Research Overview

The RPI XENON group is involved in both the XENON100 and XENON1T dark matter experiments, and the nEXO neutrinoless double beta decay experiment.

Data Analysis

Dark Matter Data

While the XENON100 detector has already reached its main scientific goal by releasing its results on the spin independent WIMP nucleon cross section in 2012, many other analyses can be performed with the data, for example to probe the validity of different dark matter models. In addition, more data is still being taken, as the detector has not yet been decommissioned and analysis of this new data is always ongoing.

As XENON1T prepares to start its science run, data analysis is already underway to understand the detector and analysis chain. RPI is contributing to this work and will be involved with the subsequent scientific studies coming from this new data.

R&D Data for XENON1T

In addition, the XENON100 detector is used for R&D for XENON1T. Different techniques, from calibration to impurity removal, are being tested in XENON100 to see if they will be valid in XENON1T. Analysis of 83mKr calibration data in XENON100 is underway, developing the calibration tools for use in XENON1T as soon as the data is available.

Simulations

Work toward designing and building nEXO requires detailed Monte Carlo studies of various detector properties, such as backgrounds, detection efficiency and optimization for the experimental sensitivity.

R&D for XENON1T and nEXO

Purity Monitoring

In order for the XENON1T detector to operate properly, electronegative impurities like water and oxygen must be removed from the xenon to extremely pure levels. Because the experiment is going to run constantly over a period of years, it is necessary to ensure that the xenon stays pure with time. Consequently, there is a need to be able to monitor the purity at all times. Indeed, even the smallest leak can spoil the high purity conditions needed to look for dark matter. RPI is taking the leading role in addressing this issue by designing and building new purity monitors which, once built, tested and characterized, will be mounted at different key points on the XENON1T purification system.

Magnetic Piston Pump

One issue that both XENON1T and nEXO face is the need to recirculate large quantities of xenon through a heated getter to remove electronegative impurities. To achieve this, a recirculation pump is needed to constantly pump the xenon in and out of the detector and run it through the purification system. These pumps need to be extremely pure themselves so as to not introduce radioimpurities in the xenon, and in addition they need to be made in order to last for years without wearing or needing extensive or frequent maintenance. A new large capacity pump based on one developed and used on EXO200 is being built and characterized at RPI in collaboration with nEXO colleagues at Stanford and XENON colleauges at Muenster University. Research at RPI focuses on creating a high performance, low maintenance drive system for this prototype pump for use on XENON1T and nEXO.

Thin Films

My research uses thin films in novel ways to build better, cleaner detector components. Novel resistors and VUV antireflective coatings based on thin film depositions are produced in cleanroom facilities at RPI. Characterization of these films includes ellipsometry, AFM, and 4 point probe resistivity at low temperature for use in liquid xenon detectors. Here my students collaborate with collegues in condensed matter and material science.