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Astrophysics, Instrumentation and Methods for Astrophysics, astro-ph.IM
Abstract:
We present an in depth analysis of the transient events, or glitches,
detected at a rate of about one per day in the differential acceleration data
of LISA Pathfinder. We show that these glitches fall in two rather distinct
categories: fast transients in the interferometric motion readout on one side,
and true force transient events on the other. The former are fast and rare in
ordinary conditions. The second may last from seconds to hours and constitute
the majority of the glitches. We present an analysis of the physical and
statistical properties of both categories, including a cross-analysis with
other time series like magnetic fields, temperature, and other dynamical
variables. Based on these analyses we discuss the possible sources of the force
glitches and identify the most likely, among which the outgassing environment
surrounding the test-masses stands out. We discuss the impact of these findings
on the LISA design and operation, and some risk mitigation measures, including
experimental studies that may be conducted on the ground, aimed at clarifying
some of the questions left open by our analysis.
