CERN Accelerating science

Gallery of four representative cosmic ray-induced events collected with \mbox{Module-0}, as recorded in the raw event data, with collected charge converted to units of thousands of electrons. In all cases, the central plane in grey denotes the cathode, and the color scale denotes the collected charge. (a) shows a stopping muon and the subsequent Michel electron decay, (b) denotes an electromagnetic (EM) shower, (c) is a multi-prong shower, and (d) is ``neutrino-like'' in that the vertex of this interaction appears to be inside the active volume.

Schematic of the $0.7~\mathrm{m}\times0.7~\mathrm{m}\times1.4~\mathrm{m}$ Module-0 detector with annotations of the key components.

Photograph of the Module-0 detector interior as seen from the bottom, with annotations of the key components.

Front (left) and back (right) of a TPC anode tile. The front contains 4,900 charge-sensitive pixels with 4.43~mm pitch that face the cathode, and the back contains a $10\times10$ array of LArPix ASICs. The dimensions are $31~\mathrm{cm}\times 32~\mathrm{cm}$, with the extra centimeter providing space for the light system attachment points.

Front (left) and back (right) of a TPC anode tile. The front contains 4,900 charge-sensitive pixels with 4.43~mm pitch that face the cathode, and the back contains a $10\times10$ array of LArPix ASICs. The dimensions are $31~\mathrm{cm}\times 32~\mathrm{cm}$, with the extra centimeter providing space for the light system attachment points.

The Pixel Array Controller and Network card (PACMAN), which controls the data acquisition and power for the charge readout system.

Run event rate and cumulative events as a function of time with respect to charge readout operating condition.

Detection principle of the two types of modules comprising the LRS: a segment of an ArCLight tile (top) and a single LCM optical fiber (bottom). The wave-like lines indicate example photon trajectories, where the white points indicate interactions. Drawings are not to scale.

An ArCLight tile (left) and three LCM tiles (right), as assembled within the Module-0 structure.

LRS data acquisition components: JINR ADC board (left), synchronization and trigger scheme (right).

LRS data acquisition components: JINR ADC board (left), synchronization and trigger scheme (right).

Self-trigger active pixel channels (in blue) and inactive channels (in black). In these coordinates, $x$ is horizontal and $y$ is vertical, both parallel to the anode plane, and $z$ is the drift direction, perpendicular to the anode plane, completing a right-handed system. The origin is the center of the module.

Most probable value (black circles) and full width at half maximum (white circles) of the $dQ/dx$ distribution for each data run. The system shows a good charge readout stability during data taking periods, both for {high threshold} (yellow bands) and {low threshold} (purple bands) runs.

LArPix channel noise in units of electron charge signal, as observed using periodic forced triggers. The total system noise is $\sim950~\mathrm{e}^-$, compared to a signal amplitude of $\sim1800~\mathrm{e}^-$ for a 4 GeV MIP track in ND-LAr's 3.7 mm pixel pitch.

Self-trigger charge distribution for MIP tracks measured in thousands of electrons (ke$^-$); 50\% of the rising edge are shown as indicators of the charge readout self-trigger thresholds. The low- and high-threshold curves are obtained from runs with the same 20 minute exposure. Each entry is normalized by hit charge over fitted track length. The MC simulation shown in comparison is described in Section~\ref{sec:cosmic-analysis}.

Total event charge per channel for MIP tracks measured in thousands of electrons (ke$^-$). The MC simulation shown in comparison is described in Section~\ref{sec:cosmic-analysis}.

Comparisons of response variation in the radial distance from the pixel center to the point of closest approach of the track projected onto the anode plane ($r$, top), the track inclination relative to the anode plane (polar angle $\theta$, middle), and the orientation angle of the track projected onto the anode plane (azimuthal angle $\phi$, bottom). The MC shown in comparison is described in Section~\ref{sec:cosmic-analysis}.

Comparisons of response variation in the radial distance from the pixel center to the point of closest approach of the track projected onto the anode plane ($r$, top), the track inclination relative to the anode plane (polar angle $\theta$, middle), and the orientation angle of the track projected onto the anode plane (azimuthal angle $\phi$, bottom). The MC shown in comparison is described in Section~\ref{sec:cosmic-analysis}.

Comparisons of response variation in the radial distance from the pixel center to the point of closest approach of the track projected onto the anode plane ($r$, top), the track inclination relative to the anode plane (polar angle $\theta$, middle), and the orientation angle of the track projected onto the anode plane (azimuthal angle $\phi$, bottom). The MC shown in comparison is described in Section~\ref{sec:cosmic-analysis}.

Relative rate of pixel response as a function of the distance between Hough line segments and segment containing pixel's center for pixels on gaps, i.e. no charge response (left), and on tracks, i.e. with charge response (right) to the total.

Relative rate of pixel response as a function of the distance between Hough line segments and segment containing pixel's center for pixels on gaps, i.e. no charge response (left), and on tracks, i.e. with charge response (right) to the total.

Self-trigger charge distribution for MIP tracks with different track orientations with respect to the pixel, normalized to number of triggered channels per reconstructed track length. Low-threshold data are used. The MC simulation shown in comparison in the second column is described in Section~\ref{sec:cosmic-analysis}.

Self-trigger charge distribution for MIP tracks with different track orientations with respect to the pixel, normalized to number of triggered channels per reconstructed track length. Low-threshold data are used. The MC simulation shown in comparison in the second column is described in Section~\ref{sec:cosmic-analysis}.

Self-trigger charge distribution for MIP tracks with different track orientations with respect to the pixel, normalized to number of triggered channels per reconstructed track length. Low-threshold data are used. The MC simulation shown in comparison in the second column is described in Section~\ref{sec:cosmic-analysis}.

Same as Fig.~\ref{fig:larpix-pixel-q-dist-lt} but for high threshold data.

Same as Fig.~\ref{fig:larpix-pixel-q-dist-lt} but for high threshold data.

Same as Fig.~\ref{fig:larpix-pixel-q-dist-lt} but for high threshold data.

MIP response maps for anode plane 1 (left) and anode plane 2 (right), showing the fraction of triggered hits on each pixel relative to the expected number based on reconstructed track trajectories.

MIP response maps for anode plane 1 (left) and anode plane 2 (right), showing the fraction of triggered hits on each pixel relative to the expected number based on reconstructed track trajectories.

Per-pixel ADC value distribution for cosmic ray events between 2 and 10 GeV. All signals are well within the ADC dynamic range of 0--256 counts.

$dQ/dx$ measured for segments of different lengths as a function of the orientation relative to the anode planes. A value of $\cos\theta = 0$ corresponds to segments parallel to the anode plane. The distributions in each bin have been fitted with a Gaussian-convolved Moyal function. The red points correspond to the most probable value of the fitted distribution and the dashed rectangles correspond to the full width at half maximum. The dashed black line represents the average MPV.

$dQ/dx$ measured for segments of different lengths as a function of the azimuthal angle $\phi=\mathrm{atan2}(y,x)$, where $y$ and $x$ are the components of the segment along the anode plane axes. The distributions in each bin are fitted with a Gaussian-convolved Moyal function. The red points correspond to the most probable value of the fitted distribution and the dashed rectangles correspond to the FWHM. The dashed black line represents the average MPV.

Typical charge spectrum obtained during SiPM gain calibration (left); SiPM gain distribution (right).

Typical charge spectrum obtained during SiPM gain calibration (left); SiPM gain distribution (right).

Oversampled signal using Fourier transformation. Red lines show the linear approximations of the rising edge and the baseline (left). The time resolution between two LCMs (LCM-011, LCM-017) as a function of the signal response (right).

Oversampled signal using Fourier transformation. Red lines show the linear approximations of the rising edge and the baseline (left). The time resolution between two LCMs (LCM-011, LCM-017) as a function of the signal response (right).

Two examples showing signals of the stopping muon and delayed Michel electron detected by the LCM. The waveforms were digitized at 10~ns intervals.

Two examples showing signals of the stopping muon and delayed Michel electron detected by the LCM. The waveforms were digitized at 10~ns intervals.

Absolute PDE for each ArCLight (left) and LCM (right) tile (arbitrary numbering). ArCLight tile 7 was disabled during Module-0 data taking. The LCM tiles are placed in sets of 3 to cover the same area as one ArCLight tile.

Absolute PDE for each ArCLight (left) and LCM (right) tile (arbitrary numbering). ArCLight tile 7 was disabled during Module-0 data taking. The LCM tiles are placed in sets of 3 to cover the same area as one ArCLight tile.