#name   Format    He gas
Hegas 	2
#
#  Elem	 rho(g/cm^3)	Gas/Solid(1/0)  refr.index Birks c
#   rho may be 1.663e-4
1         0.1786e-3		1          34.9   0 0 0
# 	Z	A  	N
	2	4.0026	1
#  ⟨Z/A⟩   I[eV]   a       k      x0    x1     Cbar  delta0
 0.4997  41.8 0.1344  5.8347  2.2017  3.6122    11.1393 0.00
