PRESENTER: I want to thank Dirk
for a wonderful introduction.
And it makes my talk
immensely easier
because I can concentrate
on how we did it.
And he showed you a
lot of what we did.
I'd like to say one or two
things about our engines.
Bill is correct
that we missed out
on the golden age we heard
so much about yesterday.
We'd been writing at
least one proposal a year
since about 1962.
And the first proposals
were for 140 MEV machine.
And we were in
internal competition
for tandem Van de Graaff.
And this went on
for several years
where Van de Graaffs were
put in other universities
and 140 MEV machines were
put national laboratories.
And there was
about 1964 a caucus
in which it was decided to
go after a 500 MEV linac
if you can't get 140.
So try for 500.
And through the help of
Arthur [? Curman, ?] Herman
[? Feshback, ?] and our
theoretical friends,
it was decided to go after
only an electron machine.
And we heard from Fred
yesterday that in 1966 we
got a phone call saying
will you settle for half.
And we had been settling for
something like that ever since.
Now Bill mentioned Peter Deimos,
Phil Sargent, Stan Kowalski,
myself, as people
who were frustrated
at the kind of machinery
that was available
and who were pressing the issue.
And when the money
was appropriated,
it became urgent to get a
couple of professionals.
One in accelerator design
that was Jake [? Hameson. ?]
And he came for a few years.
The other was an
expert in wheeling
and dealing and haggling.
And that was Paul Reardon.
He also came for a few
years, got us rolling.
And what we built, and what
we've operated for a long time,
is indicated here.
I'd like to tell you
a few things about it.
I'll use my time.
I won't go through
the whole story.
Not conceivably.
Now what you notice
is that there's
been a huge traffic through
that place in those years.
75 graduate students who
have got their PhD theses.
That is probably our
most important product.
Those are the Bates babies.
You'll hear from one
in the next lecture.
And Dirk mentioned that.
Now that work has
been carried out
by a very small
number of people.
This is the present
distribution.
I don't expect you to
remember any of this
but I'd like to point
out a number of things.
If you look at the
distribution, you'll
notice that the academic
staff, research staff,
and graduate students,
overwhelming numbers
or at least are equal to
the so-called support staff.
And you wonder, how can
you do that kind of thing.
Well, what you have
to do is you have
to have a support
staff which is as
talented as the graduate
students and the research
staff.
And if you have then
100 very talented
people who work very hard,
you can do a lot of stuff.
And that's the way
the place works.
We have smart people
working very hard.
There is a consequence however.
The organization chart that
Fred showed you, maybe the way
it looks from the dean's
office, but on the floor
this is what it looks like.
It's a conference among peers.
I defy you to find
the director in there.
I work with two directors
and for each of them that's
been the organization chart.
We have a new management
since November.
I'd be interested to
see a few years from now
whether that still applies.
You might notice
that that also looks
like a theory seminar at MIT.
One other thing that's
been remarked upon
is that over the
years, the generations
look younger and
younger, especially
you notice when the
freshman class comes in.
That's the truth.
But at Bates, the situation
is even more absurd.
This is another [? Flans ?]
instructing his elders.
Now OK.
There is an opportunity
to visit Bates tomorrow.
It's open house
and the laboratory
is about 25 miles
north of the city.
MIT is about 25 miles this way.
Cranes Beach and Plum Island
is about 10 miles that way.
And it is a very
gorgeous campus.
It is on campus according
to MIT's administration.
The laboratory is named
after William Bates.
It was the congressional
representative
from that district who helped
us get that land at a very
crucial time.
The laboratory schematically
is shown here color
coded with the code indicated
at the bottom showing
how it's grown over the years.
The original proposal
contemplated all of that
except for the ring out here,
which is the project presently
under way.
It was for 500 MEV to supply
a high resolution spectrometer
and a coincidence capability.
Now when we had
to settle for half
there was convened
in 1967, a summer
study in which all the options
were vigorously debated.
[? Ratosie ?] was a forceful
presence throughout that.
Out of it emerged--
and it was a joint
seminar with the people
with [? Sakhalin ?]
who were building
a machine at the same time.
They however, were not
financially embarrassed.
They built both sides.
We decided to build a
high resolution facility
for electron scattering.
Now very roughly, the beam
energy now goes up to a GEV.
That was accomplished
by taking the beam
and recirculating
it one more time.
This was a project
that was undertaken
by Phil Sargent and Jay
[? Flans ?] and Stan Kowalski
and has been successful.
High currents, 1% duty, 1%
duty factor, and the work I'll
show you has been
done mainly with that.
We are presently
engaged in an upgrade.
It's been referred to as the
south hall ring experiment.
At the end of that, we expect
to have approximately 100%
duty factor.
With the other parameters
more or less the same.
Now for those of you
who won't make the trip,
let me show you some pictures.
Here's a view of the
accelerator looking
at it from the injector.
It's not quite as
infinite as slack,
but it's all a matter
of perspective.
Here's a picture
of the same thing.
Now with at a later time
where the recirculator magnets
are installed.
They're not really that big,
that's a matter of perspective.
But those are surplus from
University of Michigan.
Those of you who make the trip
will notice that at least half
of the hardware around
there is hand me downs
from one place or another.
That's one way of
coping with poverty.
We have produced
and had operating
a complement of spectrometers.
I just list them here.
This is the high resolution one.
Big project to the
60s and early '70s.
[? Bertossi, ?] Kowalski,
Williamson, Sergeant, myself.
A medium energy pion
spectrometer, our [? bloom ?]
fist.
Aaron Bernstein, the RPI group.
[? Ohips, ?] June Matthews,
and her associates.
Big [? bite, ?]
[? Clod ?] Williamson.
Ed Booth with a
[? pi zero ?] spectrometer.
And now these have
all been operating.
Now we're in the process
of building something
called an outer plane
proton spectrometer system.
Let me show you some pictures.
There's the high resolution
spectrometor system.
LC here.
These are three, four
magnets of a [? ciccane, ?]
which allows us to do electron
scattering at precisely 180
degrees, which is
important if you
want to get the magnetization
densities that Dirk was talking
about.
This is a project that was
funded by the government.
DEO or [? Ert ?] one
of those outfits.
And done by the University
of Massachusetts.
Jerry Peterson and Jay Flans who
was a graduate student there.
That was his thesis.
That's an example,
one good example.
Another thing that makes the
laboratory viable in spite
of the small numbers and that's
the contributions of the users.
This is a good example and
that system worked beautifully.
Just one further remark.
That some of you may
recognize as Bill Lobar
who claims to do everything.
And that's proof.
These are coincidence
spectrometers
in the south hall.
This is the one, this
is [? Meps, ?] this is
[? Ohips. ?] This one was
designed by [? Engar ?]
[? Bloomquist. ?] And this
one was built out of surplus
magnets.
And here is schematically what
the autoplane spectrometer
system will look like.
This is the [? Ohips ?]
and here are
four quarterpole, dipole
combinations whose intent will
be to measure the out of
plane coincidence protons
from proton knockout.
And in fact, one of
these has already
been built and tested and
used in an experiment.
The first ever measurement of
the so-called fifth response
function.
This was using
polarized electrons
on a carbon and deuterium
target and measuring
the angular distribution out
of the plane of the knockout
protons.
This is an experiment
that was jointly
done by the
University of Illinois
group working under
Papa Nicholas and Bill
[? Ratosi's ?] group at MIT.
Now why did we initially settle
for just a high resolution
spectrometer?
Well you must remember the time.
The time was the early 60s,
middle 60s when shell model was
and the mean field was in the
process of being developed.
There was a lot of interest
in how can the nucleus coexist
as a collective manifest
collective properties,
and how does that come out
of the motion of nucleons
in a mean field.
How is all that
story put together?
And the available data
were mainly moments.
The integrals over the
radio wave functions.
The form factors give
you the distributions.
Now there were some data
and they were enticing,
but they were very fragmentary
and the reason was twofold.
One, the available
currents were very small.
One microamp was a
terrific current.
And the resolutions were awful.
The best was 10 to
the minus 3 and that
was insufficient to resolve
very interesting states.
So what was done was
to build a system that
would use every electron that
the accelerator would provide.
In the case of the
base accelerator,
it was like 10 to
the minus three.
And design the system so that
you could do resolution--
you could achieve resolution on
the electron scattering of 10
to the minus four or better.
So a very wonderful project.
Worked beautifully,
as I will show you.
Here is a very good example
of the kind of thing that
can be done, has been done.
The reason why the
resolution is so important.
Here is gadolinium
Well, gadolinium 154.
Where previous spectroscopy it
indicated that the low lying
states could be described as
a mix of a rotational band,
k equals zero.
Where is this?
Beta vibrational band and
a gamma vibrational band.
And the high resolution was
important for two reasons.
One of course is to
separate the states.
The second, if you look at the
zero plus beta and the two plus
beta, if the resolution
were not very good,
you wouldn't see that coming
out of the background.
So those two major motivations.
How much time do I have?
So here are
transition densities.
Based on the three
two plus states,
the rotational state at
the top, the beta vibration
in the middle, and the gamma
vibration at the bottom.
And as you can see, the
location of those distributions
beautifully support the
collective description.
At the same time
of course, there
was, and had been underway,
a very extensive set
of calculations by
John [? Negley ?]
and many of his collaborators
on the microscopic description
of these transitions.
And here is the ground state
density for the same nucleus.
One is theoretical and
the other is experimental.
And the differences are not
visible in a display like this,
but they are in the region
that I've indicated in color.
Now there is of
course by this time
several thousand
spectra form factors
in all regions of
the periodic table.
Here for example, is a series
of ISO density distributions
in the same region
of the periodic table
as I just showed you.
And up until yesterday,
I had the impression
that the theoretical
activity had more or less
subsided in this area.
But I was happy to hear
from Steve [? Kunin ?]
that there is now
a new initiative
to refine further
the mean field.
It will be very
interesting to see
whether the more
vigorous computers can
cope with data of this kind.
Dirk showed you some data
on the lead region which
I will therefore
skip and move to what
has been a preoccupation
in the laboratory
for the last oh, the
last decade maybe.
And it has to do with the
connection between the nucleon
nucleon force and the
current in the nucleus.
Oh there we go.
The nucleon nucleon
force generally
is understood in
its longest range
to be the exchange of
a pion and that pion
should manifest itself if
it's charged in a current,
and that current should be
detectable in an electron
scattering experiment.
This is the first
statement that that
should be manifested
as a current which
should be detectable
was pointed out by Felix
[? Velarez ?] in the late 40s.
And it is taken
until just recently
for that to become sorted out
in a very systematic and almost
believable way.
The present agenda in nuclear
physics is summarized here.
And in order to get
at those questions,
there is imposed on us a number
of experimental requirements
that we have been systematically
working to achieve.
You have to-- if you
want the short range you
need high Q. High Q implies low
cross-section, which therefore
experimentally implies
high luminosity, product
of luminosity, SONET
angle, and detection.
This should be epsilon
detection efficiency.
You ought to do the
coincidence experiments.
That implies the duty factor.
Many of the
interesting amplitudes
are small and have to be
extracted in a interference
experiment.
That implies spin in the
beam target and the recoil.
And because one is getting
at the fundamentals,
you want to use simple targets.
By simple meaning few hadrons,
like the [? deuteron ?]
and the helium-3 and the
[? triton. ?] Experimentally
of course, that theoretical
simplicity comes very
expensive.
Now to get the
polarized beam, there
was, as Garrick mentioned,
as frequently happens,
an experiment gets started.
You produce some
piece of hardware
specifically for
that experiment,
and it turns out to be generally
applicable for a long range
program.
So an investment
that may appear to be
large for one small
experiment extended
over the life of a
program is per year
or however you want to
measure it, not bad at all.
And the polarized electrons
appear in the laboratory from
Vernon Hughes and
Paul [? Souttar ?]
and [? Mike LaBell ?] and
the students from Yale who
scattered around too.
And with the work of Stan
Kowalski and George Dodson,
we undertook to measure the
interference between the photon
exchange and the z exchange
and the elastic scattering
of carbon-12.
We measured the asymmetry.
Our left polarization
line is right polarization
of the electrons.
The nuclear form
factor drops out
and one gets this
interference term directly.
The polarized source,
once again funded by DOE.
Construction started and
carried almost to completion
at Yale then brought
to Bates and installed.
Here is a picture of it.
The experiment very simple.
There is the entire laboratory.
There is the injector, there is
the accelerator, the beamlines,
detector systems, all
requiring careful control
on the systematics.
Because the effect
is very small.
The order of fractional
parts per million.
Here's the statistics
and the data.
That's the right
minus left asymmetry.
That's a Gaussian over that
number of orders of magnitude.
One is confident
in the statistics.
Systematic errors.
These are the final errors.
These are in parts per million.
And there was a correction
which at one stage
was a source of
considerable despair,
but which finally understood
and it was that big.
Yielding a final result.
Final experimental result.
0.6 plus or minus 0.14
statistics plus or minus
0.02 parts per million.
Which yields this
factor gamma twiddle.
Experimentally it's this.
In terms of the standard model,
it's directly proportional.
It's sine squared theta is w.
And this is the number given
the best available value
of sine squared theta.
And they're
certainly consistent,
but not a good measure now
of that electroweak factor.
How much time?
Zero.
Zero.
OK, well, let me not be tempted
to take a few minutes just
to talk about another program.
I think the point I wanted to
make has been clearly made.
Not particularly
in the specifics
that I would like
to have gone to.
But it has been, I think
it continues to be,
a very exciting program.
We are in the process of
building this south hall
ring which we expect to
finish sometime this year.
Already injection
experiments have
started in putting
electrons along this line.
This porcupine here
is the blast detector.
Which is another one of
these things where there's
large numbers of people
willing to commit
substantial fraction
of their young lives
to make building work.
And to run.
What is the state of
the blast detector?
Well, the PAC there were a
number of experimental programs
approved time assigned, even
though the detector's not
built. I forget whether that's
three or five thousands hours
of beam time that's
been approved.
Technical panels
have reviewed it
and they think
it's a good thing.
Can be built and is the
right crew to build it.
DOE's had a scientific
review and the reviewers
think it's a nice project.
We have yet however
to hear about money.
Which brings us back to where
we began about the golden age.
The original proposals we wrote
were sort of five pages long.
These are voluminous and
I quit I'll put there.
Except for one soundbite
which I wrote to Phil Sargent.
When the laboratory
was approved,
it was called a
$5 million mistake
and we'd try to make it
run a few years later
and it wouldn't work.
It was called a joke.
And I think I've given you
considerable evidence that it's
really a miracle.
Thanks for your attention.
