decay_evtgen segfault due to genr8 particle ID guidance for eta'

[mashephe]

At the bottom of most template .input files for genr8 there is a block of lines that say:

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%% extra constants not defined by GEANT
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Rho0 = 57,
% RhoPlus = 58,
% RhoMinus = 59,
% omega = 60,
% EtaPrime = 61,
% phiMeson = 62

However, if you use the id 61 for eta', then what gets written ultimately to the HDDM file after conversion is a Lithium-6 nucleus instead of an EtaPrime. This will cause a segfault in decay_evtgen if one tries to use it to decay the HDDM file.

The solution is to change the EtaPrime particle id to 35.

It would be helpful if decay_evtgen handled this a little more gracefully. That guidance posted above has likely proliferated everywhere.