Hycal response function study

Observed elasticity during snake scan when beam was centered on W2016 Shape of experimentally observed response function: *) resp. function itself *) accidentals (with false tagger hits) *) + electronics noise ?? *) + “leakage” ?? response function tail “pile up” threshold ? Which part of experimentally observed response function should be compared with the function reproduced by MC ?

Response function was split into elasticity regions X = min – 0.2 X = 0.2 – 0.5 X = 0.5 – 0.8 X = 0.8 – 0.9 These regions probably are lost in data analysis

Fraction of events in these elasticity regions were estimated for runs with different beam current: 20, 30, 50, 60, 95 pA Hycal resp. function itself is assumed independent from beam current. Fit was applied. Fitting function: Y = c1/x + c0 Values of c0 were Used as asymptotic values.

What does MC reproduce for response function snake centered Tails in MC are due to wrapping. “Zero” bin vanishes at beam slope > few mrad and looks not significant for p0 and compton. “Zero” bin can be confirmed or rejected during the next run. It can be used as a measure of wrapping “effective thickness”.

Compare data with MC Difference between data and MC ~ 0.5 – 0.9% 1.3GeV 4.4GeV X range MC Data asympt. Min – 0.2 0.02 ± 0.00 0.15 ± 0.03 0.2 – 0.5 0.23 ± 0.04 0.5 – 0.8 0.07 ± 0.01 0.40 ± 0.05 0.8 – 0.9 0.38 ± 0.02 0.61 ± 0.05 X range MC Data asympt. Min – 0.2 0.03 ± 0.01 0.06 ± 0.02 0.2 – 0.5 0.02 ± 0.00 0.14 ± 0.04 0.5 – 0.8 0.08 ± 0.01 0.26 ± 0.03 0.8 – 0.9 0.40 ± 0.02 0.57 ± 0.04

Observed tagging ratio (using Hycal) for different E-channels within one (isolated) T-channel Tagging ratio looks have -1% jump when “entering production region”. False hits real hits False hits real hits