Nuclear Transparency in Exclusive ρ0 Production at HERMES

Exclusive coherent and incoherent electroproduction of the ρ0 meson from 1H and 14N targets has been studied at the HERMES experiment as a function of coherence length (lc), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared four‐momentum of the virtual photon (−Q2). The ratio of 14N to 1H cross sections per nucleon, called nuclear transparency, was found to increase (decrease) with increasing coherence length for coherent (incoherent) ρ0 electroproduction. For fixed coherence length, a rise of nuclear transparency with Q2 is observed for both coherent and incoherent ρ0 production, which is in agreement with theoretical calculations of color transparency. © 2004 American Institute of PhysicsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87590/2/119_1.pd

Electron Beam Polarimetry for EIC/eRHIC

Ideas are being presented about how to measure the electron beam polarization at the Electron Ion Collider (EIC) at RHIC with high precision. Based on lessons learned at the HERA storage ring it is discussed which design and physics processes might be most appropriate for EIC. This is a summary of the ideas and concepts discussed at the first workshop on EIC electron beam polarimetry at BNL in November 2002. © 2004 American Institute of PhysicsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87589/2/797_1.pd

Drell-Yan scattering at Fermilab: SeaQuest and beyond

The E906/SeaQuest experiment at Fermilab will use the 120 GeV/c proton beam extracted from the Main Injector to measure the light antiquark flavor asymmetry, ¯ d/¯u, in the nucleon sea, and how it is altered in nuclei. It will provide direct input to the parton distribution fits, and provide a better understanding on the physical mechanism which generates the sea of the proton. The experiment will start in the fall of 2011 and run until the end of 2014. After completion of the SeaQuest experiment, the spectrometer will be available for a polarized Drell-Yan program, either with a polarized beam or a polarized target. The first in a long list of possible experiments at the Main Injector is a polarized Drell-Yan experiment, motivated by a fundamental prediction of QCD that postulates a sign change in the Sivers function measured in Drell-Yan as compared to deep inelastic scattering

High rate production of polarized 3He with meta-stability exchange method

Keywords: polarized 3He, meta-stability exchange, infrared laserComment: 4 figures, submitted to J. Phys. Soc. Jpn

NMR calibration of optical measurement of nuclear polarization in 3He

We have performed precise NMR measurements in order to calibrate a standard optical technique for measuring the polarization of 3He nuclei. This optical technique requires knowledge of the pressure-dependent relationship between the nuclear polarization and the degree of circular polarization of the 668-nm light emitted from a 3He discharge. We determined the nuclear polarization by comparing the adiabatic fast-passage NMR signal from samples of polarized 3He at pressures between 0.1 and 5 torr to an identical sample of water. For water, the polarization is known from statistical mechanics. The 3He is polarized using the metastability exchange technique for optical pumping of 3He. The accuracy of the calibration is ±2%, which is required for applications in nuclear physics

Momentum Transfer Dependence of Nuclear Transparency from the Quasielastic ^(12)C(e, e'p) Reaction

The cross section for quasielastic ^(12)C(e,e’p) scattering has been measured at momentum transfer Q^2=1, 3, 5, and 6.8 (GeV/c)^2. The results are consistent with scattering from a single nucleon as the dominant process. The nuclear transparency is obtained and compared with theoretical calculations that incorporate color transparency effects. No significant rise of the transparency with Q^2 is observed

Sub-Pixel Response Measurement of Near-Infrared Sensors

Wide-field survey instruments are used to efficiently observe large regions of the sky. To achieve the necessary field of view, and to provide a higher signal-to-noise ratio for faint sources, many modern instruments are undersampled. However, precision photometry with undersampled imagers requires a detailed understanding of the sensitivity variations on a scale much smaller than a pixel. To address this, a near-infrared spot projection system has been developed to precisely characterize near-infrared focal plane arrays and to study the effect of sub-pixel non uniformity on precision photometry. Measurements of large format near-infrared detectors demonstrate the power of this system for understanding sub-pixel response.Comment: 9 pages, 13 figures, submitted to PAS