Cool Science Story Of The Day [Continuing Thread]

[IROC]

We hit 1.4 MW of beam power on target this past weekend. Now I'm knee-deep in changing a target...

Spallation Neutron Source staff gave its current mercury target a run for its money in its final hours of service over the weekend, and they reached the SNS design power load of 1.4 megawatts for the first time.

The target, installed last November and reduced to receiving 850 kilowatts of beam power following a couple of premature target failures, took the punishment on Sunday, ramping up to slightly more than 1.4 MW. A maintenance shutdown begins Tuesday, Oct. 1, during which the well-worn target will be changed out.

Higher beam power means more neutrons at higher intensity, so attaining the design power is good news for the neutron scattering community of users. In the meantime, the SNS will continue on the conservative side when it restarts at 850 kilowatts following the maintenance outage.

[kang]

Originally Posted by IROC

We hit 1.4 MW of beam power on target this past weekend. Now I'm knee-deep in changing a target...

wow - cool. I'm fascinated by this stuff.

So you're shooting 1.4MW worth of neutrons at some mercury? How wide is the beam?

(You should pull a Big Bang Theory trick like when they shot a high powered laser at a plastic action figure or warmed up their soup!)

[Hawkeye's-911T]

A bit 'off-topic' - but interesting

http://www.poodwaddle.com/worldclock.swf

Cheers
JB

[IROC]

Originally Posted by kang

wow - cool. I'm fascinated by this stuff.

So you're shooting 1.4MW worth of neutrons at some mercury? How wide is the beam?

(You should pull a Big Bang Theory trick like when they shot a high powered laser at a plastic action figure or warmed up their soup!)

The beam is actually protons. We start off with H- ions, accelerate them to about 90% of the speed of light and then strip the electrons off leaving a proton beam. We sell the electrons on ebay. We then "accumulate" bunches of protons in an accumulator ring and then fire pulses of protons at ~60Hz at a liquid mercury target. The beam is nominally 70mm high by 200 mm wide. The energetic protons "spall" neutrons off of the mercury molecules which are then moderated (slowed down) and used for condensed matter physics experiments.

As you can imagine, the proton irradiation wrecks havoc on the mechanical properties of most common materials, so our target module wears out and we have to replace it. The module is about as radioactive as the core of Chernobyl right when it exploded, so it is a challenging job, needless to say.

In other words, as Trekkor would say, "it's all guesses"...

[RWebb]

Originally Posted by IROC

as Trekkor would say, "it's all guesses"...

ha

I like "the neutron scattering community"...

[kang]

Originally Posted by IROC

The beam is actually protons. We start off with H- ions, accelerate them to about 90% of the speed of light and then strip the electrons off leaving a proton beam. We sell the electrons on ebay. We then "accumulate" bunches of protons in an accumulator ring and then fire pulses of protons at ~60Hz at a liquid mercury target. The beam is nominally 70mm high by 200 mm wide. The energetic protons "spall" neutrons off of the mercury molecules which are then moderated (slowed down) and used for condensed matter physics experiments.

As you can imagine, the proton irradiation wrecks havoc on the mechanical properties of most common materials, so our target module wears out and we have to replace it. The module is about as radioactive as the core of Chernobyl right when it exploded, so it is a challenging job, needless to say.

In other words, as Trekkor would say, "it's all guesses"...

Protons, of course, kind of hard to accelerate neutrons in a magnetic ring. D'oh! But then, how do you slow them down? Some sort of medium?

Wow, 70mm X 200mm is a pretty big spread! I was thinking pencil lead sized.

I'm sure stripping neutrons off mercury atoms wreaks havoc indeed. That's the understatement of the day. How many can you strip off one atom before the atom becomes way unstable?

Cool stuff! Keep on guessing!

[IROC]

Originally Posted by kang

Protons, of course, kind of hard to accelerate neutrons in a magnetic ring. D'oh! But then, how do you slow them down? Some sort of medium?

Liquid hydrogen mostly, but we also used plain old water.

I'm sure stripping neutrons off mercury atoms wreaks havoc indeed. That's the understatement of the day. How many can you strip off one atom before the atom becomes way unstable?

Cool stuff! Keep on guessing!

The "spallation products" are varied to say the least. We were having an issue with some weird isotope of Iodine today. Our higher beam powers are having an effect on our operations. The fun thing is that no one else in the history of man is doing what we are doing, so we are seeing things that no one has seen before. Very cool stuff.

[M.D. Holloway]

Anything staring back? Your gonna get the attention of a extra dimensional alian and before you know it we will be handing over all our coffee beans and brillo pads...

[Flieger]

Originally Posted by IROC

Liquid hydrogen mostly, but we also used plain old water.



The "spallation products" are varied to say the least. We were having an issue with some weird isotope of Iodine today. Our higher beam powers are having an effect on our operations. The fun thing is that no one else in the history of man is doing what we are doing, so we are seeing things that no one has seen before. Very cool stuff.

So you are half guessing.

[IROC]

Originally Posted by Flieger

So you are half guessing.

We're going to retract our "target carriage" today. It weighs 100 tons (mostly due to shielding) and moves about 30 feet to remove the target module from the Core Vessel. Contact dose rates on the target will probably be around 30,000 rads/hr (300 Sv for the rest of the world).

I'll post a picture later.

[M.D. Holloway]

60hz? hmmm, I bet you guys are developing the next gen GWEN and HARPP to continue to tear up the 'collective memory' of healers and human conscience history! Its all about mind control, the Nine and...

[kang]

Originally Posted by IROC

The "spallation products" are varied to say the least. We were having an issue with some weird isotope of Iodine today. Our higher beam powers are having an effect on our operations. The fun thing is that no one else in the history of man is doing what we are doing, so we are seeing things that no one has seen before. Very cool stuff.

What can come out of an atomic nucleus other than a neutron or proton (at your energies)? How do your energies (and energy density) compare to the LHC? I would think a proton would be the most likely thing to fly out, rather than a neutron, as they are struggling to fly apart anyways. I would truly like to see the battle inside of a nucleus in action, as photons (carriers of the EM force) try to push the protons apart while gluons (carriers of the strong force) fight to keep them in close proximity. We picture a nucleus like a bunch of marbles glued together, but somehow I don't think that is accurate.

[RWebb]

Just don't unwrap any important strings, Mike...

[kang]

Originally Posted by RWebb

Just don't unwrap any important strings, Mike...

Or create a black hole or fall into another dimension!

Reminds me of this site showing the web cams from the LHC.

LHC WebCam

Enjoy!

[RWebb]

that was caused by the Black Audi station wagon parked in their parking lot

[rfloz]

In the legal field there is a process known as Shepardizing whereby one can trace a case citation to all subsequent cases that cited the case (actually, the headnotes from that case) that is of interest. See Wikipedia if you would like to know more.

I am wondering if there is a similar process in the scientific field. E.g., I found the following 2009 article in ScienceDaily that challenges the once scoffed at and later accepted theory that birds evolved from theropod dinosaurs.

I would like to find any later scientific articles that mentioned this article, specifically whether they agreed with, denied or challenged it. Google and such like are not a lot of help as they tend to find thousands of irrelevant articles.

Any ideas?


Discovery Raises New Doubts About Dinosaur-Bird Links

June 9, 2009 — Researchers at Oregon State University have made a fundamental new discovery about how birds breathe and have a lung capacity that allows for flight – and the finding means it's unlikely that birds descended from any known theropod dinosaurs.

The conclusions add to other evolving evidence that may finally force many paleontologists to reconsider their long-held belief that modern birds are the direct descendants of ancient, meat-eating dinosaurs, OSU researchers say.

"It's really kind of amazing that after centuries of studying birds and flight we still didn't understand a basic aspect of bird biology," said John Ruben, an OSU professor of zoology. "This discovery probably means that birds evolved on a parallel path alongside dinosaurs, starting that process before most dinosaur species even existed."

These studies were just published in The Journal of Morphology, and were funded by the National Science Foundation.

It's been known for decades that the femur, or thigh bone in birds is largely fixed and makes birds into "knee runners," unlike virtually all other land animals, the OSU experts say. What was just discovered, however, is that it's this fixed position of bird bones and musculature that keeps their air-sac lung from collapsing when the bird inhales.

Warm-blooded birds need about 20 times more oxygen than cold-blooded reptiles, and have evolved a unique lung structure that allows for a high rate of gas exchange and high activity level. Their unusual thigh complex is what helps support the lung and prevent its collapse.

"This is fundamental to bird physiology," said Devon Quick, an OSU instructor of zoology who completed this work as part of her doctoral studies. "It's really strange that no one realized this before. The position of the thigh bone and muscles in birds is critical to their lung function, which in turn is what gives them enough lung capacity for flight."

However, every other animal that has walked on land, the scientists said, has a moveable thigh bone that is involved in their motion – including humans, elephants, dogs, lizards and – in the ancient past – dinosaurs.

The implication, the researchers said, is that birds almost certainly did not descend from theropod dinosaurs, such as tyrannosaurus or allosaurus. The findings add to a growing body of evidence in the past two decades that challenge some of the most widely-held beliefs about animal evolution.

"For one thing, birds are found earlier in the fossil record than the dinosaurs they are supposed to have descended from," Ruben said. "That's a pretty serious problem, and there are other inconsistencies with the bird-from-dinosaur theories.

"But one of the primary reasons many scientists kept pointing to birds as having descended from dinosaurs was similarities in their lungs," Ruben said. "However, theropod dinosaurs had a moving femur and therefore could not have had a lung that worked like that in birds. Their abdominal air sac, if they had one, would have collapsed. That undercuts a critical piece of supporting evidence for the dinosaur-bird link.

"A velociraptor did not just sprout feathers at some point and fly off into the sunset," Ruben said.

The newest findings, the researchers said, are more consistent with birds having evolved separately from dinosaurs and developing their own unique characteristics, including feathers, wings and a unique lung and locomotion system.

There are some similarities between birds and dinosaurs, and it is possible, they said, that birds and dinosaurs may have shared a common ancestor, such as the small, reptilian "thecodonts," which may then have evolved on separate evolutionary paths into birds, crocodiles and dinosaurs. The lung structure and physiology of crocodiles, in fact, is much more similar to dinosaurs than it is to birds.

"We aren't suggesting that dinosaurs and birds may not have had a common ancestor somewhere in the distant past," Quick said. "That's quite possible and is routinely found in evolution. It just seems pretty clear now that birds were evolving all along on their own and did not descend directly from the theropod dinosaurs, which lived many millions of years later."

OSU research on avian biology and physiology was among the first in the nation to begin calling into question the dinosaur-bird link since the 1990s. Other findings have been made since then, at OSU and other institutions, which also raise doubts. But old theories die hard, Ruben said, especially when it comes to some of the most distinctive and romanticized animal species in world history.

"Frankly, there's a lot of museum politics involved in this, a lot of careers committed to a particular point of view even if new scientific evidence raises questions," Ruben said. In some museum displays, he said, the birds-descended-from-dinosaurs evolutionary theory has been portrayed as a largely accepted fact, with an asterisk pointing out in small type that "some scientists disagree."

"Our work at OSU used to be pretty much the only asterisk they were talking about," Ruben said. "But now there are more asterisks all the time. That's part of the process of science."

Journal Reference:

1.Quick et al. Cardio-pulmonary anatomy in theropod dinosaurs: Implications from extant archosaurs. Journal of Morphology, 2009; DOI: 10.1002/jmor.10752

[IROC]

Originally Posted by kang

What can come out of an atomic nucleus other than a neutron or proton (at your energies)?

Well, I suppose only neutrons or protons, but this phenomena results in all kinds of crazy isotopes and daughter products. We also have issues with proton interaction with cooling water. Not only do we get radiolysis (H2 and O2 production), but we get weird isotopes like N-17.

How do your energies (and energy density) compare to the LHC?

I think the LHC is operating much closer to the speed of light. We're only at 90%. Our accelerator is only about 1000 feet long, so nothing like the LHC.

We pulled our target module off this morning. It was reading about 31,000 rads/hr on contact. If you were able to walk up next to it, you'd receive a lethal dose of radiation in less than a minute. If you look closely on the round "seal plate" near the bottom of the picture, you can see little globs of liquid mercury.

[BRPORSCHE]

That is seriously cool stuff. I deal with x-rays everyday in an XRF but only 'see' 60 watts. I couldn't imagine 1.4 MW of energy.

[RWebb]

rfloz - there are indeed citators for scientific articles; go to a university science library and ask the ref. librarian for help

or go to the Or St. univ web site and find the faculty member's web page to see if anything is going on re that press release from 2009

[rfloz]

Thanks.