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Octal ASD Certification Tests at Michigan

Octal ASD Certification Tests at Michigan. J. Chapman, Tiesheng Dai, & Tuan Bui. August 30, 2002 - CERN. Goals of Michigan Test. Confirm actual deadtime vrs setting. Hits/event vrs trigger rate (I/O traffic test). ( Have observed a feature above 20KHz ). Operate in pair & edge modes.

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Octal ASD Certification Tests at Michigan

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  1. Octal ASD CertificationTests at Michigan J. Chapman, Tiesheng Dai, & Tuan Bui August 30, 2002 - CERN

  2. Goals of Michigan Test • Confirm actual deadtime vrs setting. • Hits/event vrs trigger rate (I/O traffic test). (Have observed a feature above 20KHz). • Operate in pair & edge modes. • Measure drift spectrum & pulse width. • Test general stability with time. • Examine high-rate behavior.

  3. Hardware on Chamber • 17 AMT2 Octal Mezz cards were installed. One for a trigger injector.

  4. AMT & ASD settings To the right is the setup screen for the ASD. Below is the AMT setup • Important settings: • Search Window = 1.825ms • Match Window = 1.2ms • ASD Deadtime = 790 ns • Cosmic data is taken with leading/trailing mode. • Other tests are done in pair mode

  5. Online Data Monitor • Data Integrity Check • EVID Match • BCID Match • Data Structure • Data size of each TDC • Head/Trailer correct • Parity Error • TDC Errors • Error details are recorded for further analysis • TDC error reports are checked at end of run

  6. Triggers 400 Ticks • Cosmic trigger (24Hz) • ORed with • Continuous pulser trigger from 100Hz to 100KHz.

  7. High Rate Test Difficulties • AMT-2 level 1 buffer address “bug” has two effects that complicate precise testing. • At high trigger rates & modest hit rate, hits lost. • At high trigger rates, readout of hits not in the match window occur. Noise is exaggerated. • With DAQ used, full readout is limited to a few KHz. For trigger rates up to 100KHz+ prescale sampling was employed.

  8. Conditions for Hit Miss

  9. False hits above 20KHz Plot shows hit rate at 60mV threshold in a 1.2 ms match window. Rate is a few hits per 10,000 events in each channel below 20KHz & rises 8 fold at high rates. ~8 fold Rise at 20KHz

  10. Noise Performance Unshielded hedgehogs Shielded hedgehogs have much smaller noise rate.

  11. Deadtime Measurement

  12. Deadtime vrs DAQ Rate

  13. ASD Noise Pulse Width • ASD noise feature • ASD main threshold is set to –10mV. One expects that most hits are introduced by ASD • For this case the pulse width seen is narrow, around 20ns

  14. Hit Width Distribution Measurements are done with nominal 60mV threshold & chamber HV on, so width distribution includes real ionization hits from chamber & ASD noise hits. ASD Noise “Real Hit Noise”

  15. Hit Rate vs Threshold At low threshold hits are from ASD noise falling with threshold. At 60mV & above the hits per channel reach a plateau & are mostly “real” chamber signals

  16. Time & Width Measurement For this test the trigger signal is injected into a mezz card for digitization & to the trigger. The measured time should be uniformly distributed in a 25nswindow since the digitization clock is not synchronized to the trigger pulser. A uniform,narrow & large width is expected for these pulses. Width encodes amplitude

  17. Fine Time Measurement Hits from Cosmic Ray

  18. Cosmic Ray Observation

  19. Cosmic Ray Spectrum ASD Noise

  20. Reconstruction Efficiency Low reconstruction efficiency of 6 layer cosmic tracks is due to dead channels. Most of the loss is traced to shorts & open circuits on the shielded hedgehog cards. Was 0.45 for unshielded

  21. Stability Test at 100KHz 17 Mezzanine Cards are tested at 100KHz DAQ rate including cosmic ray trigger. System runs without any problems. Average event size is 36.29 (= 0.29 hits per event) & is constant over a long periods. (ASD isstable & quite)

  22. DAQ for Long Drift Time Operate Mezzanine Card for long drift times without problems (ASD is stable & quiet over long periods) Pair mode cannot be used with long drift times due to limited number of bits. Can a) slow down clock or b) use leading & trailing edge mode. Hits with leading edge > 1.6ms are lost

  23. Conclusions • From an operational standpoint the ASD works without problem & is capable of triggering at 100KHz. • The measured average ASD deadtime is as expected. One ASD channel was outside the typical pattern. • The measured hit rate for a HV-on-chamber is about 1KHz per mezzanine card when the ASD threshold is 60mV or above. • We observe cosmic rays at low trigger rate. • We are unable to perform high rate tests due to the known AMT problem. We observe no ASD problems. • It is possible to operate ASD/AMT mezzanine card with long drift times but with deadtime less than 800ns.

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