S. Aoki Kobe University OPERA Emulsion Workshop 2006/12/09 Gamma-ray Telescope

Photon Observation (pointing) Radio IR Visiblerefrectable  optical imaging UV X-ray “MeV-γ”Compton scattering  multi-Compton scattering “GeV-γ”pair creation  initial e-track measurement “TeV-γ”air shower  Čerenkov light imaging The best tracking detector becomes the best “GeV-γ” telescope.

2 mrad Current Situation in various wavelength range ex. Crab nebula (M1) Radio (VLA) Infra Red (2MASS) Visible (Palomar) Ultra Violet (UIT) X-ray (Chandra) “TeV” Gamma (HESS) “GeV” Gamma (EGRET) 30 mrad 100 mrad a lot of room to improve for “GeV-γ”

Converter Emulsion metal foil spacer Energy Measure ( Em + Pb ) Fiber Tracker ( X and Y ) γ Emulsion hybrid Gamma-ray Telescope  Unit size is about 1 m 2 according to EGRET, Crab = 43 ev / 6hour ・ m 2 (E > 1GeV)  Loaded on the Scientific Balloon ($0.1M/flight << satelite)  Fiber Tracker for the “time stamp”  Orientation monitor (gyro + “star camera”) should also be equipped, to know the direction w.r.t celestial sphere.

Balloon Sanriku 2004/May/30 Micro Segment Chamber

1.5mm 10.5cm 6.5cm hadron ｊ et electroron shower ｇ amma shower Balloon Sanriku 2004/May/30

290µm (.002X 0 ) 2mrad by single layer (290µm)  [rad] “OPERA Film” tracker performance In current method, angular resolution is dominated by “stage (z-axis) noise”.

SPring-8 Laser Electron Photon Beam (by RCNP Osaka Univ.) ～ 70m

Angular Resolution RMS  x = 2.6 mrad RMS  y = 1.8 mrad

290µm (.002X 0 ) “OPERA Film” tracker performance 2mrad by single layer (290µm) 50mm c.f. GLAST 410µm (.004X 0 ) １ mrad

readout error 0.3  m 0.2  m 0.1  m GLAST 1 mrad simulation

Thicker Base

Intrinsic Tracking Resolution Ag grain after development dx  = 0.06  m Compton Electron Fog M.I.P. Track 100  m M.I.P. Track intrinsic tracking accuracy Original Crystal Size0.2  m  single grain resolution0.2  m/  12 = 0.06  m N grains resolution0.06 /  N  m Angular Resolution (200  m base) 0.06/  N *  2 / 200 = 0.4/  N mrad if N=9 0.4/  N mrad = 0.13 mrad

Summary  We are developing Emulsion Hybrid Gamma-ray Telescope  Test with Laser Electron Photon Beam (Max. 2.4GeV)  Finding conversion point is OK  By current methods, RMS = 1.8~2.6 mrad (= 6~9 arc min) and Outlook  We shall improve angular resolution.  At first, 1 day flight at Sanriku Japan to detect Crab nebula. If Solar flare happens during flight, we can see the point. (Apparent diameter of the Sun = 0.5  = 9 mrad)  Next, Long Duration (1 week) Flight at south hemisphere to see the Galaxy center and other objects.

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Emulsion can measure …  brightness (magnitude)  color (wavelength)  direction of the light.  event rate (flux)  energy (momentum)  direction of the “GeV” photon. Emulsion can be good Telescope. Telescope observes …

plate Cu 50  m Pb 500  m  plate Cu 50  m Pb 500  m ConverterEnergy Measure Test Chamber PMMA 15mm t

Detection and Measurement of Gamma-ray Net-scan reconstruction  Manual Check  e-pair confirmation  Angle measurement 10 mrad distribution in angular space 39 events form 5mm×5mm area

Energy Measurement E < “ 700 MeV ” (beam halo) E > “ 700 MeV ”

 x  0.1 GeV 1 GeV 10 GeV Angular Resolution (simulation) 68% 95% 68% readout error 0.3  m

 x  0.1 GeV 1 GeV 10 GeV Angular Resolution (simulation) 68% 95% 68% readout error 0.1  m

Signal to Background estimation  According to EGRET (ApJ.494, p734, 1998), Crub Flux = 2.0  10  7 photons cm  2 sec  1 > 1.0GeV)  During 24 hours flight, Crab is above the detector 6 hours with  45º aperture  # of arriving photon is 43 photons with 1m  2 area.  # of Signal event will be 21 ev. with 50% X 0 depth.  According to BETS, atmospheric gamma-ray flux is 63 photons m  2 sec  1 sr  1 > 1.0GeV, 25g/cm 2 height)  1.3  10  3 photons cm  2 sec  1 sr  1 > 1.0GeV, 5g/cm 2 height)  In the size of Crab nebula (1  1mrad 2 = 4.0  10  6 sr) 1.2  10  9 photons cm  2 sec  1  During 24 hours flight,  # of arriving photon is 1.1 photons with 1m  2 area  # of Backgound event will be 0.6 ev. with 50% X 0 depth.

“TeV” Gamma Observation by HESS (Imaging Air Cerenkov Telescope) PSF 1°× １ ° Crab nebula (M1) Galactic Sources “morphology” has become possible “TeV” Gamma region

dE/dx measurement dE/dx (a.u.) p (  = 0.79, dE/dx = 1.23 MIP )  (  = 0.99, dE/dx = 1.08 MIP ) “OPERA film”  KEK-PS 1.2 GeV/c beam (29 films)

momentum (p  ) measurement by multiple Coulomb scattering MDM = 5.9 GeV/c with  =0.21  m p  (GeV/c) p  (GeV/c) 1.2 GeV/c  4 GeV/c 

Balloon Sanriku 2004/May/ m MSC (40cm  50cm  8X 0 ) “hinge” for shifter

flight path 503km the north latitude the east longitude

T= ｔ 0 T=t １ T=t 2 “shifter” to get time information MSC Air-Bag hinge

altitude [km] shifter displacement [0.1mm] level flight at 36km displacement by atmospheric pressure change air bag #1 air bag #3 air bag #2 (slow change) “boomerang” flight at 14km Flight Altitude vs. Displacement

expected track density vs. before launch FLUX=10 -2 cm2/sr/sec T=6.5day=5.6x10 5 sec W=0.5sr(<0.4rad) 2.8x10 3 /cm FLUX=2.1x10 -1 T=4hour =1.4x10 4 sec W= x10 3 /cm FLUX=4x10 -2 T=14hour=5.0x10 4 sec W= x10 3 /cm 2 projection

measured track density vs. displacement projection track displacement across the air-bag

measured vs. expected

@0km before launch