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Unformatted text preview: Physics 433  Lecture 5 • Next week and following weeks we will have several experiments set up in the lab – Compton Scattering – Proportional Counters and Tubes – Muon Lifetime (data taking for entire week) – Drift velocity of electrons in a constant electric field • Thursday and Friday labs will cycle through Compton Scattering, proportional tubes, drift velocity in gases and muon life time measurements – In lab we will assign a letter to your group so that I can inform you of each week’s lab in time for you to read the lab instruction sheet before coming to lab – Friday November 11 is a holiday so the Friday lab will have a lab on December 2. • The week of December 5 will be the last week to complete a missed lab October 27, 2011 Henry Lubatti 1 Review October 27, 2011 Henry Lubatti Physics 433 – Lecture 5 • Cross section continued – Incident beam (N i /unit vol.) is spread over area A > target – Probability that a particle interacts in distance dx is given by N i Adx/A = N i dx = N s /N i , where N s and N i are the number of scattered and incident particles, respectively – As defined, is the total cross section; if the beam area is less than area of target, A is the area covered by beam – Differential cross section gives the probability of a particle scattering into a solid angle ( Ω ) per unit time, which introduces the concept of flux • Flux, F, equals particles per unit area per unit time • Because this is a random process we average over many different measuring periods and obtain a fixed differential cross section – d /d (E, ) = (1/F)dN s /d where N s is number scattered/time and FA = N i gives the incident particles per unit time – Total cross section is obtained by integrating over 4 – Mean free path is mean distance between collisions = 1/ N 2 Review October 27, 2011 Henry Lubatti Physics 433  Lecture 5...
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This note was uploaded on 01/28/2012 for the course PHYSICS 433 taught by Professor Henrylubatti during the Fall '11 term at University of Washington.
 Fall '11
 henrylubatti
 Physics

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