LHC & ATLAS UPGRADES

Transcription

1 LHC & ATLAS UPGRADES Toronto Group Meeting Physics Case for LHC Upgrade LHC Issues General ATLAS Issues ATLAS Canada R&D R. S. Orr

2 Alors, c est fini! Et maintenant?

3 ATLAS Detector Systems Diameter Barrel toroid length Endcap end-wall chamber span Overall weight 25 m 26 m 46 m 7000 Tons

4 LHC Prospects Date for 7 TeV beam commissioning: July 2008 Initial physics run starts late 2008 collect ~10 fb -1 /exp ( cm -2 s -1 ) by end of 2009 Depending on the evolution of the machine collect fb -1 /exp ( cm -2 s -1 ) in 5-6 years time Already time to think of upgrading the machine Two options initially discussed/studied Higher luminosity ~10 35 cm -2 s -1 (SLHC) Needs changes in machine and particularly in the detectors Start change to SLHC mode some time Collect ~3000 fb -1 /experiment in 3-4 years data taking. Higher energy? LHC can reach s = 15 TeV with present magnets (9T field) s of 28 (25) TeV needs ~17 (15) T magnets R&D + MCHf needed Don t discuss today

5 LHC context in SLHC make be only game in town for a LONG time.

6 Physics Case for the SLHC The use/need for for the SLHC will obviously depend on how EWSB and/or the new physics will manifest itself This will only be answered by LHC itself What will the HEP landscape look like in 2012?? Rough expectation for the SLHC versus LHC Improvement of SM/Higgs parameter determination Improvement of New Physics parameter determinations, if discovered Extension of the discovery reach in the high mass region Extension of the sensitivity of rare processes

7 Indicative Physics Reach Ellis, Gianotti, ADR Units are TeV (except W L W L reach) hep-ex/ updates Ldt correspond to 1 year of running at nominal luminosity for 1 experiment PROCESS LHC 14TeV 100 fb -1 SLHC 14TeV 1000 fb -1 SLHC 28TeV 100 fb -1 LinCol 0.8 TeV 500 fb -1 LinCol 5 TeV 100 fb -1 Squarks W L W L 2σ 4σ 4.5σ Z Extra Dim (δ=2) q * Λ comp TGC (λ γ ) indirect reach (from precision measurements) Approximate mass reach machines: s = 14 TeV, L=10 34 (LHC) : up to 6.5 TeV s = 14 TeV, L=10 35 (SLHC) : up to 8 TeV s = 28 TeV, L=10 34 : up to 10 TeV

8 First step The Higgs at the LHC Discover a new Higgs-like particle at the LHC, or exclude its existence Second step SLHC Statistics Needed Measure properties of the new particle to prove it is the Higgs Measure the Higgs mass Measure the Higgs width Measure (cross sections x branching ratio)s Ratios of couplings to particles (~m particle ) Measure decays with low Branching ratios (e.g H µµ) Measure CP and spin quantum numbers (scalar particle?) LHC~1 good year of data Measure the Higgs self-coupling (H HH), in order to reconstruct the Higgs potential Make sure it really is Higgs

9 Higgs Self Coupling Measurements Once the Higgs particle is found, try to reconstruct the Higgs potential ~ λv m H 2 = 2 λ v 2 Djouadi et al. λ SM /2 <λ< 3λ SM /2 Too much backgr. Not possible at the LHC

10 Higgs Self Couplings LHC : σ (pp HH) < 40 fb m H > 110 GeV + small BR for clean final states no sensitivity SLHC : HH W + W - W + W - ± νjj ± νjj studied 6000 fb -1 S S/B S/ B m H = 170 GeV 350 8% 5.4 m H = 200 GeV 220 7% HH production may be observed first at SLHC: ~150 <M H <200 GeV -- λ may be measured with statistical error ~ 20-25% LC : precision up to 20-25% but for M H < 150 GeV ( s GeV, 1000 fb -1 )

11 Beyond the Standard Model New physics expected around the TeV scale Stabilize Higgs mass, Hierarchy problem, Unification of gauge couplings, Cold Dark Matter, Supersymmetry Extra dimensions SM Brane G G + Bulk + a lot of other ideas Split SUSY, Little Higgs models, new gauge bosons, technicolor, compositness,..

12 SUSY : Discovery Reach Discovery reach for squarks/gluinos ATLAS 5σ discovery curves Time mass reach 1 month at ~ 1.3 TeV 1 year at ~ 1.8 TeV 1 year at ~ 2.5 TeV 5 σ discovery reach m ( ~ q), m ( ~ g) LHC 2.5 TeV SLHC 3 TeV

13 SUSY Higgses h,h,a,h ± Heavy Higgs observable region increased by ~100 GeV at the SLHC. Green region only SM-like h observable with 300 fb -1 /exp Red line: extension with 3000 fb -1 /exp Blue line: 95% excl. with 3000 fb -1 /exp

14 Time Scale of an LHC upgrade Jim Strait, 2003 time to halve error integrated L radiation damage limit ~700 fb -1 L at end of year ultimate luminosity design luminosity Life expectancy of LHC IR quadrupole magnets is estimated to be <10 years due to high radiation doses Statistical error halving time exceeds 5 years by it is reasonable to plan a machine luminosity upgrade based on new low-β IR magnets around ~

15 Machine Upgrade in Stages PushLHC performance without new hardware luminosity 2.3x10 34 cm -2 s -1, E b = TeV LHC IR upgrade replace low-β quadrupoles after ~7 years peak luminosity 4.6x10 34 cm -2 s -1 low-β quadrupoles plus dipoles, plus crab cavities. peak luminosity 15.5 x cm -2 s -1 LHC injector upgrade peak luminosity 9.2x10 34 cm -2 s -1 LHC energy upgrade E b TeV (15 24 T dipole magnets)

16 Beam-Beam Limit Luminosity Equation injector upgrade ( γε ) f ( ) 1 L πγ nb Q + ϕ F r LHC + injector changes rev * bb p β IR upgrade profile LHC+ injector changes

17 Nominal Crossing Angle at the edge F φ 1 = ; φ 2 1+ φ θ σ c 2σ x z Piwinski angle luminosity reduction factor nominal LHC

18 Summary of Luminosity Upgrade Scenarios for L 10 cm s with acceptable heat load and events/crossing * 25-ns: push β to limit Slim magnets inside detector? Crab Cavities High Gradient, Large Aperture Nb3Sn Quads 50-ns: Fewer bunches, higher charge NbTi Realizable with Beam-Beam tune shift due to large Piwinski angle? * Luminosity leveling via bunch length and β tuning

19 Early Separation (ES) ultimate LHC beam (1.7x10 11 protons/bunch, 25 spacing) squeeze β* to ~10 cm in ATLAS & CMS add early-separation dipoles in detectors starting at ~ 3 m from IP possibly also add quadrupole-doublet inside detector at ~13 m from IP and add crab cavities (φ Piwinski ~ 0) new hardware inside ATLAS & CMS detectors, first hadron crab cavities D0 dipole optional Q0 quad s stronger triplet magnets small-angle crab cavity ultimate bunches + near head-on collision

20 ES Scenario merits: most long-range collisions negligible, no geometric luminosity loss, no increase in beam current beyond ultimate, could be adapted to crab waist collisions (LNF/FP7) challenges: D0 dipole deep inside detector (~3 m from IP), optional Q0 doublet inside detector (~13 m from IP), strong large-aperture quadrupoles (Nb 3 Sn) crab cavity for hadron beams (emittance growth), or shorter bunches (requires much more RF) 4 parasitic collisions at 4-5σ separation, low beam and luminosity lifetime ~β*

21 Large Piwinski Angle (LPA) double bunch spacing to 50 ns, longer & more intense bunches with φ Piwinski ~ 2 β*~25 cm, do not add any elements inside detectors long-range beam-beam wire compensation novel operating regime for hadron colliders larger-aperture triplet magnets wire compensator fewer, long & intense bunches + nonzero crossing angle + wire compensation

22 LPA Scenario merits: no elements in detector, no crab cavities, lower chromaticity, less demand on IR quadrupoles (NbTi expected to be possible), could be adapted to crab waist collisions (LNF/FP7) challenges: operation with large Piwinski parameter unproven for hadron beams (except for CERN ISR), high bunch charge, beam production and acceleration through SPS, larger beam current, wire compensation (almost established),

23 Principle of Early Separation Stronger focusing with cancellation of the geometrical luminosity loss Full Early Separation (50 ns only if D0 not in inner detector) D0 First encounter D0 Partial Early Separation (25 or 50 ns) D0 25ns preferred by ATLAS D0 is just in front of FCal First encounter D0 We need a residual crossing angle

24 Possible locations in ATLAS A B C D Stay out of A B,C possible location of D0, but need more calculations to avoid to damage the muon system D possible location of Q0 or D0, probably the least problematic one

25 Detectors: General Considerations LHC SLHC s 14 TeV 14 TeV L Bunch spacing t 25 ns 25/50 ns σ pp (inelastic) ~ 80 mb ~ 80 mb N. interactions/x-ing ~ 20 ~ 300/400 (N=L σ pp t) dn ch /dη per x-ing ~ 150 ~ 2000/2500 <E T > charg. particles ~ 450 MeV ~ 450 MeV Tracker occupancy 1 10/20 Pile-up noise in calo 1 ~9 Dose central region 1 10 Normalised to LHC values Gy/year R=25 cm In a cone of radius = 0.5 there is E T ~ 200GeV. This will make low E t jet triggering and reconstruction difficult.

26 Detector Upgrade ATLAS has begun studying what needs to be upgraded for cm -2 s -1 instantaneous luminosity ~10 harsher pileup, radiation environment Also constrained by existing detector: what can be moved/stored where/when Major ID overhaul foreseen TRT replaced by Si Strips Pixels move to larger radius New technology for innermost layers Calorimeters New FE electronics for HEC New cold or warm FCAL Opening endcap cryostat implies a long installation schedule (~2-3 years) Schedule to fit 2016 timescale Aim for upgrade TDR in 2010 to allow adequate procurement/construction Also Trigger, FE in general, etc.. etc.. etc

27 LAr Calorimeters at slhc - Overview Critical issues ion build up and heat load The HiLum ATLAS Endcap Project Radiation hardness: R&D for HEC cold electronics;

28 FCal - Heatload EMEC HEC Neutron Shielding Pump Mini-FCal FCal V Strickland 300mm Simulation of LAr FCAL beam heating Maximum temperature 93.8K recently conclude unlikely that will LAr boil Improve FCAL cooling (open endcap cryostat)? ~2-3 year round-trip big timing challenge New warm FCAL plug? Main FCAL issue is Voltage drop on protection resistors

29 +ve Ion Buildup Distorts Electric Field limit limit EMEC and HEC OK FCAL: may go above 1 close to inner wall Turn off inner part of FCAL slhc Instal mini warm FCAL in front reduce energy deposited in FCAL1

30 HiLum ATLAS Endcap Project Goal: establish limitations on the operation of the endcap calorimeters (FCAL, EMEC, HEC) at highest LHC luminosities. R&D: 'mini modules of FCAL, EMEC and HEC type, each in one separate cryostat; IHEP Protvino: beam line # 23: from 10 7 up to p/spill; E= 60/70 GeV; Arizona, Dresden, JINR Dubna, Kosice, Mainz, LPI Moscow, MPI Munich, BINP Novosibirsk, IHEP Protvino, TRIUMF, Wuppertal.

31 FCAL module HiLum Test Modules 4 'standard' HEC gaps (HEC1) 4 read-out channels 4 HV lines (one per subgap)

32 Inner Detector Replacement Order of magnitude increase in Data rates, Occupancy, Irradiation No TRT Si strips Pixels moved to larger radius New technology for inner layers R&D required on sensors, readout, and mechanical engineering

33 Tracks silicon TRT P Nevski Preserve (improve?) tracking performance in SLHC environment Need to replace TRT: all-silicon ID Minimize material

34 Strawman Layout of Tracker b layer + 3 pixel layers Semi-projective gaps moderator η <2.5 2 long-strip layers (9cm) + stereo 3 short-strip layers (2.5cm) + stereo

35 Pixel-layer Technologies Harshest radiation environment (R~4cm) investigate new technologies 3D Si Highest signal - fabrication? Si pixel sensor BiCMOS analogue CMOS digital Thin silicon + 3D interconnects Conservative high voltage Integrated Grid (InGrid) Input pixel Cathode (drift) plane Cluster 1 Cluster2 Cluster3 Slimmed Silicon Readout chip 1mm, 100V 50um, 400V 50um Gas over thin pixel (GOSSIP) Diamond pixels Low material sparks? Rad hard, low noise, low current cost, signal, uniformity? May test in pre-slhc b-layer replacement (~2012)

36 Schedule Strawman & options fixed Dec 2006 ID R&D, conceptual design TDR Feb 2010 ID cooling PRR April 2010 Silicon sensor PRR July 2010 ID FE electronics PRR Oct 2010 b-layer replacement Ready 2012 Procure parts, component assembly Start surface assembly March 2012 Stop data taking Sep 2014 Remove old detectors, install new Data April 2016

37 Tracker Upgrade work in Canada Diamond Sensors Toronto, Carleton, Montréal, Victoria +.. Prove radiation tolerance of pcvd diamond pixel prototypes Industrialize bump-bonding FE electronics Mechanical structure Test beam program Electronics Carleton, UBC, York, TRIUMF +.. FE ASICS Si FE module controller Initially FPGA, Move to ASIC Contribute to system design develop expertise Backend (eg RODs) later in upgrade path TRIUMF Technical manpower

38 LHC Energy Doubler 14*14 TeV Dipoles: B nom =16.8T, B design =19T Superconductor 16T demonstrated at 4K 10 years for R&D, 10 years production 3G$ Nb Sn 3 LHC Energy Tripler 21*21 TeV Dipoles: B nom =25T, B design =29T Superconductor HTS-BSCCO or Well above demonstrated 20++ years for R&D,? years production?g$ Nb Sn 3 Nb3 Sn

39