About

David Kawall is a Professor in the Department of Physics at the University of Massachusetts Amherst. He earned his Ph.D. from Stanford University in 1996. His research interests include experimental nuclear physics and experimental atomic physics. He is involved in physics award-winning teaching, research opportunities, and interdisciplinary programs within a diverse and inclusive community of excellence. His main office is located in the Department of Physics at the University of Massachusetts Amherst, where he contributes to the academic and research environment.

Research topics

• Physics
• Nuclear physics
• Condensed matter physics
• Particle physics
• Optics
• Quantum mechanics
• Astronomy

Selected publications

• Adiabatic passage of $^{205}$TlF with microwaves in a cryogenic beam

  ArXiv.org · 2025-11-20

  preprintOpen access

  We present a hyperfine-resolved state preparation scheme for thallium fluoride (TlF) molecules based on microwave-driven adiabatic passage (AP) in a spatially varying electric field. This method enables efficient and robust population transfer between selected $\left|J,m_J=0\right\rangle$ hyperfine sublevels of the $X\,^1Σ^+_0$ ground state in a cryogenic molecular beam, a key requirement for the CeNTREX search for nuclear time-reversal symmetry violation. Two sequential stages of AP are implemented. The first transfers population from $J=0$ to $J=1$ at a local field of $173~\mathrm{V/cm}$, and the second transfers from $J=1$ to $J=2$ at $110~\mathrm{V/cm}$. Transfer efficiencies are quantified through laser-induced fluorescence, and accounting for residual population in excited rotational levels after a prior stage of rotational cooling. We achieve state transfer efficiencies of $0.92(6)$ and $1.05(5)$ for the first and second states of AP, respectively. This corresponds to a total efficiency of $0.97(8)$ for population transfer from $J=0$ to $J=2$. These results demonstrate robust and high-fidelity preparation of specific rotational/hyperfine states in TlF.

  PublisherOA PDFDOI

• Status of the Proton EDM Experiment (pEDM)

  ArXiv.org · 2025-04-17

  preprintOpen access

  The Proton EDM Experiment (pEDM) is the first direct search for the proton electric dipole moment (EDM) with the aim of being the first experiment to probe the Standard Model (SM) prediction of any particle EDM. Phase-I of pEDM will achieve $10^{-29} e\cdot$cm, improving current indirect limits by four orders of magnitude. This will establish a new standard of precision in nucleon EDM searches and offer a unique sensitivity to better understand the Strong CP problem. The experiment is ideally positioned to explore physics beyond the Standard Model (BSM), with sensitivity to axionic dark matter via the signal of an oscillating proton EDM and across a wide mass range of BSM models from $\mathcal{O}(1\text{GeV})$ to $\mathcal{O}(10^3\text{TeV})$. Utilizing the frozen-spin technique in a highly symmetric storage ring that leverages existing infrastructure at Brookhaven National Laboratory (BNL), pEDM builds upon the technological foundation and experimental expertise of the highly successful Muon $g$$-$$2$ Experiments. With significant R\&D and prototyping already underway, pEDM is preparing a conceptual design report (CDR) to offer a cost-effective, high-impact path to discovering new sources of CP violation and advancing our understanding of fundamental physics. It will play a vital role in complementing the physics goals of the next-generation collider while simultaneously contributing to sustaining particle physics research and training early-career researchers during gaps between major collider operations.

  PublisherOA PDFDOI

• Rotational-hyperfine cooling of $^{205}$TlF in a cryogenic beam

  arXiv (Cornell University) · 2025-01-09

  preprintOpen access

  The aim of CeNTREX (Cold Molecule Nuclear Time-Reversal Experiment) is to search for time-reversal symmetry violation in the thallium nucleus, by measuring the Schiff moment of $^{205}$Tl in the polar molecule thallium fluoride (TlF). CeNTREX uses a cryogenic beam of TlF with a rotational temperature of 6.3(2) K. This results in population spread over dozens of rotational and hyperfine sublevels of TlF, while only a single level is useful for the Schiff moment measurement. Here we present a protocol for cooling the rotational and hyperfine degrees of freedom in the CeNTREX beam, transferring the majority of the Boltzmann distribution into a single rotational and hyperfine sublevel by using a single ultraviolet laser and a pair of microwave beams. We achieve a factor of $20.1(4)$ gain in the population of the $J=0$, $F=0$ hyperfine sublevel of the TlF ground state.

  PublisherOA PDFDOI

• Detailed report on the measurement of the positive muon anomalous magnetic moment to 0.20 ppm

  Physical review. D/Physical review. D. · 2024-08-08 · 53 citations

  articleOpen access

  We present details on a new measurement of the muon magnetic anomaly, <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mi>a</a:mi><a:mi>μ</a:mi></a:msub><a:mo>=</a:mo><a:mo stretchy="false">(</a:mo><a:msub><a:mi>g</a:mi><a:mi>μ</a:mi></a:msub><a:mo>−</a:mo><a:mn>2</a:mn><a:mo stretchy="false">)</a:mo><a:mo>/</a:mo><a:mn>2</a:mn></a:math>. The result is based on positive muon data taken at Fermilab’s Muon Campus during the 2019 and 2020 accelerator runs. The measurement uses <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mrow><e:mn>3.1</e:mn><e:mtext> </e:mtext><e:mtext> </e:mtext><e:mi>GeV</e:mi><e:mo>/</e:mo><e:mi>c</e:mi></e:mrow></e:math> polarized muons stored in a 7.1-m-radius storage ring with a 1.45 T uniform magnetic field. The value of <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:msub><g:mi>a</g:mi><g:mi>μ</g:mi></g:msub></g:math> is determined from the measured difference between the muon spin precession frequency and its cyclotron frequency. This difference is normalized to the strength of the magnetic field, measured using nuclear magnetic resonance. The ratio is then corrected for small contributions from beam motion, beam dispersion, and transient magnetic fields. We measure <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:msub><i:mi>a</i:mi><i:mi>μ</i:mi></i:msub><i:mo>=</i:mo><i:mn>116</i:mn><i:mn>592</i:mn><i:mn>057</i:mn><i:mo stretchy="false">(</i:mo><i:mn>25</i:mn><i:mo stretchy="false">)</i:mo><i:mo>×</i:mo><i:msup><i:mn>10</i:mn><i:mrow><i:mo>−</i:mo><i:mn>11</i:mn></i:mrow></i:msup></i:math> (0.21 ppm). This is the world’s most precise measurement of this quantity and represents a factor of 2.2 improvement over our previous result based on the 2018 dataset. In combination, the two datasets yield <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:msub><m:mi>a</m:mi><m:mi>μ</m:mi></m:msub><m:mo stretchy="false">(</m:mo><m:mrow><m:mi>FNAL</m:mi></m:mrow><m:mo stretchy="false">)</m:mo><m:mo>=</m:mo><m:mn>116</m:mn><m:mn>592</m:mn><m:mn>055</m:mn><m:mo stretchy="false">(</m:mo><m:mn>24</m:mn><m:mo stretchy="false">)</m:mo><m:mo>×</m:mo><m:msup><m:mn>10</m:mn><m:mrow><m:mo>−</m:mo><m:mn>11</m:mn></m:mrow></m:msup></m:math> (0.20 ppm). Combining this with the measurements from Brookhaven National Laboratory for both positive and negative muons, the new world average is <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"><s:mrow><s:msub><s:mrow><s:mi>a</s:mi></s:mrow><s:mrow><s:mi>μ</s:mi></s:mrow></s:msub><s:mo stretchy="false">(</s:mo><s:mi>exp</s:mi><s:mo stretchy="false">)</s:mo><s:mo>=</s:mo><s:mn>116</s:mn><s:mn>592</s:mn><s:mn>059</s:mn><s:mo stretchy="false">(</s:mo><s:mn>22</s:mn><s:mo stretchy="false">)</s:mo><s:mo>×</s:mo><s:msup><s:mrow><s:mn>10</s:mn></s:mrow><s:mrow><s:mo>−</s:mo><s:mn>11</s:mn></s:mrow></s:msup></s:mrow></s:math> (0.19 ppm). Published by the American Physical Society 2024

  PublisherOA PDFDOI

• Measurement of the Positive Muon Anomalous Magnetic Moment to 0.20 ppm

  arXiv (Cornell University) · 2023-08-11 · 14 citations

  preprintOpen access

  We present a new measurement of the positive muon magnetic anomaly, $a_μ\equiv (g_μ- 2)/2$, from the Fermilab Muon $g\!-\!2$ Experiment using data collected in 2019 and 2020. We have analyzed more than 4 times the number of positrons from muon decay than in our previous result from 2018 data. The systematic error is reduced by more than a factor of 2 due to better running conditions, a more stable beam, and improved knowledge of the magnetic field weighted by the muon distribution, $\tildeω'^{}_p$, and of the anomalous precession frequency corrected for beam dynamics effects, $ω_a$. From the ratio $ω_a / \tildeω'^{}_p$, together with precisely determined external parameters, we determine $a_μ= 116\,592\,057(25) \times 10^{-11}$ (0.21 ppm). Combining this result with our previous result from the 2018 data, we obtain $a_μ\text{(FNAL)} = 116\,592\,055(24) \times 10^{-11}$ (0.20 ppm). The new experimental world average is $a_μ(\text{Exp}) = 116\,592\,059(22)\times 10^{-11}$ (0.19 ppm), which represents a factor of 2 improvement in precision.

  PublisherOA PDFDOI

• Measurement of the Positive Muon Anomalous Magnetic Moment to 0.20 ppm

  Physical Review Letters · 2023 · 365 citations

  • Physics
  • Nuclear physics
  • Particle physics

  We present a new measurement of the positive muon magnetic anomaly, a_{μ}≡(g_{μ}-2)/2, from the Fermilab Muon g-2 Experiment using data collected in 2019 and 2020. We have analyzed more than 4 times the number of positrons from muon decay than in our previous result from 2018 data. The systematic error is reduced by more than a factor of 2 due to better running conditions, a more stable beam, and improved knowledge of the magnetic field weighted by the muon distribution, ω[over ˜]_{p}^{'}, and of the anomalous precession frequency corrected for beam dynamics effects, ω_{a}. From the ratio ω_{a}/ω[over ˜]_{p}^{'}, together with precisely determined external parameters, we determine a_{μ}=116 592 057(25)×10^{-11} (0.21 ppm). Combining this result with our previous result from the 2018 data, we obtain a_{μ}(FNAL)=116 592 055(24)×10^{-11} (0.20 ppm). The new experimental world average is a_{μ}(exp)=116 592 059(22)×10^{-11} (0.19 ppm), which represents a factor of 2 improvement in precision.

  PublisherOA PDFDOI

• Workshop on a future muon program at FNAL

  arXiv (Cornell University) · 2023-09-12 · 1 citations

  preprintOpen access

  The Snowmass report on rare processes and precision measurements recommended Mu2e-II and a next generation muon facility at Fermilab (Advanced Muon Facility) as priorities for the frontier. The Workshop on a future muon program at FNAL was held in March 2023 to discuss design studies for Mu2e-II, organizing efforts for the next generation muon facility, and identify synergies with other efforts (e.g., muon collider). Topics included high-power targetry, status of R&amp;D for Mu2e-II, development of compressor rings, FFA and concepts for muon experiments (conversion, decays, muonium and other opportunities) at AMF. This document summarizes the workshop discussions with a focus on future R&amp;D tasks needed to realize these concepts.

  PublisherOA PDFDOI

• Electric dipole moments and the search for new physics

  Data Archiving and Networked Services (DANS) · 2022-03-15

  otherOpen access

  Static electric dipole moments of nondegenerate systems probe mass scales for physics beyond the Standard Model well beyond those reached directly at high energy colliders. Discrimination between different physics models, however, requires complementary searches in atomic-molecular-and-optical, nuclear and particle physics. In this report, we discuss the current status and prospects in the near future for a compelling suite of such experiments, along with developments needed in the encompassing theoretical framework.

  Publisher

• Field Studies with Faraday Magnetometers for Muon g-2 [Poster]

  2022-06-13

  articleOpen access

  An additional 378 NMR probes, placed at fixed locations outside the vacuum chamber, monitor the field drift in between field scans. A high-accuracy probe was designed for calibrating the probes in the scanner. In this presentation, the magnetic field measurement hardware system and analysis methods will be described in detail. The progress of the Run-1 data analysis and improvements in Run-2 will be presented as well.

  PublisherOA PDFDOI

• Progress on the CeNTREX TlF Schiff moment search

  2022-06-15

  preprint
  PublisherDOI

Frequent coauthors

• K. Tanida

  620 shared

• Y. Akiba

  469 shared

• Y. Goto

  Augustana University

  464 shared

• N. Saito

  The University of Tokyo

  455 shared

• T. Csörgő

  Institute for Particle and Nuclear Physics

  419 shared

• A. Deshpande

  411 shared

• H. Enʼyo

  403 shared

• M. Große Perdekamp

  400 shared

Labs

• David Kawall's LabPI

  Not provided