It is one of the most ubiquitous elements in the universe, second only to hydrogen. Balloons filled with it are almost everywhere and can be purchased for only a few dollars. One can easily be forgiven for assuming that helium, which plays a currently irreplaceable role in the superconducting magnets used in MRI and particle accelerators, is not only relatively easily obtained but in inexhausti...

LUPIN-II is an upgraded version of LUPIN, a novel rem counter first developed in 2010 specifically conceived to work in pulsed neutron fields (PNFs). The new version introduces some modifications that improve the performance of the detector, in particular extending its upper detection limit in PNFs. This paper discusses the characteristics and the performance of the instrument. Measurements hav...

Cosmic-rays are ubiquitous, but their origins are surprisingly difficult to understand. A review is presented of some of the basic issues common to cosmic particle accelerators and arguments leading to the likely importance of diffusive shock acceleration as a general explanation. The basic theory of diffusive shock acceleration is outlined, followed by a discussion of some of the key issues th...

It has been suggested that maximally spinning black holes can serve as particle accelerators, reaching arbitrarily high center-of-mass energies. Despite several objections regarding the practical achievability of such high energies, and demonstrations past and present that such large energies could never reach a distant observer, interest in this problem has remained substantial. We show that, ...

We study the naturalness, dark matter, and muon anomalous magnetic moment in the Supersymmetric Standard Models (SSMs) with a pseudo-Dirac gluino (PDGSSMs) from hybrid F− and D−term supersymmetry (SUSY) breakings. To obtain the observed dark matter relic density and explain the muon anomalous magnetic moment, we find that the low energy fine-tuning measures are larger than about 200 due to stro...

Abstract We performed simulations of the EAS particle transport initiated by ultra-high-energy gamma rays entering terrestrial atmosphere. During thunderstorms, electric fields above LHAASO array efficiently modulate particles. Because this modulation, possible bias on energy estimation for primary energies up to 100 TeV can be ten-fold. Moreover, higher (≈1 PeV), field modulation enlarges “gen...