How do you detect a neutrino smashing into a nucleus?

Kate Scholberg, a particle physicist and author on the study, describes how the COHERENT Collaboration able to catch this event with a detector the size of a breadbox.

Vocabulary: nucleus, neutrino, wavelength, subatomic particles, detector, neutron, proton

Next Generation Science Standards: PS1.C: Nuclear Processes, SEP2: Developing and Using Models, CC1: Patterns, CC4: Systems and System Models. Can be used to build towards HS-PS1–8.

Common Core State Standards: CCSS.ELA-LITERACY.RI.6.4, CCSS.ELA-LITERACY.RI.7.4, CCSS.ELA-LITERACY.RI.8.4, CCSS.ELA-LITERACY.RI.9–10.4, CCSS.ELA-LITERACY.RI.11–12.4

Neutrino, via Shutterstock

Neutrinos are known as the “ghost particle.” Even though countless numbers of the subatomic particles rain down from the sun, supernovae, and other cosmic sources every second, they are difficult to detect because of their weak interactions with matter. Physicists at the Oak Ridge Laboratory were able to take the first measurement of a neutrino interacting with the nucleus of an atom. Their results were published this week in the journal Science.

Neutrino detectors that hunt for high-energy cosmic neutrinos are often larger apparatuses buried deep underground. But this group of scientists used a small detector that captured low-energy neutrinos coming from a man-made source. Kate Scholberg, a physicist and an author on that study, describes how the team was able to capture this elusive process, and how this observation could be used as a model for understanding neutrinos formed from cosmic sources.

Audio Excerpt “Neutrinos Caught In The Act Of Collision,” August 4, 2017. (Original Segment)

Print this segment transcript.

Questions

  • Why do the neutrinos need to be at “low energy” for this collision to be observed?
  • Juan Collar, who worked on the development of the neutrino detector, refers to this as the “…marriage of an ideal source and an ideal detector….” Explain how the source and detector worked together to create an ideal experimental environment.
  • Kate explained the interaction of the neutrino with the nucleus in terms of ping pong balls and a bowling ball. Evaluate the model: what are some of the limitations of that analogy when explaining the interaction between a neutrino and a nucleus?
  • Based on the interview, why do you think neutrinos are called “ghost particles?”
  • You might not be able to measure neutrino and nucleus collisions, but you can try a real version of Kate’s bowling ball and ping pong ball analogy. Brainstorm ways to measure the recoil of the ping pong ball or the tiny bump the bowling ball gets from the ping pong ball.

Activity Suggestions

  • Have students observe the radioactive particles all around them using this activity where they build a cloud chamber using a clear container, dry ice, and a little rubbing alcohol. Then have students test their hand at engineering cosmic ray shielding, which they can test using their cloud chamber.

Additional Resources

This photographer turns particle physics into art!

One of the world’s largest neutrino telescopes is in Antarctica.