quarks, it is related to the transverse extension of the proton due to the quark distributions. In the present analysis about 2/3 of the available data in 2016 are used. The 2017 sample is expected to provide two to three times higher statistics, which will allow to extend the analysis and extract the dependence of the slope parameter on x_Bj}.
