Speaker
Description
The intrinsic $^{14}$C background in liquid scintillator is a major source of low-energy events in JUNO and affects detector performance, including energy resolution, with consequences for low-energy physics analyses. A precise determination of the $^{14}$C decay rate therefore serves multiple purposes such as detector characterisation and background modelling.
In this poster, we present measurements of the $^{14}$C rate in the JUNO liquid scintillator using early physics data, based on three complementary and largely independent approaches. The first method uses periodic-trigger data to measure the intrinsic low-energy event rate with minimal physics event bias. The second uses low-threshold data recorded by the multi-messenger trigger system to extract the $^{14}$C contribution using a MCMC method. The third constrains the $^{14}$C decay rate through pile-up effects observed in calibration gamma-source energy spectra.
The results obtained with these methods are mutually consistent. These measurements provide important inputs to support future developments in pile-up identification and improvements in low-energy reconstruction. In addition, we briefly discuss possible strategies for identifying $^{14}$C related pile-up events based on their characteristic low-energy and timing features.