Beijing, August 18, 2004 P. Colas - Micromegas for HEP 1

Recent developments of Recent developments of Micromegas detectors for Micromegas detectors for

High Energy PhysicsHigh Energy Physics

• Principle of operationPrinciple of operation• AdvantagesAdvantages• Experiments in progressExperiments in progress

– Compass, CAST, NA48/KabesCompass, CAST, NA48/Kabes• Developments in progressDevelopments in progress

– LC-TPC, neutron detection, LC-TPC, neutron detection, NOSTOS neutrino experiment,…NOSTOS neutrino experiment,…

P. Colas, DAPNIA Saclay

ICHEP 2004, Beijing

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 2

Micromegas: Micromegas: Principle of operationPrinciple of operation

Micromegas : a micromeshsustained by 50-100 m - high insulating pillars. The multiplication takes place between the anode and the mesh

200 m

Small size ->Fast signals ->Short recovery time ->High rate capabilities

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 3

Micromegas Micromegas further advantagesfurther advantages

S1/S2 ~ Eamplif / Edrift

S1

S2

Can choose the gap/HV to have the gain maximum w.r.t. the gap and pressure -> excellent energy resolutionIon feedback suppressed by Edrift/Eamplif

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 4

COMPASSCOMPASS• MIP detection for measuring the

nucleon spin structure• High particle flow : 105 kHz/cm2

• Sparks give less than 1 per mil dead time

• Space resolution < 70 m with 350 m strips

• The largest Micromegas so far (40x40 cm2)

• In operation at CERN since 2002efficiency>97%

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 5

CASTCAST• Solar Axion detection : con-

version of solar axions in a LHC magnet -> observe low-energy X-rays

• 2D with overlayed crossed strips

• In operation at CERN since 2003

CERN Axion Solar Telescope

axions

Transverse m

agnetic field (B

)

X ray

X ray

detector

L

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 6

CASTCAST• Low threshold : 600 eV !• Low background (fluorescence)

6.5 keV

X

y

Cu

Cuescape

Fe

Feescape

Ar

Low energy spectrum from Micromegas in CAST

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 7

NA48/KABESNA48/KABES

• CP violation• In operation at CERN since

summer 2003• Principle : TPC +

micromegas

KAon BEam Spectrometer

driftE

driftE

Tdrift2

Micromegas

Gap 50 μm Micromega

s

Gap 50 μm Tdrift1

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 8

NA48/KABESNA48/KABES

• Excellent time resolution

Tagged K track

Space resolution from drift time

measurement: 70 μm

Time resolution: 0.6 nsUsing TOT to correct time

slewing

Tagging with reconstructed K± ± + -

(T0)KABES- (T0)DCH Spectrometer (ns)

XStation 1 or 2 - XStation 3 (cm)

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 9

Challenging requirements:High two-track separation in jets both in Z and in R (O(8mm))High background from photons and neutrons (600 n/BX)Excellent jet resolution (E-flow)

Particle identification

High granularityLow ion feedbackLow H-content of the gas

High granularity, small diffusion

electrons

ionsionscham

ber =>

Micropattern detectors

Low material budget of the endplate (thin frame)Good dE/dx resolution

TPC for the Linear Collider TPC for the Linear Collider

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 10

Detector

1024 pads

Pad layout

Field cage

Readout

Berkeley-Orsay-Saclay TPC

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 11

LC-TPCLC-TPCFUTURE PROJECTS, R&D

Cosmic ray data taking in May 2004. Accurate measurements of diffusion coefficients in progress.First results show that <100 m point resolution should be reached

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 12

Spherical TPC for Spherical TPC for neutrino detectionneutrino detection

• NOSTOS project : – Neutrino oscillation from Tritium– Supernova detection, burst time

structure– Coherence in -A interactions to

be tested at a reactor• Uses the longitudinal diffusion

in the gas to estimate the distance to center

FUTURE PROJECTS, R&D

Tritium source surrounded by a Micromegas

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 13

Spherical TPC for Spherical TPC for neutrino detectionneutrino detection

• Observe tritium e oscillation and measure 13

• Measure the magnetic moment of the neutrino

• Measure the weak mixing angle at low energy

• Detect supernovae explosions

FUTURE PROJECTS, R&D

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 14

Micromegas readout by Micromegas readout by silicon pixelssilicon pixels

• CERN-NIKHEF-Saclay-Twente• MIPs have been seen in a

combination micromeg.+Medipix• InGrid (integrated grid) project

pillars on silicon

FUTURE PROJECTS, R&D

10 mm

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 15

Neutron detectionNeutron detection

• Use a converter to extract alphas

FUTURE PROJECTS, R&D

• Numerous applications: neutron tomography, neutron detection in hostile environments

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 16

New developmentsNew developments

• Bulk Micromegas obtained by lamination of a woven grid on an anode with a photo-imageable film

Large area robust detectors can be made for neutrino detection or photodetection

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 17

New developmentsNew developments

• Resistive layers (Ottawa-Saclay)

Spreads the charge -> improves resolution with large pads (70 m obtained with 2mm pads with 3keV X-rays)

Might protect from discharges

• New materials for meshes• Two-stage micromegas

Beijing, August 18, 2004 P. Colas - Micromegas for HEP 18

CONCLUSIONCONCLUSION

• Existing Micromegas detectors perform well since over a year

• Micromegas offers exciting perspectives for HEparticle detection:– High granularity and suppressed ion back-flow for TPCs– Single electron detection, with a very fast electron signal– Record-breaking time resolution– Low matter budget