18,536 research outputs found
Search for extraterrestrial antineutrino sources with the KamLAND detector
We present the results of a search for extraterrestrial electron
antineutrinos ('s) in the energy range using the KamLAND detector. In an exposure of
4.53 kton-year, we identify 25 candidate events. All of the candidate events
can be attributed to background, most importantly neutral current atmospheric
neutrino interactions, setting an upper limit on the probability of B
solar 's converting into 's at
(90% C.L.), if we assume an undistorted shape. This limit
corresponds to a solar flux of or an event
rate of above the energy threshold
. The present data also allows us to set more
stringent limits on the diffuse supernova neutrino flux and on the annihilation
rates for light dark matter particles.Comment: 22 pages, 6 figure
JUNO Conceptual Design Report
The Jiangmen Underground Neutrino Observatory (JUNO) is proposed to determine
the neutrino mass hierarchy using an underground liquid scintillator detector.
It is located 53 km away from both Yangjiang and Taishan Nuclear Power Plants
in Guangdong, China. The experimental hall, spanning more than 50 meters, is
under a granite mountain of over 700 m overburden. Within six years of running,
the detection of reactor antineutrinos can resolve the neutrino mass hierarchy
at a confidence level of 3-4, and determine neutrino oscillation
parameters , , and to
an accuracy of better than 1%. The JUNO detector can be also used to study
terrestrial and extra-terrestrial neutrinos and new physics beyond the Standard
Model. The central detector contains 20,000 tons liquid scintillator with an
acrylic sphere of 35 m in diameter. 17,000 508-mm diameter PMTs with high
quantum efficiency provide 75% optical coverage. The current choice of
the liquid scintillator is: linear alkyl benzene (LAB) as the solvent, plus PPO
as the scintillation fluor and a wavelength-shifter (Bis-MSB). The number of
detected photoelectrons per MeV is larger than 1,100 and the energy resolution
is expected to be 3% at 1 MeV. The calibration system is designed to deploy
multiple sources to cover the entire energy range of reactor antineutrinos, and
to achieve a full-volume position coverage inside the detector. The veto system
is used for muon detection, muon induced background study and reduction. It
consists of a Water Cherenkov detector and a Top Tracker system. The readout
system, the detector control system and the offline system insure efficient and
stable data acquisition and processing.Comment: 328 pages, 211 figure
NASA Thesaurus Supplement: A three part cumulative supplement to the 1982 edition of the NASA Thesaurus (supplement 2)
The three part cumulative NASA Thesaurus Supplement to the 1982 edition of the NASA Thesaurus includes: part 1, hierarchical listing; part 2, access vocabulary, and part 3, deletions. The semiannual supplement gives complete hierarchies for new terms and includes new term indications for terms new to this supplement
Freezing point depression and freeze-thaw damage by nano-fuidic salt trapping
A remarkable variety of organisms and wet materials are able to endure
temperatures far below the freezing point of bulk water. Cryo-tolerance in
biology is usually attributed to "anti-freeze" proteins, and yet massive
supercooling (C) is also possible in porous media containing only
simple aqueous electrolytes. For concrete pavements, the common wisdom is that
freeze-thaw damage results from the expansion of water upon freezing, but this
cannot explain the large pressures (~MPa) required to damage concrete,
the observed correlation between pavement damage and de-icing salts, or the
damage of cement paste loaded with benzene (which contracts upon freezing). In
this Letter, we propose a different mechanism -- nanofluidic salt trapping --
which can explain the observations, using simple mathematical models of
dissolved ions confined to thin liquid films between growing ice and charged
surfaces. Although trapped salt lowers the freezing point, ice nucleation in
charged pores causes enormous disjoining pressures via the rejected ions, until
their removal by precipitation or surface adsorption at a lower temperatures
releases the pressure and allows complete freezing. The theory is able to
predict the non-monotonic salt-concentration dependence of freeze-thaw damage
in concreter and provides a general framework to understand the origins of
cryo-tolerance.Comment: 5 figure
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