Class blog for "The Unstable Nucleus" at the School of the Art Institute of Chicago

Tuesday, September 29, 2009

Ground Zero 1945: Pictures by Atomic Bomb Survivors

Artwork

HORIKOSHI Susumu 堀越 進 (ほりこし すすむ)
Growing mushroom cloud, glittering silver under the mid-summer sun.
真夏の太陽に照らされて銀色に輝き大きくなっていったキノコ雲
Year of Birth: 1938 \ Age at time of blast: 6 \ Age when image created: 36
Date of image depicted: 1945/8/6
Distance from hypocenter in meters: 30000
Hiroshima Peace Memorial Museum
GE03-02

The following is unaltered text from the Hiroshima Peace Memorial Museum database:
Silver mushroom cloud / Drawing / Susumu Horikoshi / Approx. 30km from the hypocenter, Kake-cho, Yamagata-gun / Susumu Horikoshi (then 6) saw the flash and heard a loud roar as if lighting had struck nearby. Soon, from the other side of the mountain, a mushroom cloud rose into the sky. As the cloud gradually swelled it glinted a brilliant silver under the sun.

銀色のきのこ雲 /  絵/堀越進氏爆心地から約30km /   山県郡加計町 / 堀越進さん(当時6歳)は、ピカッと光った後、雷が落ちたような大きな音を聞きました。まもなく山の向こうにきのこ雲が立ち上っていました。きのこ雲は、太陽に照らされ銀色に輝き、徐々に大きくなっていきました。

**絵中 : 昭和二〇年八月六日午前八時十五分 / ピカーと光り三秒位い後にドカーンと雷が落ちたような大きな音がし、まもなく山の向うに大きなキノコ雲が真夏の太陽に照らされて銀色に輝き、だんだん大きくなっていった。 / 当時八才だった私は爆心地より北方約三〇キロ広島県山県郡加計町安野渡畑より見る。 / **裏 : 堀越進絵 (原爆の絵)

Massachusetts Institute of Technology ©2005 Visualizing Cultures


Living in the only society to ever use a nuclear weapon against other human beings, I think there needs to be an understanding of just how catastrophic the effects of such a weapon can be. The link is to a UCLA project where they compiled the stories and art work of nuclear blast survivors from Japan.


- Matt Ruiz

Ground Zero

Ground Zero II

Have you ever wondered what would happen if a nuclear bomb goes off in your city? With Google's Maps framework and a bit of Javascript, you can see the outcome. And it doesn't look good.


Now with Nuclear Fallout, Wind and Pressure

Just what you need to be safe in these turbulent times: enter the address of that boss, teacher, colleague or loved one and then Nuke It

Use the Tabs to navigate to other views. Use the Wind Rose to change the dispersion of fallout.

About Ground Zero II

  • Where's the older version?
    Still hosted with us - Just click here to see it
  • GZ II doesn't work!
    Make sure your browser supports the jQuery library: most of the post-2005 browsers do.
  • The screen is too small
    GZ II may not display correctly or the page layout may overlap and obscure the map. A large screen will solve this.

    Science Caveat

    The damage caused by a nuclear explosion is affected by a multitude of variables, and some of these require powerful super-computers to be simulated properly. The terrain, buildings and weather patterns are not part of the calculations used to map the damage.

    Fallout shows the possible dispersion of radioactive isotopes after six hours of the explosion, assuming a constant gentle breeze.

    The formulas used here are in the public domain, and were sourced from the websites of the Federation of American Scientists and from Wikipedia

    With thanks to: Jenn, Google and all those who posted witty and valuable comments, with praise and loathe for Ground Zero.

    Disclaimer: This code is posted "as is", with a Creative Commons license and neitherCarlos Labs nor any of its representatives guarantee the suitability of this script, or assume any responsibility for your actions.

    This script is free to use on any software project, free or otherwise, provided you credit Carlos Labs and you do not remove the header in the script.

    Project: 200903A


To help visualize the extent of the damage created by a nuclear blast. If your having trouble with the embedded link here is the link.
Thanks.
- Matt Ruiz

Where we get our oil:

Crude Oil and Total Petroleum Imports Top 15 Countries
Crude Oil Imports (Top 15 Countries)
(Thousand Barrels per Day)
Country Jul-09 Jun-09 YTD 2009 Jul-08 YTD 2008

CANADA
SAUDI ARABIA
MEXICO
VENEZUELA
NIGERIA
BRAZIL
IRAQ
ANGOLA
COLOMBIA
RUSSIA
KUWAIT
UNITED ARAB EMIRATES
ALGERIA
EQUATORIAL GUINEA
ECUADOR

Total Imports of Petroleum (Top 15 Countries)
(Thousand Barrels per Day)
Country Jul-09 Jun-09 YTD 2009 Jul-08 YTD 2008

CANADA
MEXICO
SAUDI ARABIA
VENEZUELA
NIGERIA
RUSSIA
BRAZIL
IRAQ
ALGERIA
ANGOLA
COLOMBIA
VIRGIN ISLANDS
KUWAIT
UNITED KINGDOM
UNITED ARAB EMIRATES

Monday, September 28, 2009




Came across this interesting image for the second time, very thought provoking. -Eli Skipp
BEST PHONES (low radiation) WORST PHONES (high radiation)
Samsung Impression (SGH-a877) [AT&T] Motorola MOTO VU204 [Verizon Wireless]
Motorola RAZR V8 [CellularONE] T-Mobile myTouch 3G [T-Mobile]
Samsung SGH-t229 [T-Mobile] Kyocera Jax S1300 [Virgin Mobile]
Samsung Rugby (SGH-a837) [AT&T] Blackberry Curve 8330 [Sprint, U.S. Cellular, Verizon Wireless, MetroPCS]
Samsung Propel Pro (SGH-i627) [AT&T] Motorola W385 [U.S. Cellular, Verizon Wireless]
Samsung Gravity (SGH-t459) [CellularONE, T-Mobile] T-Mobile Shadow [T-Mobile]
T-Mobile Sidekick [T-Mobile] Motorola C290 [Sprint, Kajeet]
LG Xenon (GR500) [AT&T] Motorola i335 [Sprint]
Motorola Karma QA1 [AT&T] Motorola MOTO VE240 [Cricket, MetroPCS]
Sanyo Katana II [Kajeet] Blackberry Bold 9000 [AT&T]

This is a chart I came across on digg.com describing which phones emit the most radiation and which the least. The topic of cell phones and other everyday objects and their potential danger has come up several times so I thought this would clarify some things.
It's odd, it looks like some of the newer phones are progressively getting worse, something to look out for in the future...

~Ethan Stuart

Sunday, September 27, 2009

Wow, what a messy situation with Iran

Thanks to everyone for all the posting over the last few days. It's been pretty interesting watching what's developing with Iran! Today, you may have also heard news stories about Iranian missile tests. While Iran doesn't currently have the capability to build nuclear missiles, the missile testing exercises they are doing now are a signal that they are ready and able to retaliate if Israel, the U.S., or a broader coalition attempts strikes.
New York Times article on the missile tests (there are more planned tomorrow)

It's estimated that Iran could, if it decided to "go nuclear", potentially have its first testable bomb on a timescale of about a year from now. They still maintain that they have no intentions of doing this, but it's clear that almost nobody in the international community believes them. Even Russia, who has been reluctant to join with western countries in imposing strict sanctions, has been softening that position a bit in light of the recent indications that Iran is pursuing an aggressive uranium enrichment program.

So what could be done to prevent a nuclear-armed Iran? Well, as you read below in some of the previous postings, stricter international sanctions are the preferred option according to U.S. Defense Secretary Gates:
L.A. Times article on Gates' position

There was an interesting editorial today in the Wall Street Journal that basically takes the position that sanctions will never be able to prevent a nuclear-armed Iran. It argues that the choice we have is basically another war in the short term, or dealing with Iran as a nuclear state in the long term. The author is Eliot Cohen, a conservative who has previously advocated military action in Iran (and who was one of the early voices supporting the decision to invade Iraq). He doesn't seem to think the Obama administration has the "stomach" for invading Iran, but he does think we should be looking for "harder" rather than "softer" solutions.
Eliot Cohen's editorial on the only choices left on Iran

All of this stuff going on overrides much of the material I had planned for our next class - please keep reading up on what's happening, and we'll spend a good chunk of time talking about it.

Thanks again for posting!

Kathryn

Friday, September 25, 2009

Iran defends new enrichment plant

http://english.aljazeera.net/news/middleeast/2009/09/200992581942180430.html

Mahmoud Ahmadinejad, the Iranian president, has reacted strongly to international condemnation of the Islamic Republic's second uranium enrichment facility, saying it was within the "parameters of the UN nuclear watchdog's rules".

Ahmadinejad's remarks on Friday came hours after Barack Obama, the US president, and other world leaders accused Tehran of "breaking rules".

"It's not a secret site," Ahmadinejad told a news conference in New York, saying he would have no problem allowing international inspections.

He also said Israel "wouldn't dare to attack" Iran and that Iranians were able to defend themselves.

Marc Vidricaire, a spokesman for the International Atomic Energy Agency (IAEA), told Al Jazeera on Friday that Tehran had notified the body of the second enrichment plant's existence in a letter earlier this week.

Iran was previously known to have one enrichment plant at Natanz, in central Isfahan province, which is under daily surveillance by IAEA inspectors.

"On 21 September, Iran informed the IAEA in a letter that a new pilot fuel enrichment plant was under construction in the country ... the enrichment level would be up to five per cent", Vidricaire said.

'Direct challenge'

Obama said that the new facility "demonstrates Iran's continued unwillingness to meet its obligations under UN Security Council resolutions and IAEA requirements".

"We expect the IAEA to immediately investigate the disturbing information and to report to the IAEA board of governors.

"Iran's decision to build yet another nuclear facility, without notifying the IAEA, represents a direct challenge to the basic compact of the centre of the non-proliferation regime."

"Iran is on notice that when we meet with them in October they are going to have to come clean and they are going have to make a choice - are they going to go down the path of giving up the acquisition of nuclear weapons and abide by international standards in their pursuit of peaceful nuclear energy or continue going down a path that will lead to confrontation," Obama later told a press conference in Pittsburgh.


"The international community has spoken. It is up to Iran to respond.

"I am not going to speculate on the type of action we are going to take. I am going to give October 1st a chance. But we do not rule out any options when it comes to US security interests."


The New York Times reported that the facility was being built inside a mountain near the city of Qom, where Iran's supreme leader and the country's influential clerical leadership are based.

Ali Akbar Saleri, the head of Iran's nuclear agency, told the AFP news agency that the facility was never "secret".

"This installation is not a secret one, which is why we announced its existence to the IAEA," he said.

"When I took over the job in July I committed myself to accelerate co-operation [with the IAEA] and within the existing framework of regulations of our cooperation with the IAEA we announced the existence of this insdtallation to the agency."

Iran's ISNA news agency reported an unnamed source as saying it was similar "to the Natanz enrichment facility".

'Pilot plant'

Al Jazeera's Rob Reynolds, reporting from the G20 summit in Pittsburgh, where world leaders are gathered to discuss the economic crisis, said the New York Times was reporting that Iran sent the letter to the IAEA after Western agents learnt of the facility's construction.

"They sent a very cryptic letter to the IAEA simply saying that a new 'pilot plant' was under construction but not providing any details of where it was or how many centrifuges were included," he said.

Reynolds said that the revelation would "cast a shadow" over talks between Iran and the so-called P5+1 of the United States, Britain, China, Russia, France and Germany, which are scheduled to start on October 1.

"Perhaps it makes it less likely that anything will be achieved there," he said.

"And it will probably make it more likely that if there is no progress in those talks, if those talks fail, that additional sanctions will be applied to Iran."

Iran is currently under UN sanctions for refusing to suspend enrichment and failing to clarify suspicions that its nuclear activity is aimed at developing atom bombs, not generating electricity as it says.

International criticism

Speaking alongside Obama on Friday, Gordon Brown, the British prime minister, said that he would not let the issue rest and said that he was prepared to push for "further and more stringent sanctions".

China said that negotiations should be the means though which the dispute is resolved and expressed its hopes that the October 1 meeting "will achieve results".

Russia's president urged Tehran to fully co-operate with any IAEA investigation.

Dmitry Medvedev said in a statement that Iran must offer "convincing proof of its intention to develop nuclear energy solely for peaceful aims".

Ban Ki-moon, the UN secretary genera, voiced serious concern that Iran is building a new uranium enrichment facility in a meeting with Iran's president on Friday.

Ban expressed his "grave concern about its (Iran's) activities related to continued uranium enrichment as demonstrated by the construction of a new uranium enrichment facility," Ban's press office said in a statement.

"He emphasized that the burden of proof is on Iran," the statement said.

John Large, a nuclear engineer based in the UK, told Al Jazeera that the new facility showed that the international non-proliferation system, operated by the IAEA, had simply failed.

"Once Iran develops the centrifuge technology, which it seems to have done, then it is a relatively straightforward step to transfer that technology into a production unit in another location," he said.

"That provides all sorts of opportunities for detouring material away from the main production plant ... [and] finishing to a nuclear weapons grade enrichment level at this new plant.

"The logic of Iran's enrichment programme, has been very much doubted, because it just simply doesn't have the civil nuclear reactor capacity to demand an enrichment programme that it has in place."

...

~Saraswati and Marissa

Can Sanctions Work Against Iran? (Abe Homer)

President Obama and the leaders of Britain and France on Friday accused Iran of building an underground plant to manufacture nuclear fuel and hiding the operation from international weapons inspectors for years.

The leaders gave Iran gave two months to comply with international demands or face increased sanctions. Prime Minister Gordon Brown of Britain said the international community “has no choice today but to draw a line in the sand.” Iran’s president, Mahmoud Ahmadinejad, denied that the plant was a secret.

What kinds of sanctions would work in this situation? What strategies might be deployed against Iran now?


Make Sanctions Even Harsher

Gary Milhollin

Gary Milhollin is the director of the Wisconsin Project on Nuclear Arms Control and Valerie Lincy is a senior research associate at project. They edit the project’s Iranwatch.org Web site.

Today’s revelation that Iran has been building — in secret — a uranium enrichment plant should dispel any doubts about the true nature of Iran’s nuclear program. Why would Iran hide such a site — capable of fueling weapons as well as reactors — if it is merely civilian in nature?

If the United States and its partners fail to win an immediate and total freeze of uranium enrichment when they sit down with Iran on October 1, then a policy of economic and diplomatic isolation is in order.

Attacking Iran’s nuclear sites would start another war, and the chance of destroying all of Iran’s nuclear sites is slim.


There are only three options at this point. The best is strong sanctions applied by a coalition of like-minded countries, led by the United States. The other two are living with a nuclear-capable or nuclear-armed Iran, or bombing those nuclear and military sites in Iran that we know about.

Given Iran’s belligerence toward the United States and Israel, its support of terrorism, and its bloody repression of domestic opposition, allowing Iran to get the bomb is simply too dangerous. Attacking Iran’s nuclear sites would start another war in the Middle East that is hard to see the end of, and the chance that a bombing campaign would destroy all of Iran’s nuclear sites is slim. This leaves sanctions, which, to have any chance of causing Iran to give up its nuclear work, will have to be put into place quickly.

The first, and easiest, would be to end public subsidies of economic development in Iran through loan guarantees. All developed countries (Japan, the E.U., etc.) should stop using taxpayer money to guarantee investments in Iran. Many governments have cut back on such guarantees — they should now end them.



Define and Isolate

George Perkovich

George Perkovich is director of the nuclear policy program at the Carnegie Endowment for International Peace.

Iranian leaders insist they do not want nuclear weapons. That is good. The United States and others should not assert otherwise. Rather, the focus should be on defining what are peaceful nuclear activities, which are all that Iran says it wants to pursue, and what are military nuclear activities.

Iran acknowledges it has no right to do the latter so we should cooperate with Iran in peaceful nuclear activities. For example, we could offer to help it build a small new reactor to produce medical isotopes without using highly enriched uranium, once Iran has answered all the International Atomic Energy Agency’s questions and restored international confidence.

Perhaps the U.S. could offer to help Iran build a small new reactor to produce medical isotopes without using highly enriched uranium.

At the same time we should define with Russia, China and other Security Council members a list of nuclear-related activities that have no non-military purposes. These activities would, in effect, define weaponization and mark the firewall between peaceful nuclear energy and nuclear weapons. If Iran, despite its pledges, undertook one of these specified weaponization-related activities, Russia, China and other Security Council members would be committed to the strongest possible sanctions.

Defining the line between peaceful and military nuclear programs would apply to all countries. However, some activities — like uranium enrichment — can be done for peaceful or military purposes. To give confidence that they are peaceful, states that want to undertake those activities would have to adopt reporting and transparency requirements at least as robust as the I.A.E.A. additional protocol.



Not Many Options

Anthony H. Cordesman

Anthony H. Cordesman is Arleigh A. Burke Chair in Strategy at the Center for Stategic and International Studies and the author, most recently, of “Iraq’s Insurgency and the Road to Civil Conflict.”

We need to pursue every diplomatic option we can, and keep exploring different mixes of sanctions and incentives to see if there is a way to change Iran’s behavior. We also need to understand, however, that this is an ideological and authoritarian regime that has “gamed” the West ever since it came to power.

International pressure may be able to keep Iran from open testing of nuclear weapons and deployment.

Iran developed covert purchasing networks during the Iran-Iraq War, and it has systematically built up it missile and nuclear capabilities since it first came under chemical and missile attack from Iraq. We know from work by the International Atomic Energy Agency, and from Iranian disclosures, that Iran has done far more than simply improve its uranium enrichment capability. It has acquired all of the triggering devices, specialized explosive and lens technology, neutron initiator components, and uranium machining capability needed for fission weapons.

It acquired significant amounts of Chinese and North Korean nuclear weapons design data, possibly through the A.Q. Khan network. It has developed the capability to build medium range missiles with high payloads that can carry nuclear warheads. It has also spread this activity into dozens of facilities and well over a hundred major buildings.

A list of the nuclear facilities and their functions Iran has declared as of Friday 25th of September

http://news.bbc.co.uk/2/hi/middle_east/4617398.stm



Julie Brower

Monday, September 21, 2009

Threads of our conversations

Below are some articles and readings that relate to several of the various threads of our discussions.

Iran:

First of all, the situation with Iran (posturing and negotiations over its nuclear program) continues to unfold. I found the following Q&A to be particularly interesting, in thinking about the dynamic between Iran and Israel:
Reuters Q&A on Iran and Israel
As we go further in our discussions in this class, we'll talk a lot about nuclear weapons as "deterrence". Is it a likely outcome that Iran will develop a nuclear weapon, and Israel and Iran will settle into a mutual-deterrence situation? Or will Israel feel it's necessary to strike Iran to cripple Iran's nuclear infrastructure, with or without the support of the U.S.? The critical October 1 deadline for international talks is looming.
Washington Post article on Iran's current stance
Iran continues to maintain that it is not pursuing nuclear weapons. However, the tensions with Israel are still obviously very high.

Everyday Radiation Exposure:


By now, we've talked about how all of us are exposed to radiation (from natural and technological sources) every day. The American Nuclear Society makes a handy little chart that you can use to add up your own typical radiation exposure. This is an interesting document on several levels. I'd like everyone to download it and fill it out before class next week - we will discuss what we find.
American Nuclear Society radiation dose chart


Thinking about Risk: a Case Study

In the last week, there was a senate hearing on whether or not there is good evidence that cell phones can cause brain cancer. This is an issue that just does not die - the last time that I taught a class dealing with radiation was over 5 years ago, and there were articles in the news at that time that were virtually identical to the ones that popped up in the last week. Reviewing this latest batch of articles, it doesn't sound like there has been much progress on the issue in that time period. The official conclusion from the senate hearings was that not enough is known to tell whether or not cell phones pose a risk.

In class, we have talked about the fact that the mechanisms by which low-energy electromagnetic radiation can affect biological tissues are very different from the mechanisms by which high-energy nuclear radiation affects those tissues. That's a point I want to make very clear - the radiation from your cell phone is a different beast entirely from the radiation from nuclear fallout, as an extreme example. So in some sense, cell phone radiation is off-topic for this class. However, I think this issue is a very good case study for thinking about the nature of risk, risk assessment, and acceptable risk.

As you browse the following readings, think about these issues in that more general context.

Overview on the senate hearings, from CNET

This fits into a larger debate about "electromagnetic fields (EMF)" and "radiofrequency (RF) radiation" and their health risks. Recall that radio frequencies are frequencies of "light" waves that have relatively long wavelengths. Technically "radio" includes "microwaves" as a subset. All forms of radio frequency radiation (including microwaves) are non-ionizing. These are the types of radiation that are most likely to be given off by everyday electronic technologies, as well as cell phone towers, power lines, etc. The FCC is the federal agency that regulates these things, and so for one side of the story you might find it interesting to browse their FAQ page:
FCC radio frequency safety FAQ
(there is a lot here, so no need to read all of it to get a flavor.)

For the other side of the story, there are quite a few private groups that are highly concerned about radio frequency radiation. When you read their websites, you get a very different idea of what is going on. While the FCC claims to base its guidelines on established science, anti-RF groups seem to find a lot of experts who are convinced that exposure to radio frequency radiation is definitely harmful. See, for example:

Electromagnetichealth.org "quotes from the experts"

What do you make of this? Is this a situation where we should all apply the "ALARA" principle as well, and avoid our cell phones as much as possible? Or do you think that groups like the Electromagnetichealth.org folks are alarmist? I look forward to your thoughts and comments.

Followup on imaging of the atom: some new images of molecules

As a followup on that interesting post from Eli on "seeing" atoms, here is another article I found recently on "seeing" molecules:

Article on recent imaging of molecules.

Thursday, September 17, 2009

The Hunt for Dark Matter

Not quite on topic, although briefly mentioned, but still very cool!:

The hunt for dark matter

MIT physicists are working on new detectors that may, at last, help them find the elusive particles thought to constitute up to a quarter of the universe.
Anne Trafton, MIT News Office

In a basement laboratory at MIT, assistant professor of physics Jocelyn Monroe is making some final adjustments to her team's newest particle detector. In just a few months, the detector will be 1,600 feet underground in Carlsbad, N.M., searching for the elusive particles known as dark matter.

Dark matter — considered one of the most baffling mysteries in science — is believed to make up 20 to 25 percent of the universe, while visible matter makes up only four percent. However, dark matter has never been directly observed, and scientists aren't even exactly sure what kind of particles they are looking for.

Scientists theorize the existence of dark matter to explain observations that suggest there is far more mass in the universe than can be seen. Because dark matter does not absorb or emit light, it has thus far proven impossible to detect. "There's a lot of dark matter out there, and nobody knows the best way to look for it," says Monroe.

Identifying dark matter is a fundamental pursuit, says MIT physics professor Peter Fisher, who has been studying dark matter for 20 years. "If you go way back in time, to the Neanderthals sitting around the fire, one of the first questions humans ask themselves is, 'what is the world made of?'" he says.

Dozens of research groups around the world are racing to be the first to detect dark matter. A few have reported possible detections in the past year, but those findings are not widely accepted.

Monroe, Fisher and associate professor Gabriella Sciolla have devised a new way to look for dark matter, taking advantage of the prediction that the particles should approach Earth from a certain direction in space.

'Solid evidence'

Caltech researcher Fritz Zwicky first proposed dark matter in the 1930s as a way to explain discrepancies between the inferred mass and the light output of a cluster of galaxies. Zwicky found that the amount of light coming from stars in the Coma galaxy cluster was about 100 times lower than would be expected from a cluster of its mass.

At first, other physicists assumed the missing mass must be gas or dust, but scientists have since embraced dark matter as a way to explain Zwicky's astronomical observations and others that don't add up. For example, spinning galaxies generate centripetal force that would tear them to shreds if not for the counteraction of gravity. However, there isn't enough visible matter in those galaxies to produce the necessary gravitational pull, so physicists theorize that dark matter makes up the difference.

"There is solid evidence that dark matter exists. What we're missing is direct observation of dark matter," says Sciolla, the Cecil and Ida Green Associate Professor of Physics.

Physicists have devised numerous ways to look for dark matter. Some experiments look for indirect evidence of dark matter by measuring gamma rays emitted when dark matter decays, while others try to capture the distinctive electronic traces that should be left behind when dark matter collides with other particles.

One major difficulty in looking for traces of collisions is that WIMPS (weakly interacting massive particles), one of the theoretical types of particles that scientists believe may make up dark matter, have very weak interactions with normal matter.

"We expect these particles to have interactions with protons and neutrons, but the probability of those interactions is very, very small," says Monroe.

WIMPs normally pass through regular matter without interacting at all. It is estimated that the density of dark matter (if the dark matter particle is 100 times heavier than a proton) is such that there are 10 WIMPs in a two-liter bottle of soda. Fewer than one of these WIMPs will interact with a nucleus in an entire year.

To make things even more difficult, these incredibly rare interactions can be easily overshadowed by neutron collisions, which occur much more frequently and produce a similar signature in the detector. To prevent neutrons from masking potential dark matter detections, physicists install their detectors far underground, in hopes of blocking neutrons hurtling toward Earth from outer space.

Because there are so many other possible events that could masquerade as dark matter interactions, solid evidence will be required for physicists to accept any potential dark matter detection.

"You have to make a convincing argument that you're not seeing something else, and that's very hard," says Fisher.

Dark matter wind

The MIT team's new dark matter detector (Dark Matter Time Projection Chamber) is expected to start running late this year or early next year, and is designed to look for the so-called "dark matter wind."

The disc-shaped Milky Way galaxy rotates through a spherical halo of stationary dark matter. So, just as there seems to be a wind blowing toward you when you stick your arm out the window of a moving car, "there should be an opposing wind of dark matter particles blowing opposite to the direction of our motion, because we're moving and it's not," says Monroe.

This "dark matter wind" approaches Earth from the direction of the constellation Cygnus. Incoming dark matter should collide with fluorine-rich gas inside the new detector and knock off fluorine atoms, which will recoil in the opposite direction.

The researchers can compare the direction of incoming particles with the location of Cygnus, which shifts position relative to Earth every 12 hours (just as the sun appears to set and rise). That should allow them to distinguish dark matter interactions from other electronic traces picked up by the detector.

Monroe is also working on a detector called Mini-CLEAN, which will be housed in an old coalmine about a mile underground in Sudbury, Ontario. The detector, expected to start collecting data late next year, contains 300 kilograms of liquid argon. When dark matter particles collide with an argon nucleus, the nucleus recoils, producing a burst of light.

A second detector, designed to pick up neutron collisions, will be placed next to the dark matter detector. That way, interactions that show up in both detectors can be dismissed, and those appearing only in the dark matter detector can be considered reliable.

How long will it take any of these detectors to pick up dark matter interactions? That depends on chance, as well as the size and sensitivity of the detector. The sensitivity of dark matter detectors has grown by several orders of magnitude since the earliest experiments, 20 years ago, and continues to improve.

However, the lack of results so far has led some physicists, including Fisher, to question whether they're even looking for the right thing. "After a while, there should be some hint, some indication, and there really just isn't anything," he says.

But the search continues, and some are hopeful that the first sighting is not too far off. "Maybe not this year, but I would bet a good bottle of champagne it will be found within the next 10 years," says Monroe.

posted by eli skipp

First Detailed Photos of Atoms


Though scientists have been studying them for years, atoms are only now ready for their first close-up portrait.

Sep 14, 2009

By Mike Lucibella & Lauren Schenkman
Inside Science News Service

The first detailed images of atoms show various arrangements of the clouds of electrons surrounding a carbon atom. A and B depict two different arrangements of the electron clouds.


Credit: Kharkov Institute for Physics and Technology

WASHINGTON -- For the first time, physicists have photographed the structure of an atom down to its electrons.

The pictures, soon to be published in the journal Physical Review B, show the detailed images of a single carbon atom's electron cloud, taken by Ukrainian researchers at the Kharkov Institute for Physics and Technology in Kharkov, Ukraine.

This is the first time scientists have been able to see an atom's internal structure directly. Since the early 1980s, researchers have been able to map out a material's atomic structure in a mathematical sense, using imaging techniques.

Quantum mechanics states that an electron doesn't exist as a single point, but spreads around the nucleus in a cloud known as an orbital. The soft blue spheres and split clouds seen in the images show two arrangements of the electrons in their orbitals in a carbon atom. The structures verify illustrations seen in thousands of chemistry books because they match established quantum mechanical predictions.

David Goldhaber-Gordon, a physics professor at Stanford University in California, called the research remarkable.

"One of the advantages [of this technique] is that it's visceral," he said. "As humans we're used to looking at images in real space, like photographs, and we can internalize things in real space more easily and quickly, especially people who are less deep in the physics."

To create these images, the researchers used a field-emission electron microscope, or FEEM. They placed a rigid chain of carbon atoms, just tens of atoms long, in a vacuum chamber and streamed 425 volts through the sample. The atom at the tip of the chain emitted electrons onto a surrounding phosphor screen, rendering an image of the electron cloud around the nucleus.

Field emitting electron microscopes have been a staple of scientists’ probing the very small since the 1930s. Up to this point, the microscopes were only able to reveal the arrangement of atoms in the sample.

The sharper a sample’s pointed tip inside the vacuum chamber, the greater the resolution of the final image on the screen said Igor Mikhailovskij, one of the paper's authors. In the last year, physicists learned to manipulate carbon atoms into chains. With the tip of the sample now just a single atom wide, the microscope was able to resolve the electron's orbitals. The Kharkov researchers are the first to produce real images of the electrons of a single atom, making the predictions of quantum mechanics visible.

While tools like the scanning tunneling microscope already map the structure of electrons in a sample of many atoms, "it's always good to have complementary approaches," Goldhaber-Gordon said. "Sometimes something puzzling in one view becomes crystal clear in the other view. Each one gets you a step closer to a full understanding."

Goldhaber-Gordon also pointed out that the technique may not be widely applicable because the high resolution was due to the sample's specific structure.

"At the moment it's more important for displaying quantum mechanics very directly than for learning new things about materials," he said. "But that could change if [the Ukrainian team] develop new capabilities."

via InsideScience.org (http://insidescience.org/research/first_detailed_photos_of_atoms)
and neatorama.com

posted by Eli Skipp

Tuesday, September 8, 2009

Nuclear Questions

Hey folks,

Thanks for all the interesting comments and questions in class today. I wanted to post the links to the articles we discussed, and also to highlight some of the questions that you submitted to me about them (paraphrased in a couple of cases - please add your comments if you want to set me straight on something I misunderstood).

1) Priest who, at 75, is still breaking into nuclear missile sites to protest

Quite a few of you were very harsh in your criticisms of this fellow! Interesting. Is it because he's a priest? Because of the clown suit? Because nuclear weapons seem like an old, or out-of-date issue? Someone referred to him as an "extremist". Would you use that word to characterize any persistent activist, or is there something about this particular person?
I'd love to hear further comments on this...

Some of your questions:
* How safe can a missile silo be when it takes security 45 minutes to respond to an intruder?
* Does he really think *he* should be educating the public?
* Is the fact that current generations seem less concerned about nuclear weapons because younger people are less aware, or because they don't see it as a significant threat?
* How much has peace activism impacted nuclear weapons programs?

2) North Korea announces pursuit of a second path to a nuclear bomb

Some of your questions:
* What exactly does North Korea intend to do with all these nuclear weapons?
* Might other nations have hidden nuclear weapons programs in the works as well?
* If the knowledge of uranium enrichment (the 'second path') is somehow coming from a source in Pakistan, shouldn't we be worried about stopping that from spreading?
* What would be an effective way to deter North Korea from developing weapons, and should we?
* What is easier to track - centrifuges for uranium enrichment, or the facilities needed to make bombs from plutonium?
* If North Korea is just posturing by making these claims, what is it hoping to achieve?

3) Islanders moving to Hawaii feel their health care should be covered as compensation for nuclear testing done by the US in their home nations.

Some of your questions:
* How will the radiation from nuclear tests affect future generations of people living there?
* How can you tell if an illness has been caused by radiation?
* Why did we do all of this testing in the first place? Why was it necessary to perform nearly 70 nuclear tests?
* What is the actual effect on cancer rates or health problems from nuclear testing?


4) Utah nuclear waste site wants to accept imports of nuclear waste from Italy
(here is a recent update on this situation)

Some of your questions:
* How does the waste get transported to the waste site in Utah?
* Does Italy have its own nuclear waste disposal sites? Why is it interested in sending waste here?
* Where will this waste go if we don't take it at the Utah site?
* How exactly do you dispose of nuclear waste? What does that mean?
* What is this stuff? Is it dangerous or is that just popular paranoia?

5) Standoff between the UN and Iran

Some of your questions:
* Why is it that we are allowed to have nuclear weapons yet Iran can not?
* How would you go about "catching" Iran if it's actually making nuclear weapons?
* Why exactly doesn't the international community trust Iran?
* What will happen at the end of September, which is the "due date" for Iran to respond to an offer for nuclear talks with the UN?

Radiation in the News

It seems like there is always a news story somewhere about somebody being exposed to some sort of harmful radiation. Here are a few news stories I found from the last week, which deal with a variety of different radiation issues. Taken together, they are a decent introduction to the general issues surrounding radiation and our exposure to it.

1) Is your countertop exposing you to harmful radiation?
2) New radiation therapy system
3) Medical imaging and our radiation exposure
4) French government compensating veterans for exposure, even though the impact is hard to prove.
Also, here's one quick little blurb that brings up a few more questions:
5) Can you take a pill to protect you from radiation?


(Note - at least one of these sites (New York Times) requires a login to gain full access to articles. I'd encourage you to sign up. If you are really uncomfortable doing that, contact me and we'll work out some other way to get those articles into your hands)

Monday, September 7, 2009

Welcome!

This blog is a place to post links, interesting articles, photos, and comments that relate to Science 3207, "The Unstable Nucleus", at the School of the Art Institute of Chicago.