The amplitude calibration of the TUNKA radio extension (Tunka-Rex)

Tunka-Rex is an experiment for the radio detection of cosmic-ray air showers in Siberia. It consists of 25 radio antennas, distributed over an area of 1 km2. It is co-located with Tunka-133, an air-Cherenkov detector for cosmic-ray air showers. Triggered by Tunka-133, Tunka-Rex records the radio signal, emitted by air showers with energies above 1017 eV. Its goal is to probe the capabilities of a radio detector, especially for the determination of the energy and elemental composition of cosmic ray primaries. To compare the measurements of Tunka-Rex to other radio detectors or to models describing the radio emission, the radio signal in each station has to be reconstructed in terms of physical units. Therefore, all hardware components have to be calibrated. We show how the calibration is performed and compare it to simulations

The level of blood plasma mitochondrial DNA upon acute myocardium damage in experiment

The aim of the present investigation is to study the level of plasma mtDNA as a potential marker of cardiomyocyte damage in 2 and 4 h after subcutaneous injection of adrenaline and during the formed morphological alterations of the myocardium (3 days). Methods. Real time PCR. Male Wistar rats were used as the experimental animals. Results. It was shown that during the increase in the activity of cytolysis biomarkers, at the first hours after adrenaline injection, no reliable increase is observed in the level of free circulating blood mtDNA. A tendency of 2.5-fold increase in this parameter was established at the third day after adrenaline injection during the development of acute inflammatory process in the myocardium. On the whole, further researches are needed on the dynamics of mtDNA level upon acute damage of the myocardium in experimental and clinical investigations for unbiased estimation of the prospects of using the parameter in laboratory diagnostics. Keywords: mitochondrial DNA, cardiovascular diseases, adrenaline myocarditis, cytolysis biomarkers.Цель. Изучить уровень мтДНК плазмы крови как возможного маркера повреждений кардиомиоцитов через 2 и 4 ч после подкожной инъекции адреналина и на фоне сформированных морфологических изменений миокарда (3-и сут). Методы. Полимеразная цепная реакция в реальном времени. В экспериментах использовали самцов крыс линии Вистар. Результаты. Показано, что наряду с увеличением активности биомаркеров цитолиза в первые часы после введения адреналина значимого повышения уровня свободно циркулирующей мтДНК крови не происходит. Установлена тенденция к 2,5-кратному возрастанию данного показателя на 3-и сут после инъекции адреналина на фоне развития острого воспалительного процесса в миокарде. Выводы. В целом для объективной оценки перспектив этого показателя в лабораторной диагностике инфаркта миокарда необходимо дальнейшее изучение динамики уровня мтДНК при острых повреждениях миокарда в экспериментальных и клинических исследованиях. Ключевые слова: митохондриальная ДНК, сердечно-сосудистые заболевания, адреналиновый миокардит, биомаркеры цитолиза.Мета. Вивчити рівень мтДНК плазми крові як можливого маркера пошкоджень кардіоміоцитиів через 2 і 4 год після підшкірної ін’єкції адреналіну та на фоні сформованих морфологічних змін міокарда (3-тя доба). Методи. Полімеразна ланцюгова реакція у реальному часі. В експериментах використано самців щурів лінії Вістар. Результати. Показано, що поряд із збільшенням активності біомаркерів цитолізу в перші години після введення адреналіну суттєвого підвищення рівня вільно циркулюючої мтДНК крові не відбувається. Встановлено тенденцію до 2,5-разового зростання даного показника на 3-тю добу після ін’кції адреналіну на фоні розвитку гострого запального процесу в міокарді. Висновки. У цілому для об’єктивної оцінки перспектив цього показника у лабораторній діагностиці інфаркта міокарда необхідно подальше вивчення динаміки рівня мтДНК при гострих ураженнях міокарда в експериментальних і клінічних дослідженнях. Ключові слова: мітохондріальна ДНК, серцево-судинні захворювання, адреналіновий міокардит, біомаркери цитолізу

Spin asymmetry A_1^d and the spin-dependent structure function g_1^d of the deuteron at low values of x and Q^2

We present a precise measurement of the deuteron longitudinal spin asymmetry A_1^d and of the deuteron spin-dependent structure function g_1^d at Q^2 < 1 GeV^2 and 4*10^-5 < x < 2.5*10^-2 based on the data collected by the COMPASS experiment at CERN during the years 2002 and 2003. The statistical precision is tenfold better than that of the previous measurement in this region. The measured A_1^d and g_1^d are found to be consistent with zero in the whole range of x.Comment: 17 pages, 10 figure

Gluon polarization in the nucleon from quasi-real photoproduction of high-pT hadron pairs

We present a determination of the gluon polarization Delta G/G in the nucleon, based on the helicity asymmetry of quasi-real photoproduction events, Q^2<1(GeV/c)^2, with a pair of large transverse-momentum hadrons in the final state. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarized muon beam scattered on a polarized 6-LiD target. The helicity asymmetry for the selected events is = 0.002 +- 0.019(stat.) +- 0.003(syst.). From this value, we obtain in a leading-order QCD analysis Delta G/G=0.024 +- 0.089(stat.) +- 0.057(syst.) at x_g = 0.095 and mu^2 =~ 3 (GeV}/c)^2.Comment: 10 pages, 3 figure

The Deuteron Spin-dependent Structure Function g1d and its First Moment

We present a measurement of the deuteron spin-dependent structure function g1d based on the data collected by the COMPASS experiment at CERN during the years 2002-2004. The data provide an accurate evaluation for Gamma_1^d, the first moment of g1d(x), and for the matrix element of the singlet axial current, a0. The results of QCD fits in the next to leading order (NLO) on all g1 deep inelastic scattering data are also presented. They provide two solutions with the gluon spin distribution function Delta G positive or negative, which describe the data equally well. In both cases, at Q^2 = 3 (GeV/c)^2 the first moment of Delta G is found to be of the order of 0.2 - 0.3 in absolute value.Comment: fits redone using MRST2004 instead of MRSV1998 for G(x), correlation matrix adde

A new measurement of the Collins and Sivers asymmetries on a transversely polarised deuteron target

New high precision measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarised 6LiD target are presented. The data were taken in 2003 and 2004 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. Both the Collins and Sivers asymmetries turn out to be compatible with zero, within the present statistical errors, which are more than a factor of 2 smaller than those of the published COMPASS results from the 2002 data. The final results from the 2002, 2003 and 2004 runs are compared with naive expectations and with existing model calculations.Comment: 40 pages, 28 figure

Measurement of the Spin Structure of the Deuteron in the DIS Region

We present a new measurement of the longitudinal spin asymmetry A_1^d and the spin-dependent structure function g_1^d of the deuteron in the range 1 GeV^2 < Q^2 < 100 GeV^2 and 0.004< x <0.7. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarised muon beam and a large polarised 6-LiD target. The results are in agreement with those from previous experiments and improve considerably the statistical accuracy in the region 0.004 < x < 0.03.Comment: 10 pages, 6 figures, subm. to PLB, revised: author list, Fig. 4, details adde

The COMPASS Experiment at CERN

The COMPASS experiment makes use of the CERN SPS high-intensitymuon and hadron beams for the investigation of the nucleon spin structure and the spectroscopy of hadrons. One or more outgoing particles are detected in coincidence with the incoming muon or hadron. A large polarized target inside a superconducting solenoid is used for the measurements with the muon beam. Outgoing particles are detected by a two-stage, large angle and large momentum range spectrometer. The setup is built using several types of tracking detectors, according to the expected incident rate, required space resolution and the solid angle to be covered. Particle identification is achieved using a RICH counter and both hadron and electromagnetic calorimeters. The setup has been successfully operated from 2002 onwards using a muon beam. Data with a hadron beam were also collected in 2004. This article describes the main features and performances of the spectrometer in 2004; a short summary of the 2006 upgrade is also given.Comment: 84 papes, 74 figure

Radio measurements of the energy and the depth of the shower maximum of cosmic-ray air showers by Tunka-Rex

We reconstructed the energy and the position of the shower maximum of air showers with energies E & 100PeV applying a method using radio measurements performed with Tunka-Rex. An event-to-event comparison to air-Cherenkov measurements of the same air showers with the Tunka-133 photomultiplier array confirms that the radio reconstruction works reliably. The Tunka-Rex reconstruction methods and absolute scales have been tuned on CoREAS simulations and yield energy and Xmax values consistent with the Tunka-133 measurements. The results of two independent measurement seasons agree within statistical uncertainties, which gives additional confidence in the radio reconstruction. The energy precision of Tunka-Rex is comparable to the Tunka-133 precision of 15 %, and exhibits a 20% uncertainty on the absolute scale dominated by the amplitude calibration of the antennas. For Xmax, this is the first direct experimental correlation of radio measurements with a different, established method. At the moment, the Xmax resolution of Tunka-Rex is approximately 40 g/cm2. This resolution can probably be improved by deploying additional antennas and by further development of the reconstruction methods, since the present analysis does not yet reveal any principle limitations