Questions about beta radiation shielding

[jun192022]

My understanding is that most beta radiation can be shielded by 1-2 cm of plastic. However, I have also read that beta radiation energies exist on a spectrum. Does this mean that there exist some beta-emitting radioisotopes which can be shielded by thinner materials? Are there any beta-emitting radioisotopes which have beta radiation that can be shielded by a sheet of paper? Are there any beta-emitting radioisotopes which have beta radiation that could be shielded by 1-2 layers of bubble wrap?

 

[Astronuc]

However, I have also read that beta radiation energies exist on a spectrum.

Each beta emitting radionuclide has a characteristic spectrum of beta energies. There is a maximum energy for the beta particle, and everything down to very low energy; an antineutrino shares the balance of energy.

One has to look at the beta energy for a given nuclide. Some examples:
https://en.wikipedia.org/wiki/Beta_decay#Energy_release

One needs to investigate the range of an electron with a given energy.

Bubble wrap contains air in layers of plastic, and the structure comes in a variety of thicknesses of plastic layers and bubble sizes.

 

[jun192022]

It seems that in theory, a radionuclide which emits beta particles with higher energies would have greater penetration, and that conversely, a radionuclide which emits beta particles with lower energies would be easier to shield. Would a radionuclide which emits beta particles with lower energies be expected to present a lower health risk than one which emits higher-energy betas?

 

[Astronuc]

Would a radionuclide which emits beta particles with lower energies be expected to present a lower health risk than one which emits higher-energy betas?

Not necessarily - from the beta particle, yes, however some lower energy betas may be accompanied by higher energy gamma rays from Isomeric Transition; see for example ⁶⁰C, which has

β (beta decay)	0.317[2] MeV
γ (gamma-rays)	1.1732,1.3325 MeV

One must consider gamma radiation energy, or energies, as well as the beta energy. Betas from nuclear decay have a range of energies. There is a maximum energy and a most probably energy, which is about 1/3 of the maximum energy.

Another example, The maximum energy of the tritium beta is 18.591±0.059 keV; the average energy is 5.685 ±0.008 keV. Tritium beta decay is not accompanied by gamma decay.
https://www.nrc.gov/docs/ML2034/ML20343A210.pdf

 

[snorkack]

C (carbon, element 6) does not have a bound isotope 60.
Co (cobalt, element 27) does, and that does have beta decay.
For a common example, see the same C, but isotope 14.
https://www.google.com/url?sa=t&rct...usg=AOvVaw3bjh8bQ_1Qtk1w8TTo93Nh&opi=89978449
Maximum beta energy 156 keV. Average beta energy 49,5 keV.
Maximum beta range in air 254 mm. Maximum beta range in "water/tissue" quoted as 300 μm. 50 μm water stops half of the radiation, 70 μm (thickness of dead layer of skin) 83%, 170 μm 90 %
Office paper is commonly quoted as 80 μm. Which means it is not enough to stop the high energy tail.
Uncommon isotopes are commonly quoted with maximum beta energy, without specifying maximum penetration. Is there any simple derivation of beta energy for given maximum penetration, to look up which isotopes do and which do not penetrate a given radiation shield?

 

[gleem]

As far as the penetration (range) of the maximum energy of a beta source is concerned, simple empirical relations have been determined. In general, the range can be written as Range = 412Eⁿ where
n = 0.0948 - 1.265 for energies from .01 Mev to 3 Mev and Range = 530E-106 for energies from 1 Mev to 20 Mev. Range is in mg/cm2.

As long as bremsstrahlung is not important (collision loss >> radiative losses) then the range in one medium is the same for another.

An approximation for transmission is exponential which doesn't give a max range but is useful for small thicknesses of an absorber and is useful for Beta energies of 0.1 MeV to 4Mev.

Transmission = e^-μd where μ =17/E^1.14 with E in Mev and d in g/cm2.

Most beta emitters which one might encounter have maximum energies less than 4 Mev.

Or you can use this graph

 

[snorkack]

Transmission = e^-μd where μ =17/E^1.14 with E in Mev and d in g/cm2.

Most beta emitters which one might encounter have maximum energies less than 4 Mev.

Or you can use this graph
View attachment 356255

So 100 keV penetrates about 150 g/m² and 50 keV about 50 g/m²?
Then the 80 g/m² paper sheet stops about 70 keV?
Returning to the original question: "Which radioisotopes have low enough maximum decay energy that it can be stopped by specified thickness of shielding?"
Look at the link:
https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html
Q_β colouring can be selected (under three point button)
The chart inexplicably misses some values, conspicuously the 18,6 keV of t. And be cautious clicking - the chart most inconveniently goes pale and I cannot find a way to restore it. Hover the mouse instead
Systematically browsing it is a lot of work, and I don´t have the threshold energy you ended up settling on. But other than t, some conspicuously low energies:

• C-14 at 156 keV
• Ni-63 at 67 keV
• Zr-93 at 91 keV... except with a catch! it also produces 31 keV gamma, which is more penetrating!
• Pd-107 at 34 keV
• Re-87 at 2,4 keV

But due to the above technical issues, I am not sure of completeness...