neutrino physics with icecube deepcore-pingu … and comparison with alternatives
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Neutrino physics with IceCube DeepCore-PINGU … and comparison with alternatives. TeVPA 2012 TIFR Mumbai, India Dec 10-14, 2012 Walter Winter Universität Würzburg. TexPoint fonts used in EMF: A A A A A A A A. Contents. Introduction Oscillation physics with Earth matter effects - PowerPoint PPT PresentationTRANSCRIPT
TeVPA 2012
TIFR Mumbai, IndiaDec 10-14, 2012
Walter WinterUniversität Würzburg
Neutrino physics with IceCube DeepCore-PINGU
… and comparison with alternatives
2
Contents
Introduction Oscillation physics with Earth matter
effects Mass hierarchy determination with PINGU
Neutrino beam to PINGU? Atmospheric neutrinos
Comparison with alternatives, and outlook Summary
3
Atmospheric neutrino anomaly
The rate of neutrinos should be the same from below and above
But: About 50% missing from below
Neutrino change their flavor on the path from production to detection: Neutrino oscillations
(Super-Kamiokande: “Evidence for oscillations of atmospheric neutrinos”, 1998)
4
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)
5
(also: T2K, Double Chooz, RENO)
(short baseline)
6
Consequences of large 13
13 to be well measured by Daya Bay
Mass hierarchy: 3 discovery for up to 40% of all CP possible iff ProjectX, possiblyuntil 2025
CP violation measurement extremely difficultNeed new facility!
Huber, Lindner, Schwetz, Winter, 2009
Oscillation physics withEarth matter effects
8
Matter profile of the Earth… as seen by a neutrino
(PR
EM
: Prelim
inary R
eference E
arth M
odel)
Core
Innercore
(not to scale)
9
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)
10
Parameter mapping… for 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 ~ 6.4 GeV- ~ 10.8 g/cm3 (Earth’s outer core): Eres ~ 2.8 GeV
Resonance energy:
MH
11
Mantle-core-mantle profile
Probability for L=11810 km (numerical)
(Parametric enhancement: Akhmedov, 1998; Akhmedov, Lipari, Smirnov, 1998; Petcov, 1998)
Core resonance
energy
Mantleresonance
energy
Param.enhance-
ment
Thresholdeffects
expected at:2 GeV 4-5 GeV
Naive L/E scalingdoes not apply!
Parametric enhancementthrough mantle-core-mantle
profile of the Earth.Unique physics potential!
!
Mass hierarchy determination with PINGU
13
What is PINGU?(“Precision IceCube Next Generation Upgrade“)
Fill in IceCube/DeepCore array with additional strings Drive threshold to
lower energies
LOI in preparation
Modest cost ~30-50M$ (dep. on no. of strings)
Two season deployment anticipated: 2015/2016/2017
(PINGU, 12/2012)
14
PINGU fiducial volume?
A ~ Mt fiducial mass for superbeam produced with FNAL main injector protons (120 GeV)
Multi-Mt detector for E > 10 GeV atmospheric neutrinos
Fid. volume depends on trigger level (earlier Veff higher, which is used for following analyses!)
LBNE-likebeam
Atm. neutrinos
(PINGU, 12/2012)
15
Mass hierarchy measurement:statistical significance (illustrated)
Source (spectrum, solid angle)
Osc. effect (in matter)
Detector mass
Crosssection
~ E
Atmospheric neutrinosarXiv:1210.5154
BeamsM. Bishai
x
> 2 GeV
> 5 GeV
x x
Coreres.
Measurement at threshold application rather for future upgrades: MICA?
16
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!
17
Example:
“Low-intensity“ superbeam? 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 may allow for shorter decay pipe
Advantage: Peaks in exactly the right energy range for the parametric enhancement
Include all irreduciblebackgrounds (intrinsic beam, NC, hadronic cascades), 20% track mis-ID
M. Bishai
18
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
(for Veff 03/2012)
>18 (stat. only)
19
Mass hierarchy with a beam
Very robust mass hierarchy measurement (as long as either some energy resolution or control of systematics)
(Daya B
ay best-fit; current param
eter un
certainties includ
ed; b
ased on
Tang, W
inter, JH
EP
1202 (2012) 028 )
GLoBES 2012
All irreducible backgrounds included
20
Atmospheric neutrinos
Neutrino source available “for free“
Source not flavor-clean different channels contribute and mask effect
Power law spectrum
A. Smirnov
Many different baselines at once, weighted by solid angle
Detector: angular+energy resolution required!
arXiv:1210.5154
Akhmedov, Razzaque, Smirnov, 2012
21
Mass hierarchy with atmospheric neutrinos
Akhmedov, Razzaque, Smirnov, 2012
Statistical significance depends on angular and energy resolution
About 3-10 likely for reasonable values
Final proof of principle will require event reconstruction techniques (in progress)
Comparison with alternatives
… and outlook
23
Mass hierarchy
PINGU completed by beginning of 2017?
No “conventional“ atm. neutrino experiment could be built on a similar timescale or at a similar cost Bottleneck: Cavern!
3, Project X and T2K with proton driver, optimized neutrino-antineutrino run plan
Huber, Lindner, Schwetz, Winter, JHEP 11 (2009) 44
PINGU2018-2020?
Ak
hm
edov, R
azzaqu
e, Sm
irnov, 2012; v5
3
24
Probabilities: CP-dependence
There is rich CP-phenomenology:
NH
L=11810 km
25
Upgrade path towards CP? Measurement of CP
in principle possible, but challenging
Wish list: Electromagnetic
shower ID (here: 1% mis-ID)
Energy resolution (here: 20% x E)
Maybe: volume upgrade(here: ~ factor two)
Project X Currently being
discussed in the context of further upgrades - MICA; requires further study PINGU as R&D exp.?
= LBNE + Project X!
Tang, Winter, JHEP 1202 (2012) 028
same beamto PINGU
26
Matter density measurementExample: LBNE-like Superbeam
Precision ~ 0.5% (1) on core density
Complementary to seismic waves (seismic shear waves cannot propagate in the liquid core!)
from: Tang, Winter, JHEP 1202 (2012) 028;see also: Winter, PRD72 (2005) 037302; Gandhi, Winter, PRD75
(2007) 053002; Minakata, Uchinami, PRD 75 (2007) 073013
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Conclusions: 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 MSW effect in Earth matter Atmospheric neutrinos:
Neutrino source for free, many different baselines Requires energy and angular resolution (reconstruction work in progress) PINGU to be the first experiment to discover the mass hierarchy at 3-5?
Neutrino beam: Requires dedicated source, with relatively low intensity Proton beams from FNAL main injectior have just right energy to hit mantle-
core-mantle parameteric enhancement region Even possible as counting experiment, no angular resolution needed
Beyond PINGU: CPV and matter density measurements perhaps possible with beam to even denser array (MICA)? PINGU as R&D experiment; worth further study!
Technology also being studied in water ORCA
BACKUP
29
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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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
1.0?
31
Want to study e- oscillations with different sources: 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)
Detector requirements
13, CP
13, CP
13, CP
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Detector parameterization(low intensity superbeam)
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)
33
Many proposals for measuring CP violation with a neutrino beam
Require all a dedicated (new) detector + control of systematics
Measurement of CP?
Coloma, Huber, Kopp, Winter, 2012