利用 ARGO-YBJ 的月亮阴影数据对 能标的讨论 查敏 中科院高能物理研究所

Motivation: constructing an energy “anchor” Important progress on elemental CR energy spectrum from satellite/balloon-born experiments normalization and absolute energy calibration and reference for indirect measurements

ISS-CREAM ISS-CREAM is planned for launch in 2014

Direct experiment: CREAM example Few TeV region  few 100 TeV (MC )

first suggestion by Clark 1957 Deficit of CR as looking at the moon Size of the deficit --> actual angular resolution Positon of the deficit  pointing error Displacement of moon shadow  energy calibration ( size.vs. E)

Selected MOON data Using moon shadow East-West displacement to calibration Erec: The relation between Erec and Nstrip 利用地磁场的磁谱仪的作用，再加 上 ARGO 高海拔、低阈能得特点， 挑选阴影数据通过对宇宙线轻成分 在低能端能谱的测量，建立 “ 能标 ” 。

Summary of notable experiments 82 MAGIC

The energy scale error is estimated to be smaller than 13% in the energy range 1 – 30 (TeV/Z). Two systematic uncertainties may affect the Multiplicity-Energy relation: the assumed primary CR chemical composition (7%) the uncertainties of different hadronic models (6%) 55 s.d. ARGO coll., Phys.Rev. D 84 (2011) / ARGO coll., Phys.Rev. D 85 (2012) Energy calibrtion

From Menjo Hiroaki ICRC2013 (LHCf coll.)

Geomagnetic field International Geomagnetic Reference Field (IGRF) coefficients by IAGA

 Trigger: 20 pads  Rate ~3.5 kHz  Dead time 4%  First data in July 2006  Stop operation in February 2013 ARGO-YBJ Detector Low energy with digital signal High energy with analog readout

High altitude location ( 4300 m + 606g/cm 2 ) Full coverage with RPC (92% covering factor)

analysis details Shower production – Zenith angle range: 0-40° Moon shadow statistics. Vs. shower attenuation effect Moon shadow statistics Data Selection – Add more inclined showers – detailed shower information θ≤15°≤25°≤30°≤40°≤46°≤50° Moon T6%25%35%63%83%1 ( ) Sec(θ) month moon shadow -9 sigma; Theta 300

--continued < 22 m Non-light contamination ratio: 4- 6% Proton showers  steeper and narrower lateral distribution

--continued Moon shadow analysis – Direct Integration method – 0-35 °light data – LGRF model Shower production – CORSIKA package – Hadronic models: EPOS-LHC + Fluka & QGSJETII-3 + QHEISHA; – Zenith angle range: 0-40° + uniform azimuth angle; – 5 groups composition P /He /CNO/MgAlSi/Iron Detector response simulation: G4ARGO package – Core sampling 1500 x m2; Data Selection –Core: |Xc|<31 + |Yc|<31 m; – Good contained data: r + Rp70 <50 m; – Zenith < 35 deg – <22 m

Moon shadow result >2000

Preliminary result:

Summary and Outlook ARGO-YBJ is a good candidate to construct an “energy anchor”; Selection of light component is OK; Moon shadow measurement offers cross check; Preliminary result is encouraging; To finish work and understand systematic uncertainty;

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Moon shadow: an important tool to check the detector performances and offer energy calibration  10 standard deviations /month ARGO coll., Phys.Rev. D 84 (2011) / ARGO coll., Phys.Rev. D 85 (2012) Energy calibration West displacement of the shadow caused by the geomagnetic field Bending ≈ 1.58°Z/E (TeV)