Very long baselines (maps)

Very long baselines

Neutrino factories could be the ultimative tool for high precision measurements of the small ``reactor'' angle theta_13, the neutrino mass hierarchy, and the leptonic Dirac CP phase. Typical interesting neutrino factory baselines are for a 50 GeV neutrino factory:

L~3000 km: Optimal for CP measurements

L~7250 km: ``Magic baseline'' where CP effects are almost zero to resolve correlations and degeneracies; see e.g. hep-ph/0301257

L>10700 km: Baselines through the Earth's core to observe Earth matter resonance effects; below we refer to the region on the surface where baselines for a specific source go through the Earth's core as ``Core shadow''

In partcular, the combination 3000km+7250km leads to a very competitive neutrino factory performance. In addition, the magic baseline might be useful for superbeams if theta_13 turned out to be large.

Potential high energy laboratories, who could be interested in a neutrino factory, are (from west to east):

Fermi National Accelerator Laboratory (FNAL), USA
Brookhaven National Laboratory (BNL), USA
CERN, Europe
JHF/Jaeri/KEK, Japan

On this page, we show possible detector sites for these laboratories. Since very long neutrino factory baselines are difficult to visualize, we project the iso-baseline curves onto different world maps. Example for L=3000 km (thin curves) and L=7250 km (thick curves) for all laboratories:

Postscript

Additional maps:

Below, the left maps show, for a specific lab, the 3000 km, 7500 km, and tangential core iso-baseline curves. The right maps show the iso-baseline curves for a specific site in 1000 km steps, where a different projection allows only half of the Earth's surface to be seen.

Some (biased) comments on potential detector sites:

A neutrino factory or superbeam detector may, depending on technology and synergies with other types of experiments (such as proton decay), either require an underground laboratory or only modest shielding. The requirement of an underground laboratory restricts the number of possibles detector sites. From the above maps we can read off a number of interesting observations:

The Pyhaesalmi mine in Finland could not only be interesting for CERN, but also for Japan as a magic baseline
The Gran Sasso laboratory is exactly on the magic baseline from Fermilab
The Homestake mine is on the magic baseline from CERN
China could be an interesting destination for JHF (3000 km) and CERN (magic)
Southern Africa or southern India could be interesting for a baseline from CERN (magic)
Brazil could host a detector for almost any magic baseline (except for JHF, where it is in the core shadow)
The only places which could be of interest for *all* labs are Southwest Canada, the very west of Russia, and the very east of Russia
Southern Australia could be an interesting place for a JHF magic baseline and it is in the core shadow for CERN and the US labs

FNAL	Postscript	Postscript
BNL	Postscript	Postscript
CERN	Postscript	Postscript
JHF	Postscript	Postscript