Comments on OPERA

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

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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 - PowerPoint PPT Presentation

Transcript of Comments on OPERA

Page 1: 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 Low energy electron detection

Page 2: Comments on OPERA

MeV Energy electron signal in OPERA

• CS1-CS2 alignment using Compton electrons. Very good track connection between two emulsion layers

σ ~ 1.8μm

By S. Miyamoto

Δy

Δy

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Double Beta decay detection by Nuclear 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

(Z,A)→(Z+2,A) + e1- + e2

- + νe1 + νe2 (Z,A)→(Z+2,A) + e1

- + e2-

Emulsion

Emulsion

Source

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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

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Set-up example NEMO3 level Next generation

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 !

20cm

20cm

25cm

50cm

50cm

45cm

2500 unit 4500 unit

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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

About BackgroundNEMO3 NEMO3

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理科年表(丸善)

10μm

βray

α ray track.

Uranium Chain

Thorium Chain

α decay

βdecay

Chain Products(Alpha and Beta) are contained within several micron^3

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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.

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In the case of Emulsion..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!

10μm

βray

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Needed Mass of emulsion• 100Mo Status strongest limit T1/2

0ν > 1023 year

MoO3 sheet(10μm thickness)

enrichment of 100Mo 90% ⇒more than 1,000 kg emulsion (efficiency ~ 100% , 1year exp.)

• 150Nd Status strongest limit T1/2

0ν > 1021 year

NdO3 (10μm thickness)

enrichment of 150Nd 91% ⇒more than 1kg emulsion (efficiency ~ 100% , 1year exp.)

• 96Zr Status strongest limit T1/2

0ν > 1021 year ZrO2 (10μm thickness) enrichment of 96Zr 57%

⇒more than 100 kg emulsion (efficiency ~ 100% , 1year exp.)

Status Nuclear Emulsion experiment Emulsion mass : 30,000kg

Source material should be decided by relation between Q-value and background or compatibility with emulsion.

For example

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energy resolutionAt least, E is about ⊿ 20% by effective range.

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 electro

n , Bremsstrahlung etc) ⇒   aim to 5%

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Low Energy electron signal

• CS1-CS2 alignment in OPERA( Compton Alignment)

By this technique, It is possible to detect the MeV electrons.

σΔx~ 2.1μm

σΔy~ 1.8μm

By S. Miyamoto

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2νββ and 0νββ

p

p

e-ν

n

n

e-

ν

W+

W+

n

n

e-W+

W+ e-

p

p

νR=νR

(T1/22ν) -1=G2ν (Q,Z) |M2ν|2 (T1/2

0ν) -1=G0ν (Q,Z) |M0ν|2<mν>2

• Which is neutrino Majorana or Dirac particle?• How much is neutrino’s mass?• Investigation of Lepton Flavor Violation

Neutrino must be Majorana particle. ( ν   = ν )

2νββ 0νββ

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Enegy spectrum of double beta decay

(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.

S(0

ν)/

N(2

ν)Energy resolution [%]

The case of T1/2 0νββ

T1/2 2νββ~ 106

Energy resolution is very important to distinguish between 0νββ  and 2νββ !!