QGJetII produces strange nuclear showers

Iron showers have 25x the Muons of Protons while they should have ~40% more and fluctuations are larger than for protons, while they should be smaller.

This may be related to the nuclear fragments which come on a separate stack in QII.

Original:

Übrigens ist mir aufgefallen, dass unsere Eisenschauer mit QGSJetII völlig verkehrt sind. Es gibt ~25 mal mehr Myonen als für Protonen und die Fluktuationen sind sogar größer (~25 % bei Fe, ~15 % bei p)...

OK.. und schade. Das könnte leicht an den Kern-Fragmenten in QII liegen. Es gibt ja diesen zweiten Output Stack in dem Kernbruchstücke sind. Das spielt für die Protonen Schauer keine Rolle und wir haben es deshalb bisher nicht kontrolliert. Es ist vielleicht nicht genug Zeit vor der ICHEP sich das auch noch anzuschauen... Das ist ja offensichtlich "nur" ein Bug.

added Bug label

created merge request !241 (merged) to address this issue

mentioned in merge request !241 (merged)

changed the description

closed via merge request !241 (merged)

mentioned in commit 6f227571

I'm reopening this issue since I just discovered it has not been fixed. There is an excess of energy in nucleus-air collisions of about a factor of 2 or more.

log

reopened

Ok, I will have look. But didn't you find that the for iron looked OK?

I thought so, too. Perhaps I didn't look carefully enough.

...I just find this old but really important discussion...

is this still the case? If yes, we have to fix it NOW. This is a bug, after all.

@mreininghaus what is your understanding of this at the moment?

It seems to me the fix in !241 (merged) somehow got reverted. At least in !387 (merged) it still says

int beamA = 0;
if (is_nucleus(projectileId)) { beamA = get_nucleus_A(projectileId); }

and later the fragment energy is set to. HEPEnergyType const projectileEnergyLabPerNucleon = Elab / beamA; What puzzles me is that this should cause a problem with hadron projectiles not nuclear ones.

I don't have any news. I can try running some iron showers if necessary.

marked this issue as related to #476 (closed)

I hope this is now fixed, after !413 (merged)

Can someone please simulate a few proton/iron showers to make sure?

@mreininghaus I think you recently calculated showers with QGSjet for ISMD. They looked ok? If yes please close

Yes, after !444 (merged) everything seems ok.

closed