原初引力波与暴胀宇宙学

2014年3月17日,天文学家宣布在宇宙微波背景辐射中发现了B模式偏振。根据暴胀宇宙学模型的预言,B模式偏振是宇宙诞生之初产生的原初引力波留在宇宙微波背景辐射中的特殊痕迹。引力波作为广义相对论的重要预言,至今没有得到确证,这一发现是引力波理论提出以来关于引力波存在的最重要证据。同时,这一发现强有力地支持了大爆炸和暴胀理论,或对今后宇宙学的发展产生深远影响。     

杭州市大气细颗粒物分粒径来源解析

利用安德森分级采样器采集大气细颗粒物样品,分析它们的质量浓度及无机元素、水溶性离子和碳等组分的含量.采用OC/EC最小比值法确定二次有机碳对细颗粒物的贡献,重新构建受体化学成分谱.使用化学质量平衡模型对杭州市区大气细颗粒物进行分粒径来源解析.结果表明,在小粒径段中,二次粒子和机动车尾气尘为主要贡献源类;在粗粒径段中,城市扬尘、建筑水泥尘和煤烟尘的贡献逐渐增多,二次粒子与机动车尾气尘的总分担率下降到50%左右.     

重庆市大气总悬浮颗粒物来源解析

于2001至2002年在重庆市7个采样点采集了TSP,并收集了7类尘污染源的TSP样品。对受体和源样品进行无机元素、有机碳、元素碳及水溶性离子分析,得到受体和源成分谱,用CMB模型解析了重庆市大气TSP来源。结果发现：各源类对TSP贡献率为扬尘30%、建筑尘25%、煤烟尘18%、机动车尘10%、钢铁尘8%、其他9%。与1992年解析结果比较发现：从1992年到2002年重庆市主城区大气TSP来源发生了转变,从煤烟尘和钢铁尘为主的污染逐渐变成以建筑尘、扬尘、煤烟尘和机动车尘混合型的污染。     

Probing primordial gravitational waves: Ali CMB Polarization Telescope

In this paper, we will give a general introduction to the Ali CMB Polarization Telescope (AliCPT) project, which is a Sino–US joint project led by the Institute of High Energy Physics and involves many different institutes in China. It is the first ground-based Cosmic Microwave Background (CMB) polarization experiment in China and an integral part of China''s Gravitational-wave Program. The main scientific goal of the AliCPT project is to probe the primordial gravitational waves (PGWs) originating from the very early Universe. The AliCPT project includes two stages. The first stage, referred to as AliCPT-1, is to build a telescope in the Ali region of Tibet at an altitude of 5250 meters. Once completed, it will be the highest ground-based CMB observatory in the world and will open a new window for probing PGWs in the northern hemisphere. The AliCPT-1 telescope is designed to have about 7000 transition-edge sensor detectors at 95 GHz and 150 GHz. The second stage is to have a more sensitive telescope (AliCPT-2) with more than 20 000 detectors. Our simulations show that AliCPT will improve the current constraint on the tensor-to-scalar ratio r by one order of magnitude with three years'' observation. Besides the PGWs, AliCPT will also enable a precise measurement of the CMB rotation angle and provide a precise test of the CPT symmetry. We show that three years'' observation will improve the current limit by two orders of magnitude.     

重庆市大气总悬浮颗粒物来源解析

于2001至2002年在重庆市7个采样点采集了TSP，并收集了7类尘污染源的TSP样品。对受体和源样品进行无机元素、有机碳、元素碳及水溶性离子分析，得到受体和源成分谱，用CMB模型解析了重庆市大气TSP来源。结果发现：各源类对TSP贡献率为扬尘30%、建筑尘25%、煤烟尘18%、机动车尘10%、钢铁尘8%、其他9%。与1992年解析结果比较发现：从1992年到2002年重庆市主城区大气TSP来源发生了转变，从煤烟尘和钢铁尘为主的污染逐渐变成以建筑尘、扬尘、煤烟尘和机动车尘混合型的污染。