Internal conversion coefficient

Internal conversion coefficient

In nuclear physics, the internal conversion coefficient describes the rate of internal conversion.

The internal conversion coefficient may be empirically determined by the following formula:

:alpha = frac{mbox{number of de-excitations via electron emission{mbox{number of de-excitations via gamma-ray emission

There is no valid formulation for an equivalent concept for E0 (electric monopole) nuclear transitions.

There are theoretical calculations that can be used to derive internal conversion coefficients. Their accuracy is not generally under dispute, but it should be understood that since they depend on quantum mechanical models involving purely electromagnetic interactions between nuclei and electrons, there may be unforeseen effects which result in a conversion coefficient differing from one that is empirically determined.

Internal conversion coefficients can be looked up from tables, but this is time-consuming. Computer programs have been developed (see the [http://ie.lbl.gov/programs/icc/icc.htm ICC Program] ) which will present internal conversion coefficients quickly and easily.

The three theoretical calculations of interest are the Röselref|Rösel, Hager-Seltzerref|Hager-Seltzer, and the Bandref|Band.

The Hager-Seltzer calculations omit the M and higher-energy shells on the grounds (usually valid) that those orbitals have little electron density at the nucleus and can be neglected. To first approximation this assumption is valid, upon comparing several internal conversion coefficients for different isotopes for transitions of about 100 keV.

The Band calculation assumes that the M shell may contribute to internal conversion to a non-negligible extent, and incorporates a general term (called "N+") which takes into account the small effect of any higher shells there may be, while the Rösel calculation works like the Band, but does not assume that all shells contribute and so generally terminates at the N shell.

References

# F. Rösel, H.M. Fries, K. Alder, H.C. Pauli: At. Data Nucl. Data Tables 21 (1978) 91.
# R.S. Hager and E.C. Seltzer, Nucl. Data Tables A4 (1968) 1.
# I.M. Band, M.B. Trzhaskovskaya: Tables of the gamma–ray internal conversion coefficients for the K, L, M shells, 10

Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • internal conversion coefficient — vidinės konversijos koeficientas statusas T sritis fizika atitikmenys: angl. internal conversion coefficient vok. innerer Konversionskoeffizient, m rus. коэффициент внутренней конверсии, m pranc. coefficient de conversion interne, m …   Fizikos terminų žodynas

  • Internal conversion — This article is about the nuclear process. For the chemical process, see Internal conversion (chemistry). Internal conversion is a radioactive decay process where an excited nucleus interacts with an electron in one of the lower atomic orbitals,… …   Wikipedia

  • Conversion electron — A conversion electron is a term used to describe an electron which results from the internal conversion process. Internal conversion is a process in which a nucleus can transfer its energy to an atomic electron. Due to their close proximity to… …   Wikipedia

  • coefficient de conversion interne — vidinės konversijos koeficientas statusas T sritis fizika atitikmenys: angl. internal conversion coefficient vok. innerer Konversionskoeffizient, m rus. коэффициент внутренней конверсии, m pranc. coefficient de conversion interne, m …   Fizikos terminų žodynas

  • Conversion interne — La conversion interne est un mode de désintégration radioactive par lequel un électron acquérant directement l énergie d excitation d un noyau atomique s en trouve expulsé de l atome. Il y a donc émission d un électron énergétique, mais en dehors …   Wikipédia en Français

  • Coefficient of performance — The coefficient of performance or COP (sometimes CP), of a heat pump is the ratio of the change in heat at the output (the heat reservoir of interest) to the supplied work. Contents 1 Equation 2 Derivation 3 Improving COP 4 …   Wikipedia

  • Ocean thermal energy conversion — Temperature differences between the surface and 1000m depth in the oceans Ocean Thermal Energy Conversion (OTEC) uses the difference between cooler deep and warmer shallow or surface ocean waters to run a heat engine and produce useful work,… …   Wikipedia

  • radioactivity — /ray dee oh ak tiv i tee/, n. Physics, Chem. the phenomenon, exhibited by and being a property of certain elements, of spontaneously emitting radiation resulting from changes in the nuclei of atoms of the element. Also called activity. [1895… …   Universalium

  • innerer Konversionskoeffizient — vidinės konversijos koeficientas statusas T sritis fizika atitikmenys: angl. internal conversion coefficient vok. innerer Konversionskoeffizient, m rus. коэффициент внутренней конверсии, m pranc. coefficient de conversion interne, m …   Fizikos terminų žodynas

  • vidinės konversijos koeficientas — statusas T sritis fizika atitikmenys: angl. internal conversion coefficient vok. innerer Konversionskoeffizient, m rus. коэффициент внутренней конверсии, m pranc. coefficient de conversion interne, m …   Fizikos terminų žodynas

Share the article and excerpts

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