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SPD and LHCb upgrade

The presentation by Hugo Ruiz et al. outlines the motivation behind the upgrade of the SPD and LHCb detectors, focusing on the challenges of ageing components, trigger system optimization, and the necessary replacements of various electronics and fibers. It discusses the physics motivation driving updates, including instantaneous luminosity increases and beam background considerations. Key points include the need for advancements in read-out frequencies, potential improvements in particle identification, and ongoing studies for optimizing performance ahead of the upcoming detector upgrades.

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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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