1. Member States
HST2000

2. The Creation of Particle Beams
Paul Eaton -- United States
Katarzyna Werel -- Poland
HST 2000
CERN, Switzerland/France
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3. Example of a Particle Hitting a Nucleus
Scientists learn about the fundamental components of nature
Best results occur between beams that consist of one pure type of particle
By knowing what type of particles are interacting & what particles and energies are produced, conclusions are made
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4. Pipe containing a Beam
Pipes maintain a vacuum so that a particle beam can travel great distances
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5. Target Area
Particle beams are directed into various target materials to induce interactions
Beam interactions with the atoms of the target can cause “cascades” of new types of particles
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6. Particle Beam interacting w/ Hydrogen [H2]
Scenes from the inside of a Bubble Chamber
Charged particles leave a trail of bubbles after they pass through, similar to the trails left by jet airplanes
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7. Particle Beam interacting w/ Hydrogen [H2]
When particles come close enough to the nucleus of a target atom to interact, a variety of events could occur:
1. New particles could be formed.
2. Components of the original nucleus and particle could be scattered
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8. Generalized interaction pattern
The high energy particle penetrates the medium before a chance inter-action with the target medium
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9. Generalized interaction pattern: electromagnetic cascade
mass converted to energy and two photons (gamma) are produced  e
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10. Generalized interaction pattern: electromagnetic cascade
photon passes in proximity to another atom in the medium, producing an electron (e-) / positron (e+) pair e+  e- e  e+
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11. Generalized interaction pattern: electromagnetic cascade e- e+  e- e+
this process repeats itself in a “cascading” fashion until there is not enough energy in the particles to continue e+  e- e+  e- e+   e- e+ e-  e- e+ e e- e+
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12. Generalized interaction pattern: electromagnetic cascade e- e+  e- e+
this process repeats itself in a “cascading” fashion until there is not enough energy in the particles to continue  e- e+  e- e+  e- e+  e- e+  e- e+
*Notice: Only positrons, electrons, and photons are formed
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13. Generalized interaction pattern: Hadronic Cascade
The high energy particle penetrates the medium and fractures the atomic nucleus of the target medium K+ p n + - -
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14. Generalized interaction pattern: Hadronic Cascade
The high energy particle penetrates the medium and fractures the atomic nucleus of the target medium K+ p n + - -
*Note: a large variety of particles could be produced, e.g., p, n, , , , , 
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15. Generalized interaction pattern: Hadronic Cascade- +  e  - +  e 
The particles that have been produced may also contain high enough energy to either fracture another nucleus or further degrade itself K+ K+ p n K- - +  e   - +  e 
*Note: a large variety of particles could be produced, e.g., p, n, , , , , 
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16.  Interaction Length Of a Hadronic Cascade
The average distance a charged particle travels in a target medium before initiating a Hadronic Cascade - +  e   + e -
 K+ - K+  p n K- - +  e  + e - - 
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17.  Radiation Length Which results in an electromagnetic cascade
The average distance a high energy particle penetrates a medium before initiating an electromagnetic cascade e+  e- e+
  e+  e- e+ e-  e- e+  e-  e- e+ e+ e e+ e-   e- e- e+ e e- e- e+ e+
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18. Radiation vs Interaction Length in Lead [Pb]
The radiation length in lead is only 0.56 cm long  e- e+     - K+ e - K+ + p n K-  - - +  e  e  - +  e  e +
The interaction length is 17.1 cm 
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19. Lead Target 0.4 cm in length
High energy electrons and positrons will be produced  e- e+  e- e+  e- e+ p
Virtually no hadrons will be produced
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20. Radiation vs Interaction Length in Copper [Cu] e- e+
The radiation length is 1.5 cm   +  e - K+ - - e - K+ +  p n K-  e - +  e  + e - - 
The hadronic length is 15.0 cm
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21. Length in Copper [Cu] target 40 cm e- e+
Electromagnetic cascade occurs totally inside the copper target    K+ - e - e - K+ + + p n K-   e - +  e  + - - 
The hadronic cascade begins within the target but critical energy is not reached and low level hadrons leave the target
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22. Lead Target 0.4 cm in length
High energy electrons and positrons will be produced  e- e+  e- e+  e- e+ p
Virtually no hadrons will be produced
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23. Path of Electrons/Positrons
Most of the electrons and positrons exiting the target will be clumped together following the path of the original high energy particle  e- e+  e- e+  e- e+
= electrons
= positrons
HST2000

24. Path of Electrons/Positrons
some of the trajectories of the particles will cause them to be lost
Most of the electrons and positrons exiting the target will be clumped together following the path of the original high energy particle  e- e+  e- e+  e- e+
= electrons
= positrons
HST2000

25. Main beam is directed into a magnetic field
= electrons
= positrons  e- e+  e- e+  e- e+
A magnetic field, where the field direction () is pointing into the page
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26. Path of Electrons/Positrons e- e+  e- e+  e- e+
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