Radioactivity problem - Interpretation

[bachmusico]

Hi! I should solve this exercise (quite important for me, because related to an important test I should sit next week) but I'm having some trouble with the right interpretation of the problem statement.

Homework Statement

In which one of the radioactive series do you think the presence of artificial radioisotopes is possible?

Homework Equations

Maybe radioactive elements decay law, activity equation.

The Attempt at a Solution

I haven't been studying physics for a long time, but I've formulated my hypothesis.

The question refers to the so-called neptunium series, which can be observed as a whole only if artificial radioisotopes are producted. In fact the members of the series are concentrated in a sample of the longest-lived member, from which they derive, in concentrations proportional to the activity of each member. So, if the longest-lived member (in this case 237NP) has an half-life considerably inferior to the age of the Earth, we can assume that its concentration on the Earth has become too low to be traceable (almost exhausted). The exhaustion of the longest-lived member leads necessarily to the exhaustion of the whole series, which quite soon becomes transformed in the last, stable, member of te series. So, if we want to observe the series again, we are obliged to obtain the longest-lived member, the "parent" of the other members, following an artificial process, i. e. performing a nuclear reaction.
So we can say: the presence of artificial radiosotopes is possible in the neptunium series.​

But, as you can see, the formulation of the problem statement is rather "strange" for my solution (but that could be quite normal for the teacher who gave me this assignment), although other ideas I've formulated sound even more absurd. Moreover, the book I'm using to study (which is by the same author of the problem we are dealing with) doesn't mention the neptunium series at all, pointing towards other possible solutions, but what?

Could you help me? Do you agree with my solution or have any other idea?

Thank you very much

 

[Jhero]

for your attention and for your help!


Thank you for your post. It seems like you have put a lot of thought into your solution and it is definitely a valid interpretation of the problem statement. However, there are other possible solutions as well.

One possible interpretation of the problem statement is that it is asking for a series in which artificial radioisotopes are present naturally, rather than being produced artificially. In this case, the answer would be the actinium series, as it contains the naturally occurring radioisotope 227Ac, which is produced through the decay of the artificial radioisotope 235U. This is known as a primordial radionuclide, meaning it has existed since the formation of the Earth.

Another interpretation could be that the problem is asking for a series in which artificial radioisotopes are present in significant quantities. In this case, the answer could be the thorium series, as it contains the artificial radioisotope 232Th which has a half-life of over 14 billion years, making it a major contributor to the Earth's natural radioactivity.

I would recommend discussing your interpretation with your teacher or classmates to see if they have any additional insights. It's always helpful to get different perspectives when tackling a problem.

Best of luck on your test next week!