89 research outputs found
Nearly Blinking-Free, High-Purity Single-Photon Emission by Colloidal InP/ZnSe Quantum Dots
Colloidal core/shell InP/ZnSe quantum dots (QDs), recently produced using an
improved synthesis method, have a great potential in life-science applications
as well as in integrated quantum photonics and quantum information processing
as single-photon emitters. Single-particle spectroscopy of 10-nm QDs with
3.2-nm cores reveals strong photon antibunching attributed to fast (70-ps)
Auger recombination of multiple excitons. The QDs exhibit very good
photostability under strong optical excitation. We demonstrate that the
antibunching is preserved when the QDs are excited above the saturation
intensity of the fundamental-exciton transition. This result paves the way
towards their usage as high-purity on-demand single-photon emitters at room
temperature. Unconventionally, despite the strong Auger blockade mechanism,
InP/ZnSe QDs also display very little luminescence intermittency ("blinking"),
with a simple on/off blinking pattern. The analysis of single-particle
luminescence statistics places these InP/ZnSe QDs in the class of nearly
blinking-free QDs, with emission stability comparable to state-of-the-art
thick-shell and alloyed-interface CdSe/CdS, but with improved single-photon
purity.Comment: 15 pages, 5 figure
Measurement of electron-neutrino electron elastic scattering
The cross section for the elastic scattering reaction nu_e+e- -> nu_e+e- was
measured by the Liquid Scintillator Neutrino Detector using a mu+ decay-at-rest
nu_e beam at the Los Alamos Neutron Science Center. The standard model of
electroweak physics predicts a large destructive interference between the
charge current and neutral current channels for this reaction. The measured
cross section, sigma_{nu_e e-}=[10.1 +- 1.1(stat.) +- 1.0(syst.)]x E_{nu_e}
(MeV) x 10^{-45} cm^2, agrees well with standard model expectations. The
measured value of the interference parameter, I=-1.01 +- 0.13(stat.) +-
0.12(syst.), is in good agreement with the standard model expectation of
I^{SM}=-1.09. Limits are placed on neutrino flavor-changing neutral currents.
An upper limit on the muon-neutrino magnetic moment of 6.8 x 10^{-10} mu_{Bohr}
is obtained using the nu_mu and \bar{nu}_mu fluxes from pi+ and mu+ decay.Comment: 22 pages, 11 figure
Evidence for Diffractive Charm Production in nu_mu Fe and nubar_mu Fe Scattering at the Tevatron
We present evidence for the diffractive processes nu_mu Fe -> mu^- D_s^+
(D_s^*+) Fe and nubar_mu Fe -> mu^+ D_s^- (D_s^*-) Fe using the Fermilab SSQT
neutrino beam and the Lab E neutrino detector. We observe the neutrino trident
reactions nu_mu Fe -> nu_mu mu^- mu^+ Fe and nubar_mu Fe -> nubar_mu mu^+ mu^-
Fe at rates consistent with Standard Model expectations. We see no evidence for
neutral-current production of J/psi via either diffractive or deep inelastic
scattering mechanisms.Comment: 13 pages, submitted to Phys. Rev. D, FERMILAB-Pub-99/269-
A measurement of the Z0 leptonic partial widths and the vector and axial vector coupling constants
We have measured the partial widths of the Z0 into lepton pairs, and the forward-backward charge asymmetry for the process e+e--->[mu]+[mu]- using the L3 detector at LEP. We obtain an average [Gamma]ll of 83.0+/-2.1+/-1.1 MeV.From this result and the asymmetry measurement, we extract the values of the vector and axial vector couplings of the Z0 to leptons: grmv=-0.066-0.027+0.046 and grmA= -0.495-0.007+0.007.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28666/3/0000483.pd
A new measurement of the cross section of the inverse muon decay reaction νμ + e- → μ- + νe
We have measured the cross section for inverse muon decay in the CERN neutrino wide band beam. From 4808 events observed in the CHARM II detector we derived for the Born term of the asymptotic cross section slope the result (18.16±1.36) × 10-42 cm2 GeV-1. This cross section is in good agreement with the standard model prediction and allows to constrain the scalar coupling of the electron and muon to their neutrinos to0SCOPUS: ar.jinfo:eu-repo/semantics/publishe
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