Fermi National Laboratory

Volume 25  |  Friday, August 30, 2002  |  Number 14
In This Issue  |  FermiNews Main Page

Flying Without a Net
In which a public affairs intern emabarks upon a personal neutrino adventure, confronting some of HEP's weightiest questions

by Pamela Zerbinos

On May 3 of this year, Ingrid Lucia and the Flying Neutrinos took the stage at the New Orleans Jazz & Heritage Festival, an annual two-week long party that draws more than half a million people. The Neutrinos, a quirky six-person band out of New York that mixes jazz, swing, blues and soul, were making their second appearance.

Two of the band’s members have been Neutrinos most of their lives. The lead vocalist and her brother, a tap-dancing trombone player, are the oldest children of a musical pair of socially conscious adventurers whose family band was called the Flying Neutrinos. When the oldest children split in the mid-90s, they took the name with them, and the remaining family members became the Floating Neutrinos.

“Neutrinos,” say the Neutrinos, “are subatomic particles that exist throughout the universe, invisible but ever-present, and act as a sort of balancing factor to all visible matter. The neutrino is a symbol of all the unseen but nevertheless real parts of ourselves and the universe, which must be taken into account if we are to become whole and fully manifested.”

Pamela Zerbinos finds that neutrinos are everywhere, but they’re very tricky to grasp. And that’s what I knew about neutrinos the day I reported for work at Fermilab. Clearly, there was work to be done.

My background doesn’t offer much of a starting point. I arrived at Northwestern University with thoughts of double-majoring in journalism and mathematics. I thought science coverage—especially “hard” science coverage—was abysmal, I was madly in love with calculus, and combining the two sounded like a great idea.

Predictably, I veered off-course. Although I stuck to journalism, my second major switched four times before settling on European history. My specialty, if you can call it that, was the papacy. I know a lot about popes and politics (and even papal politics), but not very much about particles or physics or particle physics.

I went on to get my Master’s degree in journalism from Northwestern, where I took a science writing class, which came on a field trip to Fermilab, which was arranged by the Public Affairs Office, which was looking for a summer intern. So, after a winding but eventually circular path, I find myself back to writing about science. My first task: figure out this neutrino thing.

The first stop on My Personal Neutrino Adventure, as I begin to think of it, is Fermilab’s website. From this, I learn that neutrinos are incredibly elusive, “ghostly particles” that travel throughout the universe “without leaving a trace.” Throughout the 70-year history of the neutrino, it has been at the center of a host of mysteries, some of which remain unsolved. Most neutrino literature has names like, “The Case of the Missing Neutrinos” and “A Subatomic Detective Story.” I start having black-and-white visions of Humphrey Bogart, chomping a cigar, interrogating physicists about the missing particles, the keys to larger mysteries and higher understanding.

I need to know more. I don’t understand how to count particles that leave no trace. I don’t understand where you get them or how you make them. (Is there some kind of neutrino factory? When I find out exactly such a thing may be in the works, I am giddy. I have visions of Willie Wonka’s Chocolate Factory, with Oompa-Loompas carrying around baskets of brightly colored neutrinos, all carefully labeled “electron,” “muon” and “tau.”) In the case of a long-baseline neutrino experiment like MINOS, how do you know the neutrinos arriving in Minnesota are the same ones that left Fermilab? I am particularly baffled by this phrase, which pops up again and again: “new physics beyond the Standard Model.” What is “new physics”? Is it like “new math”? I always thought that was a joke my parents used to get out of helping me with my algebra homework.

I set off on My Neutrino Adventure, intent on finding some answers. Help arrives quickly, although from an unexpected quarter: my mother. During our weekly phone call, I happen to mention something about neutrinos. Excitedly, she says, “I know what neutrinos are!” I can practically see her bouncing up and down. I swallow my surprise, and wait for her to continue.

“They’re energy sources from the sun,” my mother explains. “By measuring the different kinds of neutrinos and how many there are, they can tell how hot the sun is.” She pauses. “Or...something like that.”

She points me in the direction of a poorly executed story by her local NPR affiliate about the Sudbury Neutrino Observatory and its latest results. I head to SNO’s site, and then make a quick list of the neutrino facts I have gathered on my adventure: Neutrinos are elementary particles with no charge. There are three types of neutrinos—electron, muon and tau. Most were produced in the Big Bang, but some show up in cosmic-ray showers, some are produced in the sun’s core during fusion reactions and still others are given off during radioactive beta decay. For a long time, they were thought to be without mass, and the Standard Model does not account for a massive neutrino. Nor does the Big-Bang theory, or the theory about universal expansion. But recent experiments have found hints that neutrinos can oscillate—change from one type to another—and SNO seems sure that it’s got definitive proof. And if neutrinos oscillate, they have mass.

I panic, and here’s why. I’m one of those people who suffers from an overactive imagination, and in my head, it works like this: Someone discovers that a fundamental idea of physics—say, gravity— doesn’t work the way we thought it did. Furthermore, we have no idea how it works, and this changes everything. None of our math works now. Suddenly, by merely uttering that statement, reality reflects the new uncertainty. Not only does none of our math work, but gravity itself no longer works. Books fly off the shelves. People float around, bumping their heads on ceilings, which are themselves coming apart. There is a run on jet packs.

True, a massive, oscillating neutrino will solve a lot of mysteries. Neutrino mass may account for some of the mysterious dark matter in the universe. Neutrino oscillations explain “the missing solar neutrinos”—the mystery of why, when counting neutrinos from the sun, only about one-third as many show up as the theories predict.

But the cosmologists’ equations for the first few minutes of the universe use a massless neutrino. As do the astrophysicists’ equations showing the universe will expand indefinitely. And so, if neutrinos have mass (which they do), and that mass is found to be sufficient for the universe to eventually collapse back in on itself (which it probably is), then clearly that collapse is going to happen soon. Like next Tuesday. Hence my panic.

I head to the cafeteria, intent on grabbing a physicist—any physicist—and accosting him with questions like, “What are we going to do about this?!” Suddenly, I am stopped in my tracks by a comforting thought: the Plum-Pudding Model.

At New Muon Lab, Pam gets a sense of scale from a component of the near detector for the MINOS neutrino experiment.

To my knowledge, the world did not spin out of control, or explode, or cease to exist, when J.J. Thomson’s old model about atom composition was disproved. Granted, that’s comparing apples and oranges, but I try not to think about that. I go back to my desk, deciding, for the sake of my mental health, to finish my neutrino reading.

The Public Affairs library, conveniently located about four feet from my desk, is home to several helpful volumes. I grab “The Elusive Neutrino” by Nickolas Solomey, “Spaceship Neutrino” by Christine Sutton and “The Case of the Missing Neutrinos” by John Gribbin. I talk to neutrino physicists. I go to a lecture called “Neutrino Physics at Fermilab,” for which I am overdressed, and after which I call the lecturer (a very helpful Peter Shanahan) for more details. I ask him intelligent questions like, “What’s with that?” He indulges me for quite some time, and then says, “Maybe you should talk to a theorist.”

I do, and eventually, a picture starts to emerge. But just as I start to wrap my mind around it, it shatters into a million different pieces, a million new questions, each more complicated, perplexing— and philosophical—than the last.

The latest batch: Can neutrinos spin in either direction? (The short answer—yes—confuses me even more than parity violation, because, despite the valiant efforts of the theorist Boris Kayser, I don’t see why the angle from which you’re viewing the neutrino should change the direction in which it’s spinning. I just don’t.) How can a particle be its own antiparticle? Are there really just three types of neutrinos? In what ways do they mix? Why are they so light? How long do they live? What’s a spinor? (I picture a spiky armadillo, but apparently it’s some kind of mathematical construct.)

My confusion and I are in good company.

"It's like wallowing in an intellectual mud bath," says Boris, after very generously attempting to explain to me for nearly two hours just how a particle can be an antiparticle of itself. After our talk, I spend 45 minutes staring at a wall, trying to decide if I understand or need to go back.

That answer is one that comes quickly. Of course I’ll need to go back. I will always need to go back. Even the physicists need to go back, which is precisely what makes neutrinos so fascinating. Neutrinos are both telescope and microscope, able to take us out to the farthest reaches of the universe and into the very heart of matter. They can shed light on how particles acquire mass, what the universe is made of, and why there is more matter than antimatter (which is too bad—I must admit to liking the idea of an anti-Pam, except for the annihilation part). Neutrinos can be a wonderful probe into the weak force, into flavor, into the structure of the nucleon. There are countless neutrino adventures to be had, countless physics adventures to be had, and I hope to leave Fermilab better able to communicate the excitement of those adventures to the outside world. I’ll just need a few more weeks to work on this neutrino thing.

—Pamela Zerbinos is an intern in Fermilab’s Office of Public Affairs.


On the Web:
Neutrinos at Fermilab
www-numi.fnal.gov
www-boone.fnal.gov


last modified 8/30/2002   email Fermilab