aspen 2002
DESCRIPTION
Aspen 2002. Recent Results from Super-K (and K2K) Neutrino Oscillations & Mechanical Chain Reactions Jordan Goodman University of Maryland. Super-Kamiokande. Detecting neutrinos. Cherenkov ring on the wall. Electron or muon track. The pattern tells us the energy and type of particle - PowerPoint PPT PresentationTRANSCRIPT
J. Goodman - Aspen - Feb 2002
Aspen 2002
Recent Results from Super-K (and K2K)
Neutrino Oscillations &
Mechanical Chain Reactions
Jordan GoodmanUniversity of Maryland
J. Goodman - Aspen - Feb 2002
Super-Kamiokande
J. Goodman - Aspen - Feb 2002
Detecting neutrinos
Electron or
muon track
Electron or
muon track
Cherenkov ring on the
wall
Cherenkov ring on the
wall
The pattern tells us the energy and type of particle
We can easily tell muons from electrons
The pattern tells us the energy and type of particle
We can easily tell muons from electrons
J. Goodman - Aspen - Feb 2002
A muon going through the detector
J. Goodman - Aspen - Feb 2002
A muon going through the detector
J. Goodman - Aspen - Feb 2002
A muon going through the detector
J. Goodman - Aspen - Feb 2002
A muon going through the detector
J. Goodman - Aspen - Feb 2002
A muon going through the detector
J. Goodman - Aspen - Feb 2002
A muon going through the detector
J. Goodman - Aspen - Feb 2002
Stopping Muon
J. Goodman - Aspen - Feb 2002
Stopping Muon – Decay Electron
J. Goodman - Aspen - Feb 2002
Neutrino Production
Ratio predicted to ~ 5%
Absolute Flux Predicted to ~20% :
2
ee
J. Goodman - Aspen - Feb 2002
Atmospheric Oscillations
about 13,000 km
about 15
km
Neutrinos produced in
the atmosphere
Neutrinos produced in
the atmosphere
We look for transformations
by looking at s with different distances from production
SK
J. Goodman - Aspen - Feb 2002
Atmospheric Neutrino Interactions
n p
W+
Reaction Thresholds
Electron: ~1.5 MeV
Muon: ~110 MeV
Tau: ~3500 MeV
Charged Current Neutral Current
e e
n p
W +
J. Goodman - Aspen - Feb 2002
Telling particles apart
MuonElectronMuonElectron
J. Goodman - Aspen - Feb 2002
Muon - Electron Identification
PID Likelihood
sub-GeV, Multi-GeV, 1-ring
Monte Carlo (no oscillations)
We expect
about twice as
many as e
J. Goodman - Aspen - Feb 2002
Super-K Atmospheric Data Set
• 1289.4 days of data (22.5 kilotons fiducial volume)• Data Set is divided into:
– Single and Multi Ring events– Electron-like and Muon-like– Energy Intervals
• 1.4 GeV< Evis >1.4 GeV• Also Evis< 400MeV (little or no pointing)
– Fully or partially contained muons (PC)– Upward going muons - stopping or through going
• Data is compared to Atmospheric Monte Carlo– Angle (path length through earth)– Visible energy of the Lepton
J. Goodman - Aspen - Feb 2002
Low Energy Sample
No Oscillations
Oscillations (1.0, 2.4x10-3eV2)
J. Goodman - Aspen - Feb 2002
Moderate Energy Sample
J. Goodman - Aspen - Feb 2002
Multi-GeV Sample
Oscillations (1.0, 2.4x10-3eV2)
No Oscillations
UP going Down UP Down
J. Goodman - Aspen - Feb 2002
Multi-Ring Events
J. Goodman - Aspen - Feb 2002
Upward Going Muons
J. Goodman - Aspen - Feb 2002
Summary of Atmospheric Results
Best Fit for to
Sin22 =1.0,
M2=2.4 x 10-3eV2
2min=132.4/137 d.o.f.
No Oscillations
2min=316/135 d.o.f.
99% C.L.
90% C.L.
68% C.L.
Best Fit
Compelling evidence for to atmospheric neutrino oscillations
J. Goodman - Aspen - Feb 2002
Tau vs Sterile Neutrino Analysis
J. Goodman - Aspen - Feb 2002
Tau Appearance?
• Tau’s require greater than 3 GeV in neutrino energy– This eliminates most events
• Three correlated methods were used– All look for enhanced upward going multi-ring events
• All show slight evidence for Tau appearance• None are statistically significant
J. Goodman - Aspen - Feb 2002
The 0 sample
• For to s the rate of NC events is reduced as
compared to to which is the same as no
oscillations.• The SK NC enriched sample is only about 1/3
from NC interactions.
• The 0 sample is the cleanest NC signal
• Until now the error in (0) (~1-2 Gev) has been as large as the effect!
J. Goodman - Aspen - Feb 2002
Original SK Systematic Errors
• Systematic Error in r0=(0/Q.E.)
– Cross section – 20%
– Reconstruction – 7%
– Nuclear Interaction – 7%
– Flux – 3%
– Total Systematic – 23%
J. Goodman - Aspen - Feb 2002
Original Results from 0s
J. Goodman - Aspen - Feb 2002
K2K Near Detector
K2K beam is:
~1.3 GeV
98.2%
1.3% e
0.5%
J. Goodman - Aspen - Feb 2002
0 Peaks
J. Goodman - Aspen - Feb 2002
Monte Carlo of 0 Production
J. Goodman - Aspen - Feb 2002
Use K2K to measure the Cross Section
• A normalized 0 rate is defined as r0=(0/fc)
• Form double ratio of R0= r0(data)/r0(MC) to
minimize flux uncertainties and nuclear effects• Simulate both K2K and SK flux and efficiencies
• K2K finds R0 = 1.04 ± 0.02 ± 0.02 ± 0.09
Stat (data MC) Sys
• Old SK R0 = 1.05 ± 0.05 ± 0.01 ± 0.23
• Use K2K measurement to improve SK result
J. Goodman - Aspen - Feb 2002
New Systematic Errors in SK
• Using K2K Result
– Reconstruction – 7%
– Flux – 3%
– Spectral Diff between SK and K2K – 5%
– Cross section/Nuclear effects – 12%
(flux averaged)
– Total Systematic – 14%
J. Goodman - Aspen - Feb 2002
New Results
J. Goodman - Aspen - Feb 2002
Combined
J. Goodman - Aspen - Feb 2002
Super-K Disaster - Nov 12, 2001
• Chain reaction destroyed 7000 OD and 1000 ID Tubes
• The cause is not completely understood, but it started with a lower pmt collapse.
• The energy release comes from a 4 T column of water falling
• There are plans to rebuild…
J. Goodman - Aspen - Feb 2002
Disaster (Continued)
J. Goodman - Aspen - Feb 2002
Disaster (Continued)