Tonight's speaker is one of Jefferson Lab's own,
Douglas Higinbotham.
Doctor Higinbotham graduated in 1992 from
the College of William and Mary with a
major in physics and a minor in mathematics.
He attended graduate school at the
University of Virginia in Charlottesville,
graduating with a Ph.D. in nuclear physics
in January 2000.
He joined Jefferson Lab in 2001 and
currently has more than 100 publications.
In the course of his work he proposes ideas for new experiments,
coordinates with collaborators from around the world,
and helps carry out experiments conducted at the Lab.
He mentors doctoral candidates as well as
college and area high school students,
and has twice been awarded the U.S. Department of Energy's
outstanding mentor award.
Without further ado, I introduce to you Douglas Higinbotham,
presenting the Building Blocks of Matter.
[Applause]
So, thank you all for coming out tonight.
So, in 60 minutes we're going to cover three big questions.
What are the building blocks of matter?
What are you made out of? What am I made out of?
How do we do an experiment here at Jefferson Lab?
And, finally, why is it important?
So, everything I tell you about up until that point is basic research.
A basic question.
It's an old question.
It's basically a question man asked himself
once we started just hunting and gathering.
As we build up society, a very natural question,
"What is the world around us made out of?"
Many famous minds have pondered that question.
This is Aristotle's answer to that question.
And, if you think about it, think about the world you
would have lived in 300 BC, what was important to you?
Water, for survival.
The earth, for growing things.
Fire, for warmth.
And the wind.
For sailing, fishing.
All these things went together in a natural pattern.
And, though it's hard in Newport News to see
the night sky, certainly in 300 BC, in the evening,
you'd look up and see the beautiful stars in the heavens,
and all that stuff you couldn't explain with these four things,
so we'll call at the aether.
That was kind of Aristotle's out.
So, everythingthat couldn't be explained with
these four elements was ascribed to the aether.
That could be the divine substance.
This is a beautiful picture of everything.
I'm sure they're quite proud of themselves for coming
up with the building blocks of what they're made out of.
But, we didn't stop here.
I'm going to jump way forward...
This is the periodic table of the elements.
So, we've gone forward nearly two thousand years in human thought.
What you're looking at, and for those of you who had chemistry
class, this is a standard periodic table of the elements.
You've seen this before.
Hydrogen. Helium. Lithium.
This is an organization of all the
different elements people had found.
It was organized by its properties, so this row - hydrogen
lithium - these are all great materials for making fire.
Explosive, very reactive.
On the other side of this table, the helium, argon.
These are inert.
They don't react with anything.
In the middle, the metals.
The gold, the silver.
This is organized by the properties of the elements.
A very natural way to organize things.
What people hadn't yet done is figured out "Why?"
Why did nature arrange itself this way?
This is just organized by the property of the material and its weight.
Jumping forward another step.
Quantum-mechanical table of the elements.
It turns out that just by organizing things in a periodic table,
they were actually starting to get to quantum mechanics.
That's a big, scary word. Quantum mechanics.
What the heck does quantum mechanics even mean?
When you guys are driving a car down the road can go any speed you want?
What stops you?
Speed limits.
Okay, but can you go down Jefferson Avenue, can you go 43 miles per hour?
44? 45? 43.5?
You can pick any speed you like.
If you go too fast, the Newport News cops will pull you over.
But, it's any speed you like that your car is capable of going.
Quantum mechanics is a different world.
It's a world we're not that familiar with, but is around us.
It says all different variations are not possible,
only certain variations are possible.
You ever see a neon light?
It glows a pretty color.
It glows a single color.
It's a transition.
It's a quantum-mechanical transition.
Only certain wavelengths are allowed.
It would be like only certain speeds are allowed.
That you could only go exactly 45 on Jefferson Avenue.
Not any less or any more.
That's the idea of quantum mechanics,
only certain things are allowed.
And we get down to the very very small,
that's the way the world is.
Everything is in discrete steps.
And this periodic table, it turns out, is
showing those discrete steps.
Hydrogen, with one electron and one proton.
You then go to helium, with its two
protons, two neutrons...
And you've filled an outer shell.
Once a shell is filled, it doesn't
want to react with anything.
This whole concept, the coming together of quantum mechanics,
filling of shells, which was a completely new idea.
So, they were starting to figure out
that this huge table of elements,
where I have over 100 different species,
can all be described by something simpler.
Protons, neutrons and electrons.
This entire table, every element,
from your hydrogen to your helium,
all the way up to you very heavy elements
like uranium, plutonium...
Protons, neutrons and electrons.
Even cooler, as we studied our various elements...
This is hydrogen, helium...
Turns out they're different isotopes.
You can have different numbers of protons and neutrons.
So, for hydrogen, for example, just a proton by itself.
Or, proton with a neutron.
Or, a proton with two neutrons.
That's hydrogen, deuterium, tritium.
These are isotopes.
Still, all built up from protons, neutrons and electrons.
And, for me, in school this is
pretty much where the story stopped.
So, my high school education, protons, neutrons and electrons.
Those were the building blocks of matter.
That explained the periodic table.
If you understood a little bit of quantum mechanics, you
could actually understand why it went together the way did.
Beautiful.
But, is that the end of the story?
If it was, I probably wouldn't be standing here.
This is where we've gotten to today and
what Jefferson Lab is interested in.
So, this is a complex nucleus here.
Shown, built, of protons and neutrons.
Just colored red and blue.
If you zoom in on one of those objects, what we found
is that protons and neutrons are not fundamental.
They're made up of even more stuff.
So, starting with our earth, wind, fire, water...
You broke it down, we figured out it's
protons, neutrons and electrons...
We've now broken that down and found that our
protons and neutrons are made up something smaller.
And we came up with these fabulous words: quarks and gluons.
So, today. To this day, we still think quarks are
the fundamental building blocks of protons and neutrons.
And they're held together with glue. Gluons.
Scientists are very creative with their words.
So, this is today's picture of
the building blocks of matter.
This is all of them.
For most of what we do in everyday
world a lot of them don't matter.
The protons, made up of two up quarks and a down.
This is the entire table of all the fundamental particles.
I've even included the recently discovered Higgs boson.
But, this is it.
Up quarks, down quarks make protons and neutrons.
Two ups and a down is a proton.
Two downs and an up is a neutron.
And you can go on from there.
And there's all kinds of particles
we can make by applying energy.
Does anyone remember Einstein's formula? E equals...
What does that mean?
E = mc^2. Great. Energy to mass.
So, if I pump in energy into a system, I can make mass.
I can make matter.
So, one thing a lot of people don't appreciate is,
even at a facility like Jefferson Lab,
where we don't have the highest energies,
we certainly don't have the energy to make
a Higgs boson like they can at CERN,
but we have more than enough energy
to make the elementary particles.
Some are called pions, kaons, lambdas.
It's a whole particle zoo.
But we can pump energy into a system and make new matter.
By just pumping energy in.
And, what happens is, you end up with different
combinations of these fundamental particles.
For you and me, it's up and down
quarks making protons and neutrons.
The rest of this family of quarks are fairly esoteric.
Charm, strange, top and bottom.
All have been found.
Gluon holding it together.
Photons. That's certainly part for everyday
life, even including this laser pointer.
The electron.
Neutrinos, which have been very popular to study.
Very weakly interacting.
This is the family.
This is what we currently think would be
the complete Lego set to build everything.
And this really was the missing piece, the Higgs boson.
So we think we now have a set.
What we don't know, and its the mission
up this laboratory to understand,
how do you go from this set of
building blocks and make matter?
So, we understand protons, neutrons and electrons.
If I have those pieces, I can build up
the whole periodic table.
We have found these fundamental
particles by going to very high energies,
smashing things together, and
figured out this sequence.
What we don't know, and is
an amazingly complex problem,
is how do you put quarks together
and make a proton or a neutron?
How does nature do it?
So there's two thrusts going on at this laboratory.
One, theoretical.
We have a huge array of computers working
on the problem,
trying to solve something called
quantum chromodynamics,
which takes these building blocks,
puts it into a computer algorithm using
a model called quantum chromodynamics,
to see if we can figure out how
protons and neutrons go together.
Can we really model it?
Can we really start from this set and
make matter, at least computationally?
It's a huge effort.
Takes a lot of computing power.
Under way to this day.
At the other extreme, we experimentally
try to explore these particles.
What makes them really strange:
we never, ever see just one.
That's weird.
With a proton or a neutron or
electron, you can actually see it.
You always can see that one object.
Everything we're used to, everything
we're used to thinking about, I can break
it down to its fundamental block and see it.
With these guys, in general,
you only ever see combinations.
And by doing many many experiments and
seeing all the possible combinations
that you can observe, you deduce the quarks.
Now, my friends up in New York
take gold and smash it on gold at extremely
high energies and try to create a plasma
of quarks and gluons, which is a beautiful idea.
So, for a brief moment, you can liberate
these quarks and see them as individual
constituents in a plasma before it evaporates.
That's the best we've been able to do.
And, certainly experiments at CERN
are doing the same thing.
Here, we look at what these quarks
can make, and their properties.
So, I'll just give you a little
flavor of Jefferson Lab.
There are roughly 2,000 scientists who
make use of the facility here in Virginia.
There are very few places left that
do nuclear physics on a big scale.
Here in Newport News, Jefferson Lab,
and Brookhaven up in New York.
That's the big nuclear physics
facilities at the moment.
There's one more coming online in Michigan.
A lot of university of Virginia professors...
Virginia universities.
There's William and Mary, Hampton, Old Dominion...
They come here to do nuclear physics.
So, these two thousand scientists -
Virginia... United States... - and a lot
of people travel here to Newport
News to do their research.
I have a good friend from Slovenia,
Simon Sirca, who comes here.
It's really an international facility to study quarks and gluons.
We roughly get 10 Ph.D.'s a year from Jefferson Lab.
That's over a third of the Ph.D.'s in
nuclear physics in the United States of America
are granted here in Newport News.
So, this really is the hub of nuclear physics
research, in all places, Newport News.
We have college programs, high school programs.
I'm currently mentoring a high school student.
And these are fabulous programs to
help get people excited about science.
And any of you in the audience today really
interested in science should look out for
Department of Energy and National
Science Foundation opportunities,
not only at this laboratory,
but there's opportunities to go to
other laboratories over the summer.
So, go out the California to SLAC,
which is a high energy facility,
or even to CERN, in Switzerland, to see
what all is going on in basic research.
And as I said before, our basic mission
here at Jefferson Lab is to understand
how do you go from quarks and gluons
to protons and neutrons.
We think these are the fundamental
building blocks, so we'd really like
to understand how you go from
one to the other.
It's a fundamental question.
And, our problem is, you never see just one.
They're always confined, and coming
together in combinations.
So, I assumed, I think assume correctly,
that a lot of the audience would be young.
How many of you have done a science fair project?
About half.
So, I want to present a Jefferson Lab experiment
in the context of a science fair experiment.
How long does it take you to
a science fair experiment?
From beginning to end.
Days? Weeks?
How long you think it takes me to do an
experiment here at the lab?
[Amusingly Loud Kid] Years!
Years! Good job!
So this is just a cute experiment.
So, you know, how many paper clips
could you pick up with the electromagnet?
You probably could play with different batteries.
So, for your science fair project, using
this setup you'd have an introduction,
hypothesis on how it works,
you do the experiment,
and the most important thing for a science fair project,
data and analysis.
Data and analysis.
I've seen beautiful science fair projects.
They come up with great experiments and
they forget the data and analysis.
Right? You want to test the hypothesis.
You need to come up with some idea that you're testing.
Right?
So, for this picture behind me,
how many paper clips can I pick up?
I need a variable.
Maybe try different combinations of
batteries, different voltages.
Data and analysis.
And in the end, I draw conclusions.
I want a really big battery if I want to
pick up all the paper clips at one time.
Science fair project.
My science fair projects.
So, I may be 44, but I'm still doing science fair.
It's just gotten grand in scale.
So, Jefferson Lab.
Nuclear physics experiment.
I have an idea.
I have a question I want to answer.
Proposal.
It's already a little different than science fair.
Usually, you write a paragraph to your teacher,
she goes "Yeah, that looks nice. Electromagnet. Great."
Here, you write a document.
It tends to be of order 30 pages long,
though I have to admit that I've seen ones over 100,
where you write down your idea,
you reference all that has come before,
and what you expect to get out of the experiment.
You then defended it.
So, you take 12 senior scientist,
you stand up here,
just like I'm standing before you,
I try to convince them that this is the greatest experiment,
and we need to do it.
And, of those long documents we've written,
two-thirds are rejected.
In general, having worked here for
over a decade, the experiments that get...
That come here are all world class.
It's almost a shame we can't do them all.
This rejection factor - we lose two-thirds -
is really just a matter of time and money.
I can't do every single idea people come up with.
So, we have to prioritize.
We try to guess what the best science is.
And, part of that is picking a diverse
set of science experiments and ideas.
If your experiment hasn't run after three years -
3 years?!
This laboratory typically has a
five-year backlog of experiments.
So, more likely than not, even
if you've been approved,
you're going to come back and you're
going to have to defend it again.
So, your idea needs to remain topical.
If it's not, we'll pick something else.
Funding.
A lot of the experiments here need money.
They need new equipment.
So, not only do you need to convince our
panel of twelve distinguished scientist
it's a good experiment, you're going to need
to convince the Department of Energy or the
National Science Foundation or international
scientists "This is a great idea!" and we
should fund this. This really is going to have a huge
impact on the scientific community and human knowledge.
If you can get your money, avoid jeopardy, you can build it.
We then review the experiment to make sure it's ready,
both for its scientific point of view and for safety.
Then we run it.
Running.
How long you think an experiment takes run here at the lab?
Day? Year?
Most of them, about three months.
We've had ones go as long as two years.
We've had some that are just one day.
And everything in between.
But, in roughly a few months,
the average experiment gets done.
And, we can run as many as three
experiments at a time at our facility.
After the experiment is done, we've generated
information that gets analyzed by Ph.D. students.
Usually a couple of years.
And, it's the data from the experiments generating Ph.D.'s.
Finally, you get to publication.
Writing it all down.
And it's approximately one decade.
So, 10 years, from the beginning to the end.
Now, of course, people are just doing one experiment.
They have several going at a time.
So, you may be working on the idea of one while
you're building something for another experiment.
You're also analyzing some data for
an experiment that became before.
So, it's an ongoing process and people have
several experiments going on at any one time.
So, I want to give you one example.
So, we do many many experiments here.
I just want to give you an example, a taste,
of the physics we can do here and how we do it.
So, hear's a question: "What happens when a
proton and neutron get close together?"
So, protons and neutrons...
Yeah, so... Nope, she had... What do you think happens
when a proton and a neutron gets close together?
Anybody?
Yeah.
Nuclear fusion.
So, a proton and neutron free, go together,
would make deuterium.
That would be fusion. Absolutely.
So, in my cartoon here, I'm actually
showing nucleons in a nucleus.
So, this is suppose to be protons and neutrons
inside something that already exists.
This picture would be helium-4 with four.
But the proton and neutron can come close together.
Process of fusion.
Would it be possible to see the deformation of the quarks?
So, this is a cartoon of protons and neutrons,
but it's showing the three quarks in each one.
And it's showing two of them coming
together and starting to get distorted.
Could I do an experiment to probe that and learn a
little more about what's happening inside the nucleus?
What's happening inside carbon, for example?
In fact, that was the experiment.
The idea was take carbon and see if I can find inside
the carbon atoms, made of six protons, six neutrons,
see if I can probe carbon when the proton
neutron are coming close together.
See if I can see something special coming out of that.
So, electrons coming in, electrons scatter.
That's our primary tool here at Jefferson Lab.
Its an electron machine.
We take a beam of electrons, put it on a material.
It can be hydrogen, carbon, lead...
Whatever we like.
Whatever we're studying.
We know the beam from our accelerator friends
and we detect an outgoing electron.
Step one of our experiment.
If I want to see particles coming out,
I need to set up some detectors for that.
In this cartoon - electron in, electron out -
has knocked out a proton.
And I want to see what comes out, if anything.
But, I do that experiment.
This was originally proposed in 1997.
They somehow got off the hook for a year.
They came back in 2001 for jeopardy.
Finally got approved. So, '97 start date.
This is the aerial view of Jefferson Lab.
Jefferson Avenue along here, on the road.
So, those hills that you see when you're
driving buy are the tops of the domes where
our experimental halls are located.
Our accelerator starts here.
That's where our electrons are produced.
It's all under ground.
It's a racetrack design.
Electrons can go around as many as five times.
Then they're directed to one of our three experimental halls.
And they set this place up so we could run all three at
the same time in a pattern that goes 1, 2, 3, 1, 2, 3...
So it's a machine running at 1.5 gigahertz.
That's a big frequency, but everyone has
computers, so you've heard gigahertz.
And each hall receives 500 megahertz of beam.
We can do three experiments at the same
time here with our accelerator.
This is the cartoon view.
First picture is making the electrons.
So, does anyone still have a CRT TV?
The big, heavy TVs? Yeah? A few of you.
All those TVs were the way we used to make electrons.
Literally bent wire, run a current through it,
you can liberate electrons,
can focus it with a cathode, put on
screen, you make the TV work.
That's history.
So just like only a few of you have that type a TV,
we don't make electrons that way anymore.
We use lasers.
Yeah, lasers are cool.
In fact, Einstein didn't win the Nobel Prize for E = mc^2.
Einstein won the Nobel Prize for the photoelectric effect.
The idea that you could put laser light, put photons,
on a surface and liberate electrons.
So, all of the electrons that are liberated here
Jefferson Lab are done with the laser shining on
a material called strained gallium arsenide.
That makes our beam.
Goes around our racetrack as many as five times
and then split off to our experimental halls.
This photograph of our accelerator that pushes
the electrons along, gives them energy.
And our arcs, that bend around.
These are simple bending magnets.
And these are superconducting accelerators
to give the beam energy.
Six billion electron volts is
what we used to be able to deliver.
We have just upgraded the machine.
We've just got approval to run.
Actually, had the Virginia governor
here just couple weeks ago.
We can now get up to twelve billion electron volts.
The reason we push in energy - the higher I go in
energy the smaller distance scale I can see.
So if I want to see the very very small,
I need very very high energies.
That's why all the facilities, whether it's
Jefferson Lab or CERN, when I want to see the very small,
whether it's quarks and gluons or Higgs bosons,
requires tremendous amount of energy.
And this is the principal that drives that statement.
Heisenberg. One of the old masters of quantum mechanics.
So, one formula. One formula only for
tonight in my slides.
Delta-x delta-p greater than h-bar over two.
Uncertainty in position times an uncertainty
in momentum must be greater than h-bar over two.
For tonight, it's just a number.
Point two GeV times femtometer.
What Heisenberg's talking about is it's impossible to know
exactly the position and momentum of something at the same time.
It's again a quantum mechanical idea.
One you're not used to except, in a way, we are.
Ever used a camera?
If someone's running really fast and you take a picture
with your camera they look blurred in your photograph.
So, you know when you took the picture.
Where are they?
They're blurred. They're spread out.
So, you know time, but you don't know position.
If I use very high speed film and photograph
that same runner, they're stopped.
There's no blur.
Now I can't tell how fast they're going.
It's from the blur that you can tell, from looking at photograph,
if you know the speed of the film, how fast they were moving.
So, there are examples in the classical world of this same
uncertainty principle, and the cameras just a nice analogy.
This is a fundamental limit.
As far as we know, no way out.
On the other hand, it explains why at Jefferson
Lab we want to go to very high energies.
So 10 billion electron volts, or 10 GeV, lets me get
down to see a small fraction of the size of a proton.
Really lets me see what's inside.
This is a cartoon of one set of our microscopes.
We call them spectrometers.
In this cartoon we have people, here.
This is in our Experimental Hall A.
Electron beam in.
Put a target material in the center of our hall.
I detect scattered electrons and
scattered protons in these devices.
This is what it looks like in real life.
Cartoon. Two microscopes.
Real life. A mess.
Target's still in the center of the room
and here's that spectrometer.
The same device. Absolutely enormous.
I need the really big to see the really small.
I need very powerful magnets and detector systems.
And this physically is what it takes.
One thing that's great about this photograph
is there's a big empty spot.
And scientists love to build stuff for an empty spot.
So, back to the experiment.
The idea they had in mind, send the electron beam in,
detect a scattered electron, detect the scattered proton,
and see what comes out.
Does one thing come out, lots of things come out?
And thats where the blank spot is,
where the stuff would come out.
Would I see a proton coming out,
would I see a neutron coming out?
What would I see?
The idea require building new equipment, shown in a cartoon.
They wanted a new scattering chamber,
someplace to put their target material.
A bending magnet.
A scintillator and a neutron detector.
They detect protons coming out or neutrons coming out.
We gathered the magnet from Amsterdam.
This is it sinking into the Dutch soil.
We brought it here. Recycled it.
Group in Israel made particle detectors for us.
A group in Glasgow mode more of our detectors.
University of Virginia built the scattering chamber
for our particles.
And Kent State provided neutron detectors.
So, for all the experiments we do here at the Lab,
it tends to be a community effort, an international effort,
getting scientists here building equipment
they'll set up in the experimental hall.
And this is what it looked like when it was all put together.
They have a bending magnet, so if a proton came
back it would be bent up and detected here.
Neutrons have no charge, so they don't get bent by a magnet,
would pass through a lead wall and be detected this back detector.
So, they had a great experiment to do.
Electron in, electron out.
Protons going forward and see what comes back.
Are they protons coming back, neutrons coming back, to try
to learn something about when particles are close together.
They started in '97. Reapproved in 2001.
We finally ran. It only took a few months to actually run.
We had three Ph.D. students: one from MIT, one from
Tel Aviv, one from Kent State; here, in Newport News.
They lived here for over two years, analyzing that data.
They start with the information of charged particles passing
through matter and turned that the physics quantities,
compare a theory, write theses and papers.
So, finally getting all that done.
Three Ph.D. theses, an article in the Journal of Science,
Physical Review Letter, all written up about what we saw.
And what we saw surprised a lot of people,
surprised a lot of scientists.
We came in on carbon.
Electron in, electron out.
Proton forward.
And what we saw was always a neutron coming back.
It was as if, in carbon, there are
quasi-deuterons sitting there.
The expectation was we'd see lots of
proton-proton and neutron-neutron pairs.
Real life was proton-neutron.
That's why it was an exciting result,
it wasn't what people expected.
It got a lot of press.
And we tried to do a good job of
explaining to others what we saw.
And the importance, beyond this cartoon of
carbon, with a proton-neutron close together,
this actually has implications all
the way up to a neutron star.
This is a cartoon of a naive
picture of a neutron star.
It's mostly neutrons.
And, naively, you'd go "Oh, there are a few
protons. They're not going to matter."
"It's mostly going to be about a sea of neutrons."
What our experiments said is "No, protons
really want to pair up with neutrons."
So, in a system like a neutron star, where there
are only a few protons, they're not going to just
be sitting there doing nothing. They're going to pair up and
they're going to play a very important role in the neutron star.
That's a paradigm shift and, to this day, this has become
a very important result has been reconfirmed several times.
So, from beginning to end, about a decade.
So, we did an experiment where we learned a little bit about what
happens inside a nucleus with protons and neutrons coming together.
It has implications not only for nuclear physics, but astrophysics.
I think that was pretty cool.
But...
Who cares?!
This is all basic research and it's nice, it's nice figuring out
what we're made out of, but is it worth all the time and energy
and thought that goes into doing these experiments?
Who cares?! These are expensive experiments to do.
So, I'm going to give you a few examples of who cares.
One. Kathy McCormick. She got her Ph.D. here at
Jefferson Lab and went to work for Homeland Security.
This is a truck driving past something.
Does anyone have a clue what that might be?
It's a particle detector!
Absolutely! If you want to know, in the trans-containers that
are coming through Hampton Roads, through our shipping system,
that there's no bombs - nuclear bombs - you need
some way to detect it and it better be fast,
because when you're working with business, time is money.
Here's the idea.
Put particle detectors that the truck gas to drive by.
At the same time, we're weighing the truck.
If you do have weapon in that truck, a nuclear weapon,
were either going to detect the radiation,
because a nuclear weapon emits radiation that we can
easily detect with the particle detectors we use here
at Jefferson Lab, or you have shielded it was so much lead
your truck's going to be way overweight.
Either way we're going to know something's funny,
stop the truck, and inspect it.
So, Kathy McCormack cares about nuclear physics.
Who else?
Gordon Cates, professor at the
University Of Virginia.
He was very interested in something
called polarized helium-3.
He wanted to study the neutron.
Helium-3 has two protons, one neutron.
We've known for a long time that the magnetic moment
of helium-3 is very similar to the free neutron.
So, he's trying to learn about
a free neutron using helium-3.
He came up with a very clever way to polarize
helium-3, so that neutron had a definite direction.
Then he had a brilliant insight
just talking to his friends.
They were complaining about the inability of an MRI machine...
Magnetic resonance imaging, which is
really nuclear magnetic resonance imaging,
but they don't use the word 'nuclear' at the hospital.
Nuclear magnetic resonance imaging of the lungs.
This is what a picture of your lungs
looks like in an MRI machine.
Has anyone sucked on helium gas from a balloon?
Yeah, it's inert. On that periodic
table it's on the inert side.
What if you sucked in a little Gordon's
polarized helium-3 gas and did the MRI?
That's this picture.
So, Gordon came up with an idea,
just working with this friends,
who was actually Princeton at the time,
listening to people complain about their
inability to do an MRI of lungs,
says "Hey! I have polarized helium-3!
Let's try it out!"
They literally tried it in a baggie and a straw.
Suck some in. Did the image. And - POW - it worked.
So, Gordon cares.
Who else cares?
Tancredi Botto. This is one of my colleagues
from when I was doing my Ph.D.
He went to work for Schlumburger.
Oil exploration. What the heck does oil
exploration have do to with nuclear physics?
How do you know where to drill?
Schlumburger's a company that's been around
for almost one hundred years now.
They tell people where to drill.
What Schlumburger does, they drill exploratory
holes, they then put a particle detector and
a radioactive source down the hole, taking data
the whole way down.
They can tell you from the data exactly what the
rock formations are all the way down the hole.
So, they're using particle detector techniques to map out,
down over a mile, all the different rock formations.
And, when you're drilling for oil, you look for
certain formations to know where to drill.
So, oil exploration also relies on nuclear physics.
Thea Kepple cares.
She works here Jefferson Lab and was Scientific Director
at the Proton Therapy Center here in Hampton.
Inoperable tumors. How do we go after it?
We have built, here in Hampton Roads, a proton accelerator.
Leveraging the resources and knowledge and people
here at Jefferson Lab,
as well as some very charismatic people at Hampton University.
All got together. They built a proton accelerator here.
What's really cool about protons is that they stop very suddenly.
If you have an inoperable brain tumor,
they can put a beam of protons through your skull,
through your brain, and have them stop on the tumor,
leaving all the radiation right on the tumor.
Thea cares.
And this is just a huge windfall for
Hampton Roads. A world-class center.
And, finally, who else cares?
And this is probably the oddest example of all.
James Simons cares.
Last I checked, he was the 88th richest person in the world.
James Simons was the originator of quantitative finance.
He took the techniques and skills - mathematics, etcetera - that
we use here in our everyday research, and applied it to finance.
His original paper dates back from the late sixties.
So, his company was one of the first.
What's amusing about his company,
he will not hire you with an MBA.
He doesn't want business majors.
He only hires Ph.D.'s in math and science.
He can teach anyone business, but he can't teach
many people quantum mechanics or differential equations,
Monte Carlo simulations, all the tools that
we use and scientists just know a priori.
He hires some of our best and brightest.
They apply that to business and I think
that number speaks for itself.
He's done extremely well in quantitative finance.
So, there's just a few examples, and I tried to
span the gamut of things beyond basic research
that have come from Jefferson Lab.
So, time to wake up and ask some questions.
Thank you!
[Applause]
Yep! In the back.
[Audience Member] What's the purpose of sending
the electrons around the track five times?
Ah! Excellent question.
So, the reason we're sending the electrons around the track
five times is each time around they get more energy.
So, at a facility that came before us in California
called SLAC, they took the electrons and accelerated
them down a mile through an accelerator. And it
turns out it's the accelerator,
the accelerator pieces, that are extremely expensive.
So, the clever idea they had for this facility is
"Let's bend the being back around."
And magnets to bend the beam around are cheap.
So, we accelerate, bend around, accelerate,
bend around, and go right back through that
same accelerator again to get even more energy.
It's all about money.
I can put the accelerator in a smaller footprint, and
it's just cheaper to build and get to the same energies.
Yeah.
[Audience Member] Going back to that,
why is it limited to just five times?
What will limit you in the end and, actually, we have
basically hit the limit with our 12 GeV upgrade,
as a charged particle get bent around, it'll start
emitting radiation, synchrotron radiation and
that grows very fast with energies. So, eventually
you'll hit - your radius is basically too tight.
So, it's almost like a race car at the racetrack.
You get up to 200 miles per hour, 300 miles per
hour... I just can't make the turn.
Same idea, different situation.
Yep.
[Audience Member] How long is it exactly around
the whole underground part of the accelerator?
Roughly a mile. You start from the injector,
go around and go into the hall.
Yep.
[Audience Member] (Too faint to make out.
Something about the size of the domes.)
So in the halls, some the domes are bigger than the others.
I only talked tonight about one of our
experimental halls. It had two spectrometers.
What I didn't mention is those two giant spectrometers
can move. We can rotate them in angle.
So, we need a huge room to be able to do that.
And we have - That particular hall has the biggest dome.
The hall immediately beside it has a very small dome.
Their detector basically looks like a giant,
hollowed out egg.
Nothing moved. So, an enormous detector, but it fit in
a smaller room because they need to move anything.
So, those hills are really custom... are built above
customized set-ups for each of the experimental halls.
And, the idea was, different experiments
needed different set-ups.
In a very general level, Hall A was two microscopes
that could move, Hall B had a static set-up,
and in Hall C, you could build whatever you wanted.
[Audience Member] You mentioned this when you were
talking about funding, but that most of the funding...
All the places you named were federal agencies. Is there
any private people that invest in this kind of research?
Any private corporations?
So, one of the biggest at the
moment actually is the Simons Foundation.
So, James Simons, who was originally a math professor,
then went into quantitative finance, had helped directly
with the funding of our sister lab in Brookhaven.
And, probably the more important thing he's
done is created the Simons Foundation,
which is providing a lot of money
for something called The Archive,
where we, as scientists, put our
work so it's publicly accessible,
So, yes, there are some private revenue streams.
For our federal funding, I think what's most important
is our international collaborations and the international
money that comes here because it's really easy raise
your hand and say "I want money."
Has a lot more weight if you also get your
colleagues from Japan or Germany or anywhere
on the world that also say "We want to do this
and were willing to contribute."
That helps tremendously.
And on all of our big experiments we built big,
international groups where they all bring in
their manpower, their equipment, their money...
Come here to help get it done.
Yeah.
[Audience Member] When an electron turns,
it loses energy, correct?
Yes.
[Audience Member] So why don't you just make it,
like, just unfold it from, like, an oval,
into just a straight line, so it doesn't
lose any energy and it keeps accelerating
and accelerating and it hits the,
it hits the speed of light?
So, the question was, "Why not just make a straight line?"
And you also mentioned the speed of light.
So, I'll hit both.
So, our friends in California, at SLAC did
the straight line accelerator.
It's more expensive. It's as simple as that.
It's more expensive to make the long straight
accelerator than to make the oval set-up.
But, you're right, they can get to a higher energy.
They'll never have the limitation of the bend.
It's a trade-off.
The particles we accelerate here at Jefferson Lab -
We take electrons, one of the smallest fundamental
particles we know, and accelerate it as had as we can.
Twelve billion electron volts.
It's going 0.99999... the speed of light.
Brute force. You can't get past the speed of light.
We keep putting in more energy,
is still going the same speed.
You never get exactly to the speed of light.
Yep.
[Audience Member] ...always have to go at the speed of
light or can you slow everything down to see what happens.
(... unintelligible ... )
Do you always hit the same place at the same time
at the same rate, or do you...
So, it's very much a...
So, when we're doing an experiment here, it's very statistical.
So, I'm taking a foil of carbon and I'm putting
the electron beam on it and I'm looking at lots
and lots of events so I can figure out what happens.
It's almost like playing a game of pool where
someone's always setting the balls in the same place
and you're firing the cue ball in there and
you see where the balls come out,
but you don't actually see the moment that it hits.
I don't see that part and that's actually
makes nuclear physics really hard.
I see what comes out. I have to figure
out what happened.
But, you do enough experiments, if you
watch the pool table even, in fact,
you never saw the rack of balls, you could figure
out it was there by seeing where all the balls go
when you fire in from different angles.
Yeah.
[Audience Member] Is it safe (... unintelligible ... ) underground?
Yes. So, when Jefferson Lab is running,
we have something called prompt radiation.
That means there's radiation when our machine is on.
There's radiation from the electrons bending.
There's radiation from the electrons
hitting a material.
We turn our beam off, almost
all the radiation is gone,
with the exceptions of the material I'm
hitting or have passed the beam through,
it will still be activated, and our dumps.
So, if you look carefully from Jefferson Avenue,
you'll see little tails behind those domes.
They have large vats of water at the end that
catch the beam.
[Audience Member] ...it's not going to get anybody.
We dont... We aren't in there when the beam is running.
And they're very careful to make sure no
one's in there when the beam is running.
So, beam running, everyone's out. We have a
key system to make sure no one is in. Yes.
Yeah.
[Audience Member] Is the radiation emitted
from the electron mostly EMF or alpha/beta?
So, it would be electromagnetic. So, alphas and betas would be
if you're hitting a target material and knocking stuff out.
Yeah, in the back.
[Audience Member] I mean, as best I understand it,
as something goes to the speed of light,
it'll also be increasing in size.
Starting off as at this, by the time it gets,
by the time it got 1200, 12 volts. I mean, 12...
Whatever the number is. How much larger
is it that it had been?
I don't like... I don't think 'large' is the right
way look at it, but you can look at it as massive.
Mass. So, an electron, in the units that
we're using, is half a mega-electron volt.
We'd say half an MeV.
And we're accelerating it to 12 GeV.
So, we've put more energy in it than it weighs.
Which is an unbelievable amount.
And we've seen pictures of a nuclear
explosion where we took some material
and turned that material partially into energy.
We take the electrons here, we've now put
more energy into them then their mass.
They're still not going faster than the speed of light.
Now, whether you want to look at it as it gained mass
or it gained energy, it's two sides of the same coin.
And, quite frankly, it really depends on how you
want to look at the information you're getting.
Whether you want to think of it as a very massive
thing coming in or a very energetic thing.
It doesn't matter. E = mc^2.
Energy. Mass. There's an equivalence there. So, its okay.
Yeah.
[Audience Member] When you run your
machine, you said it emits radiation.
So, where does this radiation go
when you aren't using it anymore?
So, the question is, "Where does the radiation go
when we're not using it anymore?"
So, for example... I said we turn on the
electron beam, it's making radiation.
I turn it off, it's gone.
So, electrons going around there arc
are emitting a lot of photons.
They're being absorbed in the walls down in the Hall.
And, as soon as you turn it off, all those photons
are going at the speed of light, bounce around,
hit the walls, get absorbed. They're gone.
Going into heat.
The same thing is going on when you go
through the x-ray machine, or your bag
goes through the x-ray machine at the airport.
They're putting radiation on your bag.
They're looking at what passes through, the x-rays
passing through the bag, and what's getting absorbed.
Turn off the machine, it's off.
[Someone in Audience] Or your microwave oven.
Microwave ovens.
[Audience Member] What's the configuration of your carbon target?
Just a foil. I order it from a company called Goodfellows.
They will send you a nice big sheet of carbon.
We cut it down to a nice foil.
Put that foil in the beam so it's perpendicular.
Run the beam straight through it.
It's a very simple set-up and it's very easy to
get homogeneous carbon, pure carbon.
[Audience Member] (... unintelligible ... )
What are the walls made of? Concrete!
The wall's made out of concrete.
[Audience Member] How does, how does
a photon get rid of a tumor?
That's -protons- that are getting rid of the tumors.
So, again, the idea is radiation can damage cells.
That's kind of why we worry about getting exposed to radiation.
It can damage cells. You can get a tumor.
On the other hand, if I can put the
radiation in in a controlled way...
So, the proton therapy machine here in
Hampton very carefully...
They would do an MRI. If you heard brain
tumor that was inoperable.
That means I can't operate get it out.
I do an MRI scan of your head.
I'd locate exactly where the tumor is.
And then I would put the protons exactly
on the tumor.
The technology to build a machine like the proton
therapy machine has been around for decades.
The problem was we didn't have the
technology to make use of it.
You really needed an MRI machine.
You need to be able to scan the brain
to know where the tumor is very precisely.
I don't want to put the proton beam and have protons
stopping on good tissue, I only want it on the bad.
So I needed an MRI and I needed a computer.
I needed a powerful computer really to
control where I'm putting those protons.
So, it's a really clever trick.
I'm going to put protons and I'm going
to have them stop just on the tumor.
Just on the thing I want to kill.
So, I can use radiation to kill the bad stuff, too.
So, in this case, we're using
radiation to do something good.
Yep.
Speak up?
Oh, okay.
Yep.
[Audience Member] If you were in, like, the proton therapy,
and if they shot it at the tumor in your brain,
would the radiation go inside of your body?
So, the question... If you had the proton machine and they're
hitting you with protons, does the radiation get in your body.
A little bit.
And, there are tradeoffs.
So, most of the energy from the proton will stop on the tumor.
A little bit goes through your brain and
a little bit will get absorbed.
The clever thing that they do when you go in for
a brain tumor treatment, you come in one day,
they'd send the beam in from your left side and,
next time, from the right.
They come in at different angles.
So, they're not going through...
So, they go through different parts of your brain.
Give very small dose as possible to brain tissue,
good tissue, while maximizing the dose on the tumor.
Try to kill the tumor.
Any small amount of radiation can harm you,
so you want to keep it minimal.
But, very small amounts have been shown to do very little.
In fact, we're getting it right now.
You're always getting radiation.
So, the rate of radiation we get right now is called a millirem.
We get roughly 365 millirem a year of radiation.
And that's just part of being here on this planet.
Radiation comes from our sun, hits our atmosphere, cascades down,
and there are particles passing through us as we speak.
So, a square meter - so this table - it's a hundred
particles per second are going through this table.
Right now.
I can't see them, but they're there.
So, radiation is around us all the time.
And, that's one misconception people have about radiation.
They just hear 'radiation' and go 'BAD!' without really
learning about it, what it is, that it is around us.
And, there is a trade off between
medical applications of radiation.
When you're at the dentist. You have
a dental x-ray to look at your teeth.
So, you're getting a little bit of radiation, and the
benefits of being able to see the cavities before they
develop into something worse outweighs the risk of
getting cancer from that little bit of radiation.
So, it's always a trade off.
[Moderator] Let's take a moment. Some of you
may be getting ready to leave.
Some of you may wish to stick around a little bit longer.
I'll go ahead and open the door, or you can use the back door.
If you need a piece of paper signed for school,
we do have staff out in front to take care of that.
The rest of you are welcome to stay
and continue asking Doug some questions.
So, if you have any more questions, just come on down.
Thank you very much!
[Applause]
