Most of the energy of a collapsing supernova is radiated in the form of neutrinos, produced when … [+]
As a subatomic byproduct of radioactive decay, the tiny neutrino was not even theorized to exist until nearly a century ago. Italian for little neutral one, it’s a fundamental particle with no internal parts and no electric charge.
Both harmless and ubiquitous, an estimated 300 relic neutrinos dating from trillionths of a second after the big bang pass through your pinky finger every second. And because they only rarely interact with ordinary matter, they can also pass through stars and planets like a hot knife slicing through butter.
Although they’ve yet to give up all their secrets, a captivating new book, “Ghost Particle: In Search of the Elusive and Mysterious Neutrino,” brings us up to speed on what we humans have gleaned about them since 1930. Co-authors Alan Chodos, a research professor at the University of Texas at Arlington and noted science journalist James Riordon dissect what we have learned about the neutrino and how we might harness them for all forms of applied science.
Produced naturally via gamma ray bursts, supernovae, nuclear reactions in our own star, and particle decay deep within Earth, they are also byproducts of particle accelerators and present-day nuclear reactors. Perhaps, most chillingly, they were first detected as an aftereffect of 1940s nuclear weapons tests in New Mexico.
Here are five takeaways from the book.
—- Probing the cosmic neutrino background back near the beginning of time
The cosmic neutrino background dates to about one second after the big bang. If such relic neutrinos could be studied, the authors note that they would reveal the earliest universe in a way that has heretofore eluded cosmologists.
But detecting this early neutrino background is still a work in progress. The proposed Princeton Tritium Observatory for Light, Early- universe Massive- neutrino Yield (PTOLEMY) could reveal this neutrino background by looking for tritium samples that display electrons with slightly elevated energy levels, note the authors.
The idea is to use some 100-grams of tritium, about a quarter of the commercially available annual supply to distinguish between electrons coming from natural tritium decay and the ones induced by relic neutrinos, the authors note. But this would be no small feat and would require a precision measurement of one part in 50,000.
Ghost Particle
—- Using neutrinos as a supernova early warning system
The first neutrinos detected from a star about to go supernova happened 36 years ago. That was only a few hours before the now famous supernova 1987A burst forth in our neighboring dwarf galaxy, the Large Magellanic Cloud.
The few neutrinos that turned up in the three terrestrial detectors back then were a minuscule portion of the ones that came out of the 1987 supernova, the authors note, since about 99 percent of a supernova’s energy goes into neutrinos.
The idea is to use the existing Super Nova Early Warning System (SNEWS 2.0) network to identify stars about to go supernova. By looking at the timing of signals in neutrino detectors, SNEWS 2.0 can triangulate to locate the region of the sky where a supernova is about to appear, Chodos and Riordon write.
The hope is that this burgeoning the network of ground-based neutrino observatories will soon reveal pre- supernova neutrinos as far away as the center of the Milky Way galaxy, write the authors.
—- Using neutrinos to catch nations violating nuclear nonproliferation agreements
United Nations nuclear inspectors don’t always get ready access to monitor a given country’s nuclear reactors, which can also be used to generate weapons-grade uranium. But the neutrino may provide a work-around to on-site inspections.
The first neutrino detector specifically intended to demonstrate technology to remotely monitor plutonium production in reactors is the Water Cherenkov Monitor for Antineutrinos (WATCHMAN), the authors note. From 1,000 meters below ground inside northern England’s Boulby salt mine, WATCHMAN will test the idea next year by looking for neutrinos coming from the Hartlepool Nuclear Power Station some 25 kilometers away.
—- Using neutrinos to explore Earth’s deep interior
If neutrinos can be artificially produced at energies of a few trillion electron volts, they can become more interactive with their surroundings. This would thus give geoscientists the means to learn much more about Earth’s deep interior in a manner akin to medical tomography.
But to generate such high-energy neutrinos, the authors note that it would likely require an undersea particle accelerator ring some 24 kilometers in diameter. The idea is to accelerate protons to 20 trillion electron volts (20 TeV) then smash them into a target to produce a beam of particles that would then decay into high energy neutrinos.
—- E.T. might use beams of neutrinos to modify stars for interstellar signaling
Highly advanced extraterrestrial civilizations might modify pulsating Cepheid variable stars using extremely high energy beams of neutrinos in order to transmit information across the galaxy. The authors reference a 2012 article appearing the journal Contemporary Physics.
The idea is that E.T. might use pulsed neutrino beams to modify a Cepheid variable star’s pulsation period. The paper notes that such neutrino beams might generate a binary signature from the star, consisting of a normal pulsation period coupled with a neutrino-triggered artificially, shortened period.
Cepheids would make a natural choice as they can be seen at great distances and as the paper’s authors point out, any developing technological society, such as ours, would likely observe them as distance markers. The paper’s authors thus propose that we search these variable stars for patterns indicative of intelligent signals.
As for the book?
“Ghost Particle” deserves a shelf life for decades to come.
