GERDA meeting Dubna 27-29/06/2005

LNGS Chemistry Service S. Nisi

Natural Ge crystal contamination measurement and Isotopic ratio

determination by ICP-MS

Analysis method

• Ge crystal dissolution HNO3+HF+H2O 1:1:1

• 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)

ICP-MS in the clean room at LNGS

Interference on contamination measurement

ElementInterferenc

eElement

Interference

11B 10B1H, 22Ne++ N Air

27Al 31P15N16O, 30Si1H

69Ga71Ga 70Ge1H

75As 74Ge1H

113In115In

73Ge40Ar121Sb

205Tl 209Bi

232Th 238U

Ge93 13196 contamination resultsGe93 13196 Spike

Element Ge93 13196ppm

Spike conc ppm

Meas. Conc ppm

11B <0,01   <0,0127Al 0,27 0,2 0,32

31P <2 16,5  39K <5 42 34

69Ga 0,034   0,032115In 0,014   0,1

121Sb 0,001 0,01 0,025205Tl <0,0021 0,01 0,0089209Bi <0,0019   <0,0018232Th <0,0016 0,01 0,0089238U <0,0015 0,01 0,0092

Ge124 11888 contamination results

Ge124 11888 Spike

Element Ge124 11888ppm

Spike conc ppm

Meas. Conc ppm

11B <0,01   <0,0127Al 0,22 0,2 0,3531P <2 16,5  39K <5 42 33

69Ga 0,031   0,033115In 0,0038   0,13

121Sb 0,0013 0,01 0,009205Tl <0,0019 0,01 0,0093209Bi <0,0016   <0,0018232Th <0,0014 0,01 0,009238U <0,0013 0,01 0,0096

Ge crystal contamination comparison

Element nat Ge X8ppm

Ge93 13196 ppm

Ge12411888

ppm11B <0,01 <0,01 <0,01

27Al 0,32 0,27 0,2231P <2 <2 <239K <5 <5 <5

69Ga 0,039 0,034 0,031115In 0,006 0,014 0,0038

121Sb 0,0036 0,001 0,0013205Tl <0,0021 <0,0021 <0,0019209Bi <0,0018 <0,0019 <0,0016232Th <0,0015 <0,0016 <0,0014238U <0,0014 <0,0015 <0,0013

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 VALUE=LNGS measure carried out by ICP-MS (quadrupole mass analyzer)RED VALUE=MC-ICP-MS (double focusing-multicollector) carried out from ITU of JRC Karlsrhue

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

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