4)An initial number N,O) of nuclei a decay into daughter nuclei B, which are also radioactive. The respective decay probabilities are and B IfAB=2AA, calculate the time(in terms of A a when NB is at its maximum. Calculate NB(max) in terms of N(O)
4)An initial number NA (0) of nuclei A decay into daughter nuclei B, which are also radioactive. The respective decay probabilities areλA and λB . IfλB = 2λA , calculate the time (in terms of λA )when NB is at its maximum. Calculate NB (max) in terms of NA (0)
2.2 Radiation interaction with matter Overview 2)Photon Interactions 3)Neutron Interactions 4)Interaction of Heavy Charged Particles with atter 5Scattering of electrons in a medium
1) overview 2) Photon Interactions 3) Neutron Interactions 4) Interaction of Heavy Charged Particles with Matter 5) Scattering of Electrons in a Medium 2.2 Radiation interaction with Matter
1) overview Protons Electrons Photons Heavy ions (Focused ion beam FIB): Surface atoms removed by sputterin um 50 kev electrons beam broadening below the surface I mm for \-rays, surlace exposure for optical 2 Mev protons X-Rays: requires mask Well defined path Well defined path Dose homogeneity Exponential exposure with depth
1) overview
Intensity of Parallel gamma Rays as a Function of absorber Thickness Intensity, I T M Shell =e收 L Shell Coherent Photoelectric Free e Pair Incoherent production Thickness x 0 mean-free-path length Energy(Mev In 2 Half-Thickness x1/2 ut
Intensity of Parallel Gamma Rays as a Function of Absorber Thickness. Thickness x Intensity, I I = Io e –μx mean-free-path length Half-Thickness
4)Interaction of Heavy Charged Particles with Matter Sketch of Alpha Particle Paths in a Medium Fast moving protons, 4He, and other nuclei are a source E heavy charged particles Shield Coulomb force dominates charge interaction They ionize and excite The Born-Bethe Formula for Energy (give energy to) molecules oss of Charged Particles. on their path dE KM E
4) Interaction of Heavy Charged Particles with Matter Sketch of Alpha Particle Paths in a Medium source Shield Fast moving protons, 4He, and other nuclei are heavy charged particles. Coulomb force dominates charge interaction. They ionize and excite (give energy to) molecules on their path. The Born-Bethe Formula for Energy Loss of Charged Particles. - dE dx = KM z E 2