1. B.K.Lubsandorzhiev, MSU 16 May 20111 Nuclear Photonics Methods in EAS Cherenkov Arrays Bayarto Lubsandorzhiev Institute for Nuclear Research RAS Moscow Russia Kepler Centre for Astro and Particle Physics, University of Tuebingen, Tuebingen Germany

2. B.K.Lubsandorzhiev, MSU 16 May 20112 Photonics Photon sources Photon detectors Photon media: photon producing media; photon propogating media

3. B.K.Lubsandorzhiev, MSU 16 May 2011 3 1950-60s ELECTRONICS ----- NUCLEAR ELECTRONICS 1990-…… PHOTONICS ----- NUCLEAR PHOTONICS! (the term is coined by V.A.Matveev) Photon sources (light sources in calibration systems – lasers, LEDs, scintillators) Variety of DC or pulsed sources with : 0-10**16 photons per pulse with 1пс – 10 нс width covering very wide spectrum. Photon propagation and photon producing media (scintillators, light guides and optical fibres, photon radiators etc) abs, scatt Photon detectors: different types and sizes (1mm – 0,5 m) Electronics: preamps, amps, drivers, power supplies etc.

4. B.K.Lubsandorzhiev, MSU 16 May 20114 EAS Cherenkov Experiments are ideal case for nuclear photonics applications Photon detectors (PMTs, LS-HP) Photon emitters (Lasers, LEDs, LDs, ……..) Photon media (atmosphere, water, fibers, …….. )

5. B.K.Lubsandorzhiev, MSU 16 May 20115 Photon detectors PMTs LS-HP/HPDs Hamamatsu, ET MELZ-FEU!

6. B.K.Lubsandorzhiev, MSU 16 May 20116 MELZ-FEU PMT mass production Currently max dimension – 5 in. but any order of 2k-3k large (  8 in) PMTs is commercially attractive PMT and/or LS-HP(HPD)

7. B.K.Lubsandorzhiev, MSU 16 May 20117 Disadvantages of classical PMTs Poor collection and effective quantum efficiencies Poor time resolution? prepulses late pulses afterpulses sensitivity to terrestrial magnetic field larger PMT size - larger dynode system (Dph/Dd1), practically impossible to provide 2  acceptance

8. B.K.Lubsandorzhiev, MSU 16 May 20118

9. 9 Hybrid phototube with luminescent screen (LS-HP) A.E.Chudakov 1959 - hybrid tube with luminescent screen Van Aller, Flyckt et al. 1981 - prototypes of «smart tube» Van Aller, Flyckt et al. 1981-1986 - XP2600 L.Bezrukov, B.Lubsandorzhiev et al. 1985-1986 - Quasar-300 and Quasar-350 tubes L.Bezrukov, B.Lubsandorzhiev et al. 1987 - Tests of XP2600 and Quasar -300 tubes in Lake Baikal L.Bezrukov, B.Lubsandorzhiev et al. 1990 - Quasar-370 tube.

10. B.K.Lubsandorzhiev, MSU 16 May 201110 Hybrid phototube with luminescent screen Why luminescent screen? Luminescent screen - thin layer of scintillator (monocrystal or phosphor) covered by aluminum foil Light amplifier + small conventional type PMT

11. B.K.Lubsandorzhiev, MSU 16 May 201111 A number of scintillators are available only as phosphors (ZnO:Ga, LS, etc). Sometimes it’s better to work with phosphors. X-HPD is just part of the whole photodetector (Light preamplifier) LS-HP instead of X-HPD?

12. B.K.Lubsandorzhiev, MSU 16 May 201112 XP2600QUASAR-370 Transit time difference ~5ns. Transit tiem difference ~0.8ns!

13. B.K.Lubsandorzhiev, MSU 16 May 201113 QUASAR-370 single photoelectron response Photoelectron transit time spread (jitter) Multi pe charge spectrum

14. B.K.Lubsandorzhiev, MSU 16 May 201114 Quasar-370 like phototubes have excellent time and very good single electron resolutions no prepulses no late pulses in TTS low level of afterpulses ~100% effective collection effiency 1 ns TTS (FWHM) very good SER (competitive to HPD) immunity to terrestrial magnetic field >2  sensitivity Quasar-370G (B.Lubsandorzhiev, O.Putilov et al.) developed for TUNKA experiment has YSO+BaF 2 scintillator in the luminescent screen

15. B.K.Lubsandorzhiev, MSU 16 May 201115 QUASARs in Tunka Valley QUASARs in Campo Imperatore TUNKA-25 Cherenkov EAS detector QUEST detector in frame of EAS-TOP QUasars in Eas-Top QUASAR-370G

16. B.K.Lubsandorzhiev, MSU 16 May 201116 Successful operations of several astroparticle physics experiments (BAIKAL, TUNKA, SMECA, QUEST) prove the phototube’s high performances, high reliability and robustness. A number of modifications of the Quasar-370 tube have been developed with different scintillators in its luminescent screen YSO, YSO+BaF 2, YAP, SBO, LSO, LPO etc.

17. B.K.Lubsandorzhiev, MSU 16 May 201117 G = Y  k   (eff) Y - scintillator light yield k - colection efficiency of photons on small PMT’s cathode  (eff) - effective quantum efficiency of small PMT Small PMT with higher  (eff) will provide better parameters of Quasar-370! G - the first stage amplification factor

18. B.K.Lubsandorzhiev, MSU 16 May 201118 R7081HQE (10 in) XP5301 (3 in) SBA, QE=34% UBA, QE=46% (56%!) + WLS!!!

19. B.K.Lubsandorzhiev, MSU 16 May 201119 Jitter - ~3 ns Jitter vs  R7801HQE

20. B.K.Lubsandorzhiev, MSU 16 May 201120 Jitter vs  Quasar-370

21. B.K.Lubsandorzhiev, MSU 16 May 201121 Quasar-370 R7081

22. B.K.Lubsandorzhiev, MSU 16 May 2011 22 R3600-06 0,5 m cathode Jitter - ~4,7 ns 8-9 kHz noise (>0.1 pe) 3 counts/cm 2 (20  C)!!! <1 counts/cm 2 (0  C)!!! SER - poor

23. B.K.Lubsandorzhiev, MSU 16 May 201123 PMT to withstand high light background developed for TUNKA experiment 140 days exposure 8-10 years of exp. running Quasar-370G 100 nA cathode current Without change in sensitivity and scint light yield!

24. B.K.Lubsandorzhiev, MSU 16 May 201124 New parameter - effective photocathode occupancy E=Sph/Stotal !?

25. B.K.Lubsandorzhiev, MSU 16 May 201125 Quasar-370 XP2600

26. B.K.Lubsandorzhiev, MSU 16 May 201126 G.Hallewell CPPM Marseille

27. B.K.Lubsandorzhiev, MSU 16 May 201127 Conventional large are hemispherical PMTs are good for detectors with restricted angular aperture. New HQE large area conventional PMTs are promising for EAS Cherenkov arrays. (+WLS!!!) But still large area hybrid phototubes (LS-HP) are very close to “ideal photodetector” for EAS wide angle Cherenkov arrays.

28. B.K.Lubsandorzhiev, MSU 16 May 201128 Ideal photodetector for EAS wide angle Cherenkov arrays High sensitive hemispherical (up to 0.5 m in diam.) photocathode High angular acceptance High photoelectron detection efficiency (High effective CE) High time resolution Fast time response

29. B.K.Lubsandorzhiev, MSU 16 May 201129 The quest for the ideal scintillator for Quasar-370 like tubes Requirements:  Hight light yield  Fast emission kinetics  vacuum compatibility  compatibility with phocathode manufacturing procedure: high temperature, aggressive chemical environment etc.

30. B.K.Lubsandorzhiev, MSU 16 May 201130 Scintillators must be: Inorganic scintillators Nonhygroscopic

31. B.K.Lubsandorzhiev, MSU 16 May 201131 Time resolution of hybrid phototubes and scintillator parameters W(t) ~ exp(-(G/  )t) G - the first stage amplification factor G = n p.e. / N p.e. G ~ Y(E e ) Y - scintillator light yield  - scintillator decay time

32. B.K.Lubsandorzhiev, MSU 16 May 201132 Figure of merits - F F 1 = (Y/  )  a F 2 = (Y/  )  a  b Y - light yield,  - decay time, a - detectibility by small PMT or SiPM b - compatibility with photocathode manufacturing YSO YAP SBO LSO LS Bril350 Bril380 F 1 1 1.3 1.3 1.8 4* 4.6 6.4 F 2 1 1.3 1.3 1.8 4* 0? 0? * - using a photodetector with A3B5 photocathode

33. B.K.Lubsandorzhiev, MSU 16 May 201133 ZnO:Ga F1 = F2 = 250! Challenge:  the material should be extremelly pure  problems with monocrystal growth but phosphor will be O’K for luminescent screen

34. B.K.Lubsandorzhiev, MSU 16 May 201134  ~ 650 ps, light yield ~ 1500  /MeV

35. B.K.Lubsandorzhiev, MSU 16 May 2011 35 The first pilot sample of LS-HP with ZnO:Ga scintillator and GaN photocathode is currently under development!

36. B.K.Lubsandorzhiev, MSU 16 May 201136 Signal width is defined by readout pmt

37. B.K.Lubsandorzhiev, MSU 16 May 2011 37 Good opportunities for SiPM readout SiPM+scintillator unit – machine assemblage - cheapness

38. B.K.Lubsandorzhiev, MSU 16 May 201138 Hamamatsu J9758 phosphor,  ~1ns, Y ~3 Y(YAP) Hamamatsu news 2006, pp18-19

39. B.K.Lubsandorzhiev, MSU 16 May 201139 InGaN or GaN scintillators?! Expected to be very fast and very effective!

40. B.K.Lubsandorzhiev, MSU 16 May 201140 E.D.Bourret-Courchesne et al. NIMA W.Moses. NIMA (LBNL-50252) Light yield - 15000 photons/MeV Decay time - 0.4 ns!

41. B.K.Lubsandorzhiev, MSU 16 May 201141 Luminescent screen (new scintillators, not only crystals but phosphors too!) HV compound (like foam p-urethane) HV power supply HV connectors (no connectors, HV fully integrated into phototubes optical preamplifier, only low DC voltage input!? (like Hamamatsu’s small PMT modules) Photocathode We need 21st century technology

42. B.K.Lubsandorzhiev, MSU 16 May 2011 42 InGaN/GaN light emitting diodes Ultra bright, High Power UV, Violet, Blue, Cyen

43. B.K.Lubsandorzhiev, MSU 16 May 201143 Powerful nanosecond light sources for calibration systems Single LED drivers Matrixes of LEDs High power (HP) LEDs Matrixes of HP LEDs Baikal, GERDA, TUNKA, EMMA, T2K, ……….

44. B.K.Lubsandorzhiev, MSU 16 May 201144 High power LED drivers I LED > 3 A UB and HP LEDs Avalanche transistors

45. B.K.Lubsandorzhiev, MSU 16 May 201145 NXHL-NB98  t~ 5 ns (FWHM) 10 11 γ/pulse GERDA experiment

46. B.K.Lubsandorzhiev, MSU 16 May 201146 Royal blue – 455-460 nm D-A transitions For I LED > 1 A UV – 380 nm direct VC transitions I > (2-3)A  t ~ (1-2) ns InGaN/GaN LEDs

47. B.K.Lubsandorzhiev, MSU 16 May 2011 47 Fast Slow I-mediate Fast-Slow InGaN/GaN LEDs light emission kinetics under ns pulse high I (>2A)

48. B.K.Lubsandorzhiev, MSU 16 May 2011 48 NSPB500S; 1 - “old” 2- “new”KNGB; 1 - “old” 2- “new” GNL-3014BC

49. B.K.Lubsandorzhiev, MSU 16 May 201149 UV LEDs (370 nm) - Yellow band (DC activation) NSHU590

50. B.K.Lubsandorzhiev, MSU 16 May 201150 XR7090  t=3.5-4.0 ns (FWHM) max ~455 nm (380 nm) Y~10 12  /pulse

51. B.K.Lubsandorzhiev, MSU 16 May 201151 1 LED,  1/2 ~ 120 , helium baloon pilotless helicopter

52. B.K.Lubsandorzhiev, MSU 16 May 201152 4 LED drivers  = 360 

53. B.K.Lubsandorzhiev, MSU 16 May 201153 Light reflectors – white plastics (spring 2011) VM2000! (autumn 2011?)

54. B.K.Lubsandorzhiev, MSU 16 May 201154

55. B.K.Lubsandorzhiev, MSU 16 May 201155 Calibration system based on distributed nanosecond light sources Pulses from a single trigger unite are sent via long coax cables Developed initially for the lake Baikal neutrino experiment

56. B.K.Lubsandorzhiev, MSU 16 May 201156  T < 150 ps (FWHM) L cables =1200 m

57. B.K.Lubsandorzhiev, MSU 16 May 201157 Photon media Atmosphere Scintillators Fibers (FOP, WLS, ……).....................

58. B.K.Lubsandorzhiev, MSU 16 May 2011 58 FOP in calibration systems TUNKA-25 Fiber – 1mm PMMA cheap, available

59. B.K.Lubsandorzhiev, MSU 16 May 201159 Light pulses absorption in FOP Existence of absorption band at 600-650 nm is common for PMMA, PS and LS

60. B.K.Lubsandorzhiev, MSU 16 May 2011 60 Dispersion (mode+chromatic) = 80 ps/m Chromatic disp. = 10 ps/(m  nm) V = 5.3 ns/m

61. B.K.Lubsandorzhiev, MSU 16 May 2011 61 Diffusing balls The GERDA experiment at LNGS SilGel Wacker 612A + Ludox S32 Anisotropy - <10%

62. B.K.Lubsandorzhiev, MSU 16 May 201162 Scintillators WLS fibres SiPMs (MRS APDs, MPPC, SSPM, ……..)

63. B.K.Lubsandorzhiev, MSU 16 May 201163 SiPMs for plastic scintillators readout - green sensitive (~510-520 nm) SiPMs for LS-HP readout - violet/UV sensitive (350-400 nm)

64. B.K.Lubsandorzhiev, MSU 16 May 201164 E.Popova, S.Klemin, measured by Y.Musienko 2011

65. B.K.Lubsandorzhiev, MSU 16 May 201165 Conclusion Cosmic ray physics large scale experiments (EAS Cherenkov Arrays in particular) are ideal field of applications for nuclear photonics methods There are good chances for large sensitive area photodetectors (PMTs and/or Hybrids) in Russia. Ultra bright and high power LEDs provide new opportunities for development of calibration systems for cosmic ray physics large scale experiments