Discovery of zinc, selenium, bromine, and neodymium isotopes
Introduction
The discovery of zinc, selenium, bromine, and neodymium isotopes is described as part of the series summarizing the discovery of isotopes, beginning with the cerium isotopes in 2009 [1]. Guidelines for assigning credit for discovery are (1) clear identification, either through decay-curves and relationships to other known isotopes, particle or -ray spectra, or unique mass and -identification, and (2) publication of the discovery in a refereed journal. The authors and year of the first publication, the laboratory where the isotopes were produced as well as the production and identification methods are summarized. When appropriate, references to conference proceedings, internal reports, and theses are included. When a discovery includes a half-life measurement the measured value is compared to the currently adopted value taken from the NUBASE evaluation [2], which is based on the ENSDF database [3]. In cases where the reported half-life differed significantly from the adopted half-life (up to approximately a factor of two), we searched the subsequent literature for indications that the measurement was erroneous. If that was not the case we credited the authors with the discovery in spite of the inaccurate half-life.
The first criterium excludes measurements of half-lives of a given element without mass identification. This affects mostly isotopes first observed in fission where decay curves of chemically separated elements were measured without the capability to determine their mass. Also the four-parameter measurements (see, for example, Ref. [4]) were, in general, not considered because the mass identification was only mass unit.
The second criterium affects especially the isotopes studied within the Manhattan Project. Although an overview of the results was published in 1946 [5], most of the papers were only published in 1951 by Wiley in the Plutonium Project Records of the Manhattan Project Technical Series, Vol. 9A, Radiochemistry and the Fission Products, in three books [6]. We considered this first unclassified publication to be equivalent to a refereed paper.
The initial literature search was performed using the databases ENSDF [3] and NSR [7] of the National Nuclear Data Center at Brookhaven National Laboratory. These databases are complete and reliable back to the early 1960’s. For earlier references, several editions of the Table of Isotopes were used [8], [9], [10], [11], [12], [13]. A good reference for the discovery of the stable isotopes was the second edition of Aston’s book “Mass Spectra and Isotopes” [14].
Section snippets
Discovery of 54–85Zn
Thirty-two zinc isotopes from have been discovered so far; these include 5 stable, 11 neutron-deficient, and 16 neutron-rich isotopes. According to the HFB-14 model [15], 93Zn should be the last odd–even particle stable neutron-rich nucleus while the even–even particle stable neutron-rich nuclei should continue through 106Zn. The proton drip line has been reached at 54Zn, but 53Zn could live long enough to be observed [16]. About 16 isotopes have yet to be discovered corresponding to
Discovery of 64–95Se
Thirty-two selenium isotopes from have been discovered so far; these include 6 stable, 11 proton-rich, and 15 neutron-rich isotopes. According to the HFB-14 model [15], 111Se should be the last odd–even particle stable neutron-rich nucleus while the even–even particle stable neutron-rich nuclei should continue through 118Se. At the proton drip line 62Se and 63Se could still be particle stable and 61Se could live long enough to be observed [16]. About 23 isotopes have yet to be
Discovery of 70–98Br
Twenty-nine bromine isotopes from have been discovered so far; these include 2 stable, 10 proton-rich, and 17 neutron-rich isotopes. According to the HFB-14 model [15], 116Br should be the last odd–odd particle stable neutron-rich nucleus while the odd–even particle stable neutron-rich nuclei should continue through 119Br. The proton drip line has been reached and no more long-lived isotopes are expected to exist because 69Br has been shown to be unbound with a half-life of less than
Discovery of 125–156Nd
Thirty-one neodymium isotopes from have been discovered so far; these include 7 stable, 16 proton-rich, and 8 neutron-rich isotopes. 126Nd, [115]157Nd, and 158Nd [116] have been reported in conference proceedings, but have not yet been published in the refereed literature. According to the HFB-14 model [15], 185Nd should be the last odd–even particle stable neutron-rich nucleus while the even–even particle stable neutron-rich nuclei should continue through 196Nd. At the proton drip
Summary
The discoveries of the known zinc, selenium, bromine, and neodymium isotopes have been compiled and the methods of their production described.
While the discovery of the neutron-rich and neutron-deficient zinc isotopes was uncontroversial, the identification of the stable and near-stable isotopes was more difficult. The stable isotopes 64Zn, 66Zn, 68Zn, and 70Zn were initially misidentified as 63Zn, 65Zn, 67Zn, 69Zn, respectively. Then 65Zn and 69Zn as well as 63Zn were incorrectly reported to
Acknowledgments
The main research on the individual elements were performed by JLG (zinc and neodymium), JC (selenium), and JK (bromium). This work was supported by the National Science Foundation under grant No. PHY06-06007 (NSCL).
References (149)
- et al.
Nucl. Phys. A
(2003) - et al.
Phys. Lett. B
(1976) - et al.
Phys. Lett. B
(1986) - et al.
Nucl. Phys. A
(1981) - et al.
Phys. Lett. B
(1981) - et al.
Physica
(1955) Physica
(1937)- et al.
Nucl. Phys. A
(1972) - et al.
J. Inorg. Nucl. Chem.
(1974) - et al.
Nucl. Phys. A
(1977)
Nucl. Phys. A
Nucl. Instrum. Meth.
Phys. Lett. B
Phys. Lett. B
J. Inorg. Nucl. Chem.
J. Inorg. Nucl. Chem.
Nucl. Phys. A
J. Inorg. Nucl. Chem.
J. Inorg. Nucl. Chem. Lett.
J. Inorg. Nucl. Chem.
J. Inorg. Nucl. Chem.
J. Inorg. Nucl. Chem.
Phys. Lett. B
Nucl. Phys. A
Nucl. Instrum. Meth.
Phys. Lett. B
Nucl. Phys. A
Nucl. Phys. A
J. Inorg. Nucl. Chem.
At. Data. Nucl. Data. Tables
Phys. Rev. C
J. Am. Chem. Soc.
Rev. Mod. Phys.
Rev. Mod. Phys.
Rev. Mod. Phys.
Rev. Mod. Phys.
Rev. Mod. Phys.
Rev. Mod. Phys.
Table of Isotopes
Mass Spectra and Isotopes
Phys. Rev. C
Rep. Prog. Phys.
Phys. Rev. Lett.
Eur. Phys. J. A
Bull. Am.Phys. Soc.
Phys. Rev.
Phys. Rev.
Naturwiss.
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