Novel detector concepts for e + e − physics Philipp Roloff (CERN) 7 th Detector Workshop of the Helmholtz Alliance "Physics at the Terascale"
The International Linear Collider (ILC) e + e - collisions at high energies → linear accelerators • Based on superconducting RF cavities (like XFEL → ≈10 % prototype) • Gradient: 32 MV/m • Energy: 500 GeV, upgradable to 1 TeV • Luminosities: few 10 34 cm -2 s -1 Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 2
The Compact Linear Collider (CLIC) • Based on 2-beam acceleration scheme • Operated at room temperature • Gradient: 100 MV/m • Staged construction: ≈375 GeV up to 3 TeV • Luminosities: few 10 34 cm -2 s -1 Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 3
Linear collider physics landscape Excellent physics program guaranteed at 250/350 GeV: • Properties of the Higgs boson • Top physics (including threshold scan) • Precision EW and QCD measurements Discovery potential for New Physics: • Direct pair production of new particles example SUSY → mass reach up to √s/2 scenario from • Indirect searches up to scales far CLIC CDR beyond √s (typically up to tens of TeV) Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 4
Higgs physics At 250/350 GeV: Measurement of σ(HZ) using recoil method → model independent extraction of the Higgs couplings (only possible at lepton collider) At high energy: • WW fusion dominates → large samples • Extraction of the Higgs self-coupling • top Yukawa coupling from ttH events (maximum around 800 GeV) Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 5
Physics aims → detector needs (1) Momentum resolution: σ ( p T ) − 5 GeV − 1 ∼ 2 × 10 (e.g. Higgs recoil mass, H → μ + μ - , 2 p T leptons from BSM processes) Higgs recoil mass at 500 GeV H → μ + μ ‒ at 3 TeV Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 6
Physics aims → detector needs (2) Jet energy resolution: σ ( E ) ≈ 3 - 4% (ILC) ≈ 5 - 3.5% for jets in the range 50 GeV - 1 TeV (CLIC) E Example: W/Z separation (important for many physics processes): 3.5% jet energy resolution → 2.5σ separation perfect 2% 3% 6% Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 7
Physics aims → detector needs (3) Impact parameter resolution: σ( d 0 )= √ a 2 + b 2 ⋅ GeV 2 /( p 2 sin 3 θ) ,a ≈ 5 μ m ,b ≈ 10 − 15 μ m hit resolution multiple scattering → excellent flavour tagging performance Example: branching rations for H → bb/cc/gg (cc and gg not possible at LHC) Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 8
Particle Flow reconstruction (1) Composition of a typical jet: Typical jet composition: • 60% charged hadrons • 30% photons • 10% neutral hadrons Traditional approach: • Measure all jet components of jet in the calorimeters: → 70% of jet measured in HCAL: σ E / E ≈ 60% / √E[GeV] γ n π + → Intrinsically poor HCAL resolution limits jet energy resolution E jet = E ECAL + E HCAL Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 9
Particle Flow reconstruction (2) Particle Flow approach: Try to measure the energies of individual particles • charged particles: tracking detectors • photons: ECAL (σ E / E ≈ 20% / √E[GeV]) • neutrals: HCAL Only 10% of jet energy from HCAL E jet = E track + E γ + E n → improved jet energy resolution Particle Flow Calorimetry = Hardware + Software Hardware: resolve energy deposits from different particles → highly granular calorimeters Software: identify energy deposits from each individual particles → sophisticated reconstruction software Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 10
ILC detector concepts Designed for Particle Flow Calorimetry: • high granularity calorimeters (ECAL and HCAL) inside solenoid • low mass trackers → reduce interactions / conversions ILD (International Large Detector): SiD (Silicon Detector): • TPC+silicon envelope (radius: 1.8 m) • Silicon tracking (radius: 1.2 m) • B-field: 3.5 T • B-field: 5 T Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 11
CLIC detector concepts Based on ILC designs, adapted and optimised to the CLIC conditions: • Denser HCAL in the barrel (Tungsten, 7.5 λ) • Redesign of the vertex and forward detectors (backgrounds) • Precise timing capabilities of most subdetectors CLIC_ILD CLIC_SiD Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 12
Vertex detectors (CLIC_)SiD: 5 (4) single layers in barrel (endcaps) (CLIC_)ILD: 3 double layers Innermost layer: R ≈ 15 mm (ILC), R ≈ 30 mm (CLIC) example: SiD interaction region Main requirements: • very low mass (≈0.2% X 0 per layer incl. support and cooling) • 3 – 5 μm single hit resolution • time slicing with ≈10 ns accuracy for CLIC → see later Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 13
Sensor technologies overview Monolithic 3D-integrated Hybrid Examples MAPS, FPCCD, DEPFET, SOI, MIT-LL, Tezzaron, Timepix3/CLICpix HV-CMOS Ziptronix Technology Specialised HEP Customized niche industry Industry standard processes processes, r/o and processes, high density for readout; depleted high-res. sensors integrated interconnects btw. tiers planar or 3D sensors Interconnect Not needed SLID, Micro bump bonding, Cu pillars, TSVs Granularity down to 5 μm pixel size ~25 μm pixel size Material budget ~50 μm total thickness achievable ~50 μm sensor + ~50 μm r/o Depletion layer partial partial or full full → large+fast signals Timing Coarse Coarse or fast, depending Fast sparsified readout, (integrating sensor) on implementation ~ns time slicing possible R&D examples ILC, ALICE, RHIC, Belle II ILC, HL-LHC CLIC, ATLAS-IBL, HL-LHC Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 14
Tracking systems SiD: all silicon tracker ILD: TPC and silicon trackers • one stereo strip layer outside • 5 barrel layers, only axial TPC (SET, ETD) measurement • two stereo strips inside TPC (SIT) • 4 disks, stereo layers • 220 space points in TPC → see talk by Marcel Stanitzki → see talks by Astrid Münnich and Jochen Kaminsky Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 15
Calorimeters ECAL: • Absorber: tungsten • Active layers: silicon or scintillator HCAL: • Absorber: iron or tungsten (barrel for CLIC) • Active layers: scintillator, different digital technologies (RPC, GEM, MicroMegas) Comprehensive R&D program for imaging calorimetry within the CALICE collaboration → see talks by Eva Sicking and Frank Simon Forward calorimetry → see talk by Wolfgang Lohmann Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 16
Background suppression at CLIC Triggerless readout of full bunch train: During bunch train: 3.2 γγ → hadrons interactions per BX (every 0.5 ns) → pile-up in calorimeters t 0 of physics event and trackers tCluster 1.) Identify t 0 of physics event in offline event filter • Define reconstruction window around t 0 • All hits and tracks in this window are passed to the reconstruction → Physics objects with precise p T and cluster time information 2.) Apply cluster-based timing cuts • Cuts depend on particle-type, p T and detector region → Protects physics objects at high p T Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 17
Time windows and hit resolutions at CLIC Used in the reconstruction software for CDR simulations: • CLIC hardware requirements • Achievable in the calorimeters with a sampling every ≈ 25 ns Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 18
Impact of the timing cuts e + e - → tt at 3 TeV with background from γγ → hadrons overlaid 1.2 TeV background 100 GeV background in the reconstruction after timing cuts window Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 19
Hadronic final states at CLIC Chargino and neutralino pair production at 3 TeV: 82% 17% Reconstruct W ± /Z/h in hadronic decays → four jets and missing energy Precision on the measured gaugino masses (few hundred GeV): 1 - 1.5% Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 20
If you want to know more... ILC Technical Design Report (TDR) CLIC Conceptual Design Report (CDR) Volume 4: Detectors Volume 2: Physics and Detectors arXiv:1306.6329 arXiv:1202.5940 Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 21
Summary and conclusions • The physics program at linear colliders like the ILC or CLIC requires detectors with: - high momentum resolution - excellent jet energy reconstruction - precise beauty and charm tagging • The (CLIC_)ILD and (CLIC_)SiD detector concepts are designed to meet these requirements using: - low-mass vertex detectors with small pitch - high-resolution main trackers - imaging calorimeters and particle flow reconstruction • Precise timing capabilities are needed in addition to cope with the experimental conditions at CLIC Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 22
Backup slides Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 23
Overview of physics reach Indicative discovery reach: Detector concepts for e + e − physics 06/03/2014 Philipp Roloff 24
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