1. Technological Aspects and Developments of New Detector structures
Working Group 1 Summary
Technological Aspects and Developments of New Detector structures

2. WG1: Technological Aspects and Developments of New Detector Structures
Objective: Detector design optimization, development of new multiplier geometries and techniques. Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction).
Task 2: Detector design optimization including fabrication methods and new geometries (Bulk Micromegas, Microbulk Micromegas, single-mask GEM, THGEM, RETGEM, MHSP, charge-dispersive readout, Ingrid).
Task 3: Development of radiation-hard and radio-purity detectors.
Task 4: Design of portable sealed detectors. 2

3. How will we work?
Obviously, the work has to start from the Applications.
There will be meetings on the various tasks to compare findings, exchange experience from the applications
The first step was to ask, end of May 2008:
- What is your preferred technology?(GEM, Micromegas, THGEM, RETGEM, MHSP, Cobra, PIMS, Microgroove, microwell, microdots…)
- What are your main applications? (calorimetry, TPC, photon detection, medical, imaging,…
- What is your timescale (small prototyping, scale 1 prototyping, delivery of detector, …)
38 institutes out of 54 expressed interest in tasks of Working Group 1
28 on Large Area Detectors (task 1)
9 on Design optimization (task 2, strong overlap with WG2)
20 on Radiation hard and high radiopurity (task 3)
3 on sealed detectors (task 4, recently added)

4. Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction).
Bulk Micromegas
Read-out board
Laminated Photoimageable coverlay
Stretched mesh
on frame
Laminated Photoimageable coverlay
Frame
Exposure
Development
+ cure

5. Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction).
Single mask GEM
Raw material
Single-side copper patterning
Chemical polyimide etching
Chemical copper reduction

6. Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction).
Copper Thick GEM
Raw material
CNC drilling
Small rim if needed
Electrodes etching

7. Development of large-area Micro-Pattern Gas Detectors
Bulk Micromegas
Single mask GEM
RD51 effect: progress is much faster! 7

8. 300x300mm2 THGEM!

9. Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction).
Mechanical milling 0.6 mm tool diameter
0.8mm
0.8mm
0.6mm
Mesh
Read-out board
Spacer pillar
(coverlay)
2.4mm dead region

10. Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction).
Rui de Oliveira
Practical limits (raw material roll width : 600 mm => GEM and mM need seams)
Bulk Micromegas: oven size : 1000 x Laminator: 1200 x …
GEM: 450mmx100m. No firm limitation provided seems are accepted
THGEM: Time (10-20h for 1000x600 even with 4 drills x 2 PCBs
This is the point of view of the fabrication. There are also limits from the point of view of the detector operation and robustness: capacitance
Segmentation and possibly resistive components might be necessary for large size detectors. Currently R&D for SLHC muon chambers, calorimetry, etc…

11. Large volume effect Depends on initial investments Price/area THGEM
Micromegas
GEM
Volume 11

12. Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction).
Joerg Wotschack
Very big collaboration to replace some of the ATLAS Muon chambers (230 m2)
Arizona, Athens (U, NTU, Demokritos), Brookhaven, CERN,
Harvard, Istanbul (Bogaziçi, Doğuş), Naples, Seattle, USTC
Hefei, South Carolina, St. Petersburg, Shandong, Thessaloniki,…
Needs triggering capabilities as well as 100 m position resolution and high-rate capability (5 kHz/cm2). Micromegas bulk technology considered as candidate.
Recent test beams being analysed. 55 m position resolution demonstrated with strip pitch 250 m at 90°. Cosmic test will follow, 50% prototype being built.
Need to keep resolution at angles down to 45°.

14. Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction).
Modules in 2 parts because limitation to 457 mm width from raw material.
‘Splicing’ needed
Single mask GEM used to avoid alignment difficulties between top and bottom copper foil.
Large GEMs for a forward tracker.
Serge Duarte Pinto

15. Task 1: Development of large-area Micro-Pattern Gas Detectors (large-area modules, material budget reduction).
Serge Duarte Pinto
Large GEMs for a forward tracker.
3mm seam behaves as expected

16. Task 2: Detector design optimization including fabrication methods and new geometries (Bulk Micromegas, Microbulk Micromegas, single-mask GEM, THGEM, RETGEM, MHSP, charge-dispersive readout, Ingrid).
Cylindrical and flexible GEM and Micromegas (Giani Bencivenni, Frascati and Stephan Aune, Saclay)
KLOE and CLAS12 cylindrical trackers also need large GEMs or Micromegas.
Why not cylindrical? Low material budget, challenges Silicon
Half-cylinder vs full cylinder – integrated and sealed drift cathode.
Beam tests at CERN and Brookhaven
75° Lorentz angle in 5T for CLAS12 at Edrift =1kV/cm, reduced to 14° with Edrift=10kV/cm, lower drift velocity (tan q = vB/E)

17. 4
CGEM for KLOE tracker
- CLEAN ROOM : we had too many shorts in the detector:
≥ 11 shorts (5% area) in  1.2 m2 of GEM foils (to be compared with)
0 shorts in  4.5 m2 of GEM foils for LHCb

18. Micromegas Bulk for CLAS12 vertex tracker

19. First curved bulk (09-2006) PCB: 100 µm FR4 with 5 µm thick Cu strip
100 µm amplification gap
Woven Mesh Gantois non stretched bulk with an array of 400 µm pillar every 2 mm
Dimension: 180 mm x 60 mm
Picture: bulk curved, 100 mm radius

20. SUMMARY on THGEM (Amos Breskin)
● In Ar+5%CH4 the maximum achievable gains measured with UV-light (~106)
are ~100-fold higher than with 55Fe (~104)
● Probable explanation is the Raether limit
● In Ne and Ne-CH4 (5-23%) mixtures, under gas flushing, the maximum gains
with UV and 55Fe are closer ( )
● Possible explanation: 55Fe photoelectron-tracks are longer in Ne and its
mixtures  lower density of ionization per hole  lower max. gain-difference
caused by charge-density effects.
● In pure Ne scintillation prevents high gains & “masks” p.e. extraction quencher
● For RICH: optimal would be Ne–based mixtures
● Quencher additives to be optimized – for high gain and efficient p.e. extraction.
● Preliminary results indicate upon ~70% extraction efficiency in Ne/23%CH4
similar to Ar/5%CH4.
● Charge-up: geometry (rim), gain and rate dependent.
● It seems that rimless holes are advantageous, but need to establish detectors’
parameters (eff QE, e-transfer photon detection efficiency) with the right conditions
and gas
● Need to compare stability of LARGE-AREA rim/rimless THGEMs with UV photons
● Tests in RICH mode? Who? When? – Trieste ordered 60x60 cm THGEMs.
● 30x30cm THGEM tests: tested end 2008 at WIS
● Expected results in Cryo-THGEMs Gas Photomultipliers/LXe: early 2009.

21. Task 2: Detector design optimization including fabrication methods and new geometries (Bulk Micromegas, Microbulk Micromegas, single-mask GEM, THGEM, RETGEM, MHSP, charge-dispersive readout, Ingrid).
MHSP (Micro Hole and Strip Plate) (Joao Veloso) and mPIC+Micromegas (Atsuhiko Ochi)
Drift plane
1cm
Drift/detection area
(Filled by gas)
Support wire
Cathode
Anode
400mm
Micro Mesh
165mm
230mm
100mm
70mm
Micro-mesh Micro-pixel chamber : M3PIC

22. MicroHole & Strip Plate (MHSP)
Operation Principle
Gas
JFCA Veloso et al., RSI 71(2000)2371

23. MicroHole & Strip Plate (MHSP)
Present Performance:
High gains – ~
Fast charge collection – 10 ns
Excellent energy resolution – 5.9keV x-rays - Xe
High rate capability – > 0.5 MHz/mm2
High pressure operation capability
High ion blocking capability
2-D intrinsic capability – σ~125μm (with resistive line)

24. First demonstration of a GPM operation in visible range
0.03%
No visible feedback
A. Lyashenko et al., NIMA (2008),

25. 2D-Imaging – using resistive lines
Paris, 13 – 15 of October 2008
W RD51

26. Carbon dissociated from ethane deposits on polyimide surface
5 sparks
50 sparks
150 sparks
300 sparks
200 sparks
2nd RD51 Paris
14th Octber 2008

27. Correlation between number of discharges and voltage drop after the test
2nd RD51 Paris
14th Octber 2008

28. Deposited by vaporization
MESHES
Many different technologies have been developped for making meshes (Back-buymers, CERN, 3M-Purdue, Gantois, Twente…)
Exist in many metals: nickel, copper, stainless steel, Al,… also gold, titanium, nanocristalline copper are possible.
Chemically etched
Deposited by vaporization
Electroformed
Wowen
Laser etching, Plasma etching…
PILLARS
200 mm
Can be on the mesh (chemical etching) or on the anode (PCB technique with a photoimageable coverlay). Diameter 40 to 400 microns.
Also fishing lines were used (Saclay, Lanzhou)

29. pitch = 1 mm; diameter = 0.5 mm;
Detector design optimization, fabrication methods and new geometries
THGEM Example
Mask etching + drilling; rim = 0.1mm
drilling + chemical rim etching without mask
6 keV X-ray
104
pitch = 1 mm; diameter = 0.5 mm;
rim=40; 60; 80; 100; 120 mm 29

30. Development of resistive anodes and grids
Charge dispersion readout
1 M/ plastic foil
copper oxide layer
resistive foil
glue
pads
PCB
mesh
3÷10 G/
RTGEM: resistive electrode THGEM 30

31. A few people interested, will follow up
Task 3: Development of radiation-hard and high radio-purity detectors.
A few people interested, will follow up

32. New task (discussion this morning)
Task 4: Design of portable sealed detectors
New task (discussion this morning)
Make gas-tight low-outgasing detectors with locally made high-voltage, and portable (USB?) electronics
Possible applications: radiotherapy (positioning), teaching,…
Interested people: Amos Breskin, Paul Colas, Rui de Oliveira, Per Baecklund, Fabrizzio Murtas, Joaquim Dos Santos,…
==> phone meeting early November.

33. Interactions of WG1 WG2 WG6 Production WG4 WG1 WG5 WG7 Electronics
Characterization, basic studies on performance, aging
New materials, new geometries
WG4
Simulations
WG1
Protection
WG5
Electronics
WG7
Test beams