sPHENIX MAPS tracker discussion

[Anthony Frawley <afrawley AT fsu.edu>]

Hello Ross and Molly,

Interesting! Some comments/questions:

1) Why electrons? There will be significant tails on the extrapolation for electrons after 8% of a radiation length in 4 layers of INTT. 

2) You extrapolated to the inner field cage at 20 cm. The inner tracking radius is 30 cm, where space charge distortions will be worst.  Can you push it to 30 cm?

3) I am surprised  by the Z resolution for "11" and "111" on slide 4 and 5. I would have expected these to be much worse than those for any configuration having a "0" layer. The implication of this is that the Z resolution is dominated by the MVTX (which is actually not insane, it has 5 micron resolution per layer vs ~40 micron resolution for the INTT "0" layers). This raises the question of whether the INTT matters at all to the Z extrapolation accuracy. Can you try it with no INTT at all?

4) You are using a fixed momentum of the particles, and the extrapolation trajectory in r-phi is always the same at fixed momentum. I assume that the extrapolation uses the momentum measured by the MVTX and INTT to predict the hit location, and you show the distribution around the mean.  The momenta we would actually be using would be a few hundred MeV/c to maybe 1 GeV/c, and we would not have the momentum from a precise TPC measurement until we have already corrected for space charge effects. It may be that we can take the TPC space points at the space charge crossover point to get a better estimate of the track momentum, but otherwise we rely on the momentum measurement by the MVTX + INTT for the extrapolation. Can you try it with a continuous range of particle momenta?

Best regards

Tony

---

From: Ross Corliss <rcorliss AT mit.edu>
Sent: Thursday, October 4, 2018 7:16 PM
To: christof.roland AT cern.ch
Cc: jhuang AT bnl.gov; Todoroki, Takahito; Carlos Perez; Anthony Frawley; Chiu, Mickey; Sanghoon Lim; Molly Taylor; sphenix-intt-l AT lists.bnl.gov; sphenix-maps-l
Subject: Re: Meeting of the Inner Tracker Task Force VIRTUAL

 

I've uploaded some slides to the indico page ( https://indico.bnl.gov/event/5107/contributions/24213/attachments/20273/27051/TPC_IFC_resolutions_from_INTT.pdf ) showing the resolutions we're getting by extrapolating the Kalman track stubs in the MVTX+INTT out to the inner field cage.  

-Ross

 

On Oct 2, 2018, at 11:10 AM, Christof Roland <christof.roland AT cern.ch> wrote:

Hi Everybody,

since some of us are at the hard probes conference we will make the 

task force meeting scheduled tomorrow virtual. There will not be an actual 

meeting, but please post new material you would like to share on the indico 

page or add it to the google doc so we can look at it offline and discuss by email

https://indico.bnl.gov/event/5107/

https://docs.google.com/document/d/17PJdu94Ydg25V-cTHIYfSbkfojH4ZUEfsfoZPm0RDb0/edit

Cheers

   Christof