FLNP of JINR, Dubna, Russia Neutron gravity experiments and tests of the Weak Equivalence Principle A. Frank FLNP of JINR, Dubna, Russia ESS Science Symposium on Neutron Physics at Long Pulse Spallation Sources 25-27 March 2013 PSI 2010. October, 11-14, 2010
Outline Free Fall Universality tests (short review) Neutrons and gravity Status of new Neutron Gravity experiment Proposal of the future free fall experiment with UCN. A.Frank. nppatlps-2013, 27 March 2013 July
Free Fall Universality tests (short review) Neutrons and gravity Status of new Neutron Gravity experiment Proposal of the future free fall experiment with UCN. A.Frank. nppatlps-2013, 27 March 2013 July
A.Frank. nppatlps-2013, 27 March 2013 P.G. Roll, R. Krotkov, and R.H. Dicke, Ann. Phys. (N.Y.) 26, 442 (1964) S.Carusotto, V.Cavassinni, A.Mordacci et. al. Phys.Rev Lett. 69, 1722 (1992) S. Schlamminger, K.-Y. Choi, T. A. Wagner, et al. Phys.Rev Lett 100, 041101 (2008) S. Fray, C. A. Diez, T. W. Hänsch, and M. Weitz. arXiv:physics/0411052 v.2 (2005) J. G. Williams, S.G. Turyshev, and D. H. Boggs, Phys.Rev Lett 93, 261101 (2004) G. L. Smith, C. D. Hoyle, J. H. Gundlach, E. G. Adelberger, B. R. Heckel, and H. E. Swanson. Phys. Rev. Rev. D 61, (1999) 022001 A.Frank. nppatlps-2013, 27 March 2013
Free Fall Universality tests (short review) Neutrons and gravity Status of new Neutron Gravity experiment Proposal of the future free fall experiment with UCN. A.Frank. nppatlps-2013, 27 March 2013
A.Frank. nppatlps-2013, 27 March 2013 1. g =935 70cm/sec2 2. J.W.Dabbs,J.A.Harvey, D.Pava and H.Horstmann, 1965 g(002)=973.1 7.4cm/sec2 g(100)=975.1 3.1cm/sec2 gloc = 979.74cm/sec2 A.Frank. nppatlps-2013, 27 March 2013
A.Frank. nppatlps-2013, 27 March 2013 L.Koester, 1976 Knowing the neutron mass m and local free fall acceleration gloc one can obtain the effective scattering length beff Coherence length b was measured also in the neutron scattering experiment with Pb and Bi. Thus the equivalence factor was found 1- = 310-4 V.F.Sears,1982 J. Schmiedmayer, NIM A 284, (1989) 59 1- = 1.00011 0.00017 A.Frank. nppatlps-2013, 27 March 2013
Koester’s experiment and the problem of n-e scattering When the value of bcoh extracts from the total cross section data it is necessary to take into account the 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 bcoh the amplitude of n-e scattering must be known with precision of 1%. It is not evident that bne is known with such precision even now Schmiedmayer used statistically inconsistent data for n-e scattering A.Frank. nppatlps-2013, 27 March 2013
Koester’s experiment and effective potential What is a precision of the above equation for the effective potential U? V.F.Sears (1982); M. Warner, J.E Gubernatis. (1985) Lax, 1951 Theory: (estimation for lead at Vn 400 m/sec) – corrections of the order of 510-5 There are no any experiments for the test of theory with precision better than some percents A.Frank. nppatlps-2013, 27 March 2013
Neutron Interferometric Experiments (COW – type experiment) R.Colella, A,W.Overhauser and S.A. Werner (COW), 1975 The experimentally obtained values for the gravitationally induced phase factor 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. K.S.Litrell, B.E.Allman and S.A.Werner, 1997 A.Frank. nppatlps-2013, 27 March 2013
1- = (1±9)10-3 A.Frank. nppatlps-2013, 27 March 2013
Dubna-ILL-Kurchatov experiment of 2006 E0 E E E0 + mgH E0 –ħ1 +mgH H E0 –ħ2 +mgH g The idea was to compare the energy mgH with energy ħΩ A.I. Frank, P. Geltenbort, M. Jentschel,et al. JETP Letters, 86, 225 (2007) A.Frank. nppatlps-2013, 27 March 2013 12
Moving diffraction grating as a nonstationary device z y L – period of grating E 1 -1 2 -2 A.Frank. nppatlps-2013, 27 March 2013 13
Moving (rotating) diffraction grating as a nonstationary device UCN Monochromator Phase π -grating n L d E 1 -1 where N is number of groves N = 75398 A.Frank. nppatlps-2013, 27 March 2013 14
Fabry-Perot interferometers (Neutron Interference filters) as a spectrometric device Energy of the state 1 2 Substrate A.Frank. nppatlps-2013, 27 March 2013
Experimental results Bth = 0.304203 Bexp = 0.3037 ± 0.00065 A.I. Frank, P. Geltenbort, M. Jentschel,et al. JETP Letters, 86, 225 (2007) A.Frank. nppatlps-2013, 27 March 2013
Free Fall Universality tests (short review) Neutrons and gravity Status of new Neutron Gravity experiment Proposal of the future free fall experiment with UCN. A.Frank. nppatlps-2013, 27 March 2013
Comparing the energy mggnH with energy ħΩ as before Combination of Neutron Interference Filters with peculiar TOF spectrometry Flux modulation TOF base E1 Count-rate oscillations on a detector E2 E3 E1>E2>E3 A.Frank. nppatlps-2013, 27 March 2013 18
Comparing the energy mggnH with energy ħΩ as before Combination of Neutron Interference Filters with peculiar TOF spectrometry Flux modulation TOF base E1 Count-rate oscillations on a detector E2 E3 E1>E2>E3 Not sensitive to fluctuations of: Background Intensity Efficiency registration of neutrons A.Frank. nppatlps-2013, 27 March 2013 19
20 Experiment. Part I Calibration Modulation frequency 75Hz Monochromator Detector Calibration Variation of the monochromator vertical position leads to changing of the UCN energy, time of flight and total phase of the count rate oscillation A.Frank. nppatlps-2013, 27 March 2013 20
Experiment. Part II (idea) Detector Monochromator Detector Monochromator grating grating The count rate oscillation phase of the UCN which energy shifted by rotating grating must be compared with the calibration curv A.Frank. nppatlps-2013, 27 March 2013 21
Experiment. Part II (idea) Detector Monochromator Detector Monochromator grating grating The count rate oscillation phase of the UCN which energy shifted by rotating grating must be compared with the calibration curv Unfortunately -1 order of diffravtion is accopanied by the +1 and diffraction. orders of higher orders A.Frank. nppatlps-2013, 27 March 2013 22
Detector Monochromator grating Wide analyzer Using special 9-layers filter with wide transmission band it is possible to select the UCN of -1 diffraction order wide A.Frank. nppatlps-2013, 27 March 2013 23
Experiment. Part II (idea) Detector Monochromator grating Wide analyzer ΔH The count rate oscillation phase of the UCN which energy shifted by the grating rotating with different frequency must be compared with the calibration curv A.Frank. nppatlps-2013, 27 March 2013 24
New gravitational spectrometer of UCN. A.Frank. nppatlps-2013, 27 March 2013
Chopper-modulator Stability of the modulation frequency is better than 10-4 A.Frank. nppatlps-2013, 27 March 2013 26 26 26
Grating manufactured by the Qudos technology LTD (2012) A.Frank. nppatlps-2013, 27 March 2013
Experiment of 2011. A.Frank. nppatlps-2013, 27 March 2013 Oscillation of the count rate. Modulation frequency 75Hz, neutron time of flight 150 ms Dependence of the count rate oscillation phase on the modulation frequency A.Frank. nppatlps-2013, 27 March 2013
29 Experiment of 2011. A.Frank. nppatlps-2013, 27 March 2013 Detector Monochromator grating Wide analyzer A.Frank. nppatlps-2013, 27 March 2013 29
Experiment of 2011. Detector Monochromator grating Wide analyzer Rate of the collection of accuracy 1.5×10-2 per day A.Frank. nppatlps-2013, 27 March 2013 30
Experiment of 2012. A.Frank. nppatlps-2013, 27 March 2013 Amplitude of the count rate oscillation in dependence of position of analyzer. Geometry of calibration. Count rate in the geometry of calibration with rotating chopper- modulator Scanning curve of -1 diffraction order with the grating spinning at 6300 rpm.. A.Frank. nppatlps-2013, 27 March 2013
Experiment of 2012. A.Frank. nppatlps-2013, 27 March 2013 Geometry of calibration Oscillation of the count rate. Modulation frequency 84Hz, statistic collection time 3200 s, error for the phase measurement 0.01rad, total phase about 80 radian A.Frank. nppatlps-2013, 27 March 2013
Experiment of 2012. A.Frank. nppatlps-2013, 27 March 2013
Experiment of 2012. A.Frank. nppatlps-2013, 27 March 2013
The main results of 2012 The full scale test measurements with new spectrometer was performed. 2. The rate of the collection of statistical accuracy, was obtained as 5×10-3 per day. That is enough to collect statistical accuracy of the order of 5×10-4 during two cycle of statistic collection at PF2 source. 3. The systematic effect due to admixture of zero order to the spectrum of minus first order was found. This problem may be probably solved by manufacturing of the grating with a) smaller inner diameter, what as we hope will decrease the intensity of UCN bypasses the grating b) with larger space frequency what will increase separation between the zero (if it will be) and minus first orders. A.Frank. nppatlps-2013, 27 March 2013
The possible improvement The grating with larger number of groves (94 500 instead of 75398) will be used. That will increase the energy transform The monochromator with position of transmission line at 95nev will be used instead of monochromator with 105 nev line. The TOF base will be increased from to 70 to 90 cm All that will double the collection rate of the statistical accuracy. A.Frank. nppatlps-2013, 27 March 2013
Free Fall Universality tests (short review) Neutrons and gravity Status of new Neutron Gravity experiment Proposal of the future free fall experiment with UCN. A.Frank. nppatlps-2013, 27 March 2013
What was measured in the previous experiments Koester m is known tabular data of neutron mass ILL-Dubna-Kurchatov inst. It is seems very attractive to perform experiment where mi/mg will be measured without any additional information The best is the direct measurement of gn A.Frank. nppatlps-2013, 27 March 2013
Neutron fountain for the measuring of gn For the measure of time it was proposed to use Yu.N.Pokotilovsky, 1994 We propose to modify the idea of Yu. P 1. Interference filter with number of lines 1. Interference filter with single line 2. Simple chopper- modulator Instead of pseudo-random chopper 2. Correlation time of flight spectroscopy with pseudo-random chopper Detector 3. Only the phase of the intensity oscillation will be measured. 3. Because the energy of the lines is unknown, it was proposed to vary height of detector for calculation of g. A.Frank. nppatlps-2013, 27 March 2013
Neutron fountain for the measuring of gn Simple chopper- modulator Instead of pseudo-random chopper Only the phase of the intensity oscillation will be measured. Dependence of phase on the height of monochromator gives the value of g Detector Alternative possibility: instead of variation of the height of monochromator it is possible to shift energy by rotating grating Vertical mirror may be added A.Frank. nppatlps-2013, 27 March 2013
Neutron fountain for the measuring of gn Simple chopper- modulator Instead of pseudo-random chopper Solid angle Only the phase of the intensity oscillation will be measured. Dependence of phase on the height of monochromator gives the value of g Detector Vertical mirror may be added That will give a gain in the intensity of the order of magnitude A.Frank. nppatlps-2013, 27 March 2013
Main advantages of this approach is that absolute measurements are needed only for Frequency of the beam modulation The value H of the variation in the position of monochromator Or (alternatively) the frequency of quantum modulation due to diffraction by a moving grating Estimation shows that precision of the order 10-5 may be achieved at PF2 A.Frank. nppatlps-2013, 27 March 2013
A. I. Frank, S. Goryunov, G. V. Kulin, D. Kustov A.I.Frank, S.Goryunov, G.V.Kulin, D.Kustov*) Frank Laboratory of Neutron Physics, JINR, Dubna, Russia *) Institute of Nuclear Research, Kiev, Ukraine P. Geltenbort, M.Jentschel ILL, Grenoble, France A.N.Strepetov NRC “Kurchatov Institute”, Moscow, Russia.
Thank you for your attention!
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Two aspects of the Universality of Free Fall (UFF) experimental tests Tests of the equivalence principle Probes for the new interactions that violate the UFF A.Frank. nppatlps-2013, 27 March 2013