An Idiot’s Guide to LHC Upgrades Bohr Lunch Seminar. 16/5/08 Terry Wyatt. University of Manchester.

LHC Current Status Entire machine cool down by end June In parallel, check out already cold sectors and commission to >5.5 TeV Machine and experimental areas closed by mid- July First circulating beam end July? In 2008 beams will be limited in energy to 5 TeV and low intensity First collisions at 10 TeV sometime September/October? Expect maybe 20 pb -1 int. luminosity in 2008 for ATLAS and CMS? 2

Experiment Current Status CMS – currently completing beam pipe – bake out beam pipe (until 7th June) – then installation and commissioning of pixel detector – 1st endcap EM calorimeter eady for installation early June – Neither 2nd endcap EM calorimeter nor endcap preshower detectors will be installed unless there is significant slippage in the machine schedule – CMS starts final closing of detector at beginning of July – Magnet test at 3.8 T and cosmic data taking until beam ATLAS – currently - recovering from serious failure of cooling system for inner detector - preparing to close endcap calorimeters and toroids – after these are completed (~2 weeks time?) beam pipe bake out 60 days of magnet tests complete commissioning of pixel detector (but no access to fix anything) LHCb – largely complete ALICE – central detector largely complete – small parts of most outer detector systems 3

LHC Machine Upgrades Phase I (~2013) – Replace mini-β insertions – Replace proton linac (Linac 2) with H - linac (Linac 4) – Designed, approved and funded (sort of) Phase II (~2018) – Replace Booster and PS with SPL and PS2 – Replace mini-β insertions – Still at the design stage N.B. Of course nobody knows what the plateau LHC lumi will be before upgrades 4

LHC Experiment Upgrades Phase I (~2013) – CMS/ATLAS: Pixel detectors need some upgrade/replacement Ability of CMS/ATLAS to deal with 2-4 x cm -2 s -1 needs further study! – LHCb: planning for straight replacement current inner tracker (VELO) Phase II (2018) – Complete replacement of tracker systems required – Requires ~18 month shutdown? – Timescales for each stage still under discussion 5

Substantal funding and effort already being devoted to this – Temporary boost to CERN budget "White Paper" (€240M over 4 years ) Which funds: – phase I accelerator upgrades – accelerator, detector and electronics R&D – EU funding for R&D infrastructure and planning of upgrades – Further EU FP7 funding applications pending – ATLAS and CMS have substantial upgrade organizations – RD39 (diamond) RD42 (low-temp silicon), RD50 (silicon), RD51? (gas detectors) 6

Peak Luminosity N b number of particles per bunch (1.15 x ) n b number of bunches (2808) f r revolution frequency  n normalised emittance  * beta value at IP (0.5 cm for ATLAS/CMS) F reduction factor due to crossing angle N b,  n injector chain  * LHC insertion F beam separation schemes n b electron cloud effect

Inner Triplets (Mini-β insertions) By ~2013: Entirely replace current inner triplets – Reduce β* from 0.55 cm to 0.25 cm – Factor of two in instantaneous lumi 8

CERN accelerator complex

Main Motivation for Injector Upgrades Aging infrastructure – Integrated luminosity is what really counts! depends as much on reliability as on peak luminosity – Spares are expensive and hard to obtain Space charge currently the factor limiting intensities – Increase injection energy in the synchrotrons  need for new accelerators designed for the needs of SLHC 10

PSB SPS SPS+ Linac4 LPSPL PS LHC / SLHC DLHC Output energy 160 MeV 1.4 GeV 4 GeV 26 GeV 50 GeV 450 GeV 1 TeV 7 TeV ~ 14 TeV Linac2 50 MeV LPSPL: Low Power Superconducting Proton Linac (4 GeV) PS2: High Energy PS (~ 5 to 50 GeV – 0.3 Hz) SPS+: Superconducting SPS (50 to1000 GeV) SLHC: “Superluminosity” LHC (up to cm -2 s -1 ) DLHC: “Double energy” LHC (1 to ~14 TeV) Proton flux / Beam power Upgrade components PS2

Layout of the new injectors SPS PS2 SPL Linac4 PS

Planning for Injector Upgrades Linac4 approval SPL & PS2 approval Start for Physics

Expected Luminosities? 14

A More Realistic (Atractive?!) Scenario? 15

SLHC Challenges for the Experiments Bunch crossing period 25 ns (or even 50 ns) – 12.5 ns is dead (killed by electron cloud issues) – 200 pp collisions per crossing (or even 400) – Very high detector occupancies – Very high radiation doses Mini-β insertions no firm plans yet most schemes involve placing machine elements inside detectors! 16

Tracking at High Luminosity! 17

Not just a problem of developing rad.hard sensors! Also: read-out electronics, cooling, power And really need to be able to do some tracking at Level-1 trigger! Plus: beam pipe (Be), shielding, etc. Will be peer-reviewed by LHCC 18

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ATLAS Pixel Detector R&D 20

Motivation? Not much new in terms of physics studies in recent times – Everyone is waiting to see what the first few years of LHC delivers! Very general arguments: – Highly unlikely to have any other energy frontier accelerator before 2025! – History: Most accelerators have a much longer shelf life than originally planned for – Cornell/CESR still running after >30 years – Tevatron originally planned for 100 pb -1 until » Still running 4 fb -1 delivered with another ~doubling by end 2010? – Very unlikely to want to switch off LHC around 2015! By then central detectors will anyway need replacement In order to maintain interest need steady increase in integrated lumi per year – Once doubling time for integrated lumi is > few years it gets boring 21

Gauge Boson Self-Couplings In many cases SLHC competitive with 500 GeV e+e- collider 22

Rare Higgs Decays Also interesting: Higgs self-coupling, rare top decays, etc. 23

Very Heavy Higgs 24

Suggestion for Further Reading =standard&confId=

Summary LHC is likely to be around for a long time to come First stage upgrades to accelerator are in the pipeline Preparing for longer term upgrades to accelerator and experiments is urgent, given the long lead times involved Lots of opportunities to get involved! But of course we are all waiting to see what new physics shows up in the first couple of years! 26