The attenuation length of the muon content in extensive air showers provides important information regarding the generation and development of air showers. This information can be used not only to improve the description of such showers but also to test fundamental models of hadronic interactions. Using data from the LHAASO-KM2A experiment, the development of the muon content in high-energy air showers was studied. The attenuation length of muon content in the air showers was measured from experimental data in the energy range from 0.3 to 30 PeV using the constant intensity cut method. By comparing the attenuation length of the muon content with predictions from high-energy hadronic interaction models (qgsjet-II-04, sibyll 2.3d, and epos-lhc), it is evident that LHAASO results are significantly shorter than those predicted by the first two models (qgsjet-II-04 and sibyll 2.3d) but relatively close to those predicted by the third model (epos-lhc). Thus, the LHAASO data favor the epos-lhc model over the other two models. The three interaction models confirmed an increasing trend in the attenuation length as the cosmic-ray energy increases.

China

Zhen Cao

Germany

Ireland

F. Aharonian

 Axikegu

Y. X. Bai

Y. W. Bao

D. Bastieri

X. J. Bi

Y. J. Bi

W. Bian

Russia

A. V. Bukevich

Q. Cao

W. Y. Cao

Zhe Cao

J. Chang

J. F. Chang

A. M. Chen

E. S. Chen

H. X. Chen

Liang Chen

Lin Chen

Long Chen

M. J. Chen

M. L. Chen

Q. H. Chen

S. Chen

S. H. Chen

S. Z. Chen

T. L. Chen

Y. Chen

N. Cheng

Y. D. Cheng

Hong Kong

M. C. Chu

M. Y. Cui

S. W. Cui

X. H. Cui

Y. D. Cui

B. Z. Dai

H. L. Dai

Z. G. Dai

 Danzengluobu

X. Q. Dong

K. K. Duan

J. H. Fan

Y. Z. Fan

J. Fang

J. H. Fang

K. Fang

C. F. Feng

H. Feng

L. Feng

S. H. Feng

X. T. Feng

Y. Feng

Y. L. Feng

France

S. Gabici

B. Gao

C. D. Gao

Q. Gao

W. Gao

W. K. Gao

M. M. Ge

T. T. Ge

L. S. Geng

G. Giacinti

G. H. Gong

Q. B. Gou

M. H. Gu

F. L. Guo

J. Guo

X. L. Guo

Y. Q. Guo

Y. Y. Guo

Y. A. Han

O. A. Hannuksela

M. Hasan

H. H. He

H. N. He

J. Y. He

Y. He

Y. K. Hor

B. W. Hou

C. Hou

X. Hou

H. B. Hu

Q. Hu

S. C. Hu

C. Huang

D. H. Huang

T. Q. Huang

W. J. Huang

X. T. Huang

X. Y. Huang

Y. Huang

Y. Y. Huang

X. L. Ji

H. Y. Jia

K. Jia

H. B. Jiang

K. Jiang

X. W. Jiang

Measurement of attenuation length of the muon content in extensive air showers from 0.3 to 30 PeV with LHAASO

In the first part of this Chapter the present state of knowledge from the observations of cosmic rays between 10$^{13}$ and 10$^{20}$ eV is summarized. This is not intended to be a complete review, but rather a broad overview of the relevant processes involving cosmic rays, including the astrophysical environments in which they take place. This overview mainly concerns experimental results and phenomenological aspects of their interpretation, therefore experiments’ description is not given but references to the vast bibliography are provided in the text. Some attempt is made to address the most popular explanations offered by theoretical models. The second part is devoted to the description of the LHAASO performance and of its capability to provide a response to several open questions, still unanswered, concerning cosmic rays above 10$^{13}$ eV, highlighting which major steps forward in this field could be taken from LHAASO observations.

Italy

Benedetto D’Ettorre Piazzoli

Si-Ming Liu

Switzerland

Domenico della Volpe

Andrea Chiavassa

Yi-Qing Guo

Leonid T. Ksenofontov

Olivier Martineau-Huynh

Diane Martraire

Ling-Ling Ma

Xin-Hua Ma

Yuri Stenkin

Qiang Yuan

Hou-Dun Zeng

Shou-Shan Zhang

Yi Zhang

Hui Zhu

Chapter 4 Cosmic-Ray Physics  

Extra-galactic gamma-ray sources, such as gamma-ray bursts, active galactic nuclei, starburst galaxies, are interesting and important targets for LHAASO observations. In this chapter, the prospects of detecting these sources with LHAASO and their physical implications are studied. The upgrade plan for the Water Cherenkov Detector Array (WCDA), which aims to enhance the detectability of relatively lower energy photons, is also presented. In addition, a study on constraining the extragalactic background light with LHAASO observation of blazars is presented.

Xiang-Yu Wang

Xiao-Jun Bi

Piero Vallania

Han-Rong Wu

Da-Hai Yan

Chapter 3 Extra-galactic gamma-ray sources  

The Large High Altitude Air Shower Observatory (LHAASO) (Fig. 1) is located at Mt. Haizi (4410 m a.s.l., 600 g/cm$^{2}$, 29° 21’ 27.56” N, 100° 08’ 19.66” E) in Daocheng, Sichuan province, P.R. China. LHAASO consists of 1.3 km$^{2}$ array (KM2A) of electromagnetic particle detectors (ED) and muon detectors (MD), a water Cherenkov detector array (WCDA) with a total active area of 78,000 m$^{2}$, 18 wide field-of-view air Cherenkov telescopes (WFCTA) and a newly proposed electron-neutron detector array (ENDA) covering 10,000 m$^{2}$. Each detector is synchronized with all the other through a clock synchronization network based on the White Rabbit protocol. The observatory includes an IT center which comprises the data acquisition system and trigger system, the data analysis facility. In this Chapter, all the above-mentioned components of LHAASO as well as infrastructure are described.