1. Atmospheric Shower Studies from last data taking Conferenza Nazionale del Progetto EEE Extreme Energy Events La Scienza nelle Scuole 15-16 Dicembre 2014 Corrado Cicalo - Istituto Nazionale di Fisica Nucleare Sezione di Cagliari

2. The EEE Analysis Working Group Marcello Abbrescia, Luca Baldini, Giovanni Batignani, Stefano Boi, Fabrizio Coccetti, Richard Forster, Daniele De Gruttola, Marco Garbini, Ivan Gnesi, Paola La Rocca, Silvia Miozzi, Francesco Noferini, Francesco Nozzoli, Maria Paola Panetta, Laura Perasso, Davide Piccolo, Francesco Riggi, Adrian Rodriguez Rodriguez, Luisa Stori, Crispin Williams and C.C. Corrado Cicalo – INFN Cagliari2

3. Summary Atmospheric Showers Observation Muon Decay observation Study of upgoing Muons Corrado Cicalo – INFN Cagliari3

4. Atmospheric Shower 1Tev Proton 20km above sea level 20km x 5km x 5km box electrons and positrons green, muons red gamma rays cyan primary proton Corrado Cicalo – INFN Cagliari4

5. Atmospheric Shower Observation: how EEE telescopes: synchronized tracking devices. Reconstruct shower direction Time synchronization. Each telescope is equipped with a GPS receiver -> absolute time stamp assigned to each event Corrado Cicalo – INFN Cagliari5

6. Atmospheric Shower Observation: the method Collect a lot of good quality data with two (or more) nearby telescopes Reconstruct the events -> good tracks Select events in the two (or more) telescopes with little time stamp difference Corrado Cicalo – INFN Cagliari6

7. Atmospheric Shower Observation: where In the EEE network many sites have at least two nearby telescopes For example: L’AQUILA ≈200m CAGLIARI ≈500m FRASCATI ≈ 600m SAVONA ≈ 1100 BOLOGNA ≈ 1500m CATANIA≈ 3000m …….. Corrado Cicalo – INFN Cagliari7

8. CAGL-01 & CAGL-02: geometrical parameters Liceo Scientifico Pacinotti CAGL-01 Liceo Scientifico Michelangelo CAGL-02 N D = 520 m 73° Corrado Cicalo – INFN Cagliari8

9. Previous results: 2011 2011 CAGLIARI d=520m L’AQUILA d=180m Signal: 43 coincidences/day. Background: 60 events/day d=520m Signal:170 coincidences/day. Background: 85 events/day Corrado Cicalo – INFN Cagliari9

10. Pilot RUN High quality and good statistics of data simultaneously collected -> OCT-NOV 2014 Corrado Cicalo – INFN Cagliari10

11. Event Time difference Data sample: 23 days (from OCT 27 to NOV 18) NO CUTS Corrado Cicalo – INFN Cagliari11 Signal ≈23 events/day

12. Data quality Selection    all data sample First: are the tracks well reconstructed? Choose only “good tracks”   . Corrado Cicalo – INFN Cagliari12

13.  2 cuts Corrado Cicalo – INFN Cagliari13

14. Second: cut on muon relative angle rel CUT on TETAREL 01 02 rel Corrado Cicalo – INFN Cagliari14 Not to scale rel 10km -> rel =2.8° to scale 500m

15. Effect on data of this Parallelism cut Corrado Cicalo – INFN Cagliari15 Cut on rel < 15  Cut efficiency (signal)  60-65% Background suppression  factor 4

16. Time difference with quality cuts Corrado Cicalo – INFN Cagliari16

17.  L* 1 2 y (East) x (North) Correction on  angle  school -   L* = cos(  school -  )  L school  L school 12  L* Correction on angle z ctct  t =  L* sin / c  t = cos(  school -  )  L school sin / c Time delay in the coincidences and muon directions Corrado Cicalo – INFN Cagliari17

18. Effect of correction on muon relative direction Corrado Cicalo – INFN Cagliari18 with correction 250±31 without correction 382±73

19. Coincidences search in Savona -0.33 rad 1140 m x y Corrado Cicalo – INFN Cagliari 19

20. SAVO-01 vs SAVO-02 (40 days) Still low statistics but -> we are not so far to get a clear signal. Need to take 2 or 3 times more data From the fit ≈ 3.8  1.1 (90[coinc.]/40[days]/0.6[cut eff]) coincidences per day. Looks reasonable if compared with MC prediction [Eur. Phys. J. Plus (2014) 129, 166 (4-5 coinc. at 1 Km)]. Cut on rel < 15  Corrado Cicalo – INFN Cagliari20 A smearing of about 1  s (450 ns / 500 m * 1140 m) is expected to be re-assorbed thanks to the correction.

21. CAGL SAVO 5 coincidences in the acceptance at 1 Km Number of expected coincidences Montecarlo Simulation : estimate the number of coincidences /day as a function of the distance between telescopes Corrado Cicalo – INFN Cagliari21

22. Coincidences search between three telescopes. d=2360m d=2510m SitesRelative distance A. Pacinotti - Michelangelo518 m A. Pacinotti - L. B. Alberti2360 m Michelangelo - L. B. Alberti2510 m Corrado Cicalo – INFN Cagliari22 Work in progress To do list: Increase statistic Need better data quality on CAGL-03 New GPS foreseen next week Optimize analyzer CODE CAGL-03

23. Situation in BOLOGNA Corrado Cicalo – INFN Cagliari23 BOLO-01 BOLO-02 BOLO-03 BOLO-04 1500 m

24. Study on muon decay The EEE telescope can measure: the Time of Flight of the incoming muons from plane 3 to plane 1 (d≈150cm) the track length Corrado Cicalo – INFN Cagliari24

25. Average Muon Velocity Corrado Cicalo – INFN Cagliari25 |Time Of Flight| (ns) TrackLength (cm) 0.95 x speed of Light

26. Can we see Upgoing Particles? Corrado Cicalo – INFN Cagliari26 Few upgoing particles ~ 1/2000 downgoing upgoing TrackLength (cm) Time Of Flight (ns)

27. Time Delay distribution Corrado Cicalo – INFN Cagliari27 DTp = time delay from previous event DTp (s) Log10(DTp) (s) exponential Tau = 0.02s 0.02 s Note: if x has exponential distribution: exp(-x/Tau) Log(x) has the maximum @ lifetime = Tau position

28. Study of Muon Decay EEE detector Downgoing low energy muon Capture +decay Upgoing low energy electron Good Signature: delay ~ 2 μ s + large   (due to multiple scattering...) neutrino(s) ~ 50 MeV electron: range in Al ~ 7cm ACQUISITION deadtime = 0.15 μ s They are 2 separate events.  e

29. Identity of good Muon decay event 1) Upgoing electron delay of ~ 2μs with respect to parent Muon 2) Beta of parent Muon should be small (low energy Muon) 3) ChiSquare of upgoing electron should be much larger respect to downgoing muons (because of multiple scattering) 4) ChiSquare of parent muon should be slightly larger respect to high energy muons (because of multiple scattering) Corrado Cicalo – INFN Cagliari29

30. Time delay from previous event Corrado Cicalo – INFN Cagliari30 Upgoing electron delay of ~ 2μs wrt parent Muon DTp = time delay from previous event Muon decay Delayed ~2μs Log10(DTp) (s) Beta = v/c Downgoing Upgoing

31. DTn = time delay from next event Upgoing Downgoing Log10(DTn) (s) Beta = v/c Beta of parent Muon is small (end range Muon) Time delay from next event

32. Parent Muon tagging Log 10 (1+  2 ) Beta = v/c Parent Muons: = 0.65 = 3 Downgoing muons Upgoing electrons Downgoing Muons: = 0.95 = 2 Upgoing electrons: = 1 = 5.5 (as exepcted E<100MeV electrons have large due to multiple scattering) Parent Muon is tagged as a downgoing precursor of an upgoing track with Δt<30 μs As expected = 0.65 muon kinetic energy = 35MeV They are at end range (3cm Al) is slightly increased due to multiple scattering Corrado Cicalo – INFN Cagliari32

33. Muon decay observation Corrado Cicalo – INFN Cagliari33 [B.Rossi 1952] Muon Lifetime in matter is smaller than 2.2 μs (free Mu) 2μs2μs -Downgoing exponential fit -Fit with Mu decay: 1.98 μs ± 1% ACQ cut Log10 (Time Difference[s]) EVENTS -Upgoing

34. Muon decay identified in 0.005% of all EEE events (that are only <6% of all upgoing tracks) BUT Most (>80%) of upgoing tracks are due to electrons from untagged muon decay. To do: a deeper investigation of the small population (<10%) with Muon-like chisquare in upgoing tracks (maybe just Positive Beta muon tail spillover to negative Beta) (need larger exposure and additional hit-track infos) Corrado Cicalo – INFN Cagliari34

35. Conclusion and outlook Corrado Cicalo – INFN Cagliari35

36. Time difference without cuts Data sample: from OCT 27 to NOV 18 Corrado Cicalo – INFN Cagliari36

37. Expected Coincidences per Day Montecarlo Simulation Corrado Cicalo – INFN Cagliari37

38. Corrado Cicalo – INFN Cagliari38

39. Corrado Cicalo – INFN Cagliari39

40. Bethe-Bloch for muons β = 0.65 βγ = 0.85 P = 90 MeV => Kin. Energy: 35 MeV => range in Al: 3cm Density: Al: 2.7g/cm3 Concrete: 2.5-3 g/cm3

41. Muon lifetime in matter Corrado Cicalo – INFN Cagliari41 Rossi, B., High-EnergyParticles, (1952, Prentice-Hall, Inc., New York). Muon Lifetime in Al Muon Lifetime measured in matter is smaller with respect to 2.2μs of free Muons due to nuclear capture process μ−+N( A,Z)→N ∗ (A,Z−1)+ν (mainly affecting negative Muons) Carbon: 1.9μs Iron:0.14μs

42. Corrado Cicalo – INFN Cagliari42

43. Corrado Cicalo – INFN Cagliari43

44. Muon Energy Spectrum Corrado Cicalo – INFN Cagliari44 K. Nakamura et al. (PDG), JP G 37, 075021 (2010) and 2011 partial update for the 2012 edition (pdg.lbl.gov)