This unit explains nuclear Physics

Nuclear Physics

The high energy nuclear physics experimental group at Columbia University is conducting research to study the collisions of relativistic heavy nuclei to understand the properties of nuclear matter at extremely high densities (similar to the center of neutron stars) and very high temperatures (much hotter than at the center of the sun). In fact, the temperatures and densities reached in these collisions are similar to those found in the early universe a few microseconds after the Big Bang.
Atoms are made of a central nucleus with orbiting electrons.

The nucleus is composed of protons and neutrons, and individual protons and neutrons are composed of quarks and gluons which are bound inside these particles (also called hadrons). Quarks are always observed to be bound in hadronic states, and free quarks have never been observed. However, lattice calculations of Quantum Chromodynamics (QCD) indicate that at high temperature and pressure, the hadrons essentially melt and the quarks and gluons are asymptotically free. The formation and experimental detection of such a state (called the quark-gluon plasma or QGP) is the primary goal of high-energy nuclear physics.

In lower energy nuclear reactions, the nuclei exchange protons and neutrons. But, at highly relativistic energies the nuclei are destroyed leaving a region in space with an extremely large energy density. This region may be characterized as a quark-gluon plasma.

In the hot reaction region, we are looking for a phase transition of nuclear matter as shown in the above phase diagram. Eventually the system expands and cools, thus crossing back over the phase boundary and binding all the quarks and gluons back into hadrons. By studying the final particle yields, we hope to understand the nature of this phase transition. Our current model of the early universe suggest that it cooled through the quark-gluon plasma phase transition a few microseconds after the Big Bang; the aim of relativistic heavy ion physics is to replicate millions of microscopic versions of this transition, and through them learn more about the nature of the transition


(a) For each of the four radioactive decays listed below, write the decay reaction and identify the daughter in the form.

α decay of :

β decay of :

β+ decay of :

γ decay of :

(b) The number of radioactive nuclei present at the start of an experiment is 4.60 × 1015. The number present twenty days later is 8.14 × 1014. What is the half-life (in days) of the nuclei? (Solutions)


Problem 2
What is the average binding energy per nucleon (in MeV/nucleon) of the nucleus? Use the following masses in atomic mass units (Solutions):

mass of O-16 atom = 15.9949146 u

mp = 1.0072765 u

mn = 1.0086649 u

me = 0.0005486 u

Applets and Animations

Alpha Decay Watch alpha particles escape from a Polonium nucleus, causing radioactive alpha decay. See how random decay times relate to the half life. (Previously part of the Nuclear Physics simulation – now there are separate Alpha Decay and Nuclear Fission sims.)
Beta Decay Watch beta decay occur for a collection of nuclei or for an individual nucleus.
Nuclear Decay The decay of 500 atoms of the fictional element Balonium. Uses a proper Monte Carlo engine to simulate real decays
Nuclear Fission Start a chain reaction, or introduce non-radioactive isotopes to prevent one. Control energy production in a nuclear reactor! (Previously part of the Nuclear Physics simulation – now there are separate Alpha Decay and Nuclear Fission sims.)
Radioactive Dating Game Learn about different types of radiometric dating, such as carbon dating. Understand how decay and half life work to enable radiometric dating to work. Play a game that tests your ability to match the percentage of the dating element that remains to the age of the obje



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