Friday, September 30, 2011

So Long, Tevatron!

Thank you, and goodbye, Tevatron.

Don't miss the streaming broadcast of the shutdown of the Tevatron today, for those who are not able to be there in person for the event.


Thursday, September 29, 2011

The Day Before The End

On the eve of the Tevatron shut-down, Fermilab scientists and its partners urged for continued funding of the intensity frontier in high energy physics. Towards this end, they are pushing for funding of LBNE.

The idea of moving more particles, rather than more energy, is what will make the LBNE project complimentary to, rather than competing with, projects like the Large Hadron Collider at CERN in Europe.
 It will be a tough sell during a time like this. One can only hope that the publicity surrounding the shut down of the Tevatron, thus ending all particle collider experiments on US soil for the first time since such an experiment was conducted, might make some people to think hard about what they are doing.


Wednesday, September 28, 2011

Don't Jump to Conclusion Faster Than c!

Needless to say, I've had a lot of questions coming my way regarding the recent neutrino results from OPERA. You'll notice that I've tried to refrain from making any kind of analysis and commentary on this thing. But it appears that my lack of response to it seems to be causing even more questions and prodding for me to say something.

Actually, I intend to. However, I need to know quite a bit more of what is going on beyond just what they had put down on their preprint. And being at a place where I have access to people who work at CERN (through the ATLAS collaboration), and people working on MINOS, provides me some advantage of talking to them and getting their feedback. But that takes time, because these people themselves are inundated with similar questions.

I'm saving more of my comments till later next week. That's when the MINOS people here will have a chance to make their presentation and comments on this result. However, just to wet your appetite, I will describe the common theme that has been running through many of the people I've spoken to.

A very important factor here is the pulse length. The proton beam that hits the target as about, what, microsecond pulse length. This beam collision with the target creates muons, etc. that will eventually decay and create the neutrino beam in that same direction. Now, it is assumed (with good reason), that the neutrino beam will ALSO have that same pulse length. So when the neutrinos are detected, one expect the same pulse length. It is from such observation that they deduce the speed of the neutrino, very much like measuring the group velocity.

The problem here is that, the proton beam itself is quite long. If one studies the beam dynamics, one can easily envision that the tail end of the proton beam might get affected by the kicker, and that can lead to the beam not having the exact pulse length as expected when it hits the target. This affect is a bit more difficult to find and detect, unlike, say, the electronics and timing, where one can change things to double check if one gets the same thing.

There's plenty of reasons to be skeptical of the result, as one should be, as of now. We just need to let the process work itself out. I'm pretty sure the folks at MINOS and T2K will be looking at this more closely. They hold the key to the independent verification/falsification of this observation, and they are the only ones that can do that. Jumping to conclusion right now and making speculative scenario of what would happen if this is true is highly and truly premature.


Monday, September 26, 2011

Flying Circus of Physics 2011

Another event that provides the public and opportunity not only to learn physics/about physics, but also to talk to physicists. This is, I think, I yearly event at Florida State University, which open their doors to welcome the public.

On Saturday, FSU professors will conduct free tours through the physics department, give lecture demonstrations, planetarium shows and hands-on experiments from 10 a.m. to 4 p.m."We will have certain rooms dedicated to certain areas in physics, and each room will have a hands-on demonstration led by a professor," said Volker Crede, FSU physics associate professor.
I have a $1 wager here that says that at least a few of the questions they will be asked is about the OPERA/faster-than-light neutrinos! :)


Saturday, September 24, 2011

Brookhaven Lab Becomes APS Historic Site

Congratulations to the folks over at Brookhaven National Laboratory. The American Physical Society has designated the whole lab as an APS Historic Site, making Brookhaven the first US National Lab to attain that designation.

Since its inception in 1947, Brookhaven Laboratory has been a leader in nuclear and particle physics experiments around the globe. “Brookhaven researchers’ explorations of fundamental science have resulted in seven Nobel Prizes — five in physics — and insights into some of the most puzzling questions about matter and the universe, as well as advances across scientific fields,” said Brookhaven Lab Director Samuel Aronson. “We are proud to be recognized as an institution for the breadth and depth of these discoveries.”
Having spent 3 good years of my life there, I can certainly attest to the historical importance of this laboratory and the discoveries that have been made there.

Still, what does this recognition gets you? Does that mean that certain historically--significant building or equipment will get preserved?


Friday, September 23, 2011

Neutrinos Moving Faster Than c?

The big news right now, of course, is the report out of the OPERA collaboration at CERN of the apparent measurement of neutrinos moving faster than c.

The OPERA team fires muon neutrinos from the Super Proton Synchrotron at CERN in Geneva a distance of 730 km under the Alps to a detector in Gran Sasso, Italy. The team studied more than 15,000 neutrino events and found that they indicate that the neutrinos travel at a velocity 20 parts per million above the speed of light.
This will be big if true. So before jumping up and down that this is a major discovery, we will have to wait for several verifications, and certainly with experiments with high resolutions.

BTW, the article had a typo in one of its paragraphs:

This is not the first time that a neutrino experiment has glimpsed superluminal speeds. In 2007 the MINOS experiment in the US looked at 473 neutrons that travelled from Fermilab near Chicago to a detector in northern Minnesota. MINOS physicists reported speeds similar to that seen by OPERA, but their experimental uncertainties were much larger. According to the OPERA researchers, their measurement of the neutrino velocity is 10 times better than previous neutrino accelerator experiments.
 That "neutrons" should obviously be "neutrinos". As with OPERA, the MINOS experiment (which I've mentioned on this blog a few times) involves shooting neutrinos from Fermilab to a detector in Soudan, Minnesota.


Thursday, September 22, 2011

Celebrating The Tevatron

From Fermilab:

All are invited to attend this special event on September 30th @ Fermilab:

The Tevatron, the world’s highest-energy proton-antiproton collider, will shut down on Sept. 30, 2011. Since 1983, the United States’s most powerful atom smasher has created particle collisions and provided particle beams to fixed target experiments and test beam areas. The Tevatron has informed some of the most important fundamental discoveries of our time, such as the existence of the top quark and five baryons, which helped to test and refine the Standard Model of particle physics and shape our understanding of matter, energy, space and time. The Tevatron research program also yielded countless achievements in detector, accelerator and computing technology. This timeline highlights some of the Tevatron’s milestones.

During the next few years, the two detector collaborations that use the Tevatron, CDF and DZero, will continue to analyze data, produce results and publish scientific papers. CDF and DZero explore the subatomic world to search for the origin of mass, extra dimensions of space and new particles and forces that would help explain the nature of our universe.

Fermilab will continue investigating the science behind our universe using present and future experiments at the frontiers of particle physics. While the Tevatron has been Fermilab’s major focus in the past few decades, the laboratory's particle physics portfolio is diverse. The laboratory will continue to operate most of the ten accelerators on site and use them to continue to produce and provide particle beams for experiments involving protons, neutrinos and muons. Learn more about Fermilab's current and future experiments and the role that its accelerators will play.

2011 Physics Nobel Prize Prediction

It happens every year at this time. Thomson-Reuters produces their prediction for the Nobel Prizes to be given out in October. They have listed the one for physics this year, and it looks like the area of quantum optics and condensed matter are well-represented. It is of no surprise to me that Alain Aspect/Anton Zeilinger/John Clauser are nominated. I think it is just a matter of time that they get the award.


Street Corner Science 2011

This seems to be a yearly event. If you are going to be in downtown Chicago on Saturday, Sept. 24, 2011, you might get to ask a question to a Nobel Laureate. Leon Lederman will set up table in front of the Wrigley Building at Noon that day, and will field questions from everyone.

I wish something like this is done very often. It doesn't have to involve eminent physicists all the time. The general public doesn't get to meet, or ask, physicists many of these questions that they have, and thus have to rely on what they can find on the web, or through the media. We all know how bad those can be. So having events such as these where the public has the opportunity to listen and ask questions can and should make a difference. I highly support such things.


"The Big Bang Theory" Fact-Checker

I know a lot of people love The Big Bang Theory. I have to admit that I haven't even seen a single episode. I have nothing against it. I just don't often watch network TV, or TV series.

Still, this is an interesting article on the person responsible for doing the physics fact-checking for the show - Prof. David Saltzberg of UCLA.

But he’s a rock star because Big Bang Theory is the least-impressive thing on his resume. Saltzberg, 44, has a bachelor’s in physics from Princeton University, where he worked on the Cyclotron. He has a Ph.D. in physics from the University of Chicago and did his post-doc at CERN, the European nuclear research center. These days, when he’s not reading show scripts, he teaches a full course load at UCLA. In his free time he flies scientific balloons in Antarctica and uses hiatuses from the show to hop over to Switzerland to work on the Large Hadron Collider.
All I can say is, at the very least, this TV series tries to show some respect towards the science, rather than just making things up, or worse still, consulting someone that doesn't have the expertise.


Wednesday, September 21, 2011

Teaching "Science"

A very interesting article from The Independent about teaching physics in UK's high schools, especially at the A-level. It describe how, if you're a physics teacher, you are lumped into a more general specialization called "Science". Thus, you might be asked to also teach a biology and chemistry (but not mathematics) as a second subject, something many physics specialists may have very little interest (or knowledge) in.

The shortage of specialists may partly be because they’re forced to generalise. Prospective physics teachers also have to learn how to teach one of the other disciplines that come under the catch-all umbrella of “science”.

It was with laudable aims, including increasing uptake at A-level, that this one subject was formed out of three separate areas more than 20 years ago – but it had this unintended consequence, too. “Both schools and teacher-trainers were thinking in terms of a subject called ‘science’,” explains the Institute of Physics’ director of education and science, Peter Main. “So if you wanted to teach physics, you were a science teacher.” 

It can lead to subjects being taught by, essentially, the wrong teacher even where there is a specialist available. “There is this paradoxical situation where in some schools you’ve got physics specialists teaching biology, and in the same school you’ll have biology specialists teaching physics,” adds the institute’s head of pre-19 education Charles Tracy, a former physics teacher. “It’s often just slackness in timetabling, where it’s easier to say there’s a subject called ‘science’ and it doesn’t matter who teaches it, rather than trying to allocate specialists to teach their topics.”
They are trying to address this by initiating a program where a physics teacher can also specialize in mathematics and teach mathematics. This make a lot more sense, because a physics teacher should have quite a bit of mathematics skill and knowledge to be able to teach that subject at the A-level. Certainly, the physics specialist would not be so adverse to teaching mathematics, something more familiar to him or her than chemistry or biology.

It would be interesting to see if this is the same situation with teaching in US high schools. How many physics teachers have to teach other science subjects, just because he/she has been tagged with a "science teacher" label? Are you a science teacher having to teach a science topic that you did not specialize in?


Tuesday, September 20, 2011

Hendrik Schon Loses His PhD

A name from the past has resurfaced.

Jon Hendrik Schon, who was embroiled in a major scandal for falsifying data while he was at Bell Labs several years ago, has lost his suit against his former university. The latter revoked the PhD degree that it awarded to Schon.

A German court has ruled that it is legal to revoke the Ph.D. of disgraced physicist Jan Hendrik Schön. Schön was the center of a spectacular scandal in 2002, and the University of Konstanz revoked his Ph.D. in 2004. Although a university investigation turned up no evidence that Schön had committed misconduct while at the university, university officials asked Schön to return his doctoral certificate based on a state law that allows degrees to be revoked when the recipient proves "unworthy." Schön was found to have faked data in at least 17 papers while he was a researcher at Bell Laboratories in Murray Hill, New Jersey. 
Oh well. Not sure if this will end the sad history of this debacle, but I sure hope so. Still, while he may lose his PhD degree, he still has his undergraduate physics degree and thus, still eligible to be nominated for my "Most Attractive Physicist" contest, no? :)

Oh, one more thing. It is interesting to note that Malcolm Beasley, who headed the inquiry panel for Bell Labs to investigate this scandal, has just been elected Vice President of the APS, in line for the society's Presidency in a couple of years.


Ig Nobels

A look back at the short history of the Ig Nobels award, which will be handed out later this month. I forgot that Andrei Geim was awarded one of these things back in 2000 before winning the Nobel Prize last year.

"Andre Geim from Manchester, who won the 2000 Ig Nobel Prize in Physics, went on to win the 2010 Nobel Prize in Physics for his research on graphene."
Shows you that this doesn't break one's career! :)


Friday, September 16, 2011

The Hunt for Dark Matter

Another article on the hunt for dark matter in light of the lastest report from CRESST. This article describes a bit more on the apparent detection by CRESST, DAMA, and CoGeNT.

We just need more data, and more convincing data. And we also need to get all the detectors to agree.

Yes, yes, I know. Easier said than done. But hey, that's why this is tough. If it was easy, we would have seen it already.


Current Research on High-Tc Superconductivity

Physics Review X has published a cross section of the current research on high-Tc superconductivity, with commentaries accompanying the 3 papers that just appeared. These should be available to read for free. The papers cover the iron-based superconductors, the ever-popular cuprate superconductors, and the heavy-fermion superconductors.


Thursday, September 15, 2011

"Remembering the Tevatron: The Machine(s)"

As the day draws closer to the end of the Tevatron, we're seeing more news articles on its accomplishments. This is a more personal look at the history and life of the Tevatron, presented by someone who certainly has a first-hand connection to this machine.

Abstract: For 25 years the Tevatron proton-antiproton collider was the highest energy collider in the world. This presentation will trace the origins of the Tevatron, the challenges that were overcome in creating high luminosity collisions of protons and antiprotons, the technological achievements that drove performance a factor of 400 beyond the initial performance goals, and the legacy of the Tevatron in paving the way for ever more advanced colliders.  


Wednesday, September 14, 2011

Dark Matter There, Dark Matter Not There

I mentioned about the latest "finding" of possible WIMP dark matter by CRESST last week. Of course, this should be met with a bit of skepticism because of the nature of the experiment, and because it is in conflict with other measurements. Nature News has a coverage of the current conflict in these observations.

Leo Stodoksky, who works on CRESST II, calls the findings, which do not meet the criteria for proof in particle physics "intriguing but not definitive" because the scientists can not be sure they have properly identified and accounted for every background event that would mimic a WIMP-like signal. Other experiments using different detectors, including DAMA/LIBRA, also at Gran Sasso, and CoGeNT, located in the Soudan Underground Laboratory in Minnesota, have detected WIMP-like signals in a similar mass range. But all these results are at odds with two other experiments, XENON100 in the Italian laboratory and CDMS II in Soudan, which have found no statistically significant evidence of WIMPs in a similar mass range.
Now, some people, especially those not in science, may find this to be disconcerting. I don't. In fact, having conflict such as this is vital in science. It is part of our check and balance, and the fact that in the research front area, things don't always appear clean and neat in the beginning is good! It means that you need a lot more work to produce convincing evidence, and that we are not lemmings that just simply accept things that are flimsy.

To be accept as valid in science isn't easy, and it is a rigorous process. This is part of such a process.


Final Days of the Tevatron

The Tevatron will be shut down by the end of the month, ending a quarter of a century of very productive lifetime.

This NPR article looks back at this historic machine, and the life beyond the Tevatron for Fermilab.


Tuesday, September 13, 2011

I'm Back!

I'm back after a week of vacation. It went by so fast! I stayed away from checking anything and everything about news in physics. So, anything happened while I was gone? Have they discovered the Higgs yet? Or dark matter? Or an antidote for crackpots? No? Too bad!

I can already feel my work piling up even before I get in to the office. I always dread this first day back, even though I've been checking my work e-mail during my vacation. At least no "urgent" e-mail came my way, no news of any accidents, any major equipment when down, etc.. etc.

After today, I'm sure I'll be needing another vacation.....


Wednesday, September 07, 2011

Cresst Detected 67 Possible Dark Matter Events

Oh, here we go again.

The Cresst experiment in Italy has reported 67 possible dark matter events, possibly from WIMP interactions.

Cresst is just one laboratory dedicated to catching the flighty particles in deep underground detectors.

It uses 33 lumps of a crystal called calcium tungstate. When a Wimp smashes into an atomic nucleus within the crystals, the experiment is designed to see evidence both of a phonon and a photon - the sound and the light of the interaction.

The Cresst team says that in their experiments between 2009 and 2011, they have seen 67 such events that cannot be explained by other means.

The data are at a level of certainty of more than "four sigma" - strong suggestions, but still shy of what can formally be called a discovery.

We'll have to give this quite a bit of time for it to be properly digested and verified.


Monday, September 05, 2011

Symphony of Science

This is a rather innovative way to "promote" science. I put that word in quotes because I'm not sure how effective it is, but it doesn't distract from a rather unique way of conveying various words and speeches of famous scientists.

In any case, if you have not stumbled upon the Symphony of Science page, you should check it out. You could download the tracks or the entire album of the Symphony of Science, and a donation to the creator of the work would certainly be appreciated.

Very clever.


Friday, September 02, 2011

How to See a Recently Discovered Supernova

All you amateur (and not so amateur) astronomer, here's your chance to find out how you can catch a glimpse of the recently-discovered supernova "in our backyard".


A "Mirror" Made Of A Single Atom

This is a very clever experiment. A group of physicists has managed to construct something similar to a Fabry-Perot interferometer, with one of the mirrors being replaced by a single barium ion, thus effectively using that ion is the "second mirror".

Hétet, Blatt, and colleagues replaced the second mirror with a single atom—actually a barium ion. To focus the light on the atom and collect the light bouncing off it, they put a 1.5-centimeter-wide lens between it and the mirror. To hold the ion steady 14 millimeters away from the mirror, they captured it in an electronic trap and used other laser beams to cool it so that it jiggled no more than 20 nanometers from the trap's center. Finally, they tuned the wavelength of the light entering the interferometer so that it could "excite" the atom from a particular low-energy state to a higher-energy one. Without such a light-atom interaction, the atom can't affect the light.

You should read the rest of the article to also figure out what possible applications and studies that can come out of this.

An amazing piece of experimental work.


Thursday, September 01, 2011

"Using Isomorphic Problems to Learn Introductory Physics"

There is a difference between learning physics, and learning ABOUT physics. I've mentioned this several times before, especially in this blog entry. Simply having a set of disconnected information isn't meaningful in physics, because one can't do anything with it, and one does not have an understanding of how things are connected to each other.

The newly-published paper on the study of how students learn to solve isomorphic problems based on the same principle indirectly illustrates the difference between understanding physics, and merely understanding about physics. In it, the authors describe, based on other studies, of groups of students given two types of   problems: (i) problems that looks, on the surface, to be different, but actually are based on the same principle and (ii) problems that, on the surface, looks similar, but are based on different principles. They now make a similar test, but this time, giving students 2 sets of problems, one solved, and another one that is analogous to the solved problem. The students are then asked to solve the second problem.

Abstract: In this study, we examine introductory physics students’ ability to perform analogical reasoning between two isomorphic problems which employ the same underlying physics principles but have different surface features. Three hundred sixty-two students from a calculus-based and an algebra-based introductory physics course were given a quiz in the recitation in which they had to first learn from a solved problem provided and take advantage of what they learned from it to solve another problem (which we call the quiz problem) which was isomorphic. Previous research suggests that the multiple-concept quiz problem is challenging for introductory students. Students in different recitation classes received different interventions in order to help them discern and exploit the underlying similarities of the isomorphic solved and quiz problems. We also conducted think-aloud interviews with four introductory students in order to understand in depth the difficulties they had and explore strategies to provide better scaffolding. We found that most students were able to learn from the solved problem to some extent with the scaffolding provided and invoke the relevant principles in the quiz problem. However, they were not necessarily able to apply the principles correctly. Research suggests that more scaffolding is needed to help students in applying these principles appropriately. We outline a few possible strategies for future investigation. 

But what is fascinating and totally reflects that I have been arguing, is a couple of paragraph in the paper's text:

It is well known that two physics problems that look very similar to a physics expert because both involve the same physics principle do not necessary look similar to the beginning students. Research has shown that when physics experts and novices are given several introductory physics problems and asked to categorize the problems based upon similarity of solution, experts tend to categorize them based upon the fundamental physics principles (e.g., conservation of mechanical energy, Newton’s 2nd law, etc.) while novices tend to group them based upon the surface features such as pulley or inclined plane. Similarly, when a group of introductory physics students and physics faculty were asked to rate the similarities between different pairs of problems, it was found that for problem pairs which only involve surface similarity but employ different principles students were more likely to rate them as similar compared to the faculty members. The different patterns that experts and novices discern in these problems reflects the difference between the ways in which the knowledge structure of experts and novices is structured and how they exploit it to solve problems. The fact that experts in physics have a well-organized knowledge hierarchy where the most fundamental physics principles are placed at the top, followed by layers of subsidiary knowledge and details, facilitates their problem solving process, allowing them to approach the problems in a more effective and systematic way. It also guides the experts to see the problems beyond the surface features, and makes the transfer of knowledge between different contexts easier. 
 You may read the entire paper and what was tested upon. I'll copy the conclusion of the paper here:

In summary, deliberately using isomorphic worked-out examples to help students transfer what they learned from one context to another can be a useful tool to help students understand the applicability of physics principles in diverse situations and develop a coherent knowledge structure of physics. For introductory students, such well thought-out activity could provide a model for effective physics learning since the idea of looking at deep similarities beyond the surface features is enforced throughout the activity. It is possible that students will become more facile at the analogical reasoning processes if practice and feedback are constantly provided to them. The greatest benefit may be achieved if similar activities are sustained throughout the course over different topics and the coherence of physics as well as the importance of looking at the deep features of the problems is consistently explained, emphasized, demonstrated, and rewarded by the instructors.
What is important here is that it takes knowledge and skills to be able to look at a problem, and break it down into its relevant components, especially in figuring out what are the relevant principles involved. This is what is lacking when you simply present physics either via examples, or via analogy, without the mathematical formalism and without a clear presentation of the central principle. This is what is done in pop-science books, which isn't bad since that is what you have to do to present such material to the general public, but you are not teaching physics here.