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HBD analysis update

HBD analysis update. I. Ravinovich for the HBD analysis team. Electron analysis. RB runs # 237092 & 237095 with +100V, ~13.7M mb events, after +/- 20 cm vertex cut ~9.3M mb events Used “peripheral” events with < 50 DC+PC1 tracks in both arms High quality tracks 31 or 63

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HBD analysis update

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  1. HBD analysis update I. Ravinovich for the HBD analysis team I. Ravinovich

  2. Electron analysis • RB runs # 237092 & 237095 with +100V, ~13.7M mb events, after +/- 20 cm vertex cut ~9.3M mb events • Used “peripheral” events with < 50 DC+PC1 tracks in both arms • High quality tracks 31 or 63 • 3s matching cuts to EMC • n0 > 2, disp < 5, c2/npe < 10 • 0.6 < E/p < 1.2 • Number of electrons/event in Central Arms: Ne(East)=0.044, Ne(West)=0.021 ( will obtain soon w/ HBD.W in from earlier runs) • HBD analysis steps: • read all HBD pads in the event • apply gain equilibration • build the clusters with A > 10 ADC counts • project the electron track to HBD and look for a closest pad with A > 50 ADC counts • Apply the matching cuts for corresponding cluster in |DZ| < 2 cm and |Df| < 30 mrad I. Ravinovich

  3. Relative eID efficiency in HBD is obtained by varying a charge threshold of the closest (matched) pad I. Ravinovich

  4. Looking at e+e- pairs in the East arm • In order to assess the HBD rejection one has to plot the mass spectrum in the East Arm only for the electrons that point to the working modules in the HBD.E which covers only 5/8 of the acceptance. Will be done soon. • Pulse height spectrum for all pairs indicates some double structure with the ratio ~1:2. These include: “close” pairs – electron and positron match to the same cluster in HBD. In principle such clusters should have double electron amplitude; “open” pairs – electron and positron match to separate clusters, should have the charge for a single electron; • Looking only at “close” pairs we still see some double structure. This is probably due to the conversions in CF4. We will soon get from MC the spectrum for such conversions running photons through HBD w/o beam pipe and entrance window. • In order to go one (or more) step further we have asked Carla to produce ~150M events from +100V. Anne has started the production in 1008. Time estimate: a couple of weeks. • It is also extremely important to analyze the same amount of events from nominal HV data set in order to confirm (or not) that charge scales with gain. In other words that single electron collection efficiency is the same in both cases I. Ravinovich

  5. As usual: GEM production • 25 GEMs have been framed including 6 from the new batch # 9. • 16 GEMs passed all tests and are in the DB: 8 standard and 8 Au plated. • We need 18 more GEMs passed all tests in order to fill the second shipment. I. Ravinovich

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