Download or read book The Q sup 2 Dependence of the Neutron Spin Structure Function G sub 2 sup N at Low Q sup 2 written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurements of the Q sup 2 Dependence of the Proton and Neutron Spin Structure Functions G sub 1 sup P and G sub 1 sup N written by and published by . This book was released on 2000 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurements of the Q sup 2 Dependence of the Proton and Neutron SpinStructure Functions G sub 1 sup P and G sub 1 sup N written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The structure functions g[sub 1][sup p] and g[sub 1][sup n] have been measured over the range 0.014
Download or read book Precision Measurement of the Neutron Spin Dependent Structure Functions written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In experiment E154 at the Stanford Linear Accelerator Center the spin dependent structure function g[sub 1][sup n] (x, Q[sup 2]) of the neutron was measured by scattering longitudinally polarized 48.3 GeV electrons off a longitudinally polarized[sup 3]He target. The high beam energy allowed the author to extend the kinematic coverage compared to the previous SLAC experiments to 0.014[le] x[le] 0.7 with an average Q[sup 2] of 5 GeV[sup 2]. The author reports the integral of the spin dependent structure function in the measured range to be[integral][sub 0.014][sup 0.7] dx g[sub 1][sup n](x, 5 GeV[sup 2])=[minus]0.036[+-] 0.004(stat.)[+-] 0.005(syst.). The author observes relatively large values of g[sub 1][sup n] at low x that call into question the reliability of data extrapolation to x[r-arrow] 0. Such divergent behavior disagrees with predictions of the conventional Regge theory, but is qualitatively explained by perturbative QCD. The author performs a Next-to-Leading Order perturbative QCD analysis of the world data on the nucleon spin dependent structure functions g[sub 1][sup p] and g[sub 1][sup n] paying careful attention to the experimental and theoretical uncertainties. Using the parameterizations of the helicity-dependent parton distributions obtained in the analysis, the author evolves the data to Q[sup 2]= 5 GeV[sup 2], determines the first moments of the polarized structure functions of the proton and neutron, and finds agreement with the Bjorken sum rule.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book A Determination of the Neutron Spin Structure Function written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors report the results of the experiment E142 which measured the spin dependent structure function of the neutron, g[sub 1][sup n](x, Q[sup 2]). The experiment was carried out at the Stanford Linear Accelerator Center by measuring an asymmetry in the deep inelastic scattering of polarized electrons from a polarized[sup 3]He target, at electron energies from 19 to 26 GeV. The structure function was determined over the kinematic range 0.03
Download or read book New Results on Nucleon Spin Structure written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent precision spin structure data from Jefferson Lab have significantly advanced our knowledge of nucleon structure in the valence quark (high-x) region and improved our understanding of higher-twist effects, spin sum rules and quark-hadron duality. First, results of a precision measurement of the neutron spin asymmetry, A[sub 1][sup n], in the high-x region are discussed. The new data shows clearly, for the first time, that A[sub 1][sup n] becomes positive at high x. They provide crucial input for the global fits to world data to extract polarized parton distribution functions. Preliminary results on A[sub 1][sup p] and A[sub 1][sup d] in the high-x region have also become available. The up and down quark spin distributions in the nucleon were extracted. The results for [Delta]d/d disagree with the leading-order pQCD prediction assuming hadron helicity conservation. Then, results of a precision measurement of the g[sub 2][sup n] structure function to study higher-twist effects are presented. The data show a clear deviation from the lead-twist contribution, indicating a significant higher-twist (twist-3 or higher) effect. The second moment of the spin structure functions and the twist-3 matrix element d[sub 2][sup n] results were extracted at a high Q[sup 2] of 5 GeV[sup 2] from the measured A[sub 2][sup n] in the high-x region in combination with existing world data and compared with a Lattice QCD calculation. Results for d[sub 2][sup n] at low-to-intermediate Q[sup 2] from 0.1 to 0.9 GeV[sup 2] were also extracted from the JLab data. In the same Q[sup 2] range, the Q[sup 2] dependence of the moments of the nucleon spin structure functions was measured, providing a unique bridge linking the quark-gluon picture of the nucleon and the coherent hadronic picture. Sum rules and generalized forward spin polarizabilities were extracted and compared with Chiral Perturbation Theory calculations and phenomenological models. Finally, preliminary results on the resonance spin structure functions in the Q[sup 2] range from 1 to 4 GeV[sup 2] were presented, which, in combination with DIS data, will enable a detailed study of the quark-hadron duality in spin structure functions.
Download or read book Measurement of the Neutron Spin Structure Function and Its Implications for QCD Sum Rules written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors have determined the neutron spin structure function g[sub 1][sup n] over the range 0.03 [le] x [le] 0.6 at an average Q[sup 2] of 2(GeV/c)[sup 2] by measuring the asymmetry in deep inelastic scattering of polarized electrons from a polarized [sup 3]He target. The experiment was performed at SLAC and used energies between 19 and 26 GeV. The neutron asymmetry turned out to be small and negative, and the integral of the neutron spin structure function is [integral][sub 0][sup 1]g[sub 1][sup n](x)dx = -0.024 [+-] 0.006(stat.) [+-] 0.008(syst.). Combined with the current available worldwide proton data, this result confirmed the Bjorken sum rule at 10% level, once high-order perturbative QCD corrections are taken into account. The Ellis-Jaffe sum rule for the neutron predicts [integral][sub 0][sup 1] g[sub 1][sup n](x)dx = -0.010 [+-] 0.012, roughly consistent with their result.
Download or read book Measurement of the Spin Structure Function G 2 X Q 2 for the Neutron written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The asymmetry A[sub 2](x, Q[sup 2]) and structure function g[sub 2](x, Q[sup 2]) were measured for the neutron using deep inelastic electron scattering. The measurement was made using the 50 GeV longitudinally polarized electron beam at the Stanford Linear Accelerator Center. The target consisted of gaseous [sup 3]He which was polarized through spin exchange with optically pumped rubidium vapor. Data were taken simultaneously with two magnetic spectrometers fixed at 2.75[sup o] and 5.5[sup o] scattering angles, covering a combined kinematic range of 0.014 [le] x [le] 0.7 and 1.0 [le] Q[sup 2] [le] 17.0 (GeV/c)[sup 2]. The A[sub 2] data were found to be well bounded by the positivity constraint A[sub 2] [le] [radical]R, and most of the data were consistent with zero. The g[sub 2] structure function was found to be consistent with zero and with the twist-2 Wandzura-Wilczek prediction. In addition, the Operator Product Expansion twist-3 matrix element d[sub 2] was calculated from the data and found to be consistent with all theoretical predictions.
Download or read book Recent SLAC Measurements of the Spin Dependent Structure Functions for the Proton and Neutron written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present results from SLAC experiments E142 and E143 for the spin dependent structure functions of the proton g[sub 1][sup p](x, Q[sup 2]) and neutron g[sub 1][sup n](x, Q[sup 2]) measured in deep inelastic scattering of polarized electrons from a polarized target. Experiment E142 measures[integral][sub 0][sup 1] g[sub 1][sup n](x)dx=[minus]0.022[+-] 0.011 atQ[sup 2]= 2 (GeV/c)[sup 2] using a polarized[sup 3]He target. Experiment E143 measures[integral][sub 0][sup 1] g[sub 1][sup p](x)dx= 0.129[+-] 0.011 atQ[sup 2]= 3 (GeV/c)[sup 2] using a polarized NH[sub 3] target. These results are combined at Q[sup 2]= 3 (GeV/c)[sup 2] to yield[integral][sub 0][sup 1][g[sub 1][sup p](x)[minus] g[sub 1][sup n](x)]dx= 0.151[+-] 0.015. The Bjorken sum rule predicts 0.171[+-] 0.008.
Download or read book Neutron Spin Structure in the Resonance Region and Quark Hadron Duality written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Quark-Hadron duality has been experimentally demonstrated for the spin independent structure function F2. Duality is observed when, at the same value of scaling variable x{sub bj}, the smooth scaling curve at high momentum transfer becomes an average over the resonances at lower momentum transfer. Jefferson Lab experiment 01-012 used the polarized 3He target in Hall A for an extraction of the neutron spin structure function g1(superscript n) and the virtual photon asymmetry A1(superscript n) in the resonance region over a Q2 range from 1.0 to 4.0 (GeV/c)2. Data from E01-012 combined with Deep Inelastic Scattering data will provide a test of quark-hadron duality predictions for g1(superscript n) and A1(superscript n). This will be one of the first tests of the spin and flavor dependence of quark-hadron duality. The demonstration of duality for spin structure functions will enable us to use the resonance data to study the nucleon spin structure in the large x{sub bj} region.
Download or read book Measurement of the Spin Structure Function of the Neutron G1 N from Deep Inelastic Scattering of Polarized Electrons from Polarized Neutrons in He 3 written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Polarized electrons of energies 19.42, 22.67, and 25.5 GeV were scattered off a polarized [sup 3]He target at SLAC's End Station A to measure the spin asymmetry of the neutron. From this asymmetry, the spin dependent structure function g[sub 1][sup n](x) was determined over a range in x from 0.03 to 0.6 with an average Q[sup 2] of 2 (GeV/C)[sup 2]. The value of the integral of g[sub 1][sup n] over x is [integral]g[sub 1][sup n](x)dx = -0.036 [+-] 0.009. The results were interpreted in the frame work of the Quark Parton Model (QPM) and used to test the Ellis-Jaffe and Bjorken sum rules. The value of the integral is 2.6 standard deviations from the Ellis-Jaffe prediction while the Bjorken sum rule was found to be in agreement with this data and proton data from SMC and E-143.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1989 with total page 1398 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cities and Their Vital Systems written by Advisory Committee on Technology and Society and published by National Academies Press. This book was released on 1989 with total page 1298 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cities and Their Vital Systems asks basic questions about the longevity, utility, and nature of urban infrastructures; analyzes how they grow, interact, and change; and asks how, when, and at what cost they should be replaced. Among the topics discussed are problems arising from increasing air travel and airport congestion; the adequacy of water supplies and waste treatment; the impact of new technologies on construction; urban real estate values; and the field of "telematics," the combination of computers and telecommunications that makes money machines and national newspapers possible.
Download or read book Government reports annual index written by and published by . This book was released on 199? with total page 1228 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ERDA Energy Research Abstracts written by United States. Energy Research and Development Administration and published by . This book was released on 1977 with total page 994 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1996 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt:
