Week of February 26th

I dove into my dark matter research today, and started looking up all of the various dark matter experiments. For each experiment, I read all the major papers it had published, as well as general news articles. It was really challenging to get through the publications, because there was so much technical jargon as well as concepts that I haven't encountered yet. By focusing on the titles of the papers and the abstracts, I was able to get a general understanding of what the paper was about. I also learned a lot just by looking at the graphs and tables each paper included, since I tend to understand concepts better when I see visual representations of them.

There are six major dark matter experiments going on right now: The LUX (Large Underground Xenon) experiment in South Dakota, the Xenon10 and Xenon100 experiments at Columbia, the Dama/Libra experiment in Italy, the CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) experiment, and SuperCDMS (cryogenic dark matter search) in California. 

Today, I researched the LUX experiment and the Xenon10 and Xenon100 experiments, since they both use liquid xenon in their detectors. I put together a page-long summary for each experiment for Dr. Bellis, but I will just briefly recap what I learned here.

LUX experiment:

Detector: LUX is trying to directly detect dark matter (specifically WIMP particles, which most scientists believe constitute dark matter) with a liquid xenon time-projection chamber. A time-projection chamber is a type of particle detector that places electric and magnetic fields parallel to each other in the detector, which means that electrons travel in a straight line (instead of a curved path, which would occur if the electric and magnetic fields were perpendicular to each other). This allows scientists to create a three-dimensional picture of collisions in the detector, and determine the energy and momentum of particles. Xenon is used because it's very pure and because it fluoresces when struck by a charged particle. From the official LUX experiment page:

"Interactions inside the xenon will create an amount of light proportional to the amount of energy deposited. That light can be collected on arrays of light detectors sensitive to a single photon, lending the LUX detector a low enough energy threshold to stand a good chance of detecting the tiny bump of a dark matter particle with an atom of xenon."

Results: In February 2014, scientists at LUX concluded that from the first 90 days of data, there was no statistically significant evidence of WIMPS. This is surprising since it's considered to be the most sensitive detector to date, and other less sensitive detectors have found hints of the particles.

Xenon100:

The Xenon100 detector is very similar to the LUX detector. It's a time-projection chamber and it uses liquid xenon. The setup of all the dark matters are similar, but the difference is in the constraints set on the WIMP interactions (basically, where the scientists are looking for the dark matter interactions to happen). 

Results: The Xenon100 experiment found no evidence for dark matter interactions.