Atoms are the basic particles of the chemical elements. An atom consists of a nucleus of protons and generally neutrons,surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other by the number of protons that are in their atoms. For example,any atom that contains 11 protons is sodium,and any atom that contains 29 protons is copper. Atoms with the same number of protons but a different number of neutrons are called isotopes of the same element.
The neutron is a subatomic particle,symbol
n
or
n0
,which has no electric charge,and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons behave similarly within the nucleus,they are both referred to as nucleons. Nucleons have a mass of approximately one atomic mass unit,or dalton. Their properties and interactions are described by nuclear physics. Protons and neutrons are not elementary particles;each is composed of three quarks.
Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions,in addition to the study of other forms of nuclear matter.
Neutronium is a hypothetical substance made purely of neutrons. The word was coined by scientist Andreas von Antropoff in 1926 for the hypothetical "element of atomic number zero" that he placed at the head of the periodic table. However,the meaning of the term has changed over time,and from the last half of the 20th century onward it has been also used to refer to extremely dense substances resembling the neutron-degenerate matter theorized to exist in the cores of neutron stars;hereinafter "degenerate neutronium" will refer to this.
Particle physics or high-energy physics is the study of fundamental particles and forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the scale of protons and neutrons,while the study of combination of protons and neutrons is called nuclear physics.
In nuclear physics,the island of stability is a predicted set of isotopes of superheavy elements that may have considerably longer half-lives than known isotopes of these elements. It is predicted to appear as an "island" in the chart of nuclides,separated from known stable and long-lived primordial radionuclides. Its theoretical existence is attributed to stabilizing effects of predicted "magic numbers" of protons and neutrons in the superheavy mass region.
The National Superconducting Cyclotron Laboratory (NSCL),located on the campus of Michigan State University was a rare isotope research facility in the United States. Established in 1963,the cyclotron laboratory has been succeeded by the Facility for Rare Isotope Beams,a linear accelerator providing beam to the same detector halls.
TRIUMF is Canada's national particle accelerator centre. It is considered Canada's premier physics laboratory,and consistently regarded as one of the world's leading subatomic physics research centres. Owned and operated by a consortium of universities,it is on the south campus of one of its founding members,the University of British Columbia in Vancouver,British Columbia,Canada. It houses the world's largest normal conducting cyclotron,a source of 520 MeV protons,which was named an IEEE Milestone in 2010. Its accelerator-focused activities involve particle physics,nuclear physics,nuclear medicine,materials science,and detector and accelerator development.
Helium (2He) has nine known isotopes,but only helium-3 (3He) and helium-4 (4He) are stable. All radioisotopes are short-lived;the longest-lived is 6He with half-life 806.92(24) milliseconds. The least stable is 10He,with half-life 260(40) yoctoseconds,though 2He may have an even shorter half-life.
In nuclear physics,the valley of stability is a characterization of the stability of nuclides to radioactivity based on their binding energy. Nuclides are composed of protons and neutrons. The shape of the valley refers to the profile of binding energy as a function of the numbers of neutrons and protons,with the lowest part of the valley corresponding to the region of most stable nuclei. The line of stable nuclides down the center of the valley of stability is known as the line of beta stability. The sides of the valley correspond to increasing instability to beta decay. The decay of a nuclide becomes more energetically favorable the further it is from the line of beta stability. The boundaries of the valley correspond to the nuclear drip lines,where nuclides become so unstable they emit single protons or single neutrons. Regions of instability within the valley at high atomic number also include radioactive decay by alpha radiation or spontaneous fission. The shape of the valley is roughly an elongated paraboloid corresponding to the nuclide binding energies as a function of neutron and atomic numbers.
The Facility for Rare Isotope Beams (FRIB) is a scientific user facility for nuclear science,funded by the U.S. Department of Energy Office of Science (DOE-SC),Michigan State University (MSU),and the State of Michigan. Michigan State University contributed an additional $212 million in various ways,including the land. MSU established and operates FRIB as a user facility for the Office of Nuclear Physics in the U.S. Department of Energy Office of Science. At FRIB,scientists research the properties of rare isotopes to advance knowledge in the areas of nuclear physics,nuclear astrophysics,fundamental interactions of nuclei,and real-world applications of rare isotopes. Construction of the FRIB conventional facilities began in spring 2014 and was completed in 2017. Technical construction started in the fall of 2014 and was completed in January 2022. The total project cost was $730M with project completion in June 2022.
The nuclear drip line is the boundary beyond which atomic nuclei are unbound with respect to the emission of a proton or neutron.
Hendrik Schatz is a professor of Nuclear Astrophysics at Michigan State University. He earned his Diploma from the University of Karlsruhe in 1993,and his PhD from the University of Heidelberg in 1997 after completing his thesis work at the University of Notre Dame. He is one of the Principal Investigators for the Joint Institute for Nuclear Astrophysics and is a leading expert on nuclear astrophysics,. Schatz also serves the science advisory committees for the Facility for Rare Isotope Beams and GSI. Hendrik's primary field of expertise is Type I X-ray Bursts. His most notable contribution to this field is the discovery of the SnTeSb-cycle. Hendrik was featured in Science magazine November 22,2002 for his work on experimental nuclear astrophysics. Hendrik has also contributed to Physics Today.
Unbiquadium,also known as element 124 or eka-uranium,is a hypothetical chemical element;it has placeholder symbol Ubq and atomic number 124. Unbiquadium and Ubq are the temporary IUPAC name and symbol,respectively,until the element is discovered,confirmed,and a permanent name is decided upon. In the periodic table,unbiquadium is expected to be a g-block superactinide and the sixth element in the 8th period. Unbiquadium has attracted attention,as it may lie within the island of stability,leading to longer half-lives,especially for 308Ubq which is predicted to have a magic number of neutrons (184).
Dean Lee is an American nuclear theorist,researcher and educator. He is a professor of physics at the Facility for Rare Isotope Beams (FRIB) and the Department of Physics and Astronomy at Michigan State University and department head of Theoretical Nuclear Science at FRIB.
Alexandre Obertelli is a French experimental nuclear physicist and Alexander von Humboldt Professor of Experimental Nuclear Structure Physics at the Institute of Nuclear Physics of the Technische Universität Darmstadt.
Kevin Insik Hahn is a South Korean physicist who is an expert in the fields of nuclear physics and nuclear astrophysics. Since December 2019,he has been the director of the Center for Exotic Nuclear Studies at the Institute for Basic Science (IBS) in South Korea. He also holds an endowed professorship in the Department of Science Education at Ewha Womans University,where he has worked since 1999. In his research,he has worked on accelerator-based as well as non-accelerator-based experiments. His current research activities involve a number of accelerators around the world,including the RI Beam Factory (RIBF) at RIKEN,Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory,and the soon-to-open Rare isotope Accelerator complex for ON-line experiment (RAON). During his tenure at Ewha Womans University,he promoted STEM/STEAM education by serving for multiple years as the director of the Advanced STEAM Teacher Education Center. He also wrote several physics textbooks for high school students and undergraduate students.
Walter Benenson is a university distinguished professor emeritus in the department of physics and astronomy at Michigan State University. He retired in 2008,but continued to teach for another 10 years.
Alexandra Gade is a nuclear physicist who studies the nuclear structure of heavy elements,exotic nuclei,and rare isotopes,using techniques including nuclear spectroscopy,nucleon knockouts,and Coulomb excitation. Educated in Germany,she works at Michigan State University in the US as a professor of physics in the department of physics and astronomy and as deputy scientific director of the facility for rare isotope beams.
Hans Geissel was a German experimental physicist who studied the atomic and nuclear interaction of energetic heavy ions with matter. In particular,his research focused on the discovery of new isotopes and the investigation of their properties. Geissel was an adjunct professor at the II Institute of Physics at JLU Giessen and was head of the FRS / Super-FRS department at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt,where he was a Helmholtz Professor.
