Simulation Status and Plans

1
Simulation Status and Plans

• Malcolm Ellis
• MICE-UK Meeting
• RAL, 15th September 2004

2
Outline

• Status at Osaka meeting
• Unresolved issues
• PT, Pz resolution
• Emittance calculation
• Correct beam and Background
• Aims by RAL meeting
• Correct beam (G4BeamLine - Kenny)
• New RF background (Rikard)
• Resolutions
• Emittance calculation (Chris)

3
Status at Osaka Meeting

• Pattern recognition and reconstruction had been
  improved in a number of areas.
• In particular
• Improved dE/dx model used in track parameter
  propagation.
• Better seed parameters to track fit.
• Moving towards removal of MINUIT fit.
• Increased efficiency in CPU and memory use per
  event (important for high RF background rates).

4
Unresolved Issues

• Some concerns over PT resolution compared to
  expectations based on back of the envelope type
  calculations.
• Pz resolution (RMS of PZ resolution not less than
  10 of the RMS of the true distribution) and
  hence t.
• Still hadnt made an actual emittance
  calculation, so couldnt show emittance
  resolution.
• Default G4MICE beam isnt terribly realistic, and
  the RF background simulation has since been
  improved.

5
Aims by RAL Meeting

• Use a more correct beam G4BeamLine June04
  (Kenny)
• Use a better RF background simulation (Rikard)
• Final resolutions (hopefully show better than 10
  resolutions in all parameters)
• Demonstrate calculation of emittance, and of
  course the resolution! (Chris)

6
G4BeamLine Beam (Kenny)

• During August, Kenny made a run of G4BeamLine
  using the June04 setup, and produced
  approximately 15k muons going through the
  channel.
• The output of G4BL can be read into G4MICE.
• In order to get sufficient statistics, we are
  going to need to use the distribution from G4BL
  as the input for a generator in G4MICE (rather
  than attempting to produce 1,000,000 muons in
  G4BL!) not sure yet exactly how to achieve
  this...

7
Can G4MICE Cool?

• At the moment, the description of the material in
  the absorbers and windows is being improved by
  Rikard, however the RF side of things still needs
  a lot of work.
• Chris will be going to Chicago to work with
  Yagmur for a week or two (hopefully before the
  RAL meeting) in order to work with him on the
  BeamTools part of G4MICE and thus get the G4MICE
  channel to cool.
• Once the simulation cools a beam, the Analysis
  code Chris is working on (see later) should be
  able to measure it!

8
Pz Resolution (G4MICE)

• At the Osaka meeting, resolution shown was 3
  MeV/c
• The RMS of the PZ distribution was 5.3 MeV/c
  resolution is therefore 60 - not very good...

9
PZ from G4BeamLine

• RMS of the G4BL PZ distribution is 43.1 MeV/c
• The resolution is therefore now 7.0!
• PZ resolution is now acceptable without changing
  the reconstruction code...

10
t Resolution

• Because t E/PZ, the same effect as seen with
  the PZ resolution happens with t
• At Osaka, the resolution was 5.62E-3 / 2.45E-2
  23.
• The RMS of the t distribution has increased now
  to 1.58E-1, therefore the resolution is now 3.6

11
RF Background Simulation

• At NuFact/Osaka MICE meeting, Rikard presented
  the latest RF background simulation.
• Currently awaiting the resolution of a few
  technical issues, then it will be commited to the
  G4MICE repository.
• Talk to be given at next Video Conference. Once
  simulation is approved, it will be used for all
  results for the RAL meeting.
• There is also a better description of the
  material in the cooling channel coming from
  Rikard and Yagmur.

12
Emittance Calculation

• Chris has developed emittance calculation code
  which will be used to calculate the true (i.e.
  Monte Carlo) and reconstructed emittances, and
  make a study of emittance resolution.
• We will be unable to generate many 1M event runs
  (each of which in theory produce one measurement
  of true and reconstructed emittance), so will
  look at different sized subsets of the data that
  we can produce, and study the emittance
  resolution as a function of statistics and
  extrapolate to the nominal MICE case.

13
Analysis Code (Chris)

• Analysis is controlled by a datacard like file
  which controls 4 aspects
• What to calculate (phase space, trace space, 2D,
  4D, 6D, etc...)
• What to use (virtual planes, MC truth,
  reconstructed results, input beam)
• What cuts to apply (e.g. select a given momentum
  in a virtual plane, or energy from the
  reconstruction,etc...)
• Reweighting on a given variable to make the
  distribution gaussian.

14
Emittance Calculation
Hot off the Press Comparison of 2D Emittance
calculated from virtual plane downstream and from
the reconstructed track in the downstream
tracker... Virtual Plane ltEgt 2D Em 226.416
1054.57 Reconstructed Tracks ltEgt 2D Em
242.637 1080.56
15
Conclusions

• We are almost there.
• The two principle objections at Osaka should be
  answered by RAL
• t resolution broader beam from G4BL fixes that
  for us
• calculation of emittance and use of better beam
  and RF background simulation are the remaining
  hurdles.