(SVD-2 Collaboration) A. G. Afonin, E. N. Ardashev, V. F. Golovkin, S. N. Golovnya, S. A. Gorokhov, A. A. Kiryakov, A. G. Kholodenko, V. V. Konstantinov, L. L. Kurchaninov, I. S. Lobanov, E. V. Lobanova, G. A. Mitrofanov, V. S. Petrov, A. V. Pleskach, M. K. Polkovnikov, V. N. Riadovikov*, V. N. Ronzhin, V. A. Senko,N. A. Shalanda, M. M. Soldatov, Yu. P. Tsyupa, A. P. Vorobiev, V. I. Yakimchuk, and V. N. Zapolskii∗ IHEP, Protvino, Moscow region, Russia.

The general architecture and characteristics of the readout electronic system for the vertex detector of the SVD-2 setup at the U-70 accelerator (Kurchatov Institute NRC−IHEP, Protvino) are presented. The SVD-2 setup is intended to study near-threshold charmed-particle production at energies of 50–70 GeV, as well as many-particle processes and collective behavior of particles. The key characteristics of the electronic modules developed for the SVD setup by the Kurchatov Institute NRC−IHEP are briefly described.

The results of an analysis of data from the SERP-Е-184 experiment devoted to studying mechanisms of the production of charmed particles in proton–nucleus interactions at 70 GeV and their decays are presented. The data in question were obtained upon irradiating the SVD-2 active target consisting of carbon, silicon, and lead plates with a beam of 70-GeV protons. A detailed simulation on the basis of the FRITIOF7.02 and GEANT3.21 code packages made it possible to optimize event-selection criteria and to calculate the detection efficiency for Λ c + baryons. After selecting a signal from the threebody decay of a Λ c + baryon, the inclusive cross section for its production at near-threshold energies, its lifetime, and the parameter of the A dependence of the cross section were found. The Λ c + -baryon yields are tabulated along with data from other experiments and theoretical predictions.

Описана конструкция калориметра мягких фотонов установки СВД-2. Апертура прибора 210 × 210 мм. Приведены первые результаты его испытания в ходе физического набора статистики в эксперименте E-190 на ускорителе У-70 ИФВЭ.

The design of the soft photon calorimeter for the SVD-2 experiment is described. The aperture of the calorimeter is 210 × 210 mm. The first results of its testing in the course of data acquisition in the E-190 experiment at the U-70 accelerator of the Institute for High Energy Physics are presented.

The stages of development and the current status of the versatile “Spectrometer with a Vertex Detector” setup designed for physics experiments at the U-70 accelerator of the Institute for High Energy Physics (Protvino) is described. The main detectors of the setup are the vertex detector based on silicon microstrip detectors, the wide-aperture magnetic spectrometer based on multiwire proportional chambers, and the lead-glass hodoscope γ detector. In the setup, there is a fast two-level trigger system for selecting required particle interactions. The key characteristics of the setup systems are presented, and the physical results obtained on it are briefly listed.

The stages of development and the current status of the versatile “Spectrometer with a Vertex Detector” setup designed for physics experiments at the U 70 accelerator of the Institute for High Energy Physics (Protvino) is described. The main detectors of the setup are the vertex detector based on silicon microstrip detectors, the wide aperture magnetic spectrometer based on multiwire proportional chambers, and the lead glass hodoscope γ detector. In the setup, there is a fast two level trigger system for selecting required particle interactions. The key characteristics of the setup systems are presented, and the physical results obtained on it are briefly listed. DOI: 10.1134/S0020441212060012

Описаны этапы развития и современное состояние многоцелевой установки “Спектрометр с вершинным детектором”, созданной для проведения физических экспериментов на ускорителе У-70 Института физики высоких энергий (Протвино). Основными детекторами установки являются: вершинный детектор на основе кремниевых микростриповых детекторов, широкоапертурный магнитный спектрометр на основе пропорциональных камер, годоскопический детектор -квантов, собранный из свинцовых стекол. Для отбора нужных взаимодействий частиц в установке имеется быстродействующая двухуровневая система запуска. Приведены основные характеристики созданных систем установки, кратко перечислены полученные физические результаты.

The widely growing interest to the digital diagnostics and analysis systems, that have many advantages in comparison with the traditional (film) systems, in data taking, data storing, and data transmitting, requires a new detection technology. One of the most promising system for medical radiography today is a scanning type apparatus with some linear array detectors. The constructed apparatus is a device with some semiconductor GaAs detectors as sensitive elements to form the image while scanning an object. GaAs detectors are the detectors of the direct transformation of X-ray radiation into the electrical. The present paper describes the results of the construction and testing of the portable X-ray unit for traumatic examination and orthopedic manipulation in stationer clinics and at the first aid in medicine of catastrophe.

Описывается прецизионный вершинный микростриповый детектор, созданный для установки “Спектрометр с вершинным детектором”, на которой исследуются свойства адронов и короткоживущих нестабильных частиц на ускорителе ГНЦ “Институт физики высоких энергий”. Приведены структура, конструкция и технология изготовления основных компонентов детектора – микростриповых сенсоров и активной мишени; описываются также электроника съема и регистрации сигналов, система сбора данных и ее программное обеспечение. Точность определения положения вершин составляет 70–250 мкм вдоль оси пучка и 8–15 мкм – поперек оси при быстродействии 500–1000 событий/с.

A precision vertex microstrip detector has been developed for the spectrometer with a vertex detector (SVD) setup on which the properties of hadrons and short-lived unstable particles are investigated on the accelerator of the Institute for High Energy Physics. The structure and the design of the main detector components—microstrip sensors and an active target—are presented, as well as techniques for manufacturing them. The readout electronics, the data acquisition system, and its software are also described. The accuracy in determining the vertex position is 70–250 µm along the beam axis and 8–15 µm in a transverse direction at a throughput of 500–1000 events/s.

The design and technology of the silicon strip detector modules for the Semiconductor Tracker (SCT) of the ATLAS experiment have been finalised in the last several years. Integral to this process has been the measurement and verification of the tracking performance of the different module types in test beams at the CERN SPS and the KEK PS. Tests have been performed to explore the module performance under various operating conditions including detector bias voltage, magnetic field, incidence angle, and state of irradiation up to 3×1014 protons per square centimetre. A particular emphasis has been the understanding of the operational consequences of the binary readout scheme.

Data from the SVD-2 experiment that were obtained at the IHEP accelerator in 70-GeV/c proton-nucleus interactions are analyzed with the aim of searches for an exotic Θ+ baryon that decays through the pK S 0 channel. The reaction pN → pK S 0 + X characterized by a bounded multiplicity of charged secondaries is used for this analysis. A resonance of mass M = 1526 ± 3(stat.) ± 3(syst.) MeV/c2 and width Γ < 24 MeV/c2 is observed in the invariant-mass spectrum of the pK S 0 system at a statistical significance of 5.6σ. The mass and the width of this resonance correspond to the recently found positive-strangeness Θ+ baryon, which was predicted to be an exotic baryon consisting of five quarks (pentaquark), \(uudd\bar s\). The total cross section for the production of a Θ+ baryon in pA interactions is estimated at a value within the range 30–120 μb for xF ≥ 0. An analysis of the A dependence of the cross section for Θ+-baryon production does not reveal a significant deviation from the A dependence for inelastic events (∼A0.7).

A first-level trigger system for the SVD-2 setup, based on an active target and a scintillation hodoscope, is described. The implementation of the table method for data selection in the trigger system is presented. The good performance of the first-level trigger system was demonstrated in the testing run of the Serpukhov accelerator in 1999.

Charmed-particle production in pp interactions at 70 GeV/c was studied with the SVD setup at the IHEP accelerator (Protvino). The experimental procedure used and the data-selection methods are described. Data obtained by using a quickly cycling bubble chamber and a magnetic spectrometer are analyzed. The number of inelastic-interaction events recorded in the chamber is 109000, with the charge multiplicity being nch/4. The corresponding statistics are 4.96 event/µb. Part of the events were recorded in the magnetic spectrometer. Three three-prong decays of charged particles near the primary vertex are found on the films, two of these being recorded with the spectrometer. All three are interpreted as D− decays. Two neutral decays observed simultaneously in the chamber and in the spectrometer are interpreted as \(\bar D^0 \) decays. The total cross section for \(c\bar c\) production in the Feynman variable region −1<xF<+1 is estimated at \(\sigma (c\bar c) = 1.6_{ - 0.7}^{ + 1.1} (stat.) \pm 0.3(syst.)\mu b\). The cross-section values and the mean values 〈|xF|〉 and 〈p⊥〉 for D mesons are compared with other experimental results in the energy range 58–800 GeV. The data of this experiment are compatible with the cross-section estimates obtained in the beam-dump experiment at 70 GeV and with those predicted by perturbative QCD.