Abstract:Currently about 3000 different nuclei are known with about another 3000-4000 predicted to exist. A review of the discovery of the nuclei, the present status and the possibilities for future discoveries are presented.
“…About 7000 nuclides are expected to exist [11] where more than 3000 nuclides are discovered experimentally [12]. The sensitivity of the present mass spectrometry is so high that for some nuclides the first experimental information is their masses [13].…”
The Atomic Mass Evaluation (AME) contains the most reliable and comprehensive information for the values of the atomic masses and their uncertainties. A wealth of new, high-precision experimental data were included in the new version, AME2012, published in December 2012, and masses of many nuclides were improved significantly. The AME2012 is described and compared with the previous AME2003 evaluation. Perspectives about the future are given.
“…About 7000 nuclides are expected to exist [11] where more than 3000 nuclides are discovered experimentally [12]. The sensitivity of the present mass spectrometry is so high that for some nuclides the first experimental information is their masses [13].…”
The Atomic Mass Evaluation (AME) contains the most reliable and comprehensive information for the values of the atomic masses and their uncertainties. A wealth of new, high-precision experimental data were included in the new version, AME2012, published in December 2012, and masses of many nuclides were improved significantly. The AME2012 is described and compared with the previous AME2003 evaluation. Perspectives about the future are given.
“…Furthermore, the single-nucleon drip lines can be estimated from the condition −E F and pairing gap ∆ of odd-odd or odd-A nuclei can be approximated by the average of the corresponding calculated results of their even-even neighbors [22]. Accordingly, we estimate the total number of bound nuclei to be 6794, 6895, 7115 and 6659 for KDE, SLy4, MSL1 and MSL1 * , respectively, leading to a precise estimate of 6866 ± 166 (only 3191 have been discovered experimentally [47]). Although the above candidate interactions are not a large sample, the small variation of their predictions represents a useful estimate of the uncertainty from sources other than E sym (ρ sc ).…”
mentioning
confidence: 90%
“…The experimentally known 800 bound even-even nuclei (up to 2014), including 169 stable (navy squares) and 631 radioactive (green squares), are extracted from Ref. [47] and references therein.…”
Exploring nucleon drip lines and astrophysical rapid neutron capture process (r-process) paths in the nuclear landscape is extremely challenging in nuclear physics and astrophysics. While various models predict similar proton drip line, their predictions for neutron drip line and the r-process paths involving heavy neutron-rich nuclei exhibit a significant variation which hampers our accurate understanding of the r-process nucleosynthesis mechanism. Using microscopic density functional theory with a representative set of non-relativistic and relativistic interactions, we demonstrate for the first time that this variation is mainly due to the uncertainty of nuclear matter symmetry energy Esym(ρsc) at the subsaturation cross density ρsc = 0.11/0.16 × ρ0 (ρ0 is saturation density), which reflects the symmetry energy of heavy nuclei. Using the recent accurate constraint on Esym(ρsc) from the binding energy difference of heavy isotope pairs, we obtain quite precise predictions for the location of the neutron drip line, the r-process paths and the number of bound nuclei in the nuclear landscape. Our results have important implications on extrapolating the properties of unknown neutron-rich rare isotopes from the data on known nuclei. 1. Introduction.-The determination of the location of neutron and proton drip lines in the nuclear landscape is a fundamental question in nuclear physics. The drip lines tell us what is the limit of the nuclear stability against nucleon emission and how many bound nuclei can exist in the nuclear chart [1]. The quest for the neutron drip line (nDL) is also important for understanding the astrophysical rapid neutron capture process (r-process) which occurs along a path very close to the nDL in the nuclear landscape and provides a nucleosynthesis mechanism for the origin of more than half of the heavy nuclei in the Universe [2][3][4][5]. While the proton drip line (pDL) has been determined up to Protactinium (proton number Z = 91) [6], there has little experimental information on the nDL for Z > 8 [7]. Since the majority of rare isotopes inhabiting along the nDL and the r-process paths are unlikely to be observed in the terrestrial laboratory, their information has to rely on the model extrapolation based on the known nuclei, which is so far largely uncertain and hampers our accurate understanding of the r-process nucleosynthesis mechanism [8][9][10][11]. To understand and reduce the uncertainty of the model extrapolation from the known nuclei to the unknown neutron-rich rare isotopes is thus of critical importance, and we show here the symmetry energy plays a key role in this issue.
“…Only about 3300 of them were experimentally observed; this number steadily grows due to the efforts of many devoted laboratories. We should note that it has been an unfortunate tradition that only the discovery of a new chemical element -which means the progress along the Z-coordinate of the nuclear chart -was celebrated in the past as a real discovery repeatedly awarded by Nobel Prizes in chemistry; in contrast, the motion along the N-coordinate -related to the discovery of new isotopes -has been less known but often it requires great experimental efforts [7].…”
The standard textbook statement reads "Nuclei consist of protons and neutrons." For the major part of what we are going to discuss in the course, this simple notion is approximately true. Indeed, complex nuclei in the Universe were mostly "cooked" in stars by the processes of consecutive addition of neutrons and protons and their mutual transformations. It is relatively easy to extract these particles back from the nuclei since the separation energy per particle is typically only 6-8 MeV, less than 1% of the mass of the proton (p) or neutron (n) that is of order ∼ 1 GeV = 10 3 MeV.In many nuclei with an abnormal ratio between the proton and neutron numbers, the separation energy is even significantly lower than the value mentioned earlier. And still the statement of our first sentence has a limited range of validity. In general, the answer to the question of nuclear constituents depends on the kind of phenomena we are interested in. Various experimental studies emphasize different aspects of nuclear structure. Different patterns can be resolved at different energy scales by specifically adjusted experimental tools.The nuclear forces that keep the nucleus together are induced through exchange by mediating quanta -mesons, similar to how the electromagnetic interactions are generated by the exchange of photons. Roughly speaking, at energies small compared to the masses of particles that are capable of serving as mediators of nuclear forces, the nucleus indeed looks as an object composed of protons and neutrons. (Note that such a range of energies does not exist in the case of electromagnetic interactions carried by massless photons.) Protons and neutrons have very similar nuclear properties, and they are called by a unifying term "nucleons" (N). The mesons of the lightest family, pions ( +,0,− ), are approximately seven times lighter than the nucleons. Corresponding energies E < m c 2 ≈ 140 MeV define a domain of low-energy nuclear physics where the nucleus can be considered as being made of nonrelativistic nucleons. In this domain, mesons are virtual particles hidden in nucleon-nucleon interactions, and they rarely appear Physics of Atomic Nuclei, First Edition. Vladimir Zelevinsky and Alexander Volya.
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