The IceCube Neutrino Observatory, or IceCube, is a massive cubic-kilometer detector embedded deep in the Antarctic ice at the South Pole that explores fundamental questions in physics and astronomy. For the first time since its inception in 2010, IceCube has just completed an upgrade consisting of adding over 600 new detectors to the existing 5,160 which were installed more than 15 years ago. This upgrade, along with the continued collaboration of Physics faculty and students from Drexel University, should lead to more information on neutrinos, or “ghost particles” as they are sometimes referred to, and pave the way for more cosmic discoveries.
Drexel’s Naoko Kurahashi Neilson, PhD, a professor in the College of Arts and Sciences, and her research team have been studying findings from IceCube over the last decade. They were able to show that neutrinos originate from blazars – giant, oval-shaped galaxies theorized to have spinning supermassive black holes at their center that blast out radiation. Further research, in which Neilson served as lead author, showed that there is strong evidence of other neutrinos coming from a specific blazar, which can be seen in the night sky just off the left shoulder of Orion. Her team was also able to produce new, neutrino-based images of the Milky Way Galaxy.
Christina Love, PhD, an associate teaching professor of physics in the College of Arts and Sciences, was instrumental in creating the “Name that Neutrino” project, which invited the public to help scientists classify data signals from IceCube’s observatory at the South Pole.
Neilson and Love spoke with the Drexel News Blog about the IceCube upgrade and what it means for neutrino discoveries and science going forward.
What has IceCube accomplished over the last 15 years since its formation?
Love: IceCube discovered the first high-energy neutrinos from beyond our solar system, showing that powerful cosmic objects send these tiny particles across the universe to Earth. Since then, IceCube has identified likely source candidates, measured neutrino properties with high precision, searched for dark matter and other new physics, and established neutrino astronomy as a new way to study the extreme universe.
Why did it take seven years to complete the upgrade?
Love: In order to both lower our detector threshold and improve calibrations, we needed to rethink our hardware. Much of the last seven years was dedicated to developing and producing this new hardware. Unlike the previous IceCube strings, the upgraded strings contain a wide variety of new types of hardware, including hundreds of multi-PMT) modules (photomultiplier tubes which are extremely sensitive detectors of light, cameras to study the refreezing process, seismometers and precision calibration devices. The project was also delayed due to the COVID-19 pandemic.
How will the IceCube upgrade impact new (and old) IceCube results?
Love: The IceCube upgrade will significantly improve the number of neutrinos detected, and it will also provide much more detailed “pictures” of the neutrino interactions. These will allow us to more easily determine the initial properties of the neutrinos, such as where they came from. With these extra events and more detailed event information, IceCube will be able to more precisely measure fundamental parameters in nature, such as the mysterious oscillation properties of neutrinos. We will also double our sensitivity to the neutrino mass ordering. It will also allow us to improve limits on searches for astrophysical sources of neutrinos and for neutrinos from dark matter.
What will Drexel’s involvement in the project be going forward?
Kurahashi Neilson: Drexel has played a significant role in many of IceCube’s most important discoveries, contributing expertise in data analysis, event reconstruction and innovative computational approaches. We will continue to build on that leadership by advancing targeted machine learning methods that sharpen how we identify and interpret neutrino signals. Central to this effort is Name that Neutrino, the largest IceCube citizen science project, led by associate teaching professor Christina Love, which combines broad public participation with cutting-edge analysis to strengthen both our science and our impact.
Why do we want to study high-energy neutrinos?
Love: Despite years of study by talented teams of astronomers using highly precise telescopes, we still do not completely understand the universe’s most extreme environments. Unfortunately, these locations—mergers producing gravitational waves, the regions around supermassive black holes, the accelerators of cosmic rays, etc.—are often obscured, making it difficult for traditional telescopes to tell us what is occurring. Neutrinos produced in these locations are not as easily obscured, giving us a unique view into the physics of these environments.
Reporters interested in speaking with either Kurahashi Neilson or Love should contact Mike Tuberosa, assistant director, News & Media Relations, mt85@drexel.edu or 215.895.2705.
