Search

Your search keyword '"Y D, Cheng"' showing total 19 results
Start Over Author "Y D, Cheng" Search Limiters Peer Reviewed
19 results on '"Y D, Cheng"'

1. An Enigmatic PeVatron in an Area around H ii Region G35.6−0.5

Author

Zhen Cao, F. Aharonian, Axikegu, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, W. Bian, A. V. Bukevich, Q. Cao, W. Y. Cao, Zhe Cao, J. Chang, J. F. Chang, A. M. Chen, B. Q. 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, 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, 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, Z. J. Jiang, M. Jin, M. M. Kang, I. Karpikov, D. Khangulyan, D. Kuleshov, K. Kurinov, B. B. Li, C. M. Li, Cheng Li, Cong Li, D. Li, F. Li, H. B. Li, H. C. Li, Jian Li, Jie Li, K. Li, S. D. Li, W. L. Li, X. R. Li, Xin Li, Y. Z. Li, Zhe Li, Zhuo Li, E. W. Liang, Y. F. Liang, S. J. Lin, B. Liu, C. Liu, D. Liu, D. B. Liu, H. Liu, H. D. Liu, J. Liu, J. L. Liu, M. Y. Liu, R. Y. Liu, S.M. Liu, W. Liu, Y. Liu, Y. N. Liu, Q. Luo, Y. Luo, H. K. Lv, B. Q. Ma, L. L. Ma, X. H. Ma, J. R. Mao, Z. Min, W. Mitthumsiri, H. J. Mu, Y. C. Nan, A. Neronov, K. C. Y. Ng, L. J. Ou, P. Pattarakijwanich, Z. Y. Pei, J. C. Qi, M. Y. Qi, B. Q. Qiao, J. J. Qin, A. Raza, D. Ruffolo, A. Sáiz, M. Saeed, D. Semikoz, L. Shao, O. Shchegolev, X. D. Sheng, F. W. Shu, H. C. Song, Yu. V. Stenkin, V. Stepanov, Y. Su, D. X. Sun, Q. N. Sun, X. N. Sun, Z. B. Sun, J. Takata, P. H. T. Tam, Q. W. Tang, R. Tang, Z. B. Tang, W. W. Tian, L. H. Wan, C. Wang, C. B. Wang, G. W. Wang, H. G. Wang, H. H. Wang, J. C. Wang, Kai Wang, L. P. Wang, L. Y. Wang, P. H. Wang, R. Wang, W. Wang, X. G. Wang, X. Y. Wang, Y. Wang, Y. D. Wang, Y. J. Wang, Z. H. Wang, Z. X. Wang, Zhen Wang, Zheng Wang, D. M. Wei, J. J. Wei, Y. J. Wei, T. Wen, C. Y. Wu, H. R. Wu, Q. W. Wu, S. Wu, X. F. Wu, Y. S. Wu, S. Q. Xi, J. Xia, G. M. Xiang, D. X. Xiao, G. Xiao, Y. L. Xin, Y. Xing, D. R. Xiong, Z. Xiong, D. L. Xu, R. F. Xu, R. X. Xu, W. L. Xu, L. Xue, D. H. Yan, J. Z. Yan, T. Yan, C. W. Yang, C. Y. Yang, F. Yang, F. F. Yang, L. L. Yang, M. J. Yang, R. Z. Yang, W. X. Yang, Y. H. Yao, Z. G. Yao, L. Q. Yin, N. Yin, X. H. You, Z. Y. You, Y. H. Yu, Q. Yuan, H. Yue, H. D. Zeng, T. X. Zeng, W. Zeng, M. Zha, B. B. Zhang, F. Zhang, H. Zhang, H. M. Zhang, H. Y. Zhang, J. L. Zhang, Li Zhang, P. F. Zhang, P. P. Zhang, R. Zhang, S. B. Zhang, S. R. Zhang, S. S. Zhang, X. Zhang, X. P. Zhang, Y. F. Zhang, Yi Zhang, Yong Zhang, B. Zhao, J. Zhao, L. Zhao, L. Z. Zhao, S. P. Zhao, X. H. Zhao, F. Zheng, W. J. Zhong, B. Zhou, H. Zhou, J. N. Zhou, M. Zhou, P. Zhou, R. Zhou, X. X. Zhou, B. Y. Zhu, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, Y. C. Zou, X. Zuo, and (The LHAASO Collaboration)

Subjects
Gamma-rays, Gamma-ray sources, H II regions, Supernova remnants, Astrophysics, QB460-466
Abstract

Identifying Galactic PeVatrons (PeV particle accelerators) from ultrahigh-energy (UHE, >100 TeV) γ -ray sources plays a crucial role in revealing the origin of Galactic cosmic rays. The UHE source 1LHAASO J1857+0203u is suggested to be associated with HESS J1858+020, which may be attributed to the possible PeVatron candidate supernova remnant (SNR) G35.6−0.4 or H ii region G35.6−0.5. We perform detailed analysis on the very-high-energy and UHE γ -ray emissions toward this region with data from the Large High Altitude Air Shower Observatory (LHAASO). 1LHAASO J1857+0203u is detected with a significance of 11.6 σ above 100 TeV, indicating the presence of a PeVatron. It has an extent of ∼0 $\mathop{.}\limits^{\unicode{x000B0}}$ 18 with a power-law (PL) spectral index of ∼2.5 at 1–25 TeV and pointlike emission with a PL spectral index of ∼3.2 above 25 TeV. Using archival CO and H i data, we identify some molecular and atomic clouds that may be associated with the TeV γ -ray emissions. Our modeling indicates that the TeV γ -ray emissions are unlikely to arise from clouds illuminated by the protons that escaped from SNR G35.6−0.4. In the scenario in which H ii region G35.6−0.5 could accelerate particles to the UHE band, the observed GeV–TeV γ -ray emission could be well explained by a hadronic model with a PL spectral index of ∼2.0 and cutoff energy of ∼450 TeV. However, an origin in an evolved pulsar wind nebula cannot be ruled out.

Published
2025
Full Text
View/download PDF

2. Discovery of Very High Energy Gamma-Ray Emissions from the Low-luminosity AGN NGC 4278 by LHAASO

Author

Zhen Cao, F. Aharonian, Axikegu, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, W. Bian, 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, 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, S. Gabici, B. Gao, C. D. Gao, Q. Gao, W. Gao, W. K. Gao, M. M. Ge, L. S. Geng, G. Giacinti, G. H. Gong, Q. B. Gou, M. H. Gu, F. L. Guo, X. L. Guo, Y. Q. Guo, Y. Y. Guo, Y. A. Han, 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, D. H. Huang, T. Q. Huang, W. J. Huang, X. T. Huang, X. Y. Huang, Y. Huang, X. L. Ji, H. Y. Jia, K. Jia, K. Jiang, X. W. Jiang, Z. J. Jiang, M. Jin, M. M. Kang, I. Karpikov, D. Kuleshov, K. Kurinov, B. B. Li, C. M. Li, Cheng Li, Cong Li, D. Li, F. Li, H. B. Li, H. C. Li, Jian Li, Jie Li, K. Li, S. D. Li, W. L. Li, X. R. Li, Xin Li, Y. Z. Li, Zhe Li, Zhuo Li, E. W. Liang, Y. F. Liang, S. J. Lin, B. Liu, C. Liu, D. Liu, D. B. Liu, H. Liu, H. D. Liu, J. Liu, J. L. Liu, M. Y. Liu, R. Y. Liu, S. M. Liu, W. Liu, Y. Liu, Y. N. Liu, Q. Luo, Y. Luo, H. K. Lv, B. Q. Ma, L. L. Ma, X. H. Ma, J. R. Mao, Z. Min, W. Mitthumsiri, H. J. Mu, Y. C. Nan, A. Neronov, L. J. Ou, P. Pattarakijwanich, Z. Y. Pei, J. C. Qi, M. Y. Qi, B. Q. Qiao, J. J. Qin, A. Raza, D. Ruffolo, A. Sáiz, M. Saeed, D. Semikoz, L. Shao, O. Shchegolev, X. D. Sheng, F. W. Shu, H. C. Song, Yu. V. Stenkin, V. Stepanov, Y. Su, D. X. Sun, Q. N. Sun, X. N. Sun, Z. B. Sun, J. Takata, P. H. T. Tam, Q. W. Tang, R. Tang, Z. B. Tang, W. W. Tian, C. Wang, C. B. Wang, G. W. Wang, H. G. Wang, H. H. Wang, J. C. Wang, Kai Wang, L. P. Wang, L. Y. Wang, P. H. Wang, R. Wang, W. Wang, X. G. Wang, X. Y. Wang, Y. Wang, Y. D. Wang, Y. J. Wang, Z. H. Wang, Z. X. Wang, Zhen Wang, Zheng Wang, D. M. Wei, J. J. Wei, Y. J. Wei, T. Wen, C. Y. Wu, H. R. Wu, Q. W. Wu, S. Wu, X. F. Wu, Y. S. Wu, S. Q. Xi, J. Xia, G. M. Xiang, D. X. Xiao, G. Xiao, Y. L. Xin, Y. Xing, D. R. Xiong, Z. Xiong, D. L. Xu, R. F. Xu, R. X. Xu, W. L. Xu, L. Xue, D. H. Yan, J. Z. Yan, T. Yan, C. W. Yang, C. Y. Yang, F. Yang, F. F. Yang, L. L. Yang, M. J. Yang, R. Z. Yang, W. X. Yang, Y. H. Yao, Z. G. Yao, L. Q. Yin, N. Yin, X. H. You, Z. Y. You, Y. H. Yu, Q. Yuan, H. Yue, H. D. Zeng, T. X. Zeng, W. Zeng, M. Zha, B. B. Zhang, F. Zhang, H. Zhang, H. M. Zhang, H. Y. Zhang, J. L. Zhang, Li Zhang, P. F. Zhang, P. P. Zhang, R. Zhang, S. B. Zhang, S. R. Zhang, S. S. Zhang, X. Zhang, X. P. Zhang, Y. F. Zhang, Yi Zhang, Yong Zhang, B. Zhao, J. Zhao, L. Zhao, L. Z. Zhao, S. P. Zhao, X. H. Zhao, F. Zheng, W. J. Zhong, B. Zhou, H. Zhou, J. N. Zhou, M. Zhou, P. Zhou, R. Zhou, X. X. Zhou, B. Y. Zhu, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, Y. C. Zou, X. Zuo, and The LHAASO Collaboration

Subjects
High energy astrophysics, Gamma-ray astronomy, Low-luminosity active galactic nuclei, LINER galaxies, Blazars, Fanaroff-Riley radio galaxies, Astrophysics, QB460-466
Abstract

The first source catalog of the Large High Altitude Air Shower Observatory (LHAASO) reported the detection of a very high energy gamma-ray source, 1LHAASO J1219+2915. This Letter presents a further detailed study of the spectral and temporal behavior of this pointlike source. The best-fit position of the TeV source (R.A. = 185.°05 ± 0.°04, decl. = 29.°25 ± 0.°03) is compatible with NGC 4278 within ∼0.°03. Variation analysis shows an indication of variability on a timescale of a few months in the TeV band, which is consistent with low-frequency observations. Based on these observations, we report the detection of TeV γ -ray emissions from this low-luminosity active galactic nucleus. The observation by LHAASO's Water Cherenkov Detector Array during the active period has a significance level of 8.8 σ with a best-fit photon spectral index Γ = 2.56 ± 0.14 and a flux f _1–10 TeV = (7.0 ± 1.1 _sta ± 0.35 _syst ) × 10 ^−13 photons cm ^−2 s ^−1 , or approximately 5% of the Crab Nebula. The discovery of VHE gamma-ray emission from NGC 4278 indicates that compact, weak radio jets can efficiently accelerate particles and emit TeV photons.

Published
2024
Full Text
View/download PDF

3. Detection of Very High-energy Gamma-Ray Emission from the Radio Galaxy M87 with LHAASO

Author

Zhen Cao, F. Aharonian, Axikegu, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, W. Bian, 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, 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, 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, Z. J. Jiang, M. Jin, M. M. Kang, I. Karpikov, D. Khangulyan, D. Kuleshov, K. Kurinov, B. B. Li, C. M. Li, Cheng Li, Cong Li, D. Li, F. Li, H. B. Li, H. C. Li, Jian Li, Jie Li, K. Li, S. D. Li, W. L. Li, X. R. Li, Xin Li, Y. Z. Li, Zhe Li, Zhuo Li, E. W. Liang, Y. F. Liang, S. J. Lin, B. Liu, C. Liu, D. Liu, D. B. Liu, H. Liu, H. D. Liu, J. Liu, J. L. Liu, M. Y. Liu, R. Y. Liu, S. M. Liu, W. Liu, Y. Liu, Y. N. Liu, Q. Luo, Y. Luo, H. K. Lv, B. Q. Ma, L. L. Ma, X. H. Ma, J. R. Mao, Z. Min, W. Mitthumsiri, H. J. Mu, Y. C. Nan, A. Neronov, K. C. Y. Ng, L. J. Ou, P. Pattarakijwanich, Z. Y. Pei, J. C. Qi, M. Y. Qi, B. Q. Qiao, J. J. Qin, A. Raza, D. Ruffolo, A. Sáiz, M. Saeed, D. Semikoz, L. Shao, O. Shchegolev, X. D. Sheng, F. W. Shu, H. C. Song, Yu. V. Stenkin, V. Stepanov, Y. Su, D. X. Sun, Q. N. Sun, X. N. Sun, Z. B. Sun, J. Takata, P. H. T. Tam, Q. W. Tang, R. Tang, Z. B. Tang, W. W. Tian, L. H. Wan, C. Wang, C. B. Wang, G. W. Wang, H. G. Wang, H. H. Wang, J. C. Wang, Kai Wang, L. P. Wang, L. Y. Wang, P. H. Wang, R. Wang, W. Wang, X. G. Wang, X. Y. Wang, Y. Wang, Y. D. Wang, Y. J. Wang, Z. H. Wang, Z. X. Wang, Zhen Wang, Zheng Wang, D. M. Wei, J. J. Wei, Y. J. Wei, T. Wen, C. Y. Wu, H. R. Wu, Q. W. Wu, S. Wu, X. F. Wu, Y. S. Wu, S. Q. Xi, J. Xia, G. M. Xiang, D. X. Xiao, G. Xiao, Y. L. Xin, Y. Xing, D. R. Xiong, Z. Xiong, D. L. Xu, R. F. Xu, R. X. Xu, W. L. Xu, L. Xue, D. H. Yan, J. Z. Yan, T. Yan, C. W. Yang, C. Y. Yang, F. Yang, F. F. Yang, L. L. Yang, M. J. Yang, R. Z. Yang, W. X. Yang, Y. H. Yao, Z. G. Yao, L. Q. Yin, N. Yin, X. H. You, Z. Y. You, Y. H. Yu, Q. Yuan, H. Yue, H. D. Zeng, T. X. Zeng, W. Zeng, M. Zha, B. B. Zhang, F. Zhang, H. Zhang, H. M. Zhang, H. Y. Zhang, J. L. Zhang, Li Zhang, P. F. Zhang, P. P. Zhang, R. Zhang, S. B. Zhang, S. R. Zhang, S. S. Zhang, X. Zhang, X. P. Zhang, Y. F. Zhang, Yi Zhang, Yong Zhang, B. Zhao, J. Zhao, L. Zhao, L. Z. Zhao, S. P. Zhao, X. H. Zhao, F. Zheng, W. J. Zhong, B. Zhou, H. Zhou, J. N. Zhou, M. Zhou, P. Zhou, R. Zhou, X. X. Zhou, B. Y. Zhu, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, Y. C. Zou, and X. Zuo

Subjects
Active galactic nuclei, High energy astrophysics, Astrophysics, QB460-466
Abstract

The nearby radio galaxy M87 is a very high-energy (VHE) gamma-ray emitter established by observations with ground-based gamma-ray detectors. Here we report the long-term monitoring of M87 from 2021 to 2024 with the Large High Altitude Air Shower Observatory (LHAASO). M87 has been detected by LHAASO with a statistical significance ∼ 9 σ . The observed energy spectrum extends to 20 TeV, with a possible hardening at ∼20 TeV and then a clear softening at higher energies. Assuming that the intrinsic spectrum is described by a single power law up to 20 TeV, a tight upper bound on the extragalactic background light intensity is obtained. A strong VHE flare lasting 8 days, with a rise time of ${\tau }_{r}^{\mathrm{rise}}=1.05\pm 0.49$ days and decay time of ${\tau }_{d}^{\mathrm{decay}}=2.17\pm 0.58$ days, was found in early 2022. A possible GeV flare is seen also in Fermi Large Area Telescope data during the VHE flare period. The variability time as short as 1 day seen in the LHAASO data suggests a compact emission region with a size of ∼3 × 10 ^15 δ cm ( δ being the Doppler factor of the emitting region), corresponding to a few Schwarzschild radii of the central supermassive black hole in M87. The continuous monitoring of the source reveals a duty cycle of ∼1% for VHE flares with a flux above 10 ^−11 erg cm ^−2 s ^−1 .

Published
2024
Full Text
View/download PDF

4. The First LHAASO Catalog of Gamma-Ray Sources

Author

Zhen Cao, F. Aharonian, Q. An, Axikegu, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, J. T. Cai, Q. Cao, W. Y. Cao, Zhe Cao, J. Chang, J. F. Chang, A. M. Chen, E. S. Chen, Liang Chen, Lin Chen, Long Chen, M. J. Chen, M. L. Chen, Q. H. Chen, S. H. Chen, S. Z. Chen, T. L. Chen, Y. Chen, N. Cheng, Y. D. Cheng, M. Y. Cui, S. W. Cui, X. H. Cui, Y. D. Cui, B. Z. Dai, H. L. Dai, Z. G. Dai, Danzengluobu, D. della Volpe, X. Q. Dong, K. K. Duan, J. H. Fan, Y. Z. Fan, J. Fang, K. Fang, C. F. Feng, L. Feng, S. H. Feng, X. T. Feng, Y. L. Feng, S. Gabici, B. Gao, C. D. Gao, L. Q. Gao, Q. Gao, W. Gao, W. K. Gao, M. M. Ge, L. S. Geng, G. Giacinti, G. H. Gong, Q. B. Gou, M. H. Gu, F. L. Guo, X. L. Guo, Y. Q. Guo, Y. Y. Guo, Y. A. Han, H. H. He, H. N. He, J. Y. He, X. B. He, Y. He, M. Heller, Y. K. Hor, B. W. Hou, C. Hou, X. Hou, H. B. Hu, Q. Hu, S. C. Hu, D. H. Huang, T. Q. Huang, W. J. Huang, X. T. Huang, X. Y. Huang, Y. Huang, Z. C. Huang, X. L. Ji, H. Y. Jia, K. Jia, K. Jiang, X. W. Jiang, Z. J. Jiang, M. Jin, M. M. Kang, T. Ke, D. Kuleshov, K. Kurinov, B. B. Li, Cheng Li, Cong Li, D. Li, F. Li, H. B. Li, H. C. Li, H. Y. Li, J. Li, Jian Li, Jie Li, K. Li, W. L. Li, X. R. Li, Xin Li, Y. Z. Li, Zhe Li, Zhuo Li, E. W. Liang, Y. F. Liang, S. J. Lin, B. Liu, C. Liu, D. Liu, H. Liu, H. D. Liu, J. Liu, J. L. Liu, J. Y. Liu, M. Y. Liu, R. Y. Liu, S. M. Liu, W. Liu, Y. Liu, Y. N. Liu, R. Lu, Q. Luo, H. K. Lv, B. Q. Ma, L. L. Ma, X. H. Ma, J. R. Mao, Z. Min, W. Mitthumsiri, H. J. Mu, Y. C. Nan, A. Neronov, Z. W. Ou, B. Y. Pang, P. Pattarakijwanich, Z. Y. Pei, M. Y. Qi, Y. Q. Qi, B. Q. Qiao, J. J. Qin, D. Ruffolo, A. Sáiz, D. Semikoz, C. Y. Shao, L. Shao, O. Shchegolev, X. D. Sheng, F. W. Shu, H. C. Song, Yu. V. Stenkin, V. Stepanov, Y. Su, Q. N. Sun, X. N. Sun, Z. B. Sun, P. H. T. Tam, Q. W. Tang, Z. B. Tang, W. W. Tian, C. Wang, C. B. Wang, G. W. Wang, H. G. Wang, H. H. Wang, J. C. Wang, K. Wang, L. P. Wang, L. Y. Wang, P. H. Wang, R. Wang, W. Wang, X. G. Wang, X. Y. Wang, Y. Wang, Y. D. Wang, Y. J. Wang, Z. H. Wang, Z. X. Wang, Zhen Wang, Zheng Wang, D. M. Wei, J. J. Wei, Y. J. Wei, T. Wen, C. Y. Wu, H. R. Wu, S. Wu, X. F. Wu, Y. S. Wu, S. Q. Xi, J. Xia, J. J. Xia, G. M. Xiang, D. X. Xiao, G. Xiao, G. G. Xin, Y. L. Xin, Y. Xing, Z. Xiong, D. L. Xu, R. F. Xu, R. X. Xu, W. L. Xu, L. Xue, D. H. Yan, J. Z. Yan, T. Yan, C. W. Yang, F. Yang, F. F. Yang, H. W. Yang, J. Y. Yang, L. L. Yang, M. J. Yang, R. Z. Yang, S. B. Yang, Y. H. Yao, Z. G. Yao, Y. M. Ye, L. Q. Yin, N. Yin, X. H. You, Z. Y. You, Y. H. Yu, Q. Yuan, H. Yue, H. D. Zeng, T. X. Zeng, W. Zeng, M. Zha, B. B. Zhang, F. Zhang, H. M. Zhang, H. Y. Zhang, J. L. Zhang, L. X. Zhang, Li Zhang, P. F. Zhang, P. P. Zhang, R. Zhang, S. B. Zhang, S. R. Zhang, S. S. Zhang, X. Zhang, X. P. Zhang, Y. F. Zhang, Yi Zhang, Yong Zhang, B. Zhao, J. Zhao, L. Zhao, L. Z. Zhao, S. P. Zhao, F. Zheng, B. Zhou, H. Zhou, J. N. Zhou, M. Zhou, P. Zhou, R. Zhou, X. X. Zhou, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, X. Zuo, and (The LHAASO Collaboration)

Subjects
Gamma-ray astronomy, Gamma-ray observatories, Catalogs, Astrophysics, QB460-466
Abstract

We present the first catalog of very-high-energy and ultra-high-energy gamma-ray sources detected by the Large High Altitude Air Shower Observatory. The catalog was compiled using 508 days of data collected by the Water Cherenkov Detector Array from 2021 March to 2022 September and 933 days of data recorded by the Kilometer Squared Array from 2020 January to 2022 September. This catalog represents the main result from the most sensitive large coverage gamma-ray survey of the sky above 1 TeV, covering decl. from −20° to 80°. In total, the catalog contains 90 sources with an extended size smaller than 2° and a significance of detection at >5 σ . Based on our source association criteria, 32 new TeV sources are proposed in this study. Among the 90 sources, 43 sources are detected with ultra-high energy ( E > 100 TeV) emission at >4 σ significance level. We provide the position, extension, and spectral characteristics of all the sources in this catalog.

Published
2024
Full Text
View/download PDF

5. Construction and on-site performance of the LHAASO WFCTA camera

Author

F. Aharonian, Q. An, Axikegu, L. X. Bai, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, H. Cai, J. T. Cai, Z. Cao, J. Chang, J. F. Chang, X. C. Chang, B. M. Chen, J. Chen, L. Chen, M. J. Chen, M. L. Chen, Q. H. Chen, S. H. Chen, S. Z. Chen, T. L. Chen, X. L. Chen, Y. Chen, N. Cheng, Y. D. Cheng, S. W. Cui, X. H. Cui, Y. D. Cui, B. Z. Dai, H. L. Dai, Z. G. Dai, Danzengluobu, D. della Volpe, B. D’Ettorre Piazzoli, X. J. Dong, J. H. Fan, Y. Z. Fan, Z. X. Fan, J. Fang, K. Fang, C. F. Feng, L. Feng, S. H. Feng, Y. L. Feng, B. Gao, C. D. Gao, Q. Gao, W. Gao, M. M. Ge, L. S. Geng, G. H. Gong, Q. B. Gou, M. H. Gu, J. G. Guo, X. L. Guo, Y. Q. Guo, Y. Y. Guo, Y. A. Han, H. H. He, H. N. He, J. C. He, S. L. He, X. B. He, Y. He, M. Heller, Y. K. Hor, C. Hou, X. Hou, H. B. Hu, S. Hu, S. C. Hu, X. J. Hu, D. H. Huang, Q. L. Huang, W. H. Huang, X. T. Huang, Z. C. Huang, F. Ji, X. L. Ji, H. Y. Jia, K. Jiang, Z. J. Jiang, C. Jin, D. Kuleshov, K. Levochkin, B. B. Li, C. Li, F. Li, H. B. Li, H. C. Li, H. Y. Li, J. Li, K. Li, W. L. Li, X. Li, X. R. Li, Y. Li, Y. Z. Li, Z. Li, E. W. Liang, Y. F. Liang, S. J. Lin, B. Liu, C. Liu, D. Liu, H. Liu, H. D. Liu, J. Liu, J. L. Liu, J. S. Liu, J. Y. Liu, M. Y. Liu, R. Y. Liu, S. M. Liu, W. Liu, Y. N. Liu, Z. X. Liu, W. J. Long, R. Lu, H. K. Lv, B. Q. Ma, L. L. Ma, X. H. Ma, J. R. Mao, A. Masood, W. Mitthumsiri, T. Montaruli, Y. C. Nan, B. Y. Pang, P. Pattarakijwanich, Z. Y. Pei, M. Y. Qi, D. Ruffolo, V. Rulev, A. Sáiz, L. Shao, O. Shchegolev, X. D. Sheng, J. R. Shi, H. C. Song, Yu. V. Stenkin, V. Stepanov, Q. N. Sun, X. N. Sun, Z. B. Sun, P. H. T. Tam, Z. B. Tang, W. W. Tian, B. D. Wang, C. Wang, H. Wang, H. G. Wang, J. C. Wang, J. S. Wang, L. P. Wang, L. Y. Wang, R. N. Wang, W. Wang, X. G. Wang, X. J. Wang, X. Y. Wang, Y. D. Wang, Y. J. Wang, Y. P. Wang, Z. Wang, Z. H. Wang, Z. X. Wang, D. M. Wei, J. J. Wei, Y. J. Wei, T. Wen, C. Y. Wu, H. R. Wu, S. Wu, W. X. Wu, X. F. Wu, S. Q. Xi, J. Xia, J. J. Xia, G. M. Xiang, G. Xiao, H. B. Xiao, G. G. Xin, Y. L. Xin, Y. Xing, D. L. Xu, R. X. Xu, L. Xue, D. H. Yan, C. W. Yang, F. F. Yang, J. Y. Yang, L. L. Yang, M. J. Yang, R. Z. Yang, S. B. Yang, Y. H. Yao, Z. G. Yao, Y. M. Ye, L. Q. Yin, N. Yin, X. H. You, Z. Y. You, Y. H. Yu, Q. Yuan, H. D. Zeng, T. X. Zeng, W. Zeng, Z. K. Zeng, M. Zha, X. X. Zhai, B. B. Zhang, H. M. Zhang, H. Y. Zhang, J. L. Zhang, J. W. Zhang, L. Zhang, L. X. Zhang, P. F. Zhang, P. P. Zhang, R. Zhang, S. R. Zhang, S S. Zhang, X. Zhang, X. P. Zhang, Y. Zhang, Y. F. Zhang, Y. L. Zhang, B. Zhao, J. Zhao, L. Zhao, L. Z. Zhao, S. P. Zhao, F. Zheng, Y. Zheng, B. Zhou, H. Zhou, J. N. Zhou, P. Zhou, R. Zhou, X. X. Zhou, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, X. Zuo, and The LHAASO Collaboration

Subjects
Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

Abstract The focal plane camera is the core component of the Wide Field-of-view Cherenkov/fluorescence Telescope Array (WFCTA) of the Large High-Altitude Air Shower Observatory (LHAASO). Because of the capability of working under moonlight without aging, silicon photomultipliers (SiPM) have been proven to be not only an alternative but also an improvement to conventional photomultiplier tubes (PMT) in this application. Eighteen SiPM-based cameras with square light funnels have been built for WFCTA. The telescopes have collected more than 100 million cosmic ray events and preliminary results indicate that these cameras are capable of working under moonlight. The characteristics of the light funnels and SiPMs pose challenges (e.g. dynamic range, dark count rate, assembly techniques). In this paper, we present the design features, manufacturing techniques and performances of these cameras. Finally, the test facilities, the test methods and results of SiPMs in the cameras are reported here.

Published
2021
Full Text
View/download PDF

6. Line-of-shower trigger method to lower energy threshold for GRB detection using LHAASO-WCDA

Author

C. F. Feng, Bin Zhou, X. L. Ji, R. Lu, H. B. Xiao, J. R. Shi, W. Zeng, Z. H. Wang, Shengxue Zhang, Pak-Hin Thomas Tam, H. C. Li, Jun Liu, H. Y. Jia, B. D'Ettorre Piazzoli, W. X. Wu, Junjie Mao, Y. Q. Guo, Dong Liu, F. Ji, H. R. Wu, Y. J. Wei, Alejandro Sáiz, Oleg Shchegolev, L. Feng, V. Rulev, L. Xue, Xuliang Chen, Xing-Yuan Hou, D. M. Wei, S. Hu, M. L. Chen, Jianeng Zhou, J. Y. Liu, Warit Mitthumsiri, Y. Zhang, Q. An, Y. He, Q. Gao, Ruizhi Yang, X. N. Sun, H. B. Hu, H. Liu, L. Chen, X. G. Wang, S. Q. Xi, J. Fang, X. H. You, Ping Zhou, Z. C. Huang, Y. Z. Li, P. F. Zhang, C. Y. Wu, Hong-Guang Wang, G. M. Xiang, W. Liu, Yu-Lei Chen, Zihuang Cao, X. C. Chang, Z. K. Zeng, Y. J. Bi, H. D. Liu, Y. D. Cheng, Bo Zhang, Y. Zheng, L. Q. Yin, Duo Yan, F. Zheng, Hao Zhou, X. X. Zhou, Q. Yuan, Hefan Li, J. F. Chang, Z. X. Liu, Felix Aharonian, H. N. He, C. D. Gao, Lei Zhao, Q. H. Chen, Youping Li, Y. M. Ye, B. B. Li, Yongchun Wang, Y. D. Cui, Bai Yibing, L. P. Wang, J. B. Zhao, Y. J. Wang, J. Y. Yang, S. Z. Chen, Yunchao Liu, B. Z. Dai, Rong Xu, Z. X. Fan, Z. Y. You, Z. G. Dai, X. F. Wu, He Zhang, S. H. Feng, S. B. Yang, J. J. Xia, W. Gao, S. L. He, Y. P. Wang, B. M. Chen, Fan Yang, A. Masood, Kun Fang, S.H. Chen, Yugang Zhang, H. Cai, Lang Shao, H. Wang, J.W. Xia, L. Z. Zhao, G. C. Xiao, X. X. Zhai, Y. C. Nan, Shi-Qi Hu, X. J. Bi, Z. Li, R. Liu, E. W. Liang, X. Zuo, M. J. Yang, Y. H. Yao, W. L. Li, L. X. Zhang, H. K. Lv, Xufang Li, B. Y. Pang, Zebo Tang, M. H. Gu, Z. Y. Pei, Xuejiao Li, F. R. Zhu, T. L. Chen, Qie Sun, K. J. Zhu, Ying Zhang, H. M. Zhang, J. Chen, H. L. Dai, Y. L. Xin, T. Wen, S. W. Cui, M. Zha, J. C. He, W. H. Huang, L. X. Bai, Binyu Zhao, Yun-Feng Liang, Jixia Li, X. H. Cui, Xinbo He, K. Jiang, X. J. Hu, J. W. Zhang, Li-Sheng Geng, Wenwu Tian, Z. X. Wang, Xiaofei Zhang, David Ruffolo, Yu. V. Stenkin, C. Hou, Z. B. Sun, Shuibin Lin, Lu Zhang, K. Levochkin, Cheng Guang Zhu, X. D. Sheng, Minghao Qi, Houdun Zeng, Jun-Jie Wei, Jia Zhang, Y. A. Han, H. B. Li, Danzengluobu, Rui Zhang, H. C. Song, Linbin Yang, Y. Z. Fan, J. T. Cai, H. H. He, Y. M. Xing, F. Y. Li, D. H. Huang, H. Zhu, Xiang Zhang, M. M. Ge, J. G. Guo, S. R. Zhang, N. Cheng, L. L. Ma, G. H. Gong, J. S. Wang, Cunguo Wang, Shujuan Liu, N. Yin, Y. H. Yu, W. J. Long, Axikegu, Xuelong Wang, P. P. Zhang, Chunlong Li, Minghui Liu, D. Bastieri, Jinyao Liu, Z. G. Yao, X. H. Ma, M. Heller, K. Li, Z. J. Jiang, J. Liu, R. N. Wang, V. I. Stepanov, Jian Wang, Chiming Jin, D.A. Kuleshov, G. G. Xin, M. J. Chen, S. P. Zhao, Y. Y. Guo, Donglian Xu, X. L. Guo, X. J. Dong, Y. K. Hor, T. Montaruli, Y. L. Feng, W. Wang, P. Pattarakijwanich, S. Wu, B. D. Wang, C. X. Liu, Y. W. Bao, X. T. Huang, R. Zhou, L. Y. Wang, D. della Volpe, C. W. Yang, Jun-Hui Fan, Zujian Wang, Q. B. Gou, Qizhi Huang, B. Liu, Bingshui Gao, Xiang-Yu Wang, Tao Zeng, and Bin Ma

Subjects
Physics, Nuclear and High Energy Physics, Cherenkov detector, Astrophysics::High Energy Astrophysical Phenomena, Detector, Astrophysics, law.invention, Air shower, Nuclear Energy and Engineering, Duty cycle, law, Observatory, Gamma-ray burst, Energy (signal processing), Line (formation)
Abstract

Observation of high energy and very high emission from Gamma Ray Bursts (GRBs) is crucial to study the gigantic explosion and the underline processes. With a large field-of-view and almost full duty cycle, the Water Cherenkov Detector Array (WCDA), a sub-array of the Large High Altitude Air Shower Observatory (LHAASO), is appropriate to monitor the very high energy emission from unpredictable transients such as GRBs. Nevertheless, the main issue for an extensive air shower array is the high energy threshold which limits the horizon of the detector. To address this issue a new trigger method is developed in this article to lower the energy threshold of WCDA for GRB observation. The proposed method significantly improves the detection efficiency of WCDA for gamma-rays around the GRB direction at 10-300 GeV. The sensitivity of the WCDA for GRB detection with the new trigger method is estimated. The achieved sensitivity of the quarter WCDA array above 10 GeV is comparable with that of Fermi-LAT. The data analysis process and corresponding fluence upper limit for GRB 190719C is presented as an example.

Published
2021
Full Text
View/download PDF

7. A dynamic range extension system for LHAASO WCDA-1

Author

F. Aharonian, Q. An, null Axikegu, L. X. Bai, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, H. Cai, J. T. Cai, Z. Cao, J. Chang, J. F. Chang, X. C. Chang, B. M. Chen, J. Chen, L. Chen, M. J. Chen, M. L. Chen, Q. H. Chen, S. H. Chen, S. Z. Chen, T. L. Chen, X. L. Chen, Y. Chen, N. Cheng, Y. D. Cheng, S. W. Cui, X. H. Cui, Y. D. Cui, B. Z. Dai, H. L. Dai, Z. G. Dai, null Danzengluobu, D. della Volpe, B. D’Ettorre Piazzoli, X. J. Dong, J. H. Fan, Y. Z. Fan, Z. X. Fan, J. Fang, K. Fang, C. F. Feng, L. Feng, S. H. Feng, Y. L. Feng, B. Gao, C. D. Gao, Q. Gao, W. Gao, M. M. Ge, L. S. Geng, G. H. Gong, Q. B. Gou, M. H. Gu, J. G. Guo, X. L. Guo, Y. Q. Guo, Y. Y. Guo, Y. A. Han, H. H. He, H. N. He, J. C. He, S. L. He, X. B. He, Y. He, M. Heller, Y. K. Hor, C. Hou, X. Hou, H. B. Hu, S. Hu, S. C. Hu, X. J. Hu, D. H. Huang, Q. L. Huang, W. H. Huang, X. T. Huang, Y. Huang, Z. C. Huang, F. Ji, X. L. Ji, H. Y. Jia, K. Jiang, Z. J. Jiang, C. Jin, D. Kuleshov, K. Levochkin, B. B. Li, C. Li, F. Li, H. B. Li, H. C. Li, H. Y. Li, J. Li, K. Li, W. L. Li, X. Li, X. R. Li, Y. Li, Y. Z. Li, Z. Li, E. W. Liang, Y. F. Liang, S. J. Lin, B. Liu, C. Liu, D. Liu, H. Liu, H. D. Liu, J. Liu, J. L. Liu, J. S. Liu, J. Y. Liu, M. Y. Liu, R. Y. Liu, S. M. Liu, W. Liu, Y. N. Liu, Z. X. Liu, W. J. Long, R. Lu, H. K. Lv, B. Q. Ma, L. L. Ma, X. H. Ma, J. R. Mao, A. Masood, W. Mitthumsiri, T. Montaruli, Y. C. Nan, B. Y. Pang, P. Pattarakijwanich, Z. Y. Pei, M. Y. Qi, D. Ruffolo, V. Rulev, A. Sáiz, L. Shao, O. Shchegolev, X. D. Sheng, J. R. Shi, H. C. Song, Yu. V. Stenkin, V. Stepanov, Q. N. Sun, X. N. Sun, Z. B. Sun, P. H. T. Tam, Z. B. Tang, W. W. Tian, B. D. Wang, C. Wang, H. Wang, H. G. Wang, J. C. Wang, J. S. Wang, L. P. Wang, L. Y. Wang, R. N. Wang, W. Wang, X. G. Wang, X. J. Wang, X. Y. Wang, Y. D. Wang, Y. J. Wang, Y. P. Wang, Z. Wang, Z. H. Wang, Z. X. Wang, D. M. Wei, J. J. Wei, Y. J. Wei, T. Wen, C. Y. Wu, H. R. Wu, S. Wu, W. X. Wu, X. F. Wu, S. Q. Xi, J. Xia, J. J. Xia, G. M. Xiang, G. Xiao, H. B. Xiao, G. G. Xin, Y. L. Xin, Y. Xing, D. L. Xu, R. X. Xu, L. Xue, D. H. Yan, C. W. Yang, F. F. Yang, J. Y. Yang, L. L. Yang, M. J. Yang, R. Z. Yang, S. B. Yang, Y. H. Yao, Z. G. Yao, Y. M. Ye, L. Q. Yin, N. Yin, X. H. You, Z. Y. You, Y. H. Yu, Q. Yuan, H. D. Zeng, T. X. Zeng, W. Zeng, Z. K. Zeng, M. Zha, X. X. Zhai, B. B. Zhang, H. M. Zhang, H. Y. Zhang, J. L. Zhang, J. W. Zhang, L. Zhang, L. X. Zhang, P. F. Zhang, P. P. Zhang, R. Zhang, S. R. Zhang, S. S. Zhang, X. Zhang, X. P. Zhang, Y. Zhang, Y. F. Zhang, Y. L. Zhang, B. Zhao, J. Zhao, L. Zhao, L. Z. Zhao, S. P. Zhao, F. Zheng, Y. Zheng, B. Zhou, H. Zhou, J. N. Zhou, P. Zhou, R. Zhou, X. X. Zhou, C. G. Zhu, F. R. Zhu, H. Zhu, K. J. Zhu, and X. Zuo

Subjects
Physics, Nuclear and High Energy Physics, Physics::Instrumentation and Detectors, Dynamic range, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Cosmic ray, Extension (predicate logic), Measure (mathematics), Effective nuclear charge, Nuclear physics, Air shower, Nuclear Energy and Engineering, Orders of magnitude (time), Energy (signal processing)
Abstract

The main scientific goal of LHAASO-WCDA is to survey gamma-ray sources with energy from 100 GeV to 30 TeV. To observe high-energy shower events, especially to measure the energy spectrum of cosmic rays from 100 TeV to 10 PeV, a dynamic range extension system (WCDA++) is designed to use a 1.5-inch PMT with a dynamic range of four orders of magnitude for each cell in WCDA-1. The dynamic range is extended by using these PMTs to measure the effective charge density in the core region of air shower events, which is an important parameter for identifying the composition of primary particles. The system has been running for more than one year. In this paper, the details of the design and performance of WCDA++ are presented.

Published
2021
Full Text
View/download PDF

8. Propagation of Human Corneal Endothelial Cells: A Novel Dual Media Approach

Author

Gary S. L. Peh, Zhenzhi Chng, Heng-Pei Ang, Terence Y. D. Cheng, Khadijah Adnan, Xin-Yi Seah, Benjamin L. George, Kah-Peng Toh, Donald T. Tan, Gary H. F. Yam, Alan Colman, and Jodhbir S. Mehta

Subjects
Medicine
Abstract

Corneal endothelium-associated corneal blindness is the most common indication for corneal transplantation. Restorative corneal transplant surgery is the only option to reverse the blindness, but a global shortage of donor material remains an issue. There are immense clinical interests in the development of alternative treatment strategies to alleviate current reliance on donor materials. For such endeavors, ex vivo propagation of human corneal endothelial cells (hCECs) is required, but current methodology lacks consistency, with expanded hCECs losing cellular morphology to a mesenchymal-like transformation. In this study, we describe a novel dual media culture approach for the in vitro expansion of primary hCECs. Initial characterization included analysis of growth dynamics of hCECs grown in either proliferative (M4) or maintenance (M5) medium. Subsequent comparisons were performed on isolated hCECs cultured in M4 alone against cells expanded using the dual media approach. Further characterizations were performed using immunocytochemistry, quantitative real-time PCR, and gene expression microarray. At the third passage, results showed that hCECs propagated using the dual media approach were homogeneous in appearance, retained their unique polygonal cellular morphology, and expressed higher levels of corneal endothelium-associated markers in comparison to hCECs cultured in M4 alone, which were heterogeneous and fibroblastic in appearance. Finally, for hCECs cultured using the dual media approach, global gene expression and pathway analysis between confluent hCECs before and after 7-day exposure to M5 exhibited differential gene expression associated predominately with cell proliferation and wound healing. These findings showed that the propagation of primary hCECs using the novel dual media approach presented in this study is a consistent method to obtain bona fide hCECs. This, in turn, will elicit greater confidence in facilitating downstream development of alternative corneal endothelium replacement using tissue-engineered graft materials or cell injection therapy.

Published
2015
Full Text
View/download PDF

9. Extended Very-High-Energy Gamma-Ray Emission Surrounding PSR J0622+3749 Observed by LHAASO-KM2A

Author

F, Aharonian, Q, An, Axikegu, L X, Bai, Y X, Bai, Y W, Bao, D, Bastieri, X J, Bi, Y J, Bi, H, Cai, J T, Cai, Z, Cao, J, Chang, J F, Chang, X C, Chang, B M, Chen, J, Chen, L, Chen, M J, Chen, M L, Chen, Q H, Chen, S H, Chen, S Z, Chen, T L, Chen, X L, Chen, Y, Chen, N, Cheng, Y D, Cheng, S W, Cui, X H, Cui, Y D, Cui, B Z, Dai, H L, Dai, Z G, Dai, Danzengluobu, D, Della Volpe, B, D'Ettorre Piazzoli, X J, Dong, J H, Fan, Y Z, Fan, Z X, Fan, J, Fang, K, Fang, C F, Feng, L, Feng, S H, Feng, Y L, Feng, B, Gao, C D, Gao, Q, Gao, W, Gao, M M, Ge, L S, Geng, G H, Gong, Q B, Gou, M H, Gu, J G, Guo, X L, Guo, Y Q, Guo, Y Y, Guo, Y A, Han, H H, He, H N, He, J C, He, S L, He, X B, He, Y, He, M, Heller, Y K, Hor, C, Hou, X, Hou, H B, Hu, S, Hu, S C, Hu, X J, Hu, D H, Huang, Q L, Huang, W H, Huang, X T, Huang, Z C, Huang, F, Ji, X L, Ji, H Y, Jia, K, Jiang, Z J, Jiang, C, Jin, D, Kuleshov, K, Levochkin, B B, Li, C, Li, F, Li, H B, Li, H C, Li, H Y, Li, J, Li, K, Li, W L, Li, X, Li, X R, Li, Y, Li, Y Z, Li, Z, Li, E W, Liang, Y F, Liang, S J, Lin, B, Liu, C, Liu, D, Liu, H, Liu, H D, Liu, J, Liu, J L, Liu, J S, Liu, J Y, Liu, M Y, Liu, R Y, Liu, S M, Liu, W, Liu, Y N, Liu, Z X, Liu, W J, Long, R, Lu, H K, Lv, B Q, Ma, L L, Ma, X H, Ma, J R, Mao, A, Masood, W, Mitthumsiri, T, Montaruli, Y C, Nan, B Y, Pang, P, Pattarakijwanich, Z Y, Pei, M Y, Qi, D, Ruffolo, V, Rulev, A, Sáiz, L, Shao, O, Shchegolev, X D, Sheng, J R, Shi, H C, Song, Yu V, Stenkin, V, Stepanov, Q N, Sun, X N, Sun, Z B, Sun, P H T, Tam, Z B, Tang, W W, Tian, B D, Wang, C, Wang, H, Wang, H G, Wang, J C, Wang, J S, Wang, L P, Wang, L Y, Wang, R N, Wang, W, Wang, X G, Wang, X J, Wang, X Y, Wang, Y D, Wang, Y J, Wang, Y P, Wang, Z, Wang, Z H, Wang, Z X, Wang, D M, Wei, J J, Wei, Y J, Wei, T, Wen, C Y, Wu, H R, Wu, S, Wu, W X, Wu, X F, Wu, S Q, Xi, J, Xia, J J, Xia, G M, Xiang, G, Xiao, H B, Xiao, G G, Xin, Y L, Xin, Y, Xing, D L, Xu, R X, Xu, L, Xue, D H, Yan, C W, Yang, F F, Yang, J Y, Yang, L L, Yang, M J, Yang, R Z, Yang, S B, Yang, Y H, Yao, Z G, Yao, Y M, Ye, L Q, Yin, N, Yin, X H, You, Z Y, You, Y H, Yu, Q, Yuan, H D, Zeng, T X, Zeng, W, Zeng, Z K, Zeng, M, Zha, X X, Zhai, B B, Zhang, H M, Zhang, H Y, Zhang, J L, Zhang, J W, Zhang, L, Zhang, L X, Zhang, P F, Zhang, P P, Zhang, R, Zhang, S R, Zhang, S S, Zhang, X, Zhang, X P, Zhang, Y, Zhang, Y F, Zhang, Y L, Zhang, B, Zhao, J, Zhao, L, Zhao, L Z, Zhao, S P, Zhao, F, Zheng, Y, Zheng, B, Zhou, H, Zhou, J N, Zhou, P, Zhou, R, Zhou, X X, Zhou, C G, Zhu, F R, Zhu, H, Zhu, K J, Zhu, X, Zuo, and X Y, Huang

Abstract

We report the discovery of an extended very-high-energy (VHE) gamma-ray source around the location of the middle-aged (207.8 kyr) pulsar PSR J0622+3749 with the Large High-Altitude Air Shower Observatory (LHAASO). The source is detected with a significance of 8.2σ for E25 TeV assuming a Gaussian template. The best-fit location is (right ascension, declination) =(95.47°±0.11°,37.92°±0.09°), and the extension is 0.40°±0.07°. The energy spectrum can be described by a power-law spectrum with an index of -2.92±0.17_{stat}±0.02_{sys}. No clear extended multiwavelength counterpart of the LHAASO source has been found from the radio to sub-TeV bands. The LHAASO observations are consistent with the scenario that VHE electrons escaped from the pulsar, diffused in the interstellar medium, and scattered the interstellar radiation field. If interpreted as the pulsar halo scenario, the diffusion coefficient, inferred for electrons with median energies of ∼160 TeV, is consistent with those obtained from the extended halos around Geminga and Monogem and much smaller than that derived from cosmic ray secondaries. The LHAASO discovery of this source thus likely enriches the class of so-called pulsar halos and confirms that high-energy particles generally diffuse very slowly in the disturbed medium around pulsars.

Published
2021

10. High throughput gene expression analysis identifies reliable expression markers of human corneal endothelial cells.

Author

Zhenzhi Chng, Gary S L Peh, Wishva B Herath, Terence Y D Cheng, Heng-Pei Ang, Kah-Peng Toh, Paul Robson, Jodhbir S Mehta, and Alan Colman

Subjects
Medicine, Science
Abstract

Considerable interest has been generated for the development of suitable corneal endothelial graft alternatives through cell-tissue engineering, which can potentially alleviate the shortage of corneal transplant material. The advent of less invasive suture-less key-hole surgery options such as Descemet's Stripping Endothelial Keratoplasty (DSEK) and Descemet's Membrane Endothelial Keratoplasty (DMEK), which involve transplantation of solely the endothelial layer instead of full thickness cornea, provide further impetus for the development of alternative endothelial grafts for clinical applications. A major challenge for this endeavor is the lack of specific markers for this cell type. To identify genes that reliably mark corneal endothelial cells (CECs) in vivo and in vitro, we performed RNA-sequencing on freshly isolated human CECs (from both young and old donors), CEC cultures, and corneal stroma. Gene expression of these corneal cell types was also compared to that of other human tissue types. Based on high throughput comparative gene expression analysis, we identified a panel of markers that are: i) highly expressed in CECs from both young donors and old donors; ii) expressed in CECs in vivo and in vitro; and iii) not expressed in corneal stroma keratocytes and the activated corneal stroma fibroblasts. These were SLC4A11, COL8A2 and CYYR1. The use of this panel of genes in combination reliably ascertains the identity of the CEC cell type.

Published
2013
Full Text
View/download PDF

11. A space-resolved extreme ultraviolet spectrometer for radial profile measurement of tungsten ions in the Experimental Advanced Superconducting Tokamak

Author

Y. D. Cheng, Yanmin Duan, Ling Zhang, Haiqing Liu, X.T. Yang, Wei Gao, Liqing Xu, Yong Liu, Zhenwei Wu, Yingjie Chen, Z. Xu, Shigeru Morita, Xianzu Gong, Liqun Hu, Tetsutarou Ohishi, Juan Huang, Hongming Zhang, Qing Zang, and C. R. Wu

Subjects
010302 applied physics, Physics, Nuclear and High Energy Physics, Argon, Spectrometer, chemistry.chemical_element, Tungsten, 01 natural sciences, Spectral line, 010305 fluids & plasmas, Ion, chemistry, Temporal resolution, 0103 physical sciences, Atomic physics, Spectral resolution, Instrumentation, Line (formation)
Abstract

In order to study the radial transport of tungsten ions in long-pulse H-mode discharges, a space-resolved spectrometer working at 30–520 A has been newly developed to measure a radial profile of the tungsten line emission. The spectrometer is installed behind a long extension vacuum tube connected to a horizontal midplane diagnostic port of EAST tokamak. The long distance between the plasma and spectrometer, 8835.5 mm, enables observation of the radial profile of impurity line emissions in a wide vertical range of − 8 . 5 ≤ Z ≤ 40 cm ( − 0 . 1 ≤ ρ ≤ 0 . 6 ) . A good spectral resolution of Δ λ 0 = 4 − 5 pixels at the foot position of spectral line profiles and a high spatial resolution of Δ Z = 2 . 5 cm are obtained in addition to a sufficient temporal resolution, e.g. 50 ms/frame. As a result, accurate radial profiles have been successfully obtained in EAST Ohmic and H-mode discharges for several impurity species such as carbon, oxygen, argon, iron and tungsten. The radial profiles of tungsten line emissions from W 42 + – W 45 + ions with 4p–4s transitions measured at two wavelength ranges of 45–70 A and 120–140 A are analyzed for the ion density evaluation based on the photon emissivity coefficient from ADAS database. The result shows that the density of W 43 + – W 45 + ions ranges at 2–6 × 108 cm−3 in steady H-mode discharges with T e ( 0 ) = 3 keV and n e ( 0 ) = 4 × 1013 cm−3.

Published
2019
Full Text
View/download PDF

12. Electromagnetic—rotordynamic integrated vibration analysis for electrical machines

Author

Y S Chen, J. J. Liao, Y D Cheng, and C C Chiu

Subjects
Vibration, Engineering, business.industry, Mechanical Engineering, Mechanical engineering, Structural engineering, business, Finite element method
Abstract

A systematic approach for analysing vibration-related problems of electrical machines, integrating both complex electromagnetic and rotordynamic analyses, is completely presented with an in-house finite-element solution module, formulated from related theories in rotor-dynamics. The electromagnetic analysis processes with the MagNet software are described herein to obtain the performance curves of electrical machines. They are integrated into the equation of motion to investigate the corresponding vibration characteristics. Based on the previously published work, the squirrel-cage-type induction motor is employed as an extended case study to demonstrate the integrated procedure. Three types of silicon steel core materials are considered in order to explore their effects in the dynamic properties of the system. Also, what happens on the vibration amplitude of rotor critical positions at the instant right before and after passing the critical speed are investigated thoroughly. The corresponding results exhibit that the complete procedures in using the proposed methodology can solve the reliability issues of electrical machines effectively.

Published
2009
Full Text
View/download PDF

13. Dynamic analysis of disc spring effects on the contact pressure of the collet—spindle interface in a high-speed spindle system

Author

Y S Chen, Y D Cheng, and C C Chiu

Subjects
Centrifugal force, Materials science, business.industry, Mechanical Engineering, Mechanics, Deformation (meteorology), Rotation, Finite element method, Collet, Machining, Spring (device), Drill bit, business, Computer hardware
Abstract

In a high-speed gas spindle, the drawbar force required to hold the drill bit is produced by the deformation of disc spring stacks. This drawbar force, applied to the collet—spindle interface, generates a contact pressure on the collet to hold the drill bit in position. Thus, the behaviour of the collet—spindle interface is critical to machining quality. Accordingly, this study investigated how disc spring characteristics affect the collet—spindle interface in a high-speed spindle. Typi-cally, the drawbar force will decrease following the deformation of disc springs resulting from the effects of centrifugal force at high rotational speeds. This effect must be considered, especially in high-speed spindle applications. This study first measured the drawbar force experimentally and compared these results with theoretical and finite-element analysis (FEA) data under static conditions (i.e. no rotation). Having obtained satisfactory agreement among these data, the FEA was extended to a further investigation. Properties of the collet—spindle contact interface were analysed, given changes in rotational speed from 0 to 300 000 r/min under various disc spring deflections, various friction coefficients between the disc springs and their support, and distinct taper angles at the collet—spindle interface. All of these conditions are discussed here. These essential parameters are believed to cover much of the design of high-speed gas spindle systems.

Published
2009
Full Text
View/download PDF

14. Development of a finite element solution module for the analysis of the dynamic behavior and balancing effects of an induction motor system

Author

J. J. Liao, C. C. Chiou, Y D Cheng, and Y S Chen

Subjects
Engineering, Bearing (mechanical), business.industry, Applied Mathematics, Modal analysis, General Engineering, Vibration control, Modal testing, Rotordynamics, Computer Graphics and Computer-Aided Design, law.invention, Vibration, Critical speed, Control theory, law, business, Analysis, Induction motor
Abstract

The study developed a multipurpose finite element solution module with the theoretical groundwork originated from principles of rotordynamics. This module is capable of solving many of the related rotating machine problems such as of the high speed gas bearing spindles and the electric machines. The goal of this paper is to utilize the developed solution module in investigating various aspects of the vibration behavior of an induction motor system for solving its failure problem of the shaft. Some of the crucial factors to the quality and performance of the motor, such as the vibration amplitude as resulted from the bearing wear, damping effects, mass unbalance, and the passing of system resonance critical speeds, are all investigated in the study. An efficient dual-rotor model is verified to have excellent accuracy when comparing the calculated frequency response function (FRF) with that from modal testing. The results of the transient orbit analysis indicate that the bearing stiffness and damping dominates the vibration amplitude remarkably. The effects both from the bearing damping as well as from the clamping-damping between the silicon steel core and the rotating shaft are all examined. It is noticed that the bearing damping plays the major role in the restraint of the vibration amplitudes of the rotor. For the analysis of vibration suppression with different eccentricities of the unbalanced masses, it is found that the adding of balance masses will normally suppress the vibration amplitude effectively until the point where an optimum amount that causes the minimum balanced vibration amplitudes is observed. Both the qualitative and quantitative analyses for the effectiveness of the balance mass added with different eccentricity ratios are studied. Thus, the critical adding mass ratio (i.e. the adding mass ratio at the minimum balanced amplitude factor) can also be predicted through its linear relationship with the eccentricity ratio. Based on all the findings through the study, it is concluded that the approach not only can solve the realistic shaft vibration failure problems of a motor and the demonstrated processes are also believed to be able to help the designers to have better command of motor performance at the system design stage.

Published
2008
Full Text
View/download PDF

15. METAL EXTRACTION BY ALKYL SUBSTITUTED DIPHOSPHONIC ACIDS. PART 4 P,P′-DI(2-ETHYLHEXYL) BUTANEDIPHOSPHONIC ACID

Author

John R. Ferraro, A. W. Herlinger, Paul G. Rickert, Y. D. Cheng, Renato Chiarizia, and E. P. Horwitz

Subjects
chemistry.chemical_classification, Chemistry, Vapor pressure osmometry, General Chemical Engineering, Metal ions in aqueous solution, Extraction (chemistry), General Chemistry, Phosphonate, Toluene, chemistry.chemical_compound, Nitric acid, Methylene, Alkyl, Nuclear chemistry
Abstract

As part of an ongoing investigation of the properties of dialkyl substituted diphosphonic acids as solvent extraction reagents for metal cations, we have studied the extraction of alkaline earth cations, Fe(III) and representative actinides (Am(III), U(VI) and Th(IV)) at tracer-level concentration by o-xylene solutions of P,P′-di(2-ethylhexyl) butanediphosphonic acid, H2DEH[BuDP]. The extractant and acid dependencies of these metal ions exhibited significant differences from those of the previously investigated analogous extractants in which the two phosphonate groups are separated by a methylene or an ethylene bridge. The aggregation of H2DEH[BuDP] was investigated in toluene at 25° C by vapor pressure osmometry. H2DEH[BuDP] was found to exist predominantly as a trimeric species in the 0.1-0.005 molal concentration range. Osmometric measurements and infrared spectra indicate that Ca(II) is extracted into H2DEH[BuDP] solutions with little disruption of the structure of the extractant. Iron(III) c...

Published
1998
Full Text
View/download PDF

16. Matrix-assisted laser desorption with ultra-short laser pulses

Author

Plamen A. Demirev, K. Siegbahn, W. Seibt, D. Barofsky, Per Håkansson, Bo U. R. Sundqvist, Y. D. Cheng, C.T. Reimann, and A. Westman

Subjects
Matrix-assisted laser desorption electrospray ionization, Dye laser, business.industry, Chemistry, Organic Chemistry, Analytical chemistry, Physics::Optics, Threshold energy, Laser, Analytical Chemistry, law.invention, Full width at half maximum, law, Optoelectronics, Physics::Atomic Physics, Nitrogen laser, Laser power scaling, business, Spectroscopy, Power density
Abstract

An excimer pumped dye laser generating ultra-short (560 fs full width at half maximum, FWHM) pulses in the ultraviolet (UV, 248 nm) and visible (496 nm) spectral ranges is used to desorb protein ions from different matrices. The effects of laser-light energy and power density on secondary-ion yields from insulin are reported. These data are compared to data obtained by employing a nitrogen laser (337 nm, 3 ns FWHM). The existence of a threshold energy density for the matrix-asisted laser desorbtion (MALD) of insulin ions by the ultra-short pulses is established. This threshold energy is of the same order of magnitude for the two laser systems employed and does not depend on the laser pulse length (the energy deposition time). Thus we demonstrate that the amount of laser energy deposited into the sample, rather than the laser power, is the important parameter in the MALD process.

Published
1992
Full Text
View/download PDF

17. Cyanide-induced alterations to the biophysical conformations of the isolated fish liver

Author

Y D, Cheng, T Y, Liu, and S Y, Lin

Subjects
Male, Liver, Hydrogen Cyanide, Spectroscopy, Fourier Transform Infrared, Biophysics, Animals, Water Pollutants, Biophysical Phenomena, Tilapia
Abstract

The purpose of this study is to examine the applicability of an infared spectroscopic methodology for the study of an environmental problem. The effect of cyanide concentrations on the biophysical conformation of the fish liver homogenate was determined by using an attenuated total reflectance (ATR)/Fourier transform infrared (FT-IR) microspectroscopy. Alive male model fish, Tilapia Zillii, was used. The liver from fish was isolated and homogenized in pH 8.0 Tris buffer solution. The results indicate that the IR peak intensity increased markedly in the C-H stretching range (3000-2800 cm-1), ester C = O stretching of lipids (1743 cm-1) and carbohydrate bands (1195-950 cm-1), but decreased in the amide I at 1649 cm-1 and the free asymmetric stretching band of phosphate at 1261 cm-1 with the increase of KCN concentrations. The marked release of hepatic enzymes and glutathione into homogenate induced by cyanide might account for the higher IR spectral peak intensity of fish liver tissue after treatment with KCN. The cyanide was also found to induce the protein structure of fish liver homogenate from alpha-helical conformation to beta-conformation.

Published
2001

Catalog

Books, media, physical & digital resources
See catalog results