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Vol 86, No 6 (2023)
Articles
Investigation of (γ,α) Reactions on Natural Tantalum
Abstract
The study presents the results of the yield analysis of a promising medical radioisotope 177Lu in (γ,α) reactions upon irradiation of natural tantalum with electron bremsstrahlung with boundary energies of 37, 40, and 55 MeV. The experimental yields are compared with the results of calculations based on the collective model of the nucleus. The isomeric ratio of the yield for 177mgLu was determined.
641-646
ИЗМЕРЕНИЯ МЮОНОВ В ШАЛ СВЕРХВЫСОКИХ ЭНЕРГИЙ ПО ДАННЫМ ЯКУТСКОЙ УСТАНОВКИ И ЭКСПЕРИМЕНТА ОЖЕ
Abstract
Рассмотрены результаты прямых измерений плотности мюонов в широких атмосферных ливнях (ШАЛ) с зенитными углами \(\theta\leqslant 45^{\circ}\) и энергиями \(E_{0}\geqslant 10^{17}\) эВ, полученных в эксперименте Оже и на Якутской установке. Мюоны в обоих случаях регистрировались подземными сцинтилляционными детекторами с одинаковой пороговой энергией \(E_{\mu}\approx 1.0\sec\theta\) ГэВ. Измеренные величины сравниваются с теоретическими значениями, вычисленными по модели развития ШАЛ QGSJET-II-04 из пакета программ CORSIKA. Они различаются между собой в \(1.53\pm 0.13\)(stat). Показано, что это различие обусловлено завышенной в 1.22 раза плотностью мюонов и заниженной в 1.25 раза первичной энергией в эксперименте Оже.
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New Possibilities for pp-Cycle Solar Neutrino Registration by Use of Indium Detector
Abstract
Low background segmented liquid scintillator detector, doped with an indium as a target for solar neutrino registration, can be used for measuring total solar neutrino spectrum including pp neutrinos.
A detector consisting of small modules filled with liquid scintillator in the volume of 1–2 L is considered. Silicon matrices are used for light collection. The background of indium beta-activity is suppressed by
triple coincidences. The detector of such a type can measure 7Be neutrino flux
656-663
Study of the Process e+e− → − ηγ →7 γ in the Energy Range √ s = 1.07−2 GeV
Abstract
The e+e− → ηγ cross section is measured in the center-of-mass energy range from 1.07 to 2.00 GeV in the decay channel η → 3π0, π0 → γγ. The data set with an integrated luminosity of 242 pb−1
accumulated in the experiment with the SND detector at the VEPP-2000 e+e− collider is analyzed.
664-671
Measuring the Neutron Timelike Electromagnetic Form Factor with the SND Detector
Abstract
Results are presented from measuring the e+e− → n¯n cross section and effective neutron timelike form factor. Data are collected in 2020–2021 at the VEPP-2000 e+e− collider in the 1891 to 2007 MeV center-of-mass range of energies. The general purpose nonmagnetic SND detector is used to detect neutron–antineutron events. The time-of-flight approach is used to select n¯n events. The measured
cross section is 0.4–0.6 nbn. The neutron form factor in the investigated range of energies varies from 0.3 to 0.2.
672-680
ИЗМЕРЕНИЕ ДЕЙТРОННЫХ АНАЛИЗИРУЮЩИХ СПОСОБНОСТЕЙ Ay, Ayy И Axx В dp-УПРУГОМ РАССЕЯНИИ НА НУКЛОТРОНЕ
Abstract
Представлены результаты векторной Ay и тензорных Ayy и Axx анализирующих способностей в упругом дейтрон-протонном рассеянии при больших поперечных импульсах. Эти данные были получены на внутренней мишени Нуклотрона ОИЯИ в диапазоне энергий 400–1800 МэВ с использованием пучка поляризованных дейтронов от нового источника поляризованных ионов. Новые данные по дейтронным анализирующим способностям в широком энергетическом диапазоне демонстрируют чувствительность спиновой структуры изоскалярных нуклон-нуклонных корреляций на малых расстояниях.
681-685
Deuteron Beam Vector Polarization Measurement Using Proton–Proton Quasielastic Scattering at the Energies of 500 and 650 MeV/nucleon
Abstract
The deuteron beam vector polarization is obtained at the Nuclotron Internal Target Station using quasielastic proton–proton scattering on the polyethylene target. The selection of useful events is performed using the time and amplitude information from scintillation counters. The asymmetry on the hydrogen is obtained by the subtraction of the carbon background. The values of vector polarization are obtained at the beam energies of 500 and 650 MeV/nucleon. The obtained values are compared with the data obtained in the deuteron–proton elastic scattering at the beam energy of 135 MeV/nucleon.
686-690
On the Importance of Inelastic Interactions in Direct Dark Matter Searches
Abstract
The approach proposed earlier for describing the scattering of weakly interacting nonrelativistic massive neutral particles off nuclei is used as the basis to derive explicit expressions for the event counting
rate expected in experiments aimed at directly detecting dark matter (DM) particles. These expressions make it possible to estimate the rates in question with allowance for both elastic (coherent) and inelastic (incoherent) channels of DM particle interaction with a target nucleus. Within this approach, the effect of a nonzero excitation energy of the nucleus involved is taken into account for the first time in calculating the contribution of inelastic processes. A correlation between the excitation energy and admissible values of the kinetic recoil energy of the excited nucleus constrains substantially the possibility of detection of the inelastic channel with some nuclei. In addition to the standard model of the DM distribution in the
MilkyWay Galaxy, the effect of some other models that allow significantly higher velocities of DMparticles is considered. A smooth transition from from the dominance of the elastic channel of the DM particle–nucleus interaction to the dominance of its inelastic channel occurs as the nuclear recoil energy TA grows. If the DM detector used is tuned to detecting elastic-scattering events exclusively, then it cannot detect anything in the casewhere the nuclear recoil energy turns out to be belowthe the detection threshold. As TA grows, such a detector loses the ability to see anything, since elastic processes quickly become nonexistent. Radiation associated with the deexcitation of the nucleus becomes the only possible signature of the interaction that occurred. In the case of a spin-independent interaction, the inelastic contribution becomes dominant rather quickly as TA grows, while the differential event counting rate decreases insignificantly. If a DMparticle interacts with nucleons via a spin-dependent coupling exclusively, detectors traditionally set
up to detect an elastic spin-dependent DMsignal will be unable to to see anything since the signal entirely goes through the inelastic channel. It looks like the sought interactions ofDM particles may have a sizable intensity, but the instrument is unable to detect them.
Therefore, experiments aimed at directly detecting DM particles should be planned in such a way that it would be possible to detect simultaneously two signals—that of the recoil energy of the nucleus involved and that of gamma rays having a specific energy and carrying away its excitation. A experiment in this implementation will furnish complete information about the DM interaction that occurred.
691-726
Connection between the Dipole Polarizabilities of Charged and Neutral π-Mesons
Abstract
In light of the contribution of the states with isospin I = 0in the difference of the amplitudes of the processes γγ → π+π− and 0 being very small, the dispersion sum rules for the difference between
the dipole polarizabilities of the charged and neutral pions are analyzed as a function of the σ meson’s parameters. Using the value of the chiral theory of perturbations for (α1 − β1)π0 = −1.9, (α1 − β1)π± =9.4−8.2 is found for the σ meson parameter within the region mσ = 400−550 MeV, Γσ = 400−600 MeV, Γσ→γγ = 0−3 keV. Estimated optimum value of decay width σ → γγ yields Γσ→γγ 0.7 keV.
727-734
Is It Possible to Estimate the Parameters of the 2D Evolution of the Space Metric Signature with Energy from the Correlations of the Azimuthal Characteristics of Particles?
Abstract
The coplanarity of subcores in γ-ray–hadron families of the so-called long-range near-side “ridge” effect discovered by the CMS Collaboration at the LHC can be described in terms of the FANSY
2.0 model, which reproduces the coplanar generation of the most energetic particles in hadron interactions at superhigh energies. Coplanar generation can be explained, in particular, by the hypothesis of change of the signature of the metric of the space–time continuum, namely, a fluctuation transformation of the basic
three-dimensional state into two-dimensional one (3D ↔ 2D). A method is proposed for experimental verification of this hypothesis by studying the azimuthal correlations of different particles in hadron
interactions.
735-741
Metal-Loading Liquid Organic Scintillators for Recording Rare Events: Light Yield at High Metal Concentration
Abstract
Metal-loading liquid organic scintillators (MeLS) are discussed from the point of view of light yield at high metal loading (Gd, Nd, Zr, In). It is shown that, when metal β-diketonates are introduced into the scintillator, its light yield is always lower than when carboxylates are used, which is explained by the structural difference between these complexes. The nature of the metal in some cases (Nd) also affects
the light attenuation length and, consequently, the MeLS light yield. The composition of the solvent (the fraction of aromatics in the main solvent) and the degree of purification of the introduced metal complex also have a significant effect on the light yield.
742-751
Latest Results on the Search of Dark Photons with a Multicathode Counter
Abstract
The method of measurements is described that has been performed using a multicathode counter with an iron cathode. The aim of experiment was to search for diurnal variations of the count
rate of single electrons emitted from the surface of the cathode by the conversion of dark photons on its surface. The results obtained during 160 days of measurements are presented.
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