Atomic and nuclear properties of materials:
Radium (Ra)

Quantity	Value	Units	Value	Units
Atomic number	88
Atomic mass	[226.0254]	g mole-1
Specific gravity	5.00	g cm-3
Minimum ionization	1.111	MeV g-1cm2	5.555	MeV cm-1
Nuclear collision length	116.9	g cm-2	23.38	cm
Nuclear interaction length	205.5	g cm-2	41.09	cm
Radiation length	6.15	g cm-2	1.230	cm
Critical energy	7.19	MeV (for e-)	6.94	MeV (for e+)
Molière radius	18.12	g cm-2	3.625	cm
Plasma energy	40.21	eV
Muon critical energy	137.	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.
Table of isotopes
x ray mass attenuation coefficients