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We improved the accuracy in the K extrapolation from one emisphere to the other. Kaon back pointing. The presence of a big De/dx tail ( or of a bad reconstructed momentum ) in the “handle” is signalled by a big impact parameter of the handle track when extrapolated to the IP.
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We improved the accuracy in the K extrapolation from one emisphere to the other Kaon back pointing The presence of a big De/dx tail ( or of a bad reconstructed momentum ) in the “handle” is signalled by a big impact parameter of the handle track when extrapolated to the IP Big Landau tail DE/DX on DC wall “handle” K Wrong momentum assigned to the other K Wrong curvature reconstructed
K back pointing improvement |Dpt| f vs DR12 We use a cut on the radial and longitudinal distance of the K track from IP to recover a better resolution. To test it on data we plot the f momentum reconstructed from a couple of K versus the Kaons closest approach distance in r and z plane |Dpz| f vs DZ12 Dpf = pK2+ pK1 - pboost
Dpf resolution improvement (Dpx)f No sel on K PCA (Dpx)f Sel on K PCA: Rmax = 1.5 cm Zmax = 2.0 cm
Dpf resolution improvement 2 (Dpz)f No sel on K PCA (Dpz)f Sel on K PCA: Rmax = 1.5 cm Zmax = 2.0 cm
K streaming vs dedx The aim is to modify the old algo 3 selection. This selection basically asks for a Kaon with right momentum and narrow PCA to IP. The background veto relies on raw hit hinfo and is not effective. Algo 3 is the most populated of the KPM stream We try to use the dedx info of the algo 3 Kaons to reject the background .. 2x2 sample #ADC sample 3x3 sample
K streaming vs dedx 2 We compare the truncated mean for the algo 3 kaons (black) with that of the Kaons from algo 3 X tag (red) . The background pions are clearly visible ALGO 3 ALGO 3 and TAG