The counting yield for large volume, complex geometry samples such as solutions in Marinelli beakers as counted on a large
NaI(Tl) detector can be calibrated using radionuclides activated by neutrons form a252Cf source. Calibration may be done by using either a known neutron flux facility or by cross calibration of the activated
material as a point source vs. sealed gamma-standard sources. The point source of activated material is dissolved after cross
calibration to produce the large volume distributed source.
The sensitivity on n-type gamma-X detectors for low-energy X- and -rays calls for coincidence corrections in the efficiency calibration that do not apply to the calibration of p-type detectors. Corrections were calculated for the effect of cascade coincidences between -rays, X-rays, annihilation radiation, and bremsstrahlung, for 15 radionuclides frequently used for efficiency calibration. Experimental results are presented for a -X detector with 37% relative efficiency at distances from 0.9 to 17.5 cm. After coincidence correction smooth efficiency curves were found for the energy range 12 to 2750 keV, even for the position closest to the detector.
Authors:L. López-Martínez, J. Guzmán-Mar, and P. López-de-Alba
A bivariate calibration method, has been applied to the simultaneous determination of U(VI) and Th(IV) ions as complexes with carminic acid by visible absorption spectrophotometry. The bivariate calibration method was applied satisfactorily to the determination of these ions in synthetic solutions simulating sulfuric acid leach solution obtained from uranium-thorium ores and the results were compared with those given by first derivative spectrophotometry. No significant advantages of any method were found.
Authors:R. Lukaszew, H. Bellavigna, R. Cretella, M. Denari, and C. Noutary
A photoplate calibration procedure is suggested for spark source mass spectrometry /SSMS/ with photoplate detection. The technique uses the Churchill two-line method applied to the two stable isotopes of copper. The calibration curve thus obtained is split into fragments and each fragment is approximated by a polynomial. The method was applied for the quantitative determination of Hf as impurity in zirconium sponge obtained from a pilot plant dedicated to the depletion of the hafnium content in zirconium by fractional crystallization.
A new method utilizing a radio-gas chromatographic system, for the calibration of various gas chromatographic columns with
less than 10−12M of tritium-labelled samples is described. The minimum detectable level of3H,38Cl,18F,80mBr,82Br,35S and14C labelled compounds employed for column calibration is discussed. In addition, the relative retention times of nine previously
unpublished alkyl-substituted fluorocyclopropanes on five gas chromatographic columns are given.
A reactor-detector combination has been calibrated for routine determination of trace elements by instrumental neutron activation
analysis using the semi-absolute method with flux corrections. The reproducibility of the calibration constants is studied
using the standard rock AGV-1 for the activities140La,141Ce,153Sm,160Tb,152Eu,175Yb,177Lu,131Ba,60Co,51Cr,134Cs,181Hf,233Pa,46Sc, and182Ta. The results show that a calibration reproducibility with a relative precision of better than 5% can be achieved in many
of the cases without any special precautions. To study the applicability of the calibration constants, concentrations of the
corresponding elements have been determined in standard rocks, G-2, W-1 and GSP-1 and are compared with the recommended values.
Relation between the calibration coefficient of a DSC sensor k(T) and the sensitivity of a thermocouple e(T) which the sensor is made from was derived from the analysis of a heat transfer inside a DSC cell. Ratio e(T)/k(T) is equal to A+BT3. The first component depends on heat conduction and the second one on radiation. The relationship was tested for DSC-204
Netzsch using (i) data on calibration vs. enthalpies of phase transitions (reference samples) and (ii) measurements of heat capacity of corundum. Both tests show very good agreement between experimental data and predicted theoretical
A new method for determination of efficiency calibration curves in -spectrometry is described. From the calibration curves for a bulky sample and a point source, the curves for sources with the same geometrical parameters as the bulky sample but different attenuation coefficients may be calculated. The method was tested at an energy of 88 keV on a set of samples with attenuation coefficients between 0.2 and 2 cm2 g–1. The conditions where the new method is useful are discussed.
DSC measurements in open pans are often disturbed by mass losses such as sublimation during melting or release of water during
chemical reactions. By simultaneous DSC and TG measurements the DSC signal can be corrected. For this purpose, a temperature
dependent calibration function has to be determined by which the SDTA signal from the TGA/SDTA851e measuring cell can be converted into a heat flow curve (DSC).
By this procedure, accurate heat of melting can be determined despite ongoing sublimation in open pans. This method is illustrated
with reference of the melting of anthracene.
Additionally, condensation reactions were investigated and analyzed by DSC/TG even under ambient pressure, knowing the heat
of evaporation. Using phenol formaldehyde resins the influence of the presence or the release of volatile reaction products
on the reaction rate and kinetic parameters were studied.
In general, the method can be used to correct DSC curves for thermal effects related to mass change.
The relative gamma-ray intensities in the energy region between 122 and 411 keV in the decay of152Eu were measured by using a Ge(Li) detector. Its efficiency calibration was carried out with the radioactive sources of241Am,57Co,203Hg,137Cs,133Ba,75Se,169Yb and192Ir.