SLHC tracking issues

1
SLHC tracking issues

• Regina Demina,
• University of Rochester
• International Workshop on Future Hadron
  CollidersPhysics, Detectors, Machines

2
Outline

• Accelerator upgrade stages
• Requirements on tracking
• Radiation hard RD
• Electronics issues
• System integration issues
• Summary
• AIaction item (to be addressed in future
  workshops)

3
LHC upgrade stages

• LHC performance
• 7 TeV beam
• Beam-beam tune spread 0.01
• 1.1 E11 p/bunch
• L 1E34 cm-1 s-1
• Phase 0 max performance w/o hardware changes to
  the LHC
• Increase B to 9 T ? E to 7.54 TeV
• Increase bunch intensity to 1.7E11p/bunch ?
  L2.3E34
• O. Brüning et al., LHC Luminosity and Energy
  Upgrade a Feasibility Report, LHC Project Report

4
LHC upgrade stages

• Phase 1 max performance while keeping the LHC
  arcs
• b 0.5 ?0.25 m
• Crossing angle 300 mrad?425 mrad (essential at
  decreased b to minimize long range collisions)
• Bunch intensity at 1.7 E11 ? L 3.3 E34 cm-2 s-1
• Bunch crossing interval 25 ?12.5 ns
• Increased intensity and other modifications L4.7
  E34 cm-2 s-1
• Phase 2 max performance with major hardware
  changes to LHC
• Modify injectors
• Superconduct magnets for SPS (injection E?1TeV)
• Mech and dynamic aperture changes ?x2 in L
• L 1.0 E35 cm-2 s-1 by 2015
• New superconducting dipoles E?14 TeV (a lot more
  RD is needed) not considered in this discussion

5
Tracking in SuperLHC1. Radiation damage

• Design luminosity 10xLHC
• Running time ½ LHC (5 years)
• Radiation dose 5xLHC
• Inner layers of SiTrk (r20cm) are expected to be
  operated at bias voltage 600V after 10 years of
  LHC
• SuperLHC ? 3kV (?!)
• Need replacement
• Need improved more rad hard technology
• The goal is to maintain tracking and b-tagging
  performance

6
Tracking in SuperLHC 2. Granularity
R20 cm

• With collider energy and/or luminosity increase
  the emphasis shifts towards higher energy jets.
• Energetic jets are more collimated ? need higher
  granularity
• A.I. Local occupancy is more critical. Need to
  understand for typical jet E for objects at the
  threshold of sensitivity (e.g. use 7th heavy
  quark MQ production model)

7 of tracks in 500 GeV jets have merged hits
2.5 of tracks in 100 GeV jets
7
Possible detector configuration

• What to replace?
• Most likely 100 of the tracking system
• Lifetime (no relation to radiation damage) of Si
  systems so far lt3-4 years, LHC8-10 years
• Increase granularity
• Electronics compatibility
• To fix all the problems that are not known now
• Scaling law radiation 1/r2
• Rlt20 cm new technology
• 20ltRlt60 cm pixels
• Rgt60 microstrips (with some technology pushing)

8
Directions in Tracking RD

• Use of defect engineering silicon
• E.g. DOFZ is now used for ATLAS pixels,
  possibility for CMS
• 3D and new biasing schemes
• New sensor materials
• Significant success with CVD diamonds
• Cryogenic Silicon Tracker development
• Lazarus effect x10 increase in rad hardness
• Monolithic pixel detectors
• Sensorreadout on the same silicon substrate (no
  bump bonding)

9
Why now?

• CMS SiTrk detectors design time line
• RD2 report 1994
• CMS technical proposal - 1994
• RD20 report - 1995
• RD48 report 1997
• Start construction phase 2003
• Start data taking 2007 199413years
• SuperLHC start data taking 2015
• RD?? report 2015-132001
• RD50 is formed 10/02 to address the needs of
  Super LHC

10
RD50

• Approved by CERN 06/2002
• 52 institutions, 5 from US (Fermilab, Purdue,
  Rutgers, Syracuse, BNL)
• Areas of research
• Material engineering
• Oxygenation, si carbite
• Device engineering
• Pad, 3D, thin detectors
• Rad hard technologies used for LHC are not
  completely characterized

11
RD50
12
Radiation damage microscopic defects
13
Radiation damage
Leakage current grows with rad dose P-type
impurities concentration increases, sensor goes
through n?p type inversion and then depletion
voltage grows indefinitely Annealing Reverse
annealing
14
Oxygen enriched silicon

• DOFZ (Diffusion Oxygenated Float Zone) O
  1016-1017 cm-3
• Introduced to HEP in 1999
• Slows down V depl growth after type inversion

Reverse annealing delayed and saturated at high
fluences
15
Device Engineering 3D detectors

• Electrodes
• Narrow columns along detector thickness 3D
• Diameter 10 mm, distance 50-100 mm
• Lower Vdepl
• Thicker detector possible
• Fast signal

16
CVD diamonds

• Good progress lately Main issues charge
  collection distance reached 250 um
• S/N 8/1
• Very radiation hard
• Resolution improves (!) after 2E15 p/cm-2
• Pretty

17
Electronics issues

• 0.25 um ? 0.13 um
• 0.25 um might not be available on SLHC time scale
  or even worse only few vendors will be left
• 0.13 um more rad hard
• Tracker in L1 trigger
• Binary? ATLAS experience will tell
• Power supplies (why do they always become an
  issue)

• AIs
• Cost of 0.13 um development is very high
• must managed cooperatively
• Power consumption at 80 MHz
• Signal level
• At 1V every welder in your neighborhood is your
  signal

18
System integration issues

• Large complex systems cannot be treated just as
  the sum of the parts
• Installed in experiment detector systems exhibit
  features not present in laboratory testing
• Commissioning is becoming a lengthy process 1-1.5
  years
• Why we are never able to get to b-tagging
  efficiency seen in Monte Carlo?

19
Examples of integration issues

• SuSy will jump at you after 2-3 weeks of LHC data
  taking
• Not the first two weeks

DØ
Susy? No, calorimeter noise

• Silicon tracker (WSMT) ?? calorimeter cross
  talk
• Welders

20
Examples of integration issues

• CDF L00 signal carried by analogue cables
• Readout the whole L00
• Fit pedestals with Chebyshev polynomials
• Another interesting story
• Resonance Lorentz force ? wirebond breaks

21
AI on integration

• A lot of experience gained by Tevatron
• on integration and commissioning of large
  detector systems
• Statistics of failure modes (e.g. 12 of a system
  lot due to poor cable connection)
• grounding
• Documentation
• System integration is a worthy RD project

22
Summary

• LHC upgrades will deliver x10 in L and possibly
  x2 in energy
• Most likely entire tracking systems of both high
  Pt experiments will have to be replaced
• Requirements to tracking upgrades
• Radiation hardness
• Higher granularity
• Fast response
• RD program has started
• RD50 silicon detectors
• RD42 good progress with CVD diamonds
• Electronics 0.25 ? 0.13 um transition
• System integration must be given high priority

23
Action Items

• Understand local occupancy for typical jet E for
  objects at the threshold of sensitivity (e.g. use
  7th heavy quark MQ production model)
• Electronics
• Cost of 0.13 um submissions
• Power consumption
• Signal and noise levels
• Integration
• Documentation of Tevatron experience
• RD task