August 6 Minutes

New Study beginning: Superbeams with more experimental detail!

Table presented for us to consider filling in: Imagine running narrow band beams at several energies, with realistic beam fluxes (both signal and background beam fluxes!), and realistic detector backgrounds and efficiencies: what is the physics reach as a function of energy/baseline? This reach should be evaluated as a function of delta m_23^2. (perhaps 3 values should be chosen, for example). There are a few baselines and detector options listed in a table at the end of these minutes. Right now people have signed up for the FNAL to Soudan and FNAL to SLAC baselines, but if you personally want to study another baseline not listed then by all means make some flux files and we can enter them into the machinery to study physics capabilities!

It's assumed that one would run a narrow band beam at the peak of the "first minimum", so that one would have the best signal/noise ratio. If the beamline energy spectrum is narrow enough, one might also consider running at higher energies, in an already existing beamline. The important thing about this table is that each beamline be realistic, and then all the detector, proton power, and running times should be consistent between each study. Then we can really make comparisons between physics reaches of different choices.

Although the table below lists several different baselines, it was noted repeatedly that we should focus on really exploring fully all the possibilities with the NUMI beamline, since that is what is being built presently, and it's hard to imagine another beamline being built any time soon...that being said, people were opposed to ignoring completely the possibilities of higher energy beamlines going at different baselines.

Studies have already been done exploring off-axis beams: Larry Wai has presented some results at MINOS and Snowmass (which Debbie showed at the meeting today--just to demonstrate that off-axis beams may provide more flux at a particular energy than the wide-band beam), and Michal Sleper and Mayda Velasco will present results from their studies at next week's meetings.

Work Assignments:

Mayda Velasco and Michal Szleper have already started studies to see what NUMI off-axis beams can produce, they will show the fluxes they have achieved at the next meeting (August 13). Mayda Velasco and Peter Kasper will also discuss the interaction between the proton driver upgrade group and our study group--tune in next week!

Bob Bernstein offered to get his machinery going for these studies: if we can come up with reasonable fluxes and detector resolutions, he can throw them into his code and it will come up with physics sensitivities as a function of delta m_23^2. (We also need to put in backgrounds as a function of detector, too!).

Mario Campanelli also offered to put input fluxes into his monte carlo fitting aparatus as well. Mario stressed that it's not clear what the correlation is between these off axis beam energies and beamline geometry, etc. It would be nice to see a few general studies that give people a feeling for how the off-axis beams work.

Jorge Morfin will explore the possibility of designer higher energy but narrow band beamlines going to the MINOS far detector hall.

Debbie Harris offered to look into what high energy off-axis beamlines might produce in terms of flux.

Although Water Cerenkov hasn't been studied in detail at these energies, it's hoped that some of the UNO folks can contribute to this study as well by coming up with background estimates for different fluxes.

Baseline Detector (Kton) Neutrino Energy (GeV) sin2 theta_13 reach sin2 theta_23 precision
JHF-SK WC (50)
JHF-HK WC (500)
FNAL-"Soudan" 730km Fe-based (50)
FNLA-Homestake 1300km Fe-based (50)
FNAL-WIPP 1800km Fe-based (50)
FNAL-San Jacinto/SLAC 2900km Liquid Ar (50)
FNAL-"Soudan" 730km Liquid Ar (25)
FNLA-Homestake 1300km Liquid Ar (25)
FNAL-WIPP 1800km Liquid Ar (25)
FNAL-San Jacinto/SLAC 2900km Liquid Ar (25)
FNAL-"Soudan" 730km Water Cerenkov (500?)
FNLA-Homestake 1300km Water Cerenkov (500?)
FNAL-WIPP 1800km Water Cerenkov (500?)
FNAL-San Jacinto/SLAC 2900km Water Cerenkov (500?)

Deborah Harris
Last modified: Mon Aug 6 15:41:56 CDT 2001