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 moonSize of the deficit --> actual angular resolutionPositon of the deficit pointing errorDisplacement 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

82MAGIC

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) 022003 / ARGO coll., Phys.Rev. D 85 (2012) 022002

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/cm2)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 T 6% 25% 35% 63% 83% 1 (105276.)

Sec(θ) 1.04 1.1 1.15 1.3 1.44 1.55

1 month moon shadow -9 sigma;Theta< 30 deg + |xc|<31 + |yc|<31 + Ns>300

--continued

<R> < 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 15000 m2;• Data Selection

– Core: |Xc|<31 + |Yc|<31 m;– Good contained data: r + Rp70 <50 m;– Zenith < 35 deg– <R> <22 m

Moon shadow result

400-800 800-1000

1000-2000 >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;

backup

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) 022003 / ARGO coll., Phys.Rev. D 85 (2012) 022002

Energy calibration

West displacement of the shadow caused by the geomagnetic field

Bending ≈ 1.58°Z/E (TeV)