What we do know about cosmic rays at energies above 10 15 eV?
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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
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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
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• 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)
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EAS generated of various nucleiEAS generated of various nuclei
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Existing approach to EAS analysisExisting approach to EAS analysis
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Results of energy spectrum Results of energy spectrum investigationsinvestigations
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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
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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
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Results of mass composition Results of mass composition investigationsinvestigations
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Energy spectrum of various CR nucleiEnergy spectrum of various CR nuclei
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CR mass composition at low energiesCR mass composition at low energies
< lnA > 1.5
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Mass composition from Mass composition from NN//NNee measurements measurements
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Jörg R. Hörandel, 2007
Existing explanation of CR spectrumExisting explanation of CR spectrum
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Mass composition from Mass composition from XXmaxmax measurements measurements
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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.
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New method New method of EAS investigationsof EAS investigations
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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.
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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
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Traditional EAS detection technique (E ~ 1018 eV)
EA
S c
ou
nte
rs (
~ 1
m
2)
~ 5
00
m
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E ~ 1018 eV, θ=80º
~ 10 km
Muon detector
Local muon density spectra Local muon density spectra detection techniquedetection technique
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Contribution of primary energies Contribution of primary energies at different zenith anglesat different zenith angles
Wide angular interval – very wide range of primary energies !
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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
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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)
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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
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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
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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
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Muon bundle event (geometry reconstruction)Muon bundle event (geometry reconstruction)
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Results of muon bundle Results of muon bundle investigationsinvestigations
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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.
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Effective primary energy ranges
Lower limit ~ 1015 eV (limited by DECOR area).Upper limit ~ 1019 eV (limited by statistics).
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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
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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
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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.
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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..
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BaksanBaksan underground scintillation telescopeunderground scintillation telescope
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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
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Hermann Kolanoski, 32nd ICRC, 2011, Beijing
IceCubeIceCube
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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
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Patrick Berghaus, 31st ICRC, 2009, Lodz
IceCubeIceCube muon energy spectrum - 2009muon energy spectrum - 2009
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Patrick Berghaus, Chen Xu, 32nd ICRC, 2011, Beijing
IceCubeIceCube muon energy spectrum - 2011muon energy spectrum - 2011
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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
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Interaction model
EAS
Nei DEh C. C. xmax Nj
Energy spectrum
Composition
E
New approach to EAS investigationsNew approach to EAS investigations
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Possibilities of NEVOD-DECOR experiment Possibilities of NEVOD-DECOR experiment
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Energy deposit of muon bundlesEnergy deposit of muon bundles
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Expected results of muon energy Expected results of muon energy deposit measurementsdeposit measurements
E1
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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.
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Thank you for attention!Thank you for attention!