LIGO (the Laser Interferometer Gravitational-Wave Observatory) has just announced the first ever direct detection of gravitational waves. These are ripples in spacetime itself, propagating at the speed of light, and are a prediction of Einstein’s 1915 General Theory of Relativity. They should be produced copiously in many astrophysical processes, but they are so difficult to detect that only waves produced in extremely energetic processes are detectable. The signal seen by LIGO, for example, is from the collision of two black holes, of mass 29 and 36 times the mass of our sun, and resulting in about 3 solar masses being converted into gravity wave energy in a fraction of a second. The peak power was about 50 times that of the entire visible universe!
This is a major discovery, not only for the confirmation of a long-standing prediction of general relativity, but because it opens a new window on the structure of the universe. The era of gravity wave astronomy has dawned!
This year’s Science Lecture Series at Otterbein features William Phillips of NIST, co-recipient of the 1997 Nobel Prize for Physics for his pioneering work on laser trapping and cooling of atoms. Phillips will give a public lecture entitled Time, Einstein, and the Coolest Stuff in the Universe, at 7pm On February 18, 2016, in Riley Auditorium (BFAC). The talk is free and open to the public.
On Friday, Feb 19, he will also give a more technical talk entitled The Coming Revolution in the Metric System, at 10:50am in Riley.
The Ohio Department of Education has approved funding for a seventh year of OP2: Operation Physics for Middle Grades Science Teachers. This program brings to Otterbein a group of 30 (mainly) middle school physical science teachers for an intensive course in basic physics principles with lots of hands-on activities.
Check out the winners of the 32nd annual American Physics Society Division of Fluid Dynamics visualization contest.
Whee! Front page of Otterbein.
Some of my favorites:
“Rain comes from holes in clouds.”
“Gases are not matter because most are invisible.”
“Batteries have electricity inside them”
Most of these are familiar to us as instructors, even after students reach college…
An amusing project from NIST for using a LEGO “Watt balance” — the device used in the recently updated definition of the kilogram — to measure Planck’s constant h. I’ll be firing this one up at home, for sure!
Following on from the 2015 Nobel Prize, the Sudbury Neutrino Observatory has just been awarded the 2016 Breakthrough Prize:
The Physics prize is shared amongst multiple collaborations, including SNO, Super-K, K2K, KamLAND, and Daya Bay.
(As you all know, I did my graduate work on SNO. I also worked for a year on Daya Bay shortly before coming to Otterbein.)
Neutrinos continue their glorious ascendency.
My experiment is seeing first data! Hooray! Neutrinos in liquid argon, everyone!
Look at all that gorgeous structure. Straight lines are muons or pions. It looks like there’s a cosmic ray going down through the middle of the neutrino event, and there’s also what looks like a nice gamma ray (or pi-0) coming out the bottom. Lovely!
See more event pics here: http://www-microboone.fnal.gov/first-neutrinos/
From the press release:
Today the MicroBooNE collaboration announced that it has seen its first neutrinos in the experiment’s newly built detector.
“It’s nine years since we proposed, designed, built, assembled and commissioned this experiment,” said Bonnie Fleming, MicroBooNE co-spokesperson and a professor of physics at Yale University. “That kind of investment makes seeing first neutrinos incredible.”
After months of hard work and improvements by the Fermilab Booster team, on Oct. 15, the Fermilab accelerator complex began delivering protons, which are used to make neutrinos, to one of the laboratory’s newest neutrino experiments, MicroBooNE. After the beam was turned on, scientists analyzed the data recorded by MicroBooNE’s particle detector to find evidence of its first neutrino interactions.
“This was a big team effort,” said Anne Schukraft, Fermilab postdoc working on MicroBooNE. “More than 100 people have been working very hard to make this happen. It’s exciting to see the first neutrinos.”
MicroBooNE’s detector is a liquid-argon time projection chamber. It resembles a silo lying on its side, but instead of grain, it’s filled with 170 tons of liquid argon.
Liquid argon is 40 percent denser than water, and hence neutrinos are more likely to interact with it. When an accelerator-born neutrino hits the nucleus of an argon atom in the detector, its collision creates a spray of subatomic particle debris. Tracking these particles allows scientists to reveal the type and properties of the neutrino that produced them.
Neutrinos have recently received quite a bit of media attention. The 2015 Nobel Prize in physics was awarded for neutrino oscillations, a phenomenon that is of great importance to the field of elementary particle physics. Intense activity is under way worldwide to capture neutrinos and examine their behavior of transforming from one type into another.
MicroBooNE is an example of a new liquid-argon detector being developed to further probe this phenomenon while reconstructing the particle tracks emerging from neutrino collisions as finely detailed three-dimensional images. Its findings will be relevant for the forthcoming Deep Underground Neutrino Experiment, known as DUNE, which plans to examine neutrino transitions over longer distances and a much broader energy range. Scientists are also using MicroBooNE as an R&D platform for the large DUNE liquid-argon detectors.
“Future neutrino experiments will use this technology,” said Sam Zeller, Fermilab physicist and MicroBooNE co-spokesperson. “We’re learning a lot from this detector. It’s important not just for us, but for the entire neutrino community.”
In August, MicroBooNE saw its first cosmic ray events, recording the tracks of cosmic ray muons. The recent neutrino sighting brings MicroBooNE researchers much closer to one of their scientific goals, determining whether the excess of low-energy events observed in a previous Fermilab experiment was the footprint of a sterile neutrino or a new type of background.
Before they can do that, however, MicroBooNE will have to collect data for several years.
During this time, MicroBooNE will also be the first liquid-argon detector to measure neutrino interactions from a beam of such low energy. At less than 800 MeV (megaelectronvolts), this beam produces the lowest-energy neutrinos yet to be observed with a liquid-argon detector.
MicroBooNE is part of Fermilab’s Short-Baseline Neutrino program, and scientists will eventually add two more detectors (ICARUS and the Short-Baseline Near Detector) to its neutrino beamline.