Today is June 27, which means I have been doing research here at Deutsches Elektronen-Synchrotron (DESY) for three weeks. In general, my project involves studying the resolution and efficiency of silicon detectors irradiated by 23 MeV protons as a part of the reconstructing of the CMS detectors located at CERN, which is where the second part of my project will take place.
For the first week, i measured current and capacitance of the sensors up to 1000 Volts in order to obtain the macroscopic detector parameters, depletion voltage and reverse current at depletion voltage. The sensors are so irradiated that the depletion voltage is actually greater than 1000 V. I planned to perform annealing steps, which simply means heating up the sensors step by step and taking measurements at each step, but it does not look like I will have enough time given only one more week here in Hamburg. The current and capacitance measurements went fairly quickly, it has been the Transient Current Technique (TCT) method that has been the most time consuming.
TCT is an important tool to study signal formation, charge collection and trapping mechanisms in the detectors. I want to perform TCT measurements on each of my six sensors with the red light from the front and rear, and with the infrared light. Between each measurement i must take a reference measurement, and compare with a sensor of the same type that is not radiated. This is what takes so long. But i cannot complain because in our lab at Brown, we will be getting the TCT setup pretty soon, and i will be able to teach those in the lab how to use it, and possibly help make the program to analyze the data from it.
Here at DESY, i have had the chance to talk with scientists working on different things. So, they accelerate particles in circular motion and from that photons are released which are used by the biomedical group and the chemistry group for medical research. The physics group I am working with does not use the photons, just tests sensors in the highly irradiated environments.
Being at a German institution has been an indiscribable experience. I can remember being in high school and only learning about Germany when it came to WWII, and I never saw a reason why I would ever come to Germany. Upon choosing to come here and work with the accelerator, I admit I was concerned about the racial aspects of it, and I was warned by professors at Brown to be cautious and aware. I am happy to say, it is nothing like I expected. From my experience, being Black in the US is much more complicated.
My German friend and I visited a concentration camp yesterday, and that was very emotional. I always thought it would be saddening and cause me to build up resentment, but instead I have found a sudden urge to understand myself as a part of a community, not just the United States, not even just black America, but apart of the world as a person. And as I speak with people about religious beliefs, experiences in physics, and understandings of race, I am learning so much about myself and how I see the world. Most importantly how small i am in the world.
One more week of studying the accelerators and sensors here in Hamburg, Germany, and then I am off to Geneva, Switzerland.