Study of VHE Cosmic Ray Study of VHE Cosmic Ray Spectrum by means of Muon Spectrum by means of Muon Density Measurements at Ground Density Measurements at Ground Level Level I I . . I I . . Yashin Yashin Moscow Engineering Physics Institute Moscow Engineering Physics Institute , , [email protected][email protected]Vulcano 2008, 26th- 31st May
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Study of VHE Cosmic Ray Spectrum by means of Muon Density Measurements at Ground Level
Vulcano 2008, 26th-31st May. Study of VHE Cosmic Ray Spectrum by means of Muon Density Measurements at Ground Level. I . I . Yashin Moscow Engineering Physics Institute , [email protected]. Vulcano 2008, 26th-31st May. - PowerPoint PPT Presentation
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Study of VHE Cosmic Ray Spectrum Study of VHE Cosmic Ray Spectrum by means of Muon Density by means of Muon Density
Measurements at Ground LevelMeasurements at Ground Level
II..II.. Yashin Yashin
Moscow Engineering Physics InstituteMoscow Engineering Physics Institute, , [email protected]@mephi.ru
Vulcano 2008, 26th-31st May
A.G. Bogdanov, R.P. Kokoulin, G. Mannocchi, A.A. Petrukhin, A.G. Bogdanov, R.P. Kokoulin, G. Mannocchi, A.A. Petrukhin, O. Saavedra, V.V. Shutenko, G. Trinchero, I.I. YashinO. Saavedra, V.V. Shutenko, G. Trinchero, I.I. Yashin
ContentsContents
1. Motivation2. Local muon density phenomenology3. DECOR data VS simulation4. Conclusions
Moscow Engineering Physics Institute, RussiaMoscow Engineering Physics Institute, RussiaIstituto Nazionale di Astrofisica, Sezione di TorinoIstituto Nazionale di Astrofisica, Sezione di TorinoUniversita di Torino, ItalyUniversita di Torino, Italy
Vulcano 2008, 26th-31st May
MotivationMotivation
In EAS data interpretation, primary spectrum, composition, interaction characteristics, and
their energy dependence are unknown.
To solve the problem involving several unknown functions, measurements of different
EAS observables are necessary.
In this talk, phenomenology and recent data on a new EAS observable – local muon density distributions in a wide range of zenith angles – are considered.
Vulcano 2008, 26th-31st May
Local muon density phenomenologyLocal muon density phenomenology If the size of the detector is small compared to typical distances of substantial changes of muon LDF, the detector may be considered as a point-like probe. In a muon bundle event, the local muon density D (in a random point of the shower) is estimated:
D = (number of muons) / (detector area); [D] = particles / m2.
Collection area rapidly increases with zenith angle (~ 1 km2 at 80)
Vulcano 2008, 26th-31st May
Local muon density phenomenologyLocal muon density phenomenologyWithout considering fluctuations, spectrum of events in local density
may be written as [Kokoulin at al., 2005]
where N (> E) - primary spectrum, E is defined by the equation:
F D N E r ,D dS,
E,r D
[ events / (s sr)]
For a nearly scaling LDF around some energy For a nearly scaling LDF around some energy EE00
0 0 0 9E,r E E E ,r , .
and power type primary spectrum 0
N E A E E ,
0 2F D AD E ,r dS, /
Vulcano 2008, 26th-31st May
/ ( / ) / ( , ) /dF dD dN dE dS d E r dE
General view of NEVOD-DECOR complexGeneral view of NEVOD-DECOR complex
Side SM: 8.4 m2 each• σx 1 cm; σψ 1°
Coordinate-tracking detector DECOR (~115 m2)
Cherenkov water detector NEVOD (2000
m3)
Vulcano 2008, 26th-31st May
A typical muon bundle event in Side DECORA typical muon bundle event in Side DECOR
Large angles: around 10Large angles: around 101818 eV eV
Vulcano 2008, 26th-31st May
ConclusionsConclusions 1 1 LMDS methodLMDS method
1. A new approach based on local muon density spectrum phenomenology provides possibility to study PCR in a very wide energy range (from 1015 to 1019 eV) by means of a single, not large detector.
2. Local muon density spectra are sensitive to primary spectrum and composition and forward region of hadronic interactions.
3. Analysis of local muon density spectra together with data of experiments on other EAS observables will allow putting new constraints on combinations of spectrum, composition and interaction models.
Vulcano 2008, 26th-31st May
Conclusions 2Conclusions 2
DECOR data analysisDECOR data analysis
are in a reasonable agreement with expectation in the knee energy region;
favor an increase of the effective primary mass at approaching energies 1017 eV;
indicate an increase of local muon density spectrum slope at effective primary energy around 1017 eV.
Within the frame of the considered spectrumand interaction models, DECOR data: