The Glast Tracker Construction in Italy

Transcription

1 The Glast Tracker Construction in Italy Ronaldo Bellazzini Space Part Meeting Elba Island, May 22

2 The GLAST tracker construction The GLAST Gamma Ray Large Area Telescope GLAST is a pair conversion telescope based on a 8mq Silicon tracker and a CsI Electromagnetic calorimeter directly derived from the high energy experiments. GLAST will explore the uncovered energy spectrum from 3MeV to 1TeV. The tracker/converter is a very complex device, with about 1Milion readout channels, instrumented with single side silicon strip detectors. A modular design and the large use of industrial partners allow a fast and high quality construction. look in presentations

3 First Came EGRET Launched in April 1991 Observed over 6 AGN in > 1 MeV gammas. About 1/2 dozen GRB at high energy. Measurement of diffuse gamma ray background to over 1 GeV. One hundred and seventy unidentified sources in 3rd EGRET catalog. Mystery of unidentifieds since 197s Raised many interesting issues and questions which can be addressed by a NASA mid-class mission (Delta II). Sources in Third EGRET Catalog

4 .1 GeV.1 GeV Supernova Remnants GLAST Science 1 GeV 1 GeV 1 GeV Map the High-Energy Universe 1 TeV AGN GLAST pulsar survey: provide a new window on the galactic neutron star population. Map the pulsar magnetosphere and understand the physics of pulsar emission. Origin of cosmic-rays: characterize extended supernovae sources. Determine the origin of the isotropic diffuse gamma-ray background. Area (square cm) GLAST EGRET discovery reach Physics in regions of strong gravity, huge electric & magnetic fields: e.g. particle production & acceleration nea the event horizon of a black hole. Use gamma-rays from AGNs to study evolution of the early universe. Physics of gamma-ray bursts at cosmological distances. Probe the nature of particle dark matter: e.g., wimps, 5-1 ev neutrino. Decay of relics from the Big Bang Energy (GeV)

5 Pair-Conversion Telescope Photons materialize into matter-antimatter pairs: Charged particle anticoincidence shield Conversion foils Particle tracking detectors Calorimeter (energy measurement) g e+ e- E g -> m e+ c 2 + m e- c 2 GLAST Concept Low profile for wide f.o.v. Segmented anti-shield to minimize selfveto at high E. Finely segment calorimeter for enhanced background rejection and shower leakage correction. High-efficiency, precise track detectors located close to the conversions foils to minimize multiple-scattering errors. Modular, redundant design. No consumables. Low power consumption (58 W)

6 The Large Area Telescope (LAT) Tracker Array of 16 identical Tower Modules, each with a tracker (Si strips) and a calorimeter (CsI with PIN diode readout) and DAQ module. Surrounded by finely segmented ACD (plastic scintillator with PMT readout). Grid DAQ Electronics ACD Calorimeter Thermal Blanket Aluminum strong-back Grid, with heat pipes for transport of heat to the instrument sides.

7 TKR Flight-Tower Design & Assembly Tower Structure (walls, fasteners) Engineering: SLAC, Hytec Procurement: SLAC. Italy SSD Procurement, Testing Japan, Italy, SLAC SSD Ladder Assembly Italy Tower Assembly and Test Italy (18) 1, Tray Assembly and Test Italy 342 Cable Plant UCSC 18 Electronics Design, Fabrication & Test UCSC, SLAC 648 Composite Panel & Converters Engineering: SLAC, Hytec, and Italy Procurement: Italy 342

8 GLAST Tracker Design Overview 16 tower modules, each with 36cm 36cm of active cross section 83m 2 of Si in all, like ATLAS 115 SSD, ~ 1M channels 18 x,y planes per tower 19 tray structures 12 with 3% W on bottom ( Front ) 4 with 18% W on bottom ( Back ) 3 with no converter foils Every other tray is rotated by 9, so each W foil is followed immediately by an x,y plane of detectors 2mm gap between x and y oriented detectors Trays stack and align to the side walls The bottom tray has a flange to mount on the grid. Electronics on sides of trays: Minimize gap between towers 9 readout modules on each of 4 sides Electronics flex cables One Tracker Tower Module Carbon thermal panel

9 Status of the construction activities in Italy SSD receiving (22 SSDs up to now) and testing: I-V curve C-V curve Dimensional test Test status Total SSD dimensional 1527 electrical 145 Ladder assembly and test Ladder assembly Ladder bonding and encapsulation I-V curve C-V curve Alignment measurement electrical AND dimensional 1224 electrical OR dimensional 1744 Engineering Model construction Tray assembly Tray thermal and vibrational tests Tower assembly

10 SSD Pisa clean room measurements Electrical strips (p+) grounded / back plane (n) at variable V(+) use calibrated instrumentations (Vsource,p-ammeter,LCR) read through GPIB/LabView data can upload DB automatically IV scan -2V Ileak at 15V CV scan -2V Cbulk at 15V Vdep with: 2 fit intersection HPK definition

11 Leakage current distributions Leakage 15 V Pisa HPK Average Min Max RMS entries all SSD laboratory manufacturer Leakage current (na) batch analysis average leakage current (na) SWX6375 SWX6563 SWX6566 SWX6568 SWX67 SWX673 SWX679 SWX6734 SWX6736 SWX6742 SWX6745 SWX6747 SWX677 SWX6772 SWX6774 SWX6777 SWX6822 SWX Batch

12 Bulk capacity ditributions Bulk 15 V 3 25 Pisa HPK Average Min all SSD Max RMS entries 15 (th) ~ C/C x (th) ~ 2 µm Bulk capacitance (pf) batch analysis average bulk capacitance (pf) laboratory manufacturer 176 SWX6375 SWX6563 SWX6566 SWX6568 SWX67 SWX673 SWX679 SWX6734 SWX6736 SWX6742 SWX6745 SWX6747 SWX677 SWX6772 SWX6774 SWX6777 SWX6822 SWX6826 Batch

13 Depletion Voltage distributions Depletion voltage 35 3 Pisa HPK Average Min 35 4 all SSD 25 Max RMS entries Depletion voltage (V) batch analysis average depletion voltage (V) laboratory manufacturer SWX6375 SWX6563 SWX6566 SWX6568 SWX67 SWX673 SWX679 SWX6734 SWX6736 SWX6742 SWX6745 SWX6747 SWX677 SWX6772 SWX6774 SWX6777 SWX6822 SWX6826 Batch

14 HPK data statistics: defects analysis Position of defects along SSD - all 193 detectors number of defects Strip defects types 1 strip number coupling short strip isolation poly-si resistor 2 implant short ac-al open 7 32 implant open strip open leaky strip bad strips/total strips=72/

15 SSD dimensional tests D A Geometrical C 2µm 3µm 35µm B pixel/mm calibration on reference cross measure distance of reference cross centre to X and Y edge (all corners, DXA, DYA, DXB ) cut alignment evaluated with: Shift= (DyA+DyD)/2 Rotation=DyA-DyD See (LAT-TD-454)

16 Dimensions distributions Shift and rotation 4 35 shift rotation all SSD events average stdev min max Shift Rotation shift rotation micron 6 average (micron) 4 2 batch analysis -2 SWX6375 SWX6562 SWX6564 SWX6566 SWX6568 SWX657 SWX6572 SWX6699 SWX672 SWX678 SWX6733 SWX6735 SWX6737 SWX6743 SWX6746 SWX6769 SWX6771 SWX6773 SWX6776 SWX6778 SWX6825 SWX6827 SWX6829 SWX6837 SWX6923 SWX6927 SWX6929 SWX6936 SWX6948 SWX6968 SWX Batch

17 SSD failure analysis 24/1224 < 2% rejected I leakage (12V)>5nA 1 13 high current change in slope chipped corners damaged during lab test high depletion voltage probably due to transportation and handling e.g. scratches, wrong applied bias Vdep>12V

18 Ladder assembly Ladder = 4 SSDs glued together head to head without any mechanical support. All the pads are microbonded in series to form a unique detector 89.5mmX358mm Alignment Glueing Ladder assembly and testing activities in two qualified factories: G&A Engineering _ Oricola (AQ) MIPOT _ Cormons (GO)

19 Alignment of ladders prototypes mechanical ladders wafers alignment errors mm σ=5.5µm min=-32µm max=47µm 14 Ladders from mechanical wafers Produced by G&A Engineering for the Engineering Model Tower Ladder #A mm mm Requirement: max SSD displacement 4µm

20 MicroBondings and encapsulation bonding pull strength between 6-9 gr. (measured at G&A and Mipot) bonding encapsulation (at G&A and Mipot): pure epoxy (3M Scotchweld 2216 A/B) dam (3M Scotchweld 2216 A/B ) + fill (General Electric 615 ) both good but dam&fill chosen as more reliable

21 Ladders leakage current Mipot ladder #1 leakage current 6 5 G&A (Scotchweld encapsulation) 5 G&A ladder vs SSDs-sum leakage current comparison na sum of SSD currents ladder current Volt current (na) LG1_ssd LG2_ssd LG1_enc LG2_enc LG1_bare LG2_bare Mipot (Dam&Fill encapsulation) voltage (V)

22 Tray assembling Carbon-carbon closeout 4x4 array of W foils Trays are C-composite panels (Al hexcel core) Carbon-Carbon walls provide stiffness and the thermal pathway from electronics to the grid.

23 Tray Assembly Plyform, an Italian leading factory in composite assemby, has been qualified for tray production SuperGLAST tray without payload M2.5 thread holes M2.5 thread holes F3 reference holes The Engineering Model trays will be done with fully Carbon-Carbon closeouts, without the Al details

24 Tray planarity tray GALST Plyform top side Z(mm) "X=+75mm" X=-75mm X=mm "X=+75mm" Planarity of the GLAST tray # produced by Plyform Vacuum bag differential pressure =.2Atm X=-75mm X(mm) Y(mm) tray GALST Plyform bottom side Z(mm) "X=+75mm" X=-75mm X(mm) Y(mm)

25 mm Tray #1 thermal boss profiles mm Close-out tolerances Every other tray is rotated by 9 it is very important to build square trays Tray #2 thermal boss profiles mm mm MCM side Trey #3 thermal boss profiles mm mm Tray #4 thermal boss profiles mm mm CMM measurements of the sides of the tray mean dimensions= mmx mm

26 Ladder assembly over the tray bridge handle guide Z micrometers shoulder bridge pins tray pins

27 Tool to assemble the ladders on the tray Transfer bridge Tool to glue the ladders over the tray Prototype tray with dummy ladders

28 Vibrational test Tray 1 on the shaker FEM prediction=61hz g Sine Meas. channel VT11161IBTR INFN R RUN 11 RES SEARCH AFTER RANDOM T.P.6 - MEASURE - CENTER - Z AXIS Chan. No. : 6 Chan. type : M Sweep type : log Sweeps done: 1 Sweeps tot.: 1 Sweep dir. : up g^2/hz Random Meas. channel VT11161IBTR RANDOM RUN 1 RANDOM WITH NOTCH T.P. 6 - MEASURE - CENTER - Z AXIS.8 g 2 /Hz 626Hz Chan. No. : 6 Chan. type : M DOF : 132 Sweep rate :2. Oct/min Level :. db Ctrl strat.: Average.1 Resolution : 4. Hz Meas. mode : RMS 1..1 Eng. unit : g Contr. mode: Closed loop -- Testing time -- Elapsed : :3:25 Remaining : :: n 1 = 626 Hz Q» E-3.1E-4.13 g 2 /Hz Eng. unit : g RMS (act.) : g Contr. mode: Closed loop -- Time on act. level -- Elapsed : ::58 Remaining : ::2 --- Time total --- Elapsed : :2:33 Date : :34:21.1E-5 Remaining : ::2 Date : Marker x = y(max) = Hz.1E Marker x = 6 y(max) = Hz 16:18:53 Normal modes search results. Random vibration spectrum response (acceptance level)

29 Thermal qualification cycles Epoxy mock-up Qualification-like test: temperature range: -3 C +5 C T = 24 C number of cycles: C, +5 C (dt/dt) =.5 C/min T=25 C: L/L 1 µε T=-55 C: L/L - 35 µε DL/L (me) Temperature ( C)

30 Thermal test: results Epoxy mock-up T=25 C: σ 11 MPa T=-55 C: σ (-)26 MPa 28 MPa limit Maximum stress expected ( T=25 C): σ 12 MPa Stress (MPa) DT ( C)

31 Tower assembly- pre-engineering Model test Tower Assembly Jig Pre-Engineering Model Tower

32 GLAST Conclusions Activity of GLAST-Italy started full steam on both hardware and software The Italian Collaboration is providing critical contributions to: LAT design and preparation for construction development of detector and science software LAT prototyping (SSDs, ladders, tray construction, electronics, tower assembly) successfully concluded. 22 SSDs already received 12 SSDs tested Next actions (july 22): Assemby and test of 3 flight ladders Construction of the Engineering Model

33 Software activity I - Tracking Detector software - main areas of collaborations: II - Detector description III - Event display and graphics IV - GLAST simulation V - Test data analysis VI - Construction and test software

34 XML C++ generic model Detector geometry in XML (GDD,detModel) unique description for recon, simulation, graphics now read by: visualization tools G4 simulation prototype ROOT event display Recon to be implemented

35 Software: on-going activities Simulation LAT implemented in G4 interfaced to detmodel (XML geometry description) interfaced to a prototype ROOT event display Next steps: G4 validation (general, BT, BF) interface with GAUDI insert digitization modules GLAST

36 Software: on-going activities Interactive event display for simulation, reconstruction, analysis collecting user requirements from whole collaboration candidates: ROOT (C++) and Wired2 (Java) ROOT event display for Balloon flight under development

37 Software: on-going activities Software for construction and test I - development of a reduced version of reconstruction package for lab-tests of stack of trays or a tower with cosmic rays II Construction Database Relational DB engine : MS-Access easy programming widely used in industry (no extra cost) interface-able to most DBs control software no data flow directly on the web Direct connection to laboratory instruments (LabView - Delphi using DDE protocol) Procedure control (e.g. review of test non-conformancies) Data selection (e.g. ladder selection) Data analysis (VisualBasic + Excel) Data security (MS-Access internal + WinNT network security) read-only web interface (ASP queries + ODBC connection) documentation at

38 Construction DataBase architecture central repository backup Data1 Data2 Data3 data server Data1 Data2 Data3 Data1 (SSD man) Data2 (SSD lab) Data3 (Ladders) input Clean rooms DAQ Interface Instrumentation (DDE) Server interface output Web client (ODBC) production and quality monitoring I/O Users desktops Analysis Interface Selection Interface Control Interface

39 Software: on-going activities Test data analysis analysis of simulated data from BFEM and BTEM configurations for G4 validation studies preparation for BFEM data analysis Tracking study of charge sharing and signal generation to improve simulation study of TOT to improve vertexing angular accuracy study energy measurement from angular dispersion