Archive for the ‘particle physics’ category: Page 4

Mar 14, 2022

Magnetic fields can have a huge impact on reactivity of ultracold molecules

Posted by in categories: chemistry, particle physics, quantum physics

Probability of a reaction occurring increases 100-fold and points to quantum control of chemistry.

A new step towards quantum control of chemistry has been achieved by researchers in the US, who found that tuning the magnetic field applied to colliding ultracold molecules could alter the probability of them reacting or undergoing inelastic scattering a 100-fold.1 The work could potentially prove useful for producing large ensembles of molecules in the same state and investigating their properties.

At room temperature, the random thermal motion of atoms and molecules blurs the quantum nature of chemistry. In an ultracold regime, however, this thermal motion is stilled, revealing chemical interactions as quantum interference processes between matter waves. Remarkable phenomena have been seen in ultracold atomic gases, such as the creation of Bose–Einstein condensates, in which atoms all enter the quantum ground state of a trap, allowing a macroscopic view of their quantum wavefunction. Wolfgang Ketterle at the Massachusetts Institute of Technology (MIT), whose group performed the new research, shared the 2001 physics Nobel prize for the creation of this condensate.

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Mar 14, 2022

Homing in on the Higgs boson interaction with the charm quark

Posted by in category: particle physics

Since the discovery of the Higgs boson a decade ago, the ATLAS and CMS collaborations at the Large Hadron Collider (LHC) have been hard at work trying to unlock the secrets of this special particle. In particular, the collaborations have been investigating in detail how the Higgs boson interacts with fundamental particles such as the particles that make up matter, quarks and leptons. In the Standard Model of particle physics, these matter particles fall into three “generations” of increasing mass, and the Higgs boson interacts with them with a strength that is proportional to their mass. Any deviation from this behavior would provide a clear indication of new phenomena.

ATLAS and CMS have previously observed the interactions of the Higgs boson with the heaviest and leptons, of the third generation, which within the current measurement precision agree with the predictions from the Standard Model. And they have also obtained the first indications that the Higgs boson interacts with a muon, a lepton of the second generation. However, they have yet to observe it interacting with second-generation quarks. In two recent publications, ATLAS and CMS report analyses that place tight limits on the strength of the Higgs boson interaction with a charm quark, a second-generation quark.

ATLAS and CMS studied the Higgs boson interactions by looking at how the boson transforms, or “decays,” into lighter particles or how it is produced together with other particles. In their latest studies, using data from the second run of the LHC, the two teams searched for the decay of the Higgs boson into a charm quark and its antimatter counterpart, the charm antiquark.

Mar 14, 2022

Using pump lasers to create plasma lenses that focus at very high intensity levels

Posted by in categories: nuclear energy, particle physics

A team of researchers from Lawrence Livermore National Laboratory, the University of California at Berkeley and Princeton University has developed plasma-based techniques to build a lens for laser beams with petawatt-scale power. In their paper published in the journal Physical Review Letters, the group describes the two techniques they developed.

Physicists conducting work with and fusion research efforts are hopeful that other researchers will build lasers that are more powerful than those currently available. Such work has been held up by the solid-state optics technology used to create lasers—giving them more power would damage the parts used to generate the laser, making them useless. In this new effort, the researchers noted that other researchers have found that plasma can be used to create optic components such as amplifiers and mirrors. They wondered if the same might be true for the kind of lens needed to produce extremely powerful laser beams. They came up with a concept that involved inducing patterns of high and in a given plasma. Light moving through it, they note, would experience a based on the density of the plasma.

The researchers did not actually build such a laser, but instead, proposed two ways that it might be built. The first method involved firing two pump lasers at a gas sample. The first laser ionized the gas into a plasma, while the second did not. The result was a plasma with a bulls-eye configuration of high and low-density plasma rings, which could be used as a laser lens.

Mar 13, 2022

This Month in Physics History

Posted by in categories: mathematics, particle physics, quantum physics

Many people say that Einstein failed because he was simply ahead of his time. The knowledge and tools needed to complete a unified theory simply hadn’t been developed before Einstein died in 1955.

Today, many physicists are taking up his quest. The most promising approach appears to be string theory, which requires 10 or more dimensions and describes all elementary particles as vibrating strings, with different modes of vibration producing different particles.

String theory has not yet made any testable predictions, and some scientists worry that string theorists have, like Einstein in his later years, strayed too far from physical reality in their obsession with beautiful mathematics. But many others believe string theory does indeed hold the key to completing Einstein’s quest, and researchers are hoping to find ways to test some of the predictions of string theory.

Mar 12, 2022

Study sheds light on axion dark matter

Posted by in categories: cosmology, particle physics

Scientists from Durham University and Kings College London have presented a theoretical review in a new study strongly supporting the search for axion dark matter.

The identity of dark matter, which makes up 85% of the matter in the universe, is one of the big unanswered questions in particle physics.

Scientists know of its existence because of its gravitational pull effects on stars and galaxies but what kind of particle it is, still remains a mystery.

Mar 12, 2022

Shedding light on axion dark matter

Posted by in categories: cosmology, particle physics

Dark matter is one of the biggest mysteries in the universe. Scientists have not yet observed dark matter directly. But, studies have confirmed its existence due to its gravitational pull effects on stars and galaxies. However, what kind of particle it remains elusive.

In a new study, scientists examined how axions can be described mathematically. They then presented how they relate to the fundamental symmetries of the Standard Model of particle physics.

Scientists from Durham University and Kings College London have presented a theoretical review in a new study strongly supporting the search for axion dark matter.

Mar 12, 2022

Smaller than ever—exploring the unusual properties of quantum-sized materials

Posted by in categories: chemistry, nanotechnology, particle physics, quantum physics

The development of functional nanomaterials has been a major landmark in the history of materials science. Nanoparticles with diameters ranging from 5 to 500 nm have unprecedented properties, such as high catalytic activity, compared to their bulk material counterparts. Moreover, as particles become smaller, exotic quantum phenomena become more prominent. This has enabled scientists to produce materials and devices with characteristics that had been only dreamed of, especially in the fields of electronics, catalysis, and optics.

But what if we go smaller? Sub-nanoparticles (SNPs) with particle sizes of around 1 nm are now considered a new class of materials with distinct properties due to the predominance of quantum effects. The untapped potential of SNPs caught the attention of scientists from Tokyo Tech, who are currently undertaking the challenges arising in this mostly unexplored field. In a recent study published in the Journal of the American Chemical Society, a team of scientists from the Laboratory of Chemistry and Life Sciences, led by Dr. Takamasa Tsukamoto, demonstrated a novel molecular screening approach to find promising SNPs.

As one would expect, the synthesis of SNPs is plagued by technical difficulties, even more so for those containing multiple elements. Dr. Tsukamoto explains: “Even SNPs containing just two different elements have barely been investigated because producing a system of subnanometer scale requires fine control of the composition ratio and particle size with atomic precision.” However, this team of scientists had already developed a novel method by which SNPs could be made from different metal salts with extreme control over the total number of atoms and the proportion of each element.

Mar 11, 2022

These Transistor Gates Are Just One Carbon Atom Thick

Posted by in categories: computing, particle physics

Scientists in China have created a transistor using graphene and molybdenum disulfide with a gate length of just 0.34 nanometers. “We have realized the world’s smallest gate-length transistor,” says one of the paper’s authors, an electrical engineer at Tsinghua University in Beijing.

Mar 11, 2022

Stronger and Faster Than Lightning: Scientists Achieve Rare Quantum State in Polycrystals

Posted by in categories: chemistry, climatology, particle physics, quantum physics

Scientists from the Max Planck Institute for Polymer Research, Paderborn University, and the University of Konstanz have succeeded in achieving a rare quantum state. They are the first to have demonstrated Wannier-Stark localization in a polycrystalline substance. Predicted around 80 years ago, the effect has only recently been proven — in a monocrystal. Until now, researchers assumed this localization to be possible only in such monocrystalline substances which are very complicated to produce. The new findings represent a breakthrough in the field of physics and could in future give rise to new optical modulators, for example, that can be used in information technologies based on light, among other things. The physicists have published their findings in the well-respected technical journal, Nature Communications.

Stronger and faster than lightning

The atoms of a crystal are arranged in a three-dimensional grid, held together by chemical bonds. These bonds can, however, be dissolved by very strong electric fields which displace atoms, even going so far as to introduce so much energy into the crystal that it is destroyed. This is what happens when lightning strikes and materials liquefy, vaporize or combust, for example. To demonstrate Wannier-Stark localization, the scientists’ experiments involved setting up electric fields of several million volts per centimeter, much stronger than the fields involved in lightning strikes. During this process, the electronic system of a solid — in this case, a polycrystal — is forced far from a state of equilibrium for a very short time. Wannier-Stark localization involves virtually shutting down some of the chemical bonds temporarily. This state can only be maintained for less than a picosecond — one millionth of one millionth of a second — without destroying the substance.

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Mar 7, 2022

Astronomers See an Enormous Shockwave — 60x Bigger Than the Entire Milky Way Galaxy

Posted by in categories: cosmology, particle physics

Astronomers have a thing for big explosions and collisions, and it always seems like they are trying to one-up themselves in finding a bigger, brighter one. There’s a new entrant to that category – an event so big it created a burst of particles over 1 billion years ago that is still visible today and is 60 times bigger than the entire Milky Way.

That shockwave was created by the merger of two galaxy clusters to create a supercluster known as Abell 3667. This was one of the most energetic events in the universe since the Big Bang 0, according to calculations by Professor Francesco de Gasperin and his time from the University of Hamburg and INAF. When it happened over 1 billion years ago, it shot out a wave of electrons, similar to how a particle accelerator would. All these years later, those particles are still traveling at Mach 2.5 (1500 km/s), and when they pass through magnetic fields, they emit radio waves.

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