Properties of plutonium isotopes
Plutonium isotopes emit alpha rays except plutonium-241 for which the energy of beta electrons is remarkably low. Most alpha decays are direct, ie not accompanied by gamma rays, which explains that gamma energy per disintegration is particularly low (1 or 2 keV on average). Periods (half-lives) of 14 and 88 years are relatively short for the isotopes 238 and 241 which are the most active but are expressed in thousands of years for the other isotopes. The alpha decay of plutonium-238 emits considerable heat.
IN2P3(Source Encyclopaedia Britannica)