Dark Matter Annual Modulation Signatures Probed and Rejected by CDEX Experiment
The CDEX experiment at the Jinping Underground Laboratory performed “Annual Modulation (AM)” measurements with sufficient sensitivity to detect small changes of event rates due to the hypothetical Dark Matter (WIMP) over 4.2 years. The results are published in Physical Review Letters.
Experimental evidence on WIMP observation from the DAMA/LIBRA and CoGeNT experiments stands on AM measurements with a timing-pattern consistent with theoretical expectations. The WIMP interpretation is in serious disagreement with many other experiments measuring the total detection rates. The analysis which connect both measurement concepts requires that certain astrophysical models have to be assumed.
The CDEX AM data provided a direct identical probe to address this drawback. The principles of the measurements are depicted in the figure attached. Leading experimental sensitivities are achieved, enhanced by the long exposure time as well as good operation stability and low energy threshold of the germanium detector target. The results do not show evidence of AM and exclude the allowed parameters of both experiments.
The Academia Sinica-based TEXONO program is a founding partner of the CDEX experiment. AS postdoc fellow Dr. Hau-Bin Li has played major roles in the conception, execution and completion of this work.
Schematic Diagram Illustrating the Physics Basis of WIMP Annual Modulation
