Development of the HARM model for aviation dosimetry

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Development of the HARM model for aviation dosimetry

M.G. Mosotho¹, R.D. Strauss¹ & R. R. Nndanganeni²

1Center for Space Research, North-West University, 11 Hoffman Street, Potchefstroom, South Africa.

2Space Science Division, South African National Space Agency, Hospital Street, Hermanus, South Africa.

65^thSAIP Conference|Nelson Mandela University, Gqeberha

1^st - 8^th July 2022

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Overview

Introduction & Model Description Applications

Status & Conclusion

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Introduction

“Snapshort”: High Altitude Radiation

Credit image: M¨oller [2013], PhD Thesis 3 / 12

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Dose approximation model:

D_r(P_c, t, h) =− Z h

h0

Z ∞ Pc

dD_f

dP dPdh= Z h

h0

Z ∞ Pc

J (P, t)F(P, h)dPdh

Dorman Function :D_f(P_c, h) =D₀(P_c, h)1−exp(−α(P_c/P₀)^−κ)

CDA solution :J (P, t) =J₀(P)exp

− ψ β^ηP^γ

Yield function :F(P, h) = F₀(R^a₀⁰+ P^a⁰)

γ1−γ2 a0 P^γ²

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Application:

CDA : GCRs Primary particles...

10⁰ 10¹

10⁰ 10¹ 10²

J(P,t) GV.m2.s.sr−1

Rigidity range of interest : 1.08-39.5 GV Trimmed dataset

LIS

PAMELA : [Interpolated]

AMS-02 : [Interpolated]

CDA

Rigidity, P [GV]

Credit data [Spectra]: https://tools.ssdc.asi.it/CosmicRays/ ^{5 / 12}

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Application: Extrapolation - Polar NM...

−2.0

−1.5

−1.0

−0.5

η(P,t)

χ²r=0.9589 Rd=0.7438%

1.25 1.50 1.75

γ(P,t)

χ²r=0.9456 Rd=0.2887%

2 4

ψ(P,t)

χ²r=0.2345 Rd=0.4549%

2006 2008 2010 2012 2014 2016 2018

Time [years]

50 100 JT(P,t)

χ²r=0.1217 Rd=0.0048%

Credit data [All NMs]: https://www.nmdb.eu/

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Status:

• Validated model with TEPC data

• We have to:

• Incorporate SEP spectral observations.

• Simulate the impact of the 1000 hours annual flight time limit on dose accumulation on various flight routes.

• Improve the model flexibility and weaknesses.

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Application:

Model GUI...

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Application:

Local Flight...

0 10 20 30 40 50 60 70 80

Elapsed time [minutes]

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

DoseRate,µSv/hr

A B

HARM MAIRE CARI7

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Application:

International Flight: Equator crossing...

0 100 200 300 400 500 600

Elapsed time [minutes]

0 1 2 3 4

DoseRate,uSv/hr

A B

HARMMAIRE CARI7

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HARM - CARI differences...

• The Dose Rates calculated by the HARM are systematically lower (approx. 15%) than those calculated by CARI-7.

Possible reasons include:

• CARI-7 doses are takes into account the an aircraft shielding, whereas HARM assumes values in atmosphere.

• CARI-7 uses dose conversion coefficients from ICRP Report 106 whereas HARM doses mimics the TEPC data observation.

• The origin of these difference is under investigation and this analysis will be updated as soon as possible.

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Development of the HARM model for aviation dosimetry