New Small Wheel Front-End and Back-End Electronics - Siyuan Sun on behalf of the ATLAS Muon Collaboration
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
New Small Wheel Front-End and Back-End Electronics Siyuan Sun on behalf of the ATLAS Muon Collaboration 23/9/2021 Siyuan Sun, TWEPP 2021 1
Why New Small Wheel? • HL-LHC instantaneous luminosity: 5 − 7.5 × 1034 cm−2 s−1 • Cavern background rate increase exponentially when closer to beam-line up to ~20kHz/cm−2 / 1 MHz per Chan. • NSW detector must be able to operate efficiently at this high rate and aid in triggering in coincidence with large wheel Big Wheel Small Wheel Need to reduce fake trigger rate in endcaps 23/9/2021 Siyuan Sun, TWEPP 2021 2
MicroMegas (MM) Detector • Micro-Mesh gaseous structure • Precision tracking: σr ≤ 100 µm, ~1 mrad Primary electrons due to ionization in drift volume MM Basic Parameters Drift distance 5 mm Pillar height 128 μm Resistivity 1-4 MΩ/cm Readout Strip Pitch 425/450 μm Amplification in amplification gap between Ar+7% CO2 Operating Gas mesh and resistive electrodes (+2%Isobutane) Mix 23/9/2021 Siyuan Sun, TWEPP 2021 3
small-strip Thin Gap Chamber (sTGC) • Multiwire proportional chamber • Spatial resolution: σr ≤ 100 µm • Angular resolution: ~1 mrad • Pad used to quickly obtain region of interest • Strips used for precision tracking sTGC Basic Parameters Cathode-anode gap 1.4mm Wire pitch 1.8mm Cathode Resistivity 100-200 kΩ/□ Strip Pitch 3.2mm Operating Gas N-pentane + 45%CO2 23/9/2021 Siyuan Sun, TWEPP 2021 4
Main Front-End ASIC: VMM • Amplifier + Shaper for 10 bit ADC for precision charge measurement (dead-time: 250ns) both MM+sTGC 8 bit TDC for timing information • Large analog dynamic 6 bit ADC for fast trigger charge information (dead-time: 40ns) range Fix latency • Detector capacitance: Trigger data ~100 pF – 3 nF Trigger matched • Input charge: ~70 fC – Readout data 50 pC (cavern bkg) • Linear response up to 2 pC • Ability to quickly recover TTC input from large charges Configuration Data buffer + Event Builder using SPI (~500ns) L0 trigger matching 23/9/2021 5 Siyuan Sun, TWEPP 2021
Slow Control input TTC/Clock input Front End Boards Monitoring output Readout data output DC-DC converter • VMM • Amplifier Shaper • ADC DC-DC • Slow Control ASIC (SCA) converter • Configuration • Monitoring + Calibration • Readout Controller (ROC) • Clock distribution • TTC distribution • Readout data aggregator Slow Control input TTC/Clock input DC-DC • L1 trigger matching Monitoring output Readout data output converter • Event builder • Data serializer and TX • Up to 4x320 Mbps or DC-DC • 640 Mbps converter • Trigger Data Serializer (TDS) • Gigabyte transceiver used to send trigger data • DC-DC converters on board 23/9/2021 Siyuan Sun, TWEPP 2021 6
Back-End Electronics: Data Readout Detector Save data to analog input hard-drive Back-end data acquisition system hits assembled into Gigabit transceiver trigger matched events Conversion to optical signal 23/9/2021 Siyuan Sun, TWEPP 2021 7
swROD • Collect readout FELIX data from all FE electronics • save data to • Used as universal slow hard-drive control + readout system • Software for all ATLAS phase I+II specific for upgraded detectors. NSW decodes • Communicate with data network using • Broadcast readout Ethernet/infiniband data to network • Acts as a server PC. • Distribute TTC, clock • Communicate with • send configurations front-end electronics • Receive monitoring through optical fibers data on 4.8 Gbps links • Receive readout data 23/9/2021 Siyuan Sun, TWEPP 2021 8
sTGC Trigger Algorithm sTGC Quad Find 3 out of 4 coincidence in pads to find region of interest Hits in pads Muon Hits on strips Read out 6 bit charge info from Null Reconstruct strips corresponding to region of Rejection+ segments interest Convert to fiber optic 23/9/2021 Siyuan Sun, TWEPP 2021 9
sTGC Trigger Electronics Pad Trigger Board Rim L1DDC 8x Router • Receive pad trigger signal • Slow control • Receives strip hit data • Programmable 3 out of 4 • Clock distribution • Forwards data to trigger pad coincidence to • Monitoring processor through fiber determine region of interest • Data sampling • Sends ROI info to strip FEBs 23/9/2021 Siyuan Sun, TWEPP 2021 10
MM Trigger • Look for hits that line up along a “road” pointing from the interaction point • 8 MM detector layer: Interaction • 4 horizontal x-layers point • 2 stereo u-layers Identified Region • 2 stereo v-layers of interest u layer 1.5 ° • u/v stereo layers are tilted by 1.5 degrees with respect to horizontal x- x layer layers • Hits in stereo layers further narrows Muon v layer down the region of interest location 23/9/2021 Siyuan Sun, TWEPP 2021 11
Gigabit transceiver send data to trigger MM Trigger Data Path processor via fiber optic to trigger processor • ART ASIC aligns and deserializes the 32x input data streams • Selects up to 8 hits • Send a package of hit data + BCID time stamp to VMM sends location of first hit every 25ns (Address Gigabit transceiver in real time/ART) to ART data driver card (ADDC) 23/9/2021 Siyuan Sun, TWEPP 2021 12
NSW Trigger Processor • Construct MM + sTGC segments based on trigger hit data • Remove duplicate segments and construct combined MM+sTGC segment • Send segment information to ATLAS sector logic for match with big wheel and L1 muon trigger reconstruction Slow control + monitoring 23/9/2021 Siyuan Sun, TWEPP 2021 13
NSW Trigger Processor 6.4 Gbps segment output 1st sector Interface to 1x 4.8 sTGC sTGC backend detector pad input links FPGA control system and 32x 4.8 sTGC monitoring strip input links MM 32x 4.8 MM FPGA input links 6.4 Gbps segment output sTGC FPGAs with 1x 4.8 sTGC FPGA algorithms to pad input links reconstruct 32x 4.8 sTGC MM segments strip input links FPGA 32x 4.8 MM 2nd sector input links 23/9/2021 Siyuan Sun, TWEPP 2021 14
Detector Integration + Commissioning Validate all on- detector electronics Final back-end connectivity + electronics used* functionality *only enough to MM checks detector run 3 sectors at performance with once cosmic muons sTGC checks detector HV and gas leak. 23/9/2021 Siyuan Sun, TWEPP 2021 15
Examples of Commissioning Tests sTGC Test Pulse Hits in Readout Chain MM cosmic track efficiency map Receive test pulse hit for every sent Single dead channel 23/9/2021 Siyuan Sun, TWEPP 2021 16
Examples of Commissioning Tests Eye Diagram from sTGC trigger link Received sTGC Trigger Packets 23/9/2021 Siyuan Sun, TWEPP 2021 17
Tie each individual layer to the outside copper faraday cage One connection near each FEB for sTGC 1. Reference that voltages are compared to 2. Large charge reservoir which can absorb large amounts of current without changing it’s potential 3. Equipotential “0” of the system 4. The common return path for all current Connection of MM ground to it’s support frame 23/9/2021 Siyuan Sun, TWEPP 2021 18
High Frequency common mode LV Power Supply Added CM filter to power disturbances flow back via shield supply 300 V Control 10 V to input Unit Detector + + - - Shield Switch Transformer Rectifier 23/9/2021 Siyuan Sun, TWEPP 2021 19
Effect on Electronics Noise MicroMegas Noise sTGC Noise Before After Before After High noise channels improved High noise channels improved 23/9/2021 Siyuan Sun, TWEPP 2021 20
Current Status Wheel C finishing commissioning Wheel A installed inside ATLAS Scheduled for installation this November 23/9/2021 Siyuan Sun, TWEPP 2021 21
Conclusion • Detailed look into the New Small Wheel front end and backend electronics • Electronics, detector, power-supply form a inseparable interconnected electrical system • Planning of low impedance paths to return for each current path is critical when there are sensitive amplifiers involved • New Small Wheel is on schedule to have both wheels installed in ATLAS during long shutdown 2 this year. 23/9/2021 Siyuan Sun, TWEPP 2021 22
Backup Slides 23/9/2021 Siyuan Sun, TWEPP 2021 23
Detector Ground 1. Reference that voltages are compared to 2. Large charge reservoir which can absorb large amounts of current without changing it’s potential 3. Equipotential “0” of the system 4. The common return path for all current Outer metallic shell = Thick copper Largest charge reservoir = wire to wheel “Ground” 23/9/2021 Siyuan Sun, TWEPP 2021 24
Stronger Together 4 layers tied together + outside Each layer faraday cage • Now disturbances of the same by itself power level (dBmW) will disturb the voltage of fully connected ground (mV) much less • = 6 2 ~ 4 0 = 40 5 VS 1 1 • ΧC = ~ = 2 f 2 ∗ 5 ∗ 40 ~1 Ohm • The grounds were never truly isolated at high frequency Easily disturbed by anyways Much more difficult to current/EM waves wiggle the combination 23/9/2021 Siyuan Sun, TWEPP 2021 25
Chapter 3: Common vs Differential Mode Current Power Power Shield Shield Return Return • In the ideal case, we send power and signal over • Situations can arise where both power and “differential pairs.” return inject “common mode current” • One line to send, one line to return • Common mode current cannot return via the return as it is also being injected via return. • The shield serves as a third path for common 23/9/2021 Siyuan Sun, TWEPP 2021 mode current to return 26
Common mode current can return via copper faraday cage 23/9/2021 Siyuan Sun, TWEPP 2021 27
FEB Connected to Detector Layer Signal path Each front-end board is connected to it’s Return path own layer. Layers are not connected to one another except at one point with a copper wire ~1cm ~1m Inductance for center channels ~ 300 nH impedance = 2πf * L ~ 10 Ohm at 5 MHz Significant impedance to GND for central channels at high frequencies 23/9/2021 Siyuan Sun, TWEPP 2021 28
Adding one jumper Trigger cables not terminated - Blue PFEB QL3L2 Adding first jumper. – Red Does not help the noise much. Trigger cables terminated - Pink JUMPER 29
Adding second jumper Trigger cables not terminated - Blue PFEB QL3L2 Adding second jumper. – Green Helps the noise in the circled area. Channels on VMM C Trigger cables terminated - Pink JUMPER 30
Adding third jumper Trigger cables not terminated - Blue PFEB QL3L2 Adding third jumper. – Brown Helps the noise in the circled area. Channels on VMM B Trigger cables terminated - Pink JUMPER 31
Controlling current return path VS https://learnemc.com/grounding 23/9/2021 Siyuan Sun, TWEPP 2021 32
No Degradation of Noise when More Detectors are Turned On Simultaneously 23/9/2021 Siyuan Sun, TWEPP 2021 33
Ground Impedance Turns Electronics Components into Parallel Circuits Component 1 Impedance on GND G Component 2 23/9/2021 Siyuan Sun, TWEPP 2021 34
sTGC Cross-Section Gas amplification: 2e5 1.5 pC charge deposited per MIP (MPV of landau) 23/9/2021 Siyuan Sun, TWEPP 2021 35
MicroMega Detector Mesh = GND Copper Drift HV plane Back Aluminum Amplification HV / Signal Frame Strips 36
MicroMega Braids Additional Copper Jumpers Back Aluminum Frame Drift HV Front Aluminum Mesh = GND Frame Amplification HV / Signal Strips 37
Rim L1DDC sTGC Trigger pad trigger find clk dist., config 8x Routers 3 out of 4 pad tower coincidence Data Path Determine ROI Strip info output: 4.8 Gbps pad hit fiber to trigger information processor Region of interest 4.8 Gbps strip Input hit information Pad Front-End Board 23/9/2021 Siyuan Sun, TWEPP 2021 Strip Front-End Board 38
Rim Crate Contains Trigger Electronics Rim L1DDC Pad trigger 8x Router One per layer Water cooling system in the crate cools the electronics 23/9/2021 Siyuan Sun, TWEPP 2021 39
NSW Trigger Latency Budget 23/9/2021 Siyuan Sun, TWEPP 2021 40
23/9/2021 Siyuan Sun, TWEPP 2021 41
23/9/2021 Siyuan Sun, TWEPP 2021 42
You can also read
