Space Application of Geant4 for the Japanese X-ray X Gamma-ray Mission

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1 Space Application of Geant4 for the Japanese X-ray X and Gamma-ray Mission Yukikatsu Terada (RIKEN, Japan), Shin Watanabe, Masanobu Ozaki, Tadayuki Takahashi (ISAS/JAXA), and Motohide Kokubun (Univ. of Tokyo)

2 X-ray to Gamma-ray detectors in Space Many detectors, designed for astrophysical observations Photo-absorption + Collimator Coded mask + Position Sensitive Detector Compton telescope BeppoSAX PDS, CGRO OSSE, Suzaku HXD etc.. INTEGRAL SPI&ISGRI, Swift BAT, Yohko, RHESSI (rotation mask), CGRO COMPTEL

3 To success the X-ray X to Gamma-ray mission Energy Response is the key Design phase Low Background is the key Large area High BGD 3300cm2 5e-4ph/s/cm2/keV Preliminary Small area Low BGD Cyclotron absorption feature by magnetic field of a neutron star 100cm2 5e-7ph/s/cm2/keV Signal: 1/1000 of Crab Absolute energy/flux calibration Accurate pulse height distribution In Orbit phase Reduce the systematic error in the background estimation Need Monte Carlo simulation with Geant4

4 Soft Gamma-ray detectors on-board Japanese X-ray X Satellites Current Mission: Suzaku (2005~) Future Mission: NeXT (2011~) Hard X-ray detector (HXD) Super X-ray Telescope with Hard X-ray Imager (HXI) Soft Gamma-ray Detector (SGD) kev,, 10-5 cnt/s/cm 2 /kev kev, 10-8 cnt/s/cm 2 /kev kev, 10-7 cnt/s/cm 2 /kev

5 Successful launch of Astro-E2, Suzaku The fifth Japanese X-ray satellite, Astro-E2 Launched on 10 th July 2005, 03:30UT Named as Suzaku Hard X-ray Detector (HXD) kev 10 5 cnt/s/cm 2 /kev Copyright ISAS/JAXA RIKEN, Univ. of Tokyo, ISAS/JAXA, Aoyama-Gakuin, Saitama Univ., Hiroshima Univ., Kanazawa Univ., Osaka Univ., Stanford Univ. Copyright ISAS/JAXA Copyright ISAS/JAXA Orbit: altitude 568km eccentricity less than % (Circle) inclination 31.4 degrees HXD-II team, with HXD Sensor before integration (June, 2004)

6 Cross Section Hard X-ray X Detector, HXD Optical Axis Photo-absorber: PIN Si diode GSO scintillator Passive Collimator Top View Anti coincidence shield BGO scintillator 16 Well-type Units and 20 Anti BGO Units M. Kokubun et.al., IEEE T.N.S,51,1991,2004 M. Tashiro et.al., IEEE T.N.S.,49,1893,2002 and references therein. Original concept in T. Kamae et.al. Proc.SPIE,2806,314,1996

7 Suzaku Geant4 simulator Overview Two main purpose construct the energy response estimate background in orbit Suzaku original framework, ANL to share standard analysis tools and data base for the actual data M.Ozaki et.al., IEEE T.N.S. submitted Original Detector-Construction class and Material-Factory class collaborate with other instruments onboard Suzaku Real World Geant4 Pre-flight studies for the HXD validate the simulation with actual data in the calibration experiments Y.Terada et.al., IEEE T.N.S.,54,902,2005 M.Ohno et.al., IEEE T.N.S. sumitted

8 Comparison with the Pre-flight data I Geant4 Calculate an Energy deposit Real World PIN Spectrum Counts PIN PI (channel energy) Digitization include the Sensor response RI irradiation test GSO Spectrum PH of Slow Shaper PH of Slow Shaper PH of Fast Shaper PH of Fast Shaper

9 Comparison with the Pre-flight data II Geant4 Geant4 Geometry of Suzaku Real World Absorption map RI scanning test around HXD, before and after integration RI HXD BGO Units

10 Comparison with the in-orbit data Geant4 Real World for the calibration purpose Incident Energy spectra of Known astrophysical objects Energy Response by Geant4: Matrix of (incident energy v.s. Pulse height) Preliminary Crab Nebula Preliminary Expected pulse height distribution Currently: 5-10% Goal: 1-2%

11 Background study and estimation Geant4 (plan) Under developing!! Particle in orbit Real World Beam Experiment (RIKEN) Simulation (MGGPOD) Geant4 Mass Model Hadron/Nucleon produce secondary particle radio-activate process Nuclear/Atomic de-excitation In orbit H 2 +,135MeV/nuc Total 1.1x10 9 cnts Exposure: 15min Irradiated particle flux, counted by HXD-PIN. HXD WAM count rate (1 day) EM transport Detector response

12 Concept study for NeXT Mission NeXT SGD Narrow Field Compton Telescope kev, 10 7 cnt/s/cm 2 /kev Performance estimation with Geant4 H.Tajima et.al. IEEE NSS-CR, vol.1,p314,2004 Scientific simulation Laboratory: 40 layer CdTe stack Compton Image Two source, 122keV S.Watanebe et.al. IEEETNS 49,p1292,2002 T.Tanaka et.al. SPIE,2004

13 Summary We have developed a Geant4 studies for the Japanese X-ray to Gamma-ray astrophysical mission; Suzaku (current mission, 2005) HXD NeXT (future mission, 2011) HXI and SGD The purpose is two, study of the energy response estimation of the in-orbit background.