Lecture 1Health Physics PrinciplesEEE 498, EEE591Lecture 2Introduction; Review of Physical Principles: Energy Transfer, Quantum Theory Spring 2012, ASURobert Metzger,, GWC 387Energy 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 2Elastic CollisionLecture 222112222212121212121mvMVmvMVmvMVmvMV+=++=+MmV1v1Before:MmV2v2After:Elastic Collision (Cont.)•The maximum energy transferred, T, from an energetic projectile (such as a neutron) with energy Eto an atom in an elastic head-on collision is:where is: Lecture 2ETΛ=Λ2)(4MmmM+=ΛElastic Collision (Cont.)•Example: What is the maximum energy that can be transferred from a 1-MeVproton to a) a Si atom, b) to an O atom, and c) to C-12:a)b) Lecture 2MeV13.0MeV113.013.0)281(2814)(422=×=Λ==+××=+=ΛHSiSiHSiHETMmMmMeV22.0MeV122.022.0)161(1614)(422=×=Λ==+××=+=ΛHOOHOHETMmMmInelastic Collision• If Φis the binding energy of the atom:where EAis the energy loss by the neutron and EBis the energy gained by the atom.Lecture 2atomneutronφ−=ABEE
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