Publications
479 results found
Armano M, Audley H, Baird J, et al., 2023, Tilt-to-length coupling in LISA Pathfinder: A data analysis, Physical Review D, Vol: 108, ISSN: 2470-0010
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 minimizing routine making use of the long cross-talk experiment data. A similar approach could prove useful for the LISA mission.
Aalbers J, Akerib DS, Al Musalhi AK, et al., 2023, Search for new physics in low-energy electron recoils from the first LZ exposure, PHYSICAL REVIEW D, Vol: 108, ISSN: 2470-0010
Araujo HM, Balashov SN, Borg JE, et al., 2023, The MIGDAL experiment: Measuring a rare atomic process to aid the search for dark matter, ASTROPARTICLE PHYSICS, Vol: 151, ISSN: 0927-6505
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- Citations: 1
Aalbers J, Akerib DS, Akerlof CW, et al., 2023, First Dark Matter Search Results from the LUX-ZEPLIN (LZ) Experiment, PHYSICAL REVIEW LETTERS, Vol: 131, ISSN: 0031-9007
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- Citations: 5
Aalbers J, Akerib DS, Al Musalhi AK, et al., 2023, Background determination for the LUX-ZEPLIN dark matter experiment, PHYSICAL REVIEW D, Vol: 108, ISSN: 2470-0010
Apple S, Alvarez AD, Kenyon SP, et al., 2023, Design and performance characterization of a new LISA-like (laser interferometer space antenna-like) gravitational reference sensor and torsion pendulum testbed, REVIEW OF SCIENTIFIC INSTRUMENTS, Vol: 94, ISSN: 0034-6748
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- Citations: 2
Armano M, Audley H, Baird J, et al., 2023, Charging of free-falling test masses in orbit due to cosmic rays: Results from LISA Pathfinder, Physical Review D, Vol: 107, ISSN: 2470-0010
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 from -12 to -512. Variations in the neutral test-mass charging rate between 21.7 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 and -40.3 e s-1 V-1 was observed resulting in an equilibrium test-mass potential between 670 and 960 mV, 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 onboard 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.
Wass PJ, Sumner TJ, Araujo HM, et al., 2023, Simulating the charging of isolated free-falling masses from TeV to eV energies: Detailed comparison with LISA Pathfinder results, PHYSICAL REVIEW D, Vol: 107, ISSN: 2470-0010
Aalbers J, AbdusSalam SS, Abe K, et al., 2023, A next-generation liquid xenon observatory for dark matter and neutrino physics, Journal of Physics G: Nuclear and Particle Physics, Vol: 50, ISSN: 0954-3899
The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for weakly interacting massive particles, while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector.
Apple SM, Kenyon SP, Barke S, et al., 2022, Measurement of stray electric fields in a capacitive inertial sensor using contactless test-mass charge modulation, PHYSICAL REVIEW D, Vol: 106, ISSN: 2470-0010
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- Citations: 1
Akerib DS, Alsum S, Araujo HM, et al., 2022, Fast and flexible analysis of direct dark matter search data with machine learning, PHYSICAL REVIEW D, Vol: 106, ISSN: 2470-0010
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- Citations: 1
Touboul P, Metris G, Rodrigues M, et al., 2022, Result of the MICROSCOPE weak equivalence principle test, CLASSICAL AND QUANTUM GRAVITY, Vol: 39, ISSN: 0264-9381
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- Citations: 13
Armano M, Audley H, Baird J, et al., 2022, Sensor noise in LISA Pathfinder: An extensive in-flight review of the angular and longitudinal interferometric measurement system, Physical Review D: Particles, Fields, Gravitation and Cosmology, Vol: 106, Pages: 1-34, ISSN: 1550-2368
In a previous article [1], we have reported on the first subpicometer interferometer flown in space as part of ESA’s LISA Pathfinder mission, and have shown the residual sensor noise to be on the level of 32.0+2.4−1.7 fm/√Hz. This review provides a deeper and more complete overview of the full system and its interferometric mission performance under varying operational conditions, allowing a much more detailed view on the noise model. We also include the optical measurements of rotations through differential wave front sensing (DWS), which reached a sensitivity of as good as 100 prad/√Hz. We present more evidence for the long-term stability of the interferometric performance and components. This proves a solid foundation for future interferometry in space such as the LISA mission.
Touboul P, Métris G, Rodrigues M, et al., 2022, MICROSCOPE mission: final results of the test of the equivalence principle, Physical Review Letters, Vol: 129, ISSN: 0031-9007
The MICROSCOPE mission was designed to test the weak equivalence principle (WEP), stating the equality between the inertial and the gravitational masses, with a precision of 10^{-15} in terms of the Eötvös ratio η. Its experimental test consisted of comparing the accelerations undergone by two collocated test masses of different compositions as they orbited the Earth, by measuring the electrostatic forces required to keep them in equilibrium. This was done with ultrasensitive differential electrostatic accelerometers onboard a drag-free satellite. The mission lasted two and a half years, cumulating five months worth of science free-fall data, two-thirds with a pair of test masses of different compositions-titanium and platinum alloys-and the last third with a reference pair of test masses of the same composition-platinum. We summarize the data analysis, with an emphasis on the characterization of the systematic uncertainties due to thermal instabilities and on the correction of short-lived events which could mimic a WEP violation signal. We found no violation of the WEP, with the Eötvös parameter of the titanium and platinum pair constrained to η(Ti,Pt)=[-1.5±2.3(stat)±1.5(syst)]×10^{-15} at 1σ in statistical errors.
Armano M, Audley H, Baird J, et al., 2022, Transient acceleration events in LISA Pathfinder data: Properties and possible physical origin, PHYSICAL REVIEW D, Vol: 106, ISSN: 2470-0010
Aalbers J, Akerib DS, Al Musalhi AK, et al., 2022, Cosmogenic production of 37Ar in the context of the LUX-ZEPLIN experiment, Physical Review D, Vol: 105, Pages: 1-8, ISSN: 2470-0010
We estimate the amount of 37Ar produced in natural xenon via cosmic-ray-induced spallation, an inevitable consequence of the transportation and storage of xenon on the Earth’s surface. We then calculate the resulting 37Ar concentration in a 10-tonne payload (similar to that of the LUX-ZEPLIN experiment) assuming a representative schedule of xenon purification, storage, and delivery to the underground facility. Using the spallation model by Silberberg and Tsao, the sea-level production rate of 37Ar in natural xenon is estimated to be 0.024 atoms/kg/day. Assuming the xenon is successively purified to remove radioactive contaminants in 1-tonne batches at a rate of 1 tonne/month, the average 37Ar activity after 10 tons are purified and transported underground is 0.058−0.090 μBq/kg, depending on the degree of argon removal during above-ground purification. Such cosmogenic 37Ar will appear as a noticeable background in the early science data, while decaying with a 35-day half-life. This newly noticed production mechanism of 37Ar should be considered when planning for future liquid-xenon-based experiments.
Akerib DS, Akerlof CW, Akimov DY, et al., 2022, The LUX-ZEPLIN (LZ) radioactivity and cleanliness control programs (vol 80, 1044, 2020), EUROPEAN PHYSICAL JOURNAL C, Vol: 82, ISSN: 1434-6044
Akerib DS, Al Musalhi AK, Alsum SK, et al., 2021, Projected sensitivities of the LUX-ZEPLIN experiment to new physics via low-energy electron recoils, Physical Review D: Particles, Fields, Gravitation and Cosmology, Vol: 104, Pages: 1-16, ISSN: 1550-2368
LUX-ZEPLIN is a dark matter detector expected to obtain world-leading sensitivity to weakly-interacting massive particles interacting via nuclear recoils with a ∼7-tonne xenon target mass. This paper presents sensitivity projections to several low-energy signals of the complementary electron recoil signal type: 1) an effective neutrino magnetic moment, and 2) an effective neutrino millicharge, both for pp-chain solar neutrinos, 3) an axion flux generated by the Sun, 4) axionlike particles forming the Galactic dark matter, 5) hidden photons, 6) mirror dark matter, and 7) leptophilic dark matter. World-leading sensitivities are expected in each case, a result of the large 5.6 t 1000 d exposure and low expected rate of electron-recoil backgrounds in the <100 keV energy regime. A consistent signal generation, background model and profile-likelihood analysis framework is used throughout.
Akerib DS, Al Musalhi AK, Alsum SK, et al., 2021, Projected sensitivity of the LUX-ZEPLIN experiment to the two-neutrino and neutrinoless double β decays of Xe134, Physical Review C, Vol: 104, Pages: 1-11, ISSN: 2469-9985
The projected sensitivity of the LUX-ZEPLIN (LZ) experiment to two-neutrino and neutrinoless double β decay of 134Xe is presented. LZ is a 10-tonne xenon time-projection chamber optimized for the detection of dark matter particles and is expected to start operating in 2021 at Sanford Underground Research Facility, USA. Its large mass of natural xenon provides an exceptional opportunity to search for the double β decay of 134Xe, for which xenon detectors enriched in 136Xe are less effective. For the two-neutrino decay mode, LZ is predicted to exclude values of the half-life up to 1.7×1024 years at 90% confidence level (CL) and has a three-sigma observation potential of 8.7×1023 years, approaching the predictions of nuclear models. For the neutrinoless decay mode LZ, is projected to exclude values of the half-life up to 7.3×1024 years at 90% CL.
Akerib DS, Alsum S, Araujo HM, et al., 2021, Constraints on effective field theory couplings using 311.2 days of LUX data, Physical Review D: Particles, Fields, Gravitation and Cosmology, Vol: 104, Pages: 1-19, ISSN: 1550-2368
We report here the results of a nonrelativistic effective field theory (EFT) WIMP search analysis using LUX data. We build upon previous LUX analyses by extending the search window to include nuclear recoil energies up to ∼180 keVnr, requiring a reassessment of data quality criteria and background models. In order to use an unbinned profile likelihood statistical framework, the development of new analysis techniques to account for higher-energy backgrounds was required. With a 3.14×104 kg⋅day exposure using data collected between 2014 and 2016, we find our data is compatible with the background expectation and set 90% C.L. exclusion limits on nonrelativistic EFT WIMP-nucleon couplings, improving upon previous LUX results and providing constraints on a EFT WIMP interactions using the {neutron,proton} interaction basis. Additionally, we report exclusion limits on inelastic EFT WIMP-isoscalar recoils that are competitive and world-leading for several interaction operators.
Akerib DS, Alsum S, Araujo HM, et al., 2021, Improving sensitivity to low-mass dark matter in LUX using a novel electrode background mitigation technique, Physical Review D: Particles, Fields, Gravitation and Cosmology, Vol: 104, Pages: 1-15, ISSN: 1550-2368
This paper presents a novel technique for mitigating electrode backgrounds that limit the sensitivity of searches for low-mass dark matter (DM) using xenon time projection chambers. In the Large Underground Xenon (LUX) detector, signatures of low-mass DM interactions would be very low-energy (∼keV) scatters in the active target that ionize only a few xenon atoms and seldom produce detectable scintillation signals. In this regime, extra precaution is required to reject a complex set of low-energy electron backgrounds that have long been observed in this class of detector. Noticing backgrounds from the wire grid electrodes near the top and bottom of the active target are particularly pernicious, we develop a machine learning technique based on ionization pulse shape to identify and reject these events. We demonstrate the technique can improve Poisson limits on low-mass DM interactions by a factor of 1.7–3 with improvement depending heavily on the size of ionization signals. We use the technique on events in an effective 5 tonne·day exposure from LUX’s 2013 science operation to place strong limits on low-mass DM particles with masses in the range mχ∈0.15–10 GeV. This machine learning technique is expected to be useful for near-future experiments, such as LUX-ZEPLIN and XENONnT, which hope to perform low-mass DM searches with the stringent background control necessary to make a discovery.
Berge J, Baudis L, Brax P, et al., 2021, The local dark sector Probing gravitation's low-acceleration frontier and dark matter in the Solar System neighborhood, EXPERIMENTAL ASTRONOMY, Vol: 51, Pages: 1737-1766, ISSN: 0922-6435
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- Citations: 5
Battelier B, Berge J, Bertoldi A, et al., 2021, Exploring the foundations of the physical universe with space tests of the equivalence principle, EXPERIMENTAL ASTRONOMY, Vol: 51, Pages: 1695-1736, ISSN: 0922-6435
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- Citations: 16
Armano M, Audley H, Baird J, et al., 2021, Sensor Noise in <i>LISA</i> <i>Pathfinder</i>: In-Flight Performance of the Optical Test Mass Readout, PHYSICAL REVIEW LETTERS, Vol: 126, ISSN: 0031-9007
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- Citations: 16
Kenyon SP, Letson B, Clark M, et al., 2021, A Charge Management System for Gravitational Reference Sensors - Design and Instrument Testing, ISSN: 1095-323X
Gravitational reference sensors (GRSs) are imperative to Earth geodesy missions and gravitational wave observations in space. A typical GRS consists of a test mass (TM) surrounded by a capacitive electrode housing to perform sensitive relative position measurements and to apply small forces to the TM. This paper specifically discusses advancements in the charge management system (CMS) for the GRS being used in the LISA mission. Space radiation accumulating charge on the TM will eventually generate unwanted forces on the TM due to stray electric fields in the spacecraft. Thus, the TM charge must be kept close to a zero potential. The TM charge will be controlled in a contact-free manner by shining UV light and exploiting the photoelectric effect. A major design improvement for future missions is using UV LEDs, which can be pulsed. This facilitates more advanced charge control schemes for a continuous science measurement. The UV LEDs are housed in an aluminum block and controlled with supporting electronics via the charge management device (CMD). The CMD needs to be integrated with the spacecraft computer and needs to contain redundancy to survive the 10+ year LISA mission. The CMD is a NASA deliverable for the ESA mission and has begun the process of technology advancement and testing. The unit has custom PCBs designed to supply both continuous and pulsed current to the UV LEDs, readback telemetry data, manage CMD power needs, and synchronize with the spacecraft computer to communicate with spacecraft operators. The system achieved TRL 4 at the end of 2018 and surpassed all requirements for performance, redundancy, and lifetime. The system is capable of generating stable and robust square UV light pulses, has the capacity to drive the UV LEDs at their full dynamic range, and meets requirements on power, pulse properties, stability, and commanding speed. This technology features novel discharge methods and improvements on past missions in terms of noise level and cont
Bortoluzzi D, Vignotto D, Zambotti A, et al., 2021, In-flight testing of the injection of the LISA Pathfinder test mass into a geodesic, ADVANCES IN SPACE RESEARCH, Vol: 67, Pages: 504-520, ISSN: 0273-1177
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- Citations: 6
Akerib DS, Alsum S, Araujo HM, et al., 2020, Discrimination of electronic recoils from nuclear recoils in two-phase xenon time projection chambers, Physical Review D: Particles, Fields, Gravitation and Cosmology, Vol: 102, Pages: 1-27, ISSN: 1550-2368
We present a comprehensive analysis of electronic recoil vs nuclear recoil discrimination in liquid/gas xenon time projection chambers, using calibration data from the 2013 and 2014–2016 runs of the Large Underground Xenon experiment. We observe strong charge-to-light discrimination enhancement with increased event energy. For events with S1=120 detected photons, i.e., equivalent to a nuclear recoil energy of ∼100 keV, we observe an electronic recoil background acceptance of <10−5 at a nuclear recoil signal acceptance of 50%. We also observe modest electric field dependence of the discrimination power, which peaks at a field of around 300 V/cm over the range of fields explored in this study (50–500 V/cm). In the weakly interacting massive particle search region of S1=1−80 phd, the minimum electronic recoil leakage we observe is (7.3±0.6)×10−4, which is obtained for a drift field of 240–290 V/cm. Pulse shape discrimination is utilized to improve our results, and we find that, at low energies and low fields, there is an additional reduction in background leakage by a factor of up to 3. We develop an empirical model for recombination fluctuations which, when used alongside the Noble Element Scintillation Technique simulation package, correctly reproduces the skewness of the electronic recoil data. We use this updated simulation to study the width of the electronic recoil band, finding that its dominant contribution comes from electron-ion recombination fluctuations, followed in magnitude of contribution by fluctuations in the S1 signal, fluctuations in the S2 signal, and fluctuations in the total number of quanta produced for a given energy deposition.
Yang F, Bai Y, Hong W, et al., 2020, A charge control method for space-mission inertial sensor using differential UV LED emission, REVIEW OF SCIENTIFIC INSTRUMENTS, Vol: 91, ISSN: 0034-6748
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- Citations: 10
Akerib DS, Akerlof CW, Akimov DY, et al., 2020, The LUX-ZEPLIN (LZ) radioactivity and cleanliness control programs, European Physical Journal C: Particles and Fields, Vol: 80, Pages: 1-52, ISSN: 1124-1861
LUX-ZEPLIN (LZ) is a second-generation direct dark matter experiment with spin-independent WIMP-nucleon scattering sensitivity above 1.4×10−48cm2 for a WIMP mass of 40GeV/c2 and a 1000days exposure. LZ achieves this sensitivity through a combination of a large 5.6t fiducial volume, active inner and outer veto systems, and radio-pure construction using materials with inherently low radioactivity content. The LZ collaboration performed an extensive radioassay campaign over a period of six years to inform material selection for construction and provide an input to the experimental background model against which any possible signal excess may be evaluated. The campaign and its results are described in this paper. We present assays of dust and radon daughters depositing on the surface of components as well as cleanliness controls necessary to maintain background expectations through detector construction and assembly. Finally, examples from the campaign to highlight fixed contaminant radioassays for the LZ photomultiplier tubes, quality control and quality assurance procedures through fabrication, radon emanation measurements of major sub-systems, and bespoke detector systems to assay scintillator are presented.
Akerib DS, Alsum S, Araujo HM, et al., 2020, Investigation of background electron emission in the LUX detector, Physical Review D: Particles, Fields, Gravitation and Cosmology, Vol: 102, Pages: 1-17, ISSN: 1550-2368
Dual-phase xenon detectors, as currently used in direct detection dark matter experiments, have observed elevated rates of background electron events in the low energy region. While this background negatively impacts detector performance in various ways, its origins have only been partially studied. In this paper we report a systematic investigation of the electron pathologies observed in the LUX dark matter experiment. We characterize different electron populations based on their emission intensities and their correlations with preceding energy depositions in the detector. By studying the background under different experimental conditions, we identified the leading emission mechanisms, including photoionization and the photoelectric effect induced by the xenon luminescence, delayed emission of electrons trapped under the liquid surface, capture and release of drifting electrons by impurities, and grid electron emission. We discuss how these backgrounds can be mitigated in LUX and future xenon-based dark matter experiments.
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