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Register a new userA compact ultra-clean system for deploying radioactive sources inside the KamLAND detector
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We describe a compact, ultra-clean device used to deploy radioactive sources along the vertical axis of the KamLAND liquid-scintillator neutrino detector for purposes of calibration. The device worked by paying out and reeling in precise lengths of a hanging, small-gauge wire rope (cable); an assortment of interchangeable radioactive sources could be attached to a weight at the end of the cable. All components exposed to the radiopure liquid scintillator were made of chemically compatible UHV-cleaned materials, primarily stainless steel, in order to avoid contaminating or degrading the scintillator. To prevent radon intrusion, the apparatus was enclosed in a hermetically sealed housing inside a glove box, and both volumes were regularly flushed with purified nitrogen gas. An infrared camera attached to the side of the housing permitted real-time visual monitoring of the cables motion, and the system was controlled via a graphical user interface.
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The Deep Underground Neutrino Experiment (DUNE) is a leading-edge, international experiment for neutrino science and proton decay studies. This experiment is looking for answers regarding several fundamental questions about the nature of matter and the evolution of the universe: origin of matter, unification of forces, physics of black holes. Two far detector prototypes using two distinct technologies have been developed at CERN. The prototypes are testing and validating the liquid argon time projection chamber technology (LArTPC). In neutrino physics, as well as in any experiment with rare interaction rate, the good knowledge of the radioactive backgrounds is important to the success of the study. Unlike most of the charged particles or short lived neutral particles, muons and neutrons represent the main sources of background for this kind of experiments. In this paper, we have considered two sources of neutrons: cosmic neutrons and neutrons coming from the accelerating tunnel. Also, cosmic muons are taken into account. The contribution of these particles to the production of radioactive isotopes inside the active volume of the detector in comparison to the one corresponding to muons is shown. Also, simulations of nuclear reactions for the processes of interest for investigating the radioactive background due to the lack of measurements or insufficient experimental data are presented. The results presented are of interest for the future underground DUNE experiment.
The focal-plane detector system for the KArlsruhe TRItium Neutrino (KATRIN) experiment consists of a multi-pixel silicon p-i-n-diode array, custom readout electronics, two superconducting solenoid magnets, an ultra high-vacuum system, a high-vacuum system, calibration and monitoring devices, a scintillating veto, and a custom data-acquisition system. It is designed to detect the low-energy electrons selected by the KATRIN main spectrometer. We describe the system and summarize its performance after its final installation.
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SNO+ is a large-scale liquid scintillator experiment with the primary goal of searching for neutrinoless double beta decay, and is located approximately 2 km underground in SNOLAB, Sudbury, Canada. The detector acquired data for two years as a pure water Cherenkov detector, starting in May 2017. During this period, the optical properties of the detector were measured in situ using a deployed light diffusing sphere, with the goal of improving the detector model and the energy response systematic uncertainties. The measured parameters included the water attenuation coefficients, effective attenuation coefficients for the acrylic vessel, and the angular response of the photomultiplier tubes and their surrounding light concentrators, all across different wavelengths. The calibrated detector model was validated using a deployed tagged gamma source, which showed a 0.6% variation in energy scale across the primary target volume.
An automatic target monitoring method based on photographs taken by a CMOS photo-camera has been developed for the MEG II detector. The technique could be adapted for other fixed-target experiments requiring good knowledge of their target position to avoid biases and systematic errors in measuring the trajectories of the outcoming particles. A CMOS-based, high resolution, high radiation tolerant and high magnetic field resistant photo-camera was mounted inside the MEG II detector at the Paul Scherrer Institute (Switzerland). MEG II is used to search for lepton flavour violation in muon decays. The photogrammetric methods challenges, affecting measurements of low momentum particles tracks, are high magnetic field of the spectrometer, high radiation levels, tight space constraints, and the need to limit the material budget in the tracking volume. The camera is focused on dot pattern drawn on the thin MEG II target, about 1 m away from the detector endcaps where the photo-camera is placed. Target movements and deformations are monitored by comparing images of the dots taken at various times during the measurement. The images are acquired with a Raspberry board and analyzed using a custom software. Global alignment to the spectrometer is guaranteed by corner cubes placed on the target support. As a result, the target monitoring fulfils the needs of the experiment.
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