Download or read book Proton Form Factor Ratio mu pGEP GMP from Double Spin Asymmetry written by and published by . This book was released on 2013 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: The form factors are fundamental properties of the nucleon representing the effect of its structure on its response to electromagnetic probes such as electrons. They are functions of the four-momentum transfer squared Q2 between the electron and the proton. This thesis reports the results of a new measurement of the ratio of the electric and magnetic form factors of the proton up to Q2 = 5.66 (GeV/c)2 using the double spin asymmetry with a polarized beam and target. Experiment E07-003 (SANE, Spin Asymmetries of the Nucleon Experiment) was carried out in Hall C at Jefferson Lab in 2009 to study the proton spin structure functions with a dynamically polarized ammonia target and longitudinally polarized electron beam. By detecting elastically scattered protons in the High-Momentum Spectrometer (HMS) in coincidence with the electrons in the Big Electron Telescope Array (BETA), elastic measurements were carried out in parallel. The elastic double spin asymmetry allows one to extract the proton electric to magnetic form factor ratio GpE/GpM at high-momentum transfer, Q2= 5.66 (GeV/c)2. In addition to the coincidence data, inclusively scattered electrons from the polarized ammonia target were detected by HMS, which allows to measure the beam-target asymmetry in the elastic region with the target spin nearly perpendicular to the momentum transfer, and to extract GpE/GpM at low Q2= 2.06 (GeV/c)2. This alternative measurement of GpE/GpM has verified and confirmed the dramatic discrepancy at high Q2 between the Rosenbluth and the recoil-polarization-transfer iv method with a different measurement technique and systematic uncertainties uncorrelated to those of the recoil-polarization measurements. The measurement of the form factor ratio at Q2 = 2.06 (GeV/c)2 has been determined as [mu]{sub p}GpE/GpM = 0.605±0.178stat±0.033sys which is in agreement with an earlier measurement with the polarized target technique at similar kinematics. The measurement of the form factor ratio at Q2 = 5.66 (GeV/c)2 has been determined as [mu]pGpE/GpM = 0.672 ± 0.362stat which represents the highest Q2 reach with the double spin asymmetry to date.
Download or read book Proton Form Factor Ratio from Double Spin Asymmetry written by Habarakada Pushpakumari author (Liyanage, Anusha) and published by . This book was released on 2013 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of the Ratio GEP GMP to Large Q2 written by Vina Punjabi and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In two experiments at Jefferson Lab the ratio of the electromagnetic form factors of the proton, GEp=GMp, was obtained in the four-momentum transfer squared range of 0.5 to 5.6 GeV2 with a polarization transfer technique, by measuring Pt and Pl, the transverse and longitudinal recoil proton polarization in ep --> e'p reaction. In one-photon approximation GEp=GMp is proportional to Pt=Pl; the great strength of this method is the tight control of systematics it affords. The ratio mu GEp=GMp was found to decrease linearly with Q2, down to 0.29 at Q2=5.6 GeV2; revealing a definite difference between the spatial distributions of charge and magnetization at short distances. The combined results of the two JLab experiments were surprising as they appeared to contradict the consensus based on Rosenbluth separation results for (GEp)2 and (GMp)2: the ratio mu pGEp=GMp obtained with the Rosenbluth method is {approx}1 up to 5 GeV2. This unbridgeable difference between cross section and polarization experiments has been reinforced with two recent JLab Rosenbluth experiments; it appears increasingly difficult to explain it away by methodological or systematic errors. We are currently preparing a third experiment at JLab, this time in Hall C, to extend the Q2-range to 9 GeV2.
Download or read book Final Analysis of Proton Form Factor Ratio Data at Q2 written by and published by . This book was released on with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recently published measurements of the proton electromagnetic form factor ratio R = [mu]p GEp/GMp at momentum transfers Q2 up to 8.5 GeV2 in Jefferson Lab Hall C deviate from the linear trend of previous measurements in Jefferson Lab Hall A, favoring a slower rate of decrease of R with Q2. While statistically compatible in the region of overlap with Hall A, the Hall C data hint at a systematic difference between the two experiments. This possibility was investigated in a reanalysis of the Hall A data. We find that the original analysis underestimated the background in the selection of elastic events. The application of an additional cut to further suppress the background increases the results for R, improving the consistency between Halls A and C.
Download or read book Proton Form Factors written by Olivier Gayou and published by . This book was released on 2002 with total page 215 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dans cette thèse sont présentés les résultats de l'expérience E99-007, qui a mesuré le rapport des facteurs de forme électrique et magnétique du proton, jusqu'au quadri-moment de transfert Q2 = 5.6 GeV2, par polarisation de recul. Les données ont été prises en 2000 au Thomas Jefferson National Accelerator Facility en Virginie (USA). Un faisceau d'électrons polarisés de 4.6 Gev a été diffusé sur une cible d'hydrogène liquide. La polarisation du proton de recul était mesurée dans le Polarimètre du Plan Focal, situé à l'extrémité de l'un des deux Spectromètres à Haute Résolution du Hall A. Le rapport des composantes transverse et longitudinale de la polarisation du proton de recul est proportionnel au rapport des facteurs de forme. Les événements élastiques étaient identifiés en détectant l'électron diffusé dans un calorimètre en verre au plomb de grande acceptance. Le résultat principal de cette expérience est la décroissance linéaire du rapport des facteurs de forme quand Q2 augmente, correspondant à des distributions spatiales différentes de la charge électrique et de la magnétisation. De nombreux calculs théoriques montrent que des effets relativistes, comme le mélange des états de spin dûs à des transformations de Lorentz, doivent être pris en compte pour expliquer les résultats observés dans cette région cinématique critique.
Download or read book The Proton Elastic Form Factor Ratio mu pGpe Gpm at Low Q2 written by Guy Ron and published by . This book was released on 2008 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Proton Form Factor Ratio Measurements at Jefferson Lab written by and published by . This book was released on 2014 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ratio of the proton form factors, G{sub Ep}/G{sub Mp}, has been measured from Q2 of 0.5 GeV2 to 8.5 GeV2, at the Jefferson Laboratory, using the polarization transfer method. This ratio is extracted directly from the measured ratio of the transverse and longitudinal polarization components of the recoiling proton in elastic electron-proton scattering. The discovery that the proton form factor ratio measured in these experiments decreases approximately linearly with four-momentum transfer, Q2, for values above ~1 GeV2, is one of the most significant results to come out of JLab. These results have had a large impact on progress in hadronic physics; and have required a significant rethinking of nucleon structure. The increasingly common use of the double-polarization technique to measure the nucleon form factors, in the last 15 years, has resulted in a dramatic improvement of the quality of all four nucleon electromagnetic form factors, G{sub Ep}, G{sub Mp}, G{sub En} and G{sub Mn}. There is an approved experiment at JLab, GEP(V), to continue the ratio measurements to 12 GeV2. A dedicated experimental setup, the Super Bigbite Spectrometer (SBS), will be built for this purpose. It will be equipped with a focal plane polarimeter to measure the polarization of the recoil protons. The scattered electrons will be detected in an electromagnetic calorimeter. In this presentation, I will review the status of the proton elastic electromagnetic form factors and discuss a number of theoretical approaches to describe nucleon form factors.
Download or read book Measurements of the Proton Electromagnetic Form Factor Ratio From Elastic E P E P Scattering at Momentum Transfer Q2 written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Among the fundamental observables of nucleon structure, electromagnetic form factors are a crucial benchmark for modern calculations describing the strong interaction dynamics of the nucleon's quark constituents. Electromagnetic probes are traditionally preferered to the hadronic beams. The electromagnetic interaction is a powerful tool for investigating the nucleon structure since it is well understood and it reveals observables that can be directly interpreted in terms of the current carried by the quarks. Elastic scattering leads to the form factors that describe the spatial charge and current distributions inside the nucleon. The reaction mechanism is assumed to be one photon exchange, the electromagnetic interaction is exactly calculable in QED, and one can safely extract the information on the hadronic vertex. The most important feature of early measurements of proton form factor ratio GEp/GMp with recoil polarization technique at Q2 up to 5.6 (GeV/c)2 is the sharp decline of the ratio with Q2 increases, indicating that GEp falls much faster than GMp. This contradicts to data obtained by Rosenbluth separation method. An intriguing question was whether GEp will continue to decrease or become constant when Q2 increases. New set of measurements of proton form factor ratio GEp/GMp at Q2 = 2.5, 5.2, 6.7 and 8.5 (GeV/c)2 have been conducted at JLab Hall C using ~85% longitudinally polarized electron elastic scattering from unpolarized hydrogen target. Recoil protons were detected in the HMS magnetic spectrometer with the standard detector package, combined with newly installed trigger scintillators and Focal Plane Polarimeter. The BigCal electromagnetic calorimeter (1744 channel) have been used for electron detection. Data obtained in this experiment show that GEp/GMp ratio continued to drop with Q2 and may cross 'zero' at Q2> 10-15 (GeV/c)2. Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton form factor ratio GEp/GMp obtained from cross section and polarization measurements. It was assumed that the two photon exchange contribution might be responsible for difference of GEp/GMp ratio obtained by Rosenbluth separation method and recoil polarization technique. The kinematical dependence of polarization transfer observables in elastic electron-proton scattering at Q2 = 2.5 (GeV/c)2 have been used in search of effects of 2[gamma] contribution. For a wide range of values of the virtual photon polarization [Sigma] ([Sigma] = 0.15, 0.63, and 0.77), the proton form factor ratio and longitudinal polarization transfer component were measured with statistical uncertainties of ±0.01 and ±0.005, respectively. Our data provide significant constraints on models of nucleon structure.
Download or read book High Precision Measurement of the Proton Elastic Form Factor Ratio at Low Q2 written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A high precision measurement of the proton elastic form factor ratio μpGEp/GMp in the range Q2 = 0.3-0.7 GeV2/c2 was performed using recoil polarimetry in Jefferson Lab Hall A. In this low Q2 range, previous data from LEDEX [5] along with many fits and calculations [2, 3, 4] indicate substantial deviations of the ratio from unity. In this new measurement, with 80% polarized electron beam for 24 days, we are able to achieve
Download or read book Proton Form Factor Ratio Measurement with BLAST written by Adrian Tiberiu Sindile and published by . This book was released on 2006 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Proton Elastic Form Factor Ratio Mu p G p E G p M at Low Momentum Transfer written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High precision measurements of the proton elastic form factor ratio have been made at four-momentum transfers, Q^2, between 0.2 and 0.5 GeV^2. The new data, while consistent with previous results, clearly show a ratio less than unity and significant differences from the central values of several recent phenomenological fits. By combining the new form-factor ratio data with an existing cross-section measurement, one finds that in this Q^2 range the deviation from unity is primarily due to GEp being smaller than the dipole parameterization.
Download or read book Proton Elastic Form Factor Ratio written by Charles Perdrisat and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The ratio of the electric and magnetic proton form factors, G{sub Ep}/G{sub Mp}, has been obtained in two Hall A experiments, from measurements of the longitudinal and transverse polarization of the recoil proton, P{sub l} and P{sub t}, respectively, in the elastic scattering of polarized electrons, {rvec e}p {yields} e{rvec p}. Together these experiments cover the Q{sup 2}-range 0.5 to 5.6 GeV{sup 2}. A new experiment is currently being prepared, to extend the Q{sup 2}-range to 9 GeV{sup 2} in Hall C.
Download or read book Proton G E G M from Beam target Asymmetry written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The ratio of the proton's electric to magnetic form factor, G{sub E}/G{sub M}, can be extracted in elastic electron-proton scattering by measuring either cross sections, beam-target asymmetry or recoil polarization. Separate determinations of G{sub E}/G{sub M} by cross sections and recoil polarization observables disagree for Q2> 1 (GeV/c)2. Measurement by a third technique might uncover an unknown systematic error in either of the previous measurements. The beam-target asymmetry has been measured for elastic electron-proton scattering at Q2 = 1.51 (GeV/c)2 for target spin orientation aligned perpendicular to the beam momentum direction. This is the largest Q2 at which G{sub E}/G{sub M} has been determined by a beam-target asymmetry experiment. The result, [mu]G{sub E}/G{sub M} = 0.884 +/- 0.027 +/- 0.029, is compared to previous world data.
Download or read book Measurement of the Proton Form Factors Ratio GE GM to Q2 written by and published by . This book was released on 2002 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, we present the results of the experiment E99-007, which measured the ratio of the electric to magnetic form factors of the proton to the four momentum transfer square Q2 = 5.6 GeV2, by recoil polarimetry. Data were taken in 2000 at the Thomas Jefferson National Accelerator Facility in Virginia, USA. A 4.6 GeV polarized electron beam was scattered off a cryogenic hydrogen target. The polarization of the recoil proton was measured in the Focal Plane Polarimeter, located after one of the two High Resolution Spectrometers in the hall. The ratio of the transverse to longitudinal components of the recoil proton polarization is proportional to the ratio of the form factors. Elastic events were selected by detecting the scattered electron in a large acceptance lead-glass calorimeter. The main result of this experiment is the linear decrease of the form factor ratio with increasing Q2, corresponding to different spatial distributions of the electric charge and the magnetization. Numerous theoretical calculations show that relativistic effects, such as mixing of spin states due to Lorentz boosts, are important to account for the observed data in this critical intermediate kinematic region.
Download or read book Recoil Polarization Measurements of the Proton Electromagnetic Form Factor Ratio at High Momentum Transfer written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Electromagnetic form factors are fundamental properties of the nucleon that describe the effect of its internal quark structure on the cross section and spin observables in elastic lepton-nucleon scattering. Double-polarization experiments have become the preferred technique to measure the proton and neutron electric form factors at high momentum transfers. The recently completed GEp-III experiment at the Thomas Jefferson National Accelerator Facility used the recoil polarization method to extend the knowledge of the proton electromagnetic form factor ratio GpE/GpM to Q2 = 8.5 GeV2. In this paper we present the preliminary results of the experiment.
Download or read book Integration of Pharmaceutical Discovery and Development written by Ronald T. Borchardt and published by Springer Science & Business Media. This book was released on 2006-01-19 with total page 627 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the late 1980s, it became painfully evident to the pharmaceutical industry that the old paradigm of drug discovery, which involved highly segmented drug - sign and development activities, would not produce an acceptable success rate in the future. Therefore, in the early 1990s a paradigm shift occurred in which drug design and development activities became more highly integrated. This new str- egy required medicinal chemists to design drug candidates with structural f- tures that optimized pharmacological (e. g. , high affinity and specificity for the target receptor), pharmaceutical (e. g. , solubility and chemical stability), bioph- maceutical (e. g. , cell membrane permeability), and metabolic/pharmacokinetic (e. g. , metabolic stability, clearance, and protein binding) properties. Successful implementation of this strategy requires a multidisciplinary team effort, incl- ing scientists from drug design (e. g. , medicinal chemists, cell biologists, en- mologists, pharmacologists) and drug development (e. g. , analytical chemists, pharmaceutical scientists, physiologists, and molecular biologists representing the disciplines of pharmaceutics, biopharmaceutics, and pharmacokinetics/drug metabolism). With this new, highly integrated approach to drug design now widely utilized by the pharmaceutical industry, the editors of this book have provided the sci- tific community with case histories to illustrate the nature of the interdisciplinary interactions necessary to successfully implement this new approach to drug d- covery. In the first chapter, Ralph Hirschmann provides a historical perspective of why this paradigm shift in drug discovery has occurred.
Download or read book Human Melioidosis written by S. D. Puthucheary and published by NUS Press. This book was released on 2002 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: Infectious diseases account for a third of all deaths in the developing world, yet the pathogens which affect specifically these predominantly poor people attract little attention. Melioidosis is a case in point. This book describes the epidemiology, pathology, pathophysiology, clinical features, diagnosis, management and prevention of an important infection that is little known outside Southeast Asia and Australia.
