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

Energy Loss of Charged Particles

InteractionsInteractions ofof ParticlesParticles withwith MatterMatter

� 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

secondary particles.� Neutrino

Energy Loss of Charged Particles

� Weak interaction with nuclei or with electrons

InteractionsInteractions ofof ChargedCharged ParticlesParticleswithwith MatterMatter

� Of all possible interactions, only electromagnetic onei ll d f d t tiis 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; orp ;� the particle can cause the emission of transition radiation

� Bethe-Bloch formula [2,3,4,5] on energy loss due toexcitation and ionization of the atoms of the mediumitself.

Energy Loss of Charged Particles

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Energy Loss of Charged Particles

Ref. 7Minimum Ionizing Point

Energy Loss of Charged Particles

Properties of Several Gases

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Energy Loss of Charged Particles

Energy Loss Distribution

Energy Loss of Charged Particles

Energy Loss of Charged Particles Energy Loss of Charged Particles

Energy Loss of Charged Particles

References1) W.W.M. Allison and J.H. Cobb, Ann. Rev. Nucl. Sci. 30 (1980)

253.2) H.A. Bethe, Annalen d. Physik 5 (1930) 325; H.A. Bethe, Z.

Physik 76 (1932) 293; H.A. Bethe, Hdb. Physik 24 (1933) 518.3) R.M. Sternheimer, Phys. Rev. 88, 851 (1952).) , y , ( )4) R.M. Sternheimer and R.F. Peierls, Phys. Rev. B3 (1971) 3681.5) J.D. Jackson, Classical Electrodynamics, 2nd ed., John Wiley,

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 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.

Energy Loss of Charged Particles

g