Ultra-low radioactivity flexible printed cables

EPJ Techniques and Instrumentation

Research Article

Isaac J. Arnquist¹  Richard Saldanha¹  Tyler Schlieder¹  Nicole Rocco¹  Maria Laura di Vacri¹  Mario Perez²  Harshad Uka²  Jay Patil²  Raj Patel² 

[1] Pacific Northwest National Laboratory, 99352, Richland, Washington, USA;Q-Flex Inc., 92705, Santa Ana, California, USA;

关键词: Flexible cables;    Polyimide;    Radioactivity;    Low background experiments;   

DOI  :  10.1140/epjti/s40485-023-00104-6

 received in 2023-05-08, accepted in 2023-08-17,  发布年份 2023

来源: Springer

【 摘 要 】

Flexible printed cables and circuitry based on copper-polyimide materials are widely used in experiments looking for rare events due to their unique electrical and mechanical characteristics. However, past studies have found copper-polyimide flexible cables to contain 400-4700 pg 238U/g, 16-3700 pg 232Th/g, and 170-2100 ng natK/g, which can be a significant source of radioactive background for many current and next-generation ultralow background detectors. This study presents a comprehensive investigation into the fabrication process of copper-polyimide flexible cables and the development of custom low radioactivity cables for use in rare-event physics applications. A methodical step-by-step approach was developed and informed by ultrasensitive assay to determine the radiopurity in the starting materials and identify the contaminating production steps in the cable fabrication process. Radiopure material alternatives were identified, and cleaner production processes and treatments were developed to significantly reduce the imparted contamination. Through the newly developed radiopure fabrication process, fully-functioning cables were produced with radiocontaminant concentrations of 20-31 pg 238U/g, 12-13 pg 232Th/g, and 40-550 ng natK/g, which is significantly cleaner than cables from previous work and sufficiently radiopure for current and next-generation detectors. This approach, employing witness samples to investigate each step of the fabrication process, can hopefully serve as a template for investigating radiocontaminants in other material production processes.

【 授权许可】

CC BY   
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2023

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