On the Reflectivity of 128 nm Photons Off Stainless Steel

TL;DR

This paper experimentally measures the reflectivity of 128 nm photons off stainless steel, finding a value of approximately 0.674, which is crucial for optimizing photon detection in relevant physics experiments.

Contribution

It provides the first direct experimental measurement of 128 nm photon reflectivity off stainless steel in a cryogenic environment.

Findings

Reflectivity R = 0.674 +/- 0.038 for stainless steel at 128 nm

Experiment conducted in Fermilab's TallBo dewar facility

No sensitivity to differences between specular and diffuse reflections

Abstract

This investigation presents a new experimental determination of the reflectivity of 128 nm scintillation photons off stainless steel. The experiment took place in the TallBo dewar facility at Fermilab. The data were obtained using a detector that is sensitive to photons falling on its front face but is insensitive to photons falling on its back face or its sides. By comparing the ratio of photons per track from tracks that illuminate the front face of the detector to those that cross the back side with a simulation of the experiment where the reflectivity can be varied, a value of the reflectivity was determined. The reflectivity for the SA-240-304L stainless steel alloy off which the scintillation photons reflect in the TallBo dewar as found by this experiment is R = 0.674 +/- 0.038. The experiment is not sensitive to the differences between specular and diffuse reflections.