Browsing by Author "Kang H."

Now showing 1 - 3 of 3
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    Dynamic speckle analysis with smoothed intensity-based activity maps
    (2017-06-01) Stoykova E.; Berberova N.; Kim Y.; Nazarova D.; Ivanov B.; Gotchev A.; Hong J.; Kang H.
    Pointwise intensity-based algorithms are the most popular algorithms in dynamic laser speckle measurement of physical or biological activity. The output of this measurement is a two-dimensional map which qualitatively separates regions of higher or lower activity. In the paper, we have proposed filtering of activity maps to enhance visualization and to enable quantitative determination of activity time scales. As a first step, we have proved that the severe spatial fluctuations within the map resemble a signal-dependent noise. As a second step, we have illustrated implementation of the proposed idea by applying filters to non-normalized and normalized activity estimates derived from synthetic and experimental data. Statistical behavior of the estimates has been analyzed to choose the filter parameters, and substantial narrowing of the probability density functions of the estimates has been achieved after the filtering. The filtered maps exhibit an improved contrast and allowed for quantitative description of activity.
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    Polarization components in π0 photoproduction at photon energies up to 5.6 GeV
    (2012-05-31) Luo W.; Brash E.J.; Gilman R.; Jones M.K.; Meziane M.; Pentchev L.; Perdrisat C.F.; Puckett A.J.R.; Punjabi V.; Wesselmann F.R.; Ahmidouch A.; Albayrak I.; Aniol K.A.; Arrington J.; Asaturyan A.; Ates O.; Baghdasaryan H.; Benmokhtar F.; Bertozzi W.; Bimbot L.; Bosted P.; Boeglin W.; Butuceanu C.; Carter P.; Chernenko S.; Christy M.E.; Commisso M.; Cornejo J.C.; Covrig S.; Danagoulian S.; Daniel A.; Davidenko A.; Day D.; Dhamija S.; Dutta D.; Ent R.; Frullani S.; Fenker H.; Frlez E.; Garibaldi F.; Gaskell D.; Gilad S.; Goncharenko Y.; Hafidi K.; Hamilton D.; Higinbotham D.W.; Hinton W.; Horn T.; Hu B.; Huang J.; Huber G.M.; Jensen E.; Kang H.; Keppel C.; Khandaker M.; King P.; Kirillov D.; Kohl M.; Kravtsov V.; Kumbartzki G.; Li Y.; Mamyan V.; Margaziotis D.J.; Markowitz P.; Marsh A.; Matulenko Y.; Maxwell J.; Mbianda G.; Meekins D.; Melnik Y.; Miller J.; Mkrtchyan A.; Mkrtchyan H.; Moffit B.; Moreno O.; Mulholland J.; Narayan A.; Nuruzzaman; Nedev S.; Piasetzky E.; Pierce W.; Piskunov N.M.; Prok Y.; Ransome R.D.; Razin D.S.; Reimer P.E.; Reinhold J.; Rondon O.; Shabestari M.; Shahinyan A.; Shestermanov K.; Airca S.; Sitnik I.; Smykov L.; Smith G.; Solovyev L.; Solvignon P.; Strakovsky I.I.; Subedi R.; Suleiman R.; Tomasi-Gustafsson E.; Vasiliev A.; Veilleux M.; Wood S.; Ye Z.; Zanevsky Y.; Zhang X.; Zhang Y.; Zheng X.; Zhu L.
    We present new data for the polarization observables of the final state proton in the H1(γ→,p→)π0 reaction. These data can be used to test predictions based on hadron helicity conservation and perturbative QCD. These data have both small statistical and systematic uncertainties and were obtained with beam energies between 1.8 and 5.6GeV and for π0 scattering angles larger than 75° in the center-of-mass frame. The data extend the polarization measurements database for neutral pion photoproduction up to E γ=5.6GeV. The results show a nonzero induced polarization above the resonance region. The polarization transfer components vary rapidly with the photon energy and π0 scattering angle in the center-of-mass frame. This indicates that hadron helicity conservation does not hold and that the perturbative QCD limit is still not reached in the energy regime of this experiment. © 2012 American Physical Society.
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    Search for effects beyond the born approximation in polarization transfer observables in e→p elastic scattering
    (2011-03-29) Meziane M.; Brash E.J.; Gilman R.; Jones M.K.; Luo W.; Pentchev L.; Perdrisat C.F.; Puckett A.J.R.; Punjabi V.; Wesselmann F.R.; Ahmidouch A.; Albayrak I.; Aniol K.A.; Arrington J.; Asaturyan A.; Ates O.; Baghdasaryan H.; Benmokhtar F.; Bertozzi W.; Bimbot L.; Bosted P.; Boeglin W.; Butuceanu C.; Carter P.; Chernenko S.; Christy E.; Commisso M.; Cornejo J.C.; Covrig S.; Danagoulian S.; Daniel A.; Davidenko A.; Day D.; Dhamija S.; Dutta D.; Ent R.; Frullani S.; Fenker H.; Frlez E.; Garibaldi F.; Gaskell D.; Gilad S.; Goncharenko Y.; Hafidi K.; Hamilton D.; Higinbotham D.W.; Hinton W.; Horn T.; Hu B.; Huang J.; Huber G.M.; Jensen E.; Kang H.; Keppel C.; Khandaker M.; King P.; Kirillov D.; Kohl M.; Kravtsov V.; Kumbartzki G.; Li Y.; Mamyan V.; Margaziotis D.J.; Markowitz P.; Marsh A.; Matulenko Y.; Maxwell J.; Mbianda G.; Meekins D.; Melnik Y.; Miller J.; Mkrtchyan A.; Mkrtchyan H.; Moffit B.; Moreno O.; Mulholland J.; Narayan A.; Nuruzzaman; Nedev S.; Piasetzky E.; Pierce W.; Piskunov N.M.; Prok Y.; Ransome R.D.; Razin D.S.; Reimer P.E.; Reinhold J.; Rondon O.; Shabestari M.; Shahinyan A.; Shestermanov K.; Åirca S.; Sitnik I.; Smykov L.; Smith G.; Solovyev L.; Solvignon P.; Subedi R.; Suleiman R.; Tomasi-Gustafsson E.; Vasiliev A.; Vanderhaeghen M.; Veilleux M.; Wojtsekhowski B.B.; Wood S.; Ye Z.; Zanevsky Y.; Zhang X.; Zhang Y.; Zheng X.; Zhu L.
    Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, GE/GM, obtained separately from cross section and polarization transfer measurements. One possible explanation for this difference is a two-photon-exchange contribution. In an effort to search for effects beyond the one-photon-exchange or Born approximation, we report measurements of polarization transfer observables in the elastic H(e→,e′p→) reaction for three different beam energies at a Q2=2.5GeV2, spanning a wide range of the kinematic parameter μ. The ratio R, which equals μpGE/GM in the Born approximation, is found to be independent of μ at the 1.5% level. The μ dependence of the longitudinal polarization transfer component P ℓ shows an enhancement of (2.3±0.6)% relative to the Born approximation at large μ. © 2011 American Physical Society.