A.A.PetrukhinA.A.Petrukhin

National Research Nuclear University MEPhI, National Research Nuclear University MEPhI, Moscow, RussiaMoscow, Russia

New ideas about cosmic ray New ideas about cosmic ray investigations above the kneeinvestigations above the knee

Contents:1. Introduction.2. Cosmophysical approach.3. Nuclear-physical approach.4. Explanation of unusual events in CR.5. Role of nuclei-nuclei interactions.6. How to check new approach?7. Conclusion.

Introduction Introduction

• 100 years of cosmic rays and 50 years of the knee.

• In the 1st paper (Kulikov & Khristiansen, 1958) both possible interpretations of the knee origin (cosmophysical and nuclear-physical) were discussed.

• Both these interpretations are connected with problem of cosmic ray origin (galactic or extragalactic).

• But the knee itself is the result of interpretation of measured EAS parameters.

Existing approach to EAS analysisExisting approach to EAS analysis

Basic ideas of the existing approach Basic ideas of the existing approach

EAS energy is equal to the energy of primary particle.

All changes of EAS characteristics in dependence on energy are results of energy spectrum or/and composition changes only.

Primary cosmic rays have galactic origin.

Their acceleration and keeping in Galaxy are determined by their charge Z or/and mass A.

And the following results were obtained:

Results of energy spectrum “measurements”Results of energy spectrum “measurements”

Really, in the best case, EAS energy can be evaluated.

Results of energy spectrum interpretationResults of energy spectrum interpretation

Results of composition “investigations”Results of composition “investigations”

Really, N / Ne – ratio and Xmax are measured.

Results of XResults of Xmaxmax measurements measurements

Some remarksSome remarks

• In spite of interesting ideas and numerous calculations of not one generation of scientists, a satisfactory description of changes of the energy spectrum and mass composition above the knee in frame of the cosmophysical approach

has not been found.

• Experimental results of N/Ne and Xmax measurements contradict this approach.

• The problem of UHE cosmic ray origin is not clear. If the sources of such particles exist in other galaxies, why they do not exist in our Galaxy?

Basic ideas of nuclear-physical approachBasic ideas of nuclear-physical approach

Naturally, in this case primary cosmic ray spectrum and composition are not changed and their sources must be the same in the whole Universe.

EAS energy is not equal to primary particle energy:

EEAS = E2 < E1

The knee is the result of inclusion of new processes of interaction or/and production of new particles, states of matter, etc.

Two main difficulties Two main difficulties of nuclear physical approachof nuclear physical approach

• Large cross section of new processes which is required to change the cosmic ray energy spectrum.

Many physicists speak about new physics (new particles, etc.) in TeV energy region (in the center of mass system which corresponds to PeV energy region in cosmic ray experiments) but with low cross sections: nb or pb.

• Where the difference between primary particle energy and EAS energy disappears?

In favor of possibility of appearance of new processes (particles, states of matter, etc.) evident numerous unusual events which were detected in various experiments at energies above the knee.

List of unusual eventsList of unusual events In hadron experiments:

In EAS investigations (in this approach we can consider):

Important: Unusual events appear at PeV energies of primary particles.

halos, alignment, penetrating cascades, Centauros (Pamir-Chacaltaya);

long-flying component, Anti-Centauros (Tien-Shan).

In muon experiments:excess of VHE (~ 100 TeV) single (MSU) and multiple (LVD) muons;

observation of VHE muons (Japan, NUSEX), the probability to detect which is very small.

change of EAS energy spectrum in the atmosphere, which now is interpreted as a change of primary energy spectrum.

changes of behavior of N(Ne) and Xmax(Ne) dependences, which now are explained as the heaving of composition.

1 mm

1 cm

1 mm

1 cm

a)

b)

no.108

no.383

no.386

no.586

no.295

no.403

no.420

no.539

1 mm

Halo and alignmentHalo and alignment

Penetrating cascadesPenetrating cascades

Total Energy = 257.79 [TeV]tan =1.0

66.4[TeV] 45.4[TeV]27.5[TeV] 40.3[TeV]

5.2[TeV]39.6[TeV]23.0[TeV]

10.4[TeV]

Depth [cmPb]

Da

rkn

ess

0

1

Depth [cmPb]/cos

0 10 20 30 40 50 60

0 14 28 42 56 70 84

0.1

1

Muon flux excessMuon flux excess

Excess of muon bundlesExcess of muon bundles

The knee as a result of new interactionThe knee as a result of new interaction

In this case a difference between primary and EAS energies, so-called missing energy, appears.

EASenergy

primaryenergy

E 2 E 1

missingenergy

E

knee

N

E 0

What do we need to explain all unusual data?What do we need to explain all unusual data?

Model of hadron interactions which gives:

1. Threshold behaviour (unusual events appear at several PeV only).2. Large cross section (to change EAS spectrum

slope).3. Large yield of leptons (excess of VHE muons,

missing energy and penetrating cascades).

4. Large orbital (or rotational) momentum (alignment).5. More quick development of EAS (for increasing the

N / Ne ratio and decreasing Xmax elongation rate).

Possible variantsPossible variants

• Inclusion of new super-strong interaction.

• Appearance of new massive particles (supersymmetric, Higgs-bosons, relatively long-lived resonances, etc.)

• Production of blobs of quark-gluon plasma (QGP) (better to speak about quark-gluon matter (QGM), since usual plasma is a gas but quark-gluon is a liquid).

We considered the last model since it allows demonstrably explain the inclusion of new interaction.

Quark-gluon matterQuark-gluon matter

1. Production of QGM provides main conditions:

- threshold behavior, since for that large temperature

(energy) is required;

- large cross section, since the transition from

quark-quark interaction to some collective

interaction of many quarks occurs:

2 221 2R or R R

2. But for explanation of other observed phenomena a

large value of orbital angular momentum is required.

where R, R1 and R2 are sizes of quark-gluon blobs

Orbital angular momentum Orbital angular momentum in non-central ion-ion collisionsin non-central ion-ion collisions

Zuo-Tang Liang and Xin-Nian Wang, PRL 94, 102301 (2005); 96, 039901 (2006)

CentrifugalCentrifugal barrierbarrier

L s

2 2( ) 2V L L mr

1. As was shown by Zuo-Tang Liang and Xin-Nian Vang,

in non-central collisions a globally polarized QGP with large orbital angular momentum which increases with energy appears.

2. In this case, such state of quark-gluon matter can be

considered as a usual resonance with a large centrifugal barrier.

3. Centrifugal barrier will be large for light quarks but less for top-quarks or other heavy particles.

Centrifugal barrier for different massesCentrifugal barrier for different masses

How EAS development is changed How EAS development is changed in frame of a new model?in frame of a new model?

1. Simultaneous interactions of many quarks change the energy in the center of mass system drastically:

2. Produced -quarks take away energy GeV, and taking into account fly-out energy, t > 4mt 700 GeV (in the center of mass system).

tt 2t tm 350

3. Decays of top-quarks WW –bosons decay into leptons (~30%) and hadrons (~70%);

b b c c s s u u with production of muons and neutrinos.

1 12 2p cS m E m E

where mc nmN. At threshold energy, n ~ 4 ( - particle)

t t W W b b

How the energy spectrum is changed?How the energy spectrum is changed?

1. One part of t-quark energy gives the missing energy (e, , , ), and another part changes EAS development, especially its beginning, parameters of which are not measured.

2. As a result, measured EAS energy E2 will not be equal to primary particle energy E1 and the measured spectrum will be differed from the primary spectrum.

3. Transition of particles from energy E1 to energy E2 gives a bump in the energy spectrum near E2.

1015 1016 101710-25

10-24

10-23

10-22

10-21

10-20

10-19

10-18

dN

/dE

, ar

b. u

nits

E, eV1015 1016 1017

10-25

10-24

10-23

10-22

10-21

10-20

10-19

10-18

dN

/dE

, ar

b. u

nits

E, eV1015 1016 1017

10-25

10-24

10-23

10-22

10-21

10-20

10-19

10-18

dN

/dE

, ar

b. u

nits

E, eV

Change of primary energy spectrumChange of primary energy spectrum

How measured composition is changed How measured composition is changed in frame of the new approachin frame of the new approach

Since for QGM production not only high temperature (energy) but also high density is required, threshold energy for production of new state of matter for heavy nuclei will be less than for light nuclei and protons.

Therefore the heavy nuclei (f.e., iron) spectrum is changed earlier than light nuclei and proton spectra!!!

To compare the changes of spectra of different nuclei, very simple model was used.

Relation between primary energy Relation between primary energy EE11 and and

measured energy measured energy EE22

2

1 11

2

2 ln 1.7

2

c tth th

c

E Em E

E EE

m

2 3

6 5610 , GeVth c

i

nE m

A n

n = 4

t = 700 GeV

Primary spectra of various nucleiPrimary spectra of various nuclei

Measured spectra for some nuclei and Measured spectra for some nuclei and spectrum of all particlesspectrum of all particles

1015 1016 1017 1018 1019102

103

104

105

E

2.7

dN

/dE

, G

eV1

.7 m

-2 s

-1 s

r-1

E, eV

All elements H He CNO NeMgSi Fe

Influence of energy stragglingInfluence of energy straggling

1015 1016 1017

2x104

4x104

6x104

8x104

105

E

2.7

dN

/dE

, G

eV1

.7 m

-2 s

-1 s

r-1

E, eV

measurement errors 0% 10% 20%

Comparison with experimental data Comparison with experimental data (without straggling)

Comparison with experimental data Comparison with experimental data (with 10% straggling)

Discussion of resultsDiscussion of results

1. Energy spectrum obtained in frame of the simplest model surprisingly well describes experimental data.

2. Changes of composition are explained:

– a sharp increase of average mass at the expense of detection of EAS from heavy nuclei,

– after that slow transition to proton composition.

3. Results of composition changes obtained by means of N measurements are explained, too. Number of muons is increased as result of not muon production in nuclei interaction but through decays of massive particles.

EAS simulations EAS simulations in frame of the new approachin frame of the new approach

CORSIKA (version 6.960) was used.

To introduce -quarks, PYTHIA (version 6.4.22) was used. tt

Unfortunately, PYTHIA describes pp-interactions only, but in spite of this the obtained results are impressive.

The following results were obtained: - changes of various particle spectra in EAS after introduction of t-quark; - changes of inclusive muon energy spectrum; - comparison of cascades from nuclei without t-quarks and cascades from protons with t-quarks.

Various particle spectra without Various particle spectra without tt-quarks-quarks

Various particle spectra with Various particle spectra with tt-quarks-quarks

Inclusive muon energy spectrumInclusive muon energy spectrum

0 1 2 3 4 510-3

10-2

10-1

100

101

102

103

p, CORSIKA pp, PYTHIA+CORSIKA pp->tt, PYTHIA+CORSIKA

dN

/dl

gE

lg(E, GeV)

E = 1015 eV, H1int = 23.5 km

Cascade curves for various nuclei Cascade curves for various nuclei (without (without tt-quarks)-quarks)

Cascade curves for protons Cascade curves for protons (with (with tt-quarks)-quarks)

The ankle problemThe ankle problem

Explanation of the ankle appearanceExplanation of the ankle appearance

On the face of it, the considered approach does not explain the behavior of the energy spectrum above the ankle, but this is not so.

With increasing of primary particle energy the excitation level can exceed the centrifugal barrier, and the blob of QGM will decay into light quarks.

The knee The ankle

Illustration of the ankle appearanceIllustration of the ankle appearance

1017 eV 1018 eV

In this case, there will be no missing energy and the measured spectrum begins to return to the initial form ( = 2.7).

How to check the new approach?How to check the new approach?

There are several possibilities to check new approach as in LHC experiments so in cosmic ray investigations.

Of course, the most convincing results in LHC experiments can be obtained, since QGM with described characteristics (excess of t-quarks, excess of VHE muons, sharp increasing of missing energy, etc.) doubtless will be observed.

However these results unlikely can be obtained in pp-interactions even at full energy 14 TeV, which correspond 1017 eV in cosmic ray experiments (for pp-interaction), since for that collisions of sufficiently heavy nuclei are required.

How to check the new approach in How to check the new approach in cosmic ray experiments?cosmic ray experiments?

One possibility is direct measurements of various nuclei spectra in space. Changes in spectra must begin from heavy nuclei.

Two other possibilities are connected with VHE muon detection: - measurements of muon energy spectrum above 100 TeV; - measurements of energy deposit of EAS muon component below and above the knee.

For that, existing muon and neutrino detectors can be used: BUST, NEVOD-DECOR, Baikal, ANTARES, IceCube etc.

Prediction for CR nuclei spectra measurementsPrediction for CR nuclei spectra measurements

Results of VHE muon measurementsResults of VHE muon measurements

Preliminary results of muon energy spectrum investigations in Baksan Underground Scintillation Telescope (BUST)

http://arxiv.org/pdf/0911.1692

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

E1

Existing approach to EAS analysis

New approach to EAS analysis

ConclusionConclusion

Considered approach allows solve practically all problems of comic ray investigations above the knee.

If this approach is correct, it will be an excellent present to 100 year anniversary of cosmic ray discovery!

And it will provide a good job for next generations of cosmic ray physicists during the second century of cosmic ray investigations!

Thank you!Thank you!

The model of cosmic ray generation The model of cosmic ray generation in plasma pinchesin plasma pinches

B.A.Trubnikov, V.P.Vlasov, S.K.ZhdanovKurchatov Institute, Moscow

(Preprint № 4828/6 IAE, M., 1989; JETP Lett., 1989, v.49, p.581.)

In cosmic plasma (of any origin) electrical discharges – "cosmic lightnings" can occur, at which cylindrical pinches are formed. Two basic instabilities of plasma pinches are known: snaky and neck.

In the last case plasma jets are squeezed out of pinch neck.

These jets are the accelerated particle beams.

B

Snaky Neck

It is shown that energy distribution of particles in jets has the following form:

which does not depend on pinch sizes, currents in pinches and other parameters.

These parameters determine a proportionality coefficient only.

Accelerated particle energy has no limitation since density in plasma pinch when its radius 0.

Therefore the contribution of various sources of cosmic plasma (stars, Supernova, Galaxy, black holes, etc.) can be summed and general spectrum in whole Universe is formed.

Model explains the absence of point sources of cosmic rays since plasma pinches , f.e. near Supernovae, can be oriented in any direction.

Energy spectrum of accelerated particlesEnergy spectrum of accelerated particles

1 3,dN dE E