Atomic and nuclear properties of materials:
Liquid argon (Ar) (Ar)

Quantity	Value	Units	Value	Units
Atomic number	18
Atomic mass	39.948(1)	g mole-1
Specific gravity	1.40	g cm-3
Minimum ionization	1.508	MeV g-1cm2	2.105	MeV cm-1
Nuclear collision length	75.7	g cm-2	54.25	cm
Nuclear interaction length	119.7	g cm-2	85.77	cm
Radiation length	19.55	g cm-2	14.00	cm
Critical energy	32.84	MeV (for e-)	31.91	MeV (for e+)
Molière radius	12.62	g cm-2	9.043	cm
Plasma energy	22.85	eV
Muon critical energy	485.	GeV
Melting point	83.79	K	-189.4	C
Boiling point @ 1 atm	87.30	K	-185.9	C
Index of refraction (@ STP, Na D)	1.23

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