Principle

An alpha-spectrometer, consisting of a photodetector, a preamplifier, a pulse height analyser and a recording device for registration of the spectra is calibrated by means of an open alpha-emitter of known alpha energy (241-Am). The energy spectrum of a radium source which is in equilibrium with its decay products, is recorded and evaluated. The alpha-energies found in this way are allocated to the corresponding nuclides of the radium decay series.

Benefits

• Experience the essence of the Nobel Prizes: Rutherford (1908)
• The combination of multichannel analyzer (MCA), preamplifier and alphadetector leads to precise results
• No vacuum required
• MCA and preamplifier can be used in many other experiments

Tasks

1. The Alpha-spectrum of the 226-Ra is recorded with multichannel analyzer.
2. The calibration spectrum of the open 241-Am alpha-emitter is recorded at the same settings.
3. The alpha-energies corresponding to the individual peaks of the alpha spectrum of the radium are calculated and compared to the values in the literature.

Learning objectives

• Decay series
• Radioactive equilibrium
• Isotopic properties
• Decay energy
• Particle energy
• Potential well model of the atomic nucleus
• Tunnel effect
• Geiger-Nuttal law
• Semiconductor
• Barrier layer