Commissioning of the collinear laser spectroscopy facility BECOLA at NSCL/MSU

The BEam COoler and LAser spectroscopy (BECOLA) facility at National Superconducting Cyclotron Laboratory at Michigan State University has been commissioned online to determine charge radii and electromagnetic moments of radioactive isotopes. A radioactive 37K beam was used for the commissioning tests and a 1.29 μs beam bunch-width from the buncher and a bunch repetition rate of 2.5 Hz led to a background suppression factor of 3.1 × 105 in resonant photon detection measurements. The hyperfine structure of 37K and its isotope shift relative to the stable 39K were determined. The obtained hyperfine coupling constants A(2 S 1/2) = 120.3 ± 1.4 MHz, A(2 P 1/2) = 15.2 ± 1.1 MHz, and A(2 P 3/2) = 1.4 ± 8 MHz, and the isotope shift δ ν 39,37 = −264 ± 3 MHz are consistent with the previously determined values, where available.