Nuclear data sheets for A = 107

Dating and environment using long-lived radionuclides

“…Since by now some environmental parameters are clearly affected by man (e.g. the concentration of important trace gases Be, 10 Be, 14 C, 26 Al, 32 Si, 36 Cl, 39 Cl, 41 Ca, 44 Ti, 59 Ni, 60 in the atmosphere such as O 3 , CO 2 , and CH 4 ), we are most concerned that we disturb the environment in a way Nature will not be able to cope with. The basis for a better assessment of the overall environmental situation is a clear understanding of the natural variations in the past.…”

“…Suddenly it was possible to make 14 C measurements with as little as one milligram of carbon as compared to gram amounts needed for the classical beta-counting method. In addition to 14 C many other radionuclides with even longer half-lives such as 10 Be, 26 Al, 36 Cl, 41 Ca and 129 I became available through AMS [4]. The combination of long half-lives (D10 5 years) and extremely low isotopic abundances (10 212 to 10 215 ) make these radionuclides virtually unmeasurable through beta-decay counting.…”

“…Unfortunately, these attempts failed primarily because 41 Ca is distributed unevenly in the environment. The production through the 40 Ca(n, g) 41 Ca reaction happens at the surface of rocks and soil. Without forming a chemically long-lived gas like 14 CO 2 providing a well mixed reservoir, it is perhaps not surprizing that 41 Ca / 40 Ca ratios were found to vary by more than an order of magnitude in modern samples [73].…”

“…-The long half-life of 41 Ca (1.04 3 10 5 y) and its presence in bone inspired attempts [72] to use it for archaeological dating in analogy to radiocarbon, but with the prospect to go back much further in time. Unfortunately, these attempts failed primarily because 41 Ca is distributed unevenly in the environment. The production through the 40 Ca(n, g) 41 Ca reaction happens at the surface of rocks and soil.…”

“…The production through the 40 Ca(n, g) 41 Ca reaction happens at the surface of rocks and soil. Without forming a chemically long-lived gas like 14 CO 2 providing a well mixed reservoir, it is perhaps not surprizing that 41 Ca / 40 Ca ratios were found to vary by more than an order of magnitude in modern samples [73]. In addition, the low natural 41 Ca/ 40 Ca ratios in the range of 10 214 combined with the difficulty to form negative ions for Ca make it an exceptionally challenging case.…”