Brookhaven Bits & Bytes » Chelsea Whyte Thu, 01 Aug 2013 14:43:34 +0000 en-US hourly 1 Using Extragalactic Particles To Calibrate An Atom Smasher Thu, 01 Aug 2013 14:43:34 +0000 By Angela Leroux-Lindsey





RHIC physicists use tracks of cosmic rays traversing the PHENIX detector to calibrate and align its components to ensure the accuracy of experimental data taken during particle collisions.

“Before the first ion beam is accelerated, we take data with the cosmic rays to study internal detector behavior, and to keep data acquisition buzzing,” said Hubert van Hecke, a physicist at RHIC’s PHENIX detector.

Because cosmic rays are readily available, easy to identify, abundant, and free, they’re the perfect micro-tools for calibrating and aligning RHIC’s cutting-edge detection instruments. The collider isn’t active all year round, and often a period of dormancy leaves these sensitive detecting tools out of sync—like the keys of a piano left unplayed for several months. A piano tuner uses an external source that provides a note in perfect pitch to calibrate the keys. The detectors at RHIC require a similar alignment process when they’re first turned on. The physicists use the predictable, consistent radiation patterns of cosmic rays coming in from space as the “perfect pitch” for “tuning” the detectors.


“We have a lot of components and systems that constantly ‘talk’ to each other, and they need to be in alignment,” said van Hecke. “For example, we have a detector on the north wall that is far away from the detector on the south wall. Cosmic rays are the only particles that traverse both detectors simultaneously, allowing us to align the experiment and determine the accuracy of the detector.”

This simultaneity lets researchers exploit the consistency of the cosmic rays’ momentum and velocity: When the system components are functioning perfectly, each should record identical measurements for any cosmic ray passing through and recognized by the activated trigger. If these measurements are off, the data the detector collects could be compromised. So researchers tweak the instruments until their readings match.





]]> 0
The Nanostructure of Noms: Why Edible Fats Are So Tasty Fri, 08 Feb 2013 17:17:41 +0000 X-ray diffraction patterns reveal the orientation of fat crystals. The distribution and directionality of these crystal nanostructures (parallel to the shear field in C, randomly arranged in D) affects the flavor and texture of foods.


From butter in croissants to cocoa solids in chocolate, edible fats pack a flavor punch that delights like no other macronutrient we consume. Fats are the most energy dense macronutrients, providing more than twice as many kilocalories per gram as proteins or carbohydrates, which may be the reason we’ve developed a taste for them. Fats are an efficient method of fueling a surviving species, but what gives them their oh-so-delicious disposition?

The sensory characteristics of fatty foods come largely from the physical makeup of crystals that form within the nanoscale structure of fat molecules. As explained in a review paper by Alejandro Marangoni published in Soft Matter, fats are made up of fractal-like crystalline structures, which give rise to properties such as flavor, texture, meltability, and mouthfeel.

Fats are composites called triglycerides or triacylglycerides (TAGs) made up of one glycerol molecule and three fatty acid chains. The physical properties of these fatty acids and the positions they take on the glycerol molecule give rise to changes in the foods that contain them. For example, the length of fatty acid chains affects a fat’s melting point. Saturated or longer chain fatty acids, like those in milk fat or cocoa butter, will have higher melting points than triglycerides with mostly shorter or unsaturated fatty acid chains, such as olive oil. That’s why at your dinner table, the salad dressing is liquid, but the butter dish holds a solid stick.

Changes in flavor and texture of fats can also come down to which fatty acids sit where on the glycerol molecule. Milk fat contains short-chained butyric acid, which sits in the 3rd position, while cocoa butter’s 2nd position is populated almost exclusively by oleic acid.

Depending on how they are heated and cooled, triglycerides can crystallize into several forms. The resulting fractal-like crystalline structures give rise to flavor, texture, and meltability in foods like chocolate bars. Six different forms of crystal structure have been identified for cocoa butter. But only one form will turn out chocolate that tastes and feels good to eat.

The so-called Form V has a tuning fork structure to its crystals, which produces a melting range close to the temperature of the mouth. Chocolate manufacturers devote much effort to producing bars with this specific form of crystallization through the use of tempering, a process which heats and cools the chocolate to get a desired consistency.

If Form V crystals transform to Form VI, the chocolate will have a higher melting point and the cocoa butter will coat the inside of the mouth, leaving a waxy sensation. Form VI crystals can also bloom into  large, visible crystals, transforming a chocolate bar from a silky melt-in-your-mouth treat into a rough, white, waxy snack.

Marangoni and his collaborators have used x-ray diffraction at the National Synchrotron Light Source to categorize the many facets of fat crystals:

“At the mesoscale level (length scales within the micrometer range), we can witness a very diverse assortment of crystal habits – spherulites, needle-like crystals, microplatelets, disordered crystal aggregates, spherical crystal aggregates, fractal-like aggregates, and even some morphologies that defy proper description.

Despite the wide variety of crystal morphologies, they all share some common attributes: (1) the structures are awe-inspiringly beautiful when viewed under a polarized light microscope and (2) the crystalline mass in a network of these crystals is distributed in a fractal fashion.”

The discovery and characterization of these nanoplatelets adds to the knowledge upon which the food industry bases its design and engineering of food materials. Understanding how the physical chemistry of fats affects the way foods taste and feel could also potentially be useful when trying to curb the excessive consumption of fat-rich foods, writes Marangoni.

With close to 35% of the U.S. adult population and 20% of U.S. children identified as clinically obese, and the incidences of Type II diabetes and cardiovascular disease on the rise, the challenge for food engineers is to produce low-calorie foods containing fewer ‘bad fats’ while retaining many of the quality characteristics historically associated with a particular food.

]]> 1
Smashing Atoms with Common Words Thu, 07 Feb 2013 15:09:59 +0000 Particle collisions aren’t the easiest thing in the world to explain, but one of our physicists took this challenge to the extreme. In another Ten Hundred Words of Science submission, Brookhaven Lab physicist Paul Sorenson explains his work studying quark-gluon plasma with the Relativistic Heavy Ion Collider.

Where I work, we slam together small things to break them into even smaller things until we have the smallest things possible. This is how we know what matter is made of. We gave names to the smallest things in matter like “up”, “down”, “strange”, “top”, and “bottom”. Each of those things can be either matter or not-matter and can have three types. We use the name of a different color, either red, green, or blue for each type. So we can make a red-up small thing and that red-up-thing can come together with a green-up-thing and a blue-down-thing. But those small things can never be alone. They can’t escape their groups. They are held together by a strong force.

The small things come in groups of two or of three. The groups of three have to have all three colors, like a red-up with a blue-up, and a green-down. The groups of two have to be matter with not-matter like a red-up and a not-red not-up. Sometimes the small things can change groups and new ones can come and go in pairs: a small matter thing and its small not-matter friend thing can pop out of space.

We are made of lots of groups of either up-things, up-things and down-things, or up-things, down-things, and down-things. That’s up, up, and down grouped together, or up, down, and down grouped together. These two little groups are at the heart of almost all the matter we see.



We found that the thick hot stuff is so thick it makes all the little things move together, dragging on the faster ones, and pulling on the slower ones. It’s a lot like water but not like air. The thick hot stuff we make where I work is the same as what was in all of space one hundred, hundred, hundred, hundred, hundred years ago when time had just begun.

I think I have a cool job! Please tell the people with money to keep letting me do it and I’ll keep telling you about it and using what I know to help everyone as much as I can.

You can also check out Paul talking about his research at RHIC in this video, where he isn’t limited to just those thousand most common words.

]]> 0
Ten Hundred Words of Climate Science Fri, 01 Feb 2013 13:47:09 +0000 Inspired by the internet comic “The Up-Goer Five”, which used only the 1,000 most commonly used words to describe the Saturn V Rocket, scientists across the internet are attempting to describe their work using the just this small set of words. And it’s tough! But one of Brookhaven’s atmospheric scientists was up to the challenge. Alistair Rogers, who works in our Environmental Sciences Department, gives it a go:

Understanding change at the top of the world so we’ll know what is going to happen later

When we drive cars and warm our homes we give out bad stuff that ends up in the air. The bad stuff in the air makes our world warmer, which is not good. Every year there is more bad stuff in the air, and our world gets a little bit warmer. Some people pretend this is not happening, they are wrong.

The green things that live outside suck up the bad stuff in the air that we give out when we drive our cars and use it to grow bigger.  This is good because the green things are slowing down the warming of our world. When the green things die, tiny life forms in the ground eat them and return the bad stuff back to the air, this is normal.


To help work out what might happen at the top of the world years from now we are trying to understand as much as we can about the way the ice goes away, the green things that grow outside and the tiny life forms that eat them.  When we know some more about this stuff we can put what we have learnt in a big thinking box (a bit like the one you are using to read this) and use it to tell us what will happen years from now.

]]> 2
How Do Floating Water Bridges Defy Gravity? Wed, 17 Oct 2012 20:19:05 +0000 The term “floating water bridge” may sound nonsensical, but it’s the most logical name for a phenomenon that occurs when two beakers of water set slightly apart are zapped with high-voltage electricity and the water molecules jump across the gap to connect and form a thin thread of water. The molecular structure that suspends this liquid bridge has stumped scientists for over a century.


Floating water bridges





Q: What were you expecting to find?




Q: So, what did you find?




Q: Did you think your findings were wrong?










]]> 3