162177595
Observation of Multi-TeV Gamma Rays from Mrk 421 and Search for Other BL Lac Objects with the Tibet-III Air Shower Array The Tibet
129939642
Primary proton spectrum in the knee region observed by the Tibet hybrid experiment
Proton spectrum in the knee region is obtained from the Tibet hybrid experiment consisting of the emulsion chambers and the Tibet II air shower array. The proton spectrum in the energy range > 10 15 eV shows the steepening of spectrum with power index -3.14±0.10 being 3.9σ deviation from that of direct observations below a few hundred TeV. Another estimate using a proton dominant chemical composition model also results in power index of -3.06±0.09 being 3.6σ
110395885
Analysis of Emulsion Chambers in Tibet Hybrid Experi- ment Using the Image Scanner
A hybrid experiment consisting of emulsion chambers and an air shower array was carried out by the Tibet ASγ collaboration to investigate primary proton spectrum in the knee region. A new method of automatic analysis of emulsion chamber using the image scanner was developed and applied to this experiment. In this paper, the result of analysis on emulsion chamber part in hybrid experiment is presented. It is shown sufficiently high efficiency of the γfamily detection is realized by automatic analysis both in energy and geometrical resolutions. 1. Introduction Emulsion chamber is a powerful detector for γ-rays in TeV region with high spacial and energy resolution. The Tibet ASγ collaboration [2],[3] used it with combination of burst detectors and an air shower array for the purpose of measuring the energy flow characteristics of the air shower core in investigating the proton spectrum in the knee region. The total number of X-ray films of size 40 cm × 50 cm used for 3 years experiment with area of 80 m 2 amounts to 7200 sheets. It is a huge work to analyze them by traditional method where each
124994910
Expected Event Rate of Subhundred-GeV Gamma Ray Bursts using the Tibet-III Air Shower Array with Single Particle Counting Technique
We calculate the expected event rate of subhundred-GeV gamma-ray bursts using the Tibet-III air shower array with single particle counting technique. The calculation is done under reasonable assumptions that the attenuation effect of gamma rays in the intergalactic space as well as the distributions of redshift, luminosity and emission time of GRBs.
121847945
NEUTRINO ASTRONOMY AND COSMIC RAYS AT THE SOUTH POLE: LATEST RESULTS FROM AMANDA AND PERSPECTIVES FOR ICECUBE
The AMANDA neutrino telescope has been in operation at the South Pole since 1996. The present final array configuration, operational since 2000, consists of 677 photomultiplier tubes arranged in 19 strings, buried at depths between 1500 and 2000 m in the ice. The most recent results on a multi-year search for point sources of neutrinos will be shown. The study of events triggered in coincidence with the surface array SPASE and AMANDA provided a result on cosmic ray composition. Expected improvements from IceCube/IceTop will also be discussed.
121694828
Performance of prototypes for the ALICE electromagnetic calorimeter
Abstract The performance of prototypes for the ALICE electromagnetic sampling calorimeter has been studied in test beam measurements at FNAL and CERN. A 4 × 4 array of final design modules showed an energy resolution of about 11 % / E ( GeV ) ⊕ 1.7 % with a uniformity of the response to electrons of 1% and a good linearity in the energy range from 10 to 100 GeV. The electromagnetic shower position resolution was found to be described by 1.5 mm ⊕ 5.3 mm / E ( GeV ) . For an electron identification efficiency of 90% a hadron rejection factor of > 600 was obtained.
15131624
First-order attractor flow equations for supersymmetric black rings in N = 2, D = 5 supergravity
In this paper we investigate the attractor mechanism in the five dimensional low energy supergravity theory corresponding to M-theory compactified on a Calabi-Yau threefold CY3. Using very special geometry, we derive the general first-order attractor flow equations for BPS and non-BPS solutions in five-dimensional Gibbons-Hawking spaces. Especially, considering the supersymmetric solution, we obtain the first-order flow equations for supersymmetric (multi)black rings. We also solve the flow equations and discuss some properties of the solutions of flow equations.
108590046
Hierarchical trigger of the ALICE calorimeters
Abstract The trigger of the ALICE electromagnetic calorimeters is implemented in 2 hierarchically connected layers of electronics. In the lower layer, level-0 algorithms search shower energy above threshold in locally confined Trigger Region Units (TRU). The top layer is implemented as a single, global trigger unit that receives the trigger data from all TRUs as input to the level-1 algorithm. This architecture was first developed for the PHOS high p T photon trigger before it was adopted by EMCal also for the jet trigger. TRU units digitize up to 112 analogue input signals from the Front End Electronics (FEE) and concentrate their digital stream in a single FPGA. A charge and time summing algorithm is combined with a peakfinder that suppresses spurious noise and is precise to single LHC bunches. With a peak-to-peak noise level of 150 MeV the linear dynamic range above threshold spans from MIP energies at 215 up to 50 GeV. Local level-0 decisions take less than 600 ns after LHC collisions, upon which all TRUs transfer their level-0 trigger data to the upstream global trigger module which searches within the remaining level-1 latency for high p T gamma showers (PHOS) and/or for Jet cone areas (EMCaL).
14484648
A possible disk mechanism for the 23-day QPO in Mkn 501
Optically, thin two-temperature accretion flows may be thermally and viscously stable, but acoustically unstable. Here, we propose that the O-mode instability of a cooling-dominated optically thin two-temperature inner disk may explain the 23-day quasi-periodic oscillation (QPO) period observed in the TeV and X-ray light curves of Mkn 501 during its 1997 high state. In our model the relativistic jet electrons Compton upscatter the disk soft X-ray photons to TeV energies, so that the instability-driven X-ray periodicity will lead to a corresponding quasi-periodicity in the TeV light curve and produce correlated variability. We analyse the dependence of the instability-driven quasi-periodicity on the mass ( M ) of the central black hole, the accretion rate ( M ˙ ) and the viscous parameter ( α ) of the inner disk. We show that in the case of Mkn 501 the first two parameters are constrained by various observational results, so that for the instability occurring within a two-temperature disk where α  = 0.05–1.0, the quasi-period is expected to lie within the range of 8–100 days, as indeed the case. In particular, for the observed 23-day QPO period our model implies a viscosity coefficient α  ⩽ 0.28, a sub-Eddington accretion rate M ˙ ≃ 0.02 M ˙ Edd and a transition radius to the outer standard disk of r 0  ∼ 60 r g , and predicts a period variation δ P / P  ∼ 0.23 due to the motion of the instability region.