Understanding the angle Phi conversion


In order to properly match reconstructed tracks with raw tracks coming from the CSCTF, understanding the conversion from bits to degrees is crucial.

The conversition was performed with the help of L1MuTriggerScales class. It seems that this class assign for each bit a step of 2.5 degrees. This step is by far more than what a single sector covers, therefore the conversion seems to be not the proper one. A sector covers a range more or less of 62 degrees. So given we have 32 bits available for the Phi record, it is plausible to hypothesize that the range is indeed 1.9 degrees.


In this section, I report some tests I performed to have a better insight. The match between the reconstructed muons and the CSCTF tracks is done using the eta, phi of the rechits and the eta, phi information from the CSCTF. The first series of plots is about the difference between the Phi from the rechit and the Phi coming out from the CSCTF, in the case of 2.5 and 1.9 degrees assigned to each bit:

- PINK: PhiRECO - PhiRAW [2.5 degrees step]
- RED: PhiRECO - PhiRAW [1.9 degrees step]

deltaPhi_25-chain.png deltaPhi_19-chain.png

  • Overlap and Zoom In of the two distributions:

deltaPhi-chain.png deltaPhi_Zm-chain.png

From the overlap of the two distributions, one can observe how using the 1.9 degrees step gives a better matching.
In fact, the pink distribution shows an asymmetry which I can explain by the fact that 2.5 degrees is a too big step and the PhiRaw is overestimated.

  • Scatter plots for the PhiRECO vs PhiRAW. Again, for both kind of steps:

Phi25vsPhiReco-chain.png Phi19vsPhiReco-chain.png

In conclusion, 1.9 degrees seems to be the proper step to use in the conversion.
Question : is then the eta step, since it is taken from the same L1MuTriggerScales class, the correct one?

I produced the scatter plot Delta Phi vs EtaRAW and then sampled along the EtaRAW :


- PhiRAW seems a bit underestimated w.r.t to the RecHit assignment
- As EtaRAW grows (in modulo), its resolution worsen

-- GianPieroDiGiovanni - 18 Nov 2008

Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng DPhivsEta_pfx-chain.png r2 r1 manage 6.3 K 2008-11-24 - 12:20 GianPieroDiGiovanni  
PNGpng Phi19vsPhiReco-chain.png r2 r1 manage 8.0 K 2008-11-24 - 12:48 GianPieroDiGiovanni  
PNGpng Phi25vsPhiReco-chain.png r2 r1 manage 8.3 K 2008-11-24 - 12:48 GianPieroDiGiovanni  
PNGpng deltaPhi-chain.png r2 r1 manage 7.1 K 2008-11-24 - 12:49 GianPieroDiGiovanni  
PNGpng deltaPhi_19-chain.png r2 r1 manage 6.7 K 2008-11-24 - 12:46 GianPieroDiGiovanni  
PNGpng deltaPhi_25-chain.png r2 r1 manage 7.0 K 2008-11-24 - 12:46 GianPieroDiGiovanni  
PNGpng deltaPhi_Zm-chain.png r2 r1 manage 6.4 K 2008-11-24 - 12:47 GianPieroDiGiovanni  
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Topic revision: r2 - 2008-11-24 - GianPieroDiGiovanni
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