Characterization of a double Time-Of-Flight detector system for accurate velocity measurement in a storage ring using laser beams
Characterization of a double Time-Of-Flight detector system for accurate velocity measurement in a storage ring using laser beams
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使用激光束精确测量存储环速度的双飞行时间探测器系统的表征
DOI：
10.1016/j.nima.2019.03.058
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
Zhang Yu Hu
中科院分区：
文献类型：
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作者：
Yan Xin Liang;Chen Rui Jiu;Wang Meng;Yuan You Jin;Yuan Jian Dong;Wang Shao Ming;Cai Guo Zhu;Zhang Min;Lu Zi Wei;Fu Chao Yi;Zhou Xu;Zhao Dong Mei;Litvinov Yuri A;Zhang Yu Hu
同位素质谱仪（IMS）是测量储存环中半衰期短至几十微秒的奇异核质量的有力工具。为了提高质量分辨能力，同时保持接受的储存环，IMS与两个飞行时间（TOF）探测器已实施在储存环CSRe在中国兰州。通过使用双TOF探测器系统，可以获得除了环中的旋转时间之外的每个存储离子的附加速度信息。本文介绍了一种利用658 nm激光测距仪和短脉冲紫外激光直接测量安装在10 − 11 mbar真空室内的两个TOF探测器之间的距离和时间延迟差的新方法。结果表明，在20× 20 mm 2的可测面积内，两个TOF探测器的超薄碳膜间距为18032.5 ~ 18035.0 mm。给定测量的距离，两个TOF检测器之间的信号电缆长度差所带来的时间延迟差被测量为Δ t d e l a y 1− 2= 99（26）ps。新方法使我们能够使用真空中的光速来校准环中存储离子的速度。推导出CSRe现有双TOF探测器系统的速度分辨率为σ（v）scinv = 4。4× 1 0− 4，主要受TOF探测器的时间分辨率限制。
Abstract The Isochronous Mass Spectrometry (IMS) is a powerful tool for mass measurements of exotic nuclei with half-lives as short as several tens of micro-seconds in storage rings. In order to improve the mass resolving power while preserving the acceptance of the storage ring, the IMS with two Time-Of-Flight (TOF) detectors has been implemented at the storage ring CSRe in Lanzhou, China. Additional velocity information beside the revolution time in the ring can be obtained for each of the stored ions by using the double TOF detector system. In this paper, we introduced a new method of using a 658 nm laser range finder and a short-pulsed ultra-violet laser to directly measure the distance and time delay difference between the two TOF detectors which were installed inside the 1 0− 11 mbar vacuum chambers. The results showed that the distance between the two ultra-thin carbon foils of the two TOF detectors was ranging from 18032.5 mm to 18035.0 mm over a measurable area of 20× 20 mm 2. Given the measured distance, the time delay difference which comes with signal cable length difference between the two TOF detectors was measured to be Δ t d e l a y 1− 2= 99 (26) ps. The new method has enabled us to use the speed of light in vacuum to calibrate the velocity of stored ions in the ring. The velocity resolution of the current double TOF detector system at CSRe was deduced to be σ (v)∕ v= 4. 4× 1 0− 4 for laser light, mainly limited by the time resolution of the TOF detectors.