Measuring Atmospheric Parameters with SuperBeams

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Measuring Atmospheric Parameters with SuperBeams

• Enrique Fernández Martínez
• Departamento de Física Teórica and IFT
• Universidad Autónoma de Madrid

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Outline

• Introduction
• Oscillation parameters
• Experiments description
• Subleading effects in nm disappearance
• Dm2atm and the sign degeneracy
• q23 and the octant degeneracy
• The effects of q13 and d
• T2K-1 bounds revised
• Conclusions

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The oscillation parameters

• What we already know
• Solar sector
• Atm sector
• What we still dont know
• sin2q13 lt 0.40
• dcp
• Mass hierarchy
• Octant of q23

q12 28º38º
q23 35º55º
M. C. González García hep-ph/0410030
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Fluxes
T2K-1
SPL
OA2º
L295Km
L130Km
flux from p decay at
Old SPL fluxes courtesy of Gilardoni New fluxes
Campagne et al. hep-ex/0411062
T2K fluxes courtesy of J.J. Gómez Cadenas
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Event Rates
T2K-1 B1 B2 B3 B4
No osc. Nm 753 2228 2273 757
Signal Nm 46 101 381 239
SPL m - m
No osc. Nm 24245 25467
Signal Nm 1746 1614
4 energy bins of 200MeV Between 0.4 1.2GeV
L130Km
L295Km
Statistics dominated
Systematics dominated
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The importance of energy resolution
T2K-1
SPL
q13 0º d 0º
90 CL contours 5 systematic error and
backgrounds taken into account
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The importance of energy resolution
T2K-1
SPL
q13 0º d 0º
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The importance of energy resolution
T2K-1
SPL
q13 0º d 0º
E1 0.4 - 0.6GeV
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The importance of energy resolution
T2K-1
SPL
q13 0º d 0º
E1 0.4 - 0.6GeV
E2 0.6 - 0.8GeV
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The importance of energy resolution
T2K-1
SPL
q13 0º d 0º
E1 0.4 - 0.6GeV
E2 0.6 - 0.8GeV
E3 0.8 - 1.0GeV
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The importance of energy resolution
T2K-1
SPL
q13 0º d 0º
E1 0.4 - 0.6GeV
E2 0.6 - 0.8GeV
E3 0.8 - 1.0GeV
E4 1.0 - 1.2GeV
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The importance of energy resolution
T2K-1
SPL
q13 0º d 0º
E1 0.4 - 0.6GeV
E2 0.6 - 0.8GeV
E3 0.8 - 1.0GeV
E4 1.0 - 1.2GeV
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The nm disappearance channel
Where
sin 2q13 lt 0.4
E. K. Akhmedov et al. hep-ph/0402175 A. Donini
et al. hep-ph/0411402
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The sign degeneracy
Input q13 0º d 0º
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The sign degeneracy
Input q13 0º d 0º
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The sign degeneracy
Input q13 0º d 0º
Fit assuming inverted hierarchy
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The octant degeneracy
Input q13 0º d 0º
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The octant degeneracy
Input q13 0º d 0º
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The effect of q13
Input q13 0º d 0º
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The effect of q13
Input q13 0º d 0º
Assuming q13 0º
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The effect of q13
Input q13 0º d 0º
Assuming q13 0º, 2º
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The effect of q13
Input q13 0º d 0º
Assuming q13 0º, 2º, 4º
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The effect of q13
Input q13 0º d 0º
Assuming q13 0º, 2º, 4º, 6º
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The effect of q13
Input q13 0º d 0º
Assuming q13 0º, 2º, 4º, 6º, 8º
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The effect of q13
Input q13 0º d 0º
Assuming q13 0º, 2º, 4º, 6º, 8º, 10º
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The effect of d
Input q13 8º d 0º
Assuming d 0º
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The effect of d
Input q13 8º d 0º
Assuming d 0º, 90º
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The effect of d
Input q13 8º d 0º
Assuming d 0º, 90º, 180º
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T2K-1 errors revised
Input q13 0º q23 45º d 0º
90 CL
Present Dm2 (1.7 3.5)10-3 eV2 sin22q gt 0.9
tan2q 0.53 2.04
Dm2 (2.50 0.06)10-3 eV2 sin22q gt 0.98 Y.
Itow et al. hep-ex/0106019
Dm2 (2.43 2.60)10-3 eV2 sin22q gt 0.97 tan2q
0.73 1.39
Dm2 (2.45 2.56)10-3 eV2 sin22q gt 0.98
tan2q 0.76 1.31
Dm2 (-2.63 -2.49)10-3 eV2
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T2K-1 errors revised
Input q13 0º q23 40º d 0º
90 CL
Present Dm2 (1.7 3.5)10-3 eV2 sin22q gt 0.9
tan2q 0.53 2.04
Dm2 (2.42 2.61)10-3 eV2 sin22q 0.94 0.99
tan2q 0.62 0.85, 1.21 1.66
Dm2 (2.44 2.58)10-3 eV2 sin22q 0.95
0.99 tan2q 0.63 0.81, 1.24 1.58
Dm2 (-2.64 -2.47)10-3 eV2
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Conclusions

• The measurement of q13 and d will rely heavily on
  an improvement of the measure of q23 and Dm223
• Precision measurements of q23 and Dm223 need
  energy resolution and events above and below the
  oscillation peak
• The errors on the q23 and Dm223 are somewhat
  larger due to the dependence of the disappearance
  signal on q13 , d and the mass hierarchy
• This dependence can be exploited combined with
  the appearance channel to solve degeneracies

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T2K-2
T2K-2
T2K-1
5 systematic error
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T2K-2
T2K-2
T2K-1
2 systematic error
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No background and no systematic
Systematic 0 No Background
Systematic 5 With Background
Errors dominated by statistics
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10 systematic
Systematic 10
Systematic 5
Errors dominated by statistics
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Energy Resolution
Figure taken from Y. Itow et al. hep-ex/0106019
Red histogram for true QE events
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Double energy resolution
8 bins of 100MeV
4 bins of 200MeV
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Double energy resolution
8 bins of 100MeV
4 bins of 200MeV