Sphenix-calibration-l mailing list

[Hugo Pereira Da Costa <hugo.pereira-da-costa AT cea.fr>]

On 9/1/20 3:17 PM, pinkenburg via sPHENIX-calibration-l wrote:
> Hi Hugo,
>
> I'll take care of PHG4Reco so I know when to rerun the sims. I'll add 
> it to another bugfix I'll commit just now.
>
> Chris
Hi Chris, others,

Before redoing the HIJING file production with a new TPC gas, (if not 
already started), maybe it is also worth updating the vertex 
distribution, to match the one going with the 50kHz background. My 
understanding from discussion during past meetings is that it should 
have a sigma of 8cm instead of 30cm as it is now. Correct ?

Comments welcome,

best,

Hugo



> On 9/1/2020 4:50 PM, Hugo Pereira Da Costa via sPHENIX-calibration-l 
> wrote:
> > ok so I guess the "only" thing to do to get this going is to update 
> > the code at the different places where the gaz mixture is used. If 
> > noone else is working on this already, I can work on that and submit 
> > a pull request today or tomorrow.
> >
> > The places that I know of that need change are
> >
> > PHG4Reco (where sPHENIX_TPC_Gas material is defined)
> >
> > PHG4TpcElectronDrift
> >
> > Are there others that you know of ?
> >
> >
> > Hugo
> >
> >
> >
> >
> > On 9/1/20 1:19 PM, Ross Corliss via sPHENIX-calibration-l wrote:
> > > Hi Chris,
> > >
> > > The timescale of a few days matches up with the amount of production 
> > > time it would take to produce the down-stream root files anyway.  If 
> > > the revised run doesn't have to clobber the old dataset right away, 
> > > I can't offhand think of a reason not to go ahead.
> > >
> > > -Ross
> > > > On Sep 1, 2020, at 2:38 PM, pinkenburg via sPHENIX-calibration-l 
> > > > <sphenix-calibration-l AT lists.bnl.gov> wrote:
> > > >
> > > > Hi Ross,
> > > >
> > > > the only thing that matters for the hijing running is the gas 
> > > > composition. The translation into electrons is done during 
> > > > analysis. Currently we use 90%Ne:10%CF4.
> > > >
> > > > I wouldn't be too concerned about rerunning - this takes about a 
> > > > day or two. I would prefer this over adding a correction for this 
> > > > somewhere downstream
> > > >
> > > > Chris
> > > >
> > > >
> > > > On 9/1/2020 2:18 PM, Ross Corliss via sPHENIX-calibration-l wrote:
> > > > > Hi Hugo,
> > > > >
> > > > > Though eventually that would be strictly correct, I think we are 
> > > > > not very sensitive to that detail.  The energy loss across the 
> > > > > length of the tpc (assume path of 100cm) goes from 210keV for a 
> > > > > MIP to 428keV, small compared to the scales we're concerned with.
> > > > >
> > > > > We could for the moment get the approximately correct primary 
> > > > > ionization regardless of the HIJING by scaling the TPC hit->eion by:
> > > > > double gasCorrection=( 0.50 * Ne_dEdx + 0.50 * CF4_dEdx)/( 0.90 * 
> > > > > Ne_dEdx + 0.10 * CF4_dEdx)
> > > > >
> > > > > This would give us the amount of energy that would have been 
> > > > > deposited in the proper gas, and all will proceed correctly, save 
> > > > > that at the end of its path the MIP will have 200keV more energy 
> > > > > than it should, and slightly less deflection of its path.
> > > > >
> > > > > Chris, can you confirm the energy loss (or the gas mixture) 
> > > > > assumed in the current hijing events?
> > > > >
> > > > > Are there other impacts we need to consider?
> > > > >
> > > > > -Ross
> > > > > > On Sep 1, 2020, at 2:08 PM, Hugo Pereira Da Costa via 
> > > > > > sPHENIX-calibration-l <sphenix-calibration-l AT lists.bnl.gov> wrote:
> > > > > >
> > > > > > Hi Ross, others
> > > > > >
> > > > > > Thinking more about this Gas change: I guess that means that all 
> > > > > > Hijing simulations from Chris need to be redone (due to the 
> > > > > > ionization/cm change) correct ?
> > > > > >
> > > > > > Is this really what we want to do, now, with the pressing 
> > > > > > deadlines ?
> > > > > >
> > > > > >
> > > > > > On 9/1/2020 12:02 PM, Ross Corliss via sPHENIX-calibration-l wrote:
> > > > > > > Thanks, Hugo and all who attended.
> > > > > > >
> > > > > > > Per discussion in the meeting today, future spacecharge 
> > > > > > > simulations will use Ne:CF4 50:50 gas, with the following 
> > > > > > > parameters:
> > > > > > >
> > > > > > > double Ne_dEdx = 1.56;   // keV/cmI
> > > > > > > double CF4_dEdx = 7.00;  // keV/cm
> > > > > > > double Ne_NTotal = 43;    // Number/cm
> > > > > > > double CF4_NTotal = 100;  // Number/cm
> > > > > > >
> > > > > > > double dEdx=Ne_dEdx*0.5+CF4_dEdx*0.5;
> > > > > > > double NTot=Ne_NTotal *0.5+CF4_NTotal *0.5;
> > > > > > >
> > > > > > > these produce an expected 71.50 e-/cm for MIP tracks.
> > > > > > >
> > > > > > > double ionMobility=1.65; //cm^2/(V*sec)
> > > > > > > double elecDriftVelocity=8;//cm/us)
> > > > > > >
> > > > > > > the elecDriftVelocity is essentially the same for 50:50 and 
> > > > > > > 90:10 (if you have a more precise number, please feel free to 
> > > > > > > propose it).  The ionMobility, however, has changed by a factor 
> > > > > > > of two, and the ionization is 50% higher.
> > > > > > >
> > > > > > > To keep the overall gain the same, the amplification gain should 
> > > > > > > be scaled by the ratio 48.7/71.5 -- the 90:10 ionization per cm 
> > > > > > > over the 50:50 ionization per cm.
> > > > > > >
> > > > > > >
> > > > > > > -Ross
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > > On Sep 1, 2020, at 10:47 AM, Hugo Pereira Da Costa via 
> > > > > > > > sPHENIX-calibration-l <sphenix-calibration-l AT lists.bnl.gov> wrote:
> > > > > > > >
> > > > > > > > Friendly reminder: we meet in 15 minutes. Talk to you soon !
> > > > > > > >
> > > > > > > > Hugo
> > > > > > > >
> > > > > > > >
> > > > > > > > On 8/31/20 8:45 AM, Hugo Pereira Da Costa via 
> > > > > > > > sPHENIX-calibration-l wrote:
> > > > > > > > >   Dear all,
> > > > > > > > >
> > > > > > > > > Last week it was decided that the next meeting dedicated to 
> > > > > > > > > space charge distortions in the TPC wil occur tomorrow, Sept. 
> > > > > > > > > 1st, at 11AM EST
> > > > > > > > >
> > > > > > > > > It will cover activities related to both the TPC monitoring 
> > > > > > > > > detector (Outer Tracker) and space charge calibration software.
> > > > > > > > >
> > > > > > > > > Outer Tracker specific matters, if any, will be discussed first.
> > > > > > > > >
> > > > > > > > > The indico page is at https://indico.bnl.gov/event/9302/
> > > > > > > > >
> > > > > > > > > contributions are welcome.
> > > > > > > > >
> > > > > > > > > Connection details are below.
> > > > > > > > >
> > > > > > > > > Best,
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > Hugo
> > > > > > > > >
> > > > > > > > >
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> > > > --
> > > > *************************************************************
> > > >
> > > > Christopher H. Pinkenburg    ;    pinkenburg AT bnl.gov
> > > >                 ;    http://www.phenix.bnl.gov/~pinkenbu
> > > >
> > > > Brookhaven National Laboratory    ;    phone: (631) 344-5692
> > > > Physics Department Bldg 510 C    ;    fax:   (631) 344-3253
> > > > Upton, NY 11973-5000
> > > >
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