Atomic and nuclear properties of water (vapor) (H₂O)

Quantity	Value	Units	Value	Units
<Z/A>	0.55509
Specific gravity (20° C, 1 atm)	7.562E-04	g cm-3
Mean excitation energy	71.6	eV
Minimum ionization	2.052	MeV g-1cm2	1.552E-03	MeV cm-1
Nuclear collision length	58.5	g cm-2	7.737E+04	cm
Nuclear interaction length	83.3	g cm-2	1.102E+05	cm
Pion collision length	86.0	g cm-2	1.137E+05	cm
Pion interaction length	115.2	g cm-2	1.524E+05	cm
Radiation length	36.08	g cm-2	4.772E+04	cm
Critical energy	98.24	MeV (for e-)	96.11	MeV (for e+)
Molière radius	7.79	g cm-2	1.030E+04	cm
Plasma energy ℏωp	0.59	eV
Muon critical energy	1231.	GeV

Composition:

Elem	Z	Atomic frac*	Mass frac
H	1	2.00	0.111894
O	8	1.00	0.888106
* calculated from mass fraction data

For muons, dE/dx = a(E) + b(E) E. Tables of b(E): PDF TEXT
Table of muon dE/dx and Range: PDF TEXT
Explanation of some entries