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Impact of large q 13 on long-baseline measurements at PINGU. PINGU Workshop Erlangen university May 5, 2012 Walter Winter Universität Würzburg. TexPoint fonts used in EMF: A A A A A A A A. Contents. Introduction Oscillation physics using a core-crossing baseline - PowerPoint PPT Presentation
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Impact of large 13 on long-baseline measurements at PINGU
PINGU WorkshopErlangen universityMay 5, 2012
Walter Winter
Universität Würzburg
2
Contents
Introduction Oscillation physics using a core-crossing
baseline Neutrino beam to PINGU:
Beams and detector parameterization Detector requirements for large 13
Matter density measurement? Summary
3
Three flavor mixing
Use same parameterization as for CKM matrix
Pontecorvo-Maki-Nakagawa-Sakata matrix
( ) ( ) ( )= xx
(sij = sin ij cij = cos ij)
Potential CP violation ~ 13
4
13 discovery 2012
First evidence from T2K, Double Chooz Discovery (~ 5) independently (?)
by Daya Bay, RENO
(from arXiv:1204.1249)
1 error bars
Daya Bay 3
5
Three flavors: 6 params(3 angles, one phase; 2 x m2)
Describes solar and atmospheric neutrino anomalies, as well as reactor antineutrino disapp.!
Three flavors: Summary
Coupling: 13
Atmosphericoscillations:Amplitude: 23
Frequency: m312
Solaroscillations:Amplitude: 12
Frequency: m212
Suppressed
effect: CP
(Super-K, 1998;Chooz, 1999; SNO 2001+2002; KamLAND 2002;Daya Bay, RENO 2012)
MH?
6
Consequences
Parameter space for CP starts to become constrained; MH/CPV difficult (need to exclude CP=0 and )
Need new facility!
Huber, Lindner, Schwetz, Winter, 2009
7
Mass hierarchy measurement?
Mass hierarchy [sgn(m2)] discovery possible with atmospheric neutrinos? (liquid argon, HyperK, MEMPHYS, INO, PINGU?, LENA?, …)
Barger et al, arXiv:1203.6012;Smirnov‘s talk!
However: also long-baseline proposals! (LBNO: superbeam ~ 2200 km – LAGUNA design study; CERN-SuperK ~ 8870 km – Agarwalla, Hernandez, arXiv:1204.4217)
Perhaps differentfacilities for MH and CPV
proposed/discussed?
Oscillation physics using a core-crossing baseline
9
Matter profile of the Earth… as seen by a neutrino
(PR
EM
: Prelim
inary R
eference E
arth M
odel)
Core
Innercore
10
Beams to PINGU? Labs and potential detector locations (stars) in
“deep underground“ laboratories: (Agarw
alla, Hu
ber, Tang, W
inter, 2010)
FNAL-PINGU: 11620 kmCERN-PINGU: 11810 kmRAL-PINGU: 12020 kmJHF-PINGU: 11370 km
All these baselines cross the Earth‘s outer core!
11
Matter effect (MSW) Ordinary matter:
electrons, but no , Coherent forward
scattering in matter: Net effect on electron flavor
Hamiltonian in matter (matrix form, flavor space):
Y: electron fraction ~ 0.5
(electrons per nucleon)
(Wolfenstein, 1978; Mikheyev, Smirnov, 1985)
12
Parameter mapping (two flavors)
Oscillation probabilities invacuum:matter:
Matter resonance: In this case: - Effective mixing maximal- Effective osc. frequency minimal
For appearance, m312:
- ~ 4.7 g/cm3 (Earth’s mantle): Eres ~ 7 GeV- ~ 10.8 g/cm3 (Earth’s outer core): Eres ~ 3 GeV
Resonance energy:
MH
13
Mantle-core-mantle profile
Probability for CERN-PINGU (numerical)
(Parametric enhancement: Akhmedov, 1998; Akhmedov, Lipari, Smirnov, 1998; Petcov, 1998)
Coreresonance
energy
Mantleresonance
energyInter-ference
Thresholdeffects
expected at:2 GeV 5 GeV 10 GeV
Beam energyand detector thresh. have
to pass these!
Is thatpart
useful?
Challenge: Relative size of
CP-termssmaller forlonger L
Neutrino beam to PINGU?
Beams and detector parameterization
15
There are three possibilities to artificially produce neutrinos
Beta decay:Example: Nuclear reactors, Beta beams
Pion decay:From accelerators:
Muon decay:Muons produced by pion decays! Neutrino Factory
Muons,neutrinos
Possible neutrino sources
Protons
Target Selection,focusing
Pions
Decaytunnel
Absorber
Neutrinos
Superbeam
16
Considered setups
(for details: Tang, Winter, JHEP 1202 (2012) 028, arXiv:1110.5908; Sec. 3)
Single baseline reference setups:
Idea: similar beam, but detector replaced by PINGU/MICA [need to cover ~ 2 – 5 GeV]:
L [km]
17
Want to study e- oscillations Beta beams:
In principle best choice for PINGU (need muon flavor ID only) Superbeams:
Need (clean) electron flavor sample. Difficult? Neutrino factory:
Need charge identification of + and - (normally)
Oscillation channels
18
PINGU fiducial volume? In principle: Mton-size detector in relevant ranges:
Unclear how that evolves with cuts for flavor-ID etc. (background reduction); MICA even larger? Use effective detector parameterization to study requirements: Eth, Veff, Eres
(Tang, Winter, JHEP 1202 (2012) 028; Veff somewhat smaller than Jason‘s current results)
Eth
Veff
Eres (E) = E
19
Detector paramet.: mis-ID
misIDtracks << misID <~ 1 ?
(Tang, Winter, JHEP 1202 (2012) 028)
misID: fraction of events of a
specific channel
mis-identified as signal
Detector requirements for large 13
21
Superbeam
Mass hierarchy measurement very robust(even with largemisID and totalrates only possible)
Even with much smaller-scale beam?
Existing equipment, such as CNGS? NuMI?
CPV not promising (requires flavor mis-ID at the level of 1%, Veff > 5 Mt, Eres = 0.2 E or better)
(Tang, Winter, JHEP 1202 (2012) 028)
(misIDtracks = 0.01)
Fra
ctio
n of
C
P
22
NuMI-like beam to PINGU?
Difference to atmospherics: can even live without energy resolution and cascade ID (NC and added)(if some track ID and systematics controlled)
NuMI
23
Beta beam
Similar results for mass hierarchy measurement (easy)
CPV not so promising:
long L, asymmetric beam energies (at least in CERN-SPS limited case
~656 for 8B and =390 for 8Li) although moderate detector requirements
(Tang, Winter, JHEP 1202 (2012) 028)
(misID ~ 0.001, Eth=2 GeV, Eres=50% E, Veff=5 Mt)
24
Neutrino factory
No magnetic field, no charge identification Need to disentangle Pe and P by energy
resolution:
(from: Tang, Winter, JHEP 1202 (2012) 028; for non-magnetized detectors, see Huber, Schwetz, Phys. Lett. B669 (2008) 294)
)
25
contamination
Challenge:
Reconstructed at lower energies!(Indumathi, Sinha, PRD 80 (2009) 113012; Donini, Gomez Cadenas, Meloni, JHEP 1102 (2011) 095)
Choose low enough E to avoid
Need event migration matrices (from detector simulation) for reliable predictions! (neutral currents etc)
(sin2213=0.1)
(Tang, Winter, JHEP 1202 (2012) 028)
26
Precision measurements?
… only if good enough energy resolution ~ 10% E and misID (cascades versus tracks) <~ 1% can be achieved!
(Tang, Winter, JHEP 1202 (2012) 028)
The BONUS program: Matter density measurement of the Earth‘s core?
28
Example: Superbeam
Precision ~ 0.5% (1)
Highly competitive to seismic waves (seismic shear waves cannot propagate in the liquid core!)
(Tang, Winter, JHEP 1202 (2012) 028)
29
Conclusions [my personal view]
Superbeams Electron sample (cascades) probably contaminated by other flavors;
therefore precision measurements unlikely Interesting option: Use more or less existing equipment for a
mass hierarchy measurement? (e.g. CNGS/MINOS with new beam line?)
Bonus: matter density measurement of Earth‘s core Unique experiment as low-budget alternative to LBNE?
Neutrino factory Energy resolution critical, since non-magnetized detector Detector simulation needed to produce event migration matrices
for reliable conclusions if Eres ~ 10% E achievable? Beta beams
Intrinsically best-suited for PINGU/MICA: flavor-clean beam, requires muon neutrino flavor-ID
However: need high intensity, high energy 8B-8Li setups for reasonable sensitivities; there are better ways to build a beta beam for large 13 to do both MH+CPV
30
Statement of PINGU collaboration needed
now (or never)!?
BACKUP
32
Beams: Appearance channels
(Cervera et al. 2000; Freund, Huber, Lindner, 2000; Akhmedov et al, 2004)
Antineutrinos: Magic baseline:
L~ 7500 km: Clean measurement of 13 (and mass hierarchy) for any energy, value of oscillation parameters! (Huber, Winter, 2003; Smirnov 2006)
In combination with shorter baseline, a wide range of very long baseline will do! (Gandhi, Winter, 2006; Kopp, Ota, Winter, 2008)
33
Quantification of performanceExample: CP violation discovery
Sensitive region as a
function of true 13 and CP
CP values now stacked for each 13
Read: If sin2213=10-3, we
expect a discovery for 80% of all values of CP
No CPV discovery ifCP too close to 0 or
No CPV discovery forall values of CP3
~ Precision inquark sector!
Best performanceclose to max.
CPV (CP = /2 or 3/2)
34
Effective volume
Difference Eth = 2 GeV, Veff=5 Mt to actual (energy-dependent) fiducial volume:
(Tang, Winter, JHEP 1202 (2012) 028)
35
Note:
Pure baseline effect!
A 1: Matter resonance
VL baselines (1)
(Factor 1)2
(Factor 2)2
(Factor 1)(Factor 2)Prop. To L2; compensated
by flux prop. to 1/L2
36
Factor 1: Depends on energy; can be matter enhanced for long L; however: the longer L, the stronger change off the resonance
Factor 2:Always suppressed for longer L; zero at “magic baseline” (indep. of E, osc. Params)
VL baselines (2)
(m312 = 0.0025, =4.3 g/cm3, normal hierarchy)
Factor 2 always suppresses CP and solar terms for very long baselines; note that these terms include 1/L2-dep.!