Alpha particle method

Combination of the sealed tube accelerator and the associated alpha-particle method (ARM)... 

Glenn Theodore Seaborg (1912-1999), together with Ralph A. James and Albert Ghiorso J ( 1915). Irradiation of a plutonium-239 sample with alpha particles and enrichment of 242Cu by chemical methods. 

Flow-Type Ionization Chamber (PFC). The Flow -Type Ionization Chamber Method (PFC) has been developed for continuously measuring radon gas in the atmospheric air. The detail of the device has been described elsewhere (Shimo, 1985). Briefly, measurements are continuously carried out by drawing air through the detector at 1.0 2.0 /min. The ionization currentdue to alpha particles from radon and its daughters is detected with a vibrating reed electrometer (VRE) in the same manner as the DSC. The sensitivity... 

In order to determine the efficiency of the screens, the front-to-back ratio (F/B) of activities and a loss factor (SL) by which one multiplies to correct for loss in the screens (the alpha particles absorbed in a screen that cannot be detected either during the front or back measurements, see figure 1) have to be determined. Experimentally, this was accomplished by two methods ... 

Dosimetric Studies. The main objective of Rn-d dosimetry is to enable the assessment of the observed dose from Rn-d deposited in the respiratory tract from measured Rn-d concentration in the atmosphere. As a consequence of an inhomogeneous Rn-d deposition within the lung, different dosimetric concepts have been developed to describe either regional mean dose values (e.g. for tracheobronchial or pulmonary region) or microdosimetric dose calculations (e.g. for the basal cell layer). Using Monte Carlo calculation methods it is also possible to account for the random nature of cellular hits by deposited alpha particles. The results of such dosimetric calculations should provide the following information needed for Rn-d risk assessment ... 

In vivo the doses are always not only due to internal alpha but also due to the external gamma irradiation, which must be taken into account, especially in the low dose range. Therefore in vitro experiments with alpha particles of radon daughters at doses comparable to the in vivo investigations have been carried out (0.05 to 3 mGy). The method is described. Preliminary results show similar dose response as at our in vivo studies. 

Another method for detecting neutrons using an ionization chamber is to use the gas boron trifluoride (BF3) instead of air in the chamber. The incoming neutrons produce alpha particles when they react with the boron atoms in the detector gas. Either method may be used to detect neutrons in nuclear reactor neutron detectors. 

Rutherford, E. and Geiger, H. (1908). An electrical method of counting the number of alpha particles from radioactive substances. Proceedings of the Royal Society A81 141-161. 

Neutron depth profiling technique (NDP) [13]. NDP is a speeial method for depth profiling of few light elements, namely He, Li, B and N in any solid material. The method makes use of speeifie nuelear reaetions of these elements with thermal neutrons. The samples are plaeed in the neutron beam from nuclear reactor and the charged products of the neutron indueed reactions (protons or alpha particles) are registered using a standard multiehannel spectrometer. From the measured energy spectra the depth profiles of above mentioned elements can be deduced by a simple computational procedure. 

Curium can be synthesized in a nuclear reactor by several methods. The first synthesis involved alpha particle bombardment of plutonium-239 ... 

Gross alpha and gross beta activity can be determined by various radioactive counters, such as internal proportional, alpha scintillation, and Geiger counters. Radium in water can be measured by co-precipitating with barium sulfate followed by counting alpha particles. Radium-226 can be measured from alpha counting of radon-222. Various methods are well documented (APHA, AWWA, and WEF 1998. Standard Methods for the Examination of Water and Wastewater, 20 ed. Washington DC American Public Health Association). 

Radioactivity of uranium can be measured by alpha counters. The metal is digested in nitric acid. Alpha activity is measured by a counting instrument, such as an alpha scintillation counter or gas-flow proportional counter. Uranium may be separated from the other radioactive substances by radiochemical methods. The metal or its compound(s) is first dissolved. Uranium is coprecipitated with ferric hydroxide. Precipitate is dissolved in an acid and the solution passed through an anion exchange column. Uranium is eluted with dilute hydrochloric acid. The solution is evaporated to near dryness. Uranium is converted to its nitrate and alpha activity is counted. Alternatively, uranium is separated and electrodeposited onto a stainless steel disk and alpha particles counted by alpha pulse height analysis using a silicon surface barrier detector, a semiconductor particle-type detector. 

Professor of physics at MoGill, Manchester, and Cambridge Universities. He identified the three types of radiations from radioactive substances, and devised methods for counting alpha particles and for determining the number of free positive electrons in the nucleus of an atom. 

Beginning in 1922 she published a long series of excellent researches on polonium, in which she determined the velocity of its alpha-rays and the distribution of their lengths, and observed their ionizing power, the oscillations in their paths, and the homogeneity of their initial velocity. In 1923 she used an original method to determine the range in air of its alpha-particles. 

Self-heating, due to the stoppage of the alpha particles within the solid, is a well known phenomenon and calculation shows that the energy release from one gram of polonium metal would be about 140 watts. This high energy output affords a useful and absolute method for the rapid determination of polonium in large sources by calorimetry. 

It can be seen that students can easily balance and complete nuclear equations if they are familiar with the symbols for nuclear particles and know the method of nuclear decay, such as alpha particle emission or electron capture. 

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