Quincy and I are over half way through with our European adventure. I can’t believe how quickly time has gone by. Centered in Mainz, Quincy and I are working with the IceCube group at the Johannes Gutenberg University.
My project focuses on the hardware aspects for a future part of the IceCube detector called PINGU. Searching for low energy atmospheric neutrinos, PINGU aims to determine the neutrino mass hierarchy. To design the new part of the detector, new optical modules to detect light, called Wavelength-Shifter Optical Modules (WOMs) are being studied. Unfortunately. The WOMS have an increase in noise at cooler temperatures. One hypothesis is that there is a decay of potassium in the glass creating photons, which creates a the signal noise. At colder temperatures, there are fewer vibrations in the WOM, making the photon more likely to successfully create a signal to be detected by the photomultiplier of the WOM.
Initially, I built a circuit with temperature probes to verify the temperature of the environment I am running my tests in. Now, I am attempting excite the glass of the WOMs using ultraviolet light to observe whether or not there is more light at colder temperatures.
The Precision IceCube Next Generation Upgrade (PINGU) is designed primarily to detect low energy neutrinos on the order of about 1 GeV. Neutrinos at low energies are useful for resolving the Neutrino Mass Hierarchy (NMH), a prediction about mass differences between neutrino flavors. There are three neutrino flavors, and three mass states associated with these flavors. We know the difference in mass between two of the three neutrino mass states, but it’s unclear if the third mass states belongs below or above the two known mass states. We refer to these two mass state possibilities as normal NMH and inverted NMH.
I am working on producing cosmic ray flux simulations on the order of about 1 GeV. Neutrino flux on Earth appears to be isotropic on average, and this enables us to predict expected electron, muon and tau neutrino event rates at the IceCube detector. The first step is to generate a expected event rate, based on theory, as a function of cosine zenith angle and energy. Next, this theoretical event rate must be smeared to account for uncertainties in the detector hardware. I’m working on this smearing phase of the reconstruction.
We will produce two sets of simulated data which represent normal NMH and inverted NMH. When the PINGU detector hardware is installed and data are collected, we can compare the experimental results with these simulations. Over the course about 5 years of PINGU operation, we will be able to make a claim about the relative differences in neutrino mass states. We expect the experimental observation to align with either the normal NMH simulation or the inverted NMH simulation. This result will allow us to know the mass of each neutrino flavor, resolving one of the few remaining unknowns about relative particle mass in the standard model.
The past weekend we spent exploring Munich. Attempting to escape the heat (the hottest weekend recorded in German history!) we spent our days jumping into a river running through the English Gardens, enjoying the Bavarian culture (think lederhosen…) and exploring the many museums Munich has to offer. We brought another summer student from America with us and met up with my friend from the University of Wisconsin-Madison, too. After a weekend well spent, we returned home for more fun in the lab!
Maggie and Quincy
Editor’s note: Maggie Beheler-Amass is an undergraduate at the University of Wisconson-Madison. Quincy Wofford III is an undergraduate at the University of Kansas. They are Mainz, Germany undertaking IceCube research under and NSF, IRES program at the University of Wisconsin-River Falls.