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 α = 1 cps
1 cps = 1 α
例子:
将15 α颗粒转换为每秒计数：
15 α = 15 cps
| α颗粒 | 每秒计数 |
|---|---|
| 0.01 α | 0.01 cps |
| 0.1 α | 0.1 cps |
| 1 α | 1 cps |
| 2 α | 2 cps |
| 3 α | 3 cps |
| 5 α | 5 cps |
| 10 α | 10 cps |
| 20 α | 20 cps |
| 30 α | 30 cps |
| 40 α | 40 cps |
| 50 α | 50 cps |
| 60 α | 60 cps |
| 70 α | 70 cps |
| 80 α | 80 cps |
| 90 α | 90 cps |
| 100 α | 100 cps |
| 250 α | 250 cps |
| 500 α | 500 cps |
| 750 α | 750 cps |
| 1000 α | 1,000 cps |
| 10000 α | 10,000 cps |
| 100000 α | 100,000 cps |
规则