| Various known sources of elements that emit gamma radiation
over a wide range of energy are used to carry out energy calibration and
efficiency calibration of gamma-ray detectors.
An ideal radioactive source emits gamma-ray photons at discrete energies
between 10 keV and 1.5 MeV, thus allowing a full spectrum to be analysed or
calibrated.
Calibration sources with long half lives are usually chosen so that they can be used for many years
before becoming too weak to be useful.
The energies shown below associated with the
largest emission intensities (in bold) are the easiest to detect.
| Source |
Half life |
Energies
(keV) |
Intensity
(%) |
22Na |
2.6 yrs |
511 |
g annihilation |
| 1274.5 |
99.9 |
| 56Co |
77.7 days |
846.8 |
99.9 |
| 1037.9 |
14.1 |
| 1238.3 |
67.0 |
| 1360.3 |
4.3 |
| 1771.5 |
15.3 |
| 2598.6 |
16.7 |
| 3253.6 |
7.4 |
| 57Co |
271.8 days |
14.4 |
9.5 |
| 122.1 |
85.5 |
| 136.5 |
10.7 |
| 60Co |
5.3 yrs |
1173.2 |
99.9 |
| 1332.5 |
100.0 |
| 88Y |
106.6 days |
14.1 |
17.7 |
| 14.1 |
34.0 |
| 898.1 |
92.7 |
| 1836.1 |
99.4 |
| 133Ba |
10.5 yrs |
30.6 |
35.6 |
| 31.0 |
65.7 |
| 35.0 |
18.0 |
| 81.0 |
34.2 |
| 276.4 |
7.1 |
| 302.9 |
18.4 |
| 356.0 |
62.2 |
| 383.8 |
8.9 |
| 137Cs |
30.0 yrs |
31.8 |
2.0 |
| 32.2 |
3.8 |
| 36.4 |
1.0 |
| 661.7 |
85.2 |
| 152Eu |
13.3 yrs |
39.5 |
21.2 |
| 40.1 |
38.4 |
| 45.4 |
11.1 |
| 121.8 |
28.4 |
| 244.7 |
7.5 |
| 344.3 |
26.6 |
| 411.1 |
2.2 |
| 778.9 |
13.0 |
| 964.1 |
14.5 |
| 1085.9 |
9.9 |
| 1112.1 |
13.6 |
| 1408.0 |
20.8 |
| 241Am |
432.7 yrs |
13.9 |
13.0 |
| 17.6 |
20.2 |
| 59.5 |
35.7 |
|
