Black holes born in the early Universe could account for the recently observed ultrahigh-energy astrophysical neutrinos.
Category: particle physics
Primordial black hole’s final burst may solve neutrino mystery
The last gasp of a primordial black hole may be the source of the highest-energy “ghost particle” detected to date, a new MIT study proposes.
In a paper appearing today in Physical Review Letters, MIT physicists put forth a strong theoretical case that a recently observed, highly energetic neutrino may have been the product of a primordial black hole exploding outside our solar system.
Neutrinos are sometimes referred to as ghost particles, for their invisible yet pervasive nature: They are the most abundant particle type in the universe, yet they leave barely a trace. Scientists recently identified signs of a neutrino with the highest energy ever recorded, but the source of such an unusually powerful particle has yet to be confirmed.
Novel catalyst design could make green hydrogen production more efficient and durable
A new type of catalyst—a material that speeds up chemical reactions—that could make the production of clean hydrogen fuel more efficient and long-lasting has been developed by a team led by City University of Hong Kong, including researchers from Hong Kong, mainland China, and Japan.
This breakthrough uses high-density single atoms of iridium (a rare metal) to greatly improve the process of splitting water into hydrogen and oxygen, which is key to renewable energy technologies like hydrogen fuel cells and large-scale energy storage.
The researchers created a highly stable and active catalyst by placing single iridium atoms on ultra-thin sheets made of cobalt and cerium compounds. Called CoCe–O–IrSA, the final product performs exceptionally well in the water-splitting process. It requires very little extra energy (just 187 mV of overpotential at 100 mA cm-2) to drive the oxygen evolution reaction at a high rate, and it stays stable for more than 1,000 hours under demanding conditions.
MicroBooNE detector excludes electron neutrino cause of MiniBooNE anomaly
A recent Physical Review Letters publication presents a thorough analysis of MicroBooNE detector data, investigating the anomalous surplus of neutrino-like events detected by the preceding MiniBooNE experiment.
In 1990, the LSND (Liquid Scintillator Neutrino Detector) experiment observed an anomalous signal indicating the potential existence of sterile neutrinos—a fourth neutrino species beyond the three established flavors (electron, muon, and tau neutrinos).
MiniBooNE was constructed to examine this anomaly utilizing the same neutrino beam methodology. However, instead of resolving the mystery, MiniBooNE discovered an anomaly of its own.
‘Like talking on the telephone’: Quantum computing engineers get atoms chatting long distance
UNSW engineers have made a significant advance in quantum computing: they created ‘quantum entangled states’—where two separate particles become so deeply linked they no longer behave independently—using the spins of two atomic nuclei. Such states of entanglement are the key resource that gives quantum computers their edge over conventional ones.
The research is published in the journal Science, and is an important step toward building large-scale quantum computers—one of the most exciting scientific and technological challenges of the 21st century.
Lead author Dr. Holly Stemp says the achievement unlocks the potential to build the future microchips needed for quantum computing using existing technology and manufacturing processes.
‘Quantum squeezing’ a nanoscale particle for the first time
Researchers Mitsuyoshi Kamba, Naoki Hara, and Kiyotaka Aikawa of the University of Tokyo have successfully demonstrated quantum squeezing of the motion of a nanoscale particle, a motion whose uncertainty is smaller than that of quantum mechanical fluctuations.
As enhancing the measurement precision of sensors is vital in many modern technologies, the achievement paves the way not only for basic research in fundamental physics but also for applications such as accurate autonomous driving and navigation without a GPS signal. The findings are published in the journal Science.
The physical world at the macroscale, from dust particles to planets, is governed by the laws of classical mechanics discovered by Newton in the 17th century. The physical world at the microscale, atoms and below, is governed by the laws of quantum mechanics, which lead to phenomena generally not observed at the macroscale.
Shape-shifting collisions offer new tool for studying early matter produced in Big Bang’s aftermath
This summer, the Large Hadron Collider (LHC) took a breath of fresh air. Normally filled with beams of protons, the 27-km ring was reconfigured to enable its first oxygen–oxygen and neon–neon collisions. First results from the new data, recorded over a period of six days by the ALICE, ATLAS, CMS and LHCb experiments, were presented during the Initial Stages conference held in Taipei, Taiwan, on 7–12 September.
Smashing atomic nuclei into one another allows physicists to study the quark–gluon plasma (QGP), an extreme state of matter that mimics the conditions of the universe during its first microseconds, before atoms formed. Until now, exploration of this hot and dense state of free particles at the LHC relied on collisions between heavy ions (like lead or xenon), which maximize the size of the plasma droplet created.
Collisions between lighter ions, such as oxygen, open a new window on the QGP to better understand its characteristics and evolution. Not only are they smaller than lead or xenon, allowing a better investigation of the minimum size of nuclei needed to create the QGP, but they are less regular in shape. A neon nucleus, for example, is predicted to be elongated like a bowling pin—a picture that has now been brought into sharper focus thanks to the new LHC results.
How you make it matters: Spintronics device performance tied to atomic interface changes
Spintronics devices will be key to realizing faster and more energy-efficient computers. To give us a better understanding of how to make them, a Kobe University team now showed how different manufacturing techniques influence the material properties of a key component.
Electronic devices could be made more efficient and faster if electrons could carry more information at once. This is the basic idea behind spintronics, where researchers try to use the electrons’ spin in addition to charge in data storage, processing and sensor devices to significantly improve our computers.
One component for such devices is the “magnetic tunnel junction,” which may be used, for example, for neuron-like behavior in information processing or in a new type of fast and non-volatile memory. They consist of two ferromagnets, usually a nickel-iron alloy, sandwiching a thin insulating layer such as graphene.
Monitoring sediment buildup in underwater bridge tunnels with the help of high-energy muons
Over 200 underwater bridge tunnels exist for vehicular traffic around the world, providing connectivity between cities. Once constructed, however, these tunnels are difficult to monitor and maintain, often requiring shutdowns or invasive methods that pose structural risks.
Muography—an imaging technique using high-energy particles, called muons, which can traverse hundreds of meters within the Earth—can provide a noninvasive approach to examining subterranean infrastructure.
In the Journal of Applied Physics, a group of researchers from public and private organizations in Shanghai applied this technique to the Shanghai Outer Ring Tunnel, which runs under the Huangpu River as part of the city’s ring expressway.