CERN Accelerating science

The target-less configuration fluxes (solid) obtained in this work and neutrino fluxes for the target (dashed), adopted from Ref.~\cite{DUNE:2020ypp}. Here, the fluxes of $\nu_\mu$ and $\bar\nu_\mu$ in the target mode are the results obtained in the forward horn current mode and the reverse horn current mode, respectively. The red and cyan curves show the fluxes of $\nu_\mu$ and $\bar\nu_\mu$, respectively. Absolute fluxes for target and dump case are shown in the upper panel while their ratio is shown in the lower panel.

LDM sensitivity for target-less run of 3 months-0.6 MW beam (1year-1.2 MW beam) shown in solid (dashed) red curve, compared to the DUNE target configurations discussed in the literature, namely the shape analysis (blue dashed curve) of Ref.~\cite{Breitbach:2021gvv} and the PRISM analysis of Refs.~\cite{Breitbach:2021gvv,DeRomeri:2019kic} (cyan dot-dashed curve). The ``target'' symbol in the legend denotes the target mode measurements. The thermal relic density for scalar DM reproducing the observed DM abundance is shown in orange. The existing constraints from various experiments are shown in gray shaded regions. See text for more details.

The target-less configuration sensitivity to the ALP-electron and ALP-photon coupling using 3 months-0.6 MW power (1 year-1.2 MW power) shown in red solid (dashed) curves. {\emph{Top panel}:} For $g_{ae}$, Compton scattering, associated production, resonant production, and bremsstrahlung production of ALPs are considered via $\gamma$ and $e^\pm$ scattering in the dump environment. Detection channels include ALP decay to $e^+e^-$ for $m_a > 2m_e$ as well as external pair conversion and inverse Compton scattering in the detector (see text for details). Also displayed are the DFSZ model preferred regions, where DFSZ-I and DFSZ-II are sub-models differentiated by the relationship between the axion-lepton and axion-quark couplings. {\emph{Bottom panel}:} For $g_{ae}$, the production occurs via Primakoff scattering process. The detection channels involve the inverse-Primakoff scattering process and two photon final states from the decay. KSVZ model preferred regions are shown as well. The blue dashed curve is the 1 year target result using the gas detector in Ref.~\cite{Brdar:2020dpr}. The ``target'' symbol in the legend denotes this target mode measurement.