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SPD and LHCb upgrade

SPD and LHCb upgrade. Hugo Ruiz et al from. Outline. Physics motivation Ageing of: Detector, fibers PMTs Replacements to be done VFEs? FEBs Fibers. Before upgrade: motivation now. Trigger: Separate e – g @ L0

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SPD and LHCb upgrade

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  1. SPD and LHCb upgrade Hugo Ruiz et al from

  2. Outline • Physics motivation • Ageing of: • Detector, fibers • PMTs • Replacements to be done • VFEs? • FEBs • Fibers

  3. Before upgrade: motivation now • Trigger: • Separate e – g @ L0 • Thresholds 2.3 GeV and 3 GeV in the last optimization at http://indico.cern.ch/getFile.py/access?contribId=1&sessionId=2&resId=0&materialId=slides&confId=42082 • GECs, but decided to drop them two weeks ago • Under study: trigger for two-photon for lumi: 2 muons + low SPD multi • Offline: • Some improvement in resolution of p0 mass for converted gs (but not so if Pb not there?) • Instantaneous lumiand beam backgrounds

  4. The upgrade • Lumi 1033 • All detectors read-out at 40 MHz, no L0 • Still, trigger needs to use: • Seeds à la L0 (calo, muons) • Reconstruction based in regions of interest See Hans’ presentation at http://indico.cern.ch/conferenceDisplay.py?confId=43555 • Bs fg one of the star channels

  5. The SPD in the upgrade • The SPD does not harm • It’s just a first sensitive layer in the calo • But electronics, fibers (etc?) to be replaced  $ • Use: classify trigger seeds as photons or electrons • 1st layer of trigger • 2 hadron + photon ? • 1 hadron + 1 photon? (maybe not, as also want 1 hadron + 1 electron?) • g confirmation: use SPD to reject bulk of events before looking for tracks in T stations pointing to ECAL cluster

  6. But: g e+e- • Current material budget: • 0.4 X0 magnet-Calo(Reoptimization TDR, pag 3) • Underestimation: only M1 is 0.265 instead of the 0.22 in the simulation • Probability of photon survival:  70% • Current g-confirmation at HLT1 uses only g candidates • Mariusz: no inefficiency because most of ECAL clusters duplicated as e and g, differing in a single cell ??

  7. Physics motivation • Other sources of inefficiency on photons: • Random coincidence, conversion in the SPD: • Multiplicity  33 @ 21032, would be  160 @ 1033 • Roughly 160/6000  2.6% (maximum 8% in hottest cell) • Ways out of ge+e-: • Still worth for the remaining 70%? • (non-binary output…) • Remove M1: ask for production of MC without M1 • Minimum bias (rate) • Bsfg (efficiency) • Who will do the study?

  8. Edu Ageing of detector & fibers • Common with PS • Edu is just starting to have a look at some old LHCb notes on HCAL scintillators and fibers • Ageing as a function of dose  need interaction with Gloria • And tried to contact Evgeni • Inputs?

  9. Míriam PMTs ageing • Intensity with current settings: • At 1033: • max  1-2 A •  25 < 0.4 A • rest < 0.2 A Lumi 2·1032 200 nA 1 mA Lumi 5·1032

  10. PMT ageing • LHCb-Calo 2003-044, http://indico.cern.ch/conferenceDisplay.py?confId=a031004 0.3 A ? 1 year of LHC

  11. ZOOM THE VERY FIRST PART OF THE DISTRIBUTION PMT ageing 10 A • Beware: for higher currents • Plot is for an old 12 stages, but same behavior checked on a 8-stage PMT • Current at upgrade lie between safe and dangerous region… • But can change positions of a few PMTs every year • Conclusion? • Need a test-bench?

  12. Compensation of gain loss with HV • Current HV settings: • Room for increasing to 800V • Gain increase possible • At least factor 5 V

  13. VFEs and gain reduction: noise • Noise level is 2 fCrms approx • Current charge/MIP • If we allow down to 5 s: maximum factor 3 reduction • Tails are low  some margin for larger factors…

  14. VFEs and gain reduction: dthreshold • Resolution with current gain • Common Vref • Able to set up to 1 MIP in all channels • Effect of gain reduction of a factor 3 • 250 instead of 300mV required for Vref • Resolution typically 12%, up to 25% of MIP • Again: margin for higher reductions Minimum resolution with current gain (one Vref) Minimum resolution with gain/3 (one Vref)

  15. Replacements: FE, fibers • The FE will need to send data at 40 MHz  to be replaced • New fibers needed to accommodate the extra band-with to send data to the barracks

  16. Conclusions

  17. Back-up • Efficiency of Bsfg vs rate (and # of tracks to be reconstructed) a good benchmark to evaluate the need for the SPD at the upgrade • Not excluded that SPD could work in the upgrade without major replacement of PMTs • New PMT aging test bench?

  18. Occupancies lumi2 lumi2 lumi2 lumi5 lumi5 lumi5

  19. Intensity @ lumi5 / lumi2

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