A neutrino beam to IceCube/PINGU?(PINGU = “Precision IceCube Next-Generation Upgrade“)

NPAC (Nuclear/Particle/Astro/Cosmo) Forum

UW-Madison, USAMay 15, 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

Comments on LBNE reconfiguration 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

Mass spectrum/hierarchy

Specific models typically come together with specific MH prediction (e.g. textures are very different)

Good model discriminator(Albright, Chen, hep-ph/0608137)

8

8

Normal Inverted

6

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)

7

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

8

Mass hierarchy discovery?

90% CL, existing equipment

3, Project X and T2K with proton driver, optimized neutrino-antineutrino run plan

Huber, Lindner, Schwetz, Winter, JHEP 11 (2009) 44

9

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;IH more challenging

However: also long-baseline proposals! (LBNO: superbeam ~ 2200 km – LAGUNA design study; CERN-SuperK ~ 8870 km – Agarwalla, Hernandez, arXiv:1204.4217; South Pole: Dick et al, 2000)

Perhaps differentfacilities for MH and CPV

proposed/discussed?

Oscillation physics using a core-crossing baseline

11

What is PINGU?What is PINGU?

2012

12

PINGU fiducial volume?

A few Mt fiducial mass for superbeam produced with FNAL main injector protons (120 GeV)

(Jason Koskinen)

LBNE-beam

13

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!

14

Matter profile of the Earth… as seen by a neutrino

(PR

EM

: Prelim

inary R

eference E

arth M

odel)

Core

Innercore

15

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)

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Parameter mapping

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 ~ 6.4 GeV- ~ 10.8 g/cm3 (Earth’s outer core): Eres ~ 2.8 GeV

Resonance energy:

MH

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Mantle-core-mantle profile

Probability for FNAL-PINGU (numerical)

(Parametric enhancement: Akhmedov, 1998; Akhmedov, Lipari, Smirnov, 1998; Petcov, 1998)

Core resonance

energy

Mantleresonance

energy

Inter-ference

Thresholdeffects

expected at:2 GeV 4-5 GeV

Beam energyand detector threshold have to pass ~ 2 GeV!

Naive L/E scalingdoes not apply!

Parametric enhancementthrough mantle-core-mantle

profile of the Earth.Unique physics potential!

!

Neutrino beam to PINGU?

Beams and detector parameterization

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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

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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]

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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

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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 J. Koskinen ‘s current results)

Eth

Veff

Eres (E) = E

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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

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Superbeam (LBNE-like)

Mass hierarchy measurement very robust(even with largemisID and totalrates only possible)

(Tang, Winter, JHEP 1202 (2012) 028)

(misIDtracks = 0.01)

Fra

ctio

n of

C

P

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Low-intensity alternative?

Use existing equipment, new beam line Here: use most conservative assumption

NuMI beam, 1021 pot (total), neutrinos only[compare to LBNE: 22+22 1020 pot without Project X ~ factor four higher exposure than the one considered here] (FERMILAB-PROPOSAL-0875, NUMI-L-714)

Low intensity allows for shorter decay pipe (rough estimate: ~ 100 m for 700kW beam)

Advantage: Peaks in exactly the right energy range for the parametric enhancement due to the Earth‘s core

(Tang, Winter, JHEP 1202 (2012) 028)

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Detector parameterization Challenges:

Electron flavor ID Systematics (efficiency, flux normalization near

detector?) Energy resolution

Make very (?) conservative assumptions here: Fraction of mis-identified muon tracks (muon tracks may

be too short to be distinguished from signal) ~ 20% Irreducible backgrounds (zeroth order assumption!):

Intrinsic beam background Neutral current cascades cascades (hadronic and electromagnetic cascades

indistinguishable) Systematics uncorrelated between signal and

background No energy resolution (total rates only)

(for details on parameterization: Tang, Winter, JHEP 1202 (2012) 028)

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Event rates

Normal hier. Inv. hierarchy

Signal 1560 54

Backgrounds: e beam 39 59

Disapp./track mis-ID 511 750

appearance 3 4

Neutral currents 2479 2479

Total backgrounds 3032 3292

Total signal+backg. 4592 3346

(Daya Bay best-fit)

>18 (stat. only)

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NuMI-like beam to PINGU?

Very robust mass hierarchy measurement (as long as either some energy resolution or control of systematics); track mis-identification maybe too conservative

(Daya B

ay best-fit; current param

eter un

certainties, marginalized over)

GLoBES 2012

All irreducible backgrounds included

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Probabilities: CP-dependence

There is a rich CP-phenomenology:

(probably works for NH only!?)

NH

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Upgrade path towards CP? Measurement of CP

in principle possible, but challenging

Requires: Electromagnetic

shower ID (here: 1% mis-ID)

Energy resolution (here: 20% x E)

Maybe: volume upgrade(here: ~ factor two)

Project X Performance and

optimization of PINGU, and possible upgrades (MICA, …) require further study

= LBNE + Project X!

(Tang, Winter, JHEP 1202 (2012) 028)

same beamto PINGU

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Beta beam

Similar results for mass hierarchy measurement (easy)

CPV less 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)

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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)

)

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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)

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Matter density measurementExample: LBNE-like 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)

LBNE reconfiguration

(some personal comments)

Thanks discussions with:A. de Gouvea, F. Halzen, J. Hylen, B. Kayser, J. Kopp, S. Parke, PINGU collaboration, …

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~ 600M$

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Landscape (before reconfiguration)

LBNE one out of many options to measure CPV

Can this reach be matched in a phased approach?

How can one define a truly unique experiment for <= 600M US$?

How would one react if T2HK happens?

(P. Huber)

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Reconfiguration options?… or how to spend 600 M$

New detector, existing beam lineMINOS site (L=735 km)NOvA site (L=810 km)New site?

New (smaller) detector, new beam line (~300 M$)Smaller detector in Homestake (L=1300 km)Surface detector at Homestake (L=1300 km)

New beam line (<= 550 M$?), (then) existing detectorPINGU (L=11620 km)…

Idea ~ 2 weeks old

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Best physics concept?

(Barger, Huber, Marfatia, Winter, PRD 76 (2007) 053005)

NuMIbeam line

Newbeam line

Homestake, on-axis

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Conclusion:

LBNE – smaller version?

How many does one need?

Combination of experiments tolerable as physics result?

MH, 5

This is whatT2HK

cannot do

This is whatT2HK

can also do

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Conclusions: FNAL-PINGU?

FNAL-PINGU Megaton-size ice detector as upgrade of DeepCore with lower threshold; very

cost-efficient compared to liquid argon, water Unique mass hierarchy measurement through parameteric enhancement;

proton beams from main injector may just have right energy In principle, MH even with counting experiment measurable (compared to MH

determination using atmospheric neutrinos) Challenges on beam side (questions from PINGU meeting):

Tilt of beam line – feasibility, cost? Near detector necessary? Maybe not, if 10% systematics achievable … Beam bunching (to reduce atmospheric backgrounds)?NB: very low exposure required for MH; shorter decay pipe, one horn only, …?

Perspectives CP violation challenging (requires energy resolution, flavor identification), but

not in principle excluded; needs further study on detector side Measurement of Earth‘s core density, in principle, possible

(Tang, Winter, JHEP 1202 (2012) 028) Upgrades of PINGU discussed (MICA)

Truly unique and spectacular long-baseline experiment with no other alternative proposed doing similar physics!? The LBNE alternative if T2HK is going to be funded?

BACKUP

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NOvA+INO (atm.)?

(Blennow, Schwetz, arXiv:1203.3388)

MH, 3

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NF: Precision measurements?

… only if good enough energy resolution ~ 10% E and misID (cascades versus tracks) <~ 1% can be achieved!

Requires further study …

(Tang, Winter, JHEP 1202 (2012) 028)

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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)

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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)

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Effective volume

Difference Eth = 2 GeV, Veff=5 Mt to actual (energy-dependent) fiducial volume:

(Tang, Winter, JHEP 1202 (2012) 028)

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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

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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.!