1 Status of RICH Calibration with: Andrew Powell RICH Alignment & Calibration Meeting, 15 th January 2009 D*    D     p  K s  

2 MC-Free RICH Calibration Isolating pure samples of charged tracks (  ±, K ±, p ±, …) independently of RICH information is vital for the following: Monitoring the performance of the RICH during data tacking Calibrating PID  Log-likelihoods for variety of physics analyses e.g. B ±  h + h - The ‘golden’ kinematics of the decay D *  D(K  )  enable clean samples of  ±, K ± tracks be isolated with momenta GeV (approx. dynamic range of RICH) Furthermore, 2-body decays of neutral vector-particles (e.g. , K S ) are also highly promising. The kinematics of the decay products are governed by the Podolanski-Armenteros relations. Exploiting these constraints enables such decays to be reconstructed with high purity (See Chris’ talk here). Interesting modes are therefore:here   p  K S  

3 I’ve now taken over responsibility from Raluca Mureşan (who is now at EPFL) Have familiarised myself with Raluca’s D * selection code over the last few months (many thanks to Raluca for the help!) Have run the code (DaVinci v19r14) Can generate my own plots Have also started to develop a   p  selection. Preliminary studies by Bogdan Popovici (see here) looked very encouraging, and I will continue where he left off.here Natural to extend the  work to encompass the decay K S  . Recent Developments

4 D * Selection As mentioned, Raluca has taught me how to run her code (plots below). Next step is to re-write the code in DaVinci v22r0, and interface it with Chris’ monitoring tool for both online and offline monitoring.

5  & K s Selections Plots - C Jones, LHCb Week Jan ‘08 For a full analysis (binning in p and pt), the D* calibration will require O (2 fb -1 ). Only ~ hundreds events / 10 7 min bias. Very appealing with early data then will be studies with  and K s – with 10 7 min. bias expect: ~ 45k   p  ~320k K S   Applying AP kinematic cuts (left) provides very clean samples. Currently in the early stages of writing selection algorithms for both decays

6  Selection Particularly interesting is the proton efficiency distribution…. Plots - B Popovici, LHCb Week April ‘08 Calibration Sample MC truth Signal Sample The proton truth distribution is essentially flat across the full momentum range. This is useful for the monitoring since any deviations will be easy to identify.

7 Summary At the early stages of picking up Raluca’s D* calibration work. Following Raluca’s help, I can run the code and generate the efficiency and purity plots. Currently re-writing the code to operate in the newest release of DaVinci (v22r0) and then work with Chris/Ulrich to interface the algorithm with the monitoring framework. Also developing selections for the  and K s decays at the same time. Expected to be very useful with early data. Apologies for the lack of progress so far, but please watch this space…