Observation of radon mitigation in MicroBooNE by a liquid argon filtration system

• Published in: Journal of instrumentation 2022-11, Vol.17 (11)
• Main Authors: Abratenko, P., Anthony, J., Ashkenazi, A., Barrow, J., Bathe-Peters, L., Berkman, S., Bhat, A., Bhattacharya, M., Bishai, M., Blake, A., Book, J. Y., Camilleri, L., Caratelli, D., Caro Terrazas, I., Cavanna, F., Convery, M., Cooper-Troendle, L., Detje, P., Devitt, A., Diurba, R., Dorrill, R., Eberly, B., Fiorentini Aguirre, G. A., Foppiani, N., Franco, D., Garcia-Gamez, D., Gardiner, S., Gollapinni, S., Goodwin, O., Green, P., Greenlee, H., Hilgenberg, C., Hourlier, A., Itay, R., James, C., Ji, X., Joe, C., Johnson, R. A., Karagiorgi, G., Ketchum, W., Kirby, M., Kreslo, I., Li, J. -Y., Littlejohn, B. R., Louis, W. C., Luo, X., Manivannan, K., Mason, K., Mastbaum, A., McConkey, N., Miller, K., Mills, J., Mogan, A., Mohayai, T., Moor, A. F., Moore, C. D., Mulleriababu, S., Navrer-Agasson, A., Nayak, N., Neely, R. K., Newmark, D. A., Palamara, O., Paolone, V., Parkinson, H. B., Pate, S. F., Pavlovic, Z., Qian, X., Raaf, J. L., Rafique, A., Rice, L. C.J., Rochester, L., Rosenberg, M., Ross-Lonergan, M., Schmitz, D. W., Seligman, W., Sharankova, R., Smith, A., Snider, E. L., Soderberg, M., Söldner-Rembold, S., St. John, J., Sword-Fehlberg, S., Szelc, A. M., Terao, K., Thorpe, C., Torbunov, D., Totani, D., Toups, M., Tsai, Y. -T., Usher, T., Viren, B., Weber, M., Wolbers, S., Wospakrik, M., Wresilo, K., Yandel, E., Yang, T., Yates, L. E., Yu, H. W., Zhang, C.
• Format: Article
• Language: English
• Subjects: counting-gas and liquid purification; gas systems and purification; INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; noble liquid detectors (scintillation, ionization, double-phase); PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; time projection Chambers; TPC
• ISSN: 1748-0221; 1748-0221

We report the MicroBooNE liquid argon time projection chamber (LArTPC) maintains a high level of liquid argon purity through the use of a filtration system that removes electronegative contaminants in continuously-circulated liquid, recondensed boil off, and externally supplied argon gas. We use the MicroBooNE LArTPC to reconstruct MeV-scale radiological decays. Using this technique we measure the liquid argon filtration system's efficacy at removing radon. This is studied by placing a 500 kBq 222Rn source upstream of the filters and searching for a time-dependent increase in the number of radiological decays in the LArTPC. In the context of two models for radon mitigation via a liquid argon filtration system, a slowing mechanism and a trapping mechanism, MicroBooNE data supports a radon reduction factor of greater than 97% or 99.999%, respectively. Furthermore, a radiological survey of the filters found that the copper-based filter material was the primary medium that removed the 222Rn. This is the first observation of radon mitigation in liquid argon with a large-scale copper-based filter and could offer a radon mitigation solution for future large LArTPCs.