First step to Reconstruction of PANDA Barrel DIRC in PandaRoot Dipanwita Dutta GSI, Darmstadt (Also at Bhabha Atomic Research Centre, Mumbai, India) PANDA Collaboration Meeting, GSI Mar. 2010
Panda Collaboration Meeting, Mar 2010 Outline Reconstruction Algorithm for DIRC Introduction What is Look-up Table What we are doing and why? Results Summary and Outlook D. Dutta Panda Collaboration Meeting, Mar 2010 2
Panda Collaboration Meeting, Mar 2010 PANDA barrel DIRC DIRC Barrel Target Beam Pipe Cherenkov Photons Propagated in bar Beam Pipe Photons hits in the Photon Detector (Cherenkov Ring) Mirror Photon Detection Plane Photon Propagation Medium ( Marcol82 ) Lenses D. Dutta Panda Collaboration Meeting, Mar 2010 3
Reconstruction Algorithm Reconstruction Input: (1) Charged track parameter (2) Hit time and position (x,y) in Photon Detector plane Possible Reconstruction Algorithms: Babar-Like Reconstruction: (Ref. DIRC NIM paper for BaBar Experiment, NIMA 538(2005)281) Look-up Table: (PMT/Bar define angle) Likelihood method - Track maximum likelihood fit (track by track) - Event global likelihood fit Hough Transformation - Fit the ring directly, standard method for shape recognition CosC=1/n D. Dutta Panda Collaboration Meeting, Mar 2010 4
What is Look up Table? Provides Average kBar vector for each pixel in PD for (pixel, bar) combination Very fast decision: useful for triggering Track Dir Vector (trx,try,trz) PD plane Photon Dir Vector at exit (kx, ky, kz) Photon Dir Vector at creation (phx, phy, phz) kBar vector (pixel bar) in bar co-ordinate system y ky x kx z kz 8 fold ambiguity Focussing Lens D. Dutta Panda Collaboration Meeting, Mar 2010 5 5
What we are doing and why? Reconstruction : Step1 Look-up table and getting the average kBar vector for each (pixel,bar) combination Already a test model implemented in drcprop dir by Roland (talk in PID) Has to be implemented in PandaRoot framework with proper DIRC geometry Problem of implementation due to double ring structure in PD plane ( talk dec09) Instead start with average k vector ( a simplified approach to test reco.) Option 1: Take the momentum direction vector at the PD hits Option2: Take the Direction vector of the connecting vector of PD hit and the middle of bar Step2: Estimate ThetaC taking account all possible ambiguity of k vector y ky Option 1 x kx z kz 1 3 2 Option 2 8 fold ambiguity Focussing Lens D. Dutta Panda Collaboration Meeting, Mar 2010 6 6
Results on Cherenkov Angle Reconstruction Kaon (Box Generator): Mom =2 GeV, =50, =10, nEvents=100, Mag Field :off ThetaC at creation point c (rad) D. Dutta Panda Collaboration Meeting, Mar 2010 7
Results of Cherenkov Angle Reconstruction Kaon (Box Generator): Mom =2 GeV, =50, =10, nEvents=100, Mag Field :off Option 1: kDir from photon mom. Mean= 0.7676 =0.034 ThetaC estimated from all possible combination of k vector c (rad) Good News: Get a peak at expected ThetaC Bad News: The resolution ~34mrad instead of expected ~10mrad (understood due to simplified approach of k vector) D. Dutta Panda Collaboration Meeting, Mar 2010 8
Results on Cherenkov Angle Reconstruction Kaon (Box Generator): Mom =2 GeV, =50, =10, nEvents=100, Mag Field :off Option 2: kDir from connecting vector of photon hit in PD and middle of bar ThetaC with all possible combination Splitting due to two rings Further splitting due to pixelization c (rad) ThetaC after putting detection efficiency and pixelization c (rad) D. Dutta Panda Collaboration Meeting, Mar 2010 9
Results on Cherenkov Angle Reconstruction Kaon (Box Generator): Mom =0.6 GeV, =50, =10, nEvents=100, Mag Field :off ThetaC at creation point c (rad) D. Dutta Panda Collaboration Meeting, Mar 2010 10
Results on Cherenkov Angle Reconstruction Kaon (Box Generator): Mom =0.6 GeV, =50, =10, nEvents=100, Mag Field :off Option 1: kDir from photon mom. ThetaC with all possible combination c (rad) ThetaC after putting detection efficiency and pixelisation c (rad) D. Dutta Panda Collaboration Meeting, Mar 2010 11
Panda Collaboration Meeting, Mar 2010 Summary and Outlook Reconstruction with average kVector: Reconstruction of Cherenkov Angle (ThetaC), a first test version has been implemented All possible ambiguity for k vector considered to estimate ThetaC Shows peak at expected thetaC Poor Sigma due to simplified approach of k vector Splitting of ThetaC peak if k vector is taken from hit to bar middle connecting vector (due to double ring) Outlook kBar vectors in bar co-ordinate system should be implemented Average k vector should be replaced by the kBar from look-up table Studying the source of double ring structure in PD plane (talk dec09) - D. Dutta Panda Collaboration Meeting, Mar 2010 12
Panda Collaboration Meeting, Mar 2010 Thank you D. Dutta Panda Collaboration Meeting, Mar 2010 13
Patterns in Photon Detector Plane Kaon (Box Generator): Mom =2 GeV, =50, =10, nEvents=100, Mag Field :Off Putting Graphical Cuts band1 (cut1) and band2 (cut2) D. Dutta Panda Collaboration Meeting, Mar 2010 14