121830268
Neutrino Detectors: Present and Future
Abstract Detectors for neutrino intrinsic property measurements and neutrino oscillations are reviewed, with special emphasis on the future trends. Examples include semiconductor and microwave detectors for the absolute mass and magnetic moment of neutrinos, water Cherenkov, liquid Argon TPC, liquid scintillator and sampling detectors for neutrino oscillations. Technologies experienced significant progress in the past and major advances are planned for the future.
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.
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.
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.
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.
125677069
TUBE CHAMBERS FOR THE MUON FILTER OF THE L3 DETECTOR
120815101
Front-end electronics of the ALICE photon spectrometer
Abstract The photon spectrometer (PHOS) in the ALICE experiment at LHC is dedicated to measuring photons, π 0 's and η 's in a broad p T range from about 100 MeV/ c to 100 GeV/ c , providing the best possible energy and position resolution in order to narrow the π 0 and η mass peaks and thus to increase the signal to background ratio. The front-end electronics (FEE) of the PHOS is thus required to cover a large dynamic range, to have a timing resolution better than ∼ 2 ns in order to discriminate against 1–2 GeV/ c (anti-)neutrons, and to provide high p T trigger to select rare high p T events. In addition, to equalize the gains of individual detector channels, it is desired that the PHOS FEE can regulate the bias voltage of APD. In this paper, we will present the performance and status of the 32-channel low noise front-end electronics for the PHOS with a dynamic range of 14 bits. Measurements with LED pulse at laboratory and results from beam test with the first PHOS module at T10 of the CERN PS show that its performance fulfills the PHOS requirements.
118677216
CMB Temperature and Matter Power Spectrum in a Decay Vacuum Dark Energy Model
In this paper, a decay vacuum model $\bar{\rho}_\Lambda=3\sigma M_p^2H_0 H$ is revisited by detailed analysis of background evolution and perturbation equations. We show the imprints on CMB temperature and matter power spectrum from the effective coupling terms between dark sectors by comparing to the standard cosmological constant model and observational data points (WMAP7 and SDSS DR7). We find that the decay vacuum model can describe the expansion rate at late times as well as the standard cosmological constant model but it fails to simultaneously reproduce the observed CMB and matter power spectrum. Its generalization $\bar{\rho}_\Lambda=3M_p^2(\xi_1 H_0 H+\xi_2 H^2)$ is also discussed. Detailed analysis of the background evolution shows that the dimensionless parameter $\xi_{2}$ would be zero to avoid the unnatural 'fine tuning' and to keep the positivity of energy density of dark matter and dark energy in the early epoch.
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.
118640758
Neutrino constraints from future nearly all-sky spectroscopic galaxy surveys
We examine whether future, nearly all-sky galaxy redshift surveys, in combination with CMB priors, will be able to detect the signature of the cosmic neutrino background and determine the absolute neutrino mass scale. We also consider what constraints can be imposed on the effective number of neutrino species. In particular we consider two spectroscopic strategies in the near-IR, the so-called ``slitless'' and ``multi-slit'' approaches, whose examples are given by future space-based galaxy surveys, as EUCLID for the slitless case, or SPACE, JEDI, and possibly WFIRST in the future, for the multi-slit case. We find that, in combination with Planck, these galaxy probes will be able to detect at better than 3-sigma level and measure the mass of cosmic neutrinos: a) in a cosmology-independent way, if the sum of neutrino masses is above 0.1 eV; b) assuming spatial flatness and that dark energy is a cosmological constant, otherwise. We find that the sensitivity of such surveys is well suited to span the entire range of neutrino masses allowed by neutrino oscillation experiments, and to yield a clear detection of non-zero neutrino mass. The detection of the cosmic relic neutrino background with cosmological experiments will be a spectacular confirmation of our model for the early Universe and a window into one of the oldest relic components of our Universe.
847741
Robust Dark Energy Constraints from Supernovae, Galaxy Clustering, and 3 yr Wilkinson Microwave Anisotropy Probe Observations
Type Ia supernova (SN Ia), galaxy clustering, and cosmic microwave background (CMB) anisotropy data provide complementary constraints on the nature of the dark energy in the universe. We find that the 3 yr Wilkinson Microwave Anisotropy Probe (WMAP) observations give a CMB shift parameter of R ≡ 1/2 dz'/H(z') = 1.70 ± 0.03. Using this new measured value of the CMB shift parameter, together with the baryon acoustic oscillation (BAO) measurement from the Sloan Digital Sky Survey (SDSS), and SN Ia data from the HST/GOODS program and the first-year Supernova Legacy Survey, we derive model-independent constraints on the dark energy density ρX(z) and the cosmic expansion rate H(z). We also derive constraints on the dark energy equation of state wX(z) = w0 + w'z (with cutoff at z = 2) and wX(a) = w0 + (1 - a)wa. We find that current data provide slightly tighter constraints on ρX(z) and H(z) as free functions in redshift and roughly a factor of 2 improvement in constraining wX(z). A cosmological constant remains consistent with the data; however, uncertainties remain large for model-independent constraints of dark energy. A significant increase in the number of observed SNe Ia between redshifts of 1 and 2, complemented by improved BAO and weak-lensing cosmography measurements (as expected from the JEDI mission concept for the Joint Dark Energy Mission), will be required to dramatically tighten model-independent dark energy constraints.