Benchmark channels for CGEM performance studies Cristina Morales for the CGEM software group 13.03.2017 1/31
2.396 and 2.9 GeV 2/31
Close to ppbar-threshold Cristina Morales • This channel allows to compare tracker perfomances at low proton/antiproton momenta • We have studied the channel at three CMS energies Ecms= 2.0, 1.975 and 1.95 GeV . At lower energies antiprotons annihilate before reaching tracker • Phokhara v9.1 used to generate e + e - → pp with NNLO ISR under boss665p01 • No background remaining after selection (permill level) 3/31
POAxy,z resolution of the tracks To study the track's vertex resolution, the cuts corresponding Ecm = 2.0 GeV to point of closest distance of approach are not applied. proton The procedure is done for proton and for anti-proton and for E CM = 2.0, 1.975 and 1.95 GeV POAxy proton (cm) POAz resolution (cm) POAxy resolution (cm) Red: proton Red: proton Black: aproton Black: aproton 5% 150% 50% Track momentum (GeV/c) Track momentum (GeV/c) The xy and z vertex The xy vertex The vertex resolution Can CGEM achieve resolution get better for proton resolution is better vertex with increasing better than the and anti-proton is resolutions at low momenta z vertex resolution comparable momenta 4/31
P and Pt resolution of the tracks To study the track's momentum resolution, the cuts corresponding to momentum window are not applied. 2.0 GeV proton We look at the transverse momentum and at the longitudinal momentum and we compare with the MC truth, Ecms = 2.0, 1.975 and 1.95 GeV Proton p reco – proton p true (GeV/c) red: proton P resolution (MeV/c) Pt resolution (MeV/c) red: proton black: aproton black: aproton 2% 30% The pt resolution The p and pt The resolution gets worse by 30% resolution is almost the as we go to lower get better with same for proton track momenta. increasing and antiproton Can CGEM do better? momentum. 5/31
De/dx resolution To measure the resolution at each energy, E CMS = 2.0 GeV all cuts are applied except for de/dx; proton Normalized de/dx pulse height positive track height resolution (MeV/c) Red: proton Normalized DE/DX pulse Black: aproton The resolution in dedx 7% is MUCH worse as the track momentum decreases: multiple scattering? There are other PID possibilities, still it would be interesting to see dE/dx for CGEM 114% 6/31
Tracking efficiencies and total selection efficiency Tracking effs red: proton Proton tracking eff black: aproton costheta_p Track momentum (GeV/c) Slight decrease in tracking effciency at lower Efficiencies flat except for at low/high theta_p. momenta. Antiproton trackin eff worse than for Can CGEM recover high/low polar angles? proton. Can CGEM bring it up? Selection efficiency as a function of the track momentum Better resolutions in the track variables could help to enhance the efficiency also at low momenta. (GeV/c) 7/31
at E CM = 3.773 GeV Martin Ripka • This channel allows to compare tracker perfomances at low proton/antiproton momenta • Phokhara v9.1 used to generate e + e - → mu+mu- with NNLO ISR under boss665p01 • Expected remaining background coming from Bhabha 1% • Since pions and muons behavekinematically and for the detector in the same way, both ee--> pipi and ee--> mumu are treated as signal 8/31
(only events within geometrical acceptance) Efficiency = number of selected tagged events/ generated events (taged and untagged) 9/31
10/31
We will provide the tracking effs vs pt 11/31
at E CM = 4.42 GeV Andreas Pitka 12/31
After selection (bacup slides) remaining background below 1% level!!. Composition: 13/31 open charm: D*0 D0*bar, D*+ D*-, pi0 D0 D0*bar
Event navigator used to match true particles with the recons. It is checked whether PID and mother particle are correct Not full selection applied ? It has been checked that the low energetic MC tracks do not come 17/30 14/31 from pion decays
Fundamental to include it in CGEMBoss for this channel!! 17/30 15/31
17/30 16/31
true true true 17/30 17/31
at E CM = 3.097 GeV Stuart Fegan 22/30 18/31
Selection efficiency: ~45%; Background contamination: below 1% Selection efficiency: ~45%; Background contamination: below 1% 23/30 19/31
20/31
21/31
at E CM = 3.773 GeV Peter Weidenkaff 22/31
23/31
K - tracking efficiency 24/31
Flight distance obtained after secondary vertex fit 25/31
26/31
e+e- -> Lambda Lambdabar Cui Li 27/31
28/31
27% 29/31
56% distribution of Rxy 30/31
Other variables studied: POAxy and POAz of all tracks at 2.396 and 2.9 GeV (see backup slides) 31/31
Summary & Outlook 1) We have done most of the studies we wanted to perform for MDC as IT. 2) We are working on Bhabha (+ISR) 3) We will compare the obtained results with the data quality group for the mumu, bhabha and J/Psi to 3pi channels 4) We will prepare a short description of the analysis and the obtention of the results shown here. 5) Soon our J/Psi analyser will leave Mainz. We need to decide whether or not to pursue his studies. 6) Waiting impatiently for CGEMBoss to start tests.
To do
backup
Selection criteria The selection is based on the HIM's selection for low energy scan data collected in 2015 Two good charged tracks of opposite charge (Rxy, Rz and good MDC tracks required) Vertex fit to improve resolution of the track's momenta If tracks leave a TOF signal then the difference between then < 4ns All cut limits addapted to the E CMS Back to back signature between tracks after boost to CMS: 170°, 160°, 160° Momentum window cut: p expected -4σ measured < p p,pbar < p expected + 3σ measured Particle identification using directly deposited energy in MDC: dedx 2.0 GeV 1.975 GeV 1.95 GeV No background remaining after selection (permill level) Cristina Morales, 14.02.2017
POAxy,z resolution of the tracks To study the track's vertex resolution, the cuts corresponding to point of closest distance of approach are not applied. The procedure is done for proton and for anti-proton and for E CM = 2.0, 1.975 and 1.95 GeV Ecm = 2.0 GeV Ecm = 2.0 GeV The xy and z vertex proton proton resolution get better with increasing momenta The xy vertex resolution is POAxy proton (cm) POAz proton (cm) better than the z vertex resolution POAxy resolution (cm) POAz resolution (cm) Red: proton Red: proton The vertex resolution Black: aproton Black: aproton for proton 5% and anti-proton is comparable 150% Can CGEM achieve 50% better vertex resolutions at low Track momentum (GeV/c) Track momentum (GeV/c) momenta
P and Pt resolution of the tracks To study the track's momentum resolution, the cuts corresponding to momentum window are not applied. We look at the transverse momentum and at the longitudinal momentum and we compare with the MC truth. Ecms = 2.0, 1.975 and 1.95 GeV P resolution (MeV/c) red: proton 2.0 GeV The p and pt black: aproton proton resolution get better with increasing momentum. It is almost the Proton p reco – proton p true (GeV/c) same for proton and antiproton Pt resolution (MeV/c) red: proton 2.0 GeV The pt resolution proton black: aproton gets worse by 30% 2% as we go to lower track momenta. Can CGEM do better? 30% Proton pt reco – proton pt true (GeV/c)
De/dx resolution To measure the resolution at each energy,all cuts are applied except for de/dx; height resolution (MeV/c) Red: proton E CMS = 2.0 GeV Normalized DE/DX pulse Black: aproton proton 7% Normalized de/dx pulse height positive track 114% E CMS = 2.0 GeV aproton The resolution in dedx is MUCH worse as the track momentum decreases: multiple scattering? There are other PID possibilities, still it would be interesting to see if Normalized de/dx pulse height negative track CGEM can do better
Total selection efficiency and geometrical acceptance Selection efficiency as a function Geometrical acceptance of the track momentum 0.8% (GeV/c) (GeV/c) Better resolutions in the track variables could help to enhance the The angular distribution of the events is efficiency also at low momenta. almost inependent of the geometrical acceptance (form factors model almost constant for this momentum range)
Proton and anti-proton tracking efficiencies Since only one track can be identified, a new, harder signal selection is used: ed to Eff_proton = number of events with 2 good tracks / number of events with 1 (anti-proton) or 2 tracks Black: 2GeV; Tracking effs Red: 1.975 GeV; red: proton Blue: 1.95 GeV; black: aproton Proton tracking efficiency Track momentum (GeV/c) costheta_p Efficiencies flat except for at low/high theta_p. Slight decrease in tracking effciency at lower Can CGEM recover high/low polar angles? momenta. Can CGEM bring it up?
Expected remaining background coming from Bhabha 1%. ee--> pi+pi- treated as signal (similar kin behavior as ee--> mumu)
Remaining background below 1% level!!
17/30
17/30
23/30
24/30
30/30
Recommend
More recommend
