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THE RICH TRIGGER

THE RICH TRIGGER. M.Lenti. The RICH. From the test beam :17 hits @ 35 GeV /c From the test beam : 9 hits @ 15 GeV /c. PMT: Hamamatsu R7400U-03. Dark current @ 900 V: 0.5 nA ( typical ) Gain @ 900 V: 1.5×10 +6 ( typical ) Dark rate: 2 KHz /PMT 2000 PMT: 4 MHz dark rate

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THE RICH TRIGGER

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  1. THE RICH TRIGGER M.Lenti

  2. The RICH • From the test beam:17 hits @ 35 GeV/c • From the test beam: 9 hits @ 15 GeV/c M.Lenti

  3. PMT: Hamamatsu R7400U-03 • Dark current @ 900 V: 0.5 nA (typical) • Gain @ 900 V: 1.5×10+6 (typical) • Dark rate: 2 KHz/PMT • 2000 PMT: 4 MHz dark rate • Ex.: Multiplic.Trigger with 10 nswindow: • 1 hit cut: 4 MHz due to dark rate • 2 hits cut: 4MHz×4%= 0.16MHz dark rate • 3 hits cut: 4MHz×0.16%=6.4KHz dark rate M.Lenti

  4. Test beamresults • Hard todisentangle pure dark rate fromhalomuons…. • Probably the pure dark rate ismuchsmallerthancalculated • A halomuoncrossing a PMT give a hit 100ns before the Cherenkov ring hits • “Spurious” rate in the MHz range M.Lenti

  5. NINO BOARD (NEW) MULTIPLICITY OUT POWER 32 PAIR LVDS OUT EXTERNAL PROGRAMMABILITY I2C BUS I2c logic VTH DAC I2C BUS BIAS DAC I2C BUS Mult logic 4 CHIPs NINO CHIP NINO CHIP NINO CHIP NINO CHIP FRONT-END CONNECTOR AREA FRONT END PCB M.Lenti

  6. External programming of VTHAND TRIGGER LOGIC VTH trimmer is located in the center of front-end assembly Once all board are loaded and connected it is extremely diffucult to change setting. NEW RELEASE WITH DAISY CHAIN I2C BUS TO DIGITALLY CONTROLL VTH OUT IN I2C LOGIC AND DAC TRIGGER OUT LOGIC MULTIPLICITY UNIT MULT OUT M.Lenti

  7. A RICH based trigger • Using the NINO multiplicity output the n.ofchannels can bedividedby 8 (or more) • 2048/8 = 256 = half a TDC-TELL1 • One TELL1 can beusedtoprovide a multiplicity trigger from the RICH (about 10 MHz ouput rate) M.Lenti

  8. The CHOD • Needanactive detector in between the RICH and the LKR to veto photonuclearinteraction in the RICH (λ0: mirror 20%, neon 5%) • Photonuclearinteraction: hit in the CHOD and nothing else (no track): no timecorrectionpossible • Weneed a fast CHOD forvetoeingwithouttoomuch dead time • Natural candidate for CHOD: carbon copy of MUV3 M.Lenti

  9. The CHOD trigger • Weneed the CHOD forvetoeing • We can use the CHOD fortriggering • 10 MHz track rate (butintensitygetstrongertowards the center) • Define the dead timetobeaccepted • Determine the granularity M.Lenti

  10. The Charged trigger • Itseemsto me quitesafe: • Have a RICH trigger • Have a CHOD trigger • Decide at the very end whattouseasmain trigger and whatascontrol trigger M.Lenti

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