1

Americium‑241

6 × 10 ¹¹

2

Americium‑241/Beryllium

6 × 10 ¹¹

3

Caesium‑137

1 × 10¹²

4

Californium‑252

2 × 10¹¹

5

Cobalt‑60

3 × 10¹¹

6

Curium‑244

5 × 10¹¹

7

Gadolinium‑153

1 × 10¹³

8

Iridium‑192

8 × 10¹¹

9

Plutonium‑238

6 × 10¹¹

10

Plutonium‑239/Beryllium

6 × 10¹¹

11

Promethium‑147

4 × 10¹⁴

12

Radium‑226

4 × 10¹¹

13

Selenium‑75

2 × 10¹²

14

Strontium‑90/Yttrium‑90

1 × 10¹³

15

Thulium‑170

2 × 10¹⁴

16

Ytterbium‑169

3 × 10¹²