History

Compilation of the primary CR energy spectra J. R Compilation of the primary CR energy spectra J.R.Hoerandel, astro-ph/0407554

Single Source Model of the Knee

Single Source Model (SSM) Basic ground of SSM is the non-uniform distribution of CR sources (SN and SNR) in space and time. The probability of the relatively recent (<105y) SN explosion in the vicinity of the Sun (<300pc) is rather high (~1)

S does not depend on absolute values of I and g

Sharpness of the knee at different atmospheric depths Galactic Modulation GALACTIC MODULATION

Due to the stochastic nature of CR sources there must be ‘structure’ in the CR energy spectrum at some level … Wolfendale A.W.

Fine Structure of the Knee Fe in the ‘Single Source Model’ In ‘Single Source Model’ in Cherenkov light spectra in EAS size spectra knee

Single Source Model ( basic idea )

me, Baksan me, SYB zm me, QGS mh mhe

General Conclusion Sharpness of the knee and fine structure of the CR energy spectrum manifest the substantial role of the non-uniform distribution of CR sources in space and time. They point out at the dominant contribution of the nearby and young SNR in the knee region. As a candidate for this ‘single source’«одиночного can be SNR Monogem Ring with the pulsar B0656+14.

LHC and the Origin of the Knee

ALICE shows what is above the knee

ALICE shows what is above the knee

Conclusion The knee is not due to the change of the interaction characteristics of cosmic ray particles with air nuclei

Possible Single Source

Vicinity of the Sun (nearby 300 pc)

Vela SNR June 12, 1996                                                            pulsar B0833-45 & Vela X PWN Vela Jr

Do we see an ‘Iron Peak’ ?

GAMMA-2008: event-by-event analysis

TUNKA - 133

IceTop

of the contribution from the Single Source We think that the steepening of the spectrum at 1017eV indicates the end of the contribution from the Single Source

Anisotropy

EAS intensity excess at PeV energies G. Benko et al EAS intensity excess at PeV energies G.Benko et al., astro-ph/0502065, Изв.РАН, сер.физ.,2004, 68, 1599; Monogem Ring

Conclusions on the anisotropy At logE,GeV < 5 the data on the anisotropy are consistent and surprisingly indicate the excess from the Outer Galaxy ( 3rd quadrant ). Possible explanation is the random configuration of nearby sources. At logE,GeV > 5 both the amplitude and the phase change their energy dependence. Excesses move towards the Inner Galaxy ( 4th quadrant )

Puzzles of the PeV region around the Knee

‘Neutron thunder’

Neutron monitor counting rate, II I, ms-1 1000 2000 3000 Delay t, ms

PeV energy region Findings ( Antonova V.A. et al., 2002, J.Phys.G, 28, 251 ): 1. There are a lot of neutrons delayed by hundreds of ms after the main shower front (‘the neutron thunder’). Their temporal distribution is different from the standard one in neutron monitors. 2. Distortions of the temporal distributions seem to have a threshold and begin in the PeV (‘knee’) region. 3. Multiplicity of such neutrons is very high compared with EAS model expectations. 4. These neutrons are concentrated in the EAS core region. 5. Delayed neutrons are accompanied by delayed gamma- quanta and electrons.

Conclusions for PeV energies 1. The bulk of observed neutrons are not born in the shower. They are produced inside the neutron monitor. 2. Their temporal distribution is the standard monitor distribution, distorted by the saturation of the counting rate at high neutron fluxes. 3. The distortions start at the threshold when the counting rate reaches the saturation level. 4. The very high multiplicity of produced neutrons and their concentration near the EAS core are due to the narrow lateral distribution of EAS hadrons and their energy around the core. 5. Delayed gamma-quanta and electrons have also a secondary origin – they are produced by delayed neutrons in the detector environment.

Temporal distribution of eg, m and n at different EAS core distances After 5ms at the core distance of 1km neutrons are the dominant component of the shower R<10m R=100m R=1000m Time, ms or ms

General remarks The discovery of ‘the neutron thunder’ by Chubenko A.P. with his colleagues is an outstanding achievement . If our interpretation of it is correct, this phenomenon extends our understanding of the EAS development and its interaction with detectors and their environment. The study of EAS neutrons is complementary to the study of other EAS components by Geiger counters, scintillators, ionization calorimeters, gamma-telescopes, X-ray films etc. and all together they could give the full picture of atmospheric shower.

The phenomenon of ‘the neutron thunder’ emphasizes the role of detectors and their environment in the observed signals. The surrounding materials containing water could increase the neutron scattering, moderation, and production of secondary gamma-quanta and electrons. In this aspect, mountain studies can be particularly vulnerable. Mind that the EAS core at mountains as the neutron generator carries much bigger energy than at sea level. As for the environment, a good part of the year mountain stations ( viz. Tien-Shan, Aragats, Antarctic etc.) are covered by snow sometimes of meters thick. As for the Tien-Shan station, there might be an additional factor emphasizing the role of neutrons – its ground is a permafrost containing a good fraction of ice. There might be effects at shallow depths underground connected with the propagation of neutrons produced when the EAS core strikes the ground.

EAS-TOP in winter

Aragats in the spring

Aragats, May 2006

IceTop

3. The water cherenkov detectors are particularly worth of attention. First of all water as hydrogen containing stuff is a moderator like a polyethilene of the neutron monitor. Secondly it might be sensitive to secondary electrons and gamma-quanta, produced by neutrons interacting with water ( mind the discovery of cherenkov radiation itself ). Since water and ice cherenkov detectors are wide spread all over the world ( MILAGRO, NEVOD, ICE-TOP ) and in particular used in Pierre Auger Observatory, the contribution of neutrons at large core distances and ms delays might be noticable and needs a special study. 4. The same remark is relevant for large EAS, based on hydrogen containing plastic scintillators ( Yakutsk, Telescope Array ).

Delayed particles in the EAS front

Mean τ and σ of particles in the EAS front

in experiment and simulations Averaged ‹Τ› and Σ vs R in experiment and simulations

Fine structure of the EAS front (‘double showers’ ?)

Mean τ vs σ of particles in the EAS front experiment simulation

CONCLUSIONS There are more things in heaven and earth, Horatio, than are dreamt of in your philisophy… W.Shakespeare, Hamlet

“… The only malady I could conclude I had not was housemaid knee. I felt rather hurt about this at first; It seemed somehow to be a sort of slight. Why hadn’t I got housemaid knee ? Why this invidious reservation ?…” Jerome K. Jerome “Three men in a boat. To say nothing of the dog”