Experimental Particle

Transcription

1 Experimental Particle Eduardo do Couto e Silva SLUO Annual Meeting July 12, 2002 OUTLINE Introduction X rays g rays Summary 1

2 There are two Leader: E. Bloom Leader: T. Kamae 2

3 Why photons? Photons not affected by magnetic fields point directly back to sources probe cosmological volumes g Active Galactic Nuclei Gamma Ray Bursts satellite ~ 500 km What is the source of energy for Nature s largest accelerators? 3

4 Grand Unified Photon Spectrum infrared Optical & UV X-rays Radio g-rays CMBR Optical depth 4

5 X and g ray Experiments DATA are Public! 1 TeV 100 GeV 10 GeV 1 GeV 100 MeV 10 MeV Gamma rays SLAC EGRET GLAST X rays 1 MeV 100 kev 10 kev 1 kev SLAC ASCA ASTROE-2 Chandra RXTE USA XMM-Newton 5

6 Galactic Binary Systems Study Galactic Binary Systems (Black holes, neutron stars, pulsars ) X rays High r ~ g cm 3 High T ~ 10 7 K High B ~ G High g ~ g Earth Conditions not easily achievable in terrestrial laboratories! Probe gravity at dynamical time scales of > 100 ms ( > 200 ms for 1.4 solar mass NS and few ms for 10 solar mass BH) Some objects show variability in an unpredictable manner and is important to study emission at different wavelengths to understand mechanisms of acceleration. 6

7 Galactic Binary Systems A Black Hole or a Neutron Star accretes mass from a companion star. Accretion processes are at least 10 times more efficient than nuclear fusion. LMXB Companion star X rays Inner edge of the disk > 1000 km 10 ~ 100 km Accretion disk 7

8 Fourier transform of a time series of length T divided into N evenly spaced bins is N 1 2pijk / N a = j  - x e k k = 0 where x k is the number of counts in the k th time bin of the light curve. The corresponding Fourier frequency is f j = j / T Leahy normalized power spectrum is given by, 2 a j Pj = N ph where N ph is a total number of photons within time series of length T. 2 Quasi Periodic Oscillations X rays Power versus Frequency Kaice Reilly, PhD Thesis 2002 Quasi Periodic Oscillation XTE J (Hz) 8

9 Probing inner edge of accretion the disk Regular periods are found in binary systems due to (Hz) XTE J Kaice Reilly, PhD Thesis 2002 Rotation of compact object Orbital motion about the center of mass Precession of accretion disk but also quasi periodic oscillations (QPO) can occur and be used to probe the inner edge of the disk where strong gravitational effects are more pronounced Another model + X ray data Sobczak 2000 Acoustic Oscillations Model + X ray data Titarchuk (R S ) 9

10 AGN - Supermassive Black Holes? g rays X rays Up to times the luminosity of typical galaxy in a volume of one cubic parsec! (1 pc = 3.1 x cm ~ 3 light years) (assuming isotropic emission) Accretion processes can explain huge output power since they are very efficient Changes in Luminosity in a fraction of a day! Variability constrains the size of the emitting source 10

11 AGN - Mechanisms of Acceleration synchroton Inverse Compton Scattering 11

12 Gamma Ray Bursts Galactic coordinates We already know that they occur at cosmological distances, implying energies up to ergs during burst emission (if we assume isotropic model) Internal shocks External shocks 12

13 GRB and Host Galaxies First confirmed optical counterpart of a GRB after localization by Beppo -SAX Host galaxy Strong evidence that GRB has cosmological origins GLAST will have higher statistics ~ 200 GRB/year GRB GRB not centered at galaxy favors either neutron star collision or hypernova models over supermassive black hole at the center of the galaxy 13

14 Gamma Ray Astronomy in Space OSO-III (1967) 50 MeV GeV Proportional Counter SAS-2 (1972) 30 MeV GeV Spark Chamber COS-B (1975) 50 MeV 5 GeV Spark Chamber EGRET (1991) 20 MeV - 30 GeV Spark Chamber Hint of Galactic diffuse emission Galactic diffuse emission ~10 Galactic sources ~25 sources 1 extragalactic source (3C273) 271 sources including 169 unidentified sources 5 Gamma Ray Bursts 6 pulsars ~70 AGN 14

15 Gamma Ray Sky From space From the ground Why so few sources at TeV? 15

16 GLAST International Collaboration P. Michelson (Stanford) Principal Investigator R. Johnson (UCSC) Delta II 7920 H Si -Pb Tracker Large Area Telescope 2560 kg, 600 W, 1.73_ 1.06 m N. Johnson (NRL) CsI Calorimeter Anti-Coincidence Detector D. Thompson (GSFC) Gamma-ray Burst Monitor 16

17 HERMES TOSCA TB FINUDA BELLE H1 L3 OPAL CLEO3 BABAR ALEPH NOMAD-STAR DELPHI AMS PAMELA ZEUS GLAST-BTEM DO AMS2 ALICE CDF LHC-B ATLAS GLAST CMS Area in squared meters Experiments with Silicon Detectors 17

18 3 rd EGRET Catalog E > 100 MeV EGRET LAT LAT Simulation E > 100 MeV ? 5 yr operation requirement 10 yr operation goal Energy Effective area Field of view Sensitivity (1yr) Localization Deadtime 20 MeV - 30 GeV 1500 cm_ 0.5 sr ~ 10-7 g cm -2 s ms Improvement 20 MeV GeV > cm_ > 6 > 2.0 sr > 4 < g cm -2 s -1 > 20 < 0.5 > 30 < 100 ms > 100 Large area Low instrumental background 18

19 Diffuse Background Emission EGRET Data for E > 100 MeV cosmic p rays e- p 0 ISM g g g Gamma ray emissions is concentrated in the Galactic plane, these are thought to be high energy cosmic Rays that interact with the interestellar medium (ISM). Can signatures of relics from the Big bang be hidden in this background? 19

20 Balloon Flight Engineering Model Anticoincidence Detector (ACD) Shield Tracker Module (TKR) Calorimeter Module (CAL) Tsuneyoshi Kamae LAT Technical Coordinator (SLAC/Stanford University) Real-time event display of a muon track 20

21 August 4 th, Texas 38km altitude 3 hours level flight The flight 1.4 Trigger rate vs. atmospheric depth 1.2kHz maximum (~500Hz is predicted for each tower of LAT) 1.0 Run 55 Run g cm Hz in level flight We collected 200k events throughout the flight via telemetry. g cm -2 All detector components worked well in high-counting environment. 21

22 Cosmic Ray model for Protons Proton energy spectrum from zenith (T. Mizuno) AMS BESS (magnetic north pole) our model (used in Geant4 Simulation) High flux secondary (atmospheric) 0.6 < è 0.7 < è M M < 0.7 < 0.8 primary (extraterrestrial) with geomagnetic cutoff and solar modulation Palestine, GeV The flux in high geomagnetic latitude (~0.73 radian) of the Balloon Experiment corresponds to maximum flux expected in GLAST orbit. 22

23 Secondary Flux Zenith angle MC distribution of single straight track Modified secondary flux from 1+0.6sin(q) to 1+1.2sin(q) (T. Mizuno) Sum of all MC contributions BFEM Data (level flight) muon muon gamma e-/e+ alpha proton horizontal cos (theta) downward BFEM data can be used to predict flux at large angles for the LAT 23

24 GLAST Timeline 1997 Test Beam validation of measurement principles and technology choices. 1999/2000 Test Beam full engineering model including compact front end electronics 2001 Balloon Flight Next step in full flight software development and improvements based upon 1999/2000 test beam experience 2004 Calibration Beam tests Full calibration of instrument and response matrices 2006 September, Launch 24

25 We presented a brief overview on some of the interesting research topics in Particle Astrophysics Accretion Processes These can be studied with galactic and extragalactic objects. Not only constitute efficient sources of energy, but also allow us to probe regions which are governed by general relativity. Relativistic Outflows AGNs and GRBs are among the most powerful engines in the universe. Fundamental questions about their energy source and mechanisms of acceleration and jet formation make these an exciting research topics. Diffuse background The true nature of the diffuse (galactic or extragalactic) background is not known and we are interested in exploring these in both X and g ray energy bands. Are there signatures of relics from the Big Bang buried in this background? Summary 25

26 We are also developing expertise in many areas Flight software Space qualified electronic and mechanical engineering Quality Assurance and Quality Control Offline Science software for Particle Astrophysics Instrument Integration and Tests breakthroughs Number of Detected Objects 26

27 Since this is a SLUO talk Thanks to both the Particle Astrophysics and GLAST groups for providing projects and mentors to the ERULF DOE summer program. (If you are a SLAC user and do know anything about this exciting program for undergraduate students, please contact Helen Quinn) Special thanks to the following graduate students for their enthusiasm and support to the ERULF program: Derek Tournear Pablo Saz Parkinson Kaice Reilly (Oops! Dr. Reilly) David Robertson Martin Mueller 27