LEVEL 3 LABORATORY

High Energy Physics

High Resolution Gamma-ray Spectroscopy

Objectives of the Project

• Become familiar with the characteristics of a coaxial solid state Germanium (Ge) detector.
• Investigate the gamma-ray spectra of either soil/sand samples or granite samples.

Apparatus

• Soil/sand or granite samples.
• Coaxial Ge detector.
• High voltage supply.
• Electronics: Spectroscopy amplifier, Multi-channel Analyser (MCA).

Experimental Procedure

1. Measure the efficiency of the detector as a function of gamma-ray energy at the recommended operating voltage of the detector.
2. Measure the resolution of the detector as a function of gamma-ray energy at the recommended operating voltage of the detector.
3. At a gamma-ray energy of 0.662 MeV, determine the efficiency and resolution of the detector for various applied voltages up to the recommended operating voltage. What area of the detector is functioning at low applied voltages?
4. Study the spectral energy distributions of several radioactive sources, e.g. Na22, Cs137, Co60.
5. Measure the gamma-ray background with the detector inside and outside the lead shielding. Identify any lines in the background spectrum.
6. Collect sand and/or soil samples and determine their gamma ray spectra or investigate the gamma ray emissions from a variety of granite samples.

Safety and Precautions

Co60, Cs137 and Na22 emit gamma radiation. The sources must only be handled using the tweezers provided.

References

• Knoll, G.F: Radiation Detection and Measurement.
• Leo W.R.: Techniques for Nuclear and Particle Physics Experiments
• Useful statistics

Useful Links

• Nuclear Wallet Card Presents selected properties of all known nuclides and their known isomeric states.
• NIST Physics Laboratory Holdings by Element Useful listing of spectral and nuclear data organised in a periodic table.
• Table of nuclides from the Nuclear Data Evaluation Lab. Korea Atomic Energy Research Institute