Congratulations Dr. Yeghiyan! July 26, 2011Posted by apetrov in Near Physics, Particle Physics, Physics, Science, Uncategorized.
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Today my third graduate student at WSU, Gagik Yeghiyan, defended his Ph.D. thesis. Congratulations Dr. Yeghiyan! Good luck to you in your new life as an Assistant Professor at Grand Valley State University!
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As I blogged some time ago, Italian government decided to fund a new accelerator for precision studies of New Physics in decays of heavy-flavored mesons, the so-called SuperB factory, a high-intensity B-factory, which is designed to look for glimpses of New Physics in rare decays of B- and D-mesons (for professional description of the physics case, see here; for Conceptual design Report (CDR) see here).
Last week a decision was made for a location of the site of the new machine. It will be built on campus of the University of Rome ‘Tor Vergata’. Here is the picture of the proposed site (shamelessly taken from the talk of Roberto Petronzio, President of the Italian National Institute for Nuclear Physics at XVII SuperB Workshop and Kick Off Meeting – La Biodola (Isola d’Elba) Italy):
The (“green”) site is located reasonably close (4.5 km) to another well-known Italian National Lab in Frascati, Laboratori Nazionali di Frascati (LNF). The new lab will be a CERN-like consortium. The name for the lab was proposed: Cabibbo Lab, after the great Italian physicist Nicola Cabibbo whose name is associated with some of the most important objects in flavor physics.
The new lab will bring lots of talent from all over the world and, besides experiments in high energy physics, will be used as a light source for other physics experiments. It is great that even at the time when finances are tight, European governments realize that fundamental physics is important for the future of their countries. These are exciting times for the European physics!
Update on the situation at Japan’s Fukushima nuclear plant March 15, 2011Posted by apetrov in Near Physics, Physics, Science, Uncategorized.
The situation at Japan’s Fukushima nuclear plant remains fluid, but it makes sense to do an update. It turns out that the situation is more challenging then I originally thought. To recreate what is happening (based mainly on TEPCo’s press releases and Japan’s Nuclear and Industrial Safety Agency (NISA) press releases), let us take a look at the Mark 1 BWR reactor (for a short description of physics of the nuclear power generation and schematics, please see my earlier post):
This picture was modified (by me) from the materials provided by Department of Energy’s Nuclear Regulatory Comission’s (NRC) website. It is Mark-1 BWR-type nuclear power reactor supplied by General Electric.
The Fukushima Daiichi plant operates six reactors, Units 1, 2 and 6 are supplied by General Electric (Unit 1 is the oldest, built in the 70′s — I’ve heard it was supposed to be decommissioned this Spring), while Units 3-5 are supplied by Toshiba and Hitachi. So, what is happening there?
As you already know, the magnitude 9.0 on Richter’s scale earthquake hit Japan. The reactors at the Fukushima plant were designed to withstand the 8.2 magnitude quake. Nevertheless, the structures held (note that the Richter scale is logarithmic, meaning that 9.0 earthquake releases 10 times energy than 8.0). Since Japan is located in seismically-active zone, there exist provisions on what to do in case of one, especially for the nuclear power stations.Reactors 1-3 were operational at the time of the earthquake, while reactors 4-6 were in a shutdown mode.
So, first and foremost, control rods (containing boron, neutron-absorbing material) were automatically inserted. According to TEPCo’s press release, this was done successfully at all three units that were in operation. There was an alarm on Unit 1 that one of the rods was not fully inserted. The alarm then went away. It is now believed that all control rods were fully inserted and chain reaction in fuel assemblies was stopped. Even after this, one must keep circulating water in order to continue cooling fuel assemblies due to the heat produced by decays of nuclear reaction products in the fuel rods. It needs to be done for several days.
It appears that over the course of three days reactor cooling systems kept failing, which resulted in increasing steam pressure in the reactor pressure vessel (see the picture above). In this case you really don’t want to keep the pressure rising, as it eventually would simply blow up the containment vessel and you’d get pretty much what happened in Chernobyl. So, the idea is to gradually release pressure by disposing the (slightly radioactive) steam through the vent line (see above picture). The steam is only slightly radioactive because one is using purified water, which does not get activated by the radiation from the fuel assemblies. This was done at all three units. You have to still keep cooling the core, which was done at Units 1 and 3 with injection of seawater into the Primary Containment Vessel and at Unit 2 with seawater injection into the Reactor Pressure Vessel. Injecting seawater is a desperate move, as it contains salt and other staff that can get activated. Which means that the reactor will be decommissioned regardless of whether there is a meltdown or not. Along with seawater, they injected boric acid to capture neutrons.
Now, if the cooling is ineffective (as it appears is at Fukushima) and you keep disposing steam, you lose the amount of water you have in your reactor (think of a boiling teapot). This leads to water levels in the reactor dropping to the point that the fuel assemblies get exposed to steam. This is what happened at Fukushima. This is bad, because this drops cooling efficiency and fuel rods start to heat up (recall the decays of radioactive decay products that are still going on). At some point, zirconium in the ziralloy (the alloy of zirconium and tin that makes up the fuel rod casings) starts react with water vapor. Here is the chemical reaction:
2 H20 + Zr = 2 H2 + Zr O2 + energy
which means that you start producing hydrogen (H2), some of which will escape into the reactor building. Most likely, escaped hydrogen exploded in units 1-3, blowing off the roofs of the reactor building hosting Unit 1, 2, and 3, like this:
This picture is done by the local TV station and posted on Wikipedia. According to the power station owners, the containment vessels are still intact, which is precisely what they are designed to do. Let’s hope that this is an accurate assessment.
Now, if there is a meltdown (fuel rods are damaged), some of the reaction products might get into the atmosphere (the troubling news is that the monitoring stations did detect small amounts of iodine nearby the reactor). The most immediate concern are radioactive Iodine (half-life of 8 days) and Cesium (half-life is 30 years). Iodine can accumulate in human’s thyroid gland – so the first line of defense is to saturate the gland with non-radioactive Iodine. This is why the population around the station is given iodine tablets as a precaution. The detected amounts of iodine are not of a concern for the US West Coast (too far).
In the case of a serious meltdown, the melted fuel will likely remain in the reactor containment below the rector pressure vessel. This would be bad, but still nowhere near Chernobyl’s explosion. BTW, I was on a school trip in Kiev when the Chernobyl power station blew up. I had to bury my shoes because the radioactivity levels on them were too high (dust)…
To add to the problem, rector unit 4 (which was not operational at the time of an earthquake) developed problems of its own. In particular, it appears that the personnel missed that the water level in the spent fuel pool came down. This exposed spent fuel rods that contain more long-lived radioactive isotopes. You want to keep spent fuel rods in the water to cool them, as the decays still produce heat. In this case, usual convection cooling (warm water is rising and is replaced by cooler water) is sufficient to keep them cool. That is, if there is water! There was report of a fire at the spent fuel pond. This might indicated that the water level in the pool went down and spent fuel caught on fire. This might be bad, as this would release radioactive material in the air. Japanese scientists monitor the situation.
I’ll try to keep you posted as well.
What is happening at Japan’s Fukushima Daiichi power plant? March 12, 2011Posted by apetrov in Near Physics, Physics, Science, Uncategorized.
This is a good question to ask — especially amid speculations about “possible Chernobyl-like nuclear meltdown” and pictures of explosions at the plant. Knowing a little bit of physics (and reading press-releases from TEPCo — Tokyo Electric Power Company), one can make some initial analysis. Clearly, a complete picture will follow in the near future.
So, first of all, what is the problem? To understand this, let me note that nuclear reactors at the Fukushima Daiichi plant are of the Boiling Water Reactor (BWR) type — quite different in design from Three Mile Island’s PWR-type reactor and Chernobyl’s RBMK reactor. In order to see the logic of what Japanese engineers are doing, it is useful to see how the BWR reactor works.
Here is the scheme of BWR-type reactor, taken from the Wikipedia page on BWR. The physics here is very simple. Fission reaction in the uranium fuel assemblies (2) heat water (blue stuff, 7), which turns into steam (red stuff, 6) in the reactor vessel (1). The steam exits the vessel and spins the turbine (8 and 9) that generates electricity. That steam is cooled down and returned into the reactor vessel (as water) and the process begins again.
Simply speaking, fission reaction happens when a slow (thermal) neutron is absorbed by a uranium (U-235) nucleus, which then splits into several (two) lighter daughter nuclei, and several fast neutrons (about 3), releasing energy that is converted into heat. In order to have sustained nuclear reaction one needs to slow down those produced neutrons so that they could be absorbed by other U235 nuclei to initiate chain fission reaction. Different reactor designs use different moderators to do that: water (BWR, PWR), graphite (RBMK), etc.
This simple excursion into nuclear physics tells us that the rate of power generation can regulated by controlling the flux of thermal neutrons. This is indeed what is done by the control rods (3) that are usually made of a material (boron) that absorbs neutrons.
What happens in case of an earthquake? Well, the automatic control systems first and foremost would kill the sustained fission reaction that is going in the fuel elements. This was done at the Fukushima plant immediately by inserting the control rods (notice that the control rods are inserted from below). So, what’s the problem then? Why is the water vapor’s pressure rising?
The problem is that during the fission reaction one also produces a lot of short-lived nuclear isotopes. Normally, if you would like to shut down a reactor (say, to refuel), you need to allow for some time (several days) for those isotopes to decay. During that time, water is still being circulated through the reactor core in order to take away the heat produced in the decays of those short-lived isotopes. This is done via pumps that are operated via electricity from (a) power grid or (b) diesel generators or (c) batteries. After the earthquake, the grid was knocked out and the diesel generators got damaged. The pumps are now running on the batteries and the water vapor pressure inside the reactor vessel is rising — by the way, the normal operating pressure there is about 75 atmospheres!!! TEPCo reports that the pressure there rose twice that, so the plant operators decided to release steam from the vessel. Now, to cool down the reactor (until those short-lived isotopes decay) they decided to flood the containment vessel with sea water.
So, as you see, the Chernobyl-type of explosion is highly unlikely at the Fukushima plant. I think the reactor will cool down in a couple of days. BTW, it appears that the reported explosion happened at the pumping system…
The only troubling news is that the monitoring stations appear to detect small amounts of iodine and cesium isotopes (to quote TEPCo’s press release “The value of radioactive material (iodine, etc) is increasing according to the monitoring car at the site (outside of the site). One of the monitoring posts is also indicating higher than normal level.”). Those isotopes are normally produced in the nuclear fuel rods. This might indicate that one or more rods are damaged.
Update (3/14/2011): It appears that water circulation systems in reactors 1 and 3 of the power station failed on 3/12-13. The reactor containment is now cooled by sea water (with added boric acid to further capture neutrons). Sea water is not an ideal coolant — purified fresh water is — sea water contains salt and other things that can become radioactive in the core of a reactor. Thus, the spent water will most likely be transferred to the spent fuel pools (place on the power station’s campus where spent fuel rods spend some time before being transferred to the permanent storage facility). It also appears that there were two hydrogen explosions in Units 1 and, recently, 3. Where did the hydrogen come from? It most likely came from the chemical reaction on the zircalloy’s casings of the fuel assemblies. Zircalloy, an alloy of zirconium, tin and sometimes other things, contains zirconium. That zirconium reacts with oxygen in water and releases hydrogen. It is, however, believed that in both cases the containment vessels held up. Those containment vessels did not exist at the Chernobyl’s power station.
Update (3/15/2011): I decided to put updates in the separate post.
I usually don’t comment about politics in this blog. But today I’ll make an exception. Maybe someone from Michigan Congressional delegation will read it. I’ll be happy to answer any questions regarding this situation.
Each developed country in the world has a stake in an interdependent triad that builds up its wealth and independence: fundamental research, applied research and industry. It is only the combination of excellence in those three fields that has kept the United States at the forefront of technological revolutions of the past 50 years. Elimination of one of those components will spell trouble for the remaining two: for example, defunding fundamental and applied science in the Russian Federation in the early 1990’s led to a quick demise of that country’s high tech industry.
The new Continuing Resolution (CR) bill announced on 02/08/2011 by House Appropriations Chairman Hal Rogers  imposes deep cuts on Department of Energy’s Office of Science (DOE OS), National Science Foundation (NSF), NASA and National Institutes of Health (NIH) that simply threaten US fundamental research. The cut to DOE OS’ budget of $5.12B is $1.1B. It is proposed to happen half way through the current budget year. To keep things in perspective, the amount needed to implement this cut would be equivalent to closing down all US National Laboratories for a continuous period of time this year.
Among other things, DOE’s Office of Science supports fundamental and applied research done by the University groups all over the country. In the state of Michigan that includes University of Michigan, Michigan State University, Michigan Tech and Wayne State University. This funding is neither redundant nor wasteful: each grant issued by DOE’s Office of Science, NSF or NIH is reviewed by several independent experts and expert panels. It is this funding that helps us train the next generation of scientists and engineers that will keep America prosperous in coming years. It is this funding that the new CR proposal would severely cut.
To compare, Chinese government’s spending on science and technology was slated to rise 8% to $24 billion in 2010, of which $4 billion is basic R&D . By contrast, the cuts included in the proposed Continuing Resolution bill reduce funding to basic and applied research made by DOE’s Office of Science by 18%. Liberal and conservatives commentators alike voiced concerns about how the US is losing its edge in math and sciences. This budget cut signals that there is no reason for young Americans to pursue careers in science.
The fundamental research done by particle scientists might not have immediate applications to industry. But not all basic research projects are “long shots.” The first Internet browser developed by high energy physicists at CERN (the site of currently running Large Hadron Collider) for the needs of the experiment designed to understand the basic building blocks of Nature in 1991 made possible creation of the World Wide Web and revolutionized the US and world’s commerce.
Balancing our country’s budget is an important and noble goal, but it should not be done at the expense of the future.
 House appropriation committee website http://republicans.appropriations.house.gov/index.cfm?FuseAction=PressReleases.Detail&PressRelease_id=259
A picture on a wall? February 12, 2011Posted by apetrov in Funny, Particle Physics, Physics, Science.
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I was moving old pictures from my camera to my computer today and found this image. Here is a funny picture of a reflection on my neighbor’s wall. What does it look like?
To a particle physicist, this is just a pair of Feynman graphs for 2 -> 2 scattering amplitudes… with the left one in an external field . Enjoy.
Bye-bye, Tevatron! January 10, 2011Posted by apetrov in Particle Physics, Physics, Science.
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Well, it is now official: DOE has decided not to pursue the extension of the Tevatron running until the year 2013. The operations of the Tevatron, the largest US hadron accelerator, will end at the end of this year, 2011. The details of the DOE decision can be found here.
To remind you, the original idea to extend the Tevatron running until 2013 came out because of the LHC shutdown schedule (and physics, of course), Tevatron might have been competitive with the LHC in the search for light (~ 120 GeV) Higgs. Now we have to rely solely on the LHC.
Now it’s official: Italian Government Funds the Super-B December 23, 2010Posted by apetrov in Particle Physics, Physics, Science.
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So it is official. According to Roberto Petronzio (INFN President), “The Ministry for Education, University and Research [of Italy] has decided to select the SuperB project conducted by the Italian National Institute of Nuclear Physics (INFN) as one of its “flagship projects” in Italy over the next few years and has delivered an initial funding for 2010 as a part of a multiannual funding program” (see here from interaction.org site).
This was first announced by Marcelo Giorgi (Super-B spokesperson) on December 18 at the closing of the XV SuperB General Meeting in Caltech (“SuperB has been approved and funded by the Italian government. Approval has been announced in a closed session of the CERN council. We should expect press releases with announcements from INFN and the Italian minister of science and education within the next few days,” see here). The announcement was a bit unexpected — many of my colleagues even believed that the project would never be funded, especially in such difficult times. But it happened!
This is s very good news for flavor physics. The Super-B experiment is a high-intensity B-factory, which is designed to look for glimpses of New Physics in rare decays of B- and D-mesons (for professional description of the physics case, see here; for Conceptual design Report (CDR) see here). It is a descendant of the SLAC B-factory experiment BaBar — almost literally, as parts of the accelerator and BaBar detector will be disassembled at SLAC and delivered to Italy and reassembled there. This is done as part of the US strategy of moving scientific expertise in high energy physics from the US to Europe and Asia (which started with plowing most other high energy physics programs in favor of the linear collider program that was never funded in full… actually, it is not even mentioned that often nowdays — partially because of the excitement over LHC) along with scientific leadership in that area .
So these are the exciting times for the SuperB collaboration! One important thing is that the site for the experiment is not yet chosen. Currently the possibilities include a green site at Tor Vergata or exciting site of the Frascati Lab of INFN near Rome. So hey have their work cut out for them.
Update on our faculty search in particle theory December 10, 2010Posted by apetrov in Particle Physics, Physics, Science.
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The deadline for applications for an Assistant Professorship in theoretical particle physics at WSU is December 15, five days from today. So far we received 44 applications.
Is that a lot? Well, it depends. According to some of my friends at SLAC, they receive upwards of 400 applications for their postdoctoral positions. I regularly receive about 50-60 applications for postdoctoral position — when I have one. While the numbers are not important (as long as the applicants are great — and they are!), we were planning for about 100 applications for our faculty position. Of course, WSU is not Harvard or Stanford. Also, Detroit is not Boston or Palo Alto. And, the future assistant professor would have to work more to get recognized in the field — the name of the institution will not be of much help. But this position will give that person a chance to define the program. And this person will not be alone. There is Sean Gavin (nuclear theorist), there would be another nuclear theorist next year (we also have a search for an Assistant Professor in theoretical nuclear physics) — and then, according to the Strategic Plan adopted by our Department, a theoretical cosmologist will be hired in a couple of years.All of that makes our position quite attractive.
So, what’s going to happen next? The Search Committee will meet shortly after December 15 to take initial look at the application pool. We will select a “long short lost” of 20 applicants and ask them to submit their application materials to the University’s job management system (a new requirement). Then we’ll select top five from the list of that twenty and invite them for interviews on campus.
This is an interesting year for physics at WSU. There are four (4!!!) searches going on in the physics department — particle theory, nuclear theory, nuclear experiment (heavy ion collisions — WSU has one of the largest groups in relativistic heavy ions in the US), and observational astronomy. Hopefully, we will get good people. I’ll keep you updated.
Update: we have 61 applications in our pool as of Dec 15 that we started to look at. The first serious meeting of the search committee will be in the first week of the new year.
Two theory jobs at Wayne State — and more is coming (hopefully)… October 15, 2010Posted by apetrov in Uncategorized.
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It appears that my home institution, Wayne State University (see also the Physics Dept website or University website), is going through with the Theoretical Physics expansion. We will be hiring two Assistant Professors in particle theory and in nuclear theory this year. Also, a cosmologist and a condensed matter theorist hires are planned in the near future. Given that currently there are only three active theorists in particle, nuclear and CM fields (one per each field ), this can be considered a major expansion. Please apply — but remember that all theorists who came to Wayne State Physics department after 2000 received NSF CAREER awards. So we expect nothing less from the incoming candidates (for University officials — this is a joke).
TWO FACULTY POSITIONS
THEORETICAL PARTICLE PHYSICS AND THEORETICAL NUCLEAR PHYSICS
DEPARTMENT OF PHYSICS AND ASTRONOMY
WAYNE STATE UNIVERSITY
The Department of Physics and Astronomy at Wayne State University seeks applications for two tenure-track assistant professor positions: one in theoretical high-energy particle physics and one in theoretical high-energy nuclear physics. The appointments start August 2011, and are subject to final approval by the administration.
Candidates for the particle theory position should have a high level of achievement in particle physics phenomenology. Candidates for the nuclear theory position should have a strong background in QCD matter and relativistic heavy ion physics. We are seeking candidates who
will play leadership roles in the LHC era and beyond. Successful candidates will maintain active, externally funded research programs and be committed to teaching at both undergraduate and graduate levels. A Ph.D. degree or equivalent is required and postdoctoral experience is considered important. The positions include competitive start-up packages.
The Department (http://www.clas.wayne.edu/physics/) presently consists of almost 30 faculty members with active research programs in astrophysics (SDSS and LSST), high-energy particle physics (CDF, CMS, Belle and theory), relativistic heavy ion physics (STAR, ALICE and
theory), condensed matter and materials physics, biophysics, and atomic physics.
Applicants should submit a cover letter, curriculum vitae, and statements of research and teaching interests assembled, (preferred) as a single-file PDF format attachment, for particle theory to firstname.lastname@example.org; or for nuclear theory to nucl-theory-
email@example.com; or by regular mail to:
Alexey Petrov, Chair, Theoretical Particle Physics Search Committee
Sean Gavin, Chair, Theoretical Nuclear Physics Search Committee
Department of Physics and Astronomy,
Wayne State University
Detroit, MI 48201.
Informal inquiries are welcome and should be sent to Prof. Alexey A. Petrov (particle) at firstname.lastname@example.org or Prof. Sean Gavin (nuclear) at email@example.com . Review of applications will begin December 15th, 2010.
Wayne State University is an equal opportunity/affirmative action employer. Women and minority candidates are encouraged to apply.