Narrow Results

We examine the large-x QCD evolution of the twist-three gluonic-pole strength defining an effective T-odd Sivers function, where evolution of the T-even transverse-spin DIS structure function g₂ is multiplicative. The result corresponds to a colour-factor modified spin-averaged twist-two evolution.

The high energy pn charge exchange and pp elastic scattering reactions are studied in an effective hadron model for the energy range of s ~ 50 to 400 GeV². The main features of the observed differential cross section of the pn charge exchange reaction, the forward peak and the scaling behavior over the large energy range, are well reproduced by a combination of π-, ρ-exchange and a 4-Nucleon contact term. The latter acts as a background field which turns out to be naturally suppressed in elastic N N scattering but contributes significantly to the charge-exchange reaction.

Correlation among singly charged particles emitted in the forward and backward pseudo-rapidity cones is measured in ${}^{16}$O-Ag/Br and ${}^{32}$S-Ag/Br interactions at an incident energy of $200$ GeV/nucleon. Event-by-event fluctuations in the charged particle multiplicities and their pseudo-rapidity values are also investigated in terms of some known statistical measures. Evidences of short-ranged particle correlation and cluster formation in the pseudo-rapidity space are found from our analysis. A microscopic transport model based on the Ultra-relativistic Quantum Molecular Dynamics could not match the experimental results. The differences between experimental observation and corresponding simulation could neither be accounted for even when a Bose–Einstein type of correlation effect is implemented into the simulated data.

The development of manganese dioxide (MnO${}_2)$ as the cathode for aqueous Zn-MnO₂ batteries is hindered by poor capacity. Herein, we propose a high-capacity MnO₂ cathode constructed by engineering it with N-doping (N-MnO${}_2)$ for a high-performance Zn-MnO₂ battery. Benefiting from N element doping, the conductivity of N-MnO₂ nanorods (NRs) electrode has been improved and the dissolution of the cathode during cycling can be relieved to some extent. The fabricated Zn-N-MnO₂ battery based on the N-MnO₂ cathode and a Zn foil anode presents an a real capacity of 0.31mAhcm${}^{-2}$ at 2mAcm${}^{-2}$, together with a remarkable energy density of 154.3Whkg${}^{-1}$ and a peak power density of 6914.7Wkg${}^{-1}$, substantially higher than most recently reported energy storage devices. The strategy of N doping can also bring intensive interest for other electrode materials for energy storage systems.

The following article has been written primarily by the high school students who make up the team “Cryptic Ontics”, one of the two winning teams in the 2018 edition of CERN’s Beamline for Schools (BL4S) competition, and is based on the set of experiments the students endeavoured to conduct over the course of a two-week period at CERN.

Reconstructing influential physical theories from scratch often helps in uncovering hitherto unknown logical connections and eliciting instructive empirical checkpoints within said theory. With this in mind, in the following article, a top-down reconstruction (beginning with the experimental observations and ending at the theoretical framework) of the Lorentz force equation is performed, and potentially interesting questions which come up are explored. In its most common form, the equation is written out as: $F=qE+q(v\times B)$. Only the term that includes the magnetic field $q(v\times B)$ will be dealt with for this article. The independent parameters we use are (i) the momenta of the particles, (ii) the charge (rather, the types) of particles, either positive or negative, and (iii) the current passing through the dipole generating the electromagnetic field. We then measure the angle by which particles get deflected while varying these three parameters and derive an empirical relationship between them.

The development of manganese dioxide (MnO₂) as the cathode for aqueous Zn-MnO₂ batteries is hindered by poor capacity. Herein, we propose a high-capacity MnO₂ cathode constructed by engineering it with N-doping (N-MnO₂) for a high-performance Zn-MnO₂ battery. Benefiting from N element doping, the conductivity of N-MnO₂ nanorods (NRs) electrode has been improved and the dissolution of the cathode during cycling can be relieved to some extent. The fabricated Zn-N-MnO₂ battery based on the N-MnO₂ cathode and a Zn foil anode presents a real capacity of 0.31 mAh cm^–2 at 2 mA cm^–2, together with a remarkable energy density of 154.3 Wh kg^–1 and a peak power density of 6914.7 W kg^–1, substantially higher than most recently reported energy storage devices. The strategy of N doping can also bring intensive interest for other electrode materials for energy storage systems.

Over a time frame of 13 years, from November 2007 to November 2020, the AGILE MiniCALorimeter (MCAL; 0.4-100 MeV), detected 503 Gamma-Ray Bursts (GRBs). This sample is constituted by 44% short GRBs and 56% long GRBs, as retrieved from the study of the associated T₅₀ and T₉₀ burst duration distribution. For 258 GRBs, it was possible to perform a spectral analysis by adopting a single power law model; for 43 of them, also a spectral fit with a Band model with peak energy E_p above 400 keV was possible. More than 90% of these bursts were also detected by the AGILE Scientific RateMeters (RMs), providing comprehensive simultaneous observations from few tens keV to 100 MeV. The MCAL GRBs mostly consists of short-duration, spectrally hard events, due to the energy range of the detector and the adopted onboard trigger configurations, representing a burst sample which can be used to provide further insights on the high-energy component of hard-spectrum bursts.

The Fermi/LAT gamma-ray telescope has observed 36 GRBs in 4 years of operations. Among them, the bursts with the largest number of LAT-detected photons have spectra which are not well described by the widely used Band model, independently of their energy fluences. High-energy and low-energy excesses have been detected and modeled by an additional power law component and/or by an additional thermal component; high-energy cutoffs have been observed as well. These results point towards a “Band model crisis”: the unprecedented spectral coverage of Fermi (8 keV - 100 GeV) shows the need for an improved modeling of GRB spectra, opening new exciting perspectives and challenges for interpretation and theoretical development. I will review these results, with particular regard to the connected data-analysis challenges.