Sr-90 informations
General info
Sr-90 is one of isotopes of strontium. In the Sr-90 nucleon, there are 38 protons and 52 neutrons. It is produced from spent nuclear fuel by nuclear fission of radioactive materials. The fission product yield from U-235 is 5.7%, from U-238 is 6.6% and from Pu-239 is 2.0%. It emit beta with beta decay, which decay energy is $0.5459(14)\mathrm{MeV}$. But electron and neutrino share the decay energy, it means distribution of energy of electron have peak with broad band width. The average value of electron energy is $195.7 \mathrm{keV}$ The half-life is 28.91(3) years and it becomes Y-90. Y-90 result from beta decay has ground state energy, so there is any gamma particles from this decay process.
But the daughter product also have short half-life with 64.05 hours. It also does beta decay with large decay energy about $2.2785(16) \mathrm{MeV}$. Y-90 decays to 3 stats of Zr-90, which average energies are $0.0242(5)\mathrm{keV}$, $0.1846(6)\mathrm{MeV}$ and $0.9324(7)\mathrm{MeV}$. And if Y-90 decays to excited state of Zr-90, then excited Zr-90 omit gamma with $1.76070(20)\mathrm{MeV}$ or $2.18624(3)\mathrm{MeV}$. But over the 99.9% decays to ground state, thus the effect of gamma can be negligible. The details are in Decay radiation section.
Source Specification
Decay radiation
Decay scheme
Beta emission
- From Sr-90 to Y-90
| $E_{\beta-}$ [$\mathrm{keV}$] |
$I_{\beta-}(abs)$ [%] |
Daughter level [$\mathrm{MeV}$] |
$J^{\pi}$ | $E_{\beta-,max}$ [$\mathrm{keV}$] |
log ft | Transition type |
|---|---|---|---|---|---|---|
| 195.7(5) | 100 | 0 | 2- | (545.9) | 9.4(1) | 1st unique |
- From Y-90 to Zr-90
| $E_{\beta-}$ [$\mathrm{keV}$] |
$I_{\beta-}(abs)$ [%] |
Daughter level [$\mathrm{MeV}$] |
$J^{\pi}$ | $E_{\beta-,max}$ [$\mathrm{keV}$] |
log ft | Transition type |
|---|---|---|---|---|---|---|
| 24.2(5) | 1.4e-6(3) | 2.186273(14) | 2+ | (92.9) | 11.04(10) | 1st non-unique |
| 184.6(6) | 1.15e-2(14) | 1.76074(14) | 0+ | (517.8) | 9.64(6) | 1st unique |
| 932.4(7) | 99.9885(14) | 0 | 0+ | (2278.5) | 9.2240(23) | 1st unique |
Gamma emission
| $E_{\gamma}$ [$\mathrm{keV}$] |
$I_{\gamma-}(abs)$ [%] |
Initial level [$\mathrm{keV}$] |
$J^{\pi}$ | Final level [$\mathrm{keV}$] |
$J^{\pi}$ | Mult. | $\delta$ | $\alpha_T$ | $I_{tot}$ [%] |
|---|---|---|---|---|---|---|---|---|---|
| 1760.70(20) | 1760.74(14) | 0+ | 0 | 0+ | E0 | 0.0115(14) | |||
| 2186.24(3) | 0.0000014(3) | 2186.273(14) | 2+ | 0 | 0+ | E2 | 5.36e-4 | 0.0000014(3) |