Development of “Large gas Electron Multiplier” (LEM) detectors for high gain operation in ultra-pure noble gasses

B. Baibussinov, G. Mannocchi, G. Meng, F. Pietropaolo, P. Picchi, S. Centro.

R&D Experiment - INFN PD - GR. V

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Ideas and Goals (from 2006 proposal)

The basic idea: Macroscopic version of hole Gas Electron Multipliers (GEM’s)

~mm hole size in standard double-face Cu-clad Printed Circuit Board (PCB) Characteristics & performance under investigation by several collaborations

Goals: Stable High gain (> 104 up to streamer regime) in pure noble gasses

quenching gas replaced by UV photon absorption in hole walls Good energy resolution

negligible charge loss due to electron diffusion and avalanche size (small wrt hole size)

Direct readout of LEM electrodes X-Y segmentation

Possible applications: Cryogenic double phase TPC’s

low energy (~keV) event localization (Dark Matter, Solar Neutrinos) High pressure TPC for medical imaging

R&D activity fully funded in PD by PRIN 2005 Photosensitive large area detectors, RICH

coupling with radiation conversion detectors (CsI photocathodes)

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What is a LEM

A thick GEM-like gaseous electron multipliers made of standard printed-circuit board perforated with sub-millimeter diameter holes, chemically etched at their rims

In-house fabrication using automatic micromachining

Self-supporting Extremely resistant to discharges (low

capacitance) First introduced within the ICARUS

R&D group for double phase noble gasses TPC’s in

the keV region H. Wang, PhD Thesis, UCLA, 1999 L. Periale et al, 2000.

Developed also as GEM alternative Coarser resolution Low rate physics (slower signals)

A. Rubbia et al. Photo conversion detectors

Breskin et al. Policarpo et al.

Standard GEM LEM

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LEM: principle of operation

Upon application of a voltage difference across the LEM, a strong dipole field Ehole is established within the holes.

Electrons deposited by ionizing radiation in a conversion region above the LEM, or produced on a solid radiation converter, are drifting towards the LEM under Edrift and are focused into the LEM holes by a strong electric field inside the holes.

Electrons are multiplied within the holes under the high electric field (~25-50 kV/cm)

Avalanche electrons are collected on the LEM bottom electrode (a fraction could also be further transferred to a collecting anode or to a second, possibly similar, multiplier element).

Each hole acts as an independent multiplier. A more favorable hole aspect ratio allows better avalanche

confinement, reducing photon-mediated secondary effects. This leads to higher gains in LEM wrt GEM with similar gas

mixtures and to high-gain operation in a large variety of gases, including highly scintillating ones like pure noble gasses or CF4.

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Open problems for further R&D

Residual charging-up of holes walls due ions/electrons diffusion especially at high rate and residual photon feed-back in pure noble gasses, affecting:

Maximum Gain Energy resolution Time stability

Possible fields of investigation: LEM geometry (including multi-step)

To reduce diffusion effects Electrodes oxidation

To minimize photon feed-back and electron extraction Resistive electrodes

To improve “quenching” effect (RPC-like) and reach streamer mode gain >>> In the First 6 Months of 2007 We Concentrated on This Promising Development <<<

Needle-LEM To avoid discharges and carbonization of LEM hole walls

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Resistive electrodes

Hybrid RPC concept: Resistive layer “quenches”

the electron avalanche Vetronite holes “limit” the

photon propagation and after pulses

Goal It Should allow gains up to

streamer mode (maybe limited by photon feed-back through hole input)

Disadvantages Choice of resistive material

critically depending on rate and gain (resistive materials from Quadrant Technology, ranging from 105 to 1015 Ω-cm, under investigation)

Preliminary results:Gain >> 104 easily reached

Vetronite

Resistive(oxided) electrode

Resistive platesHV

Signal pickup

A charged particle entering the hole induces an avalanche, which develops into a spark. The discharge is quenched when all of the locally (~1 hole) available charge is consumed. Photons are blocked by vetronite walls.

The discharged area recharges slowly through the high-resistivity plates.

Before

++++++ ++++++After_ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _

+++++++++++++++

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UV Window

CsI photocathode

G-10 with resistive coatingReadout plate

LEM with resistive coating

Single LEM structure Hybrid RPC

Readout plate

Large area UV photosensitive detectors

1,00E-01

1,00E+00

1,00E+01

1,00E+02

1,00E+03

1,00E+04

1,00E+05

1,00E+06

1,00E+07

0 1000 2000 3000 4000 5000 6000

Voltage (V)

Gai

n

Blue: Cu coated G-10Red: G-10 with resistive coating.Gas: Ar+5% isob.

1

10

100

1000

10000

100000

1000000

10000000

0 1000 2000 3000 4000 5000 6000

Voltage (V)

Gai

n

Red: G-10 with resistive coating.Green: same plate combined with CsI photocathode.Gas :Ar+5% isob.

higher gains are possible with resistive coating

Preliminary results

P.Fonte et al.

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Laboratory equipment

Temperature controlled Cryogenic vessel

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.UHV chamber with VUV window

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LEM with resistive coating

Resistive GEM/ LEM coated with CsI photocathode installed inside the LAr test chamber

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.Examples CrO and CuO resistive coatings

A full report will be presented at the IEEE-2006

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Thick GEM-like multipliers: THGEMThick GEM-like multipliers: THGEML. Periale at al., NIM,A478,2002,377; J. Ostling et al.,IEEE Nicl Sci.,50,2003,809

Manufactured by standard PCB techniques of preciseprecise drillingdrilling in G-10 (+other materials) and Cu etchingCu etching.

Hole diameter d= 0.3 - 1 mmDist. Bet. holes a= 0.7- 4 mmPlate thickness t= 0.4 - 3 mm

A small THGEM costs ~3$ /unit. With minimum order of 400$ ~120 THGEMs.~10 times cheaper than standard GEM.

ECONOMIC & ROBUST !ECONOMIC & ROBUST !

TGEM was further developed by Breskin group : R. Chechik et al. NIM A535, 2004, 303-308

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GEM TGEM2 mm thick

J. Ostling et al., IEEE Nucl. Sci., 50, 2003, 809

Thick GEM-TGEM

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+V

-V

High resistivity layer Holes

Dielectric-

+

Resistive Electrode GEM-RETGEM

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CNC drilling

a)

b)

Cu foil

PCB

Resistive kapton 50 μm

Contact wires

Glue

Important feature: for the first time the resistive electrodes have not any metallic substrate

Surface resistivity 200 - 800 kΩ/ (100XC10E5)

0.4-2.5 mm

Diameter of holes: 0.3-0.8 mm, pitch 0.7-1.2 mmActive area 30x30 and 70x70 mm2

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Resistive Electrode GEM-RETGEM

Diameter of holes: 0.3-0.8 mm, pitch 0.7-1.2 mm

Active area 30x30 and 70x70 mm2

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Hg lamp

RETGEMs GEMs

Window

A

Charge- sensitive or current amplifiers

Radioactive source

PMs for monitoring discharges

Exp. Setup

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Ne, 1 atm

1.00E-01

1.00E+00

1.00E+01

1.00E+02

1.00E+03

1.00E+04

1.00E+05

0 200 400 600

Voltage (V)

Gain GEM

RETGEM, 1mm

Ar, 1 atm

1.00E+001.00E+011.00E+021.00E+031.00E+041.00E+05

0 500 1000 1500 2000 2500

Voltage (V)

Gai

n

GEM

RETGEM, 1mm

Ar+CO2

1,00E+00

1,00E+02

1,00E+04

1,00E+06

0 500 1000 1500 2000 2500 3000

Voltage (V)

Gain GEM

RETGEM, 1mm

RETGEM gains

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Energy resolution of ~33% FWHM was achieved for uncollimated 55Feat gains of 103-104. At higher gains the detector may lose the proportionality and sometimes even works in “Geiger” mode

Energy resolution study

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Results:

• In Ar spark current in kapton RETGEM is almost 1000 times less that metallic Thich GEM or standard GEM

• In kapton RETGEM initial “sparks”/’streamers” with further increase of the voltage may transit to glow discharge

• Neither sparks or streamers damage the detector or electronics

In several cases, we initiated continuous glow discharges in the RETGEM for a more than 10 minutes. After the discharge was stopped (by reducing the voltage on the detector’s electrodes), the RETGEMs continued to operate without any change in their characteristics, including that of the maximum achievable gain.

Continuous discharge in RETGEM hole

Robustness against sparks

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Kapton RETGEM 0. 4 mm thick

1.00E+00

1.00E+02

1.00E+04

1.00E+06

1.00E+08

0 500 1000 1500

Voltage (V)

Ga

in

NeAr

Ar+CO2

Holes 0.3 mm in diameter on a 0.7 mm pitch.

Holes 0.8 mm in diameter with a 1.2 mm pitch

Kapton RETGEM 1 mm thick

1.00E+02

1.00E+04

1.00E+06

0 1000 2000 3000

Voltage (V)

Gai

n Ne A

Ar+CO

With double RETGEMs Raether limit for “macroscopic” detectors was reached : An0~108 electrons

Gains of single (solid symbols) and double (open symbols) kapton RETGEMs

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Recent preprints and publications

R. Oliveira, V. Peskov, F. Pietropaolo and P. Picchi, First tests of thick GEMs with electrodes made of a resistive kapton, NIM-A 576, (June 2007) Pages 362-366

L. Periale, V. Peskov, C. Iacobaeus, B. Lund-Jensen, P. Picchi, F. Pietropaolo and I. Rodionov, Photosensitive gaseous detectors for cryogenic temperature applications, NIM-A 573, (April 2007) Pages 302-305

L. Periale, V. Peskov, A. Braem, Di Mauro, P. Martinengo, P. Picchi, F. Pietropaolo and H. Sipila, Development of new sealed UV sensitive gaseous detectors and their applications, NIM-A 572, (March 2007), Pages 189-192

L. Periale, V. Peskov, C. Iacobaeus, B. Lund-Jensen, P. Pavlopoulos, P. Picchi and F. Pietropaolo , A study of the operation of especially designed photosensitive gaseous detectors at cryogenic temperatures, NIM-A 567, (November 2006) Pages 381-385

A. Di Mauro et al., Development of innovative micropattern gaseous detectors with resistive electrodes and first results of their applications, arXiv:0706.0102; 04 Jun 2007

V. Peskov, R. de Oliveira, F. Pietropaolo, P. Picchi, First Tests of Thick GEMs with Electrodes Made of a Resistive Kapton, arXiv:physics/0701154; 13 Jan 2007

Di Mauro, A, Lund-Jensen, B., Martinengo, P., Nappi, E., Peskov, V. Periale, L.,Picchi, P.; Pietropaolo, F.; Rodionov, I., A New GEM-like Imaging Detector with Electrodes Coated with Resistive Layers, arXiv:physics/0612166; 17 Dec 2006, Nuclear Science Symposium Conference record 2006, IEEE Volume 6, (Oct. 2006) Page(s):3852 - 3859

V. Peskov, B. Baibussinov, S. Centro, A. Di Mauro, B. Lund-Jensen, P. Martinengo, E. Nappi, R. de Oliveira, F. Pietropaolo, P. Picchi, L. Periale, I. Rodionov, S. Ventura, Development and first tests of GEM-like Detectors with Resistive Electrodes, Nuclear Science, IEEE Accepted for publication (July 2007)

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Partecipanti, tempi, richieste 2008

Partecipanti: Padova (Tot: 1 FTE)

B. Baiboussinov (15%) S. Centro (10%) F.Pietropaolo (25%, Resp. Naz.) G. Meng (25%)

LNF (associati a PD) G. Mannocchi (20%) P. Picchi (30%)

CERN R. De Oliveira A. Di Mauro P. Martinengo V. Peskov

Nessuna Richieste ai servizi PD per il 2008

Trasferte: Interne: 3 mesi uomo (metabolismo +

tests a LNL) : 2000 € Estere: 1 mese uomo (progettazione

PCB e deposizioni CsI): 3000 €

Durata: 24 Mesi (2007 + 2008) Milestones:

Primo anno: Prototipi piccola scala (10x10 cm2): ottimizzazione layout LEM, LEM+needles, LEM resistive

Guadagno Risoluzione Stabilita temporale Accoppiamento con fotoconvertitori per VUV

Secondo anno: LEM di medie dimesioni (30x30 cm2): Readout segmentato per:

Imaging medicale in Xenon ad alta pressione (CARDIS)

Fotorivelatori a grande area LAr-TPC doppia fase

Previsioni di spesa (2008): Consumo (totale ~19000 € su 2 anni):

Forfait workshop PCB CERN (materiale + lavorazione) ~3000 €

Fornitura Argon e Xenon gas per test ~ 3000 € Fornitura materiale resistivo ~2000 € Deposizione CsI al CERN (materiale + lavorazione)

~2000 €

Per il 2007 stiamo seguendo il programma previsto senza intoppi