The RED-100 (Russian Emission Detector) is being constructed for the experiment to search for elastic coherent neutrino scattering off atomic nuclei. This fundamental process was predicted several ...decades ago by the Standard Model of electroweak interactions but has not been discovered yet. The RED-100 is a two-phase emission xenon detector containing ∼200 kg of the liquid Xe (∼ 100 kg of that is in a fiducial volume). One of the possible sites to carry out the experiment is the SNS (Spallation Neutron Source) facility at Oak Ridge National Laboratory, USA. SNS is the world's most intense pulsed source of neutrinos and unique place to study neutrino properties. The energy spectrum of neutrinos produced at the SNS extends up to ∼ 50 MeV and satisfies coherence condition. These neutrinos give kinetic energies of Xe recoils up to a few tens of keV where the response of nuclear recoils is well-known from neutron calibrations of dark matter detectors. The detector will be deployed in the basement under the experimental hall at a distance of ∼30 meters from the SNS target. The expected signal and background (neutron and gamma) are estimated for this specific location. The detector details, current status and future plans are provided.
A computer model of operation of Hamamatsu R11410-20 photomultiplier based on SPICE software package has been developed. The PMT amplification process is simulated with the use of voltage and current ...controlled sources of current. Boundaries of linear zone were obtained for high anode current (with respect to the base current) operation regime. The results of simulation are in reasonable agreement with the experimentally measured PMT characteristics. The model can be used for simulation of any type of PMT.
A laboratory experimental setup based on an electroluminescent chamber with gaseous xenon at room temperature and a pressure of 6 atm is described. It is used in the educational process to study ...electroluminescence used as a method for the detection of an registering an ionization signal. With the example of α-particles, the formation of an electroluminescent signal formed when a charge produced in the process of ionization moves in a strong electric field and its dependence on the magnitude of the field are studied. It is clearly shown that the time profiles of light and electrical signals almost completely coincide with each other.
The system for forming a trigger for the RED-100 liquid xenon detector has been developed. The trigger can be generated for all types of events required to calibrate the detector and data ...acquisition, including events with one ionization electron. The system has an event detection mechanism where each event is assigned with the timestamp and event type. The trigger system is required in the systems searching for rare events to keep only the necessary information from the ADC array. The characteristics and implementation of the trigger system that provides high efficiency operation even at low-energy events have been described.
We studied the application of statistical reconstruction algorithms, namely maximum likelihood and least squares methods, to the problem of event reconstruction in a dual phase liquid xenon detector. ...An iterative method was developed for in-situ reconstruction of the PMT light response functions from calibration data taken with an uncollimated γ -ray source. Using the techniques described, the performance of the ZEPLIN-III dark matter detector was studied for 122 keV γ-rays. For the inner part of the detector ( R <; 100 mm) , spatial resolutions of 13 mm and 1.6 mm FWHM were measured in the horizontal plane for primary and secondary scintillation, respectively. An energy resolution of 8.1% FWHM was achieved at that energy. The possibility of using this technique for improving performance and reducing cost of scintillation cameras for medical applications is currently under study.
The RED100 two-phase liquid xenon emission detector for neutrino coherent scattering experiments is equipped with 38 Hamamatsu R11410-20 photomultiplier tubes capable to operate at cryogenic ...temperatures and made of low background materials. A dedicated characterization procedure has been carried out for each PMT unit to be installed into the detector. The results presented here include single photoelectron analysis, gain curves for a wide range of the bias voltage values, data on dark count rate for 34 PMT samples. Peculiar noise characteristics of selected PMT units are analysed and discussed.
A procedure for spark-discharge purification of a liquid xenon sample with a mass of 55 kg is described. The average lifetime of ionization electrons before capture by electronegative impurities in ...liquid xenon increased from ≤ 0.1 μs to ≥ 50 μs for an electric field of 50–500 V/cm as a result of the procedure. The xenon purified with this method is intended for use in the RED-100 detector for observation of the process of coherent elastic neutrino scattering off xenon nuclei.
—
A combined passive shield of the RED-100 two-phase emission neutrino detector has been developed and built for suppressing the background of external γ rays and neutrons. The shield is composed of ...a 5‑cm-thick copper layer (the inner layer is adjacent to the detector) and a water layer with a total thickness of approximately 70 cm (including the water inside the copper shield). The Monte Carlo simulation of the shielding efficiency has been performed. The obtained attenuation factor of the copper shield for the γ-ray background has been experimentally verified in a laboratory test using a NaI(Tl) scintillator detector. The γ‑ray background rejection factor of the full shield has also been calculated.
PDF
