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gillian-nguyen

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SuperB igbite Spectrometer in Hall A
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  1. SuperBigbiteSpectrometer in Hall A • Large luminosity • Moderate acceptance • Forward angles • Reconfigurable detectors Background: photon (250-500 MHz/cm2) charged (160-200 kHz/cm2) Physics: Nucleon Form Factors SIDIS – TMD’s ... Nucleon structure Front tracker reused in BigBite

  2. Silicon Detectors

  3. GEM

  4. Main Technical solutions • Use the COMPASS approach: 3xGEM, 2D readout - onesignificantdifference: use new single mask GEM foil (instead of double mask) – cheaper and faster production • Modular design: chambersconsists of 3 independent GEM modules (40x50 cm2) with thin dead area • Electronicsaround the module, direct connection; 90 degree bending betweenmodules • Externalsupport frame in carbon fiber (long bars) to minimizethermaldeformation 40x50 cm2 module Front Tracker Chamber: 40x150 cm2

  5. GEM Module construction process Module production fully established in INFN-Catania Electronics preliminary QA in Genoa Module integration and characterization in INFN-Sanità Permaglas Frames Visual Inspection Ultrasound bath cleaning GEM Foils HV curing and quality test Stretching Production rate 2 module in 3 months Put together (align on reference pins) Gluing Assembling gas lines Electronics Test Clean room Glue Curing (>24 h) Finalization (solder resistor, check HV) Electronics integration Test and characterization by rad. source and cosmics

  6. DESY/EUDET Pixel Telescope 3 Big GEMs Reference Small GEM SBS GEM Tracker - Test Beam / Jan 2014 • Small scale final system (gas, LV, HV monitored) • Main Goals: • Characterize chambers in terms of charge sharing, efficiency and spatial resolution at different HV, gas mixture. • Figure out the gain variation of the previous test 1-4 GeV Electron Beam AIDA-EUDET support → Got lot's of good data with high spatial resolution information from pixel telescope → Stable performance (“all” conditions carefully monitored)

  7. GEM Production and Test Status • The very first 4 GEM foils did not pass the original quality checks, 3 recent GEM foils of the same bunch did not pass the quality check • One readout + honeycomb suffered bad gluing (probably still usable) • 2 of the GEM modules passed preliminary tests but then degraded significiantly (large dark current due to (? gas contamination ?); still chance to fix them. • *** soldering problem, bug fixed

  8. SBS Coll. Meeting - Front Tracker GEM Schedule and Status Development phases in part affected by constraints in the flow of funding Delivery delay of the GEM foils from CERN for prototyping and pre-production (no significant impact in SBS, we started erlier) During pre-production we made some fine optimization: • GEM foil, details in construction procedure; • one drastic change in foil quality check. Development includes: GEM chambers, readout electronics (and related software)

  9. Kalman Filter Reconstruction: simulation TrackAssociation by NN / Simulation Sij – neuron (0 or 1) – connection between two points Residues Energy Vij Neuron changing rate

  10. GEM Tracker Activity 2014-2015 • Continue Production • Test, Characterization and Calibration of GEM and electronics • Fix damaged modules/material, replace if no fix possible • Finalization of a rubust and efficient track reconstruction algorithm • Complete and test the complex firmware of the DAQ • Study (and solve) open issues

  11. Electronic (GEM + Silicon detector)

  12. Electronic Status MPD v 4.0 firmware update Revisedmemorymapping D64 read only cycle implemented: MBLT, 2eVME, 2eSST 2eSST simulatedpeakspeed: 148, 222, 296 MB/s Event builder implemented and simulated TBD Multiboardblock transfer Analyze use of fiber optic protocol MPD v 4.0 VME interfacetesting 2eSST cyclestested with STRUCK SIS-3104 2eSST supported by new firmware release Readoutspeedmeasured by software: 100 transfer 4MB each. Data integritychecked for eachblock.Speedlimited by SIS3104 2Gb/s fiber connection Bus speed is measured directly on VME bus Event Builder Implemented multi event block structure as suggested by DAQ people. Native data width: 24 bit, packed to 32 bit on 64 bit boundary for efficiency. Implemented 128MB FIFO data buffer using DDR2 SDRAM. Quite complicate machinery used to arbiter read and write to/from DDR2. Output can be read in 32/64 bit format in any of the supported VME cycles, including 2eSST. Performed functional simulation (FPGA + DDR2 + ADC) of quite simple events to follow all the signals. Some effort has to be put in DAQ driver to recover packed data.

  13. Electronic Activity 2014-2015 • Analyze a possible implementation of fiber optic data link to be connected to the SSP • Implement Multi Board block transfer (some hints needed) • Deep debug and test (implies rewriting of some DAQ code)

  14. HCAL

  15. Hcal Italianactivity SBS Coll. Meeting - Front Tracker GEM

  16. HCAL 2014-2015 activity

  17. Analysis

  18. 9Be(e,e’K)9LiL (G.M. Urciuoli et al. Submitted to PHYS REV C) Radiative correctedexperimentalexcitationenergy vs theoretical data (thin green curve). Thick curve: fourgaussianfits of the radiative corrected data Experimentalexcitationenergy vs Monte Carlo Data (red curve) and vs Monte Carlo data with radiative Effects“turned off” (blue curve) An elementary model for the (e,e′K+) reactionwith a different balance of spin-flip and non-spin-flipamplitudesmighthelp to resolve the disagreement with theory of the relative strenght of the peaks in the doublets

  19. Experiment E07-002 Present result for KLL in E07-002 seems to confirm previous measurement of E99-114, at a different angle. Work in progress. Study of systematic uncertainties is undergoing. Optimize analysis in order to conclude that at our energy regime, pQCD predictions are excluded. With those points included, ready for publication

  20. Studies on 3He asneutroneffectivetarget in SIDIS

  21. Support Slides

  22. Workforce and funding • *) one mechanical engineer • **) electronic engineer • INFN/Funding: • Prototyping and Production (2008-2014): 800 kUSD • Production and Maintainance (2015-2017): ~50 kUSD/year

  23. Assembling Improvements in Catania Several small but effective impromevents during last 2 years; one of the most relevent is the compression system during glue curing --- From Lead to vacuum --- Current System based on vacuum bag Very uniform pressure for glue degassing Old System based on Lead Bricks SBS Coll. Meeting - Front Tracker GEM Original idea from LNF- Bencivenni Group

  24. Test and characterization setup Almost finalized Use small 10x10 GEM as «reference» (in series) Large scintillation pads for cosmic Test up to 3 large GEM simultaneously SBS Coll. Meeting - Front Tracker GEM

  25. HV divider and new GEM foils «spike» signal output HV connector HV Divider and spike monitor circuit SBS Coll. Meeting - Front Tracker GEM Protective SMD resistors Reasonably compact, Easy to change Include output signal for «spike» detection

  26. Spacers shadow Cluster distributions of 9 cumulated runs Spacer Spacer shadowof ≈ 2 mm → 2.2% of total dead area of a single GEM module (Cluster finding not optimized for spacer border) Spacer Masked channels SBS Coll. Meeting - Front Tracker GEM

  27. Simulated Start Time Reconstruction Zoom Use double exponential function to fit 6 samples extracted with uniform random jitter (±12.5 ns) and poissonian amplitude distribution + gaussian noise. Optimal latency setting: first sample around the beginning of the signal SBS Coll. Meeting - Front Tracker GEM Reconstructed Start Time (t0) Error on t0 Chi2 of the fit

  28. GEM Beam Test: Spatial Scan – Start Time Start time increase slightly (but within uncertienties) Start time basically constant or sligtly decreasing (opposite to y ?) SBS Coll. Meeting - Front Tracker GEM

  29. GEM Test Beam: spatial uniformity – Hit Cahrge SBS Coll. Meeting - Front Tracker GEM

  30. Background level of: • 400 MHz/cm2 photons • 200 kHz/cm2 charged • Signal width ≈ 250 ns → Hits/cm2/trigger ≈ 0.1 → Ghosts/cm2/trigger ≈ 10-20 ! • Three steps track reconstruction: • Suppress accidentals and ghost with time and charge correlation • Associate hits with global analysis (neural network approach) • Precise track reconstruction on remaining candidate tracks by Kalman filter method SBS Coll. Meeting - Front Tracker GEM

  31. SBS Coll. Meeting - Front Tracker GEM “Residual Noise” on first APV channels Condition: 4 cards connected to chamber (one by flat adapter) Cards connected to VME by 20 m long HDMI cables Evident noise on first few (up to 8) channels of each card; This noise is somehow masked in the card with adapter (this is way we never put great attention to it in the past) Baseline noise at the level of 7 ADC channel. Pedestal Strips, physics order RMS of Pedestal Card + Flat Adapter GEM VME MPD HDMI cable

  32. SBS Coll. Meeting - Front Tracker GEM Electronics Misconfiguration Issue Electronics Low Voltage monitor 2 power lines for 2 groups of cards Small current drop during APV configuration; the “normal” level must restore In case of proper configuration; otherwise the electronics does not work properly Chamber appears inefficient → this likely explain the gain issue in 2013 DESY test

  33. SBS Coll. Meeting - Front Tracker GEM BARI Gas System w/Humidity Sensor and Absorber Series operation Series operation or GEM_50x40 or GEM_50x40 ~ 20 m long pipe < 100 ppM of H2O ~10 m ~10 m ~ 20 m long pipe

  34. SBS Coll. Meeting - Front Tracker GEM GEM Test Beam: spatial uniformity – Charge Sharing HV=4100 Ar/CO2=70/30 Charge asymmetry = 2 (Cx-Cy)/(Cx+Cy) ≈ 0.4÷0.5 → x/y Charge Sharing ≈ 1.5-1.6 y NOTE: some x/y hits can be not correcly associated or have pileup due to events with 2 or 3 particles/pulse Charge asymmetry spread ≈ 0.3 x

  35. SBS Coll. Meeting - Front Tracker GEM Reconstruction Efficiency vs #Event Efficiency holes in some of the runs: beam instability ? Lost synch with trigger ? Good run Analysis work in progress, recently master student from Catania joint. Several data to be analyzed

  36. SBS GEM Test: typical event (single module) T0+25ns (A1) T0+50ns (A2) cluster T0+125ns T0 (A0) x - Strip y - Strip Combination of T0, T0+25ns, T0+50 ns Fit of hit signal evolution Readout dual layer (x bottom and y top) strip plane

  37. SBS GEM Test: measured quantities (run 499) cluster charge max strip charge beam position cluster width max peak sample # clusters x y x/y Note: beam cross-section ≈ 3x2 mm2, approx. 30% with 2 or 3 hits in beam pulse

  38. SBS GEM Test: signal evolution fit (run 499) 6 sample fit! Integral Start time (t0) Leading Const. Trailing Const. Chi2 x y x/y tau0 ≈ 20 ns, tau1 ≈ 90 ns, RMS(t0) ≈ 4-5 ns

  39. GEM Beam Test / Time resolution • Excellent (surprising ?) start time spread (from fit) < 5 ns • expected at the level of 25/sqrt(12) ≈ 4 ns (in case of negligible contribution from electron drifting in GEM) • x/y start time reasonably correlated • no apparent effect of MPD clock synch • time spread depends on choice of APV latency (see next slide) Test beam pulse period 160 ms, multiple of APV clock period Time spread < 5 ns!

  40. GEM Beam Test: Spatial Scan – Start Time Gas flow rate: 54.3 ccm (0.5V/h) • Peak Sample • Start Time (fit) Look reasonably consistent Peak Sample vs V/h: 2 V/h: 1.2 ±0.4 1 V/h: 1.2 ±0.4 0.5 V/h: 1.3 ±0.5