On 2006 December 13 the IceTop air shower array at the South Pole detected a major solar particle event. By numerically simulating the response of the IceTop tanks, which are thick Cerenkov detectors ...with multiple thresholds deployed at high altitude with no geomagnetic cutoff, we determined the particle energy spectrum in the energy range 0.6-7.6 GeV. This is the first such spectral measurement using a single instrument with a well- defined viewing direction. We compare the IceTop spectrum and its time evolution with previously published results and outline plans for improved resolution of future solar particle spectra.
We present the search for Cherenkov signatures from relativistic magnetic monopoles in data taken with the AMANDA-II detector, a neutrino telescope deployed in the Antarctic ice cap at the Geographic ...South Pole. The non-observation of a monopole signal in data collected during the year 2000 improves present experimental limits on the flux of relativistic magnetic monopoles: Our flux limit varies between 3.8×10
−17
cm
−2
s
−1
sr
−1
(for monopoles moving at the vacuum speed of light) and 8.8×10
−16
cm
−2
s
−1
sr
−1
(for monopoles moving at a speed
β
=
v
/
c
=0.76, just above the Cherenkov threshold in ice). These limits apply to monopoles that are energetic enough to penetrate the Earth and enter the detector from below the horizon. The limit obtained for monopoles reaching the detector from above the horizon is less stringent by roughly an order of magnitude, due to the much larger background from down-going atmospheric muons. This looser limit is however valid for a larger class of magnetic monopoles, since the monopoles are not required to pass through the Earth.
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.
► Studies on noise level and transient noise in South Pole ice with the South Pole Acoustic Test Setup (SPATS). ► Acoustic noise level in South Pole ice estimated to be smaller than 20
mPa in 10–50
...kHz frequency range. ► Refreezing of IceCube holes and Rodriguez wells observed acoustically. ► Upper limit on the flux of ultra high energy neutrinos.
The detection of acoustic signals from ultra-high energy neutrino interactions is a promising method to measure the flux of cosmogenic neutrinos expected on Earth. The energy threshold for this process depends strongly on the absolute noise level in the target material. The South Pole Acoustic Test Setup (SPATS), deployed in the upper part of four boreholes of the IceCube Neutrino Observatory, has monitored the noise in Antarctic ice at the geographic South Pole for more than two years down to 500
m depth. The noise is very stable and Gaussian distributed. Lacking an in situ calibration up to now, laboratory measurements have been used to estimate the absolute noise level in the 10–50
kHz frequency range to be smaller than 20
mPa. Using a threshold trigger, sensors of the South Pole Acoustic Test Setup registered acoustic events in the IceCube detector volume and its vicinity. Acoustic signals from refreezing IceCube holes and from anthropogenic sources have been used to test the localization of acoustic events. An upper limit on the neutrino flux at energies
E
ν
>
10
11
GeV is derived from acoustic data taken over eight months.
We have measured the speed of both pressure waves and shear waves as a function of depth between 80 and 500
m depth in South Pole ice with better than 1% precision. The measurements were made using ...the South Pole Acoustic Test Setup (SPATS), an array of transmitters and sensors deployed in the ice at the South Pole in order to measure the acoustic properties relevant to acoustic detection of astrophysical neutrinos. The transmitters and sensors use piezoceramics operating at ∼5–25
kHz. Between 200
m and 500
m depth, the measured profile is consistent with zero variation of the sound speed with depth, resulting in zero refraction, for both pressure and shear waves. We also performed a complementary study featuring an explosive signal propagating vertically from 50 to 2250
m depth, from which we determined a value for the pressure wave speed consistent with that determined for shallower depths, higher frequencies, and horizontal propagation with the SPATS sensors. The sound speed profile presented here can be used to achieve good acoustic source position and emission time reconstruction in general, and neutrino direction and energy reconstruction in particular. The reconstructed quantities could also help separate neutrino signals from background.
A search for an excess of muon–neutrinos from neutralino annihilations in the Sun has been performed with the AMANDA-II neutrino detector using data collected in 143.7 days of live-time in 2001. No ...excess over the expected atmospheric neutrino background has been observed. An upper limit at 90% confidence level has been obtained on the annihilation rate of captured neutralinos in the Sun, as well as the corresponding muon flux limit at the Earth, both as functions of the neutralino mass in the range 100–5000
GeV.
The AMANDA neutrino telescope has measured the spectrum of atmospheric neutrinos up to 100 TeV and IceCube, which has about 100 times higher acceptance, is expected to collect unprecedented ...statistics at even higher energies in the near future. IceCube, with 22 strings, has measured about 1.4 kHz of muon rate at trigger level and about 20 neutrino events per day at cut levels suitable for reducing the atmospheric muon content at the level of less than 10%. At energies of about 100 TeV we expect about 1 event per day for atmospheric muons with zenith angle larger than 70 degrees. With these numbers an amount of interesting physics items can be covered, such as investigations of hadronic models in region not covered by colliders, with particular attention to kaon and charm meson and barion physics. In the poster we have shown some of the MC tests we have been performing. As a summary here we show 2 preliminary plots: the one on the left shows what we obtain for CORSIKA using two different hadronic models (SIBYLL and 2 versions of QGSJET) as the fraction of pions and kaons contributing to the production of muons and neutrinos as a function of energy (integrated over all angles); the other shows how these models compare to the muon charge ratio measured by MINOS (P. Adamson et al., Phys. Rev D 76 (2007) 052003) and L3 COSMIC (M. Aglietta et al., Phys. Rev. D 58 (1998) 092005). Other results concerning the introduction of DPMJET with charm production in CORSIKA have been published in Berghaus et al., JCAP06 (2008) 003.
Observations of the shell-type supernova remnant SN1006 have been carried out with the HESS system of Cherenkov telescopes during 2003 (18.2 h with two operating telescopes) and 2004 (6.3 h with all ...four telescopes). No evidence for TeV γ-ray emission from any compact or extended region associated with the remnant is seen and resulting upper limits at the 99.9% confidence level are up to a factor 10 lower than previously-published fluxes from CANGAROO. For SN1006 at its current epoch of evolution we define limits for a number of important global parameters. Upper limits on the γ-ray luminosity (for E = 0.26 to 10 TeV, distance d = 2 kpc) of $L_\gamma < 1.7$ $\times$ 1033 erg s-1, and the total energy in corresponding accelerated protons, $W_{\rm p}<1.6$ $\times$ 1050 erg are estimated (for proton energies $E_{\rm p} \sim 1.5$ to 60 TeV and assuming the lowest value $n=0.05$ cm-3 of the ambient target density discussed in literature). Extending this estimate to cover the range of proton energies observed in the cosmic ray spectrum up to the knee (we take here $E_{\rm p} \sim$ 1 GeV to 3 PeV, assuming a differential particle index -2) gives $W_{\rm p}<6.3$ $\times$ 1050 erg. A lower limit on the post-shock magnetic field of $B>25~\mu$G results when considering the synchrotron/inverse-Compton framework for the observed X-ray flux and γ-ray upper limits.
The mass composition of high energy cosmic rays depends on their production, acceleration, and propagation. The study of cosmic ray composition can therefore reveal hints of the origin of these ...particles. At the South Pole, the IceCube Neutrino Observatory is capable of measuring two components of cosmic ray air showers in coincidence: the electromagnetic component at high altitude (2835 m) using the IceTop surface array, and the muonic component above similar to 1 TeV using the IceCube array. This unique detector arrangement provides an opportunity for precision measurements of the cosmic ray energy spectrum and composition in the region of the knee and beyond. We present the results of a neural network analysis technique to study the cosmic ray composition and the energy spectrum from 1 PeV to 30 PeV using data recorded using the 40-string/40-station configuration of the IceCube Neutrino Observatory.
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