Minutes from March 4 Meeting
gave a talk about the NUMI on and off-axis beams, considering
the differences between positive and negative horn polarity (i.e. making
a mostly neutrino or a mostly antineutrino beam). Bottom lines for a
NUMI off-axis beam, when horns and target are in nominal configuration:
- For on and off axis, numu event rates from 1 to about 5 GeV are
about 3 times the numubar rates
- For off axis, the fractional background from (nu_e+nubar_e)
is the same between numu and numubar running: this is because the
backgrounds are mostly from muon decay at 2GeV.
- the numu background in the numubar beam is about 10%, while
the numubar background in the numu beam is only about 1%.
Andre DeGouvea gave a talk
about the sensitivity to matter effects,
Ue3^2, and CP violation, using the fluxes assumed above. Where relevant
Andre, Gabriela and Mayda assumed there would be both an on-axis and an
off axis measurement.
The running assumptions are:
off and on axis detector 40kton-years for neutrino
running, and 80 kton-years for antineutrino running. The efficiency
and background assumptions correspond to segmented minos off-axis
(so very little NC background), and minos on-axis (more NC background).
The assumption is
that the two detectors have the same mass, so given that MINOS is 5kton,
if you had an off-axis detector at 5kton and a proton driver upgrade
(to gain a factor of 4) then you would be running for 2 years neutrino
mode, 4 years antineutrino mode. If you had the off axis detector with more
mass, that counts for more since most of the statistical power for looking
at numu to nue comes from the off-axis beam.
Plots were shown for three different values of solar mass splitting (dm_12^2),
since for these three regions the physics reach is different.
Steve Geer made the suggestion that for given values of ue3^2, one should
also include the measurement that could be made by JHF to SuperK--as a
constraint--the different energy
could be an important constraint in some (if not most) of the above plots.
Last modified: Mon Mar 4 15:39:45 CST 2002