you
me
when it all started to work progress made outlook
DriftSpace
GEM foils
MediPix CMOS pixel sensorBrass spacer blockPrinted circuit boardAluminium base plate
First events, recorded on March 29, 2003.Drift space irradiated with 55Fe quantaGas: Ar/Methane 90/10
February 2004
And only 2 weeks later…
Very strong E-field above (CMOS) MediPix!
MediPix2 pixel sensorBrass spacer blockPrinted circuit boardAluminum base plate
MicroMegas
Cathode (drift) plane
55Fe
Baseplate
Drift space: 15 mm
55Fe
Nikhef/Saclay/Univ. Twente
February 2004 II
Timepix chip + Micromegas mesh:
CERN
Moiré effects
+ pillarsCharge mode
Timepix chip + SiProt + Ingrid:
“Uniform”
MESA+
IMT Neuchatel
Charge mode
• Cosmic• He iC4H10
• Fully sensitive
• Sparks observed!• He iC4H10
No B field B field of 1 T
Gas: Ar/CF4/iC4H10 : 95/3/2
And for now
Next quad: 4 chips+InGrid on a board
ReLaXd CO2 cooling
1.2 mm
Gossip: replacement of Si tracker
Essential: thin gas layer (1.2 mm)
First prototype of GOSSIP on a PSI46 working:
• 1.2 mm drift gap• Grid signal used as trigger• 30 µm layer of SiProt
End of 2007University of Nijmegen
Animated GIF of 100 hits on the PSI46 brico, 30µm SiProt.
8m
m
7.8mm
We can see tracks!University of Nijmegen
+ it is light+ primary electrons can simply be multiplied: gas amplification: low power
Tracking material, GAS vs SILICON
+ no bias current: low power+ gas can be exchanged: no radiation damage of sensor+ 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+ low sensitive for neutron and X-ray background+ δ-rays can be recognized
± high ion & electron mobility: fast signals, high count rates are possible
- discharges/sparks: readout system should be spark proof- ageing: must be solved and must be understood / under control± diffusion: limits max. drift length
ATLAS update
Pixel Vertex
Silicon strips
TRT
+ it is light
+ it is cheap
+ low power dissipation
+ high position resolution
Why not change it all?
Using GEM for calormetry is studied+ high energy resolution
digital track counting
+ excellent angular resolution± needs R&D
Questions?