Physics and Engineering of Radiation Detection

1.6. General Properties and Sources of Particles and Waves 55

Table 1.6.6: Commonαemitters, the energies of their most probable emissions,
and their half lives (26).

Element Isotope Energy (MeV) T 1 / 2

Ameritium^24195 Am 5.443 (13%), 5.486 (85.5%) 432.2 years

Bismuth^21383 Bi 5.549 (7.4%), 5.869 (93%) 45.6 minutes

Curium^24496 Cm 5.763 (23.6%), 5.805 (76.4%) 18.1 years

Californium^25298 Cf 6.076 (15.7%), 6.118 (82.2%) 2.645 years

Radium^22388 Ra 5.607 (25.7%), 5.716 (52.6%) 11.435 days

Thorium^22990 Th 4.845 (56.2%), 4.901 (10.2%) 7340 years

Plutonium^23994 Pu 5.144 (15.1%), 5.156 (73.3%) 24110 years

Polonium^21084 Po 5.304 (100%) 138.376 days

−3

10

10

−2

10

−1

1

10

60 90 120 150 180

Fission Fragment Yield (%)

A~118

A~95 A~137

Mass Number (A)

Figure 1.6.10: Typical fission

spectrum of uranium-235.

As an example, let us have a look at how uranium-235 fissions. The following
equation shows the process for two of the most probable fission fragments:^14054 Xe