Paramount Poster

4/26/13

The day flew by today in the lab. All four of the capsules had been taken out of the furnace from last week and I quickly jumped to work cleaning them out. After breaking the capsules open and trying not to breathe in too many of the less than pleasant sulfur fumes, I scraped the sulfur-34 from the glass and extracted the four crystals. I then let them soak in 4 different beakers of ethanol and put them in the ultrasonic. The ultrasonic however had too much water in it, and with the vibrations of the ultrasonic, my four little beakers almost started floating away. After dumping out a little of the water, my beakers were now comfortably resting on the bottom and I was able to turn on the ultrasonic without fear of my beakers tipping over, losing the recycled sulfur-34 in the process.

After I was done with the crystals Heather was nice enough to suggest that we could work on my poster. We downloaded everything on the lab computer and began looking at graphs. I found the linear fit using excel of a sphalerite crystal that had been scanned by the ion beam in a process called Rutherford backscattering spectrometry or RBS. This is where a burst of Helium ions are shot at the sample and a detector analyzes the backscattered electrons. Daniele then showed me a detector she would use. It was a shiny gold colored cylinder with a smaller mirror-like cylinder at its core. Daniele told me the outside was usually made of gold or platinum to help contain the particles. The mirror-like cylinder was made of silicon. The very top layer of the cylinder was doped silicon that was silicon and a lot of other elements about the width of a hair thick. The rest of the cylinder was simply pure silicon. It is the silicon that does the analyzing and measures the electron pairs that exit the sample. Using this RBS graph, I used the linear fit to calculate the activation energy of this sphalerite sample. Heather showed me the formula:
D = D₀ exp (–Q/RT)
where D is the diffusivity
D₀ is a constant
Q is the activation energy
R is the gas constant
and T is the temperature in Kelvins
After taking the natural log of both sides and doing other math, I found the activation energy to be 131 which Daniele said was a reasonable number. I had finally gotten a number from my data!

Next week, Daniele and Heather are taking me to see the ion beam at SUNY Albany. I am super excited to see the facility and finally see the behind-the-scenes analyzing that happens after I extract my crystals. It should be lots of fun even though I sadly only have one week left after the ion beam before my internship draws to a close.