January 6 2023
By Suzie Sheehy
From the accidental discovery of X-rays in 1895, which revolutionised medicine, through experiments in the 1920s that proved the existence of quantum mechanics and made it possible for contemporary computers, to the indirect effects of massive particle collider experiments, such as the World Wide Web. Of fact, physics discoveries aren't always applicable to everyday life. The 50-year-long search for the neutrino also best represents the principle of curiosity-driven study without any consideration of practical implications.
This tale started with a conundrum regarding beta decay, a form of radioactivity. In the early 1900s, researchers discovered that beta decay appeared to break momentum conservation using crude detectors and potentially harmful radioactive chemicals. This raised serious concerns. One of the most strictly adhered-to physical rules, momentum conservation asserts that the overall quantity of momentum in a system remains constant. There is initially only one item, the atom, in an atom undergoing beta decay. The atom and the "beta particle" are the next two items (i.e., an electron).In a straightforward two-body system like this, the rule of conservation of momentum requires that the kinetic energy dissipated by the projectiles take on a predictable, singular value. Beta radiation's energy appeared random and unpredictable, in contrast to the two other forms of radiation that were known at the time, alpha and gamma. Anyone who conducted such an experiment was powerless to alter the results in any manner.
Every physicist had a unique perspective on what was happening. Some, like as Niels Bohr, considered rejecting the notion of momentum conservation or at the very least getting around it by speculating that on the microscopic sizes inside atoms, energy might only be conserved on average and not in each and every disintegration. Wolfgang Pauli, one thinker in particular, was unable to dismiss the riddle. Pauli was highly recognised for his analytical and critical thinking, earning him the moniker "the scourge of God." At a conference in Brussels, Belgium, scientist Peter Debye advised him to simply stop thinking about beta decay, which didn't sit well with him. Pauli was adamant about preserving momentum conservation, and he succeeded in developing a theoretical fix, but to his horror, it made things worse. He said, "I have done a terrible thing. I've proposed a particle that cannot be found.
The neutrino was that particle, which Pauli introduced to other scientists for the first time in a letter in 1930. He speculated that perhaps a little electrically neutral particle was transferring the energy. He said to his addressees that he "dare not write anything" about it since he thought it was absurd. Pauli's prediction that these particles had no mass and no electric charge presented a dilemma since it made it nearly hard for them to manifest in an experiment.
The neutrino, or "little neutral one," was the name given to the new particle by Enrico Fermi in 1933, and he published a complete theory to the journal Nature at that time. Because it "included thoughts too far from reality to be of interest to the reader," it was rejected. The neutrinos produced by beta decay might traverse the whole world without coming into contact with any matter, according to calculations made by Rudolf Peierls and Hans Bethe in Manchester, UK, a year later. They could really do the same feat through layers of lead that were so thick that they would be measured in light years. The neutrino may have theoretically resolved the beta decay puzzle, but if a particle cannot be seen, how can its existence be confirmed? Experimentalists mostly disregarded it for a long time.
The issue persisted in that state for 20 years. Fred Reines at the Los Alamos Laboratory in New Mexico finally made the decision to pursue the elusive neutrino in the 1950s. Colleague Clyde Cowan, a chemical engineer and former captain in the US Air Force, proved to be a willing partner. Cowan was a talented experimentalist but less extroverted than Reines, who was a dazzling extrovert. A cardboard sign with the words "Project Poltergeist" and a hand-drawn logo of a gazing eye and the core team of five people gathered in a stairway to commence their project in 1951. One of them was oddly waving a big broom in the air behind the sign. They appear to be in high spirits, as they should given that their intended experiment required erecting a sizable tank, filling it with specially prepared and well-filtered liquids, enclosing it in sensitive electronics, and expecting to capture a particle that was virtually undetectable.
They realised they would have to place their experiment underground to escape the effects of cosmic rays, preferably below a nuclear reactor - which would create the neutrinos for the experiment - after early shoestring budget trials produced tantalising but ambiguous findings. At the Savannah River Site in South Carolina, they discovered a basement space, and the owner let the physicists to set up their experiment there 12 metres below ground level. Project Poltergeist was officially named as the Savannah River Neutrino Experiment at the end of 1955. The set-up had developed into a three-layered sandwich of detectors and dazzling liquid, with rectangular tanks that weighed a stunning 10 tonnes each. While electrical wires delivered signals to a trailer outside, the detector, which was encased in many layers of wax and concrete shielding, was located beneath the reactor.
The experiment on the Savannah River lasted for roughly five months. After the chemistry and electronics were all figured out, all that was left to do was carefully gather data, flash by flash. The moment the researchers noticed the distinctive signal of two lights spaced 5 microseconds apart, which whispered neutrino, only once or twice an hour, they were overcome with optimism. Their "aha" moment didn't happen all at once; rather, it was the result of a slow accumulation of information that removed all doubt. When all was said and done, the reactor was on, and there were five times more neutrino signals than when it was off. They had defied the odds by designing a mechanism that could capture a small number of neutrinos each hour and quantify their interactions from the 100 trillion (10^14) neutrinos that the reactor released every second.
Reines and Cowan and their team had accomplished the impossibility 25 years after Pauli prophesied a particle that couldn't be found. They sent Pauli a telegraph saying, "We are glad to inform you that we have certainly identified neutrinos." Pauli read the message aloud and gave an impromptu short talk at the CERN particle physics laboratory in Switzerland. According to lore Later, Pauli and his pals consumed an entire case of champagne, which might be why his return telegram to Reines and Cowan was never delivered. Everything comes to him who can wait, it said.
The chargeless and nearly massless neutrino is like a scarcely detectable puff of a particle that interacts with essentially nothing, in contrast to a zippy electron that interacts with matter via the electromagnetic force or a neutron that interacts with atomic nuclei via the strong nuclear force. Neutrinos are not directly useful to us in our daily lives, in contrast to many other scientific discoveries. However, many physics discoveries were early compared to the available technology at the time. For example, the electron didn't initially appear useful and its discovery wasn't focused on computing and communications. The creation of medicinal isotopes or the treatment of cancer was not the purpose of particle accelerators. Except for the scientists who created them, no one was eagerly anticipating these findings, and even they weren't always deliberate. Neutrinos are unlikely to ever be as directly helpful as electrons, but the information we have learned about them is significant, and amazingly, there are some potential uses in the works.
The first uses for neutrinos were for physics researchers. Later experiments confirmed that there are many sources of neutrinos out there in the universe, including our sun. In 1987, neutrino bursts from a supernova were detected by multiple experiments, giving rise to a new field of neutrino astronomy. Confirming our understanding of how neutrinos form in the sun also helped solidify our knowledge of nuclear physics, required for fusion reactors, which may provide abundant electrical energy on Earth in future.
A UK-US partnership is now constructing a new experiment named WATCHMAN at the Boulby mine in the north of England (Water Cherenkov Monitor for Antineutrinos). A neutrino detector will be used in this research to remotely monitor nuclear fission reactors. By developing a trustworthy method of determining if reactors are in compliance with non-proliferation treaties, the initiative may make a special contribution to international security. There is simply no way to conceal a working nuclear reactor from a detector like this since neutrinos are so difficult to stop.
The understanding we now have of neutrinos may have immediate uses in the future. Neutrinos may one day even develop into a form of cosmic communications because of their capacity to travel across immense cosmic distances at almost the speed of light without interruption.
system. Neutrinos may be the means of communication used by any sophisticated civilizations that may exist on one of the millions of exoplanets that have been found. This was tested in 2012 by the Main Injector Neutrino ExpeRiment to Study v-A Interactions (MINERvA) neutrino experiment at the Fermi National Accelerator Laboratory in Illinois.The scientists successfully deciphered a beam of neutrinos after correctly encoding it, then sending it through half a mile of rock to a detector. Additionally, as radio signals are affected by barriers when travelling through water, this might be helpful for submarines on Earth. They could connect with neutrinos not only via water but also directly through the centre of the earth.
Neutrinos are not nearly ready for usage yet, and maybe never will be, it is fair to assume. Although we are unable to forecast the future, we can state that our efforts to comprehend neutrinos have made substantial yet inadvertent contributions to our way of life. The Sudbury Neutrino Observatory (SNO), one of the most important neutrino experiments, is housed in a subterranean Canadian laboratory that has since been extended and given the new name SNOLAB. The laboratory is located 2100 metres below ground, which is 20 times deeper than the Large Hadron Collider in Switzerland. When they say deep underground, they really mean it. As you fall in the lift for six minutes, the air pressure rises by 20%, giving the sensation of descending in an aeroplane while surrounded by rock.
The facility below ground houses more than simply particle physicists. Its invention paved the way for advancements in several other branches of science. It is a special environment since the laboratory has a very low background radiation from cosmic rays due to its deep location in the earth. A vast study programme looking at the influence of low radiation levels on cells and organisms has been made possible by the availability of a stable, clean, subterranean facility with such low radiation levels. These studies are assisting scientists in understanding what happens when background radiation from cosmic rays is removed since no land-dwelling species has ever survived, or for that matter developed, without exposure to this radiation.
This is significant because it might provide an answer to the question of whether radiation always harms cells and organisms, whether it always does so, or whether there is a threshold radiation level below which radiation is safe or even helpful to life. It could provide further information regarding whether radiation-induced random mutations have an impact on evolution. So far, the findings seem to support the idea that life truly requires only a little amount of radiation. If future research supports this, it will have significant ramifications for understanding the presence of life elsewhere in the universe as well as for ourselves and how we interact with radiation. We just couldn't do this study without deep subterranean labs.
SNOLAB also happens to be one of the top locations on (or in?) Earth for doing quantum computing experimentation. The decoherence period, or the amount of time a quantum bit can keep information before losing it, may be constrained by background radiation from the earth's surface, according to recent research. It may be required to operate quantum computers underground in the future. These laboratories offer a unique setting for this development activity for the time being, at least.
Neutrinos have been referred to as ghosts, messengers, spacecrafts, and wisps of nothing. It began as an attempt to preserve a fundamental physical law, but as time went on, it produced immense benefits for astronomy, cosmology, geology, and our most basic knowledge of matter. In addition, as we have learned more about neutrinos, countless new questions have arisen. For example, we still don't understand why neutrinos have a very small mass rather than none.
Despite its modest size, the neutrino turns out to be a billion times more prevalent in the cosmos than the material that creates stars, galaxies, and our own solar system. It has propelled both theorists and experimenters to ever higher heights, or technically depths, in their quest to discover its mysteries. Ironically, the neutrino is now one of the richest sources of physics knowledge gaps after rescuing one fundamental law of physics. It confirms that there is a lot about the cosmos that we still don't know.
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