Performance of 10100GeV gamma ray camera for SUBARU opticalinfrared telescope

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Performance of 10-100GeV gamma raycamera for
SUBARU optical-infrared telescope

• A.Asahara, K.Komiyama, G.Kosugi, H.Kubo,
  S.Miyazaki, M.Moric, M.Nakagiri, D.Nishida,
  R.Ogasawara,
• R.Orito, K.Sakurazawa?, T.Takata, T.Tanimori
  and T.Usuda

Department of Physics, Kyoto University,
Japan Subaru Telescope, National Astronomical
Observatory cICRR, University Tokyo ?Tokyo
Institute of Technology
AGENDA

• Introduction
• Detectors at GeV region
• High altitude observation
• CheSS gamma ray camera
• Simulation of SUBARU with CheSS
• Observation report
• Summary

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1. Introduction -- Pulsars in 10GeV region --
Target Crab pulsar/nebula

• The standard candle for gamma-ray detectors.
• SUBARU has a good location to observe it.
• Wide band pulsed emission

Pass through near the zenith.
Extend above 10GeV ?

• Polar cap
• Outer gap

Cut off very sharply 20GeV
Cut off more slowly 50GeV
Credit A.K. Harding (NASA/GSFC)
Thompson astro-ph/0101039
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2. Detectors in 10GeV region
Crab Nebula (unpulsed component)
Satellite
Ground
Conventional Cherenkov detectors

• COMPTEL
• MeV region

Over 300GeV

• EGRET
• 10GeV

Two new type Cherenkov detectors

• STACEE

One point at 200GeV

• CELESTE

One point at 60GeV
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3. High Altitude Observation
10GeV gamma-seed (CORSIKA simulation)
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SUBARU optical-infrared telescope
FOV 0.75deg Focal length 15m Mirror
diameter 8.2m Mirror reflectivity 91(380nm) Tra
nsmittance of correction lenses 68(380nm)
PMT array
200mm
0.1deg
0.75deg
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How to set up
PMTs
SUBARU telescope
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4.CheSS (Cherenkov light detecting System on
Subaru)

• 44ch VME-TDC (?T 0.75nsec)
• Onboard VME-CPU
• 3ch VME-ADC
• GPS module

Acceptable trigger rate 300Hz (dead time 20)
1m
photo-cathode area 233cm (without light guides)
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• Weight 200Kg
• Power consumption under 700W

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5. Simulation of SUBARU with CheSS

• Night Sky background 6p.e/trigger
• Expected trigger rate0.89 26.7 1.5 30Hz
• Energy threshold (gamma) 30GeV

Jelley(1958)
Same as observation data
Cut the event when the sum of photons is under
7p.e
(Using CORSIKA)
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Sensitivity -- on-off chopping only --
Pulsed
Un-pulsed
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6. Observation log
Target Crab pulsar Date 17, 18, and 19,
December 2001 Time on 12hours, off
12hours Weather Fine
3 chopping modes 5min, 10min, and 12min
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Examples of noise reduction
N.S.B
35ns
shower
N.S.B
N.S.B
Camera image
ADC
PMT hit timing (measured by TDC)
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Trigger rate
Data on 17th
Trigger rate of raw data ON 8 - 30Hz OFF 6 -
22Hz
ON
OFF
Trigger rate after ADC cut (over 3000channel)
0.7Hz - 1.7Hz (depends on zenith angle)
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7. Summary

• Gamma-ray pulsars in 10GeV region
• Two emission models. polar cap or outer gap?
• Cherenkov light detecting System on SUBARU
• Compact detector. 1m X 1m cylindrical shape, 200
  kg weight.
• Energy threshold is about 30GeV (simulation).
• Observation of Crab
• On 17, 18, and 19, Dec 2001
• Total time On 12hours and Off 12hours.