1. Quantum optical experiment on measurement of the gravitational force acting on the neutron Session of the Programme Advisory Committee for Nuclear Physics. 25 January 2008

2. 25 December 2008 Session of PAC for Nuclear physics 2 Authors А.I..Frank, G.V.Kulin, D.Kustov, FLNP JINR, Dubna P.Geltenbort, M.Jentschel, ILL, Grenoble A.N. Strepetov, V.G.Nosov. RRC I.V. Kurchatov Institute, Moscow

3. 25 December 2008 Session of PAC for Nuclear physics 3 The aim was to test weak equivalence principle for neutron in new type of neutron experiment

4. 25 December 2008 Session of PAC for Nuclear physics 4 Overview 1.Neutrons and the equivalence principle (background). 2. New neutron gravity quantum experiment (ILL 2006). 3. New proposal for the tests of weak equivalence principle for neutron principle for neutron

5. 25 December 2008 Session of PAC for Nuclear physics 5 L.Koester, 1976 V.F.Sears,1982 Knowing the neutron mass m and local free fall acceleration g loc one can obtain the effective scattering length b eff Coherence length b was measured also in the neutron scattering experiment with Pb and Bi. Thus the equivalence factor  was found 1-  = 3  10 -4

6. 25 December 2008 Session of PAC for Nuclear physics 6 Koester’s experiment and the problem of n-e scattering It is not evident that b ne is known with such precision even now When the value of b coh extracts from thetotal cross section data it is necessary to take into account n-e scattering. For the case of Pb and Bi correspondent corrections are of the order 1%. Consequently, if one aim to reach 10 -4 in precision of b coh the amplitude of n-e scattering must be known with precision of 1%.

7. 25 December 2008 Session of PAC for Nuclear physics 7 Quantum experiments with neutron interferometer R.Colella, A,W.Overhauser and S.A. Werner (COW), 1975 K.S.Litrell, B.E.Allman and S.A.Werner, 1997 The experimentally obtained values for the gravitationally induced phase factor u were lower than the theoretically expected value by 1.5% for the skew-symmetric interferometer data and 0.8% for the symmetric interferometer data in measurements with relative uncertainties of 0.12% and 0.11%, respectively. ILL experiment of G.van der Zouw, et al. (2000) with the accuracy of about 0.9% did not solve the problem.

8. 25 December 2008 Session of PAC for Nuclear physics 8 The idea of new neutron gravity quantum experiment completely based on the previous results of our group The idea of new neutron gravity quantum experiment completely based on the previous results of our group

9. 25 December 2008 Session of PAC for Nuclear physics 9 Idea of the experiment H Two components are necessary for the realization 1.Non stationary device 2. Spectrometric elements E0  EE0  E E HH E 0 + mgH E 0 – ħ  1 + mgH E 0 – ħ  2 + mgH

10. 25 December 2008 Session of PAC for Nuclear physics 10 Moving grating as a non stationary device

11. 25 December 2008 Session of PAC for Nuclear physics 11 Moving grating y z V K A.Frank, V.Nosov, 1994 y´ z´ K´ V 1. Solution of a diffraction problem in a moving system. 2. Galilean transformation of the wave function.

12. 25 December 2008 Session of PAC for Nuclear physics 12 Main theoretical results L – period of grating  (y) – (complex) transmission function for the single grating element

13. 25 December 2008 Session of PAC for Nuclear physics 13 Moving grating as a quantum modulator Diffraction in -1 orderwas used in our experiment E E a 0 = 0 ! E

14. 25 December 2008 Session of PAC for Nuclear physics 14 Experimental realization UCN n L d Monochromator Si d=0.14  where  is an angular period and N – number of groves N = 75398 55

15. 25 December 2008 Session of PAC for Nuclear physics 15

16. 25 December 2008 Session of PAC for Nuclear physics 16 The spectrometry of UCN based on the using of quantum monochromator – Fabry-Perot interferometer

17. 25 December 2008 Session of PAC for Nuclear physics 17 Fabry Perot interferometer (Neutron Interference filter) Energy of the state 121 Substrate

18. 25 December 2008 Session of PAC for Nuclear physics 18 UCN spectrometer with Fabry-Perot interferometers Two NIFs with variable distance between them mg=1.02 neV Detector

19. 25 December 2008 Session of PAC for Nuclear physics 19 Experimental results Scanning curves measured at various grating rotation frequency and correspondent fitting curves

20. 25 December 2008 Session of PAC for Nuclear physics 20 Final result B exp = 0.3037 ± 0.00065 B th = 0.30421 N = 75398

21. 25 December 2008 Session of PAC for Nuclear physics 21 The spectrometer at the PF2 beam of ILL

22. 25 December 2008 Session of PAC for Nuclear physics 22 III. Nearest Future: New Gravity UCN spectrometer with FP- interferometers and modulation of intensity Alternative measurement method will be used. Time of flight with the measurement of the count rate Time of flight with the measurement of the count rate modulation phase Estimated sensitivity (2÷4)  10 -4 UCN

23. 25 December 2008 Session of PAC for Nuclear physics 23 IV. What after? New gravity experiment What was measured in previous experiments? It is seems very attractive to perform experiment where m i /m g will be measured without any additional information Koester Dubna - ILL- Kurchatov. inst. m is known tabular data of neutron mass The best is the direct measurement of g n

24. 25 December 2008 Session of PAC for Nuclear physics 24 Neutron fountain for the measuring of g n Detector For the measure of time it was proposed to use 1. Interference filter 2. Chopper- modulator Modified idea of Yu.N. Pokotilovsky (1994), 3. The phase of the intensity of the count rate oscillations will be measured.

25. 25 December 2008 Session of PAC for Nuclear physics 25 Neutron fountain for the measuring of g n Detector Only the phase of count rate oscillation will be measured at different position of the monochromator Vertical mirror may be added Solid angle   Estimation shows that precision of the order 10 -5 may be achieved at the exist UCN source of the ILL

26. 25 December 2008 Session of PAC for Nuclear physics 26 FLNP group for quantum UCN optics Sergey Kashirin Phd student (24) Dmitro Kustov (L) and German Kulin (R) Two researcher physicists (30) and (28) Two researcher physicists (30) and (28) Group leader Group leader Alexander Frank Designer engineer (24) Valentina Bulavina

27. 25 December 2008 Session of PAC for Nuclear physics 27 Thank you for your attention!

28. 25 December 2008 Session of PAC for Nuclear physics 28 Interaction of neutrons with accelerating matter Interference filters – neutron Fabry –Perot interferometers Multilayer structures on a Si wafer. Number of layers 5-120. Typical thickness of a layer 200- 300 Å. Uniformity 2-3%