Trigger operation during 2007 run D. Nicolò University of Pisa & INFN, Pisa (on behalf of Trigger group)

Outlook System overview m->eg trigger and related Hardware Firmware DAQ m->eg trigger and related Selection criteria Rates & efficiencies Statistics FADC linearity Calibration triggers a (p,g) p0 What next July 19, 2019

System overview Tree structrure made of LXe TC DC NaI+pre-shower Type 1 boards (100 MHz sampling) 216 channels from Inner PMTs fanin 1x1 160 Lateral and Outer PMTs 4x1 60 channels from TC bar PMTs 1x1 64 TC fiber APDs 8x1 32 channels from DC inner wires 8x1 32 outer wires 8x1 9+4 channels 1x1 ~ 600 channels, 40 boards Type 2 5 intermediate-layer boards 1 top-level board (master) Ancillary 5 boards for control signal (CLK, SYNC, START, STOP) distribution Type 3 (auxiliary digitizers) 640 channels (20 boards) for digitization of 1x1 output from LXe PMTs System completed and fully operating during 2007 run (all channels working!) LXe TC DC NaI+pre-shower July 19, 2019

Final trigger list trig.# name conditions 0 MEG QLXe > QTH && D < DN && |T| < TWN 1 MEG-Q QLXe > QTL && D < DN && |T| < TWN 2 MEG-D QLXe > QTH && D < DW && |T| < TWN 3 MEG-T QLXe > QTH && D < DN && |T| < TWW 4 RD-narrow QLXe > QTL && |T| < TWN 5 RD-wide QLXe > QTL && |T| < TWW 6 p0 QLXe > QTH && QNaI>QN && |T| < TWN 7 p0-pre-shower QLXe > QTH && QNaI>QN 8 NaI QNaI > QN 9 LXe-high QLXe > QTH 10 LXe-low QLXe > QTL 11 CW QTL < QLXe < QTH && |T| < TWW July 19, 2019

meg trigger and related Operated from 15 to 17/12 (run 9201-9516, ~ 25 h live time) Collected ~ 1.1x106 events (1/4 of which with trigger 0) Prescaling adjusted in order to have almost equal event sharing Rates in agreement with expectations Trigger 0 ~ 4 Hz (@ 40 MeV threshold) 1 ~ 6 Hz (@ 35 MeV ) 2 ~ 20 Hz (only up/down e+-g correlation) 3 ~ 10 Hz (DT = 20 ns) 4 ~ 40 Hz (no e+-g correlation, DT = 20 ns) 5 ~ 70 Hz (no e+-g correlation, DT = 40 ns) July 19, 2019

g-energy efficiency Rg ~ 7x103 s-1 @ Eg > 45 MeV Obtained from ratio of triggered/unbiased off-line spectra Rg ~ 7x103 s-1 @ Eg > 45 MeV July 19, 2019

Almost fully efficient (e > 0.9 @ 90% CL) at the end-point g-energy efficiency Low threshold High threshold Almost fully efficient (e > 0.9 @ 90% CL) at the end-point July 19, 2019

Timing coincidence efficiency Obtained from Radiative Decay B(p,g)C Cosmic Rays Trigger on LXe alone Ethr  30 MeV T-reconstruction in 2.5 ns ticks Rm = 5 x 106 s-1 July 19, 2019

LXe-TC timing 1 = 10 ns CR B(p,g)C (background free!) DT 4.4 MeV 11.7 MeV Fluctuation sources: algorithm ~5 ns (each) tof spread ~3 ns (e+), 1 ns (g)  DT (FWHM) ~ 18 ns  e (20 ns) = (80  5)% Dt (10 ns) July 19, 2019

Direction match zT (cm) zT (cm) log(Q1/Q2) log(Q1/Q2) no DC-info used at trigger-level (latency too long) LUT to associate (Xg, pe+ )  e+-hit on TC based on MC so far  DC-tracking needed to evaluate efficiency g-position by max PMT in LXe e+-position by charge asymmetry in TC PMTs 6-bit resolution for Q Off-line On-line zT (cm) zT (cm) zT obtained by DRS timing info log(Q1/Q2) log(Q1/Q2) July 19, 2019

Trigger for LXe calibrations gs from CW reactions B(p,g)C (used for both energy and timing) Li(p,g)Be (see G. Signorelli’s talk) a-events from wire sources Based on patch enabling capability Wire identification PSD not available for 2007 run (a,g) pulses not separated by off-line analysis Scintillation (excitation) decay time longer than expected  worse separation also by DRS Used to be better in the Large Prototype Possible hint at ionization quenching? p0 from CEX reaction July 19, 2019

a/g separation in the LP TRG waveforms recorded during 2003 test-beam at pE1 July 19, 2019

Dependence on purification? now 2003 run in LP a-run p0-run Run 9001 Run 7260 Q/A g-peak is lower with larger absorption a/g separation is poorer Final ratio is <Q/A>|g/ <Q/A>|a = 1.25  0.02 (used to be 1.93  0.02) July 19, 2019

CEX calibration Started from 18/12 to 21/12 (runs 9541-9927, 40 h live time) Collected ~ 1.3x106 events (~ 2x105 with preshower) Max PMT to obtain g-direction to LXe define collimation on a 2x3 PMT window Back-to-back correlation with NaI in 4 positions Data taken in different beam conditions LXe single rate from 1 MHz to 100 kHz @ E>30 MeV Pb collimator July 19, 2019

online reconstruction CEX spectrum in LXe LXe alone, high intensity LXe && NaI, medium intensity LXe && NaI, low intensity online reconstruction July 19, 2019

Towards 2008 run Hardware construction over Analysis of 2007 data in progress Trigger rates in agreement with expectations Trigger efficiency evaluated for Eg close to 100% DT around 80% (to be improved by better timing reconstruction) Direction (in progress) Pending questions (a,g) separation and a-trigger Good performance as a digitizer system for off-line analysis linearity guaranteed up to 130 MeV  good for energy reconstruction timing resolution at level of 1 ns Firmware upgrades Readout speed-up Data compression Q,T algorithm refinements July 19, 2019