Commissioning of the LSU-Argonne Conversion Electron Spectrometer

A collaboration between Louisiana State University (LSU) and Argonne National Laboratory (ANL) has developed a program of internal conversion electron (CE) spectroscopy to complement the strong decay spectroscopy program at the Argonne Tandem Linac Accelerator System (ATLAS)/Californium Rare Ion Breeder Upgrade (CARIBU). Internal Conversion Electron (ICE) spectroscopy is an established experimental method that has been used to determine transition multipolarities, the spin and parity of the energy levels, and uniquely able to observe electric monopole (E0) transitions between 0⁺ states.

The LSU-Argonne Conversion Electron Spectrometer (LACES) is a 200 mm² by 5-mm thick LN₂-cooled Si(Li) detector system designed to be coupled to the X-Array HPGe detectors and the Scintillator and Tape Using Radioactive Nuclei (SATURN) moving tape collector system at ATLAS at ANL. LACES will be used to study the low-spin K^π = 1⁺ isomeric state at 150.3-keV of the deformed, odd-odd nucleus ¹⁵⁶Pm via ¹⁵⁶Nd beta decay from CARIBU beams.  Also, the low-energy efficiency will be measured from the beta decay of ¹⁴¹Cs and ¹²⁸Sn. The LACES design, upgrades to the X-Array/SATURN system, performance and preliminary commissioning data will be presented.

*Supported by Louisiana State Board of Regents RCS LEQSF(2016-19)-RD-A-09, the U.S. Department of Energy, Office of Nuclear Physics, under Award No. DE-AC02-06CH11357 (ANL) and DE-SC0021315 (LSU).