Interactions of Radiation with Mattercosmicraysschool.ufabc.edu.br/pres/Pietro.pdf · Interactions...
Transcript of Interactions of Radiation with Mattercosmicraysschool.ufabc.edu.br/pres/Pietro.pdf · Interactions...
Interactions of Radiation with Matter
Pietro Chimenti25/08/2010
Layout of the presentation:●Introduction
●Interaction of Muons●Of Electrons and Photons
●Of Hadrons
A few referencesTextbooks:●G.F.Knoll, “Radiation Detection and Measurements”, John Wiley and Sons●W.R.Leo, “Techniques for Nuclear and Particle Physics Experiments: A How-to Approach”, Springer
Particle Data Group (many pictures from this):●http://pdg.lbl.gov/2010/reviews/rpp2010-rev-passage-particles-matter.pdf
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
On the subject of this presentationRadiation--> Particles!“Low” intensity: no collective effects!We analyze the interaction of a single particle crossing a material:
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
Particles to be considered●Photon: mass-less, no charge, stable●Electron: M~0.511MeV/c^2, charged, not strongly interacting, stable●Muon: M~106MeV/c^2, charged, not strongly interacting, T~2.2X10^-6 s●Proton: M~938MeV/c^2, charged, strongly interacting, stable●Neutrons, pions, kaons, other nuclei
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
An example of interaction(Bubble chamber)
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
The simplest case: muons
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
If the muon energy is not too high the interaction is dominated by the transfer of
energy to electrons of the material.
The interaction of a fast muon with an atom
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
Differential energy transfer cross section (Rutherford - corrections due to atomic physics
however are needed).
The interaction of a fast muon with an homogeneous material
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
We have to sum (integrate) over the interaction with all the surrounding atoms.
M: momentum of order J of the distribution of released energy. Order 0: total number of
interactions.Order 1: mean released energy
Example: stopping power in Copper
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
Important features: low and high energy behaviour, minimum, Bethe approximation.
Radiative Energy Loss (1)
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
Radiative Energy Loss (2)
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
Radiative Energy Loss (3)
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
Range
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
The range is the typical length traveled by a particle of a given energy in a certain material.
Bragg Peak
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
The Bragg Peak is an increase in energy deposition close to the end of the particle path.
Multiple Coulomb scattering
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
Incoherent scattering of the particle from nuclei.
Stopping power of mixtures
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
A simple weighted sum of the stopping power of the single compounds (Bragg Additivity).
An electromagnetic shower
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
The interaction of electrons, positrons and photons in materials is tightly connected.
The interaction of electrons
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
Important feature: the critical energy.
The critical energy
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
The development of the shower depends on the atomic number Z.
The interaction of photons with materials
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
Three important effects: photoelectric, Compton and pair production.
The dominant process in photon interaction
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
The photon absorption length
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
High Z material (e.g. Lead) are particularly effective in shielding against E.M. radiation.
An eletromagnetic shower in Icarus
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
An hadronic shower in Icarus
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
Basic features of hadronic showers
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
Hadrons produced abundantly, but also muons. E.M. Component much reduced.
How to detect particle interactions
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
●photons from: fluorescence, scintillation, Cherenckov effect, transition radiation●electrons and/or ions from ionization●Phase transition in material (e.g. cloud chamber)●Phonons (crystal lattice vibrations)
A Water Cherenkov Example (Super-Kamiokande)
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
Conclusions
Interactions of Radiation with Matter - Pietro Chimenti - 25/08/2010
I hope you enjoyed the lecture.
Have fun at the school!