Comparison of TPC super-sectors alignments
Updated hybrid alignment: Alex's procedure on top of Yuri's latest alignment.
Hybrid Alignment I is HFT to constrain the gamma rotataions + Yuri's August alignment (Timestamp: 20140101.001112 ) to constrain alpha and beta.
Hybrid Alignment II is HFT to constrain the gamma rotataions + Yuri's latest alignment (Timestamp: 20140101.001454) to constrain alpha and beta.
http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/res_Y.RFF2.20140103.010000.to.RFF2.20140105.000100.png
http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/res_Z.RFF2.20140103.010000.to.RFF2.20140105.000100.png
Xin's cosmics tracklets DCA using the Hybrid II set is available at the link below. The DCA constant term is down to 300-400μm now.
http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/cosmics_tracklets_DCA.RFF2.20140105.000100.png
Comparsion of Hybrid Alignment II to Yuri's latest alignment (Timestamp: 20140101.001454):
http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/res_X.RFF2.20140104.000001.to.RFF2.20140105.000100.png
http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/res_Y.RFF2.20140104.000001.to.RFF2.20140105.000100.png
http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/res_Z.RFF2.20140104.000001.to.RFF2.20140105.000100.png
Comparison of residuals along Z from different run periods (using alignment TimeStamp 20140101.001112 and old HFT-TPC alignment):
http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/res_Z.PXL.RFF2.days050-051.days091-103.png
Observations:
1- Several sectors have sizable improvements, e.g. sector 7 along X.
2- Some of the sectors residuals shifted within PXL/IST systematic due to finite resolution, e.g. sector 11 along X.
3- Some sectors are worse in Hybrid II in one transverse direction and bettet in the other, e.g. sector 3 is better in Hybrid II along X and worse along Y.
4- The constant term of the tracklets DCA is down to 300-400μm.
5- Residuals along Z vary vs. run period. It is likely that this is due to DV mis-calibration.
The new TpcSuperSectorPositionB table can be found at the link below:
http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/TpcSuperSectorPositionB.20140105.000100.C
1. Low Luminosity AuAu:
Alex's alignment AuAu (Red) to Cosmics (Blue):
http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/res_X.RFF2.20140103.010000.to.AuAu.20140103.010000.png
http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/res_Y.RFF2.20140103.010000.to.AuAu.20140103.010000.png
Yuri's latest AuAu (Red) to Cosmics (Blue):
http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/res_X.RFF2.20140104.000001.to.AuAu.20140104.000001.png
http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/res_Y.RFF2.20140104.000001.to.AuAu.20140104.000001.png
2. Updated hybrid alignment: Alex's procedure on top of Yuri's latest. New parameters from Alex are ready, he reports "I checked the chi2 only for a few sectors. Looks like that there is some little improvement for a few but other look worse. Mustafa, please check with your QA plots which sectors have finally improved. The chi2 is not always the best variable to check the quality". We are working on incorporating them with all the other tranformations.
3. FF:
Alex's alignment FF (Red) to RFF (Blue):
http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/res_X.RFF2.20140103.010000.to.FF2.20140103.010000.png
http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/res_Y.RFF2.20140103.010000.to.FF2.20140103.010000.png
Yuri's alignment FF (Red) to RFF (Blue):
http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/res_X.RFF2.20140104.000001.to.FF2.20140104.000001.png
http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/res_Y.RFF2.20140104.000001.to.FF2.20140104.000001.png
So far we have three sets of parameters:
II. Alignment using HFT, from here on called Alex alignment in this document.
III. Improved alignment from Yuri. Timestamp: 20140101.001454. From here on called Yuri's latest alignment in this document.
I produced cosmics (RFF) productions sets with different alignment sets for comparison.
Plots below are to compare the residuals of TPC tracks projections on the HFT layers.
Left column are residuals on PXL, right column are residuals on IST.
Xin Dong has also provided the DCA between two cosmics tracklets in different productions.
/star/institutions/lbl_prod/
Plots, this alignment (Blue) to alignment from August (Red):
http://www.star.bnl.gov/
http://www.star.bnl.gov/
http://www.star.bnl.gov/
Tracklets DCA: http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/DcaDiff_Pt_alex_0114.png
/star/institutions/lbl_prod/
Plots, this alignment (Blue) to alignment from August (Red):
Tracklets DCA: http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/DcaDiff_Pt_yuriJan_0114.png
- Alex's alignment gives residuals within ~200μm while Yuri's latest alignment gives ~400μm residuals.
- DCA between tracklets is ~0.5mm in Alex's alignment. ~0.8-1.2mm using Yuri's latest.
- Alex's alignment is achieved by rotatating the SuperSectors around z (γ rotation) while α and β are fixed to those from Yuri's August alignment. Yuri achieves his alignment by applying only α and β rotations. Both alignments apply translations on sectors. Alignemnet parameters:
Alex's: http://www.star.bnl.gov/protected/heavy/mstftsm/tpc/alignment-using-hft/comparison-of-different-alignments/TpcSuperSectorPositionB.20140103.000002.C
Note: Alex does the alignment in global coordinates, I transform those to local supersector coordinates. So the α and β roations could be slightly different than original ones from Yuri due to the non-orthognality of different coordinates systems.
The residuals along Z are different between alignments. There is a correlation between super sectors rotations and Z shifts. There is also a possible bias due to T0 mis-calibaration.
To check this I looked at the residuals with only new HFT-TPC alignment with old alignment from Yuri for the supersectors.
/star/institutions/lbl_prod/
Plots, this alignment (Blue) to alignment from August (Red):
Hao's presentation can be found at:
http://www.star.bnl.gov/protected/heavy/qiuh/TPC/spaceCharge/SpaceChargeAndAlignmentCheckRun14.pdf
Xin Dong's study of impact of TPC Super Sectors misalignment on TPC tracks projections on HFT:
https://drupal.star.bnl.gov/STAR/blog/dongx/impact-tpc-mis-alignment-hft-tracking
- mstftsm's blog
- Login or register to post comments