Sphenix-calibration-l mailing list

[pinkenburg <pinkenburg AT bnl.gov>]

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
> > > > >
> > > > >
> > > > > ----------------------------------
> > > > >
> > > > > Meeting URL
> > > > > https://bluejeans.com/676999731?src=join_info
> > > > >
> > > > > Meeting ID
> > > > > 676 999 731
> > > > >
> > > > > Want to dial in from a phone?
> > > > >
> > > > > Dial one of the following numbers:
> > > > > +1.408.419.1715 (United States(San Jose))
> > > > > +1.408.915.6290 (United States(San Jose))
> > > > > (see all numbers - https://www.bluejeans.com/premium-numbers)
> > > > >
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--
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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
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