Atomic and nuclear properties of materials:
Selenium (Se)

Quantity	Value	Units	Value	Units
Atomic number	34
Atomic mass	78.96(3)	g mole-1
Specific gravity	4.50	g cm-3
Minimum ionization	1.343	MeV g-1cm2	6.044	MeV cm-1
Nuclear collision length	88.7	g cm-2	19.70	cm
Nuclear interaction length	146.7	g cm-2	32.60	cm
Radiation length	11.91	g cm-2	2.646	cm
Critical energy	17.33	MeV (for e-)	16.79	MeV (for e+)
Molière radius	14.57	g cm-2	3.237	cm
Plasma energy	40.11	eV
Muon critical energy	285.	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