Raman LIDARs for the atmospheric calibration along the line-of-sight of CTA
Otger Ballester, Oscar Blanch, Joan Boix, Johan Bregeon, Patrick Brun, Merve Colak, Michele Doro, Vania Da Deppo, Lluis Font, Omar Gabella, Rafael Garcia, Marku… 展开作者
Otger Ballester, Oscar Blanch, Joan Boix, Johan Bregeon, Patrick Brun, Merve Colak, Michele Doro, Vania Da Deppo, Lluis Font, Omar Gabella, Rafael Garcia, Markus Gaug, Camilla Maggio, Manel Martinez, Oscar Martinez, Pere Munar Adrover, Raul Ramos, Stephane Rivoire, Samo Stanic, David Villar, George Vasileiadis, Longlong Wang, Marko Zavrtanik
The Cherenkov Telescope Array (CTA) is the next generation ground based observatory for gamma ray astronomy at very high energies. Employing more than 100 Imaging Atmospheric Cherenkov Telescopes in the northern and southern hemispheres, it was designed to reach unprecedented sensitivity and energy resolution. Understanding and correcting for systematic biases on the absolute energy scale and instrument response functions will be a crucial issue for the performance of CTA. The LUPM group and the Spanish/Italian/Slovenian collaboration are currently building two Raman LIDAR prototypes for the online atmospheric calibration along the line of sight of the CTA. Requirements for such a solution include the ability to characterize aerosol extinction at two wavelengths to distances of 30 km with an accuracy better than 5%, within time scales of about a minute, steering capabilities and close interaction with the CTA array control and data acquisition system as well as other auxiliary instruments. Our Raman LIDARs have design features that make them different from those used in atmospheric science and are characterized by large collecting mirrors (2.5 m2), liquid light guides that collect the light at the focal plane and transport it to the readout system, reduced acquisition time and highly precise Raman spectrometers. The Raman LIDARs will participate in a cross calibration and characterization campaign of the atmosphere at the CTA North site at La Palma, together with other site characterization instruments. After a one year test period there, an in depth evaluation of the solutions adopted by the two projects will lead to a final Raman LIDAR design proposal for both CTA sites.
Status and motivation of Raman LIDARs development for the CTA Observatory
切伦科夫望远镜阵列（CTA）是下一代成像大气切伦科夫望远镜。它将在甚高能伽马射线天文学中达到前所未有的灵敏度和能量分辨率。为了达到这些目标，应将由变化的大气条件引起的系统不确定性减至最低。不同的工具可能有助于解释这些不确定性。CTA联盟中的几个小组目前正在建造安装在CTA站点的拉曼激光雷达。拉曼激光雷达是由射入大气的强大激光器，收集分子和气溶胶反向散射光的收集器，光电传感器，光谱选择感兴趣波长的光学模块和读出系统组成的设备。拉曼激光雷达可以将伽马射线能量重建的系统不确定性降低到5%的水平。所有拉曼激光雷达的主题，这项工作，有设计特点，使他们不同于典型的拉曼激光雷达在大气科学中使用，其特点是大收集镜（$\sim2~$ m $^2$）。它们具有多个弹性和拉曼读出通道（至少4个）和定制的光学设计。本文介绍了拉曼激光雷达产生的动机、设计方法和发展现状。
The IFAE/UAB and LUPM Raman LIDARs for Cherenkov Telescope Array Observatory
切伦科夫望远镜阵列（CTA）是下一代成像大气切伦科夫望远镜。它的灵敏度和能量分辨率在甚高能γ射线天文学中是前所未有的。为了实现这一目标，应将大气条件引起的系统不确定性降至最低。不同的工具可能有助于解释这些不确定性。巴塞罗那IFAE/UAB（分别为Institut de Física d 'Altes Energies和Universitat Autumnoma de Barcelona的缩写）和蒙彼利埃LUPM（蒙彼利埃大学和粒子研究所）小组正在建造拉曼激光雷达，这种装置可以将伽马射线能量重建的系统不确定性从20 $%$降低到5 $%$。拉曼激光雷达的主题，这项工作有同轴1.8米的反射镜与Nd-YAG激光器。液体光导在焦平面处收集光并将其传输到读出系统。我们正在开发一个单色仪，目的是测试两个激光雷达的读出链。该装置由滤光片系统和光电倍增管组成，将用于研究一种特殊的弹性通道。在对系统进行表征之后，我们将建立一个多色仪来收集稀疏拉曼信号，并对其进行优化以减少每一种可能的信号损失。我们报告了激光雷达的发展现状以及不同表征测试的最新结果。
Lidar-monitoring of atmospheric fluctuations for millimeter-wave astronomical observations
CNRS-UCB, Centre Pierre Binétruy, IRL 2007, CPB-IN2P3（法国国家科学研究中心-加州大学伯克利分校，皮埃尔·比内特鲁中心）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Laboratoire des Sciences du Climat et de l’Environnement (LSCE), CNRS-CEA-UVSQ（气候与环境科学实验室）；Université Paris-Saclay, CEA, IRFU（巴黎萨克雷大学）；Université Paris Cité, CNRS, Astroparticule et Cosmologie（巴黎西岱大学）
