Diamond/Si PIN α-sensor for actinides detection in water Q.T. TRAN, J. de SANOIT, M. POMORSKI, C. MER-CALFATI and P. BERGONZO quangthuan.tran@cea.fr CEA, LIST, Diamond Sensors Laboratory, F-91191 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