geant4 in astro-h observatory development - indico at esa

Geant4 in ASTRO-H observatory Development

Masanobu Ozaki (ISAS/JAXA)<[email protected]>,

H. Odaka, T. Sato and M. Asai

Outline

1. ASTRO-H observatory

2. This year’s highlights

– Shielding Study

– Activation Simulation

3. What’s Next?

2014-05-27,28,29 / 10th Geant4 SUWSGeant4 in ASTRO-H observatory

development2

ASTRO-H

• 6th Japanese X-ray astronomy satellite

• Scheduled for launch in 2015

• 1.7t mass, 14m length

• LEO of 550 km altitude, ~30 deg inclination angle

• 1st end-to-end integration and test campaign in progress.


development3

(SUWS7, 2010)

HXI

SXS SXI

L = 14 m

SGD

ASTRO-H: detectorsFour kinds of detectors:

SXS: X-ray micro calorimeter, with a few hundred Kg aluminum alloy

SXI: X-ray CCD camera with thick Al shield for < 10 keV band

HXI: Si-strip and CdTe-pixel cameras for > 10 keV band, also sensitive for atmospheric neutron backgrounds

SGD: Compton kinematics telescopes with BGO active shields for a few hundred keVband

Different photon detection mechanism and sensitivity for

background radiation-> MC simulation is essential


development4

(SUWS7, 2010)

This year’s highlights.

– HXI shielding study

– Activation study using Geant4 v.10


development5

CXB Shielding design for HXI


development6

Green:CandidatePb shields

Attenuation (and sometimes secondaries?) changes by shield pattern.

Activation Simulation

• We succeeded in reproducing the activation by accelerator beam tests, using Geant4 database, without external library.

– Much simpler structure than past, and easy to maintenance in future.


development7

ASTRO-H Geant4 and Activation

Tasks

(SUWS8, 2011)

Activation progress• We confirmed that the CdTe activation simulation, especially for

continuum level, agrees quite well with the experiments. This should support to make the in-orbit BGD simulation reliable.

• Isomer lines were not represented well: Geant4 v.9 Hadronicprocesses don’t generate them.


development8

(SUWS9, 2013)

0.5d after irradiation

2d

14d

Activation from CdTe detector


development9

Blue: G4 v.9 Binary Cascade

Red: G4 v.10 Binary Cascade

1-20 min after irradiation

Black: Experiment Data

Geant4 v.10 represents lines from short-life isomers, and continuum level agrees with the experiment.

What’s Next?

• “Products” from the simulator have not been released yet, while expected from last year. At that time, the simulation efficiency, such as event biasing, was thought to be a key.

• Now, however, resources (of both human and computing) organization seems most important. This is not a technical but a management issue.


development10

1. CR incident and interaction

2. Generate secondaries 3. Bias distribution

probability, etc.

(backup slides)


development11

Geometry Description

• Detectors and mirrors are placed in different logical spaces (“parallel world”) from the spacecraft structure.– This allows the geometry overlaying between two spaces,

and makes it easy to develop each component/structure incrementally.


development12

(SUWS8, 2011)

Geometry Status

• Now most of components are implemented with 95-99% mass precision, by hand.


development13

Simulator Dataflow• I/O compatible with existing software• Using external heritage: X-ray mirror ray tracing software


development14


SimX equivalent FITS event file or ASTRO-H

First Fits File

Phase Space File (FITS): (x, y, z, px, py, pz, E,

IDPDG, Eex)

Background particle

generationBackground parameter

X-ray mirror simulator

X-ray mirror incident photon file (FITS)

(q, f, E)

Photon generation (from

celestial body)

Photon source parameter: SimX-

compatible spectrum QDP & FITS image

Format conversion

Phase Space File (FITS): (x, y, z, px, py, pz, E)

Inputs

Geant4

External software

Outputs

DATA

PROCESSES

I/O compatibility• Charged particle background sources are separately

described from photons.• Accepts existing software’s celestial body description.• Outputs high energy astronomy’s standard format “event

FITS”.


development15

Background particle



celestial body)



InputsASTRO-H Geant4

and Activation


First Fits File

Tasks

Outputs

External software and Geant4

• We decided to use heritage for X-ray telescopes’ ray tracing, because of strong request from the hardware developers.


development16



First Fits File

Phase Space File (FITS): (x, y, z, px, py, pz, E,

IDPDG, Eex)

Background particle


X-ray mirror simulator

X-ray mirror incident photon file (FITS)

(q, f, E)


celestial body)



Format conversion

Phase Space File (FITS): (x, y, z, px, py, pz, E)

Inputs

Geant4

External software

Outputs

DATA

PROCESSES

External software and Geant4

• The simulation uses external heritage ray tracing software for the mirror X-ray transportation.→ Consistency between official user tools and Geant4

simulation is automatically ensured.


development17

Geant4’s tracks start from the bottom of XRT

Beta release• Beta version will be released to ASTRO-H science community, which is not

familiar with Geant4.• Beta version should

– work on most of Mac OS X and Linux,– have simX 2.0 compatible I/O,– simulate all the detectors, and– be ready in one week or so.


development18

ASTRO-H simulated image

Kepler’s supernova remnant image

X-ray spectrum

the simulator

geant4 in astro-h observatory development - indico at esa

Documents