model-dependent deconvolution of hend neutron data by mcnpx code
DESCRIPTION
Model-dependent deconvolution of HEND neutron data by MCNPX code. M. Litvak, I. Mitrofanov, Charyshnikov, V. Grinkov, A. Kozyrev, A. Sanin V. Tret’yakov Institute for Space Research D. Drake Santa Fe, USA. MODEL. Atmosphere. CO 2 deposit. Dry regolith. Wet regolith. MODEL PARAMETERS. - PowerPoint PPT PresentationTRANSCRIPT
2001 Mars Odysseypage 1
W o r k s h o p H E N D - 2003
Institute for Space Research, June 9 - 11, 2003
Model-dependent deconvolution of Model-dependent deconvolution of HEND neutron data by MCNPX HEND neutron data by MCNPX
codecodeM. Litvak, I. Mitrofanov, Charyshnikov, V.
Grinkov, A. Kozyrev, A. Sanin V. Tret’yakov
Institute for Space ResearchD. Drake
Santa Fe, USA
2001 Mars Odysseypage 2
W o r k s h o p H E N D - 2003
Institute for Space Research, June 9 - 11, 2003
MODELMODEL
Atmosphere
CO2 deposit
Dry regolith
Wet regolith
2001 Mars Odysseypage 3
W o r k s h o p H E N D - 2003
Institute for Space Research, June 9 - 11, 2003
MODEL PARAMETERSMODEL PARAMETERS
Flux of CGR Atmosphere thickness at different times Chemical composition of atmosphere Thickness of CO2 frost Presence of water (%) in CO2 frost Thickness of dry regolith Chemical composition of regolith Presence of water (%) in dry regolith Presence of water (%) in wet regolith
2001 Mars Odysseypage 4
W o r k s h o p H E N D - 2003
Institute for Space Research, June 9 - 11, 2003
“Chemical analyses of Martian soil and rocks obtained by the Pathfinder Alpha Proton X-ray spectrometer” Radiation Physics and Chemistry 61 (2001)191 –197
MODEL PARAMETERSMODEL PARAMETERSMartian Soil
Name Na2O MgO Al2O3 SiO2 P2O5 SO3 Cl K2O CaO TiO2 Cr2O3 MnO FeO
SoilsA-2 SoilbyLander 3.1 10.3 10.0 40.9 0.9 6.0 0.7 0.5 6.1 0.8 0.3 0.5 20.0A-4 NexttoYogi 3.1 9.5 10.2 40.9 1.1 7.0 0.8 0.5 5.6 1.3 0.4 0.4 19.2A-5 DarknexttoYogi 3.8 8.4 10.0 40.5 0.5 5.7 0.8 0.5 6.1 0.7 0.5 0.2 22.2A-8 ScoobyDoo 2.4 7.6 10.2 45.4 0.5 5.6 0.9 0.9 7.1 0.9 0.1 0.3 18.2A-9 DistnexttoYogi 2.3 7.7 9.9 41.9 0.7 6.7 1.3 0.7 6.5 1.1 0.2 0.1 21.0A-10 NexttoLamb 2.5 8.8 9.4 41.0 0.6 6.4 0.9 0.4 6.0 1.0 0.3 0.4 22.4A-15 NoName 2.9 8.0 9.6 43.1 0.5 5.3 0.8 0.7 5.6 1.0 0.3 0.3 21.9RocksA-3 Barnacbill 3.4 2.5 12.2 53.5 0.7 2.0 0.5 1.2 5.7 0.7 0.1 0.4 17.3A-7 Yogi 3.6 6.2 10.9 47.2 0.5 4.5 0.9 0.8 6.6 0.9 0.1 0.4 17.8A-16 Wedge 4.3 4.8 11.0 47.5 0.5 3.0 0.7 0.8 6.9 0.9 0.0 0.3 19.3A-17 Shark 2.5 4.6 10.3 53.8 0.4 1.7 0.5 0.9 7.7 0.7 0.1 0.4 16.5A-18 Halfdome 4.3 4.0 11.7 49.2 0.5 3.0 0.7 1.0 5.9 0.9 0.1 0.4 18.5
For model 3.2 6.9 10.5 45.4 0.6 4.7 0.8 0.7 6.3 0.9 0.2 0.3 19.5
2001 Mars Odysseypage 5
W o r k s h o p H E N D - 2003
Institute for Space Research, June 9 - 11, 2003
MODEL PARAMETERSMODEL PARAMETERSMartian Atmosphere: Chemical composition and
thickness
Major gases: Carbon Dioxide (CO2) - 95.32% ;
Nitrogen (N2) - 2.7%
Argon (Ar) - 1.6%; Oxygen (O2) - 0.13%;
Carbon Monoxide (CO) - 0.08% http://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html
Thickness of atmosphere for given Mars region and season
is taken from the Ames global climate model
2001 Mars Odysseypage 6
W o r k s h o p H E N D - 2003
Institute for Space Research, June 9 - 11, 2003
HOW TO CALCULATE: HOW TO CALCULATE: GEOMETRYGEOMETRY
The layer produced the neutrons
2001 Mars Odysseypage 7
W o r k s h o p H E N D - 2003
Institute for Space Research, June 9 - 11, 2003
HOW TO CALCULATE: HOW TO CALCULATE: DATA SELECTIONDATA SELECTION
The Surface of Mars may be divided into the set of regions of interest. The properties of surface should be homogenous inside selected region The size of each region should be more than footprint.
2001 Mars Odysseypage 8
W o r k s h o p H E N D - 2003
Institute for Space Research, June 9 - 11, 2003
1. Calculation of neutron flux for model of homogeneous sphere with some initial parameters
2. Convolution of model spectra with efficiency functions for different detectors to get model counts
3. Comparison of model count rate and real count rate of HEND sensors for this Martian area of interest and for the same seasons
4. Fitting of parameters of geometry, water percentage in model of homogeneous sphere
hdry%H20dry
%H2Owet
hCO2
HOW TO CALCULATE: HOW TO CALCULATE: ALGORITHMALGORITHM
2001 Mars Odysseypage 9
W o r k s h o p H E N D - 2003
Institute for Space Research, June 9 - 11, 2003
HOW TO CALCULATE: MINIMIZATIONHOW TO CALCULATE: MINIMIZATION
Search of model best fit parameters based on 2 minimization:
i
ii
ii MCS
22
22value ~
Where: Ci is detector counts, i=1,5 (SD,MD,LD,SC1,SC2). Mi is model counts predicted by MCNPX for (SD,MD,LD,SC1,SC2). i is statistical error for Ci, Mi
SD, MD, LD are integral counts detected in proportional countersSC1 is fast neutron counts in energy range (0.8-2.5 MeV) registered in stilbenSC2 is fast neutron counts in energy range >2.5 MeV registered in stilben
2001 Mars Odysseypage 10
W o r k s h o p H E N D - 2003
Institute for Space Research, June 9 - 11, 2003
BEST FIT PARAMETERS: CGR fluxBEST FIT PARAMETERS: CGR flux
The selection of HEND data accumulated above large region near Solis Planum. It is driest place on Mars where variation of neutron flux explained only by variations of CGR flux or by Solar activity.
The selection of different time intervals: Ls={ [330o-360o] , [0o -30o ] ,[30o -60o] , [60o-90o], [90o-120o] , [120o-150o]
Applying of the homogenous model to estimate flux of CGR: {Atmosphere +homogenous regolith layer with 2% of water}
2001 Mars Odysseypage 11
W o r k s h o p H E N D - 2003
Institute for Space Research, June 9 - 11, 2003
BEST FIT PARAMETERS: FROST FREE BEST FIT PARAMETERS: FROST FREE AREASAREAS
The selection of data for summer surface of Mars (season when CO2 frost is absent) First step:Applying of the homogeneous regolith model with one freeparameter describing content of water in the regolith. Second step: If homogeneous model was rejected two layers regolith model should be tested with 2% of water in upper layer and two free parameters: thickness of upper layer and water content inbottom layer.
2001 Mars Odysseypage 12
W o r k s h o p H E N D - 2003
Institute for Space Research, June 9 - 11, 2003
The best fitting parameters describing summer surface are fixed for given region.
The data for given region are taken for different winter periods of time.
The real data are fitted by model of summer surface with added layer of CO2 frost with variable thickness.
BEST FIT PARAMETERS: COBEST FIT PARAMETERS: CO22 FROST FROST
THICKNESSTHICKNESS