New Limits on the Coherent Neutrino-Nucleus Elastic Scattering Cross Section at the Kuo-Sheng Reactor-Neutrino Laboratory
S. Karmakar, M. K. Singh, V. Sharma, H. T. Wong, C. Greeshma, H. B. Li, L. Singh, M. Ağartıoğlu, C. H. Cheng, C. I. Chiang, M. Deniz, Hsu‐Cheng Hsu, S. Karadaǧ, Vineet Kumar, C. H. Leung, Jiatong Li, F. K. Lin, S. T. Lin, S. K. Liu, Haitao Ma, Kapil Saraswat, M. K. Singh, V. Singh, D. Tanabe, J. S. Wang, L. T. Yang, Chih-Hsiang Yeh, Q. Yue
Abstract
Neutrino-nucleus elastic scattering (νA_{el}) with partial quantum-mechanical coherency has been observed in several nuclei with neutrinos from decay-at-rest pions. This interaction with reactor neutrinos where coherency is >95% has not yet been experimentally observed. We present new results on the studies of the νA_{el} cross section with an electrocooled p-type point-contact germanium detector at the Kuo-Sheng Reactor Neutrino Laboratory. A total of 242(357) kg-days of Reactor ON(OFF) data at a detector threshold of 200 eV in ionization energy are analyzed. The Lindhard model parametrized by a single variable k which characterizes the quenching function was used. A limit at 90% confidence level of ρ<4.7 at the predicted value of k=0.162 is derived, where ρ is the ratio of the measured to standard model (SM) cross section. Conversely, k<0.288 at the SM value of ρ=1.