Unbelievable Half-Life of Zn-64: Investigating Cu-64 Beta Decay

In summary: However, as stated in the reference, it is not known for certain if this is the case, as no such case has been observed to date.
  • #1
daveb
549
2
In the 16th edition of the chart of nuclides, it lists Cu-64 as decaying to Zn-64 by beta minus decay. OK, no problem here. Then it lists Zn-64 decaying back to Cu-64 by positron decay with a half life of 1.1 x 10^19 years. Assuming this isn't some typo, I have 2 questions.
1) How in blazes did they manage to figure this half life out?! The specific activity for Zn-64 is (very) roughly 19 Becquerels per 1000 kg of Zn-64, meaning how did they get a large enough sample to analyze it so that it could be distinguished from background? and
2) How in blazes is it possible for nuclide #1 to decay to #2 then #2 decay back to #1?! Is this some quantum mechanical tunneling effect?
 
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  • #3
Yes, I'm familiar that just about every web source out there says it's stable. However, unless it's just a misprint, the 16th edition of the CON is the most updated (that I've seen) collection of data. It's possible that the web sites that do get updated didn't incorporate this into the site. I'm just wondering if anyone out there has heard anything about this, and if so, how this can be.
 
  • #4
daveb said:
2) How in blazes is it possible for nuclide #1 to decay to #2 then #2 decay back to #1?! Is this some quantum mechanical tunneling effect?

This is not possible unless the first nucleus is initially in an excited state. (See also nuclear isomer). In this case it could be theoretically possible, but I am not aware of any such case which is actually known to occur.
Jim Graber
 
  • #5
daveb said:
In the 16th edition of the chart of nuclides, it lists Cu-64 as decaying to Zn-64 by beta minus decay. OK, no problem here. Then it lists Zn-64 decaying back to Cu-64 by positron decay with a half life of 1.1 x 10^19 years. Assuming this isn't some typo, I have 2 questions.
1) How in blazes did they manage to figure this half life out?! The specific activity for Zn-64 is (very) roughly 19 Becquerels per 1000 kg of Zn-64, meaning how did they get a large enough sample to analyze it so that it could be distinguished from background? and
2) How in blazes is it possible for nuclide #1 to decay to #2 then #2 decay back to #1?! Is this some quantum mechanical tunneling effect?
That CON seems in disagreement with BNL's on-line CON, which reports the half-life of Zn-64 as > 2.8E+16 y. Even so, the activity is so low I wonder how they measured the activity change.

http://www.nndc.bnl.gov/chart/reCenter.jsp?z=30&n=34 (Select 1 under Zoom on righthand side).

http://www.nndc.bnl.gov/chart/

The Cu-64 which decays by beta emission would be at a different energy state than one which decays by positron emission. I would imagine that if Zn-64, which for all intents and purposes is stable, decays by positron emission, then I would imagine that the resulting Cu-64 nuclide would decay by positron emission also to form Ni-64.
 

1. What is the half-life of Zn-64?

The half-life of Zn-64 is approximately 38 hours. This means that after 38 hours, half of the original amount of Zn-64 will have decayed into Cu-64.

2. How is the half-life of Zn-64 determined?

The half-life of Zn-64 is determined through a process called beta decay, in which a nucleus of Zn-64 emits a beta particle (an electron) and transforms into a nucleus of Cu-64. By monitoring the amount of Zn-64 and Cu-64 over time, scientists can calculate the rate of decay and determine the half-life.

3. What is the purpose of investigating Cu-64 beta decay?

Investigating Cu-64 beta decay can provide valuable information about the properties and behavior of Zn-64 and Cu-64, as well as the process of beta decay itself. It can also have practical applications in fields such as nuclear medicine and energy production.

4. How does the half-life of Zn-64 compare to other isotopes?

The half-life of Zn-64 is relatively short compared to many other isotopes. For example, the half-life of carbon-14 is approximately 5,730 years. This makes Zn-64 a good candidate for studying beta decay, as it allows for more efficient data collection and analysis.

5. What are the potential implications of the findings from this investigation?

The findings from this investigation can contribute to our overall understanding of nuclear decay and the behavior of Zn-64 and Cu-64 isotopes. It may also have practical implications in the development of new technologies and treatments in fields such as nuclear medicine and energy production.

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