Ankur Week 1 Post 2

By the Friday this week we were able to begin some assembly of the copper plumbing. Here I will explain in detail what we are doing in lab. There are two projects we are working on:

1. Previously, Geoffrey trapped Argon gas in a charcoal trap. Charcoal has a strong affinity for Argon when it is cooled to cryogenic temperatures; about 77 degrees C. This is a useful method for filtering Argon gas from air and other such gases because the Charcoal will trap Argon within itself and allow the majority of the other gases pass through. In order to analyse and store this gas we have to now remove the argon from the charcoal. 
2. Geoffrey received a shipment of underground gas from a well in Colorado, which should theoretically have a high Argon-40: Argon-39 ratio. These underground gases are derived form the mantle but as an aside, it is curious to figure out where they originate from. Previously it was believed that it was Solar Nebula gases trapped on in the early years of Earth's creation. However, new findings suggest otherwise. Because the Argon-39 abundance is so minimal, we use different ratios of Argon isotopes to predict where a) the gas originates from, and b) whether it might be suitable for the detector. Many inert gases such as helium, neon, and krypton have similar patterns in isotopic ratios between underground gas and the atmospheric gas. We are sending off a sample of the underground gas to Harvard Graduates who have a mass spectrometer which is sensitive enough to measure Helium-4: Helium-3 ratios, letting us know where exactly the gas was derived from: the mantle or crust, and if from the mantle, than how did it reach the mantle originally?

For the first project, it is necessary to know a basic property of charcoal. When charcoal's ability to absorb Argon has an inverse relationship with temperature. So in order to release the argon from the charcoal, we had to heat the  1L steel cylinder with heating straps. The heating straps were wrapped around the cylinder and then using a transformer we were able to effectively manipulate the temperature of the charcoal inside the cylinder. In order to monitor just how much Argon gas was being removed from the charcoal we attached a pressure gauge that allowed us to monitor just how much Argon gas we had accumulated. The tricky part was  getting the Argon out of the cylinder and into an empty storage bottle so we could use the charcoal trap for future. In order to do this we had to rely strictly on physics and common sense. If we heated the charcoal trap far enough, we would get a high pressure in the charcoal trap and if the storage bottle was evacuated, we would expect a flow from the charcoal trap to the storage bottle. So first we heated the charcoal trap. Then we vacuumed all the tubing because we didn't want air contamination in the argon. Finally we leak checked the tubing. Once the charcoal trap was a little over 400 psi, we allowed opened the valve that connected the two bottles and allowed as much argon to diffuse from the charcoal trap to the storage bottle until equal pressure through the whole system was achieved.  Of course some argon was left over in the charcoal trap, but we got the majority of it out. Next week we will begin project 2.