CMS Upgrade Requirements and Upgrade Plans Hans-Christian Kästli, PSI CHIPP Workshop on Detector R&D

CMS upgrade plans /32 Contents Introduction & Motivation Part I: Subsystems –Trigger –Tracker –Calorimeters & Muon system –Common Projects Part II: Phase I barrel pixel upgrade Contains material from J. Nash, G. Hall, R. Horisberger

CMS upgrade plans /32 A realistic (?) upgrade scenario [J. Nash]

CMS upgrade plans /32 Requirements from Physics need to be at least as good as now Especially true for forward jet tagging and b-tagging p T resolution ok as is IP resolution ok, but need to be kept at this level at SLHC (radiation damage reduces tracker resolution)

CMS upgrade plans /32 Organisation

CMS upgrade plans /32 The CMS Experiment

TRIGGER

CMS upgrade plans /32 Triggers Level 1 trigger consists mainly of: Muon triggers from individual stations (local) Calorimeter triggers e/  isolated ECAL trigger towers, no HCAL energy  :isolated ECAL + HCAL trigger tower jets:ECAL + HCAL energy in cone Higher level trigger: Combine local muon to global muons Combine muon tracks with tracks from inner tracker to improve p T resolution Correlate calorimeter trigger with tracker information (e/  /QCD discrimination ) At SLHC most of these triggers at level 1 will exceed any realistic trigger rate.  There is a severe trigger problem for CMS at L=10 35 cm -2 s -1 !

CMS upgrade plans /32 Level 1 Trigger at SLHC (MHz)  and jet rates Problem: isolation of calorimeter towers Same problem for electron trigge Muon trigger rates Problem: insufficient p T resolution from muon system Level 1 trigger has no discrimination for pT>~20GeV/c

CMS upgrade plans /32 Level 1 Trigger at SLHC Guided from high level trigger at LHC: Muon system needs tracking information on level 1 Need trigger layers/trigger information from tracker p T measurement-> outer radius Need correlation between muon and tracker Electron trigger needs tracking information on level 1 Z-vertex information for cluster-track matching  rejection -> innermost tracking layers (conversion) Need correlation between calos and tracker  trigger needs tracking information on level 1 Jet rejection -> complete tracking Need correlation between calos and tracker  Tracking triggers absolutely needed But: cannot do everything. Need priorities and/or compromises Very challenging, only vage ideas around

TRACKER

CMS upgrade plans /32 LHC CMS has an all-Si tracker with – 3 pixel barrel layers – 10 strip barrel layers (4 stereo) – 2 pixel endcap disks – 3+9 strip enddisks (2+2 stereo) The expected performance is excellent as indicated on the right p T and transvers impact parameter resolution track reconstruction of hadrons in b-jets BUT: it is heavy! This shows up in the photon conversion rate, in the track reconstruction efficiency for pions and in the track fake rate Will become a problem in SLHC

CMS upgrade plans /32 Material Budget In very central region ~0.3 radiation length A lot of materials from cables in forward region!  In future difficult to bring the power in Support structure contributes a lot, but cannot gain much in inner part Except: fewer layers  less material, less power, less costs Why are there so many? Serious concern about pattern recogni- tion with so few points (unprecedented design and environment) Probably can be relaxed (although still no full simulation of loopers… and we haven’t seen data yet!!)

CMS upgrade plans /32 Going to SLHC 25 ns bunch structure

CMS upgrade plans /32 Tracking with 500 min bias events Study of current CMS tracker for Heavy Ion events Track density very similar to 50ns running –dn ch /d  /crossing ≈ 3000 –Tracker occupancy very high –Need more pixel layers/shorter strips Tracking is possible (thanks to pixel!) –When tracks are found they are well measured –Efficiency and fake rate suffer –CPU Intensive algorithmic efficiency o fake rate Momentum ResolutionImpact Parameter Resolution Pixel layers Inner layers of strips reach 30% occupancy on every xing!

CMS upgrade plans /32 Key Areas for Tracker R&D Reducing and delivering power at lower voltage… DC-DC conversion, serial powering …and removing it, with limited material CO 2 cooling, other cooling schemes Ensuring sufficiently rad hard sensors are available and establishing the manufacturing capability with industry A new readout & control system using modern technologies radiation hardness may be a minor point this time Developing components to build one or more layers which can contribute to the L1 trigger these layers must also be light and power-efficient Designing a tracker layout from these which will meet the physics objectives (last, but by no means least…)

CMS upgrade plans /32 Tracker related R&D Projects Proposal titleContact DateStatus CM S ref Letter of intent for Research and Development for CMS tracker in SLHC eraR Demina Approved06.01 Study of suitability of magnetic Czochralski silicon for the SLHC CMS strip tracker P Luukka, J Härkönen, R Demina, L Spiegel Approved07.06 R&D on Novel Powering Schemes for the SLHC CMS TrackerL Feld Approved07.01 Proposal for possible replacement of Inner Pixel Layers with aims for an SLHC upgradeA Bean Approved07.07 R&D in preparation for an upgrade of CMS for the Super-LHC by UK groupsG Hall Approved07.08 The Versatile Link Common ProjectF Vasey, J Troska11.07Received D detectors for inner pixel layersD Bortoletto, S Kwan12.07Received07.13 Proposal for US CMS Pixel Mechanics R&D at Purdue and Fermilab in FY08D Bortoletto, S Kwan12.07Received07.15 R&D for Thin Single-Sided Sensors with HPKM Mannelli7.2.08Received08.01 An R&D project to develop materials, technologies and simulations for silicon sensor modules at intermediate to large radii of a new CMS tracker for SLHC F Hartmann, D Eckstein Received08.02 Development of pixel and micro-strip sensors on radiation tolerant substrates for the tracker upgrade at SLHC M de Palma Received

CMS upgrade plans /32 Working Group Organisation These goals motivated the R&D structure active for months

CMS upgrade plans /32 Barrel Strawman Designs Superlayer Strawman A Geometry: Perturbation of current tracking system 4 Inner pixel layers, 2 strixel + 2 short strip layers (TIB), 2-strixel + 4 short strip layers (TOB) Short strips Strixel layers, could be doublets Pixel layers Mini-strip or Pixel doublets Strawman B Geometry: Design radically different from current tracker Super-layers, each with two doublet layers (integrated tracking/ triggering layers); 3 inner Pixel layers

CMS upgrade plans /32 Strawman B: triggering + local data reduction α High p T tracks point towards the origin, low p T tracks point away from the origin Use a pair of sensor planes, at ~ mm distance –Pairs of hits provide vector, that measure angle of track with respect to the origin –Keep only vectors corresponding to high p T tracks Stacks of 2 sensor pairs, at ~ cm distance –Redundancy –Track stub provides higher resolution local p T measurement  Two level data reduction But: Material budget? How light can we build this? Power? Triggering needed, but mustn’t geopardize tracking

CALORIMETERS & Muon System

Hadron Calorimeter CMS upgrade plans /32 Forward calo may be blocked by potential changes to the interaction region. This has a direct impact mainly in the case of looking for WW scattering Upgrade proposal for new trigger/DAQ readout –New SiPM with higher gain/less noise –Allows to - add timing information -make longitudinal segmentation to reduce sensitivity to min bias Both Calorimeters suffer degraded resolution at SLHC –affects electron ID, Jet resolutions

Electromagnetic Calorimeter CMS upgrade plans /32 ECAL –Crystal calorimeter electronics designed to operate in SLHC conditions –VPT in Endcap and Endcap crystals themselves may darken at SLHC Very difficult to replace –At SLHC, per Trigger Tower, per crossing, 12  expected (  rate in ECAL ~2.4 MHz/cm 2 ), ~3 GeV  No empty ECAL towers –The readout of every crystal is technically possible, by increasing the readout rate from 0.8 Gbits/s to 14 Gbits/s for 25 crystals.  full calorimeter information could be used in the level 1 trigger decision  Proposal by R. Rusack, Proposal for ECAL R&D (Phase II), DPG 27-FEB-08 Physics benefits arguable but definitely not proven Major effort to remove the supermodules, remove the LV cables and replace the front- end boards, check and re-install. Requires un-cabling of the tracker to remove the ECAL supermodules Radiation levels for all this work

Muon System CMS upgrade plans /32 System front end electronics look fairly robust at SLHC Cathode Strip Chambers/RPC Forward Drift Tubes /RPC Barrel Trigger electronics for the muon systems would most likely need to be replaced/updated –Some Electronics is “less” radiation hard (FPGA) –Coping with higher rate/different bunch crossing frequency –May have to limit coverage in  (  > 2) due to radiation splash This effect will be known better after first data taking, potential additional cost of chamber replacement

Infrastructure Modifications: Yoke CMS upgrade plans /32  Supplement YE4 wall with borated polythene  Improve shielding of HF PMT’s  possibility of increased YE1-YE2 separation to insert another detector layer?

COMMON PROJECTS

Common Projects CMS upgrade plans /32 There are many common R&D topics which must be pursued by ATLAS and CMS A Joint meeting was held last year to discuss possible joint R&D ACES meeting - Will repeat later this year Topics include Link Technology Versatile link project (CERN): rad hard physical network layer for optical links GBTproject (CERN): gigabit optical link for data/control/trigger ASIC technology 130nm technology Power distribution Funding from EU Rad hard DC-DC converter (CERN) Small contribution from PSI: on-chip DC-DC conversion Cooling Tests on CO2 cooling hosted by CERN cryolab Radiation/shielding issues

Part II Barrel Pixel System for Phase I

CMS upgrade plans /32 Phase 1 Tracker Upgrade In 2013 need to replace > 50% of pixel barrel modules & probably optical-links due to radiation damage. Pixel module fluence limit = 6x10 14 cm -2 (TDR) Barrel mechanics constructed for quick insertion/deinstallation Radiation damage & activation probably require a complete rebuild of barrel pixel Services (cables, fibres and cooling tubes) will have to be re-used. No replacements, no additions. Rest of tracker will be unchanged (long shutdown would be needed to access strip tracker)  PSI/UNIZ/(ETHZ) are interested in building a new barrel pixel detector for the phase I upgrade Several possible scenarios presented by Roland Horisberger: No official proposal yet.

Options for Barrel Pixel CMS upgrade plans /32 Option Cooling C 6 F 14 CO 2 Readout analog 40MHz analog 40MHz analog 40MHz analog 40MHz  -tw-pairs digital 320MHz  -tw-pairs digital 640 MHz  -tw-pairs Pixel ROC PSI46 as now 2x buffers 2xbuffer, ADC 160MHz serial 2xbuffer, ADC 160MHz serial Layer/Radii 4, 7, 11cm 4, 7, 11, 16cm Power as now DC-DC new PS Comment as 2008 Data loss reduction Large gain in material budget Simplifies module design Test structures designed Uunlikely for 2013 (services)

Option 0: Simple Replacement CMS upgrade plans /32 Pro : Data taking and physics output of CMS experiment is not disturbed Pixel detector is well calibrated, aligned, efficiencies are studied, algorithms are stable No big brainpower has to be drafted for rebuild  focus on physics output of CMS Time schedule and costs are likely under control Con: Rebuild detector conceived in 1997 Detector designed for Luminosity of 1x10 34 and will develop substantial inefficiency for 4cm layer at 2x10 34 We did a reasonable job in material budget (1.92%/Layer at  =0) but could be improved, especially in eta region Present pixel needs considerable algorithmic know how to deal with gain variability of optical chain and event decoding

Option 2: CO 2 cooling CMS upgrade plans /32 Use bi-phase CO 2 cooling and benefit from reduced material budget ! allows long cooling loops (~2-3m) with very small diameter pipes (~1mm) for thermal loads of ~100 W Present C 6 F 14 monophase has parallel cooling pipes with manifold and large diameter silicon hoses for feed and drain in front of FPIX tracking region. New CO 2 allows serialized pipes without pressure drop problems and therefore reduces resident cooling liquid by large factor. Density of liquid CO 2 is ~ 1.03 g/cm 3 compared to 1.76 g/cm 3 of C 6 F 14 Needs considerable engineering support from CERN for CO 2 cooling plant. C 6 F 14 cooling CO 2 cooling Material distribution budget for 3 barrel layers

Option 2: Weight of one half barrel CMS upgrade plans /32 BPIX now BPIX CO 2 cooling Empty mechanics : 1103 g 550 g ~94g, 1.5mm pipes 384 Module 2.27 g each 872 g same 384 Signal cable (21.7mg/cm) 167g same 384 Power cable (10.6 mg/cm) 82g same 384 Power plug (42 mg/plug) 16g same 32 Print (15.61g each) with red power cable 499g same Cooling (C 6 F 14 ) in tubes, manifolds & pipes 810 g 83 g 1.45mm pipes 2x1024mm Silicon tube + C 6 F 14 in side 372g 5 g serial piping Total 3921g 2274 g Average material budget gain 1.72, but in region  =1.4 – 2.3 much more

Option 3: Replacing Kapton signal cables CMS upgrade plans /32 use  -twisted pairs 2x125  m of enameled Copper Cladded Aluminum (CCA) wires could provide a viable signal cable alternative for Kapton cables Why? Kapton cable can only bend in one plane. O(1000) modules result in very complex, expensive, laboursome endflange prints, which contribute considerable in material budget in  range ~1.6 Kapton cable length limited to < 40cm & expensive Each 300  m plug is small & light, but ~800 soldered onto PCB with 21 traces in the sensitive tracking region are definitely not light ! Benefit? modules with long pigtail cables (~1.2m) allow transmission of analog output signals without impedance breaks. More freedom in bending cables in all directions Omit endflange print  no soldering, simpler mechanics endflange, no PCB, no strong mechanics supports of PCB for plugging forces Can move optical links with auxiliary chips further out (~50cm) to high  - range and remove material budget from sensitive tracking region

Option 3: Weight of one half barrel CMS upgrade plans /32 BPIX now BPIX CO 2 cooling Empty mechanics : 1103 g 550 g ~94g, 1.5mm pipes 384 Module 2.27 g each 872 g same 384 Signal cable (21.7mg/cm) 167g 14g 4x(2x125  ) CCA 384 Power cable (10.6 mg/cm) 82g 68g 5x250  CCA 384 Power plug (42 mg/plug) 16g 0g 32 Print (15.61g each) with red power cable 499g 32g radial cables Cooling (C 6 F 14 ) in tubes, manifolds & pipes 810 g 83 g 1.45mm pipes 2x1024mm Silicon tube + C 6 F 14 in side 372g 5 g serial piping Total 3921g 1624 g Large material budget gain for  =1.4 – 2.3  forward impact parameter gain 2.4x

Summary and Conclusions CMS upgrade plans /32 Luminosity will increase gradually Due to radiation damage pixel needs to be replaced in 2013 anyway Aim for pixel re-design in Phase I Several options sketched with large gain in material budget possible within reasonable time scale/costs Phase II upgrade: Calo + muon system: minor upgrades needed Trigger: need tracking information on level 1 Tracker: completely new tracker needed to cope with high data rates. Extremely challenging project: Increasing channel number Must reduce power Must provide trigger information Should reduce material budget Have to reuse present services Time is short. Schedule has to be harmonized with ATLAS !

Backup slides

May 2008G Hall37 Geoff HallSLHC UG WG June Constraints on LoI & TDR submission dates come from several places.. Input to LoI preparation Input to TDR preparation NB “Remaining R&D” shows time left after “known” within R&D phase Examination will show this is an aggressive schedule When is t = 0? Examination will show this is an aggressive schedule When is t = 0?

Timescales Plan still seems a reasonable estimate, given 1 year shift Examples of a few predecessor activities –Prototyping of readout ASICs, including any needed for triggering –Development of sFEC, control system & sFED –Prototype sensors with major manufacturers –Provisional mechanical support design –Development and evaluation of prototype modules –Definition of cooling scheme –Definition and proof of power distribution scheme –Development of cost model, TDR cost estimate including establishing funding, preliminary negotiations with vendors –~ 6 months for TDR preparations and writing Submission of Phase II TDR ~ end 2012 –With approval and launch of approved construction project ~mid Possible LoI 2010 & Phase I TDR? May 2008G Hall

BPIX Options for 2013 replacement/upgrade Option ~1.6 Costs 4.5 MCHF 5.0 MCHF 5.4 MCHF 5.9 MCHF ~9.8 MCHF +0.4 MCHF Weight 3921 g 2274 g 1624 g 1267 g ~ 2400 g estimate Start Date Aug 10 Nov 09 Dec 08 not possible for 2013 Comments ROC wafers exist new ROC wafers 0.4 MCHF for CO 2 plant new ROC & TBM & HDI mod. pxFED & pxFEC DC-DC converters new LV Power Supplies