Photo of Particles Interacting within a Bubble Chamber

1. Photo of Particles Interacting within a Bubble Chamber How does a bubble chamber work ? How can you analyze this image ? Fermilab bubble chamber: 4.6 m in diameter in a 3 T magnetic field

2. How does a bubble chamber function ?

3. How can you analyze the image ? Relate the movement of the Compton Electrons with the direction of the magnetic field Relate the movement of the deflected particles with their charge and the direction of the magnetic field Relate the materialization of particle pairs (matter & antimatter) to the energy of the photon which preceded them Apply the Conservation of Momentum to a head-on collision between a positron and an electron

4. Relate the movement of the Compton Electrons with the direction of the magnetic field. Notice the trajectory of the spiraling lone electron, indicated by the arrow. This electron was knocked away from the atom that originally held it by a high energy photon. Identify the other examples of this interaction in the picture above What is the direction of the magnetic field? Why isn’t the photon visible ?

5. Relate the movement of the deflected particles with their charge and the direction of the magnetic field. Notice the trajectory of the spiraling lone electron, indicated by the arrow. This electron was knocked away from the atom that originally held it by a high energy photon.

6. y x z What is the relationship between the movement of the deflected particles with their charge and the direction of the applied magnetic field. Remember the Lorentz Force

7. Why isn’t the photon visible ? • A photon does not possess an electric charge. Therefore, it does not transfer energy to the medium. Hence, it does not cause the initiation of boiling along its path, therefore you get no bubbles. • What other particles would not leave a track in a bubble chamber ? • A charged particle travelling through the same medium interacts with it trough Coulomb’s Force. In this way it transfers enough energy to initiate the liquid boiling and leaving behind a trail of small bubbles.

8. Relate the movement of the deflected particles with their charge and the direction of the magnetic field B A An electron ( e - ) and a positron (e + )leave the tracks shown in the picture. Which is which?

9. B A Relate the movement of the deflected particles with their charge and the direction of the magnetic field An electron ( e - ) and a positron (e + )leave the tracks shown in the picture. The particle that deflects to the right ( track B) is an electron ( e- ). The particle that deflects to the left ( track A) is a positron ( e+ ).

10. e- D e+ C Explain the materialization of particle pairs (matter & antimatter) to the energy of the photon which preceded them One of the photons emitted at C travels to D where it interacts with a nucleus from the liquid and materializes into an electron/positron pair. To a good approximation, all of photon’s energy is shared by the e-/e+ pair. Calculate the kinetic energy of the materialized system, knowing that the linear momentum of the photon is 26531 MeV/c .( me =0,511Mev/c2 )

11. e- D e+ C Calculate the kinetic energy of the materialized system, knowing that the linear momentum of the photon is 26531 MeV/c .( me =0,511Mev/c2 ) E =h p=h/ Eo= mc2 E = 2Eo + K(e-,e+)

12. Apply the Conservation of Momentum to a head-on collision between a positron and an electron E At point E a rare event took place:the positron track changed into a negative track. What happened was that the positron made a head-on collision with an electron. What is the linear momentum of the electron if the incoming positron’s linear momentum was 54±15MeV/c? (melecton=mpositron)