K2K June/2000 Official Plots

Beam MC Group

• Fitted results of pion monitor analysis (in the form of (p,theta) distributions) are used to further constrain the nuclear model dependence of the uncertainty.
• The energy dependence of the uncertainty is presented.
• Proton input profile and centering are treated together by considering combinations of inputs. (Previously, they were treated separately and the result added linearly.)
• Kaon normalization error is studied. (Previously omitted.)
• The qualitative result from Ionocopter that the largest scale of magnetic field perturbations is disfavored is used.

• Captions for all plots
This list has comments on all the below and a couple are to be added.
• Systematic error on MC only analysis This is the systematic error as a function of neutrino energy for extrapolation using only beam MC information. (That is: not directly using any monitor data for the extrapolation. Monitor data are used to constrain this error in the MC estimation.) Sources of error considered are:
  • Nuclear model dependence of pi+ production. This uses the 64 nuclear model study and the fitted pion monitor data. The major update is the use of the monitor information. Numerically, this is a small effect, but it means we are using our own measurements as part of the input.
  • Nuclear extrapolation from Be to Al. This (a much smaller effect than the previous item) is a study changing the nuclear corrrection factor in the MC. (Except for energy dependence, this item is unchanged from the previous version at the Jan. 2000 meeting.)
  • Normalization of Kaon production. This uses the difference between pion cross section measurements from the Derrick experiment (our main source for pion production) and the Yamamoto paper (from which we get kaon production). This term is still being checked, but it is only large in the last energy bin. (This is a new term that was not included in the previous version.)
  • Magnetic field perturbations in the horn. (This term is updated compared to previous by using the information from Ionocopter that cases with 20% field variations are unlikely.)
  • Proton profile and centering. This is updated compared to previous by consireding separate MC cases of combinations of targeting center and profile width. (Previously, these variables were checked separately and the results added linearly.)
  • Mechanical sagging of the target. (This is probably over-estimated.) (Except for energy dependence, this item is unchanged from the previous version at the Jan. 2000 meeting.)
• Error estimate for extrapolation integrated over the expected FD spectrum at Z=300 out to a radius of 2m. This includes all the above mentioned sources. The integration over energy is done over finer bins than the above and (anti-)correlation of energies is automatically accounted for. This is only directly applicable to the expectation with no oscillations.
• Production point of neutrinos in the MC
This figure shows the production point for all neutrinos above 1/2GeV that pass within 1.5m of the beam axis at Z=300m. This includes far over 99% of those within 10Km of SK.
• Production point of the parents of neutrinos in the MC
(To be updated) This shows the approximate production point of the parent of each of the neutrinos in the previous plot.
• Neutrino fluxes on and off axis.(vers 1)
This figure shows expected neutrino flux at SK on axis and one kilometer away from the axis. The point is that even in this bad case we expect a reasonably similar spectrum.
• Neutrino fluxes on and off axis.(vers 2)
This alternate version of the previous plot shows the flux on axis and at 1,2,3 km away. This is nice because one can more easily see the difference, but may have the bad effect that it could make someone think we could actually be that far off in our survey. This is not true.

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I was also asked at the collaboration council meeting to make a short (1-page if possible) summary description of the beam MC. This draft is slightly long. There are two pages of information and a third page which is a reference list for pion production experiments. This is not intended to be a figure to show in a talk, but rather information to organize the talk. The two pages of information are split into a part on proton-aluminum interactions and a part on everything else.

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