3 Neutrino Oscillation and Off-axis Experiments

1. 3 Neutrino Oscillation and Off-axis Experiments David Barnhill UCLA May 30, 2003

2. 2 Neutrino Oscillations • Already talked about two different noscillations: • Solar n • Atmospheric n • Flavor states are superposition of mass eigenstates (Greek subscript is flavor and Roman subscript is mass state): where

3. 2 Neutrino Results With m2sol ~ 5 x 10-5 eV2 & m2atm ~ 3 x 10-3 eV2 But when plotting tan2 and not sin22, we know m1<m2<m3

4. Mass Hierarchy

5. 3 Neutrino Oscillation • Reality is that there are 3 neutrino flavors (or possibly 4 or more) and 3 neutrino mass eigenstates • This means neutrinos can oscillate between all three flavors How many parameters?

6. 3 Neutrino Mixing Matrix Using 3 ranges from solar, atmospheric and reactor data: Solar{ LMA Atm{ Reactor

7. 13 • Why is 13 important? • It is easily singled out in Ue3 matrix element and is directly linked to CP violating phase element • How do we measure 13? • Use  e experiment (To leading order) If the experiment is performed at the peak of this probability: Using CHOOZ limit, maximum appearance probability is 5% 2 neutrino case:

8. Reality is slightly more complex • The neutrinos must pass through matter, it’s not a vacuum oscillation • We need to include CP violating phase effects

9. Off-Axis Experiments and Superbeams • Two proposed experiments to be off-axis experiments using “superbeams” • NuMI • JHF-SK • Basically the idea is to create + by p+p collision, focus these + and get  from +->+ + 

10. Why Off-Axis? Neutrino energy in pion rest frame: assuming: Set * to 90°: Neutrino spectrum:

11. Why Off-Axis? We see that as theta increases, there is a maximum for the neutrino energy with a wide range of pion energies contributing to it. If we desire an enhancement at a particular neutrino energy, we look close to the max as given on the previous page.

12. NuMI and JHF-SK