4,138 research outputs found
Ge growth on ion-irradiated Si self-affine fractal surfaces
We have carried out scanning tunneling microscopy experiments under ultrahigh
vacuum condition to study the morphology of ultrathin Ge films eposited on
pristine Si(100) and ion-irradiated Si(100) self-affine fractal surfaces. The
pristine and the ion-irradiated Si(100) surface have roughness exponents of
alpha=0.19+/-0.05 and alpha=0.82+/-0.04 respectively. These measurements were
carried out on two halves of the same sample where only one half was
ion-irradiated. Following deposition of a thin film of Ge (~6 A) the roughness
exponents change to 0.11+/-0.04 and 0.99+/-0.06, respectively. Upon Ge
deposition, while the roughness increases by more than an order of magnitude on
the pristine surface, a smoothing is observed for the ion-irradiated surface.
For the ion-irradiated surface the correlation length xi increases from 32 nm
to 137 nm upon Ge deposition. Ge grows on Si surfaces in the Stranski-Krastanov
or layer-plus-island mode where islands grow on a wetting layer of about three
atomic layers. On the pristine surface the islands are predominantly of square
or rectangular shape, while on the ion-irradiated surface the islands are
nearly diamond shaped. Changes of adsorption behaviour of deposited atoms
depending on the roughness exponent (or the fractal dimension) of the substrate
surface are discussed.Comment: 5 pages, 2 figures and 1 tabl
Challenges posed by non-standard neutrino interactions in the determination of at DUNE
One of the primary objectives of Deep Underground Neutrino Experiment (DUNE)
is to discover the leptonic CP violation and to identify it's source. In this
context, we study the impact of non-standard neutrino interactions (NSIs) on
observing the CP violation signal at DUNE. We explore the impact of various
parameter degeneracies introduced by non-zero NSI and identify which of these
can influence the CP violation sensitivity and CP precision of DUNE, by
considering NSI both in data and in theory. In particular, we study how the CP
sensitivity of DUNE is affected because of the intrinsic hierarchy degeneracy
which occurs when the diagonal NSI parameter and
A new study of shower age distribution in near vertical showers by EAS air shower array
The air shower array has been developed since it started operation in 1931. The array covering an area of 900 sq m now incorporates 21 particle density sampling detectors around two muon magnetic spectrographs. The air showers are detected in the size range 10 to the 4th power to 10 to the 6th power particles. A total of 11000 showers has so far been detected. Average values of shower age have been obtained in various shower size ranges to study the dependence of shower age on shower size. The core distance dependence of shower age parameter has also been analyzed for presentation
Digital Repository of National Metallurgical Laboratory (CSIR),India
India's National Metallurgical Laboratory is preparing to adopt a green OA mandate to follow the spring 2009 recommendation of its parent organization, India's Council of Scientific & Industrial Research. NML also releases data on the rapid growth in deposits and usage of its IR in the nine months since its launch.
Written by Peter Suber
Editor, SPARC Newsletter, Harvard University, US
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