Geant4 Application for Japanese Space Science

Missions from 2006 to Future

Masanobu Ozaki

(ISAS/JAXA and JST/CREST)

Japanese Space Science Missions

In Japan, most of fundamental researches relating to the on-orbit radiation environment are carried out for non-commercial (i.e. scientific) missions.

1. X-ray and Gamma-ray astronomy

2. Inter-planetary missions

3. Balloon missions

4. Automated ISS mission

This presentation will introduce them briefly.

X- and Gamma-ray astronomy

“Suzaku” Observatory (ISAS/JAXA and many universities)

Launched on July 10, 2005

•XIS (X-ray CCD camera) [0.3—12 keV]•HXD (Hard X-ray Detector) [10—600 keV]

High-precision and Low-noisedetector systems

The 5th Japanese X-ray astronomy satellite

Suzaku X-ray Imaging Spectrometer (XIS)

XIS camera bodySuzaku satellite

X-ray telescope(XRT)

Readouts

2.5cm

1.4c

m2.

5cm

4.75mFocal length

15cmIm

agin

g re

gion

Fra

me-

stor

e re

gion

CCD chip

Background-event spectrum of XISPhysics processes

•Electromagnetic Interaction(down to 250eV)

•Hadronic Interaction

Used Geant4 outputs:

•Physics process of particle generation, position, energy, solid-ID•Energy deposition and its physics process•ParentID 、 TrackID 、 StepNumber

Succeeded in representing the BGD spectrum and resolving the BGD generation mechanism

Geant4 simulation (energy deposition) + charge-diffusion simulation in CCD

Primary events from 4 Sr

Suzaku Hard X-ray Detector (HXD)

　 PIN*64

BGO

GSO*16

(10 ～ 60keV)

(30 ～ 600keV)

Si-PIN [2mm thick](10—60 keV)GSO [5mm thick](30—600keV)BGO: Shield + PhoswitchBGO well + Fine Collimator: narrow FOV as a non-imaging detector

-> Low Background-> High Sensitivity

Complex Response for incident photons

Performance Key: Monte Carlo simulator

simHXD: full simulator of HXD

Mass Model

(energy, direction)

MC simulationbased on Geant4

energy deposit-> signal

simAE

simDE

pipeline processingsimulation data

mass model

HXD responses:based on simHXD outputs

Crab Nebula (a standard candle) -> well-studied emission spectrum

HXD-PIN(10-70 keV) HXD-GSO(40-600 keV)

BLACK: real data, RED: emission model x response

These responses are used by all the Suzaku Observers.

HXD WAM: Wide All-sky MonitorBGO anti-co units around HXD:Not only for active shielding, but also all-sky detector for• Gamma-ray burst spectroscopy• Bright source monitor• …

Astro-E2 Mass Model

We must take into account of the absorption and scattering of full-satellite components such as• Solid-Ne dewar• satellite-structure panels• solar array panels• .......

Future Space Plasma Missions at JAXA ~2020’s

Planetary Magnetospheres The Plasma Universe Geospace Exploration

BepiColmbo L2013ESA/JAXA mission to Mercury

ESA/JAXA missionto Jupiter in 2020’s(to be proposedto ESA CosmicVision)

SCOPE/CrossScale ESA/JAXAMultiscale at the same timein Earth magnetosphere ~2016(to be proposed to ESA CosmicVision)

ERGA small explorer intothe inner-magnetosphere and relativistic particle acceleration processes~2011

BepiColombo: Mission to Mercury

First Full-Scale Euro-Japan joint mission

Two orbiters (MPO & MMO) will observe Mercury simultaneously with instruments developed by Euro-Japan joint research teams.

Complete study of MercuryThe innermost planet Mercury was already known in the ancient days, but it was visited only by the Mariner 10 spacecraft 3 decades ago. Mercury is still “unknown” and provides important keys to the solar system science.

MPO （ Mercury Planetary Orbiter)is a three-axis stabilized spacecraft. It studies geology, composition, inner structure and the exosphere. Abnormal structure and composition of Mercury will provide the keys for the planetary formation in the inner solar system.

MMO （ Mercury Magnetospheric Orbiter ）is a spin-stabilized spacecraft. It studies magnetic field, atmosphere, Magnetosphere, and inner interplanetary space. Comparison of magnetic field & Magnetosphere with Earth will provide the new vision for space physics.

MMO [9.3h / orbit]400km x 12,000km

MPO [2.3h / orbit]400km x 1500km

Design & Development by JAXA

MMO (Mercury Magnetospheric Orbiter)

- High temperature materials & technologies.- Best scientific instruments from Japan-Euro collaboration.

Design & Development by JAXA

MMO (Mercury Magnetospheric Orbiter)

- High temperature materials & technologies.- Best scientific instruments from Japan-Euro collaboration.

Orbit / Mercury Magnetosphere (model)

Orbit / Mercury Magnetosphere (model)

C. Noshi/RISH, Kyoto Univ.

Baseline Schedule2012 Launch2017 Mercury Arrival

MMO[JAXA]MPO[ESA]

Mercury Project Office: http://www.stp.isas.jaxa.jp/mercury/

Using Geant4 in future space plasma missions

• Calculation of Radiation Dose in Spacecraft– Solar array– Electric parts ( including SEU/SEL )– Sensors ( CCD/SSD/MCP …)

• Estimation of Radiation Background in each Scientific & System Instruments– Using Geant4 for development of plasma instruments

in order to obtain high quality scientific data under strong radiation environment (Mercury, Radiation Belt, Jupiter etc )

Balloon mission: PoGOLite by Hiroshima-U, TiTech, Yamagata-U, SLAC and others

•Compton Polarimeter made of plastic scintilatorHigh modulation factorOptimized for Hard X-ray (25-100keV)

Balloon Flight!

•Japanese Consortium ：•PMT 、 Beam test, DAQ, Performance modeling

•Stanford University: Detector array, DAQ, Gondola and attitude control system, Payload integration and testing

•Swedish Consortium:Side-anticoincidence Shield, Observation planning

•Ecolo Polytechnique:Scintillator and crystal reflective material

2003 2005 2006 2007 2008

Proposal to NASASpring8/Argonne

Beam Test

KEKBeam Test

KEKBeam Test

Proton Beam Test (Osaka)

2004

Second Proposal to NASA

Sensor Complete

Gondola Ready

Flight Instrument Integration

Schedule

(b)

Slow Plastic Scint.Collimator (FOV:5 deg2)

Fast Plastic Scint.(Pol. measurement)

Bottom BGOPMT assembly(low noise)

Side BGO Scint.Shield (BG rejection.)

1st prototype(fast scinti. 7 units)

2nd prototype(fast/slow 19 units+anti)

Flight Instrument Integration and Test

-- Geant4 (original) : MF=12.4%-- Geant4 (with fix) : MF=22.2%-- EGS4 : MF=21.8%

Modulation Curve for CrabPoGOLite Geant4 simulation

•Polarized Compton ScatteringPoGO-fix process

•Rayleigh ScatteringImplement Pol. dependence

ISS mission: GSC/MAXIby JAXA and universities

FOV : 1.5deg ×160deg

The FOVs sweep almost the entire sky during one ISS orbital period of 90 minutes. A point source stays in the FOV for 45 seconds.

Monitor of All-sky X-ray Image of 2-30 keV (GSC)

The collimator:

Material : phosphor bronze

Thickness: 0.1 mm, Height: 118.4 mm

The interval between slats: 0.1 mm

128 slats for one GSC unit

Ground calibration:• Energy-PH relation, position-PH relation, energy resolution, position resolution• The collimator response based on design value

Geant4 simulation• geometry from design sheet• photoelectric absorption, energy deposition, multiple scattering• considering L-escape

Detector Response Matrix (DRM) builder for GSC/MAXI

　 :Calibration data

:DRM simulations(8keV)(X= － 5mm,Y= － 80mm)

(X= － 5mm,Y= － 80mm)Target Cu-K line (8.1keV)

Comparison between ground calibration and DRM output

Conclusion

• Several Japanese space science mission use or will use Geant4– To construct the detector response to the

incident photons.– To simulate the detector outputs due to the

environment radiation.