B.K.Lubsandorzhiev, MSU 16 May 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

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

B.K.Lubsandorzhiev, MSU 16 May s 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.

B.K.Lubsandorzhiev, MSU 16 May 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, …….. )

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

B.K.Lubsandorzhiev, MSU 16 May 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)

B.K.Lubsandorzhiev, MSU 16 May 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

B.K.Lubsandorzhiev, MSU 16 May 20118

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

B.K.Lubsandorzhiev, MSU 16 May 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

B.K.Lubsandorzhiev, MSU 16 May 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?

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

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

B.K.Lubsandorzhiev, MSU 16 May 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

B.K.Lubsandorzhiev, MSU 16 May 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

B.K.Lubsandorzhiev, MSU 16 May 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.

B.K.Lubsandorzhiev, MSU 16 May 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

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

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

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

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

B.K.Lubsandorzhiev, MSU 16 May R ,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

B.K.Lubsandorzhiev, MSU 16 May 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!

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

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

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

B.K.Lubsandorzhiev, MSU 16 May 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.

B.K.Lubsandorzhiev, MSU 16 May 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

B.K.Lubsandorzhiev, MSU 16 May 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.

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

B.K.Lubsandorzhiev, MSU 16 May 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

B.K.Lubsandorzhiev, MSU 16 May 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 * F * 0? 0? * - using a photodetector with A3B5 photocathode

B.K.Lubsandorzhiev, MSU 16 May 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

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

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

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

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

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

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

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

B.K.Lubsandorzhiev, MSU 16 May 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

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

B.K.Lubsandorzhiev, MSU 16 May 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, ……….

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

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

B.K.Lubsandorzhiev, MSU 16 May Royal blue – 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

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

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

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

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

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

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

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

B.K.Lubsandorzhiev, MSU 16 May

B.K.Lubsandorzhiev, MSU 16 May 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

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

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

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

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

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

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

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

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

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

B.K.Lubsandorzhiev, MSU 16 May 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