90 research outputs found
Searching for neutrino emissions from multi-frequency sources
Pinpointing the neutrino sources is crucial to unveil the mystery of
high-energy cosmic rays. The search for neutrino-source candidates from
coincident neutrino-photon signatures and electromagnetic objects with peculiar
flaring behaviors have the potential to increase our chances of finding
neutrino emitters. In this paper, we first study the temporal correlations of
astrophysical flares with neutrinos, considering a few hundreds of
multi-frequency sources from ALMA, WISE, Swift, and Fermi in the containment
regions of IceCube high-energy alerts. Furthermore, the spatial correlations
between blazars and neutrinos are investigated using the subset of 10-year
IceCube track-like neutrinos with around 250 thousand events. In the second
test, we account for 2700 blazars with different types of flaring phases in
addition to sole position. No significant neutrino emissions were found from
our analyses. Our results indicate an interesting trend showing the infrared
flaring stages of WISE blazars might be correlated with arrival times of the
neutrino alerts. Possible overflow of neutrinos associated with two of our
blazar sub-samples are also illustrated. One is characterized by a significant
flaring lag in infrared with respect to gamma-rays, like seen for TXS0506+056,
and the other is characterized by highly simultaneous infrared and gamma-ray
flares. These phenomena suggest the need to improve current multi-frequency
light-curve catalogs to pair with the advent of more sensitive neutrino
observatories.Comment: 30 pages, 18 figure
A fast tunable driver of light source for the TRIDENT Pathfinder experiment
TRIDENT (The tRopIcal DEep-sea Neutrino Telescope) is a proposed
next-generation neutrino telescope to be constructed in the South China Sea. In
September 2021, the TRIDENT Pathfinder experiment (TRIDENT EXplorer, T-REX for
short) was conducted to evaluate the in-situ optical properties of seawater.
The T-REX experiment deployed three digital optical modules at a depth of 3420
meters, including a light emitter module (LEM) and two light receiver modules
(LRMs) equipped with photomultiplier tubes (PMTs) and cameras to detect light
signals. The LEM emits light in pulsing and steady modes. It features a fast
tunable driver to activate light-emitting diodes (LEDs) that emit
nanosecond-width light pulses with tunable intensity. The PMTs in the LRM
receive single photo-electron (SPE) signals with an average photon number of
approximately 0.3 per 1-microsecond time window, which is used to measure the
arrival time distribution of the SPE signals. The fast tunable driver can be
remotely controlled in real-time by the data acquisition system onboard the
research vessel, allowing for convenient adjustments to the driver's parameters
and facilitating the acquisition of high-quality experimental data. This paper
describes the requirements, design scheme, and test results of the fast tunable
driver, highlighting its successful implementation in the T-REX experiment and
its potential for future deep-sea experiments
Seismic loss assessment for buildings with multiple LOD BIM data
Earthquake-induced economic loss of buildings is a fundamental concern for earthquake-resilient cities. The FEMA P-58 method is a state-of-the-art seismic loss assessment method for buildings. Nevertheless, because the FEMA P-58 method is a refined component-level loss assessment method, it requires highly detailed data as the input. Consequently, the knowledge of building details will affect the seismic loss assessment. In this study, a seismic loss assessment approach for buildings combining building information modeling (BIM) with the FEMA P-58 method is proposed. The detailed building data are automatically obtained from the building information model in which the building components may have different levels of development (LODs). The determination of component type and the development of the component vulnerability function when the information is incomplete are proposed. Finally, to demonstrate the rationality of the proposed method, an office building that is available online is selected, and the seismic loss assessments with multi-LOD BIM data are performed as case studies. The results show that, on the one hand, even if the available building information is limited, the proposed method can still produce an acceptable loss assessmenton the other hand, given more information, the accuracy of the assessment can be improved and the uncertainty can be reduced using the proposed method.The study is financial supported by the National Natural Science Foundation of China (No. 51578320)
Simulation study on the optical processes at deep-sea neutrino telescope sites
The performance of a large-scale water Cherenkov neutrino telescope relies
heavily on the transparency of the surrounding water, quantified by its level
of light absorption and scattering. A pathfinder experiment was carried out to
measure the optical properties of deep seawater in South China Sea with
light-emitting diodes (LEDs) as light sources, photon multiplier tubes (PMTs)
and cameras as photon sensors. Here, we present an optical simulation program
employing the Geant4 toolkit to understand the absorption and scattering
processes in the deep seawater, which helps to extract the underlying optical
properties from the experimental data. The simulation results are compared with
the experimental data and show good agreements. We also verify the analysis
methods that utilize various observables of the PMTs and the cameras with this
simulation program, which can be easily adapted by other neutrino telescope
pathfinder experiments and future large-scale detectors.Comment: 27 pages, 11 figure
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