“SPECIAL PARTICLE SEMINAR: Measuring Neutrino Oscillations with the T2K Experiment”

Speaker: 
Alex Himmel
Institution: 
Duke Univ.
Date: 
Monday, March 2, 2015
Time: 
3:00 pm
Location: 
FRH 4135
 

 
ABSTRACT:  
 
Neutrinos oscillate among flavors as they travel because a neutrino of a particular flavor is a also a superposition of multiple neutrinos with slightly different masses.  The interferometric nature of oscillations allows this mixing the be measured, but it requires powerful neutrino sources and massive detectors.  T2K is a long-baseline neutrino oscillation experiment with a muon neutrino beam produced at the J-PARC facility, a near detector complex located 280 m from the target, and using the Super-Kamiokande water Cherenkov detector, located 295 km away, as a far detector.  The beam is directed 2.5° away from the far detector, producing a narrow-band energy spectrum precisely tuned to measure neutrino oscillations at the “atmospheric” L/E.  In this beam, we have made the first definitive observation (> 7σ) of the appearance of a new neutrino flavor through oscillations.  With this electron neutrino appearance sample we measure the mixing angle θ13, and using the muon neutrino disappearance sample we measure the atmospheric mass splitting and mixing angle, θ23.  By combining both of these samples with the precise measurements of θ13 made by reactor experiments, we make the first exclusion of a region of δCP at the 90% confidence level.  

 
Host: 
Henry Sobel