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Home , Compact Muon Solenoid

The Compact Solenoid Detector

Zoltán Szillási, Noémi Béni CMS collaboration CMS detector overview

2 The CMS Solenoid CMS is built around a superconducting solenoid generating a magnetic field of 4 The current necessary for this – 20 kA... Superconducting NbTi wire cooled to ~4K 13m length, 6m inner diameter – enough to fit the tracker and calorimeters inside (cost ~80 MCHF)

3 Magnets in particle detectors

ATLAS A Toroidal LHC Apparatus CMS Compact Muon Solenoid

µ

µ

4 Two ways to detect a particle (in CMS)

5 Two ways to detect a particle (in CMS) See the track

Or Catch

6 Two ways to detect a particle (in CMS) Tracking detector

Or

Calorimeter

7 Particle identification in CMS

8 The Inner Tracker

Measures the trajectories of charged particles = 1/curvature The biggest silicon detector in history, over 220m2 of silicon Inner part – 4 layers of pixel detectors, outer part 10-11 layers of silicon microstrips 141 milions of read-out channels

9 Event „pile-up”

In the LHC, several -proton collisions can occur in a single bunch crossing (The image shows an event with 29 reconstructed vertices) 10 Electromagnetic Calorimeter

Electron and measurement

~75 000 PbWO4 crystals Homogeneous detector - crystals act as both the absorber and the Very good energy resolution

11 12 Calorimeter

Jet energy measurement Brass absorber interleaved with scintillator layers (1) Steel blocks with embedded quartz fibers in the „forward” part (2)

(1)

(2)

13 CMS Muon System Return iron Yoke in red Endcap Disks: Y Cathode Strip Chambers (CSC)

X

Global System of Coordinates

Z Yoke Endcap: Muon Barrel Muon Endcap YE (MB) stations (ME) stations Yoke Barrel: YB

Barrel wheels: Resistive Plate Chambers Drift Tubes (DT) (RPC) in both barrel and endcap

Barrel: 4 DT stations in 5 iron wheels and 12 (3) or 14 (1) phi-sectors: 250 chambers

2 Endcaps: 4 CSC stations mounted on 3 iron disks 14 and 18 (3) or 36 (5) phi-sectors: 468 chambers The Muon System – Drift Tubes

Muon trajectory measurement (barrel) Measured quantity – drift time of produced by the passing muon Known drift velocity → distance measurement (~50-200mm precision) Alignment is very important

15 The Muon System – CSC

Cathode Strip Chamber (CSC) measure muon trajectories in the endcaps

The chambers contain an array of positively charged wires, strung like a harp, over strips that run perpendicular to them.

The movement of electrons to wires and induced charge on the strips give two orthogonal position co-ordinates

16 The Muon System – RPC

Resistive Plate Chambers (RPC) Present in both the barrel section and the endcaps

Two gas chambers each made of two oppositely-charged Bakelite electrodes, with a copper strip between the chambers.

Excellent time-resolution helps identify the collision that produced the observed .

17 Trigger

18 The H → gg channel

One of these plots contains the (simulated) signal.

Can you spot it?

19/25 The H → gg channel

One of these plots contains the (simulated) Higgs boson signal.

Can you spot it?

20/25 The H → gg channel

One of these plots contains the (simulated) Higgs boson signal.

Can you spot it?

21/25 The H → gg channel

One of these plots contains the (simulated) Higgs boson signal.

Can you spot it?

22/25 The H → gg channel

One of these plots contains the (simulated) Higgs boson signal.

Can you spot it?

23/25 The H → gg channel

One of these plots contains the (simulated) Higgs boson signal.

Can you spot it?

24/25 The H → gg channel

One of these plots contains the (simulated) Higgs boson signal.

Can you spot it?

25/25 Luminosity provided by HL-LHC opens new doorways to physics

HL-LHC: levelled L = 5x1034cm-2s-1 and pileup 140, with potential for 50% higher L & pileup

Physics reach will include SM & Higgs, with searches for BSM including reactions initiated by Vector Boson Fusion (VBF) and including highly-boosted objects  Narrow (t) jets or merged (hadronic decays of W, Z) jets  Ideally want to trigger on these narrow VBF & merged jets

Good jet identification and measurement: crucial for HL-LHC

26 D. Barney (CERN) Future detector upgrades 42 Tracker 1×2 and 2×2 modules PHASE-2 TCurrentRACK EtrackerR 25×100 orFuture 50×50 µ mt2racker

42

1×2 and 2×2 modules PHASE-2 TRACKER 25×100 or 50×50 µm2

Outer tracker: strip+strip (SS) and strip+macro-pixel (PS) double modules: 42M strips (192 m2) and 170M macro- pixels (25m2).

Inner tracker: 1×2 and 2×2 modules: 2M hybrid pixels a.david@(4.9cern.ch m2). for CMS KI CK-OFF MEETING -R& D ON EXPERIMENTAL TECHNOLOGIES -NOVEMBER 2017 6× smaller pixel size than Phase-1. 65 nm CMOS readout.

a.david@.ch for CMS KI CK-OFF MEETING -R& D ON EXPERIMENTAL TECHNOLOGIES -NOVEMBER 2017 38 BEYOND 2030 – MUONFuture SYSTE detectorM upgrades Gas Multiplier (GEM) in the endcap region

>20-year-old systems by 2030: ­ DT, RPC, CSC installed 2003-08.

­ CF4 (DT, CSC) and Freon (RPC).

Total surface ~10’0Installation00 m2. during LS2: Foreseen detector uGE1/1:pgra ~50des m2,: two-layer triple-GEM ­ GE1 to be installed inInstallation LS2. during between LS2 and LS3: ­ Followed by GE2 (2022) and ME0 (LS3). ­ Mature technology. GE2: ~100 m2, two-layer triple-GEM. ­ Production across centersRE3, wor lRE4:dwid e~90. m2, single-layer iRPC. ­ Improved RPC in 2022-23. ­ Improve robustness and acInstallationceptance in cr acduringks. LS3: ­ 1.4 mm thinner gap and elME0:ectrod ~60es, r- mm2,eas usixrem-layerent th rtripleough r-eaGEMdou.t at both strip-ends. GEMs could step in for LS4 replacements, if needed.

[email protected] for CMS KI CK-OFF MEETING -R& D ON EXPERIMENTAL TECHNOLOGIES -NOVEMBER 2017 Triple Gas Electron Multiplier Detectors

Gas Electron Multiplier (GEM) detectors are compact, gaseous particle detectors which were invented by Fabio Sauli at CERN in 1997, and were first introduced into CMS in early 2017.

Triple-GEMs consist of the following basic (3) layers: • A drift cathode • Three GEM foils, sealed in a gas-tight volume

• Usually 70% Ar, 30% CO2 • A printed readout circuit board (PCB) • An electronics board (if necessary) • Plus a cooling circuit, aluminum cover, etc…

A GEM foil is a 50 μm-thick sheet of polyimide, coated with 5μm of copper on each side and chemically etched with 50-70 μm-thick tapered holes at a pitch of ~140 μm (1). When put to a high voltage, the conducting copper and non-conducting polyimide of (2) the GEM foils results in electric fields through the holes (2).

When a muon enters the chamber, it ionizes the gas. (1) The ionized electrons drift towards the foils, where they encounter the electric fields. Here they multiply, drift to the next layer, multiply again, etc. until they are read out at the readout PCB as signal. This is known as an electron avalanche (3).

Elisabeth Rose Starling Triple GEMs in CMS – the GE1/1 Project

When CMS was first designed, it envisioned a system of forward resistive plate chambers (RPCs) in the muon endcaps. This was never realized due to worries about RPCs’ ability to handle background particle rates on the order of 10kHz. Instead, we are now adding 144 triple-GEM detectors (as 72 superchambers (1)) in this available space (2), called the GE1/1 system (3). (1 ) (3 The GE1/1 system has the following main goals: ) • Add redundancy in a high rate / background environment • Improve tracking • Allow for the measurement of the bending angle at trigger level • This decreases the number of mismeasured muons by lowering the trigger threshold of soft muons

In 2017-2018, 5 superchambers were installed into CMS as a demonstrator system called the (4 ) Slice Test (4). (2 ) (5 Installation of the ) full GE1/1 system (2 began in July 2019 ) (5) and will be finished by the end of Long Shutdown 2 in December 2020.

Elisabeth Rose Starling CMS High Granularity Calorimeter Future detector upgrades • CMS will be going through major upgrades! new endcap high granularity calorimeter (HGCAL) • CMS electromagnetic and hadronic endcaps need to be replaced

HGCal

Maral Alyari 3 Concept: Remove complete endcap HGCal is a 5-D imaging calorimeter system and replace with HGCAL calorimeter (energy, x, y, z, t) Overall mechanical design of HGCAL heavily constrained by present endcap calorimeters

Present CMS endcap calorimeters HGCAL design

Concept: remove complete endcap calo. system and replace with HGCAL

32 D. Barney (CERN) Future detector upgrades new endcap high granularity calorimeter (HGCAL)

Active Elements: • Hexagonal modules based on Si sensors in CE-E and high-radiation regions of CE-H • Scintillating tiles with SiPM readout in low-radiation regions of CE-H Key Parameters:

• Full system maintained at -30oC ~2.3m • ~600m2 of silicon sensors • ~500m2 of • 6M Si channels, 0.5 or 1.1 cm2 cell size • ~27000 Si modules

~2m

Electromagnetic calorimeter (CE-E): Si, Cu/CuW/Pb absorbers, 28 layers, 26 X0 & ~1.7l Hadronic calorimeter (CE-H): Si & scintillator, steel absorbers, 24 layers, ~9.0l Silicon modules

Silicon sensor glued to baseplate and PCB containing front-end electronics

PCB 7 hexagonal modules for 2017 beam test

Silicon

Kapton

Baseplate

HGCAL will include 27000 modules based on hexagonal silicon sensors with 0.5-1cm2 cells

D. Barney (CERN) 34 Once more:

35 A proton-proton collision as seen by CMS

36 The End

This talk was based on the slides made by Piotr Traczyk Check his cool video about Higgs Boson Sonification  37 Credits

Many thanks to: Piotr Traczyk Andre David Tinoco Mendes David Barney Maral Alyari Elisabeth Rose Starling …. and the full CMS collaboration for the excellent work

More information about CMS: http://cms.cern.ch