Paper short abstract:

Laboratory experiments depend on being clean. But what is clean? In this talk, I open up the value of 'clean' and practices of cleaning in an experiment aimed to detect signs of a hypothetical dark matter particle.

Paper long abstract:

Laboratory sciences crucially depend on experiments being clean. But what is clean? This talk contributes to the study of valuing in the sciences by opening up the good of ‘clean’ in a physics experiment. My case is the XENONnT experiment in the Gran Sasso Mountains of Italy which is meant to detect dark matter in the form of the hypothetical WIMP – the Weakly Interacting Massive Particle. This experiment is clean when it is ‘free from signals that mimic dark matter’. In practice, such cleanliness has been difficult to achieve – soaps may be radioactive, steel may spread electronegativity, and humans are altogether dangerously filthy. And because, at least thus far, dark matter remains elusive, it is impossible to tell whether the meticulously cleaned detector is adequately clean. Additional cleaning efforts will make the detector sensitive to neutrino particles: a background that cannot be cleaned away. As the experimenters dread the possibility that this means their experiment will end in limbo, other physicists are now trying to detect other hypothetical dark matter particles with other kinds of experiments, requiring other kinds of cleanliness. Meanwhile, the attempts to achieve detector specific cleanliness requires resources and generates discards that all too easily go unnoticed. In response to this, I contend that such externalities, that is the ‘external bads’ generated by experimental sciences, urgently deserve attention.