Design and Fabrication of Liquid Scintillator Counter

Pacific Northwest National Laboratory (PNNL) is currently developing an ultra-low background liquid scintillator counter (ULB LSC) in the shallow underground laboratory. At a depth of 35-meters water-equivalent, the underground laboratory has a multi-layered shielding to keep out cosmic-ray induced background. The ULB LSC, which is located in a clean room facility, is a multi-layered design made up of various materials, including plastic scintillator veto panels, borated polyethylene, lead and copper. These layers help lower the contributions of the terrestrial background and intrinsic background, resulting from the impurities present in the materials, to the overall background count rate observed by the detectors. After the completion of the instrument, the first liquid scintillation sample will be tested using a pulley-like design. The design consists of a sample holder which holds the vial in place as it is lowered down into a light guide. The second component of the design is a piece which helps lower the sample holder in the correct orientation into the light guide in order to maximize light output and collection efficiency. The system is designed using Solidworks, a computer aided design (CAD) program, and 3D printed using Acrylonitrile Butadiene Styrene (ABS) plastic. The design for the sample holder is based off of another more complex design originally made of copper. This simplified sample handling design will accelerate the project toward initial data collection, an important milestone toward validating the UBL LSC system concept