S.P. Chernenko

X-ray detectors for structure investigations constructed at JINR

Abstract The performance characteristics of a few high resolution position-sensitive detectors constructed at JINR are presented. The detectors supplied with original software operate with an IBM PC/AT. One of these devices has been succesfully applied for protein molecule structure investigations and the other for studies of the structure-forming process during combustion. The preliminary parameters of the high count rate MWPC with parallel electronics and the testing results of the microstrip detector are given.

Development and application of a multistep chamber for digital radiochromatography imaging

Abstract A device based on multistep chamber has been developed for high-sensitive automation express-analysis of flat radiochromatograms and electrophoregrams. The device operated on-line with an SM-4 computer. The spatial resolution for β detection from 14 C, 35 S and 32 P radionuclides and for X-ray detection from 125 I is not worse than 1 mm. Analyzing the samples, radioactive spots are localized and their relative activity is measured. The time of analyzing the 160×160 mm 2 samples is not larger than 30 min. The device possesses high stability and the reproducibility of measurement results.

Test results of the parallax-free X-ray area detector SD-1000 in the diffractometer CARD-7

Abstract A parallax-free X-ray area detector with a spherical Be-window has been tested in a diffractometer. The detector provides a DQE of ∼80% (8–17 keV), a parallax-free solid angle of 50°, and accuracies of 1% for the intensity and of 0.025° for the angle.

A Position-Sensitive Detector for the Polarized-Neutron Spectrometer

A linear detector of thermal neutrons, developed at the Laboratory for High Energies (Joint Institute for Nuclear Research), is used in the polarized-neutron spectrometer of the ИБР-2 reactor (JINR). The data are acquired in the regime of frame-by-frame survey to select neutrons with a wavelength λ = 1–12 Å by the time of flight. The neutron-detection efficiency is ∼ 70% for a wavelength of 2 Å. The detector exhibits a low sensitivity to γ-rays, a differential nonlinearity of ∼1.5%, and a spatial resolution of ∼1.5 mm at counting rates of ∼105events/s.

Automatized One-dimensional X-Ray-Detector

One-dimensional gas-filled X-ray detectors with delay line readout have been developed and tested on line with IBM-PC. The pressure of a xenon (90) and CH4 (10) mixture can be set over a range of 1–10 atm. The position resolution for 8 keV photons is about 170 μm. Main properties and possible applications of the detector are presented.

Parallax-free X-ray area detector with high spatial resolution

The new parallax-free X-ray 2D detector (SD-1000) with the pixel array of 1024 × 1024 has been designed and tested. This detector is the basic element of the X-ray diffractometer which is constructed for the investigation of biological macromolecules, viruses, liquid crystals and powders. The first test results are presented.

Development and investigation of a neutron radiography imaging system with a low-pressure multistep chamber

An imaging system of thermal neutrons for an investigation of digital neutron radiography has been developed and tested. Some characteristics obtained on a neutron radiography beam of an experimental reactor are reported. The coordinates of each event are determined in this system. After processing in a LSI 1123 computer, a radiograph, accumulated in a histogramming memory of 64 K 16-bit words, is presented on a colour display. A 230 × 180 mm2 low-pressure multistep chamber is used as a detector. Neutron conversion takes place in a 6 μm boron layer enriched to 86% in 10B. The detection efficiency of thermal neutrons is no less than 3%. The count rate of the system reaches up to 2 × 105 events per second. A radiograph can be obtained within 10 minutes. The sensitivity of this system to gamma-background is low. One event/s is detected for a background of 1 R/h. The spatial resolution is found to be 0.7 mm (FWHM) using a cadmium knife edge. The integral nonlinearity is less than 0.4%. The possibility of using a hydrogeneous converter in this system for neutron radiography is discussed.

The development and utilization of multiwire coordinate detectors for an express-analysis of labelled compounds in thin layer chromatography

Abstract Characteristics of multiwire position sensitive chambers for an express-analysis of labelled compounds in thin layer chromatography are described. The analysis is characterized by a relatively high detection sensitivity, good data reproducibility and high spatial resolution.

CONSTRUCTION AND TESTING OF THE ALICE TRD CHAMBERS AT LHE, JINR

The current status of construction and testing of Transition Radiation Detectors (TRD) for ALICE at LHE, JINR, is presented. The main purpose of this detector is electron identification at intensive pion background. The whole ALICE TRD system is comprised of 540 wire chambers of total sensitive area ∼750 m2. Each chamber consists of drift and amplifying gaps and a radiator. One hundred such TRD chambers will be constructed at LHE, JINR.

MWPC-Based Automatic Systems for Electronic Autoradiography

Several systems based on multiwire proportional chambers (MWPC) used to study protein mixtures labelled with 3H, 14C, 32P, 35S and 125I are described. The detector operates on-line with a computer. Autoradiography imaging is presented on a colour TV-monitor. The spatial resolution of the systems is 1 … 2 mm, and the sensitivity is about 10 pCi/cm2. The systems make it possible to reduce the analysis time by a factor of 100 as compared to the conventional radiography of protein mixtures without destroying the sample. The high sensitivity of the systems allows the required amount of protein to be decreased by two orders of magnitude.