119833822
The Palo Verde reactor neutrino oscillation experiment
Abstract Our collaboration is operating a segmented scintillation detector, containing 11.3 tons of 0.1% Gd loaded liquid scintillator, at 750, 888 and 889 m distance from three nuclear power reactors. Goal of the experiment is to search for neutrino oscillations in disappearance mode. The anti-neutrino capture on the proton serves as detection reaction. The experiment is expected to reach a sensitivity of Δm 2 > 1.3 · 10 −3 eV 2 and sin 2 2Θ > 0.1. Our range of sensitivity is tuned to test the ν μ ↔ ν e solution of the atmospheric neutrino anomaly as reported by the Kamiokande experiment. Assembly of the detector in an underground lab, with 32 mw.e. effective overburden, is completed. Since June 1998 we are taking data a full reactor power. Detector design and performance are discussed.
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.
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
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.
119253997
Constraints on flavor-changing neutral-current $Htq$ couplings from the signal of $tH$ associated production with QCD next-to-leading order accuracy at the LHC
We study a generic Higgs boson and a top quark associated production via model-independent flavor-changing neutral-current couplings at the LHC, including complete QCD next-to-leading order (NLO) corrections to the production and decay of the top quark and the Higgs boson. We find that QCD NLO corrections can increase the total production cross sections by about 48.9% and 57.9% for the Htu and Htc coupling induced processes at the LHC, respectively. After kinematic cuts are imposed on the decay products of the top quark and the Higgs boson, the QCD NLO corrections are reduced to 11% for the Htu coupling induced process and almost vanish for the Htc coupling induced process. Moreover, QCD NLO corrections reduce the dependence of the total cross sections on the renormalization and factorization scales. We also discuss signals of the
119270914
Quadra-Spectrum and Quint-Spectrum from Inflation and Curvaton Models
We calculate the quadra-spectrum and quint-spectrum, corresponding to five and six point correlation functions of the curvature perturbation. For single field inflation with standard kinetic term, the quadra-spectrum and quint-spectrum are small, which are suppressed by slow roll parameters. The calculation can be generalized to multiple fields. When there is no entropy perturbation, the quadra-spectrum and quint-spectrum are suppressed as well. With the presence of entropy perturbation, the quadra-spectrum and quint-spectrum can get boosted. We illustrate this boost in the multi-brid inflation model. For the curvaton scenario, the quadra-spectrum and quint-spectrum are also large in the small r limit. We also calculate representative terms of quadra-spectrum and quint-spectrum for inflation with generalized kinetic terms, and estimate their order of magnitude for quasi-single field inflation.
44852902
Test results on heavily irradiated silicon detectors for the CMS experiment at LHC
We report selected results of laboratory measurements and beam tests of heavily irradiated microstrip silicon detectors. The detectors were single-sided devices, produced by different manufacturers and irradiated with different sources, for several total ionizing doses and fluences up to 4 /spl times/10/sup 14/ 1-MeV-equivalent neutrons per cm/sup 2/. Strip resistance and capacitance, detector leakage currents and breakdown performance were measured before and after irradiations. Signal-to-noise ratio and detector efficiency were studied in beam tests, for different values of the detector temperature and of the read-out pitch, as a function of the detector bias voltage. The goal of these test is to optimise the design of the final prototypes for the Silicon Strip Tracker of the CMS experiment at the CERN LHC collider.
61057086
The BEPC control system upgraded
The upgrade of the BEPC control system has been finished one year ahead of the schedule and new system was put into use in October, 1994. The upgraded system adopts a distribution architecture based on DECnet. The workstations are used as console to replace the old hardware console, the new VAX computers carry out control jobs. Some dedicated adapters have been eliminated. Up to now, the new BEPC control system has been running safely and reliably for five months. The system upgrading is crowned success. What we have been finished is presented in this paper.
18463747
THE LIQUID SCINTILLATOR NEUTRINO DETECTOR AND LAMPF NEUTRINO SOURCE
Abstract A search for neutrino oscillations of the type ν μ → ν c has been conducted at the Los Alamos Meson Physics Facility using ν μ from muon decay at rest. Evidence for this transition has been reported previously. This paper discusses in detail the experimental setup, detector operation and neutrino source, including aspects relevant to oscillation searches in the muon decay-at-rest and pion decay in flight channels.