1. Yu. Stenkin, UHECR'20081 On PRISMA project (proposal) Yuri V. Stenkin INR RAS

2. Yu. Stenkin, UHECR'20082 The Project aims Why PRISMA? PRImary Spectrum Measurement Array The main aim is: TO SOLVE THE “KNEE PROBLEM” Other aims: –cosmic rays spectra and mass composition –cosmic ray sources –applied Geophysical measurements

3. Yu. Stenkin, UHECR'20083 History & Motivation Why we need a new project? 1. The “knee problem” is a milestone of cosmic ray physics. 2. Very few experiments have been designed specially for that and KASCADE (KArlsruhe Shower Core and Array DEtector) is the best one. 3. The problem still exists.

4. Yu. Stenkin, UHECR'20084 EAS method

5. Yu. Stenkin, UHECR'20085 1. The “knee problem” The problem is exactly 50-years old! In 1958 there was published a paper (G.V. Kulikov & G.B. Khristiansen) claiming the knee existence in cosmic ray energy spectrum. They observed a sharp change of slope in EAS size spectrum and proposed a model describing this effect as an evidence of existence of 2 sources of c. r.: Galactic and Metagalactic ones. But, from the beginning and up to now there exist alternative explanations of this effect (S.I.Nikolsky, Kazanas & Nikolaidis, A.A.Petrukhin, Yu.V. Stenkin).

6. Yu. Stenkin, UHECR'20086 Examples of alternative explanations E Petrukhin Stenkin New processes knee Primary energy EAS energy Missing energy Primary energy Primary energy knee EAS method systematic

7. Yu. Stenkin, UHECR'20087 Depth in atmosphere No of particles From Hayakawa manual on cosmic ray physics EAS components equilibrium Break of equilibrium Break in attenuation “knee” in N e spectrum

8. Yu. Stenkin, UHECR'20088 When the break occurs? At E~100 TeV / nucleon For p: 100 TeV For Fe: 5 PeV (just the knee region) For details see: Yu.Stenkin, Yadernaya Phys., 71 (2008), 99 This figures are sequences of : L int = 90 g/cm 2 in air the Earth’s atmosphere thickness =1030 g/ cm 2 (depending on altitude)

9. Yu. Stenkin, UHECR'20089 2. Existing experiments KASCADE It gave many interesting results. BUT, it did not answer the question on the knee origin and thus, It has not solved the knee problem! Moreover, the problem became even less clear…. (see G. Schatz. Proc. 28th ICRC, Tsukuba, (2003), 97 or Yu. Stenkin. Proc. 29th ICRC, Pune (2005), v.6, 621)

10. Yu. Stenkin, UHECR'200810 KASCADE -> KASCADE-Grande

11. Yu. Stenkin, UHECR'200811 KASCADE hadronic calorimeter

12. Yu. Stenkin, UHECR'200812 KASCADE group connected visible knee in PeV region with c. r. protons. - Nobody saw this. C. R. should consist only of heavy nuclei at   eV or one has to adjust many parameters to make full compensation. - Nobody saw this. It contradicts emulsion chamber experiments (Pamir) and air luminescence data (Hi Res). Tibet AS experiment results contradict this hypothesis: they connect the knee with iron primary. In this case there should be the iron knee at E~10 17 eV.

13. Yu. Stenkin, UHECR'200813 Compilation of experimental data (astro-ph/0507018)

14. Yu. Stenkin, UHECR'200814 KASCADE EAS h-size spectra “knee”???

15. Yu. Stenkin, UHECR'200815 A. Haungs, J. Kempa et al. (KASCADE) Report FZKA6105 (1998 ); Nucl. Phys. B (Proc. Suppl.) 75A (1999), 248

16. Yu. Stenkin, UHECR'200816 to make a device based on new principles (asymmetrical answer) KASCADE is very precise classical instrument for EAS study. It would be difficult and useless to try to make better array. On my opinion the only way is:

17. Yu. Stenkin, UHECR'200817 PRISMA would be the answer. PRISMA Prism

18. Yu. Stenkin, UHECR'200818 New principles The main EAS component is: hadrons Therefore, let us concentrate mostly on the hadronic component Bun, instead of huge and expensive hadron calorimeter of fixed area, let us make simple, inexpensive and of unlimited area detector. How this could be done?

19. Yu. Stenkin, UHECR'200819 New Methods 2 new methods have been developed in our Lab. 1st method is based on thermal neutrons “vapour” accompanying EAS

20. Yu. Stenkin, UHECR'200820

21. Yu. Stenkin, UHECR'200821 en-detector design PMT housing 6 Li(n,a) 3 H+4.8 MeV 160,000 photons per capture ZnS(Ag) is a unique scin- tillator for heavy particles detection: plastic Scintillator: ZnS(Ag)+ 6 LiF Similar to that using in neutron imaging technique

22. Yu. Stenkin, UHECR'200822 The detector is almost insensitive to single charged particles. But, it can measure the number N of charged particles if N>5.

23. Yu. Stenkin, UHECR'200823 Thermal neutron time distributions Multicom Prototype, BaksanPrisma prototype, Moscow

24. Yu. Stenkin, UHECR'200824 Another advantage of this detector is a possibility to measure thermal neutron flux of low intensity and its variations

25. Yu. Stenkin, UHECR'200825 2d new method: The Muon Detector as a 1-layer hadronic calorimeter:

26. Yu. Stenkin, UHECR'200826  core  m2m2  jet  m 2 This picture represents a density map as measured by Carpet (left, shown in LOG scale) and by MD (right, linear scale in relativistic particles). (Detector in the center show a particle density of ρc=8*1.1252/0.5=5800 m -2. jet of (26+17)/2=21.5 particles per m 2 in MD. Jet size is very narrow (~1 m) with normal rather low density around it and second: the distance from the EAS core is large enough and equal to 48 m.

27. Yu. Stenkin, UHECR'200827 Preliminary Baksan data: hadrons at R=47m

28. Yu. Stenkin, UHECR'200828 Preliminary data Muon/hadron ratio distribution

29. Yu. Stenkin, UHECR'200829 Carpet: 400*1m 2 en-detectors grid with spacing of 5 m Central muon detector: 400*1m 2 plastic scinillators Muon detector tunnels: 1200*1m 2 plastic scintillators Outer trigger detectors: 4*25*1m 2 plastic scintillators

30. Yu. Stenkin, UHECR'200830 M-C simulations. CORSIKA 6.501 (HDPM, Gheisha6)

31. Yu. Stenkin, UHECR'200831 Ne= 407158 Nmu= 794 E0/1TeV= 355.0245 x0= -4.448307 y0= -27.31079 TETA= 13.80 FI= 161.49 Z= 3094504. Part_type= 5626 M-C simulations. CORSIKA 6.501 (HDPM, Gheisha6)+array A map of an event in neutrons

32. Yu. Stenkin, UHECR'200832 M-C

33. Yu. Stenkin, UHECR'200833 Main features: Range in primary energy: from ~10 TeV to ~30 PeV energy resolution: ~ 10% angular resolution: ~ 1 o core location:< 2.5 m capability to measure independently: N e, N h, N 

34. Yu. Stenkin, UHECR'200834 Location Collaboration Institutions budget altitude (high altitude is preferable) It depends on:

35. Yu. Stenkin, UHECR'200835 Involved Institutions: 1. Institute for Nuclear Research, Moscow 2. MEPhI, Moscow 3. Skobeltsyn Institute, MSU, Moscow 4. 5. To be continued... The collaboration is open for other participants. You are welcome!

36. Yu. Stenkin, UHECR'200836 Thank you!