Extended Haloscope Search and Candidate Validation near 1.036G Hz
/ Authors
S. Ahn, B. Ivanov, Ohjoon Kwon, Heesu Byun, A. V. Loo, Seongtae Park, Jinmyeong Kim, J. Jeong, Soohyung Lee, Jinsu Kim
and 26 more authors
Ç. Kutlu, A.K. Yi, Yasunobu Nakamura, Seonjeong Oh, Danho Ahn, Sungjae Bae, Hyoungsoon Choi, Jihoon Choi, Yonuk Chong, W. Chung, Violeta Gkika, JihnE Kim, Younggeun Kim, B. Ko, L. Miceli, Doyu Lee, Jiwon Lee, Kiwoong Lee, MyeongJae Lee, Andrei Matlashov, P. Parashar, T. Seong, Y. C. Shin, S. Uchaikin, Y. Semertzidis, S. Youn
/ Abstract
We report a follow-up axion haloscope search near 1.036 GHz that completes and extends our previous work [Phys. Rev. X 14, 031023 (2024)], in which a portion of the HEMT-based data could not be analyzed due to unrecorded experimental information. While recovering this dataset, we identified an excess near 1.036 GHz that satisfied our candidate-selection criteria, motivating dedicated validation studies, including independent cross-checks and re-examination with the original apparatus. The excess did not persist under these investigations and was not confirmed as an axion dark-matter signal. We subsequently extended the search over a 20-MHz band surrounding the candidate using a quantum-noise-limited amplifier, achieving sensitivity close to the Dine-Fischler-Srednicki-Zhitnitsky benchmark. In the absence of a confirmed signal, we set improved 90% confidence-level upper limits on the axion-photon coupling over the frequency range 1.026-1.045 GHz. This work highlights the importance of robust candidate-validation strategies as haloscope searches approach discovery-level sensitivity.