1. 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

2. New forward detectors: 2 Trento, 6/1/2010 K. Piotrzkowski JINST 4 (2009) T10001 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

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

4. HPS: Motivation Trento, 6/1/2010K. Piotrzkowski4 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); M H resolution of  2 GeV  direct limits on Higgs width Possibility of detecting H  bb mode Detection of SM Higgs boson requires (very) large luminosity  obs   fb  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.

5. Trento, 6/1/2010K. Piotrzkowski5 Observation of Exclusive Charmonium Production and  → μ+μ- in pp Collisions at √s = 1.96 TeV

6. Trento, 6/1/2010K. Piotrzkowski6 More tomorrow…

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

8. K. Piotrzkowski 6 HECTOR: JINST 2, P09005 (2007) For nominal low-  LHC optics HECTOR: JINST 2, P09005 (2007) For nominal low-  LHC optics Optimal places for tagging Central Exclusive Production (CEP) at LHC: @ 220/240m and 420m from IP Trento, 6/1/2010

9. Forward proton detectors @ 420 m Trento, 6/1/2010K. Piotrzkowski9 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 (  ~ 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

10. Moving Hamburg pipe concept Trento, 6/1/2010K. Piotrzkowski10 Successfully used at HERA: Robust and simple design, + easy access to detectors Motorization and movement control to be cloned from LHC collimator design

11. Moving pipe: Detector ‘pockets’ Trento, 6/1/2010K. Piotrzkowski11 Thin 300  m entrance and side windows by electro-erosion In preparation for beam tests:

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

13. Picosecond ToF detectors Trento, 6/1/2010K. Piotrzkowski13 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 (C 4 F 10 ) 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??

14. GasToF: Cosmic-ray tests Trento, 6/1/2010K. Piotrzkowski14 Resolution < 20 ps for 1 p.e.!

15. Proton fluence at FP420 Trento, 6/1/2010K. Piotrzkowski15 HECTOR Very high fluence due to protons in single diffraction: Distribution of protons @ FP420 in lateral plane:  Small area detectors needed (~several cm 2 )  At nominal luminosity large event rates expected ~10 MHz !!  Total fluence of protons    cm 2

16. Reconstruction: Chromacity grids Trento, 6/1/2010K. Piotrzkowski16 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  m per point and ~10 m lever arm results in about 2.10 -4 energy resolution!

17. Calibration with exclusive di-muons Trento, 6/1/2010K. Piotrzkowski17 pp  pp l + l - Nearly pure QED process Calibration/alignment of FP420 detectors (about 40% protons detected!): Expected resolution of x=E  /E is ~5.10-6 ! ~ 700  events in 100 pb -1 (single- interaction data @ 14TeV) CMS thesis: X. Rouby Calibration procedure itself can be very well controlled using Upsilon signal! BOTTOMLINE: Exclusive low-mass dimuons crucial for FP420

18. Forward proton acceptance @    m Trento, 6/1/2010K. Piotrzkowski18 HECTOR: JINST 2, P09005 (2007) To detect forward protons for CEP of light Higgs (M h ~ 120 GeV) one needs FP420 detectors; Note: Acceptance is mostly driven by energy loss NOT scattering angle (p T ) HPS240 essential for triggering + efficiency for HPS240+HPS420 ~ 2 x HPS420 only

19. Tagging at 420m and 240(220)m is complementary – together  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 !! HPS proposal: Adding HPS240 detectors 19 K. PiotrzkowskiTrento, 6/1/2010

20. HPS acceptance with newest LHC optics    m Trento, 6/1/2010K. Piotrzkowski20 Note: 2 and 4 mm approach assumed for HPS 240 and 420 (introduce some shadowing) N. Schul & J. de Favereau

21. HPS acceptance with newest LHC optics    m Trento, 6/1/2010K. Piotrzkowski21 Realistic case: 2.5 mm approach of HPS240 and 0.5 mm dead edge (=2mm physical approach) N. Schul & J. de Favereau Using two-photon spectra! Note: Acceptance for pp  pXp changes when central system X is constrained - here |rapidity(X)| < 1.5

22. Trento, 6/1/201022K. Piotrzkowski LHC beam-line close to 240 m TOTEM 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 Available space of  m!

23. Trento, 6/1/2010K. Piotrzkowski23 Taken on 14/1/2009  240m from IP5 Q6 CMS Quench resistors To alcove

24. Trento, 6/1/201024K. Piotrzkowski HPS420 ~250m

25. HPS: Staging Trento, 6/1/2010K. Piotrzkowski25 HPS requires original and challenging detector solutions – novel mechanical concept (= moving pipe 1 st 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

26. HPS: Staging Trento, 6/1/2010K. Piotrzkowski26 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!)

27.  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’ ! Stage 0 and 1 for HPS240 27 K. PiotrzkowskiTrento, 6/1/2010

28. K. Piotrzkowski28 LHC Plans as announced at HCP conference, Evian, Nov 20

29. Trento, 6/1/2010K. Piotrzkowski29 LHC Plans as announced at HCP conference, Evian, Nov 20

30. Summary/Outlook Trento, 6/1/2010K. Piotrzkowski30 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  and 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

31. Trento, 6/1/2010K. Piotrzkowski31 Extra slides

32. HPS acceptance with newest LHC optics    m Trento, 6/1/2010K. Piotrzkowski32 Note: 2mm approach introduce some shadowing of HPS420 N. Schul & J. de Favereau Using two-photon spectra!

33. HPS acceptance with newest LHC optics    m Trento, 6/1/2010K. Piotrzkowski33 Note: Acceptance changes when central system X is constrained - here |rapidity(X)| < 1.5

34. 2.5 mm approach no dead edge Trento, 6/1/2010K. Piotrzkowski34

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 Trento, 6/1/2010K. Piotrzkowski37 N. Schul at SUSY’09: Assume 10 ps resolution on each proton