Quantify environmental broadening in the BeEST electron-capture recoil spectrum

Quantify the contributions of structural and chemical variations of the lithium 1s binding energy at different tantalum lattice sites to the broadening of the K-shell capture to ground-state recoil peak in the BeEST electron-capture decay spectrum of 7Be, so as to disentangle environmental broadening from quantum uncertainty in the measured energy width.

Background

The experiment measures the energy width of the 7Li recoil associated with K-shell electron capture to the ground state, using superconducting tunnel junction sensors. The observed width includes both intrinsic quantum uncertainty and possible environmental effects from the host material.

The authors note that structural and chemical variations in the tantalum lattice can produce order-eV broadening through variations in the Li 1s binding energy, but these contributions have not yet been quantified for the BeEST energy spectrum. A precise quantification is needed to separate environmental effects from true quantum uncertainty in the recoil energy width.