119219876
Production of a gadolinium-loaded liquid scintillator for the Daya Bay reactor neutrino experiment
We report on the production and characterization of liquid scintillators for the detection of electron antineutrinos by the Daya Bay reactor neutrino experiment. A 185 tons of gadolinium-loaded (0.1% by mass) liquid scintillator (Gd-LS) and a 200 tons of unloaded liquid scintillator (LS) were successfully produced from a linear-alkylbenzene (LAB) solvent in 6 months. The scintillator properties, the production and purification systems, and the quality assurance and control (QA/QC) procedures are described. (C) 2014 Elsevier By. All rights reserved.
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.
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.
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.
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.
119303023
Acrylic Target Vessels for a High-Precision Measurement of theta13 with the Daya Bay Antineutrino Detectors
This paper describes in detail the acrylic vessels used to encapsulate the target and gamma catcher regions in the Daya Bay experiment's first pair of antineutrino detectors. We give an overview of the design, fabrication, shipping, and installation of the acrylic vessels and their liquid overflow tanks. The acrylic quality assurance program and vessel characterization, which measures all geometric, optical, and material properties relevant to e detection at Daya Bay are summarized. This paper is the technical reference for the Daya Bay acrylic vessels and can provide guidance in the design and use of acrylic components in future neutrino or dark matter experiments.
119276160
New determination of the 13C(a, n)16O reaction rate and its influence on the s-process nucleosynthesis in AGB stars
We present a new measurement of the $\alpha$-spectroscopic factor ($S_\alpha$) and the asymptotic normalization coefficient (ANC) for the 6.356 MeV 1/2$^+$ subthreshold state of $^{17}$O through the $^{13}$C($^{11}$B, $^{7}$Li)$^{17}$O transfer reaction and we determine the $\alpha$-width of this state. This is believed to have a strong effect on the rate of the $^{13}$C($\alpha$, $n$)$^{16}$O reaction, the main neutron source for {\it slow} neutron captures (the $s$-process) in asymptotic giant branch (AGB) stars. Based on the new width we derive the astrophysical S-factor and the stellar rate of the $^{13}$C($\alpha$, $n$)$^{16}$O reaction. At a temperature of 100 MK our rate is roughly two times larger than that by \citet{cau88} and two times smaller than that recommended by the NACRE compilation. We use the new rate and different rates available in the literature as input in simulations of AGB stars to study their influence on the abundances of selected $s$-process elements and isotopic ratios. There are no changes in the final results using the different rates for the $^{13}$C($\alpha$, $n$)$^{16}$O reaction when the $^{13}$C burns completely in radiative conditions. When the $^{13}$C burns in convective conditions, as in stars of initial mass lower than $\sim$2 $M_\sun$ and in post-AGB stars, some changes are to be expected, e.g., of up to 25% for Pb in our models. These variations will have to be carefully analyzed when more accurate stellar mixing models and more precise observational constraints are available.
109049594
Production and quality control of STAR-TOF MRPC
Abstract Multi-gap resistive plate chamber (MRPC) has been adopted to construct the full barrel time-of-flight (TOF) detector for the STAR experiment at RHIC. The cylindrical TOF covers a total area of approximately 64 m 2 and uses 4032 MRPC modules. 70% of the modules were produced in Tsinghua University and the rest were fabricated in University of Science and Technology of China (USTC). In this paper, the production facilities, manufacturing procedures, quality control methods and test results for the Tsinghua MRPC modules are described.
119110057
Linear growth of entanglement entropy in holographic thermalization captured by horizon interiors and mutual information
A bstractWe study the holographic entanglement entropy in a homogeneous falling shell background, which is dual to the strongly coupled field theory following a global quench. For d=2 conformal field theories, it is known that the entropy has a linear growth regime if the scale of the entangling region is large. In addition, the growth rate approaches a constant when the scale increases. We demonstrate analytically that this behavior is directly related to the part of minimal area surface probing the interior of apparent horizons in the bulk, as well as the mutual information between two disjoint rectangular subsystems in the boundary. Furthermore, we show numerically that all the results are universal for the d=3 conformal field theory, the non-relativistic scale-invariant theory and the dual theory of Gauss-Bonnet gravity.
122167948
The specification of a multipole wiggler for CAMD
The growth of CAMD's research program over the last several years, in particular following the commissioning of a 7 T wiggler, has produced a demand for both higher beam brightness and flux density. Consequently, new insertion devices, such as a multi-pole wiggler (MPW), are being considered. A proposal has been submitted to the National Science Foundation for the funding of an MPW which would replace the existing 7 T wavelength shifter. The outline specification for this device is presented and also results of tests of modified optics for the CAMD storage ring which will be needed to accommodate the MPW. The modified optics have a reduced vertical aperture requirement of 20 mm at the location of the MPW.