Datafiles for particle and energy reflection coefficients
as a function of impact energy and angle.    

Available projectiles:
H, D, T, He, N, Ne, Ar
(only for self-reflection): Be, C, W

Available targets:
Be, C, W

The tables are calculated with the Monte Carlo program
trvmcmom, which is vectorized version of trim.sp
determining also moments of distributions. The program
assumes a nearly flat surface, a statistically roughness
in the order of a monolayer is taken into account.
Well polished surfaces give a good agreement with the
calculated yields, but for rough surfaces the strong
angular dependence is reduced.

The files named [projectile]_[target].rn contain the
calculated particle reflection coefficient Rn, defined
as the fraction of incident projectile ions which are
backscattered from the surface.

The files named [projectile]_[target].re contain the
calculated energy reflection coefficient Re, defined
in such a way that the mean energy of backscattered
ions, for a constant energy E0 of the incident ions, is
<E> = E0 * (Re/Rn).

The tables are arranged in such a way that rows give an
angular dependence of reflection coefficients at a fixed
energy E0, and columns give an energy dependence at a fixed
angle of incidence. On top of the tables the values for the 
atomic numbers (Z) and the masses (m) of the projectile 
(index 1) and the target atoms (index 2) and the value for
the surface binding energy (Es) are given. Furthermore, the
number ne of incident energies and the number na of incident
angles at which the data are calculated are provided.

The files named [projectile]_[target]_fit.rn and 
[projectile]_[target]_fit.re contain, respectively, the
parameters derived fitting the calculated reflection
coefficients with the empirical Eckstein formula
Rn(E0) = (exp(a1*epsilon^a2))/(1+exp(a3*epsilon^a4)) and
Re(E0) = (exp(b1*epsilon^b2))/(1+exp(b3*epsilon^b4)),
where E0 is the projectile energy, and (a1,a2,a3,a4)
and (b1,b2,b3,b4) are the fitting parameters for particle
and energy reflection coefficients respectively, contained
in the tables for each available value of the projectile
incidence angle.
epsilon is the reduced energy, defined as epsilon = E0/ETF,
where ETF = ((Z1*Z2*e^2)/(alpha_L))*((m1+m2)/(m2)) is the
Thomas-Fermi energy, in which Z1, Z2 are the nuclear charges,
and m1, m2 are the masses of the projectile and target atoms
respectively, and e is the electron charge. Finally, alpha_L,
defined as alpha_L = 0.4685*(Z1^(2/3)+Z2^(2/3))^(-1/2), in
angstrom, is the Lindhard screening length.

The original data are published in W. Eckstein, IPP-Report
9/117, Garching, March 1998.
The fits are produced by A. Zito, Garching, October 2022.