I 3 HPJRA 4 Parallel Ionization Multiplier PIM
- Slides: 31
I 3 HP-JRA 4 Parallel Ionization Multiplier (PIM) : a multi-stage device using micromeshes for tracking particles J. BEUCHER jerome. beucher@cea. fr Dominique THERS, Eric MORTEAU (SUBATECH, Nantes, France) Vincent LEPELTIER † (LAL, Orsay, France) MPGD’s Workshop at NIKHEF April 16 th 2008
Outline • Part 1 – PIM principle – MIP’s tracking performance • Part 2 – Ion feedback suppression • Conclusions J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 2
PIM « Parallel Ionization Multiplier » Framed mesh with 10 x 10 cm² active area Drift electrode Drift 10 cm Micromesh 3 50 µm Micromesh 2 Micromesh 1 3 mm Kapton spacer foil etched by YAG laser Clean room PIM is a two amplification stages gaseous device based on micromeshes. J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 3
Modular prototype 1 - Large choice of meshes: 3 - Modular mechanical structure (S. Lupone): Ø Electroformed Nickel mesh (µm) Holes Bar Pitch Thickness Hold-down frame Spacer frame (PVC) Mesh frame (FR 4) Kapton spacer foil (or pillars) Ø Chemically etched Copper mesh with pillars from Rui de Oliveira’s lab (CERN) 60 µm (e = 5µm, hpillars = 25 ou 50 µm) - 1 mm Øholes=30µm 2 - Large choice of gap thicknesses : 25, or 50 µm pillars of CERN meshes 50, 75, 125 et 220 µm Kapton foil J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 4
55 Fe X @ 5, 9 ke. V Systematic studies J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 5
Electronic transparency : Drift or transfer stages 500 LPI Electronic transparency (%) CERN mesh e Amplification gap Electronic transparency (%) Electron transmission (1/2) Standard electroformed mesh 500 LPI (125 µm) CERN mesh (50 µm) 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 J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 6
Electron transmission (2/2) Pre-amplification gap EA 2 e- ET Transfer stage Extraction efficiency Cext 50 -125 µm 50 -200 µm 50 -220 µm Extraction efficiency Cext Extraction efficiency : 200 LPI 670 LPI (PIM 50 -125 µm) 500 LPI 1000 LPI (670 LPI) ET/EA 2 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 ET/EA 2 J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 7
Total gain Maximum gain : last point before spark induced by 5. 9 ke. V Xrays 3 mm, Ec =1 k. V/cm 500 LPI Total gain 3 mm, ET ~1 k. V/cm A 2 = 125 µm 670 LPI CERN mesh PIM 50 -125 µm (CERN, 670 LPI, 500 LPI) anode A 1 = 50 µm PIM : µm Very high total gain could be achieved 50 (few 105 with Ne+10%CO 2 ) MM µm 5 M M J. Beucher with low electric fields 2 1 MPGD’s workshop, NIKHEF, April 16 th 2008 Energy resolution ~20% (FWHM) 8
PIM performances with hadrons J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 9
Discharge probability measurement setup High hadron flux p/p+ : 10 Ge. V/c, few 105/spill (T 9) PS @ CERN • 150 Ge. V/c, 6. 107/spill (H 6) SPS @ CERN p+ @ 10 or 150 Ge. V/c Plastic scintillators + Photomultiplier for beam profile monitoring and alignment J. Beucher Prototypes • Beam counter MPGD’s workshop, NIKHEF, April 16 th 2008 10
Discharge probability Discharges probability [hadron-1] PIM « Standard » A 2 A 1 3 mm 125 µm 50 µm PIM : extraction efficiency optimized 200 µm A 2 A 1 3 mm 50 µm Total gain Discharge probability lower than 10 -9 per incident hadron at G~5000 with PIM J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 11
Prototypes 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 10 x 10 cm² Honey comb (5 mm) Front-end (GASSIPLEX +12 bits ADC) Removable 55 Fe source to simple gain monitoring J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 12
Spatial resolution PIM 50 -125 PIM_0 95 % Beam (<104/spill) PIM_1 Efficiency [%] P 1 P 2 p+, p GA 2 ~ 100 GA 2 ~ 200 Total gain x~51 µm at the beginning Spatial resolution (for one plane) of efficiency plateau (G~5000) J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 GA 2 ~ 100 GA 2 ~ 200 13
Ion Feedback Suppression J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 14
Ion Feedback Filtering (PIM 50 -125) V. Lepeltier 90 Sr ( ~1 Me. V) Second ion filtering intense source p. A Idrift , Iprimary 125 µm 50 µm 3 mm 500 lpi 3 mm CERN mesh p. A No ion filtering expected because mostly field lines in transfer space are focused inside pre-amplification gap anode Ianode First intrinsic ion filtering Current measured by KEITHLEY picoammeter Fractional Ion Feedback J. Beucher N. B : No mesh alignment (random arrangement) MPGD’s workshop, NIKHEF, April 16 th 2008 15
Fractional Ion Feedback B=0 T J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 16
Conclusion ØModular 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) ØA multi-stage device using micromeshes with only two amplification stages have very promising performance for tracking particles under high rate conditions. Ø 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 ØComplementary tests with high magnetic field are needed ØTechnology investigation is required to scale up towards large area J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 17
Back-up J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 18
MICROMEGAS (MICRO-MEsh GAseous Structure) 50 µm Ø=39µm Grille 500 LPI nickel (e = 3 à 6 µm) • Ionisation primaire • Dérive des charges primaires • Passage de la microgrille pour les e • Multiplication : avalanche électronique • Induction du signal J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 19
Cluster multiplicity Charge spreading 50 µm Cosmics + 3 mm transfert stage X 1. 5 Large transfert thickness gap could be used to spread charge cloud J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 20
Back-up Gain VS Et Cext augmente Te diminue plus Cext Te diminue vite que Cext augmente n’augmente Te ~ 100 % J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 21
Back-up Cext VS gaz J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 22
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- J. Beucher Seuil d’acquisition @ 5 ~ 6000 e- MPGD’s workshop, NIKHEF, April 16 th 2008 23
Back-up J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 24
Etiquetage des décharges Typiquement 1 V Décharge « vue » à travers une capacité Objectif : Mesurer Pdech en fonction du gain Nécessité de s’affranchir du gain Véto (qq secondes) variable après 1 décharge J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 25
Back-up GEM + MICROMEGAS Drift GEM µ-grille J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 26
Back-up Influence du champ de transfert (Et) Augmentation de Et = extraction plus importante Diminution de Pdech pour un gain donné J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 27
Mesures préliminaires Probabilités de décharge avec un détecteur MICROMEGAS : p+/p @ 10 Ge. V/c (ligne T 9 PS) 1 - Reproductibilité des résultats MICROMEGAS (125 µm) PS et SPS 2 - Caractérisation de la probabilité de décharge pour différents gaps d’amplification Ø GA 1 > 1000 Pdech dépend fortement de la hauteur avec le gap Ø GA 1 < 1000 Gain total J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 Pdech quasi-indépendante du gap 28
Influence de GA 2 (pré-amplification) Probabilités de décharge avec un détecteur PIM 125 -125 µm : Pdech @ G =4000 A 2 125 µm A 1 125 µm Pdech @ G=2000 GA 2 ~ 4000 ~ 200 A 2 GG ~ 200 A 2 ~ 4000 MICROMEGAS 125 µm ~ GA 1 G MICROMEGAS 125 µm A 2 ~ 2000 MICROMEGAS 125 µm Gain total Minimiser le gain dans chaque étage d’amplification J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 29
Influence du gap de transfert A 2 1 et 3 mm 3 et 6 mm A 1 125 µm 50 µm Indépendant de la hauteur de l’espace de transfert J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 30
Influence du gap d’amplification (A 1) A 2 3 mm 125 µm A 1 125 µm A 2 125 µm 3 mm A 1 GA 2~200 50 µm Gap de 50 µm au contact de l’anode Collection rapide des ions Minimisation de Pcorr J. Beucher MPGD’s workshop, NIKHEF, April 16 th 2008 31
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