Caratterizzazione spaziale del Tracker di GLAST Silvia Rainò INFN - BARI Incontro Nazionale di Astrofisica delle Alte Energie – Roma, maggio 2003

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie2 Overview GLAST experiment The Large Area Telescope: GLAST-Tracker Space tests: results on Engineering Model Conclusions

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie3 Gamma Ray Large Area Space Telescope GLAST is an important part of the continuing quest to broaden our view of the universe. explore Natures highest energy processes (10 keV – 300 GeV) observe, with unprecedented detail, cosmic phenomena of extreme violence - LAT: - LAT: ~20 MeV - >300 GeV - GBM: - GBM: correlative transient observations ~20 keV – 20 MeV

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie4 Glast observatory Launch VehicleDelta II – H Launch LocationKennedy Space Center Orbit Altitude575 Km Orbit Inclination28.5 degrees Orbit Period95 Minutes Launch DateSeptember 2006 Large Area Telescope (LAT) Gamma Ray Burst Monitor (GBM) Spacecraft

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie5 Large Area Telescope 4 x 4 modular array 3000 kg, 650 W 20 MeV – 300 GeV Si Tracker pitch = 228 m channels 18 x-y planes ACD Segmented scintillator tiles Grid mechanical backbone CsI Calorimeter hodoscopic array (8 layers) channels e+e+ e-e-

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie6 Large Area Telescope e+e+ e-e- Single Photon Angular Resolution MeV GeV Wide Energy Range: 20 MeV - >300 GeV Wide Field of View (> 2 sr) Low dead time: < 100 s/event Large Effective Area (A eff ) peak > 8,000 cm 2 Good Energy Resolution E/E ~ 10%; 100 MeV – 10 GeV ~ < 20%; 10 GeV – 300 GeV Point Source Sensitivity: < 6 x ph cm -2 s -1 (est. performance: < 3 x ph cm -2 s -1 ) Source Localization: 0.3 – 1

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie7 Tracker Tower 11 thin-converter trays (3% X 0 ) 4 thick-converter trays (18% X 0 ) 2 no-converter trays 1 bottom tray (no-converter) 1 top tray (converter 3% X 0 )

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie8 Space tests operate satisfactorily at the temperatures expected during the mission Thermal tests Dynamic tests withstand the mechanical solicitation during launch and first orbit phases Tray Tower TKR CAL ACD LAT

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie9 Work in progress Space test activity now concentrated on the assembly and test of the Engineering Model Tower: Test plans have already been defined Dynamic test: 12 EM panels successfully tested Thermal test: 2 EM trays cycled w/out any damage to silicon EM Tower Plan Schedule July 8:EM tower assembled July 22:Vibration testing completed August 5:Thermal-vacuum testing completed

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie10 Dynamic test Frequency range Hz Sweep rate2 oct/min Target Amplitude0.25 g 0-pk Test Sequence: 1. Modal survey: normal mode search 2. Random vibration 3.(Low frequency test + quasi static acceleration) 4. Modal survey: normal mode check Modal survey: Low amplitude sine sweep test, performed at the beginning & end of the test sequence Evaluates the transfer function of the item Allows to find any structural damage occurred during the test

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie11 Dynamic test Random Vibration: Allows to study the structural response of the item when subjected to the launch environment depends on the rocket used for launch Frequency (Hz) ASD Qualification Level (g 2 /Hz) ASD Acceptance Level (g 2 /Hz) dB/oct dB/oct Overall14.0 g rms 10.0 g rms

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie12 Vib test: experimental set-up accelerometers Shake table LDS Centrotecnica s.a.s (MI)

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie13 Modal survey EM tray - thin converter type (W=3%X 0 ) m 830 g 1 st resonant mode Hz 2 nd resonant mode Hz ESPI Vibration TEST

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie14 Random vibration EM Trays tested at successively higher excitation levels: 7 g rms 10 g rms 14 g rms White noise check among two successive random

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie15 Thermal tests 1 m 3 Climatic chamber in INFN - PG site Terni, Dip. Ingegneria dei Materiali Strain gauges positioned on the Si surface of the tray Wheatstone bridge configuration Strain gauge on Si Reference strain gauge on quartz (CTE 0 ppm/°C) LabView based DAQ system

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie16 Thermal test on EM 4 cycles -30°C ÷ +50 °C dT/dt = 20 °C/hr Plateau 5 hr

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie17 Thermal test results strain Strain vs time = trasf · E Si, E Si = 13 GPa max = 28 MPa (SF= 7.5) Stress vs T T=30°C: MPa

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie18 Conclusions Summary Test plans have been developed for all dynamic and thermal tests on trays and towers and are in the release cycle now Positive results for the tests on EM trays Further work June-July 2003: assembly and test of EM tower: Dynamic and thermal-vacuum in Alenia Globalstar, Rome Revise flight test plans with updated information resulting from EM tests Assembly & test of Flight items (October 2003 ): Test on 342 trays342 trays Cosmic rays test Assembly & test of 18 towers (16 flight+ 1 qual + 1 spare)test

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie19

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie20 Tracker Tray SSDs Bias- Circuit Structural Tray Panel Converter Foils TMCM Bias- Circuit SSDs

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie21 Tray Test flow overview Tray factory (panels)Vibration testLadder factory Tray assembly: ladders and MCMs on trays Tray thermal cyclesStacked cosmic raysElectrical testTray functional testTower assembly Electrical test before MCMs encapsulation

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie22 Cosmic rays test Tray stacked in single/double view

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie23 Tower Test Flow Overview Tower functional testVib test sequenceTower functional test Thermal-vacuum & functional test Tower assembly Sine sweep Random vib Quasi static Sine burst Sine sweep

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie24 Tower vib levels Frequency (Hz) ASD Acceptance Level (g 2 /Hz) ASD Qualification Level (g 2 /Hz) dB/oct dB/oct Overall8.7 grms12.3 grms Duration1 min/axis2 min/axis Frequency range Hz Sweep rate 2 oct/min Target Amplitude 0.25 g 0-pk Modal survey Random vibration Sinusoidal vibration TKRAcceptance (g)Qualification (g) Lateral (X) Lateral (Y) Axial (Z)+6.8/ /-2.25 Sine burst 2 half level 1 full level 2 half level 5 sinusoidal 25 Hz:

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie25 Tower thermal-vacuum cycles QualificationAcceptance Ranges-30°C 50°C-20°C 45°C # of cycles124 Temp. rate20°C/hr Pressure10 -5 Torr plateau12 hr4 hr Total Duration384 hr + stabilization58 hr + stabilization

Roma, Maggio 2003Incontro Nazionale di Astrofisica delle Alte Energie26 Bottom tray