Introduction to the ATLAS Experiment at the LHC and its Upgrade for the High Luminosity LHC 24/10/14 • Introduction • The ATLAS Experiment • Detector Technologies – Phase-0 – Phase-I – Phase-II • Digression: ATLAS and the Higgs • Conclusions 1 Steve Lloyd ATLAS UK Collaboration Board Chair Queen Mary, University of London Phil Allport . ATLAS Upgrade Coordinator University of Liverpool UK ATLAS Institutions Birmingham Cambridge Edinburgh Glasgow Lancaster Liverpool Manchester Oxford Queen Mary, London Rutherford Appleton laboratory Royal Holloway, London Sheffield Sussex University College, London Warwick
Transcript
Introduction to the ATLAS Experiment at the LHC and its Upgrade for the High Luminosity LHC
24/10/14
• Introduction • The ATLAS Experiment • Detector Technologies
– Phase-0 – Phase-I – Phase-II
• Digression: ATLAS and the Higgs • Conclusions
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Steve Lloyd ATLAS UK Collaboration Board Chair Queen Mary, University of London
Phil Allport . ATLAS Upgrade Coordinator
University of Liverpool
UK ATLAS Institutions Birmingham Cambridge Edinburgh Glasgow Lancaster Liverpool Manchester Oxford Queen Mary, London Rutherford Appleton laboratory Royal Holloway, London Sheffield Sussex University College, London Warwick
The Large Hadron Collider at CERN
The Challenges • At the LHC, around 2800 bunches of 1011 protons circulate in each
direction in a 27km tunnel at energies approaching 7 TeV (7× 1012
eV) and collide every 25ns inside the LHC experiments. Each beam carries an energy 360MJ (the same kinetic energy as a TGV at 150km/h).
• In each bunch collision, there are typically multiple proton collisions with hundreds of particles going in all directions.
• The job of the detectors is to measure the path of each particle for each bunch crossing and determine its corresponding energy and momentum.
• Detectors often need to cope with many particles per cm2 (high particle fluxes), many different particle types (different masses etc) and constraints of cost, accessibility, high radiation levels over long operation periods, data transmission and data storage limitations
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• Usually a system of detectors is needed so that the different components have to perform their function while minimally interfering with the function of the other parts
• The requirements always push in the direction of improved position, time, energy and momentum resolution with clearer particle identification (or background rejection) and real-time pattern recognition and data processing
• At the same time many application demand affordable large area coverage
Particle Detectors • Tracking detectors focus on measuring the paths of all the charged particles to find their
energies (E), momenta (p) and charge (±), derived from linking the hits for each particle combined with additional information from other detector layers (which often also can see the neutral particles)
• A very powerful technique to measure momentum is to track in a known magnetic field where the curvature is proportional to 1/p.
• As the particle traverses the full detector system (including the tracker) the pattern of energy loss in different media provides information on the particle type (and therefore mass).
• Where massive detectors stop the particle entirely (electromagnetic and hadronic calorimeters) they directly provide E and also the energies and directions of the neutral particles. (In ATLAS ionization in liquid Ar with Pb, Cu or W absorbers is used for calorimetry except the for hadronic barrel based on steel and scintillator tiles)
• Muons, the main component of cosmic ray interactions at ground level, are very penetrating and for these charged particles, the identification comes from this property
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Join the dots and fit for curves (seen end-on) in a solenoid magnetic field
Particle Detectors • Tracking detectors focus on measuring the paths of all the charged particles to find their
energies (E), momenta (p) and charge (±), derived from linking the hits for each particle combined with additional information from other detector layers (which often also can see the neutral particles)
• A very powerful technique to measure momentum is to track in a known magnetic field where the curvature is proportional to 1/p.
• As the particle traverses the full detector system (including the tracker) the pattern of energy loss in different media provides information on the particle type (and therefore mass).
• Where massive detectors stop the particle entirely (electromagnetic and hadronic calorimeters) they directly provide E and also the energies and directions of the neutral particles. (In ATLAS ionization in liquid Ar with Pb, Cu or W absorbers is used for calorimetry except the for hadronic barrel based on steel and scintillator tiles)
• Muons, the main component of cosmic ray interactions at ground level, are very penetrating and for these charged particles, the identification comes from this property
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Join the dots and fit for curves (seen end-on) in a solenoid magnetic field
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ATLAS is a collaboration of 3000 physicists from 177 universities and laboratories in 38 countries
including 1000 PhD students (see cern.ch/ATLAS)
ATLAS: Inner Tracking Detectors 25
m
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25 m
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ATLAS: Inner Tracking Detectors
The ATLAS Pixel Detector • Three barrel layers:
• R= 5 cm (B-Layer), 9 cm (Layer-1), 12 cm (Layer-2)
• modules tilted by 20º in the Rφ plane to overcompensate the Lorentz angle.
• Two endcaps: • three disks each • 48 modules/disk
• Three precise measurement points up to η<2.5: • RΦ resolution:10 µm • η (R or z) resolution: 115 µm
• 1456 barrel modules and 288 forward modules, for a total of 80 million channels, 25ns beam crossing, total area of 17,000 cm2. • Temperature of -10 ºC given
dose of 1015n/cm2 (~1MGy) • 2 T solenoidal magnetic field.
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610,000 cm2 of silicon micro-strip sensors ~20,000 6×6 cm silicon detectors
ATLAS
Designed to record each separate collision at 40 million collisions per second. Measure where particles go with 10μm precision (15 million strips).
Has to withstand radiation of 1014neq/cm2 and 100kGy.
First 7 TeV Collision Event
2012 (8TeV running) Higgs candidate to 4 muons showing importance of forward tracking
ATLAS Silicon Strip Detectors
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This is where it goes
Physics Reach at the LHC
Cro
ss-s
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n, σ
, mea
sure
d in
uni
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)
The challenge of the LHC is to cope with proton-proton collisions at rates giving up to 1016 collision events per year, but where only a tiny fraction can be sensibly recorded Most collisions give low momentum events that do not correspond to the proton’s constituents undergoing the head-on collisions which have the energies to make new particles A multi-level “trigger” quickly identifies signatures of high-energy constituent collisions and gives ×10-5 online data reduction Even then, many tens of millions of Gigabytes per year need storing and processing:
Even at LHC energies and collision rates, new physics is hard to find
→ Worldwide LHC Computing Grid (WLCG over 150,000 processors at over 170 sites in 36 countries http://lcg.web.cern.ch/LCG/public/)
The Higgs mass is measured to be 125.36 ± 0.41 GeV, corresponding to about 130 times the mass of the proton
The Higgs: Next Steps at the LHC
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The Higgs: Next Steps at the LHC
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The CERN Council (May 2013) stated: “The discovery of the Higgs boson is the start of a major programme of work to measure this particle’s properties with the highest possible precision for testing the validity of the Standard Model and to search for further new physics at the energy frontier. The LHC is in a unique position to pursue this programme. Europe’s top priority should be the exploitation of the full potential of the LHC, including the high-luminosity upgrade of the machine and detectors with a view to collecting ten times more data than in the initial design, by around 2030”
HEPAP in the US (May 2014) decided: “The HL-LHC is strongly supported and is the first high-priority large-category project in our recommended program”
Current Shutdown Phase-0
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- New Aluminum beam pipes to prevent activation problem and reduce muon BG - New C3F8 evaporative cooling plant for Inner Detector + IBL CO2 cooling plant - Replace all calorimeter low voltage power supplies - Finish the installation of the muon chambers staged in 2003 + additional
chambers in the feet and elevators region + gas system consolidation - Upgrade the magnets cryogenics and decouple toroid and solenoid cryogenics - Add specific neutron shielding where necessary - Revisit the entire electricity supply network (UPS in particular) - Where possible prepare Phase 1 upgrade (services etc) - Re-align the barrel calorimeter and ID + consolidation of infrastructure and
services + general maintenance - Some early installation of (Phase-I) trigger upgrades which are required for
above design luminosity operation ‣ New trigger processors ‣ Improve muon trigger with current small wheel (reduce fake rate) ‣ Tile calorimeter outer layer trigger (to help muon triggering) ‣ New and replacement trigger cards ‣ Dual output boards to allow fast trigger on tracks
- New insertable pixel layer (IBL) + new pixel services + new small Be pipe
Current Shutdown Phase-0
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- New insertable pixel layer (IBL) + new pixel services + new small Be pipe
19 x 20 mm2 130 nm CMOS process, based on an array of 80 by 336 pixels
(each 50 x 250 μm2) - 3D Sensor
• Both electrode types are processed inside the detector bulk
• Max. drift and depletion distance set by electrode spacing
• Reduced collection time and depletion voltage
FE chip
sensor
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IBL Insertion into ATLAS on 7th May
Future Upgrade Planning
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Future Upgrade Planning
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Phase-I Upgrade (LS2) Starts Middle 2018
Future Upgrade Planning In 2013, 4 Technical Design Reports for Phase-I construction projects were prepared within ATLAS, approved by the CB and submitted to the LHCC As of 5th December 2013 all 4 were endorsed by CERN’s LHC Committee (LHCC) and Upgrade Cost Group Memoranda of understanding with funding agencies now mostly signed
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Future Upgrade Planning In 2013, 4 Technical Design Reports for Phase-I construction projects were prepared within ATLAS, approved by the CB and submitted to the LHCC As of 5th December 2013 all 4 were endorsed by CERN’s LHC Committee (LHCC) and Upgrade Cost Group Memoranda of understanding with funding agencies now mostly signed
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New Small Muon Wheels
The innermost station of the muon end-cap Located between end-cap calorimeter and end-cap toroid
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(CERN-LHCC-2013-006)
Mechanical Prototype
Micromegas Prototype
Trigger Chambers
sTGC Prototype
2.4m×1m Micro-Megas prototype for ATLAS New “Small” muon Wheel (1280m2)
Tracking Chambers Micro-Megas Principle
Gas (ionization) based precision chambers optimised for high rate operation at HL-LHC
Future Upgrade Planning
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Phase-II Upgrade (LS3)
Starts End 2022
Phase-II Detector Upgrades Integrated radiation levels (up to 2-3×1016neq/cm2) and plan to cope with up to 200 interactions every 25ns Implications of this include: - New Inner Detector (strips and pixels) - Trigger and data acquisition upgrades - Use tracks to improve triggering - New calorimeter front-end and back-end electronics (both LAr and tile) - Possible upgrades of very forward LAr - Muon system trigger electronics - Possible muon trigger chamber upgrades - Forward detector upgrades - Collimator and shielding upgrades - Various infrastructure upgrades - Common activities (installation, safety, …) - Software and Computing
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FCal
Cold cover
ATLAS: New All-silicon Inner Tracker Long Barrel Strips Short Barrel Strips
Forward Strips
Barrel pixel Microstrip Stave Prototype
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Baseline layout of the new ATLAS inner tracker for HL-LHC Aim to have at least 14 silicon hits everywhere (robust tracking)
Forward pixel
Quad Pixel Sensor Wafer
Signal vs dose (1 MeV n equivalent)
RD50
Quad Pixel Module
New All-silicon Inner Tracker Pixel Detector • n-implant planar, 3D and diamond sensors
proved to doses up to 2×1016neq/cm2 (~10 MGy) • Use 65nm CMOS technology for 2cm×2cm read-out chips
bump-bonded with 50µm×50µm or 25µm×100µm pixels • Test structures in 65nm produced and studied after irradiation • Larger area sensors (150µm thick) quads (4cm×4cm) produced on high
resistivity wafers with several foundries • Irradiated quad pixel modules studied in
test-beam with excellent performance • Need radiation-hard optical read-out
(~10Gb/s) and low mass micro-cables • Support designs prototyped and
service routings have been studied
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Forward Pixel Services
Possible Barrel Support Concept
Quad Sensor
RD50
16×32 pixels in 65nm CMOS
Forward Pixel Rings
New All-silicon Inner Tracker
Strip Detector • New prototype n-electrode sensors delivered with
4 rows of 2.4cm long strips at 74.5µm pitch • New (256 channel) 130nm CMOS ASIC
received and working well (97% yield) • Many strip modules (single and double sided) prototyped with 250nm ASICs • Large area stave DC-DC prototype (130cm×10cm) produced and under study
• Serial and DC-DC powering studied in detail on short versions of 250nm stave • Several other new custom chips also needed • Hybrid/module designs to use these completed • Local supports extensively prototyped
and further material reduction achieved • Progress in Petal and Stave support designs • End-of-stave card for 130nm developed
Module with on-board DC-DC converter 4 row
wire bonds
Fully functional forward module
New hybrids for 130nm ASIC
1.2m
Stave: Hybrids glued to Sensors glued to Bus Tape glued to Cooling Substrate
1.2m 1.3m
Glue
Glue Current Prototypes 250nm ASIC Designs
Carbon-fibre facing with CF honeycomb and carbon foam around titanium pipes with CO2 high pressure bi-phase cooling
HV/HR-CMOS R&D
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Potential technologies under study to bring some of the advantages of monolithic active pixel sensor (MAPS) technology to the HL-LHC
Some key fundamental issues around HV/HR-CMOS sensors are not yet fully understood, in particular the charge collection and efficiencies (especially after irradiation) but also time slewing, … which all need further R&D A reasonably sized detector still needs to be demonstrated in a beam with particles
MAPS already installed at the Relativistic Heavy Ion Collider at Brookhaven, USA
Conclusions
• The understanding of the full physics potential of the HL-LHC is advancing rapidly, with greatly increased activity on both detector and accelerator preparations following the adoption by CERN Council of the Updated European Strategy for Particle Physics, with the HL-LHC as its highest priority
• ATLAS has a coherent plan for upgrades through the coming decade to meet the challenges up to and including the HL-LHC era.
• There are designs for a replacement tracker that should withstand both the pile-up and radiation conditions at the HL-LHC with performance able to not just fully recover, but also improve on, the current vertex finding and tracking capabilities at low pile-up.
• There are many opportunities for advanced technologies in sensors, radiation-hard electronics, powering, advanced low-mass composites, optical read-out, data acquisition systems and computing.
• The UK participants in ATLAS, with the support of STFC, are playing major roles in key aspects of the LHC and HL-LHC programmes.
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Projected ATLAS Upgrade Costs
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New Inner Detector
LAr Muon Tile
TDAQ
Total
Discovery of the Higgs at the LHC The Higgs mass is measured to be 125.36 ± 0.41 GeV, corresponding to about 130 times the mass of the proton
Discovery of the Higgs at the LHC The Higgs mass is measured to be 125.36 ± 0.41 GeV, corresponding to about 130 times the mass of the proton
