The Second LHAASO Collaboration Conference in 2023

24 Nov 2023, 14:00 → 29 Nov 2023, 20:00 Asia/Shanghai

Tianfu Cosmic Ray Research Center

The second LHAASO Collaboration Meeting in 2023 will be held from November 24th to 29th at the Cosmic Ray Research Center in Tianfu New Area, Chengdu, Sichuan Province, China.

On November 24th, there will be on-site registration, and the conference will take place from November 25th to 29th. 

For foreign colleagues who need to attend the meeting in person and require visa assistance, please contact Shuye Liao at liaosy@ihep.ac.cn.

Only members of the LHAASO Collaboration and their current students are eligible to attend. Please register on the conference website. Resonable registration fee will be required. 

Deadline for the registration and reservation of hotel rooms is Nov 7th, 2023.  It is also the deadline for abstract submission.

This conference will collect invited reports, oral reports and poster reports in English. Oral reports and poster should be submitted their abstracts for reviewing. There will be a specail time for poster reporters to introduce their work at the plenary(5 minutes per postal, no Q&A time).

application_form_for_registration_fee_waiver.doc

poster_v2.pdf

poster_v3.pdf

program202311.pdf

Schedule-v2.pdf

Friday, 24 November

14:00 → 20:00 on-site registration

Saturday, 25 November

09:00 → 09:50 Plenary talks

Convener: Yuhui DONG Yuhui (BSRF, IHEP, CAS)

09:00 Introduction of Participants

09:10 Leaders' Speech

09:20 Unveiling ceremony

09:30 Open address

Speaker: Zhen Cao (高能所)

09:40 Physics Coordinator Commettee work report

Speaker: songzhan（松战） CHEN（陈） (中科院高能物理研究所)

09:50 → 10:10 group photo & coffee break

10:10 → 12:10 Plenary talks: Plenary and SNR

Convener: Yang Chen (Nanjing University)

10:10 Report of the Publication Committee

I will report work of the EB.

Speaker: Siming Liu (Southwest Jiaotong University)

10:20 Speakers Bureau work report

Speaker: 睿智 杨 (University of Science and Technology of China)

10:30 Status of Joint Analysis between LHAASO and the Other Collaborations

Up to now, the LHAASO collaboration have signed ten Memorandum of Understandings (MoUs), including seven international ones and three domestic ones, with the other collaborations on joint analysis. The facilities of The joint collaborations include ground radio, gamma ray, neutrino telescopes and observatories on satelites, so that the joint field covers multi-waveband astronomy and multi-messenger astronomy. Several joint analysis working groups (JAWGs) were orgnized to proceed joint analysis on various gamma ray sources discovered by LHAASO. I will report status of joint analysis and give a discussion and expectation on it.

Speaker: Xinhua MA (Institute of High Energy Physics, CAS)

10:40 SNR summary

Speaker: Siming Liu (Southwest Jiaotong University)

11:04 Update on the analysis of the SNR G150.3+4.5

Based on the results of SNR G150.3+4.5 at the 38th International Cosmic Ray Conference (ICRC2023), we updated several main results: (1) Using the updated data, we obtained two Gaussian distributions, which basically corresponded to the energy segments of WCDA and KM2A by conjoint analyzing WCDA and KM2A data; (2) Using CO data from the Milky Way Imaging Scroll Painting survey (MWISP), it is found that the KM2A region is in good agreement with the molecular cloud, and combined with Gaia data, the distance of the SNR G150.3+4.5 is accurately obtained, about 740pc; (3) Obtain radio flux in 4.8 GHz and 1.4 GHz of the whole of SNR G150.3+4.5; (4) Using the data of FAST observation in the KM2A region for about 0.5 hours, no pulse signal was found. Our results imply that The VHE emission (KM2A) almost comes from the hadronic origin and the HE emission (WCDA) comes from lepton origin of SNRs.

Speaker: Houdun Zeng (PMO)

11:26 LHAASO observation toward the SNR-HII complex G35.6-0.4

It is difficult to identify hadronic PeVatrons (the PeV particle accelerator) from the ultra-high-energy (UHE, E>100TeV) gamma-ray sources, which is however crucial in revealing the origin of cosmic rays. As an endeavor in this regard, we focus in this work on the UHE gamma-ray source 1LHAASO J1857+0203u, which may associate with the supernova remnant (SNR) G35.6−0.4 and H II region G35.6−0.5. We analyze LHAASO KM2A and WCDA data, and report the point-like nature with a significance of 10.1σ above 100 TeV revealed by KM2A. While in 1-30 TeV band, the energy window of the WCDA detector , it shows extension with $r_{39}=0.18$ deg. The spectra measured by WCDA and KM2A can be smoothly connected, with a flux F(>1 TeV)=5.2e-12 erg/cm2/s. Based on the calculation, it is unlikely that the gamma-rays are from clouds illuminated by protons escaped from SNR G35.6-0.4. In the scenario that HII region can accelerate particles to the UHE band, the spectra is well explained by the hadronic process with an index of ~2.0 and a cutoff energy of 260 TeV. However, the putative PWN model can not be ruled out.

Speaker: Xiao Zhang (Nanjing University)

11:48 Probing extreme particle acceleration in the SNR G106.3+2.7 region with LHAASO

Identification of cosmic-ray (CR) accelerators, especially those that can accelerate protons up to PeV regime (namely, PeVatrons), is one of major goals of high-energy astrophysics and plays a crucial role in understanding the origin of Galactic CRs. In this contribution, we report the LHAASO obsesrvation on an intriguing SNR-PWN complex consisting of the famous PeVatron candidate SNR G106.3+2.7 and the Boomerang Nebula powered by a very energetic pulsar with a spindown luminsoity of 2.2e37erg/s. As multiple ultrahigh-energy gamma-ray sources being resolved around the SNR-PWN complex, it is definitely one of the most dynamic regions processing extreme particle acceleration in our Galaxy. The origin of the detected TeV-PeV gamma-ray emission is discussed.

Speaker: Sha WU (IHEP)

12:10 → 13:30 lunch

13:30 → 17:30 LHAASO IB meeing (attendees only LHAASO Institution Board members)

Convener: Zhen Cao (高能所)

Sunday, 26 November

08:30 → 10:10 conference contributions: Cosmic ray

Convener: 会海 He (Institute of High Energy Physics, CAS)

08:30 Cosmic ray summary

Speaker: lingling Malingling_马玲玲_羊八井 (ihep)

08:54 Measurement of the cosmic ray proton spectrum around the knee region with LHAASO

The origin of the knee in the all-particle energy spectrum is still unknown. One of the most important issues in cosmic ray physics is the measurement of the knee in the energy spectrum of individual components. LHAASO is made up of three detector arrays, which are the wide field-of-view Cherenkov telescope array (WFCTA), the kilometer square array (KM2A) and the water Cherenkov detector array (WCDA). The three detector arrays can achieve hybrid observation, so several Extensive Air Shower (EAS) observables sensitive to mass compositions can be measured simultaneously. In this work, the data between November 2020 and March 2021 with the shower core located in KM2A are used to obtain the proton energy spectrum. By using ROOT-TMVA package in combination with various component-sensitive parameters, we selected proton events with purity above 90 percent. The uncertainties from the proton selection, absolute energy determination, and interaction models will be discussed.

Speaker: 智勇 游

09:18 Measurement of the Proton and Helium spectrum with KM2A and WFCTA of the LHAASO experiment

We report on the measurement with high statistics of the energy spectrum of light component (Proton plus Helium nuclei) in cosmic rays by Large High Altitude Air Shower Observatory (LHAASO) around the knee region. LHAASO is a composite cosmic ray observatory, which consists of three detector arrays, including the square meter Kilometer Array (KM2A), the Water Cherenkov Detector Array (WCDA), and the Wide Field of View Cherenkov Telescope Array (WFCTA). The LHAASO experiment with multiple types of detectors can achieve the multi-parameter measurement of the cosmic ray air shower, the parameters including $N_{e}$, $N_{\mu}$, which are sensitive to the component of the cosmic ray were defined and can be used for the mass separation.
The data used in this work were taken from Nov 1, 2020, to Mar 31, 2021. During that period the LHAASO consisted of the first six WFCTA telescopes, the first half KM2A array, and the first water pool of WCDA. The analysis was performed using only information from combined observations of WFCTA and KM2A.

Speaker: 利苹 王 (IHEP)

09:42 A common origin of multi-messenger anomaly of galactic cosmic rays

Speaker: YiQing 郭义庆 (IHEP)

10:10 → 10:30 Coffee break

10:30 → 12:20 conference contributions: others

Convener: 存峰 冯 (山东大学)

10:30 Progress of ENDA

Under Chinese-Russian cooperation, electron-neutron detector array (ENDA) makes progresses during the last half an year: ENDA has been extended from ENDA-16 to ENDA-64, covering area about 1000 m2. ENDA-64 is running smoothingly and sand cubes are being added into one cluster (16 detectors). In 2023, we got supports from both NSFC Major International Joint Research Project and NSFC General Program on ENDA data analysis and detector study. Analysis of data of ENDA-64 and coincident events between ENDA and LHAASO is proceeded. Meanwhile, some results of Monte Carlo simulation on ENDA are obtained which indicate that with 2-3 years data, ENDA-64 can obtain energy spectrum of cosmic ray light component at the knee region.

Speaker: Xinhua MA (Institute of High Energy Physics, CAS)

10:45 Measurement of the muon content in EAS with muon detectors of LHAASO-KM2A

High-energy cosmic rays interact with the atmosphere, generating extensive air showers. Measuring the evolution of muon content in EAS is of profound significance for the research of interaction models. This report is based on the data samples recorded by LHAASO-KM2A of 2022 with zenith angle $\theta \leq 40^{\circ}$, which energy is estimated around $10^{\mathrm{14}} - 10^{\mathrm{16.7}} \, \mathrm{GeV}$. The Monte Carlo samples are produced for five cosmic ray components using CORSIKA for air shower simulation and GEANT4 for KM2A detector response simulation. Both hadronic interaction models EPOS-LHC and QGSJET-II-04 of CORSIKA are utilized. We conducted a comparative analysis of the relationship between the average muon number per energy and energy in both observed data and simulations, revealing a shift towards lighter composition in the data after reaching 1 PeV. In addition, we measured the attenuation length of muon content within air showers using a constant-intensity-cut method. We present the variation of attenuation length with reconstruction energy, demonstrating a increase from 100 TeV to 10 PeV. Remarkably, simulation predictions and experimental measurements are in good agreement within the margin of error. Notably, at 20 PeV, the attenuation length for muon number closely resembles the predictions from KASCADE simulations, as opposed to the experimental results.

Speaker: 晓婷 丰 (山东大学)

11:00 Time structure of the extensive air shower Electron and Muon Components measured by LHAASO-KM2A

The temporal and spatial structure of an EAS front detected at ground level reflects the nature of the primary particle and its interactions with atmosphere nuclei. We give the experiment results of the temporal structure of the shower front of the electronic and muonic EAS components, observed to larger distances from the shower axis up to core distances of R = 500m at the maximum depth of cosmic ray air showers in the knee region. For the description of the shower disc profile and thickness, a new equations are proposed.

Speaker: jia LIU 刘佳 (Key Laboratry of Partical Astrophysics, IHEP)

11:15 Temporal structure of secondary particles during thunderstorms with KM2A

The arrival time distribution of secondary particles from an extensive air shower is one of the important parameters to reconstruct the information of primary particles. Due to the acceleration/deceleration and deflection by the thunderstorm electric field, the number and space-time of the ground-level particles are altered, resulting in a variation of the shower detection and reconstruction. In this work, the temporal structure of secondary particles is studied by analyzing the KM2A data in 2022. The arrival time variation is found to be correlated to the thunderstorm electric fields, and the lightning flashes. During a thunderstorm, the arrival time distribution becomes wider, and the change amplitude is not only dependent on the electric field strength, the core distance, and also strongly dependent on the primary zenith angle. The particle flux variations within different time windows during thunderstorms are also studied. Our results are useful in understanding the change of shower rate detected by KM2A, and will also provide important information for shower reconstruction during thunderstorms.

Speaker: 学健 陈 (西南交通大学)

11:30 Data Production

Speakers: YIN Liqiao 尹丽巧 (IHEP) , Zhiguo Yao (IHEP, Beijing, China)

11:50 Data transfer updates and status

Introduce the data transfer updates and status for KM2A/WCDA/WFCTA/GRB

Speaker: 珊 曾 (高能所)

12:05 The status of LHAASO computing platform

This presentation will talk about the status of lhaaso computing platform in 2023.

Speaker: Haibo LI (高能所)

12:20 → 13:30 lunch

13:30 → 14:38 conference contributions: Young cluster

Convener: Hao Zhou (Shanghai Jiao Tong University)

13:30 Young Cluster summary

Speaker: 睿智 杨 (University of Science and Technology of China)

13:54 Observation of the γ-ray Emission from the W43 Direction with LHAASO

In this presentation we report the very-high-energy (VHE) to ultra-high-energy (UHE) \gray emission detected by the Large High Altitude Air Shower Observation (LHAASO), from the direction toward the young star-forming region W43. The extended \gray source is detected with a significance of ${\sim}23\,\sigma$ with KM2A and a significance of ${\sim}27\,\sigma$ with WCDA. The angular extension of this \gray source is about 0.6 degrees, which corresponds to a physical size of about 50 pc. Together with the multiwavelength data we discuss the origin of the \gray emission and possible CR acceleration in the W43 region. The spatial and spectral features reveal that W43 is likely another young star cluster that can accelerator CRs.

Speaker: 广威 王 (University of Science and Technology of China)

14:16 Observation of LHAASO J1843-0338 : implication for the origin of its UHE gamma-ray emission

We analyze the LHAASO-KM2A data updated to 2023-07-31 and LHAASO-WCDA data updated to 2023-05 to study the morphological and spectral features of this source. Adopting the millimeter data from a multi-CO line survey towards LHAASO J1843-0338, we find a superbubble associated with the gamma-ray emission detected by LHAASO. Our further morphological and model studies on this source, suggest that its very-high-energy gamma-ray emission likely originates from the superbubble. This provides evidence of Superbubbles as potential PeVatron Candidates.

Speaker: Rui Zhang (pmo)

14:40 → 15:30 Poster

Convener: UNKNOWN WU Sha (高能所)

14:40 Study the variance of the mean logarithmic mass of cosmic rays in the knee region using LHAASO-KM2A

Utilizing the unique advantages of the LHAASO experiment, we have achieved a high-precision measurement of the muon content generated by cosmic rays in the knee region of atmospheric showers. The first measurement of $\sigma_{lnA}$ in the knee region using LHAASO-KM2A, combined with $\langle\ln (A)\rangle$, provides experimental evidence for major physical issues such as the origin of the knee region and the origin of cosmic rays.

Speaker: Hengying Zhang (IHEP)

14:45 The precision measurements of all-particle energy spectrum and mean logarithmic mass of cosmic rays using LHAASO-KM2A

Understanding the origin of the knee in terms of the energy spectrum is often considered fundamental for determining the origin of cosmic rays. The kilometer-square array (KM2A) of the Large High Altitude Air Shower Observatory (LHAASO) simultaneously measures air shower sizes of both electromagnetic particles and muons with high precision at 4410 m a.s.l. where cosmic ray air showers with primary energies in the knee region reach approximately maximum resulting in the least fluctuations. This enables the primary energy being measured in a calorimetric way from a new variable $N_{e\mu}$ by combining the number of muons and electromagnetic particles, which shows very weak dependency on primary compositions. We present the measurement of all-particle cosmic ray energy spectrum with unprecedented accuracy in 0.3-30 PeV with KM2A data collected from September 2021 to December 2022, while the mean logarithmic mass in the same energy range is measured.

Speaker: Hengying Zhang (高能所)

14:50 Measurements of the anisotropy of light nuclei using WCDA data

In recent years, the hardening of Cosmic Rays spectra above a few hundred GV and softening around 10TV received much attention. These features of observation may provide insights into the potential origins of nearby sources. Measurements of the anisotropy of light nuclei will provide compelling evidence supporting the existence of nearby sources. In this work, PINCness is used to identify light nuclei and heavy nuclei. We have obtained preliminary results of the anisotropy of light nuclei by using two years data of WCDA from around 1 TeV up to hundreds of TeV.

Speaker: Dan li (IHEP)

14:55 Progress report on nuclei flux measurement

The knee of cosmic ray spectra may reflect the maximum energy accelerated by galactic cosmic ray sources or the limit of the galaxy's ability to bind cosmic rays. Measurements of individual energy spectra are a crucial tool to understand the origin of the knee. One of the main scientific goals of Large High Altitude Air Shower Observatory (LHAASO) is measuring the cosmic ray energy spectra and composition from 10 TeV to $\sim$ EeV. In this study, the density of electromagnetic particles measured by electromagnetic detectors (ED) and the density of muons measured by muon detectors (MD) of LHAASO are used to measure the energy and composition of the primary particle. Individual nuclei flux measured with KM2A data will be presented.

Speaker: Hu Liu (Southwest Jiaotong University)

15:00 Angular power spectrum of the TeV-PeV cosmic ray anisotropy

Propagating individual cosmic rays in synthetic three-dimensional Kolmogorov turbulence, we calculate their anisotropy at the location of an observer. These are the first calculations of the cosmic ray anisotropy down to TeV energies for values of the turbulence coherence length that are realistic for the interstellar medium. We calculate the power spectrum 𝐶𝑙, of the cosmic ray anisotropy for different observer locations, and compare with observations. We also decompose the anisotropy onto spherical harmonics, and show that an important distinction should be made between higher order multipoles that are aligned with the local direction of the magnetic field at the observer’s location, and those that are not.

Speaker: 稳懿 边 (Shanghai Jiao Tong University)

15:30 → 15:40 coffee break

15:40 → 17:10 Poster: reports and show

Monday, 27 November

09:00 → 10:30 conference contributions: Extragalactic sources

10:40 → 12:00 Diffuse gamma-ray & New physics

12:00 → 13:30 lunch

13:30 → 15:00 conference contributions: Young massive star cluster

15:25 → 16:55 Poster: reports and show

Tuesday, 28 November

09:00 → 10:30 conference contributions: Cosmic ray physics

10:40 → 12:00 Anisotropy of cosmic rays

12:00 → 13:30 lunch

13:30 → 15:00 conference contributions: Date analysis & others

15:25 → 16:55 Poster: reports and show

Wednesday, 29 November

09:00 → 11:00 conference contributions: Invited reports of Fermi data, radio, X-ray

11:20 → 12:00 Conference conclusion & Outstanding poster awards

12:00 → 13:30 lunch

13:30 → 17:30 Free arrangement: free discussion