9．Qin, Bo  (秦波)

       National Astronomical Observatories

       Chinese Academy of Sciences

       A20 Datun Road, Chaoyang

       Beijing 100012

       P.R.China

       Email: qinbo@bao.ac.cn

       Fax: +44-1865-273390

Title of talk: Dark Matter and Extra Dimensions

Abstract: Recent observations suggests that our standard picture of the "collisionless cold dark matter" model may have problems, and that dark matter particles may have considerable self-interaction. We find that this self-interaction is a natural consequence of a world with 3 large extra dimensions, where gravity diviates from Newtonian gravity in submillimeter scales and takes the r^{-5} law. We also study the enhanced gravity in large extra dimension scenarios and its implications for dark matter direct detections.

10．Wu, Xiang-Ping （武向平）

       National Astronomical Observatories

       Chinese Academy of Sciences

       A20 Datun Road, Chaoyang

       Beijing 100012

       P.R.China

       Email: wxp@bao.ac.cn

    Title of talk: Construction and Performance of 21 Centimeter Array (21CMA)

Abstract: 21CMA is an interferometric radio array dedicated to measurement of  the redshifted 21 cm emission/absorption signatures of neutral hydrogen against CMB in the epoch of reionization. The array, located in Xinjiang,  west China, consists of 81 pods with a total of 10287 log periodic antennas. It operates at frequencies from 50 to 200 MHz, covering a redshift range of 6-27. In this talk, I will present the motivation, construction and performance of 21CMA and its impact on our understanding of the history of reionization.