An Improved Atom Trap Trace Analysis Instrument for ⁴¹Ca

The in-situ cosmogenic radionuclide ⁴¹Ca, with a half-life of approximately 100,000 years, is regarded as a promising chronometer for the Middle to Late Pleistocene. However, the extremely low isotopic abundance of ⁴¹Ca (10⁻¹⁸–10⁻¹⁴) poses a challenge for analytical techniques. While atom trap trace analysis (ATTA), a laser-based ultra-sensitive technique, offers a new approach for ⁴¹Ca detection, the low atom counting rate has remained a limiting factor for practical ⁴¹Ca dating applications. This work presents an improved ATTA instrument based on a high-intensity atomic beam source. The new system has an atom counting rate of one order of magnitude higher than previous work, pushing the lowest measurable ⁴¹Ca/Ca ratio down to 1×10⁻¹⁸.