Neutron deficiency

S.M. Qaim, G. Stocklin, Production of some medically important short-lived neutron-deficient radioisotopes of halogens, Radiochim. Acta 34 (1983) 25-40. 

For very neutron-deficient (i.e., proton-rich) nuclei, the Q value for proton emission, Qp, becomes positive. One estimate, based on the semiempirical mass equation, of the line that describes the locus of the nuclei where Qp becomes positive for ground-state decay is shown in Figure 7.11. This line is known as the proton-drip line. Our ability to know the position of this line is a measure of our ability to describe the forces holding nuclei together. Nuclei to the left of the proton dripline in Figure 7.11 can decay by proton emission. 

Intruder States in Highly Neutron-Deficient Pt Nuclei... 

In this picture, the excitation of nucleons into shell-model intruder states leads to the coexistence of states with different deformations. Shell-model intruder states for the odd-mass Au isotopes, for example, are presented in fig. 2. Note that the h9 2 and i13y2 intruders drop rapidly as one goes more neutron deficient [ZGA80]. 

Van Duppen et al. have recently reported on the observation of low lying JTT=0+ states in neutron deficient Pb isotopes [DUP84]. The latter states are similar to those in the Sn nuclei and their observation is thus not unexpected. The systematic trend of the observed JTT=0+ states through the various Pb isotopes and Sn isotopes is the same. However, the excitation energy of the intruder states in Pb is much lower than in the Sn isotopes. 

Conclusions The measured E2 moments for the 12+ isomers clearly demonstrate the (i13/2)n guasiparticle nature of these states and can be guantitatively explained by the assumption of a small induced core deformation for the more neutron deficient Pb isotopes. 12+ isomers in the halflife... 

To define more accurately the boundaries of the mass regions that could be accessed with the proposed He-jet coupled mass separator system, production cross sections for both neutron-deficient and neutron-rich nuclei far from stability have been estimated for 800-MeV proton reactions. The spallation-product cross sections were estimated through use of the Rudstam systemstics [RUD66]. For estimation of the fission-product cross sections, however, there is no established, similar approach. Thus, an empirical approach was taken in... 

Property Neutron-rich [238U(p,f)] Neutron-deficient [Spallation]... 

We report on the performances of a He-jet connected to a Bernas-Nier ion source. After a brief description of the system we give the first spectroscopic results on very neutron deficient rare-earth isotopes. 

Elements are formed by three different mechanisms in stars, as elucidated by Burbidge et al. [82]. In brief, these are the s process, involving the capture of slow neutrons by nuclei the r process, involving the capture of rapid neutrons and the p process, which leads to neutron-deficient nuclides that are generally less abundant than those generated by the s and r processes. The relative abundances of the various isotopes of a given element reveal which processes, or combinations thereof, are involved in their creation in the nuclear reactions that power stars. Measurements of isotopic and elemental abundances in stars thus serve to test theories of stellar processes. 

Numerous isotopes of rhodium are known, but only ° Rh is stable. The short half-lives of the remainder mean that few radiochemical applications exist. The heavy isotopes of the element feature among the fission products of uranium and the transuranic elements they can also be made by neutron irradiation. Light isotopes result from a-bombardment of the metal, and those of high neutron deficiency from bombardment by very heavy ions. 

The excitation function for production of As radioisotopes via Ge (p, xn) reactions has been determined . Only As is obtainable in sufficiently pure form after the appropriate cooling time . Employing Ge or Ge enriched targets, the As could be produced in higher yields via (p,n) or (p,3n) nuclear reactions. An isotope generator for carrier-free As, the daughter of neutron-deficient Se, has been proposed . ... 

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