A while back, this thread strayed into my territory, here is a little background on the decay series that end with Nd142.
Nd142 can come from 4 different isotopes.
1) Ce142 (HL 5.0 E16 Years)We can pretty much rule that out as nothing much is coming down that route in 4 Billion years.
2) Pr142 (HL 19.12 hours) Not found in nature and has no parent.
3) Pm142 (HL 40.5 Seconds)
4) Sm146 (HL 1.03 E8 years) Not found anywhere.
Not including Sm146 this only leaves 1 possible decay path leading to Nd142 and that is via the short lived isotope Pm142. This path can be traced back through a series of short lived isotopes (each less than an hour) to Dy143 and Ho144. Neither of these have any parents.
In short this means that
all Nd142 had to have come from the decay path leading through Sm146.
Sm146 actually has several decay paths leading into it. One of which is another conspicuously missing isotope Gd150 with a half life of 1.75 million years.
I haven't bothered tracing it back any further as it would be a wasted effort.
If anyone would like to do so all the available information about the nuclides is available
here. Just type in the isotope of interest and it will tell you the parents, decay paths etc.
PY
This message has been edited by PurpleYouko for spelling, 12-13-2004 02:11 PM
This message has been edited by PurpleYouko, 12-13-2004 02:13 PM
™ Version 4.2
