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Comments on OPERA

Comments on OPERA. OPERA is going on. We will have good Tau neutrino interactions within years, if νμ － ντ oscillation is the real solution. New Techniques developed in OPERA Very fast Read out system SUTS, Emulsion film with new AgBr crystals

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Comments on OPERA

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  1. Comments on OPERA • OPERA is going on. We will have good Tau neutrino interactions within years, if νμ－ντ oscillation is the real solution. • New Techniques developed in OPERA Very fast Read out system SUTS, Emulsion film with new AgBr crystals Low energy electron detection

  2. MeV Energy electron signal in OPERA By S. Miyamoto Δｙ Δｙ σ～1.8μm • CS1-CS2 alignment using Compton electrons. Very good track connection between two emulsion layers

  3. Double Beta decay detection by Nuclear Emulsion Emulsion • Neutrino less Double Beta Decay 1) Two electrons emitted from one point.  Micron accuracy measurement Chance coincidence rejection by the position measurement 2) Total energy  Tracking Calorimeter: Track length + Grain information Source Emulsion (Z,A)→(Z+2,A) + e1- + e2- + νe1 + νe2 (Z,A)→(Z+2,A) + e1- + e2-

  4. Set-up example Basic Element : ECC configuration Source layer+ Emulsion layers (100Mo foil for example) Source (Foil) 10micron 50 micron emulsion layer on both sides of the foil. 1 Unit

  5. Set-up example 45cm NEMO3 level Next generation 50cm 25cm 20cm 50cm 20cm 2500 unit 4500 unit Source mass 10kg 100kg Emulsion Amount 10 litter 100 litter (FNAL E531 level) (CHORUS level) Scanning load 200 days OPERA SUTS Need X10 faster system !

  6. About Background NEMO3 NEMO3 Main Background : 214Bi ,208Tl (Max 3.17MeV beta) comes from Rn or contained U, Th chains. Those can be rejected by the existence of Alpha particles  easy in Emulsion

  7. Uranium Chain α decay βdecay Thorium Chain α ray track. 理科年表（丸善） βray 10μm Chain Products(Alpha and Beta) are contained within several micron^3

  8. Summary OPERA is going on. R&D in OPERA  Applications (Double Beta, Directional Dark Matter detection etc) Compact Double beta experiment with nuclear emulsion is possible. Current main background from Th・U chain can be rejected by detecting the existence of αrays.

  9. In the case of Emulsion.. 10μm βray In the emulsion, background caused by Th・U chain can be rejected by α ray track. Βray of Th・U chain exist with α ray!

  10. Needed Mass of emulsion • 96Zr • Status strongest limit • T1/20ν > 1021 year • ZrO2 (10μm thickness) • enrichment of 96Zr 57% • ⇒more than 100 kg emulsion • (efficiency ～100% , 1year exp.) Source material should be decided by relation between Q-value and background or compatibility with emulsion. For example Status Nuclear Emulsion experiment Emulsion mass : 30,000kg 100Mo Status strongest limit T1/20ν > 1023 year MoO3 sheet(10μm thickness) enrichment of 100Mo 90% ⇒more than 1,000 kg emulsion (efficiency ～100% , 1year exp.) 150Nd Status strongest limit T1/20ν > 1021 year NdO3 (10μm thickness) enrichment of 150Nd 91% ⇒more than 1kg emulsion (efficiency ～100% , 1year exp.)

  11. energy resolution effective range By trace of the one track, ⊿E is expected about 10% By developing the new emulsion of high sensitivity and having high AgBr density ( ex. Fine grain emulsion), pick up the some energy loss. (ionization, knock-on electron , Bremsstrahlung etc) ⇒aim to 5% At least, ⊿E is about 20% by effective range.

  12. Low Energy electron signal By S. Miyamoto σΔx ～2.1μm σΔy ～1.8μm • CS1-CS2 alignment in OPERA( Compton Alignment) • By this technique, It is possible to detect the MeV electrons.

  13. 2νββ and 0νββ 2νββ 0νββ p n n p e- e- W+ W+ ν νR=νR ν e- e- W+ W+ n n p p (T1/22ν) -1=G2ν (Q,Z) |M2ν|2 (T1/20ν) -1=G0ν (Q,Z) |M0ν|2<mν>2 Neutrino must be Majorana particle. ( ν= ν） • Which is neutrino Majorana or Dirac particle? • How much is neutrino’s mass? • Investigation of Lepton Flavor Violation

  14. Enegy spectrum of double beta decay S(0ν)/N(2ν) The case of T1/20νββ T1/22νββ ～106 Energy resolution [%] (Z,A)→(Z+2,A) + e1- + e2- + νe1 + νe2 (Z,A)→(Z+2,A) + e1- + e2- Total energy of 2 electron is Q-value region of energy spectrum of 2ν mode electrons. Energy resolution is very important to distinguish between 0νββand 2νββ !!

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