Assistant Professor Jones
Dr. Benjamin Jones
Assistant Professor of Physics
Location: Room 102B SH
My research focuses on experimental neutrino physics, and is driven by the possibility that detailed study of neutrinos may be the key to revealing fundamental truths about cosmology and particle physics. I presently focus on two main research topics:
Searching for neutrinoless double beta decay with high pressure xenon gas.
Most massive particles in nature are charged under the electromagnetic, strong or weak forces. For each such particle that may exist, a corresponding anti-particle with all opposite charges may also exist. The neutrino is the only particle in nature that has no conserved charges, and this allows for the strange possibility that the neutrino may be neither matter nor antimatter, but something in between – a Majorana fermion. If the neutrino can be shown to be a Majorana fermion, it would have profound implications for particle physics and cosmology. It would hint at an energy scale of new physics beyond the standard model through the 5-dimensional Weinberg operator; it would also enable a mechanism called leptogenesis, which may explain why the Universe contains matter and very little antimatter – and thus why galaxies, solar systems, planets and their inhabitants may exist.
Figure 1: Left – tracking and energy plane of the NEXT-NEW detector. Right: simulated neutrinoless double beta decay event in NEXT.
The only known way to show that neutrinos are Majorana fermions is through the detection of an extremely rare radioactive process called neutrinoless double beta decay. In this process, a nucleus of a candidate isotope decays to produce two electrons and no neutrinos in the final state. This may only occur if the neutrino is its own antiparticle, and is projected to happen at rates as low as once per ton of material per year. Robustly detecting this process requires exquisite background rejection methods to remove gamma and beta decay backgrounds. We work to develop new detector technologies that can search for this process under these extremely challenging conditions. In particular, we believe the high pressure xenon gas TPC with electroluminescent gain shows particular promise due to its ability to reconstruct events with exquisite energy resolution and topological discrimination, and we are making major contributions to the joint US-European NEXT program. We are also developing new background rejection techniques based on biochemical microscopy methods applied to particle detectors to reach the zero background regime.
Figure 2: graduate student Austin McDonald assembling a barium-tagging test stand which uses biochemistry techniques to search for neutrinoless double beta decay
Searching for new neutrino physics using atmospheric neutrinos at IceCube
The IceCube experiment is a one-billion-ton neutrino telescope formed from instrumented ice at the South Pole. IceCube was designed to discover astrophysical neutrinos produced in some of the most violent objects in the Universe, and succeeded in this goal in 2013, thus opening the field of high energy neutrino astronomy. As well as a telescope, IceCube is also a detector for atmospheric neutrinos, which are far more copious than their astrophysical counterparts. Studying these neutrinos, which are copiously detected in the 1-100 TeV energy range, allows world-leading measurements of neutrino properties.
Figure 3: left: The IceCube array in the deep transparent ice at the South Pole. Right: An IceCube digital optical module being deployed into a 3km deep hot-water-drilled hole.
Our group works on searches for new physics including sterile neutrinos using the IceCube detector. Sterile neutrinos are hypothetical new particles, suggested by anomalies in short-baseline neutrino oscillation experiments. Confirmation of the existence of sterile neutrinos would be a profound discovery, extending the neutrino sector of the standard model with new and unexpected particles, enhancing the richness of the weak flavor structure.
IceCube searches for sterile neutrinos through a unique quantum mechanical effect, the MSW resonance, which leads to amplification of oscillations that would typically be small in conventional experiments. IceCube is thus an extremely powerful tool for sterile neutrino searches. The analysis I developed presently holds the world's strongest limit. We are extending this analysis to five times more data, and exploring new channels for sterile neutrino detection, as well as new physics discovery channels using high energy atmospheric neutrinos.
Figure 4: Results of the 1-year sterile neutrino analysis at IceCube, compared to anomaly regions and other published exclusion limits.