Some ECC features studied with GenIma

1. Some ECC features studied with GenIma Efficiency with no fog Efficiencies with fog Micro-track number versus fog Distortions effects Sensitivity to grain density Compton or electrons background Neutrino events Jean Favier OPERA Meeting Ankara 3/04/09

2. Genima GEN : GEANT3 generation of - single track (1 single field 200x200 2 , double layer emulsion set-up) - or neutrino, showers events in a complete brick set-up. - The correct grain density is set by randomly eliminating some GEANT track hits to obtain the m.i.p density at : 34 grains/100) IMA: single “classico” FORTRAN program: - read GEANT hits - add background fog - constructs the 32 images of grains, fog,etc present in the 2 emulsion layers - clusterises the images pixels - finds micro-track - finds base-track Jean Favier OPERA Meeting Ankara 3/04/09

3. Fog generation Random generation; fog density from 0 to 30 grains/1000 3 • Clustering -Emulsion grain : 0.4  radius sphere -In input, pixels not saturated; then saturation to 256 above a threshold ( about 10 % of the saturated value); for layer 1 the threshold is 20 % lower to take account of light attenuation in emulsion ( att=300 micron)). Clusters of surface s  4 and s  64 pixels are eliminated No digital filter (coded but not used for timing reason…) Jean Favier OPERA Meeting Ankara 3/04/09

4. Micro-tracks reconstruction - Initialisation: 2 hits tracks are made with each cluster found in plane 1 to 7 associated with any cluster found in plane 10 to 16. - Then try to fish other hits in the rest of planes by using roads ; road width depends of the track angle. Fog makes difficult a good evaluation of the residual sigmas - Select tracks with  6 points and qui2 < 4.5 REMARK: for the same physical track, you can obtain more than one (ex 10) sligthly different micro-tracks. All are kept for base-tracks reconstruction Jean Favier OPERA Meeting Ankara 3/04/09

5. 0 mrad 100 mrad Residuals Fog=0 200 mrad 300 mrad 400 mrad 500 mrad 600 mrad Jean Favier OPERA Meeting Ankara 3/04/09

6. 100 mrad 0 mrad Residuals fog=8 200 mrad 300 mrad 400 mrad 500 mrad 600 mrad Jean Favier OPERA Meeting Ankara 3/04/09

7. b Widening of residuals when fog increases Jean Favier OPERA Meeting Ankara 3/04/09

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9. Not well adjusted parameters for sigmas variation with angle Jean Favier OPERA Meeting Ankara 3/04/09

10. Base-tracks reconstruction -Comparison in the midle plane of the intercepts and the angles of the two tried micro-tracks. x, y  S1 slopex, slopey  S2 S1=C/ (1-tg ) S2=D/ (1-tg ) - C= 3 micron - D=16 mrad Jean Favier OPERA Meeting Ankara 3/04/09

11. Base-track efficiency Fog=0 Jean Favier OPERA Meeting Ankara 3/04/09

12. How fog can influence efficiency ? - Fog effects will be higher at large angle where the sensible volume around the track is higher • infection of a good cluster: the resulting barycentre becomes out of association: the hits number can go down from 6 to 5 - Deformations of good clusters by a fog one can produce a deterioration of qui2 • Oppositely, on a 5 hits track, one fog cluster can, by luck, occupy the sixth rank, so the track will be accepted Jean Favier OPERA Meeting Ankara 3/04/09

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14. Base-track efficiency Fog effect Jean Favier OPERA Meeting Ankara 3/04/09

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16. Base-track efficiencies when fog increases Jean Favier OPERA Meeting Ankara 3/04/09

17. Distortion It is simulated by random rotation (0 to max) of the microtracks ,leaving fixed the intercept with the basis; we varied max from 0 to 40 mrad Emulsion layer 1 basis Jean Favier OPERA Meeting Ankara 3/04/09

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19. Micro-tracks number Jean Favier OPERA Meeting Ankara 3/04/09

20. Random micro and base tracks with fog 500 mrad cut 700mrad cut Jean Favier OPERA Meeting Ankara 3/04/09

21. Grain density fog=8 400 mrad 0 mrad Jean Favier OPERA Meeting Ankara 3/04/09

22. Nhit 5 Grain density Fog=0 (preliminary) Nhit 6 Jean Favier OPERA Meeting Ankara 3/04/09

23. Emulsion simulation Compton • 16 images Jean Favier OPERA Meeting Ankara 3/04/09

24. Compton background( preliminary) • Hall C radio-activity is installed in GEANT3 (Borexino measurements) • 1.5 108 gammas cross 1 m2 per day • This reduces to 6 gammas per day crossing our field of view. • In 1 years: 2000 crossing ( neglecting detector self-screening factor of 400 !!) produce: (based on 50 years stat) - 2 Compton micro-tracksin each layer - 0.6-1 have grains in both layers - but: base-track association efficiency 0.05/100! • This will result in much less Compton electron background than electron from lead beta-radioactivity inside detector.( see internal note J.F 07/10/03) Jean Favier OPERA Meeting Ankara 3/04/09

25. BRICK EVENT ( preliminary) Extension of set-up to a full brick; OK (in test) Scanning and reconstruction OK (in test) Actual time: 1hour (5600 cm2) for a tau-3h event Writes micro-tracks parameters ( or clusters ? Or both? ) towards FEDRA ? EMUREC ?(Amina) in progress…. Jean Favier OPERA Meeting Ankara 3/04/09

26. Tau 3 hadrons Full brick Base-tracks Jean Favier OPERA Meeting Ankara 3/04/09

27. Tau 3 hadrons 3cm Jean Favier OPERA Meeting Ankara 3/04/09

28. Electron 2 Gev Jean Favier OPERA Meeting Ankara 3/04/09

29. Conclusions • In simulation, no strong fog effect on efficiency. not simulated:the chemistry, stirring, etc of emulsion development! • Strong distortion effects • Grain density : not confortable • Compton not a problem inside detector; lead activity sould be dominant. Very low base-track efficiency for low energy electrons. • Soon: GENIMA neutrino events in Fedra ? Jean Favier OPERA Meeting Ankara 3/04/09