Speaker
Mr
Pitam Mitra
(University of Alberta)
Description
An unknown source of bubble nucleation is impacting the sensitivity of the bubble chambers of the PICO dark matter search. After the end of the current PICO runs assays have shown contamination with particulates. The present hypothesis is that these residual particulates which are small enough in size to remain suspended in the liquid are a dominant contributor of this nucleation. We have developed methods to test this hypothesis and to investigate the source of the particulate matter in the chambers.
A procedure for the collection of samples from both of the PICO chambers (2L and 60L) was developed to extract particulates on a PTFE filter. The filter was then examined under optical and electron microscopes. A method to estimate the mass of each kind of particulate seen in the filters (steel oxide, silica) was then developed using electron micrographs, x-ray spectroscopy and image analysis. This presentation reports on procedures developed and the studies performed to estimate the mass and to identify the types of materials in the samples and discusses the possible sources of the contaminants.
Primary author
Mr
Pitam Mitra
(University of Alberta)
