MPGD’s Workshop at NIKHEF April 16th 2008

Parallel Ionization Multiplier (PIM) : a multi-stage device

using micromeshes for tracking particles

Parallel Ionization Multiplier (PIM) : a multi-stage device

using micromeshes for tracking particles

MPGD’s Workshop at NIKHEFMPGD’s Workshop at NIKHEFApril 16thApril 16th 20082008

Dominique THERS, Eric MORTEAU (SUBATECH, Nantes, France)Vincent LEPELTIER † (LAL, Orsay, France)

J. BEUCHERJ. [email protected]@cea.fr

I3HP-JRA4

2MPGD’s workshop, NIKHEF, April 16th 2008J. Beucher

OutlineOutline

• Part 1

– PIM principle

– MIP’s tracking performance

• Part 2

– Ion feedback suppression

• Conclusions


Drift electrode

Micromesh 3

Micromesh 2

Micromesh 1

PIM « PPIM « Parallelarallel I Ionizationonization M Multiplierultiplier » »

10 cm

PIM is a two amplification stages gaseous device based on micromeshes.

Kapton spacer foiletched by YAG laser

Clean room

50 µm

3 mm

Framed mesh with 10x10 cm² active area

Drift


1- Large choice of meshes: Electroformed Nickel mesh

Chemically etched Copper meshwith pillars from Rui de Oliveira’s lab (CERN)

Modular prototypeModular prototype

(e = 5µm, hpillars = 25 ou 50 µm)

1 mm-

60 µm

Øholes=30µm

2- Large choice of gap thicknesses : 25, or 50 µm pillars of CERN meshes

50, 75,125 et 220 µm Kapton foil

3- Modular mechanical structure (S. Lupone):

Holes Bar Pitch Thickness(µm)

Hold-down frameSpacer frame (PVC)Mesh frame (FR4)Kapton spacer foil (or pillars)


55Fe X @ 5,9 keV

Systematic studies


Electron transmission (1/2)Electron transmission (1/2)

Electronic transparency depends on mesh geometry. Slight dependence has been observed with different

gaseous mixture (minor effect)

But full collection efficiency could be reach easily by appropriate field ratio

ee--Amplification gap

Drift or transfer stages

Ele

ctr

on

ic t

ran

sp

are

nc

y (

%)

Ele

ctr

on

ic t

ran

sp

are

nc

y (

%)

Electronic transparency :

Standard electroformed mesh 500 LPI (125 µm)

CERN mesh (50 µm)

CERN mesh

500 LPI


200 LPI

500 LPI1000 LPI

670 LPI

ET/EA2

Ext

rac

tio

n e

ffic

ien

cy C

ex

t

(PIM 50-125 µm)

ET/EA2

50-125 µm50-200 µm50-220 µm

(670 LPI)

Ext

rac

tio

n e

ffic

ien

cy C

ex

t

Electron transmission (2/2)Electron transmission (2/2)

ee--

Transfer stage

Pre-amplification gap

A good choice of mesh geometry, gap thickness and gaseous mixture allows to

achieve high extraction efficiency

Cext~ 25 % at operating conditions with 220 µm gap thickness and 670 LPI mesh

Extraction efficiency :

ET

EA2


Total gain Total gain

PIM 50-125 µm (CERN, 670LPI, 500LPI)

)().().().().( 11221

2

2

AAEE

eEE

extAAEE

etot EGTCEGTGt

A

A

t

c

A

A1 = 50 µm

A2 = 125 µm

MM

50

µm

MM 125 µm

3 mm, ET ~1 kV/cm

3 mm, Ec =1 kV/cm

anode

Maximum gain : last point before spark induced by 5.9 keV Xrays

PIM :

Very high total gain could be achieved

(few 105 with Ne+10%CO2 )

with low electric fields

Energy resolution ~20% (FWHM)

To

tal g

ain

CERN mesh

670 LPI

500 LPI


PIM performances with hadrons


Discharge probability measurement setupDischarge probability measurement setup

Beam

Plastic scintillators +

Photomultiplier for beam profile monitoring and

alignment

Pro

toty

pes

Beam counter

@ 10 or 150 GeV/c

High hadron flux p/+ :

• 10 GeV/c, few 105/spill (T9) PS @ CERN

• 150 GeV/c, 6.107/spill (H6) SPS @ CERN

incident

esdischPdisch #

arg#


Discharge probabilityDischarge probability

Discharge probability lower than 10-9 per incident hadron at G~5000 with PIM

125 µm

50 µmA1

A2

3 mm

Dis

char

ges

pro

bab

ility

[h

adro

n-1]

Total gain

200 µm

50 µmA1

A2

3 mm

PIM « Standard »

PIM : extraction efficiency optimized


Prototypes for spatial resolution measurementPrototypes for spatial resolution measurement

• 2 prototypes back to back • Low material budget • Segmented anode : 512 strips

(width=150 µm, pitch=195 µm)• 1024 GASSIPLEX channels

PIM_01

PIM_02

Active area 10x10 cm²

Honey comb (5mm)

Front-end (GASSIPLEX +12 bits ADC)

Removable 55Fe source to simple gain monitoring


95 %

GA2 ~ 100

GA2 ~ 200

Total gain

Eff

icie

ncy

[%

]

Spatial resolution PIM 50-125Spatial resolution PIM 50-125

Spatial resolution (for one plane)

2res

x~51 µm at the beginning of

efficiency plateau (G~5000)

+,p

Beam (<104/spill)P1P2

PIM

_0P

IM_0

GA2 ~ 100

GA2 ~ 200

Sp

atia

l res

olu

tio

n

PIM

_1P

IM_1


Ion Feedback Suppression


Ion Feedback Filtering (PIM 50-125)Ion Feedback Filtering (PIM 50-125)

3 mm

3 mm

anode

anode

primarydrift

I

IIFIF

pA

500 lpi

CERN mesh

500 lpi

90Sr (~1 MeV) intense source

pAIanode

Idrift , Iprimary

No ion filtering expected because mostly field lines in transfer space

are focused inside pre-amplification gap

First intrinsic ion filtering

Second ion filtering

N.B : No mesh alignment (random arrangement)

Fractional Ion Feedback

Current measured by KEITHLEY picoammeter

125 µm

50 µm

V. Lepeltier


Fractional Ion FeedbackFractional Ion Feedback

B=0T


Modular prototype and systematic studies allowed us to optimize geometry to reduce discharge rate induced by high hadron flux

Pdisch ~ 10-10 hadron-1 (@ G~5000)

A multi-stage device using micromeshes with only two amplification stages have very promising performance for tracking

particles under high rate conditions.

ConclusionConclusion

Preliminary results with PIM show good properties to avoid ion feedback without using DC ion gate

FIF below 10-4 could be easily achieved with appropriate meshes

Complementary tests with high magnetic field are needed

Technology investigation is required to scale up towards large area


Back-up


MICROMEGAS MICROMEGAS (MICRO-MEsh GAseous Structure)(MICRO-MEsh GAseous Structure)

• Ionisation primaire

• Dérive des charges primaires

• Passage de la microgrille pour les e-

• Multiplication : avalanche électronique

• Induction du signal

Grille 500 LPI nickel (e = 3 à 6 µm)

50 µm

Ø=39µm


Charge spreadingCharge spreading

Large transfert thickness gap

could be used to spread charge cloud

CosmicsC

lust

er m

ult

iplic

ity

50 µm

X 1.5

+ 3 mm transfert stage


Back-upBack-upGain VS Et

CCext ext augmenteaugmente

TTee ~ 100 % ~ 100 %

CCext ext augmenteaugmente

TTee diminue diminue

TTee diminue plus diminue plus

vite que Cext vite que Cext n’augmenten’augmente


Back-upBack-upCext VS gaz


Caractérisation de l’électronique (1/3)Caractérisation de l’électronique (1/3)

Mesures des piédestaux et du bruit :

<Piédestaux> ~ 1170 canaux ADC <sigma> ~ 1,4 canaux ADC

Réponse homogène de l’ensemble de la chaîne électronique d’acquisition

Bruit moyen ~ 1200 e- Seuil d’acquisition @ 5 ~ 6000 e-


Back-upBack-up


Etiquetage des déchargesEtiquetage des décharges

Décharge « vue » à travers une capacité

flux

dechdech Nb

NbP

Typiquement 1V

Objectif :

Mesurer Pdech en fonction du gain

Nécessité de s’affranchir du gain variable après 1 décharge

Véto (qq secondes)


Back-upBack-upGEM + MICROMEGAS

µ-grille

GEMDrift


Back-up Back-up Influence du champ de transfert (EInfluence du champ de transfert (Ett))

Augmentation de Et = extraction plus importante

Diminution de Pdech pour un gain donné


Mesures préliminairesMesures préliminaires

Probabilités de décharge avec un détecteur MICROMEGAS :

GA1 > 1000

Pdech dépend fortement de la hauteur avec le gap

1- Reproductibilité des résultats MICROMEGAS

(125 µm) PS et SPS

GA1 < 1000

Pdech quasi-indépendante du gap

/p @ 10 GeV/c (ligne T9 PS)

2- Caractérisation de la probabilité de décharge pour

différents gaps d’amplification

Gain total


Influence de GInfluence de GA2 A2 (pré-amplification)(pré-amplification)

Probabilités de décharge avec un détecteur PIM 125-125 µm :

Minimiser le gain dans chaque étage d’amplificationcorrAAtot PPPP 21~

125 µm

125 µmA1

A2

Gain total

GA2 ~ 4000GA2 ~ 4000

MICROMEGAS 125 µm

Gain totalGain total

GA2 ~ 4000

GA2 ~ 2000

MICROMEGAS 125 µm

Pdech @ G =4000

Pdech @ G=2000

Gain total

GA2 ~ 200

MICROMEGAS 125 µm

Gain total

GA2 ~ GA1

GA2 ~ 200

MICROMEGAS 125 µm


Influence du gap de transfertInfluence du gap de transfert

Indépendant de la hauteur de l’espace de transfert

125 µm

125 µmA1

A21 et 3 mm

50 µm

50 µmA1

A23 et 6 mm


Influence du gap d’amplificationInfluence du gap d’amplification (A1)(A1)

Gap de 50 µm au contact de l’anode Collection rapide des ions Minimisation de Pcorr

125 µm

50 µmA1

A23 mm

125 µm

125 µmA1

A23 mm

GA2~200GA2~200

Documents

MPGD’s Workshop at NIKHEF April 16th 2008