689 research outputs found
The MGDO software library for data analysis in Ge neutrinoless double-beta decay experiments
The GERDA and Majorana experiments will search for neutrinoless double-beta
decay of germanium-76 using isotopically enriched high-purity germanium
detectors. Although the experiments differ in conceptual design, they share
many aspects in common, and in particular will employ similar data analysis
techniques. The collaborations are jointly developing a C++ software library,
MGDO, which contains a set of data objects and interfaces to encapsulate, store
and manage physical quantities of interest, such as waveforms and high-purity
germanium detector geometries. These data objects define a common format for
persistent data, whether it is generated by Monte Carlo simulations or an
experimental apparatus, to reduce code duplication and to ease the exchange of
information between detector systems. MGDO also includes general-purpose
analysis tools that can be used for the processing of measured or simulated
digital signals. The MGDO design is based on the Object-Oriented programming
paradigm and is very flexible, allowing for easy extension and customization of
the components. The tools provided by the MGDO libraries are used by both GERDA
and Majorana.Comment: 4 pages, 1 figure, proceedings for TAUP201
Aircraft measurements of trace gases and particles near the tropopause
Research activities which were performed using atmospheric constituent data obtained by the NASA Global Atmospheric Sampling Program are described. The characteristics of the particle size spectrum in various meteorological settings from a special collection of GASP data are surveyed. The relationship between humidity and cloud particles is analyzed. Climatological and case studies of tropical ozone distributions measured on a large number of flights are reported. Particle counter calibrations are discussed as well as the comparison of GASP particle data in the upper troposphere with other measurements at lower altitudes over the Pacific Ocean
Measurement of the double-\beta decay half-life of ^{136}Xe with the KamLAND-Zen experiment
We present results from the KamLAND-Zen double-beta decay experiment based on
an exposure of 77.6 days with 129 kg of Xe. The measured two-neutrino
double-beta decay half-life of Xe is yr, consistent with a recent
measurement by EXO-200. We also obtain a lower limit for the neutrinoless
double-beta decay half-life, yr at 90%
confidence level (C.L.), which corresponds to almost a five-fold improvement
over previous limits.Comment: 6 pages, 4 figures. Version as published in PR
Study of electron anti-neutrinos associated with gamma-ray bursts using KamLAND
We search for electron anti-neutrinos () from long and
short-duration gamma-ray bursts~(GRBs) using data taken by the KamLAND detector
from August 2002 to June 2013. No statistically significant excess over the
background level is found. We place the tightest upper limits on
fluence from GRBs below 7 MeV and place first constraints on
the relation between luminosity and effective temperature.Comment: 16 pages and 5 figure
Electrical coupling of neuro-ommatidial photoreceptor cells in the blowfly
A new method of microstimulation of the blowfly eye using corneal neutralization was applied to the 6 peripheral photoreceptor cells (R1-R6) connected to one neuro-ommatidium (and thus looking into the same direction), whilst the receptor potential of a dark-adapted photoreceptor cell was recorded by means of an intracellular microelectrode. Stimulation of the photoreceptor cells not impaled elicited responses in the recorded cell of about 20% of the response elicited when stimulating the recorded cell. This is probably caused by gap junctions recently found between the axon terminals of these cells. Stimulation of all 6 cells together yielded responses that were larger and longer than those obtained with stimulation of just the recorded cell, and intensity-response curves that deviated more strongly from linearity. Evidence is presented that the resistance of the axon terminal of the photoreceptor cells quickly drops in response to a light flash, depending on the light intensity. Incorporating the cable properties of the cell body and the axon, the resistance of the gap junctions, and the (adapting) terminal resistance, a theoretical model is presented that explains the measurements well. Finally, it is argued that the gap junctions between the photoreceptor cells may effectively uncouple the synaptic responses of the cells by counteracting the influence of field potentials.
KamLAND Sensitivity to Neutrinos from Pre-Supernova Stars
In the late stages of nuclear burning for massive stars (M>8~M_{\sun}), the
production of neutrino-antineutrino pairs through various processes becomes the
dominant stellar cooling mechanism. As the star evolves, the energy of these
neutrinos increases and in the days preceding the supernova a significant
fraction of emitted electron anti-neutrinos exceeds the energy threshold for
inverse beta decay on free hydrogen. This is the golden channel for liquid
scintillator detectors because the coincidence signature allows for significant
reductions in background signals. We find that the kiloton-scale liquid
scintillator detector KamLAND can detect these pre-supernova neutrinos from a
star with a mass of 25~M_{\sun} at a distance less than 690~pc with 3
significance before the supernova. This limit is dependent on the neutrino mass
ordering and background levels. KamLAND takes data continuously and can provide
a supernova alert to the community.Comment: 19 pages, 6 figures, 1 tabl
A compact ultra-clean system for deploying radioactive sources inside the KamLAND detector
We describe a compact, ultra-clean device used to deploy radioactive sources
along the vertical axis of the KamLAND liquid-scintillator neutrino detector
for purposes of calibration. The device worked by paying out and reeling in
precise lengths of a hanging, small-gauge wire rope (cable); an assortment of
interchangeable radioactive sources could be attached to a weight at the end of
the cable. All components exposed to the radiopure liquid scintillator were
made of chemically compatible UHV-cleaned materials, primarily stainless steel,
in order to avoid contaminating or degrading the scintillator. To prevent radon
intrusion, the apparatus was enclosed in a hermetically sealed housing inside a
glove box, and both volumes were regularly flushed with purified nitrogen gas.
An infrared camera attached to the side of the housing permitted real-time
visual monitoring of the cable's motion, and the system was controlled via a
graphical user interface.Comment: Revised author affiliations, corrected typos, made minor improvements
to text, and revised reference
7Be Solar Neutrino Measurement with KamLAND
We report a measurement of the neutrino-electron elastic scattering rate of
862 keV 7Be solar neutrinos based on a 165.4 kton-day exposure of KamLAND. The
observed rate is 582 +/- 90 (kton-day)^-1, which corresponds to a 862 keV 7Be
solar neutrino flux of (3.26 +/- 0.50) x 10^9 cm^-2s^-1, assuming a pure
electron flavor flux. Comparing this flux with the standard solar model
prediction and further assuming three flavor mixing, a nu_e survival
probability of 0.66 +/- 0.14 is determined from the KamLAND data. Utilizing a
global three flavor oscillation analysis, we obtain a total 7Be solar neutrino
flux of (5.82 +/- 0.98) x 10^9 cm^-2s^-1, which is consistent with the standard
solar model predictions.Comment: 8 pages, 6 figures, submitted to Phys. Rev.
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