Atomic and nuclear properties of materials:
Roentgenium (Rg)

Quantity	Value	Units
Atomic number	111
Atomic mass	[272.1536]	g mole-1
Specific gravity	??	g cm-3
Minimum ionization	1.123	MeV g-1cm2
Nuclear collision length	123.2	g cm-2
Nuclear interaction length	218.6	g cm-2
Radiation length	5.00	g cm-2
Critical energy	5.87	MeV (for e-)
Molière radius	18.04	g cm-2
Plasma energy	68.86	eV
Muon critical energy	114.	GeV

For muons, dE/dx = a(E) + b(E) E. Tables of b(E): PS PDF TEXT
Table of muon dE/dx and Range: PS PDF TEXT
Explanation of some entries
Note: Since there is no stable isotope, given atomic mass is that of the longest-lived known isotope as of Jan 2007.
Note: Density 14.0 g/cm³ and I_eff = 1143 eV assumed in calculating critical energies and dE/dx.
Table of isotopes