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Probing the Forces Probing the Forces between Quarks with between Quarks with

Photon BeamsPhoton BeamsRyan RousselRyan Roussel

Nuclear PhysicsNuclear Physics

Mentor: Dr. Richard JonesMentor: Dr. Richard Jones

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Why do we want to study quarks?

Quarks make up 99% of all matter and little is known about how they are assembled into the neutrons and the protons which make up all matter.

The question is, how does the nucleus stay together when all the positively charged protons are repelling each other? The Strong Force binds these

particles together, in a way that is not completely understood yet.

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The Particles of the The Particles of the Standard ModelStandard Model

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QuarksQuarks

Up,Charm,TopUp,Charm,Top 2/3 positive charge2/3 positive charge

Down,Strange,BottomDown,Strange,Bottom 1/3 negative charge1/3 negative charge

Quarks have Quarks have color charge.color charge. Quarks in groups of three are called Quarks in groups of three are called

baryons and a quark/anti-quark pair baryons and a quark/anti-quark pair is called a meson.is called a meson.

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Anti-MatterAnti-Matter

All particles have an anti-particle with All particles have an anti-particle with equal mass but equal mass but opposite chargeopposite charge..

When anti-matter particles and When anti-matter particles and particles collide they annihilate and particles collide they annihilate and create pure energy. create pure energy.

The opposite can also happen, out of The opposite can also happen, out of energy aenergy a

pair of particles can pair of particles can

come out.come out.

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Force Carrying ParticlesForce Carrying Particles

The interchanges of these The interchanges of these particles is the cause of particles is the cause of these fundamental forcesthese fundamental forces

Photon(Photon(γγ)- Force carrying )- Force carrying particle for the particle for the electromagnetic force.electromagnetic force.

Weak bosons (WWeak bosons (W++,W,W--,Z)- ,Z)- Force carrying particles Force carrying particles for the weak nuclear forcefor the weak nuclear force

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Graviton(G)- undiscovered Graviton(G)- undiscovered particle theorized to be the particle theorized to be the source of gravity the weakest source of gravity the weakest force by far.force by far.

Gluon(g)- particle responsible Gluon(g)- particle responsible for the strong force, for the strong force, responsible for keeping the responsible for keeping the quarks in hadrons togetherquarks in hadrons together

Force Carrying Force Carrying Particles(Cont.)Particles(Cont.)

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Strong Force and the Gluon

The Strong force is the attraction between quarks in the nucleon when they exchange gluons.

This force overwhelms the residual electromagnetic repulsion from like charged quarks. It forms a strong attraction between quarks, keeping them together.

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Color Charge The unique feature of the strong force

is the existence of color charge. All quarks have color charge, anti-

quarks have anti-color charge and gluons have a combination of both giving 8 different colored gluons.

Quarks exchange gluons madly, thus a color force field forms.

When quarks move away from each other a concentrated stream of exchanged gluons forms, until another quark/anti-quark pair forms.

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The GlueX ExperimentOne of the main mysteries of the

subatomic world is the properties of the gluon and how it holds the quarks together in the nucleus. Probing deep into this question is the GlueX experiment at the Thomas Jefferson National Accelerator Facility in Newport News, Virginia.

This facility has the ability to excite the gluon bond between the two quarks in a meson(one quark and one anti-quark). Using a concentrated beam of photons the scientists in collaboration together are able to study the bond between quarks.

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Reaction Inside Detector

Photon

Hydrogen Atoms

Recoil Proton Debris

Meson

Meson Decay

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Diamond Wafer Photon Production

To produce the photons needed for the experiment an electron beam is fired at a diamond wafer. The atoms in the diamond get energized and release a photon packet, many atoms do this at the same time producing a photon beam. The electrons are then directed away using a magnet.

The diamond is supported by tungsten wires.

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Diamond Configuration with Tungsten Wires

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Problem Facing Photon Creation

One of the problems that occurs during photon creation is the oscillation of the diamond wafer. The diamond is supported by the tension in the tungsten wires. The diamond wafer and string system oscillates due to outside equipment. The main purpose for using the Jefferson Lab is the precision beam of photons that the facility has. If the object that is creating the beams oscillates the accelerator loses it’s precision.

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Proposed Solution to the Problem

Increasing the frequency will lower the amplitude and lessen the deflection.

Photons

Diamond

Normal (No oscillation)

Low Frequency

High Amplitude

High Frequency

Low Amplitude

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SourcesTo read more…

Particleadventure.org symmetrymagazine.org itp.uzh.ch

Picture Sources http://www.lns.cornell.edu/~nbm/

NBM_INTRO_TO_HEP1.htm http://www.ipod.org.uk/reality/

reality_electromagnetic.gif startswithabang.com/?p=1795 http://opticsclub.engineering.ucdavis.edu/home_files/

laser.jpg http://www.nsf.gov/discoveries/disc_images.jsp?

cntn_id=111420&org=NSF

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Questions?