Large High Altitude Air Shower Observatory KM 2

Large High Altitude Air Shower Observatory KM 2 A: • 5195 EDs: 1 m 2 each, 15 m spacing • 1171 MDs: 1146 MDs, 36 m 2 each, 30 m spacing WFCTA: 18 Cherenkov telescopes (1024 pixels/telescope) WCDA: 3200 cells (25 m 2/cell) WCDA+ + 四川稻城 (29 o 21’ 31” N, 100 o 08’ 15” E, 4410 m a. s. l. , 600 g/cm) 1.

LHAASO的宇宙线能谱测量 u 测量 10 Te. V to至Ee. V的分成分能谱 Þ 多阶段，多参数 3. 10 Pe. V-100 Pe. V: knee for iron 1. 10 Te. V-100 Te. V：�取能�； 2. 100 Te. V-10 Pe. V： H，He knees 4. >100 Pe. V: second knee

Prospects of proton, proton and helium from 100 Te. V to 10 Pe. V

4410 u LHAASO四分之一阵列 n 6 WFCT telescopes n WCDA++, namely the pound with higher dynamic range. n 300 muon detectors 6 Tel. Fo. V ¼ LHAASO Elevation of 60 toward North with full-moon duty cycle >30% above 100 Te. V

4410 u Measurement and Reconstruction WCDA • Core reconstruction: 3 m • Arrival direction reconstruction: 0. 3° • Energy flux near the core n WFCTA • SIZE (total PE in image) • Width, Length • Angular offset between arrival directions to the image center n KM 2 A - MD • Lateral distribution of Muon n * Measured Muon lateral distribution ● Average Muon lateral distribution ― Fiting proton iron

Particle Identification WCD A 4410 WFCTA KM 2 A MD pμ 1 Proton + Helium

4410 Particle identification Results ¼ LHAASO Proton+Helium Aperture ~900 ~1800 Contamination ~10% <4%

4410 Prospects for cosmic ray spectra u One year statistics, 10% duty cycle u 6 Cherenkov Telescopes 5121 6461 1130 1476 Horandel model ARGO-YBJ & WFCT Model

4410 Prospects of iron knee from 10 Pe. V to 100 Pe. V

4410 • KM 2 A: • Geometry reconstruction • 3 m， 0. 3° • No. of Muons • No. of electromagnetic particles • WFCTA: Selection criteria: 1: The cores should be in the array of KM 2 A 2: The arrival diections should be in the FOV of WFCTA (|X|<8°|Y|<7°) 3: Ntrigger>100 • Px: angular offset between shower arrival 4: Rp<400 m direction and the image center Xmax • Npe: Number of pe. in the Cherenkov image Elevation of 45° toward North duty cycle >30 with full-moon

4410 Particle Identification Ntot/Nμ Red: Proton Blue: Iron Lateral distributions of Log 10(Nch/Nμ) Normalized to 1

Particle Identification Xmax r Angula offset 4410

4410 Particle Identification and purity Iron+Mg. Al. Si The correlation is less then 0. 9

4410 Aperture and flux 200 145 Aperture for iron : 3. 5 X 105 m 2 Sr

4410 Energy Resolution