A complete simulation of the X-ARAPUCA device for detection of scintillation photons

Abstract

A: The concept of the ARAPUCA device is relatively new and involves increasing the effective area for photon collection of SiPMs by the use of a box with highly reflective internal walls, wavelength shifters, and a dichroic filter to allow the light to enter the box and not the leave it. There were a number of tests showing the good performance of this device. Recently an improvement on the original design was proposed: the inclusion of a WLS bar inside the box to guide photons more efficiently to the SiPMs. We present a full simulation of the device using Geant4. We have included all the material properties that are available in the literature and the relevant detailed properties for adequate photon propagation available in the framework. Main results include estimates of detection efficiency as a function of the number, shape, and placing of SiPMs, width of the WLS bar, its possible attenuation, and the existence of a gap between the bar and the SiPMs. Improvement on the efficiency with respect to the original ARAPUCA design is 15-40%. The ARAPUCA simulation has been validated in a number of experimental setups and is a useful tool to help making design choices for future experiments devices. K: Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc); Noble liquid detectors (

Liquid argon characterization of the X-ARAPUCA with alpha particles, gamma rays and cosmic muons

“…The size of the gap between the SiPM and the bar was also included with a 0.5 mm value. Changing the size of the gap should not be of great impact on the efficiency estimation as long as it is not zero, at least within the considerations made in this simulation [33].…”

“…Therefore, the simulation efficiency estimate for the device is expected to be higher than the values obtained from the experimental setup. The simulation shows that an increase in efficiency compared to the standard ARAPUCA, that does not include the WLS bar and instead deposits TPB on the dichroic filter facing the inside of the box, is of order of 15-40% [33].…”

Enhancement of the DUNE FD1 X-ARAPUCA Photon Detection Efficiency and upgrade of the FD2 Photon Collector

“…The results from the two independent setups and methods are very much aligned and consistent within the errors. The assessed values are in average significantly lower than those reported by previous tests on smaller XA devices [16,21] with different components configurations, and of the expected values [22]. (Bottom) Two spectra collected with the source at the center (blue; 2.7 Sr irradiation solid angle) and at the bottom end (red; 2.3 Sr) of the XA device, calibrated in number of detected photoelectrons as described in [16].…”

Liquid argon characterization of the X-ARAPUCA with alpha particles, gamma rays and cosmic muons

“…The size of the gap between the SiPM and the bar was also included with a 0.5 mm value. Changing the size of the gap should not be of great impact on the efficiency estimation as long as it is not zero, at least within the considerations made in this simulation [31].…”

“…Therefore, the simulation efficiency estimate for the device is expected to be higher than the values obtained from the experimental setup. The simulation shows that an increase in efficiency compared to the standard ARAPUCA, that does not include the WLS bar and instead deposits TPB on the dichroic filter facing the inside of the box, is of order of 15-40% [31].…”