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Rixter
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The Least Radioactive Radioactive Element (Known) Xe124

04/29/2019 9:34 PM

"While most xenon isotopes have half-lives of less than 12 days, a few are thought to be exceptionally long-lived, and essentially stable. Xenon 124 is one of those, though researchers have estimated its half-life at 160 trillion years as it decays into tellurium 124. The universe is presumed to be merely 13 to 14 billion years old.

The new finding puts the half-life of Xenon 124 closer to 18 sextillion years. (For the record, that's 18,000,000,000,000,000,000,000.)"

https://www.sciencedaily.com/releases/2019/04/190424153446.htm

To put that into perspective, the half-life is about a trillion times the current age of the universe!

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SolarEagle
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#1

Re: The least radioactive radioactive element (known) Xe124

04/30/2019 12:20 AM

Then how does tellurium 124 exist?

https://en.wikipedia.org/wiki/Isotopes_of_tellurium

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JohnDG
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#2
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Re: The least radioactive radioactive element (known) Xe124

04/30/2019 7:00 AM

1. However long the half-life, (there's a finite probability that) some of the Xe124 will decay every year.

2. Tellurium could have been created directly - no necessarily by Xe decay.

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#3

Re: The Least Radioactive Radioactive Element (Known) Xe124

04/30/2019 1:02 PM

Te-128 has a measured half life a couple of orders of magnitude longer at 2.2×1024 , i.e. over 120 of the zenon isotope nuclei decay in the same time it takes a single tellerium-128 nucleus to decay. So unless theenergy per decay of the zenon isotope is extremely low, it is not the least radioactive.

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Rixter
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Re: The Least Radioactive Radioactive Element (Known) Xe124

04/30/2019 1:49 PM

You're right, that's longer.

https://en.wikipedia.org/wiki/Isotopes_of_xenon

Main isotopes of tellurium (52Te)

Iso­tope

Decay

abun­dance

half-life(t1/2)

mode

pro­duct

120Te

0.09%

stable

121Te

syn

16.78 d

ε

121Sb

122Te

2.55%stable

123Te

0.89%

[1]

stable

124Te

4.74%stable

125Te

7.07%stable

126Te

18.84%stable

127Te

syn9.35 h

β−

127I

128Te

31.74%2.2×10

24 y

β−β−

128Xe

129Te

syn69.6 minβ

−

129I

130Te

34.08%8.2×10

20 y

β

−β−

130Xe

Standard atomic weightAr, standard(Te)

Main isotopes of xenon (54Xe)

Iso­tope

Decay

abun­dance

half-life (t1/2)

mode

pro­duct

124Xe

0.095%1.8×10

22 y[1]

εε

124Te

125Xe

syn

16.9 h

ε

125I

126Xe

0.089%

stable

127Xe

syn36.345 dε

127I

128Xe

1.910%stable

129Xe

26.401%stable

130Xe

4.071%stable

131Xe

21.232%stable

132Xe

26.909%stable

133Xe

syn5.247 d

β−

133Cs

134Xe

10.436%stable

135Xe

syn9.14 hβ

−

135Cs

136Xe

8.857%2.165×10

21 y[2]

β−β−

136Ba

Standard atomic weightAr, standard(Xe)
  • 131.293(6)[3]

In either case, I'm wondering how accurate the numbers are. You need a large enough number of decays to get a good value.

https://iopscience.iop.org/article/10.1088/0026-1394/52/3/S51
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SolarEagle
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#5
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Re: The Least Radioactive Radioactive Element (Known) Xe124

04/30/2019 2:05 PM

Well it's also a little misleading in that the half-life keeps halving....

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#7
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Re: The Least Radioactive Radioactive Element (Known) Xe124

05/01/2019 2:17 AM

Huh? In this example, the half-life stays the same at about 5700 years.

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#6
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Re: The Least Radioactive Radioactive Element (Known) Xe124

04/30/2019 3:37 PM

Nice article on the rarely stated uncertainty in measuring very long time nuclear half lives.

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#8

Re: The Least Radioactive Radioactive Element (Known) Xe124

05/01/2019 3:49 AM

...then it doesn't matter. The half-life of humans is much shorter than that.

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#9
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Re: The Least Radioactive Radioactive Element (Known) Xe124

05/04/2019 11:58 PM

Heck, the whole-life of humans is much shorter than that! In fact, the full life of the human race will almost certainly be a lot shorter than that!

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