1. I.Laktineh, IPNL 1 Nagoya, 2006 Studying the neutron quantum states in the gravitational field “using nuclear emulsion technique” Motivations Motivations Results obtained with CR39 Results obtained with CR39 Perspectives with emulsion Perspectives with emulsion

2. Nagoya, 2006I.Laktineh, IPNL2 "Let us consider another possibility, an atom held together by gravity alone. For exemple, we might have two neutrons in a bound state. When we calculate the Bohr radius of such an atom, we find that it would be 10 8 light years, and that the atomic binding energy would be 10 -70 Rydbergs. There is then little hope of ever observing gravitational effects on systems which are simple enough to be calculable in quantum mechanics." Brian Hatfield, in "Feynman Lectures on Gravitation" ; R.P. Feynman, F.B. Morinigo, W.G. Wagner, Ed. Brian Hatfield Addison-Wesley Publishing Company, 1995, p. 11

3. Nagoya, 2006I.Laktineh, IPNL3 Neutrons in gravitational field 1,41 2,46 3,32 0 14 24 32 Academic exercise

4. Nagoya, 2006I.Laktineh, IPNL4 Some history Solution of Schrödinger equation with linear potential 1928 : Solution of Schrödinger equation with linear potential 1928 : G. Breit, Phys Rev 32 (1928) 273 First attempts of ultra cold neutron storage at JINR (Dubna) in 1968 : First attempts of ultra cold neutron storage at JINR (Dubna) in 1968 : V.I. Luschikov et al., JETP Lett 9 (1969) 40 1976, proposal to look for quantum energy levels using ultra old neutrons : 1976, proposal to look for quantum energy levels using ultra old neutrons : V.I. Luschikov, Physics Today 42 (1977) 51; V.I. Luschikov and A.I. Frank, JETP Lett 28 (1978) 559 First observations of the quantum states in a gravitational field at ILL/France in 1999 : First observations of the quantum states in a gravitational field at ILL/France in 1999 : V.V.Nesvizhevsky et al., Nature 415 (2002) 297; V.V.Nesvizhevsky et al., Nature 415 (2002) 297; Phys Rev D87 (2003) 102002

5. Nagoya, 2006I.Laktineh, IPNL5 Institut Laue Langevin, Grenoble/France ILL ESRF LPSC/IN2P3 100 km from Lyon

6. Nagoya, 2006I.Laktineh, IPNL6 requirements To observe quantum states in gravitational field - neutral particle - long lifetime ultracold neutron - small mass (E<2 µeV, V<6 m/s) - weak energy (very low temperature) A well provided by -a mirror with: - elastic diffusion at least 99,99% - absorption 10 -5 negligible vertical - inelastic diffusion < 10 -4 speed -a gravitational field

7. Nagoya, 2006I.Laktineh, IPNL7 Experiment setup 10 cm Vh = few m/s Vv = few mm/s x

8. Nagoya, 2006I.Laktineh, IPNL8 Detector

9. Nagoya, 2006I.Laktineh, IPNL9 Neutrons in gravitational field 1,41 2,46 3,32 0 14 24 32 Academic exercise

10. Nagoya, 2006I.Laktineh, IPNL10 Wave function

11. Nagoya, 2006I.Laktineh, IPNL11 Procedure After the exposure to the UCN beam one has to - take out the Uranium (U235) layer - itch the CR39 to produce the tracks - scan the CR39 The observation of the quantum states of neutrons in gravitational field can then be obtained by “visualizing” the square wave function module using the neutron impact density. Many problems were to be addressed: -The Z zero position should be determined for the whole CR39 plate -The mechanics precision should be less than 1  But Itching leads to the CR39 curvature as well as scratches…

12. Nagoya, 2006I.Laktineh, IPNL12 Etching of uranium coating The etching may curve the detector in following manner: For this reason reference lines were used to estimate the curvature

13. Nagoya, 2006I.Laktineh, IPNL13 First results Nesvizhevsky et al., J. Phys. C40 (2005) 479 Results obtained by semi automatic scannig

14. Nagoya, 2006I.Laktineh, IPNL14 What the automatic scanning can provide? The semi-automatic scanning suffers from some drawbacks 1) It lasts about two months for each plate leading to uncertainties on the absolute position due to temperature and mechanics 2) Human intervention introduces subjective decisions which thus differ from one operator to another. 3) CR39 degradation with time if not properly protected

15. Nagoya, 2006I.Laktineh, IPNL15 What the automatic scanning can provide? At the French Scanning station we adapted the ESS to scan some of the exposed CR39. At the French Scanning station we adapted the ESS to scan some of the exposed CR39. The tracks are limited to the surface with a maximum penetration of 10 microns. The tracks are limited to the surface with a maximum penetration of 10 microns. 12-15 tomographic layers were used  1h/plate. 12-15 tomographic layers were used  1h/plate. All the tracks were found except those of large angle All the tracks were found except those of large angle (tg  > 5) (tg  > 5) Scratches dues to itching process simulated fake tracks Scratches dues to itching process simulated fake tracks “however automatic scanning can be controlled easily and quickly by a manual scanning” “however automatic scanning can be controlled easily and quickly by a manual scanning”

16. Nagoya, 2006I.Laktineh, IPNL16 What the automatic scanning can provide? In 2007-2008 a new run with more statistics is expected CR39 is a good detector but its relatively bad surface planarity and the scratches left by the Uranium itching convince us to try to use emulsion. However emulsion density is about twice the CR39 one ( 3 vs 1.3) which means that ions will produce very short tracks CR39 is a good detector but its relatively bad surface planarity and the scratches left by the Uranium itching convince us to try to use emulsion. However emulsion density is about twice the CR39 one ( 3 vs 1.3) which means that ions will produce very short tracks (< 5 microns) which are hard to work out. (< 5 microns) which are hard to work out. Diluted emulsion of 20-30 microns thickness can be of great help. Indeed the tracks can be seen from the side opposite to the U235 covered side limiting the scratches Diluted emulsion of 20-30 microns thickness can be of great help. Indeed the tracks can be seen from the side opposite to the U235 covered side limiting the scratches effects effects In both cases tracking algorithms capable of finding horizontal tracks are on preparation. In both cases tracking algorithms capable of finding horizontal tracks are on preparation.

17. Nagoya, 2006I.Laktineh, IPNL17 Conclusion The automatic scanning development we engaged for OPERA can be a wonderful tool for amazing and very interesting application. Ultra cold neutrons is one of those topics that our scanning system can perform with negligible systematics. (quantum states, 5th force search, axions…) The emulsion can be a competitive and even better one but we need help from our Japanese colleagues.