Atomic and nuclear properties of materials:
Soft tissue (ICRU four-component)

Quantity	Value	Units	Value	Units
<Z/A>	0.54975
Density	1.00	g cm-3
Mean excitation energy	74.9	eV
Minimum ionization	1.972	MeV g-1cm2	1.972	MeV cm-1
Nuclear collision length	58.5	g cm-2	58.53	cm
Nuclear interaction length	83.5	g cm-2	83.49	cm
Pion collision length	86.0	g cm-2	86.01	cm
Pion interaction length	115.4	g cm-2	115.4	cm
Radiation length	36.85	g cm-2	36.85	cm
Critical energy	79.68	MeV (for e-)	77.57	MeV (for e+)
Molière radius	9.81	g cm-2	9.806	cm
Plasma energy	21.37	eV
Muon critical energy	1042.	GeV

Composition:

Elem	Z	Atomic frac*	Mass frac*
H	1	1.00	0.101172
C	6	0.09	0.111000
N	7	0.02	0.026000
O	8	0.47	0.761828
* 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