120264451
A search for flaring very-high-energy cosmic gamma-ray sources with the L3+C muon spectrometer
The L3+C muon detector at the CERN electron-positron collider, LEP, is used for the detection of very-high-energy cosmic gamma-ray sources through the observation of muons of energies above 20, 30, 50 and 100 GeV. Daily or monthly excesses in the rate of single-muon events pointing to some particular direction in the sky are searched for. The periods from mid July to November 1999, and April to November 2000 are considered. Special attention is also given to a selection of known gamma-ray sources. No statistically significant excess is observed for any direction or any particular source. (c) 2006 Elsevier B.V. All rights reserved.
19719907
Trigger System of BESIII
The trigger system of Beijing Spectrometer III, part of the upgrade of Beijing Electron Positron Collider, has been designed and implemented, and is ready for installation. This paper describes briefly the system components, its characteristics, and some technical issues. The system consists mainly of four parts: MDC (drift chamber) tracking subsystem, EMC (electromagnetic calorimeter) subsystem, TOF (time of flight) subsystem and global trigger. Some highlights in designing of this system includes: trigger scheme optimization with software simulation; optical transmission between trigger and FEEs to realize isolation with FEEs to avoid ground loop current interference; designed with most latest FPGA (Xilinx Spartan 3, VirtexII Pro...) for simplicity, high reliability and easy maintenance and hence smaller system; FPGA in-system programming or firmware online downloadable via onboard, panel connector and/or VME bus for modification flexibility during commissioning. Different from the usual fix delay data transmission from FEE to trigger, the RocketIO has been used as SEDES.
182722222
First Level Trigger in the GEM Muon System
126253177
Experimental measurement of the mass of the tau lepton at the Beijing Electron Positron Collider (BEPC)
125302092
Measurements of the line shapes of D anti-D production and the ratio of the production rates of D+ D- and D0 anti-D0 in e+ e- annihilation at psi(3770) resonance
Abstract We report measurements of the line shapes of D + D − , D 0 D ¯ 0 and D D ¯ production as well as the line shape of the ratio of the production rates of D + D − and D 0 D ¯ 0 in e + e − annihilation at ψ ( 3770 ) resonance. We find that the line shapes of D + D − , D 0 D ¯ 0 and D D ¯ production are similar to an anomalous line shape of cross sections for e + e − → hadrons observed in the center-of-mass energy range from 3.70 to 3.87 GeV.
126124755
Measurement of the internal spin structure of the proton
Our final results of measurements at SLAC of the spin dependent asymmetry in the deep inelastic scattering of longitudinally polarized electrons by longitudinally polarized protons are presented. Data were obtained at a scattering angle of 10° and for incident energies of 16.2 and 22.7 GeV, which cover the kinematic range 0.18<x<0.70 and 3.5<Q2<10.0 (GeV/c)2. We compare our results with various models of proton spin structure and with the Bjorken and Ellis‐Jaffe sum rules.
119288954
Rigidity of SU(2, 2|2)-symmetric solutions in Type IIB
We investigate the existence of half-BPS solutions in Type IIB supergravity which are invariant under the superalgebra SU(2, 2|2) realized on either AdS5 × S2 × S1 or AdS5 × S3 warped over a Riemann surface Σ with boundary. We prove that, in both cases, the only solution is AdS5 × S5 itself. We argue that this result provides evidence for the non-existence of fully back-reacted intersecting D3/D7 branes with either AdS5 × S2 × S1 × Σ or AdS5 × S3 × Σ near-horizon limits.
119348940
Detecting the dark matter annihilation at the ground EAS detectors
Abstract In this paper we study the possibility of detecting gamma rays from dark matter annihilation in the subhalos of the Milky Way by the ground based EAS detectors within the frame of the minimal supersymmetric Standard Model. Based on the Monte Carlo simulation we also study the properties of two specific EAS detectors, the ARGO and HAWC, and the sensitivities of these detectors on the detection of dark matter annihilation. We find the ground EAS detectors have the possibility to observe such signals. Conversely if no signal observed we give the constraints on the supersymmetric parameter space, which however depends on the subhalos properties.
118646643
A hybrid model of GeV-TeV gamma ray emission from the Galactic center
The observations of high energy gamma-ray emission from the Galactic center (GC) by HESS, and recently by Fermi, suggest cosmic ray acceleration in the GC and possibly around the supermassive black hole. In this work we propose a lepton-hadron hybrid model to simultaneously explain the GeV-TeV gamma-ray emission. Both electrons and hadronic cosmic rays were accelerated during the previous activity of the GC. These particles would then diffuse outwards and interact with the interstellar gas and background radiation field. The collisions between hadronic cosmic rays with gas are responsible for the TeV gamma-ray emission detected by HESS. With fast cooling in the strong radiation field, the electrons would cool down and radiate GeV photons through inverse Compton scattering off the soft background photons. This scenario provides a natural explanation for the observed GeV-TeV spectral shape of gamma-ray.
122785773
XYZ physics at BESIII
In this talk, we present the recent study on the charmonium-like states from the BESIII Collaboration based on large data samples above D ¯ D threshold. The observation of X(3872) from the Y(4260) radiative transition, the study of the Y states from the e + e − → π + π − hc process, and the observation of the charged Zc states are included .
145909018
Highlights from the ARGO-YBJ experiment
— The ARGO-YBJ experiment is a multipurpose detector exploiting the full coverage approach at very high altitude. The apparatus, in stable data taking since November 2007 with an energy threshold of a few hundreds of GeV and a duty-cycle > 85%, is located at the YangBaJing Cosmic Ray Laboratory (Tibet, P.R. China, 4300 m a.s.l., 606 g/cm). A number of interesting results are available in cosmic ray physics and in gamma-ray astronomy after the first 3 years of stable data taking. In this paper gamma-ray astronomy results are summarized.