Neutrino factory physics reach and impact of detector performance

1
Neutrino factory physics reach and impact of
detector performance

• 2nd ISS MeetingKEK, Tsukuba, JapanJanuary 24,
  2006
• Walter Winter
• Institute for Advanced Study, Princeton

2
Contents

• Introduction
• Optimization of a neutrino factory
• Muon energy and baseline
• Disappearance channel optimization
• Impact of detector performance
• Physics beyond the big three indicators(q13
  discovery, CP violation, mass hierarchy)
• q13 and dCP precision measurements
• Physics case for q130?
• New physics tests
• Geophysics with a neutrino factory?
• Summary

3
Appearance channels nm ne
(Cervera et al. 2000 Freund, Huber, Lindner,
2000 Freund, 2001)

• Complicated, but all interesting information
  there q13, dCP, mass hierarchy (via A)

4
Correlations and degeneracies

• Connected (green) or disconnected (yellow)
  degenerate solutions (at a chosen CL) in
  parameter space
• Affect performance of appearance measurements.
  For example, q13 sensitivity

(Huber, Lindner, Winter, 2002)

• Discrete degeneracies (also Barger, Marfatia,
  Whisnant, 2001) Intrinsic (d,q13)-degeneracy
  (Burguet-Castell et al, 2001)sgn-degeneracy
  (Minakata, Nunokawa, 2001)(q23,p/2-q23)-degenerac
  y (Fogli, Lisi, 1996)

5
NF-Strategies to resolve degeneracies depend on
sin22q13!
Intrinsic degeneracy disappears for better energy
threshold!

• Combine with superbeam upgrade(sin22q13 gt 10-3)
  (Burguet-Castell et al, 2002)
• Combine with silver channels ne -gt nt
  (sin22q13 gt 10-3 ?)(Donini, Meloni, Migliozzi,
  2002 Autiero et al, 2004)
• Better detectors Higher energy resolution,
  higher efficiencies atlow energies (CID!)
  (sin22q13 gt ?)(Later this talk)
• Second NF baseline Magic baseline (sin22q13 gt
  10-4)(Lipari, 2000 Burguet-Castell et al, 2001
  Barger, Mafatia, Whisnant, 2002 Huber, Winter,
  2003 others)
• Other possibilities?

sin22q130.001
(Fig. from Huber, Lindner, Winter, 2002)
6
Example Magic baseline

• IdeaYellow term 0 independent of E,
  oscillation parameters(Huber, Winter, 2003)

• Purpose Clean measurement of q13 and mass
  hierarchy
• Drawback No dCP measurement at magic baseline
• combine with shorter baseline, such as L3 000 km
• q13-range 10-4 lt sin22q13 lt 10-2,where most
  problems with degeneracies are present

7
Optimization of a neutrino factory
4 yr x 1.06 1021 m decays 4 yr 1.06 1021 m-
decays Detector 50 kt magnetized iron
calorimeter ISS-values? 100 kt, 55 years
running time factor 2.36 luminosity increase
for 1021 useful decays/year
First time GLoBES is runon a parallel cluster!
8
Muon energy and baseline q13

• Example q13 sensitivity relative to minimum in
  each plot (3s)
• Important resultSince muon energy 40 GeV
  enough?!
• Threshold effects

Preliminary
(Huber, Lindner, Rolinec, Winter, to appear
also Freund, Huber, Lindner, 2001)
9
Muon energy and baseline CP violation

• Example Sensitivity to max. CP violation
  (absolute conservative reach, 3s)

Preliminary

• Degeneracy problem for dCP3p/2 not solvable
  without additional information or improvements

(Huber, Lindner, Rolinec, Winter, to appear)
10
Muon energy and baseline Mass hierarchy

• Example Sensitivity to normal hierarchy
  (absolute reach, 3s)

Preliminary
(Huber, Lindner, Rolinec, Winter, to appear)

• If sin22q13 small Very long baseline necessary!

11
Disappearance channel

• Disappearance information important to reduce
  errors on leading parameters(see e.g. Donini,
  Fernandez-Martinez, Rigolin, 2005 Donini,
  Fernandez-Martinez, Meloni, Rigolin, 2005)
• Idea Use data sample without charge
  identification for disappearance, i.e., add
  right and wrong sign muon events
• Better eff. at low E!

sin22q13 precision
(Fig. from Huber, Lindner, Winter, 2002)
Preliminary
sin22q13 0
(de Gouvea, Winter, 2005 Fig. from Huber,
Lindner, Rolinec, Winter, to appear)
12
Better detector? Hybrid detector?

• Better energy resolution?Was 0.15 x E
  (approximation) Optimistic
  ?
• Lower appearance threshold?Was 4 GeV, linearly
  climbing to maximum at 20 GeVOptimistic Max.
  already at 1 GeV
• CC/NC Backgrounds Assume power low
  such that 5 x 10-6 each at mean energies
• Background increases at low energies
• Even if CID improved, NC background limits
  performance!

(Fig. from Huber, Lindner, Winter, 2002 Gray
curve from Cervera et al, 2000)
(Cervera et al, 2000)
13
Better detector 4 toy scenarios

• Standard
• Appearance with standard threshold climbing
  from 4 to 20 GeV
• 15 E energy resolution
• Disappearance without CID
• Background constant in E
• Optimal appearance
• Appearance with better threshold better Eres
• Disappearance with CID !!! (old)
• Better background modeling
• Better Eres
• Like 2, but old threshold
• Better threshold
• Like 2, but old Eres modeled as 0.5 Sqrt(E)

14
Better detector q13 sensitivity

• High CL chosen (4s)avoid threshold
  effects(q13,dCP)-degeneracy affects
  sensitivity limitat L 1500-5000 km
• Better detector thresholdL2000-3000 km most
  attractive q13-baseline

Magicbaseline
Preliminary
15
Better detector MH, dCP
Preliminary

• Choose dCP3p/2 because most problems with
  degeneracies around there Cannot be completely
  resolved!
• Both Eres and threshold increase sensitive
  region Especially better threshold

16
Better detector Large q13
Preliminary
No dCP at Lmagic!

• Both better Eres and threshold useful
• Both better detector and smaller matter density
  uncertainty useful
• Either or combination sufficient to compete with
  the superbeam upgrades (prel.)
• Large Drbetter detector prefers shorter
  baselines (1000-2000km) Em small OK

17
Better detector Summary

• Better threshold helps for
• Optimization
• 3000 km competitive for q13 (compared to 7500
  km)But depends on chosen CL and finally
  achieved luminosity
• Lower Em possible (not shown) 30 GeV muons?
• Better absolute reaches (MH, dCP)
• Better energy resolution helps for
• Leading parameter measurements (very preliminary)
• Indirectly for sub-leading parameters
• Somewhat better absolute reaches (MH, dCP)
• However Even optimal detector cannot resolve
  degeneracies completely!

18
Physics beyond the big three indicators(q13
discovery, CP violation, mass hierarchy)
19
Precision of q13

• How precisely can one measure q13 if found?
• Dependence on dCP characterized by bands
• Qualitatively similar behavior to dCP precision

(Fig. from Huber, Lindner, Winter, 2002)
20
Precision of dCP / CP coverage

• Define CP coverage Fraction of all fit values
  of d which fit a chosen true d 0 lt CP coverage
  lt 360o

CP scaling
CP pattern
Degeneracy problemeven bigger thanfor max. CP
violation!
(Dc2 9, 4, 1 dashed no degs)
(Fig. from Huber, Lindner, Winter, hep-ph/0412199)

• True values of d and q13 affect topology!
  Degeneracies!
• But Degeneracies not everywhere in param. space
  important

21
CP coverage and real synergies
Any extra gain beyond a simple addition of
statistics

• 3 000 km 7 500 kmversus all detector mass at
  3 000 km (2L)
• Magic baseline allows a risk-minimized
  measurement (unknown d)
• Staged neutrino factory Option to add magic
  baseline later if in bad quadrants?

(Huber, Lindner, Winter, 2004)
One baseline enough
Two baselines necessary
22
Physics case for q130?
Establish MSW effect for q130by solar
oscillation (appearance prob.) L gt 5,500
km (Winter, 2004)
Determine mass hierarchy for q130(disappearance
probability) L 6,000 km (de Gouvea, Jenkins,
Kayser, 2005 de Gouvea, Winter,2005)
Very long (gtgt 3,000 km) baseline important
component of any such program!In addition q130
would be an important indicator for some symmetry!
23
New physics tests

• Test unitarity and small ad-mixtures of new
  physics by
• nt detection PeePemPet 1? (Donini, Meloni,
  Migliozzi, 2002 Autiero et al, 2004)
• Neutral currents (hard) (Barger, Geer, Whisnant,
  2004)
• Spectral signature on probability levelExample
  Damping effects(Blennow, Ohlsson, Winter,
  hep-ph/0502147)
• More complicated Hamiltonian-level effects
• (e.g., Blennow, Ohlsson, Winter,
  hep-ph/0508175)Example Oscillation-NSI
  confusion theorem(Huber, Schwetz, Valle, 2002)

See other talks inthis workshop forspecific
possible effects!E.g. Hisano, Kanemura, Sato,
Sorel, Xing
24
Other physics Geophysics?

• Example Measure inner core density rIC
• Per cent level precision not unrealistic
• Survives unknown oscillation parameters
• More recent discussions Discriminate seismically
  degenerate geophysics models in mantle, test plum
  hypothesis etc.?

sin22q130.01
JHF
BNL
CERN
(Winter, 2005)
Inner core shadow
25
Summary and conclusions

• Energy and baseline optimizationMuon energy of
  40 GeV enough!?L1000 km, Em20 GeV not an
  option!?
• Better detector will definitively
  helpEspecially Better threshold (app. low
  energy efficiency)
• There is plenty of beautiful neutrino
  oscillationphysics beyond standard q13, mass
  hierarchy, CP violation. Example Physics case
  q130
• Problem for any serious calculation
  calculation time! So far calculated on
  opportunistic systems with greatly variable
  calculation time! Parallel cluster time
  needed!Example One L-E-Plot takes 300-500 CPU
  hours
• Next steps Channel requirements,

26
Better detector in L-E-space q13 sens.

• 3s sensitivity to sin22q13

Better Eres
Better threshold
Better Eresthresh.
Preliminary
(Huber, Lindner, Rolinec, Winter, to appear)
27
Better detector in L-E-space Large q13

• CP fraction for CP violation (3s)Standard
  Optimal appearanceL1000 km/Em20 GeVpossible
  alternative?

Preliminary
(Huber, Lindner, Rolinec, Winter, to appear)