RU-2861603-C1 - SCINTILLATION DETECTOR

RU2861603C1RU 2861603 C1RU2861603 C1RU 2861603C1RU-2861603-C1

Abstract

FIELD: detection of ionising radiation. SUBSTANCE: detector intended for detecting ionising radiation, placed in a cryogenic volume at liquid nitrogen temperature, comprises a CsI(pure) scintillator and two silicon photomultipliers (SiPMs). All surfaces of the CsI(pure) scintillator are covered with a two-component wavelength-shifting composition of POPOP and PTP in a 4:1 ratio, capable of re-emitting the light of the CsI(pure) scintillator from the ultraviolet to the visible region of the spectrum, and a reflector made of Teflon tape. EFFECT: increasing the efficiency of light collection from the CsI(pure) scintillator and reducing the energy threshold for signal detection below 500 eV. 1 cl, 6 dwg

Inventors

BARANOV ALEKSANDR GENNADEVICH
Ivashkin Aleksandr Pavlovich
Musin Sultan Askhatovich
Strizhak Aleksandr Olegovich

Dates

Publication Date: 20260506
Application Date: 20251115

Claims (1)

A detector designed for recording ionizing radiation, placed in a cryogenic volume at the temperature of liquid nitrogen, containing a CsI(pure) scintillator and two silicon photomultipliers SiPM, characterized in that all surfaces of the CsI(pure) scintillator are coated with a wavelength-shifting two-component composition of POPOP and PTP in a 4:1 ratio with the ability to re-emit light from the CsI(pure) scintillator from the ultraviolet to the visible region of the spectrum and a reflector made of Teflon tape.

Description

AREA OF TECHNOLOGY The invention relates to highly efficient scintillation detectors of ionizing radiation with an ultra-low energy-release detection threshold and can be used in atomic, nuclear, and particle physics to detect low-energy neutrinos. Typically, such devices employ either low-mass, low-efficiency semiconductor detectors or inorganic scintillators with signal acquisition by classic photomultiplier tubes (PMTs) or silicon photomultipliers (SiPMs). The most promising are relatively large-volume CsI(pure) scintillators, which have a light yield exceeding 100 photons/keV at cryogenic temperatures and provide a neutrino detection threshold below 1 keV. Standard photomultiplier tubes have relatively low quantum efficiency and are unable to operate at the 77 K temperature of liquid nitrogen. Therefore, silicon photomultipliers with a quantum efficiency of approximately 50% in the blue spectrum are used to collect the light signal from the CsI(pure) scintillator. The main challenges of such detectors include the thermal noise of the SiPM, the need to detect scintillator radiation in the hard ultraviolet region, and high light collection efficiency, ensuring an energy detection threshold below 1 keV. LEVEL OF TECHNOLOGY Technical solution RU 2 225 017 C2 is known - A METHOD FOR DIFFERENTIAL STABILIZATION OF THE SPECTROMETRIC PATTERN OF A SCINTILLATION UNIT FOR DETECTING GAMMA RADIATION USING A REFERENCE PEAK. The patent describes a scintillation detector based on a NaI(Tl) scintillator and a photomultiplier tube (PMT) and a method for reducing the detection threshold to 15 keV by analyzing the detector signal. The SC-MacroPixel-MCA gamma-ray detector, manufactured by CapeScint (USA), is also known (https://capescint.com/wp-content/uploads/Scintillation-Probe-SC-MacroPixel-MCA-Datasheet.pdf). This detector consists of a single SrI2 (Eu) scintillator measuring 14x14x25.4 mm3 and an array of four silicon photomultipliers. The declared energy detection threshold is 10 keV. This relatively low detection threshold is ensured by the light output of the SrI2(Eu) scintillator above 100 photons/keV and the small size of the scintillator, which ensures the best light collection. A disadvantage of this device is the thermal noise of the photodiode array, which does not allow the detection threshold to be reduced below 10 keV. The technical solutions closest to those discussed in this patent are presented in the paper https://doi.org/10.1140/epjc/s10052-024-12800-y, which discusses a prototype neutrino detector made from a large cubic CsI(pure) scintillator measuring 50x50x50 mm3, with signal acquisition by two SiPM matrices placed on opposite faces of the scintillator. This detector was housed in a cryogenic volume with a temperature of 77 K. Since the emission spectrum of this scintillator lay in the ultraviolet region, where the quantum efficiency of SiPM is quite low, a wavelength-shifting compound (TRV) was used, coating the surfaces of the SiPM matrices. However, the scintillator surfaces themselves were not coated with a wavelength-shifting compound. Since the SiPM matrices in this detector operated at an extremely high supply voltage, the resulting signal amplitude reached 123 photoelectrons/keV. However, the main contribution to this amplitude was due to the parasitic effect of optical coupling between the SiPM pixels. The corrected light collection was several times lower, reaching 30 photoelectrons/keV. At the nominal supply voltage, the light collection was 20.9 photoelectrons/keV, within a fairly large error of 3 photoelectrons. It should be noted that the scintillator light collection scheme used required the placement of photodetectors with large active areas on opposite sides of the scintillator, resulting in high thermal noise. This noise was further increased by the use of an extremely high supply voltage for the SiPM. As noted in this paper, the thermal noise of the photodetectors limits the sensitivity and detection threshold of this detector. DISCLOSURE OF THE ESSENCE OF THE INVENTION The problem that the claimed invention is aimed at solving is the creation of a highly efficient detector of ionizing radiation with an energy detection threshold below 500 eV. The technical result consists in increasing the efficiency of light collection from a CsI(pure) scintillator and reducing the energy threshold for registering signals below 500 eV. The technical result is achieved in that in a detector intended for recording ionizing radiation, placed in a cryogenic volume at the temperature of liquid nitrogen, containing a CsI(pure) scintillator and two silicon photomultipliers SiPM, what is new is that all surfaces of the CsI(pure) scintillator are coated with a wavelength-shifting two-component composition of POPOP and PTP in a ratio of 4:1 with the ability to re-emit light from the CsI(pure) scintillator from the ultraviolet to the visible region of the spectrum, and a reflector made of Teflon tape. The