Proton emission

Proton emission

Proton emission (also known as proton radioactivity) is a type of radioactive decay in which a proton is ejected from a nucleus.

The decay of a proton rich nucleus A populates excited states of a daughter nucleus B by β+ emission or electron capture (EC). Those excited states that lie below the separation energy for protons (Sp) decay by γ emission towards the groundstate of daughter B. For the higher excited states a competitive decay channel of proton emission to the granddaughter C exists, called β-delayed proton emission.

Proton emission can occur from high-lying excited states in a nucleus following a beta decay, in which case the process is known as beta-delayed proton emission, or can occur from the ground state (or a low-lying isomer) of very proton-rich nuclei, in which case the process is very similar to alpha decay.

For a proton to escape a nucleus, the proton separation energy must be negative - the proton is therefore unbound, and tunnels out of the nucleus in a finite time. Proton emission is not seen in naturally occurring isotopes; proton emitters can be produced via nuclear reactions, usually utilising some kind of particle accelerator.

Although prompt (i.e. not beta-delayed) proton emission was observed from an isomer in Cobalt-53 as early as 1969, no other proton-emitting states were found until 1981, when the proton radioactive ground states of Lutetium-151 and Thulium-147 were observed at experiments at the GSI in West Germany.[citation needed] Research in the field flourished after this breakthrough, and to date more than 25 isotopes have been found to exhibit proton emission. The study of proton emission has aided the understanding of nuclear deformation, masses and structure, and it is a wonderfully pure example of quantum tunneling.

In 2002, the simultaneous emission of two protons was observed from the nucleus Iron-45 in experiments at GSI and GANIL (Grand Accélérateur National d'Ions Lourds, near Caen). In 2005 it was experimentally determined (at the same facility) that Zinc-54 can also undergo double proton decay.

See also

External links

v · d · eNuclear processes
Radioactive decay
Stellar nucleosynthesis
Other processes
Emission
Neutron emission · Positron emission · Proton emission
Capture

Wikimedia Foundation. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • Émission de proton — La désintégration d un noyau A riche ne protons peuple les niveaux d énergie excités du noyau fils B par émission β+ ou capture électronique. Les états excités qui se situent sous l énergie de séparation de protons (Sp) décroissent par émission γ …   Wikipédia en Français

  • Proton–proton chain reaction — The proton–proton chain reaction dominates in stars the size of the Sun or smaller. The proton–proton chain reaction is one of several fusion reactions by which stars convert hydrogen to helium, the primary alternative being the CNO cycle. The… …   Wikipedia

  • Proton (disambiguation) — A proton is a subatomic particle with a positive fundamental electric charge of 1.6 times; 10 19 coulomb and a mass of 938 MeV in other words, a hydrogen ion, specifically 1H, which contains no neutrons.Terms derived directly from this core… …   Wikipedia

  • Emission de neutron — Émission de neutron L émission de neutron est la réaction (radioactive) par laquelle un isotope (instable) perd (spontanément) un neutron, le poids atomique diminue de un et le numéro atomique est conservé. Par exemple 4H se transforme en 3H.… …   Wikipédia en Français

  • PROTON — Avec le neutron, le proton est l’un des composants de base des noyaux d’atomes et il constitue lui même le noyau de l’atome d’hydrogène. C’est l’une des rares particules élémentaires stables, et l’on peut le considérer, avec l’électron et le… …   Encyclopédie Universelle

  • proton decay — proton decay, the radioactive transmutation of one chemical element into another by the emission of a proton from an unstable nucleus: »Proton decay…is a process in which a nucleus emits a proton and decreases both atomic number and atomic weight …   Useful english dictionary

  • Émission bêta — Radioactivité β La radioactivité bêta ou émission bêta (symbole β) est un type de désintégration radioactive dans laquelle une particule bêta (un électron ou un positron) est émise. On parle de désintégration bêta moins (β ) (basse énergie) ou… …   Wikipédia en Français

  • Émission de neutron — L émission de neutron est la réaction (radioactive) par laquelle un isotope (instable) perd (spontanément) un neutron, le poids atomique diminue de un et le numéro atomique est conservé. Par exemple 4H se transforme en 3H. L émission de neutrons… …   Wikipédia en Français

  • proton-proton cycle — ▪ astronomy also called  Proton proton Reaction,         chain of thermonuclear reactions that is the chief source of the energy radiated by the Sun and other cool main sequence stars (star). Another sequence of thermonuclear reactions, called… …   Universalium

  • Proton (carmaker) — Infobox Company company name = Proton Holdings Bhd company company type = Public (Bursa Malaysia: PROTON) foundation = Established 1983 location = flagicon|Malaysia Kuala Lumpur, Malaysia key people = Syed Zainal Abidin Syed Mohd Tahir (MD)… …   Wikipedia

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”