IceCube is a one-gigaton instrument located at the geographic South Pole, designed to detect cosmic neutrinos, identify the particle nature of dark matter, and study high-energy neutrinos themselves. ...Simulation of the IceCube detector and processing of data require a significant amount of computational resources. This paper presents the first detailed description of IceProd, a lightweight distributed management system designed to meet these requirements. It is driven by a central database in order to manage mass production of simulations and analysis of data produced by the IceCube detector. IceProd runs as a separate layer on top of other middleware and can take advantage of a variety of computing resources, including grids and batch systems such as CREAM, HTCondor, and PBS. This is accomplished by a set of dedicated daemons that process job submission in a coordinated fashion through the use of middleware plugins that serve to abstract the details of job submission and job management from the framework.
•IceProd is a lightweight distributed workflow management framework.•Uses existing middleware and protocols.•Runs at user-level and is easily adaptable to other applications.•It has been successful in managing 450k cores across 25 computing centers.•Identified areas of improvement including scalability and load balancing.
Using the neutrino telescope AMANDA-II, we have conducted two analyses searching for neutrino-induced cascades from gamma-ray bursts. No evidence of astrophysical neutrinos was found, and limits are ...presented for several models. We also present neutrino effective areas which allow the calculation of limits for any neutrino production model. The first analysis looked for a statistical excess of events within a sliding window of 1 or 100 s (for short and long burst classes, respectively) during the years 2001-2003. The resulting upper limit on the diffuse flux normalization times E super(2) for the Waxman-Bahcall model at 1 PeV is 1.6 x 10 super(-6) GeV cm super(-2) s super(-1) sr super(-1) (a factor of 120 above the theoretical prediction). For this search 90% of the neutrinos would fall in the energy range 50 TeV to 7 PeV. The second analysis looked for neutrino-induced cascades in coincidence with 73 bursts detected by BATSE in the year 2000. The resulting upper limit on the diffuse flux normalization times E super(2), also at 1 PeV, is 1.5 x 10 super(-6) GeV cm super(-2) s super(-1) sr super(-1) (a factor of 110 above the theoretical prediction) for the same energy range. The neutrino-induced cascade channel is complementary to the up-going muon channel. We comment on its advantages for searches of neutrinos from GRBs and its future use with IceCube.
We present a measurement of neutrino oscillations via atmospheric muon neutrino disappearance with three years of data of the completed IceCube neutrino detector. DeepCore, a region of denser IceCube ...instrumentation, enables the detection and reconstruction of atmospheric muon neutrinos between 10 and 100 GeV, where a strong disappearance signal is expected. The IceCube detector volume surrounding DeepCore is used as a veto region to suppress the atmospheric muon background. Neutrino events are selected where the detected Cherenkov photons of the secondary particles minimally scatter, and the neutrino energy and arrival direction are reconstructed. Both variables are used to obtain the neutrino oscillation parameters from the data, with the best fit given by Delta m(32)(2) = 2.72(-0.20)(+0.19) x 10(-3) eV(2) and sin(2)theta(23) = 0.53(-0.12)(+0.09) (normal mass ordering assumed). The results are compatible, and comparable in precision, to those of dedicated oscillation experiments.
Relative reward effects highlight the impact of reward value shifts on goal-directed behavior. A popular method used to study relative reward effects is incentive contrast. Positive contrast is an ...upshift or increase in behavior toward an outcome due to an alternative while negative contrast is the opposite. The ability to compare rewards and utilize value shifts to make advantageous decisions may be altered in alcohol use disorders. We examined the reward comparison abilities of Sprague-Dawley (SD) and alcohol-preferring (P) rats in an operant task using 12 sucrose solution pairings to determine potential line differences in incentive contrast before P rat alcohol exposure. Animals underwent a repeated-measures design consisting of 2 single outcome blocks separated by a mixed outcome block. Appetitive and consummatory measures were used to assess positive and negative contrast toward single outcomes relative to those outcomes when they were compared to alternatives. Preliminary data in unrestricted animals show that alcohol-naive P rats are more vigilant to obtain sucrose and exhibit higher reward seeking and sucrose intake than SD rats. P rats also show more generalized responding and a complete lack of appetitive and consummatory contrast. Unrestricted SD rats show more reliable consummatory contrast as opposed to appetitive contrast. Results suggest that alcoholnaive P rats have inherent predispositions to outcome insensitivity and disrupted reward comparison abilities which are crucial in guiding goal-directed behavior. Future work will examine the impact of food restriction on contrast, alcohol's effect on contrast in P rats, and contrast effects on P rat alcohol consumption.
The Pierre Auger Observatory, in Argentina, is the present flagship experiment studying ultrahigh-energy cosmic rays (UHECRs). Facing the challenge due to low cosmic-ray flux at the highest energies, ...the Observatory has been taking data for more than a decade, reaching an exposure of over 50 000 km2 sr yr. The combination of a large surface detector array and fluorescence telescopes provides a substantial improvement in energy calibration and extensive air shower measurements, resulting in data of unprecedented quality. Moreover, the installation of a denser subarray has allowed extending the sensitivity to lower energies. Altogether, this contributes to provide important information on key questions in the UHECR field in the energy range from 0.1 EeV up to 100 EeV. A review of main results from the Pierre Auger Observatory is presented with a particular focus on the energy spectrum measurements, the mass composition studies, the arrival directions analyses, the search for neutral cosmic messengers, and the investigation of high-energy hadronic interactions. Despite this large amount of valuable results, the understanding of the nature of UHECRs and of their origin remains an open science case that the Auger collaboration is planning to address with the AugerPrime project to upgrade the Observatory.
It is planned to operate the Pierre Auger Observatory until at least the end of 2024. An upgrade of the experiment has been proposed in order to provide additional measurements to allow one to ...elucidate the mass composition and the origin of the flux suppression at the highest energies, to search for a flux contribution of protons up to the highest energies and to reach a sensitivity to a contribution as small as 10% in the flux suppression region, to study extensive air showers and hadronic multi-particle production. With operation planned until 2024, event statistics will more than double compared with the existing Auger data set, with the critical added advantage that every event will now have mass information. Obtaining additional composition-sensitive information will not only help to better reconstruct the properties of the primary particles at the highest energies, but also improve the measurements in the energy range just above the ankle. Furthermore, measurements with the new detectors will help to reduce systematic uncertainties related to the modelling hadronic showers and to limitations in the reconstruction algorithms. A description of the principal proposed Auger upgrade will be presented. The Auger upgrade promises high-quality future data, and real scope for new physics.
We present a combined fit of a simple astrophysical model of UHECR sources to both the energy spectrum and mass composition data measured by the Pierre Auger Observatory. The fit has been performed ...for energies above 5 EeV, i.e. the region of the all-particle spectrum above the so-called “ankle”’ feature. The astrophysical model we adopted consists of identical sources uniformly distributed in a comoving volume, where nuclei are accelerated with a rigidity-dependent mechanism. The fit results suggest sources characterized by relatively low maximum injection energies and hard spectral indices. The impact of various systematic uncertainties on the above result is discussed.
PDF
