Vertex Detector Options for TESLA

1
Vertex Detector Options for TESLA

• Tobias Haas
• 8 November 2001

2
Overview

• Introduction
• Physics Case
• Machine/Detector Parameters
• Sensor Technologies

3
Physics Requirements

• Very high tagging efficiency for b/c/?
• High impact parameter resolution also for
  forward/backward going jets (asymmetry
  measurements)
• Short lever arm, low mass, high noise hit
  tolerance.
• High impact parameter resolution for relatively
  slow tracks (1-2 GeV/c)
• Accurate vertex mass/charge determination
  (separate b/bbar, c/cbar)
• Excellent track-track resolution in a high
  track-density environment.
• Determination of presence/absence of leptons in
  jets
• Standalone tracking in the vertex detector in
  order to identify conversions.

4
Tesla Detector Tracking

• TPC
• Large radius ? good dp/p
• Many 3D coordinates
• VTX
• Pixel detector r ? 15mm
• SIT
• Improve dp/p
• FTD, FCH
• Recover efficiency at lower polar angle

5
Machine Constraints

• Beampipe radius r14mm
• ee- bg from beam-beam
  0.03hits/mm2/BX
• 1ms bunch trains with 2820/4500 bunches
• ee- radiation is moderate (ca. 100krad in 5
  years)
• Large n bg (109 1 MeV equiv/cm2/year)

6
Vertex Detector Base Design

• 5 Layers
• 20 x 20 ?m2 pixel CCD
• Sensor thickness lt 60 ?m
• 799 Mpixels
• Readout time 50 ?s

7
SLD VXD3

• 3 Layers
• 20 x 20 ?m2 pixel CCD
• Spatial resol 3.8 ?m
• Sensor thickness 150 ?m
• 307 Mpixels
• Readout time 180 ms

8
Detector Challenges

• Extremely thin Silicone (lt 60 ?m).
• Support
• Handling
• Readout
• SLD ? TESLA 3000 times faster
• Radiation Hardness

9
Sensor Technology Choices

• CCD
• Very low power consumption
• SLOW
• MAPS (monolithic active pixel sensor)
• Alternative to CCDs
• HAPS (hybrid active pixel sensor)
• Insufficient granularity?
• High power comsumption?
• Too much material?

10
CCDs
11
CCDs

• can be fairly large (100 x 25 mm2)
• minimal amount of material per pixel
• charge transport over cm (charge loss!)

12
CCD RD

• Readout speed
• Clocking 5 MHz (SLD) ?? 50 MHz
• Column-parallel readout
• Thinning
• Mechanical
• Support-free mounting?
• Radiation Hardness

13
CCD RD Support
With Be Substrate
30 ?m Si Be 0.12 Xo (Be 0.09)
Substrate-free
0.04 Xo?
14
CCD Effort
15
MAPS
16
MAPS

• Resolution/mass very similar to CCDs
• Standard CMOS VLSI technology
• Same substrate for detector and electronics
• Radiation hardness (no bulk charge transfer)

17
MAPS RD

• Sensor Development
• Mimosa IV Chip 4 x 64x64
• Backthinning
• Mechanical Support as with
  CCDs
• Radiation Hardness

18
MAPS Effort
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What can we do ?

• EM Radiation Studies
• Recycling MVD testbeam setup
• Together with Phys. Inst.
• Mechanical Support
• Make use of our engineers/technicians.
• Common to both MAPS and CCDs

20
Which Technology?

• CCDs
• Extremely elegant and potentially highest
  performance
• Not clear whether it can be done
• MAPS
• Performance matches CCDs
• Appears more workable

21
Concrete Steps

• Make contact with the Strasbourg Group
• See where our expertise/resources fit in
• See whether we can obtain a prototype
• Set up the readout
• Set up a teststand
  for mechanical
  studies

22
Summary

• An excellent case can be made for a VXD of
  unprecedented performance for TESLA.
• This detector can be realised with MAPS and
  (maybe) CCDs.
• There is interesting detector RD to be done
  where we have resources and expertise.
• we should do it!!!