Doppler and Sympathetic Cooling for Ultra-High Precision Mass Spectrometry of Short-Lived Radioactive Ions

Objective

This project aims to push the precision frontier in nuclear physics by enabling ultra-high-precision mass measurements of short-lived isotopes produced at radioactive ion beam (RIB) facilities to probe the limits of the Standard Model (SM). Such high-precision mass measurements, targeting relative uncertainties in the order of 10^(-11), are central to beyond the Standard Model (BSM) investigations including tests of Cabibbo–Kobayashi–Maskawa (CKM) matrix unitarity, King-plot nonlinearity studies for fifth force searches, and ultra-low Q-value measurements relevant to neutrino mass determination. Current state-of-the-art Penning trap mass spectrometers installed at RIB facilities, such as JYFLTRAP at the IGISOL facility at the University of Jyväskylä, can achieve a relative mass precision slightly below 1⋅10^(-9) for room-temperature ions. Recent simulations show that the precision of Penning trap mass spectrometry can be improved by more than an order of magnitude when reducing ion temperatures to below 1 K. While Doppler and sympathetic cooling has been a standard method of reducing temperatures of ions to sub-Kelvin temperatures for decades, its potential for cooling of short-lived radioactive ions has so far not been harnessed, except for a few specific cases. This project will pioneer the use of Doppler and sympathetic cooling for radioactive ions, preparing ultracold beams for injection into the JYFLTRAP Penning trap at the University of Jyväskylä. The first science case will be a high-precision Q-value measurement of 26mAl, a key nucleus for testing the CKM matrix unitarity. A new Q-value measurement at an order of magnitude higher precision will significantly improve the global V_ud CKM matrix element. Generally, the pioneering use of ultracold radioactive ions will establish a new precision regime in mass spectrometry of short-lived radioactive ions, opening a powerful new avenue for low-energy nuclear physics tests of the Standard Model.