Neutron multiplicity counter

Macklin, R. L.; Glass, F. M.; Halperin, J.; Roseberry, R.T.; Schmitt, H.W.; Stoughton, R. W.; Tobias, M.L.

doi:10.1016/0029-554x(72)90537-x

Cited by 21 publications

(3 citation statements)

References 12 publications

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“…This advantage is partially offset by a lower neutron detection efficiency which typically has ranged up to ~50 ~o for counter systems used in such studies. The neutron multiplicity counter used here has previously been described [9] and only a brief description will be given. The fission neutrons were detected with an array of 30 3He proportional counters in a cylindrical matrix of paraffin and polyethylene moderator (0.54m in diameter and 0.90m long).…”

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confidence: 99%

Search for spontaneous fission emitters in Atlantis II (Part I)

et al. 1981

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No evidence for spontaneous fission decay (and the implied presence of superheavy nuclides) has been found in a several kilogram precipitate gathered at the Atlantis-II site in the Red Sea. The sample was investigated with a neutron multiplicity counter non-destructively so that no chemical losses should have been sustained. Upper limits have been determined for possible superheavy element concentrations in the sample.In a recent study of hot brines from the Cheleken Penninsula, Flerov and co-workers [1, 2] report observations of spontaneous fission activities. These results have led them to conclude that the most likely interpretation of their observation is the existence of a new naturally occurring isotope of a superheavy element. These reports have stimulated investigations into other hot brines which might provide evidence on this extraordinarily interesting point. We have examined material derived from hot springs at the bottom of the Red Sea (Atlantis-II) [3][4][5] which may be anticipated to have a similar geologic origin as the samples derived from the Cheleken Penninsula. We have examined in a neutron-multiplicity counter several kilograms of dry precipitate gathered from the Atlantis II site, which are relatively rich in some of the more volatile heavy elements. The material was examined essentially as collected without recourse to either physical or chemical separations, eliminating the possibility of loss of any original constituent in the sample. In view of the fact that the range of lifetimes theoretically estimated [6,7] for superheavy nuclides encompasses half-lives as great as the age of the planet, geologic samples may be considered as possible sources for such nuclides. Spontaneous fission decay is expected to result from superheavy * Research sponsored in part by the Division of Nuclear Sciences, Office of Basic Energy Sciences, U.S. Department of Energy, under contract (W-7405-eng-26) with Union Carbide Corporation nuclides, either directly or secondary from daughters formed by alpha or beta decay. Since the only nuclide of any consequence ordinarily found in nature that exhibits spontaneous fission decay is 238U(T1/2(S.F.)=8.2x101Syr, ~=2.0), the observation of such activity (in natural samples and in the absence of uranium) raises the possibility of superheavy element decay. Such a conclusion of course can only be made with the further provision that the measurement not be contaminated with transuranic element sources. Neutron emission is ordinarily associated with spontaneous fission decay. Theoretical predictions [8] for the range of the parameter ~, the average number of neutrons emitted per fission, extend to perhaps 10 or more for superheavy nuclides. The largest value of ~ for known nuclides at most only slightly exceeds 4; so that any observation of spontaneous fission characterized by a value of ~ appreciably in excess of 4 would support the inference of superheavy element decay. Large multikilogram samples may conveniently be examined nondestructively for evidence of spontaneous f...

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confidence: 99%

Search for spontaneous fission emitters in Atlantis II (Part I)

et al. 1981

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“…The sensitivity of neutron counting can be improved by looking for multiple neutron emission with large detectors operated below ground. Such set-ups were built by Ter-Akopyan et al [7] and by Macklin et al [8]. The counter of the latter group is shown in Fig.…”

Section: Methods Used In the Search For Superheavy Elementsmentioning

confidence: 99%

“…Isometric view of a neutron multiplicity counter for selective detection of superheavy nuclides. From Macklin et al[8].Physica Scripta IO A…”

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confidence: 99%