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[en] First measurements of natural surface and bulk 210Po specific activities for metals are reported. If covered with protective foils, the surfaces did not show indications of 210Po and the obtained upper limits are in the range of single mBq m−2. Weak bulk activities, in the range of 50 – 280 mBq kg−1, were registered for Stainless Steel and Copper, while significant amounts of 210Po, ∼1.5 Bq kg−1, were detected in Titanium. One special Teflon sample was investigated with respect to its bulk 210Po. - Highlights: • First measurements of natural Surface and bulk Po-210 specific activities for metals and Teflon. • Determination of Po-210 in copper, stainless steel and titanium. • High Po-210 in Ti found.
[en] Alpha particle spectrometry is a widely-used analytical method, in particular when we deal with pure alpha emitting radionuclides. Monte Carlo simulation is an adequate tool to investigate the influence of various phenomena on this analytical method. We performed an investigation of those phenomena using the simulation code GEANT of CERN. The results concerning the geometrical detection efficiency in different measurement geometries agree with analytical calculations. This work confirms that Monte Carlo simulation of solid angle of detection is a very useful tool to determine with very good accuracy the detection efficiency.
[en] In this work, a technique for the measurement of Pu-isotopes (''239+240 Pu and ''238Pu) activity concentration in lake sediments, by alpha spectrometry, will be shown. For the measurement was used an alpha spectrometry system with four independent ion-implanted Si detectors. This system is devoted exclusively to the Pu-isotopes measurement and, consequently, a low background level can be kept for a long time and very accurate ''238Pu/''239+240 Pu activity ratios can be determined. In our working conditions (15000 s of counting time and 25% of efficiency) the Minimum Detectable Activity (MDA) was calculated to be 0.038 mBq. Sediment samples were treated in order to isolate the plutonium present in the sample and to adequate it to the measurement conditions. Some 5-10 g of sediment sample previously dried and homogenized, were traced with ''242 Pu, also alpha emitter, and reduced to ashes. Pu-isotopes were leached with 8M HNO3 during 8 hours. Liquid phase is separated by filtration and plutonium was co-precipitated with Fe''3+ as hydroxides. Since other actinides were also co-precipitated, it was necessary to isolate the plutonium. for it, the AG1x8 anion exchange resin was used. Finally, the sample was electroplated onto a stainless steel planchet and measurement in the semiconductor detector. The radiochemical yield range was 50-90% The goodness and accuracy of the radiochemical method of measurement was corroborated in an intercomparison exercise. (Author) 11 refs
[en] We present designs of different three-dimensional (3D) sampling electromagnetic calorimeters for the AMS experiment. The proton rejection power of 3D sampling calorimeters is discussed. A shower shape analysis procedure provides a typical proton suppression factor of ∼104 for most of the designs
[en] Low-level radioactivity content in copper are employed for bolometric thermal radiation sensors and astro-nuclear spectrometers. The required lowest achievable alpha emitters concentration, for treated and untreated surfaces, are measured by Double Sided Silicon Strip Detectors in a high vacuum chamber and provide information on its intrinsic NORM content. Results shows that copper alpha emitters content can be achieved in the range below 0.01 (counts. keV-1·kg-1·y-1) adequate for specific nuclear spectrometry applications. (author)
[en] The research is one of the program which was planned by PNC (Power Reactor and Nuclear Fuel Development Corporation). In this research the analyses of the uranium series nuclide of rock samples from uranium Tono deposit, Japan have been carried out. The 17 samples were collected from Tsukiyoshi Fault, at Gallery X on Shaft 2 consist of granite, sedimentary rocks and fault area. The aim of the research is to determine the area of U accumulation, equilibrium and leaching. The samples were treated by chemical reagent, separated by ion exchange resin and extracted by organic compounds. The uranium and thorium were deposited on the stainless steel plate surface by the electrolysis process. The activity of uranium and thorium was determined by alpha spectrometer. From the analyses data have been obtained that shows that the maximum activity of 238U is 3.6798±0.1873 Bq/g, activity 234U is 3.5450±0.1805 Bq/g and activity 230Th is 3.6720±0.1868 Bq/g. The ratio figure 234U/238U versus 234U/230Th has been drawn. As the conclusion, 6 samples point (No.3, 5, 8, 11, 13 and 16) lied in or on the boundary of the uranium accumulation area, 7 samples (No. 4, 6, 9, 10, 12, 15 and 17) are very close to the equilibrium position, 4 points (No. 1, 2, 7, and 14) in the leaching process. (author)