In this paper we show that state-of-the-art commercial off-the-shelf Flash memory chip technology (20 nm technology node with multi-level cells) is quite sensitive to ionizing radiation. We find that the fail-bit count in these Flash chips starts to increase monotonically with gamma or X-ray dose at 100 rad(SiO2). Significantly more fail bits are observed in X-ray irradiated devices, most likely due to dose enhancement effects due to high-Z back-end-of-line materials. These results show promise for dosimetry application.
We present the results of mechanical characterizations of many different high-quality optical coatings made of ion-beam-sputtered titania-doped tantala and silica, developed originally for interferometric gravitational-wave detectors. Our data show that in multi-layer stacks (like high-reflection Bragg mirrors, for example) the measured coating dissipation is systematically higher than the expectation and is correlated with the stress condition in the sample. This has a particular relevance for the noise budget of current advanced gravitational-wave interferometers, and, more generally, for any experiment involving thermal-noise limited optical cavities.
CHIPS (CHerenkov detectors In mine PitS ) is a novel neutrino detector concept, aimed at building megaton water-Cherenkov neutrino detectors in a flexible and cheap way, while yielding science results comparable and contributing to conventional long-baseline neutrino experiments. In the summer of 2018, a 5 kiloton proof-of-principle detector will be installed in a disused water-filled mine pit located in the NuMI neutrino beamline path in Minnesota, USA. The submerged cylindrical detector volume is 25 meters in diameter and 10 meter tall and is surrounded by light-tight liners. All inside walls are covered with PMT holding structures. CHIPS will use thousands of 3-inch PMTs to detect neutrinos interacting in the high-purity water in the detector volume. The focus of the (poster) presentation at the NuPhys2017 conference was on DAQ and electronics for the CHIPS experiment.
Artificially-grown diamond crystals have unique properties that make them suitable as solid-state particle detectors and dosimeters in high-radiation environments. We have been using sensors based on single-crystal diamond grown by chemical vapour deposition for dosimetry and beam-loss monitoring at the SuperKEKB collider. Here we describe the assembly and the suite of test and calibration procedures adopted to characterise the diamond-based detectors of this monitoring system. We report the results obtained on 28 detectors and assess the stability and uniformity of response of these devices.
This paper explores the prospect of CMOS devices to assay lead in drinking water, using calorimetry. Lead occurs together with traces of radioisotopes, e.g. Lead-210, producing $gamma$-emissions with energies ranging from 10 keV to several 100 keV when they decay; this range is detectable in silicon sensors. In this paper we test a CMOS camera (Oxford Instruments Neo 5.5) for its general performance as a detector of x-rays and low energy $gamma$-rays and assess its sensitivity relative to the World Health Organization upper limit on lead in drinking water. Energies from 6 keV to 60 keV are examined. The CMOS camera has a linear energy response over this range and its energy resolution is for the most part slightly better than 2 %. The Neo sCMOS is not sensitive to x-rays with energies below $sim!!10 keV$. The smallest detectable rate is 40$pm$3 mHz, corresponding to an incident activity on the chip of 7$pm$4 Bq. The estimation of the incident activity sensitivity from the detected activity relies on geometric acceptance and the measured efficiency vs. energy. We report the efficiency measurement, which is 0.08$pm$0.02 % (0.0011$pm$0.0002 %) at 26.3 keV (59.5 keV). Taking calorimetric information into account we measure a minimal detectable rate of 4$pm$1 mHz (1.5$pm$0.1 mHz) for 26.3 keV (59.5 keV) $gamma$-rays, which corresponds to an incident activity of 1.0$pm$0.6 Bq (57$pm$33 Bq). Toy Monte Carlo and Geant4 simulations agree with these results. These results show this CMOS sensor is well-suited as a $gamma$- and x-ray detector with sensitivity at the few to 100 ppb level for Lead-210 in a sample.
The CHIPS experiment will comprise a 10 kton water Cherenkov detector in an open mine pit in northern Minnesota, USA. The detector has been simulated using a full GEANT4 simulation and a series of event reconstruction algorithms have been developed to exploit the charge and time information from all of the PMTs. A comparison of simulated CCQE nu_mu and nu_e interactions using 10 inch and 3 inch PMTs is presented, alongside a comparison of 10% and 6% photocathode coverage for 3 inch PMTs. The studies demonstrate that the required selection efficiency and purity of charged-current nu_e interactions can be achieved using a photocathode coverage of 6% with 3 inch PMTs. Finally, a dedicated pi-zero fitter is shown to successfully reconstruct a clean sample of pi-zero mesons despite the low 6% photocathode coverage with 3 inch PMTs.