Detectors of Ionizing Radiation

Lecturer:

Tutor:

Supervisor:

Department of Natural Sciences

Synopsis:

Types of gas filled detectors, DC mode of IC, pulse mode of IC, proportional counters, pulse shape of proportional counter, neutron detection and spectrometry by means of nuclear reactions, principle of Geiger-Mueller counters, corona counter, preliminary of the scintillation detectors, exploitation of organic (solid and/or liquid) scintillators, Cerenkov detector, semiconductor detectors, Li compensated Ge detectors and HPGe detectors as photon detector.

Requirements:

To fulfil requirements for assessment, to know all the content of the course.

Syllabus of lectures:

1. Types of gas filled detectors, energy dissipation per ion pair w, design and operation of the dc or pulse operating ion chambers, formation of negative ions, charge carriers diffusion, recombination and movement, velocity in electric field in various gases and their mixtures.

2. DC mode of IC - saturated current, recombination/diffusion losses - dynamic response, current fluctuation, use of DC working IC to measure of basic dosimetric quantities (gamma ray exposure, kerma, absorbed dose, activity)

3. Pulse mode of IC - carrier collection time, derivation of the pulse shape, pulse amplitude dependency on interaction coordinate in parallel plate, coaxial and spherical IC with full or electron only collection. Fission and gridded pulse chambers.

4. Proportional counters - Townsend avalanche formation, gas multiplication factor, and the Diethorn parameters for proportional gases, space charge effects and energy resolution as result of statistical fluctuation of created ion Paris and gas multiplication factor, Fano factor.

5. Pulse shape of proportional counter - resolution time, counting characteristic, detection efficiency. Different types of PC - 2 or 4 pi windowless, window, gas flow/closed, use of PC for counting and absolute activity measurement alpha/beta. X-Ray counting and spectrometry, beryllium thin windows.

6. Neutron detection and spectrometry by means of nuclear reactions 10B(n,alpha)7Li, 3He(n,p)3H and elastic scattering n,p (hydrogen) in proportional counters, shape and unfolding of spectrum, wall effect, spurious pulses.

7. Principle of Geiger-Mueller counters, external/internal (alcohol/halogen) quenching, counter's live time, counting plateau, dead/recovery time, and service life. Types of GM counters and their detection efficiency for different ionizing radiation.

8. Corona counter - theory of corona discharge, detection of slow energy neutrons through fission or reaction 10B(n,alpha)7Li, non sensitivity to gamma rays.

9. Preliminary of the scintillation detectors. Organic/inorganic detectors. Primary and secondary scintillation process in organic scintillators, energy levels of pi - electrons, radiation/no radiation transition, fluorescence, phosphorescence, delayed fluorescence. Radiative and nonradiative migration of excitation energy -- self-absorption. One and multi component organic scintillators. Conversion efficiency, emission spectra, time constant of light emission, dependency on the types of radiation.

10. Exploitation of organic (solid and/or liquid) scintillators - betas and neutron detection and spectrometry, n - gamma pulse shape discrimination. Classification of inorganic scintillators - pure and activated alkali halides monocrystals - BGO, polycrystalline, glass, and gaseous scintillators. Basic properties, using inorganic scintillators.

11. Cerenkov detector - principle, threshold, differential types. Processing and registration of light photons from detectors - reflection coating, light guides, immersion layer, photomultiplier, and semiconductor light sensitive elements. Dynodes´ multiplication system, construction and shapes.

12. Semiconductor detectors - prompt theory - using p-n junction as detector of charged particles, thickness of depletion region, entrance window, positron sensitive Si detectors, technologies of production. P-I-N planar or coaxial structures

13. Li compensated Ge detectors and HPGe detectors as photon detector, detector cooling.

Detectors from the other semiconductor materials than Si and Ge. Properties of GaAs and CdTe semiconductor detectors

Syllabus of tutorials:

Study Objective:

Aproach to Gas filled detectors (ionization chambers, proportional counters,Geiger-Müller counters, corona counters), organic and inorganic scintillation detectors, Cerenkov counters, and semiconductor detectors.

Study materials:

[1] Knoll, G.F.: Radiation Detection and Measurement. John Wiley & Sons, 1999

[2] Green S.: Fundamentals of Radiation Dosimetry. Taylor & Francis Group 2003

[3] Graham D., Cloke P.: Principles of Radiological Physics. Churchill Livingstone 2003

Note:

Further information:

No time-table has been prepared for this course

The course is a part of the following study plans:

• Bakalářský studijní obor Biomedicínský technik - kombinovaný (compulsory elective course)