test of the gem front tracker for the sbs spectrometer at jefferson lab
DESCRIPTION
Test of the GEM Front Tracker for the SBS Spectrometer at Jefferson Lab. F. Mammoliti, V. Bellini, M. Capogni, E. Cisbani, E. Jensen, P. Musico, F. Noto, G. Ruscica, M.C. Sutera, B. Wojtsekhowski. OUTLINE -JLab facility -Super BigBite Spectrometer -GEM Tracker -Mainz Test Beam Facility - PowerPoint PPT PresentationTRANSCRIPT
Test of the GEM Front Tracker for the SBS Spectrometer at Jefferson Lab
F. Mammoliti, V. Bellini, M. Capogni, E. Cisbani, E. Jensen, P. Musico, F. Noto, G. Ruscica, M.C. Sutera, B.
Wojtsekhowski
OUTLINE-JLab facility-Super BigBite Spectrometer-GEM Tracker-Mainz Test Beam Facility-Experimental Data
The Continuous Electron Beam Accelerator Facility
The high resolution and high luminosity(polarized) CEBAF electron beam:-Current: up to 200 µA-Energy: up to 6 GeV -Energy resolution : 2.5*10-5
-Duty factor: 100% (continuous beam)-3 Experimental halls: A, B and C
JLab, Newport News (VA)
CEBAF UPGRADE
Two superconducting linear accelerators (LINACs)
Arches with Magnets that form a
circuit of 1.4 Km
Electrons Energy of 10.9 GeV for
Hall A, B, C and 12 GeV for new Hall D
Currents Sum: 5 μA for Hall D and
85 μA for the others
Searching for exotic Mesons
Proton and Neutron structure
Nucleus Structure
Parity Violation
Research fields
SUPER BIGBITE SPECTROMETER 1/3
-High Luminosity: 8 x 1038 cm-2s-1
-Forward angle (down to 6°)-Large Momentum Range (2-10 GeV/c)-Moderate angular acceptance (64 mrad) -High rate capability (1 MHz/cm2)
Flexibility:use the same detectors indifferent experimental setup
SUPER BIGBITE SPECTROMETER 2/3
1st tracker 2nd tracker 3rd tracker
Tracking Detector Configuration
HCAL
(X,Y) x2 (X,Y) x2
(X,Y) x2 (X,Y) x2
(U,V) x2
(U,V) x2(U,V) x2
Number of Layers
Area (cm2)
First Tracker 6 40*150
Second Tracker 4 50*200
Third Tracker 4 50*200
HCAL 2 80*300
Silicon tracker 10 x 20 cm2
Dipole
Two GEM planes 40 x 150
cm2
CH4 polarimeter
Second GEM tracker
Second CH4 polarimeter
Third GEM tracker
Calorimeter
Resistant to shock
Rate > 5 ∙105 Hz/mm2
Nominal spatial resolution of 60 μm
Readout flexibility
Low Cost
Why GEM detector?
SUPER BIGBITE SPECTROMETER 3/3
GEM FOILGas Electron Multiplier
GEM foil: 50 μm Kapton + few μm copper on both sides with70 μm holes, 140 μm pitch
Strong electrostaticfield in the GEM holes
VGEM
= 500 V → E ≈ 100 kV/cm
P = 140 μm
D = 70 μm
d = 50 μm
Multi-GEM Detectors
Cathode
Drift Region (3 mm)
GEM Foil
Induction Region (1 mm)
Anode (readout plane)
Maximum Gain 103
Cathode
Drift Region (3 mm)
GEM Foil
Transfer Region (2 mm)
Induction Region (1 mm)
Anode (readout plane)
Maximum Gain 106
Single-GEM Triple-GEM
GEM Prototype
GEM Prototype (10x10 cm2) built and tested at I.S.S. Roma
Assembling the GEM chambers parts requires a careful quality control at several check points and specific tools for gluing, heating, testing, cleaning
Assembling the first 40x50 cm2 module
11
Stretching
Gluing the nextframe with spacers
Tendigem made in Catania
12
FULLY equipped GEM module
• 18 front-end cards
• 2304 channels
(front end cards on the othe side)
• 7 independente HV levels
-Three GEM Chambers: 10x10 cm2
-Electron Beam energy 400 – 800 MeV
-Strip distance 0.4 mm
-Chamber distance 50 cm
-Carbon Target
-Lead glass and Plastic Scintillators
Beam test @ MAINZ 1/2Electron beam produced at MAMI (MAinz MIkrotron) at the Nuclear Physics Institute of Mainz
MAMI is a continuous wave accelerator
Beam test @ MAINZ 2/2
By using APV 25 chips, it is possible to register different parts of the signal (every 25 ns), event by event.
-Different run performed: with beam without beam (pedestal)
-Different angles between the electron beam and the plane of the GEM chambers
-Different HV settings
-Different Chamber positions
DATA ANALYSIS
-More than 50 beam run analyzed
-Study of the Pedestal
-Study of the Signal
-Study of the Clusters
-Beam Profile reconsctruction
-Tracking and Efficiency evaluation
SIGNAL OBTAINED BY USING A 90Sr SOURCE
ID RUN HV ID CHAMBER
218 2750 V 0 (FRONT)
233 3950 V 1 (MIDDLE)
240 3950 V 2 (BACK)
FRONT CHAMBER
MIDDLE CHAMBER
PEDESTAL RUN STUDY
ADC mean value obtained each 100 events in a single pedestal run: values change in different samples!IDEA: we decide to create a pedestal for each beam run by using the adc mean values of 200 events for all samples (1200 values).
signal
New pedestal
Beam run before the pedestal suppression
Beam run after pedestal suppression
SIGNAL
signal
ADC(A.U.)
Strips
1 strip = 0,4 mm
SIGNAL IN DIFFERENT SAMPLES
SAMPLE 1 SAMPLE 2 SAMPLE 3
SAMPLE 4 SAMPLE 5 SAMPLE 6
SIGNAL SHAPE
Signal shape:
- τ1 and τ2 are the slope and falling time of the signal, respectively;- t0 is the stop time;- A is the Amplitude;
Signal Amplitude for different strips.
Peak around strip # 200 (ok!) and more or less 0 in all the others.
2
0
1
0
1 tttt
eeA
STUDY OF THE CLUSTERS 1/2
A tree is filled, event by event, with different informations for each beam run:-Number of clusters;-Number of strips for each cluster;-Index of the first strip of each cluster;-ADC sum of each cluster;-Centroid of each cluster;
CLUSTERS NUMBER STRIPS NUMBER OF EACH CLUSTER
RUN #446 – 300 EVENTS – SAMPLE 2: from 0.25 to 0.50 ns
Centroids plot Adc sums of single cluster vs strip
VERY LOW PILE-UP!
STUDY OF THE CLUSTERS 2/2
Examples of CENTROID EVALUATION for 2 RUN with different Energy
ABOUT 4-6 mm400 MeV 800 MeV
Beam Profile
TRACKING AND EFFICIENCY1/2
Z
X
-POSSIBLE EVENT IF THERE IS A CLUSTER IN ALL CHAMBERS
-HIT POSITION WITH σ FOR EACH CHAMBER
-WE CONSIDER X = a*Z + b with a and b obtained by linear fit
-BY USING P0 (x0, y0) and P1 (x1,y1) WE OBTAIN a AND b
-WE CONSIDER P3 (x3,y3) and if lx3 -az3 –bl<σ3 THAN THE SIGNAL OF THE 3 CHAMBERS BELONGS TO THE SAME PARTICLE OTHERWISE IT IS REJECTED
TRACKING AND EFFICIENCY 2/2
EFFICIENCY=NUMBER OF EVENTS IN TRAJECTORY
NUMBER OF EVENTS (TRIGGER)
RESULTS FOR A RUN WITH HV = 3950 V
ID CHAMBER POSITION EFFICIENCY
0 Z=0 95%
1 Z=50 CM 85%
2 Z=100 CM 85%
CONCLUSIONS:
-GEM Tracker operated stably during the test at Mainz-Study of pedestal and signal-Study of clusters-Beam Profile was reconsctructed-Preliminary Efficiency was evaluated -GEM Tracker is a complex detector and improvement is still in progress
THANKS FOR YOUR ATTENTION