1. Cosmic ray physics at YBJ
Introduction
CR acceleration, knee
γ ray astronomy
Results from ASγ and prospect from ARGO
Knee, γ ray ,solar CR
Summary

2. CR spectrum Abundence: ~solar system and ISM Lifetime~107year
Power law?
Great energy span？
Knee？
Ankle？
No GZK cut off？
Type of particle above Knee?
Clustering of super GZK events?
LHC Ecm
LHC Elab
Steep spectrum:
Ground based
observation
necessary
GZK
cutoff
Discovered by Dr.Dai:
50M time higher than LHC

3. CR Acceleration Emax~ZBL Power to refill galactic CR: 10 41 erg/s.
Fermi acceleration: CR scatter off magnetic cloud.
Modern theory: diffusive shock acceleration at SNR up to 1016eV.
Hillas plot

4. Examples Solar flares:100GeV SNRs: 1016eV AGN: 1020eV GRB
Topdown:super massive particle decay…

5. Fermi and Shock acceleration
Fermi(1949): N(t)~exp(-t/τ), E~αn~βt, N(E)~E-γ;
Diffusive shock acceleration:
Shock wave by explosion of “high energy object”
Charged particle being accelerated crossing through back and forth the shock front;
(Voelk)

6. Diffusive shock acceleration at SNR
Explain the primary spectra.
γ ray emission from electron synchrotron and IC;
Predict the γ ray emission due to the decay of π0 which is produced by CR interacts with ambient matter.
(Berezhko)

7. Diffusive γ ray emission on galactic plan observed by EGRET

8. Origin,acceleration and propagation ~γ ray astronomyν
γ+ γir->X
BUT :
γ ray astronomy:
does much more!

9. Electromagnetic spectrum (Crab)
Electron synchrotron IC
(Voelk)

10. GeV & TeV sources NGC253: ~2.5Mpc， closest Starburst Galaxy.
First unidentified source:
TeV ；
3% Icrab, stable,index
α~-2；
Not seen by EGRET,or
other band emission;
Extended by 6 arc-min.
GeV & TeV sources
NGC253: ~2.5Mpc，
closest Starburst Galaxy.
3C66A: unconfirmed.
Z~0.444的LBL.
5.1σ由Crimean观测到.

11. (Extreme) High Energy Cosmic RayUV
Radio

12. Advantages of YBJ γ ray astronomy
Number of secondary reach maximum, favor knee physics, including composition and spectrum measurement.
Low energy threshold, favor γ ray astronomy
Better angular,energy resolution
knee
γ ray astronomy
(Ong)

13. Performance ASγ ARGO: new energy window, higher statistic etc
Eth: ~1TeV;
Angular resolution: ~ 1o;
Trigger rate: ~1KHz
ARGO: new energy window, higher statistic etc
Eth:~100GeV;
Angular resolution: ~1o;
Trigger rate:~30KHz.
~Icrab
~0.3Icrab

14. γ ray astronomy at YBJ AS γ poor γ/p separation large field of view
high duty cycle
ARGO

15. Asγ results on Knee physics
Chinese scientist made important contribution;
Aslo in RD for upgrading.
ICRC2001
ICRC2003

16. Gamma ray emission from Crab (4.8σ)

17. Extragalactic source AGN
astronomy
cosmology

18. Mrk501
Active states:
Feb.1997-Aug.1997.

19. Mrk421 (6.9σ)
ASγ saw Mrk421 flaring between earlier than IACT;
Demonstrate the advantages of large field of view and high duty cycle.

20. All sky survey from ASγ Sky map Seven interesting directions
Mrk421
Dec
Sky map
Crab Ra
Seven interesting directions
Significance > 3.5 
Nearby detected sources

21. ASγ Results on diffusive TeV γ ray emission in galactic plan

22. TeV GRB Event excess seen from MILAGRITO within error box
of BATSE GRB970417a.
BKG fluctuation probability:
2.8×10-5
AS γ candidate in
a general search
mode.

23. Moon shadow Natural spectrometer p Positive particle seen westward
Negative particle seen eastward

24. Solar CR:
1) sun shadow
2）high energy solar CR emission in coincident with solar flare,GLE

25. CR’s sidereal time modulation

26. CR’s solar modulation: Compton Getting effect
(2+ γ）βcosθ
(γ=2.75)
太阳时

27. Solar neutron in coincidence with solar flare in 2001.9.24, at 9:32UT

28. ARGO physics (~AS γ) γ ray astronomy
Point source
Diffused γ ray
GRB
Primary cosmic ray spectrum up to O(100) TeV and more;
anti proton spectrum;
Sun and heliosphere physics;

29. ARGO γ/p separation EAS: usually difficult in identifying γ from p;
Different shower pattern with NN technique;
Improve sensitivity by a factor ~1.5;

30. ARGO GRB (1GeV-1TeV) sensitivity
Single particle technique
Spatial,temporal constrained
Assume Aeff~103m2,dnγ(E)/dE~E-2 ;
dNGRB(L)~L-β, n( z,L) ~(1+z)3/(1+z).

31. Conclusion
Exciting physics topics : related with astronomy,particle,nuclear,solar physics, as well as solar terrestrial space, meteorology etc;
Fruitful outputs, still keep improving and very promising;
Expecting cooperation with colleagues in other fields, both experimental and theoretical.