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

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.
The upgrade path for the LHC allow
options which would enable CERN
to play a leading role in part of this
research, with a marginal extra cos
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.
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


Pixel #2 large pixel system


~100 SFr/cm2
Pixel #3 large area system


~400 SFr/cm2
Macro-pixel ~40 SFr/cm2
8 Layer pixel system can eventually deal
with 1200 tracks per unit pseudo –
rapidity
CMS ECAL Endcaps
Unshielded dose rate*
0.2mSv/h
=1.48
Supercrystals and their internal components
are inaccessible and cannot be replaced.
Repair of Supercrystal array would require the
dismounting of readout electronics on rear of
backplate
High activation levels, access time limited
*3300 fb-1
=3
5mSv/h
CMS HCAL Endcaps
35
10
Dose(Mrad)
10
10
10
10
10
Dose in ECAL and HCAL for L = 10
3
and One Year
2
1
ECAL
0
HCAL
-1
-2
0
1
2
3
4
5

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
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 = 1034 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 change to 10 ns or 15 ns then we most likely have to
rebuild most of this electronics.


If we can stay with 12.5 ns we may not have to rebuild much of
the ECAL, HCAL and Muon front end 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


Crowded area


Goal: reduce accidental background rates in muon system
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


Those detectors that will not be replaced after the
LHC should be very reliable by then


<10 hours at the CMS Tracker end-flange and 1 hour at
the inner CMS ECAL Endcap to reach 5mSv = 1year
allowed dose.
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



Commissioning of the new detectors will be an
additional delay



Most likely one or more extended shutdowns ( 1 year) will
be needed
Tracker installation will take 6 months
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