202 research outputs found
Search for Decay in LSND
We observe a net beam-excess of (stat) (syst) events,
above 160 MeV, resulting from the charged-current reaction of
and/or on C and H in the LSND detector. No beam related muon
background is expected in this energy regime. Within an analysis framework of
, we set a direct upper limit for this
branching ratio of at 90% confidence level.Comment: 4 pages, 4 figure
Measurements of Charged Current Reactions of on
Charged Current reactions of on have been studied using a
decay-at-rest beam at the Los Alamos Neutron Science Center.
The cross section for the exclusive reaction
was measured to be cm. The observed
energy dependence of the cross section and angular distribution of the outgoing
electron agree well with theoretical expectations. Measurements are also
presented for inclusive transitions to excited states,
and compared with theoretical expectations. The
measured cross section, cm, is somewhat
lower than previous measurements and than a continuum random phase
approximation calculation. It is in better agreement with a recent shell model
calculation.Comment: 34 pages, 18 figures, accepted to PRC, replaced with the accepted on
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 Neutrino Oscillations from Muon Decay at Rest
A search for nu_bar_mu to nu_bar_e oscillations has been conducted at the Los
Alamos Meson Physics Facility using nu_bar_mu from mu+ decay at rest. The
nu_bar_e are detected via the reaction (nu_bar_e,p) -> (e+,n), correlated with
the 2.2 MeV gamma from (n,p) -> (d,gamma). The use of tight cuts to identify e+
events with correlated gamma rays yields 22 events with e+ energy between 36
and 60 MeV and only 4.6 (+/- 0.6) background events. The probability that this
excess is due entirely to a statistical fluctuation is 4.1E-08. A chi^2 fit to
the entire e+ sample results in a total excess of 51.8 (+18.7) (-16.9) (+/-
8.0) events with e+ energy between 20 and 60 MeV. If attributed to nu_bar_mu ->
nu_bar_e oscillations, this corresponds to an oscillation probability (averaged
over the experimental energy and spatial acceptance) of 0.0031 (+0.0011)
(-0.0010) (+/- 0.0005).Comment: 57 pages, 34 figures, revtex, additional information available at
http://nu1.lampf.lanl.gov/~lsnd
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