1. "Tunka-133: Results of 3 Year Operation"
Vasily Prosin (SINP MSU)
For the Tunka Collaboration

2. OUTLINE 1. Tunka experiment geography and history.
2. Methods of data processing.
3. Primary energy spectrum.
4. Methods of Xmax measurement.
5. Mean Xmax and mean lnA.
6. Further experiments in Tunka Valley.

3. 1 km
175 optical detectors
PMT EMI 9350 Ø 20 cm
635

4. Lake Baikal shore in Kultuk – gate to Tunka valley

5. Tunka Valley, River Irkut

6. Tunka District National Park

8. History of the experiments in the Tunka Valley
1992 – 4 PMTs QUASAR-370 on the ice of Lake Baikal.
1993 – 1995 – Tunka-4 – 4 PMTs QUASAR-370 in Tunka Valley.
1995 – ICRC in Roma, La Sapienza University. Start of the first International Collaboration with Gianni Navarra and A.M. Hillas.
1996 – 1999 – Tunka-13 – 13 PMTs QUASAR-370
1998 – 2000 – QUEST (5 PMTs QUASAR-370 at EAS-TOP in LNGS).
2000 – 2003 – Tunka-25, S = 0.1 km2 in Tunka Valley.
2004 – 2009 – Creating of Tunka-133 – 133 PMTs from former MACRO experiment (Idea of Gianni Navarra), S = 0.7 km2.
2011 – Expanding of Tunka-133 – 175 PMTs ,
6 distant clusters, S = 2.5 km2.

9. Start of the Tunka experiments

10. Tunka Collaboration
S.F. Beregnev, N.N. Kalmykov, N.I. Karpov, E.E. Korosteleva, V.A. Kozhin, L.A. Kuzmichev,
M.I. Panasyuk, E.G. Popova, V.V. Prosin, A.A. Silaev, A.A. Silaev(ju), A.V. Skurikhin, L.G. Sveshnikova
I.V. Yashin,
Skobeltsyn Institute of Nucl. Phys. of Moscow State University, Moscow, Russia;
N.M. Budnev, O.A. Chvalaev, O.A. Gress, A.V. Dyachok, E.N. Konstantinov, A.V. Korobchebko,
R.R. Mirgazov, L.V. Pan’kov, Yu.A. Semeney, A.V. Zagorodnikov,
Institute of Applied Phys. of Irkutsk State University, Irkutsk, Russia;
B.K. Lubsandorzhiev, N.B. Lubsandorzhiev,
Institute for Nucl. Res. of Russian Academy of Sciences, Moscow, Russia;
V.S. Ptuskin,
IZMIRAN, Troitsk, Moscow Region, Russia;
Ch. Spiering,
DESY-Zeuthen, Zeuthen, Germany;
A. Chiavassa,
Dip. di Fisica Generale Universita' di Torino and INFN, Torino, Italy.
S.N. Epimakhov, D. Horns, M. Tluczykont
Hamburg University, Hamburg, Germany

11. Search for the Acceleration Limit of Galactic Sources
Subtask: Fill the gap between the knee range and the giant arrays range.
- KASCADE-Grande
- IceTop/IceCube
Tunka-133
IceTop
IceCube
Tunka-133
V.Ptuskin and
V.Zirakashvili,2010 11

12. Primary nucleus E0 , A?
E0 ~ Q(200) Cherenkov light flux
Xmax(model independent):
Two methods:
ADF steepness (LDF replaced now ADF)
Pulse width (FWHM replaced now by τeff )
θ, φ
Xmax 2 X0 1

13. Single detector readout: Fitting of a pulse and measuring of the parameters: Q=c∙Spulse, Amax, ti , τeff=S/A/1.24
Spulse
anode: ti
Amax
dinode:

14. CORSIKA: Core location – LDF and ADF
Core location: Amplitude – Distance Function (ADF),
ADF tail fit: A(R) = A(400)·((R/400+1)/2)-bA steepness: bA
LDF tail fit: Q(R) = Q(300)·((R/300+1)/2)-bQ steepness: bQ
bA > bQ

15. ADF:
Fore different functions in the different R ranges, but a single steepness parameter bA :
R0, Rkn, c are the
functions of bA
A(R) = Akn·exp((Rkn-R)·(1+3/(R+2))/R0)
A(R) = Akn·(Rkn/R)c
A(R) = A(400)·((R/400+a)/(a+1))-b
A(R) = A(400)·((R/400+1)/2)-b

16. Light flux
Q(200) – energy measure
Q(R) = Q(300)·((R/300+1)/2)-b

17. Recalculation from Cherenkov light flux Q200 to the primary energy E0
E0 = A·Q200g
g = 0.94
CORSIKA simulation:
~ 500 protons
~ 500 iron
Zenith angles: 0°, 30°, 45°

18. Absolute energy calibration : QUEST experiment (Cherenkov detectors at EAS-TOP)
Integral spectrum p
Normalization
point for Tunka-133
P – LDF steepness (2000)

19. Single event example Plan ADF and LDF EAS time front
τeff vs. core distance A
ADF
LDF

20. Experimental data 3 winter seasons: 2009-2010 , 2010-2011, 2011-2012
165 serene moonless nights
~ 980 h of observation with a trigger frequency ~ 2 Hz
~ triggers
The cuts for the energy spectrum used:
θ ≤ 45°
Rcore < 450 m:
~ events with E0 > 6·1015 eV – 100% efficiency
~ events E0 > 1016 eV
~ 600 events E0 >1017 eV
Rcore < 800 m:
~ 1900 events E0 >1017 eV

21. Tunka-133 (2012) effective areas
450 m
800 m

22. Energy spectrum Reff < 450 m.
1 : :
Z: p He Fe

23. Energy spectrum Reff < 450 m
Primitive composition analysis in the knee (following A.Erlykin & A.Wolfendale):
p – 14%
He – 41% …
Fe – 12%
Unknown – 21%
Conclusion:
1. He dominates in the knee.
2. Unknown component can not be extragalactic or it’s spectrum is different.
3. Fe domination is not close to 100% at 8·1016 eV. .
knee He Fe p
γ=-2.7
p? – unknown

24. Energy spectrum: power law fitting
One can see two sharp features at the energies:
~2·1016 (first announced by KASCADE-Grande in 2010)
and ~3·1017 (similar to that, announced by Yakutsk and Fly’s Eye in 90th)
Statistics is insufficient at the tail so we use expanded effective area for E0 > 1017 eV .

25. Combined spectrum .
Reff>800 m

26. Combined spectrum .
The power law index at E0>1017 is similar to that obtained by the Giant Experiments:
TA, HiRes, Auger.

27. Combined spectrum: comparison with some other works.
Agreement with KASCADE-Grande
Agreement with old Fly’s Eye, HiRes and TA spectra.

28. Two methods of Xmax measurement. ADF and WDF:
R<250 m
R<450 m

29. ΔXmax by b (ADF) steepness)
CORSIKA SIMULATIONS
(Correlations are model independent)
ΔXmax by b (ADF) steepness)
ΔXmax by τeff(400)
(τeff = S/A/1.24)
~ 500 events – 107 GeV < E0 <108 GeV, θ = 0°, 30°, 45°
green – proton, red - iron

30. PHENOMENOLOGICAL APPROACH: τeff(400) vs. zenith angle E0 = 3·1016 eV
~3500 events: 16.4 < log10(E0/eV) < 16.5 
cosθ  ΔXmax = X0/cosθ – Xmax
X0 = 965 g·cm-2
Supposed: <Xmax> = 580 g·cm-2 for E0 = 3·1016 eV

31. PHENOMENOLOGY: Xmax by τeff(400)
CORSIKA
∆Xmax = 3344 – 1624∙log10(τ400), g∙cm-2

32. PHENOMENOLOGICAL APPROACH: ADF steepness vs
PHENOMENOLOGICAL APPROACH: ADF steepness vs. zenith angle E0 = 3·1016 eV
~3500 events: 16.4 < log10(E0/eV) < 16.5 
cosθ  ΔXmax = X0/cosθ – Xmax
X0 = 965 g·cm-2
Supposed: <Xmax> = 580 g·cm-2 for E0 = 3·1016 eV

33. PHENOMENOLOGY: Xmax by the ADF steepness
CORSIKA
∆Xmax = 2865 – 3519∙log10(bA-2), g∙cm-2

34. Experimental estimation of Xmax measurement errors
Difference of Xmax derived from ADF steepness bA and τeff(400)
σapp = σmes/√2
More exactly: σb = 25 g·cm-2, στ=30 g·cm-2
The main is ADF method having better accuracy and
lower energy threshold

35. <Xmax> vs. E0
For <Xmax> estimation the events with the difference:
Xmax-ADF – Xmax-τ > 3σ
are excluded

36. EXPERIMENTAL Xmax DISTRIBUTIONS

37. ANALYSIS of Xmax DISTRIBUTIONS PRELIMINARY (the final version will be presented by S.Epimakhov at ICRC)
Fit with weighted sum of 4 group MC simulated distributions: Fe, CNO, He, p

38. Xmax DISTRIBUTION in the last 3 points

39. Analysis of Xmax DISTRIBUTION PRELIMINARY (the final version will be presented by S.Epimakhov at ICRC)
Fit with weighted sum of 4 group MC simulated distributions: Fe, CNO, He, p
We hope to get the partial group energy spectra from this analysis (to be presented at ICRC)

40. Agreement with HiRes-MIA and Auger results at 1017 – 1018 eV
<Xmax> vs. E0
Agreement with HiRes-MIA and Auger results at 1017 – 1018 eV

41. EXPERIMENT: MEAN <lnA> vs. E0

42. EXPERIMENT: MEAN <lnA> vs. E0

43. Conclusions
1. The spectrum from to eV cannot be fitted with single power law index:
γ = 3.23 ± ·1015 < E0 < 2·1016 eV.
γ = ·1016 < E0 < 3·1017 eV.
γ = 3.33 ± E0 > 2·1017 eV.
2. Agreement with KASCADE-Grande results.
3. The high energy tail do not contradict to the Fly’s Eye, HiRes and TA spectra.
4. The Xmax do not contradict to that of HiRes-MIA and Auger data.
5. Composition change to heavy from 1016 to 3·1016, stay heavy to 1017 and start change to light from ~1017 eV

44. Further Experiments in Tunka Valley
Tunka-REX (the next talk of D. Kostiunun)
Tunka-HiSCORE (M.Kunnas poster, R.Wischnewski report)
- Scintillation counters from KASCADE-Grande to measure Ne and Nμ

45. Scintillation counter of
KASCADE-Grande
(800х800х40)
Underground container
On surface hut

46. HiSCORE project – wide-angle gamma-telescope with area 100 km2 and threshold 30 TeV (M.Tluczykont et al , ArXiv: and yesterday report)
HiSCORE:Hundred i Square-km Cosmic ORigin Explorer
Time schedule
1.First SCORE Station will be installed at Tunka
in this summer-autumn
25 station at 2012 –
1 sq. km wide-angle gamma telescope
Energy spectrum from eV -
compare with Tunka-25 and Tunka-133 results

47. Тunka-HiSCORE : wide-angle Cherenkov gamma-observatory
Area : from 1 to 100 km2
FOV ~ 0.6 ster ( ± 30° )
Energy threshold ~ 20 TeV
Total cost ~ 50 ·106 Euro
HiSCORE – Hundred* i Square-km Cosmic Origin Explorer

48. Calibration
light source
4 PMTs
Station Electronics

50. Thank You!