Don Lincoln

Don Lincoln is a Fermilab scientist.

As time passes, we remember the glory days of yesterday, like the time when we found the Higgs boson. Nowadays, some scientists take the existence of the Higgs boson as a given and have moved on, using it as a way to find something new. Readers of this column almost certainly remember the announcement of the discovery of the Higgs boson on July 4, 2012. It was a heady time, as it is rare that one confirms the final missing…

The purpose of particle physics is to better understand the rules that govern the universe. Long before the papers are written, accelerators and detectors must be designed, built and operated. It is technology that makes it all possible. Readers of Fermilab Today have read many articles on many experiments: CDF and DZero, LHC, the neutrino program, the muon program, astrophysics studies. These articles focus on the outcome of the measurements and what they tell us about the physical world. But…

How many forces?

Unlike in Star Wars, where there was but one force with a light and dark side, the number of fundamental forces is a much murkier question. If you’ve read many of my columns, you know quite a bit about the Standard Model. You know that there are quarks and leptons. You’ve heard about the gluon, the W and Z bosons, the photon and the graviton. And you know that this means that there are four fundamental forces: the strong and…

Crazy particles

Scientists in the CMS collaboration look for many different possible signatures that would reveal new physical phenomena. One interesting idea is massive and long-lived particles that stop inside the detector and then decay. “We are all agreed that your theory is crazy. The question that divides us is whether it is crazy enough to have a chance of being correct.” This quote is attributed to Niels Bohr speaking to Wolfgang Pauli when the latter was presenting a new theory in…

Electromagnets

Electromagnets are made by wrapping wire in a coil and attaching it to a battery. The same technology is used to make the magnets used in large particle accelerators. Magnets are something most of us are familiar with, but you may not know that magnets are an integral part of almost all modern particle accelerators. These magnets aren’t the same as the one that held your art to your parent’s refrigerator when you were a kid. Although they have a…

Stealth SUSY

Stealth SUSY is a theory of supersymmetry that doesn’t have the usual signatures expected in more common supersymmetric models. Collisions in which stealth SUSY appears look much like the ordinary collisions of the Standard Model. A recent analysis studied CMS data to see if any evidence of stealth SUSY could be found. With the impending resumption of operations of the LHC, scientists often discuss what they think will be the next big discovery. While it is hard to make predictions,…

Collisions like these indicate the existence of invisible particles. The blob of color in the upper left hand corner shows where particles were knocked out of the collision to deposit energy in the detector. The fact that we see no balancing energy in the lower right hand corner means that an invisible particle has escaped the detector. As the number of simultaneous collisions in the LHC increases, it will become increasingly difficult to study this kind of physics. The CMS…

Boosted W’s

In the green region, we show what a W boson looks like before it decays. Moving left to right, the boson is created with more and more momentum. In the yellow region, we repeat the exercise, this time looking at the same W boson after it decays into quarks, which have then turned into jets. Finally in the pink region, we look at a jet originating from a quark or gluon. This looks much like a high-momentum W boson decaying…

The same basic equations that govern the flow of water are important for describing the collisions of lead nuclei. In today’s article, we’ll get a glimpse of how this works. It’s hard for most people to imagine what it’s like at the heart of a particle collision. Two particles speed toward one another from opposite directions and their force fields intertwine, causing some of the particles’ constituents to be ejected. Or possibly the energy embodied in the interaction might be…

Epic facepalm

A recent statement by physicist Stephen Hawking has been misrepresented in the extreme. Let’s take a look at what he really meant. If you’re a science enthusiast, this week you have likely encountered outlandish headlines invoking Stephen Hawking, the Higgs boson and the end of the universe. I hope you had the presence of mind to react as the famous actor in the picture did. Let’s start with the answer first. The universe is safe and will be for a…