LHC detector upgrade challenges

Transcription

1 LHC detector upgrade challenges Outline: Introduction LHC machine phase I and II -> overall detector limitations Phase I detector changes for ATLAS and CMS Phase II challenges, some examples LHCb and ALICE Plans (across phase I and II) Some final comments (organisation, summary) More information: Slides/plots from R.Garoby/L.Evans, N.Hessey, J.Nash, F.Muheim, J.P.Revol Links to LHCC upgrade meetings:

2 Detector Needs at SLHC Planning based on the assumption that it is well worth increasing the integrated luminosity of LHC by a factor 4-7, running well beyond 2020 Detector performance needs to be maintained despite the pile-up High-mass (~TeV) can tolerate some degradation; low backgrounds Electron ID and muons for W/Z, W'/Z', Higgs and SUSY Vertex, missing Et, pt resolution remain important, and efficiencies, for many channels of interest WW scattering (Higgs couplings or vector boson fusion) - needs forward jet trigger and central jet veto The current ATLAS and CMS ID detectors will fail around ( fb-1) Constructions of new IDs takes 6-7 years b-tag eff 2

3 Anticipated Peak and Integrated Luminosity Phase I Phase II Phase I Phase II Radiation damage limits: For inner layers around need to make changes For ID in general around independent of SLHC luminosity goal need to build completely new IDs Instantaneous (peak) luminosity: Some problems in but with changes in PIXEL region one can probably cope Very demanding to reach (SLHC) for many parts of the detectors (ID, trigger, some parts/aspects of calorimeters and muons, forward region, machine interface ) 3

4 Detector Plans Phase 1 Limited time for installation 6 to 8 months in 2012/13 shutdown Small increase in peak rate above previous estimates (2 --> 3 x ) Total integrated luminosity similar to previous expectations ~700 fb -1 Limited changes needed; some completion of detector coverage e.g. CMS muons CMS pixel detector is fast to replace Will replace at least the B-layer, and investigating substantial more ambitious plans to replace the whole pixel detector ATLAS pixel takes ~ 1 year to replace B-layer ATLAS will insert a new B-layer inside the current detector, along with a new smaller diameter beam pipe, in 2012/13 shutdown TDAQ Both experiments will continuously upgrade TDAQ to cope with rates and take advantage of new processing power CMS investigate track triggers at Level-1 with new pixel (see later related to phase II) ATLAS look at topological triggers combining different trigger elements, e.g. muon with no jet, and fast track finding (associative memory) at LVL2 4

5 Inner detectors - B-layers Both for phase I and II changes are needed, challenging for track density, radiation damage, SEU Read-out architecture and front-end chips under development 130 nm; low power; minimum pixel length; high data rates High power levels -> look at new cooling, including CO2 Lighter mass supports and services Sensors: current planar-si sensor technology is not rad-hard enough to survive to end of slhc. Either new sensors, or replace every few years 3D silicon, thin silicon, diamond, MPGD (Gossip) as alternatives Smaller beampipes --> b-layer closer to beam More generally for phase II Cheaper production more pixels? Lvl 1 Track trigger capabilities being considered (strips and/or pixels) Si pixel sensor BiCMOS analogue CMOS digital Integrated Grid (InGrid) Input pixel Cathode (drift) plane Cluster1 Cluster2 Cluster3 Slimmed Silicon Readout chip 1mm, 100V 50um, 400V 50um 5

6 Anticipated Peak and Integrated Luminosity Phase I Phase II Phase I Phase II Next slides - Phase II detectors: Conditions at SLHC Some key challenges: Machine interface and shielding PIXEL and Large Silicon Systems (complete ID changes) note again this is needed in any scenario of SLHC luminosity Calorimeters and Muon systems Trigger Electronics and Power 6

7 What are the conditions at SLHC? pile-up events at start of spill ( leveling (unless luminosity Want to survive at least 3000 fb -1 data taking B-layer at 37 mm: ~30 tracks per cm -2 per bunch crossing > MeV n-equivalent non-ionising Few 10s of MGray 7

8 LHC Evolution Phase II Several ideas being explored to see the best way to achieve 10 x nominal in 2017 Injector improvements higher current, higher reliability, shorter fill time New machine elements and ideas: Magnets inside the experiments for Early Separation schemes Crab cavities Luminosity Leveling Machine elements inside detector volume not easy increased background, and they weaken the shielding 8

9 Beam-pipe and shielding All-Be beam pipe reduces muon BG considerably Expensive beampipe, but much cheaper than new muon chambers CMS consider more shielding to η = 2 Add borated polythene; better shielding of PMTs 9

10 Pixel Systems A new generation of systems likely to be needed, building of experience from phase I upgrades Technologies mentioned earlier will continue to develop Read-out architecture and front-end chips High power levels -> look at new cooling, including CO2 Lighter mass supports and services? Cheaper production more pixels? CMS ATLAS 10

11 Large silicon strip systems 11

12 Large scale silicon systems The most critical parts are the sensors, ASICs and system engineering (mechanics, power, cooling, assembly, etc) To develop and buy silicon sensors for several hundreds of m 2 silicon sensors, with finer granularity than for LHC, is not an easy task, for example (from a CMS presentation about upgrade R&D Gino Bolla): Extend previous studies from LHC to SLHC fluence large irradiation programs needed Extend previous studies to include n-on-p (can operate not fully depleted after irradiation) Extend previous Multi-Geometry studies to substrate thickness less than or equal the pitch Strip/Pixel capacitance (back-plane, inter-strip/pixel & total) Critical fields, depletion and break-down voltage Sensor functionality (charge collection efficiency etc) Detailed design parameters for masks Extend previous studies to include MCZ and Epitaxial substrates Re-produce complementary sets of measurements and simulation Study biasing, guard rings, isolation methods Many of these considerations are related to developing a (few) reliable commercial partners for large orders and develop and validate their delivered sensors throughout the production 12

13 Electromagnetic Calorimeters Both ATLAS and CMS EM calorimeters should perform well at SLHC Pileup worsens the resolution a little, partially compensated by optimising the sampling New electronics can allow more flexibility in trigger; all (more) data read out Worst affected region is forward Remains important for WW- scattering triggers Steinar Stapnes SLHC detectors,

14 Electromagnetic Calorimeters: ATLAS LAr ATLAS forward calorimeter may suffer a number of problems: Boiling of LAr, ion build up between electrodes, voltage drop over HV resistor Studies underway; If these show action is needed, two solutions considered: Warm calorimeter in front of current calorimeter Open cryostat, insert complete new FCAL with smaller gaps and more cooling HEC ELECTRONICS HEC2 FCAL HEC1 14

15 Hadronic Calorimeters - CMS Most of the hadronic calometry is fine Forward region suffers: few towers blacked by SLHC (tower 1 ~ 4 % of original light output; tower 2 ( 23% ~ Also, machine magnets ( D0 ) block forward calorimetry Changes in readout, using SiPMs, being planned 15

16 Muon Systems CMS has a lot of shielding, rate probably OK for current chambers Need to see backgrounds to confirm; possibly η > 2 need changing, or limit trigger region New readout electronics? FPGA not rad hard enough ATLAS air core toroids have higher backgrounds; need to replace forward chambers (CSCs mainly) at nominal background. Very important to measure actual background to see how much of safety factor 5 is used up to see if significantly more needs replacing Both experiments are looking into improved shielding Difficult : current design is highly optimised Other possibility is to develop single chambers to do both triggering and precision read-out: thinner chambers leave more space for shielding 16

17 ATLAS Muon Chamber Replacement Range Depending on backgrounds, either minimal or very large fraction of ATLAS muon system needs replacing, unless backgrounds can be reduced ( luminosity (in relation to Both ATLAS and CMS have to wait for data 17

18 Muons - example of chamber R&D

19 Track trigger Inner Tracker Triggers at Level-1 Muon trigger rate ~constant above ~20-30 GeV/c; both ATLAS and CMS Current understanding is this is due to multiple scattering at CMS and width of RPC strips at ATLAS Cannot improve muon situation at CMS; difficult at ATLAS (new muon trigger (? resolution chamber layer with higher Several ideas to investigate Inner Tracker triggers (ASIC development demanding) Both Pt and vertex displacement triggers High momentum tracks are straighter so elements line up in nearby layers Search Window Pairs of stacked layers can give a P T measurement 19

20 Main Electronics Needs Readout chips The ATLAS and CMS Upgrades need new electronics throughout the detector: power supplies of calorimeters, data transfer and handling for all detectors; some cases highlighted below. Deep Sub Micron processes give new possibilities Read-out chips for pixels and strips, and also work on Controller chips and High speed data links Requirements Very challenging: rad hard, SEU tolerant, low analogue noise. Low power: number of channels increases by large factors between current and upgraded detectors. High data rates Summary of talk given by Paul O Connor in parallel session of ICHEP: Power dissipation is the major obstacle to further CMOS scaling. Foundry and mask costs going up as process options (multi-v th, multi-t ox, HBT, passives, etc.) added. Analog design is compromised by the low supply rail. NRE cost of ultra-scaled technologies becoming prohibitive for low-volume applications. Volume (wafers) Volume per project APV25 Atlaspix CMSPix HPTDC TrackerServic e Medipix AlicePixels HAL25 MGPA ADC41240 Fenix DiCaSy LHCBPix GOL ANN Dtmroc-s Beetle AliceTOF PascAm Preshower MPW11 20 CRTAll MPW15 MPW14 Plot from A.Marchioro

21 Powering From F.Faccio Need to supply ~ 50kW at 1-2 V hugely inefficient with large losses in cables (P=RI 2, so we end up introducing a large amount of copper) New detectors lower voltages in DSM processes, higher granularity we need to change approach and think new 21

22 Powering and data transfer Powering scheme Cannot have individual module LV no space, too much material DC/DC or serial very important; many possible schemes Look beyond the basic requirements of high power efficiency and low noise Safety: overcurrent, overvoltage, overtemperature Monitoring Can we avoid copper sense lines, e.g. local safety; local ADC; send DCS information along with data on fibre optics Data transfer High-speed electrical and optical links Calorimeters may want to read out all data to RODs: a lot of data better triggering capability How rad hard can we get optical links? Affects where we make the opticalelectronic transition in the ID Multiplexing and redundancy schemes Error correction schemes (SEU tolerance) 22

23 LHCb Upgrade Strategy LHCb Upgrade Phase 1 Upgrade all front-end detector electronics to 40 MHz readout by 2014, do not run in 2013 (Nov 2012 Mar 2014 with 12 months access) Run at 1x10 33 until Phase 2 shutdown Increase hadron data sample by factor ~10 Reach detector design lumi of ~20 fb -1 (except VELO) LHCb Upgrade Phase 2 Upgrade all detectors such that LHCb can operate at a luminosity of at least 2x10 33 during 18 months shutdown in 2017 Operate at highest possible luminosity for five years F. Muheim LHCC meeting CERN, 22/23 Sept 2008

24 Examples of detector changes: VELO VESPA VErtex LOcator replacement called VESPA Solution for first upgrade phase (2013) Keep mechanical structure and silicon strip sensors Replace FE chip with 40 MHz readout This device will be rad hard to ~20 fb -1 and will collect data until 2017 Solution for 2017 will be a complete overhaul Pixels/3D detectors better resolution lower occupancy Possible magnetic field to improve trigger by taking advantage of improved pattern recognition Remove bulky RF shield and replace with wires? Could use liquid N 2 cooling with cold fingers to create good vacuum, making VESPA a cryo-pump at the LHC F. Muheim LHCC meeting CERN, 22/23 Sept 2008

25 Scenario for ALICE Detector Completion (TRD, PHOS, EmCal, PMD), data taking/analysis; some maintenance Detector R&D and definition of upgrade plan (requires significant simulation effort, not possible so far) improvement of Inner Tracker System is a priority (move towards larger PIXEL system) Decision on upgrade, funding approval, etc Construction of new detectors Installation of upgraded detectors jpr/june 17,

26 VHMPID another example for ALICE Would be located on both sides of PHOS, below space frame; RICH-like detector with mirrors, Gas radiator (C4F10?) maximum length ~80cm; VHMPID Photon detector: MWPC with CsI photon converter and pad readout (current HMPID technology); Resistive Thick GEM ( 2 layers) with CsI photon converter (promising preliminary results). Dedicated trigger logic to select high p T use of TRD detector; 4 layer GEMs detector with algorithm selecting high p T particles (new trigger detector); use of EMCAL detector, opposite to beam line, triggering on high energy jets. 26

27 Planning and schedules Phase I upgrades will need their LoI, TDRs in The changes will be in the 2-5% range of original costs (depending on ambitions) The phase II changes are close to 40% of the existing detectors and it is foreseen to prepare LoIs, TPs in phase with the machine upgrade plans (TDRs for the various parts will follow as needed). A special problem with the IDs that have a long lead time, and are required in any scenario 27

28 Organisation and activities Typical Steering Groups and Projects Offices (linked to Technical Coordination) inside collaborations Cover overall organisation of the projects R&D projects covering specific topics (reviewed, open for all) Many activities covered by this (some shown earlier in these slides) Major workshops inside experiments and some times across Involves most groups in the collaborations Interacts with LHCC and has increased focus towards complete phase I and phase II plans SLHC-PP (FP7 project) is another element in the planning process 28

29 Summary There is every hope there will be a rich field of physics to explore at the LHC into the 20 s Collaborations focus more and more on the detector improvements needed to keep them running for long time (consolidation, phase I, phase II for the latter the changes needed are large) Phase-1 upgrade 2012 leading to 3 x cm -2 s -1 peak luminosity Need improved PIXEL systems mostly Phase-2 upgrade 2016 leading to 10 x cm -2 s -1 peak luminosity (restart in 2017) ID replacement and changes in most other detector systems - demanding LHCb and ALICE are also formulating upgrade programs And also for LHCb and ALICE focus is on higher rates and vertex systems A complete description of the phase II detector upgrades, taking into account early data taking experience, by