1. The Upgrade of CMS for High Lumi LHC
Why?
How?
T. Camporesi, CERN EP Department

2. Setting the scene
Pileup 40-50
Pileup 50-60
Pileup >140

3. Future @ LHC Improved detectors Pileup 40-60 Pileup 140-200 100 fb-1
Today !
Improved detectors
Phase II
Upgrade
Ready 
Physics studies, R&D and prepare TDRs,
application for funding

4. Challenges @Hi-Lumi LHC
Highest Energies
Intense Beams
Pile up 20  50  200  complex analyses
Extreme radiation hardness of detectors
Extrems high readout rate (DAQ, Computing)
Forefront for technolgies and ingenuity: detectors, electronics, computing, analyses
extreme particle flow

5. High Lumi LHC challenges
High radiation level
High Pile-Up: ultimately
~200 concurrent collisions
per beam crossing
ttbar event with 140 PU collisions
3000 fb-1 Dose map in [Gy] simulated with MARS and FLUKA
Aging studies show that Tracker & End cap Calorimeters need replacement
Mantaining the detector performance in the harsh conditions of the LHC was a major consideration in the initial design of CMSand of the Phase-I upgrade. When one consider the annual dose devilered to the detectors per uyear in the HL-LHC era will be similar to the total dose of all operations from the beginning of the LHC program to the start of LS3, the magnitude become more clear.
MARS and FLUKA . Th edamage produced in the dtectors by this radiation varies from sub-detector to subdetector. For silicon detectors radiation prodces defects in the silicon lattice that change the bulk electrical proprieties of the silico. One conseguence is that the current leakage will increase. Only partial depletion will work in this stage and this bring to lower signal. At the HL-LHC, the PbWO4 scintalling cristal or plastic scillintaning tiles the main problem is the loss of trasmission of the media thorugh which the scintillation light must pass. This results in a reduction of the signal.
Annual dose in HL-LHC will be similar to total dose from LHC start to LS3
Aging studies show that Tracker & Endcap Calorimeters need replacement
GOAL: Maintain detector performance in the presence of higher pileup (PU)
Upgrade several detector components
 Redesign electronics, trigger and DAQ

6. CMS Phase II Upgrades Trigger/HLT/DAQ Barrel EM & hadronic calorimeter
Track information at L1-Trigger
L1-Trigger: 12.5 µs latency - output 750 kHz
HLT output ≃7.5 kHz
Barrel EM & hadronic calorimeter
Replace FE/BE electronics
Lower operating temperature (8∘C)
Replace scintillator layers
What will not change:
4Tesla Magnet and return yoke
Barrel and Endcaps muons chambers
Electromagnetic Barrel Crystal Calor
Barrel Hadron Brass/Scintillator calor
Hadron FWd calo (steel/quartz fibers)
Muon systems
Replace DT & CSC FE/BE electronics
Complete RPC coverage in region 1.5 < η < 2.4
Muon tagging 2.4 < η < 3
Endcap Calorimeters
rad. tolerant
high granularity
3D capability
Replace Tracker
Rad. tolerant - high granularity - significantly less material
40 MHz selective readout (Pt≥2 GeV) in Outer Tracker for L1-Trigger
Extend coverage to η = 3.8

7. Tracker upgrade Phase I tracker (≥2017) 1016 N/cm2
Integrated Neutron Equivalent fluence by end of LHC

8. Pt module concept (basis for self selected fast trigger info )
Tracker upgrade (II)
Pt module concept (basis for self selected fast trigger info )
Barrel
Endcap
Tracker (≥2025)
2S modules
PS modules
DD modules
EC Pixel
Barrell
Pixel
Outer
tracker
Inner
tracker

9. Tracker upgrade (II) Radiation Tolerance
Pt module concept (basis for self selected fast trigger info )
Barrell
Radiation Tolerance
Increased granularity (mitigate Pileup)
Improved two track separation (mitigate Pileup)
Reduced Material in Tracking volume
Robust Pattern recognition (notably for HLT)
Contribution to first level trigger
Extended acceptance
Endcap
Tracker (≥2025)
2S modules
PS modules
DD modules
EC Pixel
Barrell
Pixel
Outer
tracker
Inner
tracker

10. Outer Tracker: the building blocks
200mm thick sensors, n-in-p
2S module: stub reco efficiency before and after irradiation

11. Tracker mechanics
Outer tracker: First layer of the PS modules (including the outer tracker inner tubes)
Outer tracker: Double discs in the endcaps (each disc comprises two DEEs)
Inner Tracker PIxels

12. Tracker material
RUN2 tracker (≥2017)
Phase II tracker (≥2025)

13. Performance : Occupancy
Inner Tracker
Outer Tracker

14. Tracking trigger efficiency
Average track rate (Pt>3 GeV) for ttbar events and different pileup (even at highest pileup the rate can be fully handled by the L1 trigger logic

15. Efficiency

16. Vertexing

17. Vertex resolution
0.15 mm
10 microns

18. B-tagging
70% b eff
Very Fwd
Fwd
Barrel
1% background

19. Jet reco
Boosted W bosons

20. Endcap Calorimeter replacement

21. EndCap Calorimeter Design
Construction:
Hexagonal Si-sensors built into modules.
Modules with a PB backing plate and PCB readout board.
Modules mounted on copper cooling plates to make wedge-shaped cassettes.
Cassettes integrated into absorber structures at integration site (CERN)
Key parameters:
583 m2 of silicon, 487 m2 of Scintilllator
6M Si pads, 0.53 or 1.18 cm2 cell-size
25000 modules
92,000 front-end ASICS.
Power at end of life 115 kW.
Novel Approach to Calorimetry
with particle flow
All of this Unthinkable 10 years ago !
System divided into three separate parts:
EE – Silicon with Pb absorber – 28 sampling layers – 25 Xo + ~1.3 λ
EH – Silicon + Scintillator tiles with SS absorber
– 24 sampling layers – 9 λ
All are maintained at – 30oC.

22. FWD Calo layout
Silicon sensors: 3 different active thickness (300,200,120 mm) to match radiation dose in order to reduce leakage current. Baseline is p-type (n-on-p) sensors, possibly considering n-type (p-on-n) for the outer part ( lower n fluence) of the detector to save money.
Hexagonal sensors from 8 inches wafer (hex to optimize wafer surface usage) matched to PCB with holes for wire bonding
For the scintillator areas: tiles with SiPM mounted on the tile

23. FWD calo layout
Hadron part: mix of Scintillator tiles and Silicon

24. Calo assembly
Motherboard collecting modules info and distributing power
Sketch of a cassette showing the modules arrangement

25. EC Reconstruction

26. EC photon energy resolution
E in 26mm radius around shower axis
E in 53 mm radius around shower axis
300mm
200mm
120mm

27. … and Higgs
Both photons unconverted and in the endcap

28. Test beam results
Single layer ( at 6X0) energy and space resolution

29. Timing resolution
30 ps
Work is ongoing to develop full 4D reconstruction algorithms

30. Adding a 4th dimension
At HI Lumi LHC the dimension of the luminous region willhave an RMS of 200ps
Ability to time physics objects precisely allows association to primary vertex and rejection of Pileup
CMS Phase 2 upgrade aims to achieve high precision timing measurements
In ECAL barrel: new electronics to achieve ~30 ps resolution for 30 GeV photons
In Forward calo : design to achieve ~50 ps timing resolution per layer in EM showers, potential to time jets
studying additional detectors for MIP timing to cover large fraction of charged particles in the event
A thin LYSO + SiPM layer in the barrel,
LGAD layer in the endcap: ~30 psec MIP timing up to |η|<3.0

31. Muon upgrade Measure local bending more precisely
Upgrade electronics readout to cope with increased trigger rate
Add additional GEM based chambers to improve resolution (Important at trigger level to reduce rate!) in area where filed is weaker

32. Muon upgrade performance
Trigger rates
Efficiency with ideal and with some extrapolation about detector aging

33. Timeline

34. Summary LHC and the experiments are performing beyond expectations
The research program is extremely rich:
so far the initial measurements of the SM parameters in the new energy ranges have been performed. The recent breakthrough in the theoretical calculations are going to stimulate higher precision measurements
The search for new physics has been the main focus of the PP experiments… No success so far, but we have just started scratching the surface of the LHC potential
The future looks bright: the LHC performance is such that the estimates of Integrated lumi (which a couple of years ago were looking very optimistic) are realistic, and the experiments are collecting data effectively and producing high quality results
The long term future is challenging: we are now designing the experimental setup of the future: it is an opportunity for developing novel technologies to be able to exploit fully the physics that LHC can produce

35. Backup

37. Inner tracker

38. Inner tracker

39. A novel approach to calorimetry
Typical classical calorimeter: compact ‘tower like’ aiming to ‘absorb’ the shower and measure its energy integrated over the shower development , possibly with a few ( <5) longitudinal sampling .Transverse size of tower ~ 1 Moliere radius
Sampling
Calorimeter
e.g. PbW04 crystals : 1 sampling , tower size ~2x2 cm
The dream: imaging calorimeter
Seeing the details of the shower development allows much better discrimination better e and hadron showers and also better resolution of close by showers caused by two separate particles

40. Some details about readout
sensors: three active thicknesses µm
0.5(1) cm2 pads for 100(200/300) µm

41. Vector Boson Scattering
VBS will be an area of measurement until the end of LHC
Besides a closure test of the Standard model is also one of the precision physics measurement with the highest potential to unveil BSM hints
It will give access to possible anomalous triple and quartic Gauge couplings
Longitudinal W scattering is the key verification to see if the Higgs alone is sufficient to regularize the possibly divergent cross section
Understanding the SM behaviour of VBS will also be a major asset in many searches which are using VBS production of new physics to beat down the backgrounds

42. Exploiting the TOP factory
Exploring the coupling of the Top to W, Z,H and analyze it in the framework of EFT deviations
improve precision of (differential) top quark production cross-sections, also in multiple dimensions, to constrain PDFs and to continue to be a driving force and testing ground for new improved higher-order QCD calculations and sophisticated new MC generators
look for rare production processes, such as tttt or even 6-top production
The staggering statistics can be appreciated if one thinks that at 3 ab-1 will have order of 108 events triggered with one top fully reconstructed and charge-tagged and can do
look for FCNC in rare decays such as t-->Zq , t-->Hq
Will have 107 W to t decays (can study lepton universality in W decays)
Can study W to charm decays
Study rare W decays
Have a sample of 108 charged tagged b hadrons

43. Higgs Physics precision
We want to go from this to this
But seeing new physics will be hard …

44. Higgs Physics precision
Differential distributions might reveal deviations: statistics (300 fb-1) will start probing expected values
Higher statistics will improve systematics understanding, allow better S/N selections etc.

45. Higgs Physics High sensitivity
High Pt might reveal surprises and is directly sensitive to production mechanism
Courtesy of M. Mangano

46. Higgs physics High sensitivity
Sensitive to Higher Dim operators

47. Discovery can come early …or late
Exploring SUSY model space
Explored:
9 different experimental signatures.
5 different types of SUSY models.
Exploring experimental signature space
There are scenarios where the full statistics of Hi Lumi LHC will be needed to reach 5s