134 Matching Results

Search Results

Advanced search parameters have been applied.
in publisher: "Thomas Jefferson National Accelerator Facility U.S."  
Results: 1 - 24 next
open access

Measurement of the deuteron elastic structure functions at large momentum transfers

Description: The cross section for elastic electron-deuteron scattering has been measured using the Hall A Facility of Jefferson Laboratory. Scattered electrons and recoiling deuterons were detected in coincidence in the two 4 GeV/c High Resolution Spectrometers (HRS) of Hall A. The deuteron elastic structure functions A(Q{sup 2}) and B(Q{sup 2}) have been extracted from these data. Results for the measurement of A(Q{sup 2}) in the range of 0.7 ≤ Q{sup 2} ≤ 6.0 (GeV/c){sup 2} are reported. Results for the m… more
Date: August 1, 1999
Creator: McCormick, Kathy
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Study of Quasielastic 1p-shell proton Knockout in the {sup 16}O (e,e'p) reaction at Q{sup 2}=0.8 (GeV/c){sup 2}

Description: Coincidence cross sections and the structure functions R{sub L+TT},#2; R{sub T} and R{sub LT} have been obtained for the quasielastic #2;#3;{sup 16}O(#7;e,#2; e'p)#8; reaction with the proton knocked out from the #2;1p{sub 1/2}#2;#2;#4; and #2;1p{sub 3/2}#5;#2;#4; states in perpendicular kinematics. The nominal energy transfer #3;{omega} was 439#11; MeV#4; the nominal Q{sup 2}#4; was 0.8 (#7;GeV/#14;c){sup 2}#8;#4; and the kinetic energy of knocked-#15;out proton was 427#3;#16; MeV. The data wa… more
Date: June 1, 1999
Creator: Gao, Juncai
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Measurement of recoil polarization in the {sup 16}O(e,e'p) reaction.

Description: The longitudinal and transverse components of the polarization of the outgoing proton were measured for the reaction {sup 16}O(e,e'p) at a four-momentum transfer squared of 0.8 GeV{sup 2} in quasifree kinematics. These were the first measurements of polarization transfer observables for a complex nucleus. Comparison of the ratio of the transverse and longitudinal polarization to theoretical predictions allows the study of modification of the proton's form factors in the nuclear medium.
Date: July 1, 1999
Creator: Jones, Mark
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

A study of the {sup 16}O (e, e'p) reaction at deep missing energies

Description: The {sup 16}O(e,e'p)#8; reaction was studied in the #6;first physics experiment performed at Jefferson lab Hall A. In the quasielastic region cross sections were measured for both quasi#11;parallel and perpendicular kinematics at q = 1000 MeV and #2;{omega} = 445#14;#14;#15; MeV. From the data acquired in quasi#11;parallel kinematics#4; longitudinal and transverse response functions#4; R{sub L} and R{sub T} were separated for E{sub miss} < 60 MeV. The perpendicular kinematics data were used to … more
Date: February 1, 1999
Creator: Liyanage, Nilanga
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Measurement of the Electric and Magnetic Elastic Structure Functions of the Deuteron at Large Momentum Transfers

Description: The deuteron elastic structure functions, A(Q{sup 2}) and B(Q{sup 2}), have been extracted from cross section measurements of elastic electron-deuteron scattering in coincidence using the Continuous Electron Beam Accelerator and Hall A Facilities of Jefferson Laboratory. Incident electrons were scattered off a high-power cryogenic deuterium target. Scattered electrons and recoil deuterons were detected in the two High Resolution Spectrometers of Hall A. A(Q{sup 2}) was extracted from forward an… more
Date: October 1, 1999
Creator: Suleiman, Riad
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

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 … more
Date: January 1, 1999
Creator: Zhou, Z.-L.; Bouwhuis, M.; Ferro-Luzzi, M.; Passchier, E.; Alarcon, R.; Anghinolfi, M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

CDEV-NT: Porting the Control Device Interface to Windows NT

Description: In recent years the rapid increase in processing power of the personal computer has made it a significant competitor to high-end workstations for accelerator control and experimental physics applications. When the decreasing price of the PC and the availability of inexpensive commercial software is also considered, NT becomes a very attractive alternative to traditional UNIX systems. In order to simplify the integration of Personal Computers into our operating environment, we have ported the Co… more
Date: October 1, 1999
Creator: Akers, W.; Chen, J. & Watson, C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

First Lasing of the Jefferson Lab IR Demo FEL

Description: As reported previously [1], Jefferson Lab is building a free-electron laser capable of generating a continuous wave kilowatt laser beam. The driver-accelerator consists of a superconducting, energy-recovery accelerator. The initial stage of the program was to produce over 100 W of average power with no recirculation. In order to provide maximum gain the initial wavelength was chosen to be 5 mu-m and the initial beam energy was chosen to be 38.5 MeV. On June 17, 1998, the laser produced 155 Watt… more
Date: May 1, 1999
Creator: Benson, Stephen; Biallas, George; Bohn, Court; Douglas, David; Dylla, H.F.; Evans, R. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Spin measurements in high -t exclusive photoreactions

Description: The approximate validity of the constituent counting rules to few GeV photoreactions has been known for many years. It is now generally accepted that perturbative QCD, which leads to these rules, cannot be applicable in this low energy and momentum transfer regime. Cross section and polarization measurements now underway show promise to lead to the underlying physics. Initial experiments on deuteron photodisintegration and pion electroproduction are now in progress, and are expected to be follo… more
Date: May 1, 1999
Creator: Gilman, Ron
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Electroproduction of strangeness above the resonance region

Description: A simple and elegant model, based on Reggeized t-channel exchanges, is successful in reproducing the main features of all existing data of the reactions ep--&gt;e'K{sup +}Sigma{sup 0}. In particular, the original way in which gauge invariance is taken into account is found to be essential to describe the ration between the Coulomb and the transverse cross sections at large Q{sup 2} that has been measured recently at Jefferson Laboratory.
Date: April 1, 1999
Creator: Guidal, Michel; Laget, Jean-Marc & Vanderhaeghen, M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

High precision beam based RF stabilization at Jefferson Lab

Description: A non-invasive monitor has been implemented for the relative phase of the beam and the accelerating RF of each of the two CW superconducting linacs at TJNAF. Its noise level and resolution are below 0.1 degrees at beam currents as low as 2 microamperes, and it has been successfully tested for use in feedback correction for the overall RF accelerating phase of each linac. The 70 MHz frequency reference in each linac is phase modulated by approximately {+-} 0.05 degrees at different frequencies (… more
Date: March 1, 1999
Creator: Tiefenback, T. G.; Lebedev, V. A. & Musson, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

The impact of coherent synchrotron radiation on the beam transport of short bunches

Description: Designs for next-generation accelerator, such as future linear colliders and short-wavelength FEL drivers, require beams of short (mm-length or smaller) bunches and high charge (nC-regime). As such a high charge microbunch traverses magnetic bends, the curvature effect on the bunch self-interaction, by way of coherent synchrotron radiation (CSR) and space charge force, may cause serious emittance degradation. This impact of CSR on the beam transport of short bunches has raised significant conce… more
Date: April 1, 1999
Creator: Li, R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Feynman-Schwinder representation approach to nonperturbative physics

Description: The Feynman-Schwinger representation provides a convenient framework for the calculation of nonperturbative propagators. In this paper the authors first investigate an analytically solvable case, namely the scalar QED in 0+1 dimension. With this toy model they illustrate how the formalism works. The analytic result for the self energy is compared with the perturbative result. Next, using a {chi}{sup 2} {phi} interaction, they discuss the regularization of various divergences encountered in this… more
Date: June 1, 1999
Creator: Savkli, C.; Tjon, J. & Gross, F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

The Automator: Intelligent Control System Monitoring

Description: A large-scale control system may contain several hundred thousand control points which must be monitored to ensure smooth operation. Knowledge of the current state of such a system is often implicit in the values of these points and operators must be cognizant of the state while making decisions. Repetitive operators requiring human intervention lead to fatigue, which can in turn lead to mistakes. The authors propose a tool called the Automator based on a middleware software server. This tool w… more
Date: March 1, 1999
Creator: Bickley, M.; Bryan, D.A. & White, K.S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Modification of the CEBAF transport dipoles for energy upgrade considerations

Description: The CEBAF accelerator at the Thomas Jefferson National Accelerator Facility contains 415 resistive dipoles in the recirculation arcs and transport lines. These dipoles were originally designed and magnetically mapped to support the operation of the accelerator at 6 GeV. Recent interests in upgrading the CEBAF energy beyond 6 GeV prompted a study into operating the dipoles beyond their design limits. Finite element modeling was performed to quantify saturation effects at higher currents and to t… more
Date: March 1, 1999
Creator: Bullard, D.; Harwood, L.; Hiatt, T.; Karn, J.; Martin, E.; Oren, W. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

The evolution of Jefferson Lab's control system

Description: Thomas Jefferson National Accelerator Facility's (Jefferson Lab) accelerator controls were initially implemented as a proprietary in-house system. During machine commissioning, problems were encountered leading to a decision to migrate to the Experimental Physics and Industrial Controls System (EPICS). Since then, the accelerator and all other laboratory controls have been successfully converted. In addition to implementing Jefferson Lab's controls using EPICS, new data visualization tools have… more
Date: October 1, 1999
Creator: White, K. S.; Bickley, M. & Watson, W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

The strangeness content of the proton from parity violating electron scattering at JLab

Description: The authors have measured the parity violating asymmetry in the cross section for elastic scattering of longitudinally polarized electrons from protons at 3.36 GeV incident energy and 0.48 GeV{sup 2}/c{sup 2} momentum transfer at JLab. From their 1998 run, this asymmetry is {minus}14.5{+-}2.2 ppm, consistent with the Standard Model with no contribution from strange quarks. They extract the combination of strange form factors G{sup 3}{sub E} + 0.39G{sup 3}{sub M}=0.023{+-}0.034(stat){+-}0.022(sy… more
Date: August 1, 1999
Creator: Michaels, R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Experimental verification of quark-hadron duality

Description: A newly-obtained sample of inclusive electron-nucleon scattering data has been analyzed for precision tests of quark-hadron duality. The data are in the nucleon resonance region, and span the range 0.3 &lt; Q{sup 2} &lt; 5.0 (GeV/c){sup 2}. Duality is observed both in limited and extended regions around the prominent resonance enhancements. Higher twist contributions to the F{sub 2} structure function are found to be minimal on average, even in the low Q{sub 2} regime of approximately 0.5 (GeV/… more
Date: April 1, 1999
Creator: Niculescu, I.; Armstrong, C.S. & Arrington, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

EPICS tools enhancements and transportability

Description: The Jefferson Laboratory electron accelerator is controlled by the Experimental Physics and Industrial Control System (EPICS), which was initially developed by the Los Alamos and Argonne National Laboratories, and which has since become an extensive collaboration among scientific institutions worldwide. In keeping with the spirit of cooperation and exchange fostered by the EPICS community, the Controls Software group at Jefferson Laboratory aims to produce portable software tools useful not onl… more
Date: March 1, 1999
Creator: Bickley, M.; Chen, J. & Larrieu, C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

First results on energy recovery in the Jefferson Lab IR FEL

Description: A recirculating, energy-recovery linac is used as a driver accelerator for Jefferson Lab's high average power FEL. CW beam of 5 mA design current is transported from the superconducting RF (SRF) linac to the wiggler for lasing, and then recirculated back to the linac for deceleration and energy recovery. About 75% of the beam power is extracted before the beam is transported to the beam dump. Energy recovery reduces power consumption, RF equipment capital costs, and beam dump shielding requirem… more
Date: August 1, 1999
Creator: Benson, S.; Biallas, G. & Bohn, C.L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Beam breakup simulations for the Jefferson Lab FEL upgrade

Description: As the Jefferson Lab Free Electron Laser steadily approaches its goal of producing 1 kW of IR radiation at 5 mA of beam current at 42 MeV, plans are being considered for possible upgrade scenarios, which will extend the IR power output and allow generation of UV radiation. The upgrade scenario presently considered will bring the beam current to 10 mA and increase the energy to values close to 200 MeV. These parameters will most likely be realized in a machine configuration with a single recircu… more
Date: April 1, 1999
Creator: Campisi, I.E.; Douglas, D.; Merminga, L. & Yunn, B.C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Dealing with a large installation of SRF cavities: Characterizing limitations and exploiting operational flexibility

Description: Linacs using a large number of SRF cavities can have an awkwardly large number of degrees of freedom for operational setup. The cost and robustness of operation as a function of operating gradient is a particular characteristic of each cavity system and the intended beamloading. A systematic characterization of these limitations has been developed which yields a valuable guide for development resource allocation. In addition, a software tool has been developed which enables the CEBAF machine op… more
Date: November 1, 1999
Creator: Reece, C.; Madre, B.; Doolittle, L. & Delayen, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Using Servers to Enhance Control System Capability

Description: Many traditional control systems include a distributed collection of front end machines to control hardware. Back end tools are used to view, modify and record the signals generated by these front end machines. Software servers, which are a middleware layer between the front and back ends, can improve a control system in several ways. Servers can enable on-line processing of raw data, and consolidation of functionality. In many cases, data retrieved from the front end must be processed in order… more
Date: March 1, 1999
Creator: Bickley, M.; Bowling, B. A.; Bryan, D. A.; Zeijts, J. van; White, K. S. & Witherspoon, S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

The fifth response function and spin-orbit final-state interaction in the framework of Glauber theory for (e, e{prime}p) reactions

Description: The author discuss the effects of the spin-orbit final state interaction on the fifth response function. Currently, there are many (e,e{prime}p) experiments at GeV energies being performed or planned at Jefferson Lab. The major theoretical problem in the description of these reactions is the fact that at transferred energies of 1 GeV or more, a consistent calculation for the initial bound state and the--in general rather complicated--hadronic final state from a microscopic Lagrangian is not fea… more
Date: November 1, 1999
Creator: Jeschonnek, Sabine & Donnelly, T.W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
Back to Top of Screen