Home Page | Overview | Site Map | Index | Appendix | Illustration | About | Contact | Update | FAQ |
![]() |
![]() |
as a function of the mass number A (shown by the solid curve in Figure 14-01). The result is not particularly accurate for the lower value of A. The expression is useful in discussing stability, radioactivity, and the fluctuations from the average behavior due to shell effects. The top diagram in Figure 14-04a shows two vibrational energy levels, which split into finer structures due to rotation. Figure 14-04b shows the deformation of the liquid drop, which eventually separates into two pieces (caused by the electrostatic repulsion of the protons). |
Figure 14-04a Liquid Drop Model [view large image] |
Figure 14-04b Fission |
![]() |
![]() |
There is extensive experimental evidence of the contrary hypothesis that the nucleons move in an effective potential well created by all the other nucleons. Since the nucleons are densely packed into a small region, it is expected that the chance of collision is very high. However, the interaction by collision is minimized by the Pauli exclusion principle, which forbids two fermions to occupy the same quantum state. If there are no nearby, unfilled quantum states that can be reached by the available energy for an interaction, then the interaction will not occur. |
Figure 14-05a Nuclear Potential |
Figure 14-05b Nuclear Energy Levels [view large image] |
![]() |
A more realistic nuclear (nucleon-nucleon) potential is the empirical curve shown in Figure 14-05c. As originally proposed by H. Yukawa, the longest range part of the strong internucleon force can be attributed to exchange of the ![]() |
Figure 14-05c Nucleon-Nucleon Potential [view large image] |
Figure 14-05c depicts a deuterium nucleus. The proton and neutron are composed of d (down), u (up), u quarks and d, u, d quarks respectively (in colors). The gluons are denoted by the coils with the lighter one representing the residual. |
![]() |
|
Figure 14-05d QCD Quandaries |
![]() |
There were reports on the detection of pentaquark since 2002. It has finally been confirmed in July 2015 by the LHCb experiment at LHC. Re-analysis of the 2009-12 data reveals that two states of the pentaquark have been detected at 4.38 and 4.45 Gev with less than 10-7 probability due to chance. The measurements were taken from the very rare events of the lambda(b) decay into the K- and the pentaquark with baryon # = 1 and electric charge +1 (see Figure 14-05e). There are two possible configurations : (1) the five quarks are tightly bound, (2) a baryon and a meson are loosely bound (something like a strong interaction molecule). The pentaquark itself decays into a proton and a J/![]() ![]() |
Figure 14-05e Pentaquark |
The discovery will provide more information about the behavior of quarks and may help to shed light on the nature of quark stars. It is also suggested that dark matter could be dense agglomerations of many quarks called Macros (See more in "Dark Matter" and even more in "Strangely Familiar"). |
![]() |
![]() |
than 100 million years, which seems to be too long even if it happens to be located right in the middle of the island of stability. Figure 14-05g presents all the trans-uranium elements synthe-sized artificially. It shows the steady decrease in half-life with increasing atomic number (# of protons), then this sudden jump in the disputed claim. The color of the square represents the |
Figure 14-05f Nuclear Island |
Figure 14-05g Trans-uranium Elements |
chemical property of the element as indicated in the traditional periodic table (see also insert in the figure). |
![]() |
The entire periodic table compiling of all the s, p, d and f orbitals (electron configurations) has finally been assembled with the synthesis of element 117 in 2010. If more elements are ever synthesized in the future, they will start with element 119 and 120 of the S-type and then follow by a huge block of the G-type with 50 columns (see Figure 14-05g). As the number of positive charges in the nucleus increase steadily, so does the speed of the electrons in the inner orbitals. The effect causes a contraction in the size of the inner orbitals, but the influence reaches all the way to the valence orbitals (the outermost ones), which define the chemical properties of the elements. For example, silver is shiny because the rather large energy gap is unable to absorb visible light; while gold (the element directly under it in the periodic table) displays rich color as the |
Figure 14-05g Periodic Table Upgrade [view large image] |
separation between energy levels shrink. Such relativistic effect becomes more drastic for elements with atomic number more than 100, they do not have the properties predicted by the periodic table and thus the table loses its explanatory power for the very heavy elements. |