Ann Heinson's Home Page

Research Physicist
Experimental High Energy Physics

Retired from physics with transverse myelitis
September 2012

American Physical Society's Woman Physicist of the Month
July 2012

Fellow of the American Association for the Advancement of Science
December 2010

Fellow of the American Physical Society
November 2008

UC Riverside Distinguished Researcher Award
for Non-Senate Faculty, September 2002

            Department of Physics
            and Astronomy
            University of California
            Riverside, CA 92521-0413

            Phone:  (951) 827-5712
            Fax:      (951) 827-3345

The DØ Research Group at UC Riverside

Ann Heinson

DØ Collaboration Banner
("The Map")
Pictures of DØ Feynman Diagrams
DØ Map for Run II
DØ Map for Run II
Click on the image
for png and eps files
of the maps, and for
flag strips for talks

2d view of DØ
2d view of DØ's tracking system
Click on the images
for gif and eps files
of these figures and
other detector images

ttbar feynman diagram
s-channel single top diagram
t-channel single top diagram
Click on the images
for png and eps files
of these and many
more Feynman diagrams

Research Interests

For the past eighteen years, I have been studying the top quark, which the collaboration  co-discovered in 1995. I am particular interested in the production of single top quarks via the weak interaction. On the practical side, I have specialized in the design and use of tracking detectors, from wire chambers to silicon microstrip devices. I co-led the single top working group at DØ from 1995 to 2009, and the Monte Carlo Generators group from 2007 to 2009, and am now the Tevatron Electroweak Working Group's top physics representative from DØ. I am responsible for DØ's Top Physics Group's web pages and the collaboration publication lists organized thus: DØ's publications by year, DØ's publications by topic, and DØ's publications by topic and year.

In May 2005, we submitted the results of the single top quark search for publication in Physics Letters B, and it was published in July: preprint, journal paper, technical summary, plain-english summary, news article, and pictures of the authors. In April 2006, we submitted a more detailed write-up of these results for publication in Physical Review D: here are the preprint and journal paper. My graduate student, Philip Perea, completed his Ph.D. dissertation, "Search for t-Channel Single Top Quark Production in ppbar Collisions at 1.96 TeV," in June 2006. In July 2006, we submitted a paper to Physics Letters B that sets limits on production of single top quarks from the decay of a heavy W-prime boson: here are the preprint and journal paper (published September 2006). In January 2007, we submitted a paper for publication on another new analysis that sets limits on the production of single top quarks from flavor-changing neutral currents, that is from a gluon-charm-top or gluon-up-top coupling: here are the preprint and journal paper (published November 2007).

This series of searches culminated in December 2006, when the DØ collaboration announced first evidence for single top quark production at the Tevatron, a most exciting event. We ruled out the hypothesis that the data does not contain single top quark events at the 99.965% level, and measured the rate that single top quarks are produced. We submitted a paper to Physical Review Letters (preprint, and journal paper, published May 2007), which is described in a technical summary and a plain-english summary. There were articles about this result in Fermilab Today, CERN Courier, Nature Physics, Physics Today, and Scientific American, where I am quoted. I gave a particle physics seminar at CERN on the result in January 2007. I was also interviewed for a news item on a local cable channel, Inland Valley News (the interview is the second item in the program), and have recorded an interview (part 1 and part 2) for the radio program Science Today. Here are the Fermilab press release and UC Riverside press release about the result. In June 2007, we updated two of the three analyses and combined the results to get a more precise result that rules out the background-only hypothesis at slightly high significance (3.6 standard deviations). This conference note describes the combination of the analyses. We submitted this result for publication in March 2008, in a long paper containing all the analysis details (preprint). This detailed paper was published in July 2008 (journal paper). A article about the paper was published in August 2008.

The single top group followed up this analysis with three studies looking for physics beyond the standard model in single top quark events. The first search was for heavy W-prime boson resonances with decay to a top quark and a bottom antiquark, published in May 2008 (preprint, journal paper). The second search was for a charged Higgs boson also decaying to a top quark and bottom antiquark. This is much harder to search for as the Higgs mass is lower, so any resonance is more background-like. We submitted this result for publication in July 2008, and it was published in May 2009 (preprint, journal paper). Both analyses set lower limits on the cross sections and masses of the predicted new particles. The third analysis studied the Wtb couplings in single top production to see if they are as predicted by the standard model, that is, only vector and left-handed in nature. We set limits on vector right-handed and tensor left- and right-handed components, and submitted a paper for publication in July 2008 that was published in November 2008 (preprint, journal paper). A follow-up paper combined this result with DØ's measurements of the W boson's helicity in ttbar decays to get improved limits (preprint, journal paper).

By March 2009, we had analyzed a dataset over twice as large as used in the previous measurements and announced first observation of single top quark production with 5.0 standard deviation significance (i.e., only a 1 in 4,000,000 chance that the background fluctuated up to fake the signal). We submitted a paper to Physical Review Letters, which was published in August 2009 (preprint, journal paper). The paper is an "Editors' Suggestion" and has an accompanying Physics Synopsis article. Everything is described on the observation results web page with lots of plots and discussion, and photos of the analysts. There were many press articles, including a discussion on National Public Radio's Science Friday program. I have written a 30 page review article on this result, and on the simultaneous one from the CDF collaboration, which has been published in Modern Physics Letters A. I have also recently co-written a 26 page review paper on the two results with Tom Junk from CDF and Fermilab, which appeared in the Annual Review of Nuclear and Particle Science in October 2011.

In addition to continuing my single top quark physics research program, I am now also working on combinations of top quark physics measurements from the DØ and CDF collaborations at the Tevatron, with all uncertainties and their correlations taken carefully into account. These results will form part of the Tevatron Collider legacy of results in the research literature and textbooks for years to come. The paper I wrote on the combination of the top quark mass measurements was submitted to Physical Review D on July 4, 2012 (aka Higgs Discovery Day).


As a member of the DØ collaboration, I am a coauthor of 404 papers in several international journals. Of these, 21 are on top quark physics using DØ's first dataset (1992-1996), and 77 are on top quark physics using DØ's second dataset (2002-2011). There are 10 additional papers from previous collaborations and from individual work, and two review papers.
Of special interest are the following papers:

Conference Talks

High Energy Physics Seminars    (click to jump down the page for the list)

Conference Proceedings Papers    (click to jump down the page for the list)

Service for the DØ Experiment

Run I
Run II
Other Professional Service

The American Physical Society's Division of Particles and Fields Meeting was held at UC Riverside, August 2004, see
(images are of posters I prepared, click on them for larger versions)
DPF welcome reception DPF student reception DPF Quarknet mentors' meeting DPF public lecture DPF women's lunch DPF chamber concert DPF Young Particle Physicists' lunch DPF town meeting DPF conference banquet

A Bit of History
I grew up in Billericay, S.E. England, and went to university in London. I graduated from Imperial College in 1984 with a B.Sc. in Physics, and in 1988 I got a Ph.D. in High Energy Physics, also from Imperial College. I wrote the first British Large Electron-Positron Collider (LEP) Ph.D. dissertation, on the ALEPH experiment. I then worked for the BBC at their engineering research labs until emigrating to California in 1989. I was a postdoctoral researcher at UC Irvine for three years, working on a rare kaon decay experiment E791 at Brookhaven National Laboratory, NY, and then moved to UC Riverside where I have been working on the DØ Experiment at Fermi National Accelerator Laboratory since 1992.

Academic Ancestry
My Ph.D. advisor was Peter Dornan, at Imperial College, London. His advisor was Otto Frisch, at Cambridge University. Frisch worked on the Manhattan Project during World War II. His advisor was Stefan Meyer, at the University of Technology, Vienna, Austria. Meyer worked with Ludwig Boltzmann in Vienna in the 1890's.

Ann and John at the Huntington Library, San Marino, CA, Nov 1999

John and me at the Huntington
Library Botanical Gardens,
San Marino, CA, November 1999

Jeffrey and me, April 2002

Jeffrey and me
April 2002

Jeffrey and me, March 2004

Two physicists
March 2004

At the Tran Quoc Pagoda, Hanoi, August 2004

Tran Quoc Pagoda
Hanoi, Vietnam
August 2004

Top Quark Symposium, Michigan, April 2005

Top Quark Symposium
Ann Arbor, Michigan
April 2005

First day of kindergarten, September 2006

First day
of kindergarten
September 2006

Submitting the single top evidence paper to PRL, December 2006

Submitting the single top
evidence paper to PRL
December 2006

Making mince pies and pastries, December 2007

Getting ready
for the holidays
December 2007

Three Heinson siblings, July 2009

Heinson siblings
July 2009

Washington DC, February 2010

February 2010

Riding lesson, May 2011

Riding lesson
April 2011

UCR Botanical Gardens, May 2011

UCR Botanical Gardens
May 2011

In the photos are John Ellison and our son, Jeffrey

High Energy Physics Seminars

Conference Proceedings Papers

Last update: January 21, 2013
Ann Heinson