The Wand Chooses the IMU - Open Source Hardware for Synchronising Wearables using Magnetometers

This paper presents the Synchronisation Wand, an open-source hardware solution which can be used to synchronise multiple inertial measurement unit sensors (IMU) using their onboard magnetometers. The wand is based on commercial off-the-shelf components with standard 4-layer PCB manufacturing and self-service assembly. The case can be 3D printed using any Fused Filament Fabrication (FFF) based printer. The system combines an ESP32-S3 micro-controller unit with an electromagnetic (EM) generator to create an encoded EM event which can be used to synchronise multiple IMUs. The hardware includes an onboard IMU allowing the user to track the motion of the wand as well as perform kinetic synchronising events. The device also includes an OLED display and 4 configurable tactile switches to enhance the usability of the system. We demonstrate the device's capability to generate an encoded EM pulse which can be used to reduce the maximum synchronisation error between two IMUs down to 10ms

Low-mass dark matter search results from full exposure of PandaX-I experiment

We report the results of a weakly-interacting massive particle (WIMP) dark matter search using the full 80.1\;live-day exposure of the first stage of the PandaX experiment (PandaX-I) located in the China Jin-Ping Underground Laboratory. The PandaX-I detector has been optimized for detecting low-mass WIMPs, achieving a photon detection efficiency of 9.6\%. With a fiducial liquid xenon target mass of 54.0\,kg, no significant excess event were found above the expected background. A profile likelihood analysis confirms our earlier finding that the PandaX-I data disfavor all positive low-mass WIMP signals reported in the literature under standard assumptions. A stringent bound on the low mass WIMP is set at WIMP mass below 10\,GeV/c$^2$, demonstrating that liquid xenon detectors can be competitive for low-mass WIMP searches.Comment: v3 as accepted by PRD. Minor update in the text in response to referee comments. Separating Fig. 11(a) and (b) into Fig. 11 and Fig. 12. Legend tweak in Fig. 9(b) and 9(c) as suggested by referee, as well as a missing legend for CRESST-II legend in Fig. 12 (now Fig. 13). Same version as submitted to PR