scholarly journals Measurement of the Ar(e,e′p) and Ti(e,e′p) cross sections in Jefferson Lab Hall A

2021 ◽  
Vol 103 (3) ◽  
Author(s):  
L. Gu ◽  
D. Abrams ◽  
A. M. Ankowski ◽  
L. Jiang ◽  
B. Aljawrneh ◽  
...  
Keyword(s):  
Cross Sections ◽  
Jefferson Lab

scholarly journals CHARGED PION PHOTOPRODUCTION FROM HYDROGEN AND DEUTERIUM AT JEFFERSON LAB

2003 ◽  
Vol 18 (02n06) ◽  
pp. 215-224
Author(s):  
◽  
HAIYAN GAO
Keyword(s):  
Cross Sections ◽  
Degrees Of Freedom ◽  
Charged Pion ◽  
Center Of Mass ◽  
Oscillatory Behavior ◽  
Color Transparency ◽  
Jefferson Lab ◽  
Glauber Theory ◽  
Nuclear Dependence ◽  
Exclusive Processes

The γn → π-p and γp → π+n reactions are essential probes of the transition from meson-nucleon degrees of freedom to quark-gluon degrees of feedom in exclusive processes. The cross sections of these processes are also, advantageous, for the investigation of oscillatory behavior around the quark counting prediction, since they decrease relatively slower with energy compared with other photon-induced processes. Moreover, these photoreactions in nuclei can probe the QCD nuclear filtering and color transparency effects. In this talk, I discuss the preliminary results on the γp → π+n and γn → π-p processes at a center-of-mass angle of 90° from Jefferson Lab experiment E94-104. I also discuss a new experiment in which singles γp → π+n measurement from hydrogen, and coincidence γn → π-p measurements at the quasifree kinematics from deuterium and 12 C for photon energies between 2.25 GeV to 5.8 GeV in fine steps at a center-of-mass angle of 90° are planned. The proposed measurement will allow a detailed investigation of the oscillatory scaling behavior in photopion production processes and the study of the nuclear dependence of rather mysterious oscillations with energy that previous experiments have indicated. The various nuclear and perturbative QCD approaches, ranging from Glauber theory, to quark-counting, to Sudakov-corrected independent scattering, make dramatically different predictions for the experimental outcomes.

K*(892)0Λ & K+Σ*(1385)- PHOTOPRODUCTION ON THE DEUTERON

2014 ◽  
Vol 26 ◽  
pp. 1460101 ◽  
Author(s):  
◽  
PAUL MATTIONE
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Experimental Cross Section ◽  
Differential Cross Sections ◽  
Cross Section Data ◽  
Jefferson Lab ◽  
Section Data ◽  
Experimental Cross ◽  
Using Data

Preliminary measurements of the differential cross sections of the γn → K*(892)0Λ and γn → K+Σ*(1385)- reactions are shown using data from the Jefferson Lab Hall B CLAS g13 experiment. No experimental cross section data have yet been published on the γn → K*(892)0Λ reaction, and the only published cross section data on the γn → K+Σ*(1385)- reaction are at forward angles, where t-channel K+ and K*+ exchanges are predicted to dominate. These data can be used to contribute to the search for the "missing" N* resonances, some of which are predicted to have non-negligible couplings to the excited strangeness channels.

scholarly journals MEASUREMENT OF EXCITED HYPERONS IN PHOTOPRODUCTION AT CLAS

2014 ◽  
Vol 26 ◽  
pp. 1460084
Author(s):  
◽  
KEI MORIYA ◽  
REINHARD A. SCHUMACHER
Keyword(s):  
Invariant Mass ◽  
Mass Distribution ◽  
Cross Sections ◽  
Invariant Mass Distribution ◽  
Total Cross Sections ◽  
Future Studies ◽  
Jefferson Lab ◽  
Measurement Results

Measurement results of photoproduced excited hyperon states using the CLAS detector at Jefferson Lab are shown. The invariant mass distribution of the Λ(1405) has recently been shown to be different for each of the three Σπ channels that it decays to, showing that there is prominent interference between the isospin I = 0 and I = 1 isospin amplitudes. Measurements of the differential and total cross sections of the three hyperons Λ(1405), Σ0(1385), and Λ(1520) are presented and compared. Prospects of future studies using a 12 GeV beam with the GlueX detector are briefly given.

scholarly journals Quasi elastic cross sections for the209Bi(e,e'p)208Pbreaction: Jefferson Lab experiment E06007

2012 ◽  
Vol 381 ◽  
pp. 012101
Author(s):  
J C Cornejo ◽  
J L Herraiz ◽  
A Camsonne ◽  
A Saha ◽  
J M Udias ◽  
...  
Keyword(s):  
Cross Sections ◽  
Lab Experiment ◽  
Jefferson Lab

scholarly journals Measurement of the cross sections for inclusive electron scattering in the E12-14-012 experiment at Jefferson Lab

2019 ◽  
Vol 100 (5) ◽  
Author(s):  
M. Murphy ◽  
H. Dai ◽  
L. Gu ◽  
D. Abrams ◽  
A. M. Ankowski ◽  
...  
Keyword(s):  
Electron Scattering ◽  
Cross Sections ◽  
Jefferson Lab ◽  
The Cross ◽  
Inclusive Electron

MESONS IN THE MEDIUM: EXPERIMENTS WITH CLAS AT JEFFERSON LAB

2011 ◽  
Vol 26 (03n04) ◽  
pp. 734-736 ◽  
Author(s):  
◽  
M. H. WOOD ◽  
R. NASSERIPOUR ◽  
M. PAOLONE ◽  
C. DJALALI ◽  
...  
Keyword(s):  
Cross Sections ◽  
Thomas Jefferson ◽  
Photon Beam ◽  
Elementary Reaction ◽  
Vector Mesons ◽  
Free Nucleon ◽  
Nucleon Interaction ◽  
Accelerator Facility ◽  
Jefferson Lab

In this article, we report on on investigations of the in-medium meson-nucleon interaction for the ω, ɸ, and [Formula: see text] mesons. Their in-medium cross sections and collisional widths can be measured by their absorption in a nucleus. In Hall B at the Thomas Jefferson National Accelerator Facility (JLab), the CLAS detector was used to study these long-lived mesons in nuclei. All of the mesons were produced by a photon beam with E γ < 4 GeV in targets of 2 H , C , Fe , and Pb . The vector mesons were reconstructed through their decay into e+e-. The [Formula: see text] mesons were measured with their dominant π+π- decay. The in-medium widths of the ω and ɸ mesons are found to be substantially larger than their values from the elementary reaction with a free nucleon. The analysis with the [Formula: see text] is preliminary, and its status will be discussd in this paper.

Experimental studies of Generalized Parton Distributions

2015 ◽  
Vol 30 (34) ◽  
pp. 1530058 ◽  
Author(s):  
Silvia Niccolai
Keyword(s):  
Cross Sections ◽  
Experimental Studies ◽  
Deeply Virtual Compton Scattering ◽  
Virtual Compton Scattering ◽  
Experimental Program ◽  
Real Photon ◽  
Longitudinal Momentum ◽  
Parton Distributions ◽  
Jefferson Lab ◽  
Generalized Parton Distributions

Generalized Parton Distributions (GPDs) are nowadays the object of an intense effort of research, in the perspective of understanding nucleon structure. They describe the correlations between the longitudinal momentum and the transverse spatial position of the partons inside the nucleon and they can give access to the contribution of the orbital momentum of the quarks to the nucleon spin. Deeply Virtual Compton scattering (DVCS), the electroproduction on the nucleon, at the quark level, of a real photon, is the process more directly interpretable in terms of GPDs of the nucleon. Depending on the target nucleon (proton or neutron) and on the DVCS observable extracted (cross-sections, target- or beam-spin asymmetries, etc.), different sensitivity to the various GPDs for each quark flavor can be exploited. This article is focused on recent promising results, obtained at Jefferson Lab, on cross-sections and asymmetries for DVCS, and their link to GPDs. These data open the way to a “tomographic” representation of the structure of the nucleon, allowing the extraction of transverse-space densities of the quarks at fixed longitudinal momentum. The extensive experimental program to measure GPDs at Jefferson Lab with the 12 GeV-upgraded electron accelerator and the complementary detectors that will be housed in three experimental Halls (A, B and C), will also be presented.

scholarly journals Deeply Virtual Pseudoscalar Meson Production at Jefferson Lab and Transversity GPDs

2016 ◽  
Vol 40 ◽  
pp. 1660051 ◽  
Author(s):  
Valery Kubarovsky
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Pseudoscalar Meson ◽  
Meson Production ◽  
Form Factors ◽  
Theoretical Models ◽  
Text Data ◽  
Jefferson Lab ◽  
Wide Range ◽  
First Time

The cross section of the exclusive [Formula: see text] and [Formula: see text] electroproduction reaction [Formula: see text] was measured at Jefferson Lab with a 5.75-GeV electron beam and the CLAS detector. Differential cross sections [Formula: see text] and structure functions [Formula: see text] and [Formula: see text] as functions of [Formula: see text] were obtained over a wide range of [Formula: see text] and [Formula: see text]. The data are compared with the GPD based theoretical models. Analyses find that a large dominance of transverse processes is necessary to explain the experimental results. Generalized form factors of the transversity GPDs [Formula: see text] and [Formula: see text] were directly extracted from the experimental observables for the first time. It was found that GPD [Formula: see text] dominates in pseudoscalar meson production. The combined [Formula: see text] and [Formula: see text] data opens the way for the flavor decomposition of the transversity GPDs. The first ever evaluation of this decomposition was demonstrated.

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

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