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[Ross Corliss <rcorliss AT mit.edu>]

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
>>>>>> 
>>>>>> 
>>>>>> ----------------------------------
>>>>>> 
>>>>>> 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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> 
> -- 
> *************************************************************
> 
> 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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