Recent developments of Micromegas detectors for High Energy Physics

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

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


Micromegas: Micromegas: Principle of operationPrinciple of operation

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


Micromegas Micromegas further advantagesfurther advantages

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 resolution

Ion feedback suppressed by Edrift/Eamplif


COMPASSCOMPASSCOMPASSCOMPASS

• 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%


CASTCASTCASTCAST

• 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

Transv

erse m

agnetic fi

eld (B

)

X ray

X ray

detect

orL


CASTCASTCASTCAST

• Low threshold : 600 eV !

• Low background (fluorescence)

6.5 keV

X

y

Cu

Cuescape

Fe

Feescape

Ar

Low energy spectrum from Micromegas in CAST


NA48/KABESNA48/KABESNA48/KABESNA48/KABES

• CP violation

• In operation at CERN since summer 2003

• Principle : TPC + micromegas

KAon BEam Spectrometer

driftE

driftE

Tdrift2

Micromegas

Gap 50 μm

Micromegas

Gap 50 μm Tdrift1


NA48/KABESNA48/KABESNA48/KABESNA48/KABES

• Excellent time resolution

Tagged K track

Space resolution from drift time

measurement: 70 μm

Time resolution: 0.6 ns

Using TOT to correct time slewing

Tagging with reconstructed K± ± + -

(T0)KABES- (T0)DCH Spectrometer

(ns)

XStation 1 or 2 - XStation 3 (cm)


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 TPC for the Linear Collider TPC for the Linear Collider


Detector

1024 pads

Pad layout

Field cage

Readout

Berkeley-Orsay-Saclay TPC


LC-TPCLC-TPCLC-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


Spherical TPC for Spherical TPC for neutrino detectionneutrino detectionSpherical 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


Spherical TPC for Spherical TPC for neutrino detectionneutrino detectionSpherical 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



Micromegas readout by Micromegas readout by silicon pixelssilicon pixels

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


10 mm


Neutron detectionNeutron detectionNeutron detectionNeutron detection

• Use a converter to extract alphas


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


New developmentsNew developmentsNew 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


New developmentsNew developmentsNew 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


CONCLUSIONCONCLUSIONCONCLUSIONCONCLUSION

• 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

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Recent developments of Micromegas detectors for High Energy Physics