1. Concepts and Status of the GEM trackers
SBS - Review
JLab : 22/Jan/2010
JLab 22/Jan/2010 SBS - Review
Concepts and Status of the GEM trackers
E. Cisbani / SBS Trackers
Evaristo Cisbani / INFN-Rome Sanità Group

2. E. Cisbani / SBS Trackers
Outline
Requirements for tracking
Conceptual design
GEM technology
Modular approach
GEM design details
Mechanics
Service components
Electronics
Beam tests
Very preliminary results
JLab 22/Jan/2010 SBS - Review
E. Cisbani / SBS Trackers

3. Different (e,e’h) experimental configurations
Experiments
Luminosity
(s·cm2)-1
Tracking Area
(cm2)
Resolution
Angular
(mrad)
Vertex
(mm)
Momentum
(%)
GMn - GEn
up to 7·1037
40x150
and 50x200
< 1
<2
0.5%
GEp(5)
up to 8·1038
40x120, 50x200 and
80x300
<0.7
~1.5
~ 1
SIDIS
up to 2·1037
40x120,
40x150 and 50x200
~ 0.5 ~1
<1%
JLab 22/Jan/2010 SBS - Review
E. Cisbani / SBS Trackers
Most demanding
High
Rates
Large
Area
Down to ~ 70 mm
spatial resolution
Maximum reusability: same trackers in different setups

4. Choice of the technology
System Requirements
Tracking Technology
Drift
MPGD
Silicon
High Background Rate (up to):
(low energy g and e) 1 MHz/cm2 NO
MHz/mm2
High Resolution (down to):
70 mm
Achievable
50 mm
30 mm
Large Area:
from 40×150 to 80×300 cm2
YES
Doable
Very Expensive
JLab 22/Jan/2010 SBS - Review
E. Cisbani / SBS Trackers
… and modular: reuse in different geometrical configuration
GEM
mMs
Flexibility in readout geometry and lower spark rate

5. E. Cisbani / SBS Trackers
GEM working principle
Ionization
Multiplication
Readout
GEM foil: 50 mm Kapton + few mm copper on both sides with 70 mm holes, 140 mm pitch
JLab 22/Jan/2010 SBS - Review
Strong electrostatic field in the GEM holes
E. Cisbani / SBS Trackers
Recent technology: F. Sauli, Nucl. Instrum. Methods A386(1997)531
Readout independent from ionization and multiplication stages

6. E. Cisbani / SBS Trackers
Rate capability
Hit rate not an issue
JLab 22/Jan/2010 SBS - Review
Ar/CO2/CF4 (60/20/20)
E. Cisbani / SBS Trackers
Triple GEM
Poli Lener, PhD Thesis - Rome 2005

7. Aging in COMPASS and LHCb
Altunbas et al.
NIMA 515 (2003) 249
X-ray 8.9 keV
Ar/CO2 (70/30)
JLab 22/Jan/2010 SBS - Review
Use of not-outgassing
epoxy
Change in HV
6.3 kHz/mm2
25 kHz/mm2
E. Cisbani / SBS Trackers
g-ray 1.25 MeV
Ar/CO2/CF4 (45/15/40)
Expected max. collected charge in GEp:
0.5 mC/mm2/y
No significant aging expected
Alfonsi et al.
Nucl. Phys. B 150 (2006) 159

8. Spatial Resolution in COMPASS: 70 mm
JLab 22/Jan/2010 SBS - Review
COMPASS readout plane (33x33 cm2) and results
(analog readout)
E. Cisbani / SBS Trackers
C. Altunbas et al.
NIMA 490 (2002) 177
70 mm resolution achieved by strips centroid
 Analog readout required

9. E. Cisbani / SBS Trackers
Approach: 40x50 cm2 Module
Use the same “basic” module for all trackers types
Size: 40x50 cm2 active area + 8 mm frame width
FEM study:
3 x GEM foils (double mask technology)
2D strip readout (a la COMPASS) mm pitch
x/y and u/v coordinates
JLab 22/Jan/2010 SBS - Review
E. Cisbani / SBS Trackers
Two exceptions in readout foil:
Front Tracker last 2 chambers:
Double segmented readout to reduce occupancy (Pentchev talk)
Coordinate Detector:
1D strip readout
1 mm pitch

10. E. Cisbani / SBS Trackers
Material Budget
Based on the COMPASS GEM
single honeycomb
smaller copper thickness
JLab 22/Jan/2010 SBS - Review
E. Cisbani / SBS Trackers
Minimise material to reduce background (Pentchev talk) and multiple scattering

11. Single Module Mechanical Structure
3D di Francesco
cover
drift
JLab 22/Jan/2010 SBS - Review
3 x transfer+induction
honeycomb
gas in/out-let detail
Service frame
E. Cisbani / SBS Trackers

12. Readout Plane and ZIF extension
Readout along all sides
not strictly required in x/y unless additional segmentation of the readout plane
weight balance
unavoidable in diagonal u/v
Extension feeds into ZIF connectors:
no soldering on the readout foil
permit safer bending
Small frame width (8 mm);
minimize dead area
Require precise cutting around the ZIF terminals
JLab 22/Jan/2010 SBS - Review
x/y
E. Cisbani / SBS Trackers
Rui De Oliveira design based on our preliminary drawing
In production

13. ± 45° u/v readout plane and fan-out configuration
Conceptual design
JLab 22/Jan/2010 SBS - Review u v
E. Cisbani / SBS Trackers
1.25% dead area in v plane
(in simpler configuration)
Detailed design in progress

14. Detail of the HV distribution
7 independent HV channels for each chamber (TBC)
3 HV identical doublets + 1 for drift (same on all GEM foils); each doublet serves one GEM foil, unused will be cut.
SMD protection resistors, under the thin frame
JLab 22/Jan/2010 SBS - Review
20 5×20 cm2
HV sectors
SMD resistor pads
GEM active area
E. Cisbani / SBS Trackers
Use the HV modules developed by Corradi/Murtas at LNF

15. Assembling tools: GEM foil stretcher
Load cells
Uniform and controlled stretching of the foil
(30 kg on the load cells)
JLab 22/Jan/2010 SBS - Review
Load cells
E. Cisbani / SBS Trackers
In production
Francesco Noto; inspired by al. (LNF)

16. SBS Tracker Chambers configuration
GEp(5) SBS
Front Tracker
Geometry
JLab 22/Jan/2010 SBS - Review x6
Modules are composed to form larger chambers with different sizes
Electronics along the borders and behind the frame (at 90°) – cyan and blue in drawing
Aluminum support frame around the chamber (cyan in drawing); dedicated to each chamber configuration
Back Trackers Geometry
X(4+4)
E. Cisbani / SBS Trackers

17. GEM Trackers Accounting
Area
(cm2)
Number of Chambers
Readout
Pitch
(mm)
Modules/Chamber
Total Modules
Total Readout Channels FT
40x150 6 2D
4(x/y) 2(u/v)
0.4
1×3 18
49000 +
13500 ST TT
50x200
4 + 4
2(x/y) 2(u/v)
4×0.4
1×5
20+20
13600 CD
80x300 2 1D
y+y
1.0
2×6 24
12000
JLab 22/Jan/2010 SBS - Review
E. Cisbani / SBS Trackers
Total chs
Last 2 FT modules with strips split in the middle (double segmentation on each site)
ST and TT readout groups 4 strips in GEp(5) with binary readout

18. Electronics layout and outer support
Green = FE card
JLab 22/Jan/2010 SBS - Review
Cyan = Module frames
Cards and modules are supported by an outer aluminum frame which runs all around the chamber.
Optimization is in progress.
E. Cisbani / SBS Trackers
Red= Outer Support Frame

19. Electronics Components
GEM  FEC  ADC+VME Controller  DAQ
JLab 22/Jan/2010 SBS - Review
8 mm
2D Readout
Up to 10m
49.5 mm
80 mm
Main features:
Use analog readout APV25 chips (wire-bonded on standard PCB, no ceramics): proven to work in COMPASS
ZIF connector on the GEM side (no soldering on readout foil)
Minimum electronics components (front-end + VME custom module)
Copper connection between front-end and VME
E. Cisbani / SBS Trackers
Thanks to Michael Böhmer and Igor Konorov from TUM
for very productive discussions on the design of the APV25 based FrontEnd card

20. E. Cisbani / SBS Trackers First front-end prototypes under test
Front End Card
Front End card based on COMPASS original design
The APV25 chip (originally developed for SiD in CMS)
Bus like digital lines (CLOCK, trigger and I2C) & Low Voltages
Single differential line for the ANALOG out
ZIF connectors on the GEM side (no soldering on readout foil); minimize thickness
800 front-end cards needed
Digital IN/OUT
+ LV
JLab 22/Jan/2010 SBS - Review
ANALOG
OUT
E. Cisbani / SBS Trackers
to the next card
First front-end prototypes under test

21. VME64x Custom Controller
JLab 22/Jan/2010 SBS - Review
From the VXS backplane:
Trigger L1/L2
Synch
Clock
Busy (OUT)
(duplicated on front panel)
VME controller hosts the digitization of the analog signals coming from the front-end card.
Handle all control signals required by the front end cards (trigger/clock/I2C)
Compliant to the JLab/12 VME64x VITA 41 (VXS) standard
Designed with the possibility to detach the ADC subcomponent to extend FEC-VME64x distance (expected to be ~7 m)
50 modules required
E. Cisbani / SBS Trackers
Prototype Design completed
More on DAQ  Hansen Talk

22. E. Cisbani / SBS Trackers
Beam Tests
Dec/09: preliminary beam test at DESY-II test area (low intensity electron beam from 1 to 6 GeV) of 2 10x10 cm2 2D prototypes + Gassiplex electronics
Characterize the small chamber
Prepare for the full size module test
March/10: Expected next test/data taking in high lumi at JLab/PREX experiment (with new electronics)
Late Spring/10: Planned test of 40x50 cm2 module at DESY
Demonstrate the large module works as expected
Improve design
JLab 22/Jan/2010 SBS - Review
E. Cisbani / SBS Trackers

23. DESY beam test in Dec/09: setup
JLab 22/Jan/2010 SBS - Review
2x 10x10 cm2 GEM prototypes
Silicon Tracker
+ scintillator fingers
Beam
E. Cisbani / SBS Trackers
HV Power Supply

24. DESY beam test in Dec/09 - pedestals
JLab 22/Jan/2010 SBS - Review
Baseline subtracted pedestals
Preliminary!
E. Cisbani / SBS Trackers
Gassiplex Readout (not optimized for negative charge), 700 ns shaping time

25. DESY beam test in Dec/09 - event example
Ar/CO2 70%/30%
3 GeV Electron Beam
JLab 22/Jan/2010 SBS - Review
DGEM = 410 V
Vdrift = 2.5 kV/cm
VGEM = 2.5 kV/cm
Vind = 3.5 kV/cm
Preliminary!
Single Event
E. Cisbani / SBS Trackers
Cumulated (Beam profile)

26. DESY beam test in Dec/09 – x/y correlation
DGEM = 410 V
Vdrift = 2.5 kV/cm
VGEM = 2.5 kV/cm
Vind = 3.5 kV/cm
JLab 22/Jan/2010 SBS - Review
Maximum charge in strip
E. Cisbani / SBS Trackers
Total Charge in cluster

27. SBS Front Tracker Project
JLab 22/Jan/2010 SBS - Review
E. Cisbani / SBS Trackers
INFN groups involved in the front tracker development + electronics
BA: Gas system
CA: Mechanics + Test + MC + Slow Control
GE: Electronics
ISS/RM: Prototyping, Test, Digitization + Reconstruction, SiD, Coordination
Collaboration and funding  Liyanage Talk

28. E. Cisbani / SBS Trackers
Conclusions
3 different trackers required in the SBS experiments;
support high rate,
down to ~70 mm spatial resolution
large areas
GEM technology adopted
high rate and spatial resolution proven in real experiments
Modular approach to get large area detectors, and at the same time to guarantee the already achieved performance
Detail design almost completed, first 40x50 cm2 module in production, test in late Spring/10
Electronics based on APV25; first prototypes under test
JLab 22/Jan/2010 SBS - Review
E. Cisbani / SBS Trackers

29. E. Cisbani / SBS Trackers
JLab 22/Jan/2010 SBS - Review
Backup slides
E. Cisbani / SBS Trackers

30. Choice of the frame width - FEM
Foil stretched with 30 kg weight
Electrostatic field of 10x5 kV/cm (1 Pa)
Permaglass frame
<40 mm distorsion assumed safe
JLab 22/Jan/2010 SBS - Review
E. Cisbani / SBS Trackers

31. E. Cisbani / SBS Trackers
GEM: Prototype 0 and 1
First 10x10 prototypes under cosmic test
Using 70/30 Ar/CO2 gas mixture
7 Independent HV levels up to ~ 4000 V
JLab 22/Jan/2010 SBS - Review
E. Cisbani / SBS Trackers
Assembling the GEM chambers parts require a careful quality control at several check points and specific tools for gluing, heating, testing, cleaning
Final 40x50 cm2 module finalized; GEM foils and readout ordered

32. Clean Room Tools and Facilities
JLab 22/Jan/2010 SBS - Review
Visual inspection back-light board
E. Cisbani / SBS Trackers
HV single foil testing station
Assembling the GEM chambers parts require a careful quality control at several check points and specific tools for gluing, heating, testing, cleaning

33. E. Cisbani / SBS Trackers
Slow Control
HV management is not trivial!
7 HV levels must rump up/down coherently
Low pass filters
JLab 22/Jan/2010 SBS - Review
E. Cisbani / SBS Trackers