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High Precision Spectrometers project in CMS Krzysztof Piotrzkowski ( UCLouvain /CERN)

High Precision Spectrometers project in CMS Krzysztof Piotrzkowski ( UCLouvain /CERN). Introduction & Motivation HPS concept and staging HPS240 case. Workshop on Diffractive and Electromagnetic Processes at the LHC , 4 -8 January 2010, ECT*, Trento. FP420. New forward detectors:.

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High Precision Spectrometers project in CMS Krzysztof Piotrzkowski ( UCLouvain /CERN)

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  1. High Precision Spectrometers project in CMSKrzysztof Piotrzkowski (UCLouvain/CERN) Introduction & Motivation HPS concept and staging HPS240 case Workshop on Diffractive and Electromagnetic Processes at the LHC, 4-8 January 2010, ECT*, Trento

  2. FP420 New forward detectors: Brief history: May’05: R&D proposal acknowledged by LHCC June’08: FP420 Report Fall’08: Proposals to CMS/ATLAS In 2009: Adding detectors @ 220/240 m FP420 JINST 4 (2009) T10001 K. Piotrzkowski

  3. Exclusive Higgs bosons at LHC Main motivation for FP420 Higgs kinematics fully reconstructed with forward detectors! Access to Higgs mass and quantum numbers. Brief history: Białas & Peschanski ’96 Albrow & Rostovtsev ’00 Khoze et al. ’02 SM Higgs signal statistically limited, larger for MSSM case:

  4. HPS: Motivation • Light Higgs boson case is compelling more than ever – exclusive production provides unique information: • Higgs quantum numbers (spin-parity filter) • Direct & precise H mass measurement (event-by-event); MH resolution of  2 GeV direct limits on Higgs width • Possibility of detecting H bb mode • Detection of SM Higgs boson requires (very) large luminosity (sobs  0.1-0.2fb) and challenging timing detectors to keep backgrounds low (S/B1:2); in case of BSM physics HPS could provide discovery channels for Higgs bosons • In addition, HPS offers access to ‘guaranteed’ and unique studies like electroweak physics in two-photon interactions, or new QCD phenomena in exclusive production, for example. K. Piotrzkowski

  5. Observation of Exclusive Charmonium Production and gg → μ+μ- in pp Collisions at √s = 1.96 TeV K. Piotrzkowski

  6. K. Piotrzkowski More tomorrow…

  7. Two-photon physics MSSM: 100 fb-1 (no pileup) arXiv:0908.2020 Large rates for WW HPS240 only range More tomorrow…

  8. Optimal places for tagging Central Exclusive Production (CEP) at LHC: @ 220/240m and 420m from IP HECTOR: JINST 2, P09005 (2007) For nominal low-b LHC optics K. Piotrzkowski

  9. Forward proton detectors @ 420 m • Installation of Si detectors in cryogenic region of LHC, i.e. cryostat redesign needed • Strict space limitations rule out Roman Pot technology, use movable beampipe instead • Radiation hardness required of Si is comparable to those at SLHC, use novel 3-D Silicon technology • To control pile-up background use very fast timing detectors (s ~ 10ps) Acceptance: (At nominal LHC β* = 0.5 m) 0.002 < ξ < 0.02 Two detector stations per arm (4 in total): each station contains tracking and timing detectors K. Piotrzkowski

  10. Moving Hamburg pipe concept Successfully used at HERA: Robust and simple design, + easy access to detectors Motorization and movement control to be cloned from LHC collimator design K. Piotrzkowski

  11. Moving pipe: Detector ‘pockets’ In preparation for beam tests: Thin 300 mm entrance and side windows by electro-erosion K. Piotrzkowski

  12. Hamburg moving beam pipe prototype UCLouvain • Two pockets laser welded ready for test beam

  13. Picosecond ToF detectors At nominal luminosity event rate so high @ FP420 that accidental overlays (= interesting event in central detector + two protons from single diffraction) become major background! Use very fast ToF detectors to reduce it by matching z-vertex from central tracking with z-by-timing from proton arrival time difference: LHC vertex spread is ~50 mm to reduce significantly backgrounds one needs ~10 ps time resolutions (  2 mm z-vertex resolution)! • Developed very fast timing detectors: Cerenkov radiators + fastest MCP-PMTs • Very challenging environment  pushing MCP-PMT performances to the limits: • High event rates, up to several MHz • Running MCP-PMTs close to maximal anode currents • Large annual total collected anode charges (~10 C/cm2!) • GasToF: Gas (C4F10) Cerenkov detector with very fast light pulse (< 1 ps!)  resolution limited by TTS of MCP-PMTs and electronics • Quartic: Quartz based Cerenkov with fine segmentation – multi-hit capability • Going beyond requires new ideas: sub-picosecond streak cameras?? K. Piotrzkowski

  14. GasToF: Cosmic-ray tests Resolution < 20 ps for 1 p.e.! K. Piotrzkowski

  15. Proton fluence at FP420 HECTOR Very high fluence due to protons in single diffraction: Distribution of protons @ FP420 in lateral plane: • Small area detectors needed (~several cm2) • At nominal luminosity large event rates expected ~10 MHz !! • Total fluence of protons > 1015 / cm2 K. Piotrzkowski

  16. Reconstruction: Chromacity grids HECTOR • Basic principle: • Three initial variables(position+angle+energy) and two measured (position+angle) assume nominal vertex position (x=0) • (Horizontal and vertical planes independent) • In each arm (and plane) position and angle @ HPS give energy loss and scattering angle @ IP • 10 mm per point and ~10 m lever arm results in about 2.10-4 energy resolution! K. Piotrzkowski

  17. Calibration with exclusive di-muons CMS thesis: X. Rouby ~ 700  events in 100 pb-1 (single-interaction data @ 14TeV) pp  pp l+l- • Nearly pure QED process • Calibration/alignment of FP420 detectors • (about 40% protons detected!): • Expected resolution of x=Eg/E is ~5.10-6 ! Calibration procedure itself can be very well controlled using Upsilon signal! BOTTOMLINE: Exclusive low-mass dimuons crucial for FP420 K. Piotrzkowski

  18. Forward proton acceptance @ b* = 0.5 m HECTOR: JINST 2, P09005 (2007) To detect forward protons for CEP of light Higgs (Mh ~ 120 GeV) one needs FP420 detectors; Note: Acceptance is mostly driven by energy loss NOT scattering angle (pT) HPS240 essential for triggering + efficiency for HPS240+HPS420 ~ 2 x HPS420 only K. Piotrzkowski

  19. HPS proposal: Adding HPS240 detectors • Tagging at 420m and 240(220)m is complementary – together ~ 0.2-10% energy loss range is covered ! • This leads to significantly higher tagged cross sections • Both 220 and 240 m locations are ‘warm&free’ – just bare beam-pipes • At IP5, locations at 220 m are occupied by TOTEM -> go 240m (as ALFA in ATLAS) - it is still possible to send triggers to CMS! • One does not need to modify the LHC beamline -> can be done before HPS420 and be treated as a proof-of-principle project (= use FP420 detector concepts) + interesting physics with HPS240 only !! K. Piotrzkowski

  20. HPS acceptance with newest LHC optics b* = 0.55 m N. Schul & J. de Favereau Note: 2 and 4 mm approach assumed for HPS 240 and 420 (introduce some shadowing) K. Piotrzkowski

  21. HPS acceptance with newest LHC optics b* = 0.55 m Note: Acceptance for pp  pXp changes when central system X is constrained - here |rapidity(X)| < 1.5 N. Schul & J. de Favereau Using two-photon spectra! Realistic case: 2.5 mm approach of HPS240 and 0.5 mm dead edge (=2mm physical approach) K. Piotrzkowski

  22. LHC beam-line close to 240 m TOTEM Available space of ~12 m! • From Detlef: • Space above quench resistors (QRs) is not reserved yet • Space between QR and beam pipe ~ 25 cm, and space between QRs ~ 50 cm • No problem of heat load K. Piotrzkowski

  23. Taken on 14/1/2009 CMS Q6 ~240m from IP5 Quench resistors To alcove K. Piotrzkowski

  24. HPS420 ~250m K. Piotrzkowski

  25. HPS: Staging HPS requires original and challenging detector solutions – novel mechanical concept (= moving pipe 1st used at HERA) + pico-second resolution ToF detectors HPS420 detectors are essential for Higgs detection but require significant LHC beam-line modification (2 New Connection Cryostats for Point 5)  long shutdowns and significant costs HPS240 detectors are important since can provide L1 signals and installation require minimal intervention to LHC (NB: HPS detectors are ‘like’ a couple of new collimators, among 100…) Stage 0: Proof-of-principle experiment In close collaboration with LHC groups develop moving pipes ready for installation @240 m; test ToF detectors + associated electronics K. Piotrzkowski

  26. HPS: Staging Stage 0: Proof-of-principle experiment Demonstrate in-situ performance of timing detectors (resolutions, resistance to backgrounds, etc) ; learn to operate near-beam detectors; characterize backgrounds etc. Stage 1: HPS240 for CMS Add simple trackers based on CMS barrel pixels + L1 trigger detectors; after integration of all detectors into CMS DAQ start unique studies – search for exclusive production of SUSY pairs, stringent tests of SM gauge boson sector, for example . Stage 2: Final HPS configuration Hunt for exclusive Higgs can start using ultimate detectors – new trackers and timing detectors (Note HPS stage 2 as ‘test-bench’ for CMS phase 2 DAQ/tracker + HPS420 in L1 is possible in phase 2!) K. Piotrzkowski

  27. Stage 0 and 1 for HPS240 • Stage 0/1: As final stage of moving pipe R&D install (in 2011?) first station with fast timing detectors + position hodoscopes • Stage 1: After HPS approval, install two HPS240 stations (in 2012-13?) with tracking based on modified CMS pixel sensors • Note: Good resolution in energy loss expected already for rather poor detectors – eg. For 100 um spatial resolution expect about 2% energy resolution for a 300 GeV loss! • Essential exercise for the final HPS design – handling of backgrounds, operation aspects + first (tagged) physics • First bremsstrahlung measurement in pp (HPS240 +ZDC) – large cross-section – can use for fast calibration of BOTH ZDC and HPS240 (?) • NOTE: Stage 1 HPS is low cost project – can be done ‘quickly’ ! K. Piotrzkowski

  28. LHC Plans as announced at HCP conference, Evian, Nov 20 K. Piotrzkowski

  29. LHC Plans as announced at HCP conference, Evian, Nov 20 K. Piotrzkowski

  30. Summary/Outlook • CMS HPS is (rather) small but very challenging project at the LHC • The FP420 R&D report published, is basis of the HPS proposal • • The R&D (first) phase ends with a complete new connection cryostat design and a pre-prototyped, tested concepts for high precision near-beam detectors at LHC • • Physics case for forward proton tagging spans the central exclusive • Production (exclusive di-jets and Higgs boson!) and ggand photon-proton physics; • If running early enough (stage 1!) give access to diffractive physics, gap survival /underlying event studies….. • • For relatively low incremental cost, forward proton detectors add significant physics potential to CMS with no effect on the operation of the LHC. • You Are Welcome to Join K. Piotrzkowski

  31. Extra slides K. Piotrzkowski

  32. HPS acceptance with newest LHC optics b* = 0.55 m N. Schul & J. de Favereau Using two-photon spectra! Note: 2mm approach introduce some shadowing of HPS420 K. Piotrzkowski

  33. HPS acceptance with newest LHC optics b* = 0.55 m Note: Acceptance changes when central system X is constrained - here |rapidity(X)| < 1.5 K. Piotrzkowski

  34. 2.5 mm approach no dead edge K. Piotrzkowski

  35. SUSY case with pileup Contribution to SUSY’09 arXiv:0910.0202 [hep-ph]

  36. (Light) SUSY case arXiv:0806.1097 [hep-ph] Forward detectors crucial for kinematics reconstruction (charged dilepton states only!): Unique contribution! HPS240 accepts about 50% events !!

  37. Supersymmetric signals at high L N. Schul at SUSY’09: Assume 10 ps resolution on each proton K. Piotrzkowski

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