Transcript Neutrino beam to PINGU?

Neutrino beam to PINGU?
BeyondDC workshop
NIKHEF Amsterdam
March 19-20, 2011
Walter Winter
Universität Würzburg
Contents
 Introduction:
Neutrino oscillations
 Matter effects
 Physics with a very long baseline
 Beam options, detector requirements
 PINGU as a far detector?
 Summary
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Introduction:
Neutrino oscillations
Neutrino production/detection
 Neutrinos are only produced and detected
by the weak interaction:
e, m, t
Electron  electron neutrino ne
Muon  muon neutrino nm
Tau  Tau neutrino nt
W exchange particle
(interaction)
Interaction with
SU(2) symmetry
partner only
ne, nm, nt
Production as
flavor state
 The dilemma: One cannot assign a mass to
the flavor states ne, nm, nt!
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Which mass do the ns habe?
 There is a set of neutrinos n1, n2, n3, for
which a mass can be assigned.
 Mixture of flavor states:
sin22q13=0.1, d=p/2
 Not unusual, know from the Standard Model for quarks
 However, the mixings of the neutrinos are much larger!
5
Three flavor mixing
 Use same parameterization as for CKM matrix
Potential CP violation ~ q13
(sij = sin qij cij = cos qij)
=
(
)(
x
)(
x
)
Pontecorvo-Maki-Nakagawa-Sakata matrix
 If neutrinos are their own anti-particles
(Majorana neutrinos) U  U diag(1,eia,eib)
(do not enter neutrino oscillations)
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Three active flavors: Masses
 Two independent mass squared splittings, typically
(solar)
(atmospheric)
 The third is given by
 The (atmospheric) mass
ordering (hierarchy) is
unknown (normal or inverted)
 The absolute neutrino mass
scale is unknown (< eV)
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Normal
Inverted
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Neutrino oscillations (two flavors)
 If only two flavors:
Lower limit for neutrino mass!
 Disappearance or
survival probability
Appearance probability
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Three flavors: Simplified
 What we know (qualitatively):
 Hierarchy of mass splittings
 Two mixing angles large, one (q13) small ~ 0?
 One obtains then (in vacuum)
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Two flavor limits
Two flavor limits by selection of frequency:
 Atmospheric frequency: D31 ~ p/2  D21 << 1
 Solar frequency: D21 ~ p/2  D31 >> 1
averages
out
Select sensitive term
by choice of L/E!
0.5
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Example: MINOS
 Running experiment in the US
for the precision measurement
of atmospheric parameters
Beam line (Protons)
Near detector: 980 t
Far detector: 5400 t
735 km
Source: MINOS
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Three flavors: Summary
(Schwetz, Tortola, Valle, 2008-)
 Three flavors: 6 params
(3 angles, one phase; 2 x Dm2)
Atmospheric
oscillations:
Amplitude: q23
Frequency: Dm312
Coupling: q13
Solar
oscillations:
Amplitude: q12
Frequency: Dm212
Suppressed
effect: dCP
(Super-K, 1998;
Chooz, 1999;
SNO 2001+2002;
KamLAND 2002)
 Describes solar and atmospheric neutrino
anomalies!
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Most interesting quantities
in the future?
 The value of q13  Three-flavor effects
 q13 sensitivity (exclusion limit if no signal)
 q13 discovery reach/discovery potential
 CP violation  Leptogenesis?
(Pascoli, Petcov, Riotto, hep-ph/0611338 )
 Mass ordering  Lepton flavor structure?
 Deviation from tribimaximal mixings?
 Deviations q23-p/4
 Deviations sin2q12 – 1/3
 In particular interesting in combination with q13=0!
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Quantification of performance
Example: CP violation discovery
Best performance
close to max.
CPV (dCP = p/2 or
Sensitive
region as a
function of true
q13 and dCP
3p/2)
dCP values
now stacked
for each q13
No CPV discovery if
dCP too close to 0 or p
3s
~ Precision in
quark sector!
Read: If
sin22q13=10-3,
No CPV discovery for
all values of dCP
we
expect a
discovery for 80%
of all values of dCP
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Artificial neutrino sources
There are three possibilities to artificially produce
neutrinos
 Beta decay:
 Example: Nuclear reactors, beta beams
 Pion decay:
Superbeam
 From accelerators:
Pions
Protons
Target
Selection,
focusing
Muons,
neutrinos
Decay
tunnel
Neutrinos
Absorber
 Muon decay:
 Muons produced by pion decays! Neutrino Factory
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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 q13 (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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Degeneracies
 CP asymmetry
Iso-probability curves
b-beam/NF, n
(vacuum) suggests
the use of neutrinos
and antineutrinos
 One discrete deg.
remains in (q13,d)-plane
b-beam/NF, antin
Best-fit
(Burguet-Castell et al, 2001)
 Additional degeneracies:
(Barger, Marfatia, Whisnant, 2001)
 Sign-degeneracy
(Minakata, Nunokawa, 2001)
 Octant degeneracy
(Fogli, Lisi, 1996)
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Degeneracy resolution
 Matter effects (signdegeneracy) – long
baseline, high E
 Different beam energies
or better energy
resolution in detector
LBNE, T2KK,
NF/BB@long L, …
 Second baseline
T2KK, magic baseline ~
7500 km, SuperNOvA
Neutrino factory, beta
beam, Mton WC
SB+BB CERN-Frejus,
silver/platinum @ NF
Reactor, atmospheric,
astrophysical, …
 High statistics
 Other channels
 Other experiment
classes
Monochromatic beam, Beta
beam with different
isotopes, WBB, …
(many many authors, see e.g. ISS physics WG report, Euronu reports)
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Perspectives for CP violation
Euronu report,
arXiv:1005.3146
Will serve as
reference setup
(later in this talk)
Generation 3?
NuFact
BB g>350
Generation 2?
LBNE
T2HK
T2KK
SPL
Generation 1:
Double Chooz
Daya Bay
T2K
NOvA
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Matter effects
Matter effect (MSW)
(Wolfenstein, 1978;
 Ordinary matter:
Mikheyev, Smirnov,
electrons, but no m, t
1985)
 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)
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Matter profile of the Earth
… as seen by a neutrino
Inner
core
(PREM: Preliminary Reference Earth Model)
Core
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Beams to PINGU?
 Labs/detector locations (stars) considered for
Neutrino Factory:
All these baselines cross the Earth‘s outer core!
(Agarwalla, Huber, Tang, Winter, 2010)
FNAL-PINGU: 11620 km
CERN-PINGU: 11810 km
RAL-PINGU: 12020 km
JHF-PINGU: 11370 km
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Parameter mapping (two flavors)
 Oscillation probabilities in
vacuum:
matter:
Matter resonance:
In this case:
- Effective mixing maximal
- Effective osc. frequency
minimal
Resonance energy:
For nm appearance, Dm312:
- r ~ 4.7 g/cm3 (Earth’s
mantle): Eres ~ 7 GeV
- r ~ 10.8 g/cm3 (Earth’s outer
core): Eres ~ 3 GeV
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Mantle-core-mantle profile
(Parametric enhancement: Akhmedov, 1998; Petcov, 1998)
 Probability for CERN-PINGU (numerical)
Core
resonance
energy
Is that
part
useful?
Threshold
effects
expected at:
Interference
2 GeV
Mantle
resonance
energy
5 GeV
10 GeV
Beam energy
and detector thresh. have
to pass these!
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 Comparison
matter (solid)
and vacuum
(dashed)
 Event rate
(n, NH)
hardly drops
with L
Event rates
(A.U.)
Baseline dependence
Peak neutrino energy ~ 14 GeV
(Freund, Lindner, Petcov, Romanino, 1999)
(Dm212  0)
NH matter effect
Vacuum, NH or IH
NH matter effect
Can a much larger
detector mass compensate
for this disadvantage?
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Physics with a very long
baseline
Risk minimization
 Complemenary mesurement (physics):
measures q13, MH only
 Insurance against anything (?)
which can go wrong:




New physics
Systematics
Luminosity
Unfortunate part of parameter
space (degeneracies – see before)
 Risk minimizer!
(Ribeiro et al, 2007)
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MSW effect, even for q13=0
 For long enough
baselines, solar
term large
enough to verify
MSW even for
q13=0
(Winter, Phys. Lett. B613 (2005) 67)
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Neutrino geophysics?
Source: Neutrino factory from Fermilab
Outer core
shadow
Inner core
shadow
1s,
sin22q13=0.01
(Winter,
Phys. Rev. D72
(2005) 037302)
 Measurement of the
density of the Earth‘s
core at the level of
1%
 Can PINGU be
used? No other
currently discussed
option can do that!
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Beam options,
detector requirements
Superbeam to PINGU?
Pions
Protons
Target
Selection,
focusing
Neutrinos
Decay
tunnel
Absorber
 Three problems:
 Energy (need to pass 5 GeV or 10 GeV for
MSW enhancement)
 Electron neutrino flavor identification
(cascades not flavor-clean)
 Statistics. Example: LBNE (200kt WC)
Disapp: 9700 (1300 km)  171 (11814 km)
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Neutrino factory – IDS-NF
~ 7500 km
IDS-NF:
 Initiative from ~ 2007-2013
to present a design report,
schedule, cost estimate,
risk assessment for a
neutrino factory
 Current status: Interim
Design Report (2011)
including details of how
costing will be done
~ 4000 km
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Neutrino factory to PINGU?
(Geer, 1997; de Rujula, Gavela, Hernandez, 1998;
Cervera et al, 2000)
Signal prop. sin22q13
Contamination
 Main issue: charge identification (CID)
 Typically requires
magnetized detector
 However: also no or
partial CID has been
discussed in literature
(Huber, Schwetz, 2008)
 Then: energy resolution
important!
 Use parametric resonance?
(liquid argon, 1300km)
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Beta beams
(CERN layout; Bouchez, Lindroos, Mezzetto, 2003; Lindroos, 2003; Mezzetto, 2003; Autin et al, 2003)
(Zucchelli, 2002)
Prod.
ring?
g
He 36 Li e  n
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18

10 Ne 9 Fe e n
6
2
 Key figure (any beta
beam):
Useful ion decays/year?
 Often used “target
values” (EURISOL):
3 1018 6He decays/year
1 1018 18Ne decays/year
 Typical g ~ 100 – 150
(for CERN SPS)
Possible/recent modifications:
 Higher g (Burguet-Castell et al, hep-ph/0312068)
 Different isotope pairs leading to
higher neutrino energies (same g)
(C. Rubbia, et al, 2006)
(http://ie.lbl.gov/toi)
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Beta beam to PINGU?
 Flavor-clean ne beam
 Flavor identification only for nm required
(ne  nm oscillation channel)
 High enough energies, in principle,
achievable for 8B, 8Li (high g)
 High enough intensities, in principle,
achievable with production ring technology?
( FP7-funded Euronu design study)
 Mainly discussed in context of upgraded
CERN-SPS
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Isotopes compared
 Example: Unoscillated spectrum for CERN-INO (India)
(E0 ~ 14 MeV)
(E0 ~ 4 MeV)
g
(from Agarwalla, Choubey, Raychaudhuri, 2006)
Peak En ~ g E0
Max. En ~ 2 g E0
(E0 >> me assumed;
E0: endpoint energy)
 Total flux ~ Nb g2 (forward boost!) (Nb: useful ion decays)
 Combine high statistics (CPV, He/Ne) with high E (MH, B/Li)?
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PINGU as a beta beam
far detector?
Reference setup
(Choubey, Coloma, Donini,
Fernandez-Martinez, 2009)
 Reference setup:
and 6He, g=350,
to 500kt water
Cherenkov detector at
L=650 km
 8B and 8Li, g=656 and
390, to 50kt iron
detector at L=7000 km
 1019 useful decay per
year (all ions)

18Ne
• Considered as good compromise
between mass hierarchy and CP violation
measurements
(see also Agarwalla, Choubey, Raychaudhuri, Winter, 2008)
• Discussed in context with CERN-SPS upgr.
• Theoretical idea pushing the technology
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What if one used PINGU
as a second detector?
Reference
setup
Ref. setup
without 2nd
baseline
Figs:
Jian
Tang
PINGU
(aggressive):
5 Mton fid.
mass above
2 GeV;
50%*E energy
resolution;
10-5 flavor
mis-ID
(Cervera, Koskinen, Tang, Winter, work in progress)
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Detector requirements (1)
 Flavor-misidentification
(essentially probability to reconstruct a cascade from ne as muon
track x fid. mass ne cascades/fid. mass muon tracks)
 misID ~ 10-3 should be target
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Detector requirements (2)
 Energy threshold (5 Mt above threshold)
 2 GeV optimal (core peak covered),
5 GeV possibly tolerable,
10 GeV beyond mantle resonance
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Detector requirements (3)
 Energy resolution
 Works, in principle, with total rates only
 However, energy resolution helps
 Need „migration matrix“ Eincident  Ereconstr
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Detector requirements (4)
 Fiducial mass
 1 Mt minimum
 Higher masses have some impact
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Detector requirements
(educated guess - summary)
 For good sensitivities, need:




At least 1 Mton above 2 GeV
A few Mtons above 5 GeV
Some energy information
Contamination of muon track data sample with
no more than a fraction of 10-3 of the cascades
(NC and CC) from ne  Cuts?
(for same fiducial volume/efficiency)
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Wish list
 Fiducial mass muon tracks as a fct. of energy
 Fiducial mass cascades as a function of
energy, possibly separated by interaction
type (CC, NC) and flavor
 „Migration matrix“ Eincident  Ereconstr
 Probability to mis-ID cascade as muon track;
or corresponding migration matrix
(see GLoBES manual, Sec. 11.5,
http://www.mpi-hd.mpg.de/personalhomes/globes/documentation.html)
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Summary
 A very long baseline is a key component e.g. of a
neutrino factory program or a high energy beta
beam program
 Interesting option to discuss the option to use PINGU
as a far detector
 Beam options: beta beam probably most
promising. However: is there some possibility for
(at least) some CID? – neutrino factory!
 Energy threshold determined by MSW effect in
Earth matter; oscillation physics with sub-GeV
neutrinos?
 Need input for more dedicated studies to
establish the physics case
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BACKUP
Neutrino oscillation probability
Standard derivation N active, S sterile (not weakly interacting) flavors
 Mixing of flavor
states
 Time evolution of
mass state
 Transition amplitude

Transition probability
„quartic re-phasing invariant“
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Further simplifications
 Ultrarelativistic approximations:
L: baseline (distance source-detector)
 Plus some manipulations:
„mass squared difference“
F(L,E)=L/E
„spectral dependence“
 For antineutrinos: U  U*
50
New reactor experiments
Examples: Double Chooz, Daya Bay
Identical detectors, L ~ 1.1 km
(Source: S. Peeters, NOW 2008)
51
GLoBES software
(General Long Baseline Experiment Simulator)
GLoBES
AEDL
User Interface
„Abstract Experiment
Definition Language“
C library,
reads AEDL files
AEDL files
Define and modify
experiments
(Huber, Lindner, Winter, 2004; Huber,
Kopp, Lindner, Rolinec, Winter, 2007)
http://www.mpi-hd.mpg.de/
lin/globes/
Functionality for
experiment simulation
Application software
linked with user interface
Calculate sensitivities …
Online now: GLoBES 3.1.8 (improved Mac support, new API functions, bug fixes, etc.)
52
Numerical evaluation
 Evolution operator method:
H(rj) is the Hamiltonian in
constant density
 Note that in general
 Additional information by interference effects
compared to pure absorption phenomena
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Current status: A variety of ideas
 “Classical” beta beams:
 “Medium” gamma options (100 < g < ~350)
- Alternative to superbeam!
- Possible at SPS (+ upgrades)  use existing infrastructure
- Usually: Water Cherenkov detector (for Ne/He)
(Burguet-Castell et al, 2003+2005; Huber et al, 2005; Donini, Fernandez-Martinez, 2006;
Coloma et al, 2007; Winter, 2008; Choubey et al, 2009; Fernandez-Martinez, 2009; Peltoniemi,
2009; Coloma et al, 2010)
 “High” gamma options (g >> 350)
- Require large accelerator (Tevatron or LHC-size)
- Water Cherenkov detector or TASD or MIND? (dep. on g, isotopes)
(Burguet-Castell et al, 2003; Huber et al, 2005; Agarwalla et al, 2005, 2006, 2007, 2008, 2008;
Donini et al, 2006; Meloni et al, 2008; Agarwalla, Huber, 2009)
 Hybrids:
 Beta beam + superbeam
(CERN-Frejus; Fermilab: see Jansson et al, 2007)
 “Isotope cocktail” beta beams (alternating ions)
(Donini, Fernandez-Martinez, 2006)
 Classical beta beam + Electron capture beam etc
(Bernabeu et al, 2009; Orme, 2009)
 …
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BB Isotopes compared
 Examples for isotopes
 Want same neutrino energies
(=same X-sections, L, physics):
Peak energy ~ g E0, flux ~ Nb g2
 Use high g and isotopes with small E0
or low g and isotopes with large E0
for same total flux
(exact for me/E0 << 1)
 Example (table):
Nb(B/Li) ~ 12 Nb(He/Ne) , g(He/Ne) ~ 3.5 g(B/Li)
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