Latest effort to weigh the elusive particle produces a more precise estimate of its upper limit.
. The experiment has so far been able to put only an upper bound on the mass. But researchers say that it might be able to make a definite measurement once it finishes collecting data in 2024, and is the only experiment in the world capable of doing this.
The electron carries almost all of the energy released during the tritium’s decay, but some is lost with the neutrino. The value of this shortfall can be used to calculate the particle’s mass.KATRIN’s 2019 results were based on an initial run of the experiment in April and May that year, when the tritium beam was operating at one-quarter of its full strength. The latest result is based on data from the first full-strength run, which took place later in 2019. These data imply an upper bound of 0.