2,071 research outputs found
Inert-Sterile Neutrino: Cold or Warm Dark Matter Candidate
In usual particle models, sterile neutrinos can account for the dark matter
of the Universe only if they have masses in the keV range and are warm dark
matter. Stringent cosmological and astrophysical bounds, in particular imposed
by X-ray observations, apply to them. We point out that in a particular
variation of the inert doublet model, sterile neutrinos can account for the
dark matter in the Universe and may be either cold or warm dark matter
candidates, even for masses much larger than the keV range. These Inert-Sterile
neutrinos, produced non-thermally in the early Universe, would be stable and
have very small couplings to Standard Model particles, rendering very difficult
their detection in either direct or indirect dark matter searches. They could
be, in principle, revealed in colliders by discovering other particles in the
model.Comment: 10 pages, 5 figures; version 2: small changes in the text and
references adde
A highly sensitive sandwich ELISA for the determination of glycomacropeptide to detect liquid whey in raw milk
Milk processing industries and distributors have problems with adulteration of liquid milk by the addition of bovine cheese whey. Recently, the detection of fraudulent manipulation of milk with whey has focused on the identification of glycomacropeptide (GMP). Current non-immunological methods to detect GMP in dairy products are expensive and time-consuming or have low sensitivity. In this study, a novel sandwich enzyme-linked immunosorbent assay (ELISA) for the detection and quantification of whey in raw milk was developed, using a polyclonal rabbit anti-GMP antibody. Calibration curves were constructed by analyzing raw milk standards containing different known concentrations of liquid cheese whey (0.02–20%). The method had a detection limit of 0.047% (v/v) and a quantification limit of 0.14% (v/v). The antibody showed high specificity and no cross-reaction with milk components (other than κ-casein) and was successful in detecting GMP in dairy commercial products. The recovery ratio was between 95.62% and 113.88% for all matrices tested. The intra-assay and interassay coefficients of variation were <6% and <7%, respectively. Finally, it can be stored for 3 months in the form of a ready-to-use kit, while maintaining its accuracy and reproducibility
MeV sterile neutrinos in low reheating temperature cosmological scenarios
It is commonly assumed that the cosmological and astrophysical bounds on the
mixings of sterile with active neutrinos are much more stringent than those
obtained from laboratory measurements. We point out that in scenarios with a
very low reheating temperature T_RH << 100 MeV at the end of (the last episode
of) inflation or entropy creation, the abundance of sterile neutrinos becomes
largely suppressed with respect to that obtained within the standard framework.
Thus, in this case cosmological bounds become much less stringent than usually
assumed, allowing sterile neutrinos to be ``visible'' in future experiments.
Here, we concentrate on massive (mostly sterile) neutrinos heavier than 1 MeV.Comment: 14 pp, 7 fig
Global fits to neutrino oscillation data
I summarize the determination of neutrino oscillation parameters within the
three-flavor framework from world neutrino oscillation data with date of May
2006, including the first results from the MINOS long-baseline experiment. It
is illustrated how the determination of the leading "solar" and "atmospheric"
parameters, as well as the bound on emerge from an interplay of
various complementary data sets. Furthermore, I discuss possible implications
of sub-leading three-flavor effects in present atmospheric neutrino data
induced by and for the bound on
and non-maximal values of , emphasizing, however, that these
effects are not statistically significant at present. Finally, in view of the
upcoming MiniBooNE results I briefly comment on the problem to reconcile the
LSND signal.Comment: 5 pages, 5 figures, talk presented at the SNOW2006 workshop,
Stockholm, 2-6 May 200
A Light Calibration System for the ProtoDUNE-DP Detector
A LED-based fiber calibration system for the ProtoDUNE-Dual Phase (DP) photon
detection system (PDS) has been designed and validated. ProtoDUNE-DP is a 6x6x6
m3 liquid argon time-projection-chamber currently being installed at the
Neutrino Platform at CERN. The PDS is based on 36 8-inch photomultiplier tubes
(PMTs) and will allow triggering on cosmic rays. The system serves as prototype
for the PDS of the final DUNE DP far detector in which the PDS also has the
function to allow the 3D event reconstruction on non-beam physics. For this
purpose an equalized PMT response is desirable to allow using the same
threshold definition for all PMT groups, simplifying the determination of the
trigger efficiency. The light calibration system described in this paper is
developed to provide this and to monitor the PMT performance in-situ.Comment: 15 pages, 5 figure
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