Anode Development for NEXT at UT-Arlington HEP

Searches for neutrinoless double beta decay are contingent upon the proper and indisputable detection of what may be a very small number of signal events, over a large background of gamma rays. One method of collecting the scintillation light from such events is through use of a Silicon Photomultiplier (SiPM) wheel. This device must be optically transparent (to allow for the light to pass through the wheel unobstructed and for the wheel) and electrically conductive (to function as a TPC anode). Prominent candidates for the substrate material are Static-Dissipative Acrylic and standard acrylic coated with a highly-conductive ink named PEDOT. On the other hand, SiPMs are intrinsically non-responsive to wavelengths within the xenon scintillation spectrum. Tetraphenyl butadiene (TPB), an organic wavelength shifter, has been proposed as coating to shift these wavelengths to the sensitive range of the optical detectors. The effects of TPB on incoming light have been studied, including attenuation lengths, node behavior (behavior at the TPB-acrylic interface) and other such factors. I will present these studies, which have helped fine-tune the model for an ideal anode for the NEXT experiment.