Neutrinos:
Worth the Wait
Kevin McFarland
University of Rochester
Warwick University Physics
Departmental Colloquium
30 November 2005
Neutrinos:
Worth the Wait
especially when snowed in…
Kevin McFarland
University of Rochester
“snowed in”
Warwick University Physics
Departmental Colloquium
30 November 2005
Neutrinos and Slowness…
• Neutrino physics has historically
been a slowly developing field
– due to the properties of the
neutrino, as we shall see
• But neutrino physics is heating
up into a very active field
– driven by experimental results
– and by new technologies
• So first, some history and
perspective…
30 November 2005
K. McFarland, Neutrinos: Worth the Wait
A Typical February
View of the George
Eastman Theater at
the University of
Rochester
3
The Birth of the Neutrino
Wolfgang Pauli
30 November 2005
K. McFarland, Neutrinos: Worth the Wait
4
Translation, Please?
4th December 1930
Dear Radioactive Ladies and Gentlemen,
As the bearer of these lines, to whom I graciously ask you to listen, will explain to you in
more detail, how because of the ”wrong” statistics of the N and 6Li nuclei and the
continuous beta spectrum, I have hit upon a desperate remedy to save the ”exchange
theorem” of statistics and the law of conservation of energy. Namely, the possibility that there
could exist in the nuclei electrically neutral particles, that I wish to call neutrons, which have
spin and obey the exclusion principle and which further differ from light quanta in that they do
not travel with the velocity of light. The mass of the neutrons should be of the same order of
magnitude as the electron mass (and in any event not larger than 0.01 proton masses). The
continuous beta spectrum would then become understandable by the assumption that in
beta decay a neutron is emitted in addition to the electron such that the sum of the energies
of the neutron and the electron is constant...
From now on, every solution to the issue must be discussed. Thus, dear radioactive people,
look and judge. Unfortunately I will not be able to appear in Tübingen personally, because I
am indispensable here due to a ball which will take place in Zürich during the night from
December 6 to 7….
Your humble servant,
W. Pauli
30 November 2005
K. McFarland, Neutrinos: Worth the Wait
5
Translation, Please?
• To save the law of conservation of energy?
β-decay
The Energy of the “β”
• If the above picture is complete, conservation of energy
says β has one energy, but we observe this instead
– Pauli suggests “neutron” takes away energy!
• The “exchange theorem of statistics”, by the way, refers to the fact
that a spin½ neutron can’t decay to an spin½ proton + spin½ electron
– he doesn’t call it the “Pauli exclusion principle”, to his credit…
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K. McFarland, Neutrinos: Worth the Wait
6
Fundamental Forces
• Of the four fundamental forces, three are
important for the structure of matter around us
Strong force
Gravity
– holds planets,
galaxies, etc.
together
Electromagnetism
– holds nucleus
together
– so strong that
quarks are confined
– holds atoms together
– keeps matter from
collapsing under the
force of gravity
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7
Theories of Forces
• Modern force description is
quantum field theory…
– often illustrated w/ its lowest order
perturbative expansion…
• First theory of weak interactions
(Fermi theory of beta decay, 1933)
– also names the “neutrino” to distinguish from
Chadwick’s neutron
Enrico Fermi
Neutron Beta Decay
30 November 2005
Neutrino-Neutron
“Quasi Elastic” Scattering
K. McFarland, Neutrinos: Worth the Wait
8
How to Hunt a Neutrino
• How do we see any fundamental particle?
• Electromagnetic
interactions kick
electrons away
from atoms
• But neutrinos don’t have
electric charge. They only interact weakly
– so we only see by-products of their weak interactions
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9
How Weak is Weak?
• Weak is, in fact, weak.
• A 3 MeV neutrino produced
in fusion from the sun will travel
through water, on average, before interacting.
– The 3 MeV positron (anti-matter electron) produced in
the same fusion process will travel 3 cm, on average.
• Moral: to find neutrinos, you need a lot of
neutrinos and a lot of detector!
30 November 2005
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10
Discovery of the Neutrino
• Reines and Cowan (1955)
– Nobel Prize 1995
– 1 ton detector
– Neutrinos from a nuclear
reactor  p  e n
Reines and Cowan at
Savannah River
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Solar Neutrino Hunting
• Radiochemical Detector
Ray Davis
Ray Davis (Nobel prize, 2002)
– ν+np+e- (stimulated β-decay)
– Use this to produce an unstable
isotope, ν+37Cl37Ar+e- , which
has 35 day half-life
– Put 615 tons of
Perchloroethylene
in a mine
• expect one 37Ar atom
every 17 hours.
30 November 2005
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Solar Neutrino Hunting
• Ran from 1969-1998
• Confirmed that sun
shines from fusion
• But found 1/3 of ν !
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13
Modern Solar Neutrino Hunting
• Kamiokande and
Super-Kamiokande
(Masatoshi Koshiba, Rochester
PhD 1955, Nobel Laureate 2002)
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14
Modern Neutrino Hunting
• The Sun, imaged in neutrinos, by
Super-Kamiokande
sadly, not
the same
angular
scale
Existence of the sun
confirmed by neutrinos!
30 November 2005
The Sun, optical image
K. McFarland, Neutrinos: Worth the Wait
15
Our Timescale So Far…
• Pauli and Fermi (theory)
1930
• to Reines and Cowan (discovery)
1950
• to Davis (solar neutrinos)
1970
1990
• to Koshiba (supernova and oscillations)
– progress continues to accelerate into the
exciting neutrino programs of today…
30 November 2005
K. McFarland, Neutrinos: Worth the Wait
16
Next Steps: The Broadest Goals
• Understand mixing of neutrinos
– a non-mixing? CP violation?
• Understand neutrino mass
– absolute scale and hierarchy
• Understand  interactions
– new physics? new properties?

• Use neutrinos as probes
– nucleon, earth, sun, supernovae
30 November 2005
K. McFarland, Neutrinos: Worth the Wait

17
Qualitative Questions
• The questions facing us now are
fundamental, and not simply a matter of
“measuring oscillations better”
• Examples:
– Are there more than three neutrinos?
– What is the hierarchy of masses?
– Can neutrinos contribute significantly to the
mass of the universe?
– Is there CP violation in neutrino mixings?
30 November 2005
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18
The Broadest Goals
• Understand mixing of neutrinos
– a non-mixing? CP violation?
• Understand neutrino mass
– absolute scale and hierarchy
• Understand  interactions
– new physics? new properties?

• Use neutrinos as probes
– nucleon, earth, etc.
30 November 2005

K. McFarland, Neutrinos: Worth the Wait
19
What We Hope to Learn From
Neutrino Oscillations
• Near future
– validation of three generation picture
• confirm or disprove LSND oscillations (>3 neutrinos)
• precision tests of “atmospheric” mixing at
accelerators
• Farther Future
– neutrino mass hierarchy, CP violation?
• Precision at reactors
• sub  multi MegaWatt sources
• 10  100  1000 kTon detectors
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20
Minimal Oscillation Formalism
• If neutrino mass eigenstates: 1, 2, 3, etc.
• … are not flavor eigenstates: e, m, t
• … then one has, e.g.,

    cos 
 
     sin 
 cos   i  sin   j
4
4
time
30 November 2005
sin     i 
  
cos    j 
take only two
generations
for now!
different
masses
alter time
evolution
    sin  4  i  cos  4  j
K. McFarland, Neutrinos: Worth the Wait
21
Oscillation Formalism (cont’d)
• So, still for two generations…
 (m  m ) L 

P( m   t )  sin 2 sin 
4E


2
2
2
2
2
1
appropriate units
give the usual
numerical factor
1.27 GeV/km-eV2
• Oscillations require mass differences
• Oscillation parameters are mass-squared differences,
dm2, and mixing angles, .
• One correction to this is matter… changes , L dep.
Wolfenstein, PRD (1978)
sin 2 2
sin 2 M 
sin 2 2  ( x  cos 2) 2
2
LM  L  sin 2 2  ( x  cos 2) 2
x
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K. McFarland, Neutrinos: Worth the Wait
2 2GF ne E
m 2
n  e- density
22
Solar Neutrinos
• There is a glorious history
of solar neutrino physics
– original goals: demonstrate
fusion in the sun
– first evidence of oscillations
SAGE - The Russian-American
Gallium Experiment
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23
Culmination: SNO
• D2O target uniquely observes:


d

ppe
– charged-current e
– neutral-current  X d  X pn
• The former is only
observed for e
(lepton mass)
• The latter for all types
• Solar flux is consistent
with models
– but not all e at earth
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K. McFarland, Neutrinos: Worth the Wait
24
KAMLAND
• Sources are
Japanese
reactors
– 150-200 km
for most of
flux. Rate uncertainty ~6%
• 1 kTon scint. detector in
old Kamiokande cavern
– overwhelming confirmation
that neutrinos change flavor
in the sun via matter
effects
30 November 2005
K. McFarland, Neutrinos: Worth the Wait
25
Solar Observations vs. KAMLAND
+ KAMLAND =
• Solar neutrino observations are best
measurement of the mixing angle
• KAMLAND does better on dm212
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Atmospheric Neutrinos
• Neutrino energy: few 100 MeV – few GeV
• Flavor ratio robustly predicted
• Distance in flight: ~20km (down) to 12700 km (up)
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K. McFarland, Neutrinos: Worth the Wait
27
Super-Kamiokande
• Super-K
detector has
excellent e/m
separation
2004
Super-K
analysis
old, but
good data!
• Up / down difference!
30 November 2005
K. McFarland, Neutrinos: Worth the Wait
28
Neutrino Beam from
KEK to Super-K
K2K
figures courtesy T. Nakaya
• Experiment has completed
data-taking
– confirms atmospheric
neutrino oscillation parameters
with controlled beam
– constraint on dm223 (limited statistics)
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29
Enough For Three Generations
figures courtesy B. Kayser
dmsol2 dm122≈8x10-5eV2
dmatm2 dm232≈2.5x10-3eV2
• Oscillations have told us the splittings in m2, but nothing
about the hierarchy
• The electron neutrino potential (matter effects) can
resolve this in oscillations, however.
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30
Three Generation Mixing
slide courtesy D. Harris
• Note the new mixing in middle, and the phase, d
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31
But CHOOZ…
• Like KAMLAND, CHOOZ
and Palo Verde expt’s
looked at anti-e from a
reactor
– compare expected to
observed rate, s~4%
• If electron neutrinos don’t
disappear, they don’t transform to
2
dm 23
muon neutrinos
– limits m->e flavor transitions at
and therefore |Ue3| is “small”
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32
Optimism has been Rewarded
“We live in the best of all possible worlds”
– Alvaro deRujula, Neutrino 2000
• By which he meant…
had not
Eatm /Rearth < dmatm2 <Eatm /hatm
and had not solar density profile
and dmsol2 been
well-matched…
• We might not be discussing oscillations!
30 November 2005
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33
Are Two Paths Open to Us?
• If “CHOOZ” mixing, 13, is small, but not too
small, there is an interesting possibility
dm232, 13
e
m
dm122, 12
• At atmospheric L/E,
SMALL
LARGE
2
2


(
m

m
2
2
2
1 )L
P( m   e )  sin 2 sin 

4
E


LARGE
SMALL
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34
Implication of two paths
• Two amplitudes
dm232, 13
e
m
dm122, 12
• If both small,
but not too small,
both can contribute ~ equally
• Relative phase, d, between them can lead to
CP violation (neutrinos and anti-neutrinos differ)
in oscillations!
30 November 2005
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35
Leptonic CP Violation in
Oscillations
• CP violation and matter effects lead to a complex mix…
• CP violation gives ellipse
Minakata & Nunokawa
but matter effects shift
JHEP 2001
the ellipse in a
long-baseline accelerator
experiment…
• Stakes are high:
– CP violation in leptons
could, in fact, have
seeded Universe’s
matter-antimatter asymmetry
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36
But LSND…
figures courtesy S. Brice
• LSND anti-e excess
– 87.9±22.4±6.0 events
– statistically overwhelming;
however…
LSND
dm2 ~ 0.1-1.0 eV2
Atmos. dm2 ≈ 2.5x10-3 eV2
Solar
30 November 2005
dm2 ≈ 8.0x10-5 eV2
K. McFarland, Neutrinos: Worth the Wait
cannot be
accommodated
with only three
neutrinos
37
MiniBooNE
figures courtesy S. Brice
• A very challenging experiment!
• Have ~0.6E21
protons on tape
• First e
appearance
results in
early 2006 (?)
30 November 2005
K. McFarland, Neutrinos: Worth the Wait
Signal
Mis-ID
Beam
38
Next Steps
(Brazenly Assuming Three Neutrinos)
• MINOS and CNGS
• Reactors
• T2K and NOvA
graphical wit
courtesy A. deRujula
• Mating Megatons and Superbeams
• Beta (e) beams and
neutrino factories (me and m)
30 November 2005
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39
Isn’t all of this overkill?
• Disentangling the physics from the
measurements is complicated
• Different measurements have different sensitivity to
matter effects, CP violation
– Matter effects amplified for long L, large E
– CP violation cannot be seen in disappearance
(reactor) measurement ee
Huber, Lindner, Rolinec,
Schwetz, Winter
30 November 2005
K. McFarland, Neutrinos: Worth the Wait
assumes
sin22
13
= 0.1
40
NuMI-Based Long Baseline
Experiments
• 0.25 MWatt  0.4
MWatt proton source
• Two generations:
– MINOS (running)
– NOvA (future)
15mrad Off Axis
30 November 2005
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41
MINOS
Goal: precise
m disappearance
measurement
Gives dm223
30 November 2005
735km baseline
5.4kton Far Det.
1 kton Near Det.
Running since early
2005
K. McFarland, Neutrinos: Worth the Wait
42
CNGS
Goal: t appearance
• 0.15 MWatt source
• high energy m beam
• 732 km baseline
• handfuls of events/yr
1 mm
e-, 9.5 GeV, pT=0.47 GeV/c
t

t interaction, E=19 GeV
1.8kTon
3kton
fiugres courtesy A. Bueno
30 November 2005
Pb
Emulsion layers
figures courtesy D. Autiero
K. McFarland, Neutrinos: Worth the Wait
43
Back to Reactors
• Recall that
KAMLAND
saw anti-e
disappearance
at solar L/E
• Have not seen
disappearance at
atmospheric L/E
30 November 2005
K. McFarland, Neutrinos: Worth the Wait
44
Why Reactors?
• CHOOZ (reactor) has left us without evidence of
anti-e disappearance indicating |Ue3|>0
– reactors are still the most sensitive probe!
• CHOOZ used a single detector
– therefore, dead-reckoning used to estimate neutrino
flux from the reactor
– could improve with a near/far technique
• KAMLAND has improved knowledge of how to
reject backgrounds significantly
(remember, their reactors are ~200 km away!)
30 November 2005
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45
How Reactors?
• To get from ~4% uncertainties to ~1% uncertainties,
need a near detector to monitor neutrino flux
• For example, Double-CHOOZ proposes to add a second
near detector and compare rates
– new detectors with 10 ton mass
– total error budget on rate ~2%
– low statistics 10t limit spectral
distortion, 1 km baseline likely
shorter than optimum
not an
engineering
drawing
• Optimization beyond Double-CHOOZ…
– ~100 ton detector mass
– optimize baseline for dm223
– background reduction with active or passive shielding
30 November 2005
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46
Where Reactors?
• A series of proposals with different technical
choices
• All challenging experiments to limit systematics
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47
Megawatt Class Beams
• J-PARC
– initially 0.7 MWatts  4 MWatts
• FNAL Main Injector
– current goal 0.25 MWatts  0.4 MWatts
– future proton driver upgrades?
• Others?
30 November 2005
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48
J-PARC Facility
30 November 2005
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49
A Digression: Off-axis
• First Suggested by Brookhaven (BNL 889)
• Take advantage of Lorentz Boost and 2body kinematics
• Concentrate m flux
at one energy
• Backgrounds lower:
– NC or other feed-down
from highlow energy
– e (3-body decays)
30 November 2005
figure courtesy D. Harris
K. McFarland, Neutrinos: Worth the Wait
50
T2K
• Tunable off-axis beam from
J-PARC to Super-K detector
– beam and m backgrounds are
kept below 1% for e signal
– ~2200 m events/yr (w/o osc.)
d=0, no matter effects
30 November 2005
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51
figures courtesy T. Kobayashi
NuMI-Based Long Baseline
Experiments
• 0.25 MWatt  0.4
MWatt proton source
• Two generations:
– MINOS (running)
– NOvA (future)
15mrad Off Axis
30 November 2005
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52
NOA
figure courtesy M. Messier
• Use Existing NuMI
Goal:
beamline
e appearance
• Build new 30kTon
In m beam
Scintillator Detector
• 820km baseline-compromise between
reach in 13 and matter
Assuming m2=2.5x10-3eV2
effects
figures courtesy J. Cooper
30 November 2005
K. McFarland, Neutrinos: Worth the Wait
e+A→p + - e-
53
Future Steps after T2K, NOvA
• Beam upgrades (2x – 5x)
• Megaton detectors (10x – 20x)
• BUT, it’s hard to make such steps without
encountering significant
TECHNICAL DIFFICULTIES
– hereafter “T.D.”
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54
TD: More Beam Power, Cap’n
Example: Fermilab Proton Driver
Neutrino
“SuperBeams”
NUMI
SY-120
FixedTarget
OffAxis
8 GeV
neutrino
8 GeV Linac
~ 700m Active Length
Main
Injector
@2 MW
30 November
figure
courtesy2005
G.W. Foster
Parallel Physics and
Machine Studies …
main justification
Is to serve as source for new
Long baseline neutrino
K. McFarland, Neutrinos: Worth the Wait
55
experiments
TDs: Beamlines
pictures courtesy D. Harris
• Handling Many MWatts of proton power and
NuMI Horn 2.
turning it into neutrinos is not trivial!
Note conductors
NuMI tunnel
boring machine.
3.5yr civil
construction
NuMI Target
shielding.
More mass
than far
detector!
30 November 2005
and alignment
fixtures
NuMI downstream absorber.
Note elaborate cooling.
“Cost more than NuTeV
beamline…” – R. Bernstein
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56
TDs: Detector Volume
• Scaling detector volume is not
so trivial
figure courtesy G. Rameika
• At 30kt NOvA is about the same mass as BaBar,
CDF, Dzero, CMS and ATLAS combined…
– want monolithic, manufacturabile structures
– seek scaling as surface rather than volume if possible
30 November 2005
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57
For Perspective…
• Consider the Temple of
the Olympian Zeus…
17m
• 17m tall, just like NOvA!
– a bit over ½ the length
• It took 700 years to
complete
– delayed for lack of funding
for a few hundred years
• Fortunately construction
technology has improved
your speaker
30 November 2005
– has the funding situation?
K. McFarland, Neutrinos: Worth the Wait
58
TDs: Detector Volume (cont’d)
Depth (below surface)
• For megatons, housing a detector is difficult!
Span
figures courtesy C.-K. Jung
60m
UNO: 60m span
1500m depth
UNO. ~1Mton.
(20x Super-K)
40%
photocathode
10%
photocathode
• Sensor R&D: focus on reducing cost
– in case of UNO,
large photocathode PMTs
– goal: automated production,
1.5k$/unit
30 November 2005
60m
K. McFarland, Neutrinos: Worth the Wait
Field Map,
Burle 20” PMT
59
TDs: Neutrino Interactions
figures courtesy D. Casper, G. Zeller
• At 1-few GeV neutrino energy (of interest for osc. expt’s)
– Experimental errors on total cross-sections are large
• almost no data on A-dependence
– Understanding of backgrounds needs
differential cross-sections on target
– Theoretically, this region is a mess…
transition from elastic to DIS
nm–p0
nmn+
30 November 2005
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60
Futuristic Accelerator Beams
• Conventional Beam
figures courtesy D. Harris
Detector Needs
• Beta Beam
• Neutrino Factory
• Great experimental benefits to new beam technology,
but beams are very challenging! And costly…
30 November 2005
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61
The Broadest Goals
• Understand mixing of neutrinos
– a non-mixing? CP violation?
• Understand neutrino mass
– absolute scale and hierarchy
• Understand  interactions
– new physics? new properties?

• Use neutrinos as probes
– nucleon, earth, etc.
30 November 2005

K. McFarland, Neutrinos: Worth the Wait
62
Neutrinoless Double-Beta Decay
• Double beta decay
A
Z
A
 Z+2   2   2 e
is a rare, but
observed process
graphics courtesy Symmetry magazine
• “Neutrinoless” implies that the neutrino is
its own anti-particle (Majorana particle)
0

 m   phase space    nucl. matrix elems.
2
calculable
• The prize: m 
30 November 2005
U
2
mi e
i i
evaluable w/ largish
uncertainties
(i is a “Majorana phase”.
Please look it up because
i
K. McFarland, Neutrinos: Worth the Wait I’m not going there…) 63
ei
Experimental Challenges
• Observables: electron energy,
final state nucleus (EXO)
– Electron energy
requires excellent
resolution and low
non  backgrounds
– Tagging the final
state nucleus is “finding
a needle in a haystack”
2
0
sum electron energy / Q
• Must have significant quantities of  isotopes
– not necessarily easy to purify. good detector material?
– nuclear physics guidance limited on “best” isotopes
30 November 2005
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64
Current Results to Date
• Results
• To notice:
– 76Ge, 130Te have
large quantities,
best limits so far
– There is a claimed
observation
figure and table from APS  report: direct mass group
• controversial
• significant non-
backgrounds
(hard-to-predict Bi lines)
30 November 2005
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65
0 Future
• If the Heidelberg-Moscow 76Ge result is
correct, should be confirmed “easily”
• If not, want to push sensitivities to m2 to
at least level of dm223 (maybe dm212)
– approximately two (maybe four) orders of
magnitude lower than present situation
• Experiments are very difficult  want
confirming signals in multiple isotopes
– many exciting ideas for future experiments
30 November 2005
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66
0 Approaches: CUORE
• Calorimetric (thermal) detector which
is the  source (TeO2)
figures courtesy E.Fiorini
heat bath
– ~keV resolution at  endpoint (2528 keV)
Thermal sensor
– Currently running “Cuoricino”, 40 kg
– Full CUORE expects to have 750 kg,
TeO2
reduced background levels
crystal
e-
eCUORE R&D (Hall C)
CUORE (Hall A)
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Cuoricino (Hall A)
67
Other 0 Approaches
• COBRA: Semi-conductor CdZnTe detector
– multiple  isotopes!
– room temperature, so no cryogenics
(advantages for growing detector size,
keeping contaminated materials away)
• NEMO
– Tracking/calorimetric detector
external to source foils
(10kg of  isotopes in prototype)
– Geiger mode wire chambers, B=25G
– Scint/Low Rad. PMT calorimeter
• Field is being driven by a multiplicity of prototypes
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Other Mass Determinations?
figures courtesy K. Eitel
cosmology &
structure formation
astrophysics:
SN ToF measurements
D.N. Spergel et al: Sm < 0.69 eV (95%CL)
powerful, but very indirect
potential for ~few eV sensitivity
direct, but precision requires
detailed knowledge of SN
 decay kinematics: microcalorimeters
magnetically adiabatic collimating electrostatic spectrometers
187Re
3H
30 November 2005
direct, but very challenging
experiments
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69
figures courtesy K. Eitel
3
H  He    
3
KATRIN
phase space determines energy spectrum
E0 = Ee + E (+ recoil corrections)
dN/dE  (E0-Ee) × [ (E0-Ee)2 – m2 ]1/2
10 eV
theoretical  spectrum near endpoint
retarding (variable)
E-field allows only MAC-E spectrometers
(Mainz, Troitsk)
E>Eret. to pass
m<2.2eV(95%CL)
(sensitivity limit)
energy resolution:
: E/E=Bmin/Bmax
Bmax = 6 T
Bmin = 3×10-4 T
so E~1 eV
30 November 2005
KATRIN sensitivity
m<0.2eV(90%CL)
commissioning in 2008
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The Broadest Goals
• Understand mixing of neutrinos
– a non-mixing? CP violation?
• Understand neutrino mass
– absolute scale and hierarchy
• Understand  interactions
– new physics? new properties?

• Use neutrinos as probes
– nucleon, earth, etc.
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
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Neutrino Interactions
• So broad a subject… so little time
•
•
•
•
Precision EWK
Neutrino magnetic moments
Non-standard neutrino interactions
Parity-violating probe
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Neutral Currents in Neutrinos
• Neutrino neutral current?
– LEP invisible width, only 2s
– NuTeV may be
very large
isospin violation
• Future reactors?
Conrad, Link, Shaevitz
– if reactor experiments have precision for 13, may also
be able to measure neutral currents
– opportunity for a purely leptonic probe
 e e   e e
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MINERvA, for Oscillations
• Noted that neutrino interactions are poorly known…
• Backgrounds or signal rate uncertainties for next
accelerator oscillation experiments could limit precision
• Enter MINERvA at NuMI beamline
– newly approved cross-section
experiment in NuMI near hall
– construction start in late 2006;
taking data by 2008
For example,
MINERvA helps
MINOS know
relationship
νµp→νµpπ0
between visible
Photon tracks!
and true energy
figures courtesy B. Ziemer, D. Harris, R. Flight
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The Broadest Goals
• Understand mixing of neutrinos
– a non-mixing? CP violation?
• Understand neutrino mass
– absolute scale and hierarchy
• Understand  interactions
– new physics? new properties?

• Use neutrinos as probes
– nucleon, earth, etc.
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
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MINERvA, Axial Form Factors
• An experiment like MINERvA
can add to knowledge of
nucleon structure!
– Jefferson Lab for
neutrinos
• Example: axial
structure of proton
at high Q2.
– of interest because
of puzzling behavior
of vector form factors
figures courtesy H. Budd, R. Flight
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Journey to the Center of the
(Spherical) Earth: Geoneutrinos
• Another use of neutrinos as a probe
figures courtesy G. Fiorentini
• The journey in brief:
– earth radiates 30-45 TWatts in heat
– the hypothesis: this is due to
radioactivity of the earth
– this radioactivity emits low energy
anti-neutrinos from U and Th
decays detectable via
  p  e   n  1.8MeV
– one complication: much of
U/Th is in crust
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Geoneutrinos (cont’d)
figures courtesy G. Fiorentini
• Crust distribution is location
dependent, but can be determined
by geochemical surveys
• Subtraction of the variable (local)
part leaves the “global” U/Th
Kamioka
• At right, expected local and
maximum “global” signal for U
– “TNU” unit is 10-32 ev/prot-yr
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Geoneutrinos (cont’d)
figures courtesy Nature
• First measurement from KamLAND!
– very challenging backgrounds!

reactors
2.0
3.0
Neutrino Energy (MeV)
• Rate of U+Th anti-neutrino reactions of
(28±14)x10-32/proton/yr
– heat limit of <60 TW at 95% confidence
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Breathless Conclusions
• There is a lot going on in neutrino physics!
• Nature has been kind to us
so far, and answers to
fundamental questions
may be ripe for the picking
• But, new experiments are
getting more difficult…
– Still, we’ve been historically patient in neutrino
physics (e.g., 30 years from Pauli to Reines and Cowan)
– And it’s been worth the wait!
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Acknowledgements
input or source material supplied by (with or without their knowledge):
A. deRujula, B. Kayser, D. Harris (also editorial help! thank you!), T. Nakaya,
S. Parke, S. Brice, D. Autiero, T.. Kobayashi, M. Messier, J. Cooper,
G.W. Foster, G. Rameika, C.-K. Jung, M. Bishai, H. Gallagher, B. Ziemer,
H. Budd, E. Fiorini, G. Gratta, X. Sarazin, K. Eitel, R. Flight, D. Casper,
H. Minakata, G. Zeller, G. Fiorentini, Nature, The Particle Adventure, Star Trek
and Symmetry magazine
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Supplementary Slides
More to learn from the sky?
• Sign-separated atmospheric neutrinos
– MINOS detector is first with this capability
Time vs Y
Time vs Z
– determine charge
from bend
y
x
z
Y vs X
Strip vs Plane
~1 yr MINOS
figures courtesy M. Bishai, H. Gallagher
Y vs Z
• Why study neutrino vs. anti-neutrino oscillations?
– possibility to test CPT violation scenarios if suggested by MiniBooNE
and LSND results
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Observing Matter Effected
Oscillations
• We apparently have seen matter effects in the
sun… can we verify it in the earth?
• Best results
from Super-K
• Expect ~2%
effect
– Not there yet
• Interesting
for future
solar 
experiments…
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Who Cares About β-Decay?
• Weak Nuclear Force
– its exciting role is to, well, make β-decays
– that sounds awfully anticlimactic… who cares?
• actually,
you do.
A lot.
– Fusion in the sun requires that a proton
turn into a neutron. Inverse of β-decay!
– Without β-decay, we are stuck where the sun
don’t shine…
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Slides for my Amusement
Is there an easier way?
• Why, yes! Leave it to Star Trek to point the way!
• Apparently, according to several
episodes, Lt. Jordy LaForge’s VISOR
can actually detect “neutrino field
emissions”
– and what do we do in science except
emulate Star Trek?
• Sadly, this technology is the sole purview of the
Pentagon for use in spotting neutrino emissions from
their political opponents… so we need other tools.
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Is there no escape from Neutrinos?
Cosmic Gall
Neutrinos, they are very small.
They have no charge and have no mass
And do not interact at all.
The earth is just a silly ball
To them, through which they simply pass,
Like dustmaids down a drafty hall
Or photons through a sheet of glass.
They snub the most exquisite gas,
Ignore the most substantial wall,
Cold-shoulder steel and sounding brass,
Insult the stallion in his stall,
And, scorning barriers of class,
Infiltrate you and me! Like tall
And painless guillotines, they fall
Down through our heads into the grass.
At night, they enter at Nepal
And pierce the lover and his lass
From underneath the bed - you call
It wonderful; I call it crass.
– John Updike
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Solar Neutrino Hunting
• Radiochemical Detector
Ray Davis (Nobel prize, 2002)
– ν+np+e- (stimulated β-decay)
– Use this to produce an unstable
isotope, ν+37Cl37Ar+e- , which
has 35 day half-life
– Put 615 tons of
Perchloroethylene
in a mine
Physicist Ray
Davis
not to be confused with
Ray “Stingray” Davis,
bass vocalist for
Parliament Funkadelic,
seen below “Tearing
the Roof Off the
Sucka” in a rare
Homestake Mine
Concert appearance
• expect one 37Ar atom
every 17 hours.
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