As early as March, the Muon g-2 experiment at Fermi National Accelerator Laboratory (Fermilab) will report a new measurement of the magnetism of the muon, a heavier, short-lived cousin of the electron. The effort entails measuring a single frequency with exquisite precision. In tantalizing results dating back to 2001, g-2 found that the muon is slightly more magnetic than theory predicts. If confirmed, the excess would signal, for the first time in decades, the existence of novel massive particles that an atom smasher might be able to produce, says Aida El-Khadra, a theorist at the University of Illinois, Urbana-Champaign. “This would be a very clear sign of new physics, so it would be a huge deal.”
Locked cabinets, a secret frequency, and the curious magnetism of a particle called the muon.
Hydrogen. In theory, it’s the perfect fuel. Run it through a fuel cell and you get electricity, water vapor, and heat. Doesn’t get any more Earth friendly than that, does it? There is theory and then there is reality, starting with where one gets the hydrogen in the first place. It is one of the most abundant elements on Earth — every molecule of water has two hydrogen atoms and there is a lot of water in the world.
Then there is the whole universe of hydrocarbons from gasoline to plastics. By definition, there are hydrogen atoms in all of them and that’s the problem. Hydrogen is so reactive it bonds with everything. Getting pure hydrogen means breaking the chemical bonds that bind to other elements. Keeping it sequestered in its pure state is a whole other conundrum.
Assuming all those challenges are overcome, then comes the question of how to distribute it so it can be used to power the fuel cells in vehicles. A DC fast charging installation might cost $300000 but a hydrogen refueling station can cost $3 million. Compressing it, trucking it, and storing it all present additional hurdles to consider.
Polarons are important nanoscale phenomena: a transient configuration between electrons and atoms (known as quasiparticles) that exist for only trillionths of a second.
Dr. Fatima Ebrahimi designed a fusion rocket that uses magnetic fields to shoot plasma particles from a craft, which could take humans to Mars 10 times faster than current devices.
Researchers at the University of Basel and Ruhr University Bochum have developed a source of single photons that can produce billions of these quantum particles per second. With its record-breaking efficiency, the photon source represents a new and powerful building-block for quantum technologies.
Researchers at the University of Basel and Ruhr University Bochum have developed a source of single photons that can produce billions of these quantum particles per second. With its record-breaking efficiency, the photon source represents a new and powerful building-block for quantum technologies.
A new type of rocket thruster that could take humankind to Mars and beyond has been proposed by a physicist at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL).
The device would apply magnetic fields to cause particles of plasma (link is external), electrically charged gas also known as the fourth state of matter, to shoot out the back of a rocket and, because of the conservation of momentum, propel the craft forward. Current space-proven plasma thrusters use electric fields to propel the particles.
The new concept would accelerate the particles using magnetic reconnection, a process found throughout the universe, including the surface of the sun, in which magnetic field lines converge, suddenly separate, and then join together again, producing lots of energy. Reconnection also occurs inside doughnut-shaped fusion (link is external) devices known as tokamaks (link is external).
BASE opens up new possibilities in the search for cold dark matter.
The Baryon Antibaryon Symmetry Experiment (BASE) at CERN’s Antimatter Factory has set new limits on how easily axion-like particles in a narrow mass range around 2.97 neV can turn into photons, the particles of light. BASE’s new result, published by Physical Review Letters, describes this pioneering method and opens up new experimental possibilities in the search for cold dark matter.
Axions, or axion-like particles, are candidates for cold dark matter. From astrophysical observations, we believe that around 27% of the matter-energy content of the universe is made up of dark matter. These unknown particles feel the force of gravity, but they barely respond to the other fundamental forces, if they experience them at all. The best accepted theory of fundamental forces and particles, called the Standard Model of particle physics, does not contain any particles that have the right properties to be cold dark matter.
Since the Standard Model leaves many questions unanswered, physicists have proposed theories that go beyond it, some of which explain the nature of dark matter. Among such theories are those that suggest the existence of axions or axion-like particles. These theories need to be tested, and many experiments have been set up around the world to look for these particles, including at CERN. For the first time, BASE has turned the tools developed to detect single antiprotons, the antimatter equivalent of a proton, to the search for dark matter. This is especially significant as BASE was not designed for such studies.
“BASE has extremely sensitive detection systems to study the properties of single trapped antiprotons. These detectors can also be used to search for signals of particles other than those produced by antiprotons in traps. In this work, we used one of our detectors as an antenna to search for a new type of axion-like particles,” says Jack Devlin, a CERN research fellow working on the experiment.
Compared to the large detectors installed in the Large Hadron Collider (LHC), BASE is a small experiment. It is connected to CERN’s Antiproton Decelerator, which supplies it with antiprotons. BASE captures and suspends these particles in a Penning trap, a device that combines electric and strong magnetic fields. To avoid collisions with ordinary matter, the trap is operated at 5 kelvins (around-268 degrees Celsius), a temperature at which exceedingly low pressures, similar to those in deep space, are reached. In this extremely well-isolated environment, clouds of trapped antiprotons can exist for years at a time. By carefully adjusting the electric fields, the physicists at BASE can isolate individual antiprotons and move them to a separate part of the experiment. In this region, very sensitive superconducting resonant detectors can pick up the tiny electrical currents generated by single antiprotons as they move around the trap.
Transport processes are ubiquitous in nature, but still raise many questions. The research team around Florian Meinert from the Fifth Institute of Physics at the University of Stuttgart has now developed a new method to observe a single charged particle on its path through a dense cloud of ultracold atoms. The results were published in Physical Review Letters and are further reported in a Viewpoint column in the journal Physics.
Meinert’s team used a Bose-Einstein condensate (BEC) for their experiments. This exotic state of matter consists of a dense cloud of ultracold atoms. By means of sophisticated laser excitation, the researchers created a single Rydberg atom within the gas. In this giant atom, the electron is a thousand times further away from the nucleus than in the ground state and thus only very weakly bound to the core. With a specially designed sequence of electric field pulses, the researchers snatched the electron away from the atom. The formerly neutral atom turned into a positively charged ion that remained nearly at rest despite the process of detaching the electron.
In the next step, the researchers used precise electric fields to pull the ion in a controlled way through the dense cloud of atoms in the BEC. The ion picked up speed in the electric field, collided on its way with other atoms, slowed down and was accelerated again by the electric field. The interplay between acceleration and deceleration by collisions led to a constant motion of the ion through the BEC.
