Nuclear fission is the most reliable source of antineutrinos, but they are difficult to characterize. A recent study suggests how their emission can be simulated most effectively.

Antineutrinos are mysterious fundamental anti-particles with no charge and an exceptionally small but non-zero mass. The JUNO project (Jiangmen Underground Neutrino Observatory) in China is a large scintillation detector designed to detect them and to characterize their properties, particularly in precise measurements of that tiny mass. Anti-particles are hard to measure and even harder to control, even when they come from a strong and reliable source.

A group of Italian physicists, led by Monica Sisti of the Istituto Nazionale di Fisica Nucleare (INFN) in Milan and Antonio Cammi of the Politecnico di Milano and part of the JUNO collaboration of over 700 scientists from 17 countries, has now modeled parameters that determine the ‘antineutrino spectrum’ emitted by a source.

Advances in inertial confinement fusion and innovative modeling have brought nuclear fusion closer to reality, offering insights into high-energy-density physics and the early universe.

The pursuit of controlled nuclear fusion as a source of clean, abundant energy is moving closer to realization, thanks to advancements in inertial confinement fusion (ICF). This method involves igniting deuterium-tritium (DT) fuel by subjecting it to extreme temperatures and pressures during a precisely engineered implosion process.

In DT fusion, most of the released energy is carried by neutrons, which can be harnessed for electricity generation. Simultaneously, alpha particles remain trapped within the fuel, where they drive further fusion reactions. When the energy deposited by these alpha particles surpasses the energy input from the implosion, the plasma enters a self-sustaining “burning” phase. This significantly boosts energy output and density.

Photons, electrons, and other particles can propagate as wave packets with helical wave fronts that carry an orbital angular momentum. These vortex states can be used to probe the dynamics of atomic, nuclear, and hadronic systems. Recently, researchers demonstrated vortex states of x-ray photons and proposed ways to realize such states for particles at higher energies (MeV to GeV). But verifying high-energy vortex states will be challenging, because characterization techniques used at lower energies would perform poorly. Zhengjiang Li of Sun Yat-sen University in China and his colleagues at Shanghai Institute of Optics and Fine Mechanics propose a new diagnostic method for high-energy vortex states. Their approach would reveal such states through an exotic scattering phenomenon called a superkick.

A superkick is a theorized effect occurring when an atom placed near the axis of a vortex light beam absorbs a photon. Under such conditions, the atom may get kicked to the side with a transverse momentum greater than that carried by the photon. Li and his colleagues considered a similar superkick involving electrons. They analyzed the elastic head-on collision of two electron wave packets at 10 MeV, one in a vortex state and the other in a nonvortex one. According to their calculations, two electrons in the beam, upon scattering, would acquire a nonzero total transverse momentum that could be detectable. The researchers predict an unmistakable signature of the vortex state: The momentum imbalance increases as the collision point gets closer to the vortex axis.

The researchers expect the superkick effect—which has never been observed—to be detectable with realistic experimental settings. They say the idea could be extended to high-energy vortices of photons, ions, and even hadrons.