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?