Neutrinos, the nature’s ghost particles, the mystery particles or whatever you call them, are everywhere but you would never see one! Trillions of them fly right through you in a second but you cannot feel them. And if we can catch them, they can tell us about the farthest reaches and most extreme environments of the universe .Neutrinos are the elementary particles (leptons) i.e. they cannot be sub divided into smaller particles. A million times less massive than an electron, neutrinos fly easily through matter unaffected by magnetic field .In fact they hardly interact with anything. One heck of introverts ..! Right?
But this has an added advantage that they can travel through the universe for millions of years, safely carrying information about where they came from giving us a picture of widest regions of space thereby introducing the new version of gazing instruments “the neutrino telescopes”.
So where do they come from?
They come from the Big Bang that began the universe , from exploding stars and most of all from the sun, they come straight through the earth at nearly the speed of light ,all the time ,in enormous numbers .We can also generate them in nuclear reactors and particle accelerators. The highest energy neutrinos are born far out in space in environments that we know very little about .Something out there, may be super massive black holes or may be some cosmic dynamo, we’ve yet to discover, accelerates cosmic rays to energies over a million times greater than anything human accelerators have achieved .These cosmic rays, most of which are protons interact violently with the matter and radiation around them producing high energy neutrinos.
They then propagate out like cosmic breadcrumbs which can tell us about the locations and interiors of the universe’s most powerful cosmic engines. Their introvert nature may make them great messengers but it also makes them extremely hard to detect.
So how is the world’s largest neutrino telescope detecting it? In the wide lone ranges of Antarctica, a set up is made within a cubic km of ice. Why specifically this location? Well, this ice is one of the clearest solids on Earth, purified by the pressure of thousands of years of accumulated ice and snow. Even though it holds over five thousand blue light sensors, most of the cosmic ray neutrinos pass through without leaving a trace but about ten times a year, a single high energy neutrino collides with a molecule of ice shooting sparks of charged subatomic particles that travel faster through the ice than light does.
In a way similar to a jet that exceeds the speed of sound produces a sonic boom, these super luminal charged particles leave behind a cone of blue light kind of a photonics boom. This light spreads through ice cube hitting some of its detectors located over a mile beneath the surface.
Photomultiplier tubes amplify the signals that contain information about the charged particle’s paths and energies. The data are beamed to astrophysicists around the world who look at the patterns of light for clues about the neutrinos that produce them.
IceCube has already observed the highest energy cosmic neutrino ever seen ,and scientists were able to trace the particle back to where it came from ,which was an entirely another galaxy - a “ distant blazer, a huge elliptical galaxy with a fast spinning super massive black hole at its heart”.
Light from infrared to X-rays to gamma rays has given us increasingly energetic and continuously surprising views of the universe. We are now at the dawn of the age of neutrino astronomy and we’ve no idea what revelations ice cube and other neutrino telescopes bring us about universe’s most violent and most energetic phenomenon. What still makes these particle such a mystery are questions like: What are the masses of the various neutrinos? How do they affect Big Bang cosmology? Do neutrinos oscillate? Are neutrinos different from their antiparticles? Inquisitive enough? Try to dig in.
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