Timepix at NIKHEF Medipix meeting, CERN – 13.09.2007 1

Some recents resultsSome recents resultsat NIKHEFat NIKHEF

M. Chefdeville, E. Bilevych, H. van de Graaf, J. Timmermans

D. Attié, P. Colas

Medipix meeting, CERN – 13 September 2007

Timepix at NIKHEF Medipix meeting, CERN – 13.09.2007 2

Overview

•Pixel readout of gaseous detectors using Micromegas-like structures

•Adding functionalities to pixel readout chips by wafer post-processing

–Gas gain grids: Ingrid–Discharge protection: Siprot

•Results with some Timepix chambers, 65k channel μTPC– 55Fe source–Cosmic rays data– 90Sr source in TOT and Time modes

Timepix at NIKHEF Medipix meeting, CERN – 13.09.2007 3

Processing Ingrids

(MESA+, Univ. Twente)

• Substrate can be:– Si wafer with a patterned anode– Pixel readout chip

• Photo-resist coating & exposure– Define the amplification gap (tens of μm)– Define the supports (pillars/walls)

• Metal film deposition & patterning– Define the grid geometry

• Dissolve the un-exposed resist– + some cleaning

substrate

photo-resist

20 μm pitch

50 μm pitch

Timepix at NIKHEF Medipix meeting, CERN – 13.09.2007 4

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 μmwith various diameters and gaps

– Investigate Micromegas geometry– Test of the ion backflow theory

feasible

• Until now: 1 μm thin Albut can now be increased to 5 μm by electrolysisExpect less damaged from sparks

Kα escapeKβ escape

13.6 % FWHM

Kβ-filtered spectrum with Cr foil

11.7% FWHM

Max Chefdeville (NIKHEF/Saclay) + Twente Univ.

Gap: 50 μm; Hole picth: 32 μm,Ø: 14 μm

Timepix at NIKHEF Medipix meeting, CERN – 13.09.2007 5

Status of Timepix usage at NIKHEF

• 1st Timepix (+ 3 μm Siprot):“under HV” Dec-Jan 2006 for 40 days He/isoButane 80/20 then died after ONE day with Ar/isoButane

• “Old” detector: (Timepix C08-W0014 + 3 μm Siprot): was “under HV” with He/isoButane 80/20 since 24 April (for 3 months!)

• Detector Next-1: (Timepix E09-W0014 + 20 μm Siprot + Ingrid): under HV for > one month with He/isoButane

• Detector Next-2: (Timepix + 20 μm Siprot + Ingrid):just started on Ar/isoButane

• Detector Next-3: (Medipix2.1 + 30 μm Siprot + Ingrid):gain 200k reached

Timepix at NIKHEF Medipix meeting, CERN – 13.09.2007 6

NIKHEF setup (on 24 Aug. 2007)

Next-3

Next-1,2 “old”

Timepix at NIKHEF Medipix meeting, CERN – 13.09.2007 7

Irradiation: 90Sr source

• Timepix chip + Micromegas mesh:

• Timepix chip + SiProt + Ingrid:

Moiré effects

“Uniform”MESA+

IMT Neuchatel

CERN

TOT mode

Timepix at NIKHEF Medipix meeting, CERN – 13.09.2007 8

Cosmic rays

A “long” cosmic track

Timepix +

20 μm thick Siprot

+

Ingrid

time

He/Iso (80:20)

Timepix at NIKHEF Medipix meeting, CERN – 13.09.2007 9

Irradiation: 90Sr source

TOT mode

Timepix+

20 μm Siprot+

Ingrid

in Next-1

5 ms/frameHe/Iso (80:20)

Timepix at NIKHEF Medipix meeting, CERN – 13.09.2007 10

Irradiation: 90Sr source

Time mode

118 μs/frame

Timepix+

20 μm Siprot+

Ingrid

in Next-1

He/Iso (80:20)

Timepix at NIKHEF Medipix meeting, CERN – 13.09.2007 11

• Chip tiling: large(r) detector surfaces (2x2, 2x4 chips)• Through Si connectivity: avoiding bonding wires• Fast readout technology: ~5 Gb/s

RELAXD project (Dutch/Belgian)NIKHEF, Panalytical, IMEC, Canberra:

Hope for “through Si vias” (with Medipix chips) later this year!

Further Developments