sPHENIX MAPS tracker discussion

[nouicer <rachid.nouicer AT bnl.gov>]

Dear Christof,

I would like to point out that the further out (close to the TPC) we put the barrels the less acceptance in pseudorapidity we get.

Right now in the INTT engineering drawings, the INTT outer barrel is at 12.676 cm(inner radius)/13.179 cm (outer radius), and this corresponds to the pseudorapidity is 0.91/0.88 (see attached document).

If we consider layer 2: 15.1183 and 15.6 this implies that the acceptance in pseudorapidity will decrease dramatically. This implies that part of the TPC acceptance will not be covered by the INTT acceptance!

Thanks.

Sincerely,
Rachid

On 10/26/2018 09:21 AM, Christof Roland wrote:

Hi Mickey, 

I tested a INTT configuration with 2 layers, both with rphi resolution, i.e type 1 in Tony's nomenclature

with radii of:

layer 1: 12.676  and 13.179

layer 2: 15.1183 and 15.6

This gives the best performance for the extrapolation precision to the TPC I have seen so far. 

Would a configuration with layer positions in this ballpark be mechanically feasible?

If yes we will do more detailled studies with this setup file. 

Thanks for your input

Cheers

   Christof 

 

On 18. Oct 2018, at 16:39, Mickey Chiu <chiu AT bnl.gov> wrote:

Hi Tony,

After talking to Rachid yesterday, I was about to send out exactly something like this.  I think this is useful because we’ll actually simulate positions that are close to final, rather than choosing a random radius.  

My only comment would be that you do need to have some sort of support structure to hold the detector in place, as well as install it.  Right now our solution is a rail system, and the outer limit available for the INTT is 15.7 cm.  Thus, within the current design limitations, the outermost layer would be

   type 0  - 15.0846

   type 1 -  15.1183

According to what I see, we should be able to push out the rails by 0.5 cm (Dan Cacace disagrees a little).  So if we can push out the rails by 0.5 cm, you can pick the next step out in the radial location.

Mickey

On Oct 17, 2018, at 5:32 PM, Anthony Frawley <afrawley AT fsu.edu> wrote:

Hi All,

I made a little macro to estimate the best sensor radius to use in the tracking macro to get close packing of the ladders. It prints this out as a function of the number of ladders in a layer. If you want to play with it, the macro is at:

/sphenix/user/frawley/macros_newTPC_june6/macros/macros/g4simulations/calculate_optimum_ladder_radii.C

The output is as follows, where I have indicated the  number of ladders presently used for the default configuration with an arrow. The number in parenthesis after the arrow is the radius presently used for the default configuration in the tracking macro. The radii from my macro are within about 0.02 cm for those cases.

Ladder type 0 ladder_rphi 2.55 clearance rphi 0.0365
      nladders 17 sensor_radius 6.85152          <==== (macro: 6.876)
      nladders 18 sensor_radius 7.26318       nladders 19 sensor_radius 7.67483       nladders 20 sensor_radius 8.08649       nladders 21 sensor_radius 8.49814       nladders 22 sensor_radius 8.90979       nladders 23 sensor_radius 9.32145       nladders 24 sensor_radius 9.7331       nladders 25 sensor_radius 10.1448       nladders 26 sensor_radius 10.5564       nladders 27 sensor_radius 10.9681       nladders 28 sensor_radius 11.3797       nladders 29 sensor_radius 11.7914       nladders 30 sensor_radius 12.203       nladders 31 sensor_radius 12.6147       nladders 32 sensor_radius 13.0263       nladders 33 sensor_radius 13.438       nladders 34 sensor_radius 13.8496       nladders 35 sensor_radius 14.2613       nladders 36 sensor_radius 14.673       nladders 37 sensor_radius 15.0846       nladders 38 sensor_radius 15.4963       nladders 39 sensor_radius 15.9079       nladders 40 sensor_radius 16.3196       nladders 41 sensor_radius 16.7312       nladders 42 sensor_radius 17.1429  Ladder type 1 ladder_rphi 3.8 clearance rphi 0.0365
      nladders 11 sensor_radius 6.56998       nladders 12 sensor_radius 7.18058       nladders 13 sensor_radius 7.79117       nladders 14 sensor_radius 8.40177       nladders 15 sensor_radius 9.01237       <======= (macro: 8.987)
      nladders 16 sensor_radius 9.62297       nladders 17 sensor_radius 10.2336       nladders 18 sensor_radius 10.8442       <======= (macro: 10.835)       nladders 19 sensor_radius 11.4548       nladders 20 sensor_radius 12.0654       nladders 21 sensor_radius 12.676         <======= (macro: 12.676)       nladders 22 sensor_radius 13.2866       nladders 23 sensor_radius 13.8972       nladders 24 sensor_radius 14.5078       nladders 25 sensor_radius 15.1183       nladders 26 sensor_radius 15.7289       nladders 27 sensor_radius 16.3395       nladders 28 sensor_radius 16.9501       nladders 29 sensor_radius 17.5607       nladders 30 sensor_radius 18.1713       nladders 31 sensor_radius 18.7819       nladders 32 sensor_radius 19.3925

Note that these are the radii that should be used for the inner sublayer of an overlapping pair of sublayers. The second overlapping layer should have the same number of ladders, and a radius larger by about 0.6 to 0.5 cm (decreasing a little as the layer radii increase).

Cheers

Tony

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