Atomic and nuclear properties of materials:
Tissue-equivalent gas (Methane based)

Quantity	Value	Units	Value	Units
<Z/A>	0.54993
Specific gravity (20° C, 1 atm)	1.06E-03	g cm-3
Mean excitation energy	61.2	eV
Minimum ionization	2.062	MeV g-1cm2	2.194E-03	MeV cm-1
Nuclear collision length	57.8	g cm-2	5.435E+04	cm
Nuclear interaction length	82.1	g cm-2	7.717E+04	cm
Pion collision length	85.3	g cm-2	8.019E+04	cm
Pion interaction length	114.1	g cm-2	1.072E+05	cm
Radiation length	39.83	g cm-2	3.743E+04	cm
Critical energy	107.61	MeV (for e-)	105.29	MeV (for e+)
Molière radius	7.85	g cm-2	7376.	cm
Plasma energy	0.70	eV
Muon critical energy	1320.	GeV

Composition:

Elem	Z	Atomic frac*	Mass frac*
H	1	1.00	0.101869
C	6	0.38	0.456179
N	7	0.02	0.035172
O	8	0.25	0.406780
* calculated from mass fraction data.

Explanation of some entries
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