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