Beryllium sources

Bowden and Singh (Refs 8 35) utilized a radioactive antimony-beryllium source with a slow neutron flux of about 106 neutrons/ cm2/sec and the cyclotron at Cavendish Laboratory for fluxes up to 3 x 108n/cm2/sec. The primary expls listed in Table 1 were irradiated for one hour so that the maximum total slow neutron dose was 1.08 x 1012 neutron/cm2. The results show that in most cases a large number of high-velocity recoil atoms are formed on the irradiation of these expls with slow neutrons. In no case did any of the expls deto-... 

Argonne National Laboratory. Beryllium Human Health Fact Sheet. Available online. URL www.ead.anl.gov/pub/doc/ beryllium.pdf. Accessed on June 23, 2009. Human health fact sheet contains details on beryllium sources, uses, and human health risks. 

The Virus House was finished in October. Besides a laboratory the structure contained a special brick-lined pit, six feet deep, a variant of Fermi s water tank for neutron-multiplication studies. By December Heisenberg and von WeizsScker had prepared the first of several such experiments. With water in the pit to serve as both reflector and radiation shield they lowered down a large aluminum canister packed with alternating layers of uranium oxide and paraffin. A radium-beryllium source in the center of the canister supplied neutrons, but the German physicists were able to measure no neutron multiplication at all. The experiment confirmed what Fermi and Szilard had already demonstrated that ordinary hydrogen, whether in the form of water or paraffin, would not work with natural uranium to sustain a chain reaction. 

Neutron activation analysis (NAA) came into being in 1936 when George von Hevesy and Hilde Levi published a new principle [3] for making analysis A sample was exposed to a stream of neutrons from a radium-beryllium source, and some of the atoms in the sample captured a neutron in their nucleus and became radioactive the composition of the sample could now be inferred from the measurement of the amounts and properties of such radioactive indicators. 

It was this commercial market that made the filling operation at Port Hope necessary. To serve private-sector customers, Eldorado had to offer them radium in a form that they could use. The filling lab prepared radium for its primary medical market by packing it in needles, moulds, or tubes in precise quantities. Gradually Errington developed an extensive line of other radium products to serve a wide variety of customer needs. One example was radium-beryllium sources for well-lo ng in the oil business. Companies servicing the mining sector used this technique to determine if there were oil reserves in the vicinity of a dry drill hole. Radium combined with beryllium in the proper ratio produces millions of neutrons a second. This neutron source could be lowered down... 

Some of CPDs R D projects in the 1950s stemmed from its experience in the radium business. One project arose out of CPDs relationship with Well Surveys Inc., its best customer for neutron sources for well-lo ji. In the early 1950s, Well Surveys asked if CPD could produce an actinium-beryllium mixmre with a much higher level ofneutron emissions than the standard radium-beryllium source. Actinium was produced by irradiating radium it then had to he separated from the radium, mixed with beryllium, and loaded in a source capsule. Errington considered this project to have as much potential as the beam-therapy program. By 1955 he was expecting to have a product... 

The source used in this part is a Plutonium-Beryllium source. The Pu and Be are alloyed together so the alphas from Pu can bombard Be and produce fast neutrons. There is some gamma radiation given off by the source, too. 

Two things to be noted about an antimony-beryllium source are that it is built up at power by the nuetron-antimony-123 reaction and it has a relatively short half life, Initial fueling must be completed before the neutron source decays or it will have to be removed from the reactor, irradiated at a test facility, and returned to the core before startup can take place. 

The foil stringers are placed in their respective positions in the pile. The antimony-beryllium source is then inserted into the graphite pedestal. The insertion time should be noted on the data sheet. 

New metliods appear regularly. The principal challenges to the ingenuity of the spectroscopist are availability of appropriate radiation sources, absorption or distortion of the radiation by the windows and other components of the high-pressure cells, and small samples. Lasers and synchrotron radiation sources are especially valuable, and use of beryllium gaskets for diamond-anvil cells will open new applications. Impulse-stimulated Brillouin [75], coherent anti-Stokes Raman [76, 77], picosecond kinetics of shocked materials [78], visible circular and x-ray magnetic circular dicliroism [79, 80] and x-ray emission [72] are but a few recent spectroscopic developments in static and dynamic high-pressure research. 

Beryllium is found in some 30 mineral species, the most important of which are bertrandite, beryl, chrysoberyl, and phenacite. Aquamarine and emerald are precious forms of beryl. Beryl and bertrandite are the most important commercial sources of the element and its compounds. Most of the metal is now prepared by reducing beryllium fluoride with magnesium metal. Beryllium metal did not become readily available to industry until 1957. 

Polonium can be mixed or alloyed with beryllium to provide a source of neutrons. The element has been used in devices for eliminating static charges in textile mills, etc. however, beta sources are both more commonly used and less dangerous. It is also used on brushes for removing dust from photographic films. The polonium for these is carefully sealed and controlled, minimizing hazards to the user. 

Beryllium has a high x-ray permeabiUty approximately seventeen times greater than that of aluminum. Natural beryUium contains 100% of the Be isotope. The principal isotopes and respective half-life are Be, 0.4 s Be, 53 d Be, 10 5 Be, stable Be, 2.5 x 10 yr. Beryllium can serve as a neutron source through either the (Oi,n) or (n,2n) reactions. Beryllium has alow (9 x 10 ° m°) absorption cross-section and a high (6 x 10 ° m°) scatter cross-section for thermal neutrons making it useful as a moderator and reflector in nuclear reactors (qv). Such appHcation has been limited, however, because of gas-producing reactions and the reactivity of beryUium toward high temperature water. 

For the neutron porosity measurement, fast neutrons are emitted from a 7.5-curie (Ci) americium-beryllium (Am-Be) source. The quantities of hydrogen in the formation, in the form of water or oil-filled porosity as well as crystallization water in the rock if any, primarily control the rate at which the neutrons slow down to epithermal and thermal energies. Neutrons are detected in near- and far-spacing detectors, located laterally above the source. Ratio processing is used for borehole compensation. 

Beryllium is extracted from the main source mineral, the alumino-silicate beryl, by conversion to the hydroxide and then through either the fluoride or the chloride to the final metal. If the fluoride is used, it is reduced to beryllium by magnesium by a Kroll-type reaction. The raw metal takes the form of pebble and contains much residual halides and magnesium. With the chloride on the other hand, the pure metal is extracted by electrolysis of a mixture of fused beryllium chloride and sodium chloride. The raw beryllium is now dendritic in character, but still contains residual chloride. 

Boron, a metalloid with largely nonmetallic properties, has acidic oxides. Aluminum, its metallic neighbor, has amphoteric oxides (like its diagonal neighbor in Group 2, beryllium). The oxides of both elements are important in their own right, as sources of the elements, and as the starting point for the manufacture of other compounds. 

Figure 3.1 James Chadwick used the apparatus depicted above to discover the neutron. The poionium source emits alpha (a) particles. The particles strike a sample of beryllium, resulting in the emission of a neutron (n ). The ejected neutrons hit the target material—paraffin, for instance—and eject a proton that is recorded by the detection device.

Minerals belonging to the category of insoluble oxide and silicate minerals are many in number. Insoluble oxide minerals include those superficially oxidized and those of oxide type. The former category comprises mainly superficially oxidized sulfide minerals, including metals such as aluminum, tin, manganese, and iron which are won from their oxidic sources. As far as silicate minerals are concerned, there can be a ready reference to several metals such as beryllium, lithium, titanium, zirconium, and niobium which are known for their occurrence as (or are associated with) complex silicates in relatively low-grade deposits. 

Soft, silver white metal that is isolated in the tiniest of amounts. All isotopes are radioactive, the longest-lived has a half-life of 22 years. The element is an intermediate in the decay series of 235U. Strong alpha emitter that is used in radioactivation analysis and forms an effective neutron source with beryllium. 

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