bigbite / sbs front-tracker gem · 2016. 7. 22. · bigbite / sbs front-tracker gem e. cisbani infn...
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BigBite / SBS Front-Tracker GEM
E. Cisbani INFN Rome e Italian National Institute of Health
SBS Meeting 21/July/2016 - JLab
• Workforce and activity
• Assembling
• Integration @ JLab / Mechanics
• Cosmic tests in Rome / some results
• Retina tracking
• Status at the end of June/2016
GEM / Workforce and funding
• *) Scholarship
• INFN/Funding (GEM + Silicon Detector):
• Prototyping and Production (2008-2015): ~650 keuro
• Production and Installation (2016-2017): ~50 keuro/year
• Operation and Maintainance (2018-…): ~30 keuro/year
INFN Group Researcher Tech. Role
Bari R. Perrino Gas system, beam test and analysis
Catania E. Bellini C. Sutera M. Russo
L. Re* (F. Noto)
F. Librizzi D. Sciliberto A. Grimaldi
GEM module assembling, mechanics, beam test, analysis, algorithm development
Genoa P. Musico Electronics design and test
RM/Sanità E. Cisbani (A. Del Dotto
C. Fanelli)
S. Colilli F. Giuliani
M. Lucentini F. Santavenere
(M. Gricia)
Coordination, design, test, chamber integration, analysis
Total 7 / 2.5 6 / 3
Other support (collaboration): CERN / UVa / JLab
2016 / July / 21 SBS GEM Front Tracker 2
GEM Activity 2015/2016 • Production
– Stronger GEM quality check
– 14 Module assembled, 2 rejected
– Introduced aluminized mylar foil to avoid charge-up of entrance windows
– External frame design finalized
– Second GEM chamber delivered to JLab
• Test – Cosmic test HW and analysis progress
• Gas – NI Compact RIO system implemented
• Elettronica and DAQ – Paolo talk
• Algorithms – Hits detection (attempt to move in firmware)
– Track Reconstruction
2016 / July / 21 SBS GEM Front Tracker 3
1. Quick ramp up to 450 V
2. Stay at 450 V for 3 min
3. Quick ramp up to 550 V
4. Stay at 550 V for 3 min
5. Current must stabilize “well” below 10 nA
6. Switch HV to 0
7. Repeat from 1 at least twice for each sector
Controlled Humidity < 10%
(used higher humidity to clean the
foil)
2016 / July / 21 SBS GEM Front Tracker
GEM Foil Tested 50 of 74
Approved 44
Spare 2
Rejected 4
4
By end of June/2016
5
First GEM Chamber at Jlab (15/05)
SBS Front Tracker
Aluminum profiles for mechanical support (carbon fiber not ready at that time)
Cable tray vertical
Total thickness: 14 cm (not compatible with available space for Front Tracker GEM)
6
639.44 mm
From JLab/Bogdan
Tight space constraints
along particle direction!
proposed chamber orientation:
F-F-F-B-F-B
(F=forward, B=backward)
Assuming:
• 131.6 mm chambers height
• 6.6 mm between F-F
• 13.2 mm between B-F
7
From 3cm Aluminum Frame to 2cm Carbon Fiber
2016 / July / 21 SBS GEM Front Tracker 7
Flex-Bck APV
Card
HV Divider
GEM Module Carbon Fiber Frame 2 cm
12 cm
1.5 cm
2 cm
14 cm
Aluminum Profile
30x120 mm
Al
Pro
file
(3
0x
30
mm
)
PVC bar PVC support
APV Card
Old Version Final Version
8
Second GEM Chamber at JLab (15/11) Carbon Fiber mechanical frame
Large extruded PVC Cable Tray
External HDMI cables are now 20 m long, but we intend to use 15 m to reduce cable noise
• Expected green light from JLab for procurement !
9
JLab: 2nd chamber - Details
2016 / July / 21 SBS GEM Front Tracker
Distance between modules < 7 mm
24x 3 m long HDMI cables (will be replaced by 2 m long
cables)
Mechanical alignment at the level of 1 mm
10
JLab: current cosmic test stand
2016 / July / 21 SBS GEM Front Tracker
Chamber 1
Chamber 0
Gas, Electronics, Low Voltage – connected Two scintillators (from S1) in place, now running (thanks to Mark Jones)
Bottom Plastic Scint.
Top Plastic Scint.
11
JLab: cosmic test setup / details
2016 / July / 21 SBS GEM Front Tracker
• 48 x 20 m long cables
• 8 MPDs (3 of them taken apart for UVa
and HU tests)
• 2 Low Voltage lines
• Ar/CO2 gas pipe (with flow regulator)
• HV ready to be connected
12
Mechanical frame design finalized
(identical to second chamber, except longer crossbeams)
Procurement of the carbon frame components underway
Cost increaded by ~60% respect to 2014 (!)
8 weeks for production (from formal order)
13
Extruded PVC cable tray
Carbon fiber rod Front-end electronics
GEM module
Support rod for cable tray
GEM chamber – final design
1824
120
1180
SBS Front Tracker
(All mm)
Expected green light
from JLab for frame
production
14
Single Chamber Gas Piping
Parker-Legris Components
IN
OUT
Expect each chamber to have a single gas flow control
due to radiation it cannot sit close to the chamber
15
Rome: Cosmic Test Setup and trigger
2 50x25 cm2 Scintillators
2 50x25 cm2 Scintillators
10x10 cm2 Scintillator
Reference 10x10 GEM
GEMs
under test
TRIGGER
AND
OR
OR
188 mm
183 mm
385 mm
SBS Front Tracker
16
M08x
M08y
M09x
M09y
M10x
M10y
Sample 0 Sample 1 Sample 2 Sample 3 Sample 4 Sample 5
Event Display
SBS Front Tracker
6*25 ns
17
Data processing
1. Common Noise Suppression
a) Mean or Median methods
2. Pedestal Subtraction
3. Hit Identification
a) Samples analysis to get time info
b) Help from Genetic Programming
4. Hits Aggregation on cluster
5. x-y Cluster Association
a) Charge and time correlation
6. Tracking
a) Clusters association (NN, Retina ?)
b) Precise Tracking (Kalman Filter)
Steps 1 and 2 already in firmware
Work in progress to have reliable
hit ID also in firmware
Not optimized yet!
GOAL: Find a simple and robust function (to be implemented in
firmware) that can discriminate real hits from background
Try: Artificial Intelligence methods (AI)
Use Neuro-Genetic Programming (Brain Project) to determine the optimal
function that approximate the experimental data (symbolic regression)
Select (unbiased) learning subsets of the data (signals and noise)
BP criterion found: Erf (q4 * q5)>0.5
qi = ADC values/(3*RMS_ped) of sample i; (25 ns step) It uses only 2 sample (q4 and q5) !
Validate on a large set of data
2016 / July / 21 SBS GEM Front Tracker 18
M. Russo, «A distributed Neuro-Genetic
Programming Tool», Swarm and Evolutionany
Computation 27 (2015) 145-155
Use 2 “robust” hit criteria that use all 6 samples information (visually checked on
large number of events)
applied to the hits that passed the ERF method (and a simple thresholding method)
ERF method recognizes the average 96% of the “real” hits
All Modules M08 M09 M10 S2
4150 V (96) 91.4 % 93.8 % 89.9 % 90.9 % 88.5 %
4200 V (102) 97.0 % 97.4 % 96.8 % 97.0 % 96.7 %
4200 V (138) 95.5 % 97.7 % 95.5 % 93.5 % 91.2 %
4250 V (143) 99.1 % 99.2 % 99.0 % 99.1 % 99.5 %
4250 V (186) 96.5 % 96.2 % 97.2 % 96.5 % 93.3 %
All Modules M08 M09 M10 S2
4150 V (96) 6.73 2.25 2.07 2.13 0.27
4200 V (102) 6.86 2.22 2.19 2.17 0.27
4200 V (138) 7.14 2.35 2.45 2.18 0.23
4250 V (143) 7.46 2.46 2.56 2.20 0.24
4250 V (186) 7.33 2.30 2.43 2.36 0.24
“True” Hits / Erf Candidates
“True” Clusters (from Erf Candidates) / Events
Method «True»/Candidates
Erf 91.2%
«Thresholding» 3 samples
81.6%
Work is in progress
2016 / July / 21 SBS GEM Front Tracker 19
20
Module 08
x
y
Charge
Correlation
Max
Charge
Correlation
Cluster
Position
#hit in
cluster
Sample
with max
#cluster
Trigger timing not optimized (max sample =4-5)
SBS Front Tracker
21
Module 09
x
y
Charge
Correlation
Max
Charge
Correlation
Cluster
Position
#hit in
cluster
Sample
with max
#cluster
SBS Front Tracker
22
Module 10
x
y
Charge
Correlation
Max
Charge
Correlation
Cluster
Position
#hit in
cluster
Sample
with max
#cluster
SBS Front Tracker
23
All modules, «first» cluster position Mod 08 Mod 09
Mod 10
SBS Front Tracker
Few channels missing in module 10, due to cut in
kapton terminals
24
Module 8 - performance over time
High treshold cut
17/Mar/2016
19/May/2016
> month of continuos
running
Time (h)
Curr
ent
(nA
)
HV=4200
Something is going on in M8
25
GEM sector issue
xray image
Conductivity of the HV distribution
line to the GEM has been tested (by
multimeter): notingh relevant found
Resistor has been re-soldered
→ cosmic test in the coming weeks
To do: single GEM foil HV
current monitor (without HV
divider)
26
Hit Tracking
SBS Front Tracker
1. Select «true» hits on two modules
2. Compute the straight line passing for the two hits
3. Project the line on the third module
4. Compute the distance of the projected point from the measured hit
Module 8 «tested»
Module 9 «tested»
Module 10 «tested»
Residual Cosmic polar angle
Run 143
HV=4200 V
27
Estimating Tracking Efficiency Assume the module can have 3 output states: • one true hit from a cosmic with probability PD
• no hit from cosmic (unefficiency) with probability PU = 1 - PD
• noisy hit (not from cosmic) with probabilty PU*PN
Assume also: • false trigger (no track passing the GEM) have probability: (1-PT)
• if a track pass one module it pass all of them
PD, PU, PN and PT determine the probability of events: • a single module has hits (independently from the others)
• two modules have hits (independenty from the others)
• all three modules have hits
• two modules define the track, hits
of third is checked in fiducial area (s)
(A = total module area)
conservative
assumption
28
Estimating Tracking Efficiency (results)
• Preliminary Minimization (use
ROOT/Minuit2 and random brute force)
• Now looks much stable (same results
using two minimization methods)
Tracking efficiency at the level of 85%
Reasonable consistent with observed event
display
Run 102:
Module Area 200000.000000 and Fiducial Area 15.707500
Total Events : 10000.000000
Combined efficiency (0,1) (0,2) (1,2): 0.383192 0.320980 0.361130
Combined efficiency (0,1,2): 0.210755
Type 0 / idx 0 : 0.583600
Type 0 / idx 1 : 0.656600
Type 0 / idx 2 : 0.550000
Mod 0: Conditional Track Efficiency: 0.142700
Type 1 / idx 0 : 0.429700
Type 1 / idx 1 : 0.360500
Type 1 / idx 2 : 0.420300
Mod 1: Conditional Track Efficiency: 0.151100
Type 2 / idx 0 : 0.291600
Mod 2: Conditional Track Efficiency: 0.143300
FCN=0.120771 FROM MIGRAD STATUS=FAILED 293 CALLS 294 TOTAL
EDM=0.0163612 STRATEGY= 1 ERR MATRIX NOT POS-DEF
EXT PARAMETER APPROXIMATE STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 pT 9.77427e-01 5.07038e-04 0.00000e+00 -1.90898e-01
2 pD0 7.00417e-01 4.60406e-02 -0.00000e+00 3.71340e-02
3 pD1 8.87866e-01 1.92789e-03 -0.00000e+00 2.55492e-01
4 pD2 8.08472e-01 6.04075e-03 -0.00000e+00 7.57888e-02
Minuit Min: 0.977 0.700 0.888 0.808 -> 0.121
Rand Min: 0.977 0.753 0.859 0.779 -> 0.095 (max=49.49)
Run 143:
Module Area 200000.000000 and Fiducial Area 15.707500
Total Events : 10000.000000
Combined efficiency (0,1) (0,2) (1,2): 0.621229 0.578736 0.606703
Combined efficiency (0,1,2): 0.467040
Type 0 / idx 0 : 0.769800
Type 0 / idx 1 : 0.807000
Type 0 / idx 2 : 0.751800
Mod 0: Conditional Track Efficiency: 0.302000
Type 1 / idx 0 : 0.684200
Type 1 / idx 1 : 0.620900
Type 1 / idx 2 : 0.679300
Mod 1: Conditional Track Efficiency: 0.343900
Type 2 / idx 0 : 0.577400
Mod 2: Conditional Track Efficiency: 0.304500
FCN=0.0797257 FROM HESSE STATUS=OK 53 CALLS 603 TOTAL
EDM=8.87514e-05 STRATEGY= 1 ERROR MATRIX ACCURATE
EXT PARAMETER STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 pT 8.69444e-01 2.14062e-02 1.29814e-03 -7.92343e-02
2 pD0 8.02158e-01 1.97294e-02 6.93234e-04 -1.52240e-01
3 pD1 9.25127e-01 1.44478e-02 7.41597e-04 -4.85990e-02
4 pD2 8.17338e-01 1.65073e-02 6.50453e-04 -1.39510e-01
Minuit Min: 0.869 0.802 0.925 0.817 -> 0.0797
Rand Min: 0.870 0.800 0.929 0.814 -> 0.081 (max=9.39)
Track Reconstruction • Multistep approach:
– Hit association: Neural Network (need smart energy function)
– Precise tracking: Kalman filter (rather consolidated approach)
• (Slow) work in progress: – Consolidate NN
– Implementation of artificial RETINA approach (for hit association)
2016 / July / 21 SBS GEM Front Tracker
Alessio Del Dotto Cristiano Fanelli
29
30
Retina Tracking – a simple case ● The original idea is in (L. Ristori,
NIM A, 452 (2000) 425)
● Reconstruction of tracks in absence
of magnetic field using the
decoupled x-y coordinates in the
detector plane
● Considering x coordinate
● Retina is an adaptive algorithm,
and we need to fix the “receptor”
mapping the (m,q) parameters
space (each point in the plot is the
centre of a parameter space
discrete cell)
To go to a more realistic case, a smart mapping of the detector “receptor space”
is the crucial point!
2016 / July / 21 SBS GEM Front Tracker
31
Working principle Let us consider all the hits in a given detector plane k, (zn,xn)k the
response of the cellular unit (mi,qj) is
Where xrij
is an hypothetical hit in the plane r on the basis of the (mi,qj) space
segmentation.
The parameter σ in the denominator gives the size of the uncertainty on the
hits and it is strictly related to the choice of the parameter space segmentation.
(In SBS: if r!=k then sijkr>>s)
The maxima of Rij correspond to potential tracks
2016 / July / 21 SBS GEM Front Tracker
32
Receptors above threshold (i.e. >4)
are considered “on”
Full receptors responce for
the case of 3 tracks
<m> and <q> can be reconstructed from the above
threshold receptors as a weighted mean
Retina: example of results Physical space
2016 / July / 21 SBS GEM Front Tracker
33
Receptors above threshold (i.e. >4) are considered “on”
Full receptors responce for
the case of 2 tracks & ghost hits
<m> and <q> can be reconstructed from the above
threshold receptors as a weighted mean
Good tracks
Retina: example of results Physical space
2016 / July / 21 SBS GEM Front Tracker
Retina for track association
• Tracks finding → search maxima in parameter space
• Relevant aspects:
– Define the segmentation of the parameter space in a smart way
– Choose a robust maxima search algorithm
• Parallelizzation (implemented on GPU), though essentially a global method
• Can be extended to curved trajectories (e.g. magnetic field)
2016 / July / 21 SBS GEM Front Tracker 34
2016 / July / 21 SBS GEM Front Tracker
Production/Test Summary Produced or Assembled
Tested or under
test
NOT Accepted
Comment
GEM foils 74 (-6 ?) 50 2+4 2
Readout+Honeycomb 22 + 20 16 2 bad assembling, 1 probably still usable
GEM Module 14 / 18 9 2 *Open issue: 2-3 modules delivered to JLab may be damaged (by visual inspection); HV sectors in cosmic test !
External Carbon Frame
1 / 6 1 Waiting production (expecting feedback from JLab)
Front End Electronics 345 / 345 200 10 * minor bugs
VME Modules 28 / 28 16 3 minor bugs
Backplane (rigid) 80 / 80 40 6
Backplane flex-rigid 36 10 26 new just arrived
Patch Panel (adapters) 50 / 50 30 2
35
Activity 2016 2017
• Complete module production (4 for the end of 2016) + spares
(3-4 first half of 2017)
• Try to understand «HV sector issue»
• Continue test and characterization
• Integrate all chambers (2 in 2016 + 2 in 2017)
• Installation at JLab, cosmic and parassitic tests
• Hits detection (in firmware?) and track reconstruction algorithm
2016 / July / 21 SBS GEM Front Tracker 36
Module M0-M4
2016 / July / 21 SBS GEM Front Tracker 37
M0
M1
M3
M4