Question

We use a detector to detect 1172 keV energy only of ⁶⁰Co. The detector has been shielded with some blocks of lead, Pb (X-ray of 75 keV). Draw the spectra and show the value of the following energies:

Interaction with Pb shielding, E_S

Photoelectric peak, E_PE

The maximum value of the Compton effect, E_CE (Compton edge)

The back scattering peak, E_BS

Double escape peak, E_DE

Annihilation peak, E_A

Single escape peak, E_SE

Answer 1

A Cobalt 60 gamma spectrum with detector for 1172 KeV. It is a small crystal

You may ignore the peak at E and assume that spectrum falls off after peak at D as our detector detects 1172 KeV peak at D only.

Interaction with Pb shielding - A (75 KeV)

The photoelectric peak - D (1172 KeV)

Compton Edge - C (usually 1118 KeV)

(F has been wrongly marked in the picture. It is not a compton edge. It is just some compton interactions)

Back Scattering Peak - B (212 KeV)

*The double escape peak, annihilation peak and single escape peak are not noticeable in 60 Co spectrum.