Measurement of the 60Co gamma–gamma Angular Correlation with an Unsegmented Liquid-Scintillator Detector
Year: 2026
Type: article
Abstract: We report a measurement of the gamma–gamma angular correlation in the $^{60}$Co cascade using a compact coincidence setup based on two unsegmented liquid-scintillator (LS) detector modules read out by photomultiplier tubes. The beta-minus decay of $^{60}$Co produces two prompt gamma rays of 1173 keV and 1332 keV in the well-known $4^+\!\rightarrow \!2^+\!\rightarrow \!0^+$ cascade, whose angular correlation can be described by an even-order Legendre expansion. Although unsegmented LS detectors do not provide event-by-event interaction-point information as segmented crystal scintillators or high-purity germanium arrays do, the correlation can be recovered statistically from coincidence timing in a fixed detector geometry. We fit the measured angular-correlation distribution with $W(\theta )=1+A_2P_2(\cos \theta )+A_4P_4(\cos \theta )$, yielding $A_2=0.1018\pm 0.0146$ and $A_4=0.0116\pm 0.0183$. These values are consistent with the theoretical coefficients $A_2^{\rm th}=0.102\,041$ and $A_4^{\rm th}=0.009\,070$ for a pure $E2$–$E2$ cascade. This work indicates that gamma–gamma angular-correlation coefficients can be quantitatively extracted with a compact, unsegmented LS system. It provides an initial benchmark for large homogeneous scintillation geometries in which event-by-event angular tagging is unavailable, and supports the feasibility of future coincidence applications with doped LS or water-based liquid-scintillator media.
DOI: 10.1093/ptep/ptag076
Authors: Hoeheon Jeong, Jubin Park, Myung-Ki Cheoun, Yechan Maeng, Ji Young Choi, Kyung Kwang Joo
Institutions: Soongsil University, Chonnam National University
Language: English
Subfield: Radiation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $979
Funder: National Research Foundation
OpenAlex ID: W7160380149