The Physics of Neutrinos from Accelerator Beams (Part 1)
Ryan Patterson Caltech
International Neutrino Summer School Fermilab August 14, 2017 Physics with accelerator neutrino experiments
. Neutrino oscillations with conventional beams Will spend most of my time here. . Searches for new physics and/or use of other sorts of accelerator 휈 sources Will spend some time on this tomorrow. . Physics unrelated to neutrinos but accessible in these experiments Will say a few words on this tomorrow. . Neutrino scattering Covered by S. Bolognesi lectures. . Detector R&D A little out of scope, but may say a few words here and there.
Today: - Brief reminder about v beams - Neutrino oscillations landscape (as connected to accelerator experiments) - Recent and current long-baseline experiments Tomorrow: planned experiments, searches for new physics, other beam sources
Ryan Patterson 2 Accelerator Neutrinos @ INSS 2017 Conventional beams
Ryan Patterson 3 Accelerator Neutrinos @ INSS 2017 NuMI neutrinos proton beams Example Neutrino (onward to MINOS and decay regions Complex (FNAL) NOvA far detectors) neutrino beams BNB neutrinos MINOS ND, NOvA ND, MINERvA, ArgoNeuT
MiniBooNE, MicroBooNE, ICARUS
SciBooNE, SBND BNB target NuMI target 8 GeV Booster supplies Booster Neutrino Beam (BNB)
120 GeV MI feeds Neutrinos from the MI (NuMI) beam
Ryan Patterson 4 Accelerator Neutrinos @ INSS 2017 NuMI beamline (FNAL)
Ryan Patterson 5 Accelerator Neutrinos @ INSS 2017 T2K beamline (J-PARC)
Ryan Patterson 6 Accelerator Neutrinos @ INSS 2017 CNGS beamline (CERN)
Ryan Patterson 7 Accelerator Neutrinos @ INSS 2017 Booster beamline (FNAL)
Ryan Patterson 8 Accelerator Neutrinos @ INSS 2017 NuMI horn
Booster neutrino beamline horn First accelerator neutrino result: discovery that 휈휇 ≠ 휈e
Ryan Patterson 12 Accelerator Neutrinos @ INSS 2017 Discovery of the weak neutral current (Gargamelle at CERN, 1970s)
Ryan Patterson 13 Accelerator Neutrinos @ INSS 2017 Bubble chamber on Many neutrino display at Fermilab scattering experiments
“NAL”’s neutrino line
Bubble chamber manual event reconstruction being performed
NuTeV (relatively recent)
Ryan Patterson 14 Accelerator Neutrinos @ INSS 2017 Tunable beamlines: NuMI example here (change horn currents and relative positions of target, horns)
Ryan Patterson 15 Accelerator Neutrinos @ INSS 2017 Proton-nucleus interactions: not very well measured at relevant energies Need to know: - multiplicity distributions of each species
- angular and momentum distribution, e.g., (pz, xF) or (pz, pT) or … 휋+ … 휋+ proton from accelerator complex … K- target (carbon, beryllium, tungsten, …)
Ryan Patterson 16 Accelerator Neutrinos @ INSS 2017 Timing to reject beam-unrelated backgrounds (MiniBooNE timing example shown)
“Duty cycle” = fraction of time the beam is on. NuMI as an example: 10 휇s pulse every 1.3 s ⇒ 8⨯10-6 duty cycle
Ryan Patterson 17 Accelerator Neutrinos @ INSS 2017 Pause for questions/discussion
Ryan Patterson 18 Accelerator Neutrinos @ INSS 2017 Current landscape of 3휈 mixing
(as accessible by accelerator neutrinos)
Ryan Patterson 19 Accelerator Neutrinos @ INSS 2017 Why so light? H t Z W
b 휏 c
s 휇
d u
e
mass (GeV) mass
mass (GeV) mass
oscillations
cosmo.osc. + cosmo.osc. + heaviest lightest neutrino neutrino Ryan Patterson 20 Why so light? H t Z See-saw mechanism? – Heavy (possibly GUT-scale) RH neutrinos W alongside light LH neutrinos: b 휏 c
s 휇
d u
e
mass (GeV) mass
mass (GeV) mass
oscillations
cosmo.osc. + cosmo.osc. + heaviest lightest neutrino neutrino Ryan Patterson 21 Why so light? H t Z See-saw mechanism? – Heavy (possibly GUT-scale) RH neutrinos W alongside light LH neutrinos: b 휏 c
s 휇
d u
e
Would imply that the physics of neutrino mass is
connected to extremely high energy scales. (GeV) mass
Potential new physics signatures in oscillation expts: non-unitarity, non-standard interactions, >3 neutrinos, large
extra dimensions, effective CPTv, decoherence, neutrino decay, …
Now textbook material, the see-saw mechanism goes back to P. Minkowski (1977); oscillations cosmo.osc. +
M. Gell-Mann, P. Ramond and R. Slansky (1979); and T. Yanagida (1979) cosmo.osc. + heaviest lightest neutrino neutrino Ryan Patterson 22
Flavor structure ← flavor symmetry ? →
→ u c t d s b
e 휇 휏
2 gauge symmetry symmetry gauge
휈e 휈휇 휈휏
← ←
(mass)
Ryan Patterson 23 Accelerator Neutrinos @ INSS 2017
Flavor structure ← flavor symmetry ? →
→ |Ue3| ≠ 0 (recent discovery) u c t d s b
e 휇 휏
2 gauge symmetry symmetry gauge
휈e 휈휇 휈휏
← ←
(mass)
Ryan Patterson 24 Accelerator Neutrinos @ INSS 2017
Flavor structure ← flavor symmetry ? →
→ |Ue3| ≠ 0 |U휇3| = |U휏3| ? (recent discovery) (“maximal mixing”) u c t d s b
e 휇 휏
2
approx. 1:1:1 ratio symmetry gauge
휈e 휈휇 휈휏
← ←
(mass)
What flavor symmetry can produce this pattern of mixings and masses, and how is that symmetry broken?
More broadly: what are the dynamical origins of fermion masses, mixings, and CP violation? Ryan Patterson 25 Accelerator Neutrinos @ INSS 2017 Flavor structure
|Ue3| ≠ 0 |U휇3| = |U휏3| ? (recent discovery) (“maximal mixing”) Experimental question: 2 sin 휃23 ≠ 0.5 ? Non-maximal mixing?
If so, which way does it break?
2
approx. 1:1:1 ratio
(mass)
Standard parametrization of PMNS matrix:
Ryan Patterson 26 Accelerator Neutrinos @ INSS 2017 CP violation New source of CP violation required to explain baryon asymmetry of universe part-per-billion level of matter/antimatter asymmetry in early universe
Neutrino CPv allowed in 휈SM, but not yet observed …due so far to the experimental challenge, not physics!
Leptogenesis1 is a workable solution for the baryon asymmetry, but need to first find any leptonic (neutrino) CPv
sin 훿 ≠ 0 ? Leptonic CP violation?
1 M. Fukugita and T. Yanagida (1986); rich history since then.
Ryan Patterson 27 Accelerator Neutrinos @ INSS 2017 휈 Ryan Patterson a simple question: Far Notice: - - - -
An inverted hierarchy implies hierarchy inverted An <
mass hierarchy Theoretical Cosmology Experimental approach to and 0 → → 1 휈 flavor flavor and mass generation interpretation of - . 훽 reaching implications for such 5 heavier or lighter Are the electron Would at…?? hint 훽 % mass degeneracy
and and
Majorana Majorana nature of
and and frameworks astrophysics m 훽
-
rich states (cf.:
for than than .
휋
+ 휈
휈 /
휋 3
0 ? ) 휈
1
28 &
휈 2
P.PRD al., et Guzowski (mass)2 Accelerator Neutrinos @ INSS 92 , 012002 ( 2015 2017
)
st
Flavor: A core problem for 21 century particle physics
Nucl. Phys. B B Nucl. Phys. Fiorentin Re Marzola, Bari, Di Flurry of theoretical work. 2 Discrete flavor groups (A4, S4, Δ(3n ), …) often combined with GUTs. Non-trivial flavor texture
in heavy sector. 893 , ,
Emphasis on genuine predictive power. Explicit 122
connections between low energy observables (
and leptogenesis. 2015
)
Often immutable preferences for mass hierarchy
and 휇/휏 asymmetry
JHEP de Varzielas, Medeiros King de Björkeroth, Anda,
Nucl. Phys. B B Nucl. Phys. Molinaro Meroni, Hagedorn,
06
, ,
141 141
(
891
2015
, ,
499 499
)
(
2015
)
Ryan Patterson 29 st
Flavor: A core question for 21 century particle physics
Nucl. Phys. B B Nucl. Phys. Fiorentin Re Marzola, Bari, Di Flurry of theoretical work. Pascoli and Zhou, JHEP 06, 73 (2016) Discrete flavor groups (A4, S4, Δ(3n2), …) often Flavor symmetry A4 ⨯ Z2 ⨯ Z4; flavon-induced combined with GUTs. Non connections-trivial flavor between texture flavor mixing and CLFV,
in heavy sector. and… 893 , ,
Emphasis on genuine predictive power. Explicit 122
connections between low energy observables (
and leptogenesis. 2015
)
Often immutable preferences for mass hierarchy
and 휇/휏 asymmetry
JHEP de Varzielas, Medeiros King de Björkeroth, Anda,
Nucl. Phys. B B Nucl. Phys. Molinaro Meroni, Hagedorn,
06
, ,
141 141
(
891
2015
, ,
499 499
)
(
2015
)
Ryan Patterson 30 Long-baseline experiments
Ryan Patterson 31 Accelerator Neutrinos @ INSS 2017 휈휇 hundreds of kilometers 휈휇 휈휏
Near Detector 휈e Far Detector
휈휇 survival (or “disappearance”):
…to leading order Past experimental data have been consistent with unity (i.e., maximal mixing). Some tension in recent data!
Ryan Patterson 32 Accelerator Neutrinos @ INSS 2017 휈휇 hundreds of kilometers 휈휇 휈휏
Near Detector 휈e Far Detector
휈휇 survival (or “disappearance”):
…to leading order Conventional 휈 beam ⇒ E휈 ~ 1 GeV Nature ⇒ m2 ~ 3⨯10-3 eV2
Thus, first oscillation maximum at L ~ hundreds of km
Ryan Patterson 33 Accelerator Neutrinos @ INSS 2017 휈휇 hundreds of kilometers 휈휇 휈휏
Near Detector 휈e Far Detector
휈휇 survival (or “disappearance”): Near Detector Far Detector
Identified 휈휇 interactions Ryan Patterson 34 Accelerator Neutrinos @ INSS 2017 휈휇 hundreds of kilometers 휈휇 휈휏
Near Detector 휈e Far Detector
휈휇 survival (or “disappearance”):
Observation:
[ 휙(E)휎(E)휀(E)P휈휇→휈x(E) + background ] ⊗ {detector effects}(E, …)
20-50% 20-50% 5-50% 5-50% typical starting uncertainties
ND largely cancels these uncertainties as they are correlated (esp. if same detector type)
Ryan Patterson 35 Accelerator Neutrinos @ INSS 2017 휈휇 hundreds of kilometers 휈휇 휈휏
Near Detector 휈e Far Detector
휈e appearance:
…plus potentially large CPv and
matter effect* modifications! 2
(mass) * 휈e see different potential than 휈휇,휏 when propagating through matter (here, the earth) ⇒ a hierarchy-dependent effect !
Ryan Patterson 36 Accelerator Neutrinos @ INSS 2017 (From PDG) (for antineutrinos, x → -x and 훿 → -훿)
Ryan Patterson 37 Accelerator Neutrinos @ INSS 2017 Recent and present LBL experiments
Ryan Patterson 38 Accelerator Neutrinos @ INSS 2017 K2K experiment in Japan (ran 1999 – 2004) K2K = “KEK-to-Kamioka”
Aimed to confirm atmospheric 휈휇 disappearance using accelerator 휈휇 Final publication: M. H. Ahn et al. (K2K), Phys. Rev. D 74, 072003 (2006)
Ryan Patterson 39 Accelerator Neutrinos @ INSS 2017 K2K experiment in Japan (ran 1999 – 2004) K2K = “KEK-to-Kamioka”
Aimed to confirm atmospheric 휈휇 disappearance using accelerator 휈휇 Final publication: M. H. Ahn et al. (K2K), Phys. Rev. D 74, 072003 (2006)
Ryan Patterson 40 Accelerator Neutrinos @ INSS 2017 K2K experiment in Japan (ran 1999 – 2004) K2K = “KEK-to-Kamioka”
Aimed to confirm atmospheric 휈휇 disappearance using accelerator 휈휇 Final publication: M. H. Ahn et al. (K2K), Phys. Rev. D 74, 072003 (2006)
Ryan Patterson 41 Accelerator Neutrinos @ INSS 2017 K2K Near Detector (More on Far Detector [Super-K] later)
Ryan Patterson 42 Accelerator Neutrinos @ INSS 2017 K2K Near Detector (More on Far Detector [Super-K] later)
Comparing to contemporary atmospheric 휈 result from Super-K
Ryan Patterson 43 Accelerator Neutrinos @ INSS 2017 Ryan Patterson 44 Accelerator Neutrinos @ INSS 2017 MINOS detectors
. “Identical” near and far detectors Magnetized tracking calorimeters B = 1.0 to 1.5 T 1 kton ND / 5.4 kton FD . Alternating layers of: steel (1” thick plates) scintillator (1 cm thick, 4.1 cm wide strips) . Scintillator layers oriented at ±45°
Near Detector Far Detector MINOS events (Monte Carlo)
휈휇 charged current . Clear signature in MINOS: long track
. If 휇 track is very short, event can be Ereco = 14.1 GeV mistaken for 휈e CC or NC
휈e charged current . 휈 is small component of initial flux e . Electron deposition arranged in transversely compact shower Ereco = 7.8 GeV
neutral current . Especially with 휋0, hard to distinguish from 휈 CC e . Energy more transversely distributed
Ereco = 8.0 GeV
Ryan Patterson 46 Relationship between ND and FD 휈휇 spectra
. Measure 휈휇 CC interactions in the near detector . Transport observed spectrum to create far detector predictions
Far detector 휈휇 spectrum Observed deficit versus energy
Ryan Patterson 47 Accelerator Neutrinos @ INSS 2017 Relationship between ND and FD 휈휇 spectra
. Measure 휈휇 CC interactions in the near detector . Transport observed spectrum to create far detector predictions
Also 휈 appearance searches… Far detector 휈휇 spectrum e 휈e appearance (single 훼LEM bin shown here)
Reconstructed neutrino energy (GeV)
Ryan Patterson 48 Accelerator Neutrinos @ INSS 2017 All MINOS 휈휇 and 휈⎺휇 data (accelerator and atmospheric sources)
Ryan Patterson 49 Accelerator Neutrinos @ INSS 2017 2 . Confidence intervals in a portion |m32 | precision = 4% 2 2 of parameter space m21 / |m32 | = 3% (휃13 and CP phase 훿 marginalized ⇒ 2휈 approximations out for clarity) a thing of the past
Ryan Patterson 50 Accelerator Neutrinos @ INSS 2017 OPERA experiment at Gran Sasso in Italy Oscillation Project with Emulsion-tRacking Apparatus Many graphics taken from D. Duchesneau, Neutrino 2016
Look for 휈휏 appearance, but not easy… - Energy threshold high energy beam low Posc for any reasonable baseline - Backgrounds, particularly charm (D meson) production Ryan Patterson 51 Accelerator Neutrinos @ INSS 2017 OPERA detector
Emulsion and lead layers arranged in “bricks”
Tracking detectors to locate interaction point among the bricks
Ryan Patterson 52 Accelerator Neutrinos @ INSS 2017 OPERA detector
Emulsion and lead layers arranged in “bricks”
Tracking detectors to locate interaction point among the bricks
Ryan Patterson 53 Accelerator Neutrinos @ INSS 2017 Ryan Patterson 54 Accelerator Neutrinos @ INSS 2017 OPERA
1 cm n
Accelerator Neutrinos @ INSS 2017 OPERA
1 cm n
Accelerator Neutrinos @ INSS 2017 OPERA
1 cm n
Accelerator Neutrinos @ INSS 2017
Different event… (1.8⨯1020 p.o.t.) Will continue this thread tomorrow (and then on to many other items…)
End of Part 1
Ryan Patterson 61 Accelerator Neutrinos @ INSS 2017