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Status report on ECAL

Status report on ECAL. TIM , Houston 8-12 Jan 2007 Marco Incagli - INFN Pisa for the ECAL group. IHEP Beijing, China (Group Leader : Hesheng Chen). INFN Pisa, Italy (Group Leader : F Cervelli). LAPP Annecy , France France (Group Leader: JP Vialle). International ECAL collaboration.

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Status report on ECAL

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  1. Status report on ECAL TIM , Houston 8-12 Jan 2007 Marco Incagli - INFN Pisa for the ECAL group

  2. IHEP Beijing, China (Group Leader : Hesheng Chen) INFN Pisa, Italy (Group Leader : F Cervelli) LAPP Annecy , France France(Group Leader: JP Vialle) International ECAL collaboration Project responsible : F. Cervelli Marco Incagli - INFN Pisa

  3. Where is ECAL Minimum amount of material (X0): • Last detector crossed by incoming (downgoing) particles • Thick detector in which particles interact in a destructive way 0.20 0.28 Upper TOF 0.32 Tracker Entry 0.40 Tracker Total 0.04 16.5 Tracker Exit ECAL Entry ECAL Total 16.1 ECAL Exit Marco Incagli - INFN Pisa

  4. ECAL = Electromagnet CALorimeter • A CALorimeter is a thick chunk of material in which particles deposit (part of) their energy (CÁLOR=heatenergy) • Most ground based experiments have large calorimetric systems CMS Marco Incagli - INFN Pisa

  5. fit Energy resolution (%) Energy deposited (GeV/layer) 50 GeV e- Some advantages of calorimeters • Resolution improves with the particle energy, differently from trackers in which resolution  momentum • Energy loss due to finite dimensions scales with the logarythm of the particle energy (therefore very slowly) Marco Incagli - INFN Pisa Longitudinal layer number

  6. Disadvantages of calorimeters • They are heavy! • Very different interaction cross sections for “light particles” (photons, electrons, positrons) wrt “heavy particles” (protons, deuterons, nuclei) • Often, in ground experiments, 2 calorimetric sections are foreseen CDF @ Fermilab ECAL : electromagnetic section HCAL : hadronic section Marco Incagli - INFN Pisa

  7. Calorimetry in space • due to limitations in weight, space experiments have just an ECAL section, normally with limited thickness • Standard measurement for “thickness” is the radiation length (X0) which is related to the development of the energy deposition by a particle • a detector with high X0 has a good energy and angular resolution and it is capable of measuring particles in the energy range 10GeV-1TeV with good accuracy (<5%) • e.g. : • AGILE : 1.5X0 • GLAST 10X0 • AMS-02 : 16.1 X0 Marco Incagli - INFN Pisa

  8. AMS ECAL • Thanks to the characteristics of the ISS (and of the Space Shuttle) AMS02 can take advantage of a calorimeter of unprecedented thickness and granularity, for space standards Marco Incagli - INFN Pisa

  9. Physics with ECAL • Very good positron/proton discrimination • Good energy reolution for positrons and photons up to ~1TeV • Detection of photons non-interacting in material above (~75% of the total) • Discrimination of nuclei Z by energy deposition • Trigger information on photons and on e± e+, p ? g

  10. Dark Matter searches in positrons • ~30% of the universe is made of matter of unknown origin: DARK MATTER • Most theories predict a surplus in the production of positrons, due to DARK MATTER • Hints from HEAT and AMS-01 • AMS-02 can measure this distribution with very small statistical error (<0.1%) … BUT … Marco Incagli - INFN Pisa

  11. …background subtraction • …BUT… what about systematic error? • A particular concern is the “background subtraction” • Proton flux higher by 104 ; to measure positrons at 1% need suppression factor of 106 • TRD provides a factor 102:103 • The ECAL standalone provides a factor 103 • Including the energy-momentum match, a further factor 10 is gained protons positrons Marco Incagli - INFN Pisa

  12. g g Photons can be detected in AMS field of view by two devices • TRACKER: uses conversion in 0.25X0 TRD material (max opening angle ~40o; conversion probability ~18%) • ECAL: uses the shower shape and asks for no hits in TOF counters (opening angle ~20o ; ~78% of the photons reach ECAL) e+ e- Marco Incagli - INFN Pisa

  13. ECAL structure • Sampling calorimeter with lead foils and scintillating fibers • Basic block is superlayer: 11 lead and 10 fiber layers • 9 superlayers with alternating x and y readout • Total thickness is 166mm, corresponding to 16.2 X0 • Total weight 634 kg p e Lead foil (1mm) Fibers (1mm) z 1.73mm particle direction FIBER LEAD y x

  14. Supporting structure and readout of AMS ECAL • The active part is inserted in a supporting structure which connects ECAL to USS • Light is readout with PhotoMultiplierTubes (PMTs) connected to fibers through light guides x y z 66 cm 18.5 mm Marco Incagli - INFN Pisa

  15. Pictures of ECAL production ECAL Marco Incagli - INFN Pisa

  16. Status of construction in short • Flight hardware: • detector : ready • front end electronics : ready and mounted on detector • readout electronics : QM tested, FM under construction, ready by end of April 2007 (boards + mechanics) • must undergo SQ tests (vibration + thermo-vacuum) • HV power supply : ready except for heaters and thermostats • must undergo SQ tests (vibration + thermo-vacuum) • LV power supply : under construction in Taiwan Marco Incagli - INFN Pisa

  17. Detector + front end electronics • Completed in September 2006 • Tested in CERN North Area experimental hall Oct 15-30 with protons of 150GeV and electrons of 6-210 GeV • Currently stored in class 100K clean area Marco Incagli - INFN Pisa

  18. Readout electronics : FM • Production started november, 2006 • Check of drawings : ok • Check of material : • PCBs all done • Electrical components all in stock except for few connectors to be soldered on ECAL Back Plane (EBP) • Mechanical parts front panels done and anodized; to be treated with alodine for conductivity. • Crate production in Pisa: Feb,1  May,1 . • Surface treatment (white paint): May,1  May,15 Marco Incagli - INFN Pisa

  19. 3 EBP (backplane), 2FM+1FS , mounted and inspected  to be tested in Pisa • All electronics ready by end of April Marco Incagli - INFN Pisa

  20. HV power supply Flight HV ready and mounted on temporary stand Missing parts: heaters (2) thermostats (4) reflecting tape Offer requests sent this week to CGS 3/4 months for delivery Marco Incagli - INFN Pisa

  21. LowVoltage: ERPD crate • FM • Electronics: • DC/DC were tested in Taiwan by J. Marin. • Board with failures repaired by CAEN now at CIEMAT (Madrid). • Ready to be sent to Taiwan for final test and coating. • Mechanics: • Items 5,6,7 ready • Material for the rest of items 1,2,3,4 sent to IAC. Marco Incagli - INFN Pisa

  22. ECAL test beam • ECAL mounted on rotating table and carried to CERN • ECAL FM has been mounted on a frame and equipped with FM or QM electronics; work done at LAPP, Annecy (FR) on sep-oct 2006 Marco Incagli - INFN Pisa

  23. ECAL at test beam • ECAL in the test beam area covered to protect flight hardware (color chosen by Sylvie…) Incoming beam Marco Incagli - INFN Pisa

  24. Not only ECAL test beam ECAL Tracker: 4 ladders Ecrate 0 Cherenkov counters Trigger counters Ecrate 1 NIM crate NIM LVDS JTBOX JLV1 JINJ PCI AMSWIRE JTCRATE Marco Incagli - INFN Pisa

  25. A complex DAQ system • Software for readout written by Stefano Di Falco with the help, or based on the programs, of P.Azzarello (Perugia), D.Haas (Geneve), A.Kounine (MIT), A.Lebedev (MIT) • Request from Helsinky University of Technology (Finland) to provide raw data taken at test beam in order to test data transfer with real AMS data E0-crate E1-crate T-crate E T R G J I N F E T R G J I N F J I N F 8 AMSWire cables 10 m long E T S H W E I R T N C E H T J L V 1 J T B X J I N J JT-crate PCI-AMSWIRE 2 AMSWire cables Ethernet Cable 50 m PARALLEL PORT EPPCAN Linux PC Marco Incagli - INFN Pisa External Trigger

  26. Trigger system : rather elaborate! Internal oscillator: pedestals evaluation (asynchronous trigger) “TOF” window: used by external scintillator counters Fast trigger window: ECAL, counters, Cherenkov Level 1 window Marco Incagli - INFN Pisa

  27. Main goal of test beam: ECAL calibration • To “calibrate” ECAL means to know its response to an impinging particle of known energy • We use “Minimum Ionizing Particles” (MIPs) : hadrons, tipically protons, or muons (cosmic rays at sea level) which cross ECAL without interacting with the lead nuclei but just with the external electrons of the material • Trajectory and energy of MIPs are marginally modified by this process: a MIP proton deposits 0.125GeV crossing ECAL. MIP Marco Incagli - INFN Pisa

  28. MIP cross scan 4 rows • Proton runs with 20k events along y and x axis • Each run hits the center of a PMT column • Total of 72 runs per each cross (12 hours of data taking) • 4 MIP scans: • Nominal voltage • Nominal voltage+50Volts • Nominal voltage • Nominal voltage+80Volts • Changing voltage varies signal amplification 5 rows x y Marco Incagli - INFN Pisa

  29. MIP distribution • Typical distribution of energy deposited by a MIP in an ECAL cell, in ADC counts, fitted with a Landau distribution • The different peak position reflects the different voltage (=amplification) • Note that a too large amplification limits the dynamical rangeof the amplifier Nominal HV Peak = 17.2 ADCcounts Nominal HV + 50Volts Peak = 32.7 ADCcounts Marco Incagli - INFN Pisa

  30. Mip distribution • Problem in “zero suppression” algorythm • We know how to fix this software problem; new software tested with cosmic rays MIP peak (ADC counts) Marco Incagli - INFN Pisa

  31. Beam profile using tracker layers • 4 tracker ladders, in front of ECAL, have been used to measure the beam profile and to know the particle hit position event by event • The beam profile changes with particle type (electrons vs protons), beam energy, primary beam polarity, … • Beam dimensions ~2×2cm2; each strip is ~100mm BLACK = 3 ladders RED = 4 ladders 1 cm BLACK = 3 ladders RED = 4 ladders 1 cm Marco Incagli - INFN Pisa

  32. Tracker-ECAL correlation Beam profile : yview Beam profile : xview ECAL cells Marco Incagli - INFN Pisa 0.9cm : ECAL cell size

  33. Testing the trigger • ECAL trigger • ANALOG part on ECAL Intermediate Board (EIB) • DIGITAL part (=trigger logic) in ETRG board EIB to ECAL crate R PMT dynode D Q 1 + FF + 10 comp - - Output Signal from PMT Programmable threshold thresh Marco Incagli - INFN Pisa

  34. 100 80 60 40 20 0 Efficiency (%) Trigger threshold Deposited energy (SADCcounts) Test of analog part of trigger • Trigger efficiency as a function of deposited energy in single cell • Varying the programmable threshold, the trigger threshold moves Trigger threshold Trigger threshold Marco Incagli - INFN Pisa

  35. Y X Z Electron runs • Electron can release, in a given cell, an amount of energy which is several thousands larger than that of a MIP • In order to cover the full energy range, the signal is split in 2 and 1 branch is divided by a factor ~30 before ADC PMT (PhotoMultiplier Tube) PMT cell High gain Low gain Marco Incagli - INFN Pisa

  36. High gain vs low gain • We expect a straight line, but on some cells we see a spurius population  under study High Gain High Gain Low Gain Low Gain Marco Incagli - INFN Pisa

  37. Linearity plot : ADC counts vs beam energy • As a consequence • Anode ADC counts vs energy shows 2 slopes, up to 30GeV and from 50GeV up . No corrections for energy leakage applied • Linearity plot with dynode (again no corrections) shows a linear behaviour • Under investigation Marco Incagli - INFN Pisa

  38. Conclusions • ECAL ready for integration • FM electronics in production; ready end of April 2007  need to do SQ tests for all crates (Ecrate+HV+LV) ! • Test beam • shows good results in terms of MIP (protons) analysis; some unclear results for more energetic (tipically electrons) energy deposits  under investigation • very useful to debug and calibrate flight hardware and firmware ; positive test of trigger system and of DAQ procedure • More results at next TIM Marco Incagli - INFN Pisa

  39. BACKUP SLIDES

  40. Problems in zero suppression • In order to limit the bandwidth, only channels with an ADC count value above some limit (>2 in our case) are written out • This procedure is called zero suppression and it is authomatically run at the beginning of each data taking • Due to the large beam rate, some times a spurius event enters in the evaluation of the pedestal shifting its value SMALL pedestal shift Distribution cut at 9 ADC counts Fit is still possible Peak = 17.5 counts LARGE pedestal shift Distribution cut at 26(!) counts Fit is not possible Peak = ? Marco Incagli - INFN Pisa

  41. Mip distribution • We know how to fix this software problem; new software will be tested with cosmic ray runs • The effect is uncorrelated with the PMT number, so >90% of ECAL cells (1324 in total) have been equalized using the two scans at nominal voltage • Remaining channels can be equalized with ground level cosmic rays (muons instead of protons, but same properties for equalization) Marco Incagli - INFN Pisa MIP peak (ADC counts)

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