5,608 research outputs found
Estimation of C II and C II* column densities along Galactic sight-lines
We present interstellar C II (1334.5323 \AA) and C II* (1335.7077 \AA) column
density measurements along 14 Galactic sight-lines. These sight-lines sample a
variety of Galactic disk environments and include paths that range nearly two
orders of magnitude in average hydrogen densities () along the lines of
sight. Five of the sight-lines show super-Solar gas phase abundances of carbon.
Our results show that the excess carbon along these sight-lines may result from
different mechanisms taking place in the regions associated with these stars.Comment: 9 pages, 3 figures; Accepted for publication in BAS
Modeling charge transport in Swept Charge Devices for X-ray spectroscopy
We present the formulation of an analytical model which simulates charge
transport in Swept Charge Devices (SCDs) to understand the nature of the
spectral redistribution function (SRF). We attempt to construct the
energy-dependent and position dependent SRF by modeling the photon interaction,
charge cloud generation and various loss mechanisms viz., recombination,
partial charge collection and split events. The model will help in optimizing
event selection, maximize event recovery and improve spectral modeling for
Chandrayaan-2 (slated for launch in 2014). A proto-type physical model is
developed and the algorithm along with its results are discussed in this paper.Comment: 9 pages, 7 figures, Proc. SPIE 8453, High Energy, Optical, and
Infrared Detectors for Astronomy
The Stability of the Gauge Hierarchy in
It has been shown that the Dimopoulos-Wilczek (or missing-VEV) mechanism for
doublet-triplet splitting can be implemented in models,
which requires no adjoint Higgs fields. This is an advantage from the point of
view of string theory construction. Here the stability of the gauge hierarchy
is examined in detail, and it is shown that it can be guaranteed much more
simply than in . In fact a symmetry ensures the stability of the
DW form of the expectation values to all orders in GUT-scale VEVs. It is also
shown that models based on have the advantages of while permitting complete quark-lepton unification as in
.Comment: 13 pages, LaTe
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