Monday, January 26, 2015

Why did Fat Man have dark paint markings?

You asked a terrific question about the black paint on Fat Man's protruding parts. Fat Man was delivered to Tinian Island in parts and assembled on the island. The implosion design had been tested in New Mexico, but had never been exposed to the kind of humidity it experienced in the Pacific. After assembly, but before loading it onto the bomber Bock's Car,  all of Fat man's seams were sprayed with a sealer. I think it was asphaltum or something similar. Many of the protruding parts were bolted on, so their seams were included in the treatment.

Was Flouride a by-product of the Manhattan Project?

 I love this question which I found this morning in our question box. So much in fact that I just had to share it with a Lab chemist I know. (Because I had no idea.) I have copied his response in full here. I recommend both of the links. Thank you for providing me with this opportunity to learn!

"I’m guessing that they are referring to the de-conversion of uranium hexafluoride to form uranium metal.  A byproduct of the de-conversion process would be fluorine – typically as a fluoride.

Here is a NRC web page providing some information on uranium de-conversion:

Also web page for the company that is building a facility in southern New Mexico for uranium de-conversion:

For example the above facility apparently plans to produce the SiF4 (silicon hexafluoride) as the byproduct instead of a fluoride salt.  As mentioned SiF4 is typically used to make high purity silicon for electronic applications.

With regard to Manhattan Project I’m not sure where the de-conversion process took place and what form, e.g. fluoride salt, they produced at the time."

Are the Little Boy and Fat Man models at the BSM full scale?

Our replicas are full scale. Actually around 2005 ago we replaced our original models with two even better replicas that are more accurate in representing the appearances of the two weapons.  The two new versions, constructed of steel and fiber glass are actually ballasted with concrete to represent the actual weights of the original weapons. Not that we ever heft them.

Thursday, May 1, 2014

How can we fix the ozone layer?

You asked a very interesting question about ozone and how can we fix the ozone layer.

It is true that lightning creates ozone. Any spark in air will do it. Ozone can also be created by certain forms of radiation. Ozone is a molecule of oxygen that consists of three atoms instead of the usual two. It has peculiar chemical properties, it is highly reactive, and at ground level it can be toxic to people and contribute to health hazards like smog.

Unfortunately, the ozone created by lightning is all in Earth's troposphere, below about 50,000 feet, the part of our atmosphere where weather happens and life flourishes. Fortunately, although thunderstorms are constantly happening all across Earth's surface, they don't create enough ozone to be much of a problem.

The ozone layer that protects organisms on the surface from ultraviolet radiation is in the stratosphere, above 50,000 feet. Here there is good and bad news, too. Ozone is created when oxygen absorbs the energy of ultraviolet light. So UV light makes ozone, and ozone absorbs even more UV light. Nature itself can take care of us, if we don't mess it up too much. That is the bad news. Some chemicals we have added to the atmosphere over many years react with ozone and break up the molecules. We have stopped using many of the nastiest ozone depleters but they break down very slowly and continue to destroy ozone. Eventually, we hope, these chemicals will wear out, and the stratosphere will be back to the way it once was, more or less. Human activity still continues, and we have to make intelligent decisions about risks.

While I was researching my answer, I found two interesting websites. has basic information about the ozone layer, and has an up-to-date ozone weather map.

Monday, September 9, 2013

Human battery exhibit

The exhibit you describe has four large metal plates, one each copper and aluminum on each side of a meter. The copper plate on the left is connected through the meter to the aluminum plate on the right and the other two plates are connected in the reverse direction. The meter measures micro amperes, or millionths of an amp of current, so it is very sensitive.

Placing one's hands on plates connected across the meter causes the needle to deflect. This is because we, the human, are acting as the electrolyte in a battery. The two metals have different affections for their electrons, and the one that is greedier steals electrons from the one more generous through our bodies. This causes an imbalance between the two plates which is corrected by the current through the meter.

A typical visitor gets a modest reading on the meter. Sometimes a person is able to easily pin the meter at one end of its range. There might be a number of reasons for this. Larger hands and greater pressure produce more current. Moister hands work better than dry hands. I don't know if this is a real affect, but I have an impression that it is common for women to get higher readings than men. I can't imagine an explanation for this, and I am pretty good at making stuff up. I doubt it is because the average man has a greater wingspan than the average woman, but I really don't know. There is also probably a day-to-day variation with an individual depending on personal chemistry, hydration, sweaty palms, etc. I have never studied that, either.

Some of my favorite questions are those I can answer, "I don't know."

How many babies were born in Post Office Box 1663?

This question sent us asking Alan, the Lab Historian, for help:

I received the following reply this afternoon from our historian. I am astounded! The 80 in the first year would mostly have been conceived off 'the hill.' The Manhattan Project arrived here in March. Many of the rest would have been the result of local efforts.

Quoth Alan:
"I haven’t been able to find an exact number, but you might find this quote from Jon Hunner’s, Inventing Los Alamos, helpful:

 'Eighty babies were born the first year, and ten newborns arrived every month thereafter' (p. 39)

 That’s essentially a shade under 300 babies born in Box 1663 during the war."

Stripes in video of atmospheric atomic bomb tests

We have been asked several times what are the vertical stripes in videos of atmospheric atomic bomb tests.

I wondered about this for a long time when I first came to the museum. The streamers you see in film of atmospheric nuclear weapons tests were smoke trails made by sounding rockets fired just before the detonation. They were used to make a sort of graph paper in the air for recording the propagation of shock waves and wind currents from the explosion.

A current project under way at Los Alamos uses something like confetti, numerous high definition video cameras, and super computers to try to build a three dimensional model of the turbulence downstream from a wind turbine tower. They are using the multiple points-of-view and the computers to track each individual speck of paper. I think the paper is dispersed upwind of the tower using a sounding rocket and a conventional firework explosive. Some technologies are just too much fun to leave on the shelf.