MINOS: Neural Network Analysis
Background Rates
To the first order, everything that happens in the Far Detector,
within the ~ 10 microsecond spill window is a neutrino interaction.
A quick estimate of the in-spill background rate yields:
BEAM-ON time / year, T(On): (10e-06 sec/spill) * (3.1e+07 sec/yr) * (0.5 spills/sec) =>
T(On) ~ 150 sec
Background rate, R(Bkg) = ~ 1,300 snarls /hr /SM => R(Bkg) ~ 100 - 120 snarls/yr
For comparison, with 3.7e+20 pot/year we expect about ~ 2500 nu_mu CC's / year
(no oscillations, 100% trigger efficiency), while the number of NC's is less than 1/3 of that.
Therefore, the background is small but not negligible.
The Far Detector 'BEAM-ON' (in-spill) background is 'simulated' by its
abundant 'BEAM-OFF' data.
These background events contaminate both the NC and CC neutrino event sample.
Applying the NC/CC Neural Network to a sample of such background events yields:
The background to the CC sample is caused mainly by CR muons while the
contaminations to the NC sample is due to natural radioctivity, light leaks etc...
Contact :
Costas Andreopoulos
[C.V.Andreopoulos@rl.ac.uk]