Neutrino Oscillation Studies with the Fermilab NuMI beam: Episode III
• Historical Introduction: Pre-history, Episodes I and II • Physics Motivation • Off-axis Beams • Backgrounds and Detector Issues • Sensitivity of NuMI Off-axis Experiments
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Pre-history
Stage: Japan, early 1960’s Progress in Theoretical Physics: many papers by Nagoya group (Sakata and Co.), Kyoto group and others addressing issues:
• Fundamental symmetries of Nature Examples of • Conserved quantum numbers important cultural values • Leptons-hadrons symmetry [Prof. Yamada] • Bold predictions Not enough experimental input/feedback, Second neutrino just barely discovered
MNS: ν1 = cosϑνe + sinϑνµ
ν 2 =−sinϑνe +cosϑνµ
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Neutrino Mixing Leads to Interference Effects (Oscillations)
Components Amplitude of the initial state have different time evolution => Ψ(t) Ψ(0) Amplitude ∑ i 3-slit interference Experiment: mass difference Ù m2 −i i L difference in optical * 2E A = ∑Uαie U βi path length i June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Young Experiment
Three slit interference experiment
detector source A ~ eeikL12++ikL eikL3
I = A 2
I(x) – interference pattern is a result of phase differences due to optical path differences
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Neutrino Oscillations Primer
2 • P(νναβ→=) 0 if all masses are equal i.e. ∆ m ij = 0 Neutrino oscillations are sensitive to mass differences only.
• P(να →ν β ) oscillates as a function of L/E
• P(νναβ→≥) 0 for α ≠ β Appearance experiment.
• P(νναα→≤) 1 : disappearance experiment
• ∑ P()νναβ→=1 :total number of neutrinos is conserved β
•If Uαi is complex then PP ( ν α →≠ νν ββ ) ( → να) hence T (or CP) violation • Possible Majorana phases do not contribute to oscillations
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Episode I: Before the “New Era”
Theory: • Neutrino mass differences 1-100 eV2 • Neutrino mixing matrix similar to quarks (small or very small mixing angles) Experiment: • No evidence for neutrino oscillations in accelerator (BEBC, CDHS, CHARM, CCFR) or reactor (Bugey, Gosgen) experiments • Confusing ‘solar neutrino problem’
New Era started by “SuperK revolution”: • Neutrinos have mass, mass differences are very small • Neutrino mixing angles are very large
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Episode II: elucidation
Two frequencies of oscillations, large mixing angles, at least two of them:
2 -5 2 • ∆m12 ~ 7(?), 12(?) x 10 eV o • θ12 ~ 35 Interference of these • Super K, SNO, KamLand two amplitudes may lead to relatively large CP-
2 -3 2 violating effects • ∆m13 ~ 1.5 - 4x10 eV o • θ12 ~ 45 • SuperK, K2K, MINOS, OPERA, ICARUS
Dawn of physics beyond the Standard Model
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Neutrinos vs Standard Model
Whereas • There is a major effort to complete the Standard Model (Higgs search) • There is a broad front of experiments looking for possible deviations from the Standard Model (SUSY searches, B- physics experiments, g-2, EDM, …)
The first evidence for physics beyond the standard model is here: • Neutrino mass and oscillations
Where does it lead us? • Just an extension (additional 9? 7? Parameters) ? • First glimpse at physics at the unification scale ? (see-saw??) • Extra dimensions? • Unexpected? (CPT violation ???)
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Surprising pattern of mixing angles: WWSS?
• We have large mixing angles. How very interesting… I thought that mixing angles tend to be small… Hmm.. sin22θ is very close to 1 . 1 23 ν ≈±()νν µτ,22 3 Maximal mixing ÍÎ symmetry. What is this new symmetry of Nature?
2 2 2 •We have sin2θ12 and sin 2θ23 large, yet sin 2θ13 rather small. How very interesting… How small is it, really? What makes it so small? Protected by some new symmetry?? What symmetry?
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Three outstanding questions νe AD 2003 νµ ντ • Neutrino mass pattern: This ? Or that?
ν3 ν2 ν1 2 • Electron component ∆m atm 2 of ν3 (sin 2θ13) mass
ν2 ν1 ν3 2 ∆m sun “Normal” mass hierarchy “Inverted” mass hierarchy s BB ν1 • Complex phase of s ÍÎ CP ν νν= BBBν violation in a neutrino sector e µτ 2 ÅÆ (?) baryon number of the BBBν 3 universe
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab β and 0νββ decay experiments and mass hierarchy
2 ∆m sun ν ν2 3 •Coupling primarily to ν1 ν1 and ν2 ∆m2 ∆m22 atm •In case of inverted ∆matmatm hierarchy m ~ 50 meV required. Challenging.. ν2 ν ν1 •In case of normal 3 2 ∆m sun hierarchy required mass sensitivity in a 10 few meV range. Tough! 10
1 1 •Want to know the mass
-1 10 -1 pattern 10
-2 10 -2 10
-3 10 -3 10
-4 June 11, 2003 1st Yamada Symposium, NDM 2003 10 -4 -3 -2 -1 -4 10 10 10 10 1 10 10 -4 -3 -2 -1 Adam Para, Fermilab 10 10 10 10 1 10 The key: νµ ⇒νe oscillation experiment
P()ν µ →=ν e PP12++P3+P4
2 2 222 ∆13 BL± ∆mij P12= sin θ 3sin θ13 sin B 2 ∆=ij ; ± 2E 2 ν 22∆12 2AL P22= cos θθ3sin 12sin A 2 AG= 2;Fen ∆ ∆∆L AL B L 12 13 13 ± BA± = ± ∆13 ; PJ3 = cosδ cos sin sin AB± 222 J = cosθ13 sin 2θθ12 sin 2 13 sin 2θ23 ∆12 ∆∆13 13 L AL B± L PJ4 = sinδ sin sin sin AB± 222
22222 2 PL= fE(,sin 2θ13,δ ,sgn(∆m13 ) ∆∆m12 ,,m13 sin2θθ12 ,sin 2 23 ,,) 3 unknowns, 2 parameters under control L, E, neutrino/antineutrino Need several independent measurements to learn about underlying physics parameters
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Observations
22 1 1 sU= = sin2 θ ≈ sin2 2θ ≈ sin2 θ e3 13 4 13 2 µe • First 2 terms are independent of the CP violating parameter δ • The last term changes sign between ν and ν o •If θ13 is very small (≤ 1 ) the second term (subdominant oscillation) competes with 1st
•For small θ13, the CP terms are proportional to θ13; the first 2 (non-CP term) to θ13 Î
• The CP violating terms grow with decreasing Eν (for a given L) • CP violation is observable only if all angles ≠ 0 ¾ Two observables dependent on several physics parameters: need measurements at different L and E
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Telling the Mass Hierarchy: Neutrino Propagation in Matter
3 2 Solar { 1
2
<−−Atmospheric−−> } Solar 1 3
NORMAL INVERTED
• Matter effects reduce mass of νe and increase mass of νe 2 • Matter effects increase ∆m 23 for 2 normal hierarchy and reduce ∆m 23 for inverted hierarchy for neutrinos, opposite for antineutrinos
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Anatomy of Bi-probability ellipses
Minakata and Nunokawa, ~cosδ hep-ph/0108085 Observables are: •P δ •P Interpretation in terms 2 ~sinδ of sin 2θ13, δ and sign of 2 ∆m 23 depends on the value of these parameters and on the conditions of the experiment: L and E
2 sin 2θ13
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Varying the mixing angle..
• Parameter correlation: even very precise determination of Pν leads to a large allowed range of 2 sin 2θ23 Î antineutrino beam is more important than improved statistics
• CP violation effects (size of the
ellipse) ~ sin2θ13, overall 2 probability ~ sin 2θ13 Îrelative effect very large
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Receipe for an νe Appearance Experiment
• Large neutrino flux in a signal region
• Reduce background (neutral currents, intrinsic νe) • Efficient detector with good rejection against NC background • Large detector
Lucky coincidences: • distance to Soudan = 735 km, ∆m2=0.025-0.035 eV2 1.27∆∆mL22π 2.54 mL • =⇒EG= ≈1.6 −2.2 eV=> ‘large’ cross section E 2 π • Below the τ threshold! (BR(τ->e)=17%)
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab νe Appearance Counting Experiment: a Primer
beam #.of νεeecand −−νηNC P = This determines εσdEΦ ()E CC ()E P (E,100%) ∫ νν νµ →νe sensitivity of the experiment 1.28 εν beam +ηNC Psens = e 90%CL ε dEΦ ()E σ CC (E)PE( ,100%) ∫ ν ννµ →νe
Systematics: •Know your expected flux •Know the beam contamination •Know the NC background*rejection power (Note: need to
beat it down below the level of νe component of the beam only) •Know the electron ID efficiency
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Off-axis NuMI Beams: unavoidable byproduct of MINOS experiment
800 900 800 700 700 600
600 500 500 400 400 300 300 200 200 100 100 0 0 0246810 0246810
60 450 400 50 350 40 300 250 30 " 200 150 20 100 10 50 0 0 0246810 0246810
•Beam energy defined by the detector position (off-axis, Beavis et al) •Narrow energy range (minimize NC-induced background) •Simultaneous operation (with MINOS and/or other detectors) •~ 2 GeV energy : •Below τ threshold • Relatively high rates per proton, especially for antineutrinos •Matter effects to amplify to differentiate mass hierarchies •Baselines 700 – 1000 km June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab NuMI Challenge: “have” beam, need a new detecor • Surface (or light overburden) High rate of cosmic µ’s Cosmic-induced neutrons •But: Duty cycle 0.5x10-5 Known direction Observed energy > 1 GeV Principal focus: electron neutrinos identification • Good sampling (in terms of radiation/Moliere length) Large mass: • maximize mass/radiation length •cheap Off-axis collaboration: Letter of Intent 2002, Proposal in preparation (October 2003), forthcoming workshops at Fermilab: July 10-12, September 11-13
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab NuMI Off-axis Detector
Low Z imaging calorimeter: – Glass RPC or – Liquid or solid scintillator Electron ID efficiency ~ 40% while keeping NC background below intrinsic νe level Well known and understood detector technologies Primarily the engineering challenge of (cheaply) constructing a very massive detector
How massive??
50 kton detector, 5 years run => 2 • 10% measurement if sin 2θ13 at the CHOOZ limit, or 2 •3σ evidence if sin 2θ13 factor 10 below the CHOOZ limit (normal hierarchy, δ=0), or • Factor 20 improvement of the limit
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Backgrounds Summary
νe component of the beam – Constrained by νµ interactions observed in the near MINOS detector (π)
– Constrained by νµ interactions observed in the near MINOS detector (µ) – Constrained by pion production data (MIPP) NC events passing the final analysis cuts (π0?) – Constrained by neutrino data from K2K near detector – Constrained by the measurement of EM ‘objects’ as a function of Ehad in the dedicated near detector • Expected to Cosmics be very small – Cosmic muon induced ‘stuff’ overlapped with the beam-induced •Measured in a neutrino event dedicated setup – (undetected) cosmic muon induced which mimics the 2 GeV (under electron neutrino interaction in the direction from Fermilab within 10 µsec beam gate construction)
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Beam-Detector Interactions
• Optimizing beam can improve signal • Optimizing beam can reduce NC backgrounds
• Optimizing beam can reduce intrinsic νe background – Easier experimental challenge, simpler detectors • # of events ~ proton intensity x detector mass – Allocate the re$ources to maximize the product, rather than individual components
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab NuMI and JHF experiments in numbers
NuMI Off-axis JHF to SK 50 kton, 85% eff, Phase I, 5 years 5 years, 4x1020 pot/y all After cuts all After cuts
νµ CC (no osc) 28348 6.8 10714 1.8 NC 8650 19.4 4080 9.3
Beam νe 604 31.2 292 11
2 Signal (∆m 23=2.8/3 x 867.3 307.9 302 123 10-3, NuMI/JHF) FOM (signal/µbckg) 40.7 26.2
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Two phase program
Phase I (~ $100-200 M, running 2007 – 2014) • 50 kton (fiducial) detector with ε~35-40% •4x1020 protons per year
• 1.5 years neutrino (6000 νµ CC, 70-80% ‘oscillated’)
• 5 years antineutrino (6500 νµ CC, 70-80% ‘oscillated’)
Phase II ( running 2014-2020) • 200 kton (fiducial) detector with ε~35-40% •20x1020 protons per year (new proton source?)
• 1.5 years neutrino (120000 νµ CC, 70-80% ‘oscillated’)
• 5 years antineutrino (130000 νµ CC, 70-80% ‘oscillated’)
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Determination of mass hierarchy: complementarity of JHF and NuMI
0.05 Combination of different baselines: 0.045 NuMI + JHF extends the range of 0.04
0.035 hierarchy discrimination to much
0.03 lower angles mixing angles
0.025
0.02
0.015 6 0.01 ∆ 2 m 13 > 0 2 0.005 5 ∆ m 13 < 0
0 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 4 ) [%] e ν
→
µ 3 ν
2 NuMI P(
1 EJHF = 0.6 GeV ENuMI = 1.5 GeV Minakata,Nunokawa, 0 0123456 Parke JHF P(ν → ν ) (%) June 11, 2003 1st Yamada Symposium, NDM 2003 µ e Adam Para, Fermilab Physics related to neutrino masses
A quest for a neutrino mass spectrum ÍÎ mass generation mechanisms: •Neutrinos have non-zero mass
• 0.05 < m3< 0.23 eV • Mass differences too small to be detectable by direct measurements Î interference experiments [ remember 0 O ∆mK=m(K S)-m(K L) ]
A search for fundamental symmetries: • Conserved ‘family lepton’ number •Conserved lepton number • CP conservation in a lepton sector ÍÎ leptogenesis ÍÎ baryon number of the Universe ÍÎour existence • CPT conservation • New, hereto unknown symmetries of Nature?
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Conclusions
Neutrino Physics is an exciting field for many years to come Most likely several experiments with different running conditions will be required to unravel the underlying physics. Healthy complementary program is shaping up (see Ichikawa-san). Fermilab/NuMI beam is uniquely matched to this physics in terms of beam intensity, flexibility, beam energy, and potential source-to-detector distances that could be available Important element of the HEP program in the US for the next 20 years
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab NuMI Of-axis Sensitivity for Phases I and II
6 6 6
5 5 5
4 4 4
3 3 3
2 2 2
1 1 1
0 0 0 -3 -2 -3 -2 -3 -2 10 10 10 10 10 10
We take the Phase II to 6 6 6 have 25 times higher POT x 5 5 5
Detector mass 4 4 4
3 3 3
Neutrino energy and 2 2 2 detector distance remain 1 1 1 the same 0 0 0 -3 -2 -3 -2 -3 -2 10 10 10 10 10 10
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Two body decay kinematics
At this angle, 15 mrad, energy of produced neutrinos is 1.5-2 GeV for all pion energies Î very intense, narrow band beam
‘On axis’: Eν=0.43Eπ
** * ppL =+γθ(cos βE) ** ppT = sinθ
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Signal and background
Fuzzy track = electron Clean track = muon (pion)
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Background examples
0 NC - π0 - 2 tracks νµ CC - with π - muon
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Sources of the νe background
νe/νµ ~0.5% All
0.45 0.3 0.4 K decays 0.25 0.35
0.3 0.2 0.25 0.15 0.2 At low energies the dominant 0.15 0.1 0.1 background is from 0.05 0.05 + + 0 0 µ Æe +νe+νµ decay, hence 0 5 10 15 20 0 5 10 15 20 Enu/enubar, R=0 Enu/enubar, R = 5 km ¾ K production spectrum is 0.16 0.06 0.14 not a major source of 0.05 0.12 systematics 0.1 0.04 0.08 0.03 ¾ ν background directly 0.06 e 0.02 0.04 related to the νµ spectrum 0.01 0.02
0 0 at the near detector 0 5 10 15 20 0 5 10 15 20
Enu/enubar, R = 10 km Enu/enubar, R = 20 km
June 11, 2003 1st Yamada Symposium, NDM 2003 Adam Para, Fermilab Mass Textures and θ13 Predictions, Examples
perturba Texture θ sin22θ 13 13 tions
11−ε Degenerate 1/2 δ − ∆m2 ε δ 22 neutrinos, sun ~0.064 ≈ 2 11++η 1ηε− ∆matm m − spontaneously 22 2 broken flavor 11−+ε ηε−1+η−2ε SO(3) ≈ 0 ε δ 2 22 Degenerate 1/2 1 0 0 111 neutrinos, m ≈ e mr0 1 0++111 δ mdemocratic m ~0.019 ν µ mass matrix 0 0 1 111
δ −11 ∆m2 ≈ sun ~0.001 η δ Inverted ∆2 m −1 η η atm 1 η η hierarchy 2 ∆msun η δ 2 <<0.001 ∆atm
1/2 2 δ εε ∆msun η < δε≈ ≈ ~0.064 Normal ∆2 m ε 11++ηη atm 1/3 hierarchy 2 2 ∆msun ε 11++ηη ≈ ~0.26 δε≈ η= 0 ∆2 June 11, 2003 1st Yamada Symposium, NDM 2003atm Adam Para, FermilabAltarelli,Feruglio, hep-ph/0206077