122755192
A large underground water Cherenkov muon detector array with the Tibet air shower array for the Gamma-ray astronomy in the 100 TeV region: Overview and physics goal
The Tibet air shower array with effective area 37,000 m 2 located at 4300m in altitude, in Tibet, China, is sensitive to celestial gamma rays with energies above a few TeV. We have a plan to add a large underground muon detector array to it in order to discriminate cosmic gamma rays from cosmic-ray hadrons and to increase its sensitivity by approximately one order of magnitude to cosmic gamma rays in the 100 TeV energy region. The overview of the plan will be briefly described.
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.
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
122942175
An upper limit on cosmic-ray anti-p/p flux ratio estimated by the moon's shadow with the TIBET III air shower array
The Tibet ASγ Collaboration M. Amenomori, S. Ayabe, S.W. Cui, Danzengluobu, L.K. Ding, X.H. Ding, C.F. Feng, Z.Y. Feng, X.Y. Gao, Q.X. Geng, H.W. Guo, H.H. He, M. He, K. Hibino, N. Hotta, Haibing Hu, H.B. Hu, J. Huang, Q. Huang, H.Y. Jia, F. Kajino, K. Kasahara, Y. Katayose, K. Kawata, T. Kido, Labaciren, G.M. Le, J.Y. Li, H. Lu, S.L. Lu, X.R. Meng, K. Mizutani, J. Mu, H. Nanjo, M. Nishizawa, M. Ohnishi, I. Ohta, T. Ouchi, S. Ozawa, J.R. Ren, T. Saito, M. Sakata, T. Sasaki, M. Shibata, A. Shiomi, T. Shirai, H. Sugimoto, K. Taira, M. Takita, Y.H. Tan, N. Tateyama, S. Torii, H. Tsuchiya, S. Udo, T. Utsugi, B.S. Wang, H. Wang, X. Wang, Y.G. Wang, L. Xue, Y. Yamamoto, X.C. Yang, Z.H. Ye, G.C. Yu, A.F. Yuan, T. Yuda, H.M. Zhang, J.L. Zhang, N.J. Zhang, X.Y. Zhang, Y. Zhang, Zhaxisangzhu, and X.X. Zhou (1) Dept. of Phys., Hirosaki Univ., Hirosaki, Japan (2) Dept. of Phys., Saitama Univ., Saitama, Japan (3) IHEP, CAS, Beijing, China (4) Dept. of Math. and Phys., Tibet Univ., Lhasa, China (5) Dept. of Phys., Shandong Univ., Jinan, China (6) Inst. of Modern Phys., SW Jiaotong Univ., Chengdu, China (7) Dept. of Phys., Yunnan Univ., Kunming, China (8) Faculty of Eng., Kanagawa Univ., Yokohama, Japan (9) Faculty of Ed., Utsunomiya Univ., Utsunomiya, Japan (10) Dept. of Phys., Konan Univ., Kobe, Japan (11) Faculty of Systems Eng., Shibaura Inst. of Technology, Saitama, Japan (12) Dept. of Phys., Yokohama Natl. Univ., Yokohama, Japan (13) ICRR, Univ. of Tokyo, Kashiwa, Japan (14) CSSAR, CAS, Beijing, China (15) NII, Tokyo, Japan (16) Tokyo Metropolitan Coll. of Aeronautical Eng., Tokyo, Japan (17) Shonan Inst. of Technology, Fujisawa, Japan
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
110710115
Readout electronics of the ALICE photon spectrometer
The photon spectrometer (PHOS) in the ALICE experiment at LHC is a PbWO4 crystal based electromagnetic calorimeter, dedicated to measuring photons, π°'s and η's over a broad pT range from about 100 MeV/c to 100 GeV/c with the best possible energy and position resolution. The front-end electronics of the PHOS is thus required to cover a large dynamic range, to achieve a timing resolution better than ~ 2 ns in order to discriminate against 1-2 GeV/c (anti-)neutrons, and to provide high pT trigger to select rare high pT events. In this paper, we present the full PHOS readout system, including the avalanche photo-diode, the low noise charge sensitive preamplifier, the 32 channel front-end electronics card, the trigger region unit and the trigger OR module. Results from PHOS commissioning with beam particles and cosmic rays will also be presented to address the performance of the PHOS readout electronics.
18728285
A relativistic mixing-layer model for jets in low-luminosity radio galaxies
We present an analytical model for jets in Fanaroff & Riley Class I (FR I) radio galaxies, in which an initially laminar, relativistic flow is surrounded by a shear layer. We apply the appropriate conservation laws to constrain the jet parameters, starting the model where the radio emission is observed to brighten abruptly. We assume that the laminar flow fills the jet there and that pressure balance with the surroundings is maintained from that point outwards. Entrainment continuously injects new material into the jet and forms a shear layer, which contains material from both the environment and the laminar core. The shear layer expands rapidly with distance until finally the core disappears, and all of the material is mixed into the shear layer. Beyond this point, the shear layer expands in a cone and decelerates smoothly. We apply our model to the well-observed FR I source 3C 31 and show that there is a self-consistent solution. We derive the jet power, together with the variations of mass flux and entrainment rate with distance from the nucleus. The predicted variation of bulk velocity with distance in the outer parts of the jets is in good agreement with model fits to Very Large Array observations. Our prediction for the shape of the laminar core can be tested with higher-resolution imaging.
19014123
An underground cosmic-ray detector made of RPC
Owing to its high efficiency, low cost and low sensitivity to environmental gamma-rays, resistive plate chamber (RPC) is a good candidate for large area underground cosmic-ray detectors. We report in this paper such a design for the Daya Bay reactor antineutrino experiment based on calculations and simulations for the efficiency, dead space control, noise and gamma-ray backgrounds. Experimental tests are performed, and good agreements with calculations and simulations are obtained, showing that the design is appropriate.
16870406
Model-independent reconstruction of the primordial power spectrum from WMAP data
Reconstructing the shape of the primordial power spectrum in a model-independent way from cosmological data is a useful consistency check on what is usually assumed regarding early universe physics. It is also our primary window to unknown physics during the inflationary era. Using a power-law form for the primordial power spectrum Pin(k) and constraining the scalar spectral index and its running, in 2003 Peiris and coworkers found that the first-year Wilkinson Microwave Anistropy Probe (WMAP) data seem to indicate a preferred scale in Pin(k). We use two complementary methods, the wavelet band power method of Mukherjee & Wang and the top-hat binning method of Wang, Spergel, & Strauss, to reconstruct Pin(k) as a free function from cosmic microwave background (CMB) data alone (WMAP, CBI, and ACBAR), or from CMB data together with large-scale structure data (2dFGRS and PCSz). The shape of the reconstructed Pin(k) is consistent with scale invariance, although it allows some indication of a preferred scale at k~0.01 Mpc-1. While consistent with the possible evidence for a running of the scalar spectral index found by the WMAP team, our results highlight the need of more stringent and independent constraints on cosmological parameters (the Hubble constant in particular) in order to more definitively constrain deviations of Pin(k) from scale invariance without making assumptions about the inflationary model.
108773563
The silicon microstrip tracker for CMS
The CMS silicon strip tracker involves about 70 m2 of instrumented silicon, with approximately 18500 microstrip detectors read out by 5 × 106 electronics channels. It has to satisfy a set of stringent requirements imposed by the environment and by the physics expected at the LHC: low cell occupancy and good resolution, radiation hardness aided by adequate cooling, low mass combined with high stability. These conditions have been incorporated in a highly modular design of the detector modules and their support structures, chosen to facilitate construction and to allow for easy assembly and maintenance.