Gamma detection is an important technique used in nearly all areas of Nuclear and Radiochemistry. A long variety of techniques and detector types can be used. On this page we have collected a set of exercises that step-by-step will teach the student the most important techniques using the most common detectors.The individual exercises in the set can either be provided as stand-alone exercises or the whole set can be used as a as large, unified comprehensive package for learning how to detect gamma rays.

The material provided here has been submitted by

• Center for Radiochemistry and Nuclear Materials, Department of Chemistry, Loughborough University (LU)
• Nuclear Chemistry Section, Department of Chemistry, Faculty of Mathematics and Natural sciences, University of Oslo (UiO)

The material was put together to form this stream-lined set of exercises by Jon Petter Omtvedt (UiO). Comments, suggestions etc. can, as usual, be posted in NucWik's comment/discussion pages or e-mailed to NucWik-post@kjemi.uio.no.

Step-by-Step Approach to Learning about Gamma Detection and Spectroscopy (with Hands-on Exercises):

1. Read up on how electromagnetic radiation (like gamma-rays) interact with matter (the detector) in your favorite textbook (or one of these)
2. Read up on how gamma-rays is detected in a scintillation detection (e.g. read this (from Ortec) or this (from Canberra)).
3. Energy Calibration of Gamma-ray Spectra from a NaI Detector (not a hands-on exercise, but preparation for such exercises)
4. Read up on how a semiconductor detector is used for gamma detection (e.g. read this (from Ortec) or this (from Canberra))).
5. Gamma-detection Principle (not a hands-on exercise, but a computer simulation)
6. Basic Usage of a HPGe-detector (hands-on; gain-adjustment, energy and efficiency calibration, sample placement)
7. Tuning a HPGe-detector system (hands-on; using an oscilloscope to inspect signals and pole-zero correction)
8. Peak-fitting and spectrum analysis software (hands-on; advanced use of spectrum analysis software)

Learning Goals

After having completed all the steps in this multi-exercise, you should be able to:

• Set up and tune a complete gamma-spectroscopy system, including the electronics.
• Calibrate a gamma-spectroscopy system with respect to energy and efficiency.
• Understand in detail how gamma rays interact with matter
• Understand in detail the physcial processes in a gamma detector.
• Be able to decide how to place a sample for gamma-ray measurement.
• Be able to evaluate how sample geometry affect counting and spectrum quiality.
• Analyse gamma-ray spectra and know where/how to find relevant information about the gamma-rays.

Relevant Textbooks Sections, Compendia, and WEB Resources

Textbooks:

• Choppin et al.: "Radiochemistry and Nuclear Chemistry" (forth Ed. 2013): Chap. 7 (Absorption of Nuclear Radiation) and Chap. 9 (Detection and Measurement Techniques).
• Loveland et al.: "Modern Nuclear Chemistry" (2006): Chap. 17 (Interaction of Radiation with Matter) and Chap. 18 (Radiation Detectors).

Application notes etc. from commercial companies:

• Canberra (Commercial company) Litterature: Introduction to Gamma and X-ray Detection.pdf
• Ortec AMETEC (Commercial company) litterature: Review of the Physics of Semiconductor Detectors
• Ortec AMETEC (Commercial company) litterature: High-resolution Gamma-ray Spectroscopy
• Ortec AMETEC (Commercial company) litterature: Gamma-Ray Spectroscopy Using NaI(Tl)

Relevant On-line Databases

• Nuclear Chart (IAEA)
• Levels and gamm-ray search tool from NNDC

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Disregard everything under this line - it's being worked upon!

Student Guides

• Using a gamma-detector simulation program to understand how a gamma detector works.

Teacher Guides

Explanation and Exercise Guide

This is a combination of two exercises, what theory and which procedures that would be followed has to be decided by the respective institutes.

Theory

Introduction to Detection of Gamma Radiation
Gamma Spectroscopy and Detectors
Yield in Neutron Activation and Nuclear Reactions
Basics about Efficiency Calibration of Gamma Detectors
Gamma-ray interaction with detector

Experimental Procedure

Procedure for energy calibration
procedure for energy efficiency calibration
Gamma-ray energy tables

Other

suggested tasks for students

After this exercise you should have the following:

• A description of how a Ge-detector works, and what it is.
• Tabulate values and intermediate results you used to plot the efficiency curve. Remember to calculate the uncertainty in the individual points!
• You are free to choose if you want to plot your data by use a computer program (e.g. Origin or MS Excel) or draw them manually.
• The determination of the unkwnown, n-activated metall and its amount.

Give the decay equations for each of the isotopes used (2 marks)
What is the major source of error in this experiment? (1 mark)
What causes the Compton Edge and the backscatter peak? (2 marks)
Why are there two photopeaks for cobalt? (1 mark)
Comment on the resolution value you have measured. (2 marks)

Equipment

Safety Aspects

No open sources