1. SYSTEMATICS (preliminary consideration) V. Sinev for Kurchatov Institute Neutrino group

2. Common consideration If the detectors, far and near, are absolutely identical, the ratio of two measured positron spectra S far and S near is energy independent: S Far /S Near = 1 in no-oscillation case, normalization: equal number of events Detector differences can mimic or hide oscillations Following deviations from detectors identity have been studied: Different energy resolutions  Far,  Near Different edge effects (positron annihilation quanta escape) due to different detector volumes V Far and V Near. Different light collection due to difference in the light absorption lengths (440 nm)

3. S far /S near for different energy resolutions Expected ratio for sin 2 2  13 =0.02,  m 2 = 2.5  10 -3 eV 2 Positron visible energy, MeV

4. S far /S near versus Detector volume ratio V far /V near Expected ratio for sin 2 2  13 =0.02,  m 2 = 2.5  10 -3 eV 2 V 1 =1.2V 2 Positron visible energy, MeV V 1 =1.15V 2 V 1 =1.1V 2

5. Light collection vs source position r and light attenuation length (440 nm) Light source position, m Transparency Light collection from the centre

6. S far /S near for different attenuation lengths far, near Expected ratio for sin 2 2  13 =0.02,  m 2 = 2.5  10 -3 eV 2 Positron visible energy, MeV

7. Neutron detection efficiency vs neutron capture point Distance from the centre, m

8. Two gammas absorbed energy versus the point of positron annihilation Distance from the centre, m

9. OTHER OPTIONS The Kr2Det scheme with two ~ 50 ton detectors at ~100 and 1000 meters uses available underground rooms and does not require digging new special caverns. The oscillation signal could be increased (1) with the far detector at about 1500 m and (2) in a 3 detector scheme: one near and two far detectors at ~1400 and ~ 2700 m. This increase will require larger volume detectors, deeper detector positions and digging new under- ground halls.

10. Visible energy, MeV S far /S near at different detector positions 1900/100  m 2 = 2.5  10 -3 eV 2 0 1 2 3 4 5 6 7 8 1.01 1 0.99 1.01 1 0.99 1000/100

11. Visible energy, MeV 1600/100 900/100 1600/900 1.01 1 0.99 1.01 1 0.99 0 1 2 3 4 5 6 7 8 2600/100 1300/100 2600/1300 1.01 1 0.99 3600/100 1800/100 3600/1800

12. Possible experimental result for ratio at Krasnoyarsk

13. Conclusion We estimated some effects which can influence the ratio to mimic effect of oscillation Kr2Det uses available underground halls for far (1000m) and near (115m) 50-ton detectors The oscillation signal could be somewhat increased with the Far detector at ~ 1400-1900 m or with two far detectors at ~ 1300 and 2600 m… This however would require digging new caverns and using detectors of larger target masses…

14. Letter of Intention I.R.Barabanov, L.B.Bezrukov, V.I.Gurentsov,V.N.Kornoukhov, E.A.Yanovich Institute for Nuclear Research of RAS (Moscow, Russia) N.A.Danilov, G.V.Korpusov, Yu.S.Krylov Institute of Physical Chemistry of RAS (Moscow, Russia) Development of a recipe and production of components for a liquid scintillator doped with Gd for K2Det or Kashiwazaki experiment.

15. 1. Development of test batches of Gd- compound for a liquid scintillator. Based on experience in the framework of LENS Collaboration on the development of Yb-loaded scintillator with characteristics: LY = 60% of BC 505; (8% of Yb), L 1/2 (430 nm) ~ 2.5 m (8% of Yb), ^ when c dec. we propose to develop and synthesized Gd-loaded LS replacing in our Yb-Carboxylate compound Yb by Gd because of their common chemical properties (even more difficult for Yb). M ~ 2 x 150 kg (0,3% of Gd) The procedure is just simple blending “Gd-compound + solvent”. 2. Production, purification and certifi- cation of an effective primary fluorescent additive (fluor) BPO, 2[4-biphenyl]5-phenyl oxazole. Light Yield of BPO is ~ 50% more than LY of PPO. M = ~ 2 x 100 kg Development of new fluor with maximum emission in 430-440 nm

16. 3. Delivery of organic base (a solvent) for LS with a high flash point (~ 80 o C). M ~ 100 t Light output 80% of Whitespirit Composition H/C ~1.8 Transparency >10 m Radio purity is low but should be investigated Chemical activity - weak If LS has H:C ~ 2 (for example, Palo Verde and CHOOZ experiment): Then for Gd = 0% (100% captured probabilities with E = 2.2 MeV):  = 180  sec for Gd = 0.1%(86% captured probabilities with E ~ 8 MeV, well above the natural radioactivity):  = 32  2%  sec