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Question light nucleus propagation 

Forum: Hadronic Processes
Date: 07 Apr, 2013
From: W.J. Llope <W.J. Llope>

Hi all, I started with exampleN04, and made some simple changes to make it look more like STAR at RHIC. Beam-pipe, TPC, and TOF. These are all hollow cylinders, TOF just outside the TPC. Then using the gun, i throw 8 particles per event: pbar,p,dbar,d,tbar,t,antiHe3,He3 with kinematics sampled from flat distributions in pt and pseudorapidity with limits. I draw the geometry and tracks and all looks good. I see reasonable hits in the TPC and TOF.

I call "survival" occurrences of a hit in TOF from a primary (gun-generated) track. Fewer antiprotons survive than do protons, as expected. However, antinuclei have a *higher* survival probability than do the corresponding nuclei, which cannot be. This is true for any of several physics lists that i've tried: QGSP, QGSP_BIC, QGSP_BERT, QGSP_BERT_HP...

I ran Hadr00 for these same particles and several different "targets", and drew the cross-sections. Indeed, the inelastic cross-sections for antinuclei are always larger than those for the same nuclei at the same particle energy, as expected.

I've stared at verbose stepping statements, put counters and various couts in the generation, stepping and event actions, etc, but I just cannot find anything wrong.

I know it'll be difficult, but if you have any suggestions of something I could check, it'd be much
appreciated... best,
     bill

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1 None: Re: light nucleus propagation   (W.J. Llope - 17 May, 2013)
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