Solar and Atmospheric Neutrinos

1
Solar and Atmospheric Neutrinos

• 8th International Workshop
• on Neutrino Factories,
• Superbeams Betabeams

Michael Smy UC Irvine
Irvine, California, August 25th 2006
2
Cast of Characters
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Super-Kamiokande

• 50kt Water Cherenkov Detector with 11,146 20 f
  PMTs
• located in Kamioka mine at 36.430N latitude and
  137.310 longitude 2,400 m.w.e underground

• April 1996-July 2001 (SK-I)
  Accident in November 2001 during maintenance
  Jan. 2003-Oct. 2005 SK-II (half PMT density)
  July 2006 (SK-III)
• many physics topics solar, atmospheric
  accelerator ns, proton decay

Courtesy Y. Oyama
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Super-K Is Repaired!
now finished!
began in fall 2005
despite some weather problems!
Mozumi Mine Entrance
Village of Dou near Atotsu Mine Entrance
Michael Smy, UC Irvine
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Sudbury Neutrino Observatory

• 1kt Heavy Water 7kt Light Water Cherenkov
  Detector with 9,438 8 f PMTs
• located in Creighton mine at 46.470N latitude and
  81.20W longitude 6,000 m.w.e underground
• November 1999-June 2001 (measurement with pure
  D2O) June 2001-October 2003 (NaCl dissolved to
  improve neutron eapture efficiency)
  April 2004- (with neutral current detector
  array)
• Mainly solar neutrinos

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Other Experiments
Homestake
Soudan 2
MACRO
Atmospheric n
Atmospheric n
Solar n
SAGE
Solar n
Solar n
Solar n
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Neutrino Sources and Oscillations
Mixing- Matrix
Michael Smy, UC Irvine
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I Solar Neutrinos
Michael Smy, UC Irvine
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Solar Neutrino Detection

in SNO
(n,p)
?
n
(n-1,p1)
CC
e-

e

• ne only
• D Q 1.445 MeV good measurement of ne energy,
  some direction info ? (1 1/3 cosq)
• Cl Q0.8 MeV (radio-chemical)
• Ga Q0.233 MeV (radio-chemical)

in SNO
NC
n
n


?

n
p
D
x
x

• equal cross section for all active n types
• Q 2.22 MeV
• measures total 8B n flux from the Sun

in Cherenkov Detector


?

e-
n
e-
n
ES
x
x

• mainly sensitive to ne, some n? and n?
• strong directional sensitivity

Based on K. Graham, ICHEP06
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Solar n Spectrum from Solar Model
KamLAND
Michael Smy, UC Irvine
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Solar n Candidates above 5 MeV
Michael Smy, UC Irvine
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SNO Signal Extraction

• maximum likelihood fit of model PDFs to data
• event variables R (radial position) b14(isotropy)
  cosqsun and E(energy)

ES separation
dont use E g energy-unconstrained g fit out CC
spectrum!
K. Graham, ICHEP06
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Solar n Problem
Michael Smy, UC Irvine
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SNO Results from NaCl Phase
4722 candidate events 391 live days
Flux Results
Neutrino Flavour Change!
Day/Night Asymmetry
CC
2176/-78
EVENTS
NC
2010/-85
Based on K. Graham, ICHEP06
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Solar Neutrino Problem Explained by SNO and
Super-K as Neutrino Flavor Conversion!
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Recoil Electron Spectrum
MC
f8B2.33x106/cm2s
fhep15x103/cm2s
ADN-1.81.61.2
ADN-6.34.3(stat)
8B n MC only
8B n MC only
Michael Smy, UC Irvine
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SNO CC Spectrum
no significant sterile or NSI effects
Based on K. Graham, ICHEP06
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Solar Neutrino Oscillation Parameters
SolarKamLAND
KamLAND
99.73
Solar
95
Michael Smy, UC Irvine
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Solar Neutrino Future Measurements

• SNO NCD phase will produce smaller error on NC
• Lower energy real-time 8B neutrino measurement in
  SK-III (and SNO) studies transition from vacuum
  oscillation to matter-dominated oscillations
• Borexino (and KamLAND) measure 7Be flux
• SNO looks at pep flux
• various projects to measure pp flux in real time

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II Atmospheric Neutrinos/Neutrino Beams
Michael Smy, UC Irvine
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Atmosph. n Oscillations
n decoh.
n decay

• 1489 live days of SK-I and 804 live days of SK-II
• only muon-like single ring events
• cut out low energy events and events near horizon
  (poor resolution in L) uncertainty in L/E is set
  to be lt70
• best fit nm?nt sin22q1.00, Dm22.3x10-3eV2,
  c283.9/83dof
• n-decay Dc223.2 or 4.8s
• n-decoher. Dc227.6 or 5.3s

n oscill.
Michael Smy, UC Irvine
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All SK Atmospheric n Data Samples
CC ne
CC nm
Plep
Best Fit Dm2 2.5 x 10-3 eV2 sin2 2q 1.00 c2
839.7 / 755 dof (18)
FC 1ring e-like
FC mring e-like
FC 1ring m-like
FC mring m-like
up-m show.
PC stop
PC thru
up-m thru
Multi-GeV
up-m stop
Preliminary
38 event type and mom. bins x 10 zenith bins x 2
exp. ? 760 bins!
Sub-GeV

• slightly better constraint on mixing angle
• but solar osc. terms affects electron samples
• true, even if q130
• especially affects deviation from max. mixing
• include solar term
• best-fit sin2 q23 0.52 (sin2 2q23 0.9984)

Preliminary
Michael Smy, UC Irvine
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Zenith angle distributions (SK-I SK-II)
data MC (no osc.) MC (best-fit w/
solar terms)
Sub-GeV e-like
Sub-GeV m-like
PC stopping
PC thru-going
Multi-GeV e-like
Multi-GeV m-like
UPm stopping
Preliminary
UPm through non-showering
multi-ring m-like
multi-ring e-like
showering
Michael Smy, UC Irvine
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Three Flavour Oscillation Analysis
1489d Normal Hierarchy
1489d Inverse Hierarchy
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Sterile Admixture Limit
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Other Atmospheric n Measurements
PRD 72, 052005 (2005)
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Future Atmospheric n Measurements

• SK-III will improve L/E measurements and t
  appearance analaysis
• MINOS distinguishes atmospheric neutrinos from
  antineutrinos
• INO, a 50kt magnet. iron experiment

P. Litchfield, Neutrino 2006
Magnetic field 1 Tesla along ?y-direction
A. Samanta, ICTP 2006/A. Dighe, ICHEP 2006
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Conclusion

• we learned a lot about neutrino oscillations from
  solar and atmospheric neutrinos (everything we
  know, except Dm212!)
• still not finished, so stay tuned