用于PICO暗物质搜索的无缓冲概念泡室
A buffer-free concept bubble chamber for PICO dark matter searches
摘要：
在本文中，我们报告的成功运作在德雷克塞尔大学的PICO合作的第一个C $_3$ F $_8$无缓冲原型氟碳化合物泡室。之前的PICO泡室使用氟碳靶流体产生了世界领先的WIMP搜索结果，通过水缓冲层与钢波纹管隔开。罐壁和液-液界面处的表面张力效应导致一类具有核反冲样声学特征的背景事件，从而污染分析中的WIMP样信号区域。因此，新的泡室将被构造为“正面朝上”，这意味着C $_3$ F $_8$的罐在波纹管上方，内部容器内没有水。Drexel泡室（DBC）在PICO用于WIMP搜索的核反冲阈值及以下成功运行，包括低至1.19 keV的阈值。我们已经证明了对$^{137}$ Cs γ和来自$^{244}$ Cm的自发裂变中子的敏感性，并且尽管所观察到的α衰变率非常低，但声学α辨别被证明是可能的。来自立体成像的位置重建允许用于校准数据的基本分析切割。该原型的成功建造和运行证实了右侧向上设计的有效性，该设计将用于未来的暗物质搜索，如PICO-40 L和PICO-500。
英文摘要：
In this paper, we report on the successful operation at Drexel University of the PICO collaboration's first C$_3$F$_8$ buffer-free prototype fluorocarbon bubble chamber. Previous PICO bubble chambers have produced world-leading WIMP search results with fluorocarbon target fluids, separated from the steel bellows by a buffer layer of water. Surface tension effects at the jar walls and liquid-liquid interface lead to a class of background events which have nuclear-recoil-like acoustic signatures and thus contaminate the WIMP-like signal region in analysis. Thus new bubble chambers are to be constructed "right-side-up", meaning that the jar of C$_3$F$_8$ is above the bellows with no water inside the inner vessel. The Drexel Bubble Chamber (DBC), runs successfully at and below the nuclear recoil thresholds used by PICO for WIMP searches, including thresholds as low as 1.19 keV. We have demonstrated sensitivity to $^{137}$Cs gammas and spontaneous fission neutrons from $^{244}$Cm, and acoustic alpha discrimination is demonstrated to be possible although the observed rate of alpha decays is very low. Position reconstruction from stereoscopic imaging allows for basic analysis cuts for calibration data. The successful construction and operation of this prototype confirm the effectiveness of the right-side-up design, which will be used in future dark matter searches such as PICO-40L and PICO-500.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
