Space Application of Geant4 Space Application of Geant4 for the Japanese Xfor the Japanese X--ray and ray and

GammaGamma--ray Missionray Mission

Yukikatsu Terada(RIKEN, Japan),

Shin Watanabe, Masanobu Ozaki, Tadayuki Takahashi (ISAS/JAXA),

and Motohide Kokubun (Univ. of Tokyo)

XX--ray to Gammaray to Gamma--ray detectors in Spaceray 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

To success the XTo success the X--ray to Gammaray to Gamma--ray missionray mission• Energy Response is the key • Low Background is the key

Absolute energy/flux calibrationAccurate pulse height distribution

Reduce the systematic errorin the background estimation

Need Monte Carlo simulation with Geant4Need Monte Carlo simulation with Geant4

Cyclotron absorption featureby magnetic field of a neutron star

Signal: 1/1000 of Crab

Large area High BGD

Small areaLow BGD

5e-4ph/s/cm2/keV

3300cm2

5e-7ph/s/cm2/keV

100cm2

Preliminary

Design phase

In Orbit phase

Soft GammaSoft Gamma--ray detectors onray detectors on--board board Japanese XJapanese X--ray Satellitesray Satellites

Current Mission:Suzaku (2005～)

Future Mission:NeXT (2011～)

Hard X-ray detector (HXD) Super X-ray Telescopewith

Hard X-ray Imager (HXI)

Soft Gamma-rayDetector (SGD)

1010––600 600 keVkeV, 10, 10--55cnt/s/cmcnt/s/cm22/keV/keV1010––70 70 keVkeV, , 1010--88cnt/s/cmcnt/s/cm22/keV/keV

5050––400 400 keVkeV, , 1010--77cnt/s/cmcnt/s/cm22/keV/keV

Successful launch of AstroSuccessful launch of Astro--E2, Suzaku E2, Suzaku The fifth Japanese X-ray satellite, Astro-E2Launched on 10th July 2005, 03:30UTNamed as “Suzaku”

Copyright ISAS/JAXA Copyright ISAS/JAXA

Copyright ISAS/JAXA

Hard X-ray Detector (HXD)

10–600 keV105cnt/s/cm2/keV

RIKEN, RIKEN, Univ. of Tokyo,Univ. of Tokyo,ISAS/JAXA,ISAS/JAXA,AoyamaAoyama--Gakuin, Gakuin, Saitama Univ.,Saitama Univ.,Hiroshima Univ.,Hiroshima Univ.,Kanazawa Univ.,Kanazawa Univ.,Osaka Univ.,Osaka Univ.,Stanford Univ.Stanford Univ.

HXD-II team, with HXD Sensor before integration (June, 2004)

Orbit: altitude 568kmeccentricity less than 0.0002% (Circle)inclination 31.4 degrees

Hard XHard X--ray Detector, HXDray Detector, HXDCross Section Top View

Photo-absorber:PIN PIN SiSi diodediodeGSO GSO scintillatorscintillator

Passive Collimator

Anti coincidence shieldBGO BGO scintillatorscintillator

16 Well-type Units and 20 Anti BGO Units

Optical Axis

M. Kokubun et.al., IEEE T.N.S,51,1991,2004M. Tashiro et.al., IEEE T.N.S.,49,1893,2002and references therein.Original concept in

T. Kamae et.al. Proc.SPIE,2806,314,1996

Suzaku Geant4 simulatorSuzaku Geant4 simulatorReal World Geant4

• Two main purposeconstruct the energy responseestimate background in orbit

•Suzaku original framework, ANLto share standard analysis tools anddata base for the actual dataM.Ozaki et.al., IEEE T.N.S. submitted

• Original Detector-Constructionclass and Material-Factory classcollaborate with other instrumentsonboard Suzaku

• Pre-flight studies for the HXDvalidate the simulation with actual data in the calibration experimentsY.Terada et.al., IEEE T.N.S.,54,902,2005M.Ohno et.al., IEEE T.N.S. sumitted

Overview

Comparison with the PreComparison with the Pre--flight data Iflight data I

PIN PI (channel energy)

Coun

ts

PIN Spectrum

GSO Spectrum

Calculate an Energy deposit

Digitization RI irradiation test

PH o

f Sl

ow S

hape

r

PH of Fast Shaper

PH o

f Sl

ow S

hape

r

PH of Fast Shaper

Real WorldGeant4

include the Sensor response

Comparison with the PreComparison with the Pre--flight data IIflight data IIReal WorldGeant4

RI scanning test around HXD,before and after integration

HXD BGO Units

RI

Absorption map

Geant4 Geometry of Suzaku

Comparison with the inComparison with the in--orbit dataorbit datafor the calibration purposeReal WorldGeant4

Incident Energy spectraof

Known astrophysical objects

×Energy Response by Geant4:Matrix of (incident energy

v.s. Pulse height)

Expected pulse height distribution

Crab Nebula

Preliminary

Preliminary

Currently: 5-10%Goal: 1-2%

Background study and estimationBackground study and estimationReal WorldGeant4 (plan)

Under developing!!Under developing!!Under developing!!

H2+,135MeV/nuc

Total 1.1x109cntsExposure: 15min

Beam Experiment (RIKEN)

Irradiated particle flux,counted by HXD-PIN.

HXD WAM count rate (1 day)

Particle in orbit

Geant4 Mass Model

Hadron/Nucleonproduce secondary particleradio-activate process

Nuclear/Atomicde-excitation

EM transport

Detector response

In orbit

Simulation (MGGPOD)

Concept study for NeXT MissionConcept study for NeXT Mission

Scientific simulation

Performance estimation with Geant4NeXT SGDNarrow Field Compton Telescope50–400 keV, 107cnt/s/cm2/keV

Compton ImageTwo source, 122keV

Laboratory:40 layer CdTe stack

S.Watanebe et.al. IEEETNS 49,p1292,2002 T.Tanaka et.al. SPIE,2004

H.Tajima et.al. IEEE NSS-CR, vol.1,p314,2004

SummarySummaryWe 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.