Neutrino telescopes are moving steadily toward the goal of detecting astrophysical neutrinos from the most powerful galactic and extragalactic sources. Here we describe analysis methods to search for ...high energy point-like neutrino sources using detectors deep in the ice or sea. We simulate an ideal cubic kilometer detector based on real world performance of existing detectors such as AMANDA, IceCube, and ANTARES. An unbinned likelihood ratio method is applied, making use of the point spread function and energy distribution of simulated neutrino signal events to separate them from the background of atmospheric neutrinos produced by cosmic ray showers. The unbinned point source analyses are shown to perform better than binned searches and, depending on the source spectral index, the use of energy information is shown to improve discovery potential by almost a factor of two.
Professor Raymond Cohen 1923-2020 Braun, Jim; Groll, Eckhard
Science & technology for the built environment,
02/2021, Letnik:
27, Številka:
4
Journal Article
We present maximum-likelihood search methods for time-dependent fluxes from point sources, such as flares or periodic emissions. We describe a method for the case when the time dependence of the flux ...can be assumed
a priori from other observations, and we additionally describe a method to search for bursts with an unknown time dependence. In the context of high energy neutrino astronomy, we simulate one year of data from a cubic kilometer scale neutrino detector and characterize these methods and equivalent binned methods with respect to the duration of neutrino emission. Compared to standard time-integrated searches, we find that up to an order of magnitude fewer events are needed to discover bursts with short durations, even when the burst time and duration are not known
a priori.
The dynamic nation of Israel has evolved in almost seven decades from a beacon of freedom for Jews, to a popular destination for vacationers and tourists of all races and religions coming from all ...over the globe. There is a security checkpoint about 15 miles from our destination and a soldier briefly boards the bus to check out the vehicle's populace. --
Recent results from IceCube regarding TXS 0506+056 suggest that it may be useful to test the hypothesis of multiple neutrino flares, where each flare is not necessarily accompanied by a corresponding ...gamma-ray flare. An untriggered, time-dependent, source-stacking search would be optimal for testing this hypothesis, however such an analysis has yet to be applied to the full duration of IceCube data. Here, we discuss one possible way of constructing such an analysis, with a global test statistic obtained by summing the individual test statistics associated with each signal-like flare in the sample. This has the additional advantage of assessing the time structure of each source when running the analysis over a source catalog. We show that, for a signal consisting of many small flares, this style of analysis represents a significant increase in discovery potential over both the existing single-flare fit and the time-integrated stacking methods. Potential source catalogs are examined in combination with this method, including the possibility of a "self-triggered" catalog consisting of the locations of the highest energy northern sky events in the IceCube sample.
New optical sensors called the "D-Egg" have been developed for cost-effective instrumentation for the IceCube Upgrade. With two 8-inch high quantum efficient photomultiplier tubes (PMTs), they offer ...increased effective photocathode area while retaining as much of the successful IceCube Digital Optical Module design as possible. Mass production of D-Eggs has started in 2020. By the end of 2021, there will be 310 D-Eggs produced with 288 deployed in the IceCube Upgrade. The D-Egg readout system uses advanced technologies in electronics and computing power. Each of the two PMT signals is digitised using ultra-low-power 14-bit ADCs with a sampling frequency of 240 megaSPS, enabling seamless and lossless event recording from single-photon signals to signals exceeding 200 PE within 10 nanosecond, as well as flexible event triggering. In this paper, we report the single photon detection performance as well as the multiple photon recording capability of D-Eggs from the mass production line which have been evaluated with the built-in data acquisition system.
Smart maintenance for rooftop units BREUKER, Mark; ROSSI, Todd; BRAUN, Jim
ASHRAE journal,
11/2000, Letnik:
42, Številka:
11
Journal Article
Recenzirano
Rooftop HVAC units are often completely ignored until performance has degraded to a point where the units are no longer providing adequate cooling. This paper addresses to issues for rooftop air ...conditioners: identification of faults that drive maintenance costs and performance degradations, and common approaches to smart maintenance that reduce operating costs.
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