DAVID W. HERTZOG

Arthur B. McDonald Distinguished Professor of Physics

Director, Center for Experimental Nuclear Physics and Astrophysics

Department of Physics   University of Washington

Box 351560, Seattle WA 98195

(206) 543-0839
hertzog@uw.edu

Appointments:

College of William and Mary Ph.D., Physics1983
Carnegie-Mellon University  Research Associate1983-86
University of IllinoisAssistant Professor, Physics1986-92
University of IllinoisAssociate, Center for Advanced Study1990
University of IllinoisAssociate Professor, Physics1992-97
University of IllinoisProfessor, Physics1997-2010
University of WashingtonProfessor, Physics2010-
University of WashingtonDirector, CENPA2017-
University of WashingtonArthur B. McDonald Distinguished Professor of Physics2020-

Current Research: I lead a group that carries out high-precision experiments involving muons:

  • Muon g-2: Measurement of the muon anomaly to a precision of 0.140 ppb, which will be a sensitive test of the standard model. I was founding co-spokesperson and served through 2018.  I was Analysis Coordinator for the Run-1 results, published in 2021.
  • PIONEER:  I am co-leading a new collaboration with a program in rare pion decays that will test lepton flavor universality violation sensitively.  This experiment is approved for running at PSI.

Previous and completed muon experiments:

  • MuLan: a 1-ppm measurement of the muon lifetime, which determines the fundamental Fermi constant to sub-ppm precision. (Co-Spokesperson)
  • MuCap: a precision measurement of the rate of the semi-leptonic electroweak process μ + p –> n + νμ, which will determine the least-well-known of the charged weak form factors of the nucleon, the pseudoscalar gp, to 7%.

See our Group’s Research page here

Honors and awards:

  • Tom W. Bonner Prize in Nuclear Physics (2022)
  • University Faculty Lecture, University of Washington (2022)
  • John Simon Guggenheim Foundation Fellow (2004)
  • Fellow, American Physical Society (2000)
  • University Scholar (2000)
  • BP Amoco Award for Innovation in Undergraduate Instruction, 2003
  • Amoco Award for Innovation in Undergraduate Education, 1997
  • W. Keck Foundation Award for Engineering Teaching Excellence, 1994
  • Everitt Award for Teaching Excellence, 1994
  • List of Excellent Teachers (at Illinois) , 18 semesters

Innovations in teaching and training (@Illinois) Developed new Modern Experimental Physics Laboratory course featuring research-style data recording, analysis techniques, report writing, and oral presentations. Developed two-semester Introduction to Physics Research/Senior Thesis course sequence to prepare advanced undergraduates for physics careers. Served on the design  teams for new introductory physics courses, which incorporate active-learning pedagogy. Designed and implemented all new laboratories for two semesters of algebra-based introductory physics courses.  Wrote The Problem Solver for Physics 102 Discussion sections.  Developed Discovery Room for Practical Physics: How Things Work course.  Co-teacher for several years in the College of Engineering Teaching College, a mentoring program for new assistant professors. @Washington:  Major effort to use SmartPhysics in 121 and 122 with a fully integrated “flip the lecture” approach.  Many of my materials are being used by other faculty. 

Science literacy and public outreach:  Founded and ran for two years the Saturday Physics Honors Program aimed at high school students, but also attended by the general public.  Several invited talks to under-graduates and high-school physics teachers and public forums on muon g-2 experiments and more recently on The World’s Greatest Scientific Instruments. Presentation to Seattle Technology Alliance on muon g-2; Scientific American podcast and other outreach related to first g-2 results in 2021

Ph.D. Students Supervised:

Former students: R. Tayloe, S.A. Hughes, P.E. Reimer, J. Ritter, T. Jones, B. Bunker, F.E. Gray, C. Polly, D.B Chitwood, D. Webber, J. Crnkovic, B. Kiburg* , N. Froemming, M. Smith, A. Fienberg, J. Hempstead, H. Binney; Current students: J. Labounty, O. Beesley

*co-supervised with P. Kammel;

Postdoctoral Fellows Supervised:

Former: P.G. Harris, S.A. Sekykh, G. Onderwater, F. Mulhauser, C. Ozben, R. McNabb, P. Winter, S. Kizilgul, P. Alonzi, J. Kaspar, K. Khaw, Z. Hodge; Current: C. Claessens, P. Schwendimann, S. Braun

Some special papers of interest:

Selected papers, but see this link for current Inspire list

Publications related to the first results from our Fermilab Muon g-2 Experiment: (and some selected press)

  1. Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm; (Muon g-2 Collaboration) B. Abi et al. Phys.Rev.Lett. 126 (2021) 14, 141801.
  2. Magnetic Field Measurement and Analysis for the Muon g-2 Experiment at Fermilab; (Muon g-2 Collaboration) T. Albahri et al. Phys.Rev.A 103 (2021) 4, 042208
  3. Measurement of the anomalous precession frequency of the muon in the Fermilab Muon g-2 experiment; (Muon g-2 Collaboration) T. Albahri et al; Phys.Rev.D 103 (2021) 7, 072002.
  4. Beam dynamics corrections to the Run-1 measurement of the muon anomalous magnetic moment at Fermilab; (Muon g-2 Collaboration) T. Albahri et al; Phys.Rev.Accel.Beams 24, (2021) 044002.

Review papers

  1. Precision Muon Physics, T.P. Gorringe and D.W. Hertzog,  Prog. Part. Nucl. Phys. 84 (2015) 73-123.
  2. Low-energy precision test of the standard model:  a shapshot,  D.W. Hertzog, Annalen der Physik, (2015)
  3. The Brookhaven Muon Anomalous Magnetic Moment Experiment, David W. Hertzog and William M. Morse, Annu. Rev. Nucl. Part. Sci. 2004. 54:141-74.
  4. D. W. Hertzog. Muons: Particles of the moment. Physics World 17 N3, 29-34 (2004)



Some Technical Papers on Calorimetry

  1. Studies of an array of PbF2 Cherenkov crystals with large-area SiPM readout, A.T. Fienberg et al., Nucl. Instrum. Meth. A783 (2015) 12-21.Some Technical Papers on Calorimetry
  2. Design and performance of SiPM-based readout of PbF2 crystals for high-rate, precision timing applications, J. Kaspar et al., JINST 12 (2017) no.01, P01009.
  3. Performance of the Muon g-2g−2 calorimeter and readout systems measured with test beam data; K.S. Khaw et al.; Nucl.Instrum.Meth.A 945 (2019) 162558.
  4. S. A. Sedykh, et al. Electromagnetic calorimeters for the BNL muon (g-2) experiment. Nucl. Instrum. & Meth. A 455, 346-360 (2000).
  5. D. W. Hertzog, P. T. Debevec, R. A. Eisenstein, M. A. Graham, S. A. Hughes, P. E. Reimer, and R. L. Tayloe. A high-resolution lead/scintillating fiber electromagnetic calorimeter. Nucl. Instrum. & Meth. A 294, 446-458 (1990)

Description of Current Research

Most of our group at the Elba, 2019 Muon g-2 Collaboration Meeting


Muon g-2: Our group is engaged in a sub-ppm measurement of the muon’s anomalous magnetic moment (g-2). The results of this experiment, when compared with precise theoretical calculations, are capable of revealing physics beyond the Standard Model attributed to SUSY particles of high mass, to structured intermediate vector bosons, or to substructure of the muon itself.  Our final measurement, from the Brookhaven E821 Experiment, was more than 3 standard deviations from the current (2022) Standard Model expectation and the result has caused a significant buzz in the theoretical community. Our new experiment at Fermilab has been taking data through 6 years, acquiring more than 20 times the data obtained at BNL. Our first results — based on about 6% of the expected total — confirmed the BNL value and, when averaged together, increased the tension with the SM to more than 4 standard deviations. Stay tuned. We are continuing to publish and theory is continuing to update their expected SM value.  Our group has had many roles from instrumentation (calorimeters, electronics, fiber-harp entrance and in-ring detectors, pulsed NMR probes and electronics) to software (Nearline, Data Quality Monitoring, offline), and analysis (coordination, beam dynamics, omega-a, weighted magnetic field).  

PIONEER  is a next-generation, rare-pion decay experiment that will take place at the Paul Scherrer Institute (PSI) in Switzerland.  There are three main physics thrusts. The first priority will be the world’s most sensitivity test of lepton flavor universality (LFU). It is strongly motivated by several inconsistencies between Standard Model (SM) predictions and data pointing towards the potential violation of LFU. The program will probe non-SM explanations of these anomalies through sensitivity to quantum effects of new particles, even if their masses are at very high scales. Measurement of the charged-pion branching ratio of electrons vs. muons is extremely sensitive to a wide variety of new physics effects. At present, the SM prediction is known to 1 part in 104, which is 15 times more precise than the current experimental result. An experiment reaching the theoretical accuracy will probe mass scales up to the PeV range.   A later stage of PIONEER will measure the ultra-rare pion beta branch, which is the cleanest way to obtain Vud and thus test CKM unitarity.  Throughout PIONEER data taking, we will also improve the experimental limits by an order of magnitude or more on a host of exotic decays probing for effects of heavy neutrinos and dark sector physics.  Pioneer is approved at PSI and we have been engaging in beam tests, in local development of LYSO calorimetry, and in developing  the overall simulation framework.


Recently completed:

MuLan: The Muon Lifetime Analysis (MuLan) experiment measures the positive muon lifetime, which provides the most precise determination of the Fermi coupling constant, one of the fundamental inputs to the standard model.  Recent advances in theory have reduced the theoretical uncertainty on the Fermi coupling constant as calculated from the muon lifetime to a few tenths of a ppm. The remaining uncertainty on the Fermi constant is entirely experimental and is dominated by the uncertainty on the muon lifetime. The MuLan experiment employs an innovative pulsed beam, a symmetric detector, and modern data-taking methods to reduce the uncertainty on the muon lifetime to 1 ppm.  This experiment took place at the Paul Scherrer Institute, Switzerland.   We completed data taking, analysis, and several well-deserved Ph.D. theses.  We proudly achieved our exact proposal goal of 1.0 ppm final precision, measured twice in blind experiments.  The Fermi constant, so obtained, has a precision of 0.5 ppm.  Our final paper is here.  The photo at the right shows some of us having prepared the soccer-ball-shaped detector for shipping to PSI.

MuCap: The goal of the MuCap experiment is a 1% precision measurement of the muon capture rate on the proton. From the capture rate, the pseudoscalar form factor, gP, of the nucleon will be extracted with 7% precision. This basic quantity is predicted theoretically with high precision, but the experimental situation was quite controversial. The first round of our experiment led an unambiguous value for gP and a strong confirmation of the chiral symmetry of QCD at low energies.  The success was based on the novel idea of capturing negative muons in ultra-pure hydrogen gas (not liquid) and, equally importantly, instrumenting the stopping volume in the manner of a time projection chamber (TPC).  My colleague Peter Kammel  invented the idea and led the effort from its inception.  Two MuCap Ph.D. students were the co-winners of the APS Nuclear Physics Dissertation prize for the earliest phase of the work, and two others have since graduated on refinements.  The final paper demonstrated that the theory is right, a very notable achievement. 

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