- Good morning.
- Morning.
- Morning.
- Before I start, I wanna thank the vice president
of research, Maria.
She has always supported me.
In particularly in this experiment.
And I also am very happy to see my good friend
Dr. Daw and his family to have come to this
meeting.
What I would like to do today is to describe
with you a little bit about the Alpha Magnetic
Spectrometer on the International Space Station.
To realize the science on the International
Space Station you just have to remember, there
are only two kind of cosmic rays in space.
Neutral cosmic ray, light waves and neutrinos
and these have been studied by many many satellites.
Then there's a charged cosmic ray.
Charged cosmic ray have a mass.
Because they have a mass they are absorbed
by 50 miles of Earth's atmosphere, which is
equal to 10 meters of water.
So to study charge, intrinsic properties of
charged cosmic ray require a detector above
Earth's atmosphere.
To measure their charge and momentum, require
a magnetic spectrometer in space.
So AMS on the Space Station is the only way
to provide long term precision measurement
of charged cosmic rays.
This is a MIT led international collaboration.
The detector were constructed in Europe and
Asia and assembled at the European Organization
for Nuclear Research in Geneva.
And last year, three universities joined us,
Moscow Engineer and Physics Institute, University
of Kiel in Germany, and University of Oulu
inside the Arctic Circle.
The 600 AMS physicists had worked together
on accelerator experiment.
None of us has any experience in space.
So let me show you some example of previous
work in Germany and that is their round density
detecting of the elusive gluons.
And the little detector only weighs a thousand
tons.
What is gluon?
In nature this gravitational force, this carrier
we still do not know.
Electromagnetic force like your cell phone
is transmitted by photons, weak forces the
collapsing of stars, the decay of nucleus
is by z and w.
Nuclear force is covered by gluons.
So this is a somewhat important discovery.
One of the authors, at that time a graduate
student, Joe Paradiso who is here today.
Another experiment was done at the European
Organization for Nuclear Research known as
the Air 3 experiment.
In that experiment we found in the universe
there are only three types of electrons.
Electrons we're familiar with, electrons from
space, 200 times heavier and electrons in
the nucleus, 4000 times heavier.
There are six type of quarks, but more important,
electrons and quarks have no size.
Their radius is less than 10 to the minus
17 centimeter.
If you think about it, you use the electricity
all the time.
You never seem to be able to measure the size
of the electron.
Unfortunately, the results are in excellent
agreement with the theory.
When experiment agree with theory, what you
learn is very limited.
When the experiment confront the theory, you
learn something more.
So this was the experiment.
In the 16 mile circumference lab accelerator,
and this experiment is not for space.
The magnet is 10,000 tons, six stories high
and there are 300 tons of uranium, uranium
detector.
And disposed from Soviet Union.
Was the largest Soviet collaboration outside.
So with this background, so when we started
experiment, we got this cartoon.
That was my qualifications.
So, before I mentioned, there are many, before
us, there are many pioneer MIT space program.
One was led by our vice president for research
GRAIL, and then Voyager, Challenger and many
many experiments.
AMS is a space version of a precision detector
used in accelerators.
So on top, there's a transition radiation
detector, eight layers of silicon tracker,
electromagnetic calorimeter, two banks of
time of flight counter, a magnet, a ring image
and turn cup counter.
In total, there are 300,000 kind of electronics,
650 fast microprocessors.
It's not too big, it's five meter by four
meter by three meter.
Not too heavy, seven and a half tons.
So the signature of different particles in
nuclear as the pass through AMS the electron
will leave this place, proton will leave for
different place, ion, different different
place.
Cosmic rays are defined by their energy.
In Giga-electron-volts momentum charge.
Charge is the location on the periodic table.
For helium, charge equal to two.
And the new term called rigidity meaning momentum
per unit charge.
Before it was sent to space, the detector
was extensively calibrated at the 27 kilometer
lab LHC accelerator and there you can see
or measure data.
And all simulation agrees to five orders of
magnitude.
Meaning, we understand the detector.
This is very important because once you send
the experiment to space, you can no longer
send a graduate student to repair it.
Half way through the detector construction
NASA decided to get rid of us.
And so this was a New York Times article.
The long awaited cosmic ray detector may be
shelved.
But many people have different opinions, George
Smoot, Barry Barish and others that thought
this is wrong.
And also in the Washington Post Steve Weinberg
also said this is not correct.
And I received many visits.
One of the ones that gave me the deepest impression
was Steve Hawking, and he came with 11 nurses.
And finally, the Congress, the House and Senate
2008 passed a law to add additional flight
to deliver Alpha Magnetic Spectrometer to
the International Space Station.
After that, many people continue visit us.
I remember him, spent the whole afternoon
with us.
And tried to understand the new technologies
we develop for space.
And after that, I decided to be more friendly
to NASA.
And so this is my support of the shuttle commander
Mark Kelly, who is now running for to be a
senator.
I hope he succeed, he's an awfully nice person.
That's me.
And so it was launched into space on May 16th,
2011.
And there are MIT alumni, Michael Fink and
Greg Chamitoff, Dr. Daw remember certainly
him.
So in eight years over 135 billion cosmic
ray has been measured by AMS.
So let me show you some of the latest results.
First is the origin of cosmic positrons.
There are three sources of positrons.
You have explosion of stars produce protons
of helium.
When they travel through space, interact with
other protons in helium produce positrons
from collisions.
If you have dark matter and they collide,
they produce positrons.
And you have a new astrophysics sources unknown
ones such as pulsar will produce positrons.
So there are three sources.
Because the great interest of positrons and
the electrons, before AMS there were many
many measurement.
This is the electron spectrum this is the
positron spectrum.
Looking at this spectrum you notice the data
are not exactly agree with each other, has
very large errors.
When the data has large errors it's very good
for theoretical physicists, because you can
make many theories.
Most physicists assume that the flux is due
to a constant times the energy to the gammas
power, gamma is now a spectral index.
So this is called the power law energy dependence.
Or measurement brings on 1.9 million positrons
and this is our measurement.
And this is, everybody believe positrons come
from collision.
And this explain the low energy part, what
happened to this.
Cannot be explained by existing theory.
And so, we finally found out, the positron
spectrum, it's a sign of low energy part from
collision cosmic rays, another is a new source,
a new astrophysics source or from dark matter.
The most important thing is when you fit this
to any formula you have a cut off energy.
One exponential, one over yes.
Meaning, after certain energy, you're no longer
going to see positrons.
And that is a very peculiar fact.
So at low energy the data come from collision
of cosmic rays, at high energy it's from a
new source or from dark matter, but it has
energy cut off.
Indeed, now we sit there for days and we don't
see anymore positrons at high energies.
Another way of theorizing which I forgot to
report to Maria last time, and that is antiprotons
and positrons have exactly similar behavior.
Antiprotons are very rare objects in space
and it goes out and tends to be flat.
For the electrons, this is based on 28 million
events, spectrum goes up, goes down.
If you analyze more carefully, you will see
we come from two power laws.
One called power law A, one called power law
B. What does this mean?
It means low energy becomes a version of cosmic
collision, this is the grim part, cannot explain
the measure data.
And this is different from positrons.
A positron you remember, a low energy positron
come from collision, but for the electron
it cannot.
Can only be described by a power law.
At high energies the electron do not have
a source term nor cut off, where positron
has both.
Therefore the electrons and positrons are
totally different.
Electron you can continue measure the high
energy, positron, after certain energy it
disappears.
Now let me share some results with you on
cosmic nuclear.
There are two types of cosmic rays, one is
called primary cosmic ray, proton, helium,
carbon, oxygen and so forth.
They are produced during the lifetime of stars
and then accelerated by the explosion of stars.
Another type is called secondary cosmic ray,
lithium, beryllium, boron.
They are produced by the collision of primary
cosmic ray with interstellar meteor.
So there are two kinds.
Now what is the difference between these two?
First let me talk about protons.
This is a measured proton data for many many
experiment before AMS, and the data again
do not agree with each other, has very large
errors.
So traditionally physicists assume the flux
is still constant times energy to the gammas
power.
This is all measurement protons, the red point.
Based on 300 million protons.
At low energies, it does agree with traditional
assumption, traditional theory, but above
this energy, you have unexpected increase.
Meaning the theory is no longer correct.
But the proton flux cannot be described by
a single power law.
Before AMS there were many results on primary
cosmic rays, helium, carbon, oxygen.
From balloons and satellite experiment.
If we group them together you have a random
pattern and you do not know what is going
on.
Mainly because the error is so large.
This is our measurement above 60 Tb. 60 Tb
the primary cosmic rays have identical rigidity
dependence for helium, for carbon, for oxygen.
And you have one energy dependence, another
energy dependence that deviate exactly at
this point.
This is very strange.
Cosmic rays are totally different things,
but their energy dependence are exactly the
same.
Then there are secondary cosmic rays, lithium,
beryllium, boron, also have identical rigidity
dependent.
This lithium, beryllium, boron.
And they are different from primary cosmic
rays.
Therefore, in space all the cosmic rays across
the periodic table have only two classes.
And think about such a think could happen.
And so let me mention what we're gonna do
on the Space Station until 2024, that's the
lifetime, projected lifetime of Space Station.
One is complex antimatter, like antihelium,
anticarbon, antioxygen, and then try to pin
down the origin of positrons, the electrons,
the antiprotons, precision study of solar
physics and continued study of heavy nuclear.
Lemme share with you some thoughts about complex
antimatter.
The Big Bang origin of the universe require
matter and antimatter to be equally abundant
at the very hot beginning, because before
the Big Bang, it's vacuum, nothing exists.
So at the beginning it must be equal matter,
antimatter.
This experiment is orders of magnitude more
sensitive than previous experiments to look
for antimatter from balloons and satellites.
This is an antimatter candidate.
This is measured the track and depending plan
and the non-depending plan, looking from the
top measure the velocity.
This signal is charge minus two.
The mass is exactly the same as helium.
Helium, of course, charge is plus two.
So you just begin to say antimatter such as
in cannot be produced from cosmic ray collision.
The raid in AMS for antihelium candidate is
less than one in 100 million helium.
At this extremely low rate, more data is required
to further check the original of this event.
One in 100 million is a very very small number.
You absolutely must make sure it's correct.
And anyway, nobody's foolish enough to put
another magnetic spectrometer in space for
the next 20 to 30 years.
So we have time to check this.
And the next question is what's the origin
of positrons, electrons and antiproton?
Today, we know at high energies the positrons
has energy cut off, but we do not know, is
this from a new source or from dark matter?
A new source, and dark matter, I will explain.
The question is what is a new source?
Why do positrons vanish at high energy?
The red point are the data we have now and
the green one will be we continue to take
data to 2024, what is most important is to
go to very high energy data.
A new source could be pulsars.
Pulsars emits light and light interact with
the pulsar magnetic field produce positrons
to higher energy.
And it's continuous without energy cut off.
A light ray do not produce antiprotons.
Antiprotons cannot come from pulsars.
So this is the projected antiproton spectrum,
this is what we measured and extended to 2024,
compare with the positrons to 2024.
Such a spectrum cannot come from pulsars because
pulsars do not produce antiprotons.
Because a photon doesn't produce protons or
antiprotons.
Then what is dark matter?
Remember your high energy, high school physics?
You have a galaxy and you have a region of
observable mass and then you have an addition
R. You have a star rotating in a close orbit.
A close orbit means the force on the star
is zero.
That means gravitational force and centrifugal
force must be balanced and therefore you can
calculate the velocity of this star must equal
to M of R, the total mass inside divide by
R. And so this curve would be from gravitation.
Assuming all the mass you can see.
And this is the measured curve of a galaxy.
That means there's a large original mass you
cannot see.
So the existence of dark matter is not in
doubt.
What is dark matter?
Collision of dark matter produced positrons,
antiprotons.
Dark matter particle has a mass M and they
move slowly, therefore collision of two particle
produce a total energy of 2M.
So dark matter collision produce antiprotons
and positrons.
Conservation of energy momentum require positron,
antiproton energy must be smaller than M,
and therefore there's a sharp drop off at
the mass of M. That's a unique signature for
dark matter.
So this is the red point is our measurement
and this is a dark matter model.
You see a sharp drop off, but the error is
still very large.
Even though it's a good fit, you cannot say
you have seen dark matter.
You need to see this point in order to make
sure the drop off.
And this is why it's so important to go to
this point.
And the next question, why are electrons so
different from positrons?
We do not know.
All we can do is continue collect data to
higher higher energy to see whether there
are any trace of similarity.
Next item is study of solar physics over the
entire solar cycle of more than 11 years.
High energy cosmic ray goes through the solar
sphere and pass through quickly.
Low energy cosmic ray are trapped in solar
magnetic field so spin for a long time.
This is some very new data of, we observe
identical monthly time variation of protons
and helium flux.
And this is from May 2011 to May 2017.
You notice where the absolute value is different,
the change is exactly the same.
And the question is what happened over the
11 years?
In addition, a new surprise is not only monthly,
but daily, the flux goes up and down for proton
and the helium is exactly the same way.
This is a phenomenon nobody predict and nobody
can provide an explanation.
Not only that, with the proton and carbon
varies the same way and proton oxygen varies
the same way.
The observation of carbon oxygen there with
deliberation, it's a new phenomenon.
And then also we see structures in positrons
and electrons.
And this again from 2011 to 2017, and this
is the period where the solar magnetic field
flips.
And you notice before the field flip, after
the field flip, the spectrum are very different,
but the spectrum varies the same way.
And the question is after the 11 years, does
it come back?
Next item, heavy nuclear.
I've analyzed the first eight elements, now
we're in the progress to analyze all of them.
So let me share with you some very basic physics
of heavy nuclear.
Namely, properties of primary cosmic rays.
Light element, helium, carbon ion are produced
during the lifetime of the stars and then
accelerated by the explosion of stars.
Heavy element, nickel and zinc are produced
during the explosion of stars.
So they come from different origin.
The question is do they have different properties?
So I shared with you helium, carbon, oxygen
and lithium, beryllium, boron.
A few days ago, we finished the analysis of
a silicon and found they belong to this class.
So the fundamental question is in the universe,
does all the cosmic ray, all the elements,
only have two classes or not?
Very strange phenomena.
Another interesting thing is up to element
number eight, they deviate from a single power
law at exactly 200 GV.
Why?
Nobody knows.
But a question you can ask, does this continue
to heavy nuclear?
And so this is a letter from the American
Physical Society, they added a physical review
letters and says one of the papers they decide
to particular to for citation and mention
the other paper we ought to commemorate in
this way, including the discovery of element
197, in observation of gravitational wave.
So in the eyes of physicists we're making
a small contribution.
None of the experiment can be explained by
the theory.
And so in the American Physical Society Meeting
2017, Igor Moskalenko, a professor at Stanford
showed this graph.
Current state of theory and light meter.
This is a very famous Russian printing.
And so this is a theorist confronted with
new data and do not know what to do.
And so let me share with you another adventure
that's coming up.
And that's we are going to install a new cooling
system on the Space Station October 19th this
year.
With the satellite.
This, putting a new cooling system on the
Space Station is not exactly easy.
This slide come from NASA, and this is a AMS,
EVA crew training.
We require five two person EVA for AMS, they
are considered to be more difficult than those
completed on the Hubble Telescope.
This the repair of the Hubble Telescope, everybody
know.
The reason the Hubble Telescope was designed
to be serviced inside and out.
AMS is so complex there are very few interfaces
that are EVA compatible.
So we have a total 25 swimming pool training
for the astronauts.
And this is Chris Cassidy, one of the astronauts
from MIT and this is Kim Ballwick, really
a great engineer from NASA.
So in eight years on the Space Station we
have recorded more than 135 billion cosmic
rays.
The accuracy and characteristic of the data
simultaneously from different types of cosmic
ray required development of new comprehensive
model of the universe.
The current theory has many parameters.
You can always adjust the parameter, agree
with one measurement, but the same parameter
cannot explain the rest.
That is the little problem we have.
Most importantly, we will continue to collect
data, collect, analyze data for the lifetime
of Space Station.
Because whenever a precision instrument such
as AMS is used to explore unknown, new and
exciting discoveries can be made.
So thank you.
Dr. Paradiso, there's a video.
You want to?
- So do you want to see the video or a clip?
- It's up to you Sam.
You're welcome to take--
- The video takes three minutes and seven
seconds.
- Let's do that.
- People really didn't work this hard.
You require a C5 to send to, from Geneva to
Kennedy Space Center.
And this is the test in Kennedy Space Center
make sure it fits into the Space Station.
- Endeavor Houston on the big loop, we're
following you in docking mech powerup and
you have a go for docking.
- Endeavor copies on the big loop, go for
docking.
- I still don't know how they did this.
- Houston and station capture is confirmed.
- Incoming.
- Hello!
D-man!
- Welcome!
Welcome aboard the station.
- Hey you guys wore coordinating shirts.
We didn't do that.
- That's alright.
- Okay.
- Look Captain Mark Kelly.
- Yeah, nice to see you again.
- Nice to see you.
- Welcome!
- Cool I can see you!
Buddy, how you doing?
- Woo hoo!
Taz, how are you?
Oh my goodness you look-- Is this guy bothering
you?
- All right Taz, look at you in the video.
- Look at Mike, Mike's--
- Oh yeah Taz, woo hoo!
- Woo hoo!
- Okay.
- Sam's gonna be around, I hope during the
break.
I think that we gotta go on with the next
panel 'cause we have very little time.
If anybody has some questions, you can catch
up with Sam during the break.
- Okay.
Thank you.
