h1. 2017-12-06-emittance

Emittance paper

Present:

* Ken Long

* Chris Hunt

* Victoria Blackmore

* Chris Rogers

We started working our way through the emittance paper

* KL noted that it's time to standardise the cuts

* CR noted need to remove "0" space points line from the TOF "number of space points per trigger" plot (*Action VB*)

* CR noted the tracker butterfly as a possible aperture cut (*Action VB*)

* Discussed handling of low pt tracks in TKU recon

* CH described the track fit algorithm using TOF01 as a seed and he has a preliminary code; CR notes that this comes before global recon; so diffuser cannot be managed well; CR notes that multiple/deficient space points are not well-handled; this is all okay as it is consistent with VB cuts. Agreed that CH will pass preliminary reconstructed datasets to VB for analysis (*Action CH*) prior to code release in mid-December

* Discussed handling of field/momentum scale

** KL: the hall probe calibration was done very carefully; so we believe the field measurement; the position has greater uncertainty; will be addressed during decommissioning phase

** Plan to scale the tracker field to the hall probes and redo the reconstruction; assume that this is sufficient (*Action CH/DR*)

* Discussed handling of tracker chi2

** CR: check the straight tracks MC vs data; that validates the scattering model and hardware construction (Action CH)

** Doesn't validate the field model or the energy loss

** Then we move on to the helix; this is indicative of the field and energy loss

** CH notes that he does see a difference between different energy loss models

** Investigate different tracker alignments and field models

** Note we still have to check the dead channel map is properly simulated

* Discussed discrepancy between MC momentum and tracker momentum

** VB: Reweight based on momentum measured in TOF using Rayner (*Action VB*)

Note that still need quantitative estimate of the uncertainty involved in the reconstruction (*Action VB*)

Reminder for referee's meeting on Monday 16th January