Jean Favier OPERA Meeting Ankara 3/04/09 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 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 Residuals Fog=0 0 mrad100 mrad 200 mrad 300 mrad 400 mrad500 mrad 600 mrad

Jean Favier OPERA Meeting Ankara 3/04/09 6 Residuals fog=8 0 mrad 100 mrad 200 mrad300 mrad 400 mrad500 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 8

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  slope x,  slope y  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

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

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Jean Favier OPERA Meeting Ankara 3/04/09 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 1basis

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Jean Favier OPERA Meeting Ankara 3/04/09 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 0 mrad 400 mrad

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

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

Jean Favier OPERA Meeting Ankara 3/04/09 24 Compton background ( preliminary)  Hall C radio-activity is installed in GEANT3 (Borexino measurements)  gammas cross 1 m 2 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-tracks - 2 Compton micro-tracks in each layer 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 cm 2 ) 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 ?