100 Years of Nuclear Isomers

Quasi-particle structure is vital to understanding the stability of the heaviest elements. The alpha decay and fission processes ultimately determine how long a nucleus will survive. Observations in the decay chains of 270Ds suggest that high-K multi-quasiparticle isomeric states can decay via alpha emission where the metastable state is longer lived than the ground state of the same nucleus....

Energy storage in chemicals, whether fuels or batteries, forms the basis for the U. S. Army’s many energy
and power applications. However, these materials are restricted in both energy density and longevity,
motivating interest in radioisotopes and nuclear isomers as a means of pushing beyond the “chemical
limit”. In particular, the potential for long‐lived isomers to enable production,...

The development of high-quality isomeric beams opens the possibility to probe the influence of nuclear isomers in stellar scenarios and provide experimentally constrained parameters to astrophysical reaction rates. Such is the case of the low-lying isomers along the rp-process nucleosynthesis path, or on Galactic ${}^{26}$Al.
In this talk, I'll discuss recent experimental efforts to develop...

To understand the exact path of the r-process and its link to the observed abundance pattern requires experimental discoveries combined with extensive network simulations. Structure and decay properties of thousands of neutron-rich nuclei are key determinants of the nuclear flow throughout the entire r-process. To date, multiple extensive sensitivity studies of nuclear masses, half-lives,...

Isomeric states may play an important role in the rp-process, but as of yet are not regularly included in sensitivity studies. In astrophysical environments, isomers may be populated through thermal excitation, as a beta-decay end product, or a combination of these. Significant isomeric populations can alter the effective beta decay rate of a given isotope, and proton capture on these isomers...

Neutron capture reactions play an important role in nuclear physics and other fields that seek to understand physical processes in which neutrons react with their environment. In particular, knowledge of capture cross sections is crucial for nuclear astrophysics applications. Many required capture cross sections are unknown and extremely difficult to determine experimentally, as their...

In the study of isomer excitation and deexcitation, it is important to know the structure properties of isomers, and in addition, the intermediate states with detailed internal transitions (ITs) that connect isomers and the ground state [1,2]. Theoretical study of all these requires the modern many-body technique and knowledge on nuclear interactions. We apply two different shell models, the...

Isomeric nuclear states provide a window into the structure of the atomic nucleus and can serve as a first indicator of change in nuclear structure as a function of neutron and proton number. However, gaps in our understanding occur when we are unable to identify and characterize certain isomeric transitions such as those where the isomeric transition is at low energy or if the transition is...

Astrophysics models usually take one of two approaches to nuclear reaction and decay rates: either they use the nuclear ground state properties, or they take a thermal equilibrium distribution of excited states. Nuclear isomers can invalidate both of these assumptions. If an isomer has a decay rate very different from the ground state rate, its inhibited transitions can cause it to fail to...

It is well known that 102Rh has a ground state with t1/2 = 207.3 days and an isomer at an excitation energy of 140.7 keV with t1/2 = 3.742-years. Following the irradiation of a rhodium chloride target with 35-MeV protons from Lawrence Berkeley National Laboratory's 88-Inch Cyclotron, we chemically separated the rhodium and palladium fractions and then counted them separately using high-purity...

We obtained some fascinating results on the ${}^{213}$Pb neutron-rich nucleus studied using the unique availability of a primary 1 GeV $A$ ${}^{238}$U beam and of the FRS-RISING setup at GSI. The products of the uranium fragmentation were separated in mass and atomic number and then implanted for isomer decay $\gamma$-ray spectroscopy. A level scheme from the decay of the $21/2^{+}$ isomer, based on...

Magic nuclei are the cornerstone of our understanding of the nuclear structure, and the double shell closure in ${}^{208}$Pb (Z=82, N=126) makes no exception. The persistence of these magic number far from ${}^{208}$Pb is a key issue for the understanding of heavy nuclei as well as for the r-process path. While the region beyond N=126 and below Z=82 is difficult to reach with multi-nucleon...