6,655 research outputs found
Accounting for correlations with core electrons by means of the generalized relativistic effective core potentials: Atoms Hg and Pb and their compounds
A way to account for correlations between the chemically active (valence) and
innermore (core) electrons in the framework of the generalized relativistic
effective core potential (GRECP) method is suggested. The "correlated" GRECP's
(CGRECP's) are generated for the Hg and Pb atoms. Only correlations for the
external twelve and four electrons of them, correspondingly, should be treated
explicitly in the subsequent calculations with these CGRECP's whereas the
innermore electrons are excluded from the calculations. Results of atomic
calculations with the correlated and earlier GRECP versions are compared with
the corresponding all-electron Dirac-Coulomb values. Calculations with the
above GRECP's and CGRECP's are also carried out for the lowest-lying states of
the HgH molecule and its cation and for the ground state of the PbO molecule as
compared to earlier calculations and experimental data. The accuracy for the
vibrational frequencies is increased up to an order of magnitude and the errors
for the bond lengths (rotational constants) are decreased in about two times
when the correlated GRECP's are applied instead of earlier GRECP versions
employing the same innercore-outercore-valence partitioning.Comment: 12 pages, 4 tables, the text of the paper was significantly improve
Summary and Outlook of the International Workshop on Aging Phenomena in Gaseous Detectors (DESY, Hamburg, October, 2001)
High Energy Physics experiments are currently entering a new era which
requires the operation of gaseous particle detectors at unprecedented high
rates and integrated particle fluxes. Full functionality of such detectors over
the lifetime of an experiment in a harsh radiation environment is of prime
concern to the involved experimenters. New classes of gaseous detectors such as
large-scale straw-type detectors, Micro-pattern Gas Detectors and related
detector types with their own specific aging effects have evolved since the
first workshop on wire chamber aging was held at LBL, Berkeley in 1986. In
light of these developments and as detector aging is a notoriously complex
field, the goal of the workshop was to provide a forum for interested
experimentalists to review the progress in understanding of aging effects and
to exchange recent experiences. A brief summary of the main results and
experiences reported at the 2001 workshop is presented, with the goal of
providing a systematic review of aging effects in state-of-the-art and future
gaseous detectors.Comment: 14 pages, 2 pictures. Presented at the IEEE Nuclear Science Symposium
and Medical Imaging Conference, November 4-10, 2001, San Diego, USA.
Submitted to IEEE Trans. Nucl. Sci (IEEE-TNS
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