arXiv subjects

Hengying Zhang

Publications and source records attributed to Hengying Zhang.

4 recordsLinked to original sources

arXiv2024

Unveiling the nature of the knee in the cosmic ray energy spectrum

The knee-like structure around 4 PeV is the most striking feature in the cosmic ray energy spectrum, whose origin remains enigmatic. We propose a novel concept of the total logarithmic mass energy spectrum to characterize the knee, taking into account LHAASO measurements of the all-particle energy spectrum and the mean logarithmic mass. The predominant role of proton in the knee formation is unearthed. The case of a mass-dependent knee is ruled out with a significance of 22.9$σ$ and the rigidity-dependent knee feature is revealed. An ankle-like structure stemming from the excess of iron is discovered at 9.7${\pm}$ 0.2 PeV with a significance of 25.9$σ$. Our findings pierce the mist of the puzzling knee for the first time since its discovery.

astro-ph.HE↗

arXiv2024

Approach for composition measurement of cosmic rays using the muon-to-electron ratio observed by LHAASO-KM2A

Composition measurement of cosmic rays (CRs) around the knee of the CR energy spectrum is crucial for studying the processes of particle acceleration and propagation of Galactic CRs. The Square Kilometer Array (KM2A) of Large High Altitude Air Shower Observatory (LHAASO) can provide precise measurement of the muonic and electromagnetic (em.) components in CR-induced extensive air showers, and hence a good chance to disentangle the CR composition. Here we propose an approach of decomposing CR compositions with the number ratio between muons and em. particles ($N_μ$/$N_{\rm e}$) observed by LHAASO-KM2A: we reconstruct the energy spectra of individual CR compositions by fitting $N_μ$/$N_{\rm e}$ distributions in each reconstructed energy bin using the template shapes of $N_μ$/$N_{\rm e}$ distributions of individual CR compositions based on Monte Carlo (MC) simulation. We evaluate the performance of this approach with MC tests where mock data of LHAASO-KM2A are generated by MC simulation. We show that the input composition model can be well recovered in this approach, independent of the CR composition model adopted in the MC simulation for the template distributions. The uncertainties of the reconstructed spectra at < 20 PeV, mainly limited by simulation statistics, are $\le$ 7% for proton, He, and Fe groups, and $\le$ 8% and $\le$ 16% for CNO and MgAlSi groups, respectively.

astro-ph.HE↗

arXiv2022

Measuring the attenuation length of muon number in the air shower with muon detectors of 3/4 LHAASO array

LHAASO KM2A consists of 5915 scintillation detectors and 1188 muon detectors, and the muon detectors cover 4% area of the whole array with 30 m spacing. The muon number of air shower events, with very high energy, is investigated with the data recorded by muon detector of the 3/4 LHAASO array in 2021. The attenuation length of muon number in the air shower is measured by fitting the muon number with constant flux in various zenith angles, based on the constant intensity cut method. The variation of the attenuation length as shower energy from hundreds TeV to tens PeV is presented. The results of simulation also is presented for comparing.

physics.data-an↗

arXiv2017

Fine structures of azimuthal correlations of two gluons in the glasma

We investigate the azimuthal correlations of the glasma in p-p collisions at $\sqrt{s_{\mathrm{NN}}}=7$ TeV by using the CGC formalism. As expected, the azimuthal correlations show two peaks at $Δϕ=0$ and $π$ which represent collimation production in CGC. Beyond that, azimuthal correlations show fine structures, i.e. bumps or shoulders between the two peaks, when at least one gluon has small $x$. The structures are demonstrated to be associated with saturation momentum, and likely appear at transverse momentum around $2Q_{\mathrm{sp}}=1.8$ GeV$/$c.

hep-ph↗