Mass measurement on the rp-process waiting point 72Kr

Area of Science:

• Nuclear Astrophysics
• Stellar Nucleosynthesis
• Exotic Isotope Research

Background:

• The rapid proton-capture (rp) process is crucial for synthesizing heavier elements in stars.
• Waiting points in the rp process, such as Krypton isotopes, significantly influence reaction flow and nucleosynthesis outcomes.
• Accurate mass measurements of these waiting points are essential for understanding stellar evolution and element production.

Purpose of the Study:

• To precisely measure the mass of the 72Kr isotope, a key waiting point in the astrophysical rp process.
• To improve the accuracy of mass measurements for 73Kr and 74Kr for enhanced astrophysical calculations.
• To reevaluate the impact of 72Kr on the duration of X-ray bursts based on new mass data.

Main Methods:

• Utilized the ISOLTRAP Penning trap mass spectrometer for high-precision mass determination.
• Measured the mass of 72Kr for the first time with a relative uncertainty of 1.2x10(-7).
• Achieved over an order of magnitude improvement in mass accuracy for 73Kr and 74Kr.

Main Results:

• The first direct mass measurement of 72Kr was successfully performed.
• The mass of 72Kr was determined with a precision of 8 keV.
• Improved mass data for 72-74Kr confirmed 72Kr as a significant waiting point, extending X-ray burst durations.

Conclusions:

• 72Kr acts as a strong waiting point in the rp process, significantly delaying X-ray burst durations.
• The beta-decay half-life of 72Kr (17.2 s) is a critical factor in its role during X-ray bursts.
• Precise mass measurements are vital for accurate modeling of explosive nucleosynthesis and understanding elemental abundances in the universe.