What we do know about cosmic rays What we do know about cosmic rays at energies above 10at energies above 101515 eV? eV?

A.A.Petrukhin A.A.Petrukhin

ContentsContents

4th Round Table, December 16 - 17, 2011

1. Introduction.

2. How these CR are investigated.

3. Results and questions.

4. New approach to CR investigations.

5. NEVOD-DÉCOR experiment.

5. Further steps.

6. Conclusion.

National Research Nuclear University MEPhI, RussiaNational Research Nuclear University MEPhI, Russia

Why these energies are interesting?Why these energies are interesting?

1015 eV in p-p – interactions corresponds to

~ 1 TeV in the center-of-mass system.

Interval 1015 – 1017 eV corresponds to

LHC energies 1.4 – 14 TeV.

There are no direct measurements of CR energy spectrum and mass composition above 1015 eV.

In indirect experiments above 1015 eV changes in CR energy spectrum and mass composition have been observed.

IntroductionIntroduction

• EAS – the single source about PCR at energies above 1015 eV.

• EAS consists of hadrons, muons, electrons, positrons, photons, neutrinos.

• EAS radiates Cherenkov fluorescent, radio, acoustic radiations.

Extensive Air Shower (EAS)Extensive Air Shower (EAS)

EAS generated of various nucleiEAS generated of various nuclei

Existing approach to EAS analysisExisting approach to EAS analysis

Results of energy spectrum Results of energy spectrum investigationsinvestigations

1 particle/m2 s

“Knee”

“Ankle”

Ground based measurements

~ 5104 m2KASCADE

0 4km

AGASA

100 km2

Pierre Auger Observatory

50 km

3000 km2

1 particle/ m2 year

1 particle/ km2 year

1 particle/ km2 century

Dir

ect

m

easu

rem

en

ts

AMS2

Fermi LAT

E (эВ/ядро)

E2

.7·d

N/d

E (

см-2

·ст

ер-1

·сек

-1·Г

эВ1

.7)

Peculiarities of CR energy spectrumPeculiarities of CR energy spectrum

Results of mass composition Results of mass composition investigationsinvestigations

Energy spectrum of various CR nucleiEnergy spectrum of various CR nuclei

CR mass composition at low energiesCR mass composition at low energies

< lnA > 1.5

Mass composition from Mass composition from NN//NNee measurements measurements

Jörg R. Hörandel, 2007

Existing explanation of CR spectrumExisting explanation of CR spectrum

Mass composition from Mass composition from XXmaxmax measurements measurements

Conclusion - 1

Satisfactory description of primary CR in the whole measured interval of energies is absent, especially at highest energies. (May be any processes around BH are sources of these CR?)

There are contradictions between different mass composition measurements..

One of possible reasons is a short dynamic interval of measured energies (~ 102) by EAS detectors.

Therefore the development of new approaches to CR investigations which can give new information in a wide energy interval is required.

New method New method of EAS investigationsof EAS investigations

Inclined EAS detectionInclined EAS detection(local muon density measurements)(local muon density measurements)

Advantages: - practically pure muon component; - large area of showers, which increases with energy;

- strong dependence of EAS energy on zenith angle.

μμ--EAS transverse section VS zenith angleEAS transverse section VS zenith angle

Number of detected EAS depends on:Number of detected EAS depends on:

array dimensions shower dimensions

Traditional EAS detection technique (E ~ 1018 eV)

EA

S c

ou

nte

rs (

~ 1

m

2)

~ 5

00

m

E ~ 1018 eV, θ=80º

~ 10 km

Muon detector

Local muon density spectra Local muon density spectra detection techniquedetection technique

Contribution of primary energies Contribution of primary energies at different zenith anglesat different zenith angles

Wide angular interval – very wide range of primary energies !

New technique of Local Muon Density New technique of Local Muon Density

Spectra was realized by means ofSpectra was realized by means of

Experimental complex Experimental complex NEVOD-DECORNEVOD-DECOR

Russian-Italian Collaboration Russian-Italian Collaboration

National Research Nuclear University MEPhI, RussiaNational Research Nuclear University MEPhI, RussiaIstituto di Fisica dello Spazio Interplanetario, INAF, Istituto di Fisica dello Spazio Interplanetario, INAF, Torino, ItalyTorino, ItalyDipartimento di Fisica Generale dell’ Universita di Torino , ItalyDipartimento di Fisica Generale dell’ Universita di Torino , Italy

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)

A typical muon bundle event in Side DECORA typical muon bundle event in Side DECOR( 9 muons, 78 degrees)( 9 muons, 78 degrees)

3468:0 3319:1 3290:2 3094:3

0:3264

SM=0 1:3216 2:3072 3:3207

3621:0 3336:1 3270:2 3294:3

0:2987

SM=1 1:3147 2:3051 3:3146

3514:0 3384:1 3110:2 3158:3

0:3596

SM=2 1:3446 2:4148 3:3509

3649:0 3511:1 3353:2 3378:3

0:3476

SM=3 1:3205 2:3331 3:3000

7190:0 3453:1 3239:2 3388:3

0:3705

SM=4 1:3597 2:3600 3:3859

4073:0 3360:1 4413:2 3888:3

0:3405

SM=5 1:3394 2:3410 3:3626

3623:0 3554:1 3470:2 3444:3

0:3521

SM=6 1:3532 2:3429 3:3159

3564:0 3299:1 3058:2 3303:3

0:3871

SM=7 1:3568 2:3545 3:3697

01234567

01234567

Plate1:Step=25nsec

Plate2:Step=25nsec

Run 8 --- Event 219242 ----06-12-2004 23:25:26.27 Trigger(1-16):01110100 00000000 Weit_Time:109.072 msec

X-projection Y-projection

Muon bundle event (geometry reconstruction)Muon bundle event (geometry reconstruction) Nlam=40,N5=26,N6=23,NR1=0 ,NR2=0 ,Sum1=0 ,Sum2=0 ,Sob-00000001,00000000

N1=35,N3=14 nCup= 0 SumAmp=1.26e+03 01110100,00000000 NGroup2=8,n=8,n1=8,n2=9,n0=8,nx=9,ny=8,One=0N2=32,N4=13 nCdow n= 0 NPMT=143 ETel= 0.0% ERec= 60.8%

Date=06-12-04 23:25:26.027 Nevent=219242 Group: fm=53.15 tm=77.87 Recon: f i=54.41 t=80.70 F= 0.0

4873:0 3644:1 3754:2 3814:3

0:3923

SM=0 1:3332 2:3387 3:3266

3859:0 4199:1 3877:2 5106:3

0:3054

SM=1 1:3101 2:3351 3:3591

3562:0 3149:1 3376:2 3672:3

0:3570

SM=2 1:3435 2:3511 3:3948

4000:0 4098:1 4109:2 4255:3

0:3619

SM=3 1:3601 2:3894 3:3760

3786:0 3732:1 3712:2 4030:3

0:3750

SM=4 1:3582 2:3655 3:3992

4000:0 3388:1 3477:2 4119:3

0:3641

SM=5 1:3639 2:3849 3:4104

4050:0 4120:1 4164:2 5038:3

0:3609

SM=6 1:3508 2:3684 3:3647

3961:0 3769:1 3844:2 4323:3

0:4245

SM=7 1:3814 2:4037 3:4338

3352:0 3438:1 3922:2 4134:3

0:4850

SM=8 1:4191 2:3898 3:5122

3181:0 3942:1 5269:2 5326:3

0:3347

SM=9 1:3879 2:3924 3:4615

3820:0 4458:1 4688:2 4870:3

0:475

SM=10 1:5515 2:5367 3:6392

3239:0 3452:1 4038:2 4575:3

0:3800

SM=11 1:5594 2:4104 3:4670

01234567

01234567

Plate1:Step=25nsec

Plate2:Step=25nsec

Run 242 --- Event 847205 ----05-05-2003 06:11:04.43 Trigger(1-16):01110101 00111100 Weit_Time:30.065 msec

A “record” muon bundle eventA “record” muon bundle event

X-projection Y-projection

Muon bundle event (geometry reconstruction)Muon bundle event (geometry reconstruction)

Results of muon bundle Results of muon bundle investigationsinvestigations

DECOR data. Muon bundle statisticsDECOR data. Muon bundle statistics

Muon multiplicityZenith angle range

(*)Live time,

(hour)Number of

events

3 30 – 60 758 18137

5 30 – 60 1296 8864

10 30 – 60 2680 3272

3 60 1552 4109

5 60 10102 6786

10 60 19922 2013

10 75 19922 395

(*) For zenith angles < 60°, only events in two sectors of azimuth angle (with DECOR shielded by the water tank) are selected.

Effective primary energy ranges

Lower limit ~ 1015 eV (limited by DECOR area).Upper limit ~ 1019 eV (limited by statistics).

Low angles: around the “knee” θ = 50º : 1016 – 1017 eV

θ = 65º : 1016 – 1018 eV Large angles: around 1018 eV

Local muon density spectraLocal muon density spectra

17.5 18.0 18.5 19.0 19.5

1

10

Q1

S

E1.6E1.9

Q2

Q1

S

E1.6

E1.9Q2

> 80 o

Onlyiron

AGASA HiRes-1 HiRes-2 Auger-2011 (combined spectrum) TA-2011 (surface detectors)

E 3

dN

/dE

/ 1

0 24 , e

V 2 m

-2 s

-1 s

r -1

log 10

(E, eV)

Onlyprotons

DECOR-2010 > 75 o

Comparison with other data Comparison with other data

Conclusion - 2Conclusion - 2A new method of EAS investigations allows investigate

cosmic ray energy spectrum in very wide interval from 1015 to 1018 eV and even higher.

The following results were obtained: - detection of the knee (this can be considered as energy scale calibration), - observation of the second knee, - some excess of muon bundles in comparison with predictions, which increases with energy.

The last result was confirmed in fact in LHC experiment.

Discussion

Apparently the change of hadron interaction model at least in multiplicity of secondary particles in nuclei-nuclei collisions has been observed.

More interesting is another question: This change of multiplicity is a simple increasing of number of secondary particles (and as the consequence – number of muons) or it is a change of energy distribution in favor of high energies?

Muon energy is the single parameter which is not measured at existing EAS arrays.

But there are other experimental results which allow get answer this question. They were obtained in BUST and IceCube experiments..

BaksanBaksan underground scintillation telescopeunderground scintillation telescope

103 104 105 106

0.01

0.1

Frejus, 1994 MACRO, 1995 LVD, 1998 Artyomovsk, 1988 Baksan, 1992 MSU, 1994

model 1 usual from , K

model 2 usual + prompt (R = 10-3)

model 3 usual + prompt (R = 3*10-3) model 4 usual + VHE

E3 dN

/dE

, c

m-2 s

-1 s

r-1 G

eV2

E, GeV

1

2

3

4

103 104 105 106

0.01

0.1

Frejus, 1994 MACRO, 1995 LVD, 1998 Artyomovsk, 1988 Baksan, 1992 MSU, 1994 Baksan (pair meter), 2009 model 1 usual from , K

model 2 usual + prompt (R = 10-3)

model 3 usual + prompt (R = 3*10-3) model 4 usual + VHE

E3 dN

/dE

, c

m-2 s

-1 s

r-1 G

eV2

E, GeV

1

2

3

4

Muon energy spectrumMuon energy spectrum

Hermann Kolanoski, 32nd ICRC, 2011, Beijing

IceCubeIceCube

IceCube Collaboration, 32nd ICRC, 2011, Beijing

Candidate shower with a high pT muon. The cosmic ray bundle is on the left and the high pT muon is on the right.

Muons in IceCubeMuons in IceCube

Patrick Berghaus, 31st ICRC, 2009, Lodz

IceCubeIceCube muon energy spectrum - 2009muon energy spectrum - 2009

Patrick Berghaus, Chen Xu, 32nd ICRC, 2011, Beijing

IceCubeIceCube muon energy spectrum - 2011muon energy spectrum - 2011

Conclusion - 3Conclusion - 3New(?) physics in cosmic rays:

In CR experiments have been observed: - not only increasing of number of muons in EAS with the

increasing of their energies, which has been confirmed in LHC experiments,

- but the excess of very high energy muons (>100 TeV)!

The excess of very high energy muons (>100 TeV) can be produced in decays of heavy particles (or other states of matter) with mass ~ 1 Tev only.

This is This is a new task for both cosmic ray a new task for both cosmic ray andand LHC experimentsLHC experiments

Interaction model

EAS

Nei DEh C. C. xmax Nj

Energy spectrum

Composition

E

New approach to EAS investigationsNew approach to EAS investigations

Possibilities of NEVOD-DECOR experiment Possibilities of NEVOD-DECOR experiment

Energy deposit of muon bundlesEnergy deposit of muon bundles

Expected results of muon energy Expected results of muon energy deposit measurementsdeposit measurements

E1

Conclusion - 4Conclusion - 4

Measurements of local muon density spectra with coordinate detector DECOR and muon bundle energy deposit with Cherenkov water detector NEVOD compose a new promising method of the search of new processes of muon generation in cosmic rays.

This experiment will start in the beginning of 2012.

Thank you for attention!Thank you for attention!