Electronics for large LAr TPC`s - INFN

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
Ideas and Goals (from 2006 proposal)

The basic idea:

Macroscopic version of hole Gas Electron Multipliers (GEM’s)



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


~mm hole size in standard double-face Cu-clad Printed Circuit Board (PCB)
Characteristics & performance under investigation by several collaborations
X-Y segmentation
Possible applications:

Cryogenic double phase TPC’s


High pressure TPC for medical imaging


low energy (~keV) event localization (Dark Matter, Solar Neutrinos)
R&D activity fully funded in PD by PRIN 2005
Photosensitive large area detectors, RICH

coupling with radiation conversion detectors (CsI photocathodes)
2
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




First introduced within the ICARUS
R&D group


In-house fabrication using automatic
micromachining
Self-supporting
Extremely resistant to discharges (low
capacitance)
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



Standard GEM
LEM
Coarser resolution
Low rate physics (slower signals)

A. Rubbia et al.
Photo conversion detectors

Breskin et al.

Policarpo et al.
3
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.
4
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)


Electrodes oxidation


To minimize photon feed-back and electron extraction
Resistive electrodes


To reduce diffusion effects
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
5
Resistive electrodes

Hybrid RPC concept:



Resistive layer “quenches”
the electron avalanche
Vetronite holes “limit” the
photon propagation and
after pulses
Vetronite
HV
Resistive plates
Signal pickup
Goal


Resistive
(oxided) electrode
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 Ωcm, under investigation)
Preliminary results:
Gain >> 104 easily reached
+++++++++++++++
____________
Before
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.
After
6
LEM with resistive coating
P.Fonte et al.
Large area UV photosensitive detectors
UV Window
Single LEM structure
Hybrid RPC
CsI
photocathode
G-10 with
resistive
coating
Readout plate
1,00E+06
1,00E+05
Blue: Cu coated G-10
Red: G-10 with resistive
coating.
Gas: Ar+5% isob.
10000000
100000
Preliminary
results
1,00E+04
Gain
Red: G-10 with resistive
coating.
Green: same plate
combined with CsI
photocathode.
Gas :Ar+5% isob.
1000000
1,00E+03
Gain
1,00E+07
Readout plate
10000
1000
1,00E+02
100
1,00E+01
10
1,00E+00
1,00E-01
0
1000
2000
3000
4000
5000
6000
1
0
1000
2000
Voltage (V)
higher gains are possible with resistive coating
3000
4000
5000
6000
Voltage (V)
7
Laboratory equipment
are
T
QIFF
uickT
needed
(Uim
ncom
e™
topressed)
and
seeathisdecom
picture.pressor
T
are
QIFF
uickT
needed
(Uim
ncom
e™
topressed)
and
seeathisdecom
picture.pressor
Temperature controlled
Cryogenic vessel
UHV chamber with
VUV window
8
LEM with resistive coating
are
T
QIFF
uickT
needed
(Uim
ncom
e™
topressed)
and
seeathisdecom
picture.pressor
T
are
QIFF
uickT
needed
(Uim
ncom
e™
topressed)
and
seeathisdecom
picture.pressor
Resistive GEM/ LEM coated with CsI
photocathode installed inside
the LAr test chamber
Examples CrO and
CuO resistive coatings
A full report will be presented at the IEEE-2006
9
Thick GEM-like multipliers: THGEM
L. Periale at al., NIM,A478,2002,377; J. Ostling et al.,IEEE Nicl Sci.,50,2003,809
Manufactured by standard PCB techniques of
precise drilling in G-10 (+other materials) and Cu etching.
ECONOMIC & ROBUST !
Hole diameter d= 0.3 - 1 mm
Dist. Bet. holes a= 0.7- 4 mm
Plate 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.
TGEM was further developed by Breskin group : R. Chechik et al. NIM A535, 2004, 303-30810
Thick GEM-TGEM
GEM
TGEM
2 mm thick
J. Ostling et al., IEEE Nucl. Sci., 50, 2003, 809
11
Resistive Electrode GEM-RETGEM
High resistivity layer
Holes
+V
-V
Dielectric
+
12
CNC drilling
Glue
PCB
a)
0.4-2.5 mm
Cu foil
Resistive kapton 50 μm
b)
Contact wires
Diameter of holes: 0.3-0.8 mm, pitch 0.7-1.2 mm
Active area 30x30 and 70x70 mm2
Important feature: for the first time the resistive electrodes have not any metallic substrate
Surface resistivity 200 - 800 kΩ/□ (100XC10E5)
13
Resistive Electrode GEM-RETGEM
Active area 30x30 and 70x70 mm2
Diameter of holes: 0.3-0.8 mm, pitch 0.7-1.2 mm
14
Exp. Setup
Hg lamp
Radioactive
source
PMs for monitoring
discharges
Window
A
GEMs
RETGEMs
Charge- sensitive or current amplifiers
15
RETGEM
gains
Ne, 1 atm
1.00E+05
Gain
1.00E+04
1.00E+03
GEM
1.00E+02
RETGEM,
1mm
1.00E+01
1.00E+00
1.00E-01 0
200
1.00E+05
1.00E+04
1.00E+03
1.00E+02
1.00E+01
1.00E+00
600
Voltage (V)
GEM
RETGEM,
1mm
Ar+CO 2
0
500
1000
1500
2000
2500
Voltage (V)
1,00E+06
Ga in
Gain
Ar, 1 atm
400
1,00E+04
GEM
1,00E+02
RETGEM, 1mm
1,00E+00
0
500
1000
1500
2000
2500
3000
Voltage (V)
16
Energy resolution study
Energy resolution of ~33% FWHM was achieved for uncollimated 55Fe
at gains of 103-104. At higher gains the detector may lose the proportionality and
sometimes even works in “Geiger” mode
17
Robustness against sparks
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.
Results:
Continuous discharge in RETGEM hole
• 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
18
Gains of single (solid symbols) and double (open
symbols) kapton RETGEMs
Kapton RETGEM 0. 4 mm thick
Gain
1.00E+08
1.00E+06
Ne
Holes 0.3 mm in diameter
on a 0.7 mm pitch.
Ar
1.00E+04
1.00E+02
Ar+CO2
1.00E+00
0
500
1000
1500
Voltage (V)
Kapton RETGEM 1 mm thick
Gain
1.00E+06
Ne
1.00E+04
A
Ar+CO
1.00E+02
0
1000
2000
Holes 0.8 mm in diameter
with a 1.2 mm pitch
3000
Voltage (V)
With double RETGEMs Raether limit for “macroscopic” detectors was reached : An0~108 electrons
19
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)
20
Partecipanti, tempi, richieste 2008

Partecipanti:

Padova (Tot: 1 FTE)











G. Mannocchi (20%)
P. Picchi (30%)
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 €
ottimizzazione layout LEM, LEM+needles, LEM resistive

Guadagno

Risoluzione

Stabilita temporale

Accoppiamento con fotoconvertitori per VUV
Per il 2007 stiamo seguendo il
programma previsto senza intoppi

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):


Primo anno: Prototipi piccola scala (10x10 cm2):
CERN



B. Baiboussinov (15%)
S. Centro (10%)
F.Pietropaolo (25%, Resp. Naz.)
G. Meng (25%)
Durata: 24 Mesi (2007 + 2008)
Milestones:
LNF (associati a PD)



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 €
21