Problem 722

Judging from Physics Reference manual of Geant4 and it reference paper as
gEnergy loss in thin layers in GEANT (NIM A362 (1995) 416)h, it looks like
current implementation of G4UniversalFluctuation has wrong conditional
clauses.

Line 105th	if(meanLoss < minLoss) return meanLoss;
Does not required or not fit an approach of Urban model in the paper.

Line 175th	if(suma < sumalim)             // very small Step
is changed to
		if ( exp(-suma) > sumalim)      // very small Step

Please read Physics Reference Manual
http://wwwasd.web.cern.ch/wwwasd/geant4/G4UsersDocuments/UsersGuides/PhysicsRef
erenceManual/html/node31.html equation No (7.23) and following statement and
also equation (12) of the paper.
Here is the point judging very small step or not.

I did test changed version and compare to the original and you can get the
result form http://www.slac.stanford.edu/~tkoi/energy_loss_fluctuation.ppt .

Please compare also the result to the figure 5 and 6 of the paper.
Original result (G4v7.0) is similar to the figure 5 which obtained with
Geant3.1.5 and fixed result is similar to the figure 6 which obtained with
Geant3.1.6. (v7.0 should be similar to the later.)
Please take care, in the paper gamma (lorentz factor) and its corresponding
energy of electrons are wrong.
Ex, in the figure 4, gamma = 1000 is corresponding 5.11 GeV e-(511MeV is
correct valued). I believe gamma values are correct and energy values are
wrong form judging plot shapes and average energy losses in the table 1.
So that I did calculate electron energy of 235 keV (gamma = 1.5) for lower
plots of the figure 5 and 6.