The CLEO-III Trigger: Analog and Digital Calorimetry

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1 The CLEO-III Trigger: Analog and Digital Calorimetry George Gollin University of Illinois at Urbana-Champaign Nuclear Science Symposium and Medical Imaging Conference, Lyon, France, October 15-20, 2000 Paper NSS575 C. Bebek 2, T.J. Bergfeld 1, J.A. Ernst 1, G.D. Gollin 1, M.J. Haney 1, R.M. Hans 1, E.E. Johnson 1, C.L. Plager 1, C. Sedlack 1, M.A. Selen 1, C.R. Strohman 2, and J. Williams 1 1 Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois Wilson Laboratory, Cornell University, Ithaca, NY

2 The CLEO-III Trigger: Analog and Digital Calorimetry. George Gollin, University of Illinois 2 Outline CLEO-III trigger description What s new since CLEO-II.5 Signal path: calorimeter trigger Analog processing Digital processing Neat analog stuff self-test capability gain adjustments output pulse width control Wrinkles See:

3 The CLEO-III Trigger: Analog and Digital Calorimetry. George Gollin, University of Illinois 3 CLEO-III detector

4 The CLEO-III Trigger: Analog and Digital Calorimetry. George Gollin, University of Illinois 4 CTL Mixer-Shapers DR3 preamplifiers DAQ TILE daughter boards QVME (quiet master) Barrel analog TILE daughter boards QVME (quiet master) AXX AXTR TIM DM/CTL Axial drift chamber G/CAL DFC DM/CTL Flow control/gating Endcaps analog TPRO (tile processor) SURF TPRO (tile processor) SURF STTR TIM DM/CTL Stereo drift chamber The CLEO-III trigger TIM DM/CTL CCGL AXPR TRCR L1TR LUMI TIM DM/CTL Pulser Calorimeter digital Level 1 decision

5 The CLEO-III Trigger: Analog and Digital Calorimetry. George Gollin, University of Illinois 5 CLEO-II vs. CLEO-III CLEO-II CLEO-III 1 crystal trigger efficiency shower energy Hard to model well... 1 crystal Showers spanning boundaries between regions in the CLEO-II calorimeter were difficult to simulate precisely. For CLEO-III, which forms analog sums of overlapping regions, at least one tile will contain the entire shower.

6 The CLEO-III Trigger: Analog and Digital Calorimetry. George Gollin, University of Illinois 6 Signal path for one CsI crystal preamps mixer-shaper from neighbors CsI crystal m/s controller to ADC s daughter board to neighbors hi/med/low Gray code TILE (services, test pulses) TPRO (tile processors) SURF (merge results) CsI: fast edge, ~900 ns fall time Preamp: peak ~3 µs, fall ~180 µs. M/s controller: peak ~2.5 µs, fall ~8 µs. Daughter board copies its mixer-shaper signal to neighbors Daughter board sums 4 analog signals Summed signal shaped (bipolar), then discriminated. Signals > hi/med/lo thresholds: zero-crossing-synched logic pulses sent to tile processors. Results from tile processors (4 barrel, 2 endcap) combined by SURF boards, then sent to Level 1 trigger. To Level 1

7 The CLEO-III Trigger: Analog and Digital Calorimetry. George Gollin, University of Illinois 7 off-board test pulses mixershaper test pulse generate copies receive copies gain adjust sum shape ZCD discriminate, then detect zero-crossing high medium low off-board mixer-shaper sum high medium low generate programmablewidth logic pulse on ZCD Gray code to TPRO bipolar shaped pulse bipolar pulse crosses threshold bipolar pulse crosses zero CLEO-III to tile processor daughter board

8 The CLEO-III Trigger: Analog and Digital Calorimetry. George Gollin, University of Illinois 8 Tile processing steps θ projection: 12 bins, 3 thresholds High thresh. tile Med. thresh. tile Low thres. tile φ H M L θ 1 2 Filter Project 2 1 H M L φ projection: 16 bins, 3 thresholds

9 The CLEO-III Trigger: Analog and Digital Calorimetry. George Gollin, University of Illinois 9 Self-test features Inject realistic test pulses into input transistors so that full signal path is driven...

10 The CLEO-III Trigger: Analog and Digital Calorimetry. George Gollin, University of Illinois 10 Self-test features thresholds test pulse to daughter board bipolar shaped pulse test pulses test pulse receive copies ZCD1 (low thresh, then zero-crossing detected) ZCD2 (med thresh, then zero-crossing detected) ZCD3 (high thresh, then zero-crossing detected) mixershaper generate copies Trigger bits for tile processor (before Gray encoding) Generate test pulse Clock readback latches Vary test pulse - latch clock delay and thresholds to test boards: discriminator + threshold DAC = ADC -500 ns to +25 µs, 1 ns steps steps

11 The CLEO-III Trigger: Analog and Digital Calorimetry. George Gollin, University of Illinois 11 Gain adjustments... Analog Devices AD8842 TrimDAC

12 The CLEO-III Trigger: Analog and Digital Calorimetry. George Gollin, University of Illinois 12 Gain adjustments... AD8842: very nice device, ~1 = C per channel, but be careful...

13 The CLEO-III Trigger: Analog and Digital Calorimetry. George Gollin, University of Illinois 13 Output pulse width programming current mirror 74LS123 monostable multivibrator (one-shot) set width timing capacitor

14 The CLEO-III Trigger: Analog and Digital Calorimetry. George Gollin, University of Illinois 14 Life is always interesting... Noise environment hard to predict before installation. ~4 MHz common-mode glitch at 60 Hz coherent noise upstream of sum high frequency supply noise in full system (PSRR drops at high frequencies) Lots of ferrite toroids on cables to block common mode noise... Grounds are hard for physicists to understand: confusion over IR vs. IωL voltage differences, etc. etc.

15 The CLEO-III Trigger: Analog and Digital Calorimetry. George Gollin, University of Illinois 15 Life is always interesting... Parts didn t always behave like we expected: touchy (non-maxim) discriminators correct configuration data shift / load / clear algorithm is different from documentation surprising (mixed signal) device sensitivity to noise on digital inputs Mixed signal (analog/digital) boards are tricky: board layout is important. Experimental halls flood, submerging spare boards temporarily kept in boxes on the floor

16 The CLEO-III Trigger: Analog and Digital Calorimetry. George Gollin, University of Illinois 16 Art simulates life... Good analog simulation tools, well-integrated with circuit design capture, proved invaluable. User interface could be improved. Often, SPICE models for new devices don t exist. Including layout information in simulation can be complicated.

17 The CLEO-III Trigger: Analog and Digital Calorimetry. George Gollin, University of Illinois 17 We re working on it... System has not been in use for very long. We are currently investigating: relative timing for signals passed from neighboring daughter boards vs. directly from mixer-shapers noise associated with analog signals passed across VME crate boundaries Built for CLEO-III calorimeter trigger: ~700 daughter boards ~30 TILE boards ~30 mixer-shaper controllers ~8 tile processor boards ~8 QVME ~4 SURF...

Timing Pulses. Important element of laboratory electronics. Pulses can control logical sequences with precise timing.

Timing Pulses. Important element of laboratory electronics. Pulses can control logical sequences with precise timing. Timing Pulses Important element of laboratory electronics Pulses can control logical sequences with precise timing. If your detector sees a charged particle or a photon, you might want to signal a clock