1 Status of RICH Calibration with: Andrew Powell RICH Alignment & Calibration Meeting, 15 th January 2009 D* D p K s

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Status of RICH Calibration with:

Andrew PowellAndrew PowellRICH Alignment & Calibration Meeting, 15RICH Alignment & Calibration Meeting, 15thth January January

20092009

• D*D• p

• Ks

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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 2-100 GeV (approx. dynamic range of RICH)

• Furthermore, 2-body decays of neutral vector-particles (e.g. , KS) 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:

• p• KS

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• 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.

• Natural to extend the work to encompass the decay KS .

Recent Developments

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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.

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& Ks 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 / 107 min bias.

• Very appealing with early data then will be studies with and Ks – with 107 min. bias expect:

• ~ 45k p• ~320k KS

• Applying AP kinematic cuts (left) provides very clean samples.

• Currently in the early stages of writing selection algorithms for both decays

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Selection• Particularly interesting is the proton efficiency distribution….

Plots - B Popovici, LHCb Week April ‘08

Calibration SampleMC 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.

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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 Ks 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…