The Wavelength-shifting Optical Module

The Wavelength-shifting Optical Module (WOM) is a novel photosensor concept for the instrumentation of large detector volumes with single-photon sensitivity. The key objective is to improve the signal-to-noise ratio which is achieved by decoupling the photosensitive area of a sensor from the cathode...

Full description

Saved in:
Bibliographic Details
Published in:arXiv.org 2022-02
Main Authors: Bastian-Querner, Benjamin, Binn, Lucas S, Böser, Sebastian, Brostean-Kaiser, Jannes, Hebecker, Dustin, Helbing, Klaus, Karg, Timo, Köpke, Lutz, Kowalski, Marek, Peiffer, Peter, Pollmann, Anna, Rack-Helleis, John, Rongen, Martin, Schlickmann, Lea, Thomas, Florian, Vocke, Anna
Format: Article
Language:English
Subjects:
Decoupling
Modules
Optical properties
Photomultiplier tubes
Photons
Photosensitivity
Signal to noise ratio
Transit time
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The Wavelength-shifting Optical Module (WOM) is a novel photosensor concept for the instrumentation of large detector volumes with single-photon sensitivity. The key objective is to improve the signal-to-noise ratio which is achieved by decoupling the photosensitive area of a sensor from the cathode area of its photomultiplier tube (PMT). The WOM consists of a transparent tube with two PMTs attached to its ends. The tube is coated with wavelength-shifting paint absorbing ultra-violet photons with nearly \(100\,\%\) efficiency. Depending on the environment, e.g. air (ice), up to \(73\,\%\) \((41\,\%)\) of the subsequently emitted optical photons can be captured by total internal reflection and propagate towards the PMTs where they are recorded. The optical properties of the paint, the geometry of the tube and the coupling of the tube to the PMTs have been optimized for maximal sensitivity based on theoretical derivations and experimental evaluations. Prototypes were built to demonstrate the technique and to develop a reproducible construction process. Important measurable characteristics of the WOM are the wavelength dependent effective area, the transit time spread of detected photons and the signal-to-noise ratio. The WOM outperforms bare PMTs especially with respect to the low signal-to-noise ratio with an increase of a factor up to 8.9 in air (5.2 in ice). Since the gain in sensitivity is mostly in the UV-regime, the WOM is an ideal sensor for Cherenkov and scintillation detectors.
ISSN:2331-8422