放射性是不稳定原子核因辐射失去能量的过程。它以Becquerels（BQ）进行测量。
1 cps = 1 t½
1 t½ = 1 cps
例子:
将15 每秒计数转换为半衰期：
15 cps = 15 t½
| 每秒计数 | 半衰期 |
|---|---|
| 0.01 cps | 0.01 t½ |
| 0.1 cps | 0.1 t½ |
| 1 cps | 1 t½ |
| 2 cps | 2 t½ |
| 3 cps | 3 t½ |
| 5 cps | 5 t½ |
| 10 cps | 10 t½ |
| 20 cps | 20 t½ |
| 30 cps | 30 t½ |
| 40 cps | 40 t½ |
| 50 cps | 50 t½ |
| 60 cps | 60 t½ |
| 70 cps | 70 t½ |
| 80 cps | 80 t½ |
| 90 cps | 90 t½ |
| 100 cps | 100 t½ |
| 250 cps | 250 t½ |
| 500 cps | 500 t½ |
| 750 cps | 750 t½ |
| 1000 cps | 1,000 t½ |
| 10000 cps | 10,000 t½ |
| 100000 cps | 100,000 t½ |
规则