Pub Date : 2014-06-23DOI: 10.1109/EFTF.2014.7331415
Haoshen Zhu, Cheng Tu, Joshua E-Y Lee, L. Rufer
In this paper, we report the manipulation of nonlinear behavior in a bulk-mode micromechanical resonator for the first time. N-doped single-crystal-silicon (SCS) resonators of the same dimensions but different crystal orientations (<;100> and <;110>) were electrically characterized using capacitive drive and piezoresistive sense. Notably, reversed nonlinear behavior (from spring softening to hardening) was observed in the <;100> devices as a result of increasing the bias dc current. We have found that the energy storage capability of the resonator has been enlarged by over 10 times at the transition from spring softening to hardening. This newfound capability to electronically "cancel nonlinearity" could be conveniently applied to improve the phase noise (PN) performance of MEMS oscillators.
{"title":"Active electronic cancellation of nonlinearity in a High-Q longitudinal-mode silicon resonator by current biasing","authors":"Haoshen Zhu, Cheng Tu, Joshua E-Y Lee, L. Rufer","doi":"10.1109/EFTF.2014.7331415","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331415","url":null,"abstract":"In this paper, we report the manipulation of nonlinear behavior in a bulk-mode micromechanical resonator for the first time. N-doped single-crystal-silicon (SCS) resonators of the same dimensions but different crystal orientations (<;100> and <;110>) were electrically characterized using capacitive drive and piezoresistive sense. Notably, reversed nonlinear behavior (from spring softening to hardening) was observed in the <;100> devices as a result of increasing the bias dc current. We have found that the energy storage capability of the resonator has been enlarged by over 10 times at the transition from spring softening to hardening. This newfound capability to electronically \"cancel nonlinearity\" could be conveniently applied to improve the phase noise (PN) performance of MEMS oscillators.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"98 9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128007107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-23DOI: 10.1109/EFTF.2014.7331456
M. Aleynikov, A. Boyko
It is well known one of the way to ensure a presence only operating atoms in the storage bulb is a method associated with Majorana transition. To implement this method a magnetic field created by two Pseudo-Helmholtz coils, that are placed at the region between state selection magnets, is used. With this shape of the total field in mind it is extremely important to know transverse (in regard to the atomic beam axis) coordinates of the region where the field change its sign, and the magnitude of the field gradient in this region. In the paper the dependences of H-maser's selection state system quality factor on the value of the magnetic field gradient and on the transverse coordinate of its zero value are calculated and examined. The extreme values of this parameters when a single-state selection does not work are defined. Moreover, the hydrogen beam intensity is a intrinsic value for Power Spectral Density of the H-maser's output signal. In the second part of the paper a principal circuit for using the output signal to create interrogation waveform (a synthesizer) for Rb atomic fountain is discussed, quantity of the Dick effect is calculated. It is shown achievable fountain's stability due to a technical noise of such RF synthesizer can reach 6·10-14 for 1 sec.
{"title":"On the single-state selection for H-maser and its signal application for fountain atomic standard","authors":"M. Aleynikov, A. Boyko","doi":"10.1109/EFTF.2014.7331456","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331456","url":null,"abstract":"It is well known one of the way to ensure a presence only operating atoms in the storage bulb is a method associated with Majorana transition. To implement this method a magnetic field created by two Pseudo-Helmholtz coils, that are placed at the region between state selection magnets, is used. With this shape of the total field in mind it is extremely important to know transverse (in regard to the atomic beam axis) coordinates of the region where the field change its sign, and the magnitude of the field gradient in this region. In the paper the dependences of H-maser's selection state system quality factor on the value of the magnetic field gradient and on the transverse coordinate of its zero value are calculated and examined. The extreme values of this parameters when a single-state selection does not work are defined. Moreover, the hydrogen beam intensity is a intrinsic value for Power Spectral Density of the H-maser's output signal. In the second part of the paper a principal circuit for using the output signal to create interrogation waveform (a synthesizer) for Rb atomic fountain is discussed, quantity of the Dick effect is calculated. It is shown achievable fountain's stability due to a technical noise of such RF synthesizer can reach 6·10-14 for 1 sec.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127995333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-23DOI: 10.1109/EFTF.2014.7331419
S. Galliou, P. Abbé, R. Bourquin, M. Goryachev, M. Tobar, E. Ivanov
It has been shown recently that premium grade quartz crystal resonators can exhibit outstanding quality-factors, Q, greater than 1 billion at liquid helium temperatures. It is demonstrated that at low temperatures interaction between acoustic and thermal phonons is governed by the Landau-Rumer theory predicting Q = const scaling law. This regime is distinct from the known Akhieser regime giving Q × f = const typically observed at room temperature. As a consequence, at low temperatures, the intrinsic Q-factor is independent of the resonant frequency making it advantageous to operate on higher overtones than the usual third or fifth overtones. Nevertheless, other loss mechanisms, such as surface or bulk scattering, can limit resonator performance, as discussed in the paper. In addition, experiment also shows that the frequency flicker noise of acoustic devices is inversely proportional to Qn, where n is close to 4, at the corresponding frequency. It emerges from both previous points, i.e. the improvement of Q-factors at low temperature in one hand and noise related to the Q-factor in the other hand, that high frequency stabilities should be expected from quartz resonator-based frequency sources operating at cryogenic temperatures. Noise measurements of resonators cooled by means of a pulse-tube cryogenerator, have then been performed. Power spectral densities of fractional frequency in the order of Sy(f = 1Hz) = 1 10-28 at 4 K have been achieved, that is to say two orders of magnitude lower than values already published. Resulting noise are described, and further promising applications are discussed.
{"title":"Properties related to Q-factors and noise of quartz resonator-based systems at 4K","authors":"S. Galliou, P. Abbé, R. Bourquin, M. Goryachev, M. Tobar, E. Ivanov","doi":"10.1109/EFTF.2014.7331419","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331419","url":null,"abstract":"It has been shown recently that premium grade quartz crystal resonators can exhibit outstanding quality-factors, Q, greater than 1 billion at liquid helium temperatures. It is demonstrated that at low temperatures interaction between acoustic and thermal phonons is governed by the Landau-Rumer theory predicting Q = const scaling law. This regime is distinct from the known Akhieser regime giving Q × f = const typically observed at room temperature. As a consequence, at low temperatures, the intrinsic Q-factor is independent of the resonant frequency making it advantageous to operate on higher overtones than the usual third or fifth overtones. Nevertheless, other loss mechanisms, such as surface or bulk scattering, can limit resonator performance, as discussed in the paper. In addition, experiment also shows that the frequency flicker noise of acoustic devices is inversely proportional to Qn, where n is close to 4, at the corresponding frequency. It emerges from both previous points, i.e. the improvement of Q-factors at low temperature in one hand and noise related to the Q-factor in the other hand, that high frequency stabilities should be expected from quartz resonator-based frequency sources operating at cryogenic temperatures. Noise measurements of resonators cooled by means of a pulse-tube cryogenerator, have then been performed. Power spectral densities of fractional frequency in the order of Sy(f = 1Hz) = 1 10-28 at 4 K have been achieved, that is to say two orders of magnitude lower than values already published. Resulting noise are described, and further promising applications are discussed.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131804086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-23DOI: 10.1109/EFTF.2014.7331455
A. Baranov, S. Ermak, V. Semenov
The results of analytical studies of the Light shift effect in the end resonance regime are presented. When linear polarized pumping is employed significantly smaller frequency shift (2 orders of magnitude less) can be obtained in comparison to circular polarized light. Yet, the results of diagonal elements of the density matrix calculations show that such pumping mode leads to 2-3 times atoms polarization loses on working transitions.
{"title":"The light and orientation end resonance frequency shifts in alkaline atoms vapors","authors":"A. Baranov, S. Ermak, V. Semenov","doi":"10.1109/EFTF.2014.7331455","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331455","url":null,"abstract":"The results of analytical studies of the Light shift effect in the end resonance regime are presented. When linear polarized pumping is employed significantly smaller frequency shift (2 orders of magnitude less) can be obtained in comparison to circular polarized light. Yet, the results of diagonal elements of the density matrix calculations show that such pumping mode leads to 2-3 times atoms polarization loses on working transitions.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131951723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-23DOI: 10.1109/EFTF.2014.7331497
M. Lipinski, P. Krehlik, L. Sliwczynski, L. Buczek, W. Wszolek
The phenomenon of some special low frequency acoustic-band optical phase-noise may occur in the field depleted fibers. Because this kind of noise may disturb the precise Time&Frequency Fiber-Optic transfer, an arrangement to do some immunity tests of the solutions applied seems to be needed. In the paper first the idea of testbed in which the mechanically induced acoustic-band optical phase noise-substitute is described and its own features and measured parameters are presented. The noise-substitute harmonic signal is generated by use of the specialized Bruel&Kjaer vibration exciter longitudionally stretching the fiber. In the second part of paper the first experimental research results on the T&F transfer OSTT-2 system's resistance to the acoustic-band noise are presented.
{"title":"Testbed for measuring of the effect of fiber acoustic-band phase noise on the T&F transfer stability","authors":"M. Lipinski, P. Krehlik, L. Sliwczynski, L. Buczek, W. Wszolek","doi":"10.1109/EFTF.2014.7331497","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331497","url":null,"abstract":"The phenomenon of some special low frequency acoustic-band optical phase-noise may occur in the field depleted fibers. Because this kind of noise may disturb the precise Time&Frequency Fiber-Optic transfer, an arrangement to do some immunity tests of the solutions applied seems to be needed. In the paper first the idea of testbed in which the mechanically induced acoustic-band optical phase noise-substitute is described and its own features and measured parameters are presented. The noise-substitute harmonic signal is generated by use of the specialized Bruel&Kjaer vibration exciter longitudionally stretching the fiber. In the second part of paper the first experimental research results on the T&F transfer OSTT-2 system's resistance to the acoustic-band noise are presented.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122169267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-23DOI: 10.1109/EFTF.2014.7331495
L. Buczek
This paper describes the concept of differential wavelength stabilization of the semiconductor lasers for fiber time and frequency transfer system. This concept based on coherent detection and down-conversion, exploiting high-speed photodiode and frequency prescaler.
{"title":"The concept of differential wavelength stabilization of the semiconductor lasers for time and frequency transfer system","authors":"L. Buczek","doi":"10.1109/EFTF.2014.7331495","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331495","url":null,"abstract":"This paper describes the concept of differential wavelength stabilization of the semiconductor lasers for fiber time and frequency transfer system. This concept based on coherent detection and down-conversion, exploiting high-speed photodiode and frequency prescaler.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"100 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122973107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-23DOI: 10.1109/EFTF.2014.7331501
C. Calosso, E. Bertacco, D. Calonico, C. Clivati, G. Costanzo, M. Frittelli, F. Levi, S. Micalizio, A. Mura, A. Godone
We performed a two-way remote optical phase comparison on optical fiber. Two optical frequency signals were launched in opposite directions in an optical fiber and their phases were simultaneously measured at the other end. In this technique, the fiber noise is passively cancelled, and we compared two optical frequencies at the ultimate 10-21 stability level. The experiment was performed on a 47km fiber that is part of the metropolitan network for Internet traffic. The technique relies on the synchronous measurement of the optical phases at the two ends of the link, that is here performed by digital electronics. This scheme offers some advantages with respect to active noise cancellation schemes, as the light travels only once in the fiber.
{"title":"Digital implementation of a two-way coherent phase transfer over optical fiber for remote clocks comparisons","authors":"C. Calosso, E. Bertacco, D. Calonico, C. Clivati, G. Costanzo, M. Frittelli, F. Levi, S. Micalizio, A. Mura, A. Godone","doi":"10.1109/EFTF.2014.7331501","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331501","url":null,"abstract":"We performed a two-way remote optical phase comparison on optical fiber. Two optical frequency signals were launched in opposite directions in an optical fiber and their phases were simultaneously measured at the other end. In this technique, the fiber noise is passively cancelled, and we compared two optical frequencies at the ultimate 10-21 stability level. The experiment was performed on a 47km fiber that is part of the metropolitan network for Internet traffic. The technique relies on the synchronous measurement of the optical phases at the two ends of the link, that is here performed by digital electronics. This scheme offers some advantages with respect to active noise cancellation schemes, as the light travels only once in the fiber.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123729808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-23DOI: 10.1109/EFTF.2014.7331469
B. Argence, B. Chanteau, O. Lopez, C. Chardonnet, C. Daussy, B. Darquié, A. Amy-Klein, D. Nicolodi, M. Abgrall, Y. Le Coq
We present a frequency chain which enables to transfer coherently the stability and the accuracy of an ultrastable laser emitting at 1.54 μm to the mid-infrared region. It includes an optical frequency comb and an ultrastable 1.54 μm frequency signal, referenced to primary standards and transferred from LNE-SYRTE to LPL through an optical link. This system gives us the ability to transfer frequency stability in the range of 10-15 and accuracy in the range of 10-14 from 1.54 μm to a wide spectral range in the mid-infrared domain. With this set-up, we stabilized a Quantum Cascade Laser emitting at 10.3 μm at an unprecedented Hz-level.
{"title":"Quantum cascade laser at Hz-level by use of a frequency comb and an optical link","authors":"B. Argence, B. Chanteau, O. Lopez, C. Chardonnet, C. Daussy, B. Darquié, A. Amy-Klein, D. Nicolodi, M. Abgrall, Y. Le Coq","doi":"10.1109/EFTF.2014.7331469","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331469","url":null,"abstract":"We present a frequency chain which enables to transfer coherently the stability and the accuracy of an ultrastable laser emitting at 1.54 μm to the mid-infrared region. It includes an optical frequency comb and an ultrastable 1.54 μm frequency signal, referenced to primary standards and transferred from LNE-SYRTE to LPL through an optical link. This system gives us the ability to transfer frequency stability in the range of 10-15 and accuracy in the range of 10-14 from 1.54 μm to a wide spectral range in the mid-infrared domain. With this set-up, we stabilized a Quantum Cascade Laser emitting at 10.3 μm at an unprecedented Hz-level.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"44 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116133405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-23DOI: 10.1109/EFTF.2014.7331503
J. Kołodziej, P. Krehlik, L. Sliwczynski, W. Slowik, P. Kalabiński
In the paper we present analytical and simulation methods of phase noise analysing. It must be pointed out that the models of device used in an electrical circuit simulators (eg. SPICE), are not suitable for a fiber optics modelling, so the structural macro model covered exact defined parameters (phase noise, power fluctuating, etc.) was designed. Presented approach allows finding an optimal system parameters (mainly a transfer function of the feedback loop) that minimize induced phase noise by mechanical vibrations in fibers.
{"title":"Noise performance optimization of time and frequency dissemination system in presence of fiber mechanical vibrations","authors":"J. Kołodziej, P. Krehlik, L. Sliwczynski, W. Slowik, P. Kalabiński","doi":"10.1109/EFTF.2014.7331503","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331503","url":null,"abstract":"In the paper we present analytical and simulation methods of phase noise analysing. It must be pointed out that the models of device used in an electrical circuit simulators (eg. SPICE), are not suitable for a fiber optics modelling, so the structural macro model covered exact defined parameters (phase noise, power fluctuating, etc.) was designed. Presented approach allows finding an optimal system parameters (mainly a transfer function of the feedback loop) that minimize induced phase noise by mechanical vibrations in fibers.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125455422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-06-23DOI: 10.1109/EFTF.2014.7331434
M. Laas-Bourez, C. Courde, E. Samain, J. Oneto, D. Rovera, J. Achkar, P. Uhrich, P. Guillemot
Three independent time transfer techniques are in operation in Observatoire de la Côte d'Azur (OCA): GPS, TWSTFT and T2L2. In Autumn 2013, a GPS receiver relative calibration campaign has been carried out. The result of this campaign, primarily intended to compare GPS with T2L2, have allowed the calibration of the TWSTFT link between OCA and OP. We computed for OCA the value of CALR = 7111.9 ns, with an uncertainty u = 2.8 ns at k = 2. From this calibration we caracterise the others links with the triangle closure technique.
{"title":"Calibration of the TWSTFT link between OCA and OP using a GPS link calibration","authors":"M. Laas-Bourez, C. Courde, E. Samain, J. Oneto, D. Rovera, J. Achkar, P. Uhrich, P. Guillemot","doi":"10.1109/EFTF.2014.7331434","DOIUrl":"https://doi.org/10.1109/EFTF.2014.7331434","url":null,"abstract":"Three independent time transfer techniques are in operation in Observatoire de la Côte d'Azur (OCA): GPS, TWSTFT and T2L2. In Autumn 2013, a GPS receiver relative calibration campaign has been carried out. The result of this campaign, primarily intended to compare GPS with T2L2, have allowed the calibration of the TWSTFT link between OCA and OP. We computed for OCA the value of CALR = 7111.9 ns, with an uncertainty u = 2.8 ns at k = 2. From this calibration we caracterise the others links with the triangle closure technique.","PeriodicalId":129873,"journal":{"name":"2014 European Frequency and Time Forum (EFTF)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127607894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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