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Coating-free monolithic fused silica resonator via total internal reflection for precision laser stabilization
Authors:
Swadha Pandey,
Rodica Martin,
Peter Fritschel,
Matthew Evans,
Evan D. Hall
Abstract:
Brownian noise in the thin-film mirror coatings of optical reference cavities is a fundamental limitation in precision metrology, including gravitational-wave detectors and optical atomic clocks. We demonstrate a monolithic fused silica resonator that eliminates the use of thin-film coatings by operating via total internal reflection (TIR), achieving a finesse of 1225 and an optical mode volume of…
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Brownian noise in the thin-film mirror coatings of optical reference cavities is a fundamental limitation in precision metrology, including gravitational-wave detectors and optical atomic clocks. We demonstrate a monolithic fused silica resonator that eliminates the use of thin-film coatings by operating via total internal reflection (TIR), achieving a finesse of 1225 and an optical mode volume of \qty{50}{mm^3}. To our knowledge, this is the largest mode volume reported for any coating-free monolithic resonator, comparable to state-of-the-art reference cavities. We use the cavity to frequency-stabilize an Nd:YAG laser, and demonstrate its application to precision metrology by operating it in a passive ring gyroscope configuration. This platform circumvents the dominant noise source of conventional reference cavities and provides a pathway toward cryogenic silicon TIR resonators that could surpass current frequency stabilization limits.
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Submitted 31 July, 2026;
originally announced July 2026.
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Wave-particle duality in the measurement of gravitational radiation
Authors:
Hudson A. Loughlin,
Germain Tobar,
Evan D. Hall,
Vivishek Sudhir
Abstract:
In a consistent description of the quantum measurement process, whether the wave or particle-like aspect of a system is revealed depends on the details of the measurement chain, and cannot be interpreted as an objective fact about the system independent of the measurement. We show precisely how this comes to be in the measurement of gravitational radiation. Whether a wave or particle-like aspect i…
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In a consistent description of the quantum measurement process, whether the wave or particle-like aspect of a system is revealed depends on the details of the measurement chain, and cannot be interpreted as an objective fact about the system independent of the measurement. We show precisely how this comes to be in the measurement of gravitational radiation. Whether a wave or particle-like aspect is revealed is a property of the detector employed at the end of the quantum measurement chain, rather than of the meter, such as a gravitational-wave (GW) antenna or resonant bar, used to couple the radiation to the detector. A linear detector yields no signal for radiation in a Fock state and a signal proportional to the amplitude in a coherent state -- supporting a wave-like interpretation. By contrast, the signal from a detector coupled to the meter's energy is non-zero only when the incident radiation contains at least a single graviton. Thus, conceptually simple modifications of contemporary GW antennae can reveal wave-particle duality in the measurement of gravitational radiation.
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Submitted 12 December, 2025; v1 submitted 4 April, 2025;
originally announced April 2025.
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Using data collected from structured light plethysmography to differentiate breathing pattern disorder from normal breathing: A study group report
Authors:
Bindi S. Brook,
Mathew Bulpett,
Robin Curnow,
Emily Fraser,
Eric J. Hall,
Shiting Huang,
Mariam Mubarak,
Carl A. Whitfield
Abstract:
This report relates to a study group hosted by the EPSRC funded network, Integrating data-driven BIOphysical models into REspiratory MEdicine (BIOREME), and supported by SofTMech and Innovate UK, Business Connect. This report summarises the work undertaken on a challenge presented by two of the authors, Mathew Bulpett and Dr Emily Fraser. The aim was to identify approaches to analyse data collecte…
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This report relates to a study group hosted by the EPSRC funded network, Integrating data-driven BIOphysical models into REspiratory MEdicine (BIOREME), and supported by SofTMech and Innovate UK, Business Connect. This report summarises the work undertaken on a challenge presented by two of the authors, Mathew Bulpett and Dr Emily Fraser. The aim was to identify approaches to analyse data collected using structured light plethysmography (SLP) from (n=31) healthy volunteers and (n=67) patients with Breathing Pattern Disorder (BPD) attributed to "long COVID", i.e. post-acute COVID-19 sequelae. This report explores several approaches including dimensionality reduction techniques on the available data and alternative indices extracted from variation in the time-series data for each measurement. Further proposals are also outlined such as different spatial indices that could be extracted from the SLP data, and the potential to couple to mechanical models of the lungs, chest and abdomen. However, running these latter analyses was beyond the scope of the limited study group timeframe.
This exploratory analysis did not identify any clear SLP biomarkers of BPD in these cohorts, however recommendations are made for using SLP technologies in future BPD studies based on its findings.
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Submitted 6 December, 2024;
originally announced December 2024.
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Advanced LIGO detector performance in the fourth observing run
Authors:
E. Capote,
W. Jia,
N. Aritomi,
M. Nakano,
V. Xu,
R. Abbott,
I. Abouelfettouh,
R. X. Adhikari,
A. Ananyeva,
S. Appert,
S. K. Apple,
K. Arai,
S. M. Aston,
M. Ball,
S. W. Ballmer,
D. Barker,
L. Barsotti,
B. K. Berger,
J. Betzwieser,
D. Bhattacharjee,
G. Billingsley,
S. Biscans,
C. D. Blair,
N. Bode,
E. Bonilla
, et al. (171 additional authors not shown)
Abstract:
On May 24th, 2023, the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), joined by the Advanced Virgo and KAGRA detectors, began the fourth observing run for a two-year-long dedicated search for gravitational waves. The LIGO Hanford and Livingston detectors have achieved an unprecedented sensitivity to gravitational waves, with an angle-averaged median range to binary neutron st…
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On May 24th, 2023, the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), joined by the Advanced Virgo and KAGRA detectors, began the fourth observing run for a two-year-long dedicated search for gravitational waves. The LIGO Hanford and Livingston detectors have achieved an unprecedented sensitivity to gravitational waves, with an angle-averaged median range to binary neutron star mergers of 152 Mpc and 160 Mpc, and duty cycles of 65.0% and 71.2%, respectively, with a coincident duty cycle of 52.6%. The maximum range achieved by the LIGO Hanford detector is 165 Mpc and the LIGO Livingston detector 177 Mpc, both achieved during the second part of the fourth observing run. For the fourth run, the quantum-limited sensitivity of the detectors was increased significantly due to the higher intracavity power from laser system upgrades and replacement of core optics, and from the addition of a 300 m filter cavity to provide the squeezed light with a frequency-dependent squeezing angle, part of the A+ upgrade program. Altogether, the A+ upgrades led to reduced detector-wide losses for the squeezed vacuum states of light which, alongside the filter cavity, enabled broadband quantum noise reduction of up to 5.2 dB at the Hanford observatory and 6.1 dB at the Livingston observatory. Improvements to sensors and actuators as well as significant controls commissioning increased low frequency sensitivity. This paper details these instrumental upgrades, analyzes the noise sources that limit detector sensitivity, and describes the commissioning challenges of the fourth observing run.
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Submitted 21 November, 2024;
originally announced November 2024.
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Squeezing the quantum noise of a gravitational-wave detector below the standard quantum limit
Authors:
Wenxuan Jia,
Victoria Xu,
Kevin Kuns,
Masayuki Nakano,
Lisa Barsotti,
Matthew Evans,
Nergis Mavalvala,
Rich Abbott,
Ibrahim Abouelfettouh,
Rana Adhikari,
Alena Ananyeva,
Stephen Appert,
Koji Arai,
Naoki Aritomi,
Stuart Aston,
Matthew Ball,
Stefan Ballmer,
David Barker,
Beverly Berger,
Joseph Betzwieser,
Dripta Bhattacharjee,
Garilynn Billingsley,
Nina Bode,
Edgard Bonilla,
Vladimir Bossilkov
, et al. (146 additional authors not shown)
Abstract:
Precision measurements of space and time, like those made by the detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO), are often confronted with fundamental limitations imposed by quantum mechanics. The Heisenberg uncertainty principle dictates that the position and momentum of an object cannot both be precisely measured, giving rise to an apparent limitation called the Stan…
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Precision measurements of space and time, like those made by the detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO), are often confronted with fundamental limitations imposed by quantum mechanics. The Heisenberg uncertainty principle dictates that the position and momentum of an object cannot both be precisely measured, giving rise to an apparent limitation called the Standard Quantum Limit (SQL). Reducing quantum noise below the SQL in gravitational-wave detectors, where photons are used to continuously measure the positions of freely falling mirrors, has been an active area of research for decades. Here we show how the LIGO A+ upgrade reduced the detectors' quantum noise below the SQL by up to 3 dB while achieving a broadband sensitivity improvement, more than two decades after this possibility was first presented.
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Submitted 16 October, 2024; v1 submitted 22 April, 2024;
originally announced April 2024.
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Advanced LIGO, LISA, and Cosmic Explorer as dark matter transducers
Authors:
Evan Hall,
Nancy Aggarwal
Abstract:
We present a method to search for scalar field ultralight dark matter directly interacting with gravitational-wave interferometers via a modulation of the fine structure constant and the electron mass. This modulation induces an effective strain in solid materials at a frequency determined by the mass of the dark matter particle. We study the prospects for looking for such an effect in the LIGO de…
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We present a method to search for scalar field ultralight dark matter directly interacting with gravitational-wave interferometers via a modulation of the fine structure constant and the electron mass. This modulation induces an effective strain in solid materials at a frequency determined by the mass of the dark matter particle. We study the prospects for looking for such an effect in the LIGO detectors by using the solid cavity which is nominally used for pre-stabilizing the laser frequency and we project upper limits. We contextualize them with previous limits from GEO600, possible limits from a similar strain in the LIGO beamsplitter, and with potential limits from upcoming experiments like LISA, Cosmic Explorer and from an upgraded solid cavity. We find that with the sensitivity of Advanced LIGO, competitive upper limits on DM coupling can be placed at the level of $\left\vert d_{m_e}+d_e\right\vert \sim 0.2$ for $m_\text{DM} \sim 10^{-13}\,\mathrm{eV}/\mathrm{c}^2$ with a combination of two searches using the solid cavity and the beamsplitter in LIGO; future experiments could reduce this upper limit to $\sim10^{-3}$.
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Submitted 31 October, 2022;
originally announced October 2022.
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Science-Driven Tunable Design of Cosmic Explorer Detectors
Authors:
Varun Srivastava,
Derek Davis,
Kevin Kuns,
Philippe Landry,
Stefan Ballmer,
Matt Evans,
Evan Hall,
Jocelyn Read,
B. S. Sathyaprakash
Abstract:
Ground-based gravitational-wave detectors like Cosmic Explorer can be tuned to improve their sensitivity at high or low frequencies by tuning the response of the signal extraction cavity. Enhanced sensitivity above 2 kHz enables measurements of the post-merger gravitational-wave spectrum from binary neutron star mergers, which depends critically on the unknown equation of state of hot, ultra-dense…
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Ground-based gravitational-wave detectors like Cosmic Explorer can be tuned to improve their sensitivity at high or low frequencies by tuning the response of the signal extraction cavity. Enhanced sensitivity above 2 kHz enables measurements of the post-merger gravitational-wave spectrum from binary neutron star mergers, which depends critically on the unknown equation of state of hot, ultra-dense matter. Improved sensitivity below 500 Hz favors precision tests of extreme gravity with black hole ringdown signals and improves the detection prospects while facilitating an improved measurement of source properties for compact binary inspirals at cosmological distances. At intermediate frequencies, a more sensitive detector can better measure the tidal properties of neutron stars. We present and characterize the performance of tuned Cosmic Explorer configurations that are designed to optimize detections across different astrophysical source populations. These tuning options give Cosmic Explorer the flexibility to target a diverse set of science goals with the same detector infrastructure. We find that a 40 km Cosmic Explorer detector outperforms a 20 km in all key science goals other than access to post-merger physics. This suggests that Cosmic Explorer should include at least one 40 km facility.
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Submitted 12 July, 2022; v1 submitted 25 January, 2022;
originally announced January 2022.
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Thermorefringent noise in crystalline optical materials
Authors:
Serhii Kryhin,
Evan D. Hall,
Vivishek Sudhir
Abstract:
Any material in thermal equilibrium exhibits fundamental thermodynamic fluctuations of its mechanical and optical properties. Such thermodynamic fluctuations of length, elastic constants, and refractive index of amorphous materials -- like dielectric mirror coatings and substrates -- limit the performance of today's most precise optical instruments. Crystalline materials are increasingly employed…
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Any material in thermal equilibrium exhibits fundamental thermodynamic fluctuations of its mechanical and optical properties. Such thermodynamic fluctuations of length, elastic constants, and refractive index of amorphous materials -- like dielectric mirror coatings and substrates -- limit the performance of today's most precise optical instruments. Crystalline materials are increasingly employed in optical systems because of their reduced mechanical dissipation, which implies a reduction of thermo-mechanical fluctuations. However, the anisotropy of the crystalline state implies a fundamental source of thermal noise: depolarization induced by thermal fluctuations of its birefringence. We establish the theory of this effect, elucidate its consequences, discuss its relevance for precision optical experiments with crystalline materials, and hint at the conditions under which it can be evaded.
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Submitted 31 March, 2022; v1 submitted 9 November, 2021;
originally announced November 2021.
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Point Absorber Limits to Future Gravitational-Wave Detectors
Authors:
W. Jia,
H. Yamamoto,
K. Kuns,
A. Effler,
M. Evans,
P. Fritschel,
R. Abbott,
C. Adams,
R. X. Adhikari,
A. Ananyeva,
S. Appert,
K. Arai,
J. S. Areeda,
Y. Asali,
S. M. Aston,
C. Austin,
A. M. Baer,
M. Ball,
S. W. Ballmer,
S. Banagiri,
D. Barker,
L. Barsotti,
J. Bartlett,
B. K. Berger,
J. Betzwieser
, et al. (176 additional authors not shown)
Abstract:
High-quality optical resonant cavities require low optical loss, typically on the scale of parts per million. However, unintended micron-scale contaminants on the resonator mirrors that absorb the light circulating in the cavity can deform the surface thermoelastically, and thus increase losses by scattering light out of the resonant mode. The point absorber effect is a limiting factor in some hig…
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High-quality optical resonant cavities require low optical loss, typically on the scale of parts per million. However, unintended micron-scale contaminants on the resonator mirrors that absorb the light circulating in the cavity can deform the surface thermoelastically, and thus increase losses by scattering light out of the resonant mode. The point absorber effect is a limiting factor in some high-power cavity experiments, for example, the Advanced LIGO gravitational wave detector. In this Letter, we present a general approach to the point absorber effect from first principles and simulate its contribution to the increased scattering. The achievable circulating power in current and future gravitational-wave detectors is calculated statistically given different point absorber configurations. Our formulation is further confirmed experimentally in comparison with the scattered power in the arm cavity of Advanced LIGO measured by in-situ photodiodes. The understanding presented here provides an important tool in the global effort to design future gravitational wave detectors that support high optical power, and thus reduce quantum noise.
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Submitted 17 September, 2021;
originally announced September 2021.
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Calorimetric classification of track-like signatures in liquid argon TPCs using MicroBooNE data
Authors:
MicroBooNE collaboration,
P. Abratenko,
R. An,
J. Anthony,
J. Asaadi,
A. Ashkenazi,
S. Balasubramanian,
B. Baller,
C. Barnes,
G. Barr,
V. Basque,
L. Bathe-Peters,
O. Benevides Rodrigues,
S. Berkman,
A. Bhanderi,
A. Bhat,
M. Bishai,
A. Blake,
T. Bolton,
L. Camilleri,
D. Caratelli,
I. Caro Terrazas,
R. Castillo Fernandez,
F. Cavanna,
G. Cerati
, et al. (157 additional authors not shown)
Abstract:
The MicroBooNE liquid argon time projection chamber located at Fermilab is a neutrino experiment dedicated to the study of short-baseline oscillations, the measurements of neutrino cross sections in liquid argon, and to the research and development of this novel detector technology. Accurate and precise measurements of calorimetry are essential to the event reconstruction and are achieved by lever…
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The MicroBooNE liquid argon time projection chamber located at Fermilab is a neutrino experiment dedicated to the study of short-baseline oscillations, the measurements of neutrino cross sections in liquid argon, and to the research and development of this novel detector technology. Accurate and precise measurements of calorimetry are essential to the event reconstruction and are achieved by leveraging the TPC to measure deposited energy per unit length along the particle trajectory, with mm resolution. We describe the non-uniform calorimetric reconstruction performance in the detector, showing dependence on the angle of the particle trajectory. Such non-uniform reconstruction directly affects the performance of the particle identification algorithms which infer particle type from calorimetric measurements. This work presents a new particle identification method which accounts for and effectively addresses such non-uniformity. The newly developed method shows improved performance compared to previous algorithms, illustrated by a 94% proton selection efficiency and a 10% muon mis-identification rate, with a fairly loose selection of tracks performed on beam data. The performance is further demonstrated by identifying exclusive final states in $ν_μ CC$ interactions. While developed using MicroBooNE data and simulation, this method is easily applicable to future LArTPC experiments, such as SBND, ICARUS, and DUNE.
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Submitted 4 January, 2022; v1 submitted 31 August, 2021;
originally announced September 2021.
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Measurement of the Longitudinal Diffusion of Ionization Electrons in the MicroBooNE Detector
Authors:
P. Abratenko,
R. An,
J. Anthony,
J. Asaadi,
A. Ashkenazi,
S. Balasubramanian,
B. Baller,
C. Barnes,
G. Barr,
V. Basque,
L. Bathe-Peters,
O. Benevides Rodrigues,
S. Berkman,
A. Bhanderi,
A. Bhat,
M. Bishai,
A. Blake,
T. Bolton,
L. Camilleri,
D. Caratelli,
I. Caro Terrazas,
R. Castillo Fernandez,
F. Cavanna,
G. Cerati,
Y. Chen
, et al. (157 additional authors not shown)
Abstract:
Accurate knowledge of electron transport properties is vital to understanding the information provided by liquid argon time projection chambers (LArTPCs). Ionization electron drift-lifetime, local electric field distortions caused by positive ion accumulation, and electron diffusion can all significantly impact the measured signal waveforms. This paper presents a measurement of the effective longi…
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Accurate knowledge of electron transport properties is vital to understanding the information provided by liquid argon time projection chambers (LArTPCs). Ionization electron drift-lifetime, local electric field distortions caused by positive ion accumulation, and electron diffusion can all significantly impact the measured signal waveforms. This paper presents a measurement of the effective longitudinal electron diffusion coefficient, $D_L$, in MicroBooNE at the nominal electric field strength of 273.9 V/cm. Historically, this measurement has been made in LArTPC prototype detectors. This represents the first measurement in a large-scale (85 tonne active volume) LArTPC operating in a neutrino beam. This is the largest dataset ever used for this measurement. Using a sample of $\sim$70,000 through-going cosmic ray muon tracks tagged with MicroBooNE's cosmic ray tagger system, we measure $D_L = 3.74^{+0.28}_{-0.29}$ cm$^2$/s.
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Submitted 25 June, 2021; v1 submitted 13 April, 2021;
originally announced April 2021.
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Point absorbers in Advanced LIGO
Authors:
Aidan F. Brooks,
Gabriele Vajente,
Hiro Yamamoto,
Rich Abbott,
Carl Adams,
Rana X. Adhikari,
Alena Ananyeva,
Stephen Appert,
Koji Arai,
Joseph S. Areeda,
Yasmeen Asali,
Stuart M. Aston,
Corey Austin,
Anne M. Baer,
Matthew Ball,
Stefan W. Ballmer,
Sharan Banagiri,
David Barker,
Lisa Barsotti,
Jeffrey Bartlett,
Beverly K. Berger,
Joseph Betzwieser,
Dripta Bhattacharjee,
Garilynn Billingsley,
Sebastien Biscans
, et al. (176 additional authors not shown)
Abstract:
Small, highly absorbing points are randomly present on the surfaces of the main interferometer optics in Advanced LIGO. The resulting nano-meter scale thermo-elastic deformations and substrate lenses from these micron-scale absorbers significantly reduces the sensitivity of the interferometer directly though a reduction in the power-recycling gain and indirect interactions with the feedback contro…
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Small, highly absorbing points are randomly present on the surfaces of the main interferometer optics in Advanced LIGO. The resulting nano-meter scale thermo-elastic deformations and substrate lenses from these micron-scale absorbers significantly reduces the sensitivity of the interferometer directly though a reduction in the power-recycling gain and indirect interactions with the feedback control system. We review the expected surface deformation from point absorbers and provide a pedagogical description of the impact on power build-up in second generation gravitational wave detectors (dual-recycled Fabry-Perot Michelson interferometers). This analysis predicts that the power-dependent reduction in interferometer performance will significantly degrade maximum stored power by up to 50% and hence, limit GW sensitivity, but suggests system wide corrections that can be implemented in current and future GW detectors. This is particularly pressing given that future GW detectors call for an order of magnitude more stored power than currently used in Advanced LIGO in Observing Run 3. We briefly review strategies to mitigate the effects of point absorbers in current and future GW wave detectors to maximize the success of these enterprises.
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Submitted 25 March, 2021; v1 submitted 14 January, 2021;
originally announced January 2021.
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Cosmic Ray Background Rejection with Wire-Cell LArTPC Event Reconstruction in the MicroBooNE Detector
Authors:
MicroBooNE collaboration,
P. Abratenko,
M. Alrashed,
R. An,
J. Anthony,
J. Asaadi,
A. Ashkenazi,
S. Balasubramanian,
B. Baller,
C. Barnes,
G. Barr,
V. Basque,
L. Bathe-Peters,
O. Benevides Rodrigues,
S. Berkman,
A. Bhanderi,
A. Bhat,
M. Bishai,
A. Blake,
T. Bolton,
L. Camilleri,
D. Caratelli,
I. Caro Terrazas,
R. Castillo Fernandez,
F. Cavanna
, et al. (164 additional authors not shown)
Abstract:
For a large liquid argon time projection chamber (LArTPC) operating on or near the Earth's surface to detect neutrino interactions, the rejection of cosmogenic background is a critical and challenging task because of the large cosmic ray flux and the long drift time of the TPC. We introduce a superior cosmic background rejection procedure based on the Wire-Cell three-dimensional (3D) event reconst…
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For a large liquid argon time projection chamber (LArTPC) operating on or near the Earth's surface to detect neutrino interactions, the rejection of cosmogenic background is a critical and challenging task because of the large cosmic ray flux and the long drift time of the TPC. We introduce a superior cosmic background rejection procedure based on the Wire-Cell three-dimensional (3D) event reconstruction for LArTPCs. From an initial 1:20,000 neutrino to cosmic-ray background ratio, we demonstrate these tools on data from the MicroBooNE experiment and create a high performance generic neutrino event selection with a cosmic contamination of 14.9\% (9.7\%) for a visible energy region greater than O(200)~MeV. The neutrino interaction selection efficiency is 80.4\% and 87.6\% for inclusive $ν_μ$ charged-current and $ν_e$ charged-current interactions, respectively. This significantly improved performance compared to existing reconstruction algorithms, marks a major milestone toward reaching the scientific goals of LArTPC neutrino oscillation experiments operating near the Earth's surface.
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Submitted 29 June, 2021; v1 submitted 12 January, 2021;
originally announced January 2021.
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Semantic Segmentation with a Sparse Convolutional Neural Network for Event Reconstruction in MicroBooNE
Authors:
MicroBooNE collaboration,
P. Abratenko,
M. Alrashed,
R. An,
J. Anthony,
J. Asaadi,
A. Ashkenazi,
S. Balasubramanian,
B. Baller,
C. Barnes,
G. Barr,
V. Basque,
L. Bathe-Peters,
O. Benevides Rodrigues,
S. Berkman,
A. Bhanderi,
A. Bhat,
M. Bishai,
A. Blake,
T. Bolton,
L. Camilleri,
D. Caratelli,
I. Caro Terrazas,
R. Castillo Fernandez,
F. Cavanna
, et al. (158 additional authors not shown)
Abstract:
We present the performance of a semantic segmentation network, SparseSSNet, that provides pixel-level classification of MicroBooNE data. The MicroBooNE experiment employs a liquid argon time projection chamber for the study of neutrino properties and interactions. SparseSSNet is a submanifold sparse convolutional neural network, which provides the initial machine learning based algorithm utilized…
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We present the performance of a semantic segmentation network, SparseSSNet, that provides pixel-level classification of MicroBooNE data. The MicroBooNE experiment employs a liquid argon time projection chamber for the study of neutrino properties and interactions. SparseSSNet is a submanifold sparse convolutional neural network, which provides the initial machine learning based algorithm utilized in one of MicroBooNE's $ν_e$-appearance oscillation analyses. The network is trained to categorize pixels into five classes, which are re-classified into two classes more relevant to the current analysis. The output of SparseSSNet is a key input in further analysis steps. This technique, used for the first time in liquid argon time projection chambers data and is an improvement compared to a previously used convolutional neural network, both in accuracy and computing resource utilization. The accuracy achieved on the test sample is $\geq 99\%$. For full neutrino interaction simulations, the time for processing one image is $\approx$ 0.5 sec, the memory usage is at 1 GB level, which allows utilization of most typical CPU worker machine.
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Submitted 5 April, 2021; v1 submitted 14 December, 2020;
originally announced December 2020.
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High-performance Generic Neutrino Detection in a LArTPC near the Earth's Surface with the MicroBooNE Detector
Authors:
MicroBooNE collaboration,
P. Abratenko,
M. Alrashed,
R. An,
J. Anthony,
J. Asaadi,
A. Ashkenazi,
S. Balasubramanian,
B. Baller,
C. Barnes,
G. Barr,
V. Basque,
L. Bathe-Peters,
O. Benevides Rodrigues,
S. Berkman,
A. Bhanderi,
A. Bhat,
M. Bishai,
A. Blake,
T. Bolton,
L. Camilleri,
D. Caratelli,
I. Caro Terrazas,
R. Castillo Fernandez,
F. Cavanna
, et al. (164 additional authors not shown)
Abstract:
Large Liquid Argon Time Projection Chambers (LArTPCs) are being increasingly adopted in neutrino oscillation experiments because of their superb imaging capabilities through the combination of both tracking and calorimetry in a fully active volume. Active LArTPC neutrino detectors at or near the Earth's surface, such as the MicroBooNE experiment, present a unique analysis challenge because of the…
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Large Liquid Argon Time Projection Chambers (LArTPCs) are being increasingly adopted in neutrino oscillation experiments because of their superb imaging capabilities through the combination of both tracking and calorimetry in a fully active volume. Active LArTPC neutrino detectors at or near the Earth's surface, such as the MicroBooNE experiment, present a unique analysis challenge because of the large flux of cosmic-ray muons and the slow drift of ionization electrons. We present a novel Wire-Cell-based high-performance generic neutrino-detection technique implemented in MicroBooNE. The cosmic-ray background is reduced by a factor of 1.4$\times10^{5}$ resulting in a 9.7\% cosmic contamination in the selected neutrino candidate events, for visible energies greater than 200~MeV, while the neutrino signal efficiency is retained at 88.4\% for $ν_μ$ charged-current interactions in the fiducial volume in the same energy region. This significantly improved performance compared to existing reconstruction algorithms, marks a major milestone toward reaching the scientific goals of LArTPC neutrino oscillation experiments operating near the Earth's surface.
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Submitted 19 August, 2021; v1 submitted 14 December, 2020;
originally announced December 2020.
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The 1.66 $μ$m Spectrum of the Ethynyl Radical, CCH
Authors:
Eisen C. Gross,
Anh. T. Le,
Gregory E. Hall,
Trevor J. Sears
Abstract:
Frequency-modulated diode laser transient absorption spectra of the ethynyl radical have been recorded at wavelengths close to 1.66 $μ$m. The observed spectrum includes strong, regular, line patterns. The two main bands observed originate in the ground $\tilde{X}\,^2Σ^+$ state and its first excited bending vibrational level of $^2Π$ symmetry. The upper states, of $^2Σ^+$ symmetry at 6055.6 cm…
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Frequency-modulated diode laser transient absorption spectra of the ethynyl radical have been recorded at wavelengths close to 1.66 $μ$m. The observed spectrum includes strong, regular, line patterns. The two main bands observed originate in the ground $\tilde{X}\,^2Σ^+$ state and its first excited bending vibrational level of $^2Π$ symmetry. The upper states, of $^2Σ^+$ symmetry at 6055.6 cm$^{-1}$ and $^2Π$ symmetry at 6413.5 cm$^{-1}$, respectively, had not previously been observed and the data were analyzed in terms of an effective Hamiltonian representing their rotational and fine structure levels to derive parameters which can be used to calculate rotational levels up to J = 37/2 for the $^2Π$ level and J = 29/2 for the $^2Σ$ one. Additionally, a weaker series of lines have been assigned to absorption from the second excited bending, (020), level of $^2Σ$ symmetry, to a previously observed state of $^2Π$ symmetry near 6819 cm$^{-1}$. These strong absorption bands at convenient near-IR laser wavelengths will be useful for monitoring CCH radicals in chemical systems.
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Submitted 17 November, 2020;
originally announced November 2020.
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Neutrino Event Selection in the MicroBooNE Liquid Argon Time Projection Chamber using Wire-Cell 3-D Imaging, Clustering, and Charge-Light Matching
Authors:
MicroBooNE collaboration,
P. Abratenko,
M. Alrashed,
R. An,
J. Anthony,
J. Asaadi,
A. Ashkenazi,
S. Balasubramanian,
B. Baller,
C. Barnes,
G. Barr,
V. Basque,
L. Bathe-Peters,
O. Benevides Rodrigues,
S. Berkman,
A. Bhanderi,
A. Bhat,
M. Bishai,
A. Blake,
T. Bolton,
L. Camilleri,
D. Caratelli,
I. Caro Terrazas,
R. Castillo Fernandez,
F. Cavanna
, et al. (160 additional authors not shown)
Abstract:
An accurate and efficient event reconstruction is required to realize the full scientific capability of liquid argon time projection chambers (LArTPCs). The current and future neutrino experiments that rely on massive LArTPCs create a need for new ideas and reconstruction approaches. Wire-Cell, proposed in recent years, is a novel tomographic event reconstruction method for LArTPCs. The Wire-Cell…
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An accurate and efficient event reconstruction is required to realize the full scientific capability of liquid argon time projection chambers (LArTPCs). The current and future neutrino experiments that rely on massive LArTPCs create a need for new ideas and reconstruction approaches. Wire-Cell, proposed in recent years, is a novel tomographic event reconstruction method for LArTPCs. The Wire-Cell 3D imaging approach capitalizes on charge, sparsity, time, and geometry information to reconstruct a topology-agnostic 3D image of the ionization electrons prior to pattern recognition. A second novel method, the many-to-many charge-light matching, then pairs the TPC charge activity to the detected scintillation light signal, thus enabling a powerful rejection of cosmic-ray muons in the MicroBooNE detector. A robust processing of the scintillation light signal and an appropriate clustering of the reconstructed 3D image are fundamental to this technique. In this paper, we describe the principles and algorithms of these techniques and their successful application in the MicroBooNE experiment. A quantitative evaluation of the performance of these techniques is presented. Using these techniques, a 95% efficient pre-selection of neutrino charged-current events is achieved with a 30-fold reduction of non-beam-coincident cosmic-ray muons, and about 80\% of the selected neutrino charged-current events are reconstructed with at least 70% completeness and 80% purity.
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Submitted 26 December, 2021; v1 submitted 2 November, 2020;
originally announced November 2020.
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Measurement of Differential Cross Sections for $ν_μ$-Ar Charged-Current Interactions with Protons and no Pions in the Final State with the MicroBooNE Detector
Authors:
MicroBooNE collaboration,
P. Abratenko,
M. Alrashed,
R. An,
J. Anthony,
J. Asaadi,
A. Ashkenazi,
S. Balasubramanian,
B. Baller,
C. Barnes,
G. Barr,
V. Basque,
L. Bathe-Peters,
O. Benevides Rodrigues,
S. Berkman,
A. Bhanderi,
A. Bhat,
M. Bishai,
A. Blake,
T. Bolton,
L. Camilleri,
D. Caratelli,
I. Caro Terrazas,
R. Castillo Fernandez,
F. Cavanna
, et al. (160 additional authors not shown)
Abstract:
We present an analysis of MicroBooNE data with a signature of one muon, no pions, and at least one proton above a momentum threshold of 300 MeV/c (CC0$π$Np). This is the first differential cross section measurement of this topology in neutrino-argon interactions. We achieve a significantly lower proton momentum threshold than previous carbon and scintillator-based experiments. Using data collected…
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We present an analysis of MicroBooNE data with a signature of one muon, no pions, and at least one proton above a momentum threshold of 300 MeV/c (CC0$π$Np). This is the first differential cross section measurement of this topology in neutrino-argon interactions. We achieve a significantly lower proton momentum threshold than previous carbon and scintillator-based experiments. Using data collected from a total of approximately $1.6 \times 10^{20}$ protons-on-target, we measure the muon neutrino cross section for the CC0$π$Np interaction channel in argon at MicroBooNE in the Booster Neutrino Beam which has a mean energy of around 800 MeV. We present the results from a data sample with estimated efficiency of 29\% and purity of 76\% as differential cross sections in five reconstructed variables: the muon momentum and polar angle, the leading proton momentum and polar angle, and the muon-proton opening angle. We include smearing matrices that can be used to "forward-fold" theoretical predictions for comparison with these data. We compare the measured differential cross sections to a number of recent theory predictions demonstrating largely good agreement with this first-ever data set on argon.
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Submitted 5 October, 2020;
originally announced October 2020.
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The Continuous Readout Stream of the MicroBooNE Liquid Argon Time Projection Chamber for Detection of Supernova Burst Neutrinos
Authors:
MicroBooNE collaboration,
P. Abratenko,
M. Alrashed,
R. An,
J. Anthony,
J. Asaadi,
A. Ashkenazi,
S. Balasubramanian,
B. Baller,
C. Barnes,
G. Barr,
V. Basque,
L. Bathe-Peters,
O. Benevides Rodrigues,
S. Berkman,
A. Bhanderi,
A. Bhat,
M. Bishai,
A. Blake,
T. Bolton,
L. Camilleri,
D. Caratelli,
I. Caro Terrazas,
R. Castillo Fernandez,
F. Cavanna
, et al. (163 additional authors not shown)
Abstract:
The MicroBooNE continuous readout stream is a parallel readout of the MicroBooNE liquid argon time projection chamber (LArTPC) which enables detection of non-beam events such as those from a supernova neutrino burst. The low energies of the supernova neutrinos and the intense cosmic-ray background flux due to the near-surface detector location makes triggering on these events very challenging. Ins…
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The MicroBooNE continuous readout stream is a parallel readout of the MicroBooNE liquid argon time projection chamber (LArTPC) which enables detection of non-beam events such as those from a supernova neutrino burst. The low energies of the supernova neutrinos and the intense cosmic-ray background flux due to the near-surface detector location makes triggering on these events very challenging. Instead, MicroBooNE relies on a delayed trigger generated by SNEWS (the Supernova Early Warning System) for detecting supernova neutrinos. The continuous readout of the LArTPC generates large data volumes, and requires the use of real-time compression algorithms (zero suppression and Huffman compression) implemented in an FPGA (field-programmable gate array) in the readout electronics. We present the results of the optimization of the data reduction algorithms, and their operational performance. To demonstrate the capability of the continuous stream to detect low-energy electrons, a sample of Michel electrons from stopping cosmic-ray muons is reconstructed and compared to a similar sample from the lossless triggered readout stream.
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Submitted 3 February, 2021; v1 submitted 31 August, 2020;
originally announced August 2020.
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Measurement of Space Charge Effects in the MicroBooNE LArTPC Using Cosmic Muons
Authors:
MicroBooNE collaboration,
P. Abratenko,
M. Alrashed,
R. An,
J. Anthony,
J. Asaadi,
A. Ashkenazi,
S. Balasubramanian,
B. Baller,
C. Barnes,
G. Barr,
V. Basque,
L. Bathe-Peters,
O. Benevides Rodrigues,
S. Berkman,
A. Bhanderi,
A. Bhat,
M. Bishai,
A. Blake,
T. Bolton,
L. Camilleri,
D. Caratelli,
I. Caro Terrazas,
R. Castillo Fernandez,
F. Cavanna
, et al. (162 additional authors not shown)
Abstract:
Large liquid argon time projection chambers (LArTPCs), especially those operating near the surface, are susceptible to space charge effects. In the context of LArTPCs, the space charge effect is the build-up of slow-moving positive ions in the detector primarily due to ionization from cosmic rays, leading to a distortion of the electric field within the detector. This effect leads to a displacemen…
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Large liquid argon time projection chambers (LArTPCs), especially those operating near the surface, are susceptible to space charge effects. In the context of LArTPCs, the space charge effect is the build-up of slow-moving positive ions in the detector primarily due to ionization from cosmic rays, leading to a distortion of the electric field within the detector. This effect leads to a displacement in the reconstructed position of signal ionization electrons in LArTPC detectors ("spatial distortions"), as well as to variations in the amount of electron-ion recombination experienced by ionization throughout the volume of the TPC. We present techniques that can be used to measure and correct for space charge effects in large LArTPCs by making use of cosmic muons, including the use of track pairs to unambiguously pin down spatial distortions in three dimensions. The performance of these calibration techniques are studied using both Monte Carlo simulation and MicroBooNE data, utilizing a UV laser system as a means to estimate the systematic bias associated with the calibration methodology.
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Submitted 9 November, 2020; v1 submitted 22 August, 2020;
originally announced August 2020.
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GINNs: Graph-Informed Neural Networks for Multiscale Physics
Authors:
Eric J. Hall,
Søren Taverniers,
Markos A. Katsoulakis,
Daniel M. Tartakovsky
Abstract:
We introduce the concept of a Graph-Informed Neural Network (GINN), a hybrid approach combining deep learning with probabilistic graphical models (PGMs) that acts as a surrogate for physics-based representations of multiscale and multiphysics systems. GINNs address the twin challenges of removing intrinsic computational bottlenecks in physics-based models and generating large data sets for estimat…
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We introduce the concept of a Graph-Informed Neural Network (GINN), a hybrid approach combining deep learning with probabilistic graphical models (PGMs) that acts as a surrogate for physics-based representations of multiscale and multiphysics systems. GINNs address the twin challenges of removing intrinsic computational bottlenecks in physics-based models and generating large data sets for estimating probability distributions of quantities of interest (QoIs) with a high degree of confidence. Both the selection of the complex physics learned by the NN and its supervised learning/prediction are informed by the PGM, which includes the formulation of structured priors for tunable control variables (CVs) to account for their mutual correlations and ensure physically sound CV and QoI distributions. GINNs accelerate the prediction of QoIs essential for simulation-based decision-making where generating sufficient sample data using physics-based models alone is often prohibitively expensive. Using a real-world application grounded in supercapacitor-based energy storage, we describe the construction of GINNs from a Bayesian network-embedded homogenized model for supercapacitor dynamics, and demonstrate their ability to produce kernel density estimates of relevant non-Gaussian, skewed QoIs with tight confidence intervals.
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Submitted 26 June, 2020;
originally announced June 2020.
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Frequency measurements and self-broadening of sub-Doppler transitions in the $v_1+v_3$ band of C$_2$H$_2$
Authors:
Sylvestre Twagirayezu,
Gregory E. Hall,
Trevor J. Sears
Abstract:
Frequency comb-referenced measurements of sub-Doppler laser saturation dip absorption lines in the $v_1+v_3$ band of acetylene near $1.5\,μ\mathrm{m}$ are reported. These measurements include transitions involving higher rotational levels than previously frequency measured in this band. The accuracy of the measured frequencies is typically better than 10 kHz. Measurements of the observed sub-Doppl…
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Frequency comb-referenced measurements of sub-Doppler laser saturation dip absorption lines in the $v_1+v_3$ band of acetylene near $1.5\,μ\mathrm{m}$ are reported. These measurements include transitions involving higher rotational levels than previously frequency measured in this band. The accuracy of the measured frequencies is typically better than 10 kHz. Measurements of the observed sub-Doppler line widths as a function of pressure showed that the self pressure-broadening coefficients are about 3.5 times larger than those derived from conventional pressure broadening of unsaturated Doppler-limited spectra. This is attributed to the contribution of velocity-changing collisions to the total dephasing rate in the low pressure sub-Doppler measurements. At higher pressures, when the homogeneous broadening becomes comparable to the typical Doppler shift per elastic collision, the velocity changing collisions cease to contribute significantly to the incremental pressure broadening. A time-dependent soft collision model is developed to illustrate the transition between low and high pressure regimes of sub-Doppler pressure-broadening.
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Submitted 7 March, 2020;
originally announced March 2020.
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Vertex-Finding and Reconstruction of Contained Two-track Neutrino Events in the MicroBooNE Detector
Authors:
MicroBooNE collaboration,
P. Abratenko,
M. Alrashed,
R. An,
J. Anthony,
J. Asaadi,
A. Ashkenazi,
S. Balasubramanian,
B. Baller,
C. Barnes,
G. Barr,
V. Basque,
L. Bathe-Peters,
S. Berkman,
A. Bhanderi,
A. Bhat,
M. Bishai,
A. Blake,
T. Bolton,
L. Camilleri,
D. Caratelli,
I. Caro Terrazas,
R. Castillo Fernandez,
F. Cavanna,
G. Cerati
, et al. (164 additional authors not shown)
Abstract:
We describe algorithms developed to isolate and accurately reconstruct two-track events that are contained within the MicroBooNE detector. This method is optimized to reconstruct two tracks of lengths longer than 5 cm. This code has applications to searches for neutrino oscillations and measurements of cross sections using quasi-elastic-like charged current events. The algorithms we discuss will b…
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We describe algorithms developed to isolate and accurately reconstruct two-track events that are contained within the MicroBooNE detector. This method is optimized to reconstruct two tracks of lengths longer than 5 cm. This code has applications to searches for neutrino oscillations and measurements of cross sections using quasi-elastic-like charged current events. The algorithms we discuss will be applicable to all detectors running in Fermilab's Short Baseline Neutrino program (SBN), and to any future liquid argon time projection chamber (LArTPC) experiment with beam energies ~1 GeV. The algorithms are publicly available on a GITHUB repository. This reconstruction offers a complementary and independent alternative to the Pandora reconstruction package currently in use in LArTPC experiments, and provides similar reconstruction performance for two-track events.
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Submitted 7 December, 2020; v1 submitted 21 February, 2020;
originally announced February 2020.
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A Cryogenic Silicon Interferometer for Gravitational-wave Detection
Authors:
Rana X Adhikari,
Odylio Aguiar,
Koji Arai,
Bryan Barr,
Riccardo Bassiri,
Garilynn Billingsley,
Ross Birney,
David Blair,
Joseph Briggs,
Aidan F Brooks,
Daniel D Brown,
Huy-Tuong Cao,
Marcio Constancio,
Sam Cooper,
Thomas Corbitt,
Dennis Coyne,
Edward Daw,
Johannes Eichholz,
Martin Fejer,
Andreas Freise,
Valery Frolov,
Slawomir Gras,
Anna Green,
Hartmut Grote,
Eric K Gustafson
, et al. (86 additional authors not shown)
Abstract:
The detection of gravitational waves from compact binary mergers by LIGO has opened the era of gravitational wave astronomy, revealing a previously hidden side of the cosmos. To maximize the reach of the existing LIGO observatory facilities, we have designed a new instrument that will have 5 times the range of Advanced LIGO, or greater than 100 times the event rate. Observations with this new inst…
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The detection of gravitational waves from compact binary mergers by LIGO has opened the era of gravitational wave astronomy, revealing a previously hidden side of the cosmos. To maximize the reach of the existing LIGO observatory facilities, we have designed a new instrument that will have 5 times the range of Advanced LIGO, or greater than 100 times the event rate. Observations with this new instrument will make possible dramatic steps toward understanding the physics of the nearby universe, as well as observing the universe out to cosmological distances by the detection of binary black hole coalescences. This article presents the instrument design and a quantitative analysis of the anticipated noise floor.
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Submitted 9 June, 2020; v1 submitted 29 January, 2020;
originally announced January 2020.
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A Wavelet Approach for the Estimation of Left Ventricular Early Filling Wave Propagation Velocity from Color-M-Mode Echocardiograms
Authors:
Sreyashi Chakraborty,
Hiroyuki Iwano,
Michael E. Hall,
Pavlos P. Vlachos
Abstract:
Objective: This work evaluates a new approach for calculating the left-ventricular (LV) early filling propagation velocity (VP) from color M-Mode (CMM) echocardiograms using wavelet analysis. Unlike current approaches, the method requires no assumptions, user inputs, or heuristic conventions. Background: Current methods for measuring VP using CMM echocardiography do not account for the spatiotempo…
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Objective: This work evaluates a new approach for calculating the left-ventricular (LV) early filling propagation velocity (VP) from color M-Mode (CMM) echocardiograms using wavelet analysis. Unlike current approaches, the method requires no assumptions, user inputs, or heuristic conventions. Background: Current methods for measuring VP using CMM echocardiography do not account for the spatiotemporal variation of the filling wave propagation velocity. They are instead confined by empirical assumptions and user inputs that significantly hinder the accuracy of VP, subsequently limiting its clinical utility. Methods: We evaluated three methods for measuring LV early filling VP: conventional VP, the strength of propagation (VS), and VP determined from the most energetically important wave (Peak-VW), using 125 patients (Group A) with normal filling (n=50), impaired relaxation (n=25), pseudonormal filling (n=25) and restrictive filling (n=25), and in 69 patients (Group B) with normal (n=32), dilated (n=15), and hypertrophic ventricles (n=22). Results: Peak-VW most accurately distinguished normal left ventricles from diseased ones. Specifically, for Group A which spanned the stages of diastolic function, using receiver operator characteristics (ROC) and measuring their corresponding area under the curve (AUC), the AUC for Peak-VW was 0.92, versus 0.62 for conventional VP, 0.63 for VS and 0.58 for intraventricular pressure difference (IVPD). These correspond to a 50-70% improvement in classification ability. Similar improvements were found using Group B. Conclusion: A new determination of the LV early filling using wavelet analysis, Peak-VW, may provide a more accurate evaluation of diastolic function than the standard method of determining Vp and enable better diagnostic classification of patients suffering with diastolic dysfunction.
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Submitted 25 October, 2019;
originally announced October 2019.
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Analysis of the $\tilde{A}-\tilde{X}$ bands of the Ethynyl Radical near 1.48$μ$m and Re-evaluation of $\tilde{X}$ State Energies
Authors:
Anh T. Le,
Eisen C. Gross,
Gregory E. Hall,
Trevor. J. Sears
Abstract:
We report the observation and analysis of spectra in part of the near-infrared spectrum of C$_2$H, originating in rotational levels in the ground and lowest two excited bending vibrational levels of the ground $\tilde{X}\,^2Σ^+$ state. In the analysis, we have combined present and previously reported high resolution spectroscopic data for the lower levels involved in the transitions to determine s…
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We report the observation and analysis of spectra in part of the near-infrared spectrum of C$_2$H, originating in rotational levels in the ground and lowest two excited bending vibrational levels of the ground $\tilde{X}\,^2Σ^+$ state. In the analysis, we have combined present and previously reported high resolution spectroscopic data for the lower levels involved in the transitions to determine significantly improved molecular constants to describe the fine and hyperfine split rotational levels of the radical in the zero point, $v_2=1$ and the $^2Σ^+$ component of $v_2=2$. Two of the upper state vibronic levels involved had not been observed previously. The data and analysis indicate the electronic wavefunction character changes with bending vibrational excitation in the ground state and provide avenues for future measurements of reactivity of the radical as a function of vibrational excitation.
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Submitted 15 March, 2018;
originally announced March 2018.
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Quantum correlation measurements in interferometric gravitational wave detectors
Authors:
D. V. Martynov,
V. V. Frolov,
S. Kandhasamy,
K. Izumi,
H. Miao,
N. Mavalvala,
E. D. Hall,
R. Lanza,
B. P. Abbott,
R. Abbott,
T. D. Abbott,
C. Adams,
R. X. Adhikari,
S. B. Anderson,
A. Ananyeva,
S. Appert,
K. Arai,
S. M. Aston,
S. W. Ballmer,
D. Barker,
B. Barr,
L. Barsotti,
J. Bartlett,
I. Bartos,
J. C. Batch
, et al. (177 additional authors not shown)
Abstract:
Quantum fluctuations in the phase and amplitude quadratures of light set limitations on the sensitivity of modern optical instruments. The sensitivity of the interferometric gravitational wave detectors, such as the Advanced Laser Interferometer Gravitational wave Observatory (LIGO), is limited by quantum shot noise, quantum radiation pressure noise, and a set of classical noises. We show how the…
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Quantum fluctuations in the phase and amplitude quadratures of light set limitations on the sensitivity of modern optical instruments. The sensitivity of the interferometric gravitational wave detectors, such as the Advanced Laser Interferometer Gravitational wave Observatory (LIGO), is limited by quantum shot noise, quantum radiation pressure noise, and a set of classical noises. We show how the quantum properties of light can be used to distinguish these noises using correlation techniques. Particularly, in the first part of the paper we show estimations of the coating thermal noise and gas phase noise, hidden below the quantum shot noise in the Advanced LIGO sensitivity curve. We also make projections on the observatory sensitivity during the next science runs. In the second part of the paper we discuss the correlation technique that reveals the quantum radiation pressure noise from the background of classical noises and shot noise. We apply this technique to the Advanced LIGO data, collected during the first science run, and experimentally estimate the quantum correlations and quantum radiation pressure noise in the interferometer for the first time.
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Submitted 10 February, 2017;
originally announced February 2017.
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The near-infrared spectrum of ethynyl radical
Authors:
Anh T. Le,
Gregory E. Hall,
Trevor J. Sears
Abstract:
Transient diode laser absorption spectroscopy has been used to measure three strong vibronic bands in the near infrared spectrum of the C$_2$H, ethynyl, radical not previously observed in the gas phase. The radical was produced by ultraviolet excimer laser photolysis of either acetylene or (1,1,1)-trifluoropropyne in a slowly flowing sample of the precursor diluted in inert gas, and the spectral r…
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Transient diode laser absorption spectroscopy has been used to measure three strong vibronic bands in the near infrared spectrum of the C$_2$H, ethynyl, radical not previously observed in the gas phase. The radical was produced by ultraviolet excimer laser photolysis of either acetylene or (1,1,1)-trifluoropropyne in a slowly flowing sample of the precursor diluted in inert gas, and the spectral resolution was Doppler-limited. The character of the upper states was determined from the rotational and fine structure in the observed spectra and assigned by measurement of ground state rotational combination differences. The upper states include a $^2Σ^+$ state at 6696 cm$^{-1}$, a second $^2Σ^+$ state at 7088 cm$^{-1}$, and a $^2Π$ state at 7110 cm$^{-1}$. By comparison with published calculations (R. Tarroni and S. Carter, \textit{J. Chem. Phys} \textbf{119}, 12878 (2003) and \textit{Mol. Phys}. \textbf{102}, 2167 (2004)), the vibronic character of these levels was also assigned. The observed states contain both $X^2Σ^+$ and $A^2Π$ electronic character. Several local rotational level perturbations were observed in the excited states. Kinetic measurements of the time-evolution of the ground state populations following collisional relaxation and reactive loss of the radicals formed in a hot, non-thermal, population distribution were made using some of the strong rotational lines observed. The case of C$ _{2} $H may be a good place to investigate the behavior at intermediate pressures of inert colliders, where the competition between relaxation and reaction can be tuned and observed to compare with master equation models, rather than deliberately suppressed to measure thermal rate constants.
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Submitted 8 August, 2016;
originally announced August 2016.
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Quadrupole Splittings in the near-infrared spectrum of $^{14}$NH$_3$
Authors:
Sylvestre Twagirayezu,
Gregory E. Hall,
Trevor J. Sears
Abstract:
Sub-Doppler, saturation dip, spectra of lines in the $v_1 + v_3$, $v_1 + 2v_4$ and $v_3 + 2v_4$ bands of $^{14}$NH$_3$ have been measured by frequency comb-referenced diode laser absorption spectroscopy. The observed spectral line widths are dominated by transit time broadening, but show resolved or partially-resolved hyperfine splittings that are primarily determined by the $^{14}$N quadrupole co…
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Sub-Doppler, saturation dip, spectra of lines in the $v_1 + v_3$, $v_1 + 2v_4$ and $v_3 + 2v_4$ bands of $^{14}$NH$_3$ have been measured by frequency comb-referenced diode laser absorption spectroscopy. The observed spectral line widths are dominated by transit time broadening, but show resolved or partially-resolved hyperfine splittings that are primarily determined by the $^{14}$N quadrupole coupling. Modeling of the observed line shapes based on the known hyperfine level structure of the ground state of the molecule shows that, in nearly all cases, the excited state level has hyperfine splittings similar to the same rotational level in the ground state. The data provide accurate frequencies for the line positions and easily separate lines overlapped in Doppler-limited spectra. The observed hyperfine splittings can be used to make and confirm rotational assignments and ground state combination differences obtained from the measured frequencies are comparable in accuracy to those obtained from conventional microwave spectroscopy. One upper state level shows very clear differences from the expected splittings. Examination of the known vibration-rotation level structure shows there is a near degeneracy between this level in $v_1+v_3$ and a rotational level in the $v_1 + 2v_4$ manifold which is of the appropriate symmetry to be mixed by magnetic hyperfine terms that couple ortho- and para- forms of the molecule.
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Submitted 23 September, 2016; v1 submitted 6 July, 2016;
originally announced July 2016.
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The Sensitivity of the Advanced LIGO Detectors at the Beginning of Gravitational Wave Astronomy
Authors:
D. V. Martynov,
E. D. Hall,
B. P. Abbott,
R. Abbott,
T. D. Abbott,
C. Adams,
R. X. Adhikari,
R. A. Anderson,
S. B. Anderson,
K. Arai,
M. A. Arain,
S. M. Aston,
L. Austin,
S. W. Ballmer,
M. Barbet,
D. Barker,
B. Barr,
L. Barsotti,
J. Bartlett,
M. A. Barton,
I. Bartos,
J. C. Batch,
A. S. Bell,
I. Belopolski,
J. Bergman
, et al. (239 additional authors not shown)
Abstract:
The Laser Interferometer Gravitational Wave Observatory (LIGO) consists of two widely separated 4 km laser interferometers designed to detect gravitational waves from distant astrophysical sources in the frequency range from 10 Hz to 10 kHz. The first observation run of the Advanced LIGO detectors started in September 2015 and ended in January 2016. A strain sensitivity of better than…
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The Laser Interferometer Gravitational Wave Observatory (LIGO) consists of two widely separated 4 km laser interferometers designed to detect gravitational waves from distant astrophysical sources in the frequency range from 10 Hz to 10 kHz. The first observation run of the Advanced LIGO detectors started in September 2015 and ended in January 2016. A strain sensitivity of better than $10^{-23}/\sqrt{\text{Hz}}$ was achieved around 100 Hz. Understanding both the fundamental and the technical noise sources was critical for increasing the observable volume in the universe. The average distance at which coalescing binary black hole systems with individual masses of 30 $M_\odot$ could be detected was 1.3 Gpc. Similarly, the range for binary neutron star inspirals was about 75 Mpc. With respect to the initial detectors, the observable volume of Universe increased respectively by a factor 69 and 43. These improvements allowed Advanced LIGO to detect the gravitational wave signal from the binary black hole coalescence, known as GW150914.
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Submitted 10 February, 2018; v1 submitted 1 April, 2016;
originally announced April 2016.
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Plasma observations during the Mars atmospheric "plume" event of March-April 2012
Authors:
D. J. Andrews,
S. Barabash,
N. J. T. Edberg,
D. A. Gurnett,
B. E. S. Hall,
M. Holmström,
M. Lester,
D. D. Morgan,
H. J. Opgenoorth,
R. Ramstad,
B. Sanchez-Cano,
M. Way,
O. Witasse
Abstract:
We present initial analysis and conclusions from plasma observations made during the reported "Mars plume event" of March - April 2012. During this period, multiple independent amateur observers detected a localized, high-altitude "plume" over the Martian dawn terminator [Sanchez-Lavega et al., Nature, 2015, doi:10.1038/nature14162], the cause of which remains to be explained. The estimated bright…
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We present initial analysis and conclusions from plasma observations made during the reported "Mars plume event" of March - April 2012. During this period, multiple independent amateur observers detected a localized, high-altitude "plume" over the Martian dawn terminator [Sanchez-Lavega et al., Nature, 2015, doi:10.1038/nature14162], the cause of which remains to be explained. The estimated brightness of the plume exceeds that expected for auroral emissions, and its projected altitude greatly exceeds that at which clouds are expected to form. We report on in-situ measurements of ionospheric plasma density and solar wind parameters throughout this interval made by Mars Express, obtained over the same surface region, but at the opposing terminator. Measurements in the ionosphere at the corresponding location frequently show a disturbed structure, though this is not atypical for such regions with intense crustal magnetic fields. We tentatively conclude that the formation and/or transport of this plume to the altitudes where it was observed could be due in part to the result of a large interplanetary coronal mass ejection (ICME) encountering the Martian system. Interestingly, we note that the only similar plume detection in May 1997 may also have been associated with a large ICME impact at Mars.
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Submitted 18 March, 2016;
originally announced March 2016.
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Calibration of the Advanced LIGO detectors for the discovery of the binary black-hole merger GW150914
Authors:
The LIGO Scientific Collaboration,
B. P. Abbott,
R. Abbott,
T. D. Abbott,
M. R. Abernathy,
K. Ackley,
C. Adams,
P. Addesso,
R. X. Adhikari,
V. B. Adya,
C. Affeldt,
N. Aggarwal,
O. D. Aguiar,
A. Ain,
P. Ajith,
B. Allen,
P. A. Altin,
D. V. Amariutei,
S. B. Anderson,
W. G. Anderson,
K. Arai,
M. C. Araya,
C. C. Arceneaux,
J. S. Areeda,
K. G. Arun
, et al. (702 additional authors not shown)
Abstract:
In Advanced LIGO, detection and astrophysical source parameter estimation of the binary black hole merger GW150914 requires a calibrated estimate of the gravitational-wave strain sensed by the detectors. Producing an estimate from each detector's differential arm length control loop readout signals requires applying time domain filters, which are designed from a frequency domain model of the detec…
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In Advanced LIGO, detection and astrophysical source parameter estimation of the binary black hole merger GW150914 requires a calibrated estimate of the gravitational-wave strain sensed by the detectors. Producing an estimate from each detector's differential arm length control loop readout signals requires applying time domain filters, which are designed from a frequency domain model of the detector's gravitational-wave response. The gravitational-wave response model is determined by the detector's opto-mechanical response and the properties of its feedback control system. The measurements used to validate the model and characterize its uncertainty are derived primarily from a dedicated photon radiation pressure actuator, with cross-checks provided by optical and radio frequency references. We describe how the gravitational-wave readout signal is calibrated into equivalent gravitational-wave-induced strain and how the statistical uncertainties and systematic errors are assessed. Detector data collected over 38 calendar days, from September 12 to October 20, 2015, contain the event GW150914 and approximately 16 of coincident data used to estimate the event false alarm probability. The calibration uncertainty is less than 10% in magnitude and 10 degrees in phase across the relevant frequency band 20 Hz to 1 kHz.
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Submitted 28 February, 2017; v1 submitted 11 February, 2016;
originally announced February 2016.
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Passive, free-space laser gyroscope
Authors:
W. Zach Korth,
Alastair Heptonstall,
Evan D. Hall,
Koji Arai,
Eric K. Gustafson,
Rana X. Adhikari
Abstract:
Laser gyroscopes making use of the Sagnac effect have been used as highly accurate rotation sensors for many years. First used in aerospace and defense applications, these devices have more recently been used for precision seismology and in other research settings. In particular, mid-sized (~1 m-scale) laser gyros have been under development as tilt sensors to augment the adaptive active seismic i…
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Laser gyroscopes making use of the Sagnac effect have been used as highly accurate rotation sensors for many years. First used in aerospace and defense applications, these devices have more recently been used for precision seismology and in other research settings. In particular, mid-sized (~1 m-scale) laser gyros have been under development as tilt sensors to augment the adaptive active seismic isolation systems in terrestrial interferometric gravitational wave detectors. The most prevalent design is the "active" gyroscope, in which the optical ring cavity used to measure the Sagnac degeneracy breaking is itself a laser resonator. In this article, we describe another topology: a "passive" gyroscope, in which the sensing cavity is not itself a laser but is instead tracked using external laser beams. While subject to its own limitations, this design is free from the deleterious lock-in effects observed in active systems, and has the advantage that it can be constructed using commercially available components. We demonstrate that our device achieves comparable sensitivity to those of similarly sized active laser gyroscopes.
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Submitted 27 August, 2015;
originally announced August 2015.
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Coherent Cancellation of Photothermal Noise in GaAs/Al$_{0.92}$Ga$_{0.08}$As Bragg Mirrors
Authors:
Tara Chalermsongsak,
Evan D. Hall,
Garrett D. Cole,
David Follman,
Frank Seifert,
Koji Arai,
Eric K. Gustafson,
Joshua R. Smith,
Markus Aspelmeyer,
Rana X Adhikari
Abstract:
Thermal noise is a limiting factor in many high-precision optical experiments. A search is underway for novel optical materials with reduced thermal noise. One such pair of materials, gallium arsenide and aluminum-alloyed gallium arsenide (collectively referred to as AlGaAs), shows promise for its low Brownian noise when compared to conventional materials such as silica and tantala. However, AlGaA…
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Thermal noise is a limiting factor in many high-precision optical experiments. A search is underway for novel optical materials with reduced thermal noise. One such pair of materials, gallium arsenide and aluminum-alloyed gallium arsenide (collectively referred to as AlGaAs), shows promise for its low Brownian noise when compared to conventional materials such as silica and tantala. However, AlGaAs has the potential to produce a high level of thermo-optic noise. We have fabricated a set of AlGaAs crystalline coatings, transferred to fused silica substrates, whose layer structure has been optimized to reduce thermo-optic noise by inducing coherent cancellation of the thermoelastic and thermorefractive effects. By measuring the photothermal transfer function of these mirrors, we find evidence that this optimization has been successful.
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Submitted 26 October, 2015; v1 submitted 23 June, 2015;
originally announced June 2015.
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Broadband Measurement of Coating Thermal Noise in Rigid Fabry-Perot Cavities
Authors:
Tara Chalermsongsak,
Frank Seifert,
Evan D. Hall,
Koji Arai,
Eric K. Gustafson,
Rana X. Adhikari
Abstract:
We report on the relative length fluctuation of two fixed-spacer Fabry-Perot cavities with mirrors fabricated from silica/tantala dielectric coatings on fused silica substrates. By locking a laser to each cavity and reading out the beat note $\hatν = ν_1 - ν_2$ of the transmitted beams, we find that, for frequencies from 10 Hz to 1 kHz, the amplitude spectral density of beat note fluctuation is…
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We report on the relative length fluctuation of two fixed-spacer Fabry-Perot cavities with mirrors fabricated from silica/tantala dielectric coatings on fused silica substrates. By locking a laser to each cavity and reading out the beat note $\hatν = ν_1 - ν_2$ of the transmitted beams, we find that, for frequencies from 10 Hz to 1 kHz, the amplitude spectral density of beat note fluctuation is $\sqrt{S_\hatν(f)} = (0.5\,\mathrm{Hz})/f^{1/2}$. By careful budgeting of noise sources contributing to the beat note, we find that our measurement is consistent with the fluctuation in this band being dominated by the Brownian noise of the mirror coatings. Fitting for the coating loss angle $φ_\mathrm{c}$, we find it equal to $4\times10^{-4}$. We then use a Bayesian analysis to combine our measurement with previous observations, and thereby extract estimates for the individual loss angles of silica and tantala. It is hoped that the testbed described in this article can be used in the future to measure the length noise of cavities formed with novel mirror materials and geometries.
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Submitted 17 June, 2014;
originally announced June 2014.
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The D0 Silicon Microstrip Tracker
Authors:
S. N. Ahmed,
R. Angstadt,
M. Aoki,
B. Åsman,
S. Austin,
L. Bagby,
E. Barberis,
P. Baringer,
A. Bean,
A. Bischoff,
F. Blekman,
T. A. Bolton,
C. Boswell,
M. Bowden,
F. Browning,
D. Buchholz,
S. Burdin,
D. Butler,
H. Cease,
S. Choi,
A. R. Clark,
J. Clutter,
A. Cooper,
W. E. Cooper,
M. Corcoran
, et al. (109 additional authors not shown)
Abstract:
This paper describes the mechanical design, the readout chain, the production, testing and the installation of the Silicon Microstrip Tracker of the D0 experiment at the Fermilab Tevatron collider. In addition, description of the performance of the detector during the experiment data collection between 2001 and 2010 is provided.
This paper describes the mechanical design, the readout chain, the production, testing and the installation of the Silicon Microstrip Tracker of the D0 experiment at the Fermilab Tevatron collider. In addition, description of the performance of the detector during the experiment data collection between 2001 and 2010 is provided.
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Submitted 5 May, 2010;
originally announced May 2010.