Atomic and nuclear properties of materials:
Niobium (Nb)

Quantity	Value	Units	Value	Units
Atomic number	41
Atomic mass	92.90638(2)	g mole-1
Specific gravity	8.57	g cm-3
Minimum ionization	1.343	MeV g-1cm2	11.51	MeV cm-1
Nuclear collision length	92.3	g cm-2	10.77	cm
Nuclear interaction length	154.3	g cm-2	18.00	cm
Radiation length	9.92	g cm-2	1.158	cm
Critical energy	14.23	MeV (for e-)	13.77	MeV (for e+)
Molière radius	14.78	g cm-2	1.725	cm
Plasma energy	56.04	eV
Muon critical energy	241.	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
Table of isotopes
x ray mass attenuation coefficients