Amorphous carbon-coated storage cell tests for the polarized gas target at LHCb

The LHC beams cannot be polarized. Hence, the implementation of a dense polarized gas target at the LHCb experiment at CERN, to be operated simultaneously with beam–beam collisions, will enable high-energy fixed target interactions to explore a range of spin physics measurements. Using an atomic beam source at the Forschungszentrum Jülich to provide a polarized atomic hydrogen beam, we investigated the properties of a storage cell coated with amorphous carbon. A notable recombination rate, lying between 93 and 100%, and a preservation of polarization during recombination exceeding 74% was observed. We were able to generate H2 molecules with a nuclear polarization of −0.59. Remarkably, no water layer accumulated on the cooled storage cell surface, even over extended periods. Furthermore, we examined the influence of Lyman-α radiation on the recombination rate on carbon, addressing a prominent question in the field of astrophysics.