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-noise detector systems The 5th Japanese X-ray astronomy satellite

Suzaku X-ray Imaging Spectrometer (XIS) XIS camera body Suzaku satellite X-ray telescope (XRT) Readouts 2.5cm 1.4 cm 2.5 cm 4.75m Focal length 15cm Imaging region Frame-store region CCD chip

Background-event spectrum of XIS Physics 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 + Phoswitch BGO 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 simulation based on Geant4 energy deposit-> signal simAE simDE pipeline processing simulation 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( keV) BLACK: real data, RED: emission model x response These responses are used by all the Suzaku Observers.

HXD WAM: Wide All-sky Monitor BGO 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 MagnetospheresThe Plasma UniverseGeospace Exploration BepiColmbo L2013 ESA/JAXA mission to Mercury ESA/JAXA mission to Jupiter in 2020’s (to be proposed to ESA CosmicVision) SCOPE/CrossScale ESA/JAXA Multiscale at the same time in Earth magnetosphere ~2016 (to be proposed to ESA CosmicVision) ERG A small explorer into the 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 Mercury The 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) C. Noshi/RISH, Kyoto Univ. Baseline Schedule 2012Launch 2017Mercury Arrival MMO [JAXA] MPO [ESA] Mercury Project Office:

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 scintilator  High modulation factor  Optimized 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 Proposal to NASA Spring8/Argonne Beam Test KEK Beam Test KEK Beam 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 deg 2 ) Fast Plastic Scint. (Pol. measurement) Bottom BGO PMT assembly (low noise) Side BGO Scint. Shield (BG rejection.) 1 st prototype (fast scinti. 7 units) 2 nd 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 Crab PoGOLite Geant4 simulation Polarized Compton Scattering  PoGO-fix process Rayleigh Scattering  Implement Pol. dependence

ISS mission: GSC/MAXI by 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: 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) Target Cu-K line (8.1keV) Comparison between ground calibration and DRM output

Other missions Swift/BAT: Detector response generation (SWIMM) INTEGRAL/IBIS Detector response evaluation NeXT (proposal phase): Detector response estimation Background spectrum estimation

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.