Atomic and nuclear properties of thorium (Th)
QuantityValueUnits ValueUnits
Atomic number 90     
Atomic mass [232.0377(4)] g mole-1   
Specific gravity 11.72 g cm-3   
Mean excitation energy 847.0 eV   
Minimum ionization 1.098 MeV g-1cm2 12.87 MeV cm-1
Nuclear collision length 117.7 g cm-2 10.05 cm
Nuclear interaction length 207.3 g cm-2 17.68 cm
Pion collision length 140.7 g cm-2 12.01 cm
Pion interaction length 233.6 g cm-2 19.93 cm
Radiation length 6.07 g cm-2 0.5182 cm
Critical energy 6.91 MeV (for e-) 6.66 MeV (for e+)
Molière radius 18.64 g cm-2 1.590 cm
Plasma energy ωp 61.44 eV   
Muon critical energy 132. GeV   
Melting point 1408. K 1135. C
Boiling point @ 1 atm 4404. K 4131. C
For muons, dE/dx = a(E) + b(E) E. Tables of b(E): PDF TEXT
Table of muon dE/dx and Range: PDF TEXT
Explanation of some entries
Note: There is a well-defined terrestrial aboundance for thorium even though it is radioactive.
Table of isotopes Warning: may not be current
x ray mass attenuation coefficients