1. 1 Experimental investigation of spatial parity violation effects in interaction of the polarized neutrons with light nuclei with the purpose of determination of weak meson-nucleon coupling constants Low energy physics: neutron physics at E n ~10 -3 eV Search for the neutral currents in the weak NN-interaction. Test of the validity of the meson exchange description of the weak NN-force. Interpretation of the P-odd observables in complex nuclei and in the eN scattering experiments. Electroweak interaction at low energy as the tools to study the strongly interacting limit of QCD. [W. M. Snow. J. Res. NIST 110 (2005) 189] P. V. Sedyshev. Frank Laboratory of Neutron Physics, JINR, Dubna, Russia

2. 2 NN electroweak interactions at low energy Light quarks u, d, s.  C – Cabibbo angle, sin  C  0.22  T – amount of isospin change

3. 3 NN electroweak interactions at low energy Description of the parity nonconservation NN interaction: Potential (meson-exchange) description: R. J. Blin-Stoil. Phys. Rev. 118 (1960)1605; G. Barton. Nuovo Cimento 19 (1961) 512; B. H. J. McKellar. Phys. Lett. B26 (1967) ; E. M. Heinly. Ann. Rev. Nucl. Part. Sci. 19(1969) 367; E. Fischbach, D. Tadic. Phys. Rep. C6 (1973) 123; M. Gari. Phys. Rep. C6(1973) 318; B. Desplanques, J. Donoghue, B. Holstein. Ann. Phys. 124 (1980) 449; B. Desplanques. Phys. Rep. 297 (1998) 1. Amplitude description: G. S. Danilov. Phys. Lett. 18 (1971) 35, M. A.Box, B. H. J. McKellar, P. Pick, K. R. Lassey J. Phys. G1 (1975) 493; B. Desplanques, J. Missener. Nucl. Phys. A300 (1978) 286. Analysis using an EFT and chiral perturbation; calculation with use of lattice gauge theory: S.-L. Zhu, J. Puglia, B. R. Holstein, M. J. Ramsey-Musolf. Phys. Rev. D63 (2001) 033006.

4. 4 One meson exchange model R. J. Blin-Stoil. Phys. Rev. 118 (1960)1605; G. Barton. Nuovo Cimento 19 (1961) 512; B. H. J. McKellar. Phys. Lett. B26 (1967) ; E. M. Heinly. Ann. Rev. Nucl. Part. Sci. 19(1969) 367; E. Fischbach, D. Tadic. Phys. Rep. C6 (1973) 123; M. Gari. Phys. Rep. C6 (1973) 318; B. Desplanques, J. Donoghue, B. Holstein. Ann. Phys. 124 (1980) 449;B. Desplanques. Phys. Rep. 297 (1998) 1. Strong NN interaction: R rep  0.8 fm – repulsive core described by spin-spin interaction between quarks; R M  2 fm – one-meson exchange model; Intermediate distances – parameters are fitted Weak NN interaction: R W,Z  10 -3 fm – no direct exchange. Meson exchange. N N N N M PVPC N N N N M

5. 5 One meson exchange model N N N N , ,  PVPC  0, ,  ’ - exchange is forbidden, due to the CP-invariance;  - exchange is strongly suppressed  ± -  T=1  -  T=0, 1, 2  -  T=0, 2

6. 6 One meson exchange model PNC NN potential is characterized by weak meson exchange coupling constants [V. M. Dubovik, et. al. PEPAN 18 (1987) 575; B. Desplanques. Phys. Rep.297 (1998) 1] :

7. 7 Weak meson-nucleon coupling constants The MNN coupling constants are calculated from the flower-conserving part of the weak interaction [V. M. Dubovik, et. al. PEPAN 18 (1987) 575; B. Desplanques. Phys.Rep.297 (1998) 1] Due to uncertainties in the effects of strong QCD, the range of predictions is broad. DDH – B. Desplanques, J. F. Donoughu, B. R. Holstein [B. Desplanques, J. Donoghue, B. Holstein. Ann. Phys. 124 (1980) 449] - used the quark model, SU(6) symmetry, the strong interaction effects are treated in RGT. DZ – V. M. Dubovik, S. V. Zenkin [V. M. Dubovik, S. V. Zenkin. Ann. Phys. 172 (1986) 100 ] – used the quark model, SU(6) symmetry, the strong interaction effects are treated in RGT. FCDH - G. B. Feldman, G. A. Crawford, J. Dubach, B. R. Holstein [G. B. Feldman et. al. Phys. Rev. C43 (1991) 863] – included M  N and M  vertices. KM – N. Kaiser, U. G. Meissner [N. Kaiser, U. G. Meissner. Nucl. Phys. A 499 (1989) 699] – calculated within the framework of a nonlinear chiral effective Langragian.

8. 8 Weak meson-nucleon coupling constants Weak meson-nucleon coupling constants (in units of 10 -7 ): G. A. Lobov: f  = 3.4∙10 -7 [G. A. Lobov. Phys. At. Nucl. 65 (2001) 561.] is calculated by the method of QCD sum rules.

9. 9 One meson exchange model Theories of PV phenomena in nuclei starts with solution of the strong, PV conserving, nuclear Hamiltonian  and the admix P-odd components  treating the weak meson- exchange potential as a perturbation : The PV observable is given by a linear combination of weak MNN constants: Problems: Theoretical – for more than a few bodies the nuclear wave functions can not be exactly calculated; Experimental – the small size of weak amplitudes relative to strong amplitudes ~10 -7. Task: using this theory to calculate electroweak effects in the NN interaction and to determine the weak couplings from experiment.

10. 10 Experiments ObservableExperiment, 10 -7 f  -0.12h  1 -0.18h  1 h  0 +0.7h  0 h1h1 h2h2 h0h0 h1h1 A z pp (13.6 MeV) -0.93  0.21 0.043 0.0170.0090.039 A z pp (45 MeV) -1.57  0.23 0.079 0.0320.0180.073 A z p  (46 MeV) -3.34  0.93 -0.3400.1400.006-0.039-0.002 P  ( 18 F)1200±3860438534-44 A  ( 19 F)-740±190-94.234.1-1.1-4.5-0.1 133 Cs800±14060.7-15.83.40.41.06.1 205 Tl370±390-18.03.8-1.8-0.30.1-2.0 PNC observables and theoretical coefficients, decomposed into the weak coupling combinations. E. G. Adelberger, W. C. Haxton. Ann. Rev. Nucl. Part. Sci. 35 (1985) 501; S. A. Page, et. al. Phys. Rev. C35 (1987) 1119; J. Lang, et.al. Phys. Rev. C34 (1986) 1545; W. C. Haxton, et. al. Phys. Rev. Lett 86 (2001) 5247; W. M. Snow. J. Res. NIST 110 (2005) 189

11. 11 The PNC constraints best values W. C. Haxton et. al. Phys. Rev. Let. 86 (2001) 5347 18 F(1.081 MeV), P  : -1.0∙10 -7  f   1.2∙10 -7 11 5705944490  hhfP  In order to solve this problem, one needs more independent interpretable inexperiments.

12. 12 Experiments Experiment in progress at LANSCE: M. T. Gerike, J. D. Bowman, R. D. Carlini, T. E. Chupp, K. P. Coulter, M. Dabaghyan, S. J. Freedman, T. R. Gentile, G. L. Green, F. W. Hersman, T. Ino, S. Ishimoto, G. L. Jones, B. Lauss, M. B. Leuschner, B. Losowski, R. Mahurin, Y. Masuda, G. S. Mitchel, S. Muto, H. Nann, S. A. Page, S. I. Penttila, W. D. Ramsay, S. Santra, P.-N. Seo, E. I. Sharapov, T. B. Smith, W. M. Snow, W. S. Wilburn, V. Yuan, H. Zhu. J. Res. NIST 110 (2005) 195; J. Res. NIST 110 (2005) 215

13. 13 P-odd effects in extremely light nuclei Cluster and multiclaster schemes for 6,7 Li: n + {  d’}  {n,d’} + . Calculation has been performed in the framework of the three body pick-up reaction mechanism. N. N. Nesterov, I. S. Okunev. JETPh Let. 48 (1988): P-odd asymmetry in the 6 Li(n,  ) 3 H reaction with cold polarized neutrons: (with DDH best values), contribution from  -exchange ~75%  n  =760 b at E th

14. 14 P-odd effects in extremely light nuclei Expected value   = 1.1  10 -7 (DDH), contribution from  -exchange ~66%  n  =3940 b at E th V. A. Vesna, Yu. M. Gledenov, P. V. Lebedev-Stepanov, I. S. Okunev, A.V. Sinykov, Yu. M. Tchuvilsky, E. V. Shulgina.Phys. At. Nucl. 62 (1999) 522; S. Yu. Igashov, A. V. Sinykov, Yu. M. Tchuvilsky. In: Proc. ISINN-11. Dubna 2003, 34 The modern formalism of RGM was used on the solution of Schroedinger equation. P-odd asymmetry in the  -emission by the de-excitation of the 1st excited state of 7 Li for the reaction 10 B(n,  ) 7 Li* with polarized neutrons.

15. 15 Experimental investigations of the P-odd effects in light nuclei V. A. Vesna 1, Yu. M. Gledenov 2, V. V. Nesvizhevsky 3, A. K. Petukhov 3, P. V. Sedyshev 2, T. Soldner 3, E. V. Shulgina 1, O. Zimmer 4 1 Petersburg Nuclear Physics Institute of RAS, Gatchina, Russia. 2 Frank Laboratory of Neutron Physics, JINR, Dubna, Russia. 3 Institut Laue-Langevin, Grenoble, France. 4 Technische Universität, München, Germany VVR-M reactor in PNPI, Gatchina, Russia; vertical channel. PF1B instrument of the ILL reactor, Grenoble, France. Averaged neutron wavelength: n = 4.7 Å, Integrated neutron flux: F n ~ (2 – 5)∙10 10 s -1 Integral method of measurement; special experimental technique and data treatment

16. 16 6 Li(n,  ) 3 H experiment 1 exp. (2002): 18 days main run; polarizer: 10  5 cm 2 exp. (2005): 48 days main run; polarizer: 8  8 cm; 3 exp. (2006): 25 days, 0-exp.; polarizer: 8  8 cm ILL, Grenoble, France PF1B instrument [V. A. Vesna, et. al. JETP Lett 82 (2005) 519].

17. 17 View of the PF1B experimental area

18. 18 Experimental scheme     p n  n  n 123 4 5 1 – polarizer; 2 – resonance spin-flipper; 3 – ionization chamber; 4 – guiding field; 5 – beam-stop. p n - neutron momentum;  n - neutron spin. pnpn nn ptpt  Geometry of experiment:  n || P n || P t. The accuracy of the alignment:  < 10 -2. Spin-flipper state was changed every 1 - 2 s.

19. 19 Ionization chamber The detector is an assembly of ionization chambers placed in a cylindrical duralumin vessel. The entrance and exit 70  150 mm windows are zirconium foils of thickness 0.5 mm. [ Yu. M. Gledenov et. al. NIM A350 (1994) 517. ]

20. 20 Ionization chamber Detector includes 24 identical double ionization chambers.

21. 21 Ionization chamber Scheme of the double ionization chamber: H – high-voltage electrode; C – signal electrode; T – target electrode. Distances: TC=CH=10.5 mm The working gas: Ar, p=2 at. U T =U H =-375 V, U C =0 V (trough the preamplifier) Signal electrodes: fiberglass frame; gold-coated wires,  100 µm, step 4 mm. High voltage electrodes: fiberglass frame; beryllium bronze wires,  100 µm, step 2 mm. Target electrodes: aluminum frame, cassette.

22. 22 Ionization chamber

23. 23 Current method of the event detection F n (t) – neutron flux on the target; Number of charged particles in elementary solid angle: N(t)~ F n (t) (  /4  )(1+  cos  ); d  /d  =(  /4  )(1+  cos  ) – differential cross section. Energy of emitted particle: E=E(  ) – due to the finite thickness of target layer. Number of the electron-ion pairs, produced by a charged particle due to ionization: n pair = E(  )/ ,  - energy of pair creation; Number of the electron-ion pairs in sensitive volume of detector: Current in the detector circuit: w – drift velocity. [V. M. Lobashev. Phys. At. Nucl. 5 (1965) 957; V. M. Lobashev et. al Phys. Lett. (1967) 104; Yu. M. Gledenov et. al. NIM A350 (1994) 517. ]

24. 24 Current method of the event detection I +, I - - detector current at different directions of the neutron polarization - mean cosine.

25. 25 Targets  max The lithium targets are 450  g/cm 2 layers of LiF (the enrichment with 6 Li of 95 %) with size of 140х60 mm. 6 Li(n,  ) 3 H, Q=4.78 MeV: E t =2.73 MeV, E  =2.05 MeV. I t ~ (1+  cos  ), I  ~ (1-  cos  ) - in opposite phases. Lithium fluoride is evaporated onto 14  m aluminum foil and covered with the foil of the same thickness. Targets absorbed 60% of beam intensity  cos  = 0.75

26. 26 Ionization chamber PnPn nn Signal electrodes of all the “forward” sections as well as the signal electrodes of the “backward” sections were joined in to two separate lines – “forward” and “backward”, respectively. The detector was designed as a two-channel system. The signs of investigated P-odd effect in the detector channels was opposite at synchronous measurements.

27. 27 The electronics and data acquisition system Control computer ADC (ACL-8112pg) Counter-Timer (ACL 7120) Flipper control Interface controlling the integrator gates Interator Integrator D1 PA U U const U U c D2 Guiding field control

28. 28 Current signal preamplifier Feedback capacitance and resistance Input U const u PA switch Calibration signal input U const I det u +-+ I  U converter: U out = I det R fb See: V. A. Knyaz'kov., et. al. Nucl.Phys. A417 (1984) 209; Yu. M. Gledenov et. al. NIM A350 (1994) 517

29. 29 Integrator K7K7 K6K6 K 10 Input Output to ADC K 6, K 7 - switches are for the integration and reset of the integrator; K 10 – switch connects the integrator and the ADC See: V. A. Knyaz'kov., et. al. Nucl.Phys. A417 (1984) 209; Yu. M. Gledenov et. al. NIM A350 (1994) 517

30. 30 The electronics and data acquisition system Control computer ADC (ACL-8112pg) Counter-Timer (ACL 7120) Flipper control Interface controlling the integrator gates Interator Integrator D1 PA U U const U U c D2 Guiding field control All signals were measured with a programmable 12-bit ADC with 16 independent inputs in the structure of the multifunctional data acquisition card ACL- 8112pg ADLink Technology Inc. The timing diagram was generated using the programmable counter-timer card ACL-7120 ADLink Technology Inc. Accuracy of the integrator key control signals is 2∙10 -5. Accuracy of the flipper state control signal is 2.5∙10 -7. / U c < 10 -4

31. 31 Reactor power fluctuations f, Hz Power of the reactor neutron flux fluctuation as a function of frequency E. A. Garusov, et. al. Kernenergie 2 (1983) 68 Compensation of the reactor power fluctuations [ V. M. Lobashov, et. al. Nucl. Phys. A197 (1972) 241; V. A. Knyaz'kov., et. al. Nucl.Phys. A417 (1984) 209; Yu. M. Gledenov et. al. NIM A350 (1994) 517. ]

32. 32 Data acquisition procedure - Values are measuring synchronously for each detector channel. 4 sequence values are jointed with a + - - + pattern: - A single measurement The N sequence single measurements are joined into a series: N = 128. U c +, U c - - are recorded one time per series.

33. 33 Compensation of the reactor power fluctuations Synchronous values L – compensation coefficient Compensation coefficient is determined over a series meeting the requirement of minimal subtraction dispersion Compensation: (  f,b /  )  80.

34. 34 Suppression of the apparatus asymmetries Pn Pn nn B+B+ B-B- - different neutron polarization:  u f(b) = (u + - u - ) ; - compensation:  u = (  u f - L  u b ) ; - different guiding field directions:  =  (B+) -  (B-) Test of the system:  = (1.7  2.4)∙10 -10 Main sources of apparatus asymmetry: signal of the flipper control; signals in the ground circuits; scattering electromagnetic fields of the working facilities

35. 35 Suppression of the apparatus asymmetries

36. 36

37. 37 The left-right asymmetry: 6 Li(n,  ) 3 H :  lr = (1.06  0.04)∙10 -4

38. 38 The left-right asymmetry Pn Pn nn Pn Pn nn  lr = (4.9  1.9)∙10 -7

39. 39 Test of LR-asymmetry Pn Pn nn PnPn  t LR ~  [p n p t ]

40. 40 Constant components and LR-asymmetry vs. angle between neutron and proton momenta. , rad  t, 10 -8 ~ 0 -0.01 -0.015 -10.8  4.4 -9.9  4.1 -7.4  4.2 Averaged value -9.3  2.5 P-odd asymmetry coefficient vs. the angle between neutron and triton momenta Additional test of the LR-asymmetry  t PNC ~  p t  t LR ~  [p n p t ]

41. 41 Some results

42. 42 Some results

43. 43 0-experiment 1.Two-channel system. 2. Linear drift compensation. 3. Compensation of the reactor power fluctuations. 4. Reversal guiding neutron spin magnetic field at the detector.

44. 44 0-experiment

45. 45 0-experiment

46. 46 0-experiment 1. 8 Li,  -, E max = 16.0 MeV, T 1/2 = 0.84 s,  = -(0.08  0.01) 2. 20 F,  -, E max = 7.0 MeV, T 1/2 = 11.0 s,  - ? 3. 35 Cl(n,p) 35 S, E p = 0.6 MeV,  = -(1.5  0.34)·10 -4 4. Al, Ar, N: , , , p - ? All targets were covered with aluminum foils with the thickness of 20  m.  0 = -(0.0  0.5) 10 -8.

47. 47 Results P  PNC 00 PNPI0.66 -(5.4  6.0)∙10 -8 (2.0  1.7)·10 -8 ILL, PF1B0.66 -(8.1  3.9)∙10 -8 ILL, PF1B0.70 -(9.3  2.5)∙10 -8 ILL, PF1B0.70 (0.0  0.5)·10 -8 -(8.6  2.0)∙10 -8 (0.2  0.5)·10 -8

48. 48 10 B(n,  ) 7 Li*  7 Li+  experiment 1-polarizer; 2-adiabatic spin-flipper; 3,6-magneted plates of guide field; 4-lead collimator; 5-concrete wall; 7-lead shield, 8-B 4 C-shield; 9-Helmgoltz coils; 10- detectors; 11-sample; 12-Li beam stop. Detectors: NaJ(Tl)  200 mm  100 mm. Sample: 50 g of 10 B, 85%, size 160  180  5 mm, 14  m Al-foil. For the light detection the “Hamamatsu” photodiodes were used.

49. 49 10 B(n,  ) 7 Li*  7 Li+  experiment

50. 50 10 B(n,  ) 7 Li*  7 Li+  experiment Result of 2 previous runs:   = (5.1  3.8)  10 -8, “0-experiment”:  0 = -(0.7  3.7)  10 -8. 1 st Experiment (ILL, 2001): Main run:  = + (8.8  4.6)  10 -8 “0”-test:  0 = - (14.8  3.3)  10 -8 2 nd Experiment (ILL, 2002): Main run :  = - (11.0  6.6)  10 -8 “0”-test:  0 = - (0.7  3.7)  10 -8 Additional measurement:  (C)= (1.7  1.9)  10 -6  normalized:  sc = (2.4  2.7)  10 -11

51. 51 Results best values

52. 52 Summary 1. We have received nonzero result of the P-odd asymmetry of the triton emission from the 6 Li(n,  ) 3 H reaction with cold polarized neutrons. 2. An accuracy of our measurements is 2.1  10 -8. Such precision have not yet been achieved in neutron experiments. 3. The f  coupling constant extracted from the experimental data favors small value, close to that have been obtained in the 18 F measurements. 4. Low f  value means that still there is no detection of the neutral currents in nucleon- nucleon interactions at low energy. 5. The measurements of the P-odd asymmetry of  - quanta from the 10 B(n,  ) 7 Li*  7 Li+  will be continued. Next run will be September-November this year. 6. The joint analysis of the 6 Li and 10 B results allows one to extract the h  0 coupling constant and to obtain more strong restrictions on the f  costant.

53. 53 Thank you for your attention.

54. 54 Experiments at PF1B: the working gas – Ar; pressure – p = 2.4 atm in 1 st measurement p = 1.9 atm in 2 nd measurement Ionization operating mode

55. 55 Suppression of the apparatus asymmetries  u f (B+) = (u f+ +v f sf )-u f- = (u f+ - u f- )+v f sf  u b (B+) = (u b+ +v b sf )-u b- = -(u b+ - u b- )+v b sf  u(B+) = (u f+ - u f- ) + L(u b+ - u b- ) + (v f sf - Lv b sf )  (B+) =  PNC + (v f sf - Lv b sf )/U c  u f (B-) = (u f+ + v f sf ) - u f- = -(u f+ - u f- ) + v f sf  u b (B-) = (u b+ + v b sf ) - u b- = (u b+ - u b- ) + v b sf  u(B-) = -(u f+ + u f- ) ) - L(u b+ - u b- ) + (v f sf - Lv b sf )  (B-) = -  PNC + (v f sf - Lv b sf )/U c

56. 56 Test of the ionization chamber Output signal vs. the lithium shutter position Output signal vs. the reactor power U const = I det R fb PNPI, VVR-M reactor, vertical channel: F n ≈ 2∙10 10 s -1 A systematic investigation was carried out for the various gas pressure (0.15 – 4 atm) and various gas mixture (Ar, Ar + %CO 2 ).

57. 57

58. 58 -spin rotation Light quarks u, d, s.  C=0,  S=0,  C – Cabibbo angle, sin  C  0.22  T – amount of isospin change at transition

59. 59 NN electroweak interactions at low energy Weak current-current Hamiltonian: g,g´ - elektroweak coupling constants; J  W,Z – hadronic part of the charged and neutral currents; m W, m Z – intermediate vector boson masses; G – Fermi constant W±W± Z0Z0 JWJW JWJW JWJW JWJW JZJZ JZJZ JZJZ JZJZ gggg ~G low level limit