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Category: particle physics – Page 108

Why are neutrinos so light?

Did you know that every second more than 100 trillion tiny particles called neutrinos pass through your body without causing any harm? These mysterious particles are produced abundantly throughout the universe in events like nuclear reactions in the sun, radioactive decays in the Earth’s crust, and in high-energy collisions in space. In particular, these subatomic particles play a crucial role in the explosive deaths of stars known as supernovae, where they act as the driving force behind the explosion. Despite their abundance in the universe, they are incredibly difficult to detect directly in experiments since they pass right through any matter and only interact extremely rarely. At the LHC, their existence can only be inferred indirectly by summing up the energy of all other particles produced from the proton collisions and looking for missing energy that has been carried away by the neutrino, which escaped the experiment undetected.

Neutrinos are a type of fundamental particle known as a lepton and they are electrically neutral. They stand out among fundamental particles because of their peculiar characteristics. Not only do they interact exceptionally rarely, but they also possess a minuscule mass, approximately 500,000 times lighter than that of an electron. One possible explanation for the smallness of their mass is given by the “seesaw” mechanism. According to this theory, there exist additional new fundamental particles that are electrically neutral. The mechanism postulates that the masses of these new particles, known as “heavy neutral leptons” (HNLs), are mathematically linked to those of the normal neutrinos, like two sides of a seesaw. The theory also predicts that the HNLs will “mix” with their known cousins, neutrinos. This means that a neutrino, produced in an LHC collision, can change into an HNL, and the HNL can then decay back into known particles that the LHC experiments can detect!

The seesaw explanation for the neutrino mass is particularly attractive and various searches for HNLs have been performed at the LHC and by other experiments in the past (see an example where CMS muon detectors are exploited in such a search). The CMS Collaboration has recently published a new search that makes the assumption that the mixing between the HNLs and neutrinos is very small. In this special case, the HNL can be “long lived” and travel macroscopic distances away from the collision point before decaying. Experiments can then take advantage of the unusual signatures from these “displaced” particle decays when trying to find evidence for the existence of HNLs.

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Big atoms demand big energy to construct. A new model of quantum interactions now suggests some of the lightest particles in the Universe might play a critical role in how at least some heavy elements form.

Physicists in the US have shown how subatomic ‘ghost’ particles known as neutrinos could force atomic nuclei into becoming new elements.

Not only would this be an entirely different method for building elements heavier than iron, it could also describe a long-hypothesized ‘in-between’ path that sits on the border between two known processes, nuclear fusion and nucleosynthesis.

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Philip Goff believes that everything, even tiny particles like electrons, has a little bit of consciousness. This idea is called panpsychism. He explains that this might help us understand why we have feelings and thoughts.

Philip discuss another idea called cosmopsychism, which is a theory that suggests the entire universe is a single conscious entity. Instead of individual minds (like human minds) being separate and independent, they are seen as parts of the universe’s larger, unified consciousness. In simpler terms, it means that the universe itself has a mind, and our individual consciousnesses are just small parts of this greater, universal mind.

Philip thinks science can’t fully explain what it’s like to feel things, like the color red or the taste of chocolate. He says we need to include consciousness in our science to understand everything better.

https://x.com/Philip_Goff.

Why? The Purpose of the Universe (Prof Philip Goff)
https://amzn.to/4cbYHqL

Galileo’s Error: Foundations for a New Science of Consciousness.

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Spintronics relies on the transport of spin currents for computing and communication applications. New device designs would be possible if this spin transport could be carried out by both electrons and magnetic waves called magnons. But spin transport via magnons typically requires electrically insulating magnets—materials that cannot be easily integrated with silicon electronics. A way to bypass that requirement has now been found by Matthias Althammer at the Bavarian Academy of Sciences and Humanities in Germany and his colleagues [1]. The researchers say that this finding could have important implications for both spintronic applications and fundamental research on spin transport.

To demonstrate their concept, Althammer and his colleagues placed two magnetic, metallic strips—each hosting coupled electrons and magnons—on a nonmagnetic, insulating substrate. In the first strip, the researchers converted electron charge currents to electron spin currents. These spin currents were transferred first to the magnons in the same strip, then across the substrate to the magnons in the second strip, and finally to the electrons in the second strip. The researchers detected this spin transport by converting the electron spin currents in the second strip to charge currents.

Althammer and his colleagues studied how the spin transport between the two strips depended on temperature and strip separation. These measurements suggested that the transport was achieved via a magnetic dipole–dipole interaction between the strips. But the researchers could not rule out the possibility that it partly or mainly occurred via crystal vibrations in the substrate. Solving this open problem, which the researchers plan to do in upcoming work, will help in optimizing devices based on this principle.

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Spin-orbit torque effects involve the transfer of angular momentum between a spin current and a magnetic layer mediated by the exchange interaction between conduction and localized electron.

Measuring these effects in magnetic materials continues to be a very active area of interest in spintronics…

Electrons have an , the so-called spin, which means that they can align themselves along a , much like a compass needle. In addition to the electric charge of electrons, which determines their behavior in electronic circuits, their spin is increasingly used for storing and processing data.

Already, one can buy MRAM memory elements (magnetic random access memories), in which information is stored in very small but still classical magnets—that is, containing very many . The MRAMs are based on currents of electrons with spins aligned in parallel that can change the magnetization at a particular point in a material.

Pietro Gambardella and his collaborators at ETH Zurich now show that such spin-polarized currents can also be used to control the quantum states of single electron spins. Their results, which have just been published in the journal Science, could be used in different technologies in the future, for instance in the control of quantum states of quantum bits (qubits).

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A research team led by Prof. Wang Zhandong from the University of Science and Technology of China (USTC), observed a series of covalent cluster intermediates in resonantly stabilized free radical gas-phase reactions with a synchrotron radiation vacuum ultraviolet photoionization mass spectrometry experimental platform, revealing the role of resonantly stabilized free radicals in the growth of particulate matter mass.

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While investigating how string theory can be used to explain certain physical phenomena, scientists at the Indian Institute of Science (IISc) have stumbled upon on a new series representation for the irrational number π. It provides an easier way to extract π from calculations involved in deciphering processes like the quantum scattering of high-energy particles.

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A new study reveals that magnesium oxide, a key mineral in planet formation, might be the first to solidify in developing “super-Earth” exoplanets, with its behavior under extreme conditions significantly influencing planetary development.

Scientists have for the first time observed how atoms in magnesium oxide morph and melt under ultra-harsh conditions, providing new insights into this key mineral within Earth’s mantle that is known to influence planet formation.

High-energy laser experiments—which subjected tiny crystals of the mineral to the type of heat and pressure found deep inside a rocky planet’s mantle—suggest the compound could be the earliest mineral to solidify out of magma oceans in forming “super-Earth” exoplanets.

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Researchers at Oak Ridge National Laboratory used additive manufacturing to produce the first defect-free complex tungsten parts for use in extreme environments. The accomplishment could have positive implications for clean-energy technologies such as fusion energy.

Tungsten has the highest melting point of any metal, making it ideal for fusion reactors where plasma temperatures exceed 180 million degrees Fahrenheit. In comparison, the sun’s center is about 27 million degrees Fahrenheit.

In its pure form, tungsten is brittle at room temperature and easily shatters. To counter this, ORNL researchers developed an electron-beam 3D-printer to deposit tungsten, layer by layer, into precise three-dimensional shapes. This technology uses a magnetically directed stream of particles in a high-vacuum enclosure to melt and bind metal powder into a solid-metal object. The vacuum environment reduces foreign material contamination and residual stress formation.

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