MRI Consortium: Development of Upgraded Stellar Intensity Interferometry Instrumentation for the VERITAS Observatory

高能（VHE）伽马射线是在宇宙中一些最极端环境中发生的粒子加速中产生的。作为天体物理学的信使，他们的观测为研究这些高能事件的条件和过程提供了一个重要的窗口。该合同支持VERITAS伽玛射线天文台的镜面和相机系统的升级。自2007年开始运行以来，VERITAS成像空气切伦科夫望远镜直接暴露在亚利桑那州的元素中，随着时间的推移会影响12米镜面系统的响应。镜面表面的新发展和先进的保护涂层使望远镜的反射率恢复到接近原始状态成为可能，大大提高了天文台对VHE伽玛射线的灵敏度，覆盖了所有可获得的能量。一套用于增强准直和带通滤波的互补焦平面仪器也将使望远镜观测到的有效反射镜面积提高约两倍。结合起来，这些升级将显著增强正在进行的VERITAS观测任务，包括实时多信使跟踪，以及最近实施的新型恒星强度干涉测量（SII）计划。该奖项为开发这些新技术的学生和博士后研究人员提供了独特的培训机会，这些新技术将增强现有的VERITAS天文台，并对将技术扩展到下一代切伦科夫望远镜阵列（CTA）至关重要。镜面和焦平面升级将安装在亚利桑那州运行的现有四台VERITAS望远镜上。在与原镜子制造商的合作下，现有的镜子涂层将被剥离，新的铝和铪涂层将被应用于镜子表面，并添加石英（SiO2）涂层，以防止亚利桑那州恶劣的元素。一个加速计划是快速重新覆盖尽可能多的镜子，这将迅速使望远镜的反射率达到80-85%，提供30-35%的平均光增加，这将使天文台对软光谱源的灵敏度提高大约2倍。预计这种涂层技术将被证明更耐用，使用寿命更长（长达5年），减少VERITAS和未来仪器的长期维护。焦平面光学活动将允许径向梯度干涉滤光技术的发展和焦平面噪声的实质性减少。这些发展可能为未来天体物理学研究提供改进大型成像大气切伦科夫天文台（如VERITAS和CTA）灵敏度的转变能力。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Very-high energy (VHE) gamma-rays are produced in the particle accelerations that occur in some of the most extreme environments in the Universe. As astrophysical messengers, their observation provides an important window to study the conditions and processes underway in these energetic events. This award supports the instrument development for upgrades to the mirror and camera systems of the VERITAS gamma-ray observatory located at Amado, AZ. In operation since 2007, the VERITAS imaging air Cherenkov telescopes are directly exposed to the Arizona elements, impacting the response of the 12 meter mirror systems over time. New developments in mirror resurfacing and advanced protective coatings make it possible to restore the reflectivity of the telescopes to nearly their original state, significantly enhancing the observatory’s sensitivity to VHE gamma rays across the full range of accessible energies. A complementary suite of focal plane instrumentation for enhanced collimation and bandpass filtering will also improve the effective mirror area observed by the telescopes by approximately a factor of two. Combined, the upgrades will significantly augment the on-going VERITAS observing missions of VHE gamma-rays from astrophysical optics, including real-time multi-messenger follow-ups, and the recently implemented novel stellar intensity interferometry (SII) program. The award provides unique opportunities for training of student and postdoctoral researchers in developing these new technologies that will enhance the existing VERITAS observatory and are critical to extending the techniques to the next generation Cherenkov Telescope Array (CTA). The mirror and focal plane upgrades will be installed on the existing four VERITAS telescopes in operation in Arizona. In cooperation with the original mirror manufacturer, the existing mirror coatings will be stripped and a new aluminum and hafnium coating will be applied to the mirror surface, with a quartz (SiO2) overcoat added for protection from the harsh Arizona elements. An accelerated program to rapidly recoat as many mirrors as possible is planned that will quickly bring the telescopes' reflectivity to 80-85%, providing a 30-35% average increase in light that will improve the observatory’s sensitivity to soft spectrum sources by approximately a factor of 2. It is anticipated that this overcoat technology will prove to be more durable and last longer (up to 5 years), reducing long-term maintenance for VERITAS and future instruments. The focal plane optics activities will allow for the development of the radial-gradient interference filter technology and a substantial reduction in focal plane noise. These developments may provide future transformational capacity for improving the sensitivity of large Imaging Atmospheric Cherenkov observatories, such as VERITAS and CTA, for future astrophysics research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.