Time fix #119
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Time fix #119
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This pull request assigns proper space and time coordinates from Pythia decayed particles according to our new definitions: space in fm and time in ys.
I took the liberty to have some optimisations and I changed the unit definitions from
static consttostatic constepxrso the scaling factors could be defined asconstexpr. This trick could be done with constants as well but it was beyond the scope of this fixes and I will defer to a later moment.About the validation tests. I generated tau events, enabling the pythia decay for tau. The taus were generated on protons, with a uniform flux up to 35 GeV.
With a macro (available in $GENIE/contrib/pythia_units) I extracted time of flight and decay length for the taus and I plotted them.
As you can see the length goes up to 18 X 10^12. Being this in fm, this corresponds to a maximum of 1.8 cm which is expected from the typical OPERA experience.
To understand the time unit, I fitted the points.
The slope is about 0.3 fm / x and it is supposed to be the speed of the tau, which is heavily boosted so, close to the speed of light ( about 3 X 10^8 m/s ). Solving for x, that is 10 ^-24 s as expected. So the time is in ys.
Let me know if we need more.