Part I: Part I: Part I: Part I: Detection of Charged Particles Detection of Charged Particles - Energy Loss of Charged Particles Energy Loss of Charged Particles Energy Loss of Charged Particles Interactions Interactions of of Particles Particles with with Matter Matter The physical processes which enable us to detect particles are different for neutral and charged particles: different for neutral and charged particles: Photon (): photoelectric Compton effect Compton effect creation of an electron-positron pair Electron or positron (or other charged particles) El i i i ih h i l f h d Electromagnetic interactions with the atomicelectrons of the detector material Neutron Strong interaction with nuclei to produce charged secondary particles. Neutrino Energy Loss of Charged Particles Weak interaction with nuclei or with electrons Interactions Interactions of of Charged Charged Particles Particles with with Matter Matter Of all possible interactions, only electromagnetic one i ll d f dt ti is generally used for detection. If a charged particle traverses a layer of material, three processes can occur [1]: three processes can occur [1]: atoms can be ionized; the particle can emit Cherenkov radiation; or the particle can cause the emission of transition radiation Bethe-Bloch formula [2,3,4,5] on energy loss due to excitation and ionization of the atoms of the medium itself. Energy Loss of Charged Particles Energy Energy Loss Loss (E) due due to to Ionization Ionization of of Atoms Atoms in in Gas Gas e – e – E i E f e – Traveling through a medium (e.g., gaseous medium) X Energy Loss of Charged Particles after many EM interactions Energy loss E = E f E i
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Part I:Part I:Part I:Part I:Detection of Charged Particles Detection of Charged Particles --Energy Loss of Charged ParticlesEnergy Loss of Charged Particles
� The physical processes which enable us to detect particles aredifferent for neutral and charged particles:different for neutral and charged particles:
� Photon (�):� photoelectric� Compton effect� Compton effect� creation of an electron-positron pair
� Electron or positron (or other charged particles)El i i i i h h i l f h d� Electromagnetic interactions with the atomic electrons of the detectormaterial
� Neutron� Strong interaction with nuclei to produce charged
New York 1975 See Chapter 13New York, 1975. See Chapter 13.6) J.H. Cobb, Ph.D. thesis, University of Oxford (1975); J.H. Cobb
et al., Nucl. Instr. Meth. 133, 315 (1976).7) I L h t l N l I t M th 153 347 (1978)7) I. Lehraus et al., Nucl. Instr. Meth. 153, 347 (1978).8) F. Sauli, Principles of Operation of Multiwire, Proportional and
Drift Chambers, CERN report 77-09 (1977).
Energy Loss of Charged Particles
Part II:Part II:Part II: Part II: Radiation Loss of ElectronsRadiation Loss of Electrons
Energy Loss of Charged Particles Energy Loss of Charged Particles
Energy Loss of Charged Particles Energy Loss of Charged Particles
Energy Loss of Charged Particles Energy Loss of Charged Particles
Energy Loss of Charged Particles Energy Loss of Charged Particles
Energy Loss of Charged Particles
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Energy loss due to ionizationand other processes
Energy Loss of Charged Particles
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Home Work Problem 5 (not for PHYS 736)
� Using Bethe-Bloch formula, plot the energy loss rate(MeV cm2/g) of a muon in argon as a function of the( g) gmuon momentum (GeV/c). Find the numerical value ofits energy loss rate at the minimum ionizing point?
� Suppose that the central core of a cosmic ray shower, atsea level contains a narrow vertical parallel beam ofsea level, contains a narrow vertical parallel beam ofmuons of energy 1000 GeV, which penetratesunderground. Assume that ionization loss in rock is
2 M V 2/ Fi d h d h i kconstant at 2 MeV cm2/g. Find the depth in rock atwhich the muon comes to rest, assuming a rock densityof 3.0 g/cm3.