space radiation environment & geant 4/gras simulations in sr2s

41
Radiation Environment and Geant4/GRAS Simulations in SR2S April 9 th , 2014 Martina Giraudo Marco Vuolo

Upload: sr2s-space-radiation-superconductive-shield

Post on 30-May-2015

177 views

Category:

Science


0 download

DESCRIPTION

Space Radiation Superconductive Shield (SR2S) is an EU funded FP7 project which is researching new technology to protect astronauts in space from radiation. On 9th April 2014 in Torino, Italy, SR2S held their first conference to give an update on the project so far. For more information visit: www.sr2s.eu Twitter - @SR2SMars

TRANSCRIPT

Page 1: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

Radiation Environment and

Geant4/GRAS Simulations in SR2S

April 9th, 2014

Martina Giraudo

Marco Vuolo

Page 2: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

• SR2S introductory VIDEO

• Space radiation Environment

• HZE biological effects

• TAS-I simulation framework

• Simulated Environment

• Geometrical Model

• Simulation Plan & Future Works

Summary

Page 3: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

SR2S Introductory Video

Page 4: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

• Cancer risk caused by radiation exposure is the main obstacle to interplanetary travel

– No simple and effective countermeasures

– Significant uncertainties

• Possible solutions:

– Optimization of space missions length

– MITIGATION MEASURES: SHIELDING and biological countermeasures

Introduction

Page 5: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

Space Radiation in Deep-Space

• Space radiation hitting the crew: HZE, primary protons and secondary protons, neutrons, and recoil nuclei

• Secondary particles produced as radiation interacts with matter

• Whole body doses of 1 to 2 mSv/day accumulated in interplanetary space

Two main components : SPE & GCR

Page 6: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

Solar particle events (SPEs)

• Mainly energetic protons, helium nuclei and heavier nuclei

• Highest intensity at solar maximum

• Relative short fluxes of particles

• Energies from 1 to 100 MeV

• Not currently predictable

• Easily shielded by passive

and active shields

Galactic cosmic rays (GCR)

• Continuous source

• Energies ranging from ~10

MeV n-1 to ~ 1012 MeV n-1

• High-LET radiation

• Biological effects poorly

known

• Most significant deep-space

missions radiation hazard

• Modulated by the Sun cycle

• Not easily shielded

Space Radiation in Deep-Space

Page 7: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

Deep Space Effective Dose Estimations

• When considering passive shielding option:

– SPE easily shielded

– GCR requires enormous mass to be shielded because of high energies and secondary radiation

• Mission at solar maximum

• Thick shielding:

– Mass problems to spacecraftlaunch systems

– Bad GCR effective dose reduction

Current shield approach:

NOT a solution

Annual GCR Effective doses or NASAEffective dose in deep space vs. depth ofshielding for males. Values for solarminimum and maximum are shown

Page 8: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

Radiation Biological Risk to the Crew

• Carcinogenesis (morbidity and mortality risk)

• Acute Radiation Risks – sickness or death

• Acute and Late Central Nervous System (CNS) risks

• Chronic & Degenerative Tissue Risks

Differences in biological damage of heavy nuclei vs x-rays Earth-based data � New knowledge on risks must be obtained

CONTROL

IRON IRRADIATED

Oxi

dat

ive

stre

ss is

incr

ease

d in

Mo

use

Hip

po

cam

pu

s 9

m

on

ths

afte

r 2

Gy

of

56

Fe ir

rad

iati

on

Page 9: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

HZE effects vs low-LET radiation effects

• HZE produce densely ionizing tracks of damage

• Complex DNA breaks, “clusters”containing mixtures of more kinds of damage– Poor damage repair

– Cell death more frequent

“Cancer risk from exposure to galactic cosmic rays: implications for space

exploration by human beings” Francis A Cucinotta, Marco Durante

Page 10: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

• Drugs– applicable for extended period of time and suitable for high-LET radiation

– no significant side effects, including those on behavior

– stable chemical composition (easy handling and storage)

– better if suitable for oral administration and rapidly absorbed and distributed throughout the body

• Dietary supports– Space environmental factors leading to increased oxidative stress �

deployment of antioxidant capacity in astronauts

– antioxidant rich diet � decreased risk of several diseases, cancer included

– Possible antioxidant radioprotectors: vitamin E and C, melatonin and selenium

• Appropriate crew selection

Biological Countermeasures

Page 11: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

SR2S Geant4/GRAS simulation

• Simulation framework

• Environment models

• Geometrical model

– Coils & cables

– Mechanical structures

– Habitat

– Detectors

• Simulation plan

Page 12: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

TAS-I Monte Carlo Simulation Framework

Simulations are simultaneously run on different processors

Results are saved in ROOT histogram for post processing

Geant4 Radiation Analysis for Space

MC toolkit for the simulation of interaction of particles in matter

Page 13: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

• GCR– CRÈME96– Solar minimum condition– No Scaling factor: variation from 1 AU to Mars Orbit is negligible for

SR2S scope (see new measurements from MER and MSL missions)

• SPE– SUPERFLARE fluence

• CREME86 (M11 - M1) representative of period 1955 to 1972 (as envelope of events of Feb ‘56 and Aug ‘72) composite worst case (hour) flare flux and mean ions composition;

• OMERE worst hours flare fluxes of: Oct ‘89, Jul ‘00, Oct ’03

– Average flux on 1 year interplanetary mission• ESP model @ 99% confidence level

• TRAPPED PARTICLES: neglected in SR2S

Modeled Environment

Page 14: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

• Compromise between accuracy of the geometrical details and computational time

– Complex geometries simplified to obtain homogeneous Geant4 materials with average elemental compositions

– Habitat modeled using average values of thickness and density

– Mechanical structures simplified

Geometric Model

Page 15: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

Geometric Model: Mechanical Structures Materials

Solid Hydrogen equivalent mass

Structural Titanium equivalent mass

Fuel Tank

Second Columbus module

Page 16: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

Geometric Model: Mechanical Structure & SC Cable

Titanium

Bars

Ti equivalent

in mass

Solid

Hydrogen

• In this way computational time is saved and no significant accuracy is lost

• As soon as the mechanical structure is finalized the geometry GDML files will be easily updated.

Page 17: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

SR2S Toroidal Configuration: Sectoring Analysis

Detector

Page 18: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

ICRU SPHERE

Used Detectors: ICRU Sphere in three different positionICRU Sphere structure and composition:

BFO 2 mm

SKIN 2mm150 mm

100 mm

Skin � G4_SKIN_ICRP*Body � G4_TISSUE_SOFT_ICRU-4*BFO � G4_TISSUE_SOFT_ICRU-4*Organs � G4_TISSUE_SOFT_ICRU-4*

*http://geant4.web.cern.ch/geant4/UserDocumentation/UsersGuides/ForApplicationDeveloper/html/apas08.html

Page 19: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

Magnetic Field Configuration

120 CoilsBmax= 3.53 TBL= 7.47 Tm

Page 20: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

Magnetic field Validation : Analytic model vs. Geant4

Perfect matching between analytical previsions and simulation results

Page 21: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

Magnetic field Validation : Analytic model vs. Geant4

Page 22: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

Magnetic field Validation : Analytic model vs. Geant4

Page 23: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

1. ICRU sphere in free space

2. Columbus habitat only

SR2S Simulation Plan 1/5

Page 24: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

3. Columbus habitat and magnetic field only

4. Columbus habitat, active shielding structures and magnetic field ON

SR2S Simulation Plan 2/5

Page 25: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

5. Columbus habitat with active shielding structures and NO magnetic field

6. Columbus habitat surrounded by passive shielding rich in H equivalent in mass to the active one

SR2S Simulation Plan 3/5

Page 26: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

• Doses have been already calculated for every considered radiation environment components for:

– ICRU sphere in deep space

– Example of deep space habitat in deep space

• Results will include data on:

– Doses - Equivalent Doses

– Fluxes - Fluences

SR2S Simulation Plan 4/5

ICRU SPHERE IN FREESPACE

Page 27: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

• Results will be available by the end of May and will permit a first evaluation of the active radiation shielding

• Other evaluations will have to be performed once the design of the mechanical structure is finalized

SR2S Simulation Plan 5/5

Page 28: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

• No actual passive shielding solutions to GCR

• Investigation of magnetic active shielding as a possible way to overcome the problem

• Necessity to further develop the involved technology, focusing on:

– Optimization of structures

– Safety and reliability

• Necessity to have biological data for GCR

Conclusions

Page 29: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

THE ENDThank you for your attention

Questions?

Page 30: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

BACK UP SLIDES

Page 31: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

SR2S Environment: Superflare differential flux

1,00E-06

1,00E-05

1,00E-04

1,00E-03

1,00E-02

1,00E-01

1,00E+00

1,00E+01

1,00E+02

1,00E+03

1,00E+04

1,00E+05

1,00E+06

1,00E+07

1,00E-01 1,00E+00 1,00E+01 1,00E+02 1,00E+03 1,00E+04 1,00E+05

pro

ton

s.M

eV

-1.c

m-2

.s-1

MeV

Superflare Differential Flux

CREME86 M11-M1

Oct 89 worst hour

Oct 03 worst hour

Jul 00 worst hour

Aug 72 worst hour

Page 32: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

SR2S Environment: GCR differential fluxes

Page 33: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

MissionTotal Mission

DurationOutbound Stay Return

Total Days in Deep-Space

Lagrange’s Points [LEM2]

200 - - - 200

NEA 410 ~170 30 ~210 ~380

MARS TITO mission

501 228 - 273 501

MARS Short Stay 545 224 30 291 515

MARS Long Stay(minimum

energy)919 224 458 237 461

MARS Long Stay(fast transit)

879 150 619 110 260

Considered Mission Scenarios

Page 34: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

The Hydrogen GCR flux at 1AU predicted by CREME96 and CREME2009

particle flux models for the solar minimum

CRÈME 96 vs CRÈME2009

Page 35: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

Differential GCR Protons Fluence for Different Scenarios

Page 36: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

• Astronauts who are on missions to the ISS, the moon, or Mars are exposed to ionizing radiation with effective doses in the range from 50 to 2,000 mSv

• The evidence of cancer risk from ionizing radiation is extensive for radiation doses that are above about 50 mSv.

Doses in Space

Page 37: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

HZE

Differences in biological damage of heavy nuclei with x-rays Earth-based data �New knowledge on risks must be obtained

Possible acute or late damages to CNS, caratacts, heart tissues, etc, from low dose rate (< 50 mGy/h) of HZE

CONTROL

IRON IRRADIATED

Oxi

dat

ive

stre

ss in

incr

ease

d in

Mo

use

Hip

po

cam

pu

s

9 m

on

ths

afte

r 2

Gy

of

56

Fe ir

rad

iati

on

Page 38: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

• International overview:– ESA: dose limits based on ICRP recommendations for ground-base

workers with some modifications

– NASA, JAXA: age and gender dependent limits for late effects

• Career Limits based on a 10 years exposure

LEO Exposure Limits – Career Effective Dose Limits

Page 39: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S
Page 40: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

Uncertainties in Risk Projection in Radiation Exposure

From Cucinotta and Durante, 2011

Page 41: Space Radiation Environment & Geant 4/GRAS Simulations in SR2S

Magnetic field Validation : Analytic model vs. Geant4