1. DANSS V.Egorov egorov@jinr.ru JINR (Dubna) + ITEP (Moscow) КАЭС

2. SPb Moscow DubnaJINR KNPP 285 km 164 km

3. Participants of the NANPino-2013 workshop (Valday, June 2013) visiting the DANSS site at KNPP

4. Service room  3 000 MW th ВВЭР-1000

5. (1946)

6. Fraction of fissions Time after beginning of operation period, days Direct detection of the reactor neutrino would allow: Measure the actual reactor power (N ν ) Deduce the actual fuel composition (E ν ) Non-proliferation (prevent unauthorized extraction of 239 Pu) Weak (ν-e) cross-section On-line reactor monitoring (tomography?)

7. Reservoirs with technological liquids (cooling pond, boric acid, etc.) Core: h =3.50  = 3.12 DANSS on a movable platform with a lifting gear. flux  5  10 13 / cm 2 / s Overburden ≈ 50 m w. e. Typical reactor building with WWER-1000  Forbidden to use dangerous materials (LS) nearby the reactor

8. Segmental solid plastic scintillator (2500 cells) Sensitive volume=1 m 3 Cu (carriage frames =  -shield) CH 2 + B (n-shield) Pb (  -shield) Plast. scnt. (µ-veto)

9. Basic element – - scintillator strip (1×4×100 cm) Gd-containing light-reflecting coating Polystyrene- based scintillator 3 wave-length shifting (WLS) fibers Ø1.2 mm

10. Conception of the detector: modular structure 2500 strips are combined into intercrossing X- and Y-modules (20  20  100 cm), thus providing not only energy information but also space pattern of each event.

11. 11 L = 12.2 mL = 9.8 m

12. Expected parameters: Sensitive volume : 1 m 3 =100×100×100 cm Scintillator: Polystyrene based ( ~7.7 % wt of H) Structure: (25 X + 25 Y) intercrossing modules =2500 strips 1 module 20×20×100 cm = 50 parallel strips Mass with (CHB+Cu+Pb)-shield: 16-18 tonnes Site: reactor unit#4 of Kalinin NPP (standard industrial WWER-1000, Ø3.12 x h3.50 m, 3000 MW th ) Reactor–Detector distance : 9.8–12.2 m (variable on-line) Count rate: (10 000 IBD + 50 BG) /day @11 m Energy resolution @ E =4 MeV: 25% (FWHM)

13. Unfortunately, design and creation of the lifting system took longer time than expected. (Nonstandard equipment: must be certified!...) Moreover, its mounting near the reactor was allowed to be done only during the fuel recharge period (when the reactor is OFF). 2-years delay… But we did not loose our time!

14. Pilot version : 2 modules of 50 = 40 kg = 1/25 th of DANSS Simplified light collection (2 PMT only, no MPPC) Simplified electronics (4 QDC and 1 TDC) Simplified data selection

15. Reactor power Rate of neutrino-like events detected per day Time [hours] S/B  1

16. DANSS ino results: it works! 100 /day S/B  1  E-resolution is poorer than expected: n = 10 ph.e./MeV 2.5 MeV  25 ph.e.   25   20% How to improve Energy Resolution? The signal should be increased (light yield + light collection + quantum efficiency) arXiv:1305.3350 [physics.ins-det] arXiv:1304.3696 [physics.ins-det]

17. 17 … if the after ends of strips be UV-illuminated, one can see: 2500 strips of Kharkov (UA) scintillator have been already prepared (equipped with WLS- fibers and MPPCs). But… 17 16 13 10 12 Visible only before the fibers been glued in!

18. Improvements implemented: All prepared strips have been thrown away  and new 2500 strips have been selected (by color) from 7000 Ultra Bialkali PMT R7600U-200 replaced by Extended Green Bialkali ones R7600U-300 Home-made MPPC replaced by Hamamatsu S12825-050C(X) – new! with reduced noise

19. 19 22 Hamamatsu MPPC S12825-050C(X) 18 + 22 = 40 p.e./MeV Resolution @ E =4 MeV: N =(4.0  1.8)×40 = 88 p.e.  E/E = √N / N = 11% (  ) = 25% (FWHM) 18

20. DANSS ino  DANSS ino 2 Huge edge effects  efficiency  10-15% (instead of 72) ~400 IBD/day (S/B >> 1)

22. 13.2 pe/MeV 19.7 pe/MeV

23. Optimization of the basic scintillator element (ENVINET plate) WLS fibers: Kuraray (JP) vs Bicron (S t -Gobain)  vs  pTP concentration: 0.6 – 1.0 – 1.5 – 2.0 – 2.5 – 3.0 – 3.5 % POPOP concentration: 1/10 – 1/5 – 1/2 – 1/1 – 2/1 of standard Wrapping: Mylar – Teflon – Tyvek – BC620 - … MPPC: Hamamatsu vs SensL

24. V = 4*4*4 = 64 L 4 * 10 = 40 X-plates (1*20*40 cm) 8 PMT + 200 MPPC 8 PMT + 80 MPPC X Y DANSSino2  S 3 40 p.e./MeV 70-80 p.e./MeV ~400 IBD/day tomography?..

25. Temelin NPP@CZ: 2 x ВВЭР-1000

26. Due date Final mounting of the lifting system: Sep 2014 Mounting of the moveable platform: Oct 2014 Mounting of the bottom shielding: Nov 2014 New control board of the lifting system:Feb 2015 Mounting of the DANSS detector: Mar 2015 Mounting and tuning of the ACQ: summer 2015 Mounting of the rest shielding: summer 2015 Mounting of the Muon Veto: summer 2015 Start of data taking: summer 2015 Off-line and on-line tests with S 3 summer 2015 @(KNPP and Temelin NPP) The main braking factor: mnt. could be performed only when the reactor is stopped for recharge…

27. ITEP (Moscow) CTU (Prague) JINR part of the DANSS team

28. Few words about “sterile sensitivity” of DANSS 1y operation

29. Core dim.: D3.12 x H3.50 m Burning prob.: p~cos(  h/H)  cos(  r/D) E resolution: 25 p.e./MeV

30. All parameters of the reactor and the detector are known absolutely Optimistic case We compare (at 90%CL) absolute count rates in 3 positions (100 days/pos) with calculated ones - keV by keV

31. Absolute neutrino intensity and the detector efficiency are not known Realistic case We compare (at 90%CL) shapes of energy spectra in 3 positions (100 days/pos) with calculated ones - keV by keV

32. Only geometric parameters of the reactor and the detector are known Pessimistic case We compare (at 90%CL) evolution of each energy bin with distance (3 positions, 100 days/pos) Theor. E -spectra, fuel composition, power variations, detector efficiency are not used at all.

33. Ongoing projects with reactor short- range neutrino oscillations namescintil.masssegm.depthmov.DistMWStatus DANSS @ RUSS + Gd1.0250050+9.7 – 12.23000mount Nucifer @ FRLS + Gd0.75113–770operation Neutrino4 @ RULS + Gd2.22few+6-12100mount STEREO @ FRLS + Gd1.75118+8.8 – 11.250R&D SoLid @ UK 6 LiF:ZnS3.06410–6 – 845 – 80R&D (Hanaro) @ KRLS + Gd, 6 Li0.51few+630R&D PROSPECT @ USLS + Gd, 6 Li1 & 101few–4 & 1820 – 120R&D NuLat @ USSS + 10 B, 6 Li1.03375few+3 – 81500R&D Poseidon @ RULS + Gd1.55few–5 – 15100MC (CARR) @ CNLS + Gd~11few–7 & 1560MC

35. Spare slides

36. Detection idea: Inverse Beta-Decay in plastic scintillator interlayed with Gd or Cd e+e+ 157 Gd (n,  )  E  =8 MeV  =255000 155 Gd (n,  )  E  =8 MeV  = 60900  ≈ 2-30  s

37. Section #3

38. Probably, IBD happened @(X=2,Y=2,Z=3) ↓ read detailed info from all X- and Y- strips around the event position (within 50 μs before the trigger) and check if there was a positron. Section #3

39. Calibration system 25 X + 25 Y capillaries run through the entire detector body (at the axis of each of 50 modules)

40. Radioactive source: 137 Cs ( , e) 22 Na ( , e + ) 60 Co (  ) 248 Cm ( ,3n,  ) etc. Teflon tube

41. The role of the source dimensions

42. True IBD Random  -n  -induced 248 Cm Time, μs Relative number of events

43. Spectrum simulated for 235 U fission Rate of neutrino-like events / 0.5 MeV / day (Differential spectrum = ON — OFF) Prompt Energy MeV

44. Max=1.77 Med=1.93 Mean=2.09