An improved method for measuring muon energy using the truncated mean of dE/dx

The measurement of muon energy is critical for many analyses in large Cherenkov detectors, particularly those that involve separating extraterrestrial neutrinos from the atmospheric neutrino background. Muon energy has traditionally been determined by measuring the specific energy loss (dE/dx) along the muon's path and relating the dE/dx to the muon energy. Because high-energy muons (E_mu > 1 TeV) lose energy randomly, the spread in dE/dx values is quite large, leading to a typical energy resolution of 0.29 in log10(E_mu) for a muon observed over a 1 km path length in the IceCube detector. In this paper, we present an improved method that uses a truncated mean and other techniques to determine the muon energy. The muon track is divided into separate segments with individual dE/dx values. The elimination of segments with the highest dE/dx results in an overall dE/dx that is more closely correlated to the muon energy. This method results in an energy resolution of 0.22 in log10(E_mu), which gives a 26% improvement. This technique is applicable to any large water or ice detector and potentially to large scintillator or liquid argon detectors.Comment: 12 pages, 16 figure

All-particle cosmic ray energy spectrum measured with 26 IceTop stations

We report on a measurement of the cosmic ray energy spectrum with the IceTop air shower array, the surface component of the IceCube Neutrino Observatory at the South Pole. The data used in this analysis were taken between June and October, 2007, with 26 surface stations operational at that time, corresponding to about one third of the final array. The fiducial area used in this analysis was 0.122 km^2. The analysis investigated the energy spectrum from 1 to 100 PeV measured for three different zenith angle ranges between 0{\deg} and 46{\deg}. Because of the isotropy of cosmic rays in this energy range the spectra from all zenith angle intervals have to agree. The cosmic-ray energy spectrum was determined under different assumptions on the primary mass composition. Good agreement of spectra in the three zenith angle ranges was found for the assumption of pure proton and a simple two-component model. For zenith angles {\theta} < 30{\deg}, where the mass dependence is smallest, the knee in the cosmic ray energy spectrum was observed between 3.5 and 4.32 PeV, depending on composition assumption. Spectral indices above the knee range from -3.08 to -3.11 depending on primary mass composition assumption. Moreover, an indication of a flattening of the spectrum above 22 PeV were observed.Comment: 38 pages, 17 figure

Level of vitamin 25 (OH) D and B group vitamins and functional efficiency among the chronically ill elderly in domiciliary care - a pilot study

Introduction and objective. Deficits of vitamin resources constitute a significant public health problem, especially among the elderly population. The aim of the research was to determine the level of vitamin 25 (OH) D and vitamins from group B in the chronically ill elderly in domiciliary care, depending on functional capacity and coexisting diseases. Materials and method. The pilot study included 137 patients staying in long-term domiciliary care. Samples of the participants’ venous blood was obtained for laboratory tests. Centrifuged serum was used to determine the level of the following biochemical parameters: vitamin 25 (OH)D, B12, folic acid and total protein, albumin, triglycerides, total cholesterol and HDL cholesterol. Assessment of the functional status of patients was made by using the Barthel scale. Results. More than 3⁄4 of the patients with functional deficit (according to Barthel’s score 0–85 points) were deficient in vitamin 25 (OH)D, while folic acid values were below the reference values in more than half of the patients. Respondents with lower functional efficiency were characterised by a reduced average value of vitamin 25 (OH)D and folic acid. Conclusions. The studied group of the chronically ill elderly was characterised by a deficiency of vitamin D3 and folic acid. Subjects with a functional impairment deficit show a reduced mean value of vitamin 25 (OH)D and folic acid in the blood serum, compared to the group of patients with higher mobility