An atom trap system for practical {sup 81}Kr dating
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 and Physics Department, Northwestern University, Evanston, Illinois 60208 (United States)
{sup 81}Kr (t{sub 1sol2}=2.3x10{sup 5} yr, {sup 81}Kr/Kr{approx}6x10{sup -13}) is a long-lived cosmogenic isotope, which is ideal for dating old groundwater and ice in the age range of 50,000 years to 1 million years. Here, we describe the apparatus and performance of an atom-counting system for practical {sup 81}Kr dating. This system is based upon the atom trap trace analysis method that was first demonstrated in 1999. Since then, significant improvements have been made to increase the system efficiency and to reduce the required krypton sample size. For a modern krypton gas sample of 100 {mu}l STP, which contains 1.2x10{sup 6} {sup 81}Kr atoms, the system can accumulate approximately 240 {sup 81}Kr counts in 20 h, thereby reaching a counting efficiency of 2x10{sup -4}. Detailed studies have been conducted to characterize the performance of this system. This system has been calibrated with a low-level counting method and has been used for {sup 81}Kr dating of ancient groundwater from the Nubian Aquifer (Egypt). It can also be used to measure the isotopic abundance of a fission-produced isotope {sup 85}Kr (t{sub 1sol2}=10.76 year,{sup 85}Kr/Kr{approx}2x10{sup -11})
- OSTI ID:
- 20636622
- Journal Information:
- Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 10 Vol. 75; ISSN 0034-6748; ISSN RSINAK
- Country of Publication:
- United States
- Language:
- English
Similar Records
Dating technique tested
Analysis of /sup 81/Kr in groundwater using laser resonance ionization spectroscopy