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lecture 2

# lecture 2 - Energy Transfer Health Physics Principles EEE...

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Lecture 1 Health Physics Principles EEE 498, EEE591 Lecture 2 Introduction; Review of Physical Principles: Energy Transfer, Quantum Theory Spring 2012, ASU Robert Metzger,, GWC 387 Energy Transfer Elastic Collision: Between two bodies in which kinetic energy and momentum are conserved. – Collision between two billiard balls – Usually collisions between a high energy neutron and a nucleus with a small Z number. Inelastic Collision: If in a collision the kinetic energy is not conserved the collision is inelastic. – Collision between a hard billiard ball and a rubber band. – Collision between a high energy neutron and a nucleus might be inelastic. Lecture 2 Elastic Collision Lecture 2 2 2 1 1 2 2 2 2 2 1 2 1 2 1 2 1 2 1 2 1 mv MV mv MV mv MV mv MV + = + + = + M m V 1 v 1 Before: M m V 2 v 2 After: Elastic Collision (Cont.) The maximum energy transferred, T , from an energetic projectile (such as a neutron) with energy E to an atom in an elastic head-on collision is: where is: Lecture 2 E T Λ = Λ 2 ) ( 4 M m mM + = Λ Elastic Collision (Cont.) Example: What is the maximum energy that can be transferred from a 1-MeV proton to a) a Si atom, b) to an O atom, and c) to C-12: a) b) Lecture 2 MeV 13 . 0 MeV 1 13 . 0 13 . 0 ) 28 1 ( 28 1 4 ) ( 4 2 2 = × = Λ = = + × × = + = Λ H Si Si H Si H E T M m M m MeV 22 . 0 MeV 1 22 . 0 22 . 0 ) 16 1 ( 16 1 4 ) ( 4 2 2 = × = Λ = = + × × = + = Λ H O O H O H E T M m M m Inelastic Collision • If Φ is the binding energy of the atom: where E A is the energy loss by the neutron and E B is the energy gained by the atom. Lecture 2 atom neutron φ = A B E E

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