المؤلفون: Armano, M, Audley, H, Baird, J, Binetruy, P, Born, M, Bortoluzzi, D, Castelli, E, Cavalleri, A, Cesarini, A, Cruise, A M, Danzmann, K, Silva, M de Deus, Diepholz, I, Dixon, G, Dolesi, R, Ferraioli, L, Ferroni, V, Fitzsimons, E D, Freschi, M, Gesa, L, Giardini, D, Gibert, F, Giusteri, R, Grimani, C, Grzymisch, J, Harrison, I, Hartig, M-S, Heinzel, G, Hewitson, M, Hollington, D, Hoyland, D, Hueller, M, Inchauspé, H, Jennrich, O, Jetzer, P, Johann, U, Johlander, B, Karnesis, N, Kaune, B, Killow, C J, Korsakova, N, Lobo, J A, López-Zaragoza, J P, Maarschalkerweerd, R, Mance, D, Martín, V, Martin-Polo, L, Martin-Porqueras, F, Martino, J, McNamara, P W, Mendes, J, Mendes, L, Meshksar, N, Nofrarias, M, Paczkowski, S, Perreur-Lloyd, M, Petiteau, A, Plagnol, E, Ramos-Castro, J, Reiche, J, Rivas, F, Robertson, D I, Russano, G, Sanjuan, J, Slutsky, J, Sopuerta, C F, Sumner, T, Texier, D, Thorpe, J I, Vetrugno, D, Vitale, S, Wanner, G, Ward, H, Wass, P J, Weber, W J, Wissel, L, Wittchen, A, Zweifel, P

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics

الوصف: The tilt-to-length coupling during the LISA Pathfinder mission has been numerically and analytically modeled for particular timespans. In this work, we investigate the long-term stability of the coupling coefficients of this noise. We show that they drifted slowly (by 1\,$\mu$m/rad and 6$\times10^{-6}$ in 100 days) and strongly correlated to temperature changes within the satellite (8\,$\mu$m/rad/K and 30$\times10^{-6}$/K). Based on analytical TTL coupling models, we attribute the temperature-driven coupling changes to rotations of the test masses and small distortions in the optical setup. Particularly, we show that LISA Pathfinder's optical baseplate was bent during the cooldown experiment, which started in late 2016 and lasted several months.

URL الوصول: http://arxiv.org/abs/2407.05852

المؤلفون: Armano, M, Audley, H, Baird, J, Binetruy, P, Born, M, Bortoluzzi, D, Castelli, E, Cavalleri, A, Cesarini, A, Cruise, A M, Danzmann, K, Silva, M De Deus, Diepholz, I, Dixon, G, Dolesi, R, Ferraioli, L, Ferroni, V, Fitzsimons, E D, Freschi, M, Gesa, L, Giardini, D, Gibert, F, Giusteri, R, Grimani, C, Grzymisch, J, Harrison, I, Hartig, M S, Heinzel, G, Hewitson, M, Hollington, D, Hoyland, D, Hueller, M, Inchauspé, H, Jennrich, O, Jetzer, P, Karnesis, N, Kaune, B, Korsakova, N, Killow, C J, Liu, L, Lobo, J A, López-Zaragoza, J P, Maarschalkerweerd, R, Mance, D, Martín, V, Martino, J, Martin-Polo, L, Martin-Porqueras, F, McNamara, P W, Mendes, J, Mendes, L, Meshksar, N, Nofrarias, M, Paczkowski, S, Perreur-Lloyd, M, Petiteau, A, Pivato, P, Plagnol, E, Ramos-Castro, J, Reiche, J, Rivas, F, Robertson, D I, Russano, G, Serrano, D, Slutsky, J, Sopuerta, C F, Sumner, T, Texier, D, Thorpe, J I, Vetrugno, D, Vitale, S, Wanner, G, Ward, H, Wass, P, Weber, W J, Wissel, L, Wittchen, A, Zweifel, P

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics, General Relativity and Quantum Cosmology

الوصف: A precise characterization of the magnetic properties of LISA Pathfinder free falling test-masses is of special interest for future gravitational wave observatory in space. Magnetic forces have an important impact on the instrument sensitivity in the low frequency regime below the millihertz. In this paper we report on the magnetic injection experiments performed throughout LISA Pathfinder operations. We show how these experiments allowed a high precision estimate of the instrument magnetic parameters. The remanent magnetic moment was found to have a modulus of $(0.245\pm0.081)\,\rm{nAm}^2$, the x-component of the background magnetic field within the test masses position was measured to be $(414 \pm 74)$ nT and its gradient had a value of $(-7.4\pm 2.1)\,\mu$T/m. Finally, we also measured the test mass magnetic susceptibility to be $(-3.35\pm0.15)\times$10$^{-5}$ in the low frequency regime. All results are in agreement with on-ground estimates.

URL الوصول: http://arxiv.org/abs/2407.04431

المؤلفون: Armano, M, Audley, H, Baird, J, Binetruy, P, Born, M, Bortoluzzi, D, Castelli, E, Cavalleri, A, Cesarini, A, Cruise, A M, Danzmann, K, Silva, M De Deus, Diepholz, I, Dixon, G, Dolesi, R, Ferraioli, L, Ferroni, V, Fitzsimons, E D, Freschi, M, Gesa, L, Giardini, D, Gibert, F, Giusteri, R, Grimani, C, Grzymisch, J, Harrison, I, Hartig, M S, Heinzel, G, Hewitson, M, Hollington, D, Hoyland, D, Hueller, M, Inchauspé, H, Jennrich, O, Jetzer, P, Karnesis, N, Kaune, B, Korsakova, N, Killow, C J, Liu, L, Lobo, J A, López-Zaragoza, J P, Maarschalkerweerd, R, Mance, D, Martín, V, Martino, J, Martin-Polo, L, Martin-Porqueras, F, McNamara, P W, Mendes, J, Mendes, L, Meshksar, N, Nofrarias, M, Paczkowski, S, Perreur-Lloyd, M, Petiteau, A, Pivato, P, Plagnol, E, Ramos-Castro, J, Reiche, J, Rivas, F, Robertson, D I, Russano, G, Serrano, D, Slutsky, J, Sopuerta, C F, Sumner, T, Texier, D, Thorpe, J I, Vetrugno, D, Vitale, S, Wanner, G, Ward, H, Wass, P, Weber, W J, Wissel, L, Wittchen, A, Zweifel, P

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics, General Relativity and Quantum Cosmology

الوصف: LISA Pathfinder was a mission designed to test key technologies required for gravitational wave detection in space. Magnetically driven forces play a key role in the instrument sensitivity in the low-frequency regime, which corresponds to the measurement band of interest for future space-borne gravitational wave observatories. Magnetic-induced forces couple to the test mass motion, introducing a contribution to the relative acceleration noise between the free falling test masses. In this Letter we present the first complete estimate of this term of the instrument performance model. Our results set the magnetic-induced acceleration noise during the February 2017 noise run of $\rm 0.25_{-0.08}^{+0.15}\,fm\,s^{-2}/\sqrt{Hz}$ at 1 mHz and $\rm 1.01_{-0.24}^{+0.73}\, fm\,s^{-2}/\sqrt{Hz}$ at 0.1 mHz. We also discuss how the non-stationarities of the interplanetary magnetic field can affect these values during extreme space weather conditions.

URL الوصول: http://arxiv.org/abs/2407.04427

المؤلفون: Armano, M., Audley, H., Baird, J., Binetruy, P., Born, M., Bortoluzzi, D., Castelli, E., Cavalleri, A., Cesarini, A., Chiavegato, V., Cruise, A. M., Bosco, D. Dal, Danzmann, K., Silva, M. De Deus, Diepholz, I., Dixon, G., Dolesi, R., Ferraioli, L., Ferroni, V., Fitzsimons, E. D., Freschi, M., Gesa, L., Giardini, D., Gibert, F., Giusteri, R., Grimani, C., Grzymisch, J., Harrison, I., Hartig, M. S., Heinzel, G., Hewitson, M., Hollington, D., Hoyland, D., Hueller, M., Inchauspé, H., Jennrich, O., Jetzer, P., Johlander, B., Karnesis, N., Kaune, B., Korsakova, N., Killow, C. J., Lobo, J. A., Lopez-Zaragoza, J. P., Maarschalkerweerd, R., Mance, D., Martın, V., Martin-Polo, L., Martin-Porqueras, F., Martino, J., McNamara, P. W., Mendes, J., Mendes, L., Meshksar, N., Nofrarias, M., Paczkowski, S., Perreur-Lloyd, M., Petiteau, A., Plagnol, E., Ramos-Castro, J., Reiche, J., Rivas, F., Robertson, D. I., Russano, G., Sala, L., Slutsky, J., Sopuerta, C. F., Sumner, T., Texier, D., Thorpe, J. I., Vetrugno, D., Vitale, S., Wanner, G., Ward, H., Wass, P., Weber, W. J., Wissel, L., Wittchen, A., Zanoni, C., Zweifel, P.

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics

الوصف: We present an in-depth analysis of the LISA Pathfinder differential acceleration performance over the entire course of its science operations, spanning approximately 500 days. We find that: 1) the evolution of the Brownian noise that dominates the acceleration amplitude spectral density (ASD), for frequencies $f\gtrsim 1\,\text{mHz}$, is consistent with the decaying pressure due to the outgassing of a single gaseous species. 2) between $f=36\,\mu\text{Hz}$ and $1\,\text{mHz}$, the acceleration ASD shows a $1/f$ tail in excess of the Brownian noise of almost constant amplitude, with $\simeq 20\%$ fluctuations over a period of a few days, with no particular time pattern over the course of the mission; 3) at the lowest considered frequency of $f=18\,\mu\text{Hz}$, the ASD significantly deviates from the $1/f$ behavior, because of temperature fluctuations that appear to modulate a quasi-static pressure gradient, sustained by the asymmetries of the outgassing pattern. We also present the results of a projection of the observed acceleration noise on the potential sources for which we had either a direct correlation measurement, or a quantitative estimate from dedicated experiments. These sources account for approximately $40\%$ of the noise power in the $1/f$ tail. Finally, we analyze the possible sources of the remaining unexplained fraction, and identify the possible measures that may be taken to keep those under control in LISA.
Comment: Accepted for publication in Phys.Rev.D

URL الوصول: http://arxiv.org/abs/2405.05207

المؤلفون: Armano, M, Audley, H, Baird, J, Bassan, M, Binetruy, P, Born, M, Bortoluzzi, D, Castelli, E, Cavalleri, A, Cesarini, A, Chiavegato, V, Cruise, A M, Bosco, D Dal, Danzmann, K, Silva, M De Deus, De Rosa, R, Di Fiore, L, Diepholz, I, Dixon, G, Dolesi, R, Ferroni, L Ferraioli V, Fitzsimons, E D, Freschi, M, Gesa, L, Giardini, D, Gibert, F, Giusteri, R, Grado, A, Grimani, C, Grzymisch, J, Harrison, I, Hartig, M S, Heinzel, G, Hewitson, M, Hollington, D, Hoyland, D, Hueller, M, Inchauspé, H, Jennrich, O, Jetzer, P, Johlander, B, Karnesis, N, Kaune, B, Korsakova, N, Killow, C J, Liu, L, Lobo, J A, López-Zaragoza, J P, Maarschalkerweerd, R, Mance, D, Martín, V, Martin-Polo, L, Martin-Porqueras, F, Martino, J, McNamara, P W, Mendes, J, Mendes, L, Meshksar, N, Moerschell, J, Nofrarias, M, Paczkowski, S, Perreur-Lloyd, M, Petiteau, A, Plagnol, E, Praplan, C, Ramos-Castro, J, Reiche, J, Rivas, F, Robertson, D I, Russano, G, Sala, L, Sarra, P, Schule-Walewski, S L, Slutsky, J, Sopuerta, C F, Stanga, R, Sumner, T, Pierick, J ten, Texier, D, Thorpe, J I, Vetrugno, D, Vitale, S, Wanner, G, Ward, H, Wass, P, Weber, W J, Wissel, L, Wittchen, A, Zanoni, C, Zweifel, P

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics, General Relativity and Quantum Cosmology

الوصف: Electrostatic force actuation is a key component of the system of geodesic reference test masses (TM) for the LISA orbiting gravitational wave observatory and in particular for performance at low frequencies, below 1 mHz, where the observatory sensitivity is limited by stray force noise. The system needs to apply forces of order 10$^{-9}$ N while limiting fluctuations in the measurement band to levels approaching 10$^{-15}$ N/Hz$^{1/2}$. We present here the LISA actuation system design, based on audio-frequency voltage carrier signals, and results of its in-flight performance test with the LISA Pathfinder test mission. In LISA, TM force actuation is used to align the otherwise free-falling TM to the spacecraft-mounted optical metrology system, without any forcing along the critical gravitational wave-sensitive interferometry axes. In LISA Pathfinder, on the other hand, the actuation was used also to stabilize the TM along the critical $x$ axis joining the two TM, with the commanded actuation force entering directly into the mission's main differential acceleration science observable. The mission allowed demonstration of the full compatibility of the electrostatic actuation system with the LISA observatory requirements, including dedicated measurement campaigns to amplify, isolate, and quantify the two main force noise contributions from the actuation system, from actuator gain noise and from low frequency ``in band'' voltage fluctuations. These campaigns have shown actuation force noise to be a relevant, but not dominant, noise source in LISA Pathfinder and have allowed performance projections for the conditions expected in the LISA mission.

URL الوصول: http://arxiv.org/abs/2401.00884

المؤلفون: Armano, M, Audley, H, Baird, J, Binetruy, P, Born, M, Bortoluzzi, D, Castelli, E, Cavalleri, A, Cesarini, A, Cruise, A M, Danzmann, K, Silva, M de Deus, Diepholz, I, Dixon, G, Dolesi, R, Ferraioli, L, Ferroni, V, Fitzsimons, E D, Freschi, M, Gesa, L, Giardini, D, Gibert, F, Giusteri, R, Grimani, C, Grzymisch, J, Harrison, I, Hartig, M-S, Heinzel, G, Hewitson, M, Hollington, D, Hoyland, D, Hueller, M, Inchauspé, H, Jennrich, O, Jetzer, P, Johann, U, Johlander, B, Karnesis, N, Kaune, B, Killow, C J, Korsakova, N, Lobo, J A, López-Zaragoza, J P, Maarschalkerweerd, R, Mance, D, Martín, V, Martin-Polo, L, Martin-Porqueras, F, Martino, J, McNamara, P W, Mendes, J, Mendes, L, Meshksar, N, Nofrarias, M, Paczkowski, S, Perreur-Lloyd, M, Petiteau, A, Plagnol, E, Ramos-Castro, J, Reiche, J, Rivas, F, Robertson, D I, Russano, G, Sanjuan, J, Slutsky, J, Sopuerta, C F, Sumner, T, Tevlin, L, Texier, D, Thorpe, J I, Vetrugno, D, Vitale, S, Wanner, G, Ward, H, Wass, P J, Weber, W J, Wissel, L, Wittchen, A, Zweifel, P

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics

الوصف: We present a study of the tilt-to-length coupling noise during the LISA Pathfinder mission and how it depended on the system's alignment. Tilt-to-length coupling noise is the unwanted coupling of angular and lateral spacecraft or test mass motion into the primary interferometric displacement readout. It was one of the major noise sources in the LISA Pathfinder mission and is likewise expected to be a primary noise source in LISA. We demonstrate here that a recently derived and published analytical model describes the dependency of the LISA Pathfinder tilt-to-length coupling noise on the alignment of the two freely falling test masses. This was verified with the data taken before and after the realignments performed in March (engineering days) and June 2016, and during a two-day experiment in February 2017 (long cross-talk experiment). The latter was performed with the explicit goal of testing the tilt-to-length coupling noise dependency on the test mass alignment. Using the analytical model, we show that all realignments performed during the mission were only partially successful and explain the reasons why. In addition to the analytical model, we computed another physical tilt-to-length coupling model via a minimising routine making use of the long cross-talk experiment data. A similar approach could prove useful for the LISA mission.

URL الوصول: http://arxiv.org/abs/2308.02398

المؤلفون: LISA Pathfinder Collaboration, Armano, M., Audley, H., Baird, J., Binetruy, P., Born, M., Bortoluzzi, D., Castelli, E., Cesarini, A. Cavalleri A., Cruise, A. M, Danzmann, K., Silva, M. de Deus, Diepholz, I., Dixon, G., Dolesi, R., Ferraioli, L., Ferroni, V., Fitzsimons, E. D., Freschi, M., Gesa, L., Giardini, D., Gibert, F., Giusteri, R., Grimani, C., Grzymisch, J., Harrison, I., Hartig, M. -S., Heinzel, G., Hewitson, M., Hollington, D., Hoyland, D., Hueller, M., Inchauspé, H., Jennrich, O., Jetzer, P., Karnesis, N., Kaune, B., Killow, C. J., Korsakova, N., Lobo, J. A., López-Zaragoza, J. P., Maarschalkerweerd, R., Mance, D., Martín, V., Martino, J., Martin-Polo, L., Martin-Porqueras, F., McNamara, P. W., Mendes, J., Mendes, L., Meshksar, N., Nofrarias, M., Paczkowski, S., Perreur-Lloyd, M., Petiteau, A., Plagnol, E., Ramos-Castro, J., Reiche, J., Rivas, F., Robertson, D. I., Russano, G., Slutsky, J., Sopuerta, C. F., Sumner, T. J., Texier, D., Thorpe, J. I., Vetrugno, D., Vitale, S., Wanner, G., Ward, H., Wass, P. J., Weber, W. J., Wissel, L., Wittchen, A., Zweifel, P.

المصدر: Phys. Rev. D 107, 062007 (2023)

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics

الوصف: A comprehensive summary of the measurements made to characterize test mass charging due to the space environment during the LISA Pathfinder mission is presented. Measurements of the residual charge of the test mass after release by the grabbing and positioning mechanism, show that the initial charge of the test masses was negative after all releases, leaving the test mass with a potential in the range $-12$ mV to $-512$ mV. Variations in the neutral test mass charging rate between $21.7$ e s$^{-1}$ and $30.7$ e s$^{-1}$ were observed over the course of the 17-month science operations produced by cosmic ray flux changes including a Forbush decrease associated with a small solar energetic particle event. A dependence of the cosmic ray charging rate on the test mass potential between $-30.2$ e s$^{-1}$ V$^{-1}$ and $-40.3$ e s$^{-1}$ V$^{-1}$ was observed and this is attributed to a contribution to charging from low-energy electrons emitted from the gold surfaces of the gravitational reference sensor. Data from the on-board particle detector show a reliable correlation with the charging rate and with other environmental monitors of the cosmic ray flux. This correlation is exploited to extrapolate test mass charging rates to a 20-year period giving useful insight into the expected range of charging rate that may be observed in the LISA mission.
Comment: 17 pages, 10 figures

URL الوصول: http://arxiv.org/abs/2211.09309

المؤلفون: Armano, M., Audley, H., Baird, J., Binetruy, P., Born, M., Bortoluzzi, D., Castelli, E., Cavalleri, A., Cesarini, A., Cruise, A. M., Danzmann, K., Silva, M. de Deus, Diepholz, I., Dixon, G., Dolesi, R., Ferraioli, L., Ferroni, V., Fitzsimons, E. D., Freschi, M., Gesa, L., Gibert, F., Giardini, D., Giusteri, R., Grimani, C., Grzymisch, J., Harrison, I., Hartig, M-S., Heinzel, G., Hewitson, M., Hollington, D., Hoyland, D., Hueller, M., Inchauspé, H., Jennrich, O., Jetzer, P., Karnesis, N., Kaune, B., Korsakova, N., Killow, C. J., Lobo, J. A., Liu, L., López-Zaragoza, J. P., Maarschalkerweerd, R., Mance, D., Martín, V., Martin-Polo, L., Martino, J., Martin-Porqueras, F., Mateos, I., McNamara, P. W., Mendes, J., Mendes, L., Meshksar, N., Nofrarias, M., Paczkowski, S., Perreur-Lloyd, M., Petiteau, A., Pivato, P., Plagnol, E., Ramos-Castro, J., Reiche, J., Rivas, F., Robertson, D. I., Roma-Dollase, D., Russano, G., Slutsky, J., Sopuerta, C. F., Sumner, T., Telloni, D., Texier, D., Thorpe, J. I., Trenkel, C., Vetrugno, D., Vitale, S., Wanner, G., Ward, H., Wass, P. J., Wealthy, D., Weber, W. J., Wissel, L., Wittchen, A., Zweifel, P.

المصدر: Monthly Notices of the Royal Astronomical Society, 2020, 494.2: 3014-3027

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics

الوصف: LISA Pathfinder (LPF) has been a space-based mission designed to test new technologies that will be required for a gravitational wave observatory in space. Magnetically driven forces play a key role in the instrument sensitivity in the low-frequency regime (mHz and below), the measurement band of interest for a space-based observatory. The magnetic field can couple to the magnetic susceptibility and remanent magnetic moment from the test masses and disturb them from their geodesic movement. LISA Pathfinder carried on-board a dedicated magnetic measurement subsystem with noise levels of 10 $ \rm nT \ Hz^{-1/2}$ from 1 Hz down to 1 mHz. In this paper we report on the magnetic measurements throughout LISA Pathfinder operations. We characterise the magnetic environment within the spacecraft, study the time evolution of the magnetic field and its stability down to 20 $\mu$Hz, where we measure values around 200 $ \rm nT \ Hz^{-1/2}$ and identify two different frequency regimes, one related to the interplanetary magnetic field and the other to the magnetic field originating inside the spacecraft. Finally, we characterise the non-stationary component of the fluctuations of the magnetic field below the mHz and relate them to the dynamics of the solar wind.
Comment: 16 pages, 17 figures. MNRAS LaTeX style file version 3.0

URL الوصول: http://arxiv.org/abs/2005.03423

المؤلفون: Armano, M., Audley, H., Baird, J., Binetruy, P., Born, M., Bortoluzzi, D., Castelli, E., Cavalleri, A., Cesarini, A., Cruise, A. M., Danzmann, K., Silva, M. de Deus, Diepholz, I., Dixon, G., Dolesi, R., Ferraioli, L., Ferroni, V., Fitzsimons, E. D., Freschi, M., Gesa, L., Gibert, F., Giardini, D., Giusteri, R., Grimani, C., Grzymisch, J., Harrison, I., Hartig, M-S., Heinzel, G., Hewitson, M., Hollington, D., Hoyland, D., Hueller, M., Inchauspé, H., Jennrich, O., Jetzer, P., Karnesis, N., Kaune, B., Korsakova, N., Killow, C. J., Lobo, J. A., Liu, L., Llopez-Zaragoza, J. P., Maarschalkerweerd, R., Mance, D., Meshksar, N., Martìn, V., Martin-Polo, L., Martino, J., Martin-Porqueras, F., Mateos, I., McNamara, P. W., Mendes, J., Mendes, L., Nofrarias, M., Paczkowski, S., Perreur-Lloyd, M., Petiteau, A., Pivato, P., Plagnol, E., Ramos-Castro, J., Reiche, J., Robertson, D. I., Rivas, F., Russano, G., Slutsky, J., Sopuerta, C. F., Sumner, T., Texier, D., Thorpe, J. I., Vetrugno, D., Vitale, S., Wanner, G., Ward, H., Wass, P. J., Weber, W. J., Wissel, L., Wittchen, A., Zweifel, P.

مصطلحات موضوعية: Physics - Space Physics, Astrophysics - Instrumentation and Methods for Astrophysics

الوصف: We report on the results of the LISA Pathfinder (LPF) free-fall mode experiment, in which the control force needed to compensate the quasistatic differential force acting on two test masses is applied intermittently as a series of "impulse" forces lasting a few seconds and separated by roughly 350 s periods of true free fall. This represents an alternative to the normal LPF mode of operation in which this balancing force is applied continuously, with the advantage that the acceleration noise during free fall is measured in the absence of the actuation force, thus eliminating associated noise and force calibration errors. The differential acceleration noise measurement presented here with the free-fall mode agrees with noise measured with the continuous actuation scheme, representing an important and independent confirmation of the LPF result. An additional measurement with larger actuation forces also shows that the technique can be used to eliminate actuation noise when this is a dominant factor.

URL الوصول: http://arxiv.org/abs/1908.11584

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