Summary of Opening Session Emmanuel Tsesmelis / CERN CARE-HHH-APD Workshop Arcidosso 2 September 2005

Physics Motivation for LHC Upgrade – M. Mangano There are many good theoretical and experimental/observational arguments suggesting that the Standard Model is incomplete or that additional structures are required.

Full exploitation of the LHC is mandatory. Whatever new physics is observed at the LHC, its understanding will require higher statistics and higher energies. No other facility in the world can achieve this in the foreseeable future. The understanding of the flavour structure of the SM and of whatever BSM framework is exposed by the LHC will demand new high-statistics explorations of low-energy phenomena in the quark and lepton sectors: K/D/B decays, neutrino properties, LFV decays, EDM, etc. The upgrade path for the LHC allows options which would enable CERN to play a leading role in part of this research, with a marginal extra cost.

Machine-Experiment Interface – F. Palla Assumed integrated luminosity  LHC: 500 fb-1  SLHC 2500 fb-1 The CMS Example - Main Consequences  Tracking detectors will suffer the largest damage Need to be rebuild entirely  ECAL Endcaps need shielding  HCAL HCAL Endcaps too much radiation, need reconsider the technology  Muons YE4 better shielding ME1 needs shielding

New Tracker – First Ideas Proposed 3 Pixel Systems that are adapted to fluence/rate and cost levels Pixel #1 max. fluence system  ~400 SFr/cm 2 Pixel #2 large pixel system  ~100 SFr/cm 2 Pixel #3 large area system  Macro-pixel ~40 SFr/cm 2 8 Layer pixel system can eventually deal with 1200 tracks per unit pseudo – rapidity

CMS ECAL Endcaps Repair of Supercrystal array would require the dismounting of readout electronics on rear of backplate High activation levels, access time limited Supercrystals and their internal components are inaccessible and cannot be replaced. 5mSv/h Unshielded dose rate* 0.2mSv/h  =3  =1.48 *3300 fb -1

CMS HCAL Endcaps Scintillator under radiation form color centers that reduces the collected light yield. Current operational limit ~ 5 Mrad Should change the technology in the HCAL endcaps Dose per year at SLHC ECAL HCAL

CMS Muon Chambers Need better shielding of YE/4 (likely to be done before SLHC proper) Need better shielding for ME/1

CMS Tracker Trigger at L1 Muon L1 Trigger rate at L = cm -2 s -1 Note limited rejection power (slope) without tracker information Must develop Tracker Trigger at L1  Export some HLT algorithms to L1?  Lot of activities going on

SLHC Bunch Spacing The consequences of switching away from 12.5 ns to 10 or 15 ns could be severe for ATLAS/CMS.  If we can stay with 12.5 ns we may not have to rebuild much of the ECAL, HCAL and Muon front end electronics. If we change to 10 ns or 15 ns then we most likely have to rebuild most of this electronics.  Need a review within ATLAS/CMS to give exact statements … but guess that the cost could easily exceed 100 MCHF. Q: it will be beneficial for us if we could only have a “default” scenario and a backup one for the parameters of the SLHC  Offer solid starting point for R&D for the experiments Allow costs/benefits to be quantified

Aperture/Material of Beam Pipe Changes in beam pipe material (z = 4.5 – 16 m)  Change to Al or Be to significantly reduce dose rate from activation  Be beam pipe would also reduce the background rate into the muon system  New idea (to be studied in detail): composite (carbon) structure with inner aluminum lining Would allow integration of innermost pixel layer onto beam pipe Changes in beam pipe diameter  Increase in diameter (to 60 mm) would reduce background rate into muon system Question: any motivation from machine point-of-view to go to smaller diameter or to larger diameter?

CMS Forward Shielding Upgrade pots for 2’nd set of jacks at each end built into UXC floor. would form basis of support for a supplementary structure closing around the existing RS time needed to open and close CMS would increase significantly (~1 week per shutdown)

Shorter L*: ATLAS Layout ATLAS layout in forward region  Detectors (muon chambers) close to the cavern wall  Shielding around the beam pipe Goal: reduce accidental background rates in muon system  Crowded area Careful studies needed for additional objects Access scenario relies on space available to move detector components

Shorter L* Questions to be addressed  Impact of moving machine elements closer to the IP Backsplash of particles from absorber protecting the focusing quadrupoles and its impact on background rates in the experiment Changes in the shielding (additional cost)  Activation of machine elements and restrictions arising in access scenarios Removal of (well aligned) machine elements each time a longer access to ATLAS/CMS will be necessary and have to be possible

Maintenance The increased activation will seriously affect the maintenance of the detector  <10 hours at the CMS Tracker end-flange and 1 hour at the inner CMS ECAL Endcap to reach 5mSv = 1year allowed dose. Those detectors that will not be replaced after the LHC should be very reliable by then  Not excluded some systems will be less radiation tolerant than expected. Remote handling might become mandatory in the design of the new detectors and should probably developed for the old ones.

Installation and Commissioning Issues Not all changes can be made in a single shutdown. Installing new shielding might be in conflict with some new detectors installation  Most likely one or more extended shutdowns (  1 year) will be needed  Tracker installation will take 6 months Commissioning of the new detectors will be an additional delay  We will get more inputs from the LHC experience  Likely to take at least 6 months after the last cable is connected Q: How much time is foreseen for installation of the new machine?

LHC Beam Parameters and IR Upgrade Options – F. Ruggiero

Fast Pulsed High Energy Injectors – W. Scandale

Summary of Various Options To be Re-visited