Scientists from the Los Alamos Neutron Science Center have produced the most precise single measurement of the free neutron lifetime to date. They timed it in at 877.83 seconds, with the error margin of under 0.3 seconds. This incredible accomplishment marks the new world record of the most accurate precision neutron lifetime measurement. It provides vital hints to answers to deeper questions at the heart of particle physics.
The free neutron lifetime plays a pivotal role in exploring the nature of the weak force, one of the four fundamental forces governing interactions in the universe. Making the next great discovery in physics will require a deep understanding of this lifetime. It might make unexpected discoveries outside the already proven Standard Model.
The team spent five years collecting data, adding in the data from an extra three years of prior experiments to improve accuracy. Their findings were published in the peer-reviewed journal Physical Review C, solidifying their contribution to ongoing discussions in particle physics.
Significance of Neutron Lifetime Measurement
The significance of free neutron lifetime measurement extends beyond scientific curiosities. Yet it is absolutely central to our ability to tackle some of the biggest open questions in fundamental physics. The weak force is very important in some processes, such as beta decay. It is critical for understanding how all particles fundamentally interact at the most basic level.
Steven Clayton, a key member of the research team, noted, “The precise lifetime of free neutrons is at the center of still-contested physics questions.” It’s a testament to the importance of their work that they are primarily responsible for helping us develop a more thorough understanding of the universe.
Now that they have that precision, researchers at LHC and elsewhere are looking to test a number of theories about how the weak force works. Clayton introduced our ambitions. In the process, we hope to learn how to characterize and quantify systematic uncertainties in the experiment and earn improve the lifetime statistical precision. At this degree of accuracy, we’ve brought the existing design as far as it will carry.
Advancements in Experimental Techniques
While this was a major step forward, the research team succeeded by dramatically improving experimental design. This scientific progress is most exemplified by our Ultracold Neutron Facility. The facility provided greater control over experimental conditions when measuring neutron decay, thus ensuring a higher level of reliability in their findings.
Maninder Singh, another researcher involved in the project, described some of the technical challenges they faced, stating, “The elevator itself was challenging to design and execute because it has to form a seal as it backs up, and we needed any gaps to be reasonable.” These innovations played a critical part in allowing them to achieve their record-breaking precision.
The team has big plans for upcoming at-sea experiments. They hope to get their new experimental beta UCNTau+ up and running in the near future. This new design aims for a reproducible increase of ultracold neutron density by a factor of five to ten. Our long-term goal is to reduce this largest systematic uncertainty by a factor of ten. For each station, we want to get to an overall uncertainty of only 0.1 seconds.
Implications for Future Research
Such a precise measurement has massive implications. This opens up exciting new avenues for probing physics beyond what we currently understand. While these results confirm the UCNtau design approach, the successful construction of this complex experiment identifies paths for effective further design iteration.
Clayton emphasized this potential for future studies: “Our results here validate the UCNtau experimental approach and point the way toward design improvements that will further enhance our understanding of the physics involved.” As this research continues, it may produce discoveries that break or go beyond the current theories of particle physics.