Married with Particles

Husband-and-wife physicists Tom Diehl and Brenna Flaugher lent a special touch to the Dec.12,2002 session of Virtual Ask-a-Scientist,an online chat session offering participants the opportunity to ask Fermilab scientists questions about high-energy physics.

People of all ages and all science backgrounds are invited to participate,and sessions are announced in the Newsbox of the Fermilab home page.To join a Virtual Ask-a-Scientist chatroom on the day of the session,click a link on the lab ’s home page and follow directions for logging-in and asking questions. Due to time constraints,some questions may not be answered during the on-line session,but full transcripts are available on-line about a week later. This is an edited version of the Dec.12 session.

Moderator:Welcome to Virtual Ask-a-Scientist!My name is Elizabeth Clements,of the Office of Public Affairs at Fermilab.Our guest scientists are Brenna Flaugher of the CDF experiment,and Tom Diehl of the DZero experiment.The big collider detectors,each host to more than six hundred scientists,are friendly rivals in Fermilab research.And talk about friendly rivals —Tom and Brenna are a married couple,making the situation even more interesting.And now,we ’re ready for your questions.

Michael:Hi,Tom and Brenna.Is it difficult to work as a physicist with your spouse?

Brenna Flaugher:Actually we work on different experiments.I think it would be hard to work together all day and then try to forget it at night.

Michael:Does it get competitive?

Brenna Flaugher:The experiments compete with each other,and during the search for the top quark there was lots of discussion about keeping secrets.Tom and I had a rule —we would not admit to knowing anything about the other experiment unless we heard it at the Fermilab lunch table,too.The Fermilab cafeteria is the best place to hear the latest rumors and secret information.

Kevin: Hi,Brenna.What ’s it like being a woman physicist?Isn ’t it a pretty “male-dominated ”world?

Brenna Flaugher:Yes,it is a male-dominated world,but I have gotten used to it.I am frequently the only woman in a meeting,but most times I don ’t notice.

Scott:You say on that on DZero,you ’re looking for new particles.Have you found any?I thought there were just the 6 quarks and 6 leptons.

Tom Diehl:New particles are created in almost every collision and collisions happen at a rate of a couple million per second.But most of those new particles are of kinds that we already know about.DZero actually discovered the 6th quark,along with our CDF colleagues,in 1994.At this time we are looking for a particle,the Higgs boson that may exist and may be responsible for mass.If the Higgs boson is not too heavy,we might be able to produce them with the Fermilab accelerator,the Tevatron.

Scott:I ’m reading “The God Particle ”[by Leon Lederman ].Has any progress been made since it was written (1991 I think)on finding the Higgs?

Tom Diehl:The probability for creating a Higgs particle in one of our collisions is very small. With about a million collisions per second,most of them producing common particles,we measure only about one or two top quarks per day.We think the Higgs is something like 50 times less common than that.

Brenna Flaugher:We have made progress on understanding how to look for it and we have more sensitive tests for finding it.But,what we need is lots of data —lots of proton-antiproton collisions and those are just starting to accumulate. We haven ’t found anything new …yet …. Wiley:What are the best things about being a physicist?

Brenna Flaugher:The thing I like about physics is it tries to understand and explain why things work the way they do.Learning physics means getting a better understand of lots of things. At Fermilab we look for the fundamental building blocks of matter,which seems pretty cool to me.

Michael:How are things working out with Run II?

Brenna Flaugher:The experiments are running pretty well and will be making presentations of new results at international conferences in the next few months.

Gluon:How is the luminosity doing?

Moderator:The luminosity keeps going up, up,up!

Sophie:Why do you make the particles go so fast around your accelerator?

Brenna Flaugher:We make them go so fast so that they have a lot of energy when they collide with the anti-protons.This way we have a chance of making new particles by converting the energy to mass (E=mc ² )

Scott:Does Fermilab study neutrinos?

Moderator:Fermilab has many different Neutrino experiments such as MiniBooNE,MINOS, NUMI. Neutrinos are a very hot topic!

Michael:I understand why CDF and DZero are located at Fermilab.But why are MiniBooNE and NuMI there,as opposed to someplace else?

Tom Diehl:The Fermilab complex has several accelerators that can be operated at the same time.While we are studying proton-antiproton collisions at DZero and CDF the beams are contained in the Tevatron accelerator.Meanwhile, the Main Injector is cracking protons into a target and producing antiprotons.Mini-Boone gets its proton beam from the booster.So all of these things can be done at the same time.

Sophie:What is the point?What are you going to DO with whatever you find out about the protons colliding with antiprotons?What can it solve?

Brenna Flaugher:By smashing the protons and antiprotons apart we learn about what holds them together.We are doing basic research.That means that it doesn ’t have a direct application right now.But we believe that it is important to learn more about our world (in this case the forces that hold the elementary particles together)and that 10 or 20 years from now it will become useful — but right now we don ’t now exactly how.One example is the web —it was started by particle physicists who wanted to communicate with each other even though they were in different countries.

Scott:Well,this Web applications developer would like to very much thank those physicists for giving me a job!

Wiley:How did physicists help develop the Web?

Moderator:Tim Berners-Lee,a scientist from CERN,invented the World Wide Web.

Tom Diehl:Physicists at CERN and around the world wanted a faster way to spread our ideas to each other.The web was developed so that we could do that.

Kevin:Have the particle physics discoveries of the past been useful?As citizens and taxpayers we all look for practical benefits —applications in our lives.

Brenna Flaugher:Practical benefits from basic research are hard to predict.Take the electron —who would have imagined all the uses of today,back when it was discovered?There are many spin-offs from particle physics —neutron therapy for treating cancer,for example.NMR magnets used for medical research were not the point of the particle physics experiments but have been adapted from the understanding we gained from the work.

Kevin:So my question,directly,is —why is particle physics worth our support? Tom Diehl:There are lots of reasons.One is practical applications.Those come about in two ways.The first:direct applications.The example we love to use is Thomson ’s discovery of the electron,our first particle.Right now,we are studying nature at a more fundamental level. When we come up with a direct practical application,if we do,it will have a profound effect.There are indirect applications —spinoffs. We have lots of them because what we do is difficult technologically.We need to invent stuff to do our work.

Bobby:If you weren ’t physicists,what would you be?

Tom Diehl:I am an “asking-questions ”type of person.I would be a scientist of some kind.Maybe instead of studying elementary particles I would be studying astronomy or astrophysics.

Brenna Flaugher:I think maybe an engineer. I have worked with many engineers while helping to build the CDF detector and I think that type of work is interesting.On the other hand,when I started college I wanted to be a vet and work with animals.If I hadn ’t switched to physics, I might be doing that.

Scott:Is working at Fermilab (and other top- notch facilities)like making the major leagues for an athlete (the best of the best)?

Tom Diehl:Fermilab is the highest energy accelerator in the world.But there are only 700 Major League baseball players (AL+NL) in the U.S.and a lot more particle physicists than that.I guess there are about 5,000 of us in the U.S.

symics:What types of jobs are available for particle physicists?

Brenna Flaugher:The types of jobs doing particle physics are professors at universities, or staff positions at national labs like Fermilab. Some people get their PhDs and then go off to other things —quite a few went to Wall Street and the stock market because writing computer programs that predict the market is somewhat like writing the programs we use in particle physics. Scott:Particle physics is one thing,but can you tell me how to set the clock on my VCR? Thanks for the chat,and good luck with those little particles.

Moderator:Thank you, everybody, for participating in this chat session!Good night!

ON THE WEB:
CDF homepage: www-cdf.fnal.gov

DZero homepage: www-do.fnal.gov