Dark matter search results from the PICO-60 CF3 I bubble chamber

• Published in: Physical review. D 2016-03, Vol.93 (5)
• Main Authors: Amole, C., Ardid, M., Asner, D. M., Baxter, D., Behnke, E., Bhattacharjee, P., Borsodi, H., Bou-Cabo, M., Brice, S. J., Broemmelsiek, D., Clark, K., Collar, J. I., Cooper, P. S., Crisler, M., Dahl, C. E., Daley, S., Das, M., Debris, F., Dhungana, N., Fallows, S., Farine, J., Felis, I., Filgas, R., Girard, F., Giroux, G., Grandison, A., Hai, M., Hall, J., Harris, O., Jin, M., Krauss, C. B., Lafrenière, M., Laurin, M., Lawson, I., Levine, I., Lippincott, W. H., Mann, E., Maurya, D., Mitra, P., Neilson, R., Noble, A. J., Plante, A., Podviianiuk, R. B., Priya, S., Ramberg, E., Robinson, A. E., Rucinski, R., Ruschman, M., Scallon, O., Seth, S., Simon, P., Sonnenschein, A., Štekl, I., Vázquez-Jáuregui, E., Wells, J., Wichoski, U., Zacek, V., Zhang, J., Shkrob, I. A.
• Format: Article
• Language: English
• Subjects: PICO-60
• ISSN: 2470-0010; 2470-0029
• DOI: 10.1103/PhysRevD.93.052014

New data are reported from the operation of the PICO-60 dark matter detector, a bubble chamber filled with 36.8 kg of CF3I and located in the SNOLAB underground laboratory. PICO-60 is the largest bubble chamber to search for dark matter to date. With an analyzed exposure of 92.8 livedays, PICO-60 exhibits the same excellent background rejection observed in smaller bubble chambers. Alpha decays in PICO-60 exhibit frequency-dependent acoustic calorimetry, similar but not identical to that reported recently in a C3F8 bubble chamber. PICO-60 also observes a large population of unknown background events, exhibiting acoustic, spatial, and timing behaviors inconsistent with those expected from a dark matter signal. These behaviors allow for analysis cuts to remove all background events while retaining 48.2% of the exposure. Stringent limits on weakly interacting massive particles interacting via spin-dependent proton and spin-independent processes are set, and most interpretations of the DAMA/LIBRA modulation signal as dark matter interacting with iodine nuclei are ruled out.