With an energy profile lower than Iridium 192, Selenium is becoming an industry standard. The lower energy profile allows large sources to be used, up to 80 Curies for type A quantities, and still giving reduced controlled areas compared to Iridium.
The long half life, 4 months, allows fewer change outs of the source and with good physical sizes, 3 mm sphere for up to 100 curies, a resolution for a given exposure time comparable to Iridium can be achieved.
| Half-life: |
119.78 days |
| Mode of decay: |
Gamma 66 - 401 keV (avg 217 keV) |
| Optimum working thickness: |
2mm to 30mm steel |
| Exposure Rate: |
1Ci @ 1 metre gives 2050 uSv/hr |
| Exposure Rate: |
1 GBq @ 1 metre gives 55 uSv/hr |
Further Information:
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