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Bubble Chamber Work Group

Bubble Chamber Work Group. Goronwy Jones Agustin Ceba Herrero Barbara Dłużewska Olga Chimczak Stephen Lam Wong Chu Lin. Order of Presentation. Targets of our work group Simple lessons with BC photographs History of BC Overview of 50-minutes lesson FAQs. Stephen Lam. Our Targets.

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Bubble Chamber Work Group

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  1. Bubble Chamber Work Group Goronwy Jones Agustin CebaHerrero Barbara Dłużewska Olga Chimczak Stephen Lam Wong Chu Lin

  2. Order of Presentation • Targets of our work group • Simple lessons with BC photographs • History of BC • Overview of 50-minutes lesson • FAQs

  3. Stephen Lam Our Targets

  4. Our Targets • To create simple lesson with BC photographs • To update webpage on history of BC • To create 50 minutes modular lesson for teaching BC concepts • To create webpage of frequently-asked questions (FAQs)

  5. Olga Chimczak Physics LAWS IN BUBBLE CHAMBER EVENTS I

  6. How do we see particles? • You can make your own cloud chamber and see tracks of particles produced by cosmic rays • Click here for instructions • When a charged particle goes through a superheated liquid, it ionises atomsalong its path and makes the liquid boil, creating a trailof bubbles • Click here for a simulation of bubble formation

  7. How do we see particles? A plane in the sky causes water vapour in the air to condense Charged particle in BC causes superheated liquid to boil

  8. BC photographs • The different coloured tracks are produced by different charged particles • Bright Green kaon K- • Red electron e- • Blue proton p • Why are tracks curve? Click herefor discussion

  9. Forces in magnetic field • A particle of charge q travelling through a magnetic field B with a velocity v experiences a force, given by • We use the formula for the Lorentz force to calculate the value and direction of the force exerted on charged particles by the magnetic field

  10. Forces in magnetic field • The thumb points in the direction of the force F • First finger points in the direction of the magnetic field B • Second finger points in the direction of motion of the positive charge v

  11. Momentum of particles • In principle, the momentum of a charged particle is obtained using the formula

  12. Why do tracks spiral? • Spiralling tracks are common in BC photographs, caused by e- or e+ • An e- loses energy at a considerable rate as it travels through BC liquid • All other charged particles, unless they collide with a nucleus, slow down very gradually – get more curved – as they lose energy by ionisation

  13. Why do tracks spiral? • e- are able to lose energy more quickly by another process in which all accelerated charges radiate • Click here for more information

  14. Barbara Dłużewska Physics LAWS IN BUBBLE CHAMBER EVENTS II

  15. Art of reading tracks Dark tracks belong to a slow particle Spiralling tracks are e- because of their very small mass

  16. Art of reading tracks Particles with large momenta are less curved Particles with small momenta are more curved

  17. Obeying physics laws • All physical laws must be fulfilled in every BC event • Momentum conservation • Charge conservation • Energy conservation • Behaviour of moving charged particles in magnetic field • Other physics laws

  18. momentum Conservation • The primary (orange) beam has –vecharge while one of the two secondary beams has –vecharge (green) and the other +vecharge (bright green) • We also know that the two outgoing tracks have low momentum because they curve significantly in B-field

  19. momentum Conservation • What is the direction of the momentum of the primary beam?

  20. momentum Conservation • Estimate the momenta of the secondary tracks • What is the total momentum after interaction?

  21. momentum Conservation • Clearly the total momentum of the outgoing charged particles does not equal to the momentum of the beam particle • Draw an arrow to show the “missing” momentum • Click here for more info

  22. Charge Conservation • In all BC photographs, the charge of the particle can be only +e or -e • Sign of particles can be determined by the direction of the track’s curvature

  23. Charge Conservation • Click here to find this • The primary beam is K- • What are the charges of secondary particles? [Hint: the red spiral is produced by an electron] • Greenis negative and bright green is positive

  24. Charge Conservation • If this event do not involve other particle, total charge before interaction (-e) is not equal to the total charge after it (0) • But the collision involves a proton (+e), so the total charge is conserved

  25. Charge Conservation • Here is another picture that could be used for a similar exercise

  26. Agustin Ceba History of bubble chamberImproving the bc website

  27. objectives • Improve and publish a webpage on history of BC • Birth and evolution of BC and its main discoveries • Important photographs • 2 articles on history of BC and personal experience • PowerPoint on history of BC

  28. Image detectors before 50’s Cloud chamber Anderson (1932), positron (e+) Nuclear Emulsion Powell (1947), pion (p+)

  29. evolution of bC • It’s faster to reactivate than cloub chambers • The expansion of BC can coincide with the accelerator cycle • BC were very small initially; only a few cubic centimetre of liquid • Big European Bubble Chamber (BEBC) in 70’s has a diameter of 3.7 m

  30. Particles discovered with BC • 1956. Discovery of S0 in a propane BC • 1964. Discovery of  which gives acceptance of Gell-Mann theory of ordering all subatomic particle “eight-fold way” • 1973. Neutral current discovered at CERN’s 25-ton Gargamelle • 1975. Discovery of “charmed” baryon in 7-foot Brookhaven

  31. Possible extensions • Research on earlier particle detectors – cloud chamber & nuclear emulsions • Design a PowerPoint presentation using the contents of the webpage • Short biographies of the people who developed the BC

  32. Wong Chu Lin 50-min lesson plan

  33. 50-Minutes Lessons • Lesson 1 – “Introduction to BC and Basic Feature of the Interactions” • Photographs, Worksheet 1 • Lesson 2 – “Identifying the Particles and Conservation of momentum & Charge” • Lesson 3 – “Particle Interactions – Collisions & Decays” • Lesson 4 – “Principle of determination of momentum”

  34. Possible extensions • Lesson 5 – “Principle of determination of energy” • Lesson 6 – “More complex BC photographs”

  35. Wong Chu Lin faqs

  36. Sample faqs What does LHC stand for? • Large Hadron Collider. Click here for further detail. What are antiparticles? • To every particle that has a non-zero value of some quantity such as electric charge, it is possible to create another particle with the opposite value – this is the antiparticle of the original one. For an example, click here.

  37. Wong Chu Lin Special projects

  38. Special project • Profile of Jonni Fulcher • An example of a collision • Jonni Fulcher Stunts You may need to install the xvid codec - you can download it from here

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