Ivan Tolstukhin

RED-100 detector for the first observation of the elastic coherent neutrino scattering off xenon nuclei

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 worlds 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.

The RED-100 two-phase emission detector

The RED-100 experimental setup, which is designed to detect elastic coherent neutrino scattering off xenon nuclei, is described. One specific feature of this setup is the possibility of using it in above ground experiments. The setup is based on the RED-100 two-phase emission detector in which liquid xenon is used as a working medium for detection of rare events. The results of the technical run with the setup are presented. These are the evidence of the normal operation of all systems and the readiness of the setup for carrying out an experiment.

Recording of relativistic particles in thin scintillators

Results of investigating an assembly of thin scintillators and silicon photomultipliers for registering relativistic particles with the minimum ionization are presented. A high efficiency of registering relativistic particles using an Ej-212 plastic scintillator, BSF-91A wavelength-shifting fiber (Saint-Gobain), and a silicon photomultiplier (Hamamtsu) is shown. The measurement results are used for creating a scintillation hodoscope of the magnetic spectrometer for registering γ quanta in the GlueX experiment.

Performance of the pair spectrometer of the GlueX experiment

The description of the pair spectrometer of the GlueX detector at Jefferson Lab and its performance during the first beam commissioning runs are presented. We measured the amount of light collected from each channel of the pair spectrometer hodoscopes and the time resolution of the pair spectrometer counters.

Thermostatting of the RED-100 liquid-xenon emission detector

The thermal stabilization system of the RED-100 liquid-xenon two-phase emission detector for the experiment aimed at detecting the effect of coherent neutrino scattering off xenon nuclei has been tested. The system is based on thermosyphons (closed two-phase heat pipes) that are filled with nitrogen and use liquid nitrogen boiling at atmospheric pressure as a cooler. The system is capable of keeping the working medium of the RED-100 detector at a temperature of 167 K with a precision of <1 K.

Time characteristics of silicon photomultipliers used in the GlueX experiment

The GlueX detector in Hall D at Jefferson Lab is instrumented with about 5000 Silicon Photomultipliers (SiPM) manufactured by Hamamatsu Corporation. Silicon photomultipliers with a sensitive area of 3×3 mm2 are used to detect light from scintillator detectors such as: the tagger microscope, pair spectrometer, and start counter. An array of 4×4 SiPM sensors was specially designed by Hamamatsu for the instrumentation of the barrel electromagnetic calorimeter. SiPMs in the tagger microscope and start counter will be operated at a relatively large rate of up to 2 MHz. We performed measurements of the time resolution for different SiPM operation rates and estimated the SiPM recovery time. Time characteristics were compared for sensors with two pixel sizes: 25 μm (MPPC S10362-33-025C, MPPC S10931-025P) and 50 μm (MPPC S10362-33-050C, MPPC S10931-050P). Time resolution of the SiPM array (MPPC S12045) was measured as a function of light for several SiPM temperatures. Studies were performed using a picoseconds laser light pulser and a light-emitting diode.