PHYS264-Scattering and Transport Tuesday 2. February 2010 Topic: Differential Cross sections – Classical particle scattering Comment: Preliminary version without text, sent by e-mail PHYS264 spring 2010 page 1

differential cross sections FROM PREVIOUS LECTURES Probability for single scattering – or collision – or deflection – or simply event Now towards the differential cross sections PHYS264 spring 2010 page 2

differential cross section Typical definition of differential cross section We use instead analogy with sport-shooting (air-gun) or darts-game s D P D s = Target – D P – probability for a given event 10,9,5,3 ... D s is the area Of the given «number» s D P D s = What is s ? The area of the target – or e.g. the square enclosing it? It is the area of possible beam/target encounter PHYS264 spring 2010 page 3

As we can see, there is always a COLLISION PLANE. This is given by the two parallel lines: 1. The velocity of the «projectile» through the original position PLANE 2. The line parallel to 1. but passing through the scattering centre SCATTERING PHYS264 spring 2010 page 4

Such scattering can be realized by simple mechanical models – provided we manage to mostly eliminate friction PHYS264 spring 2010 page 5

Attractive potential PHYS264 spring 2010 page 6

Repulsive potential (just changed sign) PHYS264 spring 2010 page 7

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As we can see, there is always a COLLISION PLANE. This is given by the two parallel lines: 1. The velocity of the «projectile» through the original position PLANE 2. The line parallel to 1. but passing through the scattering centre SCATTERING PHYS264 spring 2010 page 10

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http://web.ift.uib.no/AMOS/kepler/ PHYS264 spring 2010 page 14

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slide from Topic_1_2008_exam NEXT TIME PHYS264 spring 2010 page 16

Possible improvements of the «board technology» ? ? ? I will try using my own program in JavaScript inside Sea-Monkey The above has been written using my own program PHYS264 spring 2010 page 17