125539232
The beam energy measurement system for the Beijing electron-positron collider
The beam energy measurement system (BEMS) for the upgraded Beijing electron-positron collider BEPC-II is described. The system is based on measuring the energies of Compton back-scattered photons. The relative systematic uncertainty of the electron and positron beam energy determination is estimated as 2 ⋅ 10 − 5 .
118039047
Physics of tau and charm
The physics of tau and charm started in early 70's after J/$\psi$ and $\tau$ were discovered. Since then several dedicated accelerators and experiments were built with increasing luminosities and studies on light hadron spectroscopy, charmonium, electroweak and QCD were never interupted. New interests and surprises are not rare in this area. With the newly built BEPCII/BESIII, an even brighter future is foreseen.
18893994
The mass production and quality control of RPCs for the Daya Bay experiment
Abstract Resistive plate chambers will be used in the Daya Bay reactor neutrino experiment to help veto backgrounds created by cosmic-ray muons. The mass production of RPCs began in 2008 and by the end of 2009, 1600 RPCs (3500 m 2 ) had been produced and tested. This paper describes the production and quality control procedures, and quality assurance using cosmic-ray testing.
56005177
Inclusive J production in Z0 decays
Abstract Inclusive J production in Z0 decays is observed via the leptonic decay mode J → l+l− (l = e,μ). We measure the branching ratio Br(Z0 → J + X) = (4.1 ± 0.7 (stat.) ± 0.3 (sys.)) × 10−3. We have calculated the fraction of the J mesons from b-hadron decay and find a branching ratio of Br(b → J + X)= (1.3±0.2(stat.)±0.2(sys.)) × 10−2. We determine the average fractional energy of bottom hadrons 〈XE > = 0.70±0.03 (stat.)+0.02−0.01 (sys.) using the momentum spectrum of the J mesons. From a study of the angle between the J and the most energetic jet, we set an upper limit on the branching ratio Br ( Z 0 → q q g ∗ ; g ∗ → J + X ) −4 at 90% confidence level.
125677069
TUBE CHAMBERS FOR THE MUON FILTER OF THE L3 DETECTOR
122214277
A water Cherenkov calorimeter for long baseline neutrino oscillation experiments
Abstract We propose a water-based large homogeneous calorimeter as the next generation neutrino detector for ν factories and/or conventional ν beams. The Cherenkov light produced in water is sufficient to have good energy resolution, and the pattern recognition is realized by a modular water tank structure. Monte Carlo simulations show that the detector performance is excellent for identifying neutrino CC events while rejecting backgrounds.
15577836
CENTRALITY, SYSTEM SIZE AND ENERGY DEPENDENCE OF CHARGED PARTICLE PSEUDORAPIDITY DISTRIBUTION
Utilizing the three-fireball picture within the quark combination model, we study systematically the charged particle pseudorapidity distributions in both Au + Au and Cu + Cu collision systems as a function of collision centrality and energy, , 62.4, 130 and 200 GeV, in the full pseudorapidity range. We find that: (i) the contribution from leading particles to dNch/dη distributions increases with the decrease of the collision centrality and energy respectively; (ii) the number of leading particles is almost independent of the collision energy, but it does depend on the nucleon participants Npart; (iii) if Cu + Cu and Au + Au collisions at the same collision energy are selected to have the same Npart, the resulting charged particle dN/dη distributions are nearly identical, in both the midrapidity particle density and the width of the distribution; this is true for both 62.4 GeV and 200 GeV data; (iv) the limiting fragmentation phenomenon is reproduced. We predict the total multiplicity and pseudorapidity distribution for the charged particles in Pb + Pb collisions at . Finally, we give a qualitative analysis of Nch/〈Npart/2〉 and dNch/dη/〈Npart/2〉|η≈0 as a function of and Npart from the RHIC to the LHC.
118161430
Population study for gamma-ray pulsars; II Millisecond pulsars
The population of $\gamma$-ray emitting millisecond pulsars (MSPs) is studied by using Monte-Carlo techniques. We simulate the Galactic distributions of the MSPs, and apply the outer gap model for the $\gamma$-ray emission from each simulated MSP. We take into account the dependence of the observed $\gamma$-ray flux on the viewing angle and inclination angle, which is the angle between the rotation axis and the magnetic axis, respectively. Using the sensitivity of the six-month long observation of the $Fermi$ telescope and radio sensitivities of existing pulsar surveys, 9-13 radio-selected and 22-35 $\gamma$-ray-selected pulsars are detected within our simulation. The statistical properties of the simulated population are consistent with the $Fermi$ observations. Scaling the observed sensitivity $\propto \sqrt{T}$, where $T$ is the length of observation time, the present model predicts that over the 5-year mission $Fermi$ would detect 15-22 radio-selected $\gamma$-ray MSPs, and 95-152 $\gamma$-ray-selected MSPs. Our simulation also predicts that about 100 (or 200-300) $\gamma$-ray MSPs with a flux larger $F\ge 10^{-11}~\mathrm{erg/cm^2 s}$ (or $5\times 10^{-12}~\mathrm{erg/cm^2 s}$) irradiate the Earth. With the present sensitivities of the radio surveys, most of them are categorized as $\gamma$-ray-selected pulsars, indicating that most of the $\gamma$-ray MSPs have been missed by the present $Fermi$ observations. We argue that the Galactic $Fermi$ unidentified sources located at high latitudes should be dominated by MSPs, whereas the sources in the galactic plane are dominated by radio-quiet canonical pulsars.
111171338
DEVELOPMENT OF RADIO FREQUENCY GUNS AT NSRRC
Technologies for rf gun-based high brightness injector are being developed at NSRRC. An X-band photo-cathode rf gun has been constructed and operated successfully for coherent electromagnetic radiation research at U.C. Davis. Recent measurement of a 1.5-2 MeV beam from this gun with bunch charge at 25 pC showed that it has a normalized emittance at 1.65 mm-mrad. As a successive project, a 100 MeV electron beam injector system with a thermionic rf gun and a photo-cathode rf gun that share the same 2998 MHz rf linac is being designed as the pre-injector of the TPS (Taiwan Photon Source) booster as well as beam injector for novel light source research. For evaluation purposes, a prototype thermionic rf gun system is now under construction at NSRRC with the existing 2856 MHz high power microwave system as the driver source.
121984352
The BES detector
Abstract The Beijing Spectrometer (BES) is a general purpose solenoidal detector at the Beijing Electron Positron Collider (BEPC). It is designed to study exclusive final states in e + e − annihilations at the center of mass energy from 3.0 to 5.6 GeV. This requires large solid angle coverage combined with good charged particle momentum resolution, good particle identification and high photon detection efficiency at low energies. In this paper we describe the construction and the performance of BES detector.
118976776
Measurements of identified particles at intermediate transverse momentum in the STAR experiment from Au + Au collisions at s(NN)**(1/2) =200- GeV