Detection and reconstruction of π0 mesons in the ICARUS detector.

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Detection and reconstruction of π0 mesons in the ICARUS detector.

Energy resolution.• Monte Carlo (FLUKA) – generatedelectromagnetic showers:• photons and electrons• different angles θ , φ• We would like to know what kind ofenergies we can measure and if there issome dependent on the angle of the showerwith respect to the wiresDetection and reconstruction of π 0mesons in the ICARUS detector.Tomasz Palczewski. I.P.J (SINS).


Detection and reconstruction of π 0mesons in the ICARUS detector.Tomasz Palczewski. I.P.J (SINS).


Data selection Scanning was done in several laboratories.Warsaw, Cracow, Katowice, Pavia. Sometimes same event measured in the differentlaboratories produces different values in vertexcoordinate and shower energy determination due tothe presence of crowded environment ( noisybackground ) 212 hadronic interactions with at least one mesoncandidate were collected for further analysis.Detection and reconstruction of π 0mesons in the ICARUS detector.Tomasz Palczewski. I.P.J (SINS).


Hadronic interaction in a crovdedenvironmentRun 600 Event 17Noisy backgroundm.i.p tracksDetection and reconstruction of π 0mesons in the ICARUS detector.Tomasz Palczewski. I.P.J (SINS).


Scanning rules adopted for the pre-selection ofhadronic interactions with π 0 production: At least two, well separated electromagnetic cascadesoriginated by photons pointing to the interaction vertex weredemanded. Knowledge of event zero time (t0) was mandatory in order todetermine the interaction vertex and the track and cascadespatial positions in the chamber, as well as to apply propercorrections to the collected signals due to the drift electronmean lifetime. Interactions with neutral meson candidates were rejected whenionization due to other tracks and interactions in theirneighborhood was so high that it seriously affected the cascadeenergy determination.Detection and reconstruction of π 0mesons in the ICARUS detector.Tomasz Palczewski. I.P.J (SINS).


REJECTEDExample of the accepted (left)and rejected event (right)Overlapping of tracksDetection and reconstruction of π 0mesons in the ICARUS detector.Tomasz Palczewski. I.P.J (SINS).


Measurement of (γ,γ)() systemsFor the evaluation of the invariant mass M γγ of (γ,γ) systems are needed:1. The two shower energies, E and E 1 22. The angle θ 12 between the two showersγγMeasurements donein different laboratoriesC = calibration factor converting fromADC to MeV (after MC simulations)are in agreementC = ( 152 ± 2 ) * 10-4 fc/(/(ADC* ADC*µs)Shower energy is given by:W = the average energy needed for creationof an electron-ion pair.0.5W = .623 + −0.3R = the electron-ionrecombination factor.R = 0.640 ± 0.013e (t i-t /τe) 0 = correction for drift electronfinite life time τ eQi = the hit area.Detection and reconstruction of π 0mesons in the ICARUS detector.Tomasz Palczewski. I.P.J (SINS).


Invariant mass and energy ( data from Test Run in Pavia ).Final sample.Detection and reconstruction of π 0mesons in the ICARUS detector.Tomasz Palczewski. I.P.J (SINS).


PullIn the case of reliable errors the distribution of Pull shoud beDetection and reconstruction of π 0mesons in the ICARUS detector.Tomasz Palczewski. I.P.J (SINS).normal with RMS equal to unity.


Neutral curent ν µ events with π 0 production as abackground to ν e interaction.When can we misidentify π 0with electron?– one photon from the decay is lostwhen it is emitted with too smallenergy and the other photon eitherproduces the Compton photonclose to the primary vertex, or theconversion pair is produced closeto the primary vertex.– the two photon showers overlapand the Compton scattering occursclose to the primary vertex.Detection and reconstruction of π 0mesons in the ICARUS detector.Tomasz Palczewski. I.P.J (SINS).


M from γγ neutrino interactions (MC)ηDetection and reconstruction of π 0mesons in the ICARUS detector.Tomasz Palczewski. I.P.J (SINS).


Conclusions A sample of about 200 events with at least of twophotons pointing to the interaction vertex has beenselected from the data collected during the test run ofthe ICARUS detector. Those data was used as a test of the energyresolution as a function of photon shower energy. The invariant mass of the photon pairs from a finalsample was reconstructed.– m = 127 ± 3.0 (stat) ± 4.0 (sys) MeV/c 2confirm that the π 0 s are the main source of photon pairs.Detection and reconstruction of π 0mesons in the ICARUS detector.Tomasz Palczewski. I.P.J (SINS).


Conclusions The width of the distributions of invariant mass forsimulated events was similar within errors, confirmingthe validity of the shower energy and shower directionreconstruction methods. It was found that in the photon energy range from 50to 5000 MeV the electromagnetic showers energyresolution ∆E/E can be approximated by a formula∆E/E = P1/√E + P2 with the parameters P1 = (0.33±0.03) √MeV and P2 = 0.012 ± 0.002.Detection and reconstruction of π 0mesons in the ICARUS detector.Tomasz Palczewski. I.P.J (SINS).


Thank you.Detection and reconstruction of π 0mesons in the ICARUS detector.Tomasz Palczewski. I.P.J (SINS).

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