A Wideband spectrometer for NMR studies

The design of a wideband decimeter-wave (200–900 MHz) spectrometer with a magnetic induction of up to ∼10 T is described. This spectrometer is intended for studying electronic-nuclear oscillations in antiferromagnets at low temperatures (4.2−1.3 K). Critical field H _c = 2.5 ± 0.3 T of a reorientation transition in a noncollinear antiferromagnet Mn₃Al₂Ge₃O₁₂ at temperature T ≈ 1.3 K was determined from a ⁵⁵Mn²⁺ NMR spectrum.     

A practical electron spectrometer for chemical analysis

This paper describes the basic parameters which have been considered in the design of a practical electron spectrometer optimized for micro-chemical analysis in a 100 kV transmission electron microscope fitted with a scanning unit. Constructional factors and the operation of this spectrometer are discussed, as well as data acquisition. Typical results are presented to illustrate the operative modes. Both the prototype spectrometer and subsequent copies of it now are being utilized sucessfully in studies related to materials and biological sciences.     

A mass spectrometer for analyzing hydrogen-ion species

The design of a compact, high-resolution 180 degrees magnetic deflection mass spectrometer for the study of positive and negative hydrogen-ion species is described.     

A Rayleigh-Brillouin scattering spectrometer for ultraviolet wavelengths

A spectrometer for the measurement of spontaneous Rayleigh-Brillouin (RB) scattering line profiles at ultraviolet wavelengths from gas phase molecules has been developed, employing a high-power frequency-stabilized UV-laser with narrow bandwidth (2 MHz). The UV-light from a frequency-doubled titanium:sapphire laser is further amplified in an enhancement cavity, delivering a 5 W UV-beam propagating through the interaction region inside a scattering cell. The design of the RB-scattering cell allows for measurements at gas pressures in the range 0-4 bars and at stably controlled temperatures from -30 °C to 70 °C. A scannable Fabry-Perot analyzer with instrument resolution of 232 MHz probes the RB profiles. Measurements on N(2) and SF(6) gases demonstrate that the high signal-to-noise ratio is achievable with the instrument at the 1% level at the peak amplitude of the scattering profile.     

Angle-resolving time-of-flight electron spectrometer for near-threshold precision measurements of differential cross sections of electron-impact excitation of atoms and molecules

This article presents a new type of low-energy crossed-beam electron spectrometer for measuring angular differential cross sections of electron-impact excitation of atomic and molecular targets. Designed for investigations at energies close to excitation thresholds, the spectrometer combines a pulsed electron beam with the time-of-flight technique to distinguish between scattering channels. A large-area, position-sensitive detector is used to offset the low average scattering rate resulting from the pulsing duty cycle, without sacrificing angular resolution. A total energy resolution better than 150 meV (full width at half maximum) at scattered energies of 0.5-3 eV is achieved by monochromating the electron beam prior to pulsing it. The results of a precision measurement of the differential cross section for electron-impact excitation of helium, at an energy of 22 eV, are used to assess the sensitivity and resolution of the spectrometer.     

新型角分辨XPS电子能谱仪

本文介绍了新型角分辨XPS电子能谱的构造、特点,及其应用。     

一种能谱仪重叠峰分峰软件

X射线能谱仪是常用的元素分析仪器之一.但受限于分辨率较差,当样品中的元素存在重叠峰时,能谱仪常常不能做出准确的元素定性分析.本文介绍一种新型的图形化分峰软件,可快速准确地解决重叠峰元素定性分析问题.利用该软件对某电梯轿箱板样品中的有关元素重叠峰进行了分析,即使重叠峰的谱峰位置相差只有3eV,也能清楚识别.     

A spectrometer of polarized neutrons

A polarized neutron spectrometer intended for studies of interactions of nuclei and condensed matter with polarized neutrons with energies in the range from thermal energies to several electron volts was designed at the IBR-2 pulsed reactor (JINR, Dubna). Diffraction on magnetized Co(92%)–Fe(8%) single crystals was used to polarize neutrons and analyze the polarization. The attained neutron polarization was ∼95% within the entire energy range.     

A system of excilamps on xenon dimers for a flow photoreactor

A system consisting of ten excilamps on xenon dimers for a flow photoreactor is designed. The total radiation power at a 172-nm wavelength was ～120 W, when the radiation power density from the excilamp radiator surface was ～15 mW/cm².     

A spectral distortion correction method for an imaging spectrometer

An algorithm for calibration and spectral correction of images obtained with the aid of a spectrometer is proposed and analyzed. Using an acoustooptical microscopic imaging spectrometer as an example, the contribution of individual optical elements of the spectrometer to distortions of spectral images is determined. The accuracy of the algorithm is estimated.     

A detector for the pulsed nuclear quadrupole resonance spectrometer

An increase in the sensitivity of a pulse-type detector for the nuclear quadrupole resonance spectrometer has been attained by optimizing the delay time for switching on the receiver after termination of an excitation pulse and by using an original circuit of the synchronous detector with a high dynamic range of 100 dB. The sensitivity of the nuclear quadrupole resonance spectrometer improved by using the developed detector is about twice as great as the spectrometer sensitivity before its upgrading. The spectrometer is capable of detecting 0.5 g of sodium nitrite.     

A pulsed fourier spectrometer for impedance measurements of electrochemical systems

The facility is intended for measuring the impedance of electrochemical systems by the pulse method. The impedance spectrum is calculated by applying the Fourier transform to the step response (variation in the potential due to sample polarization by a step current pulse). The facility is controlled by a computer and contains a programmable galvanizer and 8-bit parallel ADC with a buffer RAM. Measurements are performed by the two-or three-electrode method over a frequency band of 10⁻³ to 3×10⁵ Hz with samples whose tan (δ) is within 0.01–100. The measurement error is 2%.     

A sectioned spectrometer of fast neutrons

Development of a capture gated spectrometer on the basis of a liquid organic scintillator doped with enriched ⁶Li is discussed. Particular interest is evoked by the good pulse height resolution of the spectrometer for 14-MeV neutrons, which is expected to be very high, ～10–15%. This resolution is attained by compensating for the nonlinearity of the light yield in the scintillator owing to the use of separate optically isolated sections, which independently detect scintillations from each recoil proton. The detector is sensitive to fluence rates ranging from 10^?4 to 10² cm^?2 s^?1 above a threshold of 500 keV under conditions of uncorrelated γ-ray background at a level of up to 10² s^?1 (E > 100 keV). A pilot model of the detector based on a scintillator without a lithium dopant has been produced and tested. The detector efficiency is governed by the scintillator volume (～1.2 l); for 3-MeV neutrons, its value is 0.2–0.5%. The response of the pilot detector to neutrons from a Pu-α-Be source with energies of up to 10 MeV has been measured. Initial testing indicates a low threshold at an ～600-keV energy of a recoil proton. A good spectral response is obtained using the criterion that three optical sections of the detector operate at a time. This spectrometer can find application in low-background experiments in basic physics research, as well as in space research and nuclear medicine for measuring the parameters of the neutron flux.     

A spectrometer for the study of angular correlations in polarized-orthopositronium decay

We describe a setup for experimental testing of the CPT-invariance by observing the angular correlations in the decay of polarized orthopositronium atoms. Annihilation events are detected by five NaI(T1) sensors of 150-mm diameter and 100-mm thickness, located at the vertices of a regular pentagon. The sensor signals are detected in the double-coincidence circuits gated by signals with different time delays from the positron escape. The setup has a time resolution of 8.0 ns. In order to reduce the effect of the long-term instability and the instrumental asymmetry on the experimental results, the direction of positron incidence on a SiO₂ target was reversed with a program-driven period during data acquisition. The value of the asymmetry, measured with due account of statistical and systematic errors, is 0.0008±0.00091, which is twice better as compared with the previous experiment.     

A magnesium vapor charge-exchange target for an accelerator mass spectrometer

The target design and results of experiments aimed at stripping carbon ions in magnesium vapor are presented. It is proposed to substitute such a target for gas targets conventionally used in accelerator mass spectrometers, which will reduce the background ion charge exchange outside the target. Original Russian Text ? V.F. Klyuev, V.V. Parkhomchuk, S.A. Rastigeev, 2009, published in Pribory i Tekhnika Eksperimenta, 2009, No. 2, pp. 101–104.     

A high signal-to-noise ratio toroidal electron spectrometer for the SEM

This paper presents a high signal-to-noise ratio electron energy spectrometer attachment for the scanning electron microscope (SEM), designed to measure changes in specimen surface potential from secondary electrons and extract specimen atomic number information from backscattered electrons. Experimental results are presented, which demonstrate that the spectrometer can in principle detect specimen voltage changes well into the sub-mV range, and distinguish close atomic numbers by a signal-to-noise ratio of better than 20. The spectrometer has applications for quantitatively mapping specimen surface voltage and atomic number variations on the nano-scale.