Nuclear Physics

UConn Mentor ConnectionMariel Tader

UConn Mentor Connection 2010, Mari Tader

2

The Standard Model

Describes three of the four “fundamental” forces

• Electromagnetism, weak and strong interactions

• There are 12 different kinds of elementary particles

UConn Mentor Connection 2010, Mari Tader

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The Forces

• Electromagnetism: why opposites attract• Biology/ Chemistry

• Strong Force: holds quarks together• Weak Force: mediates fundamental

particle decay• (Gravity): not included in Standard

Model

UConn Mentor Connection 2010, Mari Tader

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Electroweak Theory

• Electromagnetism and weak force are two different aspects of the same force: electroweak

• The two merge into the same force at high energies and close distance

UConn Mentor Connection 2010, Mari Tader

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The particles

• 6 Quarks: make up protons, neutrons, etc.

• 6 Leptons: electrons,neutrinos, etc.

• Force carriers: gluons for strong

force, etc.• Weak force’s range

• The three generations

UConn Mentor Connection 2010, Mari Tader

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Antimatter

• Each type of particle has a comparable anti-particle

• The same properties, except charge• The mystery: why so much more

matter?• Annihilation: matter and antimatter

collide a Z boson/gluon/photon form decay into new

matter/ antimatter pair

UConn Mentor Connection 2010, Mari Tader

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The Nucleus

• Quarks: come in threes (protons/ neutrons/ etc.) or twos (mesons)

• Gluons: hold quarks together, force carrier particle for strong force

UConn Mentor Connection 2010, Mari Tader

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Quantum Numbers

• Electric Charge: all particles except quarks have integer charge, quark charges add to whole numbers

• Flavor: different kinds of quarks/ leptons• Spin: goes by 1/2s, particles/ nuclei• Lepton/baryon numbers, etc.• Color Charge: gets its own slide• Angular momentum/ momentum: location• Weak Charge: strength of weak force

UConn Mentor Connection 2010, Mari Tader

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Color Charge

• Why quarks come in threes or twos: neutral charge

• Why quarks stay together: color force field

• Quark: 1 of 3 colors• Anti-quark: 1 of 3 anti-colors• Gluon color charges: 1 color and 1

anti-color combination

UConn Mentor Connection 2010, Mari Tader

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Bosons and Fermions

• Pauli Exclusion Principle: “two particles can’t have identical sets

of quantum numbers”• Fermions: obey Pauli• Bosons: violate Pauli

UConn Mentor Connection 2010, Mari Tader

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Radiation

• Unstable nuclei decay• Alpha: release of 2 protons/2

neutrons (helium nucleus)• Beta: release of an electron• Gamma: release of photons (as

gamma rays)• Neutron radiation: like it sounds

UConn Mentor Connection 2010, Mari Tader

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Fundamental Particle Decay• Unlike atoms, fundamentals can

not break into constituents• To become a less massive

particle:1. Emit a force carrier (W boson)

“virtual” 2. W boson immediately decays into

lighter particles

UConn Mentor Connection 2010, Mari Tader

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Virtual Particles

• Can not be detected directly• Can break “conservation of

energy” for a very short time

You can not see virtual particles, but you can see the before and after

UConn Mentor Connection 2010, Mari Tader

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The Project

• Thomas Jefferson National Accelerator

• The collaboration• Will be the first to observe and

study exotic mesons• Will begin 2014

UConn Mentor Connection 2010, Mari Tader

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gluex

• GlueX hopes to learn about quarks, gluons, and confinement by creating exotic mesons

• How we “see” the gluons:Polarized beam liquid hydrogen target exotic mesons final particles and radiation data deciphered

UConn Mentor Connection 2010, Mari Tader

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Bremsstrahlung

• German for “braking radiation”• A radiation particle interacts with

atoms and creates more radiation, while

losing the corresponding energy

Atom

UConn Mentor Connection 2010, Mari Tader

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Coherent Bremsstrahlung

• Must be in a crystal• Particle/crystal must be in

correct alignment• A few specific wavelengths are

prevalent, “peaks”

UConn Mentor Connection 2010, Mari Tader

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Reciprocal Lattice Vectors

• Bravais Lattice: repeating crystalline arrangements of points

• Reciprocal Lattice: made from the vectors perpendicular to three of the vectors of the original• Used as a simple geometric model that

can interpret diffraction in crystals

UConn Mentor Connection 2010, Mari Tader

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Framing the Crystal

• A frame would produce too much unwanted bremms.

diamond is mounted on tiny carbon fibers• The resonant frequency of the fibers should be known, to minimize rotation

UConn Mentor Connection 2010, Mari Tader

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Vibration

• Interference: two or more superimposed waves create a new wave pattern: need coherent bremss.

• Resonant frequency: An objects natural frequency of vibration

• Gluonic flux tube vibration is like a string

UConn Mentor Connection 2010, Mari Tader

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The Carbon Wire

• The theoretical model vs. the experimental data

• How we modeled it• The glue ball equation

• How we measured it• Uncertainty bars

Amplitude vs Frequency

0.E+00

1.E-05

2.E-05

3.E-05

4.E-05

5.E-05

6.E-05

7.E-05

8.E-05

61.8 61.9 62 62.1 62.2 62.3 62.4 62.5

frequency (Hz)

Am

plitu

de (m

)

UConn Mentor Connection 2010, Mari Tader

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Polarization• The orientation of the wave’s electric/

magnetic fields • Transverse wave: polarization is

perpendicular to wave’s direction• Linear Polarization: the electric or magnetic field is oriented in one direction, i.e. no rotation (chirality)

UConn Mentor Connection 2010, Mari Tader

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Putting it all together• The process: Electron beam diamond

wafer polarized photons hit mesons detectors