Polarization Correlation Measurements of Electron Impact Excitation ofH(2p)at 54.4 eV

Abstract

First direct measurements are reported of the linear reduced Stokes parameters P 1 , P 2 for H(2p) excited by electron impact at the benchmark energy of 54.4 eV. The results differ significantly from previous values deduced from angular correlation measurements which are in serious conflict with all sophisticated theoretical approaches. Our results support the trend of theoretical predictions for P 2 and confirm that its value is negative at electron scattering angles above 100 ± , as predicted by theory. [S0031-9007(98)05388-5]

New and Old Measurements of Electron Scattering in Atomic Hydrogen

“…They are in agreement with values from the intermediate energy R-matrix method of Scholz et al (1991) and the pseudostate close coupling method of Wang et al (1994). Similar measurements are in progress for 54 eV where Salim et al (1997) and O'Neill et al (1998) have indicated progress.…”

Recent progress in the description of positron scattering from atoms using the convergent close-coupling theory

“…Accordingly, establishing convergence in just the one-centre approach is all that needs to be done, though historically this was a major challenge [37,68]. Though convergence was shown to be to a result that disagreed with experiment [68], subsequent experiments showed excellent agreement with the CCC theory [234,235], which lead to reanalysis of the original data [236] yielding good agreement with the CCC theory and new experiments. A similar situation occurred in the case of double photoionisation of helium [237,238], which in effect is electron scattering on the singly charged helium ion [239,240].…”

Functional brain signals: a photon counting system for brain activity monitoring

“…A CW excitation photon-counting apparatus for measurement of ms-scale variation in optical scattering in response to vascular and neural activity related to visual function is reported here based on fast timing techniques [10]. A CW laser diode with wavelength 780nm and optical power 5mW is used as a light source.…”

“…Photon counting is done by counting the detector pulses produced by the PMT within consecutive time intervals by a counter/timer combination using the MCS. It has the advantage that it is insensitive to low frequency noise and there is also no baseline drift due to spurious currents in the PMT or in the PMT voltage divider [10]. In addition to these advantages, time-resolved technique improves localisation and characterisation of inhomogenities of the living tissue, which allows better spatial resolution.…”