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Search Results: 1 - 10 of 144428 matches for " F. Benmokhtar "
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Measurement of the 3He(e,e'p)pn reaction at high missing energies and momenta
F. Benmokhtar
Physics , 2004, DOI: 10.1103/PhysRevLett.94.082305
Abstract: Results of the Jefferson Lab Hall A quasielastic 3He(e,e'p)pn measurements are presented. These measurements were performed at fixed transferred momentum and energy, q = 1502 MeV/c and omega = 840 MeV, respectively, for missing momenta p_m up to 1 GeV/c and missing energies in the continuum region, up to pion threshold; this kinematic coverage is much more extensive than that of any previous experiment. The cross section data are presented along with the effective momentum density distribution and compared to theoretical models.
Preliminary Results from Integrating Compton Photon Polarimetry in Hall A of Jefferson Lab
D. Parno,M. Friend,F. Benmokhtar,G. Franklin,R. Michaels,S. Nanda,B. Quinn,P. Souder
Physics , 2011, DOI: 10.1088/1742-6596/312/5/052018
Abstract: A wide range of nucleon and nuclear structure experiments in Jefferson Lab's Hall A require precise, continuous measurements of the polarization of the electron beam. In our Compton polarimeter, electrons are scattered off photons in a Fabry-Perot cavity; by measuring an asymmetry in the integrated signal of the scattered photons detected in a GSO crystal, we can make non-invasive, continuous measurements of the beam polarization. Our goal is to achieve 1% statistical error within two hours of running. We discuss the design and commissioning of an upgrade to this apparatus, and report preliminary results for experiments conducted at beam energies from 3.5 to 5.9 GeV and photon rates from 5 to 100 kHz.
Comparison of Modeled and Measured Performance of a GSO Crystal as Gamma Detector
D. S. Parno,M. Friend,V. Mamyan,F. Benmokhtar,A. Camsonne,G. B. Franklin,K. Paschke,B. Quinn
Physics , 2012, DOI: 10.1016/j.nima.2013.05.154
Abstract: We have modeled, tested, and installed a large, cerium-activated Gd2SiO5 crystal scintillator for use as a detector of gamma rays. We present the measured detector response to two types of incident photons: nearly monochromatic photons up to 40 MeV, and photons from a continuous Compton backscattering spectrum up to 200 MeV. Our GEANT4 simulations, developed to determine the analyzing power of the Compton polarimeter in Hall A of Jefferson Lab, reproduce the measured spectra well.
Electrocatalytic Oxidation of Methanol on Glassy Carbon Electrode Modified by Metal Ions (Copper and Nickel) Dispersed into Polyaniline Film  [PDF]
Asmea Khouchaf, Driss Takky, Mohammed El Mahi Chbihi, Said Benmokhtar
Journal of Materials Science and Chemical Engineering (MSCE) , 2016, DOI: 10.4236/msce.2016.42011
Abstract: Polyaniline film was prepared by using the repeated potential cycling technique in an acidic solution at the surface of glassy carbon electrode. Then transition metal ions of Ni and Cu were incorporated to the polymer by immersion of the modified electrode. A comparative study of the electrocatalytic oxidation of methanol is made in NaOH, on Ni and Cu on polyaniline film covered glassy carbon electrode (Ni-PANI-GC, Cu-PANI-GC) at 25. Catalytic activity for the oxidation of methanol was studied by using cyclic voltammetry.
Enthalpy of Dissolution and Dehydration of Two Moroccan Clays  [PDF]
Jabrane Maissara, Halima Karym, Mohammed El Mahi Chbihi, Mohammed Moutaabbid, Mohamed Abatal, Said Benmokhtar
World Journal of Engineering and Technology (WJET) , 2018, DOI: 10.4236/wjet.2018.61007
Abstract: This work aims to characterize and determine the dehydroxylation enthalpy variations of two natural Moroccan clays from the Nador region (denoted K1) and the Settat region (denoted by K2). The variations of dissolution enthalpies were determined by dissolving clays in hydrofluoric acid. They have a minimum value for dehydroxylation of clays made between 600°C and 700°C. The analysis of the two clays shows that they consist of kaolinite in significant proportion. The optimum calcination parameters, for which dehydroxylation is total, are 700°C with a heating time of 6 H. The conversion of the kaolinite to metakaolinite was confirmed by IR analyses of the starting and thermally treated kaolin samples. The result confirms previous observations about obtaining metakaolinite with optimum reactivity when hydrated with calcium hydroxide as chemical activator.
Upgraded photon calorimeter with integrating readout for Hall A Compton Polarimeter at Jefferson Lab
M. Friend,D. Parno,F. Benmokhtar,A. Camsonne,M. Dalton,G. B. Franklin,V. Mamyan,R. Michaels,S. Nanda,V. Nelyubin,K. Paschke,B. Quinn,A. Rakhman,P. Souder,A. Tobias
Physics , 2011, DOI: 10.1016/j.nima.2012.02.041
Abstract: The photon arm of the Compton polarimeter in Hall A of Jefferson Lab has been upgraded to allow for electron beam polarization measurements with better than 1% accuracy. The data acquisition system (DAQ) now includes an integrating mode, which eliminates several systematic uncertainties inherent in the original counting-DAQ setup. The photon calorimeter has been replaced with a Ce-doped GSO crystal, which has a bright output and fast response, and works well for measurements using the new integrating method at electron beam energies from 1 to 6 GeV.
Test of the CLAS12 RICH large scale prototype in the direct proximity focusing configuration
N. Baltzell,L. Barion,F. Benmokhtar,W. Brooks,E. Cisbani,M. Contalbrigo,A. El Alaoui,K. Hafidi,M. Hoek,V. Kubarovsky,L. Lagamba,V. Lucherini,R. Malaguti,M. Mirazita,R. A. Montgomery,A. Movsisyan,P. Musico,A. Orlandi,D. Orecchini,L. L. Pappalardo,R. Perrino,J. Phillips,S. Pisano,P. Rossi,S. Squerzanti,S. Tomassini,M. Turisini,A. Viticchie
Physics , 2015,
Abstract: A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c up to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Laboratory. The adopted solution foresees a novel hybrid optics design based on aerogel radiator, composite mirrors and high-packed and high-segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). We report here the results of the tests of a large scale prototype of the RICH detector performed with the hadron beam of the CERN T9 experimental hall for the direct detection configuration. The tests demonstrated that the proposed design provides the required pion-to-kaon rejection factor of 1:500 in the whole momentum range.
Search for Sub-threshold Photoproduction of J/Psi Mesons
P. Bosted,J. Dunne,C. A. Lee,P. Junnarkar,J. Arrington,R. Asaturyan,F. Benmokhtar,M. E. Christy,E. Chudakov,B. Clasie,S. H. Connell,M. M. Dalton,A. Daniel,D. Day,D. Dutta,R. Ent,N. Fomin,D. Gaskell,T. Horn,N. Kalantarians,C. E. Keppel,D. G. Meekins,H. Mkrtchyan,T. Navasardyan,J. Roche,V. M. Rodriguez,D. Kiselev,J. Seely,K. Slifer,M. Strikman,S. Tajima,G. Testa,Roman Trojer,F. R. Wesselmann,S. A. Wood,X. C. Zheng
Physics , 2008, DOI: 10.1103/PhysRevC.79.015209
Abstract: A search was made for sub-threshold $J/\psi$ production from a carbon target using a mixed real and quasi-real Bremsstrahlung photon beam with an endpoint energy of 5.76 GeV. No events were observed, which is consistent with predictions assuming quasi-free production. The results place limits on exotic mechanisms that strongly enhance quasi-free production.
Deuteron Electro-Disintegration at Very High Missing Momenta
W. U. Boeglin,M. K. Jones,K. Aniol,A. Asaturyan,H. Baghdasaryan,F. Benmokhtar,H. Bitao,S. Danagoulian,D. Day,D. Gaskell,D. Higinbotham,G. Huber,S. Jeschonnek,N. Kalantarians,P. E. Markowitz,A. Mkrtchyan,H. Mkrtchyan,E. Piasetzky,A. Puckett,B. A. Raue,J. Reinhold,G. Ron,M. Sargsian,R. Shneor,G. Smith,R. Subedi,V. Tadevosyan,J. W. Van Orden,F. R. Wesselmann
Physics , 2014,
Abstract: We propose to measure the D(e,e'p) cross section at $Q^2 = 4.25$ (GeV/c)$^2$ and $x_{bj} = 1.35$ for missing momenta ranging from $p_m = 0.5$ GeV/c to $p_m = 1.0$ GeV/c expanding the range of missing momenta explored in the Hall A experiment (E01-020). At these energy and momentum transfers, calculations based on the eikonal approximation have been shown to be valid and recent experiments indicated that final state interactions are relatively small and possibly independent of missing momenta. This experiment will provide for the first time data in this kinematic regime which are of fundamental importance to the study of short range correlations and high density fluctuations in nuclei. The proposed experiment could serve as a commissioning experiment of the new SHMS together with the HMS in Hall C. A total beam time of 21 days is requested.
Studying the Proton "Radius" Puzzle with μp Elastic Scattering
R. Gilman,E. J. Downie,G. Ron,A. Afanasev,J. Arrington,O. Ates,F. Benmokhtar,J. Bernauer,E. Brash,W. J. Briscoe,K. Deiters,J. Diefenbach,C. Djalali,B. Dongwi,L. El Fassi,S. Gilad,K. Gnanvo,R. Gothe,D. Higinbotham,R. Holt,Y. Ilieva,H. Jiang,M. Kohl,G. Kumbartzki,J. Lichtenstadt,A. Liyanage,N. Liyanage,M. Meziane,Z. -E. Meziani,D. G. Middleton,P. Monaghan,K. E. Myers,C. Perdrisat,E. Piasetzsky,V. Punjabi,R. Ransome,D. Reggiani,P. Reimer,A. Richter,A. Sarty,E. Schulte,Y. Shamai,N. Sparveris,S. Strauch,V. Sulkosky,A. S. Tadepalli,M. Taragin,L. Weinstein
Physics , 2013,
Abstract: The Proton Radius Puzzle is the inconsistency between the proton radius determined from muonic hydrogen and the proton radius determined from atomic hydrogen level transitions and ep elastic scattering. No generally accepted resolution to the Puzzle has been found. Possible solutions generally fall into one of three categories: the two radii are different due to novel beyond-standard-model physics, the two radii are different due to novel aspects of nucleon structure, and the two radii are the same, but there are underestimated uncertainties or other issues in the ep experiments. The MUon proton Scattering Experiment (MUSE) at the Paul Scherrer Institut is a simultaneous measurement of \mu^+ p and e^+ p elastic scattering, as well as \mu^- p and e^- p elastic scattering, which will allow a determination of the consistency of the \mu p and the ep interactions. The differences between + and - charge scattering are sensitive to two-photon exchange effects, higher-order corrections to the scattering process. The slopes of the cross sections as Q^2 -> 0 determine the proton "radius". We plan to measure relative cross sections at a typical level of a few tenths of a percent, which should allow the proton radius to be determined at the level of ~0.01 fm, similar to previous ep measurements. The measurements will test several possible explanations of the proton radius puzzle, including some models of beyond-standard-model physics, some models of novel hadronic physics, and some issues in the radius extraction from scattering data.
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