Element

Decay

Energy/MeV

Air range/cm

Underwater range/µm

Range in ZnS(Ag)/µm

Ra-226

α

4.761

3.290

33.292

26.113

U-234

α

4.756

3.240

32.786

25.716

Th-230

α

4.66

3.150

31.876

25.001

U-238

α

4.169

2.600

26.310

20.636

Th-232

α

3.933

2.500

25.298

19.843