Nuclear Instruments and Methods最新文献

An account is given of the distortion, noise and resolution characteristics of uniform circular resistive anode encoders operated in the limit of vanishing capacitance.

The effect of the high temperature residual TL (RTL) peak on the sensitization of the dosimetric peak in CaSO₄ : Dy, CaSO₄ : Tm and CaF₂ : Dy phorphors was studied and it was found that the sensitization factor (S/S₀) is dependent on the intensity of the RTL peak. On bleaching the RTL peak intensity by a factor of ∼16 by means of intense UV irradiation (253.7 nm), it was possible to bring down the sensitization factor for CaSO₄ : Dy from a value of 2.6 to 1.0. A similar effect has also been observed in CaSO₄ : Tm and CaF₂ : Dy phosphors. The shape and also the position of the main dosimetric peak is dependent on the intensity of the RTL peak.

An exact expression for a covariance matrix of estimates is obtained in cases of peak fitting with an inadequate model. Estimate biases are discussed.

Elastic spectrum filtering of scattered neutrons is described at the two-dimensional correlation spectrometer on the IBR-30 pulsed reactor in Dubna. Illustrative time-of-flight scattering spectra are shown.

Secondary neutron fluxes were measured around the beam stop bombarded by 500 MeV protons using activation detectors. The attenuation length of concrete was obtained for angles between 0° and 100°. To compare with experimental results, Monte Carlo transport calculations were performed using the NMTC code.

The design of a mass spectrometer capable of determining directly the mass of nuclear reaction products, independent of the velocity with which they leave the target, is discussed. The spectrometer employs only electric and magnetic dipoles and magnetic quadrupoles to focus all particles of a given mass to the same point on the focal plane. The usable solid angle is a function of the mass resolution and can be as large as 5 msr. The magnification of the device is 3.3 which means that the angular convergence of particle paths at the focal plane is very small with the consequence that the focal plane may, without significant loss of resolution be regarded as straight and perpendicular to the particle path in all practical cases. The mass dispersion of the spectrometer is ∼13 mm/% and the resolving power (a function of solid angle) can be as large as m/Δm = 400.

In circular proton accelerators, the synchrotron radiation emitted by high energy beams at the edges of bending magnets contains an appreciable amount of visible light. This effect is used in the CERN SPS to measure by a non interceptive method the transverse proton density distribution above 200 GeV. The device consists of a telescope followed by an image sensor and electronics processing; its performances and some examples of applications are given in this paper.

A scintillator glass (type : SCG1B) detector of 14 × 14 × 40 cm³ gives an energy resolution (fwhm) of $\text{6.5\%/E}{}^{\mathrm{<mtext>-1</mtext><mtext>2</mtext>}}$ for low energy electrons, which is better than for lead glass by a factor approximately 0.6. The light yield for SCG1B is 3.4 times that for lead glass (SF5) if the blocks have similar dimensions. Different surface textures are also compared.

We describe an analogue electronic (ANELEC) ratemeter which has been designed to replace electromechanical ratemeters and to provide a probe-mounted ratemeter display for use with radiation detectors and portable radiation measuring instruments.

The data acquisition speed and electronic stability of a charge division position-sensitive detector may be improved by using digital signal processing with a table look-up high speed multiply to form the charge division quotient. This digitization process introduces a positional quantization difficulty which reduces the detector position sensitivity. The degree of the digitization error is dependent on the pulse height spectrum of the detector and on the resolution or dynamic range of the system analog-to-digital converters. The effects have been investigated analytically and by computer simulation. The optimum algorithm for position sensing determination using 8-bit digitization and arithmetic has a digitization error of less than 1%.