About

Janet Conrad is a Professor of Physics at MIT with a research focus on neutrinos, the lightest known matter particles, which outnumber atoms in the universe. Her work explores the properties of neutrinos, including their mass and oscillation behavior, which challenge the Standard Model of particle physics. Conrad's research involves testing for new features of neutrinos through experiments such as MicroBooNE at Fermilab, which searches for a potential new neutrino beyond the three known types, motivated by anomalies observed in previous experiments like LSND. She also investigates astrophysical neutrinos using the IceCube experiment at the South Pole, searching for sterile neutrinos and other Beyond Standard Model phenomena. Additionally, her group develops high power cyclotrons to create decay-at-rest neutrino sources for precision studies. Conrad received her B.A. from Swarthmore College, her M.Sc. from Oxford University, and her Ph.D. from Harvard. She has held positions at Columbia University, where she was the Walter O. Lecroy Professor of Physics, and has been recognized with numerous awards including the Guggenheim Fellowship, the APS Fellowship, and the Maria Goeppert Mayer Award for her leadership in experimental neutrino physics.

Research topics

• Physics
• Particle physics
• Nuclear physics
• Astronomy
• Astrophysics
• Computer Science
• Optics
• Artificial Intelligence
• Machine Learning
• Environmental science
• Electronic engineering
• Engineering
• Algorithm
• Statistics
• Earth science
• Mathematics
• Telecommunications
• Remote sensing
• Classical mechanics
• Geology
• Systems engineering
• Atomic physics

Selected publications

• Beyond Single Models: Unsupervised Ensemble Selection for Small Language Models in Medical QA

  OJS · 2026-03-27

  articleOpen accessSenior author

  Small Language Models (SLMs) provide efficient alternatives to large models for clinical open-ended question answering (QA) but often show variable performance. We propose two unsupervised answer selection strategies for SLM ensembles: a confidence-based method using normalized perplexity and a consensus-based medoid method capturing semantic similarity among model outputs. Evaluations on three clinical QA benchmarks show that both strategies outperform single-model and random selection baselines. The results show that unsupervised confidence and consensus mechanisms can enhance the performance of SLM ensembles for medical QA without requiring additional training or increasing model size.

  PublisherDOI

• Probing neutrino emission at GeV energies from compact binary mergers with the IceCube Neutrino Observatory

  Physical review. D/Physical review. D. · 2026-01-20 · 12 citations

  preprintOpen access

  The advent of multi-messenger astronomy has allowed for new types of source searches by neutrino detectors. We present the results of the search for 0.5-100 GeV astrophysical neutrinos detected with IceCube and emitted from compact binary mergers detected by the LIGO, Virgo, and KAGRA interferometers from their first run of observation (O1) to the end of the first part of the fourth (O4a). An innovative approach is used to lower the energy threshold to 0.5 GeV and to search for an excess of GeV neutrinos in time coincidence with astrophysical transient events. Furthermore, we use a statistical combination of all observations, a binomial test, to search for a subpopulation of neutrino emitters. No significant excess was found from the studied mergers, with a best post-trial $p$-value of $40\%$, and there is currently no hint of a population of GeV neutrino emitters found in the IceCube data (post-trial $p$-value = $81\%$).

  PublisherOA PDFDOI

• Evidence for Neutrino Emission from X-Ray-bright Active Galactic Nuclei with IceCube

  The Astrophysical Journal Letters · 2026-03-18 · 4 citations

  articleOpen access

  Abstract Recently, IceCube reported neutrino emission from the Seyfert galaxy NGC 1068. Using 13.1 yr of IceCube data, we present a follow-up search for neutrino sources in the northern sky. NGC 1068 remains the most significant neutrino source among 110 preselected gamma-ray emitters while also being spatially compatible with the most significant location in the northern sky. Its energy spectrum is characterized by an unbroken power-law with spectral index γ = 3.4 ± 0.2. Consistent with previous results, the observed neutrino flux exceeds its gamma-ray counterpart by at least 2 orders of magnitude. Motivated by this disparity and the high X-ray luminosity of the source, we selected 47 X-ray-bright Seyfert galaxies from the Swift/BAT spectroscopic survey that were not included in the list of gamma-ray emitters. When testing this collection for neutrino emission, we observe a 3.3 σ excess from an ensemble of 11 sources, with NGC 1068 excluded from the sample. Our results strengthen the evidence that X-ray-bright cores of active galactic nuclei are neutrino emitters.

  PublisherDOI

• Spiral tuning of wire-metamaterial cavity for a plasma haloscope

  Physical Review Applied · 2026-01-28

  articleOpen access

  Axions are hypothetical particles that provide a compelling solution to two major mysteries in modern physics: the strong CP problem and the nature of dark matter. The plasma haloscope has been proposed as a promising approach for probing the higher-mass regime for dark-matter axions by employing a periodic arrangement of conducting wires. In this work, we introduce an alternative tuning mechanism for such wire-based structures by arranging the wires into a spiral configuration. This design enables continuous frequency tuning of 25% with a single central rotation while maintaining the form factor. It also achieves scanning speeds several times faster than traditional tuning approaches, primarily due to the circular perimeter geometry, making it well suited for solenoidal magnet bores. To validate the concept, we fabricated a prototype cavity with six spiral arms and experimentally demonstrated its feasibility, obtaining frequency tuning in close agreement with numerical simulations.

  PublisherDOI

• Inclusive Search for Anomalous Single-Photon Production in MicroBooNE

  Physical Review Letters · 2026-04-09 · 2 citations

  preprintOpen access

  We present an inclusive search for anomalous production of single-photon events from neutrino interactions in the MicroBooNE experiment. The search and its signal definition are motivated by the previous observation of a low-energy excess of electromagnetic shower events from the MiniBooNE experiment. We use the Wire-Cell reconstruction framework to select a sample of inclusive single-photon final-state interactions with a final efficiency and purity of 7.0% and 40.2%, respectively. We leverage simultaneous measurements of sidebands of charged current ν_{μ} interactions and neutral current interactions producing π^{0} mesons to constrain signal and background predictions and reduce uncertainties. We perform a blind analysis using a dataset collected from February 2016 to July 2018, corresponding to an exposure of 6.34×10^{20} protons on target from the Booster Neutrino Beam at Fermilab. In the full signal region, we observe agreement between the data and the prediction, with a goodness-of-fit p value of 0.11. We then isolate a subsample of these events containing no visible protons, and observe 93±22(stat)±35(syst) data events above prediction, corresponding to just above 2σ local significance, concentrated at shower energies below 600 MeV.

  PublisherDOI

• First Event-by-Event Identification of Cherenkov Radiation from Sub-Mev Particles in Liquid Argon

  Physical Review Letters · 2025-09-29 · 1 citations

  article

  This Letter reports the event-by-event observation of Cherenkov light from sub-MeV electrons in a high scintillation light-yield liquid argon detector by the coherent CAPTAIN-Mills (CCM) experiment. The CCM200 detector, located at Los Alamos National Laboratory, instruments seven tons (fiducial volume) of liquid argon with 200 eight-inch photomultiplier tubes, 80% of which are coated in a wavelength-shifting material and the remaining 20% are uncoated. In the prompt time region of an event, defined as -6≤t<0 ns relative to the event start time t=0, the uncoated photomultiplier tubes are primarily sensitive to visible Cherenkov photons. Using gamma rays from a ^{22}Na source for production of sub-MeV electrons, we isolated prompt Cherenkov light with >5σ confidence and developed a selection to obtain a low-background electromagnetic sample. This is the first event-by-event observation of Cherenkov photons from sub-MeV electrons in a high-yield scintillator detector and represents a milestone in low-energy particle detector development.

  PublisherDOI

• Search for light sterile neutrinos with two neutrino beams at MicroBooNE

  Nature · 2025-12-03 · 5 citations

  articleOpen access

  Abstract The existence of three distinct neutrino flavours, ν e , ν μ and ν τ , is a central tenet of the Standard Model of particle physics 1,2 . Quantum-mechanical interference can allow a neutrino of one initial flavour to be detected sometime later as a different flavour, a process called neutrino oscillation. Several anomalous observations inconsistent with this three-flavour picture have motivated the hypothesis that an additional neutrino state exists, which does not interact directly with matter, termed as ‘sterile’ neutrino, ν s (refs. 3–9 ). This includes anomalous observations from the Liquid Scintillator Neutrino Detector (LSND) 3 experiment and Mini-Booster Neutrino Experiment (MiniBooNE) 4,5 , consistent with ν μ → ν e transitions at a distance inconsistent with the three-neutrino picture. Here we use data obtained from the MicroBooNE liquid-argon time projection chamber 10 in two accelerator neutrino beams to exclude the single light sterile neutrino interpretation of the LSND and MiniBooNE anomalies at the 95% confidence level (CL). Moreover, we rule out a notable portion of the parameter space that could explain the gallium anomaly 6–8 . This is one of the first measurements to use two accelerator neutrino beams to break a degeneracy between ν e appearance and disappearance, which would otherwise weaken the sensitivity to the sterile neutrino hypothesis. We find no evidence for either ν μ → ν e flavour transitions or ν e disappearance that would indicate non-standard flavour oscillations. Our results indicate that previous anomalous observations consistent with ν μ → ν e transitions cannot be explained by introducing a single sterile neutrino state.

  PublisherOA PDFDOI

• Combining IceCube Muon Tracks and Cascades to measure the Galactic Diffuse Neutrino Flux

  2025-09-24

  articleOpen access

  The diffuse Galactic neutrino flux is produced by cosmic rays interacting with the interstellar medium. The measurement of this flux can help to understand the distribution of cosmic rays in the Galaxy. The first observation of this neutrino flux was published in 2023 by the IceCube Collaboration. Here, plans for a new analysis combining different event topologies are presented. IceCube measures events in two main topologies. Tracks, originating in charged current 𝜈𝜇 interactions, provide a better angular resolution. In contrast, cascades, from most other possible interactions, provide a better energy resolution and are able to observe the Southern sky (and therefore the Galactic Center) despite the huge background of atmospheric muons. Combining both event topologies in one analysis exploits all these advantages. Sensitivities and model discrimination power of a combined measurement using a forward folding binned likelihood fit are discussed here.

  PublisherOA PDFDOI

• Sustainability and Environmental Impact of IceCube-Gen2

  2025-09-24

  articleOpen access

  IceCube-Gen2 is a proposed next-generation neutrino facility at the South Pole, designed to expand upon the achievements of the pioneering IceCube observatory. This contribution provides a comprehensive review of efforts to ensure the sustainability of IceCube-Gen2 and minimize its environmental impact in Antarctica. Scenarios for overcoming logistical challenges in detector construction and operations are explored, including the potential use of renewable energy sources such as wind and solar. A cost-benefit analysis of energy sources for drilling will be presented. Efforts to optimize the IceCube-Gen2 drilling operations will be discussed, along with studies aimed at minimizing the power consumption of detector modules, and evaluating efficient power distribution scenarios and computing resource usage.

  PublisherOA PDFDOI

• The XLZD Design Book: towards the next-generation liquid xenon observatory for dark matter and neutrino physics

  The European Physical Journal C · 2025-10-23 · 10 citations

  articleOpen access

  Abstract This report describes the experimental strategy and technologies for XLZD, the next-generation xenon observatory sensitive to dark matter and neutrino physics. In the baseline design, the detector will have an active liquid xenon target of 60 tonnes, which could be increased to 80 tonnes if the market conditions for xenon are favorable. It is based on the mature liquid xenon time projection chamber technology used in current-generation experiments, LZ and XENONnT. The report discusses the baseline design and opportunities for further optimization of the individual detector components. The experiment envisaged here has the capability to explore parameter space for Weakly Interacting Massive Particle (WIMP) dark matter down to the neutrino fog, with a 3 $$\sigma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>σ</mml:mi> </mml:math> evidence potential for WIMP-nucleon cross sections as low as $$3\times 10^{-49}\mathrm \,cm^2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>3</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>49</mml:mn> </mml:mrow> </mml:msup> <mml:mspace/> <mml:mi>c</mml:mi> <mml:msup> <mml:mi>m</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:math> (at 40 GeV/c $$^2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mn>2</mml:mn> </mml:mmultiscripts> </mml:math> WIMP mass). The observatory will also have leading sensitivity to a wide range of alternative dark matter models. It is projected to have a 3 $$\sigma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>σ</mml:mi> </mml:math> observation potential of neutrinoless double beta decay of $$^{136}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mn>136</mml:mn> </mml:mmultiscripts> </mml:math> Xe at a half-life of up to $$5.7\times 10^{27}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>5.7</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>27</mml:mn> </mml:msup> </mml:mrow> </mml:math> years. Additionally, it is sensitive to astrophysical neutrinos from the sun and galactic supernovae.

  PublisherDOI

Recent grants

• The PA-Supported Neutrino Program at MIT

  NSF · $1.0M · 2015–2019

• Neutrino Physics at MIT

  NSF · $1.2M · 2009–2012

• The EPP Supported Neutrino Program at MIT

  NSF · $909k · 2018–2022

• EAGER: H2+ Ion Source Studies at the BEST Cyclotrons, Inc. Test Stand

  NSF · $114k · 2011–2014

• The PA-Supported Neutrino Program at MIT

  NSF · $1.2M · 2019–2024

Frequent coauthors

• M. Ackermann

  Deutsches Elektronen-Synchrotron DESY

  3377 shared

• Kwok Lung Fan

  3148 shared

• S. R. Klein

  2761 shared

• I. A. Grenier

  Centre National de la Recherche Scientifique

  2734 shared

• G. M. Spiczak

  2659 shared

• J. Vandenbroucke

  2629 shared

• U. Katz

  Providence College

  2629 shared

• G. C. Hill

  Providence College

  2627 shared

Awards & honors

• 2016 // Committed to Caring Honoree, MIT Office of Dean of G…
• 2014 // Amar G. Bose Fellowship
• 2013 // CWSP Woman Physicist of the Month, August (APS)
• 2009 // John Simon Guggenheim Fellow
• 2005-08 // Columbia Distinguished Faculty Fellow