30 research outputs found
Pressure broadening and frequency shift of the D-1 and D-2 lines of Rb and K in the presence of He-3 and N-2
We report the results of a study of the pressure broadening and resonant frequency shift of the absorption profiles of the D-1 and D-2 lines of Rb and K in the presence of He-3 and N-2 gases over a range of number densities. We have also examined the temperature dependence of the broadening and shift over a range of approximately 340 to 400 K. We compare our results for the broadening and shift coefficients for Rb D-1 and D-2 to current values and present coefficients for K D-1 and D-2. DOI:10.1103/PhysRevA.87.03251
First Determination of the Weak Charge of the Proton
The Q(weak) experiment has measured the parity-violating asymmetry in (e) over right arrowp elastic scattering at Q(2) = 0.025 (GeV/c)(2), employing 145 mu A of 89% longitudinally polarized electrons on a 34.4 cm long liquid hydrogen target at Jefferson Lab. The results of the experiment\u27s commissioning run, constituting approximately 4% of the data collected in the experiment, are reported here. From these initial results, the measured asymmetry is A(ep) = -279 +/- 35 (stat) +/- 31 (syst) ppb, which is the smallest and most precise asymmetry ever measured in (e) over right arrowp scattering. The small Q(2) of this experiment has made possible the first determination of the weak charge of the proton Q(W)(p) by incorporating earlier parity-violating electron scattering (PVES) data at higher Q(2) to constrain hadronic corrections. The value of Q(W)(p) obtained in this way is Q(W)(p) (PVES) = 0.064 +/- 0.012, which is in good agreement with the standard model prediction of Q(W)(p) (SM) = 0.0710 +/- 0.0007. When this result is further combined with the Cs atomic parity violation (APV) measurement, significant constraints on the weak charges of the up and down quarks can also be extracted. That PVES + APV analysis reveals the neutron\u27s weak charge to be Q(W)(n) (PVES + APV) = -0.975 +/- 0.010
Q(weak): First Direct Measurement of the Proton\u27s Weak Charge
The Q(weak) experiment, which took data at Jefferson Lab in the period 2010 - 2012, will precisely determine the weak charge of the proton by measuring the parity-violating asymmetry in elastic e-p scattering at 1.1 GeV using a longitudinally polarized electron beam and a liquid hydrogen target at a low momentum transfer of Q(2) = 0.025 ( GeV/c)(2). The weak charge of the proton is predicted by the Standard Model and any significant deviation would indicate physics beyond the Standard Model. The technical challenges and experimental apparatus for measuring the weak charge of the proton will be discussed, as well as the method of extracting the weak charge of the proton. The results from a small subset of the data, that has been published, will also be presented. Furthermore an update will be given of the current status of the data analysis
Genomic, Pathway Network, and Immunologic Features Distinguishing Squamous Carcinomas
This integrated, multiplatform PanCancer Atlas study co-mapped and identified distinguishing
molecular features of squamous cell carcinomas (SCCs) from five sites associated with smokin
Precision measurements of A1N in the deep inelastic regime
We have performed precision measurements of the double-spin virtual-photon asymmetry A1A1 on the neutron in the deep inelastic scattering regime, using an open-geometry, large-acceptance spectrometer and a longitudinally and transversely polarized 3He target. Our data cover a wide kinematic range 0.277≤x≤0.5480.277≤x≤0.548 at an average Q2Q2 value of 3.078 (GeV/c)2, doubling the available high-precision neutron data in this x range. We have combined our results with world data on proton targets to make a leading-order extraction of the ratio of polarized-to-unpolarized parton distribution functions for up quarks and for down quarks in the same kinematic range. Our data are consistent with a previous observation of anA1n zero crossing near x=0.5x=0.5. We find no evidence of a transition to a positive slope in(Δd+Δd¯)/(d+d¯) up to x=0.548x=0.548
Female Labor Force Intermittency and Current Earnings: A Switching Regression Model with Unknown Sample Selection
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Final Report for OJI grant.
This document is a final report for DOE grant DE-FG02-00ER41147. The research described herein was funded in large part by this grant with additional support from the National Science Foundation. The primary focus of Averett's research effort is centered around the polarized {sup 3}He target in Hall A at Jefferson Lab. The close proximity of the College of William and Mary to Jefferson Lab has provided an outstanding opportunity to maintain a very active research program which still satisfying the demands of the college. Our research group includes four faculty, two post-doctoral fellows and eight graduate students. Averett also maintains a fully functional polarized {sup 3}e target lab at William and Mary which allows him to support the research program at Jefferson Lab while also doing research on polarized targets themselves. Since 1998, seven experiments using polarized {sup 3}He have been completed by the Jefferson Lab Hall A Polarized {sup 3}He Collaboration. Ten publications have been produced on this research and analysis of the two most recently completed experiments is underway. A description of the recent experiments and results is given below. In addition to target expertise, Averett has remained one of the most active collaborators in the data analysis of these experiments and maintains the largest on-site user group for this purpose as well