The Fastest Way between
Fermilab and Minnesota
Deborah Harris
Fermilab
Between Fermilab and Minnesota
• By Plane:
– Flying there takes 3 hours plus airport security and
traffic around O’Hare airport…
• By Car:
– Driving there takes 10 hours plus 15-minute stop to
buy cheese in Wisconsin
• By Phone:
– A Phone call must travel above the earth by satellite:
few hundredths of a second
• By Neutrino:
– Travels 450 miles straight through the earth at
99.999% the speed of light: 1/400 of a second
What is a Neutrino?
• Breakfast Cereal
• Japanese rhythm and
blues band
• Penny-sized jumping
spider
• Tiny neutral particles that
weigh almost nothing and
almost never interact with
anything else
Answer: most of the above
What do you mean they weigh
almost nothing?
• Normal matter: made of elements
• Elements: made of protons
and neutrons and electrons
• How much do neutrinos weigh?
– Protons and neutrons:
~1GeV (a trillion trillion or
per gram)
– Electrons:
2,000 per proton
– Neutrinos:
>1,000,000 per electron
What do you mean they almost
never interact?
n
…
- n has a good chance of traveling
thru 200 earths without interacting
- 100 billion neutrinos from the sun pass through your
thumbnail every second and you don’t even know it
• Good news and bad news:
– We can send them long distances and they will go where we
send them
– We have to send billions and billions of them through a huge
detector before one of them will interact there
How can you see neutrinos?
• Indirectly: by studying particles that
decay (radioactivity)
Y'
Y
number of β’s
b
expect β’s emitted with
a discrete energy E
E
energy
Energy crisis
• Some famous physicists said…
– Maybe energy is just not conserved, this quantum mechanics
is stranger than we thought
• Wolfgang Pauli wrote (in famous “desperate remedy” letter)
– Maybe there’s a neutral particle that lives in the nucleus that
can take away some of this energy during a decay, we just
don’t see it because it’s neutral
Y'
Y
b
“n”
Enter Enrico Fermi…
• Enrico Fermi introduced a new “weak” force to
describe radioactive decay
– proposed a smaller neutral particle: “neutrino” which
is created through this weak force
– Paper rejected by Nature because it “contained
speculations too remote from reality to be of interest
to the reader”
– Thirty years later…neutrino is discovered at a nuclear
reactor
n
p
b
“n”
What makes the sun shine?
• Since Newton, we have known
roughly how much the sun weighs: 2
million trillion trillion kilograms
(2x1030kg)
• Since the development of fuel, we
know how much energy you get from
one gallon of fuel
• We know how much energy the sun
produces in light, given how much we
see…
• This calculation says that the sun is
100 million years old…
• We know the sun has been shining
for at least 4 billion years…how can
that be?
•Answer: neutrinos and the weak interaction
Neutrinos from the Sun
Why else should we care about
neutrinos and the weak force?
• This is what allows nuclei to break up
• This is what allows different nuclei to
come together
– If no weak
force,
then
nothing
more
than
hydrogen
in the
universe!
Beyond the periodic table…
Proton: uud
Neutron: udd
Neutrinos are what
let neutrons decay to
protons: or a d quark
turn into a u quark
u c t
d s b
e
m
t
ne nm nt
Mass
+2/3
-1/3
-1
0
Leptons
Protons and
neutrons are
made of these
Quarks
• More to the universe than what’s in protons
Charge:
and neutrons
The Case of the
Missing Neutrinos
• Neutrinos from the sun were first
observed by the Homestake experiment
over 30 years ago
– Only found ~1/3 the number they expected
• A similar mystery was found with the
atmospheric neutrinos
– ~1/2 the number expected were observed
• Neutrino experiment at Los Alamos
found five times as many electron-type
neutrinos as expected…(which could
mean that 0.3% of the muon neutrinos
changed)
• These signals could be explained if
neutrinos have mass, and if different
neutrinos have different masses
What are we doing with neutrinos
at Fermilab?
• Now: Studying how neutrinos change
from one flavor to another
– MiniBooNE: looking for muon neutrinos
turning into electron neutrinos over short
distances (Kane County)
– MINOS: looking for muon neutrinos turning
into anything but muon neutrinos between
here and Minnesota
Why Minnesota?
• The state with the most saunas per
capita in the US
• They have the best iron mines
• Measurements of neutrinos from
atmosphere:
– Neutrinos from above
don’t change flavors
– Neutrinos from below change a lot
– Neutrinos from the atmosphere have to
travel at least a few hundred miles to
change at all
– So we have to
send a beam of
neutrinos far
enough through
the earth so that
they will have had
at least that much
time to interact…
How can you make a beam of neutrinos?
• Like making a
beam of light with
a flashlight
– Start with a putting
a current through a
filament
– That makes light
– Focus the light
through a lens
• One minor added
complication:
protons don’t make
neutrinos, you
have to make
particles that
decay to neutrinos
Booster
Main Injector
Beamline for MINOS
150 ft
350 ft
2000 ft
• MINOS: doing everything that other neutrino beams do,
but from 450 miles away and at a 3.5o angle
• Miners excavated a mile of
underground tunnels
Photo of Chris Laughton
• Filled decay pipe region back up
With Tunnel Boring Machine
with concrete: 1000 cement
trucks’ worth of cement
• Two elevators, two large halls
– Target hall: filled with target, horns shielding blocks
– Near Detector Hall: 150ft long, filled with MINOS Near detector
• 3½ year construction: longer than MINOS has been
taking data
MiniBooNE
Image
courtesy of
Bartoszek
Engineering.
These targets see 10’s’ of trillions of
Particles:
How can you keep something cool when you keep pumping energy into it?
MiniBooNE power: xxxx kWatts
MINOS power: 200kWatts
Hair Dryer: 150Watts
MiniBooNE
• MiniBooNE Horn:
– Has pulsed 100
million times
– 5 times a second!
• MINOS Horns
– 10 million pulses
– Once every 2
seconds
• Horn Currents:
~200,000 Amps
• 200,000 toasters!
(sounds of horns)
Ode to those who put the protons
right on target
• In order to make neutrinos, someone has to
vigilantly watch over the protons as they are
accelerated to high energies
• Direct them through the beamline
• Hit the target
• And never miss!
• Like walking a mile with a glass full
of milk that you cannot spill…
– Over and over and over again for years…
• And what thanks do they get?
How many detectors are there?
MINOS: trying to see how many muon neutrinos “DISAPPEAR”
(really just change flavor)
MiniBooNE: trying to see how many electron
neutrinos APPEAR
How can you see a neutrino?
• These three neutrinos (n’s)
are associated with
three charged particles,
who are as different
in size as
n
e,m,or t
p
n
– Squirrel (e: electron)
– Lion
(m: muon)
– Elephant (t: tau)
You can’t see the neutrino, but you can see their partners
How can you see Neutrinos
Directly?
n
p+
b“n”
• If radioactivity occurs, then this also happens:
b-p+
n
“n”
• Even more rare, neutrinos can hit electrons too…
“n”
-
b
b-
“n”
Measuring
Neutrino Flavors
• You can’t see neutrinos,
but you can see what they
produce when they hit
protons and neutrons…
• Problem: you can’t see
these products with a
microscope, because you
need lots of protons and
neutrons and microscopes
are expensive…
• How to tell the difference
between flavors?
MINOS
MINOS Detector:
5,400 tons of steel and plastic
Not just any plastic: it gives off light
when charged particles go through it
Collect the light: more particles, more light
Telling the lions from the squirrels
• These particles all had the same
energy, so “total light” is about the same
• but
pattern
in the
detector
is
very
different
Neutrino Patterns in MINOS
• This one has a muon
in it: that’s the only
thing with charge that
can travel through a
few feet of steel!
• This one does not has
a muon in it: hard to tell
in this detector
between muons and
anything else if many
particles are produced
MiniBooNE Detector Technique
• Who here knows what a sonic boom is?
– The noise that gets made when something goes faster than
sound
• Who has heard one?
– Airplanes
– Thunder
• When something goes faster than light, the same thing
happens, only instead of a loud boom, you get a flash
of light
MiniBooNE Detector
•
•
tanks contains 250,000 gallons
of mineral oil (neutrino target)
- 44 tanker trucks worth!
- 800 tons!
lined w/ 1520 PHOTOTUBES
(electronic “eyes”
of the detector)
Phototubes work like inverse
light bulbs
- produce an electrical signal
whenever light strikes them
Neutrino Patterns in MiniBooNE
muon
electron
How can neutrinos change flavors?
• Quantum mechanics presents us with a lot
of phenomena that seem weird & non-intuitive
- neutrino oscillations is one of them
- n’s can shift their identity & transform into one another
- particles can sometimes behave like waves
• Quantum mechanical state can be
the sum of several states
- let is suppose nm is sum of two different
mass states (or “matter waves”) …
- might seem odd, but is perfectly allowable
- can generate the interference pattern
we call neutrino oscillations 
sometimes
the waves are
in-phase
νμ
νμ
wave 1
wave 2
wave 1
+ wave 2
sometimes they
are out of phase
nm-ness begins to fade
Neutrino Oscillations
in much the same way as
beats are formed through
the interference of two
waves with different
frequencies
- neutrinos “waves” can oscillate between types
but only if they have different masses
- this interference causes first the disappearance
& then reappearance of the original n type
a
neutrino can change its identity!
How Do You Weigh a Neutrino?
oscillates
n flux
neutrin-o-maker
neutrin
-otaker
100% nm 100% nm
0% ne
0% ne
neutrin
-otaker
(100-x)% nm
x% ne
neutrin
-otaker
100% nm
0% ne
• so if we move the detector some distance away, a fraction
of the muon neutrinos will become electron or tau neutrinos
MiniBooNE is looking for: nm  ne at “Los Alamos” freque
MINOS is looking for nm  nt at “Atmospheric” frequency
What’s Next?
• Just Around the Corner: two experiments to look
at neutrino interactions with detectors that are
closer to microscopes
– SciBooNE: take detector from Japan, beamline from
Fermilab Booster
– MINERvA: bring brand new detector in, as well as
nuclear physicists who want to see if neutrinos can
tell what nucleus they are interacting in
– Both: will help still the next generation of oscillation
experiments
What’s next for Oscillations?
• Just around two corners: NOvA
– Best chance for seeing neutrino anti-neutrino
differences!
– Will use the same neutrino beamline as
MINOS
– Brand new detector in northern Minnesota:
better able to distinguish electrons (squirrels)
from anything else
Why Neutrinos and Anti-Neutrinos?
• Every fundamental particle has an antimatter partner
• When they meet, they annihilate into pure
energy. Alternatively, energy can
become matter plus anti-matter
So you might ask…
• The early Universe had a lot of energy. Where
is the anti-matter in the Universe?
• Good question… how do we know it isn’t around
today?
– look for annihilations.
– As far away as we can tell, today there aren’t big
matter and anti-matter collisions
– Maybe it’s the neutrinos which are different from antineutrinos!
Conclusions
• Neutrinos are everywhere all the time
• We wouldn’t be here without them
• We are just beginning to understand what
they are
• We have built the most powerful neutrino
beams and are getting to the best
measurements of neutrinos changing
flavors
• We’ve only just begun…
Thank you for funding our research. I find that when I talk
to people about the science that we do there is interest
and pride that we, as a nation, are able and willing to
pursue new and fundamental scientific
knowledge. Although many do not understand the details,
the American people seem to understand that
fundamental science is worth pursuing and is important to
the future of our country. We need to push back frontiers
of our knowledge. More practically, basic scientific
research proves to be a wise investment for the future
through creation and development of new technologies to
which it invariably leads. Thank you for the opportunity
you have given us to pursue this remarkable science.
Next, I would like to express deep respect and personal
thanks to my colleagues both within and outside MINOS
for your support, not only over the last couple of months
but over the last decade of building this facility and
experiment together. Scientific results are of course the
goal, but they come only at the end of a long and arduous
process. It is only possible to get there by working
together with people of great skill and diligence. The end
result may be just a hard number, but the process is
intrinsically human. It is a pleasure to have so many fine
colleagues with whom to share this work.
Finally, in my recent diagnosis and treatment I have
frequently found myself marveling at the technology that is
available for 21st century medical care. It is very
gratifying to me to know that many of the basic ideas and
techniques for modern imaging equipment were either first
developed IN our own field of high-energy physics or BY
people TRAINED in our field. I have gotten a first-hand
view of the remarkable achievements in the engineering,
technology, chemistry, and medicine which enable us to
effectively treat diseases like the one that I have. And just
as in physics, the glue that brings it all together and
makes it work are dedicated and skilled
professionals. Just as in our own field, the combination of
technology and people can produce fantastic results.
In Gratitude
Doug Michael, March 30 2005