Los Alamos and the long path to detecting neutrinos

https://www.lanl.gov/media/publications/1663/from-ghost-particle-to-cosmic-messenger

by LAsteNERD • 3 months ago

45 5 3 months ago

LAsteNERD• 3 months ago

Neutrinos were originally proposed as a “desperate remedy” to fix missing energy in nuclear decay, but turned out to be real—just incredibly hard to detect. Tens of quadrillions can pass through matter before one interacts. Los Alamos physicists (Reines and Cowan) confirmed their existence in 1956 using a nuclear reactor as a source. Since then, neutrino experiments have repeatedly exposed gaps in the Standard Model—like neutrino oscillations, which proved they have mass, and ongoing hints at possible “sterile” neutrinos. What’s interesting is how detection capability drove the science: better detectors led to unexpected anomalies which led to new physics. Today, neutrinos are used as probes of everything from stellar processes to matter–antimatter asymmetry, and experiments are still chasing open questions like whether neutrinos are their own antiparticles.

rdtsc• 3 months ago

The Soviet detector mentioned is probably https://en.wikipedia.org/wiki/Baksan_Neutrino_Observatory

There is a tour of it on youtube https://www.youtube.com/watch?v=J5jhp74Uw54 if you happen to speak some Russian. The scintillator array part starts around 22min

peterldowns• 3 months ago

Neutrino research is so cool. SNO+ is entering a new phase this year, with a new scintillator fluid that might allow us to determine their Majorana status. Always cool to realize how much is still unknown, and how tenuously we “know” anything.

rramadass• 3 months ago

Right. It is amazing how everything in Physics now seems to be based on our understanding of Atomic Physics/Quantum Effects. Perhaps we should revise our physics curricula to start with atomic theory.

The article reads like "magic" to the common man. For example; if electron neutrino's measured mass were to be around 26 electronvolts (eV) what does it mean to say "If true, it would “close the universe,” meaning it would ascribe enough mass and energy to the universe to eventually halt its expansion and reverse it." A lot for the curious to process and study.

PS: Folks interested in studying Atomic Physics might find this free ebook useful; Atomic Physics for Everyone: An Introduction to Atomic Physics, Quantum Mechanics, and Precision Spectroscopy with No College-Level Prerequisites - https://news.ycombinator.com/item?id=46961595

frumiousirc• 3 months ago

A follow-on experiment, called MicroBooNE, was built specifically to look for sterile neutrinos, and in late 2025, it reported no evidence of the expected signatures. But absence of evidence is not evidence of absence.

Yes, but exclusion regions are.

Los Alamos and the long path to detecting neutrinos

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