808 research outputs found
Improved constraints on WIMPs from the International Germanium Experiment IGEX
One IGEX 76Ge double-beta decay detector is currently operating in the
Canfranc Underground Laboratory in a search for dark matter WIMPs, through the
Ge nuclear recoil produced by the WIMP elastic scattering. A new exclusion
plot, has been derived for WIMP-nucleon spin-independent interactions. To
obtain this result, 40 days of data from the IGEX detector (energy threshold E
\~ 4 keV), recently collected, have been analyzed. These data improve the
exclusion limits derived from all the other ionization germanium detectors in
the mass region from 20 GeV to 200 GeV, where a WIMP supposedly responsible for
the annual modulation effect reported by the DAMA experiment would be located.
The new IGEX exclusion contour enters, by the first time, the DAMA region by
using only raw data, with no background discrimination, and excludes its upper
left part. It is also shown that with a moderate improvement of the detector
performances, the DAMA region could be fully explored.Comment: 14 pages, 8 figures, submitted to Physics Letters B (revised version
after referee's comments, some figures added
Present status of IGEX dark matter search at Canfranc Underground Laboratory
One IGEX 76Ge double-beta decay detector is currently operating in the
Canfranc Underground Laboratory in a search for dark matter WIMPs, through the
Ge nuclear recoil produced by the WIMP elastic scattering. A new exclusion plot
has been derived for WIMP-nucleon spin-independent interactions. To obtain this
result, 40 days of data from the IGEX detector (energy threshold 4 keV),
recently collected, have been analyzed. These data improve the exclusion limits
derived from all the other ionization germanium detectors in the mass region
from 20 GeV to 200 GeV, where a WIMP supposedly responsible for the annual
modulation effect reported by the DAMA experiment would be located. The new
IGEX exclusion contour enters, by the first time, the DAMA region by using only
raw data, with no background discrimination, and excludes its upper left part.
It is also shown that with a moderate improvement of the detector performances,
the DAMA region could be fully explored.Comment: 3 pages, 3 figures, talk delivered at the 7th International Workshop
on Topics in Astroparticle and Underground Physics (TAUP 2001), September
2001, Laboratori Nazionali del Gran Sasso, Italy (to appear in the Conference
Proceedings, Nucl. Phys. B (Proc. Suppl.)
New constraints on WIMPs from the Canfranc IGEX dark matter search
The IGEX Collaboration enriched 76Ge double-beta decay detectors are
currently operating in the Canfranc Underground Laboratory with an overburden
of 2450 m.w.e. A recent upgrade has made it possible to use them in a search
for WIMPs. A new exclusion plot has been derived for WIMP-nucleon
spin-independent interaction. To obtain this result, 30 days of data from one
IGEX detector, which has an energy threshold of ~4 keV, have been considered.
These data improve the exclusion limits derived from other germanium diode
experiments in the ~50 GeV DAMA region, and show that with a moderate
improvement of the background below 10 keV, the DAMA region may be tested with
an additional 1 kg-year of exposure.Comment: 7 pages, 2 figures, submitted to Physics Letter
Pulse Shape Discrimination in the IGEX Experiment
The IGEX experiment has been operating enriched germanium detectors in the
Canfranc Underground Laboratory (Spain) in a search for the neutrinoless double
decay of 76Ge. The implementation of Pulse Shape Discrimination techniques to
reduce the radioactive background is described in detail. This analysis has
been applied to a fraction of the IGEX data, leading to a rejection of ~60 % of
their background, in the region of interest (from 2 to 2.5 MeV), down to ~0.09
c/(keV kg y).Comment: 18 pages, 10 figure
Habitat use, feeding, and reproduction of the Mayan Cichlid, Cichlosoma urophthalmus Günther, in the Alvarado Lagoonal System, Veracruz, Mexico [abstract of poster presentation]
Surface finish control by electrochemical polishing in stainless steel 316 pipes
Electrochemical machining (ECM) is a non-conventional machining process which is based on the localised anodic dissolution of any conductive material. One of the main applications of ECM is the polishing of materials with enhanced characteristics, such as high strength, heat-resistance or corrosion-resistance, i.e. electrochemical polishing. The present work presents an evaluation of the parameters involved in the ECM of Stainless Steel 316 (SS316) with the objective of predicting the resulting surface finish on the sample. The interest of studying ECM on SS316 resides on the fact that a repeatable surface finish is not easily achieved. ECM experimental tests on SS316 pipes of 1.5" (0.0381 m) diameter were conducted by varying machining parameters such as voltage, interelectrode gap, electrolyte inlet temperature, and electrolyte flow rate. The surface finish of the samples was then evaluated in order to find the significance of each of these parameters on the surface quality of the end product. Results showed that overvoltage, which is dependent on the interelectrode gap and the electrolyte temperature, is one of the main parameters affecting the surface finish; additionally there is a strong relationship between the resulting surface finish and the electrolyte flow. The interelectrode gap and inlet electrolyte temperature also affect the resulting surface finish but their influence was not so evident in this work. Finally, the variation of the electrolyte temperature during the process was found to have a great impact on the uniformity of the surface finish along the sample. We believe that this contribution enables the tailoring of the surface finish to specific applications while reducing manufacturing costs and duration of the ECM process
String Theory on Dp-plane waves
We study the spectrum of solvable string models on plane waves descending
from non-conformal Dp-brane geometries. We mainly focus on S-dual F1/D1-waves
in type IIB and type I/heterotic 10D superstrings. We derive the Kaluza-Klein
spectrum of N=1,2 10D supergravities on D1/F1-waves. We compute helicity
supertraces counting multiplicities and R-charges of string excitations in the
plane wave geometry. The results are compared against the expectations coming
from gauge/supergravity descriptions. In the type I case, the Klein, Annulus
and Moebius one-loop amplitudes are computed for ten-dimensional D1-waves. We
test the consistency of the open string descendant by showing that after
modular transformations to the closed string channel, the three amplitudes
combine themselves to reconstruct a complete square (|B>+|C>)^2. Tadpole
conditions are also discussed.Comment: 22 pages, Minor corrections, References adde
The 21 cm Signature of Shock Heated and Diffuse Cosmic String Wakes
The analysis of the 21 cm signature of cosmic string wakes is extended in
several ways. First we consider the constraints on from the absorption
signal of shock heated wakes laid down much later than matter radiation
equality. Secondly we analyze the signal of diffuse wake, that is those wakes
in which there is a baryon overdensity but which have not shock heated. Finally
we compare the size of these signals compared to the expected thermal noise per
pixel which dominates over the background cosmic gas brightness temperature and
find that the cosmic string signal will exceed the thermal noise of an
individual pixel in the Square Kilometre Array for string tensions .Comment: 10 pages, 4 figures, Appendix added, version published in JCA
Effect of preharvest fruit bagging on fruit quality characteristics and incidence of fruit physiopathies in fully irrigated and water stressed pomegranated trees
BACKGROUND: This report studied the response of pomegranate fruit under full irrigation (FI) and water stress (WS) conditions to bagging with externally glossy single layer cellulosic paper bags open at the bottom from the end of fruit thinning to harvest time. RESULTS: Bagging decreased fruit size and the maturity index, and increased antioxidant activity in FI conditions. Moreover, fruit bagging substantially reduced the incidence of peel sunburn in both irrigation conditions. CONCLUSION: The delay in fruit growth and ripening as a result of pomegranate fruit bagging is outweighed by the very important commercial benefit in terms of the reduced incidence of peel sunburn and the increase in fruit antioxidant activity
UV and EUV Instruments
We describe telescopes and instruments that were developed and used for
astronomical research in the ultraviolet (UV) and extreme ultraviolet (EUV)
regions of the electromagnetic spectrum. The wavelength ranges covered by these
bands are not uniquely defined. We use the following convention here: The EUV
and UV span the regions ~100-912 and 912-3000 Angstroem respectively. The
limitation between both ranges is a natural choice, because the hydrogen Lyman
absorption edge is located at 912 Angstroem. At smaller wavelengths,
astronomical sources are strongly absorbed by the interstellar medium. It also
marks a technical limit, because telescopes and instruments are of different
design. In the EUV range, the technology is strongly related to that utilized
in X-ray astronomy, while in the UV range the instruments in many cases have
their roots in optical astronomy. We will, therefore, describe the UV and EUV
instruments in appropriate conciseness and refer to the respective chapters of
this volume for more technical details.Comment: To appear in: Landolt-Boernstein, New Series VI/4A, Astronomy,
Astrophysics, and Cosmology; Instruments and Methods, ed. J.E. Truemper,
Springer-Verlag, Berlin, 201
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