В статье демонстрируется работа модели компактного калибровочного источника нейтронов, который может быть использован для калибровки и определения функции отклика детекторов темной материи и детекторов электронных антинейтрино. Рассматриваемый калибровочный источник нейтронов представляет собой комбинацию радионуклида \({}^{252}\) Cf, который испытывает спонтанное деление с образованием нейтронов, и оригинального кремниевого полупроводникового детектора. Последний обеспечивает временную привязку к моменту образования нейтронов путем регистрации сигналов от осколков деления.

Operation of a model of a compact neutron source that can be used to calibrate dark-matter and electron-antineutrino detectors and to determine their response functions is demonstrated. The calibration neutron source in question is a combination of the ^252 Cf radionuclide, which undergoes spontaneous fission, producing neutrons, and an original silicon semiconductor detector. The latter provides a time reference for the neutron-emission instant by recording signals from fission fragments.

We present a description of the originally developed ������-spectrometer consisting of two Si(Li)-detectors with sensitive area thickness above 8 mm and 4 ������-geometry. The full absorption spectrometer allows for direct measurements of ������-spectra, disregarding the corrections to response function induced by the electron backscattering from the crystal surface. In case of ������-spectra of transitions to the excited state of the daughter isotope additional 3 & DPRIME;BGO-detector is used in order to detect the ������-quanta in coincidence with the pair of Si(Li)-spectrometers.

Точное измерение бета-спектров всегда имело большое значение в некоторых фундаментальных физических задачах, включая физику нейтрино. В этой работе мы представляем результаты измерения спектра источника \({}^{144}\) Ce– \({}^{144}\) Pr, выполненного с помощью установок двух типов с точностью, которая была существенно увеличена по сравнению с предыдущими исследованиями. Корректность теоретической подгонки была проверена формой разрешенного бета-перехода \({}^{144}\) Pr (0 \({}^{-}\) ) \(\to{}^{144}\) Nd (1 \({}^{-}\) ).

Precise measurement of beta spectra was always of great importance in some fundamental problems, including those of neutrino physics. The results obtained by measuring the spectrum of a Ce-144-Pr-144 source with setups of two types to a precision substantially improved in relation to earlier investigations are presented. The correctness of a theoretical fit is tested using the shape of the Pr-144 (0(-)) -> Nd-144 (1(-)) allowed beta transition.

Precise measurement of beta spectra was always of great importance in some fundamental problems, including those of neutrino physics. The results obtained by measuring the spectrum of a ^144 Ce– ^144 Pr source with setups of two types to a precision substantially improved in relation to earlier investigations are presented. The correctness of a theoretical fit is tested using the shape of the ^144 Pr (0 ^- ) →^144 Nd (1 ^- ) allowed beta transition.

A 4π β spectrometer consists of two Si(Li) detectors with a sensitive region that is more than 8-mm thick. Using this total-absorption spectrometer it is possible to make a direct measurement of β spectra without correcting the response function for the electron backscattering from the crystal surface. The β spectra of transitions to the excited states of daughter nuclei have been measured using an additional 3'' BGO detector of γ rays, which is connected in coincidence with the pair of Si(Li) detectors.

A spectrometer based on a Si(Li) detector has been tested by exposure to α particles with the aim of determining changes in the detector characteristics versus the fluence. As a result of 60-day measurements with a total fluence of 6.2 × 109 α particles, it has been established that the dependence of the deterioration in the energy resolution of α-particle peaks on the fluence is described by a linear function with a slope of Δσ/ΔФ = (8.4 ± 0.4) × 10–10 keV/α. The measured amplitude of the α-particle momentum decreases linearly with increasing fluence with a slope of (–4.8 ± 0.6) × 10–9 keV/α. These effects do not prevent reliable discrimination between the signals from α particles and fission fragments until the fluence reaches a value of 1010 α particles when the Si(Li) detector is a part of a neutron source for detecting fission fragments.

Present work reports the results of activities intended to reach thin Si(Li) detector entrance window on the diffusive lithium layer side. It was established that the new n-contact represented by a heterostructure of unalloyed amorphous n-type silicon a-Si:H allows one to achieve the entrance window thickness 3 = 4 orders of magnitude smaller than the lithium-side entrance window of standard Si(Li) detectors. The films of amorphous silicon were synthesized with MASD (magnetron assisted silane decomposition) method in mixture of SiH4 (25%) and Ar (75%) gases. Lithium layer surface resistivity and silicon target type (n- or p-) affection on electrical properties of Si(Li) detector contact produced were studied. The investigation performed had led to a technology of Si(Li) detector production with thickness of the entrance window on the diffusive lithium layer side below 0.1 mu m.

The characteristics of a beta spectrometer that consists of a total-absorption Si(Li) detector and a drift Si detector are presented. Using this spectrometer, it is possible to efficiently separate β radiation of nuclei from concomitant X and γ rays. The method is based on coincidences between signals from the thick and thin detectors. The spectrometer can be used to precisely measure the shape of the β spectra of various radioactive nuclei, in particular, of the 144Pr nucleus, which is the most promising antineutrino source for searching for neutrino oscillations into a sterile state.

Here we present the specifications of a newly developed beta-spectrometer, based on full absorption Si(Li) detector and thin transmission detector, allowing one to perform efficient separation beta-radiation and accompanying X-rays and gamma radiation. Our method is based on registration of coincident events from both detectors. The spectrometer can be used for precision measurements of various beta-spectra, namely for the beta-spectrum shape study of Pr-144, which is considered to be an advantageous anti-neutrino source for sterile neutrino searches.