1. Diamond/Si PIN α-sensor for actinides detection in water
Q.T. TRAN, J. de SANOIT, M. POMORSKI, C. MER-CALFATI and P. BERGONZO
CEA, LIST, Diamond Sensors Laboratory, F Gif-sur-Yvette, France
[1] de Sanoit* et al. French Patent #105815, Oct. 7,2010
Introduction
Alpha-particle detection is challenching issue due to their self-absorption properties in liquid media e.g. few tens micrometer of liquid. We have described a novel sensor based on diamond/Si PIN diode enabling to directly probe alpha-particle radioactivity in aqueous liquid media [1].
Nuclear industry or nuclear accident (e.g. Chernobyl 1986 and Fukushima 2011) generate non negligible amount of radioactive sources in the environment. Among of radionuclides, actinides (Pu-239, Am-241, Cm-244, etc.) are very hazardous due to their radiation emission and chemical toxicity, and more than their long half-life to hundreds thousands years. In natural water, the most relevant alpha-radioactivity come from the isotopes of uranium (U-234, and U-238).
This work aims at studying the performance of our sensor for actinide trace detection in water.
Sensor structure
 Amplifier
0-50V
Metallic contact (e.g. Al, Au)
B-NCD electrode
i Si
p Si
n Si
Particle α
e drift
Actinides
Protecting resin
GND
MCA PC
 Preamplifier
Direct detection in solutions
Electrochemical process
Analyzed solution
Actinides were collected onto the diamond electrode using precipitation with hydroxyl electrochemically generated from nitrate reduction. Operational condition was previously optimised elsewhere [2].
Actinides
Electrochemical collection
Measuring
B-NCD/SI PIN sensor
0.3M NaNO3, pH = 3, I = - 3 mA/cm2, V = 15 mL, T = 90 min
[2] J. de Sanoit* et al. J. Appl. Radiat. Isot., 80 (2013) 32-41
[3] Q.T. Tran* et al. IEEE, Trans. Nucl. Sci., Accepted
Sensor performance
Linearity  high reliability method
Sensor cleaning
Cleaning efficiency > 99.9 %
Spectroscopic stability
No change of peak  high stability
Actinides detection
Actinides + Uranium detection
Deposited (Bq)
Efficacity (%)
U-238 (2.90 Bq)
0.50 17
U-234 (2.90 Bq)
0.49
Pu-239 (5.13 Bq)
1.42 28
Am-241 (5.96 Bq)
1.86 31
Cm-244 (4.40 Bq)
0.72 16
Deposited (Bq)
Efficacity (%)
Pu-239 (5.13 Bq)
1.22 24
Am-241 (5.96 Bq)
2.30 38
Cm-244 (4.40 Bq)
1.61 37
Conclusion
Fabrication of an innovative detector based diamond/silicon PIN for direct alpha-particle detection in solution
Sensor could be reused after a fast cleaning with high decontamination efficiency > 99.9 %
Sensor displayed very high stability due to the protection of diamond electrode highly robust layer
Radioactivity was analyzed and identified from deconvoluted spectrum using COLEGRAM software developed by Henry Becquerel National Laboratory, CEA, Saclay
Actinides identification (Pu-239, Am-241 and Cm-244) and also toward U natural isotope