An empirical model for calculation of the absorbed dose

An empirical model for

calculation of the absorbed

dose rates on ISS

Copy of the models are available at http://www.stil.bas.bg/dwp/R3DE_POINT_model.zip and

http://www.stil.bas.bg/dwp/R3DE_ORBIT_model.zip

Ts.P. Dachev, N.G. Bankov, B.T. Tomov, Pl.G. Dimitrov,

Yu.N. Matviichuk

Space and Solar-Terrestrial Research Institute, Bulgarian Academy of Sciences, Sofia Bulgaria, [email protected]

http://www.space.bas.bg/astro/bulg.html

mailto:[email protected]

Empirical model 2

Motivation

• To apply the accumulated from the R3DE instrument on ISS more than

4 million measurements of the absorbed dose rate with 10 seconds

resolution behind less than 0.4 g cm-2 shielding;

• To be developed free, simple for use model of the ISS radiation

environment (dose rate distribution);

• To present in one model all type of predominant sources as Galactic

Cosmic Rays (GCR), Inner and Outer Radiation Belt (IRB and ORB)

radiation (protons & electrons;

• To give to the users (not qualified in radiation physics and students)

simple tool, which present directly the doses in mGy h-1;

• The model can be used during planning of Extra Vehicular Activity of

Astronauts, for nano and micro satellites missions and for educational

purposes.

COST ES0803 Workshop,

17 March 2011, Alcala, Spain


Presentation of the instruments and data

obtained

Empirical modelCOST ES0803 Workshop

17 March 2011, Alcala, Spain 3


Empirical model 4

R3DE instrument, which is a part of the EXPOSE facility is

working continuously on the EuTEF platform of Columbus

module on International space station since February 20th 2008

R3DE

EuTEF

EXPOSE

+Z

A close-up view of the Columbus

laboratory

Credits: ESA/NASA

The detector of R3DE instrument

is shielded by less than 0.4

g/cm2 material including: 1 mm

aluminum + 0.1 mm cuprum +0.2

mm plastic. This allows direct

hits on the detector by electrons

with energies higher than 0.78,

MeV and protons with energies

higher than 15.8 MeV

UV diodes

Behind the

case SSD




Empirical model 5

Place and orientation of the R3DE instrument

+Z




Place and orientation of the R3DR instrument

Empirical model 6

+Z




Empirical model 7

R3DR R3DE




What kind of particles with which energies can

reach the detectors of the R3DE/R instruments?

Empirical model 8

The detectors of R3DE/R instruments are shielded by less

than 0.4 g/cm2 material including: 1 mm aluminum + 0.1 mm

cuprum +0.2 mm plastic.

This allows direct hits on the detector by electrons with

energies larger than 0.78, MeV and protons with energies

larger than 15.8 MeV




R3D-B2 measurements on Foton M2 spacecraft

June 2005

Empirical model 9

Inner Belt

Galactic

Aircraft

Source

Background




Empirical model 10

Procedure for calculation of

the proton energy in the

region of SAA

-50

-30

-10

10

30

50

Lati

tud

e (

Deg

)

01.21.41.61.92.53.857.5103010020040060080010001100

Do

se (

uG

y/h

)

-50

-30

-10

10

30

50

0

0.6

1.2

1.8

2.5

5

20

40

60

80

100

120

130

ISS, R3DE, 21.10.08-24.02.09 Descending orbits

Flu

x (

#/c

m^

2.s

)

-50

-30

-10

10

30

50

1.2

1.4

1.6

1.8

2

2.2

2.4

2.6

2.8

3

3.4

3.8

4.2

4.6

4.8

-180 -150 -120 -90 -60 -30 0 30 60 90 120 150 180

Longitute (Deg)

-50

-30

-10

10

30

50

1520253035404550556070809095100105

En

erg

y (

MeV

)D

/F (

nG

y.c

m^

2/p

art

.)

393927

393927

157563

125600

85.068.08 10.8.010.4)(/ ppp EEEFD

pEwhere

is the energy of the

protons. D/F ratio is

obtained from the

measured independently

dose rate and flux.

The incident energy (MeV) of

the protons normally to the

detector is calculated by using

of the experimental formula

described by (Heffner, 1971):




Empirical model 11

Comparison of Chandrajaan-1 RADOM spectra with

ISS - R3DE spectra

The shape of spectra obtained

by RADOM are same as spectra

obtained by R3DE at Int. Space Station

The RADOM proton radiation belt (IRB)

spectrum is with same shape as R3DE

spectrum but at about 1.5 order of

magnitude higher because higher flux

and respectively dose

The RADOM electron radiation belt

(ORB) spectrum is with same shape as

R3DE spectrum but about 4 time

higher lower because higher dose

The RADOM galactic cosmic rays

(GCR) spectrum practically overlap the

REDE spectrum, because of same flux

and respectively doses

1.0 10.0Deposited energy (MeV)

1E-3

1E-2

1E-1

1E+0

1E+1

1E+2

1E+3

1E+4

Dep

osi

ted

Do

se (

uG

y/h

)RADOM, PRB

RADOM, ERB

R3DE, ERB

R3DE, PRB

RADOM, GCR

R3DE, GCR

IRB 4500 km

IRB

IRB

ORB

ORB

IRB 350 km

ORB 20000 km

ORB 350 km

GCR



http://www.bas.bg/

Empirical model 12

Separation of ISS radiation sources by polynomial of L value

GCR

IRB ORB

1-10 April 2008

23-30 December 2008

1-10 June 2008

11-20 June 2009

• With the decay of solar activity in 200-2009 the number of ORB events decrease;

• The increase in SAA dose rates in 200-2009 is result of ISS altitude increase;

• Global GCR visually don’t change. Small average increase from 3.7 to 3.9 mGy/h is observed.COST ES0803 Workshop,


http://www.bas.bg/

Comparison of the daily GCR dose rates with

Oulu NM* count rates

Empirical model 13COST ES0803 Workshop,


http://cosmicrays.oulu.fi/

http://www.bas.bg/

Empirical model 14

Variations of SAA dose rate per day (mGy/day), maximum dose

(mGy/h), and Incident Energy from 22/02/2008 to 23/06/2009

• SAA (trapped) average and maximum dose rates decrease during Shuttle

docking time;

• Calculated incident proton energy increase;

STS-123 STS-124 STS-126 STS-119S

AA

Do

se

(m

Gyh

-1)

(mG

yd

-1)

In

c. E

ne

rgy (

Me

V)

No Data




Outer radiation belt daily doses compared with

the GOES >2 MeV electron flux and Planetary Ap

Empirical model 15

0.0x100

4.0x108

8.0x108

1.2x109

1.6x109

2.0x109

GO

ES

Ele

ctr

on

flu

x >

2 M

eV

(c

m-2

s-1

sr-

1)

0

50

100

150

200

250

ISS

OR

B

do

se

rate

(m

Gy

h-1

)

01/03/0

8

01/05/0

8

01/07/0

8

01/09/0

8

01/11/0

8

01/01/0

9

01/03/0

9

01/05/0

9

Time (dd/mm/yy)

0

10

20

30

40

Pla

neta

ry A

p I

nd

ex




Models of the near Earth radiation evironment




Models of the radiation environment and effects

Empirical model 17

SPENVIS is a WWW-based instrument intended to facilitate the use of models of

the spatial environment in a consistent and structured way. The SPENVIS system

consists of an integrated set of models of the space environment, and a set of help

pages on both the models and the SPENVIS system itself.

http://www.spenvis.oma.be/help/system/spenvis.html#intro

The Radiation Environment

Trapped particle radiation models, Solar proton models, Galactic cosmic ray models

Radiation Effects

Ionising dose, Non-ionising energy loss, Radiation damage in solar cells, Single

event upsets

AF-GEOSPACE is a user-friendly, graphics-intensive software program bringing

together many of the space environment models, applications, and data

visualization products developed by the Air Force Research Laboratory and others

in the space weather community.

http://www.kirtland.af.mil/library/factsheets/factsheet.asp?id=7899



http://www.bas.bg/

http://www.spenvis.oma.be/help/system/spenvis.html



NASA ModelWeb Catalogue and Archive

Empirical model 18

http://ccmc.gsfc.nasa.gov/modelweb/

Atmosphere models [info]

Density and Temperature Models

Wind Models

Ionosphere Models [info]

Electron Density Models

Electron Temperature Models

Ion Composition and Drift Models

Electric Convection Field Models

Auroral Precipitation and Conductivity Models

Miscellaneous Auroral Models

Plasmasphere Models

Trapped Particle Models [info]

•VAMPOLA PROGRAMS [info]

•SHIELDOSE [info, ftp, link]

•RADBELT [ info, ftp, RUN ]

•AE/AP Trapped Particle Flux Maps [info, ftp]

•OLDER MODELS (pre-1985)



http://www.bas.bg/

http://ccmc.gsfc.nasa.gov/modelweb/

AP-8 MIN and CRRESPRO models* results(PSB97 model don’t have positive values)


17 March 2011, Alcala, Spain http://www.spenvis.oma.be/

http://www.bas.bg/




R3DE flux data




Comparison between R3DE flux data and AP-8 MIN model

(359 km, >15.8 MeV protons)



http://www.bas.bg/

Empirical model 23

Comparison between measured data and preliminary version of

model for prediction the doses developed by N. Bankov

-180 -150 -120 -90 -60 -30 0 30 60 90 120 150 180

Longitude (Deg)

-50

-30

-10

10

30

50

-50

-30

-10

10

30

50

ISS, R3DE data, 21.10.08-24.02.09 All orbits

Model at 359 km altitude

01.21.41.61.92.53.857.5103010020040060080010001100

Do

se

ra

te (

uG

y/h

)



http://www.bas.bg/

Point Dose rate [mGy/h] model

at ISS 359 km altitudehttp://www.stil.bas.bg/dwp/R3DE_POINT_model.zip



http://www.bas.bg/

http://www.stil.bas.bg/dwp/R3DE_POINT_model.zip




../POINT_DOZ.exe

Orbital Dose rate [mGy/h] model

at ISS 359 km altitudehttp://www.stil.bas.bg/dwp/R3DE_ORBIT_model.zip



http://www.bas.bg/





../ORB_DOZ.exe

Advantages of the Empirical model



• Recent! The position of the centrum of the SAA moved from the time of

AP-8 MIN model toward Northwest with more than 15°;

• Free! Everyone can download it and use it;

• Compact! Each of the versions is less than 1 MB volume and can be

used directly in the users computer without Internet connection;

• Easy! All user interface is on the screen with few simple commands;

• Calculates directly dose rates! Most of the other models including AP-

8/AE-8 calculated the flux;

• Calculates the dose rates from all sources at once.


Conclusions and Future work for the

development of the empirical model



The model is under development and the next planned steps are:

• To be divided in 3 levels of altitude;

• To to be considered mechanism for transformation of the calculated

values for larger shielding . The data from another Bulgarian build

instrument (Liulin-5) inside of ISS is planned to be used;

• To be solved the problem with very small solar activity of the existing

model by incorporation of new data base obtained with the analogical

R3DR instrument on ISS in period with larger solar activity till August

2010;

• To be considered mechanism for transformation of the absorbed dose

rates to Ambient dose equivalent rates.

http://www.bas.bg/

HZETRN Model

Empirical model 28

HZETRN

• Computational model for engineers and research scientists studying

space radiation: HZETRN (High charge (Z) and Energy TRaNsport)

HZETRN [Wilson et al. 2006a; Slaba et al. 2010a]

Deterministic, one dimensional, efficient radiation transport code

Extensive validation in LEO [Wilson et al. 2005, 2006b, 2007; Nealy et al. 2007]

Extensive verification [Wilson et al. 2005; Slaba et al. 2010a, 2010b]

Incorporated into user-friendly web interface:

OLTARIS (On-Line Tool for the Assessment of Radiation in Space)

https://oltaris.larc.nasa.gov/Nealy, J.E., Cucinotta, F.A., Wilson, J.W., Badavi, F.F., Dachev, Ts. P., Tomov, B.T., Walker, S.A., De Angelis, G., Blattnig, S.R., Atwell, W.,

Pre-engineering Spaceflight Validation of Environmental Models and the 2005 HZETRN Simulation Code. Advances in Space Research,

Volume 40, pp. 1593-1610 (2007).

Slaba, T.C., Blattnig, S.R., Badavi, F.F., Faster and more Accurate Transport Procedures for HZETRN. NASA Technical Paper 2010-216213

(2010a).

Slaba, T.C., Blattnig, S.R., Aghara, S.K., Townsend, L.W., Handler, T., Gabriel, T.A., Pinsky, L.S., Reddell, B., Coupled Neutron Transport

for HZETRN. Radiation Measurements, Volume 45 pp. 173-182 (2010b).

Wilson, J.W., Tripathi, R.K., Mertens, C.J., Blattnig, S.R., Clowdsley, M.S., Cucinotta, F.A., Tweed, J., Heinbockel, J.H., Walker, S.A., Nealy,

J.E., Verification and Validation: High Charge and Energy (HZE) Transport Codes and Future Development. NASA Technical Paper 2005-

213784 (2005).

Wilson, J.W., Tripathi, R.K., Badavi, F.F., Cucinotta, F.A., Standardized Radiation Shield Design Method: 2005 HZETRN. SAE ICES 2006-

18 (2006a).

Wilson, J.W., Cucinotta, F.A., Golightly, M.J., Nealy, J.E., Qualls, G.D., Badavi, F.F., Angelis, G.D., Anderson, B.M., Clowdsley, M.S.,

Luetke, N., Zapp, N., Shavers, M.R., Semones, E., Hunter, A., International Space Station: A Testbed for Experimental and Computational

Dosimetry. Advances in Space Research, Volume 37, pp. 1656-1663 (2006b).

Wilson, J. W., J. E. Nealy, T. Dachev, B.T. Tomov, F. A. Cucinotta, F. F. Badavi, G. de Angelis, N. Leutke, W. Atwell, Time serial analysis of

the induced LEO environment within the ISS 6A, Adv. Space Res., 40, 11, 1562-1570, 2007.



http://www.bas.bg/

https://oltaris.larc.nasa.gov/

Empirical model 29

Pre-engineering Spaceflight Validation of Environment

Models and the HZETRN 2005 Simulation Code*

*Nealy, J. E., F. A. Cucinotta, J. W. Wilson, F. F. Badavi, N. Zapp, T. Dachev, B.T. Tomov, E. Semones, S. A. Walker, G.

de Angelis, S. R. Blattnig, W. Atwell, Pre-engineering spaceflight validation of environmental models and the 2005

HZETRN simulation code, ASR, 40, 11, 1593-1610, 2007. doi:10.1016/j.asr.2006.12.029



m = measured

c = calculated

http://www.bas.bg/

Empirical model 30

Comparison of simulated results using HZETRN

and Liulin MDUs and TEPC on ISS in 2001*

*Slaba, T.C., S.R. Blattnig, F.F. Badavi, N.N. Stoffle, R.D. Rutledge, K.T. Lee, E.N. Zappe, T.P.

Dachev and B.T. Tomov, Statistical Validation of HZETRN as a Function of Vertical Cutoff

Rigidity using ISS Measurements, Adv. Space Res., 47, 600-610, 2011.

Comparison of simulated results using

HZETRN and Liulin MDU 1 measured data

on ISS from July 6, 2001 4:00 pm to July 6,

2001 9:00 pm*

Average errors between HZETRN and

the Liulin and TEPC detectors. The error bars

represent the 95% confidence interval on the sample

mean



More than 900

GCR points calculated

http://www.bas.bg/

Analysis of the Radiation Environment due to Electrons

and Photons Inside the International Space Station*



*Norman, R., F.F. Badavi, S. Blattnig, T. Slaba, J. Norbury, Analysis of the Radiation

Environment due to Electrons and Photons Inside the International Space Station, 38th

COSPAR Scientific Assembly – Bremen, Germany, July 18-25, 2010.

Preliminary Results

http://www.bas.bg/

Future work for the validation of the HZETRN model



• In total, HZETRN was used to estimate doses for the four Liulin MDUs

and the TEPC, leading to 77,590 comparisons;

• The average error at the lowest cutoff rigidity value was approximately

22%;

• HZETRN systematically underestimates the Liulin and TEPC

measurements taken aboard the ISS;

• The largest errors coming at high cutoff rigidity values. The errors are

likely associated with anisotropies in the geomagnetic field, the lack of

pion production in HZETRN, and simplified high energy cross section

models;

• Future work will include data taken during solar minimum and trapped

proton exposures in the SAA; More detailed geometry representations

and anisotropic geomagnetic field models will also be included.

http://www.bas.bg/

Thank you for your attention



http://www.bas.bg/

Documents

An empirical model for calculation of the absorbed dose