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Do you know what’s
next door?
Do you know what’s
next door?
Did you know that next door to you is
the world’s most powerful particle
accelerator?
Do you know what’s
next door?
Did you know that next door to you is
the world’s most powerful particle
accelerator?
Did you know that next door to you
two of the building blocks of the
entire universe were discovered?
Introductory Comments: Elementary Particles
The world we live in is exceedingly complicated. A scientist, trying to
understand how the world works, notes the almost infinite variety of
things: air, water, earth, rock, hard metals, mist, clouds and so on.
The earliest scientists proposed a strategy for understanding
everything. In 480 B.C. the Greek philosopher Democritus proposed
that all things were made of "atoms." These "atoms" were too small
to see but in their ceaseless motions they could collide and
accumulate. Democritus' ideas were, of course, primitive but
essentially correct.
Today, we know that all matter is made of atoms, and that atoms are
complex structures made of smaller and more elementary objects. To
understand the most fundamental particles and the forces that cause
them to cluster and interact to build up the things we can see and
touch is, then, the "first science." All other sciences - materials
science, chemistry, biology - ultimately must rest on the basic laws of
nature that govern the behavior of the elementary particles.
I.
Introduction to Fermilab
Bower
School
Bower School
Wlison Hall (a.k.a. “High Rise”)
Robert Wilson:
Founder of Fermilab
Leon Lederman:
• 2nd director of Fermilab
•received Nobel Prize in physics
•heck-of-a nice guy, not to mention
•heck-of-a smart guy
John Peoples
Fermilab’s 3rd Director
Mike Witheral
Present Fermlab Director
So what is this good for?
1. Each bit of progress was preceded by the
knowledge of how it worked
2. The tools required to make such measurements
have led to technical offshoots which we use
everyday. Examples are:
i. x-ray machines
ii. Microwave ovens
iii. televisions
II. The Standard Model
Of what is everything in
the universe made?
The Building Blocks of a Dew Drop
A dew drop is made up of many molecules
of water (1021 or a billion trillion). Each
molecule is made of an oxygen atom and
two hydrogen atoms (H2O). At the start of
the 20th century, atoms were the smallest
known building blocks of matter.
Each atom consists of a nucleus
surrounded by electrons. Electrons are
leptons that are bound to the nucleus by
photons, which are bosons. The nucleus of
a hydrogen atom is just a single proton.
Protons consist of three quarks. In the
proton, gluons hold the quarks together
just as photons hold the electron to the
nucleus in the atom
We know that we can categorize atoms
Atoms
All things in nature are made up of atoms. Atoms are made up
of a central nucleus and electrons which orbit around the nucleus.
The nucleus is made up of protons and neutrons, and is only
1/10,000, or 10-5, the size of the atom. That’s like putting a pea on
the 50 yard line of a football field; the pea is the nucleus and the
field is the size of the atom.
Electrons
Nucleus: protons and neutrons
Remember that the atom is made up of other stuff!
Protons and Neutrons
Protons and neutrons are made up
of quarks. Two up
quarks and a down quark make a
proton. (Two down quarks
and an up quark make a neutron.)
Within the proton, the
quarks and gluons are
constantly moving and
making new particles.
In the end, many particles make
Up protons and neutrons.
Quarks, Leptons, and Bosons
Physicists currently believe there are
three types of basic building blocks of
matter: quarks, leptons, and bosons.
Quarks and leptons make up everyday
matter, which is held together by
bosons. Each boson is associated with a
force. The photon, or light particle, is
the unit of the electromagnetic force
which holds the electron to the nucleus
in the atom. The gluon, holds quarks
together in the nucleus of the atom.
The way these particles combine
dictates the structure of matter.
Antimatter
For every quark and lepton,
physicists have discovered a
corresponding antiparticle.
These particles are referred to
as antimatter. Antimatter was
first observed in decays of
radioactive nuclei.
Antiprotons are composed of
two anti-up quarks and one
anti-down quark. Antihydrogen (an antiproton and a
positron) was created at the
European laboratory, CERN,
and at Fermilab in 1996.
The Particle Zoo
All of these quarks can combine together to
make particles which we can see in our detectors.
We know of two ways that quarks can combine:
III. Introduction to Particle
Accelerators
To see different sized objects we need different tools:
A Basic Accelerator
The Fermilab accelerator has two basic parts: the magnets and the
RF cavities. The magnets keep charged particles moving in a circular
path. The RF cavities pump energy into the particles each time they
pass through the cavities. Particles complete many laps around the
accelerator ring and receive a small boost in energy with every lap.
Most accelerators
have stages of
acceleration.
Show Full Acceleration
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PROTON
SOURCE
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LINAC
Click Anywhere to Begin...
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PROTON
SOURCE
LINAC
Repeat
LINAC
BOOSTER
MAIN
INJECTOR
TEVATRON
Cockroft-Walton
LINAC
LINAC Drift Tubes
Fixed Target Experiments
LINAC
Tevatron
Booster
Anti-proton Source
Main Injector Tunnel
Main Injector
High Rise
CDF
Tevatron
p
p
DZero
Tevatron Tunnel
Tevatron Tunnel with FPD Detectors
Main Control Room
IV. Detecting Particles
How we see:
Source
Sun
detector
probe
Scattered
probe
Converted
Signals
target
Processor
How we “see” with experiments:
detector
Source
probe
u
u
d
Scattered
probe
Converted
Signals
target
Processor
DZero Detector
CDF Detector
V. Inferring physics from
the detectors
Matter and Energy
Everyone has heard of Einstein’s famous formula:
E=mc2
Here, E is “energy”, m is “mass”, and c is the constant for
the speed of light. What this equation tells us is that we
can change energy into matter, and matter into energy.
Examples:
• Burning a match
• Photosynthesis
• A demolition derby
In a particle accelerator, like the Tevatron, we can create
new matter in collisions of protons and anti-protons
Here’s how we do “physics”:
–We know what quarks exist to make up particles (baryons and
mesons) that we can see in our detector.
–We know that we can use a particle accelerator to make heavy
particles through the mass-energy relationship E=mc2.
–We know that heavy particles can decay into lighter particles.
–We know the properties of many of these lighter particles.
–If we can measure (detect) the lighter particles, we can “infer” that
they came from the heavier particles, and thus from heavier quarks.
Example: my doctoral thesis experiment
To study the “b quark” , we detected “B-mesons”
Example: my doctoral thesis experiment
“B-meson” particle
A particle we
understand
p + Si
probe
target
Source
B+X
J/y + X
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m +m
Sun
detector
probe
Scattered
probe
Converted
Signals
target
Processor
What we
can detect
Example: my doctoral thesis experiment
mm+
target
p + Si
probe
B+X
J/y + X
m+ + m-
Show Full
Event--Normal Speed
Show Close-up--Normal Speed
Show Close-up--Slow Motion
Show Close-up--With Tracings
CONTINUE
Show Full Event--Normal
PRESENTATION
Speed
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PROTON
SOURCE
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Click Anywhere to Begin...
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PROTON
SOURCE
LINAC
Show Full Event--Normal Speed
LINAC
BOOSTER
MAIN
INJECTOR
TEVATRON
Magnetic Field
Target
Menu
Steel Plates
Magnetic Field
Target
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Steel Plates
Target
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Target
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PROBE
B-MESON
mJ/Y
m+
TARGET
p + Si
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B+X
J/y + X
m+ + m-
Steel Plates
Magnetic Field
Target
m-
m+
Menu
VI. Other things at Fermilab
Astrophysics
Fermilab also has a
place where people
with certain types of
cancer can be
treated.