4 Method, page #1 1.Write a document explaining what to do and why Not in the document = not on the table. 2.Simulate beams of 10k events, wide distributions. 3.Use those to find useful variables for PID. Find combinations of detectors, such that given A, expect B. When finished, there should be no covariance between variables. 4.Make fits for all expected values, and create “discrepancy variables” 1-expected/measured. Zero means very muon like. 5.Run 120k events of muons per experimental scenario. ~ 2Gb of data per file 6.For every such scenario, also run 120k muons with 40 ns lifetime to generate background. Muons not decayed at TOF2 are filtered out of analysis.
5 Method, page #2 7.Digitize every simulated beam. 8.Convert to ROOT trees, and tag good/bad event. 9.For every scenario, merge the muon sample with the background sample. 10.Train a Neural Net on the half of the merged & filtered sample (training sample). 11.Using the weights acquired by Neural Net, assign a weight all other events (the test sample). 12.Make cut on the weight such that signal efficiency is 99.90% 13.The same cut gives background rejection, and thus purity after PID.
7 Stage 6 – general setup All is MICE default. Exceptions: –Empty absorbers. –RF cavities turned off.
8 Stage 6 - smearing Since no reconstruction application in G4MICE yet, used gaussian smearing of t & p. –Added 70 ps resolution to time of flight. –Added smearing to trackers: px = py = 2.0 MeV/c, pz =0.209 px p z /p t √2 x = y = 0.5 mm Reproduces approximately M. Ellis LBNL’05 As with stage 1, simple cuts do no longer help when adding smearing to trackers & tof. –Fitting with a neural net.
9 Stage 6 – networks used 140 MeV/c –9:5:2:1 architecture –Using barycenterDiscrepancy. 170, 200,240 MeV/c & TURTLE –8:7:1 architecture –barycenterDiscrepancy does more damage than help, and is not included as input.
10 Stage 6 - purity In stage 6, objective is to measure emittance to high precision. –Requires high purity from background. Requirement: –Signal efficiency = 99.90%. –Purity = 99.80%. Safety margin: –3 times expected background. At non flip magnetic field mode, expect much more background since fewer background tracks lost at absorbers. –Safety margin can be expressed as purity = 99.93% Initial mom [MeV/c] Input purity Req. BG rej. (purity 99.80%) Safety BG rej. (purity 99.93%) >56.2> >47.4> >43.4> >20.4>73.5 Turtle99.58>52.7>84.2 Not meeting req.Meeting basic req.Meeting safety req.
15 Correctly ID 99.9% of signal, correctly ID 87.6% of background
20 Stage 6 – TURTLE beam A TURTLE beam with the design presented at RAL Oct’05 is the most realistic beam available. –Requires a 7.6 mm diffuser after TOF1. P z,TOF1 = 236 ± 26 MeV/c, non-Gaussian. In order to make G4MICE place the diffuser, I had to place it at z=-6078 mm. –It should be at z= mm. –Chris Rogers says: Z=-6010mm -> T Z=-6080mm -> T “…should be okay for PID stuff, but may I still need to fix it for beam optics stuff.”
21 Stage 6 – energy loss in diffuser
22 Results - Stage 6, TURTLE Not finished yet –Everything is simulated; simulation files are being digitized right now.
23 Results – Stage 6, summary BG rejection Initial mom. No cal., with TOF KL, no TOF SW, no TOF KL, with TOF SW, with TOF 140±14 MeV/c 47.8%56.2%79.5%58.2%79.5% 170±17 MeV/c 54.1%48.8%56.4%59.0%67.8% 200±20 MeV/c 59.0%57.3%74.2%79.4%87.6% 240±24 MeV/c 64.5%65.0%91.4%80.0%92.2% TURTLE Not meeting req.Meeting basic req.Meeting safety req.
24 Requirements for CKOV2 In order for an extra detector to be useful, it should have a background rejection capability (in order to meet safety requirement) as a function of input purity and previous background rejection. –While loosing no signal events. –Assuming BG rejection of CKOV2 not correlated to previous BG rejection:
25 p z,TOF1 p z,CKOV2 Input purity Rejected by SW Min req. rej by CKOV 140 ± 14 MeV/c 113 ± 23 MeV/c 99.54%79.5%>29% 170 ± 17 MeV/c 148 ± 22 MeV/c 99.62%67.8%>46% 200 ± 20 MeV/c 178 ± 26 MeV/c 99.60%87.6%0% Not needed 240 ± 24 MeV/c 212 ± 38 MeV/c 99.75%92.2%0% Not needed TURTLE200 ± 30 MeV/c 99.58% Requirements for CKOV2, table
26 Summary Hardest momentum for PID is p z,TOF1 170 MeV/c. Sandwich design has better performance than KLOE Light. –Best is trackers + TOFs + Sandwich calorimeter. –It is fairly easy to meet basic purity requirement. –At medium and high momenta it is possible to meet safety requirements. CKOV2 –Not needed at high momentum. (p z,CKOV2 ≥180 MeV/c) –Must be able to reject 30-50% of background at 100% signal efficiency for lower momentum.
27 Appendix Here are slides of variables used for PID, but where not presented.