2018-10-10 workshop

Agenda linked to CM52 meeting page


  1. Resolution/bias
    • Requires field integration to improve bias; Chris H seems resigned to it.
  2. Dead channels see below
    • Dead channel mapper is probably busted -> Tom L?
  3. Glue density measurement
    • ACTION: To do - find summer student/etc?
  4. Tracker efficiency improvement
    • Tom is making plots of digit distributions in each plane which don't form a track.
    • Chris H has been playing with efficiency;
      • TKU 98.8 % efficiency before fixes
      • TKD 96.6 % efficiency; compared with table 18 and 20 from Emittance Evolution note; tables are consistent with ~ 97 % efficiency
      • Low pt tracks are likely to be reconstructed poorly
    • NPE cut - throwing out "too early", do it at space point? Looks like where we are is okay
    • ACTION: Durga and Chris H to sit together and look at how to modify the recon to analyse the events that are not reconstructed
    • ACTION: Durga to check the bad channel loading
      • Chris R showed plots of doublets/triplets which are used during track finding; MC vs data; it looked reasonably good i.e. dead channels map appears to work reasonably well
    • ACTION: Chris H to look at noise
    • ACTION: Chris R to look into the clusters thing - where are they going/coming from


  • Viktor has dug down to look through the TOF calibrations; but missing calibration runs from < middle of summer
    • Calibration data is on the GRID somewhere
  • For more recent data; need lots of reconstructed data with new calibration constants; ACTION: Durga will turn it around
  • Paul K is going to do efficiency as a function of time; couple of weeks work

Emittance growth

  • Paul J is trying to understand discrepancy in measured phase advance and larmor angle
    • Use measured ensemble beta function and alpha function; deduce measured single particle phase advance and Larmor angle
    • It's a bit weird to look at ensemble properties mixed with single particle properties
    • Sources of uncertainty in particular MC vs data:
      • magnet misalignment, windows and apertures, x-y asymmetry of beam
  • Paul J is doing Hamiltonian in solenoid and emittance growth
    • Lie algebra looks challenging; pointed Paul at COSY


  • Tanaz will do reverse emittance exchange; focus for the thesis
  • Tanaz has looked at the data vs MC truth; low pt hole is still an issue
  • Reverse emittance exchange uses MICE data directly with natural dispersion in the beam
    • Makes longitudinal heating and enhanced transverse cooling
  • Emittance exchange makes longitudinal cooling and less/no transverse cooling
    • Emittance exchange requires reweighting the beam; struggled to reweight from lower dimension to higher dimension
      Steps in analysis
  • Sample selection follows standard cuts except no chi2 cuts yet; TOF; momentum cuts us and ds (but momentum cut is wider than "standard" analysis); tracker fiducial cut
  • Use transverse position and momentum to calculate KDE algorithm to generate density and
Outstanding actions
  • Select for a dispersive beam
    • Chris H looked at using Voronoi density estimators; needs to be adapted for use at global track stations
    • Tanaz looked at using KDE density estimators; Tanaz is tidying things up a bit
    • Need selection at the absorber; will be a standalone analysis tool
    • ACTION: Craig to pick up some bits of code
  • Try to split the transverse 4d emittance into two 2d emittances; look at evolution of the uncoupled emittances and demonstrate wedge plane is more significant
    • Need to demonstrate that we understand Larmor angle between absorber and TKD

Emittance Evolution

  • Introduce MC truth versus reconstructed early; talk about how the simulation was done
  • Describe TKU and TKD; define reference surface
  • Plot ADCs of two SP TOF events
  • Compare TOF-seeded tracker tracks and tracker tracks
  • Say a bit more about how the efficiency plots were generated
  • Francois - working on systems paper; started working yesterday on implementing
    the TOF reconstruction into MAUS; ETA end of next week.
    Comments on paper:
  • Eqn 1/2 units are wrong
  • Eqn 7 "when A_i is \epsilon_n"
  • Statistical uncertainty -> check

Emittance Measurement

  • Title: "Precise measurement..." may be better than "Direct measurement..."
  • Fig. 7 plots are a little small