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1 Simulation Status/Plans Malcolm Ellis Sci Fi Tracker Meeting Imperial College, 10 th September 2004

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2 Outline Status at Osaka meeting Unresolved issues: –P T, P z resolution –Emittance calculation –Correct beam and Background Aims by RAL meeting: –Correct beam (G4BeamLine) –New RF background (Rikard) –New track model? –Resolutions –Emittance calculation

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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).

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4 Unresolved Issues Some concerns over P T resolution compared to expectations based on “back of the envelope” type calculations. P z resolution (RMS of P Z resolution not less than 10% of the RMS of the true distribution) and hence t’. Still hadn’t made an actual emittance calculation, so couldn’t show emittance resolution. Default G4MICE beam isn’t terribly realistic, and the RF background simulation has since been improved.

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5 Aims by RAL Meeting Use a more correct beam – G4BeamLine June04 Use a better RF background simulation (Rikard) New track model? Final resolutions (hopefully show better than 10% resolutions in all parameters) Demonstrate calculation of emittance, and of course the resolution!

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6 G4BeamLine Beam 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...

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7 Pz Resolution (G4MICE) At the Osaka meeting, resolution shown was 3 MeV/c The RMS of the P Z distribution was 5.3 MeV/c – “resolution” is therefore ~60% - not very good...

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8 P Z from G4BeamLine RMS of the G4BL P Z distribution is 43.1 MeV/c The “resolution” is therefore now 7.0%! P Z resolution is now acceptable without changing the reconstruction code...

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9 t’ Resolution Because t’ = E/P Z, the same effect as seen with the P Z 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%

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10 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 Yagmur.

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11 New Track Model At Osaka, discussion about the pattern recognition efficiency as a function of P T resulted in the conclusion that a P T -insensitive track model is needed in order to have high efficiency at ultra-low P T. Ken has defined such a model, and done the maths, and produced an Excel/VB based implementation to test it. Plan is to make a C++ version under the current G4MICE framework and use it in the pattern recognition. However, is it really needed?

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12 P T Distribution from G4BL 10 tracks out of 32k with very low P T Transition from “curved” to “straight” happens at about P T = 0.5 MeV/c Do we care about 0.03% loss of tracks in a 0.1% experiment?

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13 Emittance Calculation Chris has developed emittance calculation code (see his talk), 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.

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14 Conclusions We are almost there. The two principle objections at Osaka should be answered by RAL: 1.t’ resolution – broader beam from G4BL fixes that for us 2.calculation of emittance and use of better beam and RF background simulation are the remaining hurdles.

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