Neutron capture on deformed rare-earth nuclei provides stringent tests of nuclear reaction models and constitutes a key benchmark for both nuclear data evaluation and s-process nucleosynthesis studies. As a stable odd-A rare-earth nucleus with a pronounced deformed structure, ¹⁵⁹Tb plays an important role in reactor-related calculations, activation analysis, nuclear data evaluation, and s-process nucleosynthesis in the rare-earth mass region. Although previous measurements have been performed at thermal and MeV neutron energies, experimental data in the eV to several hundred eV region remain scarce, and independent constraints on resonance parameters are still limited. To provide independent experimental constraints in this energy region, the ¹⁵⁹Tb(n,γ) reaction cross section is measured at the Back-n white neutron beam line of the China Spallation Neutron Source (CSNS) using the Gamma Total Absorption Facility (GTAF). The incident neutron energy is determined by the time-of-flight method over a wide white neutron spectrum. Capture events are identified by applying summed-energy window selection, crystal multiplicity gating, and pulse-shape discrimination to suppress background contributions. Dead-time correction is performed to account for the high instantaneous counting rate of the detection system. Background components are evaluated and subtracted using dedicated measurements with ^natC and empty samples, leading to the net capture yield spectrum. Based on these procedures, the experimental cross section is obtained over the 1–1000 eV energy range.
An R-matrix analysis was performed using the SAMMY code to extract resonance parameters in the resolved resonance region (1–100 eV). The extracted resonance energies and widths well reproduce the main resonance structures and are consistent with the ENDF/B-VIII.0 evaluation within uncertainties, with no indication of systematic bias. Comparison with ENDF/B-VIII.0, JEFF-4.0, JENDL-5 and BROND-3.1 shows overall consistency in the major resonance structures and energy dependence, although some local discrepancies remain in weak or complex regions. Several weak structures are observed in the experimental spectrum; although they may suggest resonance-like features, contributions from sample impurities and neutron-beam-related effects and local analysis sensitivity cannot be excluded, and a definitive interpretation requires further study. The present work provides both experimental cross sections in the 1–1000 eV region and independently extracted resonance parameters in the 1–100 eV region, thereby strengthening the experimental basis for resonance-region nuclear data of ¹⁵⁹Tb. The present measurement provides independent experimental constraints on neutron capture in a deformed rare-earth nucleus and establishes ¹⁵⁹Tb as a rare-earth benchmark for resonance-region nuclear data, contributing to improved reliability of evaluated libraries for nuclear astrophysics and reactor-related applications.