ABSTRACT IceTop is an air-shower array located on the Antarctic ice sheet at the geographic South Pole. IceTop can detect an astrophysical flux of neutrons from Galactic sources as an excess of ...cosmic-ray air showers arriving from the source direction. Neutrons are undeflected by the Galactic magnetic field and can typically travel 10 (E/PeV) pc before decay. Two searches are performed using 4 yr of the IceTop data set to look for a statistically significant excess of events with energies above 10 PeV (1016 eV) arriving within a small solid angle. The all-sky search method covers from −90° to approximately −50° in declination. No significant excess is found. A targeted search is also performed, looking for significant correlation with candidate sources in different target sets. This search uses a higher-energy cut (100 PeV) since most target objects lie beyond 1 kpc. The target sets include pulsars with confirmed TeV energy photon fluxes and high-mass X-ray binaries. No significant correlation is found for any target set. Flux upper limits are determined for both searches, which can constrain Galactic neutron sources and production scenarios.
The Milky Way is expected to be embedded in a halo of dark matter particles, with the highest density in the central region, and decreasing density with the halo-centric radius. Dark matter might be ...indirectly detectable at Earth through a flux of stable particles generated in dark matter annihilations and peaked in the direction of the Galactic Center. We present a search for an excess flux of muon (anti-) neutrinos from dark matter annihilation in the Galactic Center using the cubic-kilometer-sized IceCube neutrino detector at the South Pole. There, the Galactic Center is always seen above the horizon. Thus, new and dedicated veto techniques against atmospheric muons are required to make the southern hemisphere accessible for IceCube. We used 319.7 live-days of data from IceCube operating in its 79-string configuration during 2010 and 2011. No neutrino excess was found and the final result is compatible with the background. We present upper limits on the self-annihilation cross-section,
σ
A
v
, for WIMP masses ranging from 30 GeV up to 10 TeV, assuming cuspy (NFW) and flat-cored (Burkert) dark matter halo profiles, reaching down to
≃
4
·
10
-
24
cm
3
s
-
1
, and
≃
2.6
·
10
-
23
cm
3
s
-
1
for the
ν
ν
¯
channel, respectively.
We present the results of the first IceCube search for dark matter annihilation in the center of the Earth. Weakly interacting massive particles (WIMPs), candidates for dark matter, can scatter off ...nuclei inside the Earth and fall below its escape velocity. Over time the captured WIMPs will be accumulated and may eventually self-annihilate. Among the annihilation products only neutrinos can escape from the center of the Earth. Large-scale neutrino telescopes, such as the cubic kilometer IceCube Neutrino Observatory located at the South Pole, can be used to search for such neutrino fluxes. Data from 327 days of detector livetime during 2011/2012 were analyzed. No excess beyond the expected background from atmospheric neutrinos was detected. The derived upper limits on the annihilation rate of WIMPs in the Earth and the resulting muon flux are an order of magnitude stronger than the limits of the last analysis performed with data from IceCube’s predecessor AMANDA. The limits can be translated in terms of a spin-independent WIMP–nucleon cross section. For a WIMP mass of 50 GeV this analysis results in the most restrictive limits achieved with IceCube data.
Aims To evaluate acute and long-term symptomatic, haemodynamic (at rest and during exercise) and electrophysiological results of transcoronary ablation of septal hypertrophy (TASH), a catheter ...interventional treatment for hypertrophic obstructive cardiomyopathy. Methods and Results Sixty-two transcoronary ablations of septal hypertrophy were performed by injection of 4·6±2·6ml 96% ethanol into septal branches in 50 patients with hypertrophic obstructive cardiomyopathy and severe symptoms. Serial left and right heart catheterization, transoesophageal echocardiography and electrophysiological investigations were repeated 2 weeks and 7±1 months (n=37) after intervention. Transcoronary ablation of septal hypertrophy led to a reduction in septal thickness, sustained elimination of the outflow obstruction (51±41 vs 6±10mmHg at rest, P<0·001; 134±48 vs 28±32mmHg, P<0·001, post-extrasystolic), a decrease in left ventricular filling pressures at rest and during exercise and a pronounced clinical improvement. There was no evidence for the creation of an arrhythmogenic substrate as assessed by serial programmed electrical stimulation in 39 patients. However, permanent high-grade atrioventricular block occurred in 17% of the patients. There were two early, but no late deaths during a mean follow-up time of 10·6±5·6 months. Conclusion Transcoronary ablation of septal hypertrophy is a promising new treatment for hypertrophic obstructive cardiomyopathy in patients with severe symptoms. It should now be compared with alternative treatment strategies in prospective randomized studies.
PDF
