Testing of High Voltage Surge Protection Devices for Use in Liquid Argon TPC Detectors

In this paper we demonstrate the capability of high voltage varistors and gas discharge tube arrestors for use as surge protection devices in liquid argon time projection chamber detectors. The insulating and clamping behavior of each type of device is characterized in air (room temperature), and liquid argon (90~K), and their robustness under high voltage and high energy surges in cryogenic conditions is verified. The protection of vulnerable components in liquid argon during a 150 kV high voltage discharge is also demonstrated. Each device is tested for argon contamination and light emission effects, and both are constrained to levels where no significant impact upon liquid argon time projection chamber functionality is expected. Both devices investigated are shown to be suitable for HV surge protection applications in cryogenic detectors.Comment: 22 pages, 18 figures v2: reduced file size for journal submissio

Construction and Assembly of the Wire Planes for the MicroBooNE Time Projection Chamber

In this paper we describe how the readout planes for the MicroBooNE Time Projection Chamber were constructed, assembled and installed. We present the individual wire preparation using semi-automatic winding machines and the assembly of wire carrier boards. The details of the wire installation on the detector frame and the tensioning of the wires are given. A strict quality assurance plan ensured the integrity of the readout planes. The different tests performed at all stages of construction and installation provided crucial information to achieve the successful realisation of the MicroBooNE wire planes.Comment: 24 pages, 22 figures, accepted for publication as Technical Report in JINS

Development of a novel, windowless, amorphous selenium based photodetector for use in liquid noble detectors

Detection of the vacuum ultraviolet (VUV) scintillation light produced by liquid noble elements is a central challenge in order to fully exploit the available timing, topological, and calorimetric information in detectors leveraging these media. In this paper, we characterize a novel, windowless amorphous selenium based photodetector with direct sensitivity to VUV light. We present here the manufacturing and experimental setup used to operate this detector at low transport electric fields (2.7-5.2 V/$\mu$m) and across a wide range of temperatures (77K-290K). This work shows that the first proof-of-principle device windowless amorphous selenium is robust under cryogenic conditions, responsive to VUV light at cryogenic temperatures, and preserves argon purity. These findings motivate a continued exploration of amorphous selenium devices for simultaneous detection of scintillation light and ionization charge in noble element detectors

Surgical clipping compared to endovascular coiling of ruptured coil able middle cerebral aneurysms: A single-center experience

Objective: The middle cerebral artery (MCA) is the third most common site for ruptured intracranial aneurysms. Aneurysms in this location are known to be challenging to treat endovascularly and are commonly treated with microsurgery. Although advances in endovascular treatment options for cerebral aneurysms have markedly reduced the need for surgery in recent years and decades, there is no compelling scientific evidence that endovascular treatments are superior to surgical treatment. The present study aimed to determine the appropriate treatment modality in ruptured MCA aneurysms. Methods: We retrospectively evaluated and compared the treatment outcomes of 80 patients with ruptured MCA aneurysms who underwent either endovascular or microsurgical treatment in our center between 2011 and 2016. Post-treatment clinical and radiological outcomes were assessed in all patients. Furthermore, we compared intraoperative complications and the need for re-treatments between the two groups. Results: According to our findings, complete aneurysm occlusion was achieved in 90.5 and 89.2 of the patients in the clipping and coil group, respectively (p = 0.850). Moreover, 14.3 of the patients in the clipping group and 15.8 of the subjects in the coil group developed intraoperative complications (p = 0.851), including 3 cases of intraoperative hemorrhage and 3 cases of ischemia in the clipping group as well as 2 cases of thromboembolism and 4 cases of vasospasm during endovascular treatment in the coil group. There was an improvement in the modified Rankin score (mRS) at six months, with no significant difference between the two groups (p = 0.916). Conclusion: The results of coiling only with coil able MCA aneurysms were comparable to the results of clipping with difficult cases. Sufficient follow-up study of recurrence and retreatment are needed to determine the indication for coiling for ruptured MCA aneurysm. © 202

Calibration of the charge and energy loss per unit length of the MicroBooNE liquid argon time projection chamber using muons and protons

We describe a method used to calibrate the position- and time-dependent response of the MicroBooNE liquid argon time projection chamber anode wires to ionization particle energy loss. The method makes use of crossing cosmic-ray muons to partially correct anode wire signals for multiple effects as a function of time and position, including cross-connected TPC wires, space charge effects, electron attachment to impurities, diffusion, and recombination. The overall energy scale is then determined using fully-contained beam-induced muons originating and stopping in the active region of the detector. Using this method, we obtain an absolute energy scale uncertainty of 2% in data. We use stopping protons to further refine the relation between the measured charge and the energy loss for highly-ionizing particles. This data-driven detector calibration improves both the measurement of total deposited energy and particle identification based on energy loss per unit length as a function of residual range. As an example, the proton selection efficiency is increased by 2% after detector calibration