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Simulation study of RENO-50

Simulation study of RENO-50. Jungsic Park Seoul National University. RENO-50 International Workshop June 13-14, 2013 Hoam Faculty House, Korea. Preliminary RENO-50 Detector Concept. Concentric cylindrical detector. Initial concept is same as RENO. No gamma-catcher region and

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Simulation study of RENO-50

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  1. Simulation study of RENO-50 Jungsic Park Seoul National University RENO-50 International Workshop June 13-14, 2013 Hoam Faculty House, Korea

  2. Preliminary RENO-50 Detector Concept • Concentric cylindrical detector. • Initial concept is same as RENO. • No gamma-catcher region and • filled with Liquid Scintillator Only. • Install 15000, 10 inch inner PMTs • and 1000, 10 inch outer PMTs. RENO-50 1000 10” OD PMTs Water Mineral Oil LS (10 kton) 15000 10” PMTs 27 m 25 m 32 m KamLAND x 10 25 m 27 m 32 m

  3. RENO-50 Detector with Monte-Carlo Target : Acrylic, 25m*25m Buffer : Stainless-Steel, 27m*27m Veto : Concrete, 32m*32m Top & Bottom 2501PMTs for each region. (60 for RENO) 45cm 45cm PMT attachment scheme. Barrel : 50raw * 200 column (9*26 for RENO) Interval of each PMT center is 50cm. 2700cm 2700cm

  4. Energy resolution Assume that optical properties and thickness of detector materials are same as RENO detector. For the energy resolution, we generate single gamma of various energy (1~10MeV) at the detector center. PMT coverage : 23.95% Using the initial concept, we get ~7% resolution @ 1MeV and calculated PMT coverage is 24%.

  5. Measurement of θ12 and Δm221 sensitivity test by Monte-Carlo. Using the Pseudo-experiment , check the sensitivity of θ12 and Δm221 measurement. True value : varied varied fixed fixed Assume 10kton * 20GW * 5years exposure

  6. Χ2 fitting with pulls for θ12 Nsignal = 30000 (oscillation , 10kton, 20GW, 5years, 100% efficiency & Livetime) Nbkg = 300 (~1% level) ε = 1.0 (detection efficiency) b,e, f : pull parameter (e : efficiency, f : reactor) σeff = 0.015 (1.5%) σr = 0.03 (current limit : ~3%  goal is below 1%) σb = 0.05 (5%) Nexpr : Expected event number without oscillation Funcosci(θ12) : oscillation / No oscillation (fraction)

  7. Χ2 fitting result σeff = 0.015 (1.5%) σr = 0.03 (3%) σb = 0.05 (5%) True value : 0.8556 Fitting value : 0.8552 +- 0.0162 (1σ)  ~1.89%

  8. Statistical part only for θ12 Statistics part decrease very rapidly. The main portion is systematic part.

  9. Systematical part for θ12 We assumed σb is zero. Uncertainty of detection efficiency and reactor uncertainty are both important.

  10. Χ2 fitting with pulls for Δm221 • For the Δm221 , we should use the spectrum shape. • N_signal, N_exprN_bkg should be considered bin by bin. • Assumed that background is flat. (same number for each bin content) • 50bin/MeV • 1.8 ~ 8 MeV range cut ε = 1.0 (detection efficiency) b,e, f : pull parameter (b: background, e : efficiency, f : reactor) σeff = 0.015 (1.5%) σr = 0.03 (current limit : ~3%  goal is below 1%) σb = 0.05 (5%)

  11. Systematical part for Δm221 σeff = 0.015 (1.5%) σr = 0.03 (3%) σb = 0.05 (5%) True value : 7.6e-5 Fitting value : (7.598 +- 0.048)e-5 (1σ)  ~0.64%

  12. Expected neutrino visible energy spectrum of RENO-50

  13. Energy resolution plays a crucial role to RENO-50 Solid line : Normal Hierarchy Dashed line : Inverted Hierarchy @1MeV So, How can we increase the energy resolution ?

  14. Improve the optical properties Increase the attenuation length of Liquid Scintillator. - 1.5 times current value : 18.7m @ 430 nm - 2.0 times current value : 24.9m @ 430 nm Increase the PMT Quantum Efficiencies. - 1.25 times current value : 30.0% @ 427 nm - 1.5 times current value : 36.0% @ 427 nm 3. Increase the PMT coverage. - 25000 PMTs : 40.86 % coverage Cf) Default value 24% PMT coverage Att.length of LS is 12.4m @ 430 nm PMT QE is 24% @ 427 nm

  15. PMT Quantum Efficiency of R7081 Hamamatsu 10 inch PMT 24% @ 430 nm Maximum 25% @ 390nm

  16. Attenuation Length of Current Materials. Mineral Oil Liquid Scintillator Liquid Scintillator : 12.4m @ 430 nm Mineral Oil : 17.0m @ 430 nm

  17. Increase the Attenuation Length Attenuation length should be comparable of detector size.

  18. Increase the PMT Quantum Efficiency

  19. Increase the PMT Coverage

  20. Applying all the Improvement Effect It’s very challenging task to acquire ~3% energy resolution.

  21. Summary • RENO-50 Monte-Carlo preliminary version was made. • Statistical uncertainty decrease rapidly within few years. • Detection efficiency and reactor uncertainty contributes to systematic a lot. • Including other uncertainty parameters is still keep going. • 3% energy resolution is very challenging task. • We should improve all the Optical properties about twice. • It’s time to think about the improvement method all together.

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