2001 Mars Odyssey GRS 1 Workshop HEND - 2002 May 20 th – 22 nd 2002 Chemical elements preliminary mapping Early Mapping of Hydrogen, Potassium and Silicon.

2001 Mars Odyssey GRS1

Workshop HEND - 2002May 20th – 22nd 2002

Chemical elements preliminary mapping

Early Mapping of Hydrogen,Potassium and Siliconfrom the Gamma lines

L. d’Uston, S. Maurice, O. Gasnault




8

104

2

3

4

5

678

105

2

3

4

5

678

106

2

3

4

Cou

nts

per

Cha

nnel

1400keV12001000800600400200Energy (keV)

#075m

Ge76

Ge(p,p'n)132.68 #1

46mSc

136.00

#265

Ga(spal)

~153.60

#371

As72

Ge(p,2n)181.52

#467

Ga70

Ge(p,a)190.39

#571m

Ge72

Ge(p,p'n)194.43

#6212

Pb235.75

#744m

Sc(spal)

269.56

#8214

Pb294.18

#967

Ga70

Ge(p,a)308.91

#10228

Ac337.10

#11214

Pb350.56

#1243

K43

Sc372.29

#1367

Ga70

Ge(p,a)402.69

#1423

Na69m

Zn(n,ng);spal

438.87

#1523

Mg450.71

#1624m

Na472.24

#177Be

(spal)477.17

#18annih

511.00

#1969

Ge70

Ge(p,p'n)584.02

#2074

Ge74

As(SAW)~598.00

#21214

Bi608.71

#2243

K617.39

#2663

Cu670.77

#2772

Ge72

Ge(n,n')~693.00

#2810

B719.02

#2958

Co(spal)

811.24

#3058

Co(spal)

817.97

#3172

Ge(SAW)~835.50

#3227

Al(843.8)27

Mg(844.01)56

Fe(846.7)~843.60

#3369

Ge70

Ge(p,p'n)882.65

#3446

Ti46

Sc889.55

#35228

Ac910.98

#3763

Cu962.50

#38228

Ac969.26

#3925

Mg974.81

#4048

Ti48

V48

Sc(n,ng)983.72

#4227

Al1014.65

#4345

Ar1021.10

#4448

Sc1038.20

#4566

Ga70

Ge(n,na)1048.95

#4668

Ga72

Ge(p,na)1087.00

#4769

Ge1107.00

#4869

Ge70

Ge(p,p'n)1117.70

#5065

Zn(Spal)

1124.50

#5144

Sc(Spal)

1157.00

#5260

Co1173.12

#5422

Na22

Ne1274.44

#5548

Ti48

V48

Sc1312.29

#5660

Co1332.94

#5769

Ge1346.68

#5824

MgAl

24Na

(n,ng)1368.58

#5952m

Mn(Spal)

~1434.30

#6040

K1460.78




Gammas

Raw data from Query Tool (gammaspatial + engineering)

Time selection: Feb 20 – March 9

before annealing

Temperature selection: GRS_IS_TEMP_A < -165oC

2 weeks

55,972 spectra (~304 hours)

Neutrons

Press release data from W. Feldman & R. Tokar

Data sets







0.8

0.6

0.4

0.2

Cou

nts

/ min

/ ke

V

235023002250220021502100Energy (keV)

North (raw, >+75º)

South (bkg corrected, < -60º)

Middle (bkg corrected, > -60º, < +75º)

Al (2210)

H (2223)




Energy callibration [W. Boyton, Feb 02]

Slope = 0.6152 keV/channel

Intercept = 18.86 keV

2.4 MeV

2.0 MeV

Continuum H-line

Background

2.215 – 2.230 MeV

Spectral Analysis

Energy

(cou

nts/

19.6

sec

)




Min = 530 spectra

Mapping at 30o resolution (equal area)

(8)

(12)

(8)

(15)(12)

Application of the

Mapping/Display Toolkit




Map of background




Above +45o

Below –45o

Effects of atmospheric Absoption

Background with MOLA




Map of background (corrected for 0 km MOLA altitude)

(same color range)




Map above continuum H-LINE map




Map of H-line (corrected for 0 km MOLA altitude)




Smooth 4o

Epithermal neutrons [Press release data]

! Arb. Units = constant - epithermals !




Epithermal neutrons: Rebin to 30o




Correlation epithermals/gammas (1)




Correlation epithermals/gammas (2)




• Map of HYDROGEN is feasible; it makes sense…

• Map of BACKGROUND:– Correlated with altitude (atmospheric effect)

– Corrected map shows signal at poles

• Agreement between epithermal neutrons & gamma H-line:– Very good at first order

– Strenghten epithermal detection of H

– Differences have not been interpreted

Conclusions

• Quantify statistical significance per pixel

• Increase surface resolution of gamma’s (15o by early May – 8o at poles)

• Use better epithermal map

• Incorporate HEND data ?

• Improve spectral analysis (norm to thermals / line fit…)

• Quantify gamma H-line Quantification of abundances

Future Developments




0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

90N_60N 60N_30N 30N_00N 00S_30S 30S_60S 60S_90S

Co

un

ts p

er

Min

ute Mg 1369 keV

Ti 1382 keV

K 1461 keV

H 2223 keV

Si 1779 keV

Fe 7132 keV

Fe 847 keV




K line (1.461 MeV) underlying continuum versus MOLA altitude

Slope = 0.05 C/dt*km

Offset =4.045 C/dt




Si line (1.779 MeV) underlying continuum versus MOLA altitude

Slope = 0.032C/dt*km

Offset = 2.885C/dt










Slope E-1.6

Atmospheric correction

I(h,E) = I0 exp (-α. g)

¤ α (E) attenuation coefficient in cm2/g

¤ g (h) optical thickness

in g/cm2

Using

ρ(h)= ρ0 exp (-h/10.8)




• Atmospheric transmission:

I(h,E) = I0 exp (-α. g)

g (h) optical thickness in g/cm2

α (E) attenuation coefficient in cm2/g

2001 Mars Odyssey GRS 1 Workshop HEND - 2002 May 20 th – 22 nd 2002 Chemical elements preliminary mapping Early Mapping of Hydrogen, Potassium and Silicon.

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