  CaloFlow is a new and promising approach to fast calorimeter simulation based
on normalizing flows. Applying CaloFlow to the photon and charged pion Geant4
showers of Dataset 1 of the Fast Calorimeter Simulation Challenge 2022, we show
how it can produce high-fidelity samples with a sampling time that is several
orders of magnitude faster than Geant4. We demonstrate the fidelity of the
samples using calorimeter shower images, histograms of high-level features, and
aggregate metrics such as a classifier trained to distinguish CaloFlow from
Geant4 samples.
