Determining Neutrino Mass by means of Electron Behavior
The Project 8 experiment utilizes the beta decay of radioactive tritium to track neutrino mass. By converting one of these neutrons into a proton, tritium rots to helium while giving off an antineutrino and an electron.
” And heres the kicker,” stated Professor Martin Fertl. “Since neutrinos and their antiparticles have no electrical charge, they are really challenging to find. Therefore, we do not even attempt to detect them. Rather, we measure the energy of the resulting electrons through their orbital frequency in an electromagnetic field. Based upon the shape of the energy spectrum of the electrons, we then determine the neutrino mass, or set a ceiling on that mass in this method.”
The Precision of CRES
To obtain reliable outcomes, the energy of the electrons must be determined exceptionally precisely. This is because the resulting (anti) neutrino is incredibly light, a minimum of 500,000 times lighter than an electron.
” When neutrinos and electrons are produced at the same time, the neutrino mass has only a small impact on the electrons movement. And we wish to see this little effect,” explained Professor Sebastian Böser.
The method that makes this possible is called Cyclotron Radiation Emission Spectroscopy, CRES for brief. It registers the microwave radiation given off by the nascent electrons when they are forced into a circular course in a magnetic field. The frequency of the released radiation can be identified exceptionally specifically and then the mass of the neutrino can be presumed from the electron energy.
To make this work, Christine Claessens has actually made a decisive speculative contribution: “As part of my doctoral thesis, I established, amongst other things, an occasion detection system including a real-time trigger and an offline event restoration. This system look for the particular CRES features in the constantly digitized and processed radio frequency signal. Reconstruction of the start frequency of each electron event allows high-precision recording of a tritium decay spectrum.”
Experimental Results
On this basis, Claessens was successful in examining the first tritium spectrum taped with CRES with respect to methodical uncertainties– and thus in calculating a first upper limit for the neutrino mass with this new innovation, which has now found its method into the most recent publication.
There, the Project 8 partnership specifically reports 3,770 tritium beta decay events that were registered over a duration of 82 days in a sample cell the size of a single pea. The sample cell is cooled to really low temperatures and placed in a magnetic field that causes the getting away electrons to take a trip in a circular course long enough for the detectors to sign up a microwave signal. Crucially, no incorrect signals or background events are signed up that might be mistaken for or mask the genuine signal.
” The resulting newbie determination of the ceiling for the neutrino mass with a simply frequency-based measurement method is an extremely promising outcome, given that we can determine frequencies really precisely nowadays,” concluded Professor Sebastian Böser and Professor Martin Fertl.
The Next Steps Are Already Underway
After the successful proof of principle, the next step is prepared: For the last experiment, the researchers need private tritium atoms, which they create from the fission of tritium molecules. This is challenging since tritium, like hydrogen, chooses to form molecules. Developing such a source– first for atomic hydrogen and later for atomic tritium– is an important contribution of the Mainz team.
At the moment the Project 8 cooperation, that includes members from 10 research organizations worldwide, is dealing with testing designs for scaling up the experiment from a pea-sized sample chamber to one a thousand times larger. This will enable much more beta decay occasions to be registered. At the end of a multi-year research and advancement program, the Project 8 experiment need to eventually surpass the sensitivity of previous experiments– such as the current KATRIN experiment– to supply a value for neutrino mass for the very first time.
For more on this research study, see Project 8 Is Closing In on the Elusive Neutrino.
Recommendation: “Tritium Beta Spectrum Measurement and Neutrino Mass Limit from Cyclotron Radiation Emission Spectroscopy” by A. Ashtari Esfahani et al. (Project 8 Collaboration), 6 September 2023, Physical Review Letters.DOI: 10.1103/ PhysRevLett.131.102502.
Project 8 has actually innovatively used Cyclotron Radiation Emission Spectroscopy to observe electron behavior in tritium decay, setting a ceiling for neutrino mass. This marks progress in an enduring difficulty in particle physics, with the possible to enhance our understanding of deep spaces evolution.
Task 8 experiment reaches important turning point to determine neutrino mass.
Neutrinos are common primary particles that communicate just very weakly with normal matter. For that reason, they normally permeate it unrestricted and are hence also called ghost particles. Neutrinos play a primary role in the early universe. In order to fully describe how our universe developed, we require above all to know their mass. But so far, it has actually not been possible to identify this mass.
Job 8s Novel Approach
The global Project 8 collaboration desires to alter this with its new experiment. For the very first time, Project 8 is utilizing a completely new technology, the so-called Cyclotron Radiation Emission Spectroscopy (CRES), to figure out the neutrino mass.
In a current publication in Physical Review Letters, the Project 8 collaboration has now had the ability to show that the CRES approach is undoubtedly suitable for figuring out the neutrino mass and has currently set a ceiling for this basic quantity in a first measurement– an essential milestone has hence been reached. From Johannes Gutenberg University Mainz (JGU), the research groups of Professor Martin Fertl and Professor Sebastian Böser are involved, both researchers at the Cluster of Excellence PRISMA+. Dr. Christine Claessens, a former PhD student of Sebastian Böser and now a postdoc at the University of Washington in Seattle in the USA, made a vital contribution to the existing publication as part of her PhD thesis.
In a recent publication in Physical Review Letters, the Project 8 partnership has actually now been able to reveal that the CRES approach is undoubtedly appropriate for determining the neutrino mass and has actually currently set an upper limit for this essential amount in a very first measurement– an important turning point has actually therefore been reached. The Project 8 experiment uses the beta decay of radioactive tritium to track neutrino mass. Based on the shape of the energy spectrum of the electrons, we then identify the neutrino mass, or set an upper limit on that mass in this way.”
The frequency of the released radiation can be figured out exceptionally specifically and then the mass of the neutrino can be inferred from the electron energy.
At the end of a multi-year research study and development program, the Project 8 experiment need to ultimately go beyond the level of sensitivity of previous experiments– such as the existing KATRIN experiment– to provide a value for neutrino mass for the very first time.
