RADIATION AND DETECTORS

A.A. di erogazione 2020/2021

Laurea Magistrale in FISICA
 (A.A. 2020/2021)

Docenti

L'insegnamento è condiviso, tecnicamente "mutuato" con altri corsi di laurea, consultare il dettaglio nella sezione Mutuazioni
Anno di corso: 
1
Tipologia di insegnamento: 
Caratterizzante
Settore disciplinare: 
FISICA NUCLEARE E SUBNUCLEARE (FIS/04)
Crediti: 
6
Ciclo: 
Primo Semestre
Ore di attivita' frontale: 
48
Dettaglio ore: 
Lezione (48 ore)

The goal of the course is to provide the students with concepts and methods to understand the features of radiation sources, the features of detectors, their behaviour and the info they can provide on the radiation source. The application fields of each detector type will be analyzed in detail in order to understand their pros and cons. Such a course could be of interest for students that intend to work in the field of experimental particle physics, of applied physics (such as medical and environmental physics) and all the physics fields in which detector development is involved (optics, instrumental astrophysics, space physics).
To reach the course goal, the theoretical description of the detectors features and behaviour is completed with the analysis of experimental data acquired with prototypes on accelerator beamlines.

At the end of the course, students will be able to:
- describe the interaction of radiation with matter for all types of radiation and considering also rare effects
- explain the detectors features, their strengths and their limitations depending on the application
- analyze critically the performance of examples of detectors in different physics fields such as particle physics, medical physics, environmental physics
- design a detector system to perform a given physics measurement, taking into account mechanical, physical and cost constraints.

To better understand the topics treated in the course and perform the practical activities, it is advisable that students possess:
- bases of programming and maths
- bases of nuclear and subnuclear physics

as acquired during the bachelor course.

RADIATION SOURCES
- Review of the basics; radioactive decays
- Neutrons: production and discovery; nuclear reactors; neutron sources for medicine; neutron detectors
- Radioactive decay: activity; the law of radioactive decay; chain of radioactive decay
- The radioactive clock: methods of radioactive dating in geological sciences

RADIATION-MATTER INTERACTION
- The interaction of charged particles:
** heavy particles: Bohr’s formula; the Bethe Bloch formula
** electrons and positrons: ionization and bremsstrahlung; the radiation length
** Coulomb multiple scattering and Moliere’s theory
** the use of bent crystals to collimate charged particle beams and produce high energy radiation beams
- The interaction of photons:
** photoelectric effect, Compton scattering, Rayleigh and Thomson scattering, pair production
** photon detection: cross section; spectra as a function of the detector dimension
- Neutron interactions
- Basics of electromagnetic and hadronic showers
- Detectors general features

GAS DETECTORS
- Working principle; ionization mechanisms; primary and secondary pair production; pair production statistics
- Drift and diffusion of charges in gases
- Excitation and ionization; the avalanche multiplication; gas choice
- Multiwire proportional chambers: working principle; spatial resolution; gas type; signal time features; readout methods
- Drift chambers: working principle; spatial resolution; time resolution
- Time Projection Chamber: working principle; examples
- More gas detector types: Cathode Strip Chambers, Resistive Plate Chambers, Microstrip Gas Chambers, Micromegas, GEMs
- Limits and problems with gas detectors
- Fields of application: particle physics, digital radiography, X-ray polarimetry for space

SCINTILLATING DETECTORS
- The production of luminescence: fluorescence and phosphorescence
- Organic and inorganic scintillators: working principles and types
- Light output and linearity; quenching effects in organic scintillators; temperature light output dependence; pulse shape discrimination
- Photon detectors:
** photomultiplier tubes: working principle and features; types
** photodiodes: working principle and spectral response; types (Si pin, APD, Silicon PhotoMultiplier) and their features

SEMICONDUCTOR DETECTORS
- Physics of semiconductors:
** review of the basics; intrinsic and doped semiconductors
** carrier drift and diffusion; carrier injection
** the pn junction: from the basics to the computation of the ideal diode equation
- Features of semiconductor detectors
- Germanium detectors
- Silicon detectors:
** their features and the way they are built
** microstrip detectors: spatial resolution; tracking detector examples
** 2D detectors: double side and pixel detectors; pixel detector types (HAPs, CCDs, MAPs, DEPFETs, SDDs)
** radiation damage
- Silicon detectors in space

PARTICLE IDENTIFICATION
- Analysis of the four methods and of the range of application using existing examples: dE/dx, Time of flight, Cherenkov light emission,Transition Radiation
- Air shower Cherenkov detectors: description of the setups, the observables that can be measured, description of the present telescopes (for instance HESS)

CALORIMETRY
- Basic principles
- Electromagnetic calorimetry:
** the physics of an electromagnetic shower
** the energy resolution: stochastic, noise and constant terms
** homogeneous calorimeters: examples and features of semiconductor, Cherenkov, scintillator and noble liquid calorimeters
** sampling calorimeters: energy resolution and sampling fluctuations; examples of scintillating, gas, solid state, liquid argon sampling calorimeters
- Hadronic calorimetry:
** the physics of a hadronic shower
** electromagnetic and invisible components and the need to “compensate”
** energy resolution and its dependence on the electromagnetic/hadronic ratio
** future calorimeters: the dual readout technique and the particle flow idea
- Low temperature calorimeters

The course is organized in lectures during which the teacher explains in detail each of the topics using examples taken from several physics fields.

Students will be asked to organize one of the lessons: a topic will be assigned to the class (for instance, X-ray detectors for medical or cultural heritage applications, detectors for experiments in extreme conditions): every student has to find the bibliography on that topic for a general discussion in the class itself during one of the lessons, concentrating on the detector features and how they can be implemented.

To test what learned during the theoretical lessons, two sets of experimental data collected with prototypes on accelerator beamlines will be prepared:
- a set of files to measure the spatial resolution of a microstrip silicon detector using high energy particles
- a set of files to measure the energy resolution of a crystal and/or a sampling calorimeter using electron beams of different momenta

Students will analyze at least one of the data sets in the classroom, on their own or in groups, using the software tools developed in the bachelor course. Results will be compared with the published ones.

The final examination is an oral one; the student will choose a topic that he/she will present at the blackboard (no slides). This part of the exam intends to verify:
- the knowledge of a specific topic in the detector physics field
- the capability of analyzing the detector behaviour and its limits, considering also the application field
- the correct use of the technical language needed to explain the detector and the radiation source

In the second part of the exam, the teacher will start from the topic of the first part to ask questions concerning all the items treated during the course. This second part will allow the teacher to check:
- the level of the knowledge acquired by the student in the different topics of the course
- his/her skills in analyzing critically the performance of examples of detectors in different physics fields starting from the effects of the interaction of radiation with matter
- his/her skills in applying what learned in the design of a detection system given the boundary conditions (such as: environment, data taking speed, signal to noise ratio, cost).

To pass the exam, the student has to present the topic chosen in the first part in a satisfactory way, with an adequate language, demonstrating a satisfactory comprehension of radiation-matter interaction and detector features and limits.

To successfully pass the exam, the student should know in detail all the topics treated in the course.

Full marks with laude are assigned to students that accomplish completely what described above, demonstrating to be able to re-elaborate concepts, describe pros and cons of the detector choice for a given application, design solutions once being given the boundary requirements of the application itself.

The following bibliography is used:
- W.R. Leo, ISBN 0-387-57280-5
- G.F. Knoll, ISBN 0-471-07338-5
- K. Kleinknecht, Detectors for particle radiation, 2nd ed, Cambridge Univ. Press, Cambridge, 1998 (ISBN 0521648548)
- slides of the lessons and seminars/articles on the different types of detectors and their applications

For questions/discussion/comments, students are invited to contact the teacher via email at the following address: michela.prest@uninsubria.it

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