COMPTON SCATTERING IN FORWARD DIRECTION PROGRESS REPORT PAWEL AMBROZEWICZ NC A&T
GOAL – EXTRACT COMPTON CROSS SECTION WITH GOOD PRECISION KINEMATIC TOOLS EVENT SELECTION YIELD FITS SIMULATION CROSS SECTIONS SUMMARY
RECONSTRUCTED QUANTITIES: KINEMATICS MEASURED QUANTITIES: ENERGY OF INCIDENT PARTICLES POSITIONS AT HyCal FOR BOTH PARTICLES ENERGIES OF SCATTERED PARTICLES RECONSTRUCTED QUANTITIES: DISTANCE TO TARGET (Z): REQUIRES KNOWLEDGE OF x, y, E FOR BOTH CLUSTERS ENERGY DIFFERENCE ( E(TAGGER) - E(E1, E2, ) ): REQUIRES KNOWLEDGE OF ENERGIES FOR BOTH CLUSTERS AND OPENING ANGLE
CO-PLANARITY |-180o|<25o FIDUCIAL REGION OF HyCal : EVENT SELECTION: COINCIDENCE TIMING < 3.2 ns CO-PLANARITY |-180o|<25o FIDUCIAL REGION OF HyCal : 2+ INNER CRYSTAL LAYERS OUTERMOST CRYSTAL LAYER “CRISS-CROSS” PAIR PRODUCTION CUT ’e’ OPENING ANGLE RMIN > 18.5 cm
EVENT SELECTION: MINIMAL OPENING ANGLE/ MINIMAL SEPARATION CUT ADDITIONAL CUTS SERVE TO MINIMIZE SIGNAL-TO-NOISE RATIO TIMING CUT AFTER ALIGNMENT
RADIATIVE EFFECTS NEED TO BE ACCOUNTED FOR
TYPICAL DATA YIELD FITS
SIMULATION: GENERATES SIMPLE GEOMETRIC ACCEPTANCE APPLIES POSITION SMEAR TO REPRODUCE EXPERIMENTAL RESOLUTIONS ACCOUNTS FOR THE BEAM POSITION OFFSETS
SIMULATION ACCEPTANCE DEPENDENCE ON BEAM POSITION SHIFTS
ONGOING PARALLEL ANALYSIS – KELLI HARDY MAIN DIFFERENCES: FITS ONLY ENERGY DIFFERENCE USES EMPTY TARGET AS BACKGROUND MODEL DOES NOT REMOVE PAIR PRODUCTION EVENTS USES GEANT TO GENERATE ACCEPTANCE
SYSTEMATIC ERROR ESTIMATION STATISTICAL ERROR < 0.5% SYSTEMATIC ERROR ESTIMATION PHOTON FLUX 1.8% TARGET THICKNESS 0.05% BACKGROUND SUBTRACTION 2.5% ACCEPTANCE ~2.0% STABILITY (CALIBRATIONS) ~2.0% TOTAL ~5%
SUMMARY COMPTON CROSS SECTION HAS BEEN EXTRACTED FOR LARGE PORTION OF THE DATA – INDEPENDENT ANALYSES IN GOOD AGREEMENT STUDY SHOWS THAT STABILITY OF THE CROSS SECTION IS ~5% TO IMPROVE PRECISION MONTE CARLO SIMULATION HAS TO BE REFINED – CORRECTING FOR RADIATIVE EFFECTS NECESSARY REMAINING COMPTON DATA HAS TO BE ANALYZED … ANALYSIS NOTE – WORK IN PROGRESS …