GERDA meeting Dubna 27-29/06/2005

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GERDA meeting Dubna 27-29/06/2005

Natural Ge crystal contamination measurement
and Isotopic ratio determination by ICP-MS
LNGS Chemistry Service S. Nisi
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Analysis method

• Ge crystal dissolution HNO3HFH2O 111
• Dilution of samples and spiked samples
  preparation to check the procedure
• Measurement of contamination and isotopic ratio
  by ICP-MS Agilent Technologies model 7500a
  (quadrupole mass analyzer)

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ICP-MS in the clean room at LNGS
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Interference on contamination measurement
Element Interference Element Interference
11B 10B1H, 22Ne N Air
27Al 31P 15N16O, 30Si1H
69Ga 71Ga 70Ge1H 75As 74Ge1H
113In 115In 73Ge40Ar 121Sb
205Tl 209Bi

232Th 238U
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Ge93 13196 contamination results
Ge93 13196 Spike Ge93 13196 Spike
Element Ge93 13196 ppm Spike conc ppm Meas. Conc ppm
11B lt0,01   lt0,01
27Al 0,27 0,2 0,32
31P lt2 16,5  
39K lt5 42 34
69Ga 0,034   0,032
115In 0,014   0,1
121Sb 0,001 0,01 0,025
205Tl lt0,0021 0,01 0,0089
209Bi lt0,0019   lt0,0018
232Th lt0,0016 0,01 0,0089
238U lt0,0015 0,01 0,0092
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Ge124 11888 contamination results
Ge124 11888 Spike Ge124 11888 Spike
Element Ge124 11888 ppm Spike conc ppm Meas. Conc ppm
11B lt0,01   lt0,01
27Al 0,22 0,2 0,35
31P lt2 16,5  
39K lt5 42 33
69Ga 0,031   0,033
115In 0,0038   0,13
121Sb 0,0013 0,01 0,009
205Tl lt0,0019 0,01 0,0093
209Bi lt0,0016   lt0,0018
232Th lt0,0014 0,01 0,009
238U lt0,0013 0,01 0,0096
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Ge crystal contamination comparison
Element nat Ge X8 ppm Ge93 13196 ppm Ge12411888 ppm
11B lt0,01 lt0,01 lt0,01
27Al 0,32 0,27 0,22
31P lt2 lt2 lt2
39K lt5 lt5 lt5
69Ga 0,039 0,034 0,031
115In 0,006 0,014 0,0038
121Sb 0,0036 0,001 0,0013
205Tl lt0,0021 lt0,0021 lt0,0019
209Bi lt0,0018 lt0,0019 lt0,0016
232Th lt0,0015 lt0,0016 lt0,0014
238U lt0,0014 lt0,0015 lt0,0013
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Ge isotopic measurement for GNO
Ge70 Ge72 Ge73 Ge74 Ge76
Carrier 70Ge 96,47 96,784 1,14 1,090 0,35 0,320 1,46 1,316 0,57 0,490
Carrier 72Ge 0,36 0,355 98,54 98,609 0,23 0,223 0,73 0,683 0,14 0,129
Carrier 74Ge 0,42 0,444 0,64 0,639 0,23 0,230 98,5 98,486 0,21 0,201
BLUE VALUELNGS measure carried out by ICP-MS
(quadrupole mass analyzer) RED VALUEMC-ICP-MS
(double focusing-multicollector) carried out from
ITU of JRC Karlsrhue
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Ge crystal isotopic ratio measurement
GeX8 Ge93 13196 Ge124 11888
70Ge 19,08/-0,10 19,14 /-0,07 19,18 /-0,09
72Ge 27,00 /-0,13 26,95 /-0,14 26,80 /-0,09
73Ge 7,81 /-0,04 7,76 /-0,04 7,82 /-0,07
74Ge 37,58 /-0,21 37,63 /-0,13 37,61 /-0,24
76Ge 8,53 /-0,10 8,52 /-0,05 8,59 /-0,05
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Conclusion

• Concerning the contamination measurement of Ge
  crystal could be possible a little improvement
  (2or3 factor) of the sensitivity for some
  elements but we are close to the DL
• About the isotopic composition will be possible
  measure the enriched crystal with the same
  accuracy and precision