Tunka-133: results and status

L.A.Kuzmichev (MSU SINP)

On behalf of the Tunka Collaboration

4.06.2012

23th ECRS, MOSCOW

S.F.Beregnev, S.N.Epimakhov, N.N. Kalmykov, N.I.KarpovE.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, A.L.Pahorukov, Yu.A. Semeney, A.V. Zagorodnikov Institute of Applied Phys. of Irkutsk State University, Irkutsk, Russia;

B.K. Lubsandorzhiev, B.A. Shaibonov(ju) , N.B. Lubsandorzhiev Institute for Nucl. Res. of Russian Academy of Sciences, Moscow, Russia;

V.S. Ptuskin IZMIRAN, Troitsk, Moscow Region, Russia;

Ch. Spiering, R. Wischnewski DESY-Zeuthen, Zeuthen, Germany;

A.Chiavassa Dip. di Fisica Generale Universita' di Torino and INFN, Torino, Italy.

A.Haungs, F. SchroederKarlsruhe Institute of Technology, Karlsruhe, Germany

Tunka Collaboration

OUTLINE

1. Tunka-133.

2. Energy spectrum.

2. Mass composition ( V.Prosin report, at next session)

3. Plan for the Tunka-133 upgrading.

Tunka-133 – 1 km2 “dense” EAS Cherenkov light array

Energy threshold 1015 eV

Accuracy: core location ~ 10 m energy resolution ~ 15% Xmax < 25 g∙cm-2

Tunka-133: 19 clusters, 7 detectors in each cluster

Optical cableClusterElectronic box

DAQcenter

PMTEMI 9350Ø 20 cm

4 channel FADC boards 200 MHz, 12 bit

4 channel FADCCherenkov light pulses at two detectors of a cluster at the core distance of ~ 700 m1. ADC AD9430, 12 bit, 200 MHz

2. FPGA XILINX Spartan-3

t ( 5 ns)

1 км

2011

To the ultra-high energy!Tunka-133 is extended by 6 distant external clusters

Energy reconstruction

E = A (Q200) g

Density of Cherenkov light at core distance of 200 m

For 1016 – 1018 eV (CORSIKA):

g = 0.94±0.01

Absolute energy calibration :The QUEST experiment ( Cherenkov detectors at EAS-TOP)

P – steepness of LDF (Lateral Distribution Function)

p

Integral spectrum

Normalizationpoint for Tunka-133

σsys(E) = 8%

3 winter seasons of the array operation:165 moonless nights with good weather, 971 hours

Tunka-133 was installed in 2009

- 2009 – 2010: 286 hours of good weather ( November 2009 – March 2010) - 2010 – 2011: 305 hours of good weather (October 2010 – April 2011)-2011 – 2012 : 380 hours of good weather(October 2011 – April 2012) 6106 events with energy 1015 eV.

IN-events:Core position inside circle: R < 450m Zenith angle < 45°

2009-2012

>1016 eV: 63490

>1017 eV: 605

OUT- events: R <800 m

> 1017 eV: 1900

800 m

450m

Tns

T ns = (R+200/R0 )2 ×3.3 ns

Shower front

ADF

LDF

ADF – amplitude distant function is used for core location

WDF – width distant function

WDF

Shower front

Accuracy of out -events reconstructionWith external clusters Without external clusters

<lg(E1 / E2> = 0.02

E1 E2

σ (lg (E1/E2)) =0.05

1900 events > 1017 eV

6

2148

Combined energy soectrum

Comparison of spectras

2009 -2011 2009-2012

γ~ 3.0γ~ 3.3

Secondknee

~3 ·1017 eV

γ 1 = 3.24 ±0.01

γ 2 = 2.97 ±0.01

γ 3 = 3.4 ±0.14

γ 3 = 3.12 ±0.05

OUT-events in 1000 m radius

Second knee at (2-3) 1017 eV seems to be more adequate to the data

Eshift = 0.95· E0

σsys(E) = 8% At E= 6 1015 eV

From QUEST experiment

σsys(E) = 15%

At 1018 eV

due to uncertainty in g

Conclusions

1. The spectrum in the energy range of 1016 to 1018 eV cannot be fitted with single power law index

3.24 ±0.01 (6·1015 – 2·1016 eV) 2.97 ±0.01 (2·1016 – 1017 eV) 3.40 ± 0.14 (3 ·1017 – 1018 eV)

2. There is an indication on the second knee at ~3·1017 eV

3. Tunka spectrum = K-Gr spectrum inside energy reconstruction systimatics. The key question – to increase accuracy of absolute energy calibration. Is it possible to have 5% accuracy?

4. More statistics is needed at the energy range 1017 – 1018 eV The array will continue data taking for another 4-5 seasons.

Plans for upgrading I

1. Deployment of scintillation array for the absolute energy calibration at 3·1016 – 1017 eV (the new QUEST experiment).

2. Deployment of fluorescent detector at 7-10 km distance from the array for joint operation.

Absolute energy calibration experiment.Repeating the “QUEST” at 1016 -1017 eV

-20 scintillation counters, 10 m2

Lg (Ne / E, Tev)

p

-P

-Fe

Zenith-angle: 0º -45ºEnergy: 1016 – 1017 eV

P – steepness of LDF

2000 events with E >3·1016 eV per season

Cross calibration of Cherenkov light and fluorescent light methods.

Image detector from TUS experiment

7-10 км

S= 2 -10 м2

Угол обзора ± 7 град

Frenel mirror for TUS experiment

Plan for upgrading II

- Net of radio antennae ( poster of F.Schreoder) Tunka-REX ( Radio Extension)

- Gamma astronomy at Tunka (report of M.Tluzcykont)

HiSCORE

Tunka : 2013

M.Tluczykont, July 6, Friday F.Shreoder,

poster,

Thank you

New approach to core reconstruction

A(R) = A(400)·((R/400+1)/2)-bQ(R) = Q(300)·((R/300+1)/2)-b

QDF