7047502
Neutron production by cosmic-ray muons at shallow depth
The yield of neutrons produced by cosmic ray muons at a shallow depth of 32 meters of water equivalent has been measured. The Palo Verde neutrino detector, containing 11.3 tons of Gd loaded liquid scintillator and 3.5 tons of acrylic, served as a target. The rate of one and two neutron captures was determined. Modeling the neutron capture efficiency allowed us to deduce the total yield of neutrons, Ytot=(3.60±0.09±0.31)×10^-5 neutrons per muon and g/cm^2. This yield is consistent with previous measurements at similar depths.
125677069
TUBE CHAMBERS FOR THE MUON FILTER OF THE L3 DETECTOR
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.
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.
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.
219555605
Subaru high resolution spectroscopy of complex metal absorption lines of QSO HS1603+38201
We present a high resolution spectrum of the quasar, HS1603+3820 (zem=2.542), observed with the High Dispersion Spectrograph (HDS) on Subaru Telescope. This quasar, first discovered in the Hamburg/CfA Quasar Survey, has 11 C iv lines at 1.96 < zabs< 2.55. Our spectrum covers 8 of the 11 C iv lines at zabs > 2.29 and resolves some of them into multiple narrow components with b < 25 km s−1 because of the high spectral resolution R=45000, while other lines show broad profiles (b > 65 km s−1). We use three properties of C iv lines, specifically, time variability, covering factor, and absorption line profile, to classify them into quasar intrinsic absorption lines (QIALs) and spatially intervening absorption lines (SIALs). The C iv lines at 2.42 < zabs< 2.45 are classified as QIALs in spite of their large velocity shifts from the quasar. Perhaps they are produced by gas clouds ejected from the quasar with the velocity of vej = 8000 km s−1− 10000 km s−1. On the other hand, three C iv lines at 2.48 < zabs< 2.55 are classified as SIALs, which suggests there exist intervening absorbers near the quasar. We, however, cannot rule out QIALs for the two lines at zabs ∼ 2.54 and 2.55, because their velocity shifts, 430 km s−1 blueward and 950 km s−1 redward of the quasar, are very small. The C iv line at zabs ∼ 2.48 consists of many narrow components, and has also corresponding low-ionization metal lines (Al ii, Si ii, and Fe ii). The velocity distribution of these low-ionization ions is concentrated at the center of the system compared to that of high-ionization C iv ion. Therefore we ascribe this system of absorption lines to an intervening galaxy. Subject headings: quasars: absorption lines — quasars: individual (HS1603+3820)
14261978
How Sensitive Are Weak Lensing Statistics to Dark Energy Content
Future weak lensing surveys will directly probe the clustering of dark matter, in addition to providing a test for various cosmological models. Recent studies have provided us with the tools that can be used to construct the complete probability distribution function for convergence fields. It is also possible to construct the bias associated with the hot spots in convergence maps. These techniques can be used in both the quasi-linear and the highly nonlinear regimes using various well-developed numerical methods. We use the results here to study the weak lensing statistics of cosmological models with dark energy. We study how well various classes of dark energy models can be distinguished from models with a cosmological constant. We find that the ratio of the square root of the variance of convergence is complementary to the convergence skewness S3 in probing the dark energy equation of state; it can be used to predict the expected difference in weak lensing statistics between various dark energy models and for choosing optimized smoothing angles to constrain a given class of dark energy models. Our results should be useful for probing dark energy using future weak lensing data with high statistics from galaxy weak lensing surveys and supernova pencil beam surveys.
16037890
Supersymmetric black rings and non-linear sigma models
In this paper we investigate the non-linear sigma model arising in the reduction of D=5 supergravity to D=3, and present the application of this sigma model to supersymmetric black ring solutions in five-dimensional minimal supergravity. With the ansatz of stationary solutions with R×U(1)×U(1) isometry, we obtain a two-dimensional Lagrangian corresponding to geodesic motion of a string-like object on the coset G2(+2)/SO(4), and study the algebra of conserved charges and supersymmetry constraints of supersymmetric black ring.
97547510
Study of neutron generation from relativistic heavy ion interactions
Abstract Study has been carried out on neutron generation in the interactions of 44 and 18 GeV 12 C with Cu-and Pb-targets. The properties studied include, (1) Relative yields of secondary neutrons generated in 44 GeV versus in 18 GeV 12 C bombardment to Cu target and also to Pb target. The ratios of these are 2.12±0.19 and 2.04±0.15, respectively, which is nearly in consistence with but somewhat larger than the values of theoretical calculations for Cu target. (2) Relative yields of secondary neutrons produced in Pb target versus in Cu target. The ratios obtained are 2.54±0.20 and 2.56±0.20 for 44 GeV and 18 GeV, respectively. More neutrons are generated in Pb target than in Cu target.
122576647
On muon production and other leakage aspects of pion absorption in a lead/scintillating-fiber calorimeter
Abstract We report on an experimental study of longitudinal leakage phenomena in hadronic shower development. Pions in the energy range of 10–150 GeV were sent into a lead/scintillating-fiber calorimeter with a thickness of 9.6 nuclear interaction lengths. The average fraction of the energy leaking out at the back of this calorimeter ranges from 0.04% at 10 GeV to 0.4% at 150 GeV. This leakage has a very small effect on the hadronic energy resolution. We measured the probability of the creation of escaping muons in the shower development process. This probability ranges from 0.2% at 10 GeV to 2.1% at 150 GeV. Assuming that these muons are produced from π- or K-decay, we find an exponentially decaying muon spectrum with a typical momentum of 2.8 GeV/ c , at 80 GeV incident energy. Also the rates at which hadrons and soft neutrons escape from the calorimeter are measured. Within the acceptance of the leakage calorimeter, neutrons are observed about 10 times as often as muons. Escaping hadrons dominate muons for shower energies above 20 GeV. The experiments were performed at CERN in the framework of the LAA project.