Atomic and nuclear properties of erbium (Er)
QuantityValueUnits ValueUnits
Atomic number 68     
Atomic mass 167.259(3) g mole-1   
Specific gravity 9.026 g cm-3   
Mean excitation energy 658.0 eV   
Minimum ionization 1.168 MeV g-1cm2 10.54 MeV cm-1
Nuclear collision length 107.6 g cm-2 11.92 cm
Nuclear interaction length 186.1 g cm-2 20.62 cm
Pion collision length 131.2 g cm-2 14.54 cm
Pion interaction length 213.1 g cm-2 23.61 cm
Radiation length 7.14 g cm-2 0.7916 cm
Critical energy 8.73 MeV (for e-) 8.42 MeV (for e+)
Molière radius 17.36 g cm-2 1.924 cm
Plasma energy ωp 55.20 eV   
Muon critical energy 163. GeV   
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
Table of isotopes via WIKIPEDIA
x ray mass attenuation coefficients from NIST