1. GLAST LAT Project I&T Meeting – Jan 20,2004 E. do Couto e Silva 1 GLAST Large Area Telescope: EM1 Data Analysis and Calibration Summary Report Eduardo do Couto e Silva SU-SLAC SVAC I&T Manager eduardo@slac.stanford.edu 650-926-2698 Gamma-ray Large Area Space Telescope

2. GLAST LAT Project I&T Meeting – Jan 20,2004 E. do Couto e Silva 2 SVAC EM Requirements The Engineering Model (EM1) was used to develop the necessary infrastructure for future hardware tests. Requirements and goals were described in the (“SVAC EM Plan” LAT-TD-00573) –SVAC EM requirements  Develop infrastructure for TKR and CAL calibrations  Measure the energy spectrum of van de Graaff photons –SVAC EM goals  Exercise flexibility of geometry input for the Monte Carlo simulations.  Validate a preliminary set of Monte Carlo distributions  Prototype energy resolution algorithm   Prototype alignment algorithm

3. GLAST LAT Project I&T Meeting – Jan 20,2004 E. do Couto e Silva 3 Data Analysis Chain ROOT tree Files (digi) SAS/ONLINE Converter ROOT tree Files (recon) SAS Recon “GENERAL” USER Online Analysis tools online scripts Calibration Constants Calibration scripts ROOT ntuple files IDL Structures SAS Converter SAS User Interface EBF EM In the future the FSW Filter will go in here

4. GLAST LAT Project I&T Meeting – Jan 20,2004 E. do Couto e Silva 4 EM Calibrations TKR  Determine Operational Thresholds  Measure Electronic Gain  Identify noisy and dead strips  Characterize TOT –Slope and intercept with charge injection –Mean and width of distributions CAL  Determine Operational Thresholds (HI, LO and zero suppression)  Measure pedestal and gains –Identify noisy and dead logs  Determine muon peak position and width  Measure light Asymmetry, Attenuation, Yield  Measure position resolution without TKR tracks  Measure position resolution with TKR tracks Present status: 3 months after the end of the data taking period

5. GLAST LAT Project I&T Meeting – Jan 20,2004 E. do Couto e Silva 5 Calibrations – To do List SVAC IDDescriptionComments C10TKR Noisy ChannelsEGSE SASreconNeed to define noise level C11TKR Dead ChannelsEGSE SASrecon C12TKR ToT SignalEGSECI PID?Seen variations on channel by channel. Maybe used for particle ID C13TKR ToT Distribution SASPID?Maybe used as a cross check of C12 C14CAL Light Asymmetry SASreconWould like to change this to Energy Scale (MeV/ADC count) C15CAL Light Attenuation SASreconMeasure muon peaks (includes effects from optical and electronic gains). Function of position in a log. Investigating light taper model C16CAL Light YieldEGSECI I&T has no experience, done by CAL only. Need to capture information for offline C18CAL PedestalsEGSECISASreconNeed to define width characterization (rms vs sigma) C19CAL Electronic GainEGSECI Need to get information from online C20CAL Integral non-linearityEGSECI Need to get information from online C22CAL Noisy ChannelsEGSE SAS From pedestal widths. None observed in EM. Need to develop infrastructure C23CAL Dead ChannelsEGSECISAS From pedestal widths. None observed in EM. Need to develop infrastructure C24CAL LO DiscriminatorEGSECI I&T has no experience, done by CAL only. Need to capture information for offline C25CAL HI DiscriminatorEGSECI I&T has no experience, done by CAL only. Need to capture information for offline C26CAL Zero-Suppress Threshold EGSECI I&T has no experience, done by CAL only. Need to capture information for offline C27DeadtimeEGSE Measure overall deadtime as part of the functional test plan C29TKR GTFE Threshold ScanEGSECI Need to capture information for offline including GTFE split Calibration List derived from Level III document – SVAC EM Plan – LAT-MD-00446

6. GLAST LAT Project I&T Meeting – Jan 20,2004 E. do Couto e Silva 6 Calibration Infrastructure Tasks Lessons learned  Develop code to create constants from the digi files Redefined output format as we learned more about the instrument  Develop code to read constants into recon Modified reconstruction to allow calibrations without zero suppression in the CAL Modifying reconstruction to read in ToT constants on channel per channel basis Developing a scheme to capture the instrument configurations necessary for MC validation and for reference during calibrations  Configuration control Created cvs repository to keep the calibration code Developing process to version control creation of constants and to transfer information from online whenever needed

7. GLAST LAT Project I&T Meeting – Jan 20,2004 E. do Couto e Silva 7 Energy Measurement ROOT tree Files (digi) Raw spectrum of individual crystals Calibration Constants Perform Calibrations C14,C15,C16,C18 on each crystal Operational Settings Perform C18,C19,C20,C22,C23,C24 to establish baseline for data taking ROOT tree Files (recon) Produce Energy Calibrated Spectrum using all crystals ROOT ntuple files IDL Structures Use Data Analysis Cuts and VDG Flux Calibration to obtain final spectrum Data Analysis Calibrations

8. GLAST LAT Project I&T Meeting – Jan 20,2004 E. do Couto e Silva 8 CAL Energy Spectrum CAL Energy Spectrum 1 10 100 1000 400 300 200 100 0 1 10 100 1000 2500 2000 1500 1000 500 0 Photon Source OFF Photon Source ON Energy (MeV) Mostly photons From Gary Godfrey

9. GLAST LAT Project I&T Meeting – Jan 20,2004 E. do Couto e Silva 9 Source Calibration From Gary Godfrey Expect two energy lines

10. GLAST LAT Project I&T Meeting – Jan 20,2004 E. do Couto e Silva 10 Flux Measurement Top TKR face Extrapolation to Photon Source EM Rec Direction cosine In 0.02 bins 10% error is dominated by the knowledge on the BGO position 9% of the of photons produced by the source are measured by the EM From Gary Godfrey

11. GLAST LAT Project I&T Meeting – Jan 20,2004 E. do Couto e Silva 11 Experimental setup CALTKR Gammas:66% 17.6 MeV 34% 14.6 MeV, FWHM = 1.5 MeV + lots of electrons Cosmic Background Electrons are produced by gamma conversions in the iron shield in front of the accelerator Beam pipe Not a monochromatic beam!

12. GLAST LAT Project I&T Meeting – Jan 20,2004 E. do Couto e Silva 12 EM Energy Spectrum (VDG DATA) Event selection: nTkrTracks>=1 && zDir 4MeV Expected  Spectrum Delta function (17.6 MeV) Breit-Wigner (mean 14.5, width=1.5MeV ) Energy (MeV) From Xin Chen

13. GLAST LAT Project I&T Meeting – Jan 20,2004 E. do Couto e Silva 13 Energy Spectrum (VDG MC) Events converted in top layer of Tracker only From Xin Chen Event selection: nTkrTracks>=1 && zDir 4MeV Expected  Spectrum Delta function (17.6 MeV) Breit-Wigner (mean 14.5, width=1.5MeV ) Energy (MeV)

14. GLAST LAT Project I&T Meeting – Jan 20,2004 E. do Couto e Silva 14 Documentation for EM2 We are now updating the following documents  SVAC EM Plan – LAT-MD-00573 Defines the SVAC requirements  Calibration algorithms for the EM – LAT-TD-01588 Describes Algorithms Describes Output Formats for the calibration data  LAT SAS EM Calibration Infrastructure – LAT-TD-01340 Describes the SAS database and how calibrations are used by the offline code  SVAC Database for the EM – LAT-TD-00578 Describes how calibration data is stored in ORACLE for trending

15. GLAST LAT Project I&T Meeting – Jan 20,2004 E. do Couto e Silva 15 Summary Current status 3 months after the end of the data taking period Calibrations –We have met all calibration requirements –Lessons learned on the infrastructure are now being implemented for EM2 Data Analysis –We have met the requirements for the measurement of the energy spectrum –In addition we met most of the goals for the EM1 including the development of an algorithm for energy resolution, which is now being documented and will be presented in detail in the near future by Xin Chen for a group review Documentation –We have started updating all documentation relevant to EM2