Transcript RD51yes

The Glorious Future of Gaseous Detectors
Harry van der Graaf
RD51 Workshop
CERN, Sept 11, 2007
1968: Wire chambers
Drift chambers
1968: first Si track detector
Gaseous trackers (proportional wire chambers) are limited in
- granularity
- counting rate (ion tail)
- ageing
- robustness (broken wires, sparks)
After 1985: gaseous inner trackers replaced by Si
1995 -1996
Invention of Micromegas and GEM solving
granularity & counting rate & robustness
2003 first pixel-anode readout MPGD (Moore’s Law!):
pushing granularity.
After 2000
New Technology: Micro Engineering & Technology
Wafer Post Processing (MEMS)
Continuation of Moore’s Law
Integrated Grid
TwinGrid
Medipx-2
He/Isobutane
80/20
Modified MediPix
δ-ray!
Efficiency for
detecting single
electrons:
< 95 %
14 x 14 mm2
Integral of 15 hours operation (same image with different maximum level)
55Fe
quanta in He/Isobutane 80/20; raw data
New InGrid developments and results
Process improvement: grids much
flatter
– Extremely good energy resolution:
13.6 % FWHM with 55Fe in P10
– Removal of Kβ 6.5 keV line:
11.7 % @ 5.9 keV in P10
– With F=0.17 and Ne = 229
gain fluctuation ~ 0.5
New wafer masks:
hole pitches down to 20 μm
with various diameters and gaps
– Investigate Micromegas geometry
– Test of the ion backflow theory
feasible
Until now: 1 μm thin Al
but can now be increased to 5 μm
by electrolysis
Expect less damaged from sparks
Kα
escape
Kβ
escape
13.6 %
FWHM
Kβ-filtered spectrum with Cr foil
11.7%
FWHM
Gossip: replacement of Si tracker
New Muon Chambers for ATLAS
‘bulk Micromegas’ chambers
BulkMicromegas
FE electronics:
- pixel chips as anode
- pcb with pads, feedthroughs & FE chips
……economy…..: Si chips: Euro/cm2
General principle of new gaseous detector:
readout plane: MPGD
+
Drift space
- pixel anode chips
or
- hybrid pad pcb +
feedthrough + FE chips
With drift length of 2000 mm: TPC
200 mm: (μ)TPC
20 mm: drift chamber
2 mm: Gossip
For tracking, gas is a better detection material than Si:
- it is light
- primary electrons can simply be multiplied: gas amplification
- high electron mobility: fast signals, high count rates are possible
- gas can be exchanged: no radiation damage
- gas has a low εr: with small voxels the source capacity can be small (10 fF)
allowing fast, low-noise, and low-power preamps
- gas is usually cheap
- ageing: must be solved and must be understood / under control
- discharges/sparks: readout system should be spark proof
- diffusion: limits max. drift length
Gas On Slimmed Silicon Pixels
GOSSIP
Replacement of Si (inner, pixel vertex) trackers
- lighter
- require less power
- radiation hard
First Gossip-Demo build (Univ. of Nijmegen): 1.2 mm drift gap
with PSI-46 (CMS pixel) chip, Micromegas and SiProt
Plans for 2nd half 2007:
- beam telescope with 4 – 12 sensors
- Muon Calibrator for ATLAS
Muon Calibrator
Alu profile with Rasnik
ATLAS pixel FE chip made available…..
data lines (Cu/kapton)
ladder cross section
casted aluminium
Stainless steel tube: - string
- power
- CO2 cooling
Gossip chip + InGrid
drift gap
cathode foil
ladder side view
ladder top view
Gossip
string (4x)
cathode plane
Gossip chip + InGrid
radiator
cathode foil
Xe filled drift gap
Gossip (InGrid + pixel chip)
New: Gossip-TRT
GOSSIPO-2
test of
preamp-shaper-discriminator
and
700 MHz TDC per pixel
• 0.13 μm technology
• containing 16 x 16 pixels
• Submission Nov 29, 2006
• Can be used for GOSSIP demo!
3 x 2 mm2
Proposed FE architecture for data communication
pixel
start 700 MHz
avalanche
input pad
oscillator
AmpShaDisc
BX clock
stop
40 MHz
BXcounter
memory 1
BX-ID +Tdrift +Ttime-over-threshold
16 bits
memory 2
BX-ID +Tdrift +Ttime-over-threshold
16 bits
DAQ
bus
valid BX
pixel-ID + Tdrift + TtimeOverthreshold
An ‘almost all gas’ experiment for ILC (or CLIC)
- Inner Tracker & Vertex: gas
- TPC: gas
- Outer Tracker: gas
- Calorimeters in outer region
RD-51: a CERN based common R & D project
Technology
Electronics
Ageing
Simulations
Test Beam Facilities
Technology
- chamber materials; [radiation hardness]
- μ -technology, MEMS, etching, 3D technology
- wafer post processing
- HV stability aspects: insulators, sparks, discharges, polarisation
- Expertise: universities, institutes (IMEC, Fraunhofer, MESA+), Si-companies
Electronics
- Only FE electronics: DAQ FE is not detector-specific
- If sufficient common interest: development of general purpose
drift chamber pixel chip, and/or
- multichannel FE chip, possibly including TDC
- radiation hardness
CERN has a competent Micro-electronics group that may act
as centre-of-gravity of inter-institute chip design
Gossipo-2
Medipix-2
TimePix
1
2
5
4
55μm
6
Control logic
55μm
preamp/sha
per
High
Low
threshold
threshold
3
5
1
2
4
6
Ageing
- In 2007 we know little more than in 1907:
- there is no compound known causing ageing
- many compounds have been suspected to cause ageing
- Recent trouble with LHC experiments (LHC-B, ATLAS Muon)
demonstrate the need to clear the mystery
Proposal: operate a proportional chamber that has no ageing;
then apply (little) changes, and monitor if ageing occurs
After all, it is physics, no antroposophy or religion.
Simulations
Do we understand our detector? Is the response in agreement
with our expectations?
Required:
- positions of clusters and (single) electrons after interaction of
particle with chamber gas
- drift, diffusion and attachment of electrons and ions in gas
- 3D Electrostatic fields, taken insulators in account (imperfections,
polarisation
- Electrostatic induced charge
Much may be present, but a new level of
- parametrisation
- user friendliness
- standarisation
is required
Test beam facilities
- at present there are many testbeams available
- common use of beams at CERN would encourage communication
So: let us start with RD-51