LAT Instrument Analysis and Operations report Riunione Commissione

LAT Instrument Analysis and Operations report Riunione Commissione Scientifica Nazionale II Frascati, 3 Ottobre 2009 Ronaldo Bellazzini (INFN–Pisa) ronaldo. bellazzini@pi. infn. it

Fermi Gamma-ray Space Telescope Do. E – NASA – international partnership GLAST renamed Fermi by NASA on August 26, 2008 http: //fermi. gsfc. nasa. gov/ “ Enrico Fermi (1901 -1954) … was the first to suggest a viable mechanism for astrophysical particle acceleration. This work is the foundation for our understanding of many types of sources to be studied by the Fermi Gamma-ray Space Telescope, formerly known as GLAST. ” “ Questo nuovo nome e' stato selezionato con un sondaggio pubblico realizzato dalla NASA e che ha ricevuto piu' di 12 mila risposte. Oltre ad avere un legame diretto con la scienza dei raggi-gamma della nostra nuova missione, Fermi ha un significato speciale per il Do. E, l'ASI e l'INFN, tre agenzie che hanno maggiormente contribuito alla missione" Jon Morse Director of Astrophysics Division, NASA HQ, Washington DC

The Large Area Telescope (LAT) LAT images the sky one photon at a time: g-ray converts in LAT to an electron and a positron ; direction and energy of these particles tell us the direction and energy of the photon GBM

June 11, 2008 12: 05 pm (EDT)

GLAST Large Area Telescope GLAST First Light Seminar, 26 Aug 2008 6

Fermi in orbit Circular orbit, 565 km altitude (96 min period), 25. 6 degrees inclination http: //observatory. tamu. edu: 8080/Trakker (track the satellite) http: //www. nasa. gov/mission_pages/GLAST/news/glast_online. html (look at Fermi in the sky from your place)

Major achievements since last year • Launch on june 11! – 6 months delay in overall schedule for non-collaboration issues – Had to move env test to NRL for conflict with another GD mission – 1 month delay at launch site for rocket issues • • • An year full of successful training on simulations (Ops. Sim 1, 2, 3 and full sky simulations) – Full development of data monitoring tools and data processing infrastructure – Two generations of event analysis package (background rejection, event classes, IRFs) released and studied against simulations, third one in the works – Most science analysis routines in place before launch L&EO successfully completed – Very smooth operation in all respect ( from S/C to event identification) – Functional and performance verification completed on schedule with performance as expected – Nominal science configuration identified – Engineering data are effectively the first Fermi science data Routine science operations well under way – 2 full months of good data available and being analyzed – First set of papers ready for submission INFN-CSNII – October 3, 2008 Ronaldo Bellazzini

Year 1 Science Operations Timeline Overview spacecraft turn-on checkout week LAT, GBM turn-on check out “first light” Observatory whole sky week Start Year 1 Science Ops renaming Start Year 2 Science Ops sky survey + ~weekly GRB pointed + sky survey tuning repoints + extraordinary TOOs month 12 m o n t h s LAUNCH L+60 days initial tuning/calibrations 2 nd GLAST Symposium in-depth instrument studies Release Flaring and Monitored Source Info GBM and LAT GRB Alerts continuous release of new photon data GI Cycle 1 Funds Release Fellows Year 1 Start GI Cycle 2 Proposals LAT 6 -month high-confidence source release, GSSC science tools advance release LAT Year 1 photon data release PLUS LAT Year 1 Catalog and Diffuse Model 10

Commissioning highlights • Supported L&EO at SLAC with Duty scientists, Burst and Flare advocates, dedicated analysis – Instrument nominal configuration identified (trigger, subsystem calibrations, timing) – Basic performance verified – Prescriptions for high level analysis outlined (data and event selection) – Confirmation of expected results (EGRET) and discovery science achieved • Transition to routine operations outlined – Progressively more remote shifts (all kinds) – Automated tasks tested (ASP) and new tools under finalization (RSP) – Improvement area in instrument analysis identified (Pass 7) 11

Mapping of the SAA ü The South Atlantic Anomaly (SAA) is a region with a high density of trapped particles (mostly low energy protons). ü We do not take physics data when in the SAA (ACD HV turned off), but we do count the TKR and CAL trigger to map the radiation intensity. ü Started with a conservative boundary definition, new polygon already uploaded on the spacecraft (time spent in the SAA reduced from ~18% to ~15%). INFN-CSNII – October 3, 2008 Ronaldo Bellazzini

On orbit rates in nominal configuration ü Overall trigger rate: ~few KHz ü Huge variations due to orbital effects. ü Downlink rate: ~400— 500 Hz ü ~90% from GAMMA filter ü ~20— 30 Hz from DGN filter ü ~5 Hz from HIP filter ü Rate of photons after the standard background rejection cuts for source study: ~1 Hz ü Most of the downlinked events are in fact background, final ~ 1000: 1 rejection is done in ground processing. INFN-CSNII – October 3, 2008 Ronaldo Bellazzini

Tracker performance and calibration ü No evidence of a reduction in hit efficiency (well above 99% on average) with respect to the ground calibrations. ü No significant change in the alignment constants (intra and inter-tower) after the launch (the LAT underwent up to 4 g acceleration). ü No evidence of any increase in the overall noise level (~1 noise hit per event for the full LAT). INFN-CSNII – October 3, 2008 Ronaldo Bellazzini

LAT all-sky “First Light” map

INFN-CSNII – October 3, 2008 Ronaldo Bellazzini

Psf Validation with Vela INFN-CSNII – October 3, 2008 • Use Vela to validate PSF parameterisation – Take advantage of photon phase to eliminate background • Taking into account orbital variations – Compare direction error distribution – Compare 68% containment radius vs Energy Ronaldo Bellazzini

Instrument Response Functions • Release calendar – Pass 4_v 2 (correct energy selection) on public performance page 7/2007 – Pass 5 IRFs – sep 08 – Pass 6 IRFs – may 08 – current analysis and LAT paper – Preparing to Pass 7 INFN-CSNII – October 3, 2008 Ronaldo Bellazzini

Vela (2 cycles, P=89. 3 ms) Geminga (2 cycles, P=237. 1 ms) In a few days, Fermi confirmed the EGRET pulsars and found new g-ray pulsars as well PSR B 1706 -44 (2 cycles, P=102. 4 ms) PSR B 1055 -52 (2 cycles, P=197 ms) Crab (2 cycles, P=33. 4 ms)

PKS 1502 -106 and 3 C 454. 3 • The sky is dynamic, GLAST is monitoring the sky, catching flaring sources over different time scales. • Atel #1628 (3 C 454. 3) and #1650 (PKS 1502 -106) issued to announce these flares. INFN-CSNII – October 3, 2008 Ronaldo Bellazzini

First GRBs detected by Fermi/LAT • 2 Ge. V GRB detected above 5 sigma, triggered by GBM – 080825 C (GCN 8183) – weak burst – 080916 C (GCN 8246) – many hundreds photons, exciting analysis in progress 080825 C – LAT DATA INFN-CSNII – October 3, 2008 080916 C – GBM DATA Ronaldo Bellazzini

Analysis systematics • Long-term strive • Many sources – Instrumental effects (T, calibrations) – MC fidelity (geometry, physics processes) – IRF – Residual bkg modelling – Likelihood analysis • Early papers conservative assessment – 30% on integral flux – 5% trigger – 10% filter efficiency – 15% event selection cuts – Residual background contamination critical for extended or faint sources, high energy regions – under verification INFN-CSNII – October 3, 2008 Ronaldo Bellazzini

Future developments • Revised event analysis with lessons learned from LEO – Ghost track filter to minimize orbital effects – Reject hits from track segments that did not fire single towers trigger – Add ghosts to MC and produce training sample to test/update rejection – New subsystems filters – New energy resolution and PSF sections – Revised background model • Acceptance increase above 10 Ge. V – CAL-only events – Larger FOV at expense of angular resolution • Augmented particle identification – Electron tagging with classification techniques – Protons and nuclei tagging INFN-CSNII – October 3, 2008 Ronaldo Bellazzini

MC validation from CERN Beam Test Major Updates • T effects on CAL corrected • Discovered G 4 bug in LPM implementation thanks to shower fine sampling, now available in Geant 4 9. 2 -beta -01 Major improvements • CAL energy scale in good agreement with a single recalibration factor • basic TKR and CAL variables in agreements • shower transverse size in CAL still not properly reproduced in MC From the LAT paper – 45° incoming angle, 5. 3% global scaling factor applied to MC INFN-CSNII – October 3, 2008 Ronaldo Bellazzini

GLAST LAT Science • Science Working Groups – Calibration and Analysis Methods (L. Latronico, P, Bruel) – Beam Test (Latronico, Bruel) – IRF development (Rando), IRF monitoring (Cecchi) – – – – • • Blazars and other AGNs (G. Tosti, B. Lott) Diffuse and Molecular Clouds (T. Porter, A. Strong) Catalogs (D. Thompson, I. Grenier) Pulsars, SNR and Plerions (D. Smith, A. Harding) GRB (N. Omodei, V. Connaughton) Sources in the Solar System (F. Longo, I. Moskalenko) Dark Matter and new physics (J. Conrad, R. Johnson) (just rotated A. Morselli, E. Bloom) Satellite groups – Multiwavelength – Ge. V-Te. V connection Analysis coordination – Julie Mc. Energy, Nicola Omodei (deputy) INFN-CSNII – October 3, 2008 Ronaldo Bellazzini

Papers in the pipeline • • • In preparation (Category 1): – 3 C 454. 3 (Tosti*…) – 1 st new pulsars (from known ephemerides) (…Caliandro, Gargano, Razzano…) – Pulsar catalog (Caliandro*…) – Vela 1 Pulsar (Razzano*…) – Other papers are coming shortly… Ready for submission (Category 2): – Prospects for GRB science with the GLAST Large Area Telescope (Omodei, Longo, Baldini…) – Pulsar Simulations for LAT (Razzano, …) – “LAT instrumental paper” Submitted: – Discovery of a new gamma-ray pulsar… (blind search) INFN-CSNII – October 3, 2008 Ronaldo Bellazzini

Conclusions • • Fermi-LAT is fully operational since june 25 and in routine survey mode since august 11 (end of commissioning) The commissioning phase was extremely smooth and satisfactory thanks to the thourough preparatory work of the full collaboration A new observational window in the Universe has opened – EGRET/AGILE results corroborated in just a few days – Exciting new discoveries coming up soon INFN is a key-player in this story of success since the beginning of the project – TKR construction and qualification – Instrument calibration – Science analysis INFN-CSNII – October 3, 2008 Ronaldo Bellazzini