Supernova Explosion in M82: Exciting, but No Neutrinos

The M82 galaxy before (top) and after (bottom) its new supernova on Jan. 22 (Photo: UCL/University of London Observatory/Steve Fossey/Ben Cooke/Guy Pollack/Matthew Wilde/Thomas Wright)

The M82 galaxy before (top) and after (bottom) its new supernova on Jan. 22 (Photo: UCL/University of London Observatory/Steve Fossey/Ben Cooke/Guy Pollack/Matthew Wilde/Thomas Wright)

 

By Erin Weeks

In the early morning hours of January 22, the Earth turned spectator to a celestial event the likes of which hadn’t been seen in nearly three decades. The explosive death of a white dwarf star in Messier 82 (M82), a nearby galaxy, quickly ignited the astronomy world.

The supernova is exciting for a number of reasons that other outlets have well outlined — but unfortunately for Kate Scholberg, neutrinos are not one of them. Scholberg, a Duke University physics professor, studies the mysterious, nearly-massless particles at Super-K, a detector located deep in the mountains of Japan. Super-K was designed to spot neutrinos as they speed through Earth, revealing information about their sources, which can include the sun, cosmic rays, and supernovae.

“M82 is too far away for us to see any neutrinos from it,” Scholberg wrote in an email. “It’s about 11.4 million light years from us, meaning that the chance of seeing even a single neutrino from a core-collapse supernova in current detectors is probably a few percent or less (of course, we’ll look).”

Even if it were close enough, she said, this supernova doesn’t appear to be the type that generates a lot of neutrinos. White dwarves are common, dense stars whose supernovae are triggered when they consume new matter and experience runaway nuclear reactions. It takes a far more massive star to undergo core collapse, when a star’s unstable center caves in under the its own gravity.

“Core-collapse supernovae are the ones that spew neutrinos,” she wrote. ”So, not much hope we’ll see anything in neutrinos, alas.”

Scholberg coordinates SNEWS, the SuperNova Early Warning System, which will sound the alarm at the first sign of a neutrino-generating supernova. SNEWS and Scholberg will have to keep waiting for the next big blast, but the white dwarf supernova in M82 is still great news for physicists who study another hot topic — dark energy.

Astronomers spotted the supernova unusually early, meaning they’ll be able to collect a wealth of data before it hits peak brightness in a couple of weeks. It may be possible then to see the supernova with just a set of binoculars.

A six-photo composite of the starburst galaxy M82 (Photo: NASA, ESA, and The Hubble Heritage Team [STScI/AURA])

A six-photo composite of the starburst galaxy M82 (Photo: NASA, ESA, and The Hubble Heritage Team [STScI/AURA])

Detecting Dark Matter: the LUX experiment

Photomultipliers of the LUX detector

Photomultipliers of the LUX detector

By Olivia Zhu

How far would people go to detect something that, by definition, isn’t there?

Scientists from the Large Underground Xenon (LUX) experiment have built a facility a mile underneath the black hills of South Dakota in hopes of finding evidence of dark matter. Dark matter currently “does not exist” because it cannot be detected with light; however, it must be there, as it exerts a gravitational force on “normal” matter. Actually, it should have a rather large presence: the universe is made of 4.9% normal matter, 26.8% dark matter, and 68.3% dark energy.

On Jan. 16, Carmen Carmona-Benitez, a LUX representative from Case Western Reserve University in Cleveland, presented LUX’s latest findings to Duke’s Physics Department. The LUX experiment hopes to detect the presence of weakly interacting massive particles (WIMPs), a candidate component of dark matter. Carmona-Benitez described their detector, which has photomultipliers at either end; these photomultipliers will sense light emitted from electrons when WIMPs collide with their nuclei.

The LUX experiment, comprising 100 people, is a collaboration of 17 institutions in the United States and a few internationally. How could 100 extremely talented scientists work together without butting heads? Well, Carmona-Benitez stressed that many of the scientists design the machinery supporting the primary WIMP detector. For example, the team at University of California Santa Barbara built a filter system for the enormous tank of water that shields the detector from external gamma radiation. Another team contributed four thermosyphons used to cool the detector.

Thanks to these various efforts, LUX has achieved unprecedented sensitivity to WIMPs; however, no WIMP has been detected. This suggests that WIMPs, in fact, do not exist, and therefore do not comprise dark matter. The LUX team, though, refuses to give up and is creating a new and improved LZ experiment for WIMP detection.

The Triangle Universities Nuclear Laboratory (TUNL), based at Duke, is also trying to understand dark matter by studying neutrinos.

New Blogger: Olivia Zhu

196034_10150927127403780_429300165_n-2Hi!  My name is Olivia Zhu, and I am a sophomore biophysics major hailing from Pleasanton, California. I’m thrilled to start writing for the Duke Research Blog.

When I started my Duke career, I had absolutely no idea what research was. I had a vague conception of it as a drawn-out, painstaking process in which one traded in his life’s freedom for a micropipette. However, midway through my freshman year, a conversation with Professor Henry Greenside prompted me to reconsider. Professor Greenside inverted my perspective on research: he showed me that research did not revolve around tedious procedures, but rather around the pursuit of answers to fascinating questions. Since then, all sorts of research topics, particularly those with some aspect of physics, have captivated me. I found that research fulfills the idealistic conception I have always held of education: research represents the ultimate pursuit of pure knowledge, often without the pressures of immediate practical application.

Currently, I work in the Mooney Lab of neurobiology, which studies the learning processes in songbirds. Via surgical viral infection, I am examining the role that dopamine plays in this circuit.

In other matters, I enjoy forsaking my science-based identity by taking English, art, and history classes. I play soccer, run around campus, read classic novels, and discuss philosophy with friends. At Duke, I am a part of the Round Table and pWILD communities. Sometimes I miss hiking in California or exploring the islands in Beaufort, North Carolina, but I know there’s no place I’d rather be than here in Durham.

I’m looking forward to sharing my exploration of research at Duke!

Keely Glass, the Omni-Chemist

Guest post by Addie Jackson, North Carolina School of Science and Mathematics

Keely's picture from Linked-In

Keely’s picture from Linked-In

Ask Keely Glass how she would describe her research to a third grader, and she laughs while thinking of the best way to explain.

“So, say you’re sitting next to your friends. One has really black hair and one has red hair. They have different hair colors, because their hair colors come from the different pigments. Your friend with black hair has more eumelanin, while your friend with red hair has pheomelanin.”

A PhD candidate in the chemistry department at Duke, Glass currently does research on analytical methods to analyze these pigments in biological and historical samples. She’s also using those skills to provide direct chemical evidence for the presence and preservation of eumelanin in the fossil record.

Trust us, that's a fossil squid. (Courtesy of Willsquish on Wikimedia Commons.)

Trust us, that’s a fossil squid. (Courtesy of Willsquish on Wikimedia Commons.)

Glass elaborates by describing a common fascination with squids, also known as cephalopods, who release pure black eumelanin when faced with a predator. Two kinds of melanin are present in nature: eumelanin (brown to black in color) and pheomelanin (yellow to red). Through her work, she and her team have verified that eumelanin is preserved in the fossil record, and showed that it can be identified directly using its known chemical signature. They have also found that the eumelanin identified in the fossil record is not significantly different from the modern eumelanin, meaning it hasn’t evolved in the more than 160 million years since.

Another lab at Duke, run by Professor Warren S. Warren, uses a pump-probe microscopy system to characterize melanins to attempt to find statistically significant variations between melanomas (skin cancers) that do not develop metastases. The hope for this project is to improve diagnostic accuracy for these metastatic melanomas, through analyzing the melanin distribution in “old” archived (stored for >10 years) tissue samples. Glass says, “The paper I wrote with them essentially says if melanin resists degradation (stays intact and doesn’t alter) over more than 160 million years, it’s fairly clear that it will resist degradation in storage for 10 years. In other words, it’s pretty clear that these archived tissue samples are still viable for melanin analysis.”

Fourteen months in the life of one man's nodular melanoma. (Courtesy of 0x6adb015 via Wikimedia commons.)

Fourteen months in the life of one man’s nodular melanoma. (Courtesy of 0x6adb015 via Wikimedia Commons.)

Working with the Warren group, Glass also found that the pump-probe system was sensitive to the higher iron-concentration fossilized squid melanin as compared with modern cephalopod melanin. They were able to mirror the iron-independent signal by adding iron to modern cephalopod melanin. This proved to be interesting because metastatic melanomas have increased iron levels, which may or may not be responsible for signature variations.

The classical fields of chemistry (analytical, organic, physical, theoretical, inorganic, and biological) have become more integrated over time, making the labels themselves increasingly obsolete. To better label themselves, most chemists mix and match:  “I’ve called myself at various times a ‘Bioanalytical Chemist,’ ‘Biophysical Organic Chemist,’ ‘Analytical Biochemist,’ ‘Organic Geochemist’ etc. to emphasize that the systems I’ve worked on, the techniques I’ve used, and the skills I’ve obtained are diverse and dependent on the project I’m defining.”

Glass says, “When I think that the names have gone a little haywire, I jokingly call myself an omni-chemist. Like most chemists I work on diverse array of projects that require techniques and knowledge from many fields.”

Addie Jackson interviewed Keely Glass and wrote this post as part of a Science Communication seminar led by NCSSM Dean of Science Amy Sheck.

Chocolate’s crisp crack comes from chemistry

By Ashley Yeager

This is the final post in a four-part, monthly series that gives readers recipes to try in their kitchens and learn a little chemistry and physics along the way. Read the first post here and the second one here and the third one here.

chocolate-bunny

This bunny must have been made from quality chocolate. His ears are already gone. Credit: Waponi, Flickr.

When you snap off and savor the ears of a chocolate bunny this Sunday, say a quick thanks to science.

“The essence of science is to make good chocolate,” said Patrick Charbonneau, a professor of chemistry and physics at Duke.

He explained that cocoa butter, one of the main ingredients in chocolate, can harden into six different types of crystals. All six types are made of the same molecules. But, at the microscopic level, the types have distinct molecular arrangements, which lead to differences in the crystals that form.

“The problem with chocolate is that only two of these types have good texture when eaten,” Charbonneau told students in the Chemistry and Physics of Cooking.

He teaches the freshman seminar with chef Justine de Valicourt and chemistry graduate students Mary Jane Simpson and Keely Glass.

During class, students looked at and tasted chocolate containing only the good-tasting crystal types and some that also contained the less favorable ones. The first had that signature sheen and snap of quality chocolate and melted evenly when left on the tongue. The latter pieces were dull, melted with the slightest touch and left a sandy texture on the tongue.

The demonstration showed that the different types of chocolate crystals melt at different temperatures. By carefully controlling the chocolate as it cools, chocolate-makers can create mixtures of only the favorable crystal types.

The process, called tempering, takes chocolate through a series of heating and cooling steps. The initial cooling step forms many of the chocolate crystal types, including the dull, unfavorable ones. Warming the mixture a little — to about 31°C (87°F) — melts the unfavorable crystals but not the best-tasting ones.

As the mixture cools again, the remaining, favorable crystals “seed” the chocolate so that good-tasting crystals form preferentially throughout, ensuring good chocolate structure and taste.

Students got a chance to test the science in lab later that evening, and judging by the number of mouths (and faces) covered with chocolate, it’s safe to say the science was successful.

If you’re looking to try it out — or save a poor bunny’s ears — here’s the recipe.

Tempering chocolate:

Materials:
1 small, microwave safe bowl
1 big bowl
1 spatula
2 scraper spatulas
1 chocolate mold
parchment paper
cooking thermometer

Ingredients:
250 g Dark Chocolate or 250 g Milk Chocolate (about 1 1/3 cups)

Filling:
60g white chocolate (about 1/4 cup)
60g yogurt (a little less than 1/4 cup)

Instructions:

1. Place milk or dark chocolate in the small bowl.
2. Heat the bowl in 30-second intervals in a microwave (stirring after each) until the chocolate is melted. Note: The milk chocolate should take about 1.5 minutes and the dark chocolate about 2 minutes to melt.
3. Once heated, pour half the liquid chocolate onto a clean marble or stone counter. The chocolate puddle should be the size of a medium pancake. (Note: If there is not stone or marble surface, another technique is to melt less chocolate and then add good tempered chocolate in it to lower the temperature.)
4. Spread the pancake portion out in ribbons using the scraper spatula. Bring the chocolate back together into a mound repeatedly for 5 minutes, until it starts to solidify.
5. Put the chocolate back in the original heating bowl. Adding the cooler chocolate will cool the rest of the liquid to the right temperature.
6. Mix the cold and hot chocolate.
7. Check the temperature of the chocolate. (Dark: 31-32°C/88-89.5°F; Milk: 29-30°C/84-86°F).
8. Dip the parchment paper in the mixture of the “hot” and “cold” chocolate. If it cools on the parchment paper and is uniform and shiny, then it’s ready.
9. Pour chocolate into mold.
10. To make stuffed chocolate candies, flip the mold to empty excess chocolate.
11. Turn it back, scrap the excess of chocolate off the surface. Let the thin layer of chocolate in the mold crystallize.
11. Melt white chocolate. Mix it with yogurt. Cool to room temperature.
12. Add filling to 2/3 of the mold cavities, and then pour more tempered chocolate on top.
13. Level the chocolate with a scraper and scrape off excess.
14. Let it rest for few minutes at 20°C (68°F) or put it in the fridge.
15. Pop candies from mold and enjoy.

Local high-schoolers analyze real LHC data at Duke

By Ashley Yeager

Duke physicist Mark Kruse explains a few finer points of analyzing LHC data to two NCSSM students. Credit: Ashley Yeager, Duke.

Duke physicist Mark Kruse explains finer points of analyzing LHC data to two NCSSM students. Credit: Ashley Yeager, Duke.

Thin, blue lines spider across the computer screen. With a click on one, a solid blue peak on a bar graph pops up. A click on the other line makes a similar graph. Looking at them closely, two high-schoolers decide if they could be signatures of a particle called a Z-boson.

The girls — physics students from the North Carolina School of Science and Mathematics (NCSSM) — log their analysis of the lines and move on to another set. They aren’t getting too excited about their possible Z-boson discovery yet because they still have 48 other sets of lines, or events, to analyze.

Once they’ve worked through all the events, they’ll know if what they’ve seen could be due to a Z-boson decaying into pairs of electrons or muons.

“This exercise isn’t that much different than what scientists do to look for Higgs bosons,” said Duke physicist Mark Kruse, adding that the exercise is a good illustration of the particle-hunting process. “It shows you that you can’t just look at a single event and say ‘that’s a Higgs boson’.”

Kruse shared this insight with the two girls and a dozen other NCSSM high-schoolers during a Large Hadron Collider (LHC) Masterclass held at Duke on March 16. The European Particle Physics Outreach Group runs the masterclasses annually with help from university professors such as Kruse. This was the first time Duke hosted the program for local students.

During the day, they got an introduction to particle physics and research at the LHC and an overview of ATLAS, the experiment Kruse and his collaborators use to search for Higgs bosons and other particles. Then, after a tour of Duke’s Free Electron Laser facility and a pizza lunch, the high-schoolers got their hands on real LHC data.

NCSSM students work on LHC data to find hints of Z-bosons. Credit: Ashley Yeager, Duke

NCSSM students work on LHC data to find hints of Z-bosons. Credit: Ashley Yeager, Duke

They were looking mainly for events that showed possible remnants of a Z-boson. But a few Higgs-like candidates were thrown in too, which excited the students, Kruse and his two graduate students David Bjergaard and Kevin Finelli. The group may have even found a Higgs candidate in one of the first event analyses they looked at during the day.

But, as with all discoveries, they had to take a closer look at their analyses and share their work with others. The group closed the day with a videoconference with high-schoolers in Medellin, Colombia who also went through an LHC masterclass at the same time.

“This was an impressive group. They asked a lot of great questions, sparking some incredible discussion,” Kruse said. The questions — like, does anything make up a quark — are ones other audiences are perhaps too intimidated to ask because they might think it’s a silly question, he said. But it’s these questions that really get everyone thinking about the fundamentals of physics and how much scientists still don’t know, including if quarks can break down into anything smaller. This is in fact one of the many questions LHC scientists are trying to answer.

Based on the success of the class, he is now thinking of running it again for physics students from other area high schools and possibly adapting it for journalists and policymakers. The goal is to illustrate to a wider audience the “gradual, cumulative nature of discovery” at the LHC, he said.