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Bug #1855

Tracker Recon Straight Tracks Alignment

Added by Rogers, Chris about 6 years ago. Updated about 6 years ago.

Status:
Open
Priority:
Normal
Assignee:
Category:
Tracker
Target version:
-
Start date:
08 June 2016
Due date:
% Done:

0%

Estimated time:
Workflow:
New Issue

Description

Looks like there is an incorrect transformation in the tracker recon such that straight tracks are still not reconstructed correctly


Files

residual_xp.png (10.6 KB) residual_xp.png Rogers, Chris, 08 June 2016 06:58
residual_yp.png (10.7 KB) residual_yp.png Rogers, Chris, 08 June 2016 06:59
virtual_hit_xp_vs_residual_xp.png (7.84 KB) virtual_hit_xp_vs_residual_xp.png Rogers, Chris, 08 June 2016 06:59
virtual_hit_yp_vs_residual_yp.png (6.95 KB) virtual_hit_yp_vs_residual_yp.png Rogers, Chris, 08 June 2016 06:59
test_beam_alignment.tar.gz (3.31 MB) test_beam_alignment.tar.gz Rogers, Chris, 08 June 2016 06:59
residual_xp-v2.png (9.4 KB) residual_xp-v2.png Rogers, Chris, 08 June 2016 14:21
test_beam_alignment-v2.tar.gz (30 MB) test_beam_alignment-v2.tar.gz Rogers, Chris, 08 June 2016 14:21
#1

Updated by Rogers, Chris about 6 years ago

I ran a simulation with quite a narrow beam, scattering switched off; (and in fact too high energy, not that it should matter). I used the 7417 geometry with all of the fields (including quads) set to 0. I plotted the difference between truth and recon. I can see a clear misalignment at the few millirad level in dx/dz and dy/dz residuals. I presume that the correction to rotations etc is not applied correctly.

I attach residual plots (virtual hit - sf hit).

#2

Updated by Rogers, Chris about 6 years ago

Bump

#3

Updated by Hunt, Christopher about 6 years ago

I think this was a little bug left over from the last refit of Kalman, in that the CMM measurements weren't correctly used in the reconstruction.
It should be fixed in the next release due very soon I believe.

#4

Updated by Rogers, Chris about 6 years ago

I am using MAUS trunk...

#5

Updated by Rogers, Chris about 6 years ago

Hang on, let me check that I am up to date and I will post new results.

#6

Updated by Rogers, Chris about 6 years ago

I am using:

 $> bzr revision-info 
1105 phuccj@gmail.com-20160607075611-09902p7yrnu6gsqj
 $> bzr info
Checkout (format: 2a)
Location:
       checkout root: .
  checkout of branch: bzr+ssh://bazaar.launchpad.net/+branch/maus/merge/

I made a few changes:

  • Did a bzr update; scons
  • Made the input beam distribution a bit bigger, in case I was getting bias from "unlucky" combination of fibres
  • Made the beam energy 200 MeV, not that it should matter
  • downloaded the latest 7417 geometry, as of this morning, leaving quads on full current (i.e. not touched the geometry)

I still see a 1.5 mrad bias in dx/dz; this makes 4.5 mm over 3000 mm distance between the trackers, which is obviously significant. Plot attached as residual_xp-v2.png

#7

Updated by Hunt, Christopher about 6 years ago

Thanks for finding this Chris.

I think I saw this before the last release, Though I thought that I had fixed it before I got distracted by other things. But apparently I missed something.

Working on it at the moment.

#8

Updated by Hunt, Christopher about 6 years ago

Do you see the discrepancy in the upstream tracker or the downstream tracker? Or both?

#9

Updated by Rogers, Chris about 6 years ago

Try unpacking the tar ball and see whether I did something stupid. But it is upstream tracker (I didn't look at downstream yet).

#10

Updated by Rajaram, Durga about 6 years ago

Any news on this - Chris H?

#11

Updated by Hunt, Christopher about 6 years ago

I think I have a fix, I just need to finish testing it and push it to LP.

Unfortunately we're going through the process of swapping disk servers around at IC at the moment, hopefully I'll have myself back to normal tomorrow. I'll let you/Adam know when its good to go.

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