In-beam spectroscopy of heavy elements

Abstract

Traditionally the experimental study of heavy and superheavy elements has belonged to the realm of decay spectroscopy and nuclear reactions. Only in the past twenty years or so has it become feasible to study nuclei with Z=96 and beyond with in-beam spectroscopic techniques. Since the pioneering studies in the late 1990s, development of both instrumentation and experimental techniques has resulted in a significant lowering of the spectroscopic limit for in-beam measurements. Such measurements give access to a wide range of nuclear structure observables which in general are beyond the reach of other techniques. The current review aims to present the most recent developments and results in the field, building upon previous reviews with a similar theme.

Colloquium : Superheavy elements: Oganesson and beyond

“…Nuclear structure observables strongly depend on the underlying shell structure. Unfortunately, current empirical shell model potentials as well as self-consistent DFT models do not produce robust, consistent explanations of the steadily-growing body of spectroscopic information on transactinides (Ackermann, 2015;Ackermann and Theisen, 2017;Gates et al, 2015;Herzberg, 2016;Rudolph et al, 2015Rudolph et al, , 2013Theisen et al, 2015).…”

“…To constrain nuclear models in the superheavy region, new high-quality data on bulk properties and spectroscopy of superheavy systems are required. High-quality experimental data have been accumulated on global properties of superheavy nuclei and their spectroscopy (Ackermann, 2015;Ackermann and Theisen, 2017;Herzberg, 2016;Rudolph et al, 2015Rudolph et al, , 2013Theisen et al, 2015).…”

Stability of the heaviest elements: K isomer in No250

“…Indeed, sidebands are commonly observed in N = 150, 152 isotones (e.g., 254 No, 252 No, 250 Fm, etc. [6,26,28,29]) as well as in other N = 148 isotones. For instance, a recent study of 244 Cm underlines the presence of a sideband with spin and parity K π = 2 − and a bandhead at 933.6 keV, interpreted as an octupole vibrational band [30].…”

“…In even-even nuclei, breaking of a pair of nucleons can lead to the creation of a high-K configuration, whose decay is strongly hindered according to selection rules, resulting in formation of a metastable state. Although K isomerism is a common feature in the transfermium region [4][5][6][7], only a few cases have been observed in which their half-lives are longer than that of the ground state. Those cases, indeed, are of special interest since they point to significant enhancement of stability against the fission despite the high excitation energy (≈ 1 MeV) and the low fission barrier (≈ 6 MeV).…”

Production cross section and decay study of Es243 and Md249

“…On the other hand, the studies of odd-mass nuclei are rewarded by the wealth of information regarding single-particle states, exceeding what can be obtained for even-even nuclei [2]. Regarding the known excited states of single-particle or collective nature, little data is available for Es (Z = 99) and Md (Z = 101) isotopes [2,3]. Before in-beam spectroscopy of these odd-Z nuclei can be attempted, feasibility studies are a prerequisite, in particular, measurements of production cross sections.…”